AU696388B2 - Rotary valve for internal combustion engine - Google Patents

Description

ROTARY VALVE FOR INTERNAL COMBUSTION ENGINE

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

BACKGROUND OF THE INVENTION

Rotary valves for internal combustion engines have been know for many years to replace the use of poppet valves. Poppet valves operate in a reciprocatory action and while they are mechanically opened by a cam or a cam operated pushrod through rockers, each has to be closed by a spring. In order to ensure closing of the valve at high speeds stronger springs are used, and even double springs have been used in an attempt to prevent valve bounce. Thus the valve has to open against the action of the spring or springs, and this necessarily requires a substantial force to do so resulting in a virtual power waste of the engine.

A rotary valve requires little power to rotate the valve, however problems have arisen with prior art valves in sealing of the valve to the port opening into the cylinder. Also the valve must have an adequate cooling arrangement, particularly for the portion of the valve controlling the exhaust gases. Rotary valves are known to be used on racing motor cycle engines, but these have been known to be restricted to the use of the valve on a single cylinder engine.

AU591052 discloses a rotary valve having means to overcome the thrust on the valve due to the large pressures developed in the cylinder of the engine, and is also directed to the lubrication of the rotating valve.

US4,949,685 discloses an internal combustion engine having a pair of rotary tube valves for each head. Each hollow valve has a slot to co-operate with a port in the cylinder head, one end of each tube valve being closed, and the other end connected to a machined port in the head which port is connected to either a carburettor or to exhaust. A ceramic seal is provided around the ports to the cylinder, the seals having a wave spring to maintain sealing pressure.

US4,879,979 also discloses a rotary valve for an internal combustion engine, the rotary valve including a hollow shaft which is water cooled.

AU68942/87 is directed to a rotary valve for an internal combustion engine having a hollow cylindrical rotor having along its bore an inclined integral baffle with ports on either side of the baffle arranged to be brought into communication with a port as the rotor rotates. The rotor is supported in roller bearings, and has longitudinal sealing strips co-operating with sealing strips to seal around the ports.

GB2.211 ,549 describes a rotary valve for an engine, the rotary valve having circumferentially extending grooves along its length. The ports open into channels which open into ducts which communicate with ports in the cylinders of the engine.

AU59304/90 also discloses a rotary valve mechanism having at least one gas port passing through its cylindrical surface. A valve housing surrounds the rotary valve and has a longitudinal slit in its circumference and defines a gas port to pass gas between the rotor and the combustion chamber. A seal is also described between the valve housing and the cylinder head.

The prior art shows that either there is a separate rotary valve for each cylinder, or where a single valve is provided for a plurality of cylinders, the valve has radial or diametrical ports opening to a manifold on one side of the valve to a port to the cylinder on the other side of the valve.

BRIEF STATEMENT OF THE INVENTION

It is an object of this invention to provide a rotary valve for an internal combustion engine, which valve can be used for an engine having a multiple of in-line cylinders in one bank.

It is another object of this invention to provide a single rotary valve for a plurality of cylinders in the one bank, the single valve controlling both the inlet and exhaust gases for each cylinder.

It is a further object of this invention to provide a single linear rotary valve which has improved cooling of the valve.

It is a still further object of this invention to provide an improved, effective and simple seal for the rotor of the rotary valve.

Thus there is provided according to the invention a rotary valve for a multi- cylinder internal combustion engine having at least two in-line cylinders, the rotary valve having a rotor rotatable in a split housing, the fixed portion of the housing having inlet and outlet ports communication respectively with each combustion chamber, said rotor having a first spiral channel extending from one end to terminate adjacent the other end, and a second spiral channel extending from said other end to terminate adjacent said one end, one of said channels communicating in sequence with said inlet ports, and the other of said channels communicating in sequence with said exhaust ports, and sealing means between said rotor and each of said ports.

There is also provided according to the invention a rotary valve for an internal combustion engine having a piston operating in a cylinder formed in a block, said rotary valve having a rotor rotatable in a housing, passage means in said rotor providing inlet and exhaust passages sequentially opening to said cylinder, characterised by a seal between said rotor and said cylinder, said seal having a first end and a second end, said first end sealing against the rotor surface, said first end having a first area subject to cylinder pressure, and said second end having second area subject to cylinder pressure, said first and second areas being so chosen that the seal is balanced or substantially balanced under cylinder pressure.

Preferably the seal is spring loaded to be biased into contact with said rotor by a spring acting between the seal and the block.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more fully describe the invention reference will now be made to the accompanying drawings in which:-

Figure 1 is a side view of the invention as applied to an engine having a bank of 4 cylinders,

Figure 2 is an end view of the invention as shown in Figure 1 , and

Figure 3 is a side and end view to an enlarged scale of the sealing between the rotor and port in the cylinder head.

DESCRIPTION OF THE PREFERRED EMBODIMENT.

Referring to the drawings there is shown a reciprocating engine having four cylinders, with a head 2 being of split construction having a base 3 and an upper portion 4. The head is provided a cylindrical bore 5 containing a valve rotor 6 the rotor being mounted in bearings 7 in the head. Thus the rotor is effectively mounted in a split housing formed by the two portions 3 and 4 of the head 2.

The rotor is provided with two spiral channels, inlet spiral channel 10 and outlet spiral channel 11 , with inlet ports 8 and exhaust ports 9 respectively through the surface of the rotor in alignment with each cylinder to respectively alternately communicate with a cylinder port 25 formed in the base portion 3 of the head. In the drawing the ports 8 and 9 on the front face of the rotor are shown shaded while the ports on the reverse side of the rotor are dotted and also indicated by the respective letters I and E. The cylinder port 25 is basically square or rectangular in shape and the ports 8 and 9 are elongated along the respective spiral in a general polygonal shape and thus match the cylinder port 25 to thus provide adequate valve opening time.

Spiral 10 opens to one end 12 of the rotor, this end being connected to a carburettor or to air if the engine is fuel injected, the spiral 10 thus forming the inlet spiral for the engine. The other spiral 11 opens to the other end 13 of the rotor, this end being connected to the exhaust system of the engine so that the spiral 11 forms the exhaust passage for the engine. The rotor is driven by a drive 14 which may be a chain, lugged belt or spur or bevel gear train from the crankshaft of the engine. It is to be noted that the rotor is driven at one half crankshaft engine speed for a four stroke engine.

The spirals are spaced circumferentially around the rotor, the spacing being such that each spiral opens to its respective cylinder port 25 in each respective cylinder in the correct sequence. The ports 8 and 9 are also so arranged that there is the required degree of overlap in the ports opening into the cylinder port 25, the leading edge of the inlet port 8 connecting to the cylinder port 25 before the trailing edge of the outlet port 9 leaves the cylinder port 25.

The cooling of the rotor is provided by a cooling jacket 15, the jacket 15 being provided in the rotor thus surrounding the exhaust and inlet passages. The upper portion of the head 4 has an inlet 16 and an outlet 17 connecting to openings in the rotor to connect to the jacket 15. Incorporated in the rotor there are turbines 18 to circulate the cooling fluid through the rotor. Thus the turbines can be used as the water pump for circulating the cooling fluid, so that a separate drive for the water pump is not required. Lubrication of the rotor is provided by a plurality of oil injectors 19 spaced along the length of the base upper portion of the head. The number of oil injectors will vary depending on the length of the rotor, i.e. whether the engine has two, four, six or more cylinders in one bank. In order to control the lubricating oil around the rotor, there are preferably provided an oil scrapers 20 extending along the length of the rotor so that excess lubrication can be removed through line 26.

Seals 27 are provided in the housing to seal against the rotor. These seals 27 are positioned between the exhaust ports along the rotor to prevent exhaust gasses creeping along the rotor between the rotor and the housing.

Preferably these seals are heat resisting and low friction seals such as of the silicon and PTFE type.

A spark plug 21 is shown extending through the head base 3 into the upper portion of the cylinder of the engine. On the opposite of the head base there is shown a fuel injector 28. The fuel injector is preferably inserted into the head base 3 with a thread identical to the spark plug thread, so that if there is single point injection or a carburettor, twin spark plugs can be utilised.

Figure 3 shows an example of the form of seal that can be used to seal the head port against the rotor during operation of the engine. The seal member 22 can be of any suitable material, such as aluminium and carbon composition hardened steel, or any suitable steel alloy, or ceramic material if desired. The seal is provided with a wave spring 23 under a shoulder of the seal, and an O ring seal 24 prevents leakage between the seal and the passage forming the port in the base 3. It has been calculated that due to the stepped nature of the seal that if the area of the base of the seal is equal to the area of the stepped flange, then there will be no added force on the rotor other than that provided by the wave spring. In this way there is a simple and effective seal by preloading only.

Thus it will be seen by reference to Figure 3 that the seal is effectively balanced. The area of the seal available to the combustion pressure at the bottom of the seal is equal to the area of the seal available to the combustion pressure around the port in the rotor. Thus the load on the seal L = (W x L) - (W x L') x combustion pressure. If it is desired to apply greater pressure of the seal against the rotor during the combustion and exhaust cycles, then the ratios of the two effective areas on opposite ends of the seal can be varied so that the area facing the cylinder is greater than the area adjacent the rotor.

Thus it can be seen that there is provided according to the invention a rotary valve for a multicylinder combustion engine, the single valve controlling both the inlet and exhaust passages of each cylinder. Also there is provided a seal between the rotary valve and the cylinder of the engine which seal does not apply heavy loading on the rotary valve during the combustion process. Also the invention provides a means for cooling the valve during operation.

Although one form of the invention has been described in some detail it is to be realised that the invention is not to be limited thereto but include variations and modifications falling within the spirit and scope of the invention.

Claims (12)

1. A rotary valve for a multi-cylinder internal combustion engine having at least two in-line cylinders, the rotary valve having a rotor having a first end and a second end rotatable in a split housing forming the head of the engine, the portion of the housing attached to the block of the engine port communicating respectively with each cylinder, said rotor having a first spiral channel extending through the rotor from a first end of said rotor, said first spiral channel being open at said first end and closed at the second end of the rotor, a second spiral channel extending through the rotor from said second end of said rotor, said second spiral channel being open at said second end of said rotor and closed at said first end of said rotor, said first channel having spaced apertures through the wall of the rotor corresponding to the position of the said port for each cylinder, said second spiral channel having spaced apertures corresponding to the said port for each cylinder, sealing means between the rotor and each of the said ports, and drive means to drive the rotor.

2. A rotary valve as defined in claim 1 wherein the first spiral channel receives a fuel-air mixture for a spark ignition engine, or the combustion air in respect of a fuel injection engine, the second spiral channel being connected to exhaust.

3. A rotary valve as defined in claim 1 or claim 2, wherein said sealing means comprise a seal mounted in each said port, each said seal having a first end and a second end, said first end of said seal having a first surface in contact with said rotor and a second surface exposed to cylinder pressure adjacent said first surface, said second end of the seal having a third surface exposed to cylinder pressure, the relative areas of said second and third surfaces being chosen that the seal is balanced by the cylinder pressure.

4. A rotary valve as defined in claim 3 and including a sealing ring between the seal and the said housing portion attached to the block, and spring means to maintain the first surface of the seal in sealing contact with the surface of the rotor.

5. A rotary valve as defined in claim 3 wherein the seals are rectangular, and each of the apertures in the surface of the rotor are polygonal extending along the spiral passage to provide adequate valve opening time

6. A rotary valve as defined in claim 2 wherein the rotor includes a coolant passage extending the length of the rotor from a coolant inlet at one end of the rotor to a coolant outlet at the other end of the rotor, and turbine means positioned at each end of the rotor to pass the coolant through the rotor.

7. A rotary valve as defined in claim 3 wherein circumferential seals are positioned in the split housing to isolate the port of one cylinder from the adjacent cylinder port.

8. A rotary valve as defined in claim 3 wherein means are provided for the lubrication of the rotary valve.

9. A rotary valve as defined in claim 3 wherein the housing portion attached to the block has provision for a spark plug or a fuel injector.

10. A rotary valve for an internal combustion engine having a piston operating in a cylinder formed in a block, said rotary valve having a rotor rotatable in a housing, passage means in said rotor providing inlet and exhaust passages sequentially opening to said cylinder, characterised by a seal between said rotor and said cylinder, said seal having a first end and a second end, said first end sealing against the rotor surface, said first end having a first area subject to cylinder pressure, and said second end having second area subject to cylinder pressure, said first and second areas being so chosen that the seal is balanced or substantially balanced under cylinder pressure.

11. A rotary valve as defined in claim 10 wherein the seal is spring loaded to be biased into contact with said rotor by a spring acting between the seal and the block.

12. A rotary valve substantially as hereinbefore described with reference to the accompanying drawings.