ROTARY VALVE FOR INTERNAL COMBUSTION ENGINE

Abstract: A rotary valve (1) for an internal combustion engine, comprising a cylindrical valve rotor (2) having an inlet and an outlet port (3, 7) arranged in the circumferential surface thereof, and a plurality of sealing elements (13a, 13b, 14a-14f) mounted on the valve rotor (2) such as to subdivide the circumferential surface of the rotor body (2) to define discrete circumferential surface zones thereon, a predetermined one of the discrete surface zones being arranged such that, when the rotary valve (1) is received within a valve bore in a cylinder head of an engine and the sealing elements (13a, 13b, 14a-14f) of the rotary valve (1) abut on the valve bore surface, it periodically seals-off a transfer port in the cylinder head, for which the rotary valve (1) serves as closing and opening means, during at least part of the compression and combustion strokes performed in the engine, whereby air-fuel mixture compressed during the compression stroke and combustion gases created during combustion stroke are substantially prevented from passing into the inlet or outlet port (3, 7) of the valve (1) during these strokes.

Description: - 1 - ROTARY VALVE FOR INTERNAL COMBUSTION ENGINE The present invention relates to an improved rotary valve for internal combustion engines as well as to a cylinder head - rotary valve assembly for internal comjustion engines The invention also relates to an improved arrangement of sealing elements fcr rotary valves . There have oeen proposed different kinds of rotary valve assemolies for internal combustion engines, most of which have in common the provision of a cylindrical or sleeve-like rotor body having separate intake and exnaust passages Degmnmg in opposite axial sides of the rotor boαy and whicn respectively terminate in an inlet and exhaust port angularly spaced apart on the peripneral surface of the rotor body. The ports are dimensioned and arranged with respect to one another such that upon rotation of tne valve rotor in a cylinder nead valve bore, in which the rotary valve is rotatably supported to maintain a small clearance gap between facing surfaces of the core and rotor body, the inlet and exhaust ports periodically align with and pass over a single transfer port in the bore surface of the cylinder head. The transfer port is in fluid communication with a comoustion chamber cf the engine. Periodical and properly timed opening of the transfer port by means of the rotary valve allows passage of a specified air or air-fuel mixture amount, depending on whether the fuel supply is by means of injection or by a carburettor, through the valve rotor into the combustion chamber and expulsion of exhaust gases therefrom into the exhaust manifold during the induction and exhaust strokes of the engine. The circumferential surface of the valve rotor serves to close the transfer port during the combustion and compression stroke of the cycle and ideally snould provide a leak-free shutting of the transfer port during this part of the cycle. A number of different sealing systems nave been proposed to prevent escape of high pressure combustion gases durmg tne compression and combustion phases of the cycle from the transfer port into the peripneral gap between rotor and valve bore and on into the intake and exhaust ports. In particular, there are a number of published patent applications by A. E. Bishop Research Pty Ltd (US 4, 852, 532 and W094/11621) and Dana Corporation (US 4, 019, 487) which describe a system of so called "window of floating seals" aimed at preventing or at least substantially reducmg high pressure gas loss through the transfer port into and past the valve into the valve bore during the combustion and compression cycle. Bishop's US patent 4, 852, 532 discloses a system of seals consisting of two axially spaced apart ring seals which are received in suitably sized annular grooves withm the valve bore, the ring seals being pre-loaded so as to rub with their inner-peripheral surfaces against the outer peripheral surface of the rotor body on either side of the let and exhaust ports such as to sealingly close the annular gap between valve rotor and valve bore along the bore axis. The system also comprises two axially extending sealing bars which are located in suitably shaped grooves in the valve bore surface on either circumferential side of the cylinder-head transfer port. The sealing blades are biased against the circumferential surface of the valve rotor by leaf springs housed underneath the blades in the axial grooves. The blade length is chosen such that these abut at either longitudinal end against the axially facing sides of the ring seals. The function of the so created "seal frame" _s to trap and prevent leakage of high pressure combustion gas from within the seal frame surrounding the transfer port and past the peripheral surface of the rotor body. Bishop's PCT document W094/11618 illustrates a slight modification of such sealing system in that it provides two further annular sealing elements on both axial sides of the sealing element frame described above. While it is noted Bishop's PCT document 094/11618 that the annular sealing elements could also be received in suitable annular grooves on the peripheral surface of the valve rotor, . so as to conjunctively rotate therewith, the above described sealing systems all provide a sealing frame stationarily surrounding the transfer port . There are a number of disadvantages associated with such sealing systems. Stationary sealing frames require the transfer port in the cylinder-head to have a substantial extension m circumferential direction in order to ensure a good volumetric efficiency during the induction stroke of the piston. Room constraints in the cylmder-head limit the possible arc lengtn of the transfer port in circumferential direction to about 70 * - 80', thus limiting volumetric efficiency in normal engines not provided with additional compressor or turbo- chargers . Furthermore, fluid cross-contamination between the inlet and exhaust port of the valve is possible during the compression and combustion strokes, as well as during the intake and exhaust strokes . While the sealing element frame surrounding the transfer port may prevent pressure loss by sealing off the radial gap between the valve rotor and the valve bore around the transfer port, the gap is maintained elsewhere, thus allowmg gas flow in circumferential direction between the exnaust and inlet ports at any time. The present invention seeks to provide an alternative to such prior art rotary valve and sealing systems. In a broad aspect, the present invention can be defined as relating to: a rotary valve for an internal combustion engine, comprising a cylindrical valve rotor having an let and an outlet port arranged the circumferential surface thereof, and a plurality of sealing elements received on the valve rotor such as to subdivide the circumferential surface of the rotor body to define discrete circumferential surface zones thereon, a predetermined one of the discrete surface zones bemg arranged such that, when the rotary valve is received within a valve bore in a cylinder head of an engine and tne sealing elements of the rotary valve abut on the valve bore surface, it periodically seals-off a transfer port m the cylinder head, for which the rotary valve serves as closing and opening means, during at least part of the compression and combustion strokes performed the engine, whereby air-fuel mixture compressed in the compression stroke and combustion gases created durmg combustion are substantially prevented from exiting through the transfer port into the inlet or outlet ports of the valve. In other words, the invention provides a rotary valve with a system of discrete sealing frames wnich rotate with the rotary valve and which effectively seal off from one another a predetermined number of surface zones theron when the rotary valve is received in the valve bore of the cylinder head, the surface zones being correlated with the strokes performed durmg a cycle m the engine. In a further aspect of the present invention there is provided a rotary valve for an internal combustion engine, comprising: - a cylindrical valve rotor having • at least one mlet port located in the circumferential surface of the rotor body, an inlet passage extending from the mlet port to terminate in an opening in one of two axial end faces of the rotor body, • at least one exhaust port locateα in the circumferential surface of the rotor body, an exhaust passage extending from the exnaust port to terminate in an opening in the other one of the two axial end faces of the rotor body, • the rotor body bemg adapted to be mounted m a valve bore m a cylinder head of the engine for rotation with small radial clearance between the bore surface and tne circumferential surface of the rotor body, • the let and outlet ports being located with respect to one another on the circumferential surface of the rotor body and sized such that durmg rotation of the rotor body the ports periodically pass over a transfer port in the cylinder head communicating with a combustion chamber of the engine and allow air-fuel mixture to enter the combustion chamber via the mlet port and the mlet passage of the rotor body through an intake manifold of the cylinder head and be expelled from the combustion chamber via the exhaust port and exhaust passage of the rotor body through an exhaust manifold of the cylinder head accordance with the stroke timing sequence of the engine; - a plurality of axial sealing elements extending substantially parallel to the axis of rotation of the rotor body, one or more of the axial sealing elements being received with a predetermined fit in an associated one of a plurality of axial grooves formed in the circumferential surface of the rotor body, tne grooves being arranged with predetermined angular distance from one another, at least one axial sealing element being located on each side of the let and outlet ports, the axial sealing elements extending radially outwards from the rotor body to slidingly abut against the core surface; and - at least two annular sealing elements positioned along the axis of rotation of the rotor body, at least one of the annular sealing elements received with a predetermined fit in an associated annular groove formed in the circumferential surface of the rotor body on either axial end of the axial grooves and the intake and exhaust ports, the annular sealing elements bemg pre- loaded to extend radially outwards from the rotor body to slidingly abut against the bore surface. With the sealing system described above it is possible to "section" respective gap volume zones between the circumferential surface of the valve body and the bore surface to correspond with the exhaust, induction, compression and combustion stroke of a working member (i.e., a piston) in a cylinder to which such rotational valve is assigned. This enables to effectively subdivide and seal from one another in circumferential direction discrete rotor surface zones, which periodically align with the transfer port, one each such zone ceing associated with each one of said strokes carried out during one internal combustion engine cycle. The discretely sealed zones rotate with the rotor. Thus, sealing is not only effected around the transfer port of the cylinder head but for each of said zones separately or part zones thereof. This increases sealing efficiency in circumferential direction. Furthermore, providing the axial sealing elements on the valve rotor body permits to reduce the dimensions of the cylinder head transfer port in circumferential direction without penalising air intake amount capability during the induction stroke. What is more, the present rotary valve with its system of axial and radial seals located on the rotor body permits to obtain an optimum volumetric efficiency. It is, amongst other factors, the correlation between cylinder head transfer port size, valve intake and exnaust port dimensions and timed rotation of the valve rotor with the crank shaft of the engine, that is the opening and closure time windows, that determme volumetric efficiency. The present rotary valve design with axial sealing elements on the rotor body enables to optimise the length in circumferential direction of the valve rotor intake port to correspond with an actual time interval which air or air-fuel mixture ("charge") can actually be induced through the valve rotor into the cylinder during the induction stroke, thus raking the "intake window" or valve opening rate durmg induction completely independent from any constraints otherwise imposed by the seal systems used m prior art rotary valves. In other words, the size of the intake port can be chosen such that it is in fluid communication with the transfer port throughout the time period in which a vacuum is present in the engine cylinder to draw in charge into the combustion chamber without cross- contamination. Given the possibility of reducmg the circumferential extension of the transfer port it is also possible to prevent, if required, simultaneous opening of both exnaust and intake port into the transfer port, that is preventing an overlapping between transfer port, exhaust port and intake port during rotation of the valve, therefore preventing cross-contamination flow between exhaust and intake ports when passing over the transfer port durmg the transition between exhaust and induction stroke. The inclusion of the sealing elements on the rotor body allows tne valve ports to be dimensioned independently from the transfer port size and to avoid overlap without sacrificing high volumetric efficiency. This also results in cleaner emission and, thus, reduced pollution. Further, cy arranging the axial sealing elements on the rotor bocy it is possible to dispense with the necessity for separate biasing elements to ensure abutment of the axial sealing elements against the valve bore surface. This "biasing" s provided by centrifugal forces actmg cn the sealing elements during rotation of the rotor body, which thus ensures proper and revolution- speed dependent abutment of the axial seals on the valve bore surface. While the centrifugal forces to which the rotor sealing elements are subjected durmg the start-up of the engine are small, therefore reducing during this initial perioα abutment pressure between valve bore surface and the axial sealing elements on either sioe of the discrete surface zone of the valve rotor correlated with the compression and combustion strokes, and therefore possibly not completely preventing pressure loss from the discretely sealed-off framed volume zone, reduced compression ratios do not necessarily present a problem when starting the engine, but are in many instances preferable to aid engine start-up against reduced reaction forces otherwise experienced at high compression ratios. On the other hand, if desired, it is possible to arrange suitably shaped leaf spring elements withm all or some of the axial grooves of the rotor oody such as to provide biasing means which positively abut the axial sealing elements against the valve bore surface independently of valve rotation. Also, because the exhaust and intake ports are sealed-off from one another by the annular sealing elements and the axial sealing elements disposed on either side of said ports, and the respective exhaust and inlet passages terminate at axially opposite end faces of the rotor body, the exhaust and air/charge manifolds can significantly be sealed-off from one another. Advantageously, the axial end faces of the valve rotor body can have a recessed central zone forming an intake part-cnamber and an exhaust part-chamber, respectively, wnich may have a concave spherical snape, the mlet and exhaust passages terminating in the respective part-chambers . By appropriately dimensioning said partial cnambers and using the valve bore volume unoccupied by the valve rotor body on either axial side thereof it is possible to provide useful intake and exhaust cnambers withm the cylinder-head. The intake and exhaust chambers are effectively sealed-off from one another in axial flow direction by the annular sealing elements of the rotor body. The volume of the intake chamber can be dimension so as to correspond with the swept volume of the cylinder of the engine to which the valve is assigned. Preferably, the rotary valve has a central load- bearing snaft which is integral with the valve rotor body, thus enabling a more compact design than sleeve/or tubular shaped rotary valves. It is of course also possible to mount a given number of rotor bodies fixed against rotation and axial movement on a common load bearing shaft. Preferably, the sealing elements are dimensioned to provide a small clearance play between surfaces of adjoining sealing elements in a cold engine condition, and to provide sliding sealing contact of abutting sealing element surfaces in normal to hot engine conditions. Advantageously, the sealing rings are received in the associated annular grooves in the rotor body surface with a slide f t, with minimum possible axial play, such that relative rotational movement between sealing rings and rotor oody is permitted during rotation of the valve. This measure reduces friction forces and wear between rotary valve and valve bore while maintaining adequate sealing between facing surfaces thereof. When using conventional piston-type sealing rings with clearance gap it is preferaoie to arrange two sealing rings m each groove, thereby reducing the statistical possibility of having the gap in the rings coincide in their rotational position with the circumferential location of the transfer port and reduce sealing efficiency during the combustion and compression strokes during these alignments. Alternatively, one sealing ring could be held stationary against rotation by any conventional means, such as a fixing lug, withm the receiving groove in a rotational position which does not coincide with the discrete circumferential surface zones of the rotor body which are correlated with the combustion and/or compression stroke of the engine. Alternatively, a discontinuous sealing ring having overlapping and stepped portions or legs can be employed, thus eliminating ring end clearance gaps . Advantageously, the axial sealing elements are shaped as narrow, rectangular parallelepipeds, the surface of the sealing element which abuts against the valve bore surface having a radius of curvature correspondmg to that of the valve bore. The axial sealing elements are dimensioned to slidingly abut with their axial end faces against the axial facing surfaces of the respectively adjoining annular sealing elements when received in the axial grooves of the rotor body. Alternatively, the axial sealing elements can each comprise two narrow rectangular parallelepiped sections ter-engaged for sliding movement along their axial extension and axial biasing means for resiliently forcing the two sections m opposite axial directions. The parallelepiped sections can be dimensioned to fit side by side with a slide fit within the axially extending grooves, each naving a length which is smaller oy a predetermined amount than the axial groove length ano the distance between the surfaces of facing annular sealing elements in between which the composite axial sealing elements are to be received abutmgly. The biasing means, which can be a simple spring located in a slot in the facing sides of the parallelepiped sections and actmg between protrusions of the sections extending mto the respective other one sections' receiving slot, pushes the sections m opposite axial direction sucr. that one section abuts with its one terminal axial face against the adjacent annular sealing element and the other section aouts with its opposite terminal axial face against the other annular adjacent sealing element. The predetermined amount can be chosen such as to compensate for manufacturmg plays between abutting parts and take- up an amount equivalent to the thermal expansion of a one-part seal element between cold and overheating conditions of the engine. Thus, sucn two-part axial sealing blade or element allows to maintain a gap-free contact with the sealing rings respectively located at both axial ends thereof independent of engine temperature conditions and manufacturing plays, and thus provide an optimum "sealing frame" around each one of the circumferential surface zone the rotor body is divided mto (as described above) and effectively seal-off the radial gap between rotor surface and bore surface around said zones. As indicated, the circumferential surface of the rotor body is preferably divided mto four circumferentially, successively arranged zones respectively associated with the induction, compression, combustion and exhaust stroke performed by a piston in the cylinder of an engine operatmg in four stroke mode; the circumferential length of said surface zones can each be chosen such as to exactly be correlated with the respective stroke length between bottom dead centre ( "BDC'J and top dead centre ( "TDC'J of the piston. However, since vacuum generated durmg the actual induction stroke between TDC and BDC is still present in the cylinder after the pistcn passes BDC and starts moving upwards the compression stroke, the intake port located in the induction zone can be extended for an arc- length greater than π/2 x r (where r is the radius of the valve rotor body) to take advantage of the "compression lag", thus enabling longer induction time windows lengths in which air/charge can actually be fed mto the cylinder. For example, the actual intake port length ("IPL") in circumferential direction for a 4 stroke engine type can be expressed as IPL = 1/2 π x d (180" + ' + β') x 1/360' x 1/2 where d = diameter of cylindrical rotor body, 180' corresponds to the crank shaft rotation during the induction stroke between TDC and BDC; ' corresponds to a predetermined value of crank shaft rotation in the exhaust stroke before reaching TDC at the beginning of the induction stroke, i.e. a scavanging overlap; β' corresponds to a predetermined value of crank shaft rotation in the compression stroke after BDC at the end of the induction stroke, that is the value of crank shaft rotation correspondmg to the "compression lag". The actual intake window length ("IWL") is then: I L = IPL + TPL where TPL is the transfer port length. If the sizes of the transfer and intake ports are chosen to be the same and assuming a compression lag of 30' and overlap of 10 " , then the port sizes equate each to 55' arc angle opening or: TPL = IPL = 55' x 1/360 x iτ x d Of course, ' and β * can be 0 ' or any other value as appropriate in the circumstances. It is to be understood that specific values can easily be determined by the skilled addressee without the necessity of any mventive input. Further, the successive compression and combustion zones on the rotor body share a common part-zone ("ignition zone") which extends for a predetermined arc- length which correlates to the size of the transfer port plus a 5 '-20' crank-shaft rotation on either s de of TDC of the compression stroke of the piston. This ignition zone aligns with the transfer port during a critical phase overlapping the compression and combustion strokes, which phase extends from just before the charge in the combustion chamber is ignited and the piston is m a position just before or at TDC to when the piston is already moving downwards in the combustion stroke after maximum combustion pressure is experienced. Thus, the rotor body is advantageously provided with a total of six of above-mentioned axial sealing elements or blades, one each on either side of the induction and the exhaust zones, to prevent fluid cross-contam ation between the ports in said zones, and one at either end of the above-mentioned ignition zone to ensure proper sealing of the clearance gap between rotor body surface and bore surface during said first critical moments immediately prior to ignition and shortly after combustion. Because in carburator type-engines there is always a pressure differential between the intake and exhaust manifold, which is also present at the intake and exhaust ports of the rotary valve, it is advantageous to seal-off the discrete zones from one another in which these ports are located such as to substantially prevent gas flow therebetween. An advantageous rotary valve can be provided in that the inlet passage opens to both axial end faces of the rotor body, the exhaust passage includes a plurality of axial exnaust bores extending between both axial end faces of the rotor body, the exhaust bores being arranged with angular distance from one another with a sector of predetermined arc-length and located radially outward from the inlet passage openings, and the rotor body comprises a plurality of flow-through passages extending in axial direction between both axial end faces and located about the same radial distance away from the axis of rotation cf the rotor body as the inlet passage openings. Thus, a cylinder-head for a multi-cylinder engine adapted to receive a number of such discrete rotary valve members, the valve bore can be used as a charge-fresh air. feed duct for all valve members, since axial flow through the valve members is only restricted in the radially outward zone where the exhaust bores are located, and at the same time provide efficient cooling means for the rotary valves and bearings thereof. While the working temperature of the rotary valve is (partly) controlled by the temperature of the air/charge supplied through the valve into the combustion chamber, it is possible to also utilise existing cooling systems of the engine which the rotary valve is to be mounted. The zone surrounding the valve bore may be cooled by circulating engine coolant through suitably formed cavities within the cylinder-head. Cooling of the bearings of the rotary valve can be aided by any conventional means. Separate lubrication of the bearings, however, could be dispensed with for specific applications, where lubricant contents in the charge and exhaust gases is sufficient to ensure proper lubrication of rotary parts or self-lubricating contained bearings are used. In a further aspect of the present invention there is provided a cylinder head-rotary valve assembly for an internal combustion engine comprising: - at least one rotary valve as described above; - a cylinder head body having rotary valve cooling means, cylinder head cooling means, at least one cylindrical cavity for housmg the rotor body of the rotary valve, the cavity having a transfer port for communication with a combustion chamber of the engine, the outer diameter of the rotor body and the cavity diameter being cnosen such that when the rotary valve is installed in the cylinder heao cavity, a small uniform radial clearance gap is maintained between the rotor body circumferential surface and tne cavity surface, bearing supports arranged on opposite axial ends of the cylindrical cavity, intake manifold means arranged to oe in continuos (constant) fluid communication with the mlet port of the rotor body through the inlet cnannei via its opening in the one axial end face of the rotor body, and exhaust manifold means arranged to be in continuos (constant) or periodical fluid communication with the exhaust port of the rotor body through the exhaust channel via its opening in the other one axial end face of the rotor body, - bearing means for rotatably mounting the rotary valve on the bearing supports in an axially fixed manner, and - synchronising means coupled to the rotary valve (s) for connection with a cran shaft of the engine such that the rotary valve (s) is timed with the stroke sequence performed in the engine and to rotate the valve (s) to allow the intake and exhaust ports to periodically register with the associated transfer port to effect charge intake into and exhaust expulsion from the combustion chamber to which the rotary valve is assigned. Coolmg of the rotary valve may advantageously be solely provided by the intake air-charge for the combustion; the cylinder cooling means may be provided by a cool g water circuit and/or heat exchange f ns on the outside of the cylinder head. The bearing means may be any suitable conventional bearings used in automotive engines such as roller bearings, journals, bushes and the like, depending on the engine type, operation parameters and design life of such cylinder head assembly. The number of bearing elements can be determined as appropriate. The synchronising means may comprise, in a cylinder head for multi-cylinder engines, ournaled couplings between individual valve rotors, in case discrete rotary valves are used, or other type of couplings to ensure synchronicity of rotation of the rotary valve elements, and a drive mechanism coupling one shaft end of the rotary valve (s) with the crank shaft of the engine, such as a pinion and chain drive. In a particularly advantageous embodiment of the invention, the intake and exhaust manifold means of the cylinder head can be designed to be interchangeably used as intake or exhaust manifold, the intake and exhaust ports of the valve rotor then being sized equally and the rotary valve rotor being mirror symmetrical in longitudinal section so as to enable operation of an engine provided with such cylinder head rotary valve assembly with clockwise or anti-clockwise rotation of the crank shaft . When using a rotary valve wherein the inlet passage opens to both axial end faces of the rotor body and having a plurality of flow-through passages axially extending through the rotor body as described above, the cylinder head-rotary valve assembly may comprise a plurality of bearing supports comprised of a plurality of supporting plates, each of which is mountable in the cylinder head in an axially fixed manner and secured against rotation in predetermined locations between axially adjoining rotary valves so as to rotatably support the load bearing shafts of said rotary valves, each supporting plate having a plurality of axially extending passage holes arranged a radial distance apart circumferentially around the axis of rotation of the rotary valve so as to allow fluid passage in axial direction througn the support plates and between the through passages of rotary valves arranged on either side of each support plate, and each support plate having an arcuate slot extending axially between both axial end faces of the support plate and communicating with an exhaust opening in a peripheral surface of the support plate, the exhaust opening located such as to register in sealing manner with an exhaust manifold opening the cylinder head at said fixing location of each support plate, the width, arc-length and radial distance of the slot from the axis of rotation being chosen such as to allow periodical registration thereof with the axial exhaust bores of tne rotary valves durmg the exhaust stroke of the piston in the cylinders which are provided with said rotary valves . Advantageously, the support plates or the rotor bodies of the rotary valves can be provide with ring shaped sealing elements on the respective axial surfaces which face one another, the sealing elements being arranged such as to surround the passage holes and prevent fluid communication between the passage holes and througn passages on the one side and the arc snaped slot and the exnaust bores on the other side. The present invention and different aspects and advantages thereof will be more fully understood from the followmg description of preferred embodiments thereof given with respect to the accompanying drawings, in which: - Figure 1 is a perspective view of a rotor body of a rotary valve a first embodiment according to the invention; Figure 2 is an isometric view of a system of rotating sealing elements arranged in spaced relationship such as to be received m respective grooves in the rotor body illustrated in Fig. 1; - Figure 3 is an axial plan view of the rotor body of Fig. 1; - Figure 4 is a longitudinal section of the rotor body according to arrows A-B m Fig. 3 ; - Figure 5 is a schematic cross-section through a cylinder head-rotary valve assembly in accordance with the present invention; - Figure 6. is a schematic longitudinal section through a cylinder head-rotary valve assembly for a multi-cylinder internal combustion engine in accordance with the present invention, the rotor bodies being illustrated m a section similar as Fig. 4, - Figure 7 is a plan view in axial direction of a rotary valve in a second embodiment; - Figure 8 is a longitudinal section of the rotary valve along arrows c-d in Fig. 7, - Figure 9 is a schematic plan top view of a lower cylinder head section of a cylinder head rotary valve assembly for a four-cylinder internal combustion engine for use with four rotary valves as illustrated in Fig. 7 and 8, - Figure 10 is a plan view in axial direction of a support plate for rotatably mountmg the rotary valves illustrated in Fig. 7 and 8 in the cylinder head section illustrated in Fig. 9; - Figure 11 is a section of the support plate along arrows e-f in F g. 10; - Figure 12 is a schematic illustration showmg a rotary valve according to Fig. 7 and 8 co-operating with two support plates according to Fig. 10 and 11, and Figures 13 and 14 are isometric detail illustrations of an axial sealing element and a annular sealing element, respectively, as used tne rotary valves according to the invention, - Figure 15 is a longitudinal section of a rotary valve a third embodiment in accordance with the invention, the valve comprising a rotor body and a separate load bearing shaft onto which the rotor is mounted; - Figure 16 is an axial plan view of the rotor oody illustrated in Fig. 16. - Figure 17 is a schematic cross-section similar to Fig. 5 through a cylinder head-rotary valve assembly with a replaceable rotary valve liner or bush received with the valve bore in accordance with yet a further embodiment of tne present invention; and - Figure 18 is a longitudinal section of the rotary valve liner illustrated in Fig. 17. Referring first to Figs. 5 and 6, there is schematically illustrated a rotary valve 1 whicn is supported for rotation m a valve bore 31 of a cavity in a cylinder head 20 of an internal combustion engine. While Fig. 5 schematically illustrates a one-cylmder engine, it is understood that the cross-section according to Fig. 5 is also illustrative of a two-/or multi- cylinder internal combustion engine (see Fig. 6) , in which each engine cylinder 27, 27' is provided with one rotary valve 1, 1' to control in known manner tne opening and closing of a rectangular transfer port 23, 23' in the cylinder head 20 associated with each cylinder 27, 27' . The transfer port 23, 23' provides fluid communication between the combustion chamber 24 , 24 ' of the cylinder 27, 27' and the intake and exhaust manifold channels 28, 29 in the cylinder head 20 via the rotary valve 1, 1' . A reciprocating piston 26, 26' is arranged in cylinder 27, 27' in a known manner to drive a crank shaft (not shown) of the engine. The cylinder head 20 can be provided as a one piece housing (as _,s commonly the case with one-cylmder engines) or comprise lower and upper cylinder head sections 21 and 22. The cylinder head 20 is provided with suitably formed bearing pedestals 33 in the cylinder head cavity and bearing support end plates 34, which are arranged at both axial ends cf the valve bore 31, for rotatably supporting the rotary valve (s) 1, 1' by suitable roller bearings 36. In a multi-cylinder engine, adjoining rotary valves 1, 1' are coupled for synchronous rotation via suitable coupling journals, schematically illustrated at 35 in Fig. 6. The drive for the rotary valve (s) is provided by a conventional sprocket and chain drive 37 coupled to the crank shaft of the engine for timed rotation therewith. In a four-stroke type engine, rotary valve rotation speed is half crank shaft rotation speed so that exhaust and intake ports provided on the rotor body of the rotary valves, as will be described herein below, will coincide once during each revolution of the rotary valve 1, 1' with the transfer port 23, 23' m the cylinder head 20 during a full cycle comprising an induction, a compression, a combustion and an exhaust stroke of the piston 26, 26' in the respective cylinder 27, 27' . As can be best seen from Figs. 5 and 6, the cylindrical rotor body 2 of the rotary valve 1 is supported within the valve bore 31 so that tnere is a small radial clearance gap 32 between the circumferential surface 11 of the rotor body 2 and the internal surface of the valve bore 31 circumferentially enclosing the rotor valve body 2. The clearance gap 32 is provided, amongst other reasons, to take-up any thermal expansions and contractions the rotary valve and the cylinder head may be subjected to during operation of the engine and to inhibit seizing of the rotary valve with the cylinder head. The gap 32 also ensures that friction durmg rotation is limited to bearing point friction. It is to oe understood that the expression "small clearance gap" as used herein is not intended to be necessarily understood as the smallest possible gap which would still permit rotation of the rotor body without the circumferential surface thereof making contact with the valve bore surface, that is a sealing gap, but could be, for example, a l/2mm gap clearance or smaller. Turning now to Figs. 1 - 4, there is illustrated different representations a first embodiment cf a rotary valve 1 according to the invention. The rotary valve 1 comprises a cylindrical rotor body 2 having an integrally formed central load bearing shaft 12 extending from both axial end faces 6 and 10 of the rotor body 2. As best is seen in Figs. 1 and 4, each axial end face 6, 10 has a central concave surface zone 6a, 10a surrounding the shaft ends and a planar annular surface 6b, 10b radially outward therefrom. The rotor body 2 has on its circumferential surface 11 a rectangular mlet port 3 which extends via an mlet channel 4 through the rotor body 2 to terminate in an inlet opening 5 in the recessed surface 6a. A rectangular exhaust port 7 is provided on the circumferential surface 11 with angular spacing from the mlet port 3. The exhaust port 7 extends via an exhaust channel 8 through the rotor body 2 to terminate in an exhaust opening 9 in the recessed surface 10a on the opposite axial side of the rotor body 2. The specific size and path of the mlet and exhaust channels 4, 8 is dictated, amongst others, by fluid-dynamic parameters. As can be seen in Fig. 6, m a cylinder head for a multiple cylinder engine, the rotors 2 are received such that facing concave surfaces of adjoining valve rotors 2 form together with the interposed valve bore zone, wnere the rotary valve 1, 1' are jointly supported at 35, a chamber 39 in the cylinder head 20 common to two valves; in the specific valve arrangement of Fig. 6, since the facing concave surfaces are those in which the exhaust channels of the respective valves open, the chamber acts as a common exnaust chamber from which a single exhaust manifold channel 29 leads into the exnaust system of the engine. While not illustrated in Fig. 6, similar considerations apply in formmg a common intake chamber Detween adjoining rotary valves where the facing concave surfaces are those in which the let channels of the respective valves open. In the two-cylinder arrangement illustrated in Fig. 6, two intake chambers 40 are formed at either end of the cylinder head 20 by tr.e concave recessed surfaces in which the respective mlet channels of the rotor valves open and by the respectively adjoining valve bore zones sealingly closed by the bearing support end plates 34. An intake manifold lme 28 communicates with each intake chamber 40 and with an air intake system of the engine in known manner. As has hereinbefore been described, each rotary valve 1, 1' is timed with the reciprocating movement (stroke) of the respectively associated piston 26, 26' . Thus, discretely defined circumferential surface zones of the rotor body can be co-related to and can be said to be associated with a respective one of the strokes of the piston performed durmg one full cycle, i.e. the rotor body surface 11 can be subdivided in an exhaust, induction, compression, and combustion surface zone. The rotor body 2 is provided with a number of sealing elements 13a, 13b, 14a - 14f to provide so-called sealing frames surrounding the above-referred to discrete surface zones of the rotor body surface 11. The sealing elements 13a, 13b, 14a - 14f co-operate with the inside surface of the valve bore 31 to create sealed-off volume zones the annular gap volume between rotor and pore surface, thereoy substantially preventing gas-flow between said framed volume zones. As best seen in Fig. 1 and 2, the rotor body 2 has two circumferentially extending grooves 15a and 15b located on either side with distance from the edges of the intake and exhaust ports 3 and 7. In these anular grooves 15a and 15b are respectively positioned one sealing ring 13a, 13b. While conventional piston rings 13a, 13b having a small gap in the circumferential extension may be used, Fig. 14 shows a preferred form in which the free ends of the sealing ring are stepped and overlapped to provide a gap-free annular sealing element. The sealing rings 13a, 13b prevent gas passage from the combustion chamber 24 through the transfer port 23 along the valve bore 31 in axial direction past the axial end faces of the rotary valve. The sealing rings 13a, 13b and the grooves 15a, 15b are dimensioned so as to provide a slide fit which allows relative rotation of the rings with respect to the rotor body 2 while maintaining minimum possible axial play. The sealing rings 13a, 13b are pre-loaded such that when received in their respective grooves 15a, 15b they biaisingly abut against the circumferential surface of the valve bore 31 but are not inhibited from rotation. When the sealing ring comes to lie with its stepped-overlapping legs within the rotor surface zones associated with the compression and combustion zones, the compression and combustion pressure will serve to press the ring ends against the axially outward facing surface of the annular groove, thus enhancing gap-leakage prevention past the sealing ring ends (see Fig. 14) . Passage of gas from the combustion chamber 24 through the transfer port 23 in a circumferential direction of the rotor body 2 is restricted or limited to discrete surface zones by six (6) axially extending sealing blades 14a - 14f, which are angularly spaced from one another along the circumference of the rotor body surface 11 and received in correspondingly shaped and spaced axial grooves 16a - 16f extending between the annular grooves 15a, 15b. The length of the parallelepiped shaped axial sealing elements 14a - 14f is chosen such that when received in their respective grooves 16a, 16b they abut with their axial end faces against the respectively adjacent sealing rings 13a, 13b. One way to ensure a sealing abutment in axial direction is to provide a two-piece sealing blade 14 (Fig. 13) consisting of two parallelepiped blade sections 141, 142 having a groove and feather means 144, 145 for linear- reciprocatmg alignment such that the two plate sections can move in axial direction with respect to one another in a sliding manner. A spring 143 is arranged with the grooves such as to work together with the feather-groove means to provide a telescopically extendable and retractable, variable length composite blade design as illustrated Fig. 13, which maintains a sealing abutment of the axial end faces of the sealing blade between the sealing rings 13a, 13b. It should also be noted that the surface of each axial sealing blade 14a - 14f, which abuts against the valve bore surface can be formed arcuate so as to conform with the valve bore surface, that is said abutment surface has a radius of curvature corresponding to that of the valve bore. Turning again to Fig. 1 and 3, one groove each is located adjacent either circumferential end of the intake port 3 and exnaust port 7 of the rotor body 2. That is, the axial sealing blades 14a and 14b on either side of the exhaust port 7 and the herembetween extending arc sections of the sealing rings 13a and 13b provide above- mentioned sealing frame for the discrete exhaust zone of the rotor body, and the axial sealing blades 14b and 14s on either side of the intake port 3 and the herembetween extending arc sections of the sealing rings 13a and 13b provide a sealing frame for the discrete induction zone of the rotor body. The other two grooves 14c and 14d are located on the circumference on either side of an arcuate surface zone sector of about 20 '-35' as can be seen m Fig. 3. The position and relation of said surface zone with respect to the induction and exhaust surface zones is determined by the timing relationship between rotary valve and crank shaft rotation, that is the stroke sequence and length of stroκe. The grooves 14c and 14d are located such that the sealing blades 16c and 16d received therein come to be positioned during rotation of the rotary valve 1 in the valve bore 31 on either circumferential side of the transfer port 23 the cylinder head 20 durmg a time period extending immediately before ignition of the charge is effected in the combustion chamber of the cylinder before the piston reacnes TDC to when the piston has passed TDC and is on its downward combustion stroke after maximum combustion pressure was achieved in the combustion chamber. Durmg this period, the crank shaft rotation encompasses an angle of about 10'-40' . The above given value of 20 '-35' angle opening for the surface sector, also referred to as ignition surface zone, is exemplarily only and chosen only for the illustrated embodiment . It is evident that the specific circumferential length of the rotor surface which is to cover the transfer port during the above described pre- and-post ignition time window will vary depending on the circumferential extension of the transfer port. Thus, the ignition surface zone will have a circumferential length which is greater that the one of the transfer port in the cylinder head for which the rotor valve serves as a periodical closure, sealing and opening means. As has been stated hereinbefore, the axial sealing elements (blades) 14a - 14f are mounted in their receiving grooves 16a - 16f with glide fits such that they will abut against the surface of the valve bore 31 under the influence of centrifugal forces durmg rotation of the valve 1 But for the lubricant properties of the fuel and exhaust gases passing through the rotary valve mto and from the combustion chamber, the sealing rings and blades may not require a separate lubricant; this in turn requires a specific material selection for the sealing elements, which could be made out of conventional materials used for known piston sealing rings as well as ceramics, composite ceramics and the like, .vhich are chose such as to minimise friction and wear between moving parts as well as taking mto consideration the thermal loads the elements are subjected to. A second embodiment of a rotor body of a rotary valve in accordance with the present invention is illustrated in Fig. 7 - 8 and 12. The sealing system consisting of sealing rings and blades forming above described discrete sealing frame is the same as described hereinbefore, and thus any reference to the discrete rotor surface zones and sealing frame arrangement should be understood in light of above given description, unless otherwise stated. The circumferential surface 111 of the rotor body 102 has two annular grooves 115a and 115b, one each located axially adjacent the mlet and exhaust ports 103 and 107, which themselves are sized and located on the circumferential surface 111 as previously described with reference to the first embodiment. A total of six axial grooves 116a - 116f are angularly spaced from one another on the circumferential surface 111 in similar locations as described above. The sealing elements to be received in the annular and axial grooves have been omitted from Fig. 7 and 8 for clarity of illustration purposes but are the same as illustrated in Fig. 2 and described above. In contrast to the rotor body of Figs. 3 and 4, the intake port 103 leads via intake channel 104 to both axial ends of the rotor body 102 and opens (105) both concave axial surfaces 106a, 110a near the central load bearing shaft 112. The concave surface zones 106a and 110a have a smaller diameter than those of the first embodiment and, accordingly, the hereto radially outwardly adjoining ring surface zones 106b and 110b have a greater radial extension. A total of six exhaust bores 109 extend n axial direction through the rotor body 102 in angularly spaced apart relationsnip to open in the ring surface zones 106b, 110b. The exhaust bores 109 are confined withm a sector, to the circumferential rotor surface of wnich comprises the exhaust port 107 of the rotor oody 102. The exhaust port 107 is in fluid communication with each of these exhaust ports 109 via a common exhaust channel 108 Accordingly, the rotor body 102 illustrated in Fig. 7 and 8 provides two radially spaced apart zones for air/charge intake and exhaust gas expulsion, respectively, in both orientations along the axis of rotation of the rotary valve. Three angularly spaced apart passages 117 extend axially through the rotor body 102 open in both concave surfaces 106a, 110a. These passages 117 allow fluid passage in axial direction through the rotor body 102 withm the central zone surrounding the shaft 112, thus dispensing with the necessity of having to provide separate intake manifold line in the cylinder head for each (or each two) rotary valve elements as described above with reference to Fig. 6. Fig. 9 schematically illustrates the lower section 121 of a cylinder head 120 which is adapted to received four rotary valves according to Fig. 7, 8. As can be seen there, one intake manifold branch 128 is arranged on either axial end of the cylinder head section 121 to provide a common intake means for air/charge m axial flow direction into the valve bore 131 in which the rotary valves are to be mounted as described here later. The cylinder head is intended for a four cylinder engine and, therefore, has four transfer ports 123 the valve bore surface 131, for respective communication with an associated combustion chamber of the four cylinders of the engine. Inbetween neighbouring and at either side of the axially outermost transfer ports 123 are located slots 133, each adapted to receive a oeaπng support plate 140 (see Figs. 10-12) , as will be described here oelow, for rotatably mountmg the rotor valve members the cylinder head section 121. Within each slot 133 is located an exhaust manifold port 129a leading into the exhaust manifold system of the cylinder head. Fig. 10 and 11 illustrate a bearing support plate 140 having a central bore 141 for receiving and fixing therein a roller bearing or ournaled coupling for the load bearing shaft of two rotary valves to be supported by each support plate with the lower cylinder section illustrated in Fig. 9. The support plate 140 is also provided with a plurality of angularly spaced apart air/charge passage holes 142 surrounding the central bore 141 and extending axially through the plate at a radial location such as to lie withm the diameter of the concave surface zone 110a, 116a and allow fluid communication with the passages 117 and intake opening 105 of the rotor body 102. Thus, fluid communication is not dependent upon registration of said openings in the rotor body with those the support plate, but is constant because the recessed concave axial ends of the rotor body provide supply chambers for said openings, as can be also seen in Fig 12. An annular groove 143 is provided on each axial surface of the support plate 140 encircling the passage holes 142 and adapted to receive a sealing ring 144. The slide fit between groove 143 and sealing ring 144 is such as to allow rotation of the sealing ring with the groove. The support plate 147 is further provided with an arcuate slot 145 of predetermined circumferential extension and extending axially through the plate sucn as to open via an exhaust cavity 146 in a radial opening 147 in the circumferential surface of the support plate 140. The radial location and length of the arcuate slot 145 is chosen such as to coincide with the radial location of the exhaust bores 109 of the rotor body 102 and the length of the sector in which these exhaust bores 109 are located. Thus, as can be best seen in the schematic illustration of Fig. 12, and with reference to Fig. 9, each support pla.te 140 can be mounted in a respective slot 133 in the cylinder head section 121 and fixed against rotation so that the exhaust cavity 146 and its radial opening 147 coincide and sealingly cover the exhaust manifold port 129a within said slot 133 to provide fluid communication therebetween. Further, during each complete rotation of the rotary valve 102 which is rotatably supported between two support plates 140, the axial exhaust bores 109 will pass over and register with the arcuate slot 145 of adjacent support plates 140 and thus provide communication between the transfer port 123 and the exhaust manifold port 129a of the cylinder head section 121 via the exhaust port 108 and axially extending exhaust bores 109 of the rotor body 102 and the arcuate slot 145 and radial opening 147 of the support plates 140. The sealing rings 144 received on either side of the support plate 140, which separate the arcuate slot 145 and the passage holes 142 of the support plate 140 abut hereby against the axial end ring surface zones 106b, 110b of the respectively adjoining rotor body 102 and prevent any substantial cross-leakage of fluids into and from the axial end concave cavities of the rotor body 102 in which the air/charge passages 117 and the axial intake opening 104 of the intake channel 104 are provided. While the passage holes 142 of the support plates 140 and the through passages 117 in the rotor bodies 102 ensure constant fluid communication in axial direction along adjoining rotary valve members, thus allowing the air/charge for a combustion process to provide efficient continuous coolmg of the rotary valves curing the exhaust, induction, compression and combustion strokes of the engine, the exhaust manifold is only in timed periodic fluid communication with the combustion chamoers of the cylinder via the respective rotary valve members during the respective exhaust stroke of the piston the associated cylinder. As has been described above, one important feature of the present invention is to provide a rotary valve with a system of discrete sealing frames which rotate with the rotary valve and which effectively seal off from one another a predetermined given number of surface zones thereon, when the rotary valve is received in the valve bore of the cylinder head, the surface zones correlated with the strokes performed during cycle in the engine. One of these discrete sealing frames is arranged such that the two axially extending sealing blades of this frame come to lie adjacent in circumferential direction to the transfer port edges such as to effectively seal the cylinder combustion chamber by means of said sealing frame and the framed circumferential surface zone of the rotor body during the critical moments immediately prior to and after ignition of the charge in the combustion chamber to which the rotary valve is assigned, that is for about 5 '-20' crank shaft rotation after the compression on either side of the pistons top dead centre (TDC) . This cranK shaft rotation sector corresponds to the final stages of the compression stroke and the initial stages of the combustion stroke of the piston. Also, discrete sealing frames are provided to surround the exhaust and intake ports of the rotary valves and increase overall sealing efficiency. A further embodiment of a rotor body of a rotary valve in accordance with the present invention is illustrated schematically in Figs 15 and 16. But for the differences noted below, the rotor body 202 and the sealing system consisting of sealing rings and blades forming above described discrete sealing frame s similar as described with reference to Figs 1 - 4 , and thus reference should be made as well to the description given with reference to those figures. In modification of the embodiment illustrated in Figs 1 - 4, a total of four annular grooves 215A, 215B are provided on the circumferential surface 211 of the rotor body 202, two grooves each on either s de of the exhaust and inlet port 203, 207. The groove 215A and 215B are adapted to each receive one appropriately dimensioned sealing ring (not illustrated) as described with reference to the other two embodiments of the rotor body. The rotor body 202 is received on a discrete load bearing shaft 212 and secured against rotation thereon by means of a key 212a which is received in an axially extending key groove 212b in the central zone 212c of the shaft 212d as well as in a correspondingly shaped key way 216 machine in the inner-peripheral surface of bore 212e of the rotor body 202. As will be appreciated, the central zone 212c on which the rotor body 202 is received has a slightly smaller diameter to allow a glide fitting between the two parts, whereby the rotor body 202 is secured against axial movement along the axis of the shaft 212 by means of two circlips 212f engaging in anular retention grooves 212g on either axial side of the rotor body 202. Otherwise, the rotary valve is as described with reference to Figs 1 - 4. In Fig. 17 is illustrated a further embodiment of a cylinder head - rotary valve assembly for an internal combustion engine. But for the differences noted below, this assembly is similar to the one illustrated in and described with reference to Fig. 5, and thus. where appropriate, same reference numerals have been used to designate same parts. It will be appreciated that the rotary valve can incorporate a cylindrical rotor body 2, 102 or 202 as illustrated with reference to the different embodiments thereof pπorly described. The rotary valve 1 is supported for rotation in the cylindrical valve bore 31 in the cylinder head 20 of the internal combustion engine as priorly described. A replaceable, cylindrical liner 50 is provided for the or each rotary valve rotor. The liner 50 has an outside diameter such that its outer- peripheral surface 52 is sealing engagement with the inner-peripheral surface of the valve bore 31, preferably with a slight interference fit to prevent rotational movement of the liner 50 within the bore 31; Other known means may be used to prevent rotation and axial movement of the liner 50 within the cavity 31. A transfer window 51 corresponding in size with the transfer port 23 of the cylinder head 20 extends through the peripheral wall of the liner 50 and is arranged to coincide with said transfer port 23 when mounted in the cylinder head cavity 31. The inner-peripheral surface of the housing cavity 31 is provided with a number of depressions 42 which are arranged to partially surround the liner body 50 and which form cavities for circulating cooling or lubricating fluid; individual cavities 42 are m fluid communication with a common drainage channel 44 extending through the cylinder head 20 and communicating with a similar drainage channel of the engine's cylinder body 27. The valve liner 50 is provided diametrically opposite the transfer window 51 with two oil feedmg holes 53 (see also Fig. 18) extending througn the peripheral wall and which are in fluid communication with a oil feedmg channel 43 of the cylinder head housing 20. Further, a plurality of oil drainage holes 54 extending radially througn the liner wail are arranged angularly spaced from one another and located such as to be in fluid communication with the cavities 42 of the cylinder head housmg 23. The side diameter of the cylindrical liner 50 is sized such that the cylindrical rotor body 2, 102, 202 of the rotary valve 1 is received with a predetermined clearance fit to provide for the small radial clearance .gap 32 between the circumferential outer surface 11 of the rotor body 2, 102, 202 and the internal circumferential surface 55 of the cylindrical liner 50, in similar fashion as was described with reference to the embodiment illustrated Fig. 5. Advantageously, the material of the liner or bush 50 is selected such as to provide adequate wear resistance for the sealing elements (rings and blades) (see Fig. 1) which provide the sealing frames previously described. Currently, it is believed that sintered cast iron or metal-ceramic composite materials will provide such adequate wear resistance. In operation of the rotary valve, cooling and/or lubricating fluid is fed via oil feeding channel 43 and oil feeding bores 53 mto the gap 32 between the outer peripheral surface 11 of the rotor body 2 and the inner- peripheral surface 55 of the cylindrical liner 50. Here, the cool g and/or lubricating fluid, e.g. oil, lubricates and cools the rotor body and sealing elements (sealing rings and sealing blades) and can exit through the liner dram holes 54 into the cylinder head drain cavities 42 from where it can return via dram channel 44 to the sum of the engine . It will be appreciated by those skilled the art that the above description of preferred embodiments provides tne basic concepts underlining the present invention; specific dimensions and materials of the rotary valve rotor, seals and cylinder head, as well as dimensional inter-relationships of the co-operating ports and openings and surfaces involved in controlling air/charge intake to the combustion chamber during induction, pressure leakage during the ignition phase as well as during the combustion and compression strokes, and gas exhaust during the exhaust stroke can be readily chosen to meet specific requirements. It is also evident that any number of axial sealing blades can be provided in angular spaced relationship on the rotor body surface, but that proper angular positioning of the sealing blades can reduce such number without detrimentally affecting sealing efficiency. Also, the rotary valve is not solely intended for use with reciprocating piston, 4-stroke type engines but can be used in other engines such as, for example, having rotary pistons (Wankel) or engines having a 2-stroke combustion cycle. In the latter case, the rotary valve rotor need only have one intake port since the exhausts are expelled through an opening in the cylinder wall itself. Applications include automotive, industrial, marine engines and the like.

Claims: Claims 1. A rotary valve for an internal combustion engine, comprising a cylindrical valve rotor having an inlet and an outlet port arranged in the circumferential surface thereof, and a plurality of sealing elements mounted on the valve rotor such as to subdivide the circumferential surface of the rotor body to define discrete circumferential surface zones thereon, a predetermined one of the discrete surface zones being arranged such that, when the rotary valve is received within a valve bore in a cylinder head of an engine and the sealing elements of the rotary valve aout on the valve bore surface, it periodically seals-off a transfer port the cylinder head, for which the rotary valve serves as closing and opening means, durmg at least part of the compression and combustion strokes performed the engine, whereby air-fuel mixture compressed during the compression stroke and combustion gases created during combustion stroke are substantially prevented from passing into the mlet or outlet port of the valve during these strokes. 2. A rotary valve for an internal combustion engine comprising: - a cylindrical valve rotor having - at least one inlet port located in the circumferential surface of the rotor body, an let passage extending from the inlet port to terminate in an opening in one of two axial end faces of the rotor body, at least one exhaust port located in the circumferential surface of the rotor body, an exnaust passage extending from the exhaust port to terminate in an opening in the other one of the two axial end faces of the rotor body, - the rotor body being adapted to be mounted in a valve bore a cylinder head of the engine for rotation with small radial clearance between the bore surface and the circumferential surface of the rotor body, - the mlet and outlet ports being located with respect to one another on the circumferential surface of the rotor body and sized such that durmg rotation of the rotor booy the ports periodically pass over a transfer port in the cylinder head communicating with a combustion chamber of the engine and allow air-fuel mixture to enter the combustion chamber via the mlet port and the mlet passage of the rotor body through an intake manifold of the cylinder head and be expelled from the combustion chamυer via the exhaust port and exhaust passage of the rotor body through an exhaust manifold of the cylinder head in accordance with the stroke timing sequence of the engine; - a plurality of axial sealing elements extending substantially parallel to the axis of rotation of the rotor body, one or more of the axial sealing elements being received with a predetermined fit in an associated one of a plurality of axial grooves formed in the circumferential surface of the rotor body, the grooves being arranged with predetermined angular distance from one another, at least one axial sealing element oemg located on each side of the inlet and outlet ports, the axial sealing elements extending radially outwards from the rotor body to slidingly abut against the bore surface; and - at least two annular sealing elements positioned along the axis of rotation of the rotor body, at least one of the annular sealing elements received with a predetermined fit in an associated annular groove formed in the circumferential surface of the rotor body on either axial end of the axial grooves and the intake and exhaust ports, the annular sealing elements being pre- loaded to extend radially outwards from the rotor body to slidingly abut against the bore surface. 3. A rotary valve m accordance with claim 2, wherein the axial end faces of the rotor body have a recessed central zone forming an intake part-chamber and an exhaust part-chamber, respectively, the mlet and exhaust passages terminating in the respective part-chamber. 4. A rotary valve in accordance with claim 2 or 3 , wherein the recessed central zone is concave spherical in shape. 5. A rotary valve m accordance with any one of claims 1 to 3 , wherem the rotor body comprises a load bearing shaft for journaling the rotor oody in the cylinder head. 6. A rotary valve in accordance with claim 5, wherein the load bearing shaft is integral with the rotor body and extends axially from both axial end faces of the rotor body. 7. A rotary valve in accordance with any one of the preceding claims, wherein the sealing elements are dimensioned to provide a small clearance play between surfaces of adjoining sealing elements in a cold engine condition, and to provide sliding sealing contact of abutting sealing element surfaces in normal to hot engine conditions. 8. A rotary valve in accordance with any one of claims 2 to 7, wherein the predetermined fit of the annular sealing elements in the associated annular grooves is a slide fit and allows rotation of the sealing elements withm the annular grooves. 9. A rotary valve in accordance with any one of claims 2 to 8, wherein two annular sealing elements are received in each associated annular groove. 10. A rotary valve in accordance with any one of claims 2 to 8, wherein the rotor body has four annular grooves, two each on opposite axial sides of the intake and exhaust ports, at least one annular sealing element being received within each groove. 11. A rotary valve in accordance with any one of claims 2 to 10, wherein the annular sealing elements are piston rings as used in reciprocating type internal combustion engines. 12. A rotary valve in accordance with any one of ciaims 2 to 10, wherein the annular sealing elements are gap- free, stepped ring end piston rings. 13. A rotary valve in accordance with any one of claim 2 to 12, wherein the predetermined fit of the axial sealing elements in the associated axial grooves is a tight slide fit such as to allow centrifugal forces acting on the axial sealing elements that upon rotation of the rotor body to bias the axial sealing elements radially against the valve bore surface. 14. A rotary valve in accordance with claim 13, wherein the axial sealing elements are shaped as narrow rectangular parallelepipeds, the surface of the sealing element which abuts against the valve bore surface having a radius cf curvature corresponding to that of the valve bore. 15. A rotary valve in accordance with claim 14, wherein the axial sealing elements are dimensioned to slidingly abut with their axial plane ends against tne facing surfaces of the respectively adjoining annular sealing elements when received in the axial grooves of the rotor body and when under expected working temperature conditions in the engine. 16. A rotary valve in accordance with claim 13, wherein the axial sealing elements comprise two narrow rectangular parallelepiped sections inter-engaged for sliding movement along their axial extension and axial biasing means tending to move the two sections in opposite axial directions. 17. A rotary valve in accordance with any one of ciaims 1 to 16, wherein the circumferential surface of the rotor body is divided into four circumferentially successively arranged zones corresponding to an induction, a compression, a combustion and an exhaust stroke performed by a piston in a cylinder of the engine operatmg in four-stroke mode, the intake port located in the induction zone extending for an arc length equivalent to a sector angle of about 90 to 120 degrees and the compression and combustion zones comprising an overlapping ignition zone extending for an arc length greater than the extension of the transfer port in circumferential direction, and wherein the rotor body is provided with a total of six of the axial sealing blades, one each on either end of the induction and the exhaust zones, and one at either end of the ignition zone. 18. A rotary valve in accordance with any one of claims 1 to 17, wherein the sealing elements are made from wear resistant spring steel material. 19. A rotary valve in accordance with any one of ciaims 1 to 17, wherein the sealing elements are made from wear resistant ceramic material or a composite steel-ceramic material . 20. A rotary valve in accordance with any one of ciaims 2 to 18, wherein the mlet passage opens to ooth axial end faces of the rotor body, wnerem the exhaust passage includes a plurality of axial exhaust bores extending between both axial end faces of the rotor oody, the exhaust bores oeing arranged with angular distance from one another withm a sector of predetermined arc length and located radially outward from the let passage openings, and wherein the rotor body comprises a plurality of flow-through passages extending axial direction between both axial end faces and located about the same radial distance away from the axis cf rotation of the valve body as the let passage openings. 21. A cylinder head - rotary valve assembly for an internal combustion engine, comprising: - at least one rotary valve in accordance with any one of claims 1 to 20; - a cylinder head body having rotary valve cooling means, cylinder head cooling means, at least one cylindrical cavity for housmg the rotor body of the rotary valve, the cavity having a transfer port for communication with a combustion chamber of the engine, the outer diameter of the rotor body and the cavity diameter being chosen such that when the rotary valve is installed in the cylinder head cavity, a small uniform radial clearance gap is maintained between the rotor body circumferential surface and the cavity surface, bearing supports arranged on opposite axial ends of the cylindrical cavity, intake manifold means arranged to be in continuous fluid communication with the mlet port of the rotor body via its opening in the one axial end face of the rotor body, and exhaust manifold means arranged to be in continuous or periodical fluid communication with the exnaust port cf the rotor body via its opening in the other one axial end face of the rotor body, - bearing means for rotatably mounting the rotary valve on the bearing supports in an axially fixed manner, and - synchronising means coupled to the rotary valve for connecting the later with a crank shaft of the engine such that the rotary valve s timed with the stroke sequence performed in the engine and to rotate the valve to allow the intake and exhaust ports to periodically register with the transfer port to effect charge intake mto and exhaust expulsion from the combustion chamber to which the rotary valve is assigned. 22. A cylinder head - rotary valve assembly for an internal combustion engine, comprising: - at least one rotary valve in accordance with any one of claims 1 to 20; - a sleeve-like cylindrical valve liner, having a communication port extending through its peripheral wall, and arranged to receive the rotary valve for rotation therein, the outer diameter of the rotor body and the inner diameter of the liner being chosen such that a small radial clearance gap is maintained between the rotor body of the valve and the mside of the liner; - a cylinder head body having rotary valve coolmg means, cylinder head coolmg means, at least one cylindrical cavity nav g a transfer port for communication with a comoustion chamber of the engine, the rotary valve liner being installed the cylinder head cavity aga st rotation and such that the transfer port and communication port register with one another, bearing supports arranged on opposite axial ends of the cylindrical cavity, intake manifold means arranged to be m continuous fluid communication with the mlet port of the rotor body via its opening in the one axial end face of the rotor body, and exhaust manifold means arranged to be in continuous or periodical fluid communication with the exhaust port of the rotor body via its opening m the other one axial end face of the rotor body, - bearing means for rotatably mountmg the rotary valve on the bearing supports in an axially fixed manner, and synchronising means coupled to the rotary valve for connecting the later with a crank shaft of the engine such that the rotary valve is timed with the stroke sequence performed in the engine and to rotate the valve to allow the intake and exhaust ports to periodically register with the transfer port to effect charge intake into and exhaust expulsion from the combustion cnamber to which the rotary valve is assigned. 23. A cylinder head - rotary valve assembly accordmg to claim 21 or 22, wherein the intake and exhaust manifold means of the cylinder head are designed to be interchangeably used as intake or exhaust manifolds and the intake and exhaust ports of the valve rotor are sized equally so as to enable operation of an engine provided with such assembly with clockwise or anti-clockwise rotation of the crank shaft . 24. A cylinder head - rotary valve assembly according to claim 21, 22 or 23, and adapted for a multi-cylinder engine of reciprocating type, wherein each cylinder is allocated one rotary valve, tne valves having a common load bearing sr.aft or individual load bearing shafts of axially adjoining valves being connected by journal couplings. 25. A cylinder head - rotary valve assembly according to claim 21, 22 or 23 and adapted for smgle piston engines of reciprocating type, wherein the cylinder head is a one piece construction with a through valve bore for housing the rotary valve, the rotary valve being held withm the valve bore by bearmg support end plates sealingly closing the valve bore . 26. A cylinder head - rotary valve assembly for a multi- cylinder engine of reciprocating type according to any one of claims 21 to 24 and when having a plurality of rotary valves accordance with claim 20, wnerem the bearing supports comprise a plurality of supporting plates, each of which is mountable in the cylinder head in an axially fixed manner and secured against rotation m predetermined locations between axially adjoining rotary valves so as to rotatable support the load bearing shafts of said rotary valves, each supporting plate having a plurality of axially extending passage holes arranged a radial distance apart circumferentially around the axis of rotation of the rotary valve so as to allow fluid passage axial direction through the support plates and between the through passages of rotary valves arranged on either side of each support plate, and each support plate navmg an arcuate slot extending axially between both axial end faces of the support plate and communicating with an exhaust opening in a peripheral surface of the support plate, the exhaust opening located such as to register in sealing manner with an exhaust manifold opening in the cylinder head at said fixing location for each support plate, the width, arc-length and radial distance of the slot from the axis cf rotation being chosen sαch as to allow periodical registration thereof with tne axial exhaust bores of the rotary valves durmg the exhaust stroke of the engine. 27. A cylinder head - rotary valve assembly according to claim 26, wherein the support plates or the rotor bodies are provided with ring shaped sealing elements on the respective axial end faces which face one another, the sealing elements arranged such as to surround the feed holes and prevent fluid communication between the feed holes and through passages on the one side and the arc- shaped slot and exhaust bores on the other side. 28. A rotary valve substantially as hereinbefore described with reference to the accompanying figures. 29. A cylinder head - rotary valve assembly substantially as hereinbefore described with reference to the accompanying figures.

Inventors: SMITH BRIAN, SMITH WAYNE, SMITH, BRIAN, SMITH, WAYNE
Applicants: SMITH BRIAN, SMITH WAYNE, SMITH, BRIAN, SMITH, WAYNE
Application year: 1996
Main classification: F01L7
IPC codes: F01L7, F02B75