阅读说明：本技术 旋转气门内燃发动机 (Rotary valve internal combustion engine ) 是由 K·拉维斯 B·梅森 于 2019-09-04 设计创作，主要内容包括：本发明提供一种火花点火旋转气门内燃发动机,包括：燃烧室,其部分地由所述活塞和所述气缸的燃烧端部限定；气门壳体,其固定在所述气缸的燃烧端部的外部并且限定出孔；和旋转气门,其能围绕旋转气门轴线在所述气门壳体的孔中旋转,所述旋转气门具有中空气门主体,其在燃烧过程中承受燃烧气体,并且所述中空气门主体还在其壁部中具有端口,在所述气门旋转期间,该端口提供经由所述气门壳体中的进入端口和排出端口相继进出于所述燃烧室的流体连通。所述进入端口和排出端口相对于所述发动机气缸的中心的径向线具有角偏离量。(The present invention provides a spark ignition rotary valve internal combustion engine, comprising: a combustion chamber defined in part by the piston and a combustion end of the cylinder; a valve housing secured to an exterior of a combustion end of the cylinder and defining a bore; and a rotary valve rotatable in a bore of the valve housing about a rotary valve axis, the rotary valve having a hollow valve body which is subjected to combustion gases during combustion and the hollow valve body also having a port in a wall thereof which provides fluid communication successively into and out of the combustion chamber via an inlet port and an outlet port in the valve housing during rotation of the valve. The inlet and outlet ports have an angular offset from a radial line from the center of the engine cylinder.)

1. A rotary valve internal combustion engine adapted for use in a hand held machine, the engine comprising: a piston connected to a crankshaft and reciprocable in a cylinder having a combustion end; a combustion chamber defined in part by the piston and a combustion end of the cylinder; a valve housing secured to an exterior of the combustion end of the cylinder and defining a bore; and a rotary valve rotatable in the bore of the valve housing about a rotary valve axis, the rotary valve having a hollow valve body with an internal volume forming part of the combustion chamber, wherein the internal volume of the hollow valve body is subjected to combustion gases during combustion and the hollow valve body further has a port in a wall thereof providing fluid communication successively into and out of the combustion chamber via an inlet port and an outlet port in the valve housing during rotation of the valve, the engine having a carburettor for controlling the intake/fuel mixture into the engine and the engine having an exhaust muffler for exhaust gases, the port angle being arranged to: the body of the carburetor and the body of the exhaust muffler being located on opposite sides of the engine and being generally parallel to a centerline of the crankshaft, wherein the valve port is angled toward an operator by a predetermined number of degrees when the engine is at top dead center, the angular offset reducing a radial offset of the inlet port necessary to achieve a mounting flange for the carburetor that is generally parallel to the centerline of the engine, the centerline of the inlet port being offset toward the operator by a predetermined number of degrees relative to a radial line relative to the cylinder axis, the angular offset allowing the mounting flange for the carburetor to be generally parallel to the centerline of the engine, and the centerline of the exhaust port being offset by a predetermined number of degrees relative to the cylinder axis and the radial line relative to a radial line, the angular offset allows the body of the muffler to be substantially parallel to the centerline of the engine with an angular flange.

2. A rotary valve internal combustion engine according to claim 1, wherein the radial offset of the inlet port is less than the radial offset of the outlet port.

3. A rotary valve internal combustion engine according to claim 1 or 2, wherein the exhaust muffler has an angular flange which mates with a corresponding mounting of the exhaust port such that the body of the exhaust muffler is substantially aligned with the centre line of the engine.

4. A rotary valve internal combustion engine according to any preceding claim, wherein a deflector directs incoming cooling air around the cylinder and towards the back of the cylinder.

5. A rotary valve internal combustion engine according to any preceding claim wherein a closure plate located behind the engine forces cooling air out from behind the shroud rather than down in a short cycle to the inlet for the cooling air.

6. A rotary valve internal combustion engine according to any one of claims 1 to 5 wherein the engine has a bellows containing a curved tuning tube extending from the intake of the engine into the filtered air volume portion of the bellows.

7. A rotary valve internal combustion engine according to claim 6, wherein the engine has a carburettor and a tuning tube secured to the air intake of the carburettor.

8. A rotary valve internal combustion engine according to claim 6 or 7 wherein the bellows is divided into an unfiltered volume and a filtered volume by a dividing wall, the dividing wall housing a filter through which air passes from the unfiltered volume to the filtered volume, the tuning tube inlet being located in the filtered volume.

9. A rotary valve internal combustion engine according to claim 6, wherein the tuning tube passes from the carburettor through the unfiltered volume and then through the dividing wall into the filtered volume.

10. A rotary valve internal combustion engine according to claim 6, wherein the tuning tube passes through the filter in the dividing wall.

11. A rotary valve internal combustion engine according to claim 6, wherein the tuning tube has a serpentine profile along its length.

12. A handheld garden machine having an engine according to any one of claims 1 to 11.

Technical Field

The present invention relates to a rotary valve internal combustion engine, particularly but not exclusively for a hand-held machine, such as a garden mower or hedge trimmer, in which control of the intake and exhaust of combustion gases is achieved by means of rotary valves.

Background

The rotary valve internal combustion engine includes: a piston connected to a crankshaft and reciprocating in a cylinder having a combustion end; a combustion chamber defined in part by the piston and a combustion end of the cylinder; a valve housing secured to an exterior of a combustion end of the cylinder and defining a bore; and a rotary valve rotatable in a bore of the valve housing about a rotary valve axis, the rotary valve having a hollow valve body with an internal volume forming part of the combustion chamber, wherein the internal volume of the hollow valve body is subjected to combustion gases during combustion, and the valve body further has a port in a wall thereof providing fluid communication successively into and out of the combustion chamber via an inlet port and an outlet port in the valve housing during rotation of the valve.

Disclosure of Invention

The present invention aims to provide such an engine suitable for use in a garden machine designed to be hand-held and manually operated by an operator. The term "garden machine" is intended to include hand-held machines for gardening, gardening and forestry, such as lawn mowers, hedge trimmers, brush cutters, weed saws, shredders, pressurised vacuum collectors, sprayers and chain saws.

According to the present invention, there is provided a rotary valve internal combustion engine comprising: a piston connected to a crankshaft and reciprocating in a cylinder having a combustion end; a combustion chamber defined in part by the piston and a combustion end of the cylinder; a valve housing secured to an exterior of the combustion end of the cylinder and defining a bore; and a rotary valve rotatable in the bore of the valve housing about the rotary valve axis, the rotary valve having a hollow valve body with an internal volume forming part of the combustion chamber, wherein the internal volume of the hollow valve body is subjected to combustion gases during combustion and the hollow valve body further has a port in a wall thereof providing fluid communication successively into and out of the combustion chamber via an inlet port and an outlet port in the valve housing during rotation of the valve, the engine having a carburetor for controlling the intake/fuel mixture into the engine and the engine having an exhaust muffler for exhaust gases, wherein the port arrangement is arranged such that the exhaust muffler and the carburetor are located on opposite sides of the engine, the port angle is arranged such that the body of the carburetor and the body of the muffler are substantially parallel to a centerline of the engine, wherein the valve port is at a predetermined degree of angle relative to the crankshaft axis when the engine is at top dead center, the angular offset reducing a radial offset of the inlet port necessary to achieve a mounting flange for the carburetor, the mounting flange being substantially parallel to the centerline of the engine, a radial line of the inlet port relative to the cylinder axis being offset toward the operator by a predetermined degree, the angular offset allowing the mounting flange for the carburetor to be substantially parallel to the centerline of the engine, and a radial line of the outlet port relative to the cylinder axis being offset by a predetermined degree, the angular offset allows the body of the muffler to be substantially parallel to the centerline of the engine with an angular flange.

Drawings

Preferred embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 shows a cross-sectional view of a single cylinder air-cooled spark-ignited rotary valve internal combustion engine, an

FIG. 2 shows a partial cross-sectional top view of an embodiment of the engine suitable for use in a hand-held and manually-operated garden machine, such as a lawn trimmer or hedge trimmer, and

figure 3 shows a side view of the portion of the engine shown in figure 2,

fig. 4 shows a cross-sectional view of a portion of the engine shown in fig. 1, showing air/fuel intake passages,

figure 5 shows a cross-sectional view of a portion of a single cylinder air-cooled spark-ignited rotary valve internal combustion engine,

figure 6 shows an enlarged schematic view of a part of the rotary valve body and the spark plug,

figure 7 shows a cross-sectional view of a single cylinder air-cooled rotary valve internal combustion engine,

figure 8 shows an enlarged schematic view of a portion of the rotary valve body and drive gear,

figure 9 shows a top view of the rotary valve train and driven gear,

figure 10 shows a cross-sectional view of a single cylinder air-cooled rotary valve internal combustion engine,

fig. 11 shows a cross-sectional view of the engine, showing the dividing line between the cylinder housing and the crankcase,

figure 12 shows a cross-sectional view of a single cylinder air-cooled rotary valve internal combustion engine,

figure 13 shows an enlarged schematic view of a portion of the rotary valve body and drive gear,

figure 14 shows a top view of the rotary valve train and driven gear,

figure 15 shows an enlarged cross-sectional view of the rotary valve train and transmission gears,

figures 16a to 16b show a top view and a side view respectively of a wave spring,

figure 17 shows a view of the valve and driven gear,

figure 18 shows a view of the valve and ball bearings,

fig. 19 shows the escape path of the combustion gas.

Detailed Description

Referring now to FIG. 1, a single cylinder air-cooled engine is shown. The engine has a cylinder housing containing a cylinder 2. The piston 1 is connected in a conventional manner to a crankshaft 3 mounted for rotation in a crankcase 14 for reciprocating movement in the cylinder 2. The upper part of the cylinder 2 is closed by a combustion chamber 4 in a combustion chamber housing. The combustion chamber housing has an inlet port 27 for the inflow of an intake air/fuel mixture into the combustion chamber and an outlet port 28 for the exhaust gases from the combustion chamber 4, which gases are controlled by the rotary valve 5. In the present exemplary embodiment, the valve 5 is rotatable in a valve housing 8 in the combustion chamber housing about an axis 5a, which axis 5a is coaxial with the axis of the cylinder 2. In other embodiments, the axis of rotation of the valve body is offset from the axis 5a of the cylinder 2.

At its end remote from the combustion chamber 4, the rotary valve 5 has a concentric drive shaft 6 which carries a single-track ball bearing 7 which rotatably supports the valve 5 in a valve housing 8. The valve drive shaft 6 is fixed to a coaxial driven gear 9 which meshes with a drive gear 10 of a transmission 11, by means of which transmission the driven gear 9 and thus the rotary valve 5 are connected to the crankshaft 3. The transmission 11 comprises a transmission shaft 12 located in a channel or duct 17 in the cylinder housing and mounted for rotation in an upper bearing 18 adjacent the transmission gear 10 and in a lower bearing 13 adjacent the crankshaft 3. The drive shaft 11 carries a bevel gear 15 which meshes with a corresponding bevel gear 16 fixed to the crankshaft for rotation with the crankshaft 3. Thus, the rotation of the crankshaft 3 and therefore the piston motion is coordinated with the rotation of the rotary valve 5, so that the engine operates in a conventional four-stroke cycle. To achieve this, the diameter of the driven gear 9 is twice the diameter of the transmission gear 10, so that the rotary valve 5 rotates at half the engine speed. The rotary valve 5 comprises a generally cylindrical rotary valve body 5 which is rotatable about a rotary valve axis 5a and which is a close sliding fit in a bore of the valve housing 8, the rotary valve 5 having a hollow valve body with an internal volume 19 forming part of said combustion chamber. The valve has a generally cylindrical body portion comprising the valve body 19 itself, which is slightly larger in diameter than the shaft 6 and forms a shoulder 14 against which the inner race of the ball bearing 7 is located. The valve body 19 extends into the combustion chamber and has a volume 20 in its interior which forms part of the combustion chamber 4 and which is subjected to the combustion gases at all stages of the combustion process.

A portion of the rotary valve 5, i.e. the shaft 6, has a diameter slightly smaller than the diameter of the valve body 19 to provide the shoulder 14. The shaft is solid to provide a good path for heat to be conducted away from the valve body 19 to the outside.

The rotary valve body 19 has a port 21 enabling fluid communication successively into and out of the internal volume of the valve, and hence into and out of the combustion chamber, via an inlet port and an outlet port in the valve housing during rotation of the valve. In the present embodiment, the port 21 is formed in the lower peripheral edge 22 of the wall 23 of the valve body adjacent to the combustion chamber 4 in the form of a recess extending upwardly from the lower edge of the wall of the valve to form the port 21 in the side face of the valve.

Ignition is provided by a spark plug secured to a plug hole 25 formed in the valve housing 8 and extending into the valve hole.

Referring now to fig. 2, there is shown a top view of an engine intended for a garden machine, such as a lawn or hedge trimmer, which is hand-held and operated by an operator, wherein the engine is located to the side of and/or behind the operator. In such machines, it is necessary to locate the exhaust mechanism and exhaust muffler away from the operator and to locate the carburetor for controlling the air/fuel mixture passing through the inlet port towards the operator. This is due to the heat of the exhaust mechanism and the fact that the operator may need to adjust the carburetor. The vaporizer is attached to the inlet port 27 by means of a bellows assembly 29, and an exhaust muffler 30 is connected to the exhaust port 28. Ideally, the carburetor bellows assembly 29 and exhaust muffler 30 should be substantially parallel to the centerline of the crankshaft, and the inlet and outlet ports should be straight, rather than curved, to achieve die casting of the cylinder 2. The straight port and exhaust muffler/carburetor bellows location simplifies manufacturing, provides a neat appearance to the engine, and allows the engine to be easily packaged in typical garden machinery. However, in order to provide correct valve timing for the engine, this would require that the inlet and outlet ports each be angled away from their ideal angle, which is aligned with a radius from the cylinder axis, as determined by the position of the inlet and outlet openings in the valve housing.

Furthermore, any restriction to flow in the inlet port will have a greater effect on engine power than an equivalent restriction to the outlet port due to the non-radial port angle, the angle at which the ports are angled such that the inlet port is closer to the ideal radial angle than the outlet port.

In the present embodiment, the top dead center timing point is at an angle of 10 ° to the centerline of the crankshaft toward the intake port side, in other words, the centerline of the valve port is directed to the side of the engine closest to the operator by 10 ° when the piston is at the top dead center. This enables the inlet port opening in the valve housing to move approximately 10 degrees towards the operator. This brings the inlet port 27 closer to the desired radial angle than the outlet port. The inlet port 27 is then additionally angled at 11 deg. to the radial axis of the cylinder axis with the result that the mounting flange of the carburetor bellows assembly 29 is substantially parallel to the engine centerline.

The centerline of the discharge port 28 is offset from the radial axis 15. The exhaust muffler has an angled flange 33 that mates with the exhaust port 28 to allow the body of the exhaust muffler to be substantially aligned with the centerline 31 of the engine.

The exhaust muffler 13 is a muffler having a two-part shell construction and has a flange that mates with the angled exhaust port. This has the advantage of avoiding the use of a separate pipe or tube between the discharge port and the muffler body.

As shown above in fig. 2, the intake port side of the cylinder has a curved plate 34 for directing cooling air around the cylinder rear to provide a cooling flow around the cylinder rear.

As shown in fig. 3, a closure plate 35 located behind the engine forms the lower interface of the cooling air flow passage, which forces the cooling air out from behind the engine/exhaust pipe shroud, rather than down the cooling air intake in a short cycle.

Referring now to FIG. 4, a cross-sectional view of a portion of the engine shown in FIG. 1 is shown, illustrating air/fuel intake passages. The part of the housing 29 of the engine comprises a bellows 30, also called plenum chamber, which is divided by a wall 33 into an unfiltered air volume, into which ambient air enters via an inlet channel 31, and a filtered air volume 32.

The partition wall 33 contains a filter 34 through which air from the unfiltered side passes into the filtered air side volume 32. The inlet conduit has a tuning tube 35 secured to the vaporizer. The tuning tube 35 extends from the air inlet 36 of the carburetor 28 through a tortuous path through the unfiltered volume in the windbox, through the dividing wall and into the filtered air volume 32. In one form, the tuning tube 35 passes through the filter itself. An inlet 37 to the tuning tube 35 is located in the filter volume 32 and flares outwardly to improve airflow into the tuning tube 35 and hence into the engine. The curved path maximizes the tuning tube length, which increases the efficiency of the engine without causing significant changes in the overall size of the engine.

It should be appreciated that while a simple curvilinear shape is shown, the tuning tube may have a more complex shape and may follow a serpentine path.

Referring now to FIG. 5, a single cylinder air-cooled engine is shown. The engine has a cylinder housing containing a cylinder 102. The piston 101 is connected in a conventional manner to a crankshaft 103 mounted for rotation in a crankcase 114 for reciprocating movement in the cylinder 102. The upper part of the cylinder 102 is closed by a combustion chamber 104 in a combustion chamber housing. The flow of intake air/fuel mixture and exhaust gas into and out of the combustion chamber 104 is controlled by a rotary valve 105. In this embodiment, the valve 105 is rotatable in a valve housing 108 in the combustion chamber housing about an axis 105a, which axis 105a is coaxial with the axis of the cylinder 102. In other embodiments, the axis of rotation of the valve body is offset from the axis 105a of the cylinder 102.

At its end remote from the combustion chamber 104, the rotary valve 105 has a concentric drive shaft 106, said drive shaft 106 carrying a single-track ball bearing 107 which rotatably supports the valve 105 in a valve housing 108. The valve drive shaft 106 is fixed to a coaxial driven gear 109 which meshes with a drive gear 110 of a transmission 111 through which the driven gear 109 and hence the rotary valve 105 are connected to the crankshaft 103. The transmission 111 includes a drive shaft 112 located in a passage or conduit 117 in the cylinder housing and mounted for rotation in an upper bearing 118 adjacent the drive gear 110 and in a lower bearing 113 adjacent the crankshaft 103. The drive shaft 111 carries a bevel gear 115 which meshes with a corresponding bevel gear 116 fixed to the crankshaft to rotate with the crankshaft 103. Thus, rotation of the crankshaft 103, and therefore the piston motion, is coordinated with rotation of the rotary valve 105, such that the engine operates in a conventional four-stroke cycle. To achieve this, the diameter of the driven gear 109 is twice the diameter of the drive gear 110, so that the rotary valve 105 rotates at half the engine speed.

Referring now to fig. 6, there is shown more detail of a rotary valve 105 comprising a generally cylindrical rotary valve body 105 rotatable about a rotary valve axis 105a and closely sliding fit within a bore of a valve housing 108, the rotary valve 105 having a hollow valve body with an internal volume 119 forming part of the combustion chamber. The valve has a generally cylindrical body portion comprising the valve body 119 itself, which is slightly larger in diameter than the shaft 106 and forms a shoulder 14 against which the inner race of the ball bearing 107 is located. The valve body 119 extends into the combustion chamber and has a volume 120 within it which forms part of the combustion chamber 104 and which is subjected to the combustion gases at all stages of the combustion process. The valve body 119 is rotatable in a tight sliding fit in the bore of the valve housing 108. The valve 105 and the valve housing 108 are formed of aluminum.

A portion of the rotary valve 105, i.e., the shaft 106, has a diameter slightly smaller than the diameter of the valve body 119 to provide the shoulder 114. The shaft is solid to provide a good path for heat to be conducted out of the valve body 119 to the outside.

The rotary valve body 119 has a port 121 which enables fluid communication successively into and out of the internal volume of the valve, and hence into and out of the combustion chamber, via an inlet port and an outlet port in the valve housing during rotation of the valve. In this embodiment, the port 121 is formed in the lower peripheral edge 122 of the wall 123 of the valve body adjacent the combustion chamber 104 in the form of a recess extending upwardly from the lower edge of the wall of the valve to form the port 121 in the side of the valve.

Ignition is provided by a spark plug secured to a plug hole 125 formed in the valve housing 108 and extending into the valve hole. The axis of the plug hole 125 is axially below the centerline of each valve port where it contacts the valve body. In this way, the ignition point is closer to the incoming fuel mixture body.

The plug hole is formed by means of a thread, the length of which is just sufficient to secure the plug 124 in the plug hole 125, the remainder of the plug hole 125 comprising a spark plug hole volume 126, the remainder being located between the end of the thread supporting the plug and the opening of the plug hole 125 to the combustion chamber, the holes of the spark plug hole volume being smooth, thereby promoting the feed of the incoming fuel flow and accelerating the flame front from the spark plug into the main volume of the combustion chamber 104.

The plug bore volume 126 is necessarily present because it must be ensured that there is clearance between the spark plug itself and the rotary valve. This does however have the disadvantage that after ignition it forms a pocket for the exhaust gases, which tends to delay the incoming charge/air mixture for the next cycle and also prevents the maximum possible amount of charge/air mixture from reaching the spark plug. To eliminate this drawback, a vent 127 is provided that extends from the plug-hole volume 126 to the main volume of the combustion chamber, so that the plug-hole volume 126 is in fluid communication with the main volume of the combustion chamber 104. This empties the volume 126 before the next input of a fresh fuel charge for the next cycle. As shown in fig. 6, the chimney 127 comprises an aperture in the valve housing that extends from the volume 126 into the combustion chamber 104. In an alternative configuration, the air passage may be formed by a channel or slot formed in the valve housing 108.

The embodiment of fig. 5 and 6 shows a rotary valve internal combustion engine including: a piston connected to a crankshaft and reciprocating in a cylinder having a combustion end; a combustion chamber defined in part by the piston and a combustion end of the cylinder; a valve housing secured to an exterior of a combustion end of the cylinder and defining a bore; and a rotary valve rotatable in a bore of the valve housing about a rotary valve axis, the rotary valve having a hollow valve body with an internal volume forming part of the combustion chamber, wherein the internal volume of the hollow valve body is subjected to combustion gases during combustion and the valve body further has a port in a wall thereof providing fluid communication successively into and out of the combustion chamber via an inlet port and an outlet port in the valve housing during rotation of the valve, wherein the engine is a spark ignition engine, the spark plug being screwed into a plug bore in the valve housing adjacent the valve body, a spark plug bore volume being formed in the plug bore between the plug and the valve body and between the spark plug volume and the main cylinder volume, a breather passage is positioned in the valve housing to exhaust combustion gases in the spark plug volume to the main cylinder volume.

In a preferred form, the air passage comprises a bleed hole in the valve housing or in a channel or groove of the valve housing.

Referring now to FIG. 7, a single cylinder air-cooled engine is shown. The engine has a cylinder housing containing a cylinder 202. The piston 201 is connected in a conventional manner to a crankshaft 203 mounted for rotation in a crankcase 214 for reciprocation in the cylinder 202. The upper portion of the cylinder 202 is closed by a combustion chamber 204 in a combustion chamber housing. The flow of intake air/fuel mixture and exhaust gas into and out of combustion chamber 204 is controlled by rotary valve 205. In the present embodiment, the valve 205 is rotatable in a valve housing 208 in the combustion chamber housing about an axis 205a, which axis 205a is coaxial with the axis of the cylinder 202. In other embodiments, the axis of rotation of the valve body is offset from the axis 205a of the cylinder 202.

At its end remote from the combustion chamber 204, the rotary valve 205 has a concentric drive shaft 206 carrying a single track ball bearing 207 which rotatably supports the valve 205 in a valve housing 208. The valve drive shaft 206 is fixed to a coaxial driven gear 209 which meshes with a drive gear 210 of a transmission 211 through which the driven gear 209, and hence the rotary valve 205, is connected to the crankshaft 203. The transmission 211 includes a transmission shaft 212 located in a channel or conduit 217 in the cylinder housing and mounted for rotation in an upper bearing 218 adjacent the transmission gear 210 and in a lower bearing 213 adjacent the crankshaft 203. The channel or conduit 217 is cast into the cylinder housing. The channel or duct 217 is integrally formed with the cylinder housing, which may be formed by a casting process. The drive shaft 211 carries a bevel gear 215 which meshes with a corresponding bevel gear 216 fixed to the crankshaft to rotate with the crankshaft 203. Thus, rotation of crankshaft 203, and therefore the piston motion, is coordinated with rotation of rotary valve 205, such that the engine operates in a conventional four-stroke cycle. To accomplish this, the driven gear 209 is twice the diameter of the drive gear 210 so that the rotary valve 205 rotates at half the engine speed.

Referring now to FIG. 8, further details of the rotary valve 205 are additionally shown, including a generally cylindrical rotary valve body 205 that is rotatable about a rotary valve axis 205a and that is a close sliding fit in a bore of a valve housing 208, the rotary valve 205 having a hollow valve body with an interior volume 219 that forms a portion of the combustion chamber. The valve has a generally cylindrical body portion comprising the valve body 219 itself, which is slightly larger in diameter than the shaft 206 and forms a shoulder 214 against which the inner race 228 of the ball bearing 207 is located. The valve body 219 extends into the combustion chamber and has a volume 220 within it that forms a part of the combustion chamber 204 and is subjected to combustion gases at all stages of the combustion process. The valve body 219 is rotatable in a tight sliding fit in the bore of the valve housing 208. The valve 205 and the valve housing 208 are formed of aluminum.

A portion of the rotary valve 205, the shaft 206, has a diameter slightly smaller than a diameter of the valve body 219 to provide the shoulder 214. The shaft is solid to provide a good path for heat to be conducted out of the valve body 219 to the exterior.

During rotation of the valve, the rotary valve body port 221, which enables fluid communication successively into and out of the internal volume of the valve, and thus into and out of the combustion chamber, via an inlet port and an outlet port in the valve housing. In this embodiment, the port 221 is formed in the lower peripheral edge 222 of the valve body wall 223 adjacent the combustion chamber 204 in the form of a recess extending upwardly from the lower edge of the valve wall to form the port 221 in the side of the valve.

With further reference to fig. 8 and 9, the connection between the driven gear 209 and the rotary valve 205 is shown. The driven gear 209 is fixed coaxially with the rotary valve 205 by a countersunk screw 230. The driven gear 209 has a concentric recess that receives the outer end of the shaft 206 and the recess has an annular ring/eye 231 that is aligned with the inner race 228 of the ball bearing 207. A small axial clearance 232 is provided between the orifice ring 231 and the inner race 228 to allow a small degree of axial play, which means that the valve 205 is not trapped by the inner race 228 and can therefore move slightly in the radial direction to accommodate any small concentric offset between the bearing 207 and the valve bore in which it rotates.

The correct position of the rotary valve 205 relative to the valve train, which determines the timing of the engine, is achieved by the timing pin 233. The transmission gear 210 has a timing mark 234 indicating that the engine is at top dead center. The driven gear 209 connected to the rotary valve has a timing hole 235 adapted to receive the timing pin 233 and has a corresponding timing hole through which the drive pin is inserted to secure the driven gear 209 to the rotary valve 205 to maintain the rotary valve in its top dead center position. Next, the grub screw 230 is inserted to fix the driven gear 209 to the rotary valve 205 in the correct timing position, and the head of the grub screw 230 engages the end of the timing pin 230, thereby fixing it in place. Other tools, such as washers on the screw 230, may also be used to secure the timing pin 233 in place.

Since the rotary valve has ports 221 cut in its peripheral wall, it will be appreciated that the mass of the valve is not evenly distributed around its periphery and this generates unbalanced forces when the rotary valve is actually rotated. In another embodiment of the engine, a balancing portion or balancing weight is configured on the valve train, in particular by adding material to the driven gear 209 or by removing material in place in the driven gear 209.

The embodiments of fig. 7, 8 and 9 show a rotary valve internal combustion engine comprising: a piston connected to a crankshaft and reciprocating in a cylinder having a combustion end; a combustion chamber defined in part by the piston and a combustion end of the cylinder; a valve housing secured to an exterior of a combustion end of the cylinder and defining a bore; and a rotary valve rotatable in a bore of the valve housing about a rotary valve axis, the rotary valve having a hollow valve body with an internal volume forming part of the combustion chamber, wherein the internal volume of the hollow valve body is subjected to combustion gases during combustion and the valve body further has a port in a wall thereof providing fluid communication successively into and out of the combustion chamber via an inlet port and an outlet port in the valve housing during rotation of the valve, a sealing function being achieved between a body surface of the rotary valve and a continuous surface of the bore of the valve housing, wherein the rotary valve is mounted in the valve housing for rotation by the crankshaft through a gear train comprising a drive gear connected to the crankshaft through a cone drive, the drive gear meshes with a driven gear rotatable about the rotary valve axis, which rotates rapidly with the rotary valve and is positioned in the correct timed position relative to the rotary valve by a locating pin and is secured to the rotary valve by a securing means which also locks the locating pin in place.

Preferably, the driven gear has an unbalance weight to offset the unbalance weight in the rotary valve body.

Referring now to FIG. 10, a single cylinder air-cooled engine is shown. The engine has a cylinder housing containing a cylinder 302. The piston 301 is connected in a conventional manner to a crankshaft 303 mounted for rotation in a crankcase 314 for reciprocation in the cylinder 302. The upper portion of the cylinder 302 is closed by a combustion chamber 304 in a combustion chamber housing. The flow of intake air/fuel mixture and exhaust gas into and out of the combustion chamber 304 is controlled by a rotary valve 305. In this embodiment, the valve 305 is rotatable in a valve housing 308 in the combustion chamber housing about an axis 305a, which axis 305a is coaxial with the axis of the cylinder 302. In other embodiments, the axis of rotation of the valve body is offset from the axis 305a of the cylinder 302.

At its end remote from the combustion chamber 304, the rotary valve 305 has a concentric drive shaft 306 carrying a single track ball bearing 307 which rotatably supports the valve 305 in a valve housing 308. The valve drive shaft 306 is fixed to a coaxial driven gear 309 which meshes with a drive gear 310 of a transmission 311 through which the driven gear 309 and hence the rotary valve 305 is connected to the crankshaft 303. The transmission 311 comprises a drive shaft 312 located in a channel or conduit 317 integrally formed in the cylinder housing and mounted for rotation in an upper bearing 318 adjacent the drive gear 310 and in a lower bearing 313 mounted in the cylinder housing adjacent the crankshaft 303. The channels or ducts 317 are formed in the cylinder housing, which may be formed by a casting process. The drive shaft 312 carries a bevel gear 315 which meshes with a corresponding bevel gear 316 fixed to the crankshaft to rotate with the crankshaft 303. Thus, rotation of the crankshaft 303, and therefore the piston motion, is coordinated with rotation of the rotary valve 305, such that the engine operates in a conventional four-stroke cycle. To accomplish this, the driven gear 309 is twice the diameter of the drive gear 310 so that the rotary valve 305 rotates at half the engine speed.

Referring now also to fig. 11, in which like reference numerals refer to like components, the crankcase 314 has a bore 336 having a diameter slightly larger than the outer diameter of the bevel gear 315 so that when the crankcase is provided with the cylinder housing carrying the transmission, the bevel gear 315 can enter the crankcase to mesh with an associated bevel gear 316 fixed to the crankshaft 314. The upper surface of the crankcase 314 is arranged to cooperate with the lower surface of the cylinder housing assembly when lowered onto the crankcase. The lower bearing 313 is secured in a counterbore 337 formed in the cylinder housing so as to be concentric with the crankcase bore 336, with a small axial clearance provided between the outer race of the lower bearing 313 and the end of the counterbore 337 in which the bearing seats to ensure that the cylinder housing assembly including the transmission 311 can be properly mated with the top surface 314a of the crankcase 314.

In this way, the assembly of the cylinder housing, which comprises the main parts of the rotary valve 305 and the transmission gear arrangement 311, is formed as a sub-assembly for cooperation with the crankcase 314. For final assembly, the pistons carried by the crankcase 314 are fed into the piston bores of the cylinder housing 302, and at the same time the bevel gear 315 is fed through the crankcase bore 336 to complete the engine assembly.

The embodiment of fig. 10 and 11 shows a rotary valve internal combustion engine comprising: a crankcase comprising a crankshaft; a piston connected to the crankshaft and reciprocable in a cylinder of a cylinder housing connected to the crankshaft, the cylinder having a combustion end; a combustion chamber defined in part by the piston and a combustion end of the cylinder; a valve housing located outside of a combustion end of the cylinder and defining a bore; and a rotary valve rotatable in a bore of the valve housing about a rotary valve axis, the rotary valve having a hollow valve body with an internal volume forming part of the combustion chamber, wherein the internal volume of the hollow valve body is subjected to combustion gases during combustion and the hollow valve body further has a port in a wall thereof providing fluid communication successively into and out of the combustion chamber via an inlet port and an outlet port in the valve housing during rotation of the valve, wherein the rotary valve is mounted on bearings fixed in the valve housing for rotation via the crankshaft through a gear train comprising a drive gear connected to the crankshaft via a cone drive, the drive gear meshing with a driven gear rotatable about the rotary valve axis, a driven gear fixed for rotation with the rotary valve, the bevel gear assembly comprising a bevel gear fast in rotation on the crankshaft, in engagement with a bevel gear fixed to one end of a drive shaft mounted for rotation in the cylinder housing, the drive shaft carrying the drive gear at its end opposite the bevel gear, wherein a mating face of the cylinder housing is adapted to mate with a corresponding face on the crankcase, the crankcase incorporating an opening through which the bevel gear on the drive shaft passes into the crankcase to engage the bevel gear on the crankcase when assembled.

In this embodiment, the drive shaft may be positioned in a channel formed in the cylinder housing, and the drive shaft may be positioned for rotation in a bearing mounted in the cylinder housing.

Referring now to FIG. 12, a single cylinder air-cooled engine is shown. The engine has a cylinder housing containing a cylinder 402. The piston 401 is connected in a conventional manner to a crankshaft 403 mounted for rotation in a crankcase 414 for reciprocation in the cylinder 402. The upper portion of the cylinder 402 is closed by a combustion chamber 404 in a combustion chamber housing. The flow of intake air/fuel mixture and exhaust gas into and out of the combustion chamber 404 is controlled by a rotary valve 405. In this embodiment, the valve 405 is rotatable in a valve housing 408 in the combustion chamber housing about an axis 405a, the axis 405a being coaxial with the axis of the cylinder 402. In other embodiments, the axis of rotation of the valve body is offset from the axis 405a of the cylinder 402.

At its end remote from the combustion chamber 404, the rotary valve 405 has a concentric drive shaft 406 carrying a single track ball bearing 407 which rotatably supports the valve 405 in a valve housing 408. The valve drive shaft 406 is fixed to a coaxial driven gear 409 which meshes with a drive gear 410 of a transmission 411 through which the driven gear 409 and hence the rotary valve 405 is connected to the crankshaft 403. The transmission 411 includes a drive shaft 412 located in a passage or conduit 417 in the cylinder housing and mounted for rotation in an upper bearing 418 adjacent the drive gear 410 and in a lower bearing 413 adjacent the crankshaft 403. The channel or duct 417 is cast into the cylinder housing. The channel or duct 417 is integrally formed with the cylinder housing, which may be formed by a casting process. The drive shaft 411 carries a bevel gear 415 which meshes with a corresponding bevel gear 416 fixed to the crankshaft to rotate with the crankshaft 403. Thus, rotation of the crankshaft 403, and therefore the piston motion, is coordinated with rotation of the rotary valve 405, such that the engine operates in a conventional four-stroke cycle. To achieve this, the driven gear 409 has a diameter twice that of the driving gear 410, so that the rotary valve 405 rotates at half the engine speed.

Referring now to fig. 13, further details of the rotary valve 405 are shown, including a generally cylindrical rotary valve body 405 rotatable about a rotary valve axis 405a and closely sliding fit within a bore of a valve housing 408, the rotary valve 405 having a hollow valve body 416 with an internal volume 419 forming a portion of the combustion chamber. The valve has a generally cylindrical body portion comprising the valve body 416 itself, which is slightly larger in diameter than the shaft 406 and forms a shoulder 414 against which the inner race 428 of the ball bearing 407 is positioned. The valve body 416 extends into the combustion chamber and has a volume 420 within it that forms a portion of the combustion chamber 404 and is exposed to combustion gases at all stages of the combustion process. The valve body 419 may rotate in a tight sliding fit within the bore of the valve housing 408. The valve 405 and the valve housing 8 are formed of aluminum.

A portion of the rotary valve 405, i.e., the shaft 406, has a diameter slightly smaller than the diameter of the valve body 419 to provide the shoulder 414. The shaft is solid to provide a good path for heat to be conducted out of the valve body 416.

A rotary valve body port 421 which, during rotation of the valve, enables fluid communication successively into and out of the internal volume of the valve, and hence into and out of the combustion chamber, via an inlet port and an outlet port in the valve housing. In this embodiment, the port 421 is formed in the lower peripheral edge 422 of the wall 423 of the valve body adjacent to the combustion chamber 44 in the form of a recess extending upwardly from the lower edge of the wall of the valve to form the port 421 in the side of the valve.

With further reference to fig. 13 and 14, the connection between the driven gear 409 and the rotary valve 405 is shown. The driven gear 409 is fixed coaxially with the rotary valve 405 by a countersunk screw 430. The driven gear 409 has a concentric recess that receives the outer end of the shaft 406 and the recess has an annular rib 431 that aligns with the inner race 428 of the ball bearing 407. An axial clearance 432 is provided between the ring 431 and the inner race 428 to allow a small degree of axial play, which means that the valve 405 is not clamped by the inner race 428 and can therefore move slightly in the radial direction to accommodate any small concentric offset between the bearing 407 and the valve bore in which it rotates.

In operation, the forces generated by the combustion gases tend to move the valve body axially relative to the valve housing. To prevent impact of the shoulder 414 against the inner race 428 of the bearing 407 caused by axial movement of the valve body 416 relative to the bearing inner race 428, a resilient element in the form of a wave spring 424 biases the driven gear 409 to urge the shoulder 414 of the valve body 416 upwardly and into contact with the lower interface of the inner race 428, which impact would otherwise occur during each combustion cycle, as shown in fig. 15, the two components are prevented from impacting or fluttering during operation by means of sufficient force, but not so strong as to impede slight radial movement of the valve body, which is necessary to accommodate slight misalignment between the valve and the valve housing, which in practice occurs as a result of slight differences caused by manufacturing tolerances of the components.

As shown in fig. 16a and 16b, the wave spring is constructed of a generally annular plate-like body. Throughout its annular length, the wave spring 424 has a plurality of waves that bend the spring outward from a radial plane, as shown particularly in fig. 5b and 5 c. In the present embodiment, the wave spring is formed of spring steel. The spring element may be formed of other materials, designs or profiles as long as the objectives of providing the desired elastic damping effect are met and the harsh environmental conditions in the engine are addressed.

Fig. 17 shows a schematic perspective view of the rotary valve 405 and driven gear 409 with the wave spring 424 seated between the inner race 428 of the bearing and the driven gear 409. Fig. 18 shows a schematic perspective view of a similar rotary valve 405 and driven gear 409 with the single track ball bearing 407 in place. As shown in fig. 19, the space between the inner and outer raceways 428 and 429 of the bearing 407 is closed at the lower edge of the bearing by a metal seal 426.

It has been demonstrated that in practice, some combustion gases escape from the interface between the rotary valve body 405 and the valve housing 408. This wasted combustion gas may pass through the bearing 407, past the balls 425 and into the chamber containing the driven gear and wave spring, causing a build up of carbon dioxide which negatively impacts the performance and durability of the valve, and the high temperature and corrosive effects of the hot gases may cause premature failure of the wave spring. To prevent, or at least reduce, leakage of the combustion gases through the bearing 407, the seal 426 closes the gap between the inner and outer races 428 and 429 of the bearing. The sealing portion is formed of metal to cope with the severe environmental conditions. Furthermore, the seal limits the escaping combustion gases from damaging or destroying the spring.

Referring now to fig. 19, there is shown an enlarged view of the valve and bearing arrangement, wherein the modification is shown that a vent channel 437 from the narrow annular space 428 between the annular metal seal 426 and the valve housing extends into the inlet port, as indicated by black arrow 440. This has the advantage that the escaping combustion gases are supplied to the inlet port 439 and are circulated there through the engine to improve engine emissions performance.

Since the rotary valve has ports 421 cut in its peripheral wall, it will be appreciated that the mass of the valve is not evenly distributed around its periphery and this generates unbalanced forces when the rotary valve is actually rotated. In another embodiment of the engine, a balancing portion or balancing weight is configured on the valve train, in particular by adding material to the driven gear 409 or by removing material in place in the driven gear 409. The embodiment described is a single cylinder air cooled engine but it will be appreciated that the invention is equally applicable to multi-cylinder and/or water cooled engines.

The embodiment of fig. 12 to 19 shows a rotary valve internal combustion engine including: a piston connected to a crankshaft and reciprocating in a cylinder having a combustion end; a combustion chamber defined in part by the piston and a combustion end of the cylinder; a valve housing secured to an exterior of a combustion end of the cylinder and defining a bore; and a rotary valve rotatable in a bore of the valve housing about a rotary valve axis, the rotary valve having a hollow valve body with an internal volume forming part of the combustion chamber, wherein the internal volume of the hollow valve body is subjected to combustion gases during combustion and the valve body further has a port in a wall thereof providing fluid communication successively into and out of the combustion chamber via an inlet port and an outlet port in the valve housing during rotation of the valve, a sealing function being achieved between a body surface of the rotary valve and a continuous surface of the bore of the valve housing, wherein the rotary valve is mounted in the valve housing for rotation by the crankshaft through a gear train comprising a driven gear rotatable about the rotary valve axis, the driven gear rapidly rotates with the rotary valve, and a bearing is disposed between the driven gear and the valve body, the bearing comprising a single bearing, wherein a space between inner and outer races of the bearing is closed by a seal, thereby substantially restricting combustion gas from passing through the bearing.

Preferably, the sealing portion is located at a valve side of the single track ball bearing so that the ball bearing avoids the combustion gas, and the sealing portion may be formed of metal.

In another further aspect, a vent passage may be provided to vent combustion gases from between the valve body and valve housing back to the inlet port, the vent passage being constituted by a bore or groove in the valve bore face.

In another example further aspect, a predetermined axial clearance is provided between the driven gear and the bearing in which the rotary valve is mounted, and the driven gear has an annular rib aligned with the inner race of the bearing, the axial clearance being formed between the annular rib and the inner race of the bearing.

In this embodiment, the seal preferably comprises a resilient annular element which is coaxial with the rotary valve and may be a wave spring.

It should be understood that features of the various embodiments described herein may be combined with each other, unless specifically noted otherwise.

Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Accordingly, the application is intended to be limited only by the claims and the equivalents thereof.