| 摘要 |
The back pressure valve (46) has a shaft-mounted piston (81) reciprocally disposed on the axis of a valve inlet opening (91) such that increased pressure from within the motor casing (16) of a centrifugal compressor (13) causes the piston (81) to move in the direction of the refrigerant flow, against a biasing means (82), to increase the flow of refrigerant through the opening (91), and to thereby regulate the pressure drop across said valve (46) to a predetermined level. The shaft (79) has an extended portion projecting through the piston (81) toward the motor casing (16) such that when the compressor (13) is shut down and the pressure is thus greater in the valve (46) than in the motor casing (16), the piston (81) can move out of the inlet opening (91) to the extended portion of the shaft (79) to thereby allow the unrestricted flow of refrigerant into the motor casing (16). <IMAGE> <IMAGE> |
