Heat Pump Systems With Capacity Modulation

Abstract

A climate-control system may include a compressor, indoor and outdoor heat exchangers, a fluid line, and a control valve. The compressor may include a scrolls that cooperate to define a plurality of pockets, including outer, inner and intermediate pockets. A capacity-modulation passage is in fluid communication with the intermediate pocket. The heat exchangers are in fluid communication with the compressor. The fluid line extends from the compressor to a location between the heat exchangers and is fluidly connected to the intermediate pocket via the capacity-modulation passage. The control valve controls a flow of fluid through the fluid line. The system is operable in a high-capacity mode, an intermediate-capacity mode, and a low-capacity mode. The control valve allows fluid flow through the fluid line in the high-capacity mode and in the low-capacity mode. The control valve prevents fluid flow through the fluid line in the intermediate-capacity mode.

What is claimed is: 
     
         1 . A climate-control system comprising:
 a compressor having a first scroll and a second scroll that cooperate to define a plurality of pockets therebetween, wherein the pockets include a radially outer pocket, a radially inner pocket, and an intermediate pocket disposed radially between the radially outer and inner pockets, wherein the first scroll includes a capacity-modulation passage in fluid communication with the intermediate pocket;   an outdoor heat exchanger in fluid communication with the compressor;   an indoor heat exchanger in fluid communication with the compressor;   a fluid line extending from the compressor to a location between the indoor and outdoor heat exchangers, wherein the fluid line is fluidly connected to the intermediate pocket via the capacity-modulation passage; and   a control valve controlling a flow of fluid through the fluid line,   wherein the climate-control system is operable in a high-capacity mode, an intermediate-capacity mode, and a low-capacity mode, and   wherein the control valve allows fluid flow through the fluid line in the high-capacity mode and in the low-capacity mode, and wherein the control valve prevents fluid flow through the fluid line in the intermediate-capacity mode.   
     
     
         2 . The climate-control system of  claim 1 , further comprising a flash tank having a first opening, a second opening, and a third opening, wherein the first opening is fluidly connected to the indoor heat exchanger, wherein the second opening is fluidly connected to the outdoor heat exchanger, and wherein the third opening in fluidly connected to the fluid line. 
     
     
         3 . The climate-control system of  claim 2 , further comprising:
 a first expansion valve disposed between and controlling fluid flow between the indoor heat exchanger and the first opening; and   a second expansion valve disposed between and controlling fluid flow between the outdoor heat exchanger and the second opening.   
     
     
         4 . The climate-control system of  claim 3 , wherein in the high-capacity mode, the first and second expansion valves control a pressure a vapor working fluid in the flash tank to be higher than a pressure of working fluid in the intermediate pocket, thereby causing vapor working fluid in the flash tank to exit the flash tank through the third opening and flow through the fluid line toward the compressor. 
     
     
         5 . The climate-control system of  claim 4 , wherein in the low-capacity mode, the first and second expansion valves control a pressure a vapor working fluid in the flash tank to be lower than the pressure of working fluid in the intermediate pocket, thereby causing working fluid in the intermediate pocket to flow out of the compressor via the capacity-modulation passage and flow through the fluid line toward the flash tank. 
     
     
         6 . The climate-control system of  claim 5 , further comprising a reversing valve operable to switch the climate-control system between a heating mode and a cooling mode, and wherein the climate-control system. 
     
     
         7 . The climate-control system of  claim 6 , wherein when the climate-control system is operable in the low-capacity mode and the intermediate-capacity mode while operating in the cooling mode. 
     
     
         8 . The climate-control system of  claim 7 , wherein when the climate-control system is operable in the low-capacity mode, the intermediate-capacity mode, and the high-capacity mode while operating in the heating mode. 
     
     
         9 . A climate-control system comprising:
 a compressor defining a suction chamber, a discharge chamber, and an intermediate pocket at a pressure between pressures of the suction and discharge chambers, wherein the compressor includes a capacity-modulation passage in fluid communication with the intermediate pocket;   an outdoor heat exchanger in fluid communication with the compressor;   an indoor heat exchanger in fluid communication with the compressor;   a fluid line extending from the compressor to a location between the indoor and outdoor heat exchangers, wherein the fluid line is fluidly connected to the intermediate pocket via the capacity-modulation passage; and   a control valve controlling a flow of fluid through the fluid line,   wherein the climate-control system is operable in a high-capacity mode, an intermediate-capacity mode, and a low-capacity mode, and   wherein the control valve allows fluid flow through the fluid line in the high-capacity mode and in the low-capacity mode, and wherein the control valve prevents fluid flow through the fluid line in the intermediate-capacity mode.   
     
     
         10 . The climate-control system of  claim 9 , further comprising a flash tank having a first opening, a second opening, and a third opening, wherein the first opening is fluidly connected to the indoor heat exchanger, wherein the second opening is fluidly connected to the outdoor heat exchanger, and wherein the third opening in fluidly connected to the fluid line. 
     
     
         11 . The climate-control system of  claim 10 , further comprising:
 a first expansion valve disposed between and controlling fluid flow between the indoor heat exchanger and the first opening; and   a second expansion valve disposed between and controlling fluid flow between the outdoor heat exchanger and the second opening.   
     
     
         12 . The climate-control system of  claim 11 , wherein in the high-capacity mode, the first and second expansion valves control a pressure a vapor working fluid in the flash tank to be higher than a pressure of working fluid in the intermediate pocket, thereby causing vapor working fluid in the flash tank to exit the flash tank through the third opening and flow through the fluid line toward the compressor. 
     
     
         13 . The climate-control system of  claim 12 , wherein in the low-capacity mode, the first and second expansion valves control a pressure a vapor working fluid in the flash tank to be lower than the pressure of working fluid in the intermediate pocket, thereby causing working fluid in the intermediate pocket to flow out of the compressor via the capacity-modulation passage and flow through the fluid line toward the flash tank. 
     
     
         14 . The climate-control system of  claim 13 , further comprising a reversing valve operable to switch the climate-control system between a heating mode and a cooling mode, and wherein the climate-control system. 
     
     
         15 . The climate-control system of  claim 14 , wherein when the climate-control system is operable in the low-capacity mode and the intermediate-capacity mode while operating in the cooling mode. 
     
     
         16 . The climate-control system of  claim 15 , wherein when the climate-control system is operable in the low-capacity mode, the intermediate-capacity mode, and the high-capacity mode while operating in the heating mode. 
     
     
         17 . A climate-control system comprising:
 a compressor having a first scroll and a second scroll that cooperate to define a plurality of pockets therebetween, wherein the pockets include a radially outer pocket, a radially inner pocket, and an intermediate pocket disposed radially between the radially outer and inner pockets, wherein compressor includes a capacity-modulation passage in fluid communication with the intermediate pocket;   an outdoor heat exchanger in fluid communication with the compressor;   an indoor heat exchanger in fluid communication with the compressor;   a fluid line extending from the compressor to a location between the indoor and outdoor heat exchangers, wherein the fluid line is fluidly connected to the intermediate pocket via the capacity-modulation passage;   a flash tank having a first opening, a second opening, and a third opening, wherein the first opening is fluidly connected to the indoor heat exchanger, wherein the second opening is fluidly connected to the outdoor heat exchanger, and wherein the third opening in fluidly connected to the fluid line;   a first expansion valve disposed between and controlling fluid flow between the indoor heat exchanger and the first opening; and   a second expansion valve disposed between and controlling fluid flow between the outdoor heat exchanger and the second opening,   wherein the climate-control system is operable in a high-capacity mode, an intermediate-capacity mode, and a low-capacity mode,   wherein in the high-capacity mode, the first and second expansion valves control a pressure a vapor working fluid in the flash tank to be higher than a pressure of working fluid in the intermediate pocket, thereby causing vapor working fluid in the flash tank to exit the flash tank through the third opening and flow through the fluid line toward the compressor,   wherein in the low-capacity mode, the first and second expansion valves control a pressure a vapor working fluid in the flash tank to be lower than the pressure of working fluid in the intermediate pocket, thereby causing working fluid in the intermediate pocket to flow out of the compressor via the capacity-modulation passage and flow through the fluid line toward the flash tank, and   wherein in the intermediate-capacity mode, fluid flow through the fluid line is prevented.   
     
     
         18 . The climate-control system of  claim 17 , further comprising a reversing valve operable to switch the climate-control system between a heating mode and a cooling mode, and wherein the climate-control system. 
     
     
         19 . The climate-control system of  claim 18 , wherein when the climate-control system is operable in the low-capacity mode, the intermediate-capacity mode, and the high-capacity mode while operating in the heating mode. 
     
     
         20 . The climate-control system of  claim 19 , wherein when the climate-control system is operable in the low-capacity mode and the intermediate-capacity mode while operating in the cooling mode.