Gerotor type motor with pressure biased rotary valve

Claim 1

A gerotor type rotary piston machine comprising a casing having a main axis, expansible chamber means having cyclically movable chamber forming means, rotatable shaft means connected to said chamber forming means, an annularly shaped valve mounted in said casing for rotation about said main axis, said valve being in surrounding relation to said shaft between the opposite ends thereof, fluid passages in said casing between said valve and said expansible chamber means, drive means connecting said rotatable shaft means and said valve in driving relation, said valve having first and second sets of circumferentially extending and alternately arranged inlet and outlet ports cooperable with said Casing passages, said second set of valve ports being spaced from the inner and outer circumferences of said valve, an annularly shaped pressure plate in abutting engagement with said valve, said pressure plate being rotationally fixed relative to said casing and axially movable relative to said valve, said pressure plate having first and second fluid passage means having fluid communication with said first and second sets of valve ports, said second fluid passage means being spaced from the inner and outer circumferences of said pressure plate, first and second annularly shaped channels in said casing having respectively fluid communication with said first and second pressure plate fluid passage means, said second annularly shaped channel having the mouth thereof in radial registration with said second fluid passage means, said pressure plate having first and second surface portions respectively radially inwardly of said first and second annular channels with at least one of said surface portions being subjected to pressurized fluid in either of said annular channels to axially bias said pressure plate into abutting engagement with said valve.