Rotary engine with modified trochoidally shaped inner wall

In a machine of the character described, wherein a rotor having circumferentially spaced apexes is journalled on an eccentric portion of a rotor shaft rotatably mounted in a housing that has an inner peripheral wall surface of basically trochoidal shape with a plurality of lobes, radiating from a common center, said lobes being one less in number than the number of rotor apexes, and each lobe being symmetrical about a center line radiating from said common center and being separated by a cusp from its next adjacent lobe in the direction of rotor rotation, the apexes of the rotor coacting with said inner peripheral wall to define a plurality of discrete working chambers that vary in volume as rotation of the rotor about the shaft orbitally moves the apex seals along said inner peripheral wall surface, said discrete chambers being sealed from one another by means including apex seals that occupy transverse slots in the apexes of the rotor so that pressure differentials in the chambers flanking the apex seals and manifested in the slots force the apex seals against said inner peripheral wall surface of the housing and also against a side of the slots they occupy, the pressure differential at opposite sides of each apex seal varying as the seal traverses the inner peripheral wall surface of each lobe, increasing significantly as the seal moves through the lobe, customarily identified as the compression lobe when the machine is a rotary engine, to reach maximum at a location approximately two-thirds the circumferential distance from a point at which the centerline of that lobe intersects said surface to the cusp dividing that lobe from its next adjacent lobe, then diminishing from said location as the apex seal crosses the cusp and again increasing and diminishing as the seal traverses the next adjacent lobe, the improvement by which

• scoring of said inner peripheral wall surface of the housing by the forced engagement therewith of the apex seals is significantly minimized,
• and which improvement resides in:
• means to effect outward stroking of each apex seal in the slot it occupies as the seal traverses said identified lobe,
• the magnitude of said outward stroking reaching its maximum at a point beyond the location at which the differential in pressure at opposite sides of the seal is greatest,
• the means for effecting said outward stroking of the apex seals residing in an outward displacement of the inner peripheral wall surface of said identified lobe from an imaginary path that would be traced by the sealing edges of the apex seals upon rotation of the rotor and the shaft if said seals remained in identical positions with respect to the rotor axis and neither stroked inward nor outward,
• said outward displacement of the inner peripheral wall surface from said imaginary path commencing substantially at the point said surface is intersected by the centerline of said identified lobe and gradually increasing in magnitude from said point to reach maximum at a point beyond the location on the orbit of the apex seals at which the pressure differential at opposite sides thereof is greatest, and from said point of maximum outward displacement gradually decreasing in magnitude but continuing across said cusp into the next adjacent lobe, and then merging gently with the aforesaid imaginary path.