Control valve for variable displacement compressors

A control valve for controlling the displacement of a variable displacement type compressor, wherein the compressor includes a crank chamber, a suction pressure zone, the pressure of which is suction pressure, a discharge pressure zone, the pressure of which is discharge pressure, a bleed passage for releasing gas from the crank chamber to the suction pressure zone, and a supply passage for supplying gas from the discharge pressure zone to the crank chamber, the control valve comprising:

• a valve housing;
• a supply side valve for controlling the opening degree of the supply passage;
• a transmission rod extending in the valve housing, wherein the transmission rod moves axially and has a distal end portion and a proximal end portion;
• a relief side valve for controlling the opening degree of the bleed passage, wherein the transmission rod connects the relief side valve with the supply side valve, the relief side valve including:
• a passage chamber constituting part of the bleed passage;
• a valve seat for defining part of the passage chamber;
• and
• a relief side valve body that contacts the valve seat, the relief side valve body being located in the passage chamber, wherein, when the relief side valve body contacts the valve seat, the passage chamber is separated into a first area, which is connected to the crank chamber via an upstream part of the bleed passage, and a second area, which is connected to the suction pressure zone via a downstream part of the bleed passage, wherein the distal end portion of the transmission rod is accommodated in the second area;
• a solenoid for urging the transmission rod in a direction to move the relief side valve body away from the valve seat with a force in accordance with an external signal, wherein the solenoid has an area for accommodating the proximal end portion, and wherein the pressure in the crank chamber is applied to the area;
• and
• a pressure sensing member located in the first area and moving the relief side valve body in accordance with the pressure in the first area, wherein the cross sectional area of the passage chamber that is sealed by the relief side valve body is substantially equal to a sum of the effective pressure receiving area of the pressure sensing member and an effective pressure receiving area of the proximal end portion.

A control valve for controlling the displacement of a variable displacement type compressor, wherein the compressor includes a crank chamber, a suction pressure zone, the pressure of which is suction pressure, a discharge pressure zone, the pressure of which is discharge pressure, a bleed passage for releasing gas from the crank chamber to the suction pressure zone, and a supply passage for supplying gas from the discharge pressure zone to the crank chamber, the control valve comprising:

• a valve housing;
• a transmission rod extending in the valve housing, wherein the transmission rod moves axially and has a distal end portion and a proximal end portion;
• a solenoid located nearby in the proximal end portion of the transmission rod, wherein the solenoid urges the transmission rod in axial direction with a force in accordance with the electric current supplied to the solenoid, wherein the solenoid has an area for accommodating the proximal end portion, and wherein the pressure in the crank chamber is applied to the area;
• a supply side valve for controlling the opening degree of the supply passage, wherein the supply side valve includes a guide passage that constitutes a part of the supply passage and a supply side valve body formed on the transmission rod to enter in the guide passage, wherein the solenoid moves the transmission rod such that the supply side valve body is selectively entered and moved away to the guide passage;
• a relief side valve for controlling the opening degree of the bleed passage, wherein the transmission rod connects the relief side valve portion with the supply side valve portion, the relief side valve portion including:
• a passage chamber constituting part of the bleed passage;
• a valve seat for defining part of the passage chamber;
• and
• a relief side valve body that contacts the valve seat, the relief side valve body being located in the passage chamber, wherein, when the relief side valve body contacts the valve seat, the passage chamber is separated into a first area, which is connected to the crank chamber via an upstream part of the bleed passage, and a second area, which is connected to the suction pressure zone via a downstream part of the bleed passage;
• and
• a pressure sensing member located in the first area and moving the relief side valve body in accordance with the pressure in the first area, wherein the cross sectional area of the passage chamber that is sealed by the relief side valve body is substantially equal to a sum of the effective pressure receiving area of the pressure sensing member and an effective pressure receiving area of the proximal end portion.