PURPOSE: To aim at a sharp reduction in pump discharge noise by making the most forward front end of an actuating chamber port so as to be interconnected to a suction groove in the state that a specified predecompressing angle rotor has advanced from a first position equivalent to a top dead center position of a piston.
CONSTITUTION: A suction groove 9 and a discharge groove 10 make a piston 6 have a specified predecompressing angle ranging from the state that the piston 6 is most displaced to the side of a piston part 1 in an actuating chamber port 8 to a position where a rotational front end of this actuating chamber port 8 starts for interconnection with the suction groove 9. In addition, the same specified precompressive angle is formed in a gap with the position of a piston center shaft in a position where the rotational front end of the actuating chamber port 8 starts its interconnection with the discharge groove 10 from a bottom dead center position of the piston 6. With this constitution, a sudden variation of pressure in both suction and discharge starting positions will not occur at all.
SUZUKI MASAHIKO
MATSUI KAZUMA
NAGAI KOJI
ITO YOSHIAKI
| JP61080375B | ||||
| JPS61250387A | 1986-11-07 |