A rotary piston is eccentrically mounted in a housing and comprises chamber-defining means, which define a plurality of fluid-handling chambers with said housing. The chamber-defining means comprise sealing means in sealing surface contact with said housing to seal said fluid-handling chambers from each other. The sealing means are arranged to derive from the pressure of fluid in said fluid-handling chambers and from the centrifugal force which is due to the rotation of said rotary piston a first force urging said sealing means against said housing. The chamber-defining means further comprise force-deriving means for deriving from said pressure of fluid in said fluid-handling chambers a second force which throughout the revolution of said rotary piston is smaller than and opposes said first force. The housing is formed with first and second fluid ports, which are peripherally spaced apart and each of which is adapted to connect each of said fluid-handling chambers to the outside of said housing once during each revolution of said piston.
A rotary machine apex seal arrangement having a pair of seal members that are pivotally mounted on a pin on the machine's rotor and are biased by chamber pressure, centrifugal force and a compression spring therebetween to contact the machine's internal peripheral wall to provide leading and trailing seals.
