During the emergence of the reciprocating piston internal combustion engine at the turn of the century two main valve systems were in use-rotary and poppet. The rotary valve sought to avoid the inefficiencies of the reciprocating poppet valve. However, the latter predominated due to an inability of the former to perform reliably without excessive oil consumption.

GB 463412 (ASPIN) discloses a rotary valve providing a valve member which rotates axially with a piston and contains an offset combustion chamber. Aspin was later responsible for a number of further improvements to this rotary valve, culminating in GB 1516092. The"Aspin"valve was effectively a cone valve relying on a lapping contact with its housing with oil lubrication to maintain a seal, thus resulting in high emission levels.

A development of the Bourneville rotary valve-wherein the valve member rotates at 90° to the axis of the piston- is disclosed in US 4,976,232 (COATES). This document describes a single circular floating seal per cylinder, which is: (a) contained and sealed against a rotary valve outside the combustion chamber, and (b) sealed against pressure primarily from within the

seal section.

It is an object of at least one aspect of the present invention to provide an improved valve over those known in the art.

It is a further object of at least one aspect of the present invention to obviate or mitigate one or more of the aforementioned problems in the prior art.

According to a first aspect of the present invention there is provided a valve for use with an internal combustion engine comprising at least one cylinder having a reciprocable piston, the valve comprising a valve seat having at least one inlet and/or at least one outlet, a rotatable valve member mountable within the valve seat at a compression end of one of the at least one cylinders and having at least one orifice extending therethrough between the valve seat and an interior of the cylinder, wherein there is provided a seal member (s) between the valve member and the at least one inlet and/or the at least one outlet.

The valve seat may provide at least one inlet and at least one outlet.

Advantageously the/each seal member may be resiliently biased towards a sealed position.

Advantageously also, the/each seal member may be substantially circular in planar cross-section.

Advantageously also, the/each seal member may be substantially"L"shaped in perpendicular cross-section.

Advantageously also, the valve seat may comprise a

substantially concave portion, which may preferably be substantially hemispherical.

Advantageously the concave portion faces the cylinder, the valve member being retained therebetween.

Advantageously also, the valve seat may be non- contacting with the valve member.

Advantageously also, the/each respective seal member may initially seal between the valve member and the at least one inlet and/or the at least one outlet, whilst during a combustion cycle of the at least one cylinder, in use, combustion maintains sealing between the valve member and the at least one inlet and/or outlet.

Advantageously the/each seal includes a sealing surface which may include a recess.

Preferably the valve member is rotatable about a longitudinal axis of the at least one cylinder.

Preferably the orifice has a first opening adjacent the valve seat and a second opening adjacent the at least one cylinder.

Preferably rotation of the valve member causes the first opening of the at least one orifice to sequentially register/align with the at least one inlet and the at least one outlet.

Advantageously at least a major portion of the orifice is offset relative to an axis of rotation of the valve member.

Advantageously a centre of the second opening of the

orifice is offset relative to an axis of rotation of the valve member.

Advantageously also, the orifice comprises a chamber which constitutes a major portion of a compression space at a moment of maximum compression within the cylinder, in use.

Preferably a first seal member (s) is/are provided between the valve member and the/each inlet.

Preferably a second seal member (s) is/are provided between the valve member and the/each outlet.

Preferably the valve seat provides a spark plug between the/each inlet and adjacent outlet.

Preferably a third seal member (s) is/are provided between the valve seat and a shaft extending from the valve member.

Advantageously each seal member is carried by the valve seat.

In a preferred embodiment each seal member may comprise a primary seal member which may comprise a ring member carried in a groove formed in the valve seat.

Advantageously a sealing surface of a primary seal member may be adapted to seal against an adjacent surface of the valve member.

In the preferred embodiment each seal member may also comprise a secondary seal member which may comprise an o- ring carried in a slot formed in a side wall of the primary seal member.

Preferably each seal member is biased towards the valve

member, for example, by resilient loading means such as a spring, e. g. a wavy spring.

The valve member may be at least partly hollow and provide a cavity therein.

A first hollow tubular body/shaft may communicate with and extend from the cavity.

A second hollow tubular body may be positioned within the first tubular body.

Cooling fluid may be circulated through the cavity via the second and first tubular bodies.

According to a second aspect of the present invention there is provided a seal member for use in a valve according to the first aspect.

According to a third aspect of the present invention there is provided an internal combustion engine having a valve according to the first aspect.

The engine may be single or multi-cylinder.

The engine may be of any size and may be a two or four stroke engine.

The engine may be a petrol or diesel engine.

Particular, the engine may be: a two or four stroke spark ignition engine; a two or four stroke compression ignition (diesel) engine; a two stroke uniflow compression ignition (diesel) engine.

According to a fourth aspect of the present invention

there is provided a valve for use with an internal combustion engine comprising at least one cylinder having a reciprocable piston, the valve comprising a valve seat, a rotatable valve member mountable within the valve seat at a compression end of one of the at least one cylinders and having at least one orifice extending therethrough between the valve seat and an interior of the cylinder, wherein there is provided a seal member (s) sealing between the cylinder and an at least one inlet and/or an at least one outlet, each/the seal member (s) being biased by resilient means towards a sealed position.

According to a fifth aspect of the present invention there is provided a valve for use with an internal combustion engine comprising at least one cylinder having a reciprocable piston, the valve comprising a valve seat, a rotatable member mountable within the valve seat at a compression end of one of the at least one cylinders and having at least one orifice extending therethrough between the valve seat and an interior of the cylinder, wherein the valve seat provides a substantially hemispherical concave seating surface.

According to a sixth aspect of the present invention there is provided a valve for use with an internal combustion engine comprising at least one cylinder having a reciprocable piston, the valve comprising a valve seat, a rotatable valve member mountable within the valve seat at a compression end of one of the at least one cylinders and

having at least one orifice extending therethrough between the valve seat and an interior of the cylinder, wherein the valve seat is spaced from the valve member.

According to a seventh aspect of the present invention there is provided a valve for use with an internal combustion engine comprising at least one cylinder having a reciprocable piston, the valve comprising a valve seat, a rotatable valve member mountable within the valve seat at a compression end of one of the at least one cylinders and having at least one orifice extending therethrough between the valve seat and an interior of the cylinder, wherein there is provided a seal member (s) initially sealing between the cylinder and an at least one inlet and/or an at least one outlet, and wherein further, in use, combustion within the cylinder causes the seal member (s) to further seal between the at least one inlet and/or the at least one outlet.

According to an eighth aspect of the present invention there is provided a motorised apparatus having an engine having a valve according to the first, fourth, fifth, sixth or seventh aspects of the present invention.

The motorised apparatus may be a vehicle, for example, an automobile; motorcycle; passenger, goods or commercial vehicle with one or more wheels or tracks or skids; a military vehicle having one or more wheels, tracks or skids; a marine craft whether with inboard and/or outboard drives; an amphibious vehicle with one or more wheels, tracks or

skids; a hovercraft ; an aircraft.

The motorised apparatus may be a pump or generator, whether for commercial, industrial and/or domestic use, whether stationary or mobile.

According to a ninth aspect of the present invention there is provided a valve for with an internal combustion engine comprising at least one cylinder having a reciprocable piston, the valve comprising a valve seat, a rotatable valve member mounted within the valve seat at a compression end of one of the at least one cylinders and having at least two orifices extending therethrough between the valve seat and an interior of the cylinder, wherein there is provided a fuel injector located substantially centrally within the rotatable valve member between the at least two orifices.

Preferably the outlet of the injector is provided in a portion of the valve seat, and preferably comprises an outwardly extending cone.

Preferably the orifices are provided symmetrically about the valve seat.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drainas, which are:- Fig. 1 a partial cross-sectional side view of an internal combustion engine including a rotary valve according to a first embodiment of the present invention; Fig. 2 a cross-sectional top view of the valve of Fig.

li Fig. 3 a detailed side view of a seal provided in the valve of Fig. 1 ; Fig. 4 a partial side view to an enlarged scale of the seal of Fig. 3; Fig. 5 a view of an orifice of a valve member of the valve of Fig. 1 taken in direction"A" ; Fig. 6 a cross-sectional top view of a rotary valve according to a second embodiment of the present invention.

Fig. 7 a partial side view to an enlarged scale of an improved seal of Fig. 4; Fig. 8 a partial side view to an enlarged scale of an alternative embodiment of the improved seal of Fig. 7; Fig. 9 a detailed side view of the improved seal of Fig. 8 provided in the valve of Fig. 1 ; Fig. 10 a partial side view to an enlarged scale of a modified improved seal of Fig. 4; Fig. 11 a partial side view to an enlarged scale of an alternative embodiment of the modified improved seal of Fig.

10; Fig. 12 a detailed side view of the modified improved seal of Fig. 11 provided in a valve with a cylindrical valve seat; and Fig. 13 a partial cross-sectional side view of an internal combustion engine including a rotary valve according to a modified embodiment of the present invention.

Referring to Figs. 1 to 5 there is illustrated a rotary

valve, generally designated 5, according to a first embodiment of the present invention comprising part of an internal combustion engine, generally designated 10. The engine 10 provides a cylinder 15 having a reciprocable piston 50.

The valve 5 comprises a valve housing (block) 110 having a valve seat 20. The valve seat 20 has an inlet port 80 and an outlet port 90. The valve 5 further provides a rotatable valve member 60 mounted within the valve seat 20 at a compression end of one of the cylinders 15 having an orifice/combustion chamber 70 extending therethrough between the valve seat 20 and an interior of the cylinder 15.

There are further provided a plurality of seal members 25a, 25b, 25c at least between the valve member 60 and the inlet 80 and the outlet 90.

The seal member (s) 25a, 25b, 25c are biased towards a sealed position as will be described hereinafter. The seal member (s) 25a, 25b, 25c are substantially circular in planar cross-section.

The valve seat 20 comprises a substantially concave portion which is hemispherical in shape. The concave portion faces the cylinder 15, the valve member 60 being retained therebetween. The valve seat 20 is spaced from the valve member 60.

Each seal member 25a, 25b, 25c initially seals between the valve member 60 and the inlet port 70 or outlet port 80, whilst during a combustion cycle of the cylinder 15, in use,

combustion maintains sealing between the valve member 60 and the inlet port 70 and outlet port 80.

The valve member 60 is rotatable about a longitudinal axis of the cylinder 15.

The orifice 70 has a first opening adjacent the valve seat 20 and a second opening adjacent the cylinder 15.

As can best be seen from Fig. 2, rotation of the valve member 60 causes the first opening of the orifice 70 to sequentially register/align with the one inlet port 80 and the outlet port 90.

Referring particularly to Fig. 1, a major portion of the orifice 70 is offset relative to an axis of rotation of the valve member 60. Further a centre of the second opening of the orifice 70 is offset relative to the axis of rotation of the valve member 60. It will be appreciated that the orifice 70 comprises a chamber which constitutes a major. portion of a compression space at a moment of maximum compression within the cylinder 15, in use.

A first seal member 25a is provided between the valve member 60 and the inlet port 80, while a second seal member 25b is/are provided between the valve member 60 and the outlet port 90. Further, the valve seat 20 recessively provides a spark plug 100 between the inlet port 80 and outlet port 90.

A third seal member 25c is provided between the valve seat 20 and the valve member 60 and a shaft 36 extends from the valve member 60.

Each seal member 25a, 25b, 25c is carried by the valve seat 20. In this embodiment each seal member 25a, 25b, 25c comprises a primary seal member 180 which comprises a ring member carried in a retaining groove 190 formed in the valve seat 20. A sealing surface 30 of the primary seal member 180 is adapted to seal against an adjacent surface of the valve member 60. In this embodiment each seal member 25a, 25b, 25c further comprises a secondary seal member 210 which comprises an o-ring carried in a slot 200 formed in a side wall of the primary seal member 180. Each seal member 26a, 25b, 25c is biased towards the valve member 60, by respective resilient (spring) loading means such as a wavy spring 220.

The valve member 60 is partly hollow and provides a cavity 35 therein. The shaft 36 comprising a first hollow tubular body communicates with and extends from the cavity 35. A second hollow tubular body 37 is positioned within the first tubular body 36. Cooling fluid 120 may circulated through the cavity 35 via the second a first tubular bodies 36,37, as indicated by arrows B in Fig. 1.

The engine 10 further includes fuel injector 130a within a housing 130b and a spray cone 140, as are known in the art.

The valve member 60 is suitably located by means of bearings 150 and driven by means of valve drive 170 via bevel gear 160.

Operation of the valve 5 will now be described in

greater detail. The valve 5 hereinbefore described may comprise part of a four stroke spark ignition engine. It is apparent that the valve 5 is situated within the conventional combustion space but itself contains a combustion chamber 40 offset from the axis X of the valve 5, which in turn, rotates in line with the axis X of the piston 50. The valve 5 contains the orifice 70 linking the combustion chamber 40 with the inlet port 80, sparking plug 100 and exhaust port 90 respectively during one rotation of the valve 5. The inlet port 80, exhaust port 90 and valve shaft 36 are selectively sealed from the combustion chamber 40 by floating seals 25a, 25b, 25c contained within the valve housing 110.

The valve 5 is carried in bearings (e. g. ball or taper roller) 150 designed and specified to withstand operational axial and radial loadings.

When the valve 5 is manufactured as described under Primary Seal 180/Valve 5 (or Valve Face)/Valve Bearing and Drive System Materials and Manufacturing Processes hereinafter described, the valve 5 can be carried in non lubricated bushes and thrust pads of the same materials and manufacturing processes.

The valve 5 is driven from a crankshaft at half crankshaft speed, and the valve 5 timing is set to give no valve overlap as it is not so necessary for high flow efficiencies (minimum idle speed) but with valve lead/lag.

These parameters can be changed according to design

requirements and engine type. The orbiting combustion chamber 40 induces a continuous swirl and charge stratification and a powerful squish is generated by the piston 50 crown (only a small proportion of which forms a base of the combustion chamber 40) and the valve base at top dead centre (TDC). This commences when the inlet port 80 opens to the combustion chamber 40 and continues after the inlet port 80 is closed during compression and combustion, at a rate increasing proportionally with the engine 10 rotation rate. This together with high volumetric efficiency (no obstruction from poppet valves), low surface to volume ratio of the combustion chamber 40 which helps maintain fuel charge vaporisation and the centrifuging of the charge towards the sparking plug 100, enables a full burn of lean mixtures in the order of 1: 23 at high compression ratios in the order of 13: 1. Combustion chamber 40 temperatures can be controlled and more air can be present than is consumed during the combustion process generating a cool exhaust and presenting the ability to maintain very low emissions across the entire engine speed range including low idle.

The following describes the operation of the four stroke cycle for the engine 10 incorporating the rotary valve 5 containing the offset combustion chamber 40 and rotating at half the crankshaft speed as previously detailed.

At the commencement of an Induction Stroke with the

piston 50 at TDC the inlet and exhaust ports 80,90 are closed and sealed against the valve member 60 by the floating seals 25a, 25b and therefore condition of zero valve overlap exists. As the piston 50 descends the valve member 50 rotates in a clockwise direction and the valve orifice 70 presents itself to the inlet port 80, the air is drawn in and as the valve orifice 70 approaches the point at which the inlet port 80 is fully open to the combustion chamber 40 the vaporise fuel is injected directly into the combustion chamber 40 without condensing on inlet tract walls. When the piston 50 reaches bottom dead centre (BDC) the inlet port 80 is still partially open (valve lag) and is fully closed during the initial part of an upward Compression Stroke of the piston 50. The inlet and exhaust ports 80,90 are fully sealed and closed (aided by the increasing pressure of the charge behind the floating primary seals 180). The valve orifice 70 now faces the sparking plug 100 which wouid typically fire slightly before, at or slightly after TDC and may incorporate a multi-spark facility. The piston 50 passes TDC and is driven down during a Power Stroke. As the piston 50 nears BDC the exhaust port 90 starts to open (valve lead) and the burnt gases start to move out through the opening exhaust port 90. As the piston 50 passes BDC and rises during an Exhaust Stroke the exhaust port 90 opens fully, commences its closure and is fully closed when the piston 50 reaches TDC, the inlet port 80 remaining fully closed (zero valve

overlap). During two rotations of the crankshaft and the single rotation of the valve 5 the charge and latterly the burnt gases, are continually swirled and centrifuged by virtue of the offset combustion chamber 40.

Referring briefly to Fig. 6 there is illustrated a rotary valve, generally designated 5', according to a second embodiment of the present invention. Like parts of the valve 5'are identified by the same integers as in the valve 5, but suffixed with"'".

Twin inlet ports 80'and single or twin exhaust ports 90', each with their associated floating seals 180'and housing 110'and two sparking plugs 100'can be incorporated, together with two equal and diametrically opposed combustion chambers 40'contained within the rotary valve 5', with a valve speed reduction to a quarter of crankshaft speed. This enables air to be induced separately from the air fuel mixture which together with phased firing of the plugs 100'and temperature control of the combustion chambers surfaces (enhanced by the twin combustion chambers 40'which in turn, enhance the valve 5' balance) gives further control in relation to minimising emission levels (especially residual nitrous oxides) and maximising combustion efficiency.

Referring again to the first embodiment of Figs. 1 to 5, by decreasing the angle described by the inlet and exhaust ports 80,90 from that necessary (for any given size of port opening) to achieve zero inlet/exhaust valve overlap

(low stable idle), a degree of valve overlap can be incorporated if desired. As valve overlap is introduced valve lead/lag is correspondingly decreased. By laterally changing the length of the valve orifice 70 the extent of valve lead/lag and the time for which the valve 5 is fully open can be varied. By these means and the shaping and entry angles of the inlet ports 80, the characteristics of the engine 10 can be optimised to meet preferred design criteria e. g. low emissions and low stable idle for passenger vehicles, high power outputs for racing engines.

The engine 10 described incorporates a valve drive 170 from the crankshaft via a pulley driving a tensioned belt driving a second pulley (having twice the number of teeth as the first pulley) and mounted on a shaft, the other end of which carries a bevel gear 160 meshing with and driving a second bevel gear 160 mounted on and driving, the valve shaft 36 and the valve 5 (at half crankshaft speed).

Alternative drives can be based on either non-lubricated or sealed for life systems e. g. tensioned multi belt and pulley or 90° belt drive or chain and sprocket or vertical shaft drive incorporating and driving, bevel, spur, intermeshed or worm gears.

The following particular points shall be noted:- a) Non contact valve seat 20/valve member 60 Provided by the floating seal 25a, 25b, 25c design minimising friction losses and obviating shape constraints by self lapping seal requirements. These

floating seal members 25a, 25b, 25c are designed to: a) be contained and seal against a vertical rotary valve 5 (incorporating a combustion chamber 40) contained inside a combustion area; and b) seal against charge compression/combustion gases penetrating from the areas surrounding the outer circumference of the seal via a gap between its inner circumference and its housing. b) Valve member 60 shape Whilst many shape configurations are viable, a hemisphere is the selected design option for the following reasons: -A constant depth single plane primary seal 180 can be used thus avoiding any tendency which a seal with a face curved in one direction and straight in the other (as necessitated by a conical or cylindrical form) would have to lift slightly leading to leakage and differential wear rates to both the seal face and the rubbed (valve) surface.

-Volume weight and cost reductions relating to both the valve 5 and housing 110.

-Optimisation of the combustion chamber 40 shape- maximum volume, minimum surface area and minimum non- optimised volume linking combustion chamber 40 with inlet and exhaust ports 80,90 and sparking plug (s) 100.

-A better balanced valve 5 with less inertia to

overcome and more efficient cooling tracts with the ability to optimise combustion chamber 40 surface temperatures according to the type of engine design and fuel characteristics. c) Non-lubricated valve member 60/seal members 25a, 25b 25c Each seal member 25a, 25b, 25c (inlet port 80, exhaust port 90 and valve shaft 36) comprises: -Primary Seal 180 The primary seal 180 comprises a single piece continuous ring seal formed to accurately mate with an outer rotating face of the hemispherical rotary valve member 60. It is contained within a circular groove 200 formed in the hemispherical valve housing 110.

The inner and outer diameters of the groove 200 are such as to retain the seal 180 within close tolerances dictated by: a) the parameters of the secondary seal 210; b) the necessity for combustion gases to penetrate between the outer seal face and the retaining groove 190 to maintain seal pressure; and c) avoid any tendency to"lock on"through expansion during thermal cycling.

The inner face of the seal 180 contains a circular slot 190 containing the secondary seal 210. The diameters of the primary seals 180 are dictated by the valve shaft 36, inlet and exhaust port 80,90 diameters respectively whilst the seal contact surface width is

relatively small thus minimising friction losses. In the event of a selected primary seal material being capable of beneficial use but incapable of being effectively manufactured to accommodate the secondary seal groove then a carrier can be made in a suitable material (e. g. aluminium alloy etc.) with a secondary seal groove and a groove in the base to carry the separate primary seal 180.

-Secondary Seal 210 The secondary seal 210 takes the form of an"0" ring seal contained within the aforementioned slot 190 provided in the inner face of the primary seal 180 and prevents the charge compression/combustion gases circumventing the primary seal 180 via the gap between the primary seal 180 inner face and its housing groove 200. The tolerances of the slot 190 and"0"ring seal 210 are dictated by established parameters for seals of this nature.

-Initiation Spring 220 Sealing of the seal members 25a, 25b, 25c is initiated by"wavy"springs 220 capable of withstanding the operating temperatures encountered within its housing 110 (e. g. manufactured from an appropriate grade of stainless steel) and seated in the base of the primary seal housing groove 200 the spring rate of which is sufficient to overcome the friction of the secondary seal 190 and initiate a seal prior to the

charge compression/combustion gases increasing and maintaining an operational seal.

-Primary Seal 180/Valve 5 (or Valve Face)/Valve Bearing and Drive Svstem Materials and Manufacturing Processes: The materials selected and developed together with the manufacturing processes provide Non-lubricated Seal Faces minimising fuel contamination with unvapourised lubricating oil, in turn minimising emissions whilst providing the longevity and reliability required in current engine manufacture. The preferred primary seal 180 and valve member 60 material is a silicon carbide/boron nitride matrix, carbon fibre reinforced.

A carbon fibre"green"near netshape preform is infiltrated with the ceramic matrix within a reaction chamber using a CVI (chemical vapour infiltration) process. This results in an economically viable part with a fine grain structure surface with any post production treatment restricted to diamond lapping and capable of withstanding high temperatures, thermal shock and mechanical stress on a long term basis without lubrication.

Other ceramic based formulations including cements have been used successfully albeit with reduced longevity e. g. silicon/boron/zirconium/carbon/chrome oxide/graphite/aluminium etc. using CVD (chemical vapour deposition), hot and cold isostatic pressing,

thermal spray forming and casting techniques which can be economically and structurally viable especially for different engine types, sizes and quantities and in parts of the World where material and manufacturing processes are restricted. It is also appreciated that current developments in engineering polymers and their associated reinforcements can already be used as base materials for some of the seals and their associated parts and that this situation is likely to improve relatively rapidly which in turn could give rise to cheaper manufacturing methods.

-Secondary Seal 200 Material: The preferred"0"ring material for the secondary seals 210 is fluoroelastomer/Perflouroelastomer (trade name e. g. Viton) which can withstand elevated temperatures, chemicals and solvents in arduous environments such as those found within the combustion processes of gasolene and diesel engines. Other polymer materials could be used albeit with reduced longevity or increased costs. d) Fuel Injection-Siting and Timing The fuel injector 130a is sited so as to minimise obstruction to the inlet port 80 whilst allowing a spray cone 140 to deliver the fuel directly through the unobstructed valve inlet port 80/orifice 70, directly into the combustion chamber 40 thus minimising fuel deposition on inlet tract walls. Fuel injection

timing and injection rates are optimised for the available injection window throughout the extended speed range being a characteristic of the rotary valve.

It will be appreciated that the embodiments of the present invention hereinbefore described are given by way of example only, and are not meant to limit the scope of the invention in any way.

Particularly it should be understood that the present invention is applicable to single and multi-cylinder, reciprocating piston, internal combustion engines of any capacity, e. g. of the following types: -Two and Four Stroke Spark Ignition engines ; -Two and Four Stroke Compression Ignition (Diesel) engines; -Two Stroke Uniflow Compression Ignition (Diesel) engines.

Further it should be appreciated that existing engine designs could be modified to incorporate a new detachable cylinder head containing a valve according to the present invention thus allowing retrofitting.

The present Applicant terms the valve according to the present invention a Rotary Orbital Combustion Valve (ROCV).

It is believed that embodiments of the ROCV will provide one or more of the following advantages:- a) Lower manufacturing costs: -fewer components and less weight; -no lubrication system required for the upper

engine (cylinder head). b) Extended longevity achieving current and anticipated life expectancy for automotive engines: -seal and valve design together with material section, development and manufacturing processes; -less oil contamination of crankcase oil system therefore extended oil renewal periods. c) Increased efficiency over previous valve designs in the following areas: -lower emissions; -lower fuel consumption with multi fuel capabilities ; -smoother torque curve; -higher power output across extended speed range; -higher power to weight ratio; -higher volumetric efficiency ; -higher compression ratios; -lower stable idle and higher maximum engine speed; -leaner mixtures and cooler exhaust.

Reference is now made to Fig. 7 which depicts an improved seal 182 in the arrangement of Fig. 4: like parts are identified with like numerals suffixed with the letter "a". Seal 182 is substantially"L"shaped in perpendicular cross-section. This provides an erosion resisting surface to face A. Face A of the seal 182 effectively replaces the lower section of the internal diameter of the primary seal

housing 200a and thus provides an erosion resistant surface.

Sealing surface 30a includes a recess 35a which equilibriates pressure across the contact surface between sealing surface 30a and valve member 60, and that produced by surfaces 31a.

. Reference is now made to Fig. 8 which depicts a modification to the improved seal 182. The modified seal 184 is shown with like parts identified with like numerals suffixed with the letter"b". The arrangement of 184 differs from 182 in that the secondary seal 210b is contained within a slot located on the valve housing 110b as opposed to the secondary seal 210a being contained within a slot located on the seal 182.

Figure 9 depicts the valve 5 and seal 182 positioned for a hemispherical valve seat.

Similar arrangements of seals, depicted as 186 and 188 in Figs. 10, 11 and 12 show the arrangement of the improved and modified seals 182,184 when used on a cylindrical valve seat.

Fig. 13 depicts a further improvement of a valve 5e within a uniflow 2 stroke diesel engine 10e : corresponding to Fig. 1 with like parts numbered with like numerals suffixed with the letter"e". The engine provides a cylinder 15e having a reciprocable piston 50e. The valve 5e comprises a valve seat 20e and a rotatable valve member 60e which is mounted within the valve seat 20e at the compression end of a cylinder 15. The rotatable valve

member 60e has two orifices 70e, the combustion chambers, positioned symmetrically about the valve seat 20e, and joined via a link bridge 75. The orifices 70e extend through the valve member 60e between the valve seat 20e and an interior of the cylinder 15e. A fuel injector 130e is located substantially centrally upon the valve seat 20e between the two orifices 70e. The outlet 140e of the injector 130e is an outwardly extending cone. To aid construction of engine 10e, seal carrier inserts 132 are used to hold the seals 184 in place.

The location of the outlet of the fuel injector 140e is positioned with the link bride 75 to ensure: -the fuel is injected at the point of maximum compression at the centre bridge of the rotating combustion chambers which in turn -avoids the local concentration and uneven distribution of the fuel droplets encountered in conventional engines despite current ongoing development.

-the continuous rotation blends the fuel and air throughout the entire combustion period therefore ensuring virtually complete oxidisation-combustion of the fuel.

-the continuous low pressure fuel delivery and return of the excess a) cools the valve body and the injector/pump unit and b) preheats the fuel prior to injection.

The main benefits provided by an engine 10b including the fuel injector 130e arranged to release fuel in the link bridge 75 are realised as: -the even and continuous fuel/air distribution throughout the whole combustion period leads to substantial thermal/fuel efficiency gains in turn substantially reducing or even eliminating -the delay period which is effectively the need for injection to commence in advance of TDC (Top Dead Centre) necessitated by the above mentioned local concentration and uneven fuel droplet distribution in conventional engines in turn -reducing substantially the rapid pressure rise which causes"diesel knock"and the need for strong heavy engine design.

-the ROCV Uniflow 2 Stroke is therefore a quieter, lighter and cheaper engine the afterburn period (which takes place in minimum compression conditions and gives rise to much of the diesel emissions i. e. CO, HC-carbon and soot) is also virtually eliminated with consequent emission reduction -the need for expensive ECU systems is therefore reduced and the ability to revert to simple and cheap combined pump/injector units will reduce costs further.

The valve 5e having injector 130e is particularly advantageous for use in two-stroke uniflow engines, e. g. diesel type, but may also be used on four-stroke engines, e. g. petrol and diesel type The embodiments of the present invention hereinbefore described are given by way of example only and are not meant to limit the scope of the invention in any way.