Patent ID: 6126406
Filing Date: 2000-10-03
Classification: F04B

Abstract:
A compressor including a housing having a cylinder bore and a crank chamber, a drive plate located in the crank chamber and mounted on a rotary shaft, and a piston operably coupled to the drive plate and located in the cylinder bore, wherein the drive plate converts rotation of the rotary shaft to reciprocating movement of the piston, wherein the piston compresses gas supplied to the cylinder bore from an external circuit by way of a suction chamber and discharges the compressed gas from the cylinder bore to the external circuit by way of a discharge chamber, wherein the drive plate is tiltable with respect to the rotary shaft responsive to a difference between the pressure in the crank chamber and the pressure in the cylinder bore, the piston having a stroke based on the inclination of the drive plate to control the displacement of the compressor, the compressor further comprising:a shutter chamber defined in the housing and having an elongated, cylindrically shaped inner peripheral wall and a rear end wall at one end of the inner peripheral wall, the rear end wall being provided with an opening to communicate the external circuit with the suction chamber through the shutter chamber;a shutter member slidably accommodated in the shutter chamber, wherein the shutter member is reciprocally movable between a first position and a second position in response to the tilting motion of the drive plate, wherein the shutter member has a large diameter portion supported by the inner peripheral wall of the shutter chamber and a small diameter portion extending from the large diameter portion and radially spaced away from the inner peripheral wall of the shutter chamber, the small diameter portion having a rear end which opens said opening in the rear end wall of the shutter chamber to provide flow communication between the external circuit and the suction chamber when the shutter member is in the first position and closes the opening to disconnect the external circuit from the suction chamber when the shutter member is in the second position, and wherein the shutter member has a step defined by the conjunction between said large and small diameter portions, the step facing toward but spaced away from the rear end wall of the shutter chamber when the shutter member is in its said first and second positions; anda coil spring located in the shutter chamber to bias the shutter member in a direction toward the first position and away from the second position, wherein the coil spring has a longitudinal axis, a first end in engagement with the step of the shutter member and a second end in engagement with the rear end wall of the shutter chamber, the first end of the coil spring having an inner diameter substantially equal to the diameter of the small diameter portion of the shutter member, and wherein the coil spring is spaced radially away from the inner peripheral wall of the shutter chamber along substantially all of the spring's axial length to prevent the coil spring from sliding against the inner peripheral wall of the shutter chamber while the coil spring is being expanded or compressed during the movement of the shutter member alternately between its said first and second positions.