VARIABLE DELIVERY PUMP

PURPOSE:To make the discharging capacity of a compressor variable without enlarging the size of the compressor by providing a by-pass passage between a minor discharge chamber and a suction chamber and by making the discharging capacity of the compressor variable in accordance with the open/close of this passage. CONSTITUTION:Rotation of a shaft gives a piston, through driving members, the reciprocating motion force with which the piston performs reciprocating motion in a cylinder. With this motion, the coolant is supplied from a suction chamber 35 to each cylinder via minor suction chambers 22 to 24 and returns to a discharge chamber 30 via minor discharge chambers 22 to 24. When the air conditioning load is large, by- pass valves 42 and 43 close by-pass passages 40 and 41 located between the suction chamber 35 and the minor discharge chambers, while, when the air conditioning load is small, a lead wire 68 is electrified to get a valve disc 48 apart from a by-pass opening 46. Thus the by-pass passages 40 and 41 are opened to lower the pressure in the minor discharge chambers, and discharge connecting openings 26 and 28 are closed by check valves 71 and 72. Accordingly, so far as the function of the compressor concerns, only the coolant discharged from the passages 40 and 41 to the minor discharge chamber 23 is discharged from the discharge chamber 30.