Suction structure in double-headed piston type compressor

Abstract

A suction structure is provided for allowing refrigerant into first and second compression chambers from a suction pressure region through first and second rotary valves and first and second communication passages in a double-headed piston type compressor. The first and the second rotary valves respectively have first and second introduction passages. The distance to the first communication passage from the suction pressure region through the first introduction passage is greater than the distance to the second communication passage from the suction pressure region through the second introduction passage. The first communication passage with a circular cross-section in the cylinder block connects the first compression chamber to the first introduction passage. The second communication passage with a circular cross-section in the cylinder block connects the second compression chamber to the second introduction passage. The diameter of the first communication passage is greater than the diameter of the second communication passage.

1 . A suction structure for allowing refrigerant from a suction pressure region in a double-headed piston type compressor, the compressor comprising:
 a cylinder block;   a rotary shaft supported by the cylinder block;   a double-headed piston reciprocating with rotation of the rotary shaft;   a first cylinder bore and a second cylinder bore formed in the cylinder block in a paired manner so as to accommodate the double-headed piston;   a first compression chamber and a second compression chamber defined by the double-headed piston in the first and the second cylinder bores, respectively;   the suction structure in the compressor comprising:   a first rotary valve introducing refrigerant from the suction pressure region into the first compression chamber through a first introduction passage;   a second rotary valve introducing refrigerant from the suction pressure region into the second compression chamber through a second introduction passage, wherein each part of the first and the second introduction passages is formed in the rotary shaft;   a first communication passage having a circular cross-section and formed in the cylinder block so as to connect the first compression chamber to the first introduction passage; and   a second communication passage having a circular cross-section and formed in the cylinder block so as to connect the second compression chamber to the second introduction passage, wherein the distance to the first communication passage from the suction pressure region through the first introduction passage is greater than the distance to the second communication passage from the suction pressure region through the second introduction passage, wherein the diameter of the first communication passage is greater than the diameter of the second communication passage.   
   
   
       2 . The suction structure according to  claim 1 , wherein the diameter of the first communication passage is less than or equal to 1.8 times of the diameter of the second communication passage. 
   
   
       3 . The suction structure according to  claim 2 , wherein the diameter of the first communication passage is less than or equal to 1.4 times of the diameter of the second communication passage. 
   
   
       4 . The suction structure according to  claim 1 , wherein the second introduction passage in the rotary shaft shares a part of the first introduction passage. 
   
   
       5 . A double-headed piston type compressor comprising:
 a cylinder block;   a rotary shaft supported by the cylinder block;   a cam body formed with the rotary shaft;   a double-headed piston engaged with the cam body, wherein rotation of the rotary shaft is transmitted to the piston through the cam body;   a first cylinder bore and a second cylinder bore formed in the cylinder block in a paired manner so as to accommodate the double-headed piston;   a first compression chamber and a second compression chamber defined by the double-headed piston in the first and the second cylinder bores, respectively;   a first rotary valve rotated integrally with the rotary shaft, wherein the rotary valve has a first introduction passage so as to introduce refrigerant from a suction pressure region into the first compression chamber through the first introduction passage;   a second rotary valve rotated integrally with the rotary shaft, wherein the second rotary valve has a second introduction passage so as to introduce refrigerant from the suction pressure region into the second compression chamber through the second introduction passage, wherein each part of the first and second introduction passages is formed in the rotary shaft;   a first communication passage having a circular cross-section and formed in the cylinder block so as to connect the first compression chamber to the first introduction passage; and   a second communication passage having a circular cross-section and formed in the cylinder block so as to connect the second compression chamber to the second introduction passage, wherein the distance to the first communication passage from the suction pressure region through the first introduction passage is greater than the distance to the second communication passage from the suction pressure region through the second introduction passage, wherein the diameter of the first communication passage is greater than the diameter of the second communication passage.