Compressor Having Capacity Modulation System

Abstract

A compressor may include first and second scrolls and a capacity-modulation system. The first and second scrolls include first and second end plates and first and second spiral wraps. The second end plate may define a suction inlet, a discharge passage, a modulation port, and a vent passage. The capacity-modulation system may include a control valve and a piston. The control valve is movable between first and second positions. The piston may be disposed within a recess in the second end plate and is movable between an open position in which communication between the modulation port and the vent passage is allowed and a closed position in which communication between the modulation port and the vent passage is prevented. Moving the control valve to the first position moves the piston to the closed position. Moving the control valve to the second position moves the piston to the open position.

What is claimed is: 
     
         1 . A compressor comprising:
 a first scroll having a first end plate and a first spiral wrap extending from the first end plate;   a second scroll having a second end plate and a second spiral wrap extending from the second end plate, wherein the first and second spiral wraps cooperate to define a plurality of fluid pockets, wherein during operation of the compressor, the fluid pockets move from a radially outer position to radially intermediate positions to a radially inner position, wherein the second end plate includes a modulation port and a vent passage, wherein the modulation port is in fluid communication with one of the fluid pockets at one of the radially intermediate positions, and wherein the vent passage is in fluid communication with the modulation port and a suction-pressure region; and   a capacity-modulation system operable in a high-capacity mode and a low-capacity mode, the capacity-modulation system including a control valve and a piston,   wherein:
 the control valve is movable between a first position and a second position, 
 the piston is movable between an open position in which fluid communication between the modulation port and the vent passage is allowed and a closed position in which fluid communication between the modulation port and the vent passage is prevented, 
 movement of the control valve between the first and second positions causes movement of the piston between the open and closed positions, 
 the piston is movably disposed within a first recess that extends into the second end plate, wherein the piston seats against a surface of the second end plate in the closed position, and 
 at least one of the piston and the surface of the second end plate includes a second recess that decreases a surface area of contact between the piston and the surface of the second end plate. 
   
     
     
         2 . The compressor of  claim 1 , wherein the second recess is formed in the piston and is in fluid communication with the modulation port. 
     
     
         3 . The compressor of  claim 1 , wherein the second recess is in fluid communication with the vent passage. 
     
     
         4 . The compressor of  claim 3 , wherein the suction-pressure region is a suction inlet defined by the second scroll, and wherein the vent passage extends from the suction inlet. 
     
     
         5 . The compressor of  claim 1 , wherein the control valve selectively allows intermediate-pressure working fluid to flow into an actuation chamber defined by the piston and the second end plate, and wherein the intermediate-pressure working fluid is at a pressure higher than a suction pressure and less than a discharge pressure. 
     
     
         6 . The compressor of  claim 5 , wherein the second end plate includes a first portion and a second portion that is attached to the first portion by fasteners. 
     
     
         7 . The compressor of  claim 6 , wherein the second portion of the second end plate defines the first recess and cooperates with the piston to define the actuation chamber. 
     
     
         8 . The compressor of  claim 7 , wherein the second recess is formed in the first portion of the second end plate. 
     
     
         9 . The compressor of  claim 8 , wherein:
 the control valve includes a body, a housing, and a valve member,   the body is received in a valve passage in the second portion of the second end plate,   the housing is fixed relative to the second end plate and the body, and   the valve member is disposed within the housing and is movable therein between the first and second positions.   
     
     
         10 . The compressor of  claim 9 , wherein the body includes a first passage, a second passage, and a third passage. 
     
     
         11 . The compressor of  claim 10 , wherein the housing includes an aperture in fluid communication with a suction chamber of the compressor, and wherein movement of the valve member controls fluid communication between the first passage and the aperture. 
     
     
         12 . A compressor comprising:
 a first scroll having a first end plate and a first spiral wrap extending from the first end plate;   a second scroll having a second end plate and a second spiral wrap extending from the second end plate, wherein the first and second spiral wraps cooperate to define a plurality of fluid pockets, and wherein during operation of the compressor, the fluid pockets move from a radially outer position to radially intermediate positions to a radially inner position; and   a capacity-modulation system including a control valve and a piston,   wherein:
 the second end plate includes a first portion and a second portion that is attached to the first portion by fasteners, 
 the second end plate includes a modulation port and a vent passage, wherein the modulation port is in fluid communication with one of the fluid pockets at one of the radially intermediate positions, wherein the modulation port is disposed in the first portion of the second end plate, and wherein the vent passage is in fluid communication with the modulation port and a suction-pressure region, 
 the piston is movable between an open position in which fluid communication between the modulation port and the vent passage is allowed and a closed position in which fluid communication between the modulation port and the vent passage is prevented, 
 movement of the control valve between a first position and a second position causes movement of the piston between the open and closed positions, 
 the piston is movably disposed within a first recess that extends into the second portion of the second end plate, wherein the piston seats against a surface of the first portion of the second end plate in the closed position, 
 at least one of the piston and the surface of the first portion of the second end plate includes a second recess that decreases a surface area of contact between the piston and the surface of the second end plate, and 
 the second portion of the second end plate defines the first recess and cooperates with the piston to define an actuation chamber. 
   
     
     
         13 . The compressor of  claim 12 , wherein the second recess is formed in the piston and is in fluid communication with the modulation port. 
     
     
         14 . The compressor of  claim 12 , wherein the second recess is in fluid communication with the vent passage. 
     
     
         15 . The compressor of  claim 14 , wherein the suction-pressure region is a suction inlet defined by the second scroll, and wherein the vent passage extends from the suction inlet. 
     
     
         16 . The compressor of  claim 12 , wherein:
 the control valve includes a body, a housing, and a valve member,   the body is received in a valve passage in the second portion of the second end plate,   the housing is fixed relative to the second end plate and the body, and   the valve member is disposed within the housing and is movable therein between the first and second positions.   
     
     
         17 . The compressor of  claim 16 , wherein the body includes a first passage, a second passage, and a third passage. 
     
     
         18 . The compressor of  claim 17 , wherein the housing includes an aperture in fluid communication with a suction chamber of the compressor, and wherein movement of the valve member controls fluid communication between the first passage and the aperture. 
     
     
         19 . The compressor of  claim 18 , wherein the housing is fixed relative to the second end plate and the body, and wherein the valve member includes a stem portion that is movably received in the first passage of the body. 
     
     
         20 . The compressor of  claim 19 , wherein the first passage of the body is in fluid communication with the actuation chamber, wherein the first passage of the body is in selective fluid communication with an axial biasing chamber containing intermediate-pressure working fluid, and wherein the first passage of the body is selective fluid communication with the suction chamber of the compressor.