US3860366A

US3860366A - Rotary engine

Info

Publication number: US3860366A
Application number: US433989A
Authority: US
Inventors: Robert J Haglund; Thomas R Zimmer
Original assignee: General Motors Corp
Current assignee: Motors Liquidation Co
Priority date: 1974-01-17
Filing date: 1974-01-17
Publication date: 1975-01-14
Anticipated expiration: 1992-01-14

Abstract

A rotary engine with a two-lobe internal peripheral wall and a three-lobe planetary rotor has the peripheral wall formed so that apex seals that are mounted on the rotor and engage the peripheral wall to seal a chamber therebetween are simultaneously wedged gradually radially inwardly when chamber pressure is high so that the apex seal engagement with the peripheral wall is mechanically enforced by wedging action to reduce leakage past these seals to adjacent chambers.

Description

United States Patent Haglund et al. Jan. 14, 1975 ROTARY ENGINE 3,196,848 7/1965 Bensinger 123/845 Inventors: Robert J- g Birmingham; 3,270,720 9/1966 Erhardt 123/801 3; Zlmmer Llvoma both Primary Examiner-William L. Freeh Assistant Examiner0. T. Sessions [73] Assignee: General Motors Corporation, Attorney, Agent, or Firm-R. L. Phillips Detroit, Mich. 221 Filed: Jan. 17, 1974 [57] ABSTRACT A rotary engine with a two-lobe internal peripheral [21 1 Appl' 433989 wall and a three-lobe planetary rotor has the peripheral wall formed so that apex seals that are mounted [52] us. Cl. 418/61 A, 123/845 0n the rotor and ngag th peripheral wall to seal a [51] Int. Cl. Folc 1/02 chamber een are simultaneously wedged [58] Field of Sear h 123/301, 8 45; 413/61 A gradually radially inwardly when chamber pressure is high so that the apex seal engagement with the periph- [56] References Cit d eral wall is mechanically enforced by wedging action UNITED STATES PATENTS to reduce leakage past these seals to adjacent cham- 3,116,722 1/1964 Froede 123/801 bets 3,139,072 6/1964 Froede 123/8.01 4 Claims, 5 Drawing Figures PAIENTED JAN 1 4 I975 sum 2 or 2- B c I D 0" I20 210 INNER PERIPHERAL WALL LOCATION B c 90 I20 INNER PERIPHERAL WALL LOCATION O kzmzzmudluma ROTARY ENGINE This invention relates to rotary engines and more particularly to an internal peripheral wall for such engines that provides wedging action on the apex seals on the engines rotor to reduce leakage therepast.

In the presently commercial rotary engine having a two-lobe internal peripheral wall and a three-lobe planetary rotor, the apex seals at the rotors apexes are urged to engage the peripheral wall to provide sealing between the adjacent chambers by a combination of spring force, centrifugal force, and gas pressure. These apex seals normally have a constant radius sealing edge and the peripheral wall conforms to the outer envelope of these sealing edges that is developed when the rotor is turned with these sealing edges at equal radial distances from the center of the rotor. In geometrical terms, the peripheral wall follows a curve outside of and parallel to an epitrochoid through the center of curvature of the apex seal sealing edge with the distance therebetween equal to the radius of curvature of the apex seal sealing edge. The result is that theoretically the apex seals are not required to move radially with respect to the rotor as the rotor turns to maintain sealing engagement with the peripheral wall which is highly desirable. Such construction is disclosed in U.S. Pat. No. 2,988,008 issued June 13, 1961. However, in actual practice it has been found that because of thermal distortion, running clearance and manufacturing tolerances, the apex seals are actually required to travel some small amount to maintain their sealing engagement with the peripheral wall. Heretofore, there have been proposals to modify the shape of the internal peripheral wall in an effort to either prevent any apex seal movement or force movement of the leading apex seal in either radial direction for the purpose of improving gas sealing and/or preventing chatter marks on the peripheral wall. Such constructions are disclosed in U.S. Pat. No 3,102,492 issued Sept. 3, i963, U.S. Pat. No. 3,139,072 issued June 30, 1964 and U.S. Pat. No. 3,196,848 issued July 27, 1965.

We have found that while chatter marks can be elimir nated without such peripheral walls modifications by other methods such as selection of materials and surface finishes, the actual movements of the apex seals in a rotary engine having an unmodified peripheral wall which is parallel to a true epitrochoid can cause substantial gas leakage when high gas pressure is developed in the chambers during the compression and expansion or power phases of the engine cycle. We have found that the sealing provided by the apex seals can be substantially improved by providing peripherally spaced wedges on the peripheral wall that are effective to simultaneously wedge the leading apex seal and the trailing apex seal of each chamber gradually radially inwardly on rotor rotation when the chamber pressure rises above a certain value which occurs during the compression and expansion phases. Thus, the apex seal engagement with the peripheral wall at both ends of the chamber is mechanically enforced by wedging action provided by the peripheral wall rather than depending upon the normal radially outwardly acting forces on these apex seals.

An object of the present invention is to provide a new and improved rotary engine construction.

Another object is to provide in a rotary engine a peripheral wall that operates to wedge radially inwardly both the leading apex seal and the trailing apex seal of each chamber when the pressure therein rises above a certain value during the compression and expansion phases of the engine cycle.

Another object is to provide in a rotary engine an inner peripheral wall that in a peripherally extending direction deviates inwardly from the normal outerenvelope of the apex seal sealing edges so that the leading apex seal and the trailing apex seal of each chamber are simultaneously wedged gradually radially inwardly by the peripheral wall when chamber pressure exceeds a certain value whereby the apex seal engagement with the peripheral wall at both ends of the chambers is mechanically enforced by wedging action provided by the peripheral wall when the chamber pressure is high to reduce gas leakage past these seals.

These and other objects of the present invention will be more apparent from the following description and drawing in which:

FIG. 1 is a longitudinal view with parts in section of one embodiment of a rotary engine constructed according to the present invention.

FIG. 2 is a view taken along the line 2-2 in FIG. 1.

FIG. 3 is a view similar to FIG. 2 showing another embodiment of the inner peripheral wall according to the present invention.

FIG. 4 is a displacement diagram of the modified portion of the peripheral wall in FIG. 2.

FIG. 5 is a displacement diagram of the modified portion of the peripheral wall in FIG. 3.

The present invention is for use in a rotary combustion engine of the planetary type shown in FIGS. 1 and 2. The engine comprises a housing which in a single rotor arrangement, as shown, has basically three parts; namely, a rotor housing 12 having an inwardly facing inner peripheral wall 14 and a pair of

end housings

16 and 18 having parallel, oppositely facing, spaced

inner ends walls

20 and 22, respectively. The housing parts are secured together by bolts, not shown, and the

inner housing walls

14, 20 and 22 cooperatively provide a cavity 24. As shown in FIG. 2, the peripheral wall is a two-lobe curve with a center line indicated at 26 and orthogonal major and minor axes therethrough. A crankshaft 28 extends through the cavity and is rotatably supported in sleeve bearings 30 and 32 which are secured in

collars

34 and 36 that are bolted to the

end housings

16 and 18, as shown in FIG. 1, the crankshaft axis being coincident with the center line 26, parallel to the peripheral wall 14 and at right angles to the

end walls

20 and 22. The crankshaft 28 is provided in cavity 24 with an eccentric 38. A three-lobe rotor 40 has a hub 41 having a sleeve bearing 42 secured therein which is received on the eccentric 38 so that the rotor is thereby supported in cavity 24 for rotation about the eccentrics center line 44 which is thus the rotors axis.

The rotor 40 has the general shape of an arcuate sided triangle with two

parallel side walls

46 and 48 at right angles to the rotor axis which face and run close to the

end walls

20 and 22, respectively, and an outer peripheral wall having three arcuate outer faces 50 which face the peripheral wall 14 and cooperate therewith and with the

end walls

20 and 22 to define three variable volume working chambers 52. Sealing of these chambers is effected by sealing means comprising three apex seals 54 which are each mounted in an axially extending groove or slot at each apex or corner of the rotor 40 and extend the width thereof. Three arcuate side seals 56 are mounted in accommodating grooves in each rotor side and extend adjacent the rotor faces between two of the apex seals 54. Three cylindrical corner seals 58 are mounted in cylindrical blind bores in each rotor side contiguous with the apex seal slots with each corner seal having a slot receiving one end of an apex seal and providing sealing between the ends of two side seals and one apex seal as shown in FIG. 2. The apex seals 54 are spring biased to engage the peripheral wall 14 and both the side seals 56 and the corner seals 58 are spring biased to engage the respective end walls and 22 with the complete gas seal arrangement acting to seal the working chambers. A circular oil seal 60 mounted in an accommodating groove in each side of the rotor is spring biased to engage the opposing housing end wall to prevent the oil used for lubrication from passing further radially outward.

With the two-lobe peripheral wall 14 and the threelobe rotor 40, each of the working chambers 52 sequentially expands and contracts between minimum and maximum volume twice during each revolution while the rotor apexes closely follow the peripheral wall by forcing the rotor to rotate at one-third the speed of the crankshaft. This is accomplished by gearing comprising an internal tooth gear 62 which is formed integral with the right-hand side 48 of the rotor and concentric with the rotor axis. The gear 62 meshes with an external tooth annular gear 64 which is freely received about and is concentric with the crankshaft 28 and is made stationary by being formed integral with the left-hand end of the right-hand collar 36 as shown in FIG. 1. The gear 62 has one and one-half times the number of teeth as the gear 64 to provide the required speed ratio of 3:1 between the crankshaft and the rotor.

A combustible air-fuel mixture from a suitable carburetor arrangement, not shown, is made available to each working chamber 52 by an intake passage 66 as shown in FIG. 2. Intake passage 66 extends through the engine housing and opens to the cavity through either the peripheral wall 14, as shown, or through aligned ports in the

end walls

20 and 22 or through a combination thereof with such porting being located on the leading side of cusp 68 of the peripheral wall relative to the direction of rotor rotation indicated by the arrow in FIG. 2, this cusp being centered on the minor axis. Thus, the rotor uncovers the intake passage to the chambers as they are expanding in the intake phase to draw in the combustible mixture and then closes this passage to them when they are contracting to compress the mixture in the following compressionphase. A single channel or recess 69 is provided in the center of each chamber face of the rotor so that when each rotor face is at or near its top-dead-center position with its center opposite the peripheral walls other cusp 70 at the other end of the minor axis the associated chamber is not then divided by this cusp. A spark plug 72 is mounted in the rotor housing 12 adjacent the cusp 70 with its electrodes exposed to the passing working chambers and is supplied with voltage from a suitable ignition system, not shown, at the proper time at or near top-dead-center to initiate combustion at the end of the compression phase. On combustion the peripheral wall 14 takes the reaction forcing the rotor to continue rotating while the gas is expanding in the expansion or power phase. The leading apex seal 54 of each of the working chambers eventually traverses an exhaust passage 74 in the rotor housing on the trailing side of the cusp 68 whereby the exhaust products are then expelled in the exhaust phase to complete the cycle.

The engine construction thus far described is conventional. It should also be understood that it is conventional practice as is found in present commercial rotary engines of this type to design the inner peripheral wall 14 so that apex seals having constant radius sealing edges are not required to move substantial radial distances on the rotor to maintain engagement with the peripheral wall while the actual sealing contact moves along the sealing edges. Thus, instead of a fixed line contact between the sealing edges of the apex seals and the inner peripheral wall, there is provided a moving line contact that spreads the wear across the width of the apex sea]. This conventional inner peripheral wall shape is determined by first generating a true epitrochoid wherein the generating point is the center of curvature of the constant radius sealing edge of the apex seals and then adding to these dimensions an amount equal to the radius of curvature of the sealing edges normal to the true epitrochoid over its entire length. This construction is disclosed in the earlier identified U.S. Pat. No. 2,988,008. We have found that in such a conventionally constructed engine, substantial leakage from the chambers past the apex seals can occur in the compression and expansion phases when chamber pressure rises substantially above atmospheric pres sure. For example, we have observed substantial leakage when the chamber pressure exceeds 50 psi. We have found that is it possible to modify the contour of the inner peripheral wall 14 to wedge both the leading apex seal and the trailing apex seal of each chamber in a certain manner when the chamber pressure therein becomes significant from a gas leakage standpoint and thereby improve the sealing thereof. This is accomplished by providing the inner peripheral wall with either a double wedge or a single wedge configuration that acts to simultaneously wedge the leading apex seal and the trailing apex seal of each chamber gradually radially inwardly in their slots on the rotor during the compression and expansion phases. The double wedge construction is shown in FIG. 2 and a displacement diagram thereof is shown in FIG. 4. Using the major axis as a base reference at the location designated A between the inlet port and the spark plug and measuring therefrom in the clockwise direction, we have found that significant leakage from a chamber can occur when the trailing apex seal of the chamber travels from 0 to or A to B while the leading apex seal travels from to 210 or C to D. To prevent such leakage, the peripheral wall 14 is modified in the peripheral direction so as to deviate inwardly from the conventional profile shown in dashed line in the high chamber pressure zone of the rotor housing with this deviation being such that there is a rapid transition in the direction of rotor rotation from the normal wall configuration to provide a fast rise in a short peripheral wall distance to a first wedge, 14 which has a constant incline or slope with a small angle 0 such as 5between the points A and B. The modified portion 148.0 of the p w ri pheral wall thereafter rapidly returns to the conventional E85 tour midway between the points B and C and then there is again a rapid transition or fast rise in a short peripheral wall distance to a second wedge 14 which has the same slope 0 as the first wedge and extends between the points C and D. After the point D, the second wedge 14 then rapidly falls off to the conventional shape. Preferably, the transitions at each end of the wedges 14 and 14 are sine waves for good apex seal acceleration control.

With the two wedges 14 and 14 thus provided in the peripheral wall 14 and as the rotor rotates, the pressure in a chamber in the compression phase will start to rise above the significant leakage pressure value each time the rotor reaches the dashed line position shown in FIG. 2, in which event the chamber then undergoing compression has its leading apex seal then starting on the leading wedge 14 and the trailing apex seal then starting 'on the trailing wedge 14,,.,;. Thereafter as the rotor continues to rotate the leading and trailing wedges wedge the respective leading and trailing apex seals gradually radially inward throughout the remainder of the compression phase and then into the expansion or power phase until the leading apex seal reaches the end of the leading wedge 14 at point D while the trailing apex seal reaches the end of the slope 14 at point B. The wedging of the apex seals sealing this chamber thus terminates near the end of the power phase when chamber pressure is low and thereafter the before described leading apex seal then follows the normal contour until it serves as the trailing apex seal for the preceding chamber and is wedged by the trailing wedge 14 while the before described trailing apex seal then serves as the leading apex seal for the following chamber and is wedged by the leading wedge 14 Thus, the total apex seal travel is zero for the full 360 of rotor rotation with returns to the conventional peripheral wall profile between points B and C and just after point D.

It is also possible to build the leading wedge 14 on top of the trailing wedge 14 as shown in FIG. 3 and illustrated in FIG. 5. The slope 0 of the wedges remains the same but instead of the curve portion 14 returning to the normal profile between the points B and C, there is provided an accelerated rise to the leading wedge 14 with the leading apex seal after leaving this wedge at D then following a steeper step out to the conventional profile. This latter step can be reduced by reducing the rise 14 with the minimum step occurring when the leading wedge is made a straight line continuation of the trailing wedge.

Thus, in both embodiments there is provided an initial fast radially inward displacement of the apex seals as they enter the high pressure zone and thereafter linear radially inward displacement as they progress therethrough. This initial take-up is determined to offset any clearances that might defeat the wedging action with the linear wedge portions thereafter providing an assured continuous gradual wedging action throughout the high pressure zone to assure continuing good seal contact.

The actual apex seal displacement forced by the wedges is, of course, selected to suit a particular engine design. However, for illustrative purposes we have found that significant sealing improvement has resulted with the wedge dimensions indicated in FIGS. 4 and 5 wherein there is a 0.004 inch take-up for clearances and thereafter a linear increase of 0.002 inch.

The above described embodiments are illustrative of the invention which may be modified within the scope of the appended claims.

We claim:

l. A rotary engine comprising a housing having a multi-lobe internal peripheral wall and two oppositely facing side walls cooperatively defining a cavity, a shaft extending through said cavity and side walls and rotatably supported by said housing, said shaft having an eccentric located in said cavity, a multilobe rotor located in said cavity and rotatably mounted on said eccentric of said shaft, means providing a fixed speed ratio between said rotor and said shaft, said rotor cooperating with said walls and said cavity to provide a plurality of chambers that are spaced about and move with said rotor while varying in volume in fixed relation to said walls as said rotor and said shaft rotate, an intake port for delivering air-fuel mixture to said chambers as they expand in an intake phase and an exhaust port for exhausting said chambers as they contract in an exhaust phase, said rotor having apex seals with curved sealing edges biased outward to engage said peripheral wall and side seals biased outward to engage said side walls to seal said chambers from each other, said peripheral wall conforming in a peripherally extending low chamber pressure zone to the imaginary outer envelope of the sealing edges of said apex seals that would be deter.- mined on rotation of said rotor and shaft with said apex seals in identical radial positions on said rotor whereby said apex seals are not required to move substantially either inwardly or outwardly to maintain engagement with said low chamber pressure zone on rotor and shaft rotation, and said peripheral wall in a peripherally extending high chamber pressure zone deviating inwardly from said outer envelope to provide peripherally spaced leading and trailing wedge portions for simultaneously wedging the respective leading and trailing apex seals of each said chamber gradually inwardly throughout said high chamber pressure zone on rotor and shaft rotation whereby apex seal engagement with said peripheral wall is mechanically enforced by wedging action of said peripheral wall in said high chamber pressure zone.

2. A rotary engine comprising a housing having a twolobe internal peripheral wall and two oppositely facing side walls cooperatively defining a cavity, a shaft extending through said cavity and side walls and rotatably supported by said housing, said shaft having an eccentric located in said cavity, a three-lobe rotor located in said cavity and rotatably mounted on said eccentric of said shaft, means providing a 1:3 speed ratio between said rotor and said shaft, said rotor cooperating with said walls and said cavity to provide three chambers that are spaced about and move with said rotor while varying in volume in fixed relation to said walls as said rotor and said shaft rotate to provide intake, compression, expansion and exhaust phases, an intake port for delivery air-fuel mixture to said chambers as they expand in said intake phase and an exhaust port for exhausting said chambers as they contract in an exhaust phase, said rotor having apex seals with curved sealing edges biased outward to engage said peripheral wall and side seals biased outward to engage said side walls to seal said chambers from each other, said peripheral wall conforming in a peripherally extending low chamber pressure zone to the imaginary outer envelope of the sealing edges of said apex seals that would be determined on rotation of said rotor and shaft with said apex seals in identical radial positions on said rotor whereby said apex seals are not required to move substantially either inwardly or outwardly to maintain engagement with said low chamber pressure zone on rotor and shaft rotation during said intake and exhaust phases, and said peripheral wall in a peripherally extending high chamber pressure zone deviating inwardly from said imaginary outer envelope to provide peripherally spaced leading and trailing wedge portions of constant slope for simultaneously wedging the respective leading and trailing apex seals of each said chamber gradually inwardly in said high chamber pressure zone on rotor and shaft rotation whereby apex seal engagement with said peripheral wall is mechanically enforced by wedging action of said peripheral wall in said high chamber pressure zone during said compression and expansion phases.

3. A rotary engine comprising a housing having a two-lobe internal peripheral wall and two oppositely facing side walls cooperatively defining a cavity, a shaft extending through said cavity and side walls androtatably supported by said housing, said shaft having an eccentric located in said cavity, a three-lobe rotor located in said cavity and rotatably mounted on said eccentric of said shaft, means providing a 1:3 speed ratio between said rotor and said shaft, said rotor cooperating with said walls and said cavity to provide three chambers that are spaced about and move with said rotor while varying in volume in fixed relation to said walls as said rotor and said shaft rotate to provide intake, compression, expansion and exhaust phases, an intake port for delivery air-fuel mixture to said chambers as they expand in said intake phase and an exhaust port for exhausting said chambers as they contract in an exhaust phase, said rotor having apex seals with curved sealing edges biased outward to engage said peripheral wall and side seals biased outward to engage said side walls to seal said chambers from each other, said peripheral wall conforming in a peripherally extending low chamber pressure zone to the imaginary outer envelope of the sealing edges of said apex seals that would be determined on rotation of said rotor and shaft with said apex seals in identical radial positions on said rotor whereby said apex seals are not required to move substantially either inwardly or outwardly to maintain engagement with said low chamber pressure zone on rotor and shaft rotation during said intake and exhaust phases, and said peripheral wall in a peripherally extending high chamber pressure zone deviating inwardly from said imaginary outer envelope to provide peripherally spaced leading and trailing wedge portions of constant slope with accelerated rises from said outer envelope for simultaneously wedging the respective leading and trailing apex seals of each said chamber inwardly in said high chamber pressure zone at a fast rate over a short peripheral wall distance and then at a gradual rate over a long peripheral wall distance on rotor and shaft rotation whereby apex seal engagement with said peripheral wall is mechanically enforced by wedging action of said peripheral wall in said high chamber pressure zone during said compression and expansion phases.

4. A rotary engine comprising a housing having a two-lobe internal peripheral wall and two oppositely facing side walls cooperatively defining a cavity, a shaft extending through said cavity and side walls and rotatably supported by said housing, said shaft having an eccentric located in said cavity, a three-lobe rotor located in said cavity and rotatably mounted on said eccentric of said shaft, means providing a 1:3 speed ratio between said rotor and said shaft, said rotor cooperating with said walls and said cavity to provide three chambers that are spaced about and move with said rotor while varying in volume in fixed relation to said walls as said rotor and said shaft rotate to provide intake, compression, expansion and exhaust phases, an intake port for delivery air-fuel mixture to said chambers as they expand in said intake phase and an exhaust port for exhausting said chambers as they contract in an exhaust phase, said rotor having apex seals with curved sealing edges biased outward to engage said peripheral wall and side seals biased outward to engage said side walls to seal said chambers from each other, said peripheral wall conforming in a peripherally extending low chamber pressure zone to the imaginary outer envelope of the sealing edges of said apex seals that would be determined on rotation of said rotor and shaft with said apex seals in identical radial positions on said rotor whereby said apex seals are not required to move substantially either inwardly or outwardly to maintain engagement with said low chamber pressure zone on rotor and shaft rotation during said intake and exhaust phases, and said peripheral wall in a peripherally extending high chamber pressure zone deviating inwardly from said imaginary outer envelope to provide peripherally spaced leading and trailing wedge portions of constant slope with an accelerated rise from said outer envelope to said trailing wedge and an accelerated rise from said trailing wedge to said leading wedge for simultaneously wedging the respective leading and trailing apex seals of each said chamber inwardly in said high chamber pressure zone at a fast rate over a short peripheral wall distance and then at a gradual rate over a long peripheral wall distance on rotor and shaft rotation whereby apex seal engagement with said peripheral wall is mechanically enforced by wedging action of said peripheral wall in said high chamber pressure zone during said compression and expansion phases.

Claims

1. A rotary engine comprising a housing having a multi-lobe internal peripheral wall and two oppositely facing side walls cooperatively defining a cavity, a shaft extending through said cavity and side walls and rotatably supported by said housing, said shaft having an eccentric located in said cavity, a multilobe rotor located in said cavity and rotatably mounted on said eccentric of said shaft, means providing a fixed speed ratio between said rotor and said shaft, said rotor cooperating with said walls and said cavity to provide a plurality of chambers that are spaced about and move with said rotor while varying in volume in fixed relation to said walls as said rotor and said shaft rotate, an intake port for delivering air-fuel mixture to said chambers as they expand in an intake phase and an exhaust port for exhausting said chambers as they contract in an exhaust phase, said rotor having apex seals with curved sealing edges biased outward to engage said peripheral wall and side seals biased outward to engage said side walls to seal said chambers from each other, said peripheral wall conforming in a peripherally extending low chamber pressure zone to the imaginAry outer envelope of the sealing edges of said apex seals that would be determined on rotation of said rotor and shaft with said apex seals in identical radial positions on said rotor whereby said apex seals are not required to move substantially either inwardly or outwardly to maintain engagement with said low chamber pressure zone on rotor and shaft rotation, and said peripheral wall in a peripherally extending high chamber pressure zone deviating inwardly from said outer envelope to provide peripherally spaced leading and trailing wedge portions for simultaneously wedging the respective leading and trailing apex seals of each said chamber gradually inwardly throughout said high chamber pressure zone on rotor and shaft rotation whereby apex seal engagement with said peripheral wall is mechanically enforced by wedging action of said peripheral wall in said high chamber pressure zone.

2. A rotary engine comprising a housing having a two-lobe internal peripheral wall and two oppositely facing side walls cooperatively defining a cavity, a shaft extending through said cavity and side walls and rotatably supported by said housing, said shaft having an eccentric located in said cavity, a three-lobe rotor located in said cavity and rotatably mounted on said eccentric of said shaft, means providing a 1:3 speed ratio between said rotor and said shaft, said rotor cooperating with said walls and said cavity to provide three chambers that are spaced about and move with said rotor while varying in volume in fixed relation to said walls as said rotor and said shaft rotate to provide intake, compression, expansion and exhaust phases, an intake port for delivery air-fuel mixture to said chambers as they expand in said intake phase and an exhaust port for exhausting said chambers as they contract in an exhaust phase, said rotor having apex seals with curved sealing edges biased outward to engage said peripheral wall and side seals biased outward to engage said side walls to seal said chambers from each other, said peripheral wall conforming in a peripherally extending low chamber pressure zone to the imaginary outer envelope of the sealing edges of said apex seals that would be determined on rotation of said rotor and shaft with said apex seals in identical radial positions on said rotor whereby said apex seals are not required to move substantially either inwardly or outwardly to maintain engagement with said low chamber pressure zone on rotor and shaft rotation during said intake and exhaust phases, and said peripheral wall in a peripherally extending high chamber pressure zone deviating inwardly from said imaginary outer envelope to provide peripherally spaced leading and trailing wedge portions of constant slope for simultaneously wedging the respective leading and trailing apex seals of each said chamber gradually inwardly in said high chamber pressure zone on rotor and shaft rotation whereby apex seal engagement with said peripheral wall is mechanically enforced by wedging action of said peripheral wall in said high chamber pressure zone during said compression and expansion phases.

3. A rotary engine comprising a housing having a two-lobe internal peripheral wall and two oppositely facing side walls cooperatively defining a cavity, a shaft extending through said cavity and side walls and rotatably supported by said housing, said shaft having an eccentric located in said cavity, a three-lobe rotor located in said cavity and rotatably mounted on said eccentric of said shaft, means providing a 1:3 speed ratio between said rotor and said shaft, said rotor cooperating with said walls and said cavity to provide three chambers that are spaced about and move with said rotor while varying in volume in fixed relation to said walls as said rotor and said shaft rotate to provide intake, compression, expansion and exhaust phases, an intake port for delivery air-fuel mixture to said chambers as they expand in said intake phase and an exhaust port for exhausting said chambers as They contract in an exhaust phase, said rotor having apex seals with curved sealing edges biased outward to engage said peripheral wall and side seals biased outward to engage said side walls to seal said chambers from each other, said peripheral wall conforming in a peripherally extending low chamber pressure zone to the imaginary outer envelope of the sealing edges of said apex seals that would be determined on rotation of said rotor and shaft with said apex seals in identical radial positions on said rotor whereby said apex seals are not required to move substantially either inwardly or outwardly to maintain engagement with said low chamber pressure zone on rotor and shaft rotation during said intake and exhaust phases, and said peripheral wall in a peripherally extending high chamber pressure zone deviating inwardly from said imaginary outer envelope to provide peripherally spaced leading and trailing wedge portions of constant slope with accelerated rises from said outer envelope for simultaneously wedging the respective leading and trailing apex seals of each said chamber inwardly in said high chamber pressure zone at a fast rate over a short peripheral wall distance and then at a gradual rate over a long peripheral wall distance on rotor and shaft rotation whereby apex seal engagement with said peripheral wall is mechanically enforced by wedging action of said peripheral wall in said high chamber pressure zone during said compression and expansion phases.