WO2020121266A1

WO2020121266A1 - A rotary valve system for an engine

Info

Publication number: WO2020121266A1
Application number: PCT/IB2019/060753
Authority: WO
Inventors: Gideon Johannes OOSTHUYSE
Original assignee: Oosthuyse Gideon Johannes
Priority date: 2018-12-14
Filing date: 2019-12-13
Publication date: 2020-06-18

Abstract

This invention concerns a rotary valve system (10, 210) for an internal combustion engine. The rotary valve system (10, 210) comprises a rotary valve element (14, 214) carrying at least one cavity (16, 216.1, 216.2). The valve element (14, 214) is rotatable between a first, inlet position, wherein the cavity (16, 216.1, 216.2) creates a fluid flow path between an inlet port and combustion chamber of the engine, and a second position, wherein the cavity (16, 216.1, 216.2) creates a fluid flow path between the combustion chamber and an exhaust port of the engine. A sealing arrangement, which has a primary seal (18) and a secondary seal (20), is carried along the periphery of an inner rim of an opening in the cylinder head of the engine. The primary (18) and secondary (20) seals are configured to engage the outer surface of the valve element (14, 214).

Description

A ROTARY VALVE SYSTEM FOR AN ENGINE

BACKGROUND TO THE INVENTION

This invention relates to a rotary valve system for an engine. In particular, but not exclusively, the invention relates to a rotary valve and sealing arrangement for an internal combustion engine.

Internal combustion engines, in particular reciprocating internal combustion engines are well known. Such an engine comprises an engine block with a single cylinder or a plurality of cylinders arranged in either a single row, two rows or even three rows. A piston is located within a cylinder and seals one end of the cylinder while continuously sliding within the cylinder during operation. A cylinder head is attached to the engine block and serves to seal the cylinder(s) on the opposite side to the piston. A combustion chamber is formed between the piston and the cylinder head within the cylinder. The cylinder head typically includes at least one inlet port and at least one exhaust port for each cylinder. These ports are selectively opened and closed during operation by valves, in particular linear valves, which are biased into their closed positions by springs and opened by overhead cams driven by associated camshafts.

A disadvantage of the above engine configuration is that the valves restrict the flow into and out of the combustion chamber, predominantly due to the valve head shape. This, in turn, limits the breathability of the engine resulting in diminished performance. Similarly, the valve heads limit the performance due to their weight. At high revolutions, the return springs, which bias the valves into their closed positions, fail to keep up with the operation of the engine. This results in what is termed valve bounce which once again limits the performance of the engine.

Rotary valves for internal combustion engines are known and serve to replace the linear, spring actuated valves, in an attempt to mitigate the disadvantages mentioned above. Typically, the rotary valve is rotated by the camshaft. Grooves or cavities are located in the valve and as the valve rotates, the grooves or cavities align either the inlet port or the exhaust port with the combustion chamber, depending on the stroke of the piston.

In one known rotatory valve system a disc-like valve is used to regulate flow through each of the inlet and exhaust ports of the cylinder. The valves include fluid passages for creating a fluid path between the combustion chamber and the inlet and exhaust ports respectively when the passages aligns with the ports. A single annular seal is located about each of the inlet and exhaust ports and serve to seal the rotary valve against the ports.

In another known rotary valve system a single elongate cylinder is used to regulate flow through the inlet and exhaust ports. The cylindrical valve includes two cavities located along the periphery of the cylinder which are configured such that a single rotary valve may regulate flow into and out of the chamber through the inlet and exhaust ports respectively. In this known system, the cylindrical valve is rotated by way of a torque plate and a seal is created between the combustion chamber and the inlet and exhaust ports by means of a lubricating oil on the outer surface of the rotary valve. A disadvantage of the known rotary valves is that the seal or sealing arrangement created by the valve between the combustion chamber and the inlet or exhaust port respectively is neither ideal nor effective for the high pressures and temperatures experienced within the combustion chamber.

It is an object of this invention to alleviate at least some of the problems experienced with existing rotary valve systems, in particular a sealing arrangement for a rotary valve system, for internal combustion engines.

It is a further object of this invention to provide a rotary valve system, in particular a sealing arrangement for a rotary valve system, for an internal combustion engine that will be a useful alternative to existing systems.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the invention there is provided a rotary valve system for an internal combustion engine having an engine block with at least one cylinder, a piston carried in the cylinder, a cylinder head located at an end of the cylinder opposite to the piston, a combustion chamber defined in the cylinder between the piston and the cylinder head and an inlet port and an exhaust port in flow communication with the combustion chamber via an opening located in the cylinder head, the rotary valve system including:

a rotary valve element carrying at least one cavity, wherein the valve element is rotatable between a first, inlet position, wherein the cavity creates a fluid flow path between the inlet port and the combustion chamber via the opening in the cylinder head, and a second position, wherein the cavity creates a fluid flow path between the combustion chamber and the exhaust port via the opening in the cylinder head; a sealing arrangement including a primary seal and a secondary seal, wherein the sealing arrangement is carried along the periphery of an inner rim of the opening in the cylinder head;

wherein the primary and secondary seals are configured to engage the outer surface of the valve element.

The rotary valve element may carry a number of cavities such that one revolution of the rotary valve element corresponds to more than one completed cycle of a four-stroke internal combustion engine.

The rotary valve element may carry two cavities which are located diametrically opposite one another on the rotary valve element such that one revolution of the rotary valve element corresponds to two completed cycles of the four-stroke internal combustion engine.

The primary and secondary seals may be in the form of spaced apart sealing rings.

The secondary sealing ring is preferably located operatively above the primary sealing ring.

The sealing rings may, in use, be embedded in complementary shaped grooves located in the cylinder head.

Each of the primary and secondary sealing rings may have an internal edge, which is its radially inner edge abutting the valve element in use, wherein the internal edges may be shaped complementary to the shape of the valve element.

The internal edges may be chamfered such that the chamfer is shaped to conform substantially to the outer surface of the valve element.

The primary seal and/or the secondary seal may include a discontinuity to allow for expansion and contraction of the seal. The discontinuity in the primary seal and/or the secondary seal may be in the form of a break that has a zig-zag or Z-shaped profile.

The discontinuity of the secondary seal may be located approximately diametrically opposite the break of the primary seal.

The rotary valve element may be substantially spherical.

The at least one cavity may be in the form of a semi-circular channel extending across the outer surface of the valve element.

The rotary valve assembly may include more than one, for example at least two, rotary valve elements such that a first valve element corresponds to the inlet port and a second valve element corresponds to the exhaust port.

In accordance with another aspect of the invention there is provided an internal combustion engine including a rotary valve assembly according to the first aspect of the invention.

In accordance with yet another aspect of the invention there is provided a rotary valve system for controlling the flow of a medium, such as fluid for example, through a port or opening, the system including:

a rotary valve element carrying at least one cavity, wherein the valve element is rotatable between a first, inlet position, wherein the cavity creates a fluid flow path through the port, and a second position, wherein the valve element obstructs, or completely closes, the fluid flow path through the port;

a sealing arrangement including a primary seal and a secondary seal, wherein the sealing arrangement is carried along the periphery of an inner rim of the port;

wherein the primary and secondary seals are configured to engage the outer surface of the valve element. In accordance with yet another aspect of the invention there is provided a method of controlling the flow of a medium, such as fluid for example, through a port or opening, the method including:

moving a rotary valve element carrying at least one cavity between a first, inlet position, wherein the cavity creates a fluid flow path through the port, and a second position, wherein the valve element obstructs, or completely closes, the fluid flow path through the port;

sealing an interface between the rotary valve element and the port using a sealing arrangement including a primary seal and a secondary seal, wherein the sealing arrangement is carried along the periphery of an inner rim of the port and wherein the primary and secondary seals are configured to engage the outer surface of the valve element.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a simplified perspective view of a rotary valve system for an engine in accordance with the invention;

Figure 2 shows a perspective view of the valve element of the rotary valve system of Figure 1 ;

Figure 3 shows a schematic illustration of the rotary valve system of the invention in cross-section in which piston is undergoing its intake stroke and the rotary valve element allows flow between the inlet port and the combustion chamber;

Figure 4 shows a schematic illustration of the rotary valve system of the invention in cross-section in which the piston is undergoing its compression stroke and the rotary valve element is fully sealed;

Figure 5 shows a schematic illustration of the rotary valve system of the invention in cross-section in which the piston is undergoing its expansion stroke and the rotary valve element is fully sealed;

Figure 6 shows a schematic illustration of the rotary valve system of the invention in which the piston is undergoing its exhaust stroke wherein the rotary valve element allows flow between the combustion chamber and the exhaust port of the cylinder.

Figure 7 shows an enlarged cross-sectional plan view of the primary seal of the sealing arrangement of the rotary valve system of the invention;

Figure 8 shows an enlarged perspective view of the rotary valve system of the invention in which the primary and secondary seals are visible as the valve element cavity provides a flow path between the inlet port and the combustion chamber;

Figure 9 shows an enlarged cross-sectional view of the primary seal and secondary seal interacting with the valve element;

Figure 10 shows a schematic illustration of a rotary valve system of the invention in accordance with a second embodiment wherein a complete revolution of the rotary valve is illustrated in (a) to (h) in which two complete intake, compression, expansion and exhaust cycles are completed; Figure 11 shows a cross-sectional front view of a four-stroke internal combustion engine including the rotary valve assembly of the present invention; and

Figure 12 shows a cross-sectional side view of a four-stroke internal combustion engine including the rotary valve assembly of the present invention.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted," "connected," "supported," and "coupled" and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings and are thus intended to include direct connections between two members without any other members interposed therebetween and indirect connections between members in which one or more other members are interposed therebetween. Further, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings. Additionally, the words "lower", "upper", "upward", "down" and "downward" designate directions in the drawings to which reference is made. The terminology includes the words specifically mentioned above, derivatives thereof, and words or similar import. It is noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the," and any singular use of any word, include plural referents unless expressly and unequivocally limited to one referent. As used herein, the term“include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.

Referring to the drawings, in which like numerals indicate like features, a non-limiting example of a rotary valve system for an engine in accordance with the invention is generally indicated by reference numeral 10.

The rotary valve system 10 is configured for a typical internal combustion engine, in particular but not limited to a four-stroke internal combustion engine. The engine includes an engine or cylinder block with at least one cylinder 100. A piston 102 is carried within the cylinder 100 and serves to seal one end of the cylinder 100. A cylinder head 104 is located at an end of the cylinder 100 opposite to the piston 102. A combustion chamber 106 is defined in the cylinder 100 between the piston 102 and the cylinder head 104. An inlet port 108 and exhaust port 1 10 are in flow communication with the combustion chamber 106 via an opening 12 located in the cylinder head 104.

The rotary valve system 10 includes a rotary valve element 14. The rotary valve element 14 is rotatably carried within a housing 1 12 by a cam shaft 1 14 of the engine. In the preferred embodiment, the valve element 14 is spherical (best seen in Figure 2). The opening 12 is specifically configured for the spherical shape of the valve element 14 to be received or seat therein i.e. the periphery or rim of the opening 12 is similarly angled to that of the outer surface of the spherical valve element 14. The valve element 14 includes a cavity 16 located on the periphery of the valve element 14. In use, the valve element 14 is rotatable between a first position, wherein the cavity 16 provides a flow path between the inlet port 108 and combustion chamber 106, and a second position, wherein the cavity 16 provides a flow path between the combustion chamber 106 and the exhaust port 1 10. In the preferred embodiment, the cavity 16 is in the form of a semi-circular groove, best seen in Figure 2. The cavity 16 extends in a straight line across the surface of the valve element 14 and has a semi-circular cross section. This configuration, in combination with the angles of the inlet and exhaust ports 108, 1 10 provides a direct, unobstructed flow path between the inlet 108 or outlet 1 10 and the combustion chamber 106 when the cavity 16 is aligned therewith. In the preferred embodiment, the valve element 14 includes a single cavity 16 which provides a flow path between the combustion chamber 106 and inlet and exhaust ports 108, 1 10 respectively, as the valve element 14 is rotated between its first and second positions.

A sealing arrangement is carried along the inner periphery of the opening 12. The sealing arrangement is configured to seal the outer surface of the valve element 14 against the inner periphery of the opening 12 thereby effectively sealing the combustion chamber 106. The sealing arrangement includes a primary seal 18 and a secondary seal 20. The secondary seal 20 is carried, in use, above and parallel to the primary seal 18. The sealing rings 18, 20 are therefore spaced apart from each other such that one is carried vertically above the other (with reference to the orientation shown in the drawings). Both seals 18, 20 are carried one above the other along the inner periphery of the opening 12 effectively extending along a major portion of, preferably the entire periphery of the opening 12. The seals 18, 20 are preferably in the form of annular sealing rings. Each seal 18, 20 is embedded in the cylinder head 104 and, in particular, is embedded in complementary shaped grooves located in the cylinder head. As can be seen in Figure 7, the primary seal 18 has a zig-zag or Z-shaped break to form a discontinuity 25 in the seal. This allows for expansion and/or contraction to occur when the engine is in operation. The same applies to the secondary seal 20. The Z-shaped break 25 in the secondary seal is preferably located about 180° from the Z-shaped break in the primary seal 18. In other words, the seals 18, 20 are arranged such that their discontinuities 25 are located substantially diametrically opposite each other in use. This arrangement provides that the breaks located in the seals 18, 20 do not substantially affect the functioning of the sealing arrangement. It should be understood that the two seals 18, 20 are in continuous sealing contact with the outer surface of the valve element 14 during operation. Referring to Figure 9, the inner edges 22, 24 of the seals 18, 20 which come into contact with the outer surface of the valve element 14 are chamfered to form surfaces or edges 22, 24 which substantially conform to the outer edge of the valve element 14. The chamfered seal edges 22, 24 not only provides superior sealing capabilities but also act to prevent damage to the valve element 14 and to be more resistant to high temperatures.

The functioning of the rotary valve system 10 will now be described in more detail with specific reference to Figures 3 to 6. It must first be understood that the rotary valve system 10 replaces the linear, spring actuated valve systems used in typical four-stroke cycle internal combustion engines, the operations of which is well-known.

The intake stroke of the piston 102 is illustrated in Figure 3. At the first stage, the valve element 14 is positioned such that the cavity 16 provides a direct flow path between the combustion chamber 106 and the inlet port 108 via the opening 12. In this stroke an air-fuel mixture is introduced via the inlet port 108 into the combustion chamber 106. This process occurs when the piston 102 moves from top dead centre (shown in the first diagram, wherein the piston 102 is at the topmost position) to bottom dead centre (shown in the second diagram, wherein the piston 102 is at the bottommost position). As the piston 102 moves down toward bottom dead centre, the air-fuel mixture is drawn into the combustion chamber 106 through the direct, unobstructed flow path created by the cavity 16 in the valve element 14. During this stroke the exhaust port 1 10 is fully sealed off by the valve element 14. The valve element 14 rotates as the piston 102 moves downward and once the piston 102 reaches bottom dead centre the valve element 14 almost seals off the inlet 108 completely. The inlet port 108 remains slightly open just past bottom dead centre and once it seals completely, the compression process or compression stroke starts. The compression stroke is illustrated in Figure 4. In this stroke, the air-fuel mixture is compressed within the combustion chamber 106 between the upward moving piston 102 and the cylinder head 104. In this stroke the valve element 14 seals the opening 12 in the cylinder head 104 completely in order for the air-fuel mixture to be charged for ignition. The sealing arrangement in the form of the primary seal 18 and secondary seal 20, seals off the combustion chamber 106 and prevents any escape of the air- fuel mixture through the inlet port 108 and exhaust port 1 10, even under the high pressure. Just before the piston 102 reaches top dead centre the compressed air-fuel mixture is ignited. Ignition is initiated by either a spark plug (not shown) found in petrol engines or by compression combustion in diesel engines. During the combustion stroke the valve element 14 rotates and the cavity 16 is located away from the opening 12.

The power stroke is illustrated in Figure 5. The power stroke starts with the ignition of the air-fuel mixture and the piston 102 is forced downward to apply torque to the crankshaft (not shown). During this stroke the valve element 14 seals the opening 12 completely. Once again, the sealing arrangement 18, 20 serves to prevent any release of combustion gases through the inlet port 108 or exhaust port 1 10. This, in turn, prevents any loss in performance of the engine. The power stroke ends when the piston 102 reaches bottom dead centre and the exhaust stroke commences. It is important to note that during this stroke, the seals 18, 20 experience a large explosive force as well as a high temperature from within the combustion chamber 106. During this stroke the seals 18, 20 are required to withstand high temperatures and it is envisaged that they may be similar in material to the seals found on the outer edge of the piston 102.

The exhaust stroke is illustrated in Figure 6. During the exhaust stroke, gases are expelled from the combustion chamber 106 through the exhaust port 1 10. During this stroke the valve element 14 is positioned such that the cavity 16 creates direct, unobstructed flow path from the combustion chamber 106 to the exhaust port via the opening 12. At the same time the inlet port 108 remains sealed. During the exhaust stroke, the piston 102 moves from bottom dead centre to top dead centre. At top dead centre the valve element 14 is positioned such that the cavity 16 provides a partial flow path between both the inlet port 108 and the exhaust port 1 10 with the combustion chamber 106. Once the piston 102 passes top dead centre, the entire four-stroke cycle repeats, starting with the intake stroke.

It is envisaged that in an alternative embodiment of the invention not illustrated, the rotary valve system 10 may include at least two rotary valve elements identical to the rotary valve element 14 as described above. The first rotary valve element selectively seals the inlet port 108 via a first opening while the second rotary valve element selectively seals the exhaust port 1 10 via a second opening. The two valve elements are rotated by individual camshafts and each valve element only handles a single process, either inlet of the combustion chamber or exhaust of the combustion chamber. The operation of this embodiment is identical in all other aspects as to that of the illustrated embodiment.

It is envisaged that the rotary valve system 10 may be lubricated by a lubricating medium which is provided from an exterior of the housing 1 12 to the valve element 14 by way of a delivery port (not shown). It is also envisaged that the valve element 14 may be lubricated from the camshaft carrying a lubricating medium and providing the lubricating medium to the outer surface of the valve element 14. In this case the camshaft is configured as a hollow shaft and lubricating medium may be carried in the shaft to each valve element 14. It is also envisaged that the valve element 14 may be lubricated by the fuel passing through the combustion chamber 106. It is also envisaged that the rotary valve system 10 will require temperature control means (not shown) for controlling the temperature of the valve element 14 during use. The temperature control means may include a cooling medium such as cooling oil, which is pumped from a cooling system via a conduit located in the camshaft 1 14 to a channel located within the valve element 14. Referring now to Figure 10, a non-limiting example of a second embodiment of a rotary valve system for an engine in accordance with the invention is generally indicated by reference numeral 210. Again, like numerals indicate like features.

The rotary valve system 210 is substantially similar to the rotary valve system 10 in accordance with the first embodiment of the invention and, only the differences will be described herein. The rotary valve system 210 again has a rotary valve element 214 but, in contrast to the first embodiment, has a plurality of cavities. In particular, the rotary valve element 214 of the second embodiment has two cavities 216.1 and 216.2. The cavities 216.1 , 216.2 are substantially similar to the cavity 16. In this second embodiment the cavities 216.1 and 216.2 are located diametrically opposite each other on the rotary valve element 214. The valve element 214 is rotatable between different positions, wherein each of the cavities 216.1 , 216.2 provides a flow path between the inlet port 108 and combustion chamber 106, and between the combustion chamber 106 and the exhaust port 1 10, respectively. The different positions of the rotary valve element 214, and accordingly the cavities 216.1 and 216.2, are indicated in Figure 10. The shading in Figure 10 is used to indicate the four quadrants of the rotary valve element 214 corresponding to the different strokes of a four-stroke internal combustion engine. The shading is therefore not physical features of the rotary valve element 214 but simply used for illustrative purposes for the sake of clarity.

Figure 10(a) illustrates a first inlet period of the rotary valve element 214 that corresponds with the intake stroke of the piston 102. In this inlet period the valve element 214 is positioned such that the cavity 216.1 provides a direct flow path between the combustion chamber 106 and the inlet port 108 via the opening 212. In this stroke an air-fuel mixture is introduced via the inlet port 108 into the combustion chamber 106. Figure 10(b) illustrates a first compression period of the rotary valve element 214 that corresponds with the compression stroke of the piston 102. In this stroke, the air-fuel mixture is compressed within the combustion chamber 106 between the upward moving piston 102 and the cylinder head 104. In this stroke the valve element 214 seals the opening 212 in the cylinder head 104 completely in order for the air-fuel mixture to be charged for ignition. Just before the piston 102 reaches top dead centre the compressed air-fuel mixture is ignited. Figure 10(c) illustrates a first combustion period of the rotary valve element 214 that correspond with the combustion and power stroke of the engine. During this combustion and power stroke the valve element 214 seals the opening 212 completely. The valve element 214 rotates and the cavity 216.1 is rotated away from the opening 212 while the cavity 216.2 is rotated towards the opening 212. Figure 10(d) illustrates a first exhaust period of the rotary valve element 214 that corresponds to the exhaust stroke of the engine. During the exhaust stroke, the cavity 216.2 aligns with the opening 212 to create a fluid flow path from the combustion chamber 106 to the exhaust port 1 10.

It should be clear from the above description that Figure 10(a) to (d) illustrate a full four-stroke cycle of the engine while the rotary valve element 214 has only completed half a revolution. Figure 10(e) to (h) illustrates the same four-stroke cycle described above with reference to Figure 10(a) to (d) but with the rotary valve element 214 rotating through the second half of the revolution. For the sake of clarity, one complete revolution of the rotary valve 214 is illustrated in Figure 10(a) to (h). Figures 10(e) to (h), and accordingly the second part of the revolution of the rotary valve 214, are identical to Figures 10(a) to (d), and accordingly the first part of the revolution of the rotary valve 214, apart from the reversed positioning of the cavities 216.1 and 216.2. Accordingly, Figures 10(e) to (h) illustrate a second inlet period, a second compression period, a second combustion and power period and a second exhaust period respectively.

A significant advantage of the rotary valve assembly 210 of the second embodiment is that a 4:1 ratio between the crankshaft driving the piston and the‘camshaft’ is achieved. The rotary valve assembly 210 therefore allows the rotary valve element 214 to rotate at half of the speed of a typical camshaft in the well-known 2:1 ratio in a typical crankshaft and camshaft combination. This reduced speed of rotation of the rotary valve element 214 results in less friction being generated at the same revolutions per minute (RPM) compared to an engine comprising known valves run by a camshaft. Another advantage is that less heat is being generated due to the slower rotational speed of the rotary valve element 214. It is furthermore envisaged that the rotary valve element 214 will result in superior rotational valve balance. The abovementioned advantages ultimately result in a longer life span of the rotary valve assembly 210 compared to known valve assemblies.

It should be appreciated that the‘camshaft’ of the engine incorporating the rotary valve system 10, 210 of the present invention is essentially the shaft driving the rotatable valve element 214. A simple application of the rotary valve assembly 210 of the invention is illustrated in Figures 1 1 and 12. Figures 1 1 and 12 show a section of an internal combustion engine including the rotary valve assembly 214 of the invention. The rotary valve element 214 is driven by a shaft 226, which is in turn driven by a gear 228. Best seen in Figure 12 the rotary valve element 214 is carried by the shaft 226 and rotates in harmony with the shaft 226. It should be understood that the shaft 226 replaces the camshaft found in an engine comprising a typical linear valve assembly. The crankshaft is indicated by reference numeral 1 12 in Figure 12 and drives the piston 102 by means of a connecting rod 1 14. The crankshaft 1 12 is in turn driven by a crankshaft gear 1 16.

As shown in Figure 12 the rotary valve assembly 210 includes the same sealing arrangement as the rotary valve assembly 10 in accordance with the first embodiment of the invention, and it will accordingly not be described again.

Although the rotary valve system 210 is described to include two cavities 216.1 , 216.2 it is envisaged that alternative embodiment could include more than two cavities. The rotational speed of the rotary valve element 214 can be adjusted accordingly to accommodate more than two cavities. It will be appreciated that the rotary valve system 10, 210 provides an effective and efficient alternative to the presently employed linear, spring actuated valve systems in internal combustion engines. The rotary valve system 10, 210 provides direct, unobstructed flow paths between the inlet 108 and the combustion chamber 106 during the intake stroke, and between the exhaust outlet 1 10 and the combustion chamber 106 during the exhaust stroke. The rotary valve system 10, 210 provides a rotating valve element 14 which performs consistently at high revolutions and chance of valve bounce is completely negated. The rotary valve system 210 furthermore has the advantage of operating at reduced speeds

Although the rotary valve system 10, 210 is described for use with an internal combustion engine only it is envisaged that it could be used in other applications to control the flow of fluid, or other medium, through one of more port or opening. The invention is therefore not limited for use in an internal combustion engine only. The invention also concerns a method of controlling the flow of a medium, such as fluid for example, through a port or opening. The method should be clear from the above description but for the sake of clarity will be described briefly. The method includes moving a rotary valve element 14, 214 carrying at least one cavity 16, 216.1 , 216.2 between a first, inlet position, wherein the cavity creates a fluid flow path through the port, and a second position, wherein the valve element 14, 214 obstructs, or completely closes, the fluid flow path through the port. The method further includes sealing an interface between the rotary valve element 10, 210 and the port using a sealing arrangement including a primary seal 18 and a secondary seal 20. As described above, the sealing arrangement is carried along the periphery of an inner rim of the port and the primary 18 and secondary 20 seals are configured to engage the outer surface of the valve element 14, 214.

It will be appreciated that the above description only described some embodiments of the invention and that there may be many variations without departing from the spirit and/or the scope of the invention. It is easily understood from the present application that the particular features of the present invention, as generally described and illustrated in the figures, can be arranged and designed according to a wide variety of different configurations. In this way, the description of the present invention and the related figures are not provided to limit the scope of the invention but simply represent selected embodiments.

The skilled person will understand that the technical characteristics of a given embodiment can in fact be combined with characteristics of another embodiment, unless otherwise expressed or it is evident that these characteristics are incompatible. Also, the technical characteristics described in a given embodiment can be isolated from the other characteristics of this embodiment unless otherwise expressed.

Claims

1 . A rotary valve system for an internal combustion engine having an engine block with at least one cylinder, a piston carried in the cylinder, a cylinder head located at an end of the cylinder opposite to the piston, a combustion chamber defined in the cylinder between the piston and the cylinder head and an inlet port and an exhaust port in flow communication with the combustion chamber via an opening located in the cylinder head, the rotary valve system including:

a rotary valve element carrying at least one cavity, wherein the valve element is rotatable between a first, inlet position, wherein the cavity creates a fluid flow path between the inlet port and the combustion chamber via the opening in the cylinder head, and a second position, wherein the cavity creates a fluid flow path between the combustion chamber and the exhaust port via the opening in the cylinder head;

a sealing arrangement including a primary seal and a secondary seal, wherein the sealing arrangement is carried along the periphery of an inner rim of the opening in the cylinder head;

2. A rotary valve system according to claim 1 , wherein the rotary valve element carries a number of cavities such that one revolution of the rotary valve element corresponds to more than one completed cycle of a four-stroke internal combustion engine.

3. A rotary valve system according to claim 2, wherein the rotary valve element carries two cavities which are located diametrically opposite one another on the rotary valve element such that one revolution of the rotary valve element corresponds to two completed cycles of the four-stroke internal combustion engine.

4. A rotary valve system according to any one of claims 1 to 3, wherein the primary and secondary seals are spaced apart sealing rings.

5. A rotary valve system according to claim 4, wherein the secondary sealing ring is located operatively above the primary sealing ring.

6. A rotary valve system according to either claim 4 or 5, wherein the sealing rings are, in use, embedded in complementary shaped grooves located in the cylinder head.

7. A rotary valve system according to any one of claims 4 to 6, wherein each of the primary and secondary sealing rings has an internal edge, which is its radially inner edge abutting the valve element in use, and wherein the internal edges are shaped complementary to the shape of the valve element.

8. A rotary valve system according to claim 7, wherein the internal edges are chamfered such that the chamfer is shaped to conform substantially to the outer surface of the valve element.

9. A rotary valve system according to any one of claims 1 to 8, wherein the primary seal and/or the secondary seal include(s) a discontinuity to allow for expansion and contraction of the seal.

10. A rotary valve system according to claim 9, wherein the discontinuity in the primary seal and/or the secondary seal is/are in the form of a break that has a zig-zag or Z-shaped profile.

1 1. A rotary valve system according to either claim 9 or 10, wherein the discontinuity of the secondary seal is located approximately diametrically opposite the break of the primary seal.

12. A rotary valve system according to any one of claims 1 to 1 1 , wherein the rotary valve element is substantially spherical.

13. A rotary valve system according to any one of claims 1 to 12, wherein the at least one cavity is in the form of a semi-circular channel extending across the outer surface of the valve element.

14. A rotary valve system according to any one of claims 1 to 13, including at least two rotary valve elements such that a first valve element corresponds to the inlet port and a second valve element corresponds to the exhaust port.

15. An internal combustion engine including a rotary valve assembly according to any one of claims 1 to 14.