Sleeve valve assembly

A sleeve valve assembly. The assembly includes a valve seat, a sleeve valve and an oil path-defining piece. The sleeve valve includes a distal end with a cavity. The distal end contacts the valve seat when the sleeve valve is located in a closed position. The oil path-defining piece includes an inlet port, an outlet port and a plurality of cooling passages. The flange of the sleeve valve is slidably in contact with the oil path-defining piece such that cooling fluid travelling into the inlet port and through the cooling passages enters into the cavity before exiting out the exit port.

BACKGROUND

An internal combustion engine includes a sleeve valve which fits between the piston and the cylinder wall in the cylinder where it rotates and/or slides. The sleeve valve moves independently from the piston so that openings in the valve align with the inlet and exhaust ports in the cylinder at proper stages in the combustion cycle. One example of such a sleeve valve is shown in U.S. Pat. No. 7,559,298, titled “Internal Combustion Engine,” which is assigned to Cleeves Engines Inc., and is incorporated in its entirety herein.

FIG. 9illustrates a cross-sectional view of a portion of a conventional annular sleeve valve assembly20. The sleeve valve assembly20includes a sleeve valve22, an oil path-defining piece24and a valve seat36. The sleeve valve22has a distal end18with an end surface14, an inner surface21, and an exterior surface23. The oil path-defining piece16includes an oil inlet28, a cooling passage30, and an oil outlet32.FIG. 9shows the sleeve valve22in a closed position as the end surface14is in contact with the valve seat36.

The sleeve valve22reciprocates between an open position and a closed position over the valve seal26. On one side of the seal26is the manifold gas, either intake on one side or exhaust on the other (via port34), and the other side of the seal26is cooling/lubricating oil path27in the oil path-defining piece16. The combustion gases in the cylinder (not shown) heat the inner surface21of the sleeve valve22and, indirectly, the oil seal on the exterior surface23of the sleeve valve22. In this embodiment, the coolant travelling through the cooling passage30is at least a distance t1from the exterior surface23of the sleeve valve22. A typical distance t1is several millimeters away from the exterior surface23of the sleeve valve22.

A conventional sleeve valve is often manufactured from steel. In the instance whereby the sleeve valve22is steel, it is very difficult to effectively cool the end surface14of the sleeve valve22during operation of the engine.

A more efficient cooling system is needed for a sleeve valve design.

SUMMARY

One aspect of the present technology is to provide a sleeve valve assembly with improved cooling features. Providing a sleeve valve assembly that allows cooling fluid to circulate near the tip of the sleeve valve is one way to maximize the cooling efficiency of the assembly. In one embodiment, the sleeve valve assembly includes a sleeve valve with a reentrant cavity at a distal end of the valve. In another embodiment, the sleeve valve assembly includes a sleeve valve having high thermal conductivity characteristics combined with cooling grooves formed in an exterior surface of the sleeve valve. In yet another embodiment, the sleeve valve assembly includes a hollow sleeve valve partially filled with a heat transfer agent.

A sleeve valve having a reentrant cavity at the tip allows cooling fluid circulating within an oil path-defining piece to travel within a close distance to the hottest portions of the sleeve valve. In operation, heat generated within the cylinder heats the inner surface of the sleeve valve. The highest temperatures within the cylinder are at a distal end of the sleeve valve, causing the distal end to be the hottest portion of the valve. The cavity at the tip of the sleeve valve allows cooling fluid to spray the inner surfaces of the valve tip. Thus, cooling fluid is separated from the hottest surfaces of the valve by only the thickness of the valve itself.

A hollow sleeve valve filled with a heat transfer agent provides additional cooling that may be required for high-performance engines. In one embodiment, the cavity in the sleeve valve is partially filled with sodium. When the sodium is subjected to the heat being transferred through the inner sleeve valve wall (from the cylinder), the sodium liquefies and begins to slosh around in the cavity. The liquid sodium draws heat from the inner wall of the sleeve valve. An oil path-defining piece circulates cooling fluid along an exterior wall of the sleeve valve. Cooling fluid flowing along the exterior wall of the sleeve valve draws heat from the exterior wall of the sleeve valve. It also conducts heat to the oil path defining piece.

A sleeve valve with high thermal conductivity characteristics provides a higher heat flux for drawing heat from the hot end of the sleeve valve. In one embodiment, the sleeve valve may comprise an aluminum sleeve valve. Aluminum has a high thermal conductivity and hence is able to dissipate heat quicker than, for example, steel. To reduce the mass of an aluminum sleeve valve and to increase the surface area for cooling, axial grooves are formed in an exterior surface of the sleeve valve. The oil path-defining piece circulates cooling fluid through these grooves.

One embodiment of the present technology is to increase the life of a sleeve valve. In one embodiment, a hardened insert is placed over the sleeve valve. Alternatively, a coating is placed over the tip of the sleeve valve. The insert or coating preferably has a higher hardness than the sleeve valve material itself. The insert and/or coating will prevent or slow down the wear of the sleeve valve. An insert may include impact absorbing features to distribute the impact forces received from the valve seat over a greater surface area.

DETAILED DESCRIPTION

The present technology will now be described in reference toFIGS. 1-8and10-14.FIG. 1illustrates a sleeve valve assembly100. The sleeve valve assembly100includes a sleeve valve102, a central connecting piece104and an oil path-defining piece106. InFIG. 1, the sleeve valve102is shown in a closed position as the end surface110of the sleeve valve102is in contact with the valve seat116.

The sleeve valve102includes a sleeve portion103, an end surface110and a flange112. The sleeve portion103includes an inner surface103A and an exterior surface103B. The sleeve portion103is cylindrical in shape, having an outside diameter OD1, an inside diameter ID1and an axial centerline C-C. The thickness or width t2of the sleeve portion103is therefore half the distance between the outside diameter OD1and the inside diameter ID1.

In theFIG. 1embodiment, the sleeve portion103includes a distal end108(also referred to as the “top end” or “tip”) that transitions into the end surface110and flange112. As will be discussed in more detail later, the end surface110forms a seal with the valve seat116when the sleeve valve102is in a closed position. The flange112extends a distance d1rearward from the end surface110, and includes an interior surface115and an exterior surface117. A cavity114is formed in the sleeve valve tip between the sleeve portion103and the flange112. In particular, the cavity114is defined by the area between the exterior surface103B of the sleeve portion103, an inner wall119(seeFIGS. 4 and 5) of the sleeve valve tip and the inner surface115of the flange112.FIG. 1illustrates that the thickness t2of the sleeve portion103is slightly less than the thickness of the sleeve tip and the flange112. It is within the scope of the technology for the sleeve portion103, the sleeve tip and the flange112to have a uniform width or that the flange112could be thin relative to sleeve portion103.

The central connecting piece104is in the form of a ring having an outer portion105and an inner portion107. The central connecting piece104includes spark plug sleeves (not shown), through which spark plugs can be inserted. The central connecting piece104further defines the valve seat116. An air inlet or exit port10(shown inFIG. 4) is defined between the central connecting piece104on one side and a cylinder block (not shown) on the other side.

The oil path-defining piece106provides two main functions for the sleeve valve assembly100: it defines a cooling fluid path for circulating cooling fluid (e.g., oil) through the assembly, and it acts as a guide for both the sleeve portion103and the flange112. The cooling fluid path in the oil path-defining piece106is defined by an inlet port120, a circumferential grove126, axial grooves128, a collector170and an outlet port122. The inlet port120allows the cooling fluid to enter the oil path-defining piece106and travel towards the exterior surface103B of the sleeve portion103. Cooling fluid exits the port122into the collector170. The circumferential groove126allows the cooling fluid to distribute around the circumference of the sleeve portion103along its exterior surface103B. The axial grooves128are provided in a first guide ring183. The grooves128provide a path from the circumferential groove126to the cavity114. The first guide ring183generally provides a surface for the exterior surface103B of the sleeve portion103to slide along and prevent radial motion of the sleeve valve102(motion orthogonal to arrows A-A). Additional detail of the first guide ring183will be provided later herein with reference toFIG. 3.

The oil path-defining piece106also includes a second guide ring185. The second guide ring185includes a seal groove133between two surfaces145,147. The second guide ring185can provide a guide surface for the flange112. In the instance whereby the second guide ring185does provide a guide surface for the flange112, it is within the scope of the technology for either surface145or surface147to provide a guide surface for the flange112. Alternatively, both surfaces145and147can provide a guide surface for the flange112. A seal within the seal groove133prevents cooling fluid from leaking in to the port10. Additional detail of the second guide ring185will be provided later herein with reference toFIG. 3.

The sleeve valve102is slidably movable to the right and the left relative to the oil path-defining piece106, as shown by arrows A-A. Movement of the sleeve valve102to the right (from theFIG. 1perspective) opens the port10. Movement of the sleeve valve102to the left closes the port10, and the end surface110of the sleeve valve102forms a seal with the valve seat116.

IfFIG. 1represents the sleeve valve closed during ignition, the internal volume of the sleeve valve102has been filled with pressurized air and fuel, typically vaporized petroleum. The fuel is ignited, which causes combustion, and an increase in pressure within the internal volume of the sleeve valve102. At this instance, the sleeve portion103is subjected to the highest pressure and temperatures during the cycle. In particular, the sleeve tip or distal end108is subjected to the highest temperatures. After ignition, the internal volume of the cylinder expands (piston moves to the right, not shown) due to the increased pressure of combustion. The expansion causes a reduction in pressure and temperature within the internal volume of the sleeve valve102. Thus, the temperature gradient that the inner surface103A of the sleeve portion103is subjected to is hottest at the distal end108and the temperature of the inner surface103A lessens down the sleeve portion103(away from the distal end108). Accordingly, circulating cooling fluid over the hottest portion of the sleeve valve102(e.g., distal end108) provides efficient cooling.

In operation, the cooling fluid is effectively sprayed or jetted from the grooves128into the cavity114. Thus, the cooling fluid contacts or covers the exterior surface103B of the sleeve portion103, the inner surface119(FIGS. 4 and 5) of the tip of the valve102and the inner surface115of the flange112before the cooling fluid drains out of the cavity114into the collector170(and eventually exiting out the port122). The cooling fluid within the cavity114is therefore separated from the inner surface103A of the sleeve portion103by only the thickness t2of the sleeve portion103. By way of example only, the thickness t2of the sleeve portion103may comprise a distance between 1-3 mm. Similarly, the cooling fluid within the cavity114is separated from the end surface110of the valve102by only the thickness of the sleeve tip. The cavity114provided in the sleeve valve tip drastically reduces the distance between the cooling fluid and the hottest portions of the sleeve valve102; greatly increasing the heat transfer rate of the assembly100over conventional sleeve valve designs.

FIG. 1illustrates that the flange112extends rearward from the end surface110a distance d1. The length d1of the flange112may vary. As will be described in more detail later, the flange112provides several functions. The exterior surface117of the flange112is slidably in contact with the second contact surface147of the second guide ring185of the oil path-defining piece106. The exterior surface117of the flange112is preferably not in slidable contact with the first contact surface145as there is no lubrication between the exterior surface117of the flange112and the first contact surface145. To prevent cooling fluid from leaking out from the collector170along the exterior surface117of the flange112into the port10, a seal130(shown inFIG. 5) is seated with a channel133located between the first and second contact surfaces145,147.

FIG. 2illustrates the sleeve valve102in an open position. As shown inFIG. 2, the sleeve valve102has moved rearward a distance d4away from the valve seat116. The seal130maintains contact with the exterior surface117of the flange112as the sleeve valve102moves rearward. As the sleeve valve102moves rearward, the distal end108of the sleeve valve102moves towards the seal130. As discussed above, the distal end108is a hot portion of the sleeve valve102during operation of the engine. Thus, the seal130travels over a hotter portion of the sleeve valve102as it opens. By way of example only, the seal130is within 1 to 3 mm of the end surface110when the valve102is located in the open position shown inFIG. 2(as opposed to approximately 1.5 cm away when the valve102is located in the closed position shown inFIG. 1). These distances are exemplary only.

The length d1of the flange112should be long enough so that the flange112always remains in contact with the seal130. In the instance where the first guide ring183provides the guide surface (e.g., guide off exterior surface103bof the sleeve portion103), surfaces145and147likely will not contact the exterior surface117of the flange112. Instead, the surface145is proximate to the exterior surface117of the flange112to minimize or prevent exhaust gas from exiting and surface147is proximate to the exterior surface117of the flange112to support and locate the seal130of the second guide ring185. The flange112should not be so long that the rim119(FIGS. 4 and 5) of the flange112contacts the rear wall171of the collector170when the valve102is located in the open position (FIG. 2).FIG. 2also illustrates that a gap exists between the inner surface115of the flange112and the bottom surface173of the collector170to allow the cooling fluid to flow during all aspects of operation of the sleeve valve102and to prevent mechanical damage to the assembly. Additional details of the cooling fluid path are provided herein with regard toFIGS. 4-8.

FIG. 2illustrates that the end surface110includes a first surface111and a second surface113. As will be discussed in more detail later, the shape or configuration of the end surface110preferably mirrors the shape of the valve seat116.

FIG. 3provides additional detail of the oil path-defining piece106.FIG. 3illustrates that the oil path-defining piece106includes a body180, a first guide ring183and a second guide ring185. The body180includes the inlet port120, which allows the cooling fluid to travel into the circumferential groove126. The body180also defines a collector170and the outlet port122. The first guide ring183includes multiple cooling grooves128, each having an inlet128A and an outlet128B. Cooling fluid that enters the circumferential groove126exits into the cooling grooves128. The raised surfaces141formed between the grooves128provide a guide surface for the exterior surface103B of the sleeve portion103as the valve102moves between an open position and a closed position. The raised surfaces141also act as a flow restrictor to insure that cooling fluid distributes around the circumferential groove126and subsequently passes through the cooling grooves128with enough velocity to impinge on the inner surface119of end wall110. The cooling grooves128provide a path for the cooling liquid to travel from the circumferential groove126, along the exterior surface103B of the sleeve valve portion103, and into the cavity114in the distal end108of the sleeve valve102. The first guide ring183has an inside diameter substantially equal to the outside diameter OD1of the sleeve portion103.

FIG. 3illustrates one configuration of the cooling grooves128in the guide ring183. The cooling grooves128are not limited to theFIG. 3configuration. The guide ring183may include more (or fewer) cooling grooves128than shown inFIG. 3, and the cooling grooves128may comprise a different shape (e.g., square cross-section, etc.). The grooves128may also have a larger or smaller diameter than that shown inFIG. 3. The length of the grooves128may also vary. The grooves128shown inFIG. 3are axially aligned with respect to the centerline C-C of the sleeve valve102. The grooves128may also be oriented at an angle with respect to the centerline C-C of the sleeve valve102.

The second guide ring185provides guidance for the flange112. The inside diameter of the guide ring185is preferably substantially similar to the outside diameter of the flange112. As discussed above, the guide ring185also maintains a seal with the exterior surface117of the flange112(via seal130) to prevent cooling fluid from leaking into the port10.

FIGS. 4-8illustrate various configurations of a sleeve valve and oil path-defining piece.FIG. 4illustrates a variation of the sleeve valve assembly100shown inFIGS. 1-2, with the sleeve valve102in a closed position. In theFIG. 4configuration, the exterior surface117of the flange112does not directly contact the surface146of the oil path-defining piece106during operation. In addition, the seal130travels with the flange112to remain a fixed distance from the end surface110of the sleeve valve102.

FIG. 4illustrates that two protrusions132extend upward from the exterior surface117of the flange112. The distal end of each protrusion132is proximate to the surface146of the oil path-defining piece106. In one embodiment, the distal ends of the protrusions132have clearance with the surface146and support the seal seated between the protrusions132.

One advantage of theFIG. 4configuration is that the seal130remains a fixed distance from the end surface110of the sleeve valve102. As the sleeve valve102opens (moves to the right), the seal130moves to the right with the flange112. Thus, the seal130does not slide over the hottest portion of the flange112(towards the end surface110). Exposing the seal130to high temperatures may degrade the life of the seal130. Thus, maintaining the seal130a fixed distance from the end surface110of the sleeve valve102may increase the life of the seal130. Each protrusion132has a height h1. The height h1of the protrusions132reduces the available height h2of the cavity114; effectively decreasing the volume of the cavity114.

FIG. 4illustrates that the cooling fluid flows (shown by dashed-lines with arrows) within the sleeve valve assembly100from right to left as the fluid enters the inlet port120and exits the outlet port122(from theFIG. 4perspective). Alternatively, the fluid flow can be reversed (e.g., inlet port120and outlet port122are reversed).FIG. 4also illustrates that the thickness of the sleeve portion103is greater than the thickness of either the tip of the valve or the flange112. As discussed above, the sleeve portion103likely requires a greater thickness to provide adequate stiffness characteristics. As the cooling fluid sloshes within the cavity114, the cooling fluid is cooling the exterior surface103B of the sleeve portion103, the inner surface115of the flange112and the inner surface119of the sleeve tip.

FIG. 5provides additional detail of the sleeve valve102, connecting piece104and oil path-defining piece106shown inFIGS. 1-2.FIG. 5illustrates the sleeve valve102in a closed position, whereby the end surface110of the sleeve valve102is in contact with the valve seat116.FIG. 5illustrates that the inner wall119of the sleeve tip forms an angle θ with the exterior surface103B of the sleeve portion103. The angle θ may comprise any angle between 30-90 degrees, and in one embodiment comprises 45 degrees.FIG. 5also illustrates the height h3of the cavity114. The increased height of the cavity causes the exterior surface117of the flange112to form a seal with the surfaces145,147of the oil path-defining piece106. The height h3shown inFIG. 5is larger than the height h2shown inFIG. 4because the gap h1that existed between the flange112and the oil path-defining piece106has been eliminated. Increasing the volume of the cavity114increases the amount of cooling fluid that may circulate through the cavity114. Increased circulation of cooling fluid in the sleeve valve tip provides better cooling characteristics of the assembly shown inFIG. 5(e.g., removes more heat from the sleeve portion103exposed to the high temperatures within the cylinder) and allows less restrictive drains.

The seal130seated in the channel133is stationary, and does not move with the flange112. As the sleeve valve102moves to an open position (seeFIG. 6), the exterior surface117of the flange112travels over the seal130. Bringing the distal end108of the flange112closer to the seal130subjects the seal130to higher temperatures because, as discussed above, the flange112is hottest at the distal end108.

FIG. 6illustrates that a gap g1is maintained between the inner surface115of the flange112and the bottom surface173of the collector170when the sleeve valve102is located in the open position. The gap g1allows the cooling fluid to exit from the cavity114, into the collector170, and exit via the port122. In one embodiment, the gap g1comprises a distance between 1-3 mm. The gap g1may vary, and comprise other distances as well.

FIG. 7illustrates another embodiment of a sleeve valve assembly. The sleeve valve assembly200shown inFIG. 7includes a sleeve valve202, a connecting piece104and an oil path-defining piece206. The connecting piece104is substantially similar to the configuration shown inFIG. 4-6, whereby the connecting piece104includes a valve seat116.

The sleeve valve202includes a top or distal end208and a second end209, and has an inner surface203A and an exterior surface203B. The distal end208of the sleeve valve202forms an end surface210, which forms a seal with the valve seat116, as shown inFIG. 7. The end surface210includes a first section210aand a second section210b. The first section210amay be located radially inward of the second section210b(i.e., closer to the central axis C,FIG. 1). The first section210amay be provided at an oblique angle with respect to the central axis, and may mate with a portion of seat116having a similarly formed oblique angle. The respective angles of the portion210aand seat116may be approximately the same. Alternatively, the angle of the first portion210amay be more oblique than the angle of the corresponding portion of the seat116so that, when the first portion210amates against that portion of the seat116, the radially innermost tip of portion210acontacts the seat116first.

Providing the seal at a radially inner portion of the seat limits the area of end surface210exposed to the combustion gas pressure. Gas pressure on end surface210tends to lift the valve off the seat. In particular, if the seal is made radially farther out between end surface210and seat116, it increases the force with which the gas attempts to push the valve away from the seat. Thus, providing the seal between the seat116and a radially innermost portion of end surface210reduces the force with which the distal end208is biased away from the seat116. A spring may be used to bias the sleeve valve and hold the distal end208against the seat116. Providing the seal at a radially inner diameter of the end surface210reduces the force with which the spring needs to hold the sleeve valve against the seat116. The seal may be made anywhere along the interface between the end surface210and the seat116in further embodiments. The distal end208has a thickness or width t3and the second end of the valve202has a thickness or width t4, which is thinner than the thickness t3of the distal end108. As shown inFIG. 7, the distal end208does not have a cavity in the sleeve tip.

The oil path defining piece206includes one or more inlet ports220and a circumferential groove248. The circumferential groove248allows the cooling fluid to distribute around the circumference of the sleeve portion203along its exterior surface203B. The oil defining piece206further includes a seal groove233. A seal230is seated within the groove233, and is located between a first surface245and a second surface247. The seal230prevents cooling fluid from leaking between the exterior surface203B of the sleeve valve202and the second surface245into the port10.

The exterior surface203B of the sleeve valve202has been machined to create axial grooves228around the circumference of the valve202. Each groove has a first end228A and a second end228B. Using the first guide ring183as an example (shown inFIG. 3), the exterior surface203B of the sleeve valve202appears similar to the first guide ring183; the exterior surface203B of the sleeve valve202has multiple grooves228with raised surfaces like141between the grooves228. The exterior surface203B of the valve202is in slidable contact with the surfaces,247and249of the oil path-defining piece206.

Compared to theFIG. 4-6embodiments of a sleeve valve with a cavity114in the tip of the valve, the sleeve valve202shown inFIG. 7does not have any means for distributing the cooling fluid as close to the distal end208of the sleeve valve202. A valve with a solid tip also potentially creates a valve having a larger mass. The sleeve valve202shown inFIG. 7likely comprises a lighter material than the sleeve valves shown inFIGS. 4-6to offset the larger mass of the distal end208(and maintain a substantially similar weight). In one embodiment, the sleeve valve202is aluminum. The mass of an aluminum sleeve valve202(as shown inFIG. 7) is substantially the same as the mass of a steel sleeve valve102(withFIG. 4configuration) even though the weight of the distal end208of the valve202is likely greater than the tip of the sleeve valve102.

The material stiffness of aluminum is one-third that of steel. Thus, the thickness t3of the distal end of the sleeve valve needs to be substantially three times greater than the thickness of a steel sleeve valve. However, because the mass of aluminum is approximately one-third that of steel, the resultant sleeve valve is the same weight as a steel sleeve valve. There are several advantages using aluminum over steel. Aluminum conducts heat approximately two times better than steel. Thus, an aluminum sleeve valve having a distal end with a thickness t3removes six times as much heat as a steel sleeve valve having a thickness t2. In addition, the sleeve portion212can be machined away to form fins to increase the surface area away from distal end208. Reducing the thickness of the sleeve portion212is possible because the pressure inside the cylinder is lower as the piston moves away from the distal end208. The fins help transfer more heat into the cooling fluid.

To lighten the mass of the sleeve valve202,FIG. 7illustrates that a portion of the exterior surface203B has been removed to form cooling grooves228; reducing the thickness of a portion of the valve202with a thickness t4. The length of the cooling grooves228may vary.FIG. 7illustrates that, when the sleeve valve202is in a closed position, the cooling grooves228do not extend into the seal230. In other words, the exterior surface203B of the sleeve valve202, at the distal end208, always remains in contact with the seal230during operation.

Cooling fluid travels into the inlet port220in the oil path-defining piece206and into a first end228A of the cooling grooves228. The cooling fluid travels within the cooling grooves228towards a second end228B of the cooling grooves228, which provides an outlet port for the cooling fluid. Forming cooling passages228into the exterior surface203B of the sleeve valve202brings the cooling fluid as close as possible to the inner surface203A of the sleeve valve202, which is the surface that is subjected to the highest heat from within the cylinder. Reducing the distance t4to a minimum acceptable distance reduces the distance the heat from within the cylinder must travel before being exposed to the cooling fluid. The same is true with respect to the distal end208of the valve202, which is subjected to the highest temperatures within the cylinder

The distal end208of the sleeve valve202is subjected to the higher pressures from within the cylinder than the body portion209of the sleeve valve202. A sleeve valve202with a thicker distal end208provides the higher stiffness characteristics required at the distal end208. In the instance of an aluminum sleeve valve202(instead of steel), the thickness t4of the sleeve valve202may have to be greater than the thickness t2of the sleeve portion103of a conventional sleeve valve for stiffness reasons. For example, the thickness t4of an aluminum sleeve valve may be required to be approximately three times thicker than the thickness t2of the sleeve portion103shown inFIG. 1. The thickness t4of the sleeve valve202may vary. The sleeve valve202may comprise other high thermal conductivity materials such as, but not limited to, copper berilium, metal matrix composites, various Al alloys, and the like.

One advantage of an aluminum sleeve valve is that aluminum has a significantly higher thermal conductivity than steel. Even though the surface area exposed to the heat within the cylinder (area of inner surface203A) is equal to the surface area of the valve102shown inFIG. 1, in combination with the larger cross-sectional area of the valve202, more heat can be drawn out of the sleeve valve202. One disadvantage of aluminum is the material's low hardness at high temperatures. This material property of aluminum might lead to excessive wear of the end surface110from the valve seat116, reducing the life of the sleeve valve202.

An insert or coating may be placed over the end surface210of the sleeve valve202(or sleeve valve102) to prevent excessive wear of the end surface210. Additional details of inserts and coating will be provided later herein in reference toFIG. 10-14.

FIG. 8illustrates a sleeve valve assembly300. The sleeve valve assembly300includes a sleeve valve302, a connecting piece304and an oil path-defining piece306. The sleeve valve302shown inFIG. 8is hollow. The valve302has a cavity336defined by an exterior wall308, an inner wall310, a first end wall312and a second end wall314. The first end wall312includes an exterior surface316having a first surface311and a second surface313. The connecting piece304defines a valve seat116.

The oil path-defining piece306includes an inlet port320, cooling grooves328and an exit port322. The oil path-defining piece306further includes a circumferential groove333(shown with a seal130seated in the groove333) in between first and second surfaces345,347. Using theFIG. 3example of the guide ring183, the portion of the oil path-defining piece306with grooves328may appear similar to the guide ring183(e.g., grooves328are machined into an interior surface346of the oil path-defining piece306). In this instance, the exterior surface308A of the exterior wall308is in slidable contact with the interior surface346of the oil path-defining piece306. The portion of the oil path-defining piece306with the surfaces345,347and the groove333may appear similar to the surfaces145m147and groove133shown inFIG. 3. In this case, the exterior surface308A is in slidable contact with the surfaces,347, and the seal330prevents oil from leaking out into the port10.

The sleeve valve302is shown in an open position inFIG. 8. As shown inFIG. 8, the seal330travels over the distal end308of the valve302when the valve302moves to the open position. As discussed above, the distal end of a valve is the hottest portion of the valve and therefore, the seal330inFIG. 8will be subjected to the higher temperatures of the valve302. The cooling fluid travelling through the grooves328does not travel particularly close to the distal end308or the inner wall310of the valve302.

However, the cavity336within the sleeve valve302valve is partially filled with a material that has good heat transfer characteristics and is liquid at operating temperatures. One such material that could partially fill the cavity336is sodium. In this instance, the sodium within the cavity336transforms into a liquid form when exposed to the heat of the inner wall310, and begins to slosh back and forth in the cavity336as the sleeve valve302moves between the open and closed positions. The molten or liquid sodium draws heat from the inner wall310and the first end wall312of the valve302. Sodium is one exemplary material, and is not intended to limit the scope of this technology. Other materials may partially fill the cavity336of the sleeve valve302.

The molten sodium within the cavity336transfers heat to each of the walls of the valve302. The cooling liquid travelling within the grooves328is in direct contact with the exterior wall308of the valve302. Thus, the cooling fluid draws heat out of the exterior wall308and creates a heat differential that draws heat from the molten sodium metal towards the exterior wall308. One instance whereby the sleeve valve assembly300shown inFIG. 8is applicable is use in high-performance engines. The sleeve assembly300may be used in other engines as well.

FIGS. 10-14illustrate various embodiments of inserts and coatings to enhance the durability of a sleeve valve. The sleeve valve shown inFIGS. 10-14generally coincides with sleeve valve202shown inFIG. 7. Sleeve valve202is exemplary only, and is not intended to limit the scope of the technology described herein. The inserts and coatings described herein may be used in conjunction with any other sleeve valves.

In general, the repeated opening and closing of a sleeve valve causes the end surface210or valve tip to repeatedly slam into the valve seat116. This repeated contact with the valve seat116causes the end surface210to wear and deform over time. Eventually, the end surface210will not form an effective seal with the valve seat116when the sleeve valve202is located in the closed position. Two components contributing to the wear of a sleeve valve are (i) the speed at which the sleeve valve slams into the valve seat, and (ii) the hardness of the sleeve material. The repeated impacts of the sleeve valve against the valve seat causes rubbing/scraping of the two surfaces (surface213of for exampleFIG. 10and valve seat116of for exampleFIG. 4) and/or incrementally compacts the material itself.

FIG. 10illustrates an insert250that is placed completely over the end surface210, and partially over the surfaces203A and203B of the sleeve valve202shown inFIG. 7. The insert250forms a hardened sleeve tip having an exterior member251and an interior member253. The insert250may be affixed to the sleeve valve202by several different methods including, but not limited to, cast in place, swaged forged shrink fit (e.g., assemble when hard material is hot and Al is very cold), and the like. In one embodiment, the surfaces211,213,203A and203B have been machined in preparation for the insert250; forming a seat to place the insert250within. Alternatively, the insert250may be affixed directly over the surfaces211and213. The front of the insert250shown inFIG. 10mirrors the surfaces211and213of the sleeve valve202. Thus, in theFIG. 10embodiment, the contact surface255of the insert250forms a seal with the valve seat116when the valve202is located in a closed position.

The insert250preferably comprises a material having a hardness sufficient to withstand the repeated impact with the valve seat116without deforming the surface255. By way of example only, carbon steel may comprise one such material. Other materials may include, but are not limited to, tool steels, traditional poppet valve steel or titanium alloys, copper berilium, and the like.

The insert250wraps around the end surface210of the valve202to form the exterior member251. The exterior member251extends a distance X1along the outer surface203B of the sleeve valve102. By way of example only, the distance X1may comprise a distance between 1 mm-10 mm. The surface257of the exterior member251is preferably flush with the exterior surface203B so as to not interfere with the range of motion of the sleeve valve202during operation. For example, if the sleeve valve202shown inFIG. 10replaces the sleeve valve shown inFIG. 6, it is preferable that the insert250does not interfere with the sleeve valve's ability to move the fully-open position shown inFIG. 6(e.g., the surface257of the insert250should not be raised and strike the oil path-defining piece106). The inner member253of the insert250extends along the inner surface203A of the sleeve valve202by a distance X2. The distance X2may comprise any distance. By way of example only, the distance X2comprises between 1 mm-3 mm.FIG. 10shows that the distance X2is shorter than the distance X1, but this is not a required feature of the insert250.

As discussed above, the surface255of the insert will be repeatedly slammed into the valve seat116at high speeds. This subjects the surface255to high impact forces. Extending the insert250along the exterior surface203B and along the inner surface203A increases the total surface area of the insert250(as opposed to simply covering the end surface210with the insert250). Increasing the surface area of the insert250distributes the impact forces (from striking the valve seat) received by the surface255over a larger area, which provides more area for impact energy dissipation and interference of retention.FIG. 10illustrates that the insert250has a uniform thickness. Alternatively, one or more of the surface of the insert250may comprise a different width or surface area.

FIG. 11illustrates another embodiment of an insert280. The insert280includes a first member282and a second member284. The first member282of the insert280has a distal end surface285which effectively replaces the contact surface213of the sleeve valve202shown inFIG. 7. The distal end surface285of the first member282is flush with the inner surface203A of the sleeve valve202, but could be extended likeFIG. 14. The surface211of the sleeve valve202, which does not contact the valve seat116, is not covered by the insert280so that the wrap around of211provides retention of280. The second member284of the insert280extends inward into the distal end208of the sleeve valve202a distance X3. The distance X3may vary.

The second member284of the insert280increases the total surface area of the insert280, which distributes the impact forces received by the insert280over a larger area (as opposed to the insert280simply covering the surface113) and provides more area for the impact forces to dissipate. One advantage to the insert280shown inFIG. 11is that the insert280does not extend along the exterior surface203B of the valve202. Thus, the insert280cannot interfere with the operation of the valve202(e.g., the insert280will not strike the oil path-defining piece106or interfere with the seal staying smoothly in contact with one surface).

FIG. 12illustrates a sleeve valve202with a coating290on the end surface210. In one embodiment, the coating290comprises a chrome plating. Alternatively, the end surface210may be anodized to form an aluminum oxide coating. Other materials that may be used include, but are not limited to, Nikasil, diamond like carbon, flame sprayed hard metal, ceramic materials, and the like.

FIG. 12illustrates that the coating290completely covers the end surface210of the sleeve valve202(e.g., the first surface211and the second surface213). Alternatively, the coating290may be formed over only the surface213, which is the surface that strikes the valve seat116. Similar to the inserts discussed above, the coating290is preferably a harder material than the sleeve valve202itself to increase the life of the sleeve valve202. The coating290is intended to prevent or slow down the wear of the sleeve valve202due to the constant rubbing and/or scraping between the end surface210of the sleeve valve202and the valve seat116during operation. The thickness of a coating may vary, and is dependent on the type of coating material. By way of example only, an anodized coating may comprise 1-10 microns while a plated or sprayed material may comprise up to 100 to 200 microns.

FIG. 13illustrates another embodiment of the insert250shown inFIG. 10. InFIG. 13, the top member251of the insert250extends along the exterior surface203B of the sleeve valve202by a distance X4. The distance X4is greater than the distance X2shown inFIG. 10. In one embodiment, the top member251of the insert250extends along substantially the entire exterior surface203B of the sleeve valve202up to the groove228.

One advantage of the insert250shown inFIG. 13is that the top member251of the insert250covers the entire (or substantially the entire) contact surface between the sleeve valve202and the seal of the oil path-defining piece206(shown inFIG. 7). In operation, a sleeve valve202without the insert250, experiences wear along the exterior surface203B due to the sliding contact with the seal of the oil path-defining piece206. Adding the insert250shown inFIG. 13places a harder surface (top member251) in slidable contact with the seal of the oil path-defining piece206. This harder surface251will not wear at the same rate as the sleeve material, if at all; effectively extending the life of the sleeve valve202.

FIG. 14illustrates an insert400. InFIG. 14, the insert400includes an exterior member402, a front member404and an impact energy absorbing structure410. The top member402extends along the exterior surface203B of the sleeve valve202a distance X5. Similar toFIG. 13, the top member402extends along substantially the entire exterior surface203B of the sleeve valve202up to the groove228. The front member404defines a contact surface408that forms a seal with the valve seat116when the sleeve valve202is located in a closed position.

FIG. 14shows that the front member404includes a tip408that extends down into the cylinder and protrudes out past the inner surface203A of the sleeve valve202. The distance the front member404extends into the cylinder may vary. By way of example only, the distance may comprise between 1-10 mm.FIG. 14also illustrates that the front member404of the insert400forms an angle Φ with respect to the inner surface203A of the sleeve valve. The angle Φ may comprise any angle between 15-55 degrees, and in one embodiment comprises 45 degrees. The tip408includes an inner surface409and an outer surface411, and forms a lip at the distal end208of the sleeve valve202. When the piston (not shown) compresses air within the combustion chamber, with the sleeve valve202in a closed position, a positive pressure differential is created between the inner surface409and the outer surface411of the tip408. The positive pressure differential further assists in keeping the tip408sealed against the valve seat116.

The impact energy absorbing structure410increases the total surface area of the insert400. As described above, increasing the total surface area of an insert helps to distribute and dissipate the impact forces received from the valve seat116impacting the insert.

The foregoing detailed description of the inventive system has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the inventive system to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. The described embodiments were chosen in order to best explain the principles of the inventive system and its practical application to thereby enable others skilled in the art to best utilize the inventive system in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the inventive system be defined by the claims appended hereto.