Sealing structure for rotary valves

A sealing structure for a rotary valve, comprising:

• a rotary member provided with a plurality of pockets opening toward the outer periphery of said rotary member;
• a casing enclosing the outer periphery of said rotary member;
• sealing members provided between the outer periphery of said rotary member and the inner periphery of said casing;
• said sealing members being formed to be adjustably projectable in the radial direction;
• radial blades partitioning and separating said plurality of pockets provided in said rotary member;
• cavities in the outer tips of said blades;
• said sealing members being slidably fitted in said cavities to be pressed to project outwardly in the radial direction of said rotary member;
• a first passage provided in the axial direction in the center portion of said rotary member;
• a plurality of auxiliary passages within each said radial blade communicating with said first passage, and communicating with said sealing member containing cavities;
• means for supplying, from outside, fluid under pressure to said first passage;
• piston-shaped pushing members, each fitted at least partially in each said auxiliary passage, for projecting said sealing members radially outwardly in response to fluid pressure in said first passage;
• and
• said piston-shaped pushing members being pressed so as to slide radially outwardly by said fluid pressure in said first passage so as to bear against and project said sealing members radially outwardly.