Patent Application
20060243226
The present invention concerns the feed devices for the cooling nozzles of the pistons in internal combustion engines, making it possible to project a cooling fluid such as oil against the tops of the pistons, that is, against the surfaces of the pistons outside of the explosion chamber, or in the galleries of the tops of the pistons.
The piston cooling nozzles customarily used are detachable parts, secured in the engine and communicating with an admission opening for cooling fluid. The position of the nozzle is determined with precision to produce a jet of cooling fluid directed toward a precise zone of the piston top or the gallery of the piston top. The nozzle is an interchangeable part, whose replacement in principle does not require an overhauling of the engine block itself.
In present-day engines, the cooling nozzles of the pistons are supplied by the lubrication circuit of the engine, in which the cooling and lubricating fluid is propelled by an oil pump, driven in rotation by the engine itself.
Thus, the cooling fluid has a dual role. A first role is to cool the heated elements of the engine, particularly the pistons, carrying away the heat energy given off by these elements through the cooling fluid, whose flow rate and caloric capacity are well chosen. A second role of the cooling fluid is to ensure the lubrication of the moving parts of the engine, such as the crankshaft bearings, the large and small ends of the connecting rod, the sliding surfaces between the pistons and the liner, etc. The fluid used is generally oil. Thus, we shall speak of oil, cooling fluid, or even cooling and lubricating fluid, without drawing a distinction.
In the constant struggle to lower equipment costs in order to remain competitive, automotive designers try to reduce the size of the oil pump. This reduction in size of the oil pump forces the engine designers to make do, at low engine revolutions, with a low flow rate of oil for lubrication. There is thus a need to design means adapted to the reduced size of the oil pumps, yet still able to ensure a good lubrication of the moving parts of the engine at low revolutions, even with a permitted low flow rate of oil.
To do this, there are familiar feed devices for the cooling nozzle, able to inhibit, by a valve, the circulation of cooling fluid until the pressure of the cooling fluid passes a particular threshold value. The valves of such structures of feed devices for cooling nozzles are sometimes in the form of a ball, pushed by a compression spring against a seat to block an opening for the passage of the cooling fluid.
When the engine is turning at low revolutions, the pressure of the cooling fluid is less than a particular threshold pressure: the opening of the seat is blocked and thus there is no jet of cooling fluid directed toward the zone of the piston top. In this way, at low engine revolutions, the majority of the oil is reserved for the lubrication of more sensitive moving parts of the engine, such as the crankshaft bearings, the large or even the small ends of the connecting rod.
At high engine revolutions, the pressure of the cooling fluid is greater than the particular threshold pressure, and the valve of the oil feed device of the cooling nozzles is then opened, allowing a jet of cooling fluid to be directed against a zone of the piston top.
The invention results from the observation of wear effects on the internal moving parts of an engine when using such valve-type feed devices.
Likewise, in the known valve-type cooling nozzles, noise and vibrations perceptible to the human ear are produced upon opening of the valve of the feed devices for the cooling nozzles, which constitutes a parasitic noise source for the user.
To improve the lubrication at low engine revolutions, an oil admission device with two circuits has already been proposed, in document JP 2004-346766 A: the oil is admitted into the engine cylinder from a common channel made in the engine block, which branches in the engine block into a main channel and a secondary channel. A valve-type nozzle is connected at the end of the main channel of the engine block and comprises an upstream segment, a control valve, and a downstream segment which directs a main oil jet longitudinally toward the piston top. The secondary channel of the engine block conveys the oil in the engine block from the common channel, upstream from the valve, directly into the engine cylinder, and directs a secondary oil jet transversely in the engine cylinder. The main and secondary oil jets intersect. The secondary oil jet, directed transversely, is perpendicular to the displacement of the piston in the cylinder and is thus perturbed by the displacement of the piston. As a result, its efficiency is not optimal. The making of the secondary channel requires an additional machining of the engine block, which machining is costly and no modifiable, nor is it easily adaptable to all existing engine block configurations.
The problem put forward by the present invention is to design detachable and interchangeable means which, without modification or alteration of the engine block, efficiently make it possible to reduce these wear effects, and at the same time to reduce these parasitic noises and vibrations in engines outfitted with valve-type feed devices.
To accomplish these objectives, as well as others, the invention calls for a device to feed cooling and lubricating fluid to one or more pistons of an internal combustion engine, the device comprising one or more detachable cooling and lubricating nozzles for the pistons of the internal combustion engine, the device having at least one detachable valve, said valve having an upstream channel which can be connected to a feed channel and having a downstream channel taking the cooling fluid to the piston(s), said detachable valve having means of closure comprising a blocking element able to move in a compartment to block an opening of a seat, said detachable valve responding to the pressure of the cooling fluid by opening when the upstream pressure is greater than a threshold pressure and closing when the upstream pressure is less than the threshold pressure; according to the invention, the detachable valve also has a means of calibrated leakage which connects the upstream channel to the downstream channel in parallel with the means of closure of the valve.
Such a structure can still provide a low flow rate of fluid in the cooling nozzles when the engine is turning at low revolutions, so as to lubricate the sliding contacts between the pistons and the liners. The leakage is calibrated so that the oil flow rate at low engine revolutions is just enough to enable the lubrication of the sliding contacts, but not to reduce the lubrication of the other moving parts of the engine in a substantial manner.
At higher engine revolutions, it generally becomes necessary to cool the pistons and the liner in sliding contact. Now, the increase in engine revolutions increases the pressure of the fluid in the cooling circuit. The movable blocking element then moves away from the seat, thus allowing oil to pass through the opening made in the seat. One then has a sufficient oil flow rate to ensure both lubrication of the moving parts of the engine and their cooling by carrying away the heat energy.
In this way, one minimizes the effects of wear by ensuring a permanent and well distributed lubrication of the moving parts of the engine, including when it is turning at low revolutions, that is, when the pressure of the cooling fluid is less than the particular threshold pressure. The direction of the jet is unchanged, and remains longitudinal against the piston top, regardless of the condition of the valve. The lubrication thus produced is optimal, since it is not perturbed by the movements of the piston.
At low engine revolutions, a low flow rate of cooling fluid is sufficient for the cooling nozzles pointing at a zone of the piston top. This is sufficient, because it is not necessary at that time for the cooling fluid to play any role other than that of lubrication.
At the same time, the maintaining of a slight oil circulation in the downstream channel when the pressure of the cooling fluid is less than the particular threshold pressure makes it possible to reduce the difference between the pressure in the upstream channel and the pressure in the downstream channel at the opening of the valve of the feed device. One thus dampens the movement of the blocking element of the valve of the feed device, thereby reducing in significant fashion the noise produced by the displacement of the blocking element of the valve.
According to a first embodiment, the cooling fluid feed device can contain a valve with means of calibrated leakage, common to several cooling and lubricating nozzles for the piston top.
According to a second embodiment, the cooling fluid feed device can be arranged so that each cooling and lubricating nozzle of the piston top includes a valve with means of calibrated leakage.
Advantageously, the threshold pressure can be between around 1.8 and around 2.8 bar for a gasoline engine, and between around 1.2 and around 2.5 bar for a diesel engine.
Preferably, the means of calibrated leakage can comprise at least one notch made in the seat of the valve.
One thus achieves a means of leakage in economical, simple and rapid manner, one that is easily dimensionable by the depth of the notch made.
A second embodiment of the means of calibrated leakage according to the invention can be contemplated, whereby:
Another embodiment of the device according to the invention can be contemplated, whereby:
According to the invention, an internal combustion engine may have one or more pistons fed with cooling and lubricating fluid by a device as described hereabove.
Advantageously, the valve-type feed device according to the invention can be entirely incorporated into a nozzle, to form a valve nozzle possibly containing:
Preferably, the valve body comprises an upstream segment having the upstream channel and shaped to fit axially in a bore of the engine along an axial direction of penetration and to receive a cooling and lubricating fluid arriving by said bore.
According to another aspect, the valve nozzle can comprise an outlet structure with at least one downstream channel for the passage of fluid in the valve body and with at least one downstream tube for directing onto the piston to be cooled at least one jet of cooling and lubricating fluid.
Advantageously, the downstream outlet tube for cooling and lubricating fluid can be a curved tube whose free end is directed at the piston and contains a contraction.
According to the invention, the valve nozzle can have a threshold pressure between around 1.8 and around 2.8 bar for a gasoline engine, and between around 1.2 and around 2.5 bar for a diesel engine.
Advantageously, the means of calibrated leakage of the valve nozzle can comprise at least one notch made in the seat of the valve.
Preferably, the valve nozzle can be such that
In advantageous manner, the valve nozzle can be such that:
According to the invention, an internal combustion engine may have valve nozzles as described hereabove that feed cooling and lubricating fluid to one or more pistons of the engine.
Other objects, characteristics and advantages of the present invention will emerge from the following description of particular embodiments, provided in connection with the enclosed figures, among which:
a presents two cross section views along planes staggered by 90° relative to each other for a first embodiment of a valve mechanism according to the invention in a closed state;
b presents two cross section views along planes staggered by 90° relative to each other for the embodiment of the valve mechanism of
a presents two cross section views along planes staggered by 90° relative to each other for a second embodiment of a valve mechanism according to the invention in a closed state;
b presents two cross section views along planes staggered by 90° relative to each other for the embodiment of the valve mechanism of
a presents two cross section views along planes staggered by 90° relative to each other for a third embodiment of a valve mechanism according to the invention in a closed state;
b presents two cross section views along planes staggered by 90° relative to each other for the embodiment of the valve mechanism of
In this arrangement, a central detachable valve 21 with calibrated leakage controls the flow of cooling and lubricating fluid from a feed channel 7 in the engine block to the detachable cooling and lubricating nozzles 8a, 8b, 8c and 8d which, by means of their respective downstream channels 9a, 9b, 9c and 9d direct a jet of cooling and lubricating fluid onto the top of the respective pistons 10a, 10b, 10c and 10d to be cooled.
In this arrangement, the detachable cooling and lubricating nozzles 8a, 8b, 8c and 8d do not have an internal valve. Sample embodiments of such nozzles 8a, 8b, 8c and 8d are shown in
The single nozzle 12 has one branch tip 12a designed to be connected to the feed channel 7 (
The double nozzle 11 is connected to the feed channel 7 by its branch tip 11a and has two curved outlet tubes 11b and 11c, whose free ends 11d and 11e have contractions 11f and 11g. The free ends 11d and 11e of the curved outlet tubes 11b and 11c are designed to each direct at least one jet of cooling and lubricating fluid against the tops of the pistons 10a-10d to be cooled.
Such valve nozzles 8a, 8b, 8c and 8d, comprising a valve 21a-21d and a means of calibrated leakage, are shown in
Such valve nozzles 110 or 120 have a valve body 210, whose upstream segment 21e is designed to fit axially into a bore of the engine along an axial direction of penetration. The valve nozzle is a detachable element in the engine block, easily interchangeable and adaptable without modification of the engine block itself.
a shows in cross section a first embodiment of a valve 21 according to the invention in its closed state. The valve 21 comprises a valve body 210 having an upstream channel 13 able to communicate with a feed channel 7 of the engine cooling circuit, in which a pressure prevails that is lower than the particular threshold pressure, chosen by the engine designer. A spring 15 pushes against a seat 19 a blocking element 16 able to move in a compartment 17, to block an opening 18 of the seat 19, thereby preventing the passage of the cooling and lubricating fluid from the upstream channel 13 to go into the compartment 17 and into the downstream channel 14.
There are two notches 20 made in the seat 19, constituting a means of leakage for the cooling and lubricating fluid arriving by the upstream channel 13 in the compartment 17, in parallel with the zone of closure of the valve 21. This means of leakage is calibrated by the depth of the notches 20 made in the seat 19. Thus, even for pressures of the cooling circuit lower than the particular threshold pressure, chosen by the engine designer, there is a circulation of cooling and lubricating fluid through the valve 21, with a rate defined by the cross section of the notches 20 and the pressure of the cooling fluid.
b illustrates the open state of the valve 21 of
a and 6b show a second embodiment of a valve mechanism according to the invention, respectively in its closed state and in its open state.
In
In
Thus, the means of calibrated leakage comprises a radial hole 25 of diameter D1 less than that of the passage left for the oil by the valve 21, once it is opened, that is, the radial passage 26, of diameter D2, made in the lateral wall between the compartment 17 of the valve 21 and the annular chamber 24, and making it possible for the cooling and lubricating fluid to flow from the feed channel 7, connected to the upstream channel 13, to the downstream channel.
a and 7b show a third embodiment of a valve mechanism according to the invention, respectively in its closed state and in its open state.
a shows in cross section a valve according to the third embodiment of the invention in its closed state. The upstream channel 13 communicates with the feed channel 7 of the cooling circuit, in which a pressure prevails that is lower than the particular threshold pressure, chosen by the engine designer. A spring 15 pushes on the blocking element 16, which is a piston able to move in the compartment 17, to block the opening 18 of the seat 19, thereby preventing the passage of the cooling and lubricating fluid from the upstream channel 13 to the compartment 17 and the downstream channel 14.
There are two notches 20 made in the seat 19, constituting a means of leakage for the cooling and lubricating fluid arriving by the upstream channel 13 in the compartment 17, in parallel with the zone of closure of the valve 21. This means of leakage is calibrated by the depth of the notches 20 made in the seat 19. Once in the compartment 17, the cooling and lubricating fluid can go through a transverse passage 27, situated in the piston head 29, and through the axial passage 28 to reach the downstream channel 14.
Thus, even for pressures of the cooling circuit less than the particular threshold pressure, chosen by the engine designer, there is still a slight circulation of cooling and lubricating fluid through the valve 21, with a flow rate defined by the cross section of the notches 20 and the pressure of the cooling fluid.
b illustrates the open state of the valve 21 of
In the three embodiments illustrated in
Of these, curve 1 shows the flow rate of the cooling and lubricating fluid as a function of the pressure in the case of a cooling circuit lacking an oil feeding valve 21 for the cooling and lubricating nozzles 8a, 8b, 8c and 8d of the pistons 10a, 10b, 10c and 10d of an internal combustion engine (
In this same
In this same
The area 4 between the curves 1 and 3 represents the quantity of cooling and lubricating fluid economized by the presence of the oil feed device according to the invention at low engine revolutions, which oil quantity can then be used to lubricate more significant moving parts of the engine, such as the crankshaft bearings, the large and small ends of the connecting rod.
The area 5 between curve 3 and curve 2 represents the quantity of cooling and lubricating fluid used for lubrication of the sliding contact between the pistons and the liner at low engine revolutions, and which thus lets one substantially lessen the effects of wear on this sliding contact at low engine revolutions.
The man skilled in the art will easily understand that the position of the point A on the graph of
The present invention is not limited to the embodiments described explicitly herein, but rather includes the different variants and generalizations contained in the domain of the claims below.
| Number | Date | Country | Kind |
|---|---|---|---|
| 05 04702 | May 2005 | FR | national |
