Suction structure in fixed displacement piston type compressor

Abstract

A suction structure is provided for allowing refrigerant into a suction pressure region in a fixed displacement piston type compressor. The compressor includes a rotary valve. The suction structure includes a shifting device which shifts between a connecting state and a disconnecting state. The shifting device includes a valve body, a return spring, a first and a second displacement chambers, and a throttle passage. The return spring urges the valve body from a connecting position toward a disconnecting position. The volume of the first displacement chamber is displacable in accordance with an amount of a fluid inside therein. The volume of the second displacement is displaced. The fluid is filled in the first and the second displacement chambers. The throttle passage connects the first displacement chamber to the second displacement chamber. The fluid flows through the throttle passage when the volume of the first displacement chamber is displaced.

1 . A suction structure for allowing refrigerant into a suction pressure region in a fixed displacement piston type compressor, wherein cylinder bores for accommodating a respective piston are arranged around a rotary shaft, wherein a cam body is formed with the rotary shaft, wherein the piston is engaged with the cam body so that the rotation of the rotary shaft is transmitted to the piston, wherein a compression chamber is defined by the piston in the respective cylinder bore, wherein a rotary valve has a supply passage for introducing the refrigerant from the suction pressure region to the compression chamber, wherein the rotary valve is rotated integrally with the rotary shaft, the suction structure comprising:
 a shifting device for shifting between a connecting state and a disconnecting state, wherein in the connecting state the outlet of the supply passage is connected to the suction pressure region and in the disconnecting state the outlet of the supply passage is disconnected from the suction pressure region, the shifting device including;
 a valve body movable between a connecting position and a disconnecting position, wherein the connecting position corresponds to the connecting state and the disconnecting position corresponds to the disconnecting state; 
 a return spring urging the valve body from the connecting position toward the disconnecting position; 
 a first displacement chamber urging the valve body from the disconnecting position toward the connecting position, the volume of the first displacement chamber is displacable in accordance with an amount of a fluid inside therein; 
 a second displacement chamber of which the volume is displacable, wherein the fluid is filled in the first and the second displacement chambers; and
 a throttle passage connecting the first displacement chamber to the second displacement chamber, wherein the volume of the first displacement chamber is increased when the fluid flows from the second displacement chamber to the first displacement chamber through the throttle passage, and wherein the volume of the first displacement chamber is decreased when the fluid flows from the first displacement chamber to the second displacement chamber through the throttle passage. 
 
   
   
   
       2 . The suction structure according to  claim 1 , wherein the first displacement chamber is formed between a partition wall and a first chamber forming member which has a first movable portion, wherein the second displacement chamber is formed between the partition wall and a second chamber forming member which has a second movable portion, wherein the throttle passage is formed so as to extend through the partition wall, wherein the volume of the first displacement chamber is displaced in accordance with the position displacement of the first movable portion, wherein the volume of the second displacement chamber is displaced in accordance with the position displacement of the second movable portion. 
   
   
       3 . The suction structure according to  claim 2 , wherein the first chamber forming member is a first bellows connected to the partition wall, and the second chamber forming member is a second bellows connected to the partition wall, wherein the first movable portion is a first movable end of the first bellows, wherein the second movable portion is a second movable end of the second bellows. 
   
   
       4 . The suction structure according to  claim 3 , wherein the valve body is fixed to the movable end of the first bellows. 
   
   
       5 . The suction structure according to  claim 3 , wherein the stroke length of the first movable end of the first bellows is greater than that of the second movable end of the second bellows when the displacement of the first bellows is the same magnitude as that of the second bellows. 
   
   
       6 . The suction structure according to  claim 1 , wherein the fluid is a liquid. 
   
   
       7 . The suction structure according to  claim 1 , wherein the valve body is located at the disconnecting position for disconnecting an inlet of the supply passage from the suction pressure region in the compressor when the shifting device is in the disconnecting state. 
   
   
       8 . The suction structure according to  claim 1 , wherein the supply passage includes an inlet at an end surface of the rotary valve and an outlet at an circumferential surface of the rotary valve, wherein the supply passage includes an in-shaft passage extending in the direction of the rotary axis of the rotary shaft, wherein the outlet of the supply passage is formed so as to extend through the circumferential surface of the rotary shaft and is connected to the in-shaft passage, wherein the valve body is slidably fitted in the in-shaft passage in the direction of the rotary axis, wherein the valve body is moved in the direction of the rotary axis between the connecting position and the disconnecting position, wherein in the disconnecting position the valve body disconnects the outlet of the supply passage from the in-shaft passage. 
   
   
       9 . The suction structure according to  claim 1 , wherein the compressor includes a cylinder block in which the cylinder bores are formed, wherein a rear housing is connected to the cylinder block, wherein a suction chamber as the suction pressure region is formed in the rear housing, wherein the valve body is provided in the rear housing. 
   
   
       10 . The suction structure according to  claim 1 , wherein the rotary shaft is connected to an external drive source through a clutch. 
   
   
       11 . A fixed displacement piston type compressor comprising:
 pistons;   cylinder bores for accommodating the respective piston, wherein the cylinder bores are arranged around a rotary shaft;   a cam body formed with the rotary shaft, wherein the piston is engaged with the cam body so that the rotation of the rotary shaft is transmitted to the piston;   a compression chamber defined by the piston in the respective cylinder bore;   a rotary valve including a supply passage for introducing refrigerant from a suction pressure region in the compressor to the compression chamber, wherein the rotary valve is rotated integrally with the rotary shaft; and   a shifting device for shifting between a connecting state and a disconnecting state, wherein in the connecting state the outlet of the supply passage is connected to the suction pressure region and in the disconnecting state the outlet of the supply passage is disconnected from the suction pressure region, the shifting device including;
 a valve body movable between a connecting position and a disconnecting position, wherein the connecting position corresponds to the connecting state and the disconnecting position corresponds to the disconnecting state; 
 a return spring urging the valve body from the connecting position toward the disconnecting position; 
 a first displacement chamber urging the valve body from the disconnecting position toward the connecting position, the volume of the first displacement chamber is displacable in accordance with an amount of a fluid inside therein; 
 a second displacement chamber of which the volume is displacable, wherein the fluid is filled in the first and the second displacement chambers; and 
 a throttle passage connecting the first displacement chamber to the second displacement chamber, wherein the volume of the first displacement chamber is increased when the fluid flows from the second displacement chamber to the first displacement chamber through the throttle passage, and wherein the volume of the first displacement chamber is decreased when the fluid flows from the first displacement chamber to the second displacement chamber through the throttle passage.