Variable displacement engine

Claim 1

IN A VARIABLE DISPLACEMENT VANE ENGINE OF THE DOUBLE LOBE BALANCED TYPE, INCLUDING A HOUSING, A ROTOR FORMED WITH A PLURALITY OF CIRCUMFERENTIALLY-SPACED VANE SLOTS FOR RECEIVING A PLURALITY OF SLIDING VANES, STATIONARY VALVE MEANS LOCATED ADJACENT AT LEAST ONE END OF THE ROTOR AND CONTAINING CIRCUMFERENTIALLY-SPACED INLET AND DISCHARGE PORTS THAT LIE IN PLANES NORMAL TO THE AXIS OF THE ROTOR AND ARE POSITIONED RADIALLY TO REGISTER WITH THE INTERVANE SPACES, THERE BEING TWO DIAMETRICALLY-OPPOSED INLET PORTS AND TWO DIAMETRICALLY-OPPOSED DISCHARGE PORTS AND ADJACENT PORTS BEING SPACED FROM EACH OTHER A DISTANCE NOT LESS THAN THE INTERVANE INTERVAL, AND A CAM RING ENCIRCLING THE ROTOR AND HAVING A CAM SURFACE WHICH ENGAGES THE OUTER ENDS OF THE VANES, THE CAM RING BEING MOUNTED IN THE HOUSING FOR SUBSTANTIAL ROTATIONAL ADJUSTMENT ABOUT THE AXIS OF THE ROTOR BETWEEN MINIMUM AND MAXIMUM DISPLACEMENT ESTABLISHING POSITIONS, THE IMPROVEMENT WHICH COMPRISES A CYLINDRICAL CAM SURFACE ON THE CAM RING WHICH IN TRANSVERSE CROSS-SECTION IS DEFINED BY TWO DIAMETRICALLY-OPPOSED TRUE CIRCULAR ARCS WHICH ARE CENTERED ON THE AXIS OF THE ROTOR, TWO DIAMETRICALLY-OPPOSED ECCENTRIC CIRCULAR ARCS WHICH ARE CENTERED AT POINTS DISPLACED IN OPPOSITE DIRECTIONS FROM THE AXIS OF THE ROTOR, THE DISTANCE FROM THE AXIS OF THE ROTOR TO ANY POINT ON EACH OF THESE ARCS BEING GREATER THAN THE RADIUS OF THE TRUE CIRCULAR ARCS, AND FOUR BLEND CURVES JOINING THE ADJACENT ENDS OF THE FOUR ARCS, THE LENGTHS OF THE ARCS