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 first modulation port, a second modulation port, and a vent passage, wherein the first modulation port is in fluid communication with a first one of the fluid pockets at the radially intermediate positions, wherein the second modulation port is in fluid communication with a second one of the fluid pockets at the radially intermediate positions, and wherein the vent passage is in selective fluid communication with the first and second modulation ports and a suction-pressure region;   a capacity-modulation system including a first control valve, a second control valve, a first piston, and a second piston; and   a control module controlling operation of the first and second control valves,   wherein:
 each of the first and second control valves is movable between a first position and a second position, 
 the first piston is movable between an open position in which fluid communication between the first 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, 
 the second piston is movable between an open position in which fluid communication between the second 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 control module is in communication with a thermostat that communicates to the control module whether a cooling demand exists and whether a humidity control demand exists, 
 in response to determining that the cooling demand exists, the control determines whether the cooling demand is a high cooling demand, a medium cooling demand, or a low cooling demand, 
 in response to determining that the cooling demand is the high cooling demand, the control module is configured to control the first and second control valves to cause the first and second pistons to move to the closed position to prevent fluid communication between the first modulation port and the vent passage and to prevent fluid communication between the second modulation port and the vent passage, 
 in response to determining that the cooling demand is the medium cooling demand, the control module is configured to control the first control valve to cause the first piston to move to the closed position to prevent fluid communication between the first modulation port and the vent passage and the control module is configured to control the second control valve to cause the second piston to move to the open position to allow fluid communication between the second modulation port and the vent passage, 
 in response to determining that the cooling demand is the low cooling demand, the control module is configured to control the first and second control valves to cause the first and second pistons to move to the open position to allow fluid communication between the first modulation port and the vent passage and to allow fluid communication between the second modulation port and the vent passage, and 
 in response to determining that there is the humidity control demand exists and that there is no cooling demand, the control module is configured to control the first and second control valves to cause the first and second pistons to move to the open position to allow fluid communication between the first modulation port and the vent passage and to allow fluid communication between the second modulation port and the vent passage. 
   
     
     
         2 . The compressor of  claim 1 , wherein in response to determining that the cooling demand exists, the control module is configured to determine whether an energy saving mode is active. 
     
     
         3 . The compressor of  claim 2 , wherein in response to determining that the energy saving mode is active, the control module is configured to control the first and second control valves to cause the first and second pistons to move to the open position to allow fluid communication between the first modulation port and the vent passage and to allow fluid communication between the second modulation port and the vent passage regardless of whether the cooling demand is the high cooling demand, medium cooling demand, or low cooling demand. 
     
     
         4 . The compressor of  claim 3 , wherein each of the first and second control valves includes a body, a housing, and a valve member,
 wherein:
 the body is fixedly received in a valve passage in the second end plate and sealingly engages a first portion of the valve passage, 
 the body includes a first passage, a second passage, and a third passage, 
 the housing is fixed relative to the second end plate and the body and includes an aperture that is open to a suction chamber of the compressor, 
 the valve member is disposed within the housing and is movable therein between first and second positions, and 
 the valve member includes a stem portion that is movably received in the first passage of the body. 
   
     
     
         5 . The compressor of  claim 4 , wherein:
 when the valve member is in the first position, the stem portion allows fluid communication between the second and third passages and prevents fluid communication between the third passage and the aperture in the housing,   when the valve member is in the second position, the stem portion prevents fluid communication between the second and third passages and allows fluid communication between the third passage and the aperture in the housing,   the vent passage extends from and is in direct communication with a suction inlet defined by the second scroll;   the capacity-modulation system includes a control valve and a piston,   the control valve is movable between a first position and a second position,   the piston is disposed within a recess in the second end plate,   the vent passage extends from the recess to the suction inlet,   the piston is movable in the recess 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, and   movement of the control valve to the first position causes movement of the piston to the closed position, and movement of the control valve to the second position causes movement of the piston to the open position.   
     
     
         6 . The compressor of  claim 5 , wherein each of the first and second pistons includes a recess formed in an axially-facing surface thereof, wherein the axially-facing surface sealingly contacts a surface of the second scroll in the closed position. 
     
     
         7 . The compressor of  claim 6 , wherein the recess in the piston is vented to the vent passage. 
     
     
         8 . The compressor of  claim 5 , wherein:
 the first piston is movably disposed within a first recess that extends into the second end plate, wherein the first 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.   
     
     
         9 . The compressor of  claim 8 , wherein the second recess is formed in the piston and is in fluid communication with the modulation port. 
     
     
         10 . The compressor of  claim 8 , wherein the second recess is in fluid communication with the vent passage. 
     
     
         11 . The compressor of  claim 10 , wherein the second end plate includes a first portion and a second portion that is attached to the first portion by fasteners. 
     
     
         12 . The compressor of  claim 11 , wherein the second portion of the second end plate defines the first recess and cooperates with the first and second pistons to define first and second actuation chambers, wherein the first and second actuation chambers are in fluid communication with the first and second control valves, respectively. 
     
     
         13 . The compressor of  claim 12 , wherein the second recess is formed in the first portion of the second end plate. 
     
     
         14 . 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 first modulation port, a second modulation port, and a vent passage, wherein the first modulation port is in fluid communication with a first one of the fluid pockets at the radially intermediate positions, wherein the second modulation port is in fluid communication with a second one of the fluid pockets at the radially intermediate positions, and wherein the vent passage is in selective fluid communication with the first and second modulation ports and a suction-pressure region;   a capacity-modulation system including a first control valve, a second control valve, a first piston, and a second piston; and   a control module controlling operation of the first and second control valves,   wherein:
 each of the first and second control valves is movable between a first position and a second position, 
 the first piston is movable between an open position in which fluid communication between the first 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, 
 the second piston is movable between an open position in which fluid communication between the second 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 control module is in communication with a thermostat that communicates to the control module whether a cooling demand exists and whether a humidity control demand exists, 
 in response to determining that the cooling demand exists, the control determines whether the cooling demand is a high cooling demand, a medium cooling demand, or a low cooling demand, 
 in response to determining that the cooling demand is the high cooling demand, the control module is configured to control the first and second control valves to cause the first and second pistons to move to the closed position to prevent fluid communication between the first modulation port and the vent passage and to prevent fluid communication between the second modulation port and the vent passage, 
 in response to determining that the cooling demand is the medium cooling demand, the control module is configured to control the first control valve to cause the first piston to move to the closed position to prevent fluid communication between the first modulation port and the vent passage and the control module is configured to control the second control valve to cause the second piston to move to the open position to allow fluid communication between the second modulation port and the vent passage, 
 in response to determining that the cooling demand is the low cooling demand, the control module is configured to control the first and second control valves to cause the first and second pistons to move to the open position to allow fluid communication between the first modulation port and the vent passage and to allow fluid communication between the second modulation port and the vent passage, 
 in response to determining that there is the humidity control demand exists and that there is no cooling demand, the control module is configured to control the first and second control valves to cause the first and second pistons to move to the open position to allow fluid communication between the first modulation port and the vent passage and to allow fluid communication between the second modulation port and the vent passage, each of the first and second control valves includes a body, a housing, and a valve member, 
 the body is fixedly received in a valve passage in the second end plate and sealingly engages a first portion of the valve passage, the body includes a first passage, a second passage, and a third passage, 
 the housing is fixed relative to the second end plate and the body and includes an aperture that is open to a suction chamber of the compressor, 
 the valve member is disposed within the housing and is movable therein between first and second positions, and 
 the valve member includes a stem portion that is movably received in the first passage of the body. 
   
     
     
         15 . The compressor of  claim 14 , wherein:
 the first piston is movably disposed within a first recess that extends into the second end plate, wherein the first 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.   
     
     
         16 . The compressor of  claim 15 , wherein the second recess is formed in the piston and is in fluid communication with the modulation port. 
     
     
         17 . The compressor of  claim 15 , wherein the second recess is in fluid communication with the vent passage. 
     
     
         18 . The compressor of  claim 15 , wherein the second end plate includes a first portion and a second portion that is attached to the first portion by fasteners. 
     
     
         19 . The compressor of  claim 18 , wherein the second portion of the second end plate defines the first recess and cooperates with the first and second pistons to define first and second actuation chambers, wherein the first and second actuation chambers are in fluid communication with the first and second control valves, respectively. 
     
     
         20 . The compressor of  claim 19 , wherein the second recess is formed in the first portion of the second end plate.