GB2453593A

GB2453593A - Turbo valve gas seal system for i.c. engine rotary valve

Info

Publication number: GB2453593A
Application number: GB0720009A
Authority: GB
Inventors: Gordon Mcnally
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-10-12
Filing date: 2007-10-12
Publication date: 2009-04-15
Also published as: CN101896695A; KR20100080558A; MX2010003996A; WO2009047566A1; EP2222941A1; JP2011501012A; TW200928077A; GB0720009D0; US20100236514A1; AU2008309310A1

Abstract

A gas seal between a port (10, 12, fig.1) of a rotary valve (7) and a port 8 in a combustion chamber 6 of a rotary valve engine comprises gas channel means, eg a circular groove 15, which is supplied with gas under pressure to form a turbo valve 26 surrounding the port 8. Compression means creates a pressure in the gas channel means greater than a pressure in the combustion chamber 6 during a compression stroke and a power stroke of the engine. The pressurised air may be supplied to the groove 15 by a crankshaft-driven compressor or by crankcase compression charging an air storage chamber (21, fig.6). The air is forced tangentially, eg by a turbo valve injector 25, into the groove 15 where it circulates at high speed and at a pressure higher than that in the combustion chamber 6. The rotary valve rotor may be water-cooled.

Description

Seal for a rotary valve for an internal combustion engine This invention relates to a seal for a rotary valve for an internal combustion engine.

Known commercially available internal combustion engines have changed little in principle since their invention in 1 892. Although there have been many variations of engine, they have all used similar principles.

A known four-stroke engine includes a cylinder block comprising at least one cylinder bore in which a piston may reciprocate, a crankcase rotatably supporting a crankshaft connected to the piston via a con rod and a cylinder head containing a valve mechanism comprising an inlet valve and an outlet valve opening to the cylinder bore. As the crankshaft rotates, the piston reciprocates within the cylinder bore. Rotation of the crankshaft also causes rotation of a camshaft within the cylinder head that, using one of a variety of mechanisms, opens and closes the inlet and outlet valves in the cylinder head.

On an induction or intake stroke, the piston travels along the cylinder bore in a direction away from the valve mechanism with the inlet valve open. A partial vacuum created in a combustion chamber within the cylinder bore between the piston and the valve mechanism draws a mixture of vaporised fuel and air into the cylinder bore from, for example, a carburettor.

On a return stroke the piston travels back along the cylinder bore towards the valve mechanism with the inlet valve now closed, compressing gas within the combustion chamber between the piston and an end of the bore at which the inlet and outlet valves are located.

As the piston reaches an end of its reciprocating motion along the cylinder bore towards the inlet and outlet valves, ignition takes place igniting the compressed fuel and air mixture. This generates a power stroke pushing the piston in a direction away from the valve mechanism, in turn rotating the crankshaft.

The piston then travels back towards the valve mechanism and in turn the exhaust valve opens, so that hot exhaust gases are forced out of the cylinder and cylinder head, and exit the engine via an exhaust gas path.

The four-stroke engine requires many components to operate the valve system within the cylinder head. These components increase a cost of the engine. The engine may also emit a high level of noxious gases in its exhaust fumes.

Over the years, as more appropriate materials have become available, higher performance engines have been manufactured resulting in higher speeds and reliability.

However, there have been few attempts to produce other types of internal combustion engine, and the most common alternative that has become commercially established is a two-stroke engine. The two-stroke engine differs from the more common four-stroke engine by completing the same four processes (intake, compression, power, exhaust) in only two strokes of the piston rather than four. This is accomplished by using the beginning of the compression stroke and the end of the power stroke to perform the exhaust and intake functions, respectively. This allows a power stroke for every revolution of the crank, instead of every second revolution as in a four-stroke engine. For this reason, two-stroke engines provide high specific power, so they are valued for use in portable, lightweight applications.

1-lowever, proposals to replace the valves and con rods of a conventional internal combustion engine with a rotary valve for supplying gas to, and exhausting gas from, a cylinder of an internal combustion engine are also well know.

US 4,852,532 discloses a rotary valve for an internal combustion engine having a hollow cylindrical rotor with an inclined integral baffle along its bore with ports on either side of the baffle arranged to be brought into communication with a window in the cylinder as the hollow cylindrical rotor rotates. The rotor is supported by rollers supported in grooves formed in a surface of the rotor and bearing on the inside surface of a bore of the cylinder head. Seals are provided around the window, the seals consisting of sealing strips arranged in longitudinal grooves formed in the bore of the cylinder head and circumferential rings acconirnodated in annular grooves within the bore of the cylinder head. The longitudinal strips abut in surface contact at each end of the surface of one of the circumferential rings. Passages are provided in the cylinder head for cooling water and in the rotor for cooling oil. Cooling of the rotor is accomplished by radiation to an adjacent surface of the rotor bore which is cooled by water in the water passages and by a flow of oil in the oil passage.

GB 2234300 discloses an air-cooled rotary valve including within the cylindrical rotary valve an inlet duct communicating with an inlet port opening into the cylinder when aligned with the cylinder and an exhaust duct communicating with an exhaust port circumferentially offset from the inlet port, opening into the cylinder when aligned with the cylinder. Two circumferential grooves containing sealing rings are located one on each side of the inlet and outlet ports to isolate the ports from the environment. Longitudinal sealing bars are provided to isolate the inlet port from the outlet port. The rotary valve is cooled by passing air through a bore of the rotary valve.

US 5,941,206 discloses a rotary valve for an internal combustion engine, comprising a cylindrical valve rotor having an inlet and an outlet port in a circumferential surface. A plurality of seating elements mounted on the valve rotor divide the circumferential surface of the rotor body to define discrete circumferential surface zones. One of the zones is arranged so that, when the rotary valve is received within a valve bore in a cylinder head, the sealing elements abut on the valve bore surface and the ports are periodically sealed off.

WO 02/27165 discloses a rotating valve engine with an engine housing that contains an annular timing ring, a rotatable cylinder with a closed end and an open end; and a piston within the cylinder. The cylinder is mechanically driven by the piston via a transmission assembly that includes a con rod that drives a gear that in turn engages a bevel gear fonned at the open end of the cylinder. The rotating valve is cooled by oil forced over the rotating cylinder US 2004/0144361 discloses a rotary valve internal combustion engine including a crankshaft, a throttle, a throttle actuator, a cylinder head, a combustion chamber, and at least one rotary valve. The rotary valve has at least two ports terminating as openings in its periphery, the cylinder head having a bore in which the rotary valve rotates. A window in the bore communicates with the combustion chamber, the openings successively aligning with the window by virtue of the rotation. A drive mechanism with phase change means drives the rotary valve. The ports comprise an inlet port and an exhaust port, and the phase change means applies a phase change in response to changes in the operating conditions of the engine over at least one engine cycle.

A particular concern in rotary valve engines has been to find means of sealing the valve ports of the rotating valve against leakage under pressure.

US 5,526,780 discloses a rotary valve assembly for an internal combustion engine in which the valve has a combination of axial sealing elements and inner circumferential sealing elements arranged to form a first seal pressurizing cavity extending circumferentially between the axial sealing elements and two second seal pressurizing cavities each lying between the inner and adjacent outer circumferential sealing elements axially on each side of a window opening in a cylinder head in which the valve rotates. The arrangement permits high pressure combustion gas to pass from the first cavity to the two second cavities whereby during combustion the outer circumferential sealing elements are caused to seal the second pressurizing cavities by being forced against the axially outermost sides of circumferentially extending grooves in which they are located to prevent axially outward movement of gas. The inner circumferential sealing elements are loaded axially inwardly to seal against axially innermost sides of circumferentially extending grooves in which they are located and to load the four circumferential sealing elements radially to seal against a bore surface in which the valve is housed and against which they are preloaded.

WO 03/100232 discloses a valve seal mechanism for a rotatable valve assembly that provides a seal between a rotating valve element and a fixed valve element as used in a rotary cylinder valve engine. In one embodiment the seal mechanism comprises a substantially rigid sealing frame which surrounds and seals the periphery of the valve port of one of the cylindrical valve elements and also seals a surface of the other cylindrical valve element. In another embodiment, the seal mechanism comprises a resiliently deflectable tubular element of variable diameter, mounted around a first valve element with an aperture of the tubular element being radially aligned with a valve port of the first valve element, the tubular element being biased radially outward of the first valve element.

Cooling of the valve and the sealing mechanism is effected by pumping cooling fluid through coolant channels in a housing of the valve and then over lower parts of the rotating valve element.

WO 2005/11901 8 discloses a seal arrangement for a rotary valve internal combustion engine having a cylinder including a valve port in communication with a combustion chamber. The cylinder is rotatable about its longitudinal axis in a cylindrical bore of a valve housing, the valve housing having an inlet port and an outlet port adapted to be aligned successively with said valve port during rotation of the cylinder in the housing to enable fluid to flow respectively into and out of the combustion chamber. A seal is provided around the valve port between the cylinder and a concentric surface, and comprises a seal element located in a recess in the cylinder, fluid pressure in said valve port acting on said seal element to urge the seal element into contact with the concentric surface and outwardly from the centre of the port into contact with the periphery of the recess.

WO 2006/024081 discloses a sealing system for an axial flow rotary valve internal combustion engine comprising an array of floating gas seals and an optional oil sealing system. The array of floating seals surrounds a window in the bore of the cylinder head through which the ports of the valve communicate with a combustion chamber. The array of floating seals comprises axial seals and circumferential seals housed in slots in the bore of the cylinder head wherein the circumferential seals are disposed axially between the ends of the axial seals. The valve may be cooled with oil that is pumped through the valve.

WO 2006/024086 discloses an axial flow rotary valve for an internal combustion engine comprising a cylinder head having a bore in which an axial flow rotary valve rotates. The valve has a cylindrical centre portion, and an inlet and an exhaust port terminating as openings in the centre portion. The openings periodically communicate with a combustion chamber through a window in the bore. A clearance between the centre portion and the bore is sealed by an array of floating seals comprising at least two axial seals spaced apart on opposite sides of the window. The assembly further comprising at least one floating axially extending masking seal being disposed outside the window and circumferentially remote from the axial seals. In some instances the valve is cooled with oil that is pumped through the valve.

It is therefore apparent that only complex mechanical arrangements are known for sealing ports of a rotary valve against leakage in an axial direction under pressure.

It is an object of the present invention at least to ameliorate the aforesaid deficiency

in the prior art.

According to the invention, there is provided a gas seal system between a port of a rotary valve and a port in a combustion chamber of a rotary valve engine, the seal comprising gas channel means forming a turbo valve means surrounding the combustion chamber port and compression means for creating a pressure in the gas channel means greater than a pressure in the combustion chamber during a compression stroke and a power stroke of the engine.

Advantageously, a clearance between the turbo valve means and an outer surface of the rotary valve is approximately 0.0254 mm (1 mu).

Conveniently, the compression means comprises a turbo valve injector means for injecting gas substantially tangentially into the turbo valve means.

Conveniently, the gas seal system further comprises position sensor means for sensing a rotational position of a rotor of the rotary valve for signalling to the compression means.

Conveniently, the gas seal system further comprises valve means for controlling admission of compressed gas from the compression means to the turbo valve injector means on receipt of signals from the sensor means.

Advantageously, the compression means comprises a compression chamber means.

Conveniently, the compression means comprises compressor means driven by a crankshaft of the rotary valve engine.

Alternatively, the compression means comprises a crankcase of the engine pressurised by intake and power strokes of the engine.

Conveniently, the crankcase comprises a one-way valve means for admitting air into the crankcase on compression and exhaust strokes of the engine.

Conveniently, the gas seal system further comprises a non-return valve means for passing compressed air from the crankcase to the compression chamber means.

According to a second aspect of the invention, there is provided a rotary valve engine comprising a gas seal as described above.

Conveniently, a rotor of the rotary valve is arranged to be cooled by passing water through a bore of the rotor.

According to a third aspect of the invention, there is provided a method of providing a seal in a rotary valve engine between a port in the rotary valve and a port in a combustion chamber of the engine, comprising the steps of: providing a gas channel means forming a turbo valve means surrounding the combustion chamber port; creating, with gas compression means, a pressure in the gas channel means greater than a pressure in the combustion chamber during a compression stroke and a power stroke of the engine.

Conveniently, the method further comprises injecting gas substantially tangentially into the turbo valve means with a turbo valve injector means.

Conveniently, the method further comprises sensing a rotational position of a rotor of the rotary valve with sensor means for signalling to the compression means.

Conveniently, the method further comprises controlling admission of compressed gas from the compression means to the turbo valve injector means on receipt of signals from the sensor means.

Advantageously, creating a pressure in the gas channel means comprises creating a pressure in a compression chamber means.

Conveniently, creating a pressure in the gas channel means comprises creating a pressure with a compressor means driven by a crankshaft of the rotary valve engine.

Alternatively, creating a pressure in the gas channel means comprises pressurising air in a crankcase of the engine by intake and power strokes of the engine.

Conveniently, pressurising air in the crankcase, comprises admitting air into the crankcase through a one-way valve means on compression and exhaust strokes of the engine.

Conveniently, creating a pressure in the gas channel means comprises passing compressed air from the crankcase to the compression chamber means through pneumatic tubing means and a non-return valve means.

The invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a cut away draing of a rotary valve internal combustion engine according to the invention; Figure 2 is a vertical, longitudinal cross-section of the engine of Figure 1; Figure 3 is a side view of the engine of Figure 1; Figure 4 is a front view of the engine of Figure 1; Figure 5 is a rear view of the engine of Figure 1; Figure 6 is a front view of the engine of Figure 1, including a gas compression system; Figure 7 is a vertical, transverse cross-section of the engine of Figure 6; Figure 8 is a vertical, transverse cross-section of a gas seal of the engine of Figure 6; and Figure 9 is a plan view of the gas seal of Figure 8.

in the Figures, like reference numerals denote like parts.

Referring to Figures 1 to 3 and 7, a rotary valve engine comprises a one piece cylinder block I and cylinder head 2, eliminating cylinder head bolts and a cylinder head gasket, which are required in a standard internal combustion engine to join a separate cylinder block and cylinder head, which in a water-cooled engine can be a source of water leaks. The one-piece construction also provides a more rigid construction than that of a standard internal combustion engine. The cylinder block 1 is provided with a conventional crankshaft 3, con rods 4, and pistons 5. Referring to the orientation of the engine in the drawings, within the cylinder head 2 and just above combustion chambers 6 above the pistons 5 there is a rotary valve 7 which controls inlet and exhaust gases going in and out of the combustion chambers 6, respectively, via ports 8 in upper ends of the combustion chambers 6.

The rotary valve 7 is driven by the crankshaft 3 using a toothed belt 9 at a front of the engine accurately to align inlet ports 10 and exhaust ports 12 within the circumference of the rotary valve 7 with the ports 8 with the same accurate precision as provided by cams and mechanical mechanisms in opening and closing valves in a standard internal combustion engine. As a piston 5 travels down the cylinder block I within a bore of a cylinder 11, a port 10 within the rotary valve 7 rotates to a position over the cylinder head port 8, allowing inlet gases to be drawn into the combustion chamber 6.

As the piston 5 rises up the cylinder 11 in the cylinder bore on a compression stroke, the rotor 7 continues to rotate and blanks off the port 8 in the cylinder head 2. The compressed charge is then ignited, for example by a spark plug, resulting in a power stroke while the rotor 7 continues to rotate.

As the piston 5 rises up the cylinder again on an exhaust stroke to force out exhaust gases, an exhaust port 12 within the rotor 7 reaches the port 8 within the cylinder head 2, allowing the exhaust gases to be purged out of the engine through the rotary valve. This process is carried out within the engine; each cylinder having its own set of inlet and outlet ports within the rotary valve 7.

The rotor of the rotary valve 7 is water-cooled in a more efficient maimer than cooling in a conventional cylinder head. Also the surface 16 of the rotor 7 that passes over the cylinder head port 8 absorbs the heat over a relatively large area compared with heat exchange surfaces in a conventional engine. Water enters the rotor 7 at a front end 13 of the cylinder block and exits at a rear end 14 into the cylinder block 1. This ensures that maximum desirable cooling is given to the rotor 7. The rotor 7 is a one piece structure that may be constructed to fit lengthways over any number of cylinders as a one piece component, so that water can enter at one end and exit through the other end, unlike some previous rotary valves where inlet and exhaust gases have had to use either end for transfer, making them only suitable for single cylinder engines without any water cooling.

An advantage of the rotary valve of the present invention is that the inlet and the exhaust valves are shaped to act as a conventional port of a standard engine, allowing the gasses to enter and leave through a side of the rotor. This means that the inlet gas for the cylinder or cylinders can enter the rotor across to the centre of the rotor, and then turn downwards into the cylinder.

After combustion has taken place, the exhaust port in the rotor opens, allowing the exhaust gas to enter the port and to be forced across a centre of the rotor and out through the side of the rotor and through the cylinder head port to an exhaust pipe.

This allows water to enter the front of the rotor and have a clear passage around each of the ports mounted across the rotor from side to side.

Control of thermal expansion of the rotor is easily achieved to maintain a running clearance with the cylinder head.

Referring to Figure 4, the exhaust port 12 has an angled leading edge 17, as best seen in Figure 6, which shaves carbon build up off the cylinder head surface 18 ensuring a maximum sealing of combustion pressure, minimizing an air pressure required in a recess groove 15, described below, to ensure complete sealing throughout the working life of the engine.

Referring to Figures 1 and 7 to 9, to maintain compression of inlet gases within the cylinder head 2, a recess groove 15 is provided which encircles the port 8 on an outer face of an upper end of the cylinder and is linked to air channels, as best seen in Figure 8, to form a turbo valve 26. Air is supplied under pressure to the turbo valve 26. The air can be supplied by a small compressor, not shown, driven by the crankshaft 3 or, as illustrated in Figure 6, the required pressure is generated internally by the pistons 5 of the engine.

As the piston 5 ascends, a valve, not shown, in the side of the crankcase 19, automatically opens to atmosphere, allowing air to be drawn into the crankcase. As the piston 5 descends on a power stroke of the engine, the crankcase valve closes and the piston compresses air within the crankcase 19 forcing air through pneumatic tubing and a non-return valve 20 into an air storage chamber 21. On a multi-cylinder engine, the crankcase has dividing walls, not shown, either cast as part of the crankcase or fitted separately to provide individual compartments fitted with an oil seal at the crankshaft main bearing. This is to allow each compartment to work with a respective air valve system activated by the downward stroke and the upward stroke of the piston within that respective compartment individually.

This charging of the air storage chamber occurs twice per power stroke of the engine, providing the air storage chamber 21 with a volume of compressed air. As the piston 5 of the engine ascends under compression for its power stroke a solenoid valve 22 is triggered into operation by a sensor 23 operated by the rotor 7 in the cylinder head 2 to allow air to be led from the air storage chamber 21 via a pneumatic tubing system 24 and the electronic solenoid valve 22 to a turbo valve injector 25 which forces the compressed air substantially tangentially into the circular groove 15, as best seen in Figure 9, to circulate at high speed around the recess groove 15 of the turbo valve 26. The turbo valve 26 is located at an upper end of the combustion chamber 6 and is only 0.0254 mm (J/J,�00th of an inch) clear of the circumference 16 of rotor 7.

An upper portion of a wall of the turbo valve 26, with a profile conforming to an outer circumference of the rotor 7 radius, has a chamfer 27. This concentrates the air pressure on the 0.0254 mm (1/1,000 inch) gap 28 between an upper edge of the turbo valve and a surface of the rotor 7.

The pressure of the circulating air in the gap 28 between the turbo valve and rotor surface is arranged to be greater than the gas pressure inside the combustion chamber 6 so that all fuel and detonation combustion gases are retained in the combustion chamber 6 during the compression and power strokes respectively.

This external air pressure is held in the turbo valve 26 during the combustion stroke and the exhaust stroke of the engine. As the exhaust port 10 within the rotor 7 moves to a location over the port 8 to allow the exhaust gases to escape, the sensor 23 receives a pulse from the rotor 7 and sends a signal which causes the electronic solenoid valve 22 to close.

At the same time, the compressed air around the turbo valve 26 escapes through the port 10 which cools the exhaust gas on its way to the atmosphere.

A conventional engine will emit a high level of poisonous gases into the atmosphere.

This is because the exhaust valves run red hot, superheating gases passing through them.

As the engine of the invention runs a lot cooler and does not have those problems, the exhaust gases the engine emits produces reduced pollution of the atmosphere compared with conventional internal combustion engines.

It will be understood that the electronic solenoid valve 22 can be replaced by, for example, a mechanical cam driven valve.

DRAWING COMPONENT NUMBERS

(1) Cylinder block (2) Cylinder head (3) Crankshaft (4) Conrod (5) Piston (6) Combustion chamber (7) Rotor (8) Combustion chamber port (9) Toothed belt (10) Inlet port (11) Cylinder (12) Exhaust port (13) Front end (14) Back end (15) Recess groove (16) Rotor surface (17) Angled trailing edge (19) Crankcase (20) Non return valve (21) Storage chamber (22) Solenoid valve (23) Sensor (24) Pneumatic tubing system (25) Turbo valve injector (26) Turbo valve (27) Chamfer (28) Gap between upper edge of turbo valve and rotor

Claims

I. A gas seal system between a port of a rotary valve and a port in a combustion chamber of a rotary valve engine, the seal comprising gas channel means forming a turbo valve means surrounding the combustion chamber port and compression means for creating a pressure in the gas channel means greater than a pressure in the combustion chamber during a compression stroke and a power stroke of the engine.
2. A gas seal system as claimed in claim 1 wherein a clearance between the turbo valve means and an outer surface of the rotary valve is approximately 0.0254 mm(I mu).
3. A gas seal system as claimed in claims I or 2, wherein the compression means comprises a turbo valve injector means for injecting gas substantially tangentially into the turbo valve means.
4. A gas seal system as claimed in claim 3, comprising position sensor means for sensing a rotational position of a rotor of the rotary valve for signalling to the compression means.
5. A gas seal system as claimed in claim 4, comprising valve means for controlling admission of compressed gas from the compression means to the turbo valve injector means on receipt of signals from the sensor means.
6. A gas seal system as claimed in any of the preceding claims, wherein the compression means comprises a compression chamber means.
7. A gas seal system as claimed in any of the preceding claims, wherein the compression means comprises compressor means driven by a crankshaft of the rotary valve engine.
8. A gas seal system as claimed in any of claims I to 6, wherein the compression means comprises a crankcase of the engine pressurised by intake and power strokes of the engine.
9. A gas seal system as claimed in claim 8, wherein the crankcase comprises a one-way valve means for admitting air into the crankcase on compression and exhaust strokes of the engine.
10. A gas seal system as claimed in claims 8 or 9, comprising a non-return valve means for passing compressed air from the crankcase to the compression chamber means.
Ii. A rotary valve engine comprising a gas seal as claimed in any of the preceding claims.
12. A rotary valve engine as claimed in claim 11, wherein a rotor of the rotary valve is arranged to be cooled by passing water through a bore of the rotor.
13. A method of providing a seal in a rotary valve engine between a port in the rotary valve and a port in a combustion chamber of the engine, comprising the steps ot a. providing a gas channel means forming a turbo valve means surrounding the combustion chamber port; b. creating, with gas compression means, a pressure in the gas channel means greater than a pressure in the combustion chamber during a compression stroke and a power stroke of the engine.
14. A method as claimed in claim 13, comprising injecting gas substantially tangentially into the turbo valve means with a turbo valve injector means.
15. A method as claimed in claims 13 or 14, comprising sensing a rotational position of a rotor of the rotary valve with sensor means for signalling to the compression means.
16. A method as claimed in claim 14, comprising controlling admission of compressed gas from the compression means to the turbo valve injector means on receipt of signals from the sensor means.
1 7. A method as claimed in any of claims 13 to 16, wherein creating a pressure in the gas channel means comprises creating a pressure in a compression chamber means.
18. A method as claimed in any of claims 13 to 17, wherein creating a pressure in the gas channel means comprises creating a pressure with a compressor means driven by a crankshaft of the rotary valve engine.
19. A method as claimed in any of claims 1310 1 7, wherein creating a pressure in the gas channel means comprises pressurising air in a crankcase of the engine by intake and power strokes of the engine.
20. A method as claimed in claim 19, wherein pressurising air in the crankcase, comprises admitting air into the crankcase through a one-way valve means on compression and exhaust strokes of the engine.
21. A method as claimed in any of claims 17 to 20, wherein creating a pressure in the gas channel means comprises passing compressed air from the crankcase to the compression chamber means through pneumatic tubing means and a non-return valve means.
22. A gas seal system substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
23. A rotary valve engine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings
24. A method of providing a seal in a rotary valve engine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.