Method and system for automatic capacity self-modulation in a comrpessor

Abstract

An automatic self-modulation capacity compressor for an HVAC&R system is disclosed. The system includes a housing, a compressor, a motor, and a pressure sensitive control valve. The HVAC&R system further comprises an expander and a condenser. In the open position, the control valve permits a portion of the pressurized gasses from the compressor to escape, creating a partial capacity compressor within the system. Once a predetermined set point pressure differential is met, the control valve moves to the closed position, where all of the pressurized gasses within the compressor are provided to the system, thereby creating a full capacity compressor. Once the compressor is operating in full capacity, the compressor remains in full capacity mode until the demands of the system are met and the compressor shuts down. Upon restart, the compressor operates in partial capacity until the predetermined set point pressure is met once again and the compressor begins operating in full capacity.

1 . A method for modulating capacity in a compressor for an HVAC&R system comprising the steps of:
 providing a control valve having a first position and a second position, the control valve being configured and disposed to permit full compressor capacity in response to the control valve being in the second position and being configured to permit partial compressor capacity in response to the control valve being in the first position;   positioning the control valve in the first position upon start up of the compressor;   operating the compressor at partial capacity in response to the control valve being in the first position;   measuring a pressure differential in the compressor;   comparing the measured pressure differential to a predetermined pressure differential set point;   switching the control valve to the second position to operate the compressor at full capacity in response to the measured pressure differential being equal to or greater than the predetermined pressure differential set point; and   operating the compressor at full capacity in response to the control valve being in the second position until a shut down of the compressor.   
   
   
       2 . The method of  claim 1  further comprising the steps of:
 selecting a temperature set point for an enclosed space;   measuring an actual temperature of the enclosed space;   comparing the actual temperature and the temperature set point; and   initiating operation of the compressor in response to the temperature set point not being satisfied.   
   
   
       3 . The method of  claim 2  further comprising the step of deactivating the compressor in response to the actual temperature satisfying the temperature set point. 
   
   
       4 . The method of  claim 3  wherein the HVAC&R system is operated in a heating mode and the step of deactivating the compressor includes shutting down the compressor when the actual temperature is equal to or greater than the temperature set point. 
   
   
       5 . The method of  claim 3  wherein the HVAC&R system is operated in a cooling mode and the step of deactivating the compressor includes shutting down the compressor when the actual temperature is less than or equal to the temperature set point. 
   
   
       6 . The method of  claim 1  wherein the step of positioning the control valve includes positioning the control valve in an open position and the step of switching the control valve to the second position includes positioning the control valve in a closed position. 
   
   
       7 . The method of  claim 1  wherein the step of providing a control valve includes positioning the control valve in a closed position and the step of switching the control valve to the second position includes positioning the control valve in an open position. 
   
   
       8 . The method of  claim 1  wherein the step of switching the control valve to the second position occurs substantially instantaneously. 
   
   
       9 . The method of  claim 1  wherein the step of operating the compressor at full capacity includes continuing to operate the compressor at full capacity when the pressure differential is less than the predetermined pressure differential set point. 
   
   
       10 . A compressor for an HVAC&R system comprising:
 a housing, the housing having an inlet and an outlet;   a compression mechanism, the compression mechanism being configured to receive uncompressed fluid from the inlet at a first pressure and provide compressed fluid to the outlet at a second pressure higher than the first pressure; and   a pressure control valve having a first position and a second position, the pressure control valve being configured to be in the first position on startup of the compressor, to switch to the second position in response to the difference between the first pressure and the second pressure being greater than a predetermined pressure differential set point, and to remain at the second position until the compressor shuts down.   
   
   
       11 . The compressor of  claim 10  wherein the first position of the control valve is an open position and the second position of the control valve is a closed position. 
   
   
       12 . The compressor of  claim 11  wherein the open position of the control valve permits fluid to return to the inlet during operation of the compressor and the closed position of the control valve prevents fluid from returning to the inlet. 
   
   
       13 . The compressor of  claim 12  wherein the pressure control valve upon being in the closed position is configured to remain in the closed position when the pressure differential is less than the predetermined pressure differential set point. 
   
   
       14 . The compressor of  claim 10  wherein the first position of the control valve is a closed position and the second position of the control valve is an open position. 
   
   
       15 . The compressor of  claim 10  wherein the pressure control valve is in fluid communication with the inlet. 
   
   
       16 . The compressor of  claim 10  wherein the switch to the second position occurs substantially instantaneously. 
   
   
       17 . An HVAC&R system comprising:
 a compressor, a condenser and an evaporator connected in a closed refrigeration loop;   a temperature control system, the temperature control system being configured to receive a set point temperature and a corresponding measured temperature for an enclosed space;   the compressor being configured to receive a fluid at an inlet at a first pressure and discharge fluid at an outlet at a second pressure higher than the first pressure, the compressor comprising:
 a pressure control valve having a first predetermined position and a second predetermined position; and 
 the pressure control valve being configured to be in the first position on startup of the compressor and to switch to the second position in response to the difference between the first pressure and the second pressure being greater than the predetermined set point pressure, and to remain at the second predetermined position until the compressor shuts down. 
   
   
   
       18 . The system of  claim 17  wherein the system is a cooling system and begins operation in response to the measured temperature being greater than the set point temperature and ends operation in response to the measured temperature being less than or equal to the set point temperature. 
   
   
       19 . The system of  claim 17  wherein the system is a heating system and begins operation in response to the measured temperature being less than the set point temperature and ends operation in response to the measured temperature being equal to or greater than the set point temperature. 
   
   
       20 . The system of  claim 17  wherein the first position is an open position and the second position is a closed position. 
   
   
       21 . The system of  claim 20  wherein the open position permits fluid to return to the inlet during operation of the compressor and the closed position prevents fluid from returning to the inlet. 
   
   
       22 . The system of  claim 21  wherein the pressure control valve is configured to transition from the open position to the closed position substantially instantaneously. 
   
   
       23 . The system of  claim 17  wherein the first position is a closed position and the second position is an open position.