ELECTROHYDRAULIC VALVE ACTUATOR WITH RECIPROCATING CAM

Abstract

An electrohydraulic valve actuator with cylinder and reciprocating cam includes: a valve-actuating hydraulic cylinder (2) which opens a valve of an internal combustion engine (100) via a valve-opening solenoid valve (4), a valve-opening high-pressure duct (11), and an incoming high-pressure hydraulic circuit (5), and which closes the valve via a valve-closing solenoid valve (6), a valve-closing high-pressure duct (12) and an outgoing high-pressure circuit (7), a hydraulic positive displacement pump (8) cooperating with a pump non-return valve (14) and a pump outlet sealing solenoid valve (13) and the outlet of which is connected to a low-pressure circuit (9) and to a low-pressure reservoir (10) supplied by a replenishing pump (52) and a replenishing reservoir (53).

Description

The present invention relates to an electrohydraulic valve actuator having a cylinder and reciprocating cam for internal combustion engines.

The intake and exhaust valves of reciprocating internal combustion engines open when the crankshaft of these engines reaches a certain angular position. This results from the ordinarily invariable angular position of the camshaft or camshafts of these engines with respect to that of said crankshaft, the latter position being considered over 360 degrees in 2-stroke engines and over 720 degrees in 4-stroke engines such as those conceived by Mr. Nikolaus Otto and Mr. Alphonse Eugène Beau de Rochas.

In order to render variable the moment at which said valves open relative to the angular position of said crankshaft, modern gasoline engines comprise at least one intake camshaft phase shifter and, more and more frequently, an exhaust camshaft phase shifter. These phase shifting devices are generally hydroelectric, sometimes electric, and make it possible to vary the angular position of said shafts in relation to that of the crankshaft.

For most engines produced by the automobile industry, the parameters of opening time, opening speed, and the valve lift height are definitively established by the profile of the cams which actuate said valves. Making these parameters variable is of great interest due to their strong impact on the filling of the cylinders and the quality of combustion. The variability of these parameters is a source of significant improvement in the control of the polluting emissions of these engines. In particular, this variability makes it possible:

• • To improve the filling of the cylinders of the internal combustion engine when it is used at wide-open throttle in order to increase the torque and the power of the engine over its entire engine speed range. This result is obtained by bringing about the opening and closing of the intake and exhaust valves at the most favorable moment for said filling, particularly by taking into account the aerodynamic and acoustic behavior of the gases in the cylinder and in the intake and exhaust ducts of the engine;
  • To reduce pumping losses of the internal combustion engine when it is operating at partial throttle by replacing the winnowing to the intake ordinarily operated by a throttle valve with an appropriate rule for the opening and closing of the intake valve based on two main principles:
    • The first of these strategies consists of reclosing the intake valve quickly during the engine's intake stroke while maintaining the intake duct at a pressure close to atmospheric pressure during that course, in such a manner as to trap in the cylinder of that engine the load of air or desired carbureted mixture, then to expand this air or mixture until the bottom dead center point of the piston of the engine before recompressing this air or mixture in the combustion chamber until the top dead center point of the piston.
    • The second strategy consists of closing the intake valve late during the compression stroke of the engine, the intake duct being maintained at a pressure close to atmospheric pressure during that stroke and a maximum load of air or carbureted mixture being introduced into the cylinder during the intake stroke of the engine, upon which said load is partially forced back into said duct during the compression stroke until the load remaining in the cylinder corresponds to the desired load, at which time the intake is closed again. This latter strategy runs an Atkinson cycle—more effective at partial loads that than that of Otto or of Beau de Rochas—and is of particular interest in variable-compression engines.
  • These strategies for reducing the pumping losses results in a significant improvement of the performance of the engine at partial loads;
  • To improve the stability and the quality of the combustion of the internal combustion engine, particularly by better controlling the turbulence of the gases in the combustion chamber, which is achieved, for example, by finely tuning the lift height of the intake valve. This improved control makes it possible, for example, to improve the homogeneity of the air/fuel mixture of the multipoint injection engine by providing a small lift of the intake valves at low throttle, the effect of which is the generation of finer turbulences when the gases pass through the intake valve, said turbulences being favorable to said homogeneity. This control also makes it possible to adjust the “tumble” movement of the air or the gases in the cylinder, with the effect of transforming this movement into fine turbulence when the piston of the engine arrives at the top dead center point, thus improving the flame propagation during the development of combustion. This control also enables the adjusting of the turbulent movement, or “swirl,” of the air or gases commonly used in Diesel engines, it being possible, for example, to regulate this movement by moving the opening point of the two intake valves of the same cylinder;
  • To reduce both the pumping losses and the heat losses of the internal combustion engine when it is operating at partial throttle by increasing the level of hot residual burnt gases contained in the charge at the time of combustion. These gases do not contain any oxygen and do not participate in the combustion but rather capture the heat released by said combustion, which limits the heat losses at the walls and thus the consumption of fuel. Since they are hot, these gases are voluminous and reduce the volumetric efficiency of the engine with the consequence of reducing the need for the winnowing of the intake duct when it is used at partial throttle. An increase in the level of residual burnt gases is particularly achieved by increasing the overlap of the intake and exhaust valves, which is to say the time during which the intake and exhaust valves of the same cycle are open simultaneously. This enables the piston of the engine to intake fresh gases and burnt gases simultaneously. An increase in the level of residual burnt gases can also be achieved by opening the intake valve early in order to stock up the burnt gases in the duct before reintroducing them into the cylinder during the intake stroke of the engine. As another non-limiting example, an increase in the level of residual burnt gases can also be achieved by closing the exhaust valve early in order to trap the exhaust gases in the cylinder before opening the intake valve. It should be noted that the recycling of the exhaust gas from the preceding cycle in the current cycle is also a strategy which makes it possible to reduce the polluting emissions and, particularly, the sulfur oxides from Diesel engines;
  • To provide a higher compression ratio for the engine when it is at a fixed compression level with the consequence of better average performance of the engine when it is used, for example, to propel an automobile, one of the primary characteristics of which is being used such that the power varies continuously over wide ranges. This is achieved by controlling the effective compression level of the engine by delaying the closing of the intake valve such that, at high loads and low engine speeds, only part of the engine's piston stroke is used to compress the gases, whereas practically the entire stroke of the piston is used to expand those gases. However, according to this strategy, certain operating points of the engine can use practically the entire stroke of the piston both to compress and to expand those gases to the extent that the load and speed conditions of the engine neither produce knocking nor destructive combustion;
  • To improve the performance and the power of turbocharged multi-cylinder engines by preventing or limiting the back-flow of the gases to the exhaust under heavy loads. This is achieved by preventing the exhaust valve, to the greatest extent possible, from opening when the pressure in the cylinder of the engine is less than the pressure in the exhaust manifold of the engine;
  • To improve the performance of multi-cylinder engines when they are used at low power by deactivating one or more cylinder(s) of said engines. This can be achieved by leaving the intake and exhaust valve(s) of the deactivated cylinder(s) closed, the cylinder(s) deactivated in this way operating from a series of compression/expansion that consumes little energy while the cylinders that have remained active provide better performance because they are operating at a higher load. It should be noted that, according to this strategy, it is possible to insert inactive cycles into a series of active cycles of the same cylinder so as to obtain smoother operation of the internal combustion engine, in which case each cylinder is only deactivated part of the time that the engine is in operation, whereas that cylinder functions normally the rest of the time;
  • To improve the efficiency of 2-stroke internal combustion engines by optimizing the scavenging of burnt gases by intake air performed at the end of the stroke for expanding those gases. This is achieved by optimizing the opening and closing points of the intake and exhaust valves in relation to the angular position of the crankshaft of these engines so as to trap the desired air charge in the cylinder(s) of the engines, and to preserve the desired quantity of residual burnt gases in the cylinders. This strategy potentially makes it possible to avoid using an intake and/or exhaust opening, as said opening is associated with various drawbacks for the functioning and architecture of these engines;
  • To improve the efficiency of the devices for the aftertreatment of pollutants from internal combustion engines, whether it be a 2- or 3-way catalyst or a particle filter. Since these devices do not function at wide-open throttle and/or are only regenerated starting at a certain temperature, an early opening of the exhaust valves of these engines makes it possible to shorten the expansion of the gases so as to exert less pressure on the piston of these engines in order to increase the temperature of their exhaust gases. This strategy particularly makes it possible to accelerate the rise in operating temperature of these devices and/or to give them the heat energy necessary for their regeneration;
  • To facilitate the designing of the combustion chamber of reciprocating internal combustion engines by making it possible to reduce the depth of the recesses ordinarily provided on the seal of the pistons of these engines, or even to eliminate said recesses, as their function is to prevent any collision between the pistons and the valves of these engines. This is achieved by deliberately reducing the lift height of the valves of these engines when the compression ratio thereof is high, which generally corresponds to the operation of these engines at partial throttle;

Various technologies make it possible to completely or partially control the time of opening, the duration of opening and the lift height of the valves of reciprocating internal combustion engines. Camshaft phase shifters are industrialized and tend to be widely used, but they control neither the duration of opening nor the lift height of these valves. However, these phase shifters are associated more and more frequently with devices which render variable the lift height of these valves.

These devices are marketed under various brands and/or trade names. These are discrete valve lift height variators comprising at least two cam profiles and continuous lift variators.

Among the discrete lift variators, one finds, in particular, the device “VTec®” from the Honda company, the “Variocam Plus®” from the Porsche company, the “Valvelift system” from the Audi company, as well as the “VVTL-i” from the Toyota company.

Among the continuously variable valve lift height variators, one finds the “Valvetronic®” developed by the BMW company and based on a variable-ratio lever, or the “Multiair®” from the FIAT company, which provides a hydraulic transmission between the cam and the valve lifter with a solenoid valve for returning the used hydraulic fluid to the reservoir, thus making it possible to shorten the lift of the valve to a greater or lesser extent.

It should be noted that the variable valve lifting devices are used most frequently in intake valves and, in rare cases, in exhaust valves. These devices generally only fit out one of the engine's camshafts, i.e., either the intake valve or the exhaust valve, primarily for reasons relating to cost or clutter.

We note that when they are used in mass-produced passenger cars, these devices are always reliant on at least one camshaft, so their performance depends directly on the profile of the cams making up said shaft.

It would obviously be advantageous to overcome the constraint introduced by the cam profile. This is the aim of so-called “camless” devices. In theory, these devices can implement any rule whatsoever pertaining to the opening, lifting and closing of the valves within the limits imposed by physics and geometry.

There are numerous camless devices in the prototype phase such as the “electromagnetic camless” from the Valeo company, the “Free Valve” from the Cargine company, the hydro-electric device developed by the American company Sturman in collaboration with the Siemens company, or “Active Valve Train (AVT™)” from the Lotus company.

In most cases, these systems are associated with excessive or even prohibitive energy consumption and/or acoustic emissions and/or clutter and/or cost.

Other drawbacks or limits associated with these devices prohibit or defer them from being produced on an industrial scale, such as reliability and/or durability that is difficult to guarantee over the entire service life of an automobile and/or potentially insufficient controllability, which may lead to the perturbation of the valves at high speeds, and/or a lack of progressivity when the valves are at rest in their seat and/or operation in ballistic mode which leads to opening rules that are difficult to control.

These observations are at the root of international patent WO 2004/011780 belonging to the applicant, which describes a “camless” hydraulic actuator enabling control of the lift, the Advance to Opening and/or the Delay of the Closing of the valves of reciprocating internal combustion engines. This actuator potentially enables the implementation of the majority of strategies for increasing the power and performance of internal combustion engines as well as those enabling better control of the polluting emissions of said engines.

Moreover, in relation to this actuator, this patent claims reliability and production cost that are potentially compatible with the specifications of an internal combustion engine for mass-produced automobiles. Particularly, this actuator comprises:

• • at least one hydraulic cylinder linked to a high-pressure hydraulic circuit by a duct and providing for the opening of at least one valve;
  • at least one hydraulic positive displacement pump comprising at least one outlet and one inlet and the rotational speed of which is proportional to that of the crankshaft of the engine;
  • at least one pump outlet closure member which makes it possible to prevent the hydraulic fluid expelled from the outlet of the hydraulic positive displacement pump to go into a low-pressure circuit or into a reservoir and to force it to go toward a high-pressure circuit communicating with one or more hydraulic cylinder(s) providing for the opening of one or more valves;
  • at least one valve opening selector which makes it possible to direct, via the high-pressure circuit, the hydraulic fluid expelled at the outlet of the hydraulic positive displacement pump toward the hydraulic cylinder of at least one valve needing to be opened, all while preventing said hydraulic fluid from being directed toward one or more other valves needing to remain closed;
  • at least one opening non-return valve placed on the high-pressure circuit between the pump outlet and the hydraulic cylinder of at least one valve which enables the retention of the hydraulic fluid in said hydraulic cylinder of said valve in order to keep it open;
  • at least one valve closing selector which makes it possible to direct the hydraulic fluid contained in the hydraulic cylinder from at least one valve kept open by the opening non-return valve toward the inlet or inlets of the hydraulic positive displacement pump in order to provide for the closing of the valve(s), and to prevent the hydraulic fluid contained in its hydraulic cylinder from being introduced into the hydraulic cylinder of another valve or of other valves needing to remain in the closed position;
  • and at least one pump inlet anti-return valve which enables the hydraulic fluid from the low-pressure circuit or from the reservoir to be let into the inlet or inlets of the hydraulic positive displacement pump when the pressure of the low-pressure circuit or of the reservoir is greater than that of the inlet or inlets of the low-pressure.

Despite these potential advantages, the hydraulic valve actuator for internal combustion engine described in international patent WO 2004/011780 belonging to the applicant has various limits and drawbacks, including:

• • It is not possible to simultaneously obtain a valve opening rule for a cylinder that is different from that of another cylinder of the same internal combustion engine, so it is not possible, for example, to deactivate the valves of one of the cylinders of the engine;
  • It is not possible to provide more than one lift per engine cycle for the same valve or to go from a 4-stroke cycle to a 2-stroke cycle;
  • The hydraulic cylinders of the valves of the internal combustion engine attack the valves directly, the lifting of these valves produces violent a water hammer in the ducts of the actuator, since the pressure surges suddenly in these ducts when the cylinders are put on circuit with the hydraulic positive displacement pump of the actuator, this water hammer resulting from the inertia of the valves, which leads to significant acceleration forces, these forces being increased by the opposing force produced by the return spring of the valves;
  • It is difficult to have the valves of an internal combustion engine rest gently on their seat due to a constant relationship between the outlet of the hydraulic pump of the actuator and the opening and closing speed of the valves. This can potentially lead to excessive acoustic emissions resulting from the impact produced between the valves and their seat as well as to premature wearing of the seat and of the valves;
  • The ducts that connect the actuator to the hydraulic cylinders that open and close the valves are very long and contain a significant volume of oil which is compressed and then decompressed upon each operation of the valves. This may lead to the valves having an unstable position and being difficult to control;
  • The actuator has a certain complexity of design due to the multitude of precise parts of which it is composed, and this complexity and parts can potentially lead to the actuator having a high production cost;
  • The actuator requires precise electric motors in order to guide the position of its forks for lifting, advancing to opening, and delaying of closing of the valve(s) in a proportional manner. These complex motors are potentially expensive.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the invention stands out from the valve drive devices known from the prior art in that it inherits advantages of the hydraulic valve actuator for internal combustion engine as described in international patent WO 2004/011780 belonging to the applicant while eliminating the drawbacks thereof and pushing aside the functional limits thereof by means of an embodiment and means used which are radically different.

Consequently, the electrohydraulic valve actuator according to the invention:

• • makes it possible to simultaneously provide a valve opening rule for a cylinder of the internal combustion engine that is different from that of another cylinder of the engine;
  • makes it possible to provide an opening rule for an intake or exhaust valve of a cylinder of the internal combustion engine that is simultaneously different from that of another valve of the same cylinder having the same function of either intake or exhaust;
  • enables the deactivation of the valves of one or more cylinders of the same internal combustion engine;
  • allows for several lifts of the same valve per engine cycle;
  • enables the same internal combustion engine or any of the cylinders of the same internal combustion engine to execute a 2-stroke or a 4-stroke cycle equally well;
  • prevents or strongly attenuates water hammers in the ducts of the actuator by reducing the inertial forces generated by the parts attacked directly by the hydraulic cylinder and by providing a progressivity of lifting and lowering of the valves of the internal combustion engine, resulting in a reduction of the noise and of the positional instabilities of the valves;
  • enables the valves of the internal combustion engine to rest gently on their seat, thus preventing any excessive acoustic emissions and any premature wear of the seats and/or of the valves;
  • strongly reduces the effects of the compressibility of oil on the stability of the position of the valves of the internal combustion engine;
  • has significantly reduced cost and complexity.

The other features of the present invention have been described in the description and in the secondary claims depending directly or indirectly on the main claim.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises:

• • at least one valve-actuating hydraulic cylinder which comprises at least one valve-actuating piston which opens at least one valve of an internal combustion engine or of a piston compressor when the cylinder is connected by a valve-opening solenoid valve to at least one incoming high-pressure hydraulic circuit, said cylinder closing said valve when it is connected by a valve-closing solenoid valve to at least one outgoing high-pressure circuit, and said cylinder maintaining said valve open when it is connected neither to the incoming high-pressure circuit nor to the outgoing high-pressure circuit;
  • at least one hydraulic positive displacement pump comprising at least one outlet connected to a low-pressure circuit connected to at least one low-pressure reservoir and at least one inlet connected to said low-pressure circuit, said pump rotating at a speed proportional to that of a crankshaft of the internal combustion engine;
  • at least one high-pressure valve-opening duct connecting the outlet of the hydraulic positive displacement pump to the incoming high-pressure hydraulic circuit of the valve-actuating hydraulic cylinder;
  • at least one valve-closing high-pressure duct connecting the inlet of the hydraulic positive displacement pump to the outgoing high-pressure hydraulic circuit of the valve-actuating hydraulic cylinder;
  • at least one pump outlet closure member which is able to prevent the hydraulic fluid expelled at the outlet of the hydraulic positive displacement pump from returning to the low-pressure hydraulic circuit, so that said fluid is forced into the high-pressure valve-opening duct;
  • at least one pump inlet non-return valve which prevents the hydraulic fluid coming from the valve-actuating hydraulic cylinder via the high-pressure valve-closing duct from returning directly to the low-pressure hydraulic circuit, so that said fluid is forced to the inlet of the hydraulic positive displacement pump while said valve enables the pump to intake the fluid contained in the low-pressure hydraulic circuit when the pressure of the latter is greater than the pressure in the valve-closing high-pressure duct;
  • at least one valve-opening cam connected on the one hand to the valve-actuating hydraulic cylinder by a mechanical transmission and on the other hand to the valve of the internal combustion engine either directly or through an intermediate transmission, said cam moving in one direction during the opening operations of the valve, then in the opposite direction during the closing operations of the valve;
  • at least one return spring of the valve-opening cam which tends to return the cam into the position it is in when the valve of the internal combustion engine is closed;

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve-actuating hydraulic cylinder which rotates and a valve-actuating piston which is pallet-shaped, said piston separating at least one high-pressure chamber from at least one low-pressure chamber such that the pressure of the hydraulic fluid can rotate the piston, said piston being rotationally connected either directly or indirectly to the valve-opening cam.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve-actuating piston which can move in a cylinder and push on a valve-opening rack guided in a cylinder head contained in the internal combustion engine or the piston compressor, said rack cooperating with a pinion arranged on an axis of the valve-opening cam so as to rotate said cam when the piston moves in longitudinal translation.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve-opening rack that is guided in the cylinder head of the internal combustion engine by at least one ball or roller bearing.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve-actuating piston which moves in a cylinder and pushes a valve-opening rod to one of the ends of which it is joined, said rod pushing, in turn, on a cam arm comprised directly or indirectly by the valve-opening cam to which the other end of the rod is also joined so as to rotate the cam when the piston moves in longitudinal translation.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve-opening rod which is hinged at at least one of its two ends by means of an open or closed ball-and-socket joint.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a hydraulic positive displacement pump comprising several compartments, each of which constitutes an autonomous pump comprising at least one inlet and at least one outlet connected to at least one valve-actuating hydraulic cylinder, said autonomous pumps being rotated by the same cam and being housed in the same casing.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a position sensor on the valve of the internal combustion engine.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a cam angular position sensor on the valve-opening cam.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve-opening cam which cooperates with a cam stop limiting the maximum angular position of the cam when the valve of the internal combustion engine actuated by said cam is closed.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a cam stop which is mounted on a shock absorber or which comprises a shock absorber limiting the acoustic emissions when said cam comes into contact with the cam stop.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve-opening cam which comprises two open or closed joints and a cam leverage contact surface, the first joint being fixed to the internal combustion engine whereas the second is connected to the valve-actuating piston either directly by means of a piston follower or indirectly by means of a push rod, said cam being able to roll and/or slide on a surface of a contact of a rocker switch arranged on a rocker switch breaker arm is hinged at one of its ends on at least one breaker arm anchorage fixed to the engine and equipped at its other end with at least one breaker arm follower which can push either directly or indirectly on a tail of at least one valve of the engine for opening said valve.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a ball-and-socket joint on at least one of the two open or closed joints.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a push rod which is hinged at each of its ends on a ball-and-socket joint, the first joint being arranged in or at the end of the valve-actuating piston whereas the second ball-and-socket joint is arranged in or on the valve-opening cam.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve-opening cam which comprises a cam leverage contact surface and is rotated by means of at least one rotation arm one of the ends of which is fixed to the axis of the cam whereas the other end thereof is hinged by means of a pivot joint or a ball-and-socket joint with the first end of an arm push rod, the second end of the rod being hinged by means of a pivot joint or a ball-and-socket joint with the valve-actuating piston and the cam being able to roll and/or slide on a rocker switch contact surface arranged on a rocker switch breaker arm hinged at one of its ends on at least one breaker arm anchorage fixed to the internal combustion engine and equipped at its other end with at least one breaker arm follower that can push directly or indirectly on a tail comprised by at least one valve of the engine for opening said valve.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve-actuating piston which moves in a cylinder equipped with an end-position shock-absorbing opening that is closed in whole or in part by said piston when the piston arrives near the position it is in when the valve of the internal combustion engine that it actuates is closed.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve-actuating piston which moves in a cylinder equipped with a piston end-position stop, the latter limiting the depth of insertion of the piston in the cylinder.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a low-pressure reservoir which is comprised of at least one compensating pressure accumulator that is kept under pressure by at least one replenishing pump which supplies the accumulator with hydraulic fluid by suctioning the fluid into at least one replenishing reservoir.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve-opening solenoid valve and/or valve-closing solenoid valve and/or pump outlet sealing solenoid valve which is a tube solenoid valve comprised of at least one rectilinear tube that can move in longitudinal translation in a valve casing comprising an upper chamber and a lower chamber, said rectilinear tube comprising a first end leading into the upper chamber and a second end leading into the lower chamber, said second end being able to come into contact with at least one sealing surface fixed to the valve casing so as to seal the second end as tightly as possible.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a tube solenoid valve comprising sealing means between the outer surface of the valve casing which isolates the upper chamber from the lower chamber.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a tube solenoid valve comprising at least one closing spring which tends to maintain the rectilinear tube in contact with the sealing surface.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a tube solenoid valve comprising at least one electrical actuator capable of applying a force opposite that produced by the closing spring, said force being sufficient to lift the rectilinear tube from the sealing surface when an electric current passes through said actuator.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a tube solenoid valve the electrical actuator of which is comprised of a coil of conductive wire which attracts a magnetic core or pallet when an electric current passes through said coil.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises an electrical actuator the magnetic coil or pallet of which is housed in the upper chamber.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises an electrical actuator whose coil of conductive wire is housed in the upper chamber.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises an electrical actuator whose coil of conductive wire is housed on the exterior of the upper chamber, the magnetic field generated by said coil when an electrical current passes through it passing through the external wall of said chamber so as to exert a force on the magnetic core or pallet.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a tube solenoid valve the first end of which rectilinear tube is fixed to the magnetic core or pallet.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a rectilinear tube the first end of which comprises at least one radial and/or axial opening leading into the upper chamber.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a rectilinear tube the second end of which has the shape of a truncated sphere and has a line of contact with the sealing surface similar to that made by a ball resting on a seat.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a sealing surface which is arranged on an independent floating mounted part in the valve casing, said part being able to align with the rectilinear tube when the second end of said tube comes into contact with said surface.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve casing comprising either directly or indirectly via an intermediate plug, a vent which is closed by the independent part on which the sealing surface is arranged.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve casing which is fixed to the internal combustion engine and which comprises inland/outlet openings and/or ducts connecting the upper chamber and/or lower chamber either to the valve-actuating hydraulic cylinder or to hydraulic positive displacement pump via the incoming high-pressure hydraulic circuit, the outgoing high-pressure circuit or the low-pressure hydraulic circuit.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a rectilinear tube whose section at the seal that said tube constitutes with the valve casing is slightly smaller than the section of said tube at the level of its contact with the sealing surface.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a tube solenoid valve whose sealing means are comprised of the external surface of the rectilinear tube which cooperates with the internal surface of the valve casing.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a tube solenoid valve provided with an adjustable or non-adjustable stop which is arranged on the rectilinear tube and which cooperates with an axial stop surface arranged directly or indirectly in the valve casing, said stop determining the maximum distance between said tube and the sealing surface with which it cooperates.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve casing which can house several tube solenoid valves.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a replenishing pump comprising a replenishing piston which can move in a back-and-forth motion in a blind-end cylinder arranged in a blind-end cylinder housing so as to define a variable volume on the interior of said cylinder, said piston also cooperating with a replenishing inlet valve and a replenishing outlet valve, whose respective outlet and inlet lead into said volume, said inlet valve letting in hydraulic fluid coming from the replenishing reservoir, whereas the outlet valve expels said fluid into the compensating pressure accumulator or into the replenishing pressure accumulator.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a replenishing pump whose replenishing piston is actuated in translation in a first direction by an electric solenoid actuator comprised primarily of a replenishing magnetic core, a coil of conductive wire, and a replenishing magnetic casing, and in a second direction by a return spring of the replenishing piston.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a replenishing pump whose blind-end cylinder is embodied in the same metallic part as the replenishing magnetic casing.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a replenishing pump whose blind-end cylinder comprises a jacket in which the replenishing piston moves.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a replenishing pump whose blind-end cylinder comprises an end-position delivery opening which connects said cylinder to the replenishing outlet valve such that the replenishing piston covers said opening at the end of the delivery stroke and is slowed and then stopped in its delivery stroke.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a replenishing pump whose maximum stroke is limited in the delivery direction by a delivery stop and/or in the suction direction by a suction stop.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises an electric solenoid valve actuator whose replenishing magnetic coil is traversed by the replenishing piston on which it is rigidly mounted, said piston traversing the replenishing magnetic casing from end to end in order to cooperate on one side of said casing with the blind-end cylinder and on the other side of said casing with the return spring of said piston.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a replenishing pump which comprises a replenishing tubular piston which can undergo back-and-forth movements in an open cylinder arranged in an open cylinder casing which is directly or indirectly integral with a pump casing such that said piston, said cylinder and said pump casing define together a variable volume on the interior of said cylinder, said replenishing tubular piston cooperating with a tubular piston inlet valve comprised of a ball and a spring, said ball resting on a seat arranged at the bottom and on the interior of said piston and an open cylinder outlet valve comprised of a ball and a spring, said ball resting on a seat arranged on the bottom and on the exterior of said cylinder, said inlet valve letting in hydraulic fluid coming from the replenishing reservoir, whereas the outlet valve expels said fluid into the compensating pressure accumulator or into the replenishing pressure accumulator.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises an open cylinder casing which comprises a hydraulic fluid delivery duct connecting, either directly or indirectly, the tubular piston inlet valve to a pump inlet opening comprised by the pump casing.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a pump casing which comprises a hydraulic fluid outlet duct connecting, either directly or indirectly, the open cylinder outlet valve to a pump outlet opening comprised by the pump casing.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a replenishing tubular piston which is actuated in translation in a first direction by an electric solenoid valve actuator primarily comprised of a replenishing magnetic core fixed to the piston, a coil of conductive wire, and a replenishing magnetic casing, and in a second direction by a return spring of the replenishing tubular piston.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a replenishing magnetic core which is provided with at least one core channel connecting the hydraulic fluid delivery duct indirectly to the center of the replenishing tubular piston via the tubular piston inlet valve, said open cylinder casing, said core and said piston being commonly housed on the interior of a tight casing, whereas said casing delivers the hydraulic fluid from the duct to said channel.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a replenishing reservoir which is supplied with hydraulic fluid by the lubricating oil of the internal combustion engine.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a replenishing reservoir which contains a specific hydraulic fluid and is independent from the lubricating oil circuit of the internal combustion engine.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve-actuating hydraulic cylinder comprising at least one drain which recovers the hydraulic fluid escaping from said cylinder, so that said fluid returns to the replenishing reservoir via at least one cylinder draining duct.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a hydraulic positive displacement pump comprising at least one drain which recovers the hydraulic fluid escaping from said pump, so that the fluid returns to the replenishing reservoir via at least one pump draining duct.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises one or more drain cocks placed on the hydraulic cylinder and/or on the hydraulic positive displacement pump and/or at any point in the incoming high-pressure hydraulic circuit and/or of the outgoing high-pressure hydraulic circuit and/or of the low-pressure hydraulic circuit.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve-opening cam which is a wedge-shaped slide that can be translated under the action of the valve-actuating hydraulic cylinder in a guide or a slide arranged in the cylinder head of the internal combustion engine such that the wedge shape of said slide creates a local variation in thickness that makes it possible to lift the valve of the internal combustion engine from its seat or to deposit it therein.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a guide or slide comprising at least one roller on which the wedge-shaped slide rolls.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a wedge-shaped slide which cooperates with an rocker switch breaker arm hinged at one of its ends on at least one breaker arm anchorage fixed to the internal combustion engine and equipped at its other end with at least one breaker arm follower which can push directly or indirectly on the tail comprised by the valve of said engine for opening said valve.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve-opening cam which is comprised of a cam pin hinged at one of its ends on an axis and which comprises at its other end a tangential lifting surface, said surface having a shape which is such that it exerts a thrust with respect to said axis onto a rocker switch breaker arm with roller when the cam pin turns on said axis under the action of the valve-actuating hydraulic cylinder, and the breaker arm itself being hinged at one of its ends on at least one breaker arm anchorage fixed to the engine and being equipped at its other end with at least one breaker arm follower so as to enable it to push directly or indirectly on a tail comprised by the valve of said engine in order to open said valve.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a mechanical transmission connecting the cam pin to the valve-actuating hydraulic cylinder that is comprised of a push rod comprising at each of its two ends a pivoting and/or ball-and-socket joint, the first end resting on or in the valve-actuating piston, whereas the second end rests on the body of the cam pin.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a cam pin return spring which is comprised of at least one helicoidal spring which exerts a force opposite that of the valve-actuating piston and which tends to move the two pivoting and/or ball-and-socket joints from each other which are guided with respect to each other by at least one sliding connection, the first joint resting directly or indirectly on the internal combustion engine, whereas the second joint rests on the body of the cam pin.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a tangential lifting surface which ends at a stop that can come into contact with the roller rocker switch breaker arm so as to limit the angular movement of the cam pin.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises at least one replenishing pressure accumulator which is inserted between the replenishing pump and the compensating pressure accumulator.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a replenishing pressure accumulator the outlet of which comprises a lockout valve.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a replenishing pressure accumulator which is connected to the compensating pressure accumulator by a duct comprising at least one non-return valve, said valve permitting the hydraulic fluid to go from the replenishing pressure accumulator compensating pressure accumulator and not vice versa.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises a valve-opening high-pressure duct which comprises at least one pressure maintenance valve positioned at its end nearest the hydraulic positive displacement pump, said valve permitting the hydraulic fluid coming from said pump to penetrate into said duct but not to emerge from it.

The electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine according to the present invention comprises at the outlet of the hydraulic positive displacement pump a low-pressure reservoir non-return valve positioned between said outlet and the pump outlet sealing solenoid valve, said valve permitting the hydraulic fluid to go from the outlet of the hydraulic positive displacement pump to said low-pressure reservoir, but not vice versa.

The function of the electrohydraulic valve actuator with cylinder and reciprocating cam is:

• • to force the hydraulic fluid delivered to the outlet of the hydraulic positive displacement pump in the valve-actuating hydraulic cylinder of at least one valve of the thermal internal combustion engine in order to lift said valve progressively at the desired moment and for the time necessary to lift said valve to the desired height;
  • then,
  • to keep the hydraulic fluid confined in the valve-actuating hydraulic cylinder of said valve in order to keep said valve open for the desired time, said time being expressed in number of degrees of crankshaft rotation of said engine;
  • then,
  • to force the hydraulic fluid contained in the valve-actuating hydraulic cylinder of said valve into the inlet of the hydraulic positive displacement pump such that said valve rests softly on its seat at the desired moment, all while recovering the majority of the mechanical energy stored by the return spring of said valve during the opening thereof, and the majority of the kinetic energy stored by said valve, by said spring and by the mechanical components which combine to actuate said valve during its closing stroke.

According to one specific embodiment, the electrohydraulic valve actuator with cylinder and reciprocating cam according to the invention also comprises:

• • at least one cam position sensor and/or at least one valve position sensor;
  • at least one electronic control unit which controls the different solenoid valves of said actuator;
  • at least one sensor which measures the angular position of the crankshaft of the engine, which position is taken into account by the electronic control unit in order to control the valve-opening solenoid valves, the valve-closing solenoid valves and the pump-sealing solenoid valves such that the actual position of the valve measured by the cam angular position sensor and/or the valve position sensor for each angular position of the crankshaft matches well with the actual opening, the lift height and the closing point desired for the valve(s) in question, these different sensors, the electronic control unit and its various solenoid valves realizing a closed-loop control of the position of the valves.

The description to follow with reference to the enclosed drawings, provided as non-limiting examples, will facilitate better understanding of the invention, the features it presents, and the advantages which it is capable of providing:

FIG. 1 shows a schematic diagram of the electrohydraulic valve actuator with cylinder and reciprocating cam according to the present invention such as can be provided in order to actuate only one of the valves of a reciprocating internal combustion engine.

FIG. 2 shows a schematic diagram of the actuator according to the invention such as can be provided in order to actuate the eight intake or exhaust valves of a reciprocating internal combustion engine with four cylinders and with four valves per cylinder, each group of two valves of the same cylinder being actuated by the same valve-actuating hydraulic cylinder.

FIG. 3 shows a schematic diagram of the actuator according to the invention such as can be provided in order to actuate the eight intake valves and the eight exhaust valves of a four-cylinder engine having four valves per cylinder, each group of two valves of the same cylinder being actuated by the same valve-actuating hydraulic cylinder.

FIG. 4 is a sectional schematic view of a sample installation on a reciprocating internal combustion engine of the actuator according to the invention.

FIG. 5 is an exploded view of the hydraulic positive displacement pump of the actuator according to the present invention when, according to one specific embodiment, said pump is compartmentalized so as to constitute several autonomous pumps driven by the same shaft and housed in the same casing.

FIG. 6 is a schematic sectional view of the valve-opening cam, of the valve-actuating hydraulic cylinder, and of the mechanical transmission between said cylinder and said cam of the actuator according to the present invention when, according to one specific embodiment, said transmission is a rack cooperating with a pinion fixed to the axis of said cam.

FIG. 7 is a schematic sectional view of the valve-opening cam, of the valve-actuating hydraulic cylinder, and of the mechanical transmission between said cylinder and said cam of the actuator according to the present invention when, according to one specific embodiment, said transmission is a valve-opening rod hinged on one cam arm comprised by said cam.

FIG. 8 is a schematic sectional view of the valve-opening cam, of the valve-actuating hydraulic cylinder, and of the mechanical transmission between said cylinder and said cam of the actuator according to the present invention when, according to one specific embodiment, said cam takes the form of a wedge-shaped slide which can translate between a roller slide and a roller-type breaker arm.

FIG. 9 is a schematic sectional view of the valve-opening cam according to the present invention when, according to one specific embodiment, it is actuated by a rotating hydraulic cylinder mounted directly on the axis of said cam, the mechanical transmission between said cylinder and said cam being comprised by said axis.

FIGS. 10 and 11 are schematic sectional views of the open valve and closed valve, respectively, of the valve-opening cam, of the valve-actuating hydraulic cylinder, and of the mechanical transmission between said cylinder and said cam of the actuator according to the invention when, according to one specific embodiment, said cam comprises two open or closed joints and a cam leverage contact surface, and said cam cooperates with a rocker switch breaker arm.

FIG. 12 is a schematic sectional view of a variant of the components of the actuator represented in FIGS. 10 and 11 which differs in that the valve-opening cam is rotated by means of a rotating arm one of the ends of which is fixed to the axis of said cam and which cooperates with an arm push rod, which transfers to it the force produced by the valve-actuating piston.

FIG. 13 is a schematic sectional view of the valve-opening cam, of the valve-actuating hydraulic cylinder, and of the mechanical transmission between said cylinder and said cam of the actuator according to the present invention, said cam being comprised of a cam pin hinged at one of its ends on an axis, its other end comprising a tangential lifting surface cooperating with a roller-type rocker switch breaker arm.

FIGS. 14 and 15 are schematic sectional views of the valve-opening solenoid valve and/or the pump outlet sealing solenoid valve according to the present invention when it takes the form of a tube solenoid valve according to one specific embodiment, in closed position (FIG. 14) and in open position (FIG. 15), respectively.

FIG. 16 is a schematic sectional view of the replenishing pump according to the present invention and according to one specific embodiment providing a blind-end cylinder.

FIG. 17 is a schematic sectional view of the replenishing pump according to the present invention and according to a second specific embodiment providing a replenishing tubular piston.

FIGS. 18 to 20 are exploded three-dimensional views of the replenishing pump according to the present invention and according to the embodiment as shown in FIG. 17.

FIG. 21 shows a schematic diagram of the electrohydraulic valve actuator with cylinder and reciprocating cam according to the present invention such as can be provided in order to actuate only one of the valves of a reciprocating internal combustion engine, the pump inlet non-return valve being replaced by a pump inlet solenoid valve mounted parallel to a pump inlet pressure limiter.

FIGS. 1 to 4 show an electrohydraulic valve actuator with cylinder and reciprocating cam 1 for internal combustion engine 100.

The electrohydraulic valve actuator 1 comprises at least one valve-actuating hydraulic cylinder 2 comprising at least one valve-actuating piston 3 which opens at least one valve 101 of the internal combustion engine 100 or of a piston compressor when said hydraulic cylinder 2 connected by a valve-opening solenoid valve 4 to at least one incoming high-pressure hydraulic circuit 5.

Said hydraulic cylinder 2 closes said valve 101 when it is connected by a valve-closing solenoid valve 6 to at least one outgoing high-pressure circuit 7.

Said hydraulic cylinder 2 ensures that said valve 101 remains open when it is connected neither to the incoming high-pressure circuit 5 nor to the outgoing high-pressure circuit 7.

The incoming high-pressure hydraulic circuits 5 and outgoing high-pressure hydraulic circuits 7 may comprise an inherently known flow divider in order to divide the flow to or from several valve-actuating hydraulic cylinders 2.

The electrohydraulic valve actuator 1 comprises at least one hydraulic positive displacement pump 8 comprising, on the one hand, at least one outlet connected to a low-pressure hydraulic circuit 9 connected to at least one low-pressure reservoir 10 and, on the other hand, at least one inlet connected to said low-pressure hydraulic circuit 9.

The low-pressure reservoir 10 is comprised of at least one compensating pressure accumulator 51 kept under pressure by at least one replenishing pump 52 which supplies said accumulator 51 with hydraulic fluid by suctioning said fluid into at least one replenishing reservoir 53.

Note that the compensating pressure accumulator 51 may be embodied with a membrane, a piston or be of any other type known to a person skilled in the art, and it can be housed in the casing 35 of the hydraulic positive displacement pump 8 and has, particularly, the function of limiting the effects of the compressibility of the hydraulic fluid on the functioning of the actuator 1 according to the invention on the one hand and of preventing any cavitation phenomena on the interior of said actuator on the other hand.

Note that the hydraulic positive displacement pump 8 rotates at a speed proportional to that of a crankshaft 102 comprised by the internal combustion engine 100.

The hydraulic positive displacement pump 8 can have a fixed cylinder or a variable cylinder, internal gears or external gears, piston(s), screw(s) or palette(s).

The hydraulic positive displacement pump 8 can be fixed on the internal combustion engine 100 and can be driven by the crankshaft 102 of said engine by at least one pinion or at least one chain or by at least one belt or by means of a fixed-ratio or variable-ratio transmission.

The driving of the hydraulic positive displacement pump 8 by said crankshaft 102 can occur solely by mechanical means or electrically as well by means of an alternator which drives an electric motor driving said pump. The electrical energy produced by said alternator can be stored previously in a battery or not, and the low-pressure hydraulic circuit 9 may comprise a pressure sensor which returns the value of the pressure prevailing in said circuit to an electronic control unit.

The electrohydraulic valve actuator 1 comprises at least one valve-opening high-pressure duct 11 connecting the outlet of the hydraulic positive displacement pump 8 to the incoming high-pressure hydraulic circuit 5 of the valve-actuating hydraulic cylinder 2.

The electrohydraulic valve actuator 1 comprises at least one valve-closing high-pressure duct 12 connecting the inlet of the hydraulic positive displacement pump 8 to the outgoing high-pressure hydraulic circuit 7 of the valve-actuating hydraulic cylinder 2.

The electrohydraulic valve actuator 1 comprises at least one pump outlet sealing solenoid valve 13 which is capable of preventing the hydraulic fluid expelled at the outlet of the hydraulic positive displacement pump 8 from returning to the low-pressure hydraulic circuit 9, so that said fluid is forced into the valve-opening high-pressure duct 11.

According to one specific embodiment of the electrohydraulic valve actuator 1, a pressure limiter 144 can be mounted parallel to the pump outlet sealing solenoid valve 13, said limiter permitting the hydraulic fluid to pass directly from the outlet of the hydraulic positive displacement pump 8 to the low-pressure reservoir 10 without passing through said solenoid valve when the pressure difference at the ends of said solenoid valve exceeds a certain value.

The electrohydraulic valve actuator 1 comprises at least one pump inlet non-return valve 14 which prevents the hydraulic fluid coming from the valve-actuating hydraulic cylinder 2 via the valve-closing high-pressure duct 12 from returning directly to the low-pressure hydraulic circuit 9, so that said fluid is forced to enter the hydraulic positive displacement pump 8.

Said non-return valve 14 permits said hydraulic positive displacement pump 8 to suction said fluid contained in the low-pressure hydraulic circuit 9 when the pressure of the latter is greater than the pressure prevailing in the valve-closing high-pressure duct 12.

According to non-limiting sample embodiment, said non-return valve 14 can be comprised of a ball kept in its seat by a spring.

According to one specific embodiment of the electrohydraulic valve actuator 1 shown in FIG. 21, the pump inlet non-return valve 14 can be replaced by a pump inlet solenoid valve 142 which can then be mounted parallel to a pump inlet pressure limiter 143 which permits the hydraulic fluid to pass directly from the low-pressure reservoir 10 to the inlet of the hydraulic positive displacement pump 8 without passing through said solenoid valve 142 when the difference in pressure at the ends of said solenoid valve exceeds a certain value. This configuration can advantageously cooperate with a non-return valve 145 of the valve-closing high-pressure duct 12 in order to enable the pressure prevailing in the low-pressure reservoir 10 to be greater than that necessary to completely close the valve 101 of the engine 100, said configuration making it possible, in particular, to reduce the average difference in pressure applied to the ends of the hydraulic positive displacement pump 8 in order to improve the energy performance of the electrohydraulic valve actuator 1.

The electrohydraulic valve actuator 1 comprises at least one valve-opening cam 15 connected, on the one hand, to the valve-actuating hydraulic cylinder 2 by a mechanical transmission 16 and, on the other hand, to the valve 101 of the internal combustion engine 100 either directly or via an intermediate transmission 17.

Said valve-opening cam 15 moves in one direction during the opening operations of said valve 101, then in the opposite direction during the closing operations of said valve 101.

Said intermediate transmission 17 can be a tappet, a rocker arm or a roller-type breaker arm 18 known to a person skilled in the art, it being possible for the latter to optionally comprise an inherently known automatic device for compensating for the clearance between said cam 15 and said valve 101.

Said valve-opening cam 15 is [sic] the movable parts with which it cooperates, said mechanical transmission 16 and said intermediate transmission 17 being embodied such that they are as light as possible.

The electrohydraulic valve actuator 1 comprises at least one return spring 19 of the valve-opening cam 15 which tends to return said cam 15 to the position it is in when the valve 101 of the internal combustion engine 100 is closed.

According to one specific embodiment, said return spring 19 can be the spring 103 ensuring that said valve 101 returns to the closed position.

The valve 101 of the internal combustion engine 100 comprises a position sensor (not shown) which can be inductive, function using the Hall effect, or be any other type known to a person skilled in the art.

FIG. 9 shows a sample embodiment of the electrohydraulic valve actuator with cylinder and reciprocating cam 1 according to the present invention.

The electrohydraulic valve actuator 1 comprises a valve-actuating hydraulic cylinder 2 which rotates and a valve-actuating piston 3 have the shape of a pallet.

Said valve-actuating piston 3 separates at least one high-pressure chamber 20 from at least one low-pressure chamber 21 such that the pressure of the hydraulic fluid can rotate said piston 3, the latter being rotationally connected either directly or indirectly to the valve-opening cam 15.

FIG. 6 shows another sample embodiment of the electrohydraulic valve actuator with cylinder and reciprocating cam 1 according to the present invention.

The electrohydraulic valve actuator 1 comprises a valve-actuating piston 3 which can move in a cylinder 22 and push on a valve-opening rack 23 guided in a cylinder head 104 comprised by the internal combustion engine 100 or by the piston compressor.

Said valve-opening rack 23 cooperates with a pinion 24 arranged on an axis 25 of the valve-opening cam 15 so as to rotate said cam 15 when said piston 3 moves in longitudinal translation, said rack 23 and said pinion 24 constituting the mechanical transmission 16.

Note that, according to one specific embodiment, the pinion 24 may be comprised of a toothed segment of a few degrees arranged directly on the perimeter of the valve-opening cam 15.

The valve-opening rack 23 can be guided in the cylinder head 104 of the internal combustion engine 100 or by means of at least one ball or roller bearing 26.

FIG. 7 shows another sample embodiment of the electrohydraulic valve actuator with cylinder and reciprocating cam 1 according to the present invention.

The electrohydraulic valve actuator 1 comprises a valve-actuating piston 3 which can move in a cylinder 22 and push a valve-opening rod 27 with one of the ends at which it is hinged.

Said valve-opening rod 27 pushes, in turn, on a cam arm 28 comprised directly or indirectly by the valve-opening cam 15 with which the other end of said rod 27 is also hinged so as to rotate said cam 15 when said valve-actuating piston 3 moves in longitudinal translation.

The valve-opening rod 27 and the cam arm 28 constitute the mechanical transmission 16 of the electrohydraulic valve actuator 1.

The valve-opening rod 27 is hinged at at least one of its two ends by means of an open or closed ball-and-socket joint 29.

The valve-opening cam 15 comprises a cam angular position sensor 30 which can be a coder or any other type of angular sensor known to a person skilled in the art (FIGS. 6, 7, 9 and 12).

The valve-opening cam 15 cooperates with a cam stop, not shown, which limits the maximum angular position of said cam 15 when the valve 101 of the internal combustion engine 100 actuated by said cam 15 is closed.

The cam stop is mounted on a shock absorber or comprises a shock absorber, thus limiting the acoustic emissions when said valve-opening cam 15 comes into contact with the cam stop.

FIG. 5 shows a sample embodiment of the hydraulic positive displacement pump 8 of the electrohydraulic valve actuator with cylinder and reciprocating cam 1 according to the present invention.

The hydraulic positive displacement pump 8 comprises several compartments 31 each of which constitutes an autonomous pump comprising at least one inlet 32 and at least one outlet 33 connected to at least one valve-actuating hydraulic cylinder 2, said autonomous pumps being rotated by the same shaft 34 and being housed in the same casing 35.

FIGS. 10 and 11 show another sample embodiment of the electrohydraulic valve actuator with cylinder and reciprocating cam 1 according to the present invention.

The valve-opening cam 15 comprises two open or closed joints 36, 37 and a cam leverage contact surface 38.

The first joint 36 is fixed to the internal combustion engine 100, whereas the second joint 37 is connected to the valve-actuating piston 3 either directly by a piston follower or indirectly by a push rod 40.

The valve-opening cam 15 can roll and/or slide on a rocker switch contact surface 41 arranged on a rocker switch breaker arm 42 hinged at one of its ends on at least one breaker arm anchorage 43 fixed to said engine 100 and equipped at its other end with at least one breaker arm follower 44 which can push directly or indirectly on the tail 105 of at least one valve 101 of said engine 100 in order to open said valve.

Since the two joints 36, 37 of the valve-opening cam 15, the cam leverage contact surface 38, the rocker switch contact surface 41, and the position of the breaker arm anchorage 43 and of the breaker arm follower 44 are provided so as to offer to the valve-actuating piston 3 a large leverage arm for opening the valve 101 of the internal combustion engine 100 when said valve 101 is closed, said leverage arm then becoming weaker and weaker as the lift height of said valve 101 becomes greater.

Note that the breaker arm anchorage 43 can be comprised of an inherently known hydraulic device for compensating for the play in said valve 101.

Note that the shape of the valve-opening cam 15, the shape of the contact surface 41 arranged on the rocker switch breaker arm 42, the positioning of the joint fixed to the internal combustion engine 100 of said cam 15, and the positioning of the breaker arm anchorage 43 fixed to said engine 100 are determined so as to favor the largest rolling component possible and the smallest slide component possible at the point of contact between said cam 15 and said contact surface 41 when said valve 101 undergoes an opening or closing operation.

The valve-opening cam 15 comprises two joints 36, 37 at least one of which of the two open or closed joints is a ball-and-socket joint 45.

The push rod 40 is hinged at each of its ends by a ball-and-socket joint, the first ball-and-socket joint 46 being arranged in or at the end of the valve-actuating piston 3, whereas the second ball-and-socket joint 47 is arranged in or on the valve-opening cam 15.

FIG. 8 shows that the valve-opening cam 15 can be a wedge-shaped slide 90 which can translate under the action of the valve-actuating hydraulic cylinder 2 in a guide or a slide 91 arranged in the cylinder head 104 of the internal combustion engine 100 such that the shape of the wedge of said slide 90 creates a local variation in thickness which makes it possible to lift the valve 101 of the internal combustion engine from its seat or to deposit it therein.

The guide or slide 91 of the valve-opening cam 15 may be comprised of at least one roller 92 on which the wedge-shaped slide rolls.

The wedge-shaped slide 90 cooperates with a rocker switch breaker arm 18 hinged at one of its ends on at least one breaker arm anchorage 43 fixed to said engine 100 and equipped at its other end with at least one breaker arm follower 44 which can push directly or indirectly on the tail 105 comprised by a valve 101 of said engine 100 for opening said valve.

Note that the breaker arm anchorage 43 may be comprised of an inherently known hydraulic device for compensating for the play in said valve.

As is shown in FIG. 13, the valve-opening cam 15 may be comprised of a cam pin 131 hinged at one of its ends on an axis 133 and comprising at its other end a tangential lifting surface 132, said surface having a shape which is such that it pushes radially with respect to said axis 133 on a roller-type rocker switch breaker arm 18 when the cam pin 131 rotates on its axis 133 under the action of the valve-actuating hydraulic cylinder 2.

According to this configuration, the breaker arm 18 is itself hinged at one of its ends on at least one breaker arm anchorage 43 fixed to the engine 100, while being equipped at its other end with at least one breaker arm follower 44 so as to be able to push directly or indirectly on the tail 105 comprised by the valve 101 of said engine in order to open said valve.

In observing FIG. 13, one notes that the mechanical transmission 1 connecting the cam pin 131 to the valve-actuating hydraulic cylinder 2 may be advantageously comprised of a push rod 40 comprising at each of its two ends 135, 136 a pivoting and/or ball-and-socket joint, the first end 135 resting on or in the valve-actuating piston 3, whereas the second end 136 rests on the body of the cam pin 131.

Also note that the return spring 19 of the cam pin 13 may be comprised of at least one helicoidal spring 134 which exerts a force opposite that of the valve-actuating piston 3 and which tends to separate the two pivoting and/or ball-and-socket joints 138, 139 from each other guided with respect to each other by at least one slide connection 137, the first joint 138 resting directly or indirectly on the internal combustion engine 100, whereas the second joint 139 rests on the body of the cam pin 131.

In addition, and as a variant, the tangential lifting surface 132 may end at a stop 140 that can come into contact with the roller-type rocker switch breaker arm 18 so as to limit the angular movement of the cam pin 131.

FIG. 12 shows another sample embodiment of the electrohydraulic valve actuator with cylinder and reciprocating cam 1 according to the present invention.

The valve-opening cam 15 comprises a cam leverage contact surface 38.

The valve-opening cam 15 is rotated by at least one rotating arm 48 one of the ends of which is fixed to the axis 25 of said cam 15, whereas its other end is hinged by means of a pivot or ball-and-socket joint 49 with the first end of an arm push rod 40.

The second end of said rod 40 is hinged by means of a pivot or ball-and-socket joint 47 with the valve-actuating piston 3.

The valve-opening cam 15 can roll and/or slide on a rocker switch contact surface 41 arranged on a rocker switch breaker arm 42 hinged at one of its ends on at least one breaker arm anchorage 43 fixed to the internal combustion engine 100 and equipped at its other end with at least one breaker arm follower 44 which can push directly or indirectly on a tail 105 comprised by at least one valve 101 of said engine 100 in order to open said valve 101.

The axis 25 of the valve-opening cam 15, the cam leverage contact surface 38, the rocker switch contact surface 41, and the positioning of the breaker arm anchorage 43 and of the breaker arm follower 44 are provided so as to offer to the valve-actuating piston 3 a large lifting arm for opening the valve 101 of the internal combustion engine 100 when said valve 101 is closed, said lifting arm then becoming weaker and weaker as the lift height of said valve 101 becomes greater.

Note that, according to one specific embodiment, the rotating arm 48 can rotate several valve-opening cams 15.

Also note that the breaker arm anchorage 43 may be comprised of an inherently known hydraulic device for compensating for the play in said valve.

Note that the shape of the valve-opening cam 15, the shape of the contact surface arranged on the rocker switch breaker arm 42, the positioning of the joint fixed to the internal combustion engine of said cam, and the positioning of the rocker switch anchorage fixed to said engine are determined so as to favor the largest rolling component possible and the smallest sliding component possible at the point of contact between said cam and said surface when said valve undergoes an opening or closing operation.

The valve-actuating piston 3 moves in a cylinder 22 equipped with a shock-absorbing opening at the end of the piston stroke 50.

The shock-absorbing opening 50 is sealed in whole or in part by said piston 3 when said piston 3 arrives near the position it is in when the valve 101 of the internal combustion engine 100 that it actuates is closed.

Said shock-absorbing opening 50 slows said piston 3 by progressively reducing the section through which the hydraulic fluid passes which is expelled out of said hydraulic cylinder 2 upon the closing of said valve 101.

The valve-actuating piston 3 moves in a cylinder 22 equipped with a piston end-position stop, said stop limiting the depth to which said piston 3 is introduced into said cylinder 22.

FIGS. 14 and 15 show a sample embodiment of the valve-opening solenoid valve 4 and/or valve-closing solenoid valve 6 and/or pump outlet sealing solenoid valve 13 of the electrohydraulic valve actuator with cylinder and reciprocating cam 1 according to the present invention.

The valve-opening solenoid valve 4 and/or the valve-closing solenoid valve 6 and/or the pump outlet sealing solenoid valve 13 is a tube solenoid valve 60 comprised of at least one rectilinear tube 61 that can move in longitudinal translation in a valve casing 62 comprising an upper chamber 63 and a lower chamber 64.

The rectilinear tube 61 comprises a first end 65 leading into the upper chamber 63 and a second end 66 leading into the lower chamber 64.

The second end 66 of the rectilinear tube 61 can come into contact with at least one sealing surface 67 fixed to said valve casing 62 so as to seal said second end in as tight as manner as possible.

The tube solenoid valve 60 comprises sealing means 68 between the external surface of the rectilinear tube 61 and the valve casing 62 which isolate the upper chamber 63 from the lower chamber 64.

The tube solenoid valve 60 comprising at least one closing spring 69 which tends to maintain the rectilinear tube 61 in contact with the sealing surface 67.

The tube solenoid valve 60 comprises at least one electrical actuator 70 capable of applying to the rectilinear tube 61 a force opposite that produced by the closing spring 69, said force being sufficient to lift the rectilinear tube 61 from the sealing surface 67 when an electric current passes through said actuator.

The electrical actuator 70 is comprised of a coil of conductive wire 71 which attracts a conductive core or pallet 72 when an electric current passes through said coil 71.

The conductive core or pallet 72 of the electrical actuator 70 can be housed in the upper chamber 63 of the valve casing 62.

The coil of conductive wire 71 of the electrical actuator 70 can be housed in the upper chamber 63 of the valve casing 62.

The coil of conductive wire 71 of the electrical actuator 70 can be housed on the exterior of the upper chamber 63, the magnetic field generated by said coil 71 when electric current passes through it passing through the external wall of said chamber 63 so as to exert a force on the conductive core or pallet 72.

The first end 65 of the rectilinear tube 61 can be fixed to the conductive core or pallet 72.

The conductive core or pallet 72 can be embodied in the same metallic part as the rectilinear tube 61, or it can be fixed to said core by gluing, screwing, crimping, or by any other means known to a person skilled in the art.

The first end 65 of the rectilinear tube 61 comprises at least one radial and/or axial opening 88 leading into the upper chamber 63.

The second end 66 of the rectilinear tube 61 has the shape of a truncated sphere and has a line of contact with the sealing surface 67 similar to that made by a ball resting on a seat.

The sealing surface 67 is arranged on a mounted floating independent part 73 in the valve casing 62, said part 73 being able to align with the rectilinear tube 61 when the second end 66 of said tube comes into contact with said sealing surface 67.

The valve casing 62 comprises directly, or indirectly via an intermediate plug 74, a vent 75 which is closed by the independent part 73 on which the sealing surface is arranged the sealing surface 67 such that the force applied by the closing spring 69 via the rectilinear tube 61 to said independent part 73 and/or the force resulting from the pressure prevailing in the upper chamber 63 and/or the lower chamber 64 maintains said part 73 under pressure on said vent 75 in order to keep it closed.

The contact surface between said independent part 73 and said valve casing 62 can be provided with a joint or with a stop which increases the contact pressure locally so as to improve the tightness between said part 73 and said casing 62.

The valve casing 62 is fixed to the internal combustion engine 100 and comprises inlet/outlet openings and/or ducts 89 connecting the upper chamber 63 and/or the lower chamber 64 either to the valve-actuating hydraulic cylinder 2 or to the hydraulic positive displacement pump 8 via the incoming high-pressure hydraulic circuit 5, the outgoing high-pressure circuit 7 or the low-pressure hydraulic circuit 9.

The section of the rectilinear tube 61 at the seal which said tube constitutes with the valve casing 62 is slightly smaller than the section of said tube at its contact with the sealing surface 67.

The sealing means 68 are comprised by the external surface of the rectilinear tube 61 which cooperates with the internal surface of the valve casing 62.

The sealing means 68 can also be comprised by the external surface of the rectilinear tube 61 which cooperates with the internal surface of the valve casing 62 in which can be housed at least one annular joint and/or at least one segment which can be advantageously replaced by a small clearance of a few microns left between the external surface of the rectilinear tube 61 and the internal surface of the valve casing 62.

It is possible to arrange on the rectilinear tube 61 an adjustable or non-adjustable stop which cooperates with an axial stop surface provided directly or indirectly in the valve casing 62, said stop determining the maximum distance between said tube and the sealing surface 67 with which it cooperates.

Note that the valve casing 62 can house several tube solenoid valves 60 such as those described previously.

FIG. 16 shows a sample embodiment of the replenishing pump 52 of the electrohydraulic valve actuator with cylinder and reciprocating cam 1 according to the present invention.

The replenishing pump 52 comprises a replenishing piston 54 which can move back and forth in a blind-end cylinder 55 arranged in a blind-end cylinder casing 56 so as to define a variable volume on the interior of said cylinder.

Le replenishing piston 54 cooperates with a replenishing inlet valve 57 and a replenishing outlet valve 58 whose respective outlet and inlet lead into said volume, said inlet valve 57 letting in hydraulic fluid coming from the replenishing reservoir 53, whereas the outlet valve 58 expels said fluid into the compensating pressure accumulator 51 or into the replenishing pressure accumulator 85.

The replenishing piston 54 is actuated translationally in a first direction by an electrical solenoid actuator 80 primarily comprised of a replenishing magnetic core 81, a coil of conductive wire 82, and a replenishing magnetic casing 83, and in a second direction by a spring 84 enabling said replenishing piston 54 to return.

The blind-end cylinder casing 56 is embodied in the same part as the replenishing magnetic casing 83 of the electrical solenoid actuator 80.

The blind-end cylinder casing 56 comprises a jacket 59 in which the replenishing piston 54 of the replenishing pump 52 moves.

The blind-end cylinder 55 comprises an end-position delivery opening 76 which connects said cylinder to the replenishing outlet valve 58 such that the replenishing piston 54 covers said opening at the end of the delivery stroke and is slowed and then stopped in its delivery stroke.

Note that the maximum stroke of the replenishing piston 54 is limited in the delivery direction by a delivery stop 77 and/or in the suction direction by a suction stop 78.

The delivery stops 77 and suction stops 78 may be comprised of at least one piece of elastic material providing shock-absorbing properties.

The replenishing magnetic core 81 is traversed by the replenishing piston 54 on which it is rigidly mounted.

The replenishing piston 54 passes through the replenishing magnetic casing 83 from end to end in order to cooperate on one side of said casing with the blind-end cylinder 55 and on the other side of said casing with the return spring 84 of said replenishing piston 54.

According to a first modification of this arrangement, the replenishing piston 54 can be fixed to the replenishing core 81.

For this purpose, said replenishing core 81 comprises means of connection to the return spring 84, the latter being fixed indirectly to said replenishing piston 54 so as to return both said core and said spring.

As a variant as illustrated in FIGS. 17 to 20, the replenishing pump 52 may comprise a replenishing tube piston 107 which can move back and forth in an open cylinder 108 arranged in an open casing 109 which is directly or indirectly integral with a pump casing 126.

Thus, said piston 107, said cylinder 108 and said pump casing 126 define together a variable volume 110 on the interior of said cylinder 108, said replenishing tube piston 107 cooperating with a tube piston inlet valve 111 comprised by a ball 113 and a spring 114, said ball resting on a seat 115 arranged at the bottom and on the interior of said piston 107 and an open cylinder outlet valve 112 comprised by a ball 116 and a spring 117, said ball resting on a seat 118 arranged at the bottom and on the exterior of said cylinder 109.

It should therefore be noted that said inlet valve 111 lets in hydraulic fluid coming from the replenishing reservoir 53, whereas the outlet valve 112 expels said fluid into the compensating pressure accumulator 51 or into the replenishing pressure accumulator 85.

According to one specific embodiment, the open cylinder casing 109 may comprise a hydraulic fluid delivery duct 124 which directly or indirectly connects the tube piston inlet valve 111 to a pump inlet opening 125 comprised by the pump casing 126.

Also note that the pump casing 126 comprises a hydraulic fluid outlet duct 127 directly or indirectly connecting the open cylinder outlet valve 112 to a pump outlet opening 128 comprised by the pump casing 126.

According to the selected embodiment, the replenishing tube piston 107 may be actuated translationally in a first direction by an electrical solenoid actuator 119 primarily comprised by a replenishing magnetic core 120 fixed to said piston 107, a coil of conductive wire 121, and a replenishing magnetic casing 122, and in a second direction by a return spring 123 of the replenishing tube piston 107.

According to this configuration, the replenishing magnetic core 120 may be provided with at least one core channel 129 indirectly connecting the hydraulic fluid delivery duct 124 to the center of the replenishing tube piston 107 via the tube piston inlet valve 111, the open cylinder casing 109, said core 120 and said piston 111 being commonly housed on the interior of a watertight casing 130, whereas said casing 130 delivers the hydraulic fluid from the duct 124 to the channel 129.

The replenishing reservoir 53 is supplied with hydraulic fluid by the lubricant oil circuit of the internal combustion engine 100.

The replenishing reservoir 53 contains a specific hydraulic fluid and is independent of the lubricant oil circuit of the internal combustion engine 100.

Said hydraulic fluid can be specially formulated so that the performance, the precision and the durability of the electrohydraulic valve actuator with cylinder and reciprocating cam 1 according to the invention are maximized, particularly thanks to a low viscosity of said fluid regardless of the operating temperature of the thermal engine, to low compressibility, to good lubricating and anti-wear characteristics, or to the absence of abrasive particles and corrosive or oxidizing agents.

It should be pointed out that the valve-actuating hydraulic cylinder 2 may comprise at least one drain, not shown, which recovers the hydraulic fluid emerging from said cylinder, so that said fluid returns to the replenishing reservoir 53 via at least one cylinder drainage duct.

Note that the hydraulic positive displacement pump 8 may comprise at least one drain, not shown, which recovers the hydraulic fluid emerging from said pump, so that said fluid returns to the replenishing reservoir 53 via at least one cylinder drainage duct.

The electrohydraulic valve actuator with cylinder and reciprocating cam 1 according to the invention may comprise one or more drain cocks placed on the hydraulic cylinder 2 and/or on the hydraulic positive displacement pump 8 and/or at any point on the incoming high-pressure hydraulic circuit 5 and/or of the outgoing high-pressure hydraulic circuit 7 and/or of the low-pressure hydraulic circuit 9.

Said drain cock(s), not shown, may be of a type analogous to those commonly used by those skilled in the art in any hydraulic application.

The electrohydraulic valve actuator with cylinder and reciprocating cam 1 according to the invention may comprise at least one replenishing pressure accumulator 85 which is inserted between the replenishing pump 52 and the compensating pressure accumulator 51.

The replenishing pressure accumulator 85 may supply several compensating pressure accumulators 51 which respectively supply several independent valve actuator circuits as shown in FIGS. 2 and 3.

The replenishing pressure accumulator 85 supplies said compensating pressure accumulators 51 when the pressure in said circuits goes beyond a certain value.

The replenishing pressure accumulator 85 may be embodied with a membrane, a piston or be of any other type known to a person skilled in the art.

The outlet of the replenishing pressure accumulator 85 comprises a lockout valve ensuring that the pressure is maintained in said accumulator when the internal combustion engine 100 is stopped.

The replenishing pressure accumulator 85 is connected to the compensating pressure accumulator 51 by a duct comprising at least one non-return valve 86, said valve permitting the hydraulic fluid to go from the replenishing accumulator 85 to the compensating pressure accumulator 51, and not vice versa.

The valve-opening high-pressure duct 11 comprises at least one pressure maintenance valve 87 positioned at its end nearest the hydraulic positive displacement pump 8.

The pressure maintenance valve 87 permits the hydraulic fluid coming from said hydraulic positive displacement pump 8 to penetrate into said duct but not to emerge from it.

Particularly, the pressure maintenance valve 87 makes it possible to prevent the depressurization of said circuit between two valve lifts 101 in order to limit the acoustic emissions and to increase the performance of the actuator according to the invention.

As a variant, the outlet of the hydraulic positive displacement pump 8 comprises a low-pressure reservoir 10 non-return valve 141 positioned between said outlet and the pump outlet sealing solenoid valve 13, said valve 141 permitting the hydraulic fluid to go from the outlet of the hydraulic positive displacement pump 8 to said low-pressure reservoir 10, but not vice versa.

The electrohydraulic valve actuator with cylinder and reciprocating cam 1 may comprise at least one hydraulic circuit pressure limiter 146 placed at any point of the low-pressure hydraulic circuit 9 and/or of the valve-opening high-pressure duct 11 and/or of the valve-closing high-pressure duct 12, said limiter 146 permitting the hydraulic fluid contained in said circuit 9 and/or said ducts 11, 12 to return directly to the replenishing reservoir 53 when the pressure prevailing in said circuit 9 and/or said conduits 11, 12 exceeds a certain value.

Based on the preceding description, the functioning of the electrohydraulic valve actuator with cylinder and reciprocating cam 1 according to the present invention is understood.

With respect to FIG. 1, which shows a schematic diagram of a variant of the invention provided in order to control only one valve 101, and with respect to FIG. 12, which proposes a specific embodiment thereof, the actuator according to the invention operates functionally as follows:

The hydraulic positive displacement pump 8 is constantly driven by the crankshaft 102 of the internal combustion engine 100.

When the valve 101 of the internal combustion engine 100 must remain closed, the valve-opening solenoid valve 4 and the valve-closing solenoid valve 6 are closed, whereas the pump outlet sealing solenoid valve 13 is open and allows the hydraulic fluid expelled at the outlet of the hydraulic positive displacement pump 8 to go toward the low-pressure hydraulic circuit 9, the latter feeding hydraulic fluid back to the inlet of said pump 8 at the same rate, via the pump inlet non-return valve 14. Since the differential pressure between the inlet and the outlet of said pump is low, the latter consumes little energy.

When the valve 101 of the internal combustion engine 100 must undergo an opening operation, the pump outlet sealing solenoid valve 13 closes and prevents the hydraulic fluid expelled at the outlet of the hydraulic positive displacement pump 8 from returning to the low-pressure hydraulic circuit 9, so that said fluid is naturally forced into the valve-opening high-pressure duct 11.

Once the pump outlet sealing solenoid valve 13 is closed, the pressure at the outlet of the hydraulic positive displacement pump 8 increases rapidly and reaches that which was previously stored in the valve-opening high-pressure duct 11 by the pressure maintenance valve 87. Approximately at this instant, the valve-opening solenoid valve 4 opens, so that the hydraulic fluid penetrates into the valve-actuating hydraulic cylinder 2 and pushes on the valve-actuating piston 3.

As illustrated in FIG. 12, while moving, the valve-actuating piston 3 pushes on the arm push rod 40, which pushes the rotating arm 48, which rotates the valve-opening cam 15 on its axis 25. The rotation of said cam 15 results in the cam leverage contact surface 38 arranged on said cam 15 exerting pressure on the rocker switch contact surface 41 arranged on the rocker switch breaker arm 42. This causes said breaker arm 42 to topple over which, upon resting on its breaker arm anchorage 43 fixed to the internal combustion engine 100, pushes on the tail 105 of the valve 101 of said engine via its breaker arm follower 44, which results in the opening of said valve 101.

Note that, in view of the arrangement illustrated in FIG. 12, the axis 25 of the valve-opening cam 15, the cam leverage contact surface 38, the rocker switch contact surface 41, and the positioning of the breaker arm anchorage 43 and of the breaker arm follower 44 are provided such that they offer to the valve-actuating piston 3 a large leverage arm for opening the valve 101 of the internal combustion engine 100 when the valve 101 is closed, said leverage arm then becoming weaker and weaker as the lift height of said valve 101 becomes greater.

This configuration enables the progressive acceleration of said valve 101 as well as the possible decompression of the combustion chamber 106 comprised by the internal combustion engine 100, so that the pressure in said cylinder 2, in the incoming high-pressure hydraulic circuit 5, and in the valve-opening high-pressure duct 11 increases progressively without the risk of water hammer or of excitation during the compression and/or decompression of the hydraulic fluid resulting in an instability of the angular position of the valve-opening cam 15 and of the longitudinal position of the valve 101 of said engine.

As can be seen in FIG. 12, the lift height of the valve 101 of the internal combustion engine 100 can be deduced from the angular position of the valve-opening cam 15 that is measured by the cam angular position sensor 30. The measured value is returned to the electronic control unit of the internal combustion engine 100.

When the lift height desired for said valve 101 is reached, said electronic control unit opens the pump outlet sealing solenoid valve 13, which stops the opening of said valve 101 since the hydraulic fluid expelled at the outlet of the hydraulic positive displacement pump 8 is no longer forced into the valve-opening high-pressure duct 11 and therefore naturally flows toward the low-pressure hydraulic circuit 9.

Almost simultaneously, the valve-opening solenoid valve 4 closes, one effect of which is to stabilize the valve 101 in its set position, and another effect of which is to trap a certain quantity of hydraulic fluid under pressure in the valve-opening high-pressure duct 11 and in the incoming high-pressure hydraulic circuit 5, the pressure maintenance valve 87 preventing said fluid from returning toward the hydraulic positive displacement pump 8.

Note that the trapping of said fluid in said ducts by said valve can advantageously lead to decreased acoustic emissions and/or to improved performance of the actuator according to the invention, particularly by reducing the volume of fluid that is stopped violently in the compensating pressure accumulator 51.

Note that the valve 101 of the internal combustion engine 100 is kept open as long as the valve-closing solenoid valve 6 is not actuated by the electronic control unit so as to open. The timing of the opening of said valve 101 is determined based on the objectives assigned to the control of the internal combustion engine 100, whether it be to improve the torque and power performance of said engine, to improve its energy efficiency, or to reduce its pollutant emissions.

In order to reclose said valve 101 at the desired time, the electronic control unit opens the valve-closing solenoid valve 6. The result of this action is to permit the hydraulic fluid contained in the valve-actuating hydraulic cylinder 2 to emerge through the outgoing high-pressure hydraulic circuit 7 and then through the valve-closing high-pressure duct 12 in order to be connected to the inlet of the hydraulic positive displacement pump 8.

This action instantaneously increases the pressure at the inlet of said pump, so that said pressure becomes greater that that prevailing in the low-pressure hydraulic circuit 9. This difference in pressure closes the pump inlet non-return valve 14, so that hydraulic fluid coming from the valve-actuating hydraulic cylinder 2 is forced to pass through the inlet of said hydraulic positive displacement pump 8.

Rotated by the fluid expelled by the valve-actuating hydraulic cylinder 2, said hydraulic positive displacement pump 8 becomes a motor and returns to the crankshaft 102 of the internal combustion engine 100 a portion of the mechanical work that previously made it possible to compress the hydraulic fluid and the spring 103 of the valve 101 of said engine and to tension the return spring 19 of the valve-opening cam 15 and that previously made it possible to accelerate said valve, and the entire chain of mechanical transmission 16 and hydraulic transmission moved in a reciprocating motion by the actuator according to the invention.

Note that the valve-closing solenoid valve 6 can be opened a single time, but it can also be opened either in a proportional manner or several times. These strategies for opening said solenoid valve can contribute to minimizing the shock that the valve 101 of the internal combustion engine 100 suffers when it lands on its seat in addition to the variable leverage effect produced by mechanical transmission 16 and by the intermediate transmission 17 as represented in FIG. 12.

Particularly, the proportional opening of said valve-closing solenoid valve 6 can be achieved by applying a pulse-width modulated current to the ends of its coil 71, this method also being known under the acronym “PWM” (Pulse Width Modulation). The controlling of said solenoid valve is entrusted to the electronic control unit, which cooperates with the cam angular position sensor 30 and/or the crankshaft angular coder 102 of the internal combustion engine 100 in order to control the speed of said valve 101, particularly at the moment it lands on its seat.

Note that the total volume of the hydraulic circuit of the actuator 1 varies depending on the position of the valve-actuating piston 3 in its cylinder 22. This variation in volume is absorbed by the compensating pressure accumulator 51 which maintains the pressure of the low-pressure hydraulic circuit 9 between two values, a minimum and a maximum.

Said minimum pressure value is sufficient, on the one hand, to enable the actuator 1 according to the invention to function without cavitation phenomena, said phenomena being deemed destructive and, on the other hand, to minimize the possible positional instabilities of the valve 101 of the internal combustion engine 100 introduced by the compressibility of the hydraulic fluid. In any event, said maximum pressure valve must not exceed that which permits the valve-actuating piston 3 to lift the valve 101 of the internal combustion engine 100 from its seat.

Note that if the minimum pressure value of the low-pressure hydraulic circuit 9 descends below a certain threshold—said value being monitored by an electronic control unit by means of a pressure sensor placed at any point in the low-pressure hydraulic circuit 9—the replenishing pump 52 replenishes the compensating pressure accumulator 51 with hydraulic fluid by suctioning said fluid in the replenishing reservoir 53 and delivering said fluid into said accumulator.

In FIGS. 2 and 3, one can see that when the actuator 1 according to the invention provides several parallel circuits each supplying several valves 101 or groups of valves not opening at the same time but belonging to the same internal combustion engine 100, a replenishing pressure accumulator 85 can advantageously be inserted between the replenishing pump 52 and the compensating pressure accumulators 51 comprised by each of said parallel circuits. In this case, a single replenishing pressure accumulator 85 supplies hydraulic fluid to the compensating pressure accumulator 51 comprised by each low-pressure hydraulic circuit 9 via the replenishing non-return valve 86 comprised by each of said low-pressure hydraulic circuits.

According to this configuration, it is the minimum pressure value prevailing in the replenishing pressure accumulator 85 that is monitored by the electronic control unit by means of a pressure sensor, the minimum pressure value prevailing in each of the low-pressure hydraulic circuits 9 being maintained automatically at the desired value by its replenishing non-return valve 86.

As will also be readily understood, the preceding description has only been given as an example and does not at all limit the scope of the invention, which includes the details of execution described by any other equivalent.

Claims

1. Electrohydraulic valve actuator with cylinder and reciprocating cam for internal combustion engine (100), characterized in that it comprises: at least one valve-actuating hydraulic cylinder (2) which comprises at least one valve-actuating piston (3) which opens at least one valve (101) of an internal combustion engine (100) or of a piston compressor when the cylinder (2) is connected by a valve-opening solenoid valve (4) to at least one incoming high-pressure hydraulic circuit (5), said cylinder (2) closing said valve (101) when it is connected by a valve-closing solenoid valve (6) to at least one outgoing high-pressure circuit (7), and said cylinder (2) maintaining said valve (101) open when it is connected neither to the incoming high-pressure circuit (5) nor to the outgoing high-pressure circuit (7);at least one hydraulic positive displacement pump (8) comprising at least one outlet connected to a low-pressure circuit (9) connected to at least one low-pressure reservoir (10) and at least one inlet connected to said low-pressure hydraulic circuit (9), said pump (8) rotating at a speed proportional to that of a crankshaft (102) of the internal combustion engine (100);at least one high-pressure valve-opening duct (11) connecting the output of the hydraulic positive displacement pump (8) to the incoming high-pressure hydraulic circuit (5) of the valve-actuating hydraulic cylinder (2);at least one valve-closing high-pressure duct (12) connecting the inlet of the hydraulic positive displacement pump (8) to the outgoing high-pressure hydraulic circuit (7) of the valve-actuating hydraulic cylinder (2);at least one pump outlet closure member (13) which is able to prevent the hydraulic fluid expelled at the outlet of the hydraulic positive displacement pump (8) from returning to the low-pressure hydraulic circuit (9), so that said fluid is forced into the high-pressure valve-opening duct (11);at least one pump inlet non-return valve (14) which prevents the hydraulic fluid coming from the valve-actuating hydraulic cylinder (2) via the high-pressure valve-closing duct (12) from returning directly to the low-pressure hydraulic circuit (9), so that said fluid is forced to the inlet of the hydraulic positive displacement pump (8) while said valve enables the pump to intake the fluid contained in the low-pressure hydraulic circuit (9) when the pressure of the latter is greater than the pressure in the valve-closing high-pressure duct (12);at least one valve-opening cam (15) connected on the one hand to the valve-actuating hydraulic cylinder (2) by a mechanical transmission (16) and on the other hand to the valve (101) of the internal combustion engine (100) either directly or through an intermediate transmission (17), said cam (15) moving in one direction during the opening operations of the valve (101), then in the opposite direction during the closing operations of the valve (101);at least one return spring (19) of the valve-opening cam (15) which tends to return the cam (15) into the position it is in when the valve (101) of the internal combustion engine (100) is closed.

2. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the valve-actuating hydraulic cylinder (2) rotates and a valve-actuating piston (3) is pallet-shaped, said piston (3) separating at least one high-pressure chamber (20) from at least one low-pressure chamber (21) such that the pressure of the hydraulic fluid can rotate the piston (21), said piston being rotationally connected directly or indirectly to the valve-opening cam (15).

3. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the valve-actuating piston (3) moves in a cylinder (22) and pushes on a valve-opening rack (23) guided in a cylinder head (104) comprised by the internal combustion engine (100) or the piston compressor, said rack (23) cooperating with a pinion (24) arranged on an axis (25) of the valve-opening cam (15) so as to rotate said cam (15) when said piston (3) moves in longitudinal translation.

4. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 3, characterized in that the valve-opening rack (23) is guided in the cylinder head (104) of the internal combustion engine (100) by means of at least one ball or roller bearing (26).

5. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the valve-actuating piston (3) moves in a cylinder (22) and pushes a valve-opening rod (27) with one of the ends of which it is hinged, said rod (27) pushing, in turn, on a cam arm (28) comprised directly or indirectly by the valve-opening cam (15) with which the other end of said rod (27) is also hinged so as to rotate said cam (15) when said piston (3) moves in longitudinal translation.

6. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 5, characterized in that the valve-opening rod (27) is hinged at at least one of its two ends by means of an open or closed ball-and-socket joint (29).

7. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the hydraulic positive displacement pump (8) comprises several compartments (31) each of which constitutes an autonomous pump comprising at least one inlet (32) and at least one outlet (33) connected to at least one valve-actuating hydraulic cylinder (2), said autonomous pumps being rotated by the same shaft (34) and being housed in the same casing (35).

8. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the valve (101) of the internal combustion engine (100) comprises a position sensor.

9. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the valve-opening cam (15) comprises a cam angular position sensor (30).

10. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the valve-opening cam (15) cooperates with a cam stop which limits the maximum angular position of said cam (15) when the valve (101) of the internal combustion engine (100) actuated by said cam (15) is closed.

11. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 10, characterized in that the cam stop is mounted on a shock absorber or comprises a shock absorber limiting the acoustic emissions when said cam (15) comes into contact with the cam stop.

12. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the valve-opening cam (15) comprises two open or closed joints (36, 37) and a cam leverage contact surface (38), the first joint (36) being fixed to the internal combustion engine (100), whereas the second joint (37) is connected to the valve-actuating piston (3) either directly by a piston follower or indirectly by a push rod (40) and said cam (15) being able to roll and/or slide on a rocker switch contact surface (41) arranged on a rocker switch breaker arm (42) hinged at one of its ends on at least one breaker arm anchorage (43) fixed to said engine (100) and equipped at its other end with at least one breaker arm follower (44) which can push directly or indirectly on a tail (105) of at least one valve (101) of said engine (100) in order to open said valve (101).

13. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 12, characterized in that at least one of the two open or closed joints (36, 37) is a ball-and-socket joint.

14. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 12, characterized in that the push rod (40) is hinged at each of its ends by a ball-and-socket joint, the first ball-and-socket joint (46) being arranged in or at the end of the valve-actuating piston (3), whereas the second ball-and-socket joint (47) is arranged in or on the valve-opening cam (15).

15. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the valve-opening cam (15) comprises a cam leverage contact surface (38) and is rotated by means of at least one rotating arm (48) one of the ends of which is fixed to the axis (25) of said cam (15), whereas its other end is hinged by means of a pivot or ball-and-socket joint (49) with the first end of an arm push rod (40), the second end of said rod (40) being hinged by means of a pivot or ball-and-socket joint (47) with the valve-actuating piston (3) and said (15) being able to roll and/or slide on a rocker switch contact surface (41) arranged on a rocker switch breaker arm (42) hinged at one of its ends on at least one breaker arm anchorage (43) fixed to the internal combustion engine (100) and equipped at its other end with at least one breaker arm follower (44) which can push directly or indirectly on a tail (105) comprised by at least one valve (101) of said engine (100) for opening said valve (101).

16. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the valve-actuating piston (3) moves in a cylinder (22) equipped with a piston end-position shock-absorbing opening (50), said opening being closed in whole or in part by said piston (3) when the piston arrives near the position it is in when the valve (101) of the internal combustion engine (100) that it actuates is closed.

17. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the valve-actuating piston (3) moves in a cylinder (22) equipped with a piston end-position stop, the latter limiting the depth of insertion of said piston (3) into said cylinder (22).

18. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the low-pressure reservoir (10) is comprised of at least one compensating pressure accumulator (51) maintained under pressure by at least one replenishing pump (52) which supplies said accumulator with hydraulic fluid by suctioning said fluid into at least one replenishing reservoir (53).

19. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the valve-opening solenoid valve (4) and/or the valve-closing solenoid valve (6) and/or the pump outlet sealing solenoid valve (13) is a solenoid valve tube (60) comprised of at least one rectilinear tube (61) that can move in longitudinal translation in a valve casing (62) comprising an upper chamber (63) and a lower chamber (64), said rectilinear tube (61) comprising a first end (65) leading into the upper chamber (63) and a second end (66) leading into the lower chamber (64), said second end (66) being able to come into contact with at least one sealing surface (67) fixed to said valve casing (62) so as to seal the second end (66) as tightly as possible.

20. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 19, characterized in that the tube solenoid valve (60) comprises sealing means (68) between the external surface of the rectilinear tube (61) and the valve casing (62) which isolate the upper chamber (63) from the lower chamber (64).

21. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 19, characterized in that the tube solenoid valve (60) comprises at least one closing spring (69) which tends to maintain the rectilinear tube (61) in contact with the sealing surface (67).

22. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 21, characterized in that the tube solenoid valve (60) comprises at least one electrical actuator (70) capable of applying to the rectilinear tube (61) a force opposite to that produced by the closing spring (69), said force being sufficient to lift the rectilinear tube (61) from the sealing surface (67) when an electric current passes through said actuator.

23. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 22, characterized in that the electrical actuator (70) is comprised of a coil of conductive wire (71) which attracts a conductive core or pallet (72) when an electric current passes through said coil.

24. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 23, characterized in that the conductive core or pallet (72) is housed in the upper chamber (63).

25. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 23, characterized in that the coil of conductive wire (71) is housed in the upper chamber (63).

26. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 23, characterized in that the coil of conductive wire (71) is housed on the exterior of the upper chamber (63), the magnetic field generated by said coil when an electrical current passes through it passing through the external wall of said chamber so as to exert a force on the magnetic core or pallet (72).

27. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 23, characterized in that the first end (65) of the rectilinear tube (61) is fixed to the conductive core or pallet (72).

28. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 19, characterized in that the first end (65) of the rectilinear tube (61) comprises at least one radial and/or axial opening (88) leading into the upper chamber (63).

29. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 19, characterized in that the second end (66) of the rectilinear tube (61) has the shape of a truncated sphere and has a line of contact with the sealing surface (67) similar to that made by a ball resting on a seat.

30. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 19, characterized in that the sealing surface (67) is arranged on an independent floating mounted part (73) in the valve casing (62), said part being able to align with the rectilinear tube (61) when the second end (66) of said tube comes into contact with said surface.

31. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 30, characterized in that the valve casing (62) comprises directly, or indirectly via an intermediate plug (74), a vent (75) which is closed by the independent part (73) on which the sealing surface (67) is arranged.

32. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 19, characterized in that the valve casing (62) is fixed to the internal combustion engine (100) and comprises openings and/or inlet/outlet ducts (89) connecting the upper chamber (63) and/or the lower chamber (64) either to the valve-actuating hydraulic cylinder (2) or to the hydraulic positive displacement pump (8) via the incoming high-pressure hydraulic circuit (5), the outgoing high-pressure circuit (7) or the low-pressure hydraulic circuit (9).

33. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 19, characterized in that the section of the rectilinear tube (61) at the seal comprised by said tube with the valve casing (62) is slightly smaller than the section of said tube at its contact with the sealing surface (67).

34. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 20, characterized in that the sealing means (68) are comprised of the external surface of the rectilinear tube (61) which cooperates with the internal surface of the valve casing (62).

35. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 19, characterized in that an adjustable or non-adjustable is arranged on the rectilinear tube (61) which cooperates with an axial stop surface (93) arranged directly or indirectly in the valve casing (62), said stop determining the maximum distance between said tube and the sealing surface (67) with which it cooperates.

36. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 19, characterized in that the valve casing (62) can house several tube solenoid valves (60).

37. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 18, characterized in that the replenishing pump (52) comprises a replenishing piston (54) which can move back and forth in a blind-end cylinder (55) arranged in a blind-end cylinder case (56) so as to define a variable volume on the interior of said cylinder, said replenishing piston (54) also cooperating with a replenishing inlet valve (57) and a replenishing outlet valve (58), the outlet and inlet respectively lead into said volume, said inlet valve (57) letting in hydraulic fluid coming from the replenishing reservoir (53), whereas said outlet valve (58) expels said fluid into the compensating pressure accumulator (51) or into the replenishing pressure accumulator (85).

38. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 37, characterized in that the replenishing piston (54) actuated in translation in a first direction by an electric solenoid actuator (80) comprised primarily of a replenishing magnetic core (81), a coil of conductive wire (82), and a replenishing magnetic casing (83), and in a second direction by a return spring (84) of the replenishing piston (54).

39. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 38, characterized in that the blind-end cylinder casing (56) is embodied in the same metallic part as the replenishing magnetic casing (83).

40. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 37, characterized in that the blind-end cylinder casing (56) comprises a jacket (59) in which the replenishing piston (54) moves.

41. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 38, characterized in that the blind-end cylinder (55) comprises an end-position delivery opening (76) which connects said cylinder to the replenishing outlet valve (58) such that the replenishing piston (54) seals said opening at the end of the delivery stroke and is slowed and then stopped in its delivery stroke.

42. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 37, characterized in that the maximum stroke of the replenishing piston (54) is limited in the delivery direction by a delivery stop (77) and/or in the suction direction by a suction stop (78).

43. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 38, characterized in that the replenishing magnetic core (81) is traversed by the replenishing piston (54) on which it is rigidly mounted, said piston traversing the replenishing magnetic casing (83) from end to end in order to cooperate on one side of said casing with the blind-end cylinder (55) and on the other side of said casing with the return spring (84) of said piston (54).

44. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 18, characterized in that the replenishing pump (52) comprises a replenishing tube piston (107) which can move back and forth in an open cylinder (108) arranged in an open cylinder casing (109) which is directly or indirectly integral with a pump casing (126) such that said piston (107), said cylinder (108) and said pump casing (126) define together a variable volume (110) on the interior of said cylinder (108), said replenishing tube piston (107) cooperating with a tube piston inlet valve (111) comprised of a ball (113) and a spring (114), said ball resting on a seat (115) arranged at the bottom and on the interior of said piston (107) and an open cylinder outlet valve (112) comprised of a ball (116) and a spring (117), said ball resting on a seat (118) arranged on the bottom and on the exterior of said cylinder (109), said inlet valve (111) letting in hydraulic fluid coming from the replenishing reservoir (53), whereas said outlet valve (112) expels said fluid into the compensating pressure accumulator (51) or into the replenishing pressure accumulator (85).

45. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 44, characterized in that the open cylinder casing (109) comprises a hydraulic fluid delivery duct (124) directly or indirectly connecting the tube piston inlet valve (111) to a pump inlet opening (125) comprised by the pump casing (126).

46. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 44, characterized in that the pump casing (126) comprises a hydraulic fluid outlet duct (127) directly or indirectly connecting the open cylinder outlet valve (112) to a pump outlet opening (128) comprised by the pump casing (126).

47. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 44, characterized in that the replenishing tube piston (107) and actuated in translation in a first direction by an electric solenoid actuator (119) comprised primarily of a replenishing magnetic core (120) fixed to said piston (107), a coil of conductive wire (121), and a replenishing magnetic casing (122), and in a second direction by a return spring (123) of the replenishing piston (107).

48. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 47, characterized in that the replenishing magnetic core (120) is provided with at least one core channel (129) indirectly connecting the hydraulic fluid delivery duct (124) to the center of the replenishing tube piston (107) via the tube piston inlet valve (111), the open cylinder casing (109), said core (120) and said piston (111) being commonly housed on the interior of a watertight casing (130), whereas said casing (130) delivers the hydraulic fluid from the duct (124) to said channel (129).

49. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 18, characterized in that the replenishing reservoir (53) is supplied withy hydraulic fluid by the lubricant oil circuit of the internal combustion engine (100).

50. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 18, characterized in that the replenishing reservoir (53) contains a specific hydraulic fluid and is independent of the lubricant oil circuit of the internal combustion engine (100).

51. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 18, characterized in that the valve-actuating hydraulic cylinder (2) comprises at least one drain which recovers the hydraulic fluid emerging from said cylinder, so that said fluid returns to the replenishing reservoir (53) via at least one cylinder drainage duct.

52. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 18, characterized in that the hydraulic positive displacement pump (8) comprises at least one drain which recovers the hydraulic fluid emerging from said pump, so that said fluid returns to the replenishing reservoir (53) via at least one pump drainage duct.

53. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that it comprises one or more drain cocks placed on the valve-actuating hydraulic cylinder (2) and/or on the hydraulic positive displacement pump (8) and/or at any point of the incoming high-pressure hydraulic circuit (5) and/or of the outgoing high-pressure hydraulic circuit (7) and/or of the low-pressure hydraulic circuit (9).

54. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the valve-opening cam (15) is a wedge-shaped slide (90) which can translate under the action of the valve-actuating hydraulic cylinder (2) in a guide or slide (91) arranged in the cylinder head (104) of the internal combustion engine (100) such that the wedge shape of said slide (90) creates a local variation in thickness which makes it possible to lift the valve (101) of the internal combustion engine (100) from its seat or to deposit it therein.

55. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 54, characterized in that the guide or slide (91) comprises at least one roller (92) on which the wedge-shaped slide (90) rolls.

56. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 54, characterized in that the wedge-shaped slide (90) cooperates with a roller-type rocker switch breaker arm (18) hinged at one of its ends on at least one breaker arm anchorage (43) fixed to the engine (100) and equipped at its other end with at least one breaker arm follower (44) which can push directly or indirectly on the tail (105) comprised by the valve (101) of said engine for opening said valve.

57. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the valve-opening cam (15) is comprised of a cam pin (131) hinged at one of its ends on an axis (133) and comprising at its other end a tangential lifting surface (132), said surface having a shape which is such that it exerts a radial force with respect to said axis (133) on a roller-type rocker switch breaker arm (18) when the cam pin (131) rotates on its axis (133) under the action of the valve-actuating hydraulic cylinder (2), and the breaker arm (18) itself being hinged at one of its ends on at least one breaker arm anchorage (43) fixed to the engine (100) and equipped at its other end with at least one breaker arm follower (44) so as to be able to push directly or indirectly on a tail (105) comprised by the valve (101) of said engine in order to open said valve.

58. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 57, characterized in that the mechanical transmission (16) connecting the cam pin (131) to the valve-actuating hydraulic cylinder (2) is comprised of a push rod (40) comprising at each of its two ends (135, 136) a pivoting and/or ball-and-socket joint, the first end (135) resting on or in the valve-actuating piston (3), whereas the second end (136) rests on the body of the cam pin (131).

59. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 57, characterized in that the return spring (19) of the cam pin (131) is comprised of at least one helicoidal spring (134) which exerts a force opposite that of the valve-actuating piston (3) and which tends to separate the two pivoting and/or ball-and-socket joints (138, 139) from each other guided with respect to each other by at least one slide connection (137), the first joint (138) resting directly or indirectly on the internal combustion engine (100), whereas the second joint (139) rests on the body of the cam pin (131).

60. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 57, characterized in that the tangential lifting surface (132) ends at a stop (140) which can come into contact with the roller-type rocker switch breaker arm (18) so as to limit the angular movement of the cam pin (131).

61. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 18, characterized in that at least one replenishing pressure accumulator (85) is inserted between the replenishing pump (52) and the compensating pressure accumulator (51).

62. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 61, characterized in that the outlet of the replenishing pressure accumulator (85) comprises a lockout valve.

63. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 61, characterized in that the replenishing pressure accumulator (85) is connected to the compensating pressure accumulator (51) by a duct comprising at least one non-return valve (86), said valve permitting the hydraulic fluid to go from the replenishing pressure accumulator (85) toward the compensating pressure accumulator (51) and not vice versa.

64. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the high-pressure valve-opening duct (11) comprises at least one pressure maintenance valve (87) positioned toward its end nearest to the hydraulic positive displacement pump (8), said valve permitting the hydraulic fluid coming from said pump to penetrate into said duct but not to emerge from it.

65. Electrohydraulic valve actuator with cylinder and reciprocating cam as set forth in claim 1, characterized in that the outlet of the hydraulic positive displacement pump (8) comprises a low-pressure reservoir (10) non-return valve (141) positioned between said outlet and the pump outlet sealing solenoid valve (13), said valve (141) permitting the hydraulic fluid to go from the outlet of the hydraulic positive displacement pump (8) to said low-pressure reservoir (10), but not vice versa.