SLEEVE VALVE OIL SEAL

TECHNICAL FIELD

The subject matter described herein relates to engines that include one or more ports controlled by the motion of one or more sleeve valves.

BACKGROUND

A sleeve valve is a type of valve usable in internal combustion engines, including but not limited to opposed piston engines in which two pistons share a single cylinder, and also in engines in which each piston reciprocates in its own cylinder. Such a valve typically forms all or a portion of the cylinder wall defining a combustion chamber inside the cylinder. In some variations, one or more sleeve valves can reciprocate back and forth substantially in parallel to an axis upon which one or more pistons reciprocates to open and close intake and/or exhaust ports at appropriate times to introduce air or an air-fuel mixture into the combustion chamber and/or to exhaust combustion products from the chamber. In other variations, one or more sleeve valves can rotate about and/or translate along the axis of the piston or pistons to open and close one or both of the intake and exhaust ports. Due to the potentially large circumferential port area that can be controlled by a sleeve valve, such valves can provide a relatively large cross sectional area for fluid flow in the open position.

Sleeve valves, in common with other parts of an internal combustion engine, especially those in the region of the combustion chamber, require cooling. This can be achieved by provision of oil to the sleeve valve, which enables heat arising in the sleeve valve as a result of the combustion process, to be transferred away from the sleeve valve to other parts of the engine. If the oil is delivered to the exterior surface of the sleeve valve, it can transfer heat out of the sleeve valve to other, stationary parts of the engine. The oil can also act as a lubricant between the exterior surface of the sleeve valve and the engine block. However, leakage of the oil into the ports is a concern.

SUMMARY

The current subject matter relates generally to seals for preventing leakage of a liquid (e.g. a coolant and/or a lubricant) past a sleeve valve to a port in communication with a combustion chamber of an internal combustion engine.

In one aspect, a sleeve valve assembly includes a sleeve valve and a substantially ring-shaped seal. The sleeve valve has a valve body configured to at least partially encircle one or more pistons that moves in a reciprocating manner on operation of an internal combustion engine. The sleeve valve and the one or more pistons at least partially define a combustion chamber of the internal combustion engine, and the sleeve valve is configured to move between open and closed positions to control fluid flow through a port that opens to the combustion chamber. The substantially ring-shaped seal is configured to resist leakage of a liquid (e.g. coolant and/or lubricant) past the valve body to the port. In optional variations, the substantially ring-shaped seal includes at least one of a) a ring carried in a groove recessed into the valve body, and b) first and second rings disposed around the valve body and biased apart from each other. In option b), the first and second rings are disposed on a stationary part of the internal combustion engine such that the valve body moves relative to the first and second rings.

In an interrelated aspect, a method includes moving a sleeve valve between open and closed positions to control fluid flow through a port of an internal combustion and resisting leakage of a liquid comprising coolant and/or lubricant past a valve body of the sleeve valve to the port. The resisting is performed at least in part by a substantially ring-shaped seal that includes either or both of a) a ring carried in a groove recessed into the valve body, and b) first and second rings disposed around the valve body and biased apart from each other. In option b), the first and second rings are disposed on a stationary part of the internal combustion engine such that the valve body moves relative to the first and second rings.

In other interrelated aspects an internal combustion engine includes the sleeve valve assembly discussed above with any of the optional variations discussed below. Alternatively or in addition, such an internal combustion engine can be arranged to operate consistent with the method discussed above optionally including any variations discussed below. A vehicle can include such an internal combustion engine.

In optional variations, one or more additional features, including but not limited to those discussed in the next few paragraphs, can be included in implementations of the current subject matter. The ring and/or each of the first and second rings can be formed of a metal. One or more compression rings can be included in a sleeve valve assembly or otherwise be included for resisting leakage of gases in the combustion chamber and/or the port past the sleeve valve. The sleeve valve can reciprocate between the open and closed positions along a common axis with a piston of the one or more pistons. The valve body can include a cylindrical body having a length and a flange spaced apart radially outwards from the cylindrical body and extending along at least a part of the length, and the cylindrical body and the flange can define a cavity therebetween in which the liquid can circulate. The seal can optionally be carried by the flange.

Consistent with option a), the substantially ring-shaped seal can include the ring carried in the groove recessed into the valve body, and the seal can exert a radial force outward against the stationary part of the internal combustion engine. The seal can exert a first force against a first side of the groove and a second force against a second side of the groove. The seal can include a biasing structure that exerts the first and second forces. The seal can include both the ring and an additional ring, and the ring and additional ring can be substantially flat, split rings. The ring and the additional ring can be separated by the biasing structure. The groove can be configured such that the material thickness of the valve body is substantially the same at the groove as through a remainder of the valve body. The seal can remain substantially stationary relative to the valve body as the sleeve valve moves.

Consistent with option b), the substantially ring-shaped seal can include the first and second rings disposed on the stationary part and around the valve body, and the first and second rings can have respective ring tensions to exert a radial force inward against the valve body. The first ring and the second ring can be separated by a biasing structure which biases them apart. The first and second rings can include flat, split rings having respective ring tensions arising from one or more of their shape; size; curvature and material. The stationary part can include a groove in which the seal is installed, and the first ring can be biased against a first side of the groove while the second ring is biased against a second, opposite side of the groove. The stationary part can further include an oil drain through which oil in the groove drains. The sleeve valve body can include a honed surface against which the first and second rings exert the radial force.

The details of one or more variations of the subject matter described herein are set forth in the accompanying drawings and the description below. Other features and advantages of the subject matter described herein will be apparent from the description and drawings, and from the claims. The claims that follow this disclosure are intended to define the scope of the protected subject matter.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, show certain aspects of the subject matter disclosed herein and, together with the description, help explain some of the principles associated with the disclosed implementations. It should be noted that the orientation of various features or structures illustrated in the drawings are not meant to be limiting. For example, in an engine with the axis or axes of reciprocation of the pistons lying close to horizontal, the structures in FIG. 3, FIG. 4, and FIG. 6, FIG. 7, FIG. 8, FIG. 9 will be clearly understood to be rotated by some angle relative to that depicted. In the drawings,

FIG. 1 shows a cutaway diagram of part of an internal combustion engine in which two opposed pistons move reciprocally within a cylinder;

FIG. 2 shows a cross-sectional diagram of part of the internal combustion engine shown in FIG. 1;

FIG. 3A shows a diagram illustrating an example of a first sleeve valve and sealing mechanism consistent with implementations of the current subject matter;

FIG. 3B shows a diagram illustrating another example of a sleeve valve and sealing mechanism consistent with implementations of the current subject matter;

FIG. 4 shows a diagram illustrating an example of a second sleeve valve and sealing mechanism consistent with implementations of the current subject matter;

FIG. 5 shows a process flow diagram illustrating aspects of a method having one or more features consistent with implementations of the current subject matter;

FIG. 6 shows a diagram illustrating an example of a third sleeve valve and sealing mechanism consistent with implementations of the current subject matter, with the sleeve valve in a closed position;

FIG. 7 shows a diagram illustrating the third sleeve valve and sealing mechanism of FIG. 6, with the sleeve valve in an open position;

FIG. 8 shows a diagram illustrating a detail of the sealing mechanism of FIG. 6 and FIG. 7;

FIG. 9 shows a diagram illustrating a detail of another example of a sealing mechanism consistent with implementations of the current subject matter; and

FIG. 10 shows a process flow diagram illustrating aspects of a method having one or more features consistent with implementations of the current subject matter.

When practical, similar reference numbers denote similar structures, features, or elements.

DETAILED DESCRIPTION

Implementations of the current subject matter can, among other possible advantages, provide systems, methods, techniques, etc. to achieve a lubricant seal between a sleeve valve and an engine block or other part of an internal combustion engine that remains stationary during operation of the sleeve valve. In particular, the efficacy of the lubricant seal is improved by provision of an improved sealing apparatus and/or a sealing apparatus that moves with the sleeve valve.

FIG. 1 shows a partially cut away isometric view of an illustrative but non-limiting example of an internal combustion engine 100 in which sleeve valve sealing as discussed herein can be applied. Sleeve valves that are sealed in a manner consistent with implementations of the current subject matter can be used in opposed piston engines, including configurations differing from the examples discussed herein as well as in other engine configurations in which a piston does not share a combustion chamber with one or more other pistons. In addition, the structures and mechanisms for opening and closing sleeve valves that are depicted in the drawings and described herein are only illustrative examples. Other approaches to controlling the operation of sleeve valves in an internal combustion engine can be used in conjunction with the described sealing techniques. Furthermore, in engines including more than one sleeve valve, sealing approaches consistent with implementations of the current subject matter need not be used on all of the sleeve valves. For example, an opposed piston engine with two sleeve valves might use the described sealing technology on either only one of the sleeves or on both of the sleeves controlling fluid flow into and out of the combustion chamber.

The internal combustion engine 100 includes a pair of opposing pistons that includes a first piston 102 and a second piston 104. The first piston 102 is operably coupled to a first crankshaft 106 by a first connecting rod 110 and the second piston 104 is operably coupled to a second crankshaft 112 by a second connecting rod 114. As shown in FIG. 1, the first crankshaft 106 is operably coupled to the second crankshaft 112 by a series of gears that synchronize or otherwise control motion of the first piston 102 and second piston 104. During engine operation, the first piston 102 and the second piston 104 reciprocate toward and away from each other in coaxially aligned cylindrical bores formed by corresponding sleeve valves. More specifically, the first piston 102 reciprocates back and forth in an exhaust sleeve valve 116, while the second piston 104 reciprocates back and forth in a corresponding intake sleeve valve 120. The exhaust sleeve valve 116 and the intake sleeve valve 120 can also reciprocate back and forth to open and close a corresponding exhaust port 122 and inlet port 124, respectively, at appropriate times during the engine cycle to deliver air and/or fuel to a combustion chamber 126 defined at least in part by the bodies of the exhaust and intake sleeve valves 116, 120 and the heads of the first and second pistons 102, 104.

FIG. 2 shows a cross-sectional view 200 of the internal combustion engine 100 of FIG. 1. As further illustrated in FIG. 2, a first pivoting rocker arm 230 (also referred to as a “rocker” 230), which has a proximal end portion in operational contact with a corresponding first cam lobe 232 and a distal end portion operably coupled to the exhaust sleeve valve 116, opens the exhaust sleeve valve 116, for example by moving a sealing edge of the exhaust sleeve valve 116 away from its corresponding first valve seat 234. Similarly, a pivoting rocker arm 236 (also referred to as a “rocker” 240), which has a proximal end portion in operational contact with a second cam lobe 240 and a distal end portion operably coupled to the intake sleeve valve 120, opens the intake sleeve valve 120, for example by moving a sealing edge of the intake sleeve valve 120 away from its corresponding second valve seat 242.

The first cam lobe 232 can be carried on a suitable first camshaft that can be operably coupled to a corresponding crankshaft by one or more gears. On the exhaust side, for example, rotation of the first cam lobe 232 can drive the proximal end portion of the first rocker 230 in one direction (e.g., from left to right), which in turn causes a distal end portion of the first rocker 230 to drive the exhaust sleeve valve 116 in an opposite direction (e.g., from right to left) to thereby open the exhaust port 122. A similar action can occur on the intake side, where rotation of the second cam lobe 240 can drive the proximal end portion of the second rocker 236 in one direction (e.g., from right to left), which in turn causes a distal end portion of the second rocker 236 to drive the intake sleeve valve 120 in an opposite direction (e.g., from left to right) to thereby open the inlet port 124.

Each of the exhaust sleeve valve 116 and the intake sleeve valve 120 is urged into a closed position by a corresponding biasing member, such as for example a first large coil spring 244 and a second large coil spring 246, each of which is compressed between a flange on the bottom portion of the corresponding sleeve valve and an opposing surface fixed to the corresponding crankcase. The first biasing member 244 urges the exhaust sleeve valve 116 from left to right to close the exhaust port 122 as controlled by the first cam lobe 232, and the second biasing member 246 urges the intake sleeve valve 120 from right to left to close the intake port 124 as controlled by the second cam lobe 240.

Due to their proximity to the combustion chamber, the sleeve valves can typically become extremely hot during operation of the engine. Without provision for cooling the sleeve valves, they could undergo damage and distortion. To provide cooling, a coolant, cooling fluid, etc. (such as, for example, oil or the like), can be circulated to contact the sleeve valve. A cooling fluid path within the engine block, part of a sleeve valve assembly, etc. can enable oil to circulate either within or around the sleeve valve, depending on the design of the sleeve valve. Some examples of such cooling are described in co-owned U.S. patent application publication no. US2010/0212622A1, the contents of which are herein incorporated by reference. Regardless of the design of the sleeve valve, it can be desirable for some cooling fluid to flow around the outer surface of the sleeve valve, so that it can act additionally as a lubricant between the outer surface of the sleeve valve and the stationary part of the engine against which it slides. The stationary part can be a part of the engine block, a part of a fluid path-defining piece, or some other engine structure that does not move with the sleeve valve or piston. A trade-off can exist between providing sufficient lubrication and avoiding leakage of cooling fluid past the sleeve valve into the port which the sleeve valve opens and closes. Many prior art piston engines used rotating sleeve valves, which were known to have high oil consumption due to cooling fluid being carried past the sleeve valve to the port by the rotational movement. A reciprocating sleeve valve, has many advantages, such as a better ability to control combustion timing, as described in co-owned U.S. Pat. No. 7,559,298, the disclosure of which is incorporated by reference herein. However, the movement of a reciprocating sleeve valve can potentially cause some amount of the cooling fluid to be carried past the sleeve valve to the port.

To address these and potentially other issues with currently available solutions, one or more implementations of the current subject matter provide methods, systems, articles of manufacture, and the like that may improve the sealing ability of sleeve valves in internal combustion engines. The following exemplary embodiments provide sealing mechanisms for controlling leakage of the cooling fluid into the inlet or exhaust port which is opened and closed by the sleeve valve.

Since a reciprocating sleeve valve does not need to include an opening to align with the intake or exhaust ports, a “sliding seal” i.e. a seal that is able to maintain substantially continuous contact with the sliding metal surface of the sleeve valve, can be used, hence enabling a substantially uninterrupted seal. Some examples of such seals consistent with the current subject matter will be described in the following.

FIG. 3A shows a sleeve valve assembly 300 illustrating features consistent with one or more implementations of the current subject matter. A cross-section through a sleeve valve body 302 is depicted. The sleeve valve body 302 is shown in a closed position, covering a port 306 (which can be an intake port, an exhaust port, etc.). In this position, the sleeve valve body 302 forms a gas seal with a valve seat 304 at a first end 308 of the sleeve valve 302. The first end 308 is proximal to the valve seat 304. As shown in FIG. 3A, the first end of the sleeve valve includes a gas assist feature similar to those described in co-owned U.S. Pat. No. 7,559,298 and co-owned U.S. patent application publication no. US2012/0085309A1, the disclosure of which is incorporated herein by reference.

The sleeve valve body 302 reciprocates to open and close the port 306, in a direction as indicated by an arrow 310. As noted above in reference to FIG. 1 and FIG. 2, the reciprocating can be effected by any variation of valve operation mechanism, including but not limited to cams, rocker arms, biasing springs, hydraulic systems, and the like, in any feasible combination. The sleeve valve body 302 can be formed as a hollow cylinder having an inside surface 312 and an exterior surface 314 and a length extending in the direction of the arrow 310. A piston and a combustion chamber (not shown) are disposed in the interior 316 of the hollow sleeve valve body 302. In other words, the sleeve valve body 302 at least partially encircles at least one piston and a combustion volume that expands and contracts with motion of the at least one piston. A portion of the exterior surface 314 of the sleeve valve 302 distal from the valve seat 304 can run against a cylindrical guide 318 disposed between this distal portion of the sleeve valve and a stationary part 320, which can be the engine block or other engine structure relative to which the sleeve valve body 302 moves.

The proximal end 308 of the sleeve valve can include a flange or lip 322 spaced radially outward from the sleeve valve body 302. A cavity 324 can be formed in the space between the exterior surface 314 of the sleeve valve body 302 in the region of its proximal end 308 and the flange 322. The flange 322 can extend a sufficient distance along the length of the sleeve valve body 302 to cover the port 306 and to enable formation of a seal against the stationary part 320. The flange 322 forms the exterior surface of the sleeve valve in this region of the sleeve valve and partially surrounds the sleeve valve body 302. This part of a sleeve valve can be referred to as an “umbrella” structure. The end of the flange 322 distal from the proximal end 308 of the sleeve valve body 302 can include a groove 325 formed in the exterior surface of the flange 322. The depth of the groove 325 can be such that it can accommodate a seal 326, details of which are described below. The groove 325 can be formed in an end region 327 of the flange 322, although it is not essential for the groove to be at the end of the flange 322. The end region 327 can, in some implementations of the current subject matter, be formed as a lip protruding towards the inner surface 312 of the sleeve valve body 302, such that the material thickness of the flange 322 in that region can be substantially the same as the thickness elsewhere, while forming the groove 325. There is nevertheless a radial space between the groove 325 and the guide 318.

The stationary part 320 has features enabling cooling fluid to be circulated through or in contact with the sleeve valve body 302. This can be achieved by a variety of designs, for example an oil-path defining piece for circulating oil as a cooling fluid such as is described in U.S. Pat. No. 7,559,298. Schematically, the oil path flows form a cooling fluid inlet port 328, along the length of the sleeve valve body 302 in a direction towards the proximal end 308 and into the cavity 324. Having circulated in the cavity 324, as shown by the dotted path, the oil can exit in a region beyond the groove 325 (having been able to flow through the above-mentioned radial space) and back out into the cylinder block 320 through a cooling fluid outlet port 330. Absent some sort of sealing structure or mechanism, such as for example the seal 326, it would be possible for oil to leak past the flange 322 and into the port 306.

The seal 326 is ring-shaped and may be formed from metal or elastomer and can be sized to fit within the groove 325 and to protrude out of the groove 325 to form a seal and running surface against a sealing surface 332 of the stationary part 320. The seal 326 can be dimensioned and have a ring tension such that it provides a good contact against the outer contact (sealing) surface 332 to minimize oil leakage, while also maintaining sufficient tension against the flange 322 with an inner contact surface such that during reciprocating strokes, a small amount of oil can flow onto the outer contact surface 332 to ensure sufficient lubrication during the stroke. In general, oil will be in the area between the seal 326 and the cooling fluid outlet port 330 while the valve is in its closed position (e.g. with the proximal end 308 in contact with the valve seat 304). The sealing surface 332 upon which the seal slides is therefore coated with oil when the sleeve valve is in this position. In some implementations of the current subject matter, this coating of oil can be sufficient to insure proper lubrication of the sliding surface. This lubricating oil and any oil which is scraped by the ring can be drained by provision of a suitable drain in the sleeve valve body 602. The configuration of such a drain would need to ensure that cooling oil circulating through the cavity 624 as previously described was not picked up into the seal. For example, a vertical configuration (i.e. vertically in FIG. 3A or in the direction of the arrow 310 oriented along the length of the sleeve valve 600) for the drain would minimize this happening. Such a drain is shown schematically in the diagram 350 of FIG. 3B. This figure shows a similar arrangement to FIG. 3A, but a flange 322a differs from the flange 322 of FIG. 3A in that it contains a series of vent holes 340. FIG. 3B is taken through one of the vent holes 340, which extend in the direction of the arrow 310 from a groove 325a such that coolant can drain out into the coolant outlet port 330.

A metal ring seal 326 can be designed to balance the amount of oil allowed to pass and the life of the sliding surfaces. Typically, a metal ring seals against the outside sealing surface 332 and one of the sides of the groove 325, but not simultaneously against both the sealing surface 332 and the base of the groove 325. For this reason, a metal oil control ring can employ tension to push the outer contact surface of the ring out against the sealing surface 332. A spring arrangement or some other configuration that provides an expansive force in a direction parallel to the arrow 310 to push the seal 326 against the sides of the groove 325 can also or alternatively be included. A conventional piston ring used to contain lubricating fluid around a piston from entering the combustion chamber generally relies on gas pressure to push the piston ring out against the cylinder walls and down against the side of a groove to make the seal. In the seal configurations described here, a metal seal 326 can include two or more rings. In one example, a three piece ring can include two thin rings and a spring between the two thin rings to push the two thin rings outwardly against the sides of the groove 325. Some examples of use of such a seal will be discussed in more detail below. A seal 326 constructed of an elastomer material can seal against the inner and the outer surfaces because of its ability to change shape under compression, which can accommodate changes in distance between the two sliding surfaces that can result from manufacturing tolerances, temperature differences during operation, etc.

While the seal 326 moves with the sleeve valve, in many cases there will be some local relative movement between the seal 326 and the other parts of the sleeve valve during reciprocating strokes. For example, some degree of movement of the seal 326 within the groove 325 is possible within the scope of the current subject matter. In other words, the seal 326 remains substantially stationary relative to the sleeve valve in general and specifically relative to the flange 322.

In a second sleeve valve system 400 shown in FIG. 4, a spring 402 is present to assist with seating of a sleeve valve body 302 against the valve seat 304. Such a spring can also be used in the configurations shown in FIG. 3A and FIG. 3B. The sleeve valve body 302 has a flange 322. In the configuration of FIG. 4, the flange 322 of FIG. 4 includes a first groove 325A to accommodate a first seal 326A having a first seal inner contact surface and a first seal outer contact surface. The flange 322 also includes a second groove 325B, disposed more distal from the proximal end 308 of the sleeve valve, to accommodate a second seal 326B having a second seal inner contact surface and a second seal outer contact surface. An end region 327 of the flange 322 is shaped to accommodate the two grooves 325A and 325B. The grooves 325A and 325B may each carry a seal of any of the types described above with respect to FIG. 3A and FIG. 3B. Alternatively, one groove may carry a seal of any of the types described above with respect to FIG. 3A and FIG. 3B, while another carries a gas-control ring to minimize leakage of gaseous products past the sleeve valve body 302. One example of a possible gas control ring will be discussed below with reference to FIG. 9.

FIG. 5 shows a process flow chart 500 illustrating method features, one or more of which can be included in an implementation of the current subject matter. At 502, a sleeve valve is cooled with a cooling fluid, in a manner as described above. The cooling fluid can be oil in at least some implementations. At 504, the sleeve valve is operated during a combustion cycle of an internal combustion engine in which it provides a valve function. During some time periods of the combustion cycle, the sleeve valve is stationary, and during other time periods it moves (in a reciprocating motion), to open or close a port. At 506, the sleeve valve resists leakage of cooling fluid to the port by action of one or more ring-shaped seals carried in a respective groove on the sleeve valve. Thus, the seal moves with the valve body or, in other words, remains substantially stationary relative to the valve body during the combustion cycle. Thus its sealing function is optimized. This may improve oil consumption and durability relative to some stationary seal arrangements. Additionally, the seal is formed at a constant distance from a contact end of the sleeve valve, thereby avoiding a condition that can occur in previously available approaches in which the seal is periodically exposed to elevated temperatures of the combustion chamber, for example when the sleeve valve is in an open position and the proximal, contact end of the sleeve valve is withdrawn to the vicinity of a stationary seal mounted on the engine block or some other stationary part of the engine.

A ring-shaped seal made of one or more of a variety of materials, including but not limited to metal (e.g. steel or the like), an elastomer, etc., can be used as the seal 326, 326A, 326B. The ring-shaped seal may be generally ring-shaped but have a gap in a portion of the ring, to facilitate the correct tension and consequent pre-load in the ring relative to the sleeve valve. The ring-shaped seal may be flat to provide optimal contact with the sides of the grooves 325, 325A or 325B. An additional spring may be provided to enable the ring to provide an appropriate level of force to operate as a seal and to allow lubrication as described above. The invention is not limited to a single ring but may include arrangements having multiple rings or other configurations such as spiral rings having, for example, 2-5 or more turns.

A system consistent with implementations of the current subject matter can include a sleeve valve including a valve body arranged to at least partially encircle at least one piston arranged to move in a reciprocating manner. The sleeve valve and the at least one piston at least partially define a combustion chamber of an internal combustion engine. The sleeve valve is moveable between an open position and a closed position to control fluid flow through a port of the internal combustion engine. The system can also include a substantially ring-shaped seal carried in a groove on the sleeve valve in a configuration. During operation of an internal combustion engine that includes the sleeve valve, the substantially ring-shaped seal remains substantially stationary relative to the sleeve valve to resist leakage of coolant from the valve body to the port.

FIG. 6 shows an alternative sleeve valve assembly 600 illustrating features consistent with one or more implementations of the current subject matter. A cross-section through a sleeve valve body 602 is depicted. The sleeve valve body 602 is shown in a closed position, covering a port 306 (which can be an intake port, an exhaust port, etc.). In this position, the sleeve valve body 602 forms a gas seal with a valve seat 304 at a first end 608 of the sleeve valve 602. The first end 608 is proximal to the valve seat 304. As shown in FIG. 6, the first end 608 of the sleeve valve includes a gas assist feature similar to those described in co-owned U.S. Pat. No. 7,559,298 and co-owned U.S. patent application publication no. US2012/0085309A1, the disclosure of which is incorporated herein by reference.

The sleeve valve body 602 reciprocates to open and close the port 306, in a similar manner as discussed above with respect to the sleeve valve body 302 of FIG. 3A and FIG. 3B. FIG. 7 shows the sleeve valve assembly 600 in an open position, in which the port 306 is open i.e. not covered by the sleeve valve assembly 600.

The sleeve valve body 602 can be formed as a hollow cylinder having an inside surface 612 and an exterior surface 614 and a length extending in the direction of the arrow 610. A piston and a combustion chamber (not shown) are disposed in the interior 616 of the hollow sleeve valve body 602. In other words, the sleeve valve body 602 at least partially encircles at least one piston and a combustion volume that expands and contracts with motion of the at least one piston. A portion of the exterior surface 614 of the sleeve valve 602 distal from the valve seat 304 can run against a cylindrical guide 618 disposed between this distal portion of the sleeve valve and a stationary part 620, which can be the engine block or other engine structure relative to which the sleeve valve body 602 moves.

The proximal end 608 of the sleeve valve can include a flange or lip 622 spaced radially outward from the sleeve valve body 602. A cavity 624 can be formed in the space between the exterior surface 614 of the sleeve valve body 602 in the region of its proximal end 608 and the flange 622. The flange 622 can extend a sufficient distance along the length of the sleeve valve body 602 to cover the port 306 and to enable formation of a seal against the stationary part 620. The flange 622 forms the exterior surface of the sleeve valve in this region of the sleeve valve and partially surrounds the sleeve valve body 602. This part of a sleeve valve can be referred to as an “umbrella” structure. This umbrella structure can have an exterior surface finish that has been engineered to provide a sealing surface for sealing against a stationary seal 626 mounted in the stationary part 620. Typically, the surface finished in this way is hard enough to resist the abrasion from the seal 626 and has small surface features that can maintain a small amount of coolant, such as oil, which lubricates the interface between the seal 626 and the surface of the flange 622 as the sleeve valve body 602 moves. Steel and iron having a surface topology provided by a honing process are examples of a suitable surface finish, but others could be contemplated by those skilled in the art. In one example, the honing can include a pattern of shallow scratches that are narrow compared to the dimensions of the sleeve valve body 602 at that are aligned at some angle (e.g. ±approximately 45°, ±approximately 30°, ±approximately 60°) relative to the axis along which the sleeve valve reciprocates. During operation, such scratches can fill with oil to thereby create a sealing effect which can minimize transmission of oil past the sleeve valve body 602 to the port 304 and which is also able to form a substantially gas-tight seal. In another example, the honing can include a pattern of surface features such as divots, depressions, channels, or the like. Surface topologies such as those described, as well as others that are also within the scope of the current subject matter, can be formed by processes such as grinding, burnishing, bombardment with beads or other materials, sanding, laser treatment, etching, or other that might be contemplated by those skilled in the art.

The seal 626 is mounted in a stationary part 620 such as an engine block, so it remains substantially stationary while the sleeve valve assembly 600 moves. In other words, the position of the seal 626 relative to the moving sleeve valve body 602 varies as the sleeve valve moves. For example, in FIG. 6, the seal 626 can be seen as contacting the flange 622 some way along the flange from the proximal end 608 of the sleeve valve body 602, whereas in FIG. 7, the seal 626 can be seen as contacting the flange 622 close to the proximal end 608. The region of the stationary part 620 where the seal is mounted is a small distance (relative to the length of the sleeve valve assembly 600) away from the port 306 in the direction of the arrow 610 i.e. along the length of the sleeve valve assembly 600. Thus in FIG. 7, the contact point is not at the proximal end 608. This arrangement assists in keeping any lubricating coolant which is present between the surface of the flange 622 and the stationary part 620 away from the port, although the contact point could be at the proximal end or closer to it in some implementations. Whilst the seal remains substantially stationary, there may also be some local relative movement of the seal 626 within the region in which it is held in the stationary part 620. For example, some degree of movement of the seal 626 within the stationary part 620 is possible within the scope of the current subject matter.

The seal 626 can be an elastomeric seal, as described in co-owned US publication no. 2012/0085309A1. However, durability may be improved if at least a part of the seal 626 comprises a metal.

One possible design for the seal 626 is a ring arrangement as shown in FIG. 6 and FIG. 7. FIG. 8 shows an enlarged view 800 of the seal 626. It includes a first metal ring 650 disposed at the proximal side of the seal 626 and a second metal ring 652 disposed at the distal side of the seal 626. In various implementations, the rings 650, 652 may be formed from cast iron or steel or some other metal or metal alloy. The rings 650, 652 can also or alternatively include a coating of a metal or an alloy, such as for example molybdenum or chrome, to provide a hard surface finish on the sealing surface of the ring or rings (e.g. the surface of the ring that contacts with the sleeve valve body 602). The rings 650, 652 are shaped as flat cylinders and sit in a plane substantially perpendicular to the arrow 610 i.e. to the length of the sleeve valve assembly 600. Having a substantially planar inner surface facilitates contact with the surface of the flange 622. However, this precise shape is not essential. The two rings 650, 652 may be identical in shape and size or they may be different. The rings can optionally be split. In one example the rings can be configured as one-piece with two narrow regions for contacting the sliding surface of the sleeve valve body 602. The internal geometries of the rings may cause or facilitate the rings to be urged towards the sides 656 of the groove 656. The size, shape, material, curvature and possibly other aspects of the configuration of the rings is chosen such that they have a desired ring tension when fitted around a sleeve valve moving relative to the stationary part 620 in which the rings are held. They are accordingly pretensioned such that they maintain contact with the sleeve valve body 602 on their inner circumferences. They exert a combined force against the sleeve body 602, which may have components of force from each of the two rings. Typical ring tension may be similar to that of a conventional piston ring, but, unlike a conventional piston ring which exerts an outward force, the rings consistent with implementations of the current subject matter exert a force towards the center of the rings i.e. a radially inward force, resulting in a pressure on the sleeve valve body 602.

The first and second rings 650, 652 can be separated by a biasing structure 654, which may be a spring, and conveniently is a spring washer or other similar structure. The ring arrangement is fitted in a groove 656 in the stationary part 620. The groove 656 has a first side 658, corresponding to the proximal end of the sleeve valve body 602 and a second side 660, corresponding to the distal end of the sleeve valve body 602. Thus the first and second sides 658, 660 are substantially flat and substantially parallel to the first and second rings 650, 652 when the ring arrangement is installed in the groove 656. The biasing structure 654 tends to hold the first ring 650 against the first side 658 and the second ring 652 against the second side 660. Thus the first ring 650 exerts a first lateral force on the first side 658 and the second ring 652 exerts a second lateral force on the second side 660. The arrangement of the biasing structure 654 between the two rings 650, 652 thus urges the rings against the sides of the groove 656 and thereby improves the effect of the seal 626 by improving the stability of the rings 650, 652 when subject to forces arising from their contact with the moving sleeve valve 600.

As the sleeve valve 600 moves from the open position of FIG. 7 to the closed position of FIG. 6, the second ring 652 can scrape by at least a small amount of lubricant (e.g. oil) as the surface of the flange 622 moves against the second ring. This lubricant can be pushed back during the return stroke to the closed position and can flow back between the flange 622 and the stationary part 620 and out through the cooling fluid outlet port 330. The first ring 650 will scrape additional lubricant. FIG. 6, FIG. 7, and FIG. 8 show that the groove 656 is open to a drain or vent 662 at the opposite end to that against which the flange 622 moves. Thus any oil that is scraped by the rings 650, 652, and particularly oil scraped by the first ring 650, can flow through the spring 654 to the back of the groove 656 and can then drain out of the groove 656. Alternatively or additionally, one or both rings could be provided with one or more holes and or grooves through which coolant can drain. The vent 662 feeds into the exit port 320, so that any drained oil can flow away from the combustion chamber together with oil that has circulated around the oil path defining piece, and eventually to the engine sump.

In examples consistent with the present subject matter where the seal is held in a stationary part of the engine, the hottest region of the sleeve valve body 602 i.e. the proximal end 608 which closes the port 306, will be closer to the seal at some times during an engine cycle than it would be if the seal remained a fixed distance from the proximal end 608 as in examples such as those of FIG. 3A and FIG. 3B. An alternative or additional means of cooling the sleeve valve may be employed to protect if from the heat of the proximal end 608 of the sleeve valve body 602. Provision for this could be made by means of an extra coolant path, for example in the form of an extra cavity, provided in the stationary part 620 in the region of the seal 626, such as behind the seal. Two such cavities 664a and 664b are depicted in FIG. 6 and FIG. 7. Such cavities can be sized and positioned to fit on one or both sides of the drain 662 and their shape can vary from the exemplary schematic shape shown. Additionally or alternatively, in examples where the sleeve valve has an umbrella structure or some other internal cavity into which a cooling material can be placed or can flow, sufficient cooling of the valve can be insured in this manner. In application of the present subject matter to a turbocharged engine, it may be desirable to provide both cooling of the stationary part 620 such as a cylinder block and cooling of the sleeve valve 600 itself, in view of the higher pressure and temperature in the exhaust port as compared to a naturally aspirated engine, although both types of cooling could be provided in a naturally aspirated engine if desired.

The arrangement of a seal 626 in a groove 656 as shown in FIG. 6, FIG. 7, and FIG. 8 may be suitable for a naturally aspirated engine. FIG. 9 shows view 900 of an alternative arrangement, which may be suitable for a turbocharged engine. FIG. 9 shows a seal 626 of the type as described above with reference to FIG. 6, FIG. 7, and FIG. 8. However, a distance from the seal 626 towards the proximal end of the sleeve valve body 602 is disposed a further ring 950. The further ring 950 is disposed in a second groove 952, which is sized and shaped for the ring 950 to fit snugly therein. The further ring 950 may be made of metal and may be a flat, split ring. It is configured to have a ring tension which holds it against a moving sleeve valve 600 and its purpose is to form a gas seal. Particularly in a turbocharged engine, the manifold gas pressure may assist in urging the further ring 950 against the sleeve valve and also against the sides of the second groove 952, thereby enhancing resistance to gas leakage. The further ring 950 differs from, for example, a conventional piston ring that resists gas leakage because it is a compression ring which exerts a force inwards i.e. towards a center of its circumference. By contrast, a conventional piston compression ring is arranged to exert a force outwards i.e. away from a center of its circumference so as to urge an outer side of the ring against a cylinder wall.

It may be desirable to use a further ring 950 in a naturally aspirated engine. It may also be useful to use one or two further rings such as the further ring 950 in a turbocharged engine, in order to further improve resistance to gas leakage. This approach can be desirable in a heavily turbocharged engine where the exhaust system pressure is very high relative to the engine internal pressure.

In either of the arrangement of FIG. 6, FIG. 7, and FIG. 8 or that of FIG. 9 or other arrangements having a combination of one or more oil seals and one or more gas seals, a valve spring such as the valve spring 402 shown in FIG. 4 could be present.

The arrangements of FIG. 6, FIG. 7, and FIG. 8 or FIG. 9 can optionally be used in examples where the seal is carried on the sleeve valve, such as the arrangements shown in FIG. 3A, FIG. 3B, and FIG. 4. For example, the seal 326 in FIG. 3A and/or the seal 326a in FIG. 3B could be replaced by the seal 626 of FIG. 6, FIG. 7, and FIG. 8.

FIG. 10 shows a process flow chart 1000 illustrating method features, one or more of which can be included in an implementation of the current subject matter. At 1002, a sleeve valve is cooled and/or lubricated with a liquid, in a manner as described above. The liquid, which can have either or both of cooling and lubricating properties, can be oil in at least some implementations. At 1004, the sleeve valve is operated during a combustion cycle of an internal combustion engine in which it provides a valve function. During some time periods of the combustion cycle, the sleeve valve is stationary, and during other time periods it moves (in a reciprocating motion), to open or close a port. At 1006, the sleeve valve resists leakage of the liquid to the port by action of one or more seals exerting a radial force against the valve body of the sleeve valve i.e. a force directed co-linearly with a radius of the seal, the cylinder, the sleeve valve, etc. A suitable seal can include two rings which are biased apart from one another. The seal may be held in a groove and thus the rings may each be biased against one side of the groove. The groove may be situated within a stationary part of the internal combustion engine, such as an engine block or an oil-path defining piece. Thus, the seal and a valve body of the sleeve valve move relative to one another during the combustion cycle.

It will be understood by those skilled in the art that features of the current subject matter could equally well be applied to a sleeve valve operating to open and/or close one or more ports in an engine in which each piston moves in its own cylinder. Furthermore, it is not essential for the sleeve valve to have an “umbrella” portion, but rather embodiments of the invention are also applicable to the main body of a sleeve valve not having a flange.

In the descriptions above and in the claims, phrases such as “at least one of” or “one or more of” may occur followed by a conjunctive list of elements or features. The term “and/or” may also occur in a list of two or more elements or features. Unless otherwise implicitly or explicitly contradicted by the context in which it used, such a phrase is intended to mean any of the listed elements or features individually or any of the recited elements or features in combination with any of the other recited elements or features. For example, the phrases “at least one of A and B;” “one or more of A and B;” and “A and/or B” are each intended to mean “A alone, B alone, or A and B together.” A similar interpretation is also intended for lists including three or more items. For example, the phrases “at least one of A, B, and C;” “one or more of A, B, and C;” and “A, B, and/or C” are each intended to mean “A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together.” Use of the term “based on,” above and in the claims is intended to mean, “based at least in part on,” such that an unrecited feature or element is also permissible.

The subject matter described herein can be embodied in systems, apparatus, methods, and/or articles depending on the desired configuration. The implementations set forth in the foregoing description do not represent all implementations consistent with the subject matter described herein. Instead, they are merely some examples consistent with aspects related to the described subject matter. Although a few variations have been described in detail above, other modifications or additions are possible. In particular, further features and/or variations can be provided in addition to those set forth herein. For example, the implementations described above can be directed to various combinations and subcombinations of the disclosed features and/or combinations and subcombinations of several further features disclosed above. In addition, the logic flows depicted in the accompanying figures and/or described herein do not necessarily require the particular order shown, or sequential order, to achieve desirable results. Other implementations may be within the scope of the following claims.

SLEEVE VALVE OIL SEAL

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CPC

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