Control apparatus for variable capacity compressor and method of calculating torque of variable capacity compressor

Abstract

An apparatus for calculating torque of a variable capacity compressor is provided. The compressor includes a suction chamber, a discharge chamber, a piston to draw coolant from the suction chamber, compress the drawn coolant, and discharge the compressed coolant into the discharge chamber, a clutch to be turned on to transmit driving force from a driving source to the piston so that the piston operates and to be turned off to disconnect the driving force of the driving source from the piston so that the piston stops, and a pressure adjuster to adjust a back pressure introduced from the discharge chamber to the back of the piston and thereby adjust a piston stroke. The apparatus comprises a counter configured to count an OFF time when the clutch is tuned off from an ON state until the clutch is next turned on, a determiner configured to determine whether or not the OFF time is less than a predetermined time, and a start torque calculator configured to calculate a start torque of the compressor depending on the determination of the determiner.

1 . An apparatus for calculating torque of a variable capacity compressor, the compressor including a suction chamber, a discharge chamber, a piston to draw coolant from the suction chamber, compress the drawn coolant, and discharge the compressed coolant into the discharge chamber, a clutch configured to be turned on to transmit driving force from a driving source to the piston so that the piston operates and to be turned off to disconnect the driving force of the driving source from the piston so that the piston stops, and a pressure adjuster to adjust a back pressure introduced from the discharge chamber to the back of the piston and thereby adjust a stroke of the piston, the apparatus comprising: 
 a counter configured to count an OFF time when the clutch is tuned off until the clutch is next turned on;    a determiner configured to determine whether the OFF time is less than a predetermined time; and    a start torque calculator configured to calculate a start torque of the compressor depending on the determination of the determiner.    
   
   
       2 . The apparatus of  claim 1 , wherein: 
 the predetermined time is an experimentally obtained period of time between when the clutch is turned off and when a pressure equilibrium state is established in the variable capacity compressor, so as to return the piston to an initial position.    
   
   
       3 . The apparatus of  claim 1 , wherein the start torque calculator comprises: 
 a first start torque calculator configured to calculate a start torque when the OFF time is less than the predetermined time; and    a second start torque calculator configured to calculate a start torque when the OFF time is equal to or greater than the predetermined time.    
   
   
       4 . The apparatus of  claim 3 , wherein: 
 the first start torque calculator being configured to assumes that the piston is between the initial position and a full-stroke position and calculates a start torque according to a first start torque expression; and    the second start torque calculator being configured to assume that the piston is at the initial position and calculates a start torque according to a second start torque expression.    
   
   
       5 . The apparatus of  claim 3 , wherein: 
 the first start torque calculator employs an ambient temperature and a high pressure of a refrigeration cycle as input parameters to calculate a start torque; and    the second start torque calculator employs the high pressure of the refrigeration cycle as an input parameter to calculate a start torque.    
   
   
       6 . An apparatus for calculating torque of a variable capacity compressor, the compressor including a suction chamber, a cylinder bore, a discharge chamber, a piston to draw coolant from the suction chamber into the cylinder bore, compress the drawn coolant, and discharge the compressed coolant into the discharge chamber, a clutch configured to be turned on to transmit driving force from a driving source to the piston so that the piston operates and to be turned off to disconnect the driving force of the driving source from the piston so that the piston stops, and a pressure adjuster to adjust a back pressure introduced from the discharge chamber to the back of the piston and thereby adjust a stroke of the piston, the apparatus comprising: 
 a capacity controller including an start-torque-calculate adminicle configured to provide the pressure adjuster with an external control signal for at least a predetermined time after the clutch is turned off, the external control signal being identical to a maximum capacity signal to establish a full piston stroke; and    a torque calculator having a start torque calculator configured to calculate a start torque of the compressor when the clutch is turned on.    
   
   
       7 . An apparatus for calculating torque of a variable capacity compressor, the compressor including a suction chamber, a cylinder bore, a discharge chamber, a piston to draw coolant from the suction chamber into the cylinder bore, compress the drawn coolant, and discharge the compressed coolant into the discharge chamber, a clutch configured to be turned on to transmit driving force from a driving source to the piston so that the piston operates and to be turned off to disconnect the driving force of the driving source from the piston so that the piston stops, and a pressure adjuster to adjust a back pressure introduced from the discharge chamber to the back of the piston and thereby adjust a stroke of the piston, the apparatus comprising: 
 a torque calculator configured to calculate torque of the compressor and including: 
 a counter configured to count an OFF time when the clutch is tuned off until the clutch is next turned on;  
 a determiner configured to determine whether the OFF time is less than a predetermined time; and  
 a start torque calculator configured to calculate a start torque of the compressor depending on the determination of the determiner; and  
   a capacity controller configured to provide the pressure adjuster with an external control signal, the capacity controller including: 
 an start-torque-calculate adminicle configured to provide the pressure adjuster with an external control signal for at least a predetermined time after the clutch is turned off, the external control signal being identical to a maximum capacity signal to establish a full piston stroke.  
   
   
   
       8 . The apparatus of  claim 1 , wherein: 
 the clutch is turned off when an evaporator exit temperature is equal to or less than a predetermined temperature.    
   
   
       9 . The apparatus of  claim 1 , wherein the pressure adjuster comprises: 
 a valve plug configured to change an opening of a path between the discharge chamber and the back side of the piston; and    a pressure sensitive element configured to move the valve plug in a valve opening direction when a low pressure of the refrigeration cycle decreases and in a valve closing direction when the low pressure increases.    
   
   
       10 . The apparatus of  claim 6 , wherein, when the compressor is in a steady-state operation: 
 the capacity controller controls the pressure adjuster to bring an actual evaporator exit temperature closer to a target evaporator exit temperature.    
   
   
       11 . A method of calculating torque of a variable capacity compressor, the compressor including a suction chamber, a cylinder bore, a discharge chamber, a piston to draw coolant from the suction chamber into the cylinder bore, compress the draw coolant, and discharge the compressed coolant into the discharge chamber, a clutch configured to be turned on to transmit driving force from a driving source to the piston so that the piston operates and to be turned off to disconnect the driving force of the driving source from the piston so that the piston stops, and a pressure adjuster to adjust a back pressure introduced from the discharge chamber to the back of the piston and thereby adjust a stroke of the piston, the method comprising: 
 counting an OFF time when the clutch is tuned off until the clutch is next turned on;    determining whether the OFF time is less than a predetermined time; and    calculating a start torque of the compressor depending on the determination.    
   
   
       12 . The method of  claim 11 , wherein: 
 the predetermined time is an experimentally obtained period of time between when the clutch is turned off and when a pressure equilibrium state is established in the variable capacity compressor to return the piston to an initial position.    
   
   
       13 . The method of  claim 11 , wherein calculating a start torque of the compressor depending on the determination comprises: 
 when the OFF time is less than the predetermined time, assuming that the piston is between the initial position and a full-stroke position and calculating a start torque according to a first start torque expression; and    when the OFF time is equal to or greater than the predetermined time, assuming that the piston is at the initial position and calculating a start torque according to a second start torque expression.    
   
   
       14 . The method of  claim 11 , wherein calculating a start torque of the compressor depending on the determination comprises: 
 when the OFF time is less than the predetermined time, employing an ambient temperature and a high pressure of a refrigeration cycle as input parameters to calculate a start torque; and    when the OFF time is equal to or greater than the predetermined time, employing the high pressure of the refrigeration cycle as an input parameter to calculate a start torque.    
   
   
       15 . A method of calculating torque of a variable capacity compressor, the compressor including a suction chamber, a cylinder bore, a discharge chamber, a piston to draw coolant from the suction chamber into the cylinder bore, compress the drawn coolant, and discharge the compressed coolant into the discharge chamber, a clutch configured to be turned on to transmit driving force from a driving source to the piston so that the piston operates and to be turned off to disconnect the driving force of the driving source from the piston so that the piston stops, and a pressure adjuster to adjust a back pressure introduced from the discharge chamber to the back of the piston and thereby adjust a stroke of the piston, the method comprising: 
 providing the pressure adjuster with an external control signal for at least a predetermined time after the clutch is turned off, the external control signal being identical to a maximum capacity signal to establish a full piston stroke; and    calculating a start torque of the compressor when the clutch is turned on.    
   
   
       16 . A method of calculating torque of a variable capacity compressor, the compressor including a suction chamber, a cylinder bore, a discharge chamber, a piston to suck coolant from the suction chamber into the cylinder bore, compress the sucked coolant, and discharge the compressed coolant into the discharge chamber, a clutch to be turned on to transmit driving force from a driving source to the piston so that the piston operates and to be turned off to disconnect the driving force of the driving source from the piston so that the piston stops, and a pressure adjuster to adjust a back pressure introduced from the discharge chamber to the back of the piston and thereby adjust a piston stroke, the method comprising: 
 providing the pressure adjuster with an external control signal after the clutch is turned off from an ON state, the external control signal being identical to a maximum capacity signal to establish a full piston stroke;    counting an OFF time when the clutch is tuned off until the clutch is next turned on;    determining whether the OFF time is less than a predetermined time; and    calculating a start torque of the compressor depending on the determination.    
   
   
       17 . The method of  claim 16 , wherein: 
 a time for providing the external control signal identical to the maximum capacity signal is longer than the predetermined time.    
   
   
       18 . The method of  claim 11 , further comprising: 
 turning off the clutch when an evaporator exit temperature is equal to or lower than a predetermined temperature.    
   
   
       19 . The method of  claim 11 , wherein the pressure adjuster comprises: 
 a valve plug configured to change an opening of a path between the discharge chamber and the back side of the piston; and    a pressure sensitive element configured to move the valve plug in a valve opening direction when a low pressure of the refrigeration cycle decreases and in a valve closing direction when the low pressure increases.