Double- headed piston type swash plate compressor

Abstract

A double-headed piston type swash plate compressor includes a rotation shaft, a housing, a swash plate, two cylinder bores, a double-headed piston, and two shoes. The double-headed piston includes two shoe holders, a neck, two heads, and two coupling portions. At least one of the two coupling portions includes a load receiving portion. The load receiving portion is configured to receive bending load that is applied from the swash plate to the double-headed piston and acts toward an inner side in the radial direction. The load receiving portion is separated from the wall surface of the cylinder bore when load applied to the double-headed piston is less than a specific threshold value. The load receiving portion abuts against the inner wall of the cylinder bore and receives the bending load when the load applied to the double-headed piston is greater than the specific threshold value.

1 . A double-headed piston type swash plate compressor comprising:
 a rotation shaft extending in an axial direction and a radial direction;   a housing that accommodates the rotation shaft;   a swash plate that rotates when the rotation shaft rotates;   two cylinder bores located in the housing at an outer side of the rotation shaft in the radial direction;   a double-headed piston that reciprocates in the two cylinder bores; and   two shoes that couple the double-headed piston to the swash plate, wherein   the two cylinder bores and the double-headed piston define two compression chambers,   rotation of the swash plate reciprocates the double-headed piston in the two cylinder bores and compresses fluid in each of the compression chambers,   the double-headed piston includes:
 two shoe holders that hold the two shoes, wherein the two shoe holders are opposed to each other in an axial direction of the double-headed piston; 
 a neck that couples the two shoe holders, wherein the neck is located at an outer circumferential side of the swash plate and deformable in the radial direction; 
 two heads respectively located at two ends of the double-headed piston in the axial direction of the double-headed piston, wherein each of the two heads includes a side surface opposing a wall surface of the cylinder bore; and 
 two coupling portions that couple the two shoe holders and the two heads, respectively, 
   at least one of the two coupling portions includes a load receiving portion located between the corresponding head and the corresponding shoe holder as viewed in the radial direction, wherein the load receiving portion is configured to receive bending load that is applied from the swash plate to the double-headed piston and acts toward an inner side in the radial direction,   the load receiving portion is separated from the wall surface of the cylinder bore when load applied to the double-headed piston is less than a specific threshold value, and   the load receiving portion abuts against the inner wall of the cylinder bore and receives the bending load when the load applied to the double-headed piston is greater than the specific threshold value.   
     
     
         2 . The double-headed piston type swash plate compressor according to  claim 1 , wherein
 each of the two coupling portions includes:
 an outer portion extending in the axial direction of the double-headed piston; and 
 an inner portion located at the inner side of the outer portion in the radial direction and extended from the head in the axial direction of the double-headed piston, 
   the inner portion includes an inner surface opposing the wall surface of the cylinder bore in the radial direction,   the inner surface and the side surface of the head form a step so that the inner surface is farther from the wall surface of the cylinder bore than the side surface of the head, and   the load receiving portion is an end of the inner portion near the corresponding shoe holder.   
     
     
         3 . The double-headed piston type swash plate compressor according to  claim 2 ,
 when referring to a direction orthogonal to both of the axial direction and an opposing direction of the inner portion and the outer portion as a widthwise direction,   the inner portion includes a fixed-width portion having a fixed width, and   the end of the inner portion near the corresponding shoe holder is wider than the fixed-width portion.   
     
     
         4 . The double-headed piston type swash plate compressor according to  claim 1 , wherein
 the cylinder bore includes oil and an oil collection region located between the load receiving portion and the corresponding head; and   the oil enters the oil collection region when load applied to the double-headed piston is greater than the threshold value.   
     
     
         5 . The double-headed piston type swash plate compressor according to  claim 1 ,
 each of the two coupling portions includes the load receiving portion,   when the double-headed piston reciprocates from a first position to a second position,   a first one of the load receiving portions that is included in a first one of the two coupling portions opposes the wall surface of the cylinder bore when the double-headed piston is located at the first position, and   a second one of the load receiving portions that is included in a second one of the two coupling portions opposes the wall surface of the cylinder bore when the double-headed piston is located at the second position.   
     
     
         6 . The double-headed piston type swash plate compressor according to  claim 1 , further comprising an actuator that changes an inclination angle of the swash plate, wherein
 the actuator includes:   a movable body that is movable in the axial direction of the rotation shaft; and   a partition that defines a control chamber in cooperation with the movable body, and   the actuator is operable to change an inclination angle of the swash plate when the movable body is moved in accordance with pressure of the control chamber.   
     
     
         7 . The double-headed piston type swash plate compressor according to  claim 6 , wherein
 the two heads include a first head and a second head, and   the second head has a smaller diameter than a diameter of the first head.