Rotary Internal Combustion Engine

This invention relates to a rotary internal combustion engine and is primarily concerned with an engine operating on the conventional four-stroke cycle and using sliding abutments moving within chambers in which the operating cycles of the engine are performed.

One of the major problems normally associated with rotary engine design is that, unlike a reciprocating piston engine, a rotor will only provide one direction of motion. Although it is relatively simple to design a sliding abutment type 'true' rotary engine that will perform the induction and compression strokes in one direction of motion, the gases (once compressed) will, as a consequence of the unidirectional operation, always be located against the wrong side of the sliding abutments prior to ignition; i.e. if the gases were to ignite upon compression, the rotor would need to reverse its direction of motion, which defeats the object of the rotary design. In order to overcome this problem, many rotary engine designers have included gas by-pass systems within their designs to enable the compressed gases to transfer to the opposite side of a sliding abutment prior

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to (or during) ignition. Although in theory this would work, it necessitates that, at some stage, the sliding abutments will need to break contact with the rotor surfaces to enable completion of the internal combustion cycle. unfortunately, any rotary engine design that requires the sliding abutments to continually make-and- break contact with the rotor surfaces would be impracticable. This is because make-and-break type designs cause gas seal separation problems, create abutment to rotor alignment problems and necessitate the inclusion of independent sliding abutment activation mechanisms which complicate the design. It is therefore essential that, for a rotary engine design to be practical, any sliding abutments used within the design must remain in continuous contact with all rotor surfaces at all times; all sliding abutment ends must continually bear against all chambered, unchambered and transition surfaces. Because of this essential design requirement, it is not practical to include a gas by-pass system within the design of a rotary engine and consequently, it is not possible to produce a reliable stroke generating cycle with unidirectional motion.

In an attempt to overcome the problem of the non¬ availability of two directions of motion within a rotary design, certain known oscillatory rotary engine designs

have been developed. Although these provide a stroke generating cycle, they have deviated so much from the true rotary concept that they are in fact no more efficient (and usually less reliable) than a conventional piston engine. This invention seeks to avoid such drawbacks and to provide bidirectional operation for true rotary motion to be maintained and eliminates problems created by unidirectional operation..

According to this invention there is provided a rotary internal combustion engine comprising an annular stator and a pair of annular rotors positioned on each side of the stator and in co-planar operative relationship therewith, the rotors being rotatable about a common central axis at right-angles to the planes of the stator and in mutually opposite directions; each rotor having, on that surface facing the stator, a chamber including a plurality of fixed sections with stepped level transitions between each adjacent fixed section being joined by a transversely sliding section movable between a first position level with one abutting fixed section and a second position level with the other adjacent abutting fixed section; the stator including sliding abutments corresponding in number to the sliding sections with the abutments sealingly engaging the chambers of a respective rotor; the abutments being

passed from one section of a fixed chamber to another by transverse movement of a said sliding section; communicating passageways for transfer of fluidic medium to or from a chamber in one rotor to a chamber in the other rotor or to and from externally communicating ports and forming or including valve means operating in synchronism with the rotation of the rotors being provided adjacent the abutments whereby a combustible fluid medium may enter a chamber of one rotor, be compressed therein, ignited and expanded by transfer through the communicating passageway to a chamber in the other rotor to drive same, the exhaust gases being discharged through a passageway forming or including a valve means adjacent to another sliding abutment.

In this invention the chambers of respective rotors co-operate such that compressed combustible charge is transferred across the stator to the contra-rotating rotor via the communicating passageways, thus avoiding reciprocating motion. After ignition the rotor is driven by the expanding gases until the next sliding abutment in sequence where, on reaching the stepped transition the abutment and sliding section move to open an exhaust passageway, the stepped transition at the end of the chamber then causing exhaust gases to be discharged.

This invention is described and illustrated with

reference to the drawings showing an embodiment in simplified form, to enable the invention to be more clearly understood, and more detailed constructional embodiments all being illustrative of the invention and by way of example. The drawings also illustrate preferred features of the construction. In the drawings: -

Figure 1 shows a schematic simplified view of an embodiment mainly illustrating the basic principle of this invention, Figure 2 shows a broken-away perspective view of one practical construction according to this invention, Figures 3a to 3h show diagrammatically stages in the working cycle, Figure 4 shows a cross section of the embodiment shown in Figure 2, Figure 5 shows an alternative construction for the configuration of the rotors, and Figure 6 shows another alternative construction for the configuration of the rotors. The invention is explained further by reference to Figure 1 of the drawings showing a partly exploded view of the rotors and stator in simplified form.

As shown the rotary internal combustion engine has

an annular stator S and two annular rotors Rl and R2 positioned on each side of stator S and co-planar therewith. The rotors are rotatable about an axis perpendicular to the planes of the rotors and stator and defined by shaft SH. The rotors turn in mutually opposite directions of rotation indicated by arrows X and Y. Each rotor includes a plurality of chambers CHI and Ch2 being even in number with stepped transitions TR between adjacent chambers CHI and CH2. The transitions TR are defined by transversely sliding sections TF which may move from a position level with chamber CHI to a position level with chamber CH2 (an intermediate position is shown) . The stator S has a raised housing surface HS which sealingly engages the chamber CHI but which provides a free chamber space within the chamber CH2. The stator includes sliding abutments AB which, during rotation, may slide in contact with the surface of chamber CH2 to then travel onto the surface of the transition TF, this being co-extensive therewith. The transition section TF then moves, by means not shown here, to be co-extensive with the surface of chamber CHI to allow the abutment AB to smoothly run onto the surface of this chamber. It will be understood that the movement of the transition must be synchronised with the rotational rate to achieve this.

The abutments thus define a moving wall in the chamber CH2 which is otherwise closed-off by the transition edge TFE. A similar relationship is provided in the other rotor Rl but here when a given abutment travels in a chamber CH2 in rotor R2 the opposed abutment travels in chamber CHI of the other rotor Rl. By the provision of transfer passageways adjacent to alternate abutments AB a charge may be compressed and then transferred to the opposed chamber in the other rotor and ignited to drive the other rotor. Passageways adjacent to other abutments provide for the induction of the charge and for exhaust.

This invention is now more fully described with reference to Figures 2 to 6 of the drawings.

In these drawings reference numerals identify component parts referred to in the following and as set out in the following key: -

List of Components

1. Top rotor.

2. Bottom rotor.

3. Main housing.

4. Inner housing.

5. Compression/power sliding abutment.

6. Induction/exhaust sliding abutment.

7. Leading transition section.

8. Trailing transition section.

9. Chambered rotor surface.

10. Unchambered rotor surface.

11. Rotor retaining ring.

12. Peripheral rotor bearing.

13. Main rotor bearing.

14. Rotor shim.

15. Peripheral oil seal.

16. Inner oil seal.

17. Auxiliary shaft oil seal.

18. Drive shaft oil seal.

19. Auxiliary shaft.

20. Drive shaft.

21. Auxiliary shaft bearing.

22. Drive shaft gear wheel.

23. Auxiliary shaft bearing.

24. Drive shaft bearing.

25. Transition gear drive ring.

26. Transition gear drive ring oil seal.

27. Rotor spoke.

28. Transition section cover.

29. Transition section cam.

30. Transition section gear wheel.

31. Transition section gear spindle.

32. Transition section spring.

33. Transition section auto-adjust.

34. Alignment guide.

35. Alignment guide channel.

38. Auxiliary to drive shaft mesh gear.

39. Auxiliary to drive shaft mesh gear spindle.

40. Auxiliary shaft gear.

41. Drive shaft gear. 42. Rotor to auxiliary shaft gear. 43. Rotor to drive shaft gear. 44. Rotor to Auxiliary shaft gear drive ring. 45. Rotor to drive shaft gear drive ring. 46. Rotor to auxiliary shaft gear spindle. 47. Rotor to drive shaft gear spindle. 48. Top cover. 49. Bottom cover and transmission mounting. 50. Transmission locating hole. 51. Circular sump 52. Interconnecting combustion chamber.

59. Spark plug. 60. Spark plug hole. 61. Inlet port. 62. Exhaust port. 63. Raised housing surface. 64. Raised housing gas seal. 65. Sliding abutment gas seal.

68. Spark plug lead hole. 69. Inner housing securing bolt. 70. Rotor retaining ring securing bolt. 71. Outer rotor interconnection. 72. Inner rotor interconnection. 73. Double sided central rotor.

Figures 3 (a) to 3 (h) show in eight stages the operation of the engine. In these drawings the following key is used to indicate the state of any one chamber.

INDUCTION COMPRESSION POWER EXHAUST

• ^■• . ^•• . ^• . ^• • ^••• ;" ^• " ^• .: ^• .?

A cross within the combustion chamber indicates ignition taking place.

The symbol φ-> shows the position of each rotor at the various stages and also shows its direction of rotation.

Radial movement of the leading transition sections (7) and the trailing transition sections (8) are indicated by the arrows.

The compression/power sliding abutments (5) and the inlet/exhaust sliding abutments (6) move in conjunction with the sliding transition sections (7) and (8) when in contact with them.

Although the cycle progression diagrams refer to the gas flow cycle within and between a pair of face-to-face equal diameter rotors, they are shown with an inner and

outer relationship for ease of description. This is because, with a plan view, one rotor would obscure the other. The diagrams are shown in this manner purely for gas flow description purposes. The correct rotor relationship can be seen by referring to Figures 2 and 4. This invention relates to a synchronised interactive bidirectional rotary engine. It is a sliding abutment type rotary engine that operates by the four-stroke principle and consists of a pair of chambered interactive rotors which turn in opposite directions at equal R. P. M. around a central axis. The rotors are of identical construction with one rotor inverted in relation to the other. The pair of rotors are separated by a fixed housing section which contains various components including sliding abutments and interconnecting combustion chambers. Sliding abutments are located at equidistance around the housing surface and sealingly engage with their respective rotor surfaces. The two rotors are meshed together and cause the central drive shaft to rotate. The face-to-face rotor surfaces are divided into sections of alternately located chambered and unchambered surface. The unchambered rotor surfaces have (apart from their depth) the same cross-section formation to that of the chambered rotor surfaces and are recessed to allow the sliding abutments to remain in

permanent engagement with the rotor surfaces when withdrawn from the chambered sections. Located between the chambered and unchambered surfaces are sliding transition sections which have (apart from their depth) the same cross section formation to that of the chambered and unchambered rotor surfaces. The sliding transition sections enable the sliding abutments to transfer to and from the chambered and unchambered surfaces whilst maintaining a perpendicular relationship at all times. Each chamber has a leading transition section and a trailing transition section (depending on the direction of rotation of the rotor) . The chambered rotor surfaces and recessed unchambered rotor surfaces are machined at consistent depths. The combination of a face-to-face surface relationship, consistent depth chambered and unchambered surfaces and sliding transition sections, allow all three surfaces (chambered, unchambered and transition) of both rotors, to remain on the same parallel plane.

The design enables each sliding abutment to remain in continuous contact with its respective rotor. The continuous contact, permanent engagement and parallel plane features combine to ensure that the sliding abutments and gas seals continually bear against surfaces of consistent form and curvature.

This design allows the induction and compression strokes of each four-stroke cycle to be completed within a chamber of one rotor, as it turns in one direction, and then allows the power and exhaust strokes, of the same cycle, to be completed within a chamber of the second rotor, as it turns in the opposite direction. Gas transfer between the pair of rotors is via the interconnecting combustion chambers within which they compress and ignite. Each chamber first acts as a supplying chamber, by performing the induction and compression strokes of one four-stroke cycle and then acts as a receiving chamber by performing the power and exhaust strokes of a different four-stroke cycle. The gas flow cycle can be seen by referring to the 8-stage (45°) cycle progression diagrams of Figure 3.

In a practical construction the rotary engine is geometrically designed so that the four-stroke internal combustion cycle will work efficiently and reliably within an engine operating by rotary motion. The synchronised interactive bidirectional operation produces a stroke generating cycle without reciprocating or oscillating motion.

In this invention each four-stroke internal combustion cycle is completed within and between two interactive rotors , through two different directions of

motion. The rotors, which turn in opposite directions at equal R. P. . around a central axis, allow the induction and compression operations of each four-stroke cycle to be completed within a chamber of one rotor, as it turns in one direction, and then allow the power and exhaust operations of the same cycle to be completed within a chamber of the second rotor as it turns in the opposite direction. Gas transfer between the pair of rotors is via interconnecting combustion chambers within which the gases are compressed and caused to ignite. For thermodynamic and power distribution purposes, the gas flow cycle allows the role of each chamber to be reversed as it progresses around the housing surface, i.e. each chamber will first act as a supplying chamber, by performing the induction and compression operations of one four-stroke cycle and then act as a receiving chamber, by performing the power and exhaust operations of a different four-stroke cycle, and so on. This method of operation ensures that, although a single chamber will only perform two operations of any one particular cycle, it will, however, still perform all four different operations as it rotates. This particular gas flow cycle, when used with a pair of twin chamber rotors, will produce a simultaneous diametrically opposite firing sequence and will provide equalised power

application to both sides of each rotor. The gas flow cycle also ensures continuous power application to the output drive shaft throughout rotation.

By providing two directions of motion (as are provided by a conventional piston engine) all four strokes of each cycle can be completed within and between two pairs of adjacent sliding abutments. This removes the need for the compressed gases to transfer to the opposite side of an abutment prior to (or during) ignition. By ensuring correct gas location, the need for the gas by-pass systems (as required by unidirectional 'true' rotary designs) is removed. Removal of the gas by-pass requirement enables the sliding abutments (and gas seals) to remain in continuous contact with all rotor surfaces at all times, thereby removing the gas seal separation problems normally experienced with true rotary engine designs. Continuous contact also allows the sliding abutments to be used for supplying lubrication to the rotor contact surfaces. The continuous contact method of operation also removes the need for the independent sliding abutment activation mechanisms that are required by 'make-and-break' type designs.

The interactive operation is provided by dividing the surfaces of each rotor into sections of alternately

located chambered and unchambered surface. By offsetting the leading transition surfaces of each rotor (prior to meshing) one sliding abutment will remain in contact with the chambered surface of one rotor, whilst its opposed abutment remains in contact with the unchambered surface of the other rotor, and vice versa.

For reasons of practicality, it is essential that the sliding abutments remain in continuous contact with the chambered and unchambered rotor surfaces.

If the chambers were located within the curved inner or outer surfaces (as is the case with most other rotary engine designs), the sliding abutments, which must bear against the chambered and unchambered surfaces, would need to bear against two surfaces of different diameter causing excessive abutment and gas seal wear. To overcome this problem the chambers of this invention (which are machined at constant depth) are located within the flat facing surfaces of two equal diameter interactive rotors. This allows the chambered and unchambered surfaces of both rotors to remain on the same parallel plane. However, if (as in most other rotary engine designs) transition curves were used to transfer the sliding abutment ends to and from the chambered and unchambered surfaces, the abutments would again be required to bear against surfaces of different form,

causing the same problems as those created by chambered and unchambered surfaces of different diameter. To overcome this problem sliding transition sections which allow the abutments to transfer to and from the chambered and unchambered surfaces whilst maintaining a perpendicular relationship at all times, are used.

The combination of a face-to-face surface relationship, chambered surfaces of consistent depth and sliding transition sections, allows all three surfaces (chambered, unchambered and transition) of both rotors, to remain on the same parallel plane. This, when combined with continuous contact, enables all sliding abutments and gas seals to continually bear against surfaces of consistent form and curvature. The design removes the sliding abutment to rotor surface relationship problems normally experienced with rotary engine design. Consequently, the gas sealing qualities will be similar to those of a conventional piston engine.

Although the face-to-face interactive surfaces solve the sliding abutment to rotor surface relationship problems, such an arrangement is not often used within rotary engine design. The reason for this is that during operation, the internal pressures would cause the rotor (or rotors) to be forced away from the housing surface. This would necessitate the inclusion of

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peripheral retaining bearings to prevent rotor separation and would cause excessive frictional drag against the rotor (or rotors) . If two unidirectional rotors were used, the problem could be solved by externally interconnecting the two rotors, but because this invention is (for essential purposes) bidirectional in operation, this is not possible. However, because the gas flow cycle (of a twin chamber version) provides a simultaneous diametrically opposite firing sequence, it is possible to externally interconnect two pairs of bidirectional rotors (in a specific manner) to provide pressure equalisation between the inner and outer rotors. This method of construction and operation provides a virtually friction free means of preventing rotor separation and enables the parallel plane surface relationship to be included within the design. If a two pair construction is used, the inner rotors can be joined to form (or be constructed as) double sided rotors. Therefore, a four rotor (two pair) assembly, can be built as a three rotor unit, with a double-sided central rotor turning in one direction and two externally interconnected outer rotors turning in the opposite direction. Although the two pair variation provides an ideal method of operation, for simplicity, the main drawings and description refer to a single pair

construction.

To enable the sliding transition sections to operate in a reliable manner alignment guides protrude from either side of the sliding abutments and interlock the transition sections with their relative chambered and unchambered rotor surfaces during transition. The design ensures that the sliding transition sections are in perfect alignment with the relative surfaces before the sliding abutments pass across them. It also enables automatic adjustment to compensate for any wear that may eventually occur to the transition section activation components. The alignment guides also enable a small gas-sealed clearance to be maintained between the sliding abutments and rotor surfaces which ensures that any wear to the interactive surfaces will be even. The sliding transition sections can be constructed with a parallelogram type formation which provides progressive gas seal feed across the rotor to transition/transition to rotor surfaces. This will remove any possibility of the gas seals catching as they pass across the relative surfaces.

Another major problem normally associated with sliding abutment type rotary engine design is that of maintaining correct alignment between the sliding abutments and rotor surfaces when the abutments are

withdrawn from the chambers. This problem is solved by the face-to-face interactive surface relationship which enables the inclusion of raised surfaces within the design of the central housing. The raised housing surfaces protrude from either side of the central housing and permanently engage with the unchambered rotor surfaces which are recessed to accommodate them. The sliding abutments, which have the same cross section formation to that of the raised housing surfaces will, when withdrawn from a chamber, form part of the raised housing surface and will likewise remain engaged with the recessed unchambered rotor surfaces. The design removes the need for the sliding abutments to withdraw from the rotors when withdrawn from the chambers and ensures that they remain in perfect alignment at all times. Permanent engagement between the sliding abutments and rotor surfaces could not be achieved without the raised housing surfaces and the raised housing surfaces could not be included within the design without the face-to- face interactive surface relationship.

The permanent engagement feature also provides another advantage. Because the sliding abutments, when in a withdrawn position, form a gas sealed protrusion equal in cross section formation to that of the raised housing surface, they can be constructed, if desired,

with a curved cross section formation. This allows all the relative surfaces to be curved and enables the inclusion of curved gas seals within the design. It would be very difficult to use a curved sliding abutment cross section formation without the raised housing surfaces, due to the gas sealing problems that would arise upon withdrawal of a curved sliding abutment into a flat housing surface. The use of curved gas seals within the design provides automatic wear compensation and further reduces the gas sealing problems normally associated with rotary engines.

Apart from eliminating all the major problems normally associated with unidirectional rotary engines, the design also provides other operational advantages.

The design enables the inlet and exhaust port cross section area to be variable in relation to the open chamber cross section area and enables optimum gas flow to be achieved. Because opening and closing of the inlet and exhaust ports is determined by the position of the interactive surfaces in relation to the raised housing surfaces, this invention does not require inlet and exhaust valves.

The geometric design, interactive bidirectional operation and simultaneous diametrically opposite firing sequence ensure that the engine is completely self-

balancing in operation. The externally located semi- exposed rotors (which are self-cooling in operation) provide ample momentum and remove the need for a separate flywheel.

The construction can be used in any situation where a conventional internal combustion engine is used including motor, marine, aircraft and industrial use. It can be adapted to allow mounting at any angle between horizontal and vertical. Horizontal mounting is particularly suitable for use within a motor vehicle as the central output drive shaft (which will be vertical) can be located into a gearbox mounted between the front or rear wheels. The overall height, when mounted horizontally, will be far less than that of a conventional piston engine.

A construction of a single pair version can be seen by referring to Figures 2 and 4. The gas flow cycle can be seen by referring to the 8-stage (45°) cycle progression diagrams shown in Figures 3a to 3h. It should be noted that, although the cycle progression diagrams refer to the gas flow cycle within and between a pair of face-to-face equal diameter rotors, they are shown with an inner and outer relationship for ease of description. This is because, with a plan view of the suggested construction, one rotor would obscure the

other. The diagrams are shown in this manner purely for gas flow description purposes. The correct rotor relationship can be seen by referring to Figures 2 and 4.

The rotary engine consists of a pair (or pairs) of chambered rotors which turn in opposite directions, at equal R.P. . around a central axis- The pair (or pairs) of rotors are separated by a housing section (or sections) containing components including inlet and exhaust ports, sliding abutments, interconnecting combustion chambers and rotor meshing gear.

The pair (or pairs) of rotors work together to perform an alternating interactive bidirectional four- stroke internal combustion cycle. The induction and compression operations (strokes) of each cycle are performed within a chamber of one rotor as it turns in one direction and the power and exhaust operations (strokes), of the same cycle, are then performed within a chamber of the second rotor as it turns in the opposite direction. Gas transfer between the pair (or pairs) of rotors is via the interconnecting combustion chambers within which the gases are compressed and caused to ignite. Rotor Construction

The pair (or pairs) of rotors, which can be of identical construction (if required) are assembled either

side of the housing section (or sections) with their interactive surfaces facing each other. The face-to- face interactive surfaces are divided into sections of alternately located chambered and unchambered surfaces of different (consistent) depths. The unchambered rotor surfaces have (apart from their depth) the same cross section formation to that of the chambered rotor surfaces and are recessed to allow the interactive sliding abutment ends to remain engaged with the rotor surfaces when withdrawn from the chambered sections. The recessed unchambered rotor surfaces also allow the engagement of raised surfaces that protrude from either side of the central housing section (or sections). The raised housing surfaces have the same cross section formation to that of the sliding abutments.

Located between the chambered and unchambered rotor surfaces are sliding transition sections which have (apart from their depth) the same cross section formation to that of the chambered and unchambered rotor surfaces. The sliding transition sections enable the contact surfaces of the sliding abutments to transfer to and from the chambered and unchambered rotor surfaces whilst maintaining a perpendicular relationship to them at all times.

The combination of a face to face interactive

surface relationship, consistent depth chambered and unchambered surfaces and sliding transition sections, allow all three surfaces (chambered, unchambered and transition) of both rotors (of a pair) to remain on the same parallel plane. This method of construction allows the sliding abutment gas seals to continually bear against surfaces of consistent form and curvature.

The transition section angles of both rotors are equal. The angles are suited to the sliding abutment angles. The chambered section angles of both rotors are equal. The angles are equal to the angle between the outer edges of two adjacent ports, plus the angle between the sliding abutment centres, less twice the transition section angle. The unchambered section angles of both rotors are equal. The angles are equal to the angle between the sliding abutment centres, less the angle between the outer edges of the two adjacent ports.

As the rotors are semi-exposed externally located components they are self-cooling in operation and should require no additional water or air cooling systems. The location, construction and operation of the rotors also enables momentum to be maintained without the need of a separate flywheel.

Housing Construction

The housing which separates the pair (or pairs) of rotors, contains various components including sliding abutments, interconnecting combustion chambers, rotor bearings, rotor meshing gear, central output drive shaft, inlet and exhaust porting and transition section activation components. Spark plugs (if required) are located within the interconnecting combustion chambers.

Opening and closing of the inlet and exhaust ports is determined by the position of the rotor surfaces in relation to the raised housing surfaces and removes the need for inlet and exhaust valves.

Raised surfaces, which have the same cross section formation to that of the sliding abutments, protrude from either side of the housing and permanently engage with the recessed unchambered surfaces of both rotors (of a pair) .

The housing, which can be water or air cooled as required, can be of any suitable formation. Its construction includes conventional channelling and ducting for lubrication, ventilation and cooling purposes. The inlet and exhaust ports can (if required) enter and exit via the inner housing section to facilitate the external interconnection of rotors within a multiple rotor version.

Transition Section Alignment

To ensure that the contact surfaces of the sliding transition sections always remain in perfect alignment with their relative chambered and unchambered surfaces during the transition operation, alignment guides can be built into the sliding abutments as shown in the Figure 2. If any slight misalignment occurs, (due to wear on the activation mechanism) the guides will automatically correct the misalignment before the sliding abutments pass across the relative surfaces. In the event of misalignment correction occurring, the relative sliding transition section will be caused to relieve its pressure against the activation mechanism, allowing a self- adjusting mechanism to operate. The design provides perfect transition alignment regardless of activation component wear.

As the alignment guide engagement channels are located beyond the raised housing gas sealing line, they do not require sealing. The alignment guides can be spring-loaded within the interactive sliding abutment surfaces to assist assembly.

The transition alignment design also enables a small gas-sealed clearance to be maintained between the sliding abutments and interactive rotor surfaces and prevents the increased frictional pressures that occur during the

transition operation from being applied to the sliding transition section surfaces. This ensures that any wear to the three interactive surfaces (chambered, unchambered and transition) will be even and maintains correct transition alignment regardless of interactive surface wear. The gas-sealed clearance also allows for component expansion and contraction.

Transition section activation can be provided by static axial cams, rotary cams (as shown in Figure 2) or by other means. If the activation mechanism is self- contained within the rotor surfaces (as with the rotary cam type) transition alignment can be pre-set and checked before assembly. The transition sections can be constructed with a parallelogram type formation or with other suitable formation as desired.

A parallelogram type formation will allow the gas seals to progressively feed across the rotor to transition/transition to rotor surfaces and provides automatic lowering of the gas seals if any misalignment should occur. This prevents the sliding abutment gas seals from catching (whether or not the transition sections are in perfect alignment) and also ensures that the raised housing gas seals do not catch when entering an unchambered rotor section or lowered transition section.

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Sliding Abutments

The sliding abutments are arranged in pairs and are located at equidistance around the central housing. The number of abutments required is dependent on the number of chambers used within the construction. One pair of sliding abutments are required per chamber; therefore a pair of single chamber rotors will require two pairs of sliding abutments, a pair of twin chamber rotors will require four pairs of sliding abutments, and so on.

One pair of sliding abutments (or alternate pairs of sliding abutments) will have inlet and exhaust ports located at both sides and will control the inlet and exhaust operations. The other pair of sliding abutments (or intermediate pairs of sliding abutments) will have interconnecting combustion chambers located at both sides and will control the compression and power operations.

The inlet and exhaust ports and interconnecting combustion chambers can be located within the housing surfaces, adjacent to their relative pair of sliding abutments, or can be located within the surfaces of the sliding abutments in the three dimensional sectional diagram. Rotor and Abutment Synchronisation

The centres of any two chambered sections of both rotors (of a pair) are aligned (prior to meshing) with

the centre line between any two pairs of abutments.

The specific geometrical construction and synchronised movement of components ensures that, as a pair of rotors turn in opposite directions, at equal R. P. M. around the central axis, the gas seals of each sliding abutment will remain in continuous contact with the rotors at all times. Continuous Contact

Interactive bidirectional operation enables each four-stroke cycle to be completed within and between two adjacent sliding abutments. This removes the need for the compressed gases to transfer to the opposite side of an abutment prior to (or during) ignition and thereby removes the need for the gas by-pass systems that are normally required within unidirectional true rotary designs. By removing the by-pass systems (which necessitate the sliding abutments to continually make and break contact with the rotor surfaces) the sliding abutment gas seals are able to remain in continuous contact with the rotor surfaces at all times. The continuous contact method of operation provides three main advantages that are not possible with make-and-break type designs.

Firstly, because the gas seals located within the abutments do not need to break contact with the rotor

surfaces, there is no possibility of seal separation.

Secondly, continuous contact enables abutment movement to be controlled by the movement of the rotor surfaces and removes the need for an independent sliding abutment activation mechanism.

Thirdly, continuous contact between the sliding abutment gas seals and interactive rotor surfaces enables the abutments to be used to provide lubrication between themselves and the rotor surfaces. Permanent Engagement

Raised surfaces protrude from either side of the housing and permanently engage with the recessed unchambered surfaces of both rotors. The sliding abutments, which have the same cross-section formation to that of the raised housing surfaces will, when withdrawn from a chamber, form part of the raised housing surfaces and will likewise remain engaged with the unchambered rotor surfaces. The raised housing surfaces are included within the design to provide permanent engagement between the sliding abutments and rotor surfaces at all times. Permanent engagement provides two more advantages in addition to those provided by continuous contact.

Firstly, because the sliding abutments will remain engaged with the recessed unchambered rotor surfaces

(when withdrawn from the chambered surfaces) and because the unchambered surfaces are effectively a continuation of the chambered surfaces, the sliding abutments will remain in alignment with all surfaces at all times.

Secondly, as the sliding abutments, when in a withdrawn position, form a gas sealed protrusion equal in cross section formation to that of the raised housing surfaces, they can be constructed, if desired, with a curved cross section formation. This method of construction allows all relative surfaces and associated gas seals to be curved and provides automatic wear compensation advantages. Gas Seal Construction

All gas seals are located within the raised housing and sliding abutment surfaces and will bear against the rotor surfaces.

Because the upper surfaces of the raised housing gas seals are only required to provide a seal against the recessed unchambered rotor surfaces, they are not (unlike the sliding abutment gas seals) required to remain in continuous contact with all surfaces at all times. However, because the lower surfaces of the same seals will remain in continuous contact with all lower rotor surfaces at all times, they are locked-in and there is no possibility of their upper surfaces separating from the

raised housing when the relative surfaces disengage.

A suggested construction and location of the gas seals can be seen by referring to Figure 2.

The combination of a geometrical interactive bidirectional design that enables the use of continuous contact sliding abutments, raised housing surfaces that provide permanent engagement between the sliding abutments and rotor surfaces, a curved construction of the various components that allows the gas seals to be curved and a parallel plane surface relationship that enables all gas seals to bear against surfaces of consistent form and curvature, ensures that the gas sealing problems normally associated with sliding abutment type rotary engine design are removed. Alternating Interactive Bidirectional Four-stroke Cvcle

The interactive bidirectional operation enables each four-stroke cycle to be completed through two different directions of motion, by providing two directions of motion.

The design allows the induction and compression operations of the four operation cycle to be performed in one direction of rotation, within a chamber of one rotor and then allows the power and exhaust operations (of the same cycle) to be performed in the opposite direction of rotation, within a chamber of the second rotor. Gas

transfer between a pair of rotors is via the interconnecting combustion chambers within which the gases are compressed and caused to ignite.

Additionally, (with reference to the previously described cycle) as the induction operation is being performed, the exhaust operation of another cycle is simultaneously performed, as the compression operation is being performed, the power operation of another cycle is simultaneously performed, as the power operation is being performed, the compression operation of another cycle is simultaneously performed and as the exhaust operation is being performed, the induction operation of another cycle is simultaneously performed.

The alternating interactive bidirectional four- stroke cycle allows each chamber to reverse its role as it progresses around the housing surface. In other words, each chamber will, as it rotates, first act as a supplying chamber by performing the induction and compression operations of one four-stroke cycle and then act as a receiving chamber by performing the power and exhaust operations of a different four-stroke cycle, and so on.

This method of operation ensures that, although a single chamber will only perform two operations of any one particular cycle, it will however still perform all

four different operations as it progresses around the housing surface and therefore provides an efficient interactive gas flow sequence that has a balanced distribution of power with good thermodynamic qualities.

The power strokes, within each chamber, will occur through alternate angles of rotation and the offset relationship between the two rotors will provide continuous power application to the output drive shaft throughout rotation. Cvcle Generation

Due to the method of construction and operation each chamber will simultaneously perform two unrelated cycle operations. Because of this, a pair of single chamber rotors (with an angle of 180° between sliding abutment centres) will generate eight operations (two cycles) per 360° rotation of both rotors. (720° total rotation). (720° rotation ÷ 90° chamber angle) x 4 chambers - 32 operations, and so on. Detailed Single Cvcle Description

The following section provides a more detailed description of the gas flow operation that would occur during a single four-operation cycle. For ease of description, it ignores unrelated cycle operations that would occur simultaneously at the opposite sides of the sliding abutments.

As an inlet/exhaust sliding abutment enters a chamber, via its leading transition section, a vacuum is created between itself and the leading chamber surfaces causing a combustible mixture to be drawn into the chamber through the inlet port, thus creating the induction operation. Upon completion of the induction operation the inlet/exhaust sliding abutment withdraws from the chamber, via its trailing transition section and simultaneously a compression/power sliding abutment enters the chamber, via its leading transition section, causing the combustible mixture to be compressed between itself and the trailing chamber surfaces, thus creating the compression operation. upon completion of the compression operation, the compression/power sliding abutment withdraws from the chamber, via its trailing transition section. At this stage the compressed combustible mixture is contained within the interconnecting combustion chamber. As the compression/power sliding abutment (of the same pair) enters a chamber of the second section via its leading transition, the compressed combustion mixture is caused to ignite, forcing the leading chamber surfaces with the second rotor away from the compression/power sliding abutment, thus creating the power operation. Upon completion of the power operation the compression/power

sliding abutment withdraws from the chamber, via its trailing transition section and simultaneously the induction/exhaust sliding abutment end enters the chamber, via its leading transition section, causing the burnt gases, which are between itself and the trailing chamber surfaces, to be expelled through the exhaust port, thus creating the exhaust operation.

The same sequence of operation will occur during the completion of any four-operation cycle regardless of the number of chambers used per rotor, the only variations being the angle through which the operations are completed and the number of operations completed per 360° of rotation of both rotors. Construction

Figures 2 and 4 show a version constructed with a single pair of twin chamber rotors with four sliding abutments. The interactive surfaces are located within the facing surfaces of the two equal diameter rotors and the raised housing surfaces, interactive rotor surfaces and sliding abutments are constructed with a curved cross section formation. The rotor meshing gear is arranged in a manner which will cause the central output drive shaft to rotate at twice the speed of the rotors. The suggested construction has electrical ignition, uses petrol as fuel and injection for delivery. It also

shows the employment of peripheral rotor retaining rings to prevent rotor separation. It should be noted that the frictional pressures applied to the peripheral bearings can be removed (if required) by the interconnection of two pairs of rotors in a specific manner (Figure 5).

A pair of twin chamber rotors with four pairs of sliding abutments and a meshing gear arrangement as in the three-dimensional sectional diagram will generate 32 operations (8 cycles) per 360° rotation of both rotors and therefore 16 operations (4 cycles) per 360° rotation of the output drive shaft. This equals the amount of operations (strokes) generated by a conventional eight cylinder piston engine per 360° rotation of the crankshaft.

Ignition (within this construction) will occur simultaneously diametrically opposite within both chambers of each rotor through alternate 90° angles of rotation and will provide equalised power application to both sides of each rotor. The 90° offset relationship between the pair of rotors will provide continuous power application to the output drive shaft throughout rotation.

The alternating interactive bidirectional four- stroke cycle and gas flow sequence that would occur

within an engine constructed in the suggested manner can be seen by referring to the cycle progression diagrams. It should be noted that although the diagrams refer to the gas flow within and between a pair of equal diameter rotors, they are shown with an inner and outer construction for ease of description. This is because, with a plan view of the suggested construction, one rotor would obscure the other. The diagrams are shown in this manner purely for gas flow description purposes. Variations of Construction and Operation

Although the drawings show a version constructed with the interactive surfaces facing each other, it is also possible with certain variations, to construct the engine with the interactive surfaces facing away from each other.

The interconnecting combustion chambers can be located within the housing surfaces, adjacent to the sliding abutments, or can be located within the sliding abutment surfaces.

The number of chambers per rotor can be varied and pairs of rotors can be joined together to form multiple rotor engines. Two pairs of twin chamber rotors (with simultaneous diametrically opposite firing sequence) can be externally interconnected in a specific manner, to provide pressure equalisation between the inner and outer

rotors. This variation of construction removes the need for the rotor retaining rings that are required by a single pair of bidirectional rotors and provides a virtually friction free method of preventing rotor separation (Figure 5).

When using a multiple rotor construction the inner rotors can be joined to form (or be constructed as) double sided rotors. Therefore a four rotor (two pair) assembly can be built as a three rotor unit with a double sided central rotor turning in one direction and two externally interconnected outer rotors turning in the opposite direction (Figure 6).

The gas flow sequence can be varied by relocating and/or increasing the number of interconnecting combustion chambers, by locating the inlet and exhaust ports within the interconnecting combustion chambers and by introducing inlet and exhaust valves.

The cross-section formation of the raised housing surfaces, interactive rotor surfaces and sliding abutment ends can be of any suitable shape and need not be curved (as in the three dimensional sectional diagram).

The rotor meshing gear can be arranged in any suitable location or manner to provide direct drive or any variation of ratio between the output drive shaft and rotors.

This invention can be adapted to operate on various combustible fuels and gases and delivery can be by carburration or injection, with or without turbo charging or supercharging. Ignition can be electrical or compression generated.

The engine can be adapted to operate at any angle between horizontal and vertical and can be used in any application where a conventional internal combustion engine is used including motor, marine, aircraft and industrial use.

It is possible to construct a version of the engine with a pair of unidirectional rotors by using a cross¬ over interconnecting combustion chamber design, i.e. a synchronised interactive unidirectional rotary engine. However this method of construction would complicate the design, remove the self-balancing qualities and cause a thermodynamic imbalance.