Rotary air pump or compressor with flexible end sealing plates

In combination with a rotary air pump or compressor comprising:

• a stator housing having a cylindrical inner wall;
• a pair of end heads mounted on the opposite ends of said stator housing to form a cylindrical pump cavity, each of said end heads being provided at its inner wall with a circular recess corresponding with the cylindrical inner wall of said stator housing;
• a drive shaft eccentrically journalled on at least one of said end heads and extending in the interior of the pump cavity;
• a rotor mounted on said drive shaft within the pump cavity and co-operating with the cylindrical inner wall of said stator housing to form suction, compression and delivery chambers;
• and
• a pair of flexible diaphragm type sealing plates clamped at their outer peripheries between the opposite ends of said stator housing and said end heads to form a pair of pressure chambers within the respective recess of said end heads, said sealing plates being pressed against the opposite end faces of said rotor due to pressure differences between the pump cavity and the pressure chambers to provide end-face sealing contacts;
• the improvement wherein each of said sealing plates comprises a flat peripheral flange portion clamped between the end faces of said stator housing and said end head and a substantially cone shaped portion protruding inwardly from said flat flange portion to be pressed upon assembly onto the end face of said rotor and substantially coinciding at its apex with the axis of said rotor, the height of said cone shaped portion from the inner surface of said flat flange portion being determined in a range of ##EQU3##