WO1982000176A1

WO1982000176A1 - Toroidal cylinder internal combustion engine

Info

Publication number: WO1982000176A1
Application number: PCT/US1981/000872
Authority: WO
Inventors: W White; B White
Original assignee: W White; B White
Priority date: 1980-06-27
Filing date: 1981-06-25
Publication date: 1982-01-21
Also published as: EP0054568A1

Abstract

A pair of toroidal cylinders (2, 4) are arranged in pairs with their transverse axes in colinear alignment. Each toroidal cylinder includes at least one piston (6A-6D). The pistons within adjacent toroidal combustion chambers rotate in opposite directions and combustion is induced at the moment when two pistons disposed within two adjacent toroidal combustion chambers pass. A combustion port (24A, 24B) is provided between the adjacently disposed toroidal cylinders. The combustion process occurs within the port and within internal combustion chambers provided within each of the pistons. This port allows a single combustion to propel the pistons in each of the cylinders in opposite directions. The pistons drive counter-rotating drive shafts (10, 12) which are constrained in a time relationship. A flap valve (44) is provided in the upstream end of each piston to allow the piston to accept fresh intake gases. Intake and exhaust valves (30A, 30B, 32A, 32B) are also provided within the cylinder walls to control the intake of a fresh charge and to allow the combustion by-products to be exhausted.

Description

Description TOROIDAL CYLINDER INTERNAL COMBUSTION ENGINE

Technical Field

This invention relates to an internal combustion engine having a pair of adjacently disposed toroidal cylinders and a pair of counter-rotating pistons dis¬ posed therein.

Background Art

Internal combustion engines having reciprocating pistons are well known and widely used. These engines include several undesirable characteristics which are inherent in their design. For example, reciprocating piston engines are difficult to balance and therefore exhibit undesirable vibrations. Also, because the piston is at rest at the top dead center position in the cylinder at the time of maximum gas expansion, the piston cannot apply useful torque on the crankshaft and thus the engine's efficiency is reduced. These and other undesirable characteristics are well known limitations of reciprocating piston designs.

Several attempts have been made to produce an internal combustion engine design which overcomes the disadvantages of the reciprocating piston design through the use of a toroidal cylinder. For example, U.S. Patent 1,562,299 to Cundy discloses a toroidal cylinder combustion engine where the combustion process occurs within the piston. Here, rotary valves present a reaction surface to the explosive gases to cause a reaction within the piston.

U.S. Patent 1,721,626 to Hanson discloses a toroidal internal combustion engine including a piston P¹ in which the combustion process is performed and a second piston P for performing the intake and exhaust gas pumping functions.

U.S. Patent 4,086,881 to Rutten discloses a rotary engine which utilizes wedge shaped pistons within a circular combustion chamber. The combustion gases are communicated to a pressurized interior hollow.

U.S. Patent 1,151,489 to Mclntyre discloses a toroidal internal combustion engine having paired cylinders. The intake charge compressed by the leadirg edge of a piston in the first chamber is passed to the rear of a piston in the second chamber and ignited to thereby propel the piston in the second chamber. Thus, the Mclntyre patent discloses the transfer of compressed intake charge between two adjacent disposed toroidal cyl¬ inders. While each of the above mentioned patents discloses an internal combustion engine having a toroidal cylinder, the present invention utilizes new principles of operation and provides many improvements and advan¬ tages over these prior art references.

Disclosure of the Invention

It is, therefore, an object of the present invention to provide a new and novel internal combustion engine where combustion is initiated in a port between two counter-rotating pistons and performed in the interior combustion chambers of the respective counter- rotating pistons.

Another object of the present invention is to provide a new and novel internal combustion engine which exhibits a high degree of dynamic balance.

It is yet another object of the present invention to provide an internal combustion engine which efficiently utilizes the expansion of combustion gases by constantly applying the combustion forces to pistons having constant velocities and to a moment arm of constant radius.

Pursuant to the present invention, an internal combustion engine has toroidal cylinders arranged in pairs. Each toroidal cylinder includes at least one piston. The piston or pistons within adjacent toroidal cylinders rotate in opposite directions. Combustion is induced in the engine of the present invention during the moment when the counter-rotating pistons pass each other. A port is provided between the two adjacently disposed toroidal cylinders and combustion is induced in this port. The port allows a single combustion to propel the pistons in each of the cylinders in opposite directions. The pistons drive counter-rotating drive shafts which are constrained in a timed relationship to synchronize the movement of adjacent pistons. The pistons are formed as cylindrical toroidal sections having substantially wedge shaped inner surfaces. A flap valve is provided in the front of each piston to introduce fresh intake gases into the piston's combustion chamber. Intake and exhaust valves are provided within the cylinder walls to admit fresh intake gases and allow the combustion by-products to be exhausted.

The attached drawings illustrate, by way of example, an embodiment of the internal combustion engine of the present invention.

O PI Brief Description of the Drawings

Figure 1 is a perspective view of the toroidal combustion engine of the present invention;

Figure 2 is a side elevation of the toroidal internal combustion engine of the present invention showing particular detail of the cylinder timing and drive gearing;

Figure 3 is a diagrammatic sectional view of the combustion chamber and counter-rotating pistons at the moment of combustion as taken along line AA of Figure 2;

Figure 4 is a perspective view of a piston of the present invention removed from the toroidal cylinder;

Figure 5 is a diagrammatical overhead section showing the interior construction and piston port arrangement of the piston of the present invention;

Figures 5A and 5B are front end views of the pistons of the present invention showing a piston flap valve in both the open and partially closed positions;

Figures 6A and 6B show a detail of the exhaust pert of the toroidal internal combustion engine of the present invention in both closed and open positions, respectively;

Figure 7 is a detailed perspective view of an intake flap valve used in the present invention; Figures 7A and 7B are details of an intake flap valve of the present invention showing this valve in the opened and closed positions, respectively; and

Figure 8 discloses a cross sectional view of the toroidal internal combustion engine of the present invention taken through the center of the combustion port along line C-C of Figure 10;

Figure 8A shows a perspective detail of the antithrust stabilizer of Figure 8;

Figure 9 is a partial perspective view showing the detail of a sealing ring used to seal the internal combustion engine cylinder;

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OMPI Figure 10 shows a schematic sectional repre¬ sentation of the internal combustion engine of the present invention showing its operation as taken along lines B-B of Figure 2.

Best Mode

Referring to Figures 1, 2 and 10, the toroidal cylinder internal combustion engine of the present invention is illustrated.

A first toroidal cylinder 2 and a second tcroidal cylinder 4 are placed side by side with their transverse axes colinearly aligned.

Figure 10 illustrates the positioning of a first set of pistons 6 having individual pistons 6A-6D within the first toroidal cylinder 2. As evident from this figure, the pistons 6A-6D are spaced in an equiangular fashion. An identical set of pistons 7 having individual pistons 7A-7D are arranged in a similar manner in the second toroidal cylinder 4. The first and second toroidal cylinders 2,4 are mirror images of each other, thus allowing the counter-rotation of the pistons 6A-6D with respect to the pistons 7A-7D. Because of the similarity between the first and second toroidal cylind¬ ers 2,4, the details of the second toroidal cylinder 4 are not illustrated. The details of the second toroidal cylinder 4 are the same as those discussed with respect to the first toroidal cylinder 2 unless otherwise indicated.

Each of the pistons 6A-6D are connected to respective ones of a set of connecting rods 8 having individual connecting rods 8A-8D. The pistons 6A-6D of the first toroidal cylinder 2 are connected through their respective individual connecting rods 8A-8D to an inner drive shaft 10. Similarly, the pistons 7A-7D of the second toroidal cylinder 4 are connected to a similar set

O FI of connecting rods (not shown) which are connected to an outer drive shaft 12.

The outer drive shaft 12 terminates by connection to a first output gear 14. Similarly, the inner drive shaft 10 terminates at one end by connection to a second output gear 16. The first output gear 14 and the second output gear 16 are bevelled gears having the same bevel angle and number of teeth. The first and second output gears 14, 16 are synchronized for precise control of the location of the pistons 6A-6D within the first toroidal cylinder 2 with respect to the location of the pistons 7A-7D within the second toroidal cylinder. This synchronization is performed by a first synchronization gear 18 and a second synchronization gear 20 which are rotatably mounted on a synchronization shaft 21 having an axis perpendicular to the axes of the inner and outer drive shafts 10, 12. The synchronization gear shaft 21 is rigidly held to prevent rotation of the first and second synchronization gears 18, 20 about the axes of the inner and outer drive shafts 10, 12 by a set of supports 22A, 22B. The first and second output gears 14, 16 together with the first and second synchronization gears 18, 20 collectively form a bevelled epicyclic gear train, generally known as BET. In the preferred embodiment, a set of combustion ports 24A, 24B are provided for communication between the first toroidal cylinder 2 and the second toroidal cylinder 4. As shown in Figure 2,these combustion ports 24A, 24B allow the communication of gases between the first toroidal cylinder 2 and the second toroidal cylinder 4. As the center of each com¬ bustion port 24 is the center of the combustion process, each combustion port is provided with a spark plug 26. It is readily apparent that the toroidal cylinder internal combustion engine of the present invention may be used with various types of fuels or ignition arrangements. For example, a fuel injection nozzle could be used with the spark plug 26 in a gasoline engine or a diesel fuel injector could replace the spark plug 26 and diesel combustion could be relied upon. A cam ring 28 is attached to the set of connecting rods 8. This cam ring 28 controls the opening and closing of a pair of intake flap valves shown generally as 30A, 30B, and a pair of exhaust gate valves shown generally as 32A, 32B as will be later discussed. The cam ring is provided with a set of cam plateaus 31 and set of cam valleys 29. The number of individual cam valleys 29A-D and individual cam plateaus 31A-D correspond to the number of individual pistons 6A-D. A pair of secondary intake flap valves 34A, 34B are also provided to improve the breathing of the toroidal internal combustion engine of the present invention. If normal carburation is relied upon, the engine of the present invention may have intake manifolds and carburators attached. Referring now to Figures 3, 4, 5, 5A and 5B, the shape of the piston used in the toroidal combustion engine of the present invention is illustrated. All of the pistons 6A-6D and 7A-7D are constructed in an identical fashion. Figure 4 illustrates an exemplary piston used in the present invention. This piston is exteriorly shaped in the form of a chordal section of a toroid having a circular cross section in a direction transverse to the piston's direction of travel. The diameter of the piston's circular cross section is substantially identical to the diameter of the bore of the toroidal cylinders 2, 4 of the present invention. In the preferred embodiment, this piston may be a section of approximately 15°of th toroidal cylinder. Each of the pistons used in the present invention has an outer wall 36 substantially conforming to the interior of the

O PI toroidal cylinders 2,4 of the present invention. An interior combustion chamber 38 is also provided as can be best illustrated in Figure 5. The side of each piston nearest the combustion ports 24A, 24B has a piston combustion port 40 formed therein. This combustion port extends along a greater portion of the length of the piston and allows combustion gases to be communicated between the counter-rotating pistons of the present invention. An exhaust piston port 42 is also provided in the side of the piston of the present invention. This exhaust piston port 42 is provided on the opposite side of the piston from the piston combustion port 40. This piston exhaust port 42 does not extend along substantially the entire length of the piston but rather extends along approximately the upstream one-half of the piston.

The internal combustion chamber 38 of the piston has a relatively large cross sectional area near an upstream portion 37 and a relatively small cross sectional area near a downstream portion 39. The interior combustion chamber 38 is tapered from the upstream portion portion to the downstream portion by varying the thickness of an outer toroidal section wall 41 directly opposite of the piston combustion port 40. A piston gate valve 44 is provided in the front of the piston. This gate valve allows substantially the entire surface area of the upstream end of the piston to be opened to allow intake gases to be presented into the interior combustion chamber 38. This piston gate valve 44 includes a first and a second gate valve doors 46, 48, pivotally mounted on a gate valve pivot shaft 50. A gate valve bias spring 52 is provided to bias the gate valve doors closed when intake gases are net being supplied into the interior combustion chamber 38. Alternatively, a ball valve may replace the piston gate valve 44 as would occur to one skilled in the art. When the pressure in front of one of the vidual pistons 6A-6D, 7A-7D is greater than the pressure within the piston interior combustion chamber 38, the gate valve opens as shown in Figure 5B. When the pressure within the piston interior combustion chamber 38 is greater than or equal to the pressure outside the piston the gate valve 44 closes as shown in Figure 5A.

Figure 3 discloses the location of two pistons, for example, pistons 6A and 7A at the moment of combustion as they pass combustion port 24A between toroidal cylinders 2 and 4. The force of combustion drives the individual pistons 6A, 7A in their respective directions of travel due to the unequal forces applied within the piston 6A and 7A. The shape of the interior combustion chambers 38 of each of pistons 6A and 7A aids in the creation of an offset force with a component in the pistons direction of travel.

Figures 6A and- 6B show a detail of an exhaust gate valve 32 of the present invention. Figure 6A shows the exhaust gate valve in the closed position. A gate 54 is held in a gate frame 56 which guides the gate 54 between the open and closed positions. A gate push rod 58 is attached to the gate 54 and controls the opening and closing of gate 54 in response to the positioning of gate cam roller 60 which follows the cam ring 28. A gate valve spring 62 is used to maintain the gate cam roller 60 against the cam ring 28 to thereby ccntrol the opening and closing of the exhaust valve. An exhaust manifold may be connected to each of the exhaust ports 32A,32B to direct the exhaust gases to a muffling and pollution control system.

Figure 7 illustrates the valve train which is a part of each of the intake flap valves 30. Figures 7A and 7B illustrate the positioning of the valve train and the flap valves in the open and closed positions respectively. An intake port 64 is provided along the outer edge of the toroidal cylinder of the present invention, just forward of the combustion port 24. This intake port 64 has a corresponding intake flap 66 which sealingly covers the intake port and allows the piston to freely pass when closed. When open, this intake flap substantially covers the entire cross section of the interior of the toroidal cylinder of the present invention. The intake flap 66 is mounted on an intake flap mount 68 which is hinged on an intake flap pivot shaft 70. An intake pivot rack 72 and an intake pivot pinion 74 convert the linear movement produced by an intake cam roller 76 and applied by an intake push rod 78 into motion to rotate the intake pivot rack 72. An intake flap valve bias spring 80 is provided to maintain the cam roller 76 against the cam ring 28.

Figure 8 illustrates the relationship between the sets of pistons 6,7, the sets of connecting rods 8 and the cam rings 28. As readily apparent from Figure 8, the cam rings 28 are mounted onto the connecting rods 8. Thus, the cam revolves at a speed identical to the speed of the pistons. A pair of anti-thrust stabilizers 82 are further shown in Figure 8. These anti-thrust stabilizers 82 are used to stabilize the side loading due to components of the combustion force transverse to the piston's direction of travel. Since the force of combustion forces the pistons associated with this combustion apart, the anti-thrust stabilizers 82 are placed on the connecting rods so as to allow a pair of thrust slide surfaces 84 to interact. Figure 8A illustrates the detail of the anti-thrust stabilizers 82. As can be seen from this figure, a transitional ramp 86 is used to allow a gradual contact of the thrust slide surfaces 84 when passing due to the counter-rotational movement of the connecting rods 8. The thrust stabilizers thus attenuate side loading caused by forces of combustion transverse to the piston's direction of travel.

Figure 9 illustrates a detail of one section of the toroidal cylinder of the present invention which shows a sealing ring 88 used to seal a gap 90 in the wall of the toroidal cylinder of the present invention. This sealing ring prevents the leakage of engine gases and oil which would escape from the gap 90 without the presence of the sealing ring 88. Although unnecessary for the operation of the toroidal internal combustion engine of the present invention, a supplemental intake flap valve is advantageously provided in the toroidal cylinder at a point in the rotation of the piston just downstream one of the exhaust gate valves 32. A supplemental intake port 91 is provided in the exterior wall of each of the first or second toroidal cylinders 2,4. A supplemental intake manifold 92 is attached to the cylinder wall surrounding the supplemental intake port 91. A supplemental intake flap valve 94 is used to control the flow of intake gases. This supplemental intake flap valve 94 is held closed by supplemental intake valve bias spring 96 when no intake charge is entering the toroidal cylinder 2 of Figure 10. The supplemental intake manifold 92 is used to place the supplemental intake flap valve 94 a sufficient distance away from the toroidal cylinder 2 to prevent the supplemental intake flap valve 94, when open, from interfering with the movement of the set of pistons 6. The cooling of the toroidal cylinder internal combustion of the present invention may be accomplished in a number of manners. A preferred method is the use of cooling fins (not shown) on the outer walls in addition tc blades (not shown) attached to the set of piston

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OMPI ±2

reds 8 and the outer drive shaft 12. The air used for cooling may also be directed toward the intake ports under pressure to increase the efficiency of the engine. If necessary, water jackets could replace the cooling fins to make the engine water cooled as is well known in the art.

For lubrication the engine of the present invention may use a gear driven pump and a small oil suπp (not shown) at any desired location in the base of the engine. It may also be advantageous to surround the engine with a shroud or housing to keep the moving parts clean and to contain any oil and gases which may escape from the cylinders 2,4 through the sealing ring 88.

To start the engine of the present invention, any method may be used to rotate the engine in the proper direction. For example, a starter and ring gear .may be attached to a splined drive shaft 98. The splined drive shaft 98 may also be used as a power takeoff.

Referring to the drawings, and in particular to Figures 3 and 10, the toroidal cylinder internal combustion engine of the present invention operates as follows:

As pistons 6A and 7A approach the combustion port 24A, they are filled with a fresh intake charge. As these pistons reach the position shown in Figure 3, the spark plug 26A ignites the intake charge to create a combustion. Due to the internal shape of the pistons 6A, 7A, the pistons are forced apart in the direction of the arrows shown in Figure 3. The anti- thrust stabilizers 82 are used to reduce the transverse loading and to prevent excessive wear on the outer piston wall due to the transverse forces exerted by the combustion process. This combustion process drives the

"BUREA OMPI pistons in their respective directions.

Because of the location of the cam valley 29A with respect to piston 6A, the intake flap valve 30A closes upon the approach of the piston 6A. The intake flap valve 30A remains closed until the piston 6A passes its location at which time the cam plateau 31A causes the intake flap valve 30A to open. This blocks any air flow which might pass through the toroidal cylinder and allows the suction effect produced by the movement of the piston 6A to draw a fresh intake charge into the cylinder through the intake flap valve 30A. Because the previous piston has left a fresh intake charge in the area of the toroidal cylinder in front of the flap valve 30A, the piston 6A pushes this intake charge around the toroidal cylinder. When the piston 6A reaches the exhaust gate valve 32A, the cam valley 29A in the cam ring 28 causes this exhaust valve to open. As shown in the piston cutaway of Figure 5, the exhaust port 42 is passed across the open exhaust gate valve 32A and thus the spent combustion gases are removed from the piston 6A.

Fresh intake gases entering the interior combustion chamber 38 through the piston gate valve 44 force the exhausted gases out of the interior combustion chamber 38 through the exhaust port 42 and the open exhaust gate valve 32A, allowing the fresh intake gases to enter the piston 6A. The passing of the previous piston has created a vacuum and allowed fresh intake charges to be loaded into the area of the toroidal cylinder between the supplemental flap valve 34A and the ccmbustion port 24B. As the piston 6A continues its travel past the supplemental intake flap valve 34A, the intake charge is compressed into the interior combustion chamber 38 of the piston 6A as the gases are compressed between the rear of the intake flap valve 30B and the piston 6A. Simultaneously, as the piston moves between the supplemental intake flap valve 34A and the intake flap valve 30B, a vacuum is created behind the pis¬ tons 6A which opens the supplemental intake flap valve 34A and allows a fresh intake charge to enter the toroidal combustion chamber downstream of this valve. As the piston 6A approaches the second combustion port 24B, the corresponding piston 7A in the second toroidal cylinder 4 approaches this combustion port from the opposite direction.

As shown in Figure 3, these two pistons 6A, 7A reach the combustion port 24B, and the spark plug ignites the intake charge and combustion occurs starting a cycle identical to the one started by the combustion occurring in piston 6A and 7A at combustion port 24A. Piston 6A then continues the cycle and returns to combustion port 24A. The other three pistons 6B-6D of the first toroidal cylinder 2 and the other three pistons 7B-7D of the second toroidal cylinder 4 operate in a similar manner. It should be noted that the toroidal cylinder internal combustion engine of the present invention could also operate with any multiple of pistons. For example, three or six equally spaced pistons could be provided instead of four. The cam ring 28 must, however, have a number of cam valleys 29 and cam plateaus 31 equal to the number of pistons. The power created by each cylinder of the toroidal cylinder internal combustion engine of the present invention is applied to the inner drive shaft and the outer drive shaft 12. Because of the relationship imposed upon these two shafts by the bevelled epicyclic gear train BET, the pistons of the two cylinders remain rigidly timed. This rigid timing allows power to be taken off either the inner drive shaft 10 or the outer drive shaft 12. As an example of one form of output drive shaft, the splined drive shaft 98 is provided on the end of inner drive shaft 10 as shown in Figure 2. The operation of a preferred embodiment of the present invention having been disclosed, it is clear that other preferred embodiments are within the scope of the present invention. The present invention may be modified as would occur to one of ordinary skill in the art without departing from the spirit and scope of this invention.

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O FI

Claims

1. A rotary internal combustion engine comprising: first and second toroidal cylinders; a piston disposed within each of said first and second toroidal cylinders, each of said pistons having an internal combustion chamber formed therein; a combustion port provided between said first and second toroidal cylinders; means for introducing an intake charge in said interior combustion chamber of each of said pistons; means for igniting the intake charge to drive said pistons disposed within each of said cylinders in counter- rotating directions, said means for igniting being located in said combustion port.

2. The rotary engine of claim 1 wherein said pistons each include a piston combustion port formed in one side of said piston for communication with said combustion port when said piston passes said combustion port during rotation of the piston.

3. The rotary engine of claim 2 wherein the exterior of said piston has the configuration of a toroidal section; and wherein said piston has an upstream leading end portion and a downstream trailing end portion; said interior combustion chamber being tapered and having a relatively large cross sectional area near the upstream end portion of said piston and a relatively small cross sectional area near the downstream end portion of said piston.

4. The rotary engine of claim 2 wherein the taper of said interior combustion chamber is formed by the varying of the thickness of the toroidal section wall directly opposite to said piston combustion port.

5. The rotary engine of claim 2 or 4 wherein the upstream leading edge portion of each of said piston has a valve disposed therein to allow the entry of an intake charge into each of said pistons.

6. The rotary engine of claim 5 wherein said valve is a unidirectional pressure' responsive flap valve.

7. The rotary engine of claim 1 or 4 further comprising exhaust valve means for removing expended gases from said pistons, said exhaust valve means including a piston exhaust port located in each piston to provide access to said interior combustion chamber of each piston, and ar exhaust valve provided in each cylinder and located to allow communication with said piston exhaust port to thereby remove said gases.

8. The rotary engine of claim 7 wherein said exhaust valve is a gate valve.

9. The rotary engine of claim 8 wherein said means for introducing an intake charge includes a primary intake flap valve and a secondary pressure responsive intake flap valve; said primary intake flap valve substantially blocking said toroidal cylinder downstream of the opening produced by said valve in order to allow said piston to draw a fresh intake charge into said engine.

10. The rotary engine of claim 9 further comprising: a cam ring for controlling the opening and closing of said primary intake flap valve and exhaust gate valve, said exhaust gate valve having a pυshrod which allows the valve to be controlled by said cam ring. -

11. The rotary engine of claim 10 wherein said secondary intake flap valve is a pressure responsive spring biased flap valve.

12. The rotary engine of claim 1 or 4 wherein said means for igniting is a spark plug; and wherein the intake charge is a fuel- air mixture.

13. The rotary engine of claim 1 or 4 wherein said means for igniting is a diesel injector; and wherein said intake charge is air. ιy

14. The rotary engine of claim 10 further comprising: means for supplying power, said means for supplying power including an output shaft.

15. The rotary engine of claim 14 wherein said means for supplying power comprises; a connecting rod attached to each of said pistons disposed in said first and second toroidal cylinders; a pair of counter-rotating shafts; gear means for converting the forces supplied by said counter-rotating output shafts into a unidirectional rotational force; and an output shaft for supplying said unidirectional force to a load.

16. The rotary engine of claim 1 wherein each of said first and second toroidal cylinders has a transverse axis about which its piston rotates; and wherein said transverse axes are colinear.

17. The rotary engine of claim 15 wherein each of said first and second toroidal cylinders has a transverse axis about which its piston rotates; and wherein said transverse axes are coaxial.

18. The rotary engine of claim 16 wherein said counter- rotating shafts are rigidly timed by a bevelled epicyclic gear train.

19. The rotary engine of claim 18 wherein said bevelled epicyclic gear train rigidly synchronizes the timing of said counter-rotatirg pistons so as to simultaneously present said pistons at said combustion port.

O PI

20. The rotary engine of claim 17 wherein said pair of counter-rotating drive shafts are coaxial inner and outer drive shafts.

21. The rotary engine of claim 20 wherein said counter- rotating shafts are rigidly timed by a bevelled epi-cyclic gear train.

22. The rotary engine of claim 21 wherein said bevelled epi-cyclic gear train rigidly synchronizes the timing of said counter-rotary pistons so as to simultaneously present said pistons at said combustion port.

23. The rotary engine of claim 22 wherein said first and second toroidal cylinders have discontinuity in each of their surfaces which allows said connecting rods to be attached to said pistons through the walls of said toroidal cylinders.

24. The rotary engine of claim 23 further comprising: annular sealing means for sealing said discontinuity in each of said toroidal cylinders, said annular sealing means substantially preventing the escape of oil and compressed gases from said toroidal cylinders.

25. The rotary engine of claim 23 further comprising: transverse thrust attenuation means for preventing excessive piston-cylinder wall loading due to transverse combustion forces.

26. The rotary engine of claim 16 further comprising: synchronization means for rigidly timing said counter-rotating pistons so as to simultaneously present said pistons at said combustion port.