The above patent specifications describe a construction of rotary valve for use in a reciprocating internal combustion engine. The valve is mounted in the cylinder head above a cylinder and comprises a rotary valve member equipped with passages through which combusted and combustible gases are respectively discharged from and flow into the cylinder. The valve member is rotated in synchronism with the output drive shaft of the engine and rotates inside a floating valve-housing assembly which includes a cylindrical sleeve split longitudinally parallel to its axis and having its inner surface in sliding, sealing contact with an outer cylindrical surface of the rotary valve member. The sleeve is also provided with a gas-conducting port to allow gases to flow between the cylinder and the passages in the valve member. The sleeve is divided into three axially-adjacent cylindrical zones the central one of which provides a gas-sealing zone which includes totally within its length the gas-conducting port and is located between the other two, lubricated, load-carrying zones. Annular grooves are provided around the inside surface of the sleeve which divide the annular bearing sections of the sleeve from the central ported portion. A resilient sealing strip extends the full length of the sleeve split and radial bores or drain holes extend through the sleeve from the grooves adjacent the sealing strip on its side towards which the oil is conveyed along the grooves by the rotation of the valve rotary member or rotor. Such an arrangement transports lubricant, which would otherwise

leak into the ported portion of the sleeve, along the grooves and out of the bores to oil discharge passages in the cylinder head. The valve member is supported for rotation in the cylinder head by roller bearings. The present invention provides constructional changes to the rotary valve described above which generally have the effect of improving its performance in simplifying its construction and in preferred forms of the invention improving the control of migration of lubricant from the lubricated zones. Details of these changes are disclosed in a description of a preferred embodiment of the invention set out below.

The present invention consists in a rotary valve mechanism for a reciprocating heat engine having a cylinder, a piston reciprocating therein and a cylinder head defining a combustion chamber, the rotary valve mechanism consisting of a cylindrical valve rotor supported for rotation, in said cylinder head, the valve rotor having at least one gas port passing through its cylindrical surface, mechanical means to rotate said valve rotor in a timed relationship with the movement of said piston, a cylindrical valve housing in said cylinder head surrounding said valve rotor and providing a cylindrical inner surface in sliding sealing contact with the outer cylindrical surface of said valve rotor, said valve housing having a longitudinally extending split in its circumference, and defining a gas conducting port to provide a communication path between said rotor gas port and said combustion chamber, the external cylindrical surface of the valve housing being in contact with an internal cylindrical surface of the cylinder head opposite said port, resilient annular sealing means arranged between the valve housing and the cylinder head extending around said port, said sealing means acting on the valve housing in conjunction with gas pressure generated in the

cylinder to force the valve housing against the said internal cylindrical surface of the cylinder head, said force being transmitted through the valve rotor.

In order that the invention may be better understood and put into practice a preferred form thereof is hereinafter described by way of example with reference to the accompanying drawings in which:-

Figure 1 is a schematic sectioned side elevation of a rotary valve assembly in association with a combustion chamber of an internal combustion engines.

Figure 2 is a schematic sectioned end elevation of the valve assembly of Figure 1,

Figure 3 is a schematically developed plan view of the split valve housing in which the valve rotor rotates, Figure 4 is a cross sectional view of the portions of the valve housing either side of the split therein,

Figure 5 is a perspective view of the valve housing, Figure 6 is a perspective view of an Oldham type coupling through which the valve rotor is driven, and Figure 7(a),(b),(c) and (d) are diagrammatic views showing various possible porting configurations of the rotary valve

In Figures 1 and 2 there is schematically depicted a valve assembly 10 in association with a cylinder head 11. The head 11, in combination with a co-operating piston 12 and cylinder 13, defines a combustion chamber 14. The rotary valve assembly 10 includes a rotor 15 which includes longitudinally extending passages 16 and 17 which terminate on the longitudinal peripheral surface of the rotor 15 so as to provide two rotor ports 18 and 19

(Fig. 2). The rotor ports 18 and 19 are angularly spaced about the longitudinal axis of the rotor 15 so as to communicate alternately with a port 21 of combustion chamber 14. The passages 16 and 17 control the flow of fuel to, and the flow of expended exhaust gases from, the

combustion chamber 14.

In operation of the valve assembly 10, the rotor 15 is rotated about its longitudinal axis so that the passages 16 and 17 are alternately brought into communication with the combustion chamber 14 in a timed sequence with movement of the piston 12.

The rotor 15 is mounted for rotation in a valve housing 22, the valve housing being split along a line 23 the configuration of which is described in more detail in relation to Figure 3. The valve housing 22 is contained within the cylinder head 10 and fits closely within it. The valve housing 22 is maintained in a condition in which it is clamped closely around the valve rotor 15 by means of the annular sealing ring 24 which is of substantially V-shaped form in cross section and is formed from resilient material. The sealing ring 24 acts to force the valve housing 22 against the rotor 15 and also against the inner cylindrical surface of the upper part of the cylinder head 10. The effect of the sealing ring 24 is reinforced by gas pressure in the combustion chamber 14 acting on the valve rotor 15 and also on those portions of the valve housing 22 extending inwardly of the sealing ring 24. The result of these forces is that the valve housing 22 is pressed against the inner surface of the cylinder head 10 causing the split 23 to close whereby the housing 22 closely embraces the outer surface of the rotor 15 to make sealing contact with it. A further effect is that heat is transferred directly from the valve housing 22 to the cylinder head 10 from which it may be readily dissipated.

In the inner surface of the valve housing 22 are formed four circumferential grooves, two inner grooves 26 and two outer grooves 27. Each inner groove 26 and outer groove 27 define between them an outer lubricated load bearing zone 28 and the two inner grooves 26 define

between them an inner gas sealing zone 29 into which the port 21 opens.

The continuity of each of the grooves 26 and 27 is interrupted by a dam 31. Each groove is terminated at one side of the dam 31 by a drain hole 32 through which lubricant circulating in the grooves can drain away. The holes 32 axe arranged upstream of the dams 31 so that rotation of the rotor in the direction indicated by the arrow A in Figure 3 tends to carry oil around in the grooves towards the drain holes 32.

The grooves 26 act to inhibit the flow of lubricant from the load bearing lubricated zones 28 into the gas sealing zone 29 and the grooves 27 act to inhibit the flow of lubricant out beyond the ends of the valve rotor into the inlet or exhaust system of the cylinder head. Lubricant oil is supplied to the two lubricated load bearing zones 28 through entry ports 33 to which it is supplied by a suitable pump (not shown) .

As is best seen in Figures 3 and 5 the split 23 in the valve housing 22 consists of a central portion 34 extending parallel to the axis of the valve and angled portions 35, 36, 37 and 38 which extend at an angle of between 20 and 30 degrees to the grooves 26 and 27 in the direction of rotation of the valve rotor so as to act under the influence of the rotation of the valve rotor to prevent the migration of lubricant out of of the load bearing lubricated zones 28. It is found that the construction of the split in this manner is particularly effective in preventing the passage of lubricant along the split 23 into the inner gas sealing zone 29 or post the ends of the rotor 15.

The split 23 is filled with a heat and oil resistant elastomer 39 (see Fig. 4) which can be self-adhesive or vulcanised or bonded in-situ. This seals the split 23 while permitting the housing 22 to clamp around the rotor 15

The rotor 15 is driven by means of an Oldham type coupling 41 which is shown in Figure 6. The coupling 41 enables the valve rotor to be driven in synchronism with the engine crank shaft while eliminating any side (radial) loadings into the valve rotor from the drive mechanism which may be constituted by a chain, tooth belt or gears (not shown). The coupling 41 has_ a. gas port 42 formed in it, which as. it shown in Figure 1 forms part of the exhaust or inlet gas tract. As is indicated in Figure 1 in broken lines a second Oldham type coupling 43 may be provided to couple the valve rotor to the valve rotor in an adjacent cylinder in an in-line multi-cylinder engine. In the particular form of the invention illustrated in Figure 1 ^" the second coupling 43 also has a gas port 44. The gas ports 42 and 44 link up with exhaust or inlet tracts formed in the cylinder head.

The valve rotor of a rotary valve mechanism according to the invention may incorporate a variety of types of valve-rotor porting to suit two cycle or four cycle engines of single or multi-cylinder configuration. Figure 7a shows a porting suitable for two cycle or four cycle multi-cylinder engines. Figure 7b shows porting suitable for a four cycle cylinder engine. Figure 7c shows porting for a two cycle engine performing either the inlet or the exhaust function. Figure 7d is also intended for a two cycle engine but the dual port allows the valve rotor to be driven at one half crankshaft speed.

The embodiment of the invention described above is given by way of example only as constituting one preferred embodiment of the invention within the scope of the succeeding claims.

This form of invention does illustrate a number of the advantages of the rotary valve mechanism constructed according to the present invention over that disclosed in

the abovementioned United States and European patent specifications. The construction is considerably simpler in that fewer parts are required and the use roller bearings is eliminated, the rotor being supported for rotation entirely by the inner cylindrical surface of the valve housing which in turn is supported by an inner cylindrical surface of the cylinder head leading to good heat conduction to the cylinder head.

The provision of two additional circumferential grooves in the valve housing to prevent the passage of lubricant beyond the ends of the valve housing is advantageous in preventing passage of lubricant into the inlet or exhaust system. Such grooves however are not essential to all forms of the invention in that it is contemplated that a rotary valve mechanism according to the invention may be employed in a two stoke engine in which lubrication of the valve rotor is obtained solely from lubricant contained in the fuel.

The use of an Oldham type coupling drive the valve rotor greatly facilitates the use of a rotary valve mechanism according to the invention in a multi-cylinder in-line application.