Variable delivery compressor

A variable delivery compressor adapted for use in compressing a refrigerant gas of an air-conditioning circuit of a vehicle comprising:

• cylinder block means having therein a plurality of compression chambers in which reciprocatory compression pistons are received, respectively;
• housing means having therein a suction chamber from which the refrigerant gas before compression is sucked into the plurality of compression chambers and a delivery chamber into which the compressed refrigerant gas is delivered from the compression chambers;
• a valve plate arranged between said cylinder block means and said housing means, and having therein suction ports providing a fluid communication between respective said compression chambers and said suction chamber and delivery ports providing a fluid communication between respective said compression chambers and said delivery chamber;
• a suction flange element attached to said cylinder block means, for introducing said refrigerant gas before compression from said air-conditioning circuit into said suction chamber;
• a delivery flange element attached to said cylinder block, for delivering said compressed refrigerant gas from said delivery chamber to said air-conditioning circuit;
• delivery valve means for closing said delivery ports that provide a fluid communication between said plurality of compression chambers and said delivery chamber, said delivery valve means being opened by said compressed refrigerant gas when delivered from the compression chambers into said delivery chamber;
• suction valve means for closing said suction ports that provide a fluid communication between said plurality of compression chambers and said suction chamber, and capable of being opened by said refrigerant gas sucked from the suction chamber into respective said compression chambers;
• movable means arranged in said suction chamber and adapted for movement toward and away from said suction valve means, said movable means including a spool element axially slidably mounted in a pressure chamber defined by inner wall means projected inside said housing means;
• valve pressing means held by said movable means so as to be moved together with said movable means and adapted for forcibly displacing a predetermined part of said suction valve means from a first position for closing said suction ports of said valve plate to a second position for opening said suction ports when said valve pressing means are moved toward said suction valve means, said valve pressing means including a valve pressing plate attached to an axially inner end of said spool element, and a plurality of valve pressing tongues connected to said valve pressing plate, each said valve pressing tongue being axially extended toward said suction valve means so as to be engaged with said suction valve means when said spool element is moved toward said suction valve means, and respective said plurality of valve pressing tongues having axial lengths different from one another;
• means for permitting said predetermined part of said suction valve means which has been forcibly opened by said valve pressing means to return to said first position from said second position in response to movement of said compression pistons toward top dead centers thereof;
• a control unit for providing a control signal indicating that a change in a delivery amount of said compressor is needed in response to a change in a cooling load applied to said air-conditioning circuity, and;
• means for actuating movement of said movable means toward said suction valve means upon being energized by said control signal of said control unit, said actuating means including a screw element threadedly engaged with said movable means, and a drive motor connected to said screw element for providing said screw element with a rotation, via a rotation transmitting mechanism, said drive motor being connected to said control unit so that said drive motor is operated by said control signal of said control unit, said rotation of said screw element causing axial movement of said movable means.