Method for estimating drive torque of variable displacement compressor and system for controlling drive source rotation speed

Abstract

The value of an estimated drive torque is prevented from greatly differing from an actual drive torque of a variable displacement compressor immediately after a refrigerating cycle is started. A first estimated drive torque that is calculated based on a physical quantity other than the pressure of a refrigerant and increases with lapse of time after the variable displacement compressor begins to compress the refrigerant and a second estimated drive torque calculated using the pressure of the refrigerant are compared and the one with the value closer to the actual drive torque is employed as an estimated drive torque of the variable displacement compressor.

1 . A method for estimating a drive torque of a variable displacement compressor included in a refrigerating cycle, wherein the refrigerating cycle comprises: 
 a variable displacement compressor having a compression mechanism section for compressing a refrigerant and a displacement variable mechanism for varying a displacement of the refrigerant to be compressed by the compression mechanism section;    a condenser for condensing the refrigerant compressed by the variable displacement compressor;    a pressure reducing means for reducing pressure of the refrigerant condensed by the condenser;    an evaporator for evaporating the refrigerant reduced in pressure by the pressure reducing means;    refrigerant pipes for connecting the variable displacement compressor, the condenser, the pressure reducing means, and the evaporator; and    a pressure detection means for detecting pressure of the refrigerant from the variable displacement compressor to the pressure reducing means, and    wherein the method comprises:    a first drive torque estimation means for calculating a first estimated drive torque of the variable displacement compressor, which is calculated based on at least a physical quantity other than pressure of refrigerant detected by the pressure detection means and which gradually increases with lapse of time after the variable displacement compressor begins to compress the refrigerant; and    a second drive torque estimation means for calculating a second estimated drive torque of the variable displacement compressor using pressure of refrigerant detected by the pressure detection means, and    the first estimated drive torque and the second estimated drive torque are compared and the one with the lower value is employed as an estimated drive torque of the variable displacement compressor.    
   
   
       2 . A method for estimating a drive torque of a variable displacement compressor included in a refrigerating cycle, wherein the refrigerating cycle comprises: 
 a variable displacement compressor having a compression mechanism section for compressing a refrigerant and a displacement variable mechanism for varying a displacement of the refrigerant to be compressed by the compression mechanism section;    a condenser for condensing the refrigerant compressed by the variable displacement compressor;    a pressure reducing means for reducing pressure of the refrigerant condensed by the condenser;    an evaporator for evaporating the refrigerant reduced in pressure by the pressure reducing means;    refrigerant pipes for connecting the variable displacement compressor, the condenser, the pressure reducing means, and the evaporator; and    a pressure detection means for detecting pressure of the refrigerant from the variable displacement compressor to the pressure reducing means, and    wherein the method comprises:    a first drive torque estimation means for calculating a first estimated drive torque of the variable displacement compressor based on at least a physical quantity other than pressure of refrigerant detected by the pressure detection means;    a second drive torque estimation means for calculating a second estimated drive torque of the variable displacement compressor using pressure of refrigerant detected by the pressure detection means; and    a lapse of time measurement means for measuring lapse of time after the variable displacement compressor begins to compress the refrigerant, and    when the lapse of time measured by the lapse of time measurement means is less than a predetermined time, the first estimated drive torque is employed as an estimated drive torque of the variable displacement compressor and when the lapse of time measured by the lapse of time measurement means is equal to or more than the predetermined time, the second estimated drive torque is employed as an estimated drive torque of the variable displacement compressor.    
   
   
       3 . The method for estimating a drive torque of a variable displacement compressor as set forth in  claim 2 , wherein: 
 the displacement variable mechanism varies the displacement of the refrigerant to be compressed by the compression mechanism section by a control current input from an outside; and    the first drive torque estimation means calculates the first estimated drive torque based on the control current.    
   
   
       4 . The method for estimating a drive torque of a variable displacement compressor as set forth in  claim 1 , wherein the first drive torque estimation means calculates the first estimated drive torque using the lapse of time after the variable displacement compressor begins to compress the refrigerant and a value stored in advance in accordance with the lapse of time.  
   
   
       5 . A system for controlling a drive source rotation speed, wherein the variable displacement compressor is driven by a drive source and the estimated drive torque calculated by the method for estimating a drive torque of a variable displacement compressor as set forth in  claim 1  is used to control rotation speed of the drive source.  
   
   
       6 . A system for controlling a drive source rotation speed, comprising 
 a refrigerating cycle having: a variable displacement compressor having a compression mechanism section for compressing a refrigerant and a displacement variable mechanism for varying a displacement of the refrigerant to be compressed by the compression mechanism section; a condenser for condensing the refrigerant compressed by the variable displacement compressor; a pressure reducing means for reducing pressure of the refrigerant condensed by the condenser; an evaporator for evaporating the refrigerant reduced in pressure by the pressure reducing means; refrigerant pipes for connecting the variable displacement compressor, the condenser, the pressure reducing means and the evaporator; and a pressure detection means for detecting the pressure of the refrigerant from the variable displacement compressor to the pressure reducing means,    a drive source for driving the variable displacement compressor,    a lapse of time measurement means for measuring lapse of time after the variable displacement compressor begins to compress the refrigerant,    a drive torque estimation means for calculating an estimated drive torque of the variable displacement compressor using pressure of refrigerant detected by the pressure detection means, and    a rotation speed calculation means for calculating a target rotation speed of the drive source using the estimated drive torque,    wherein when the lapse of time measured by the lapse of time measurement means is less than a predetermined time, a value, which is obtained by subtracting a torque calculated by a predetermined calculation from an estimated drive torque calculated by the drive torque estimation means, is used as an estimated drive torque to be used in calculation, and the estimated drive torque calculated by the drive torque estimation means is used, as it is, in calculation when the lapse of time measured by the lapse of time measurement means is equal to or more than the predetermined time.    
   
   
       7 . The system for controlling a drive source rotation speed as set forth in  claim 5 , wherein the rotation speed calculation means calculates a target idle rotation speed of the drive source.  
   
   
       8 . A method for estimating a drive torque of a variable displacement compressor in a refrigerating cycle, wherein the refrigerating cycle comprises: 
 a variable displacement compressor having a compression mechanism section for compressing a refrigerant and a displacement variable mechanism for varying a displacement of the refrigerant to be compressed by the compression mechanism section;    a condenser for condensing the refrigerant compressed by the variable displacement compressor;    a pressure reducing means for reducing pressure of the refrigerant condensed by the condenser;    an evaporator for evaporating the refrigerant reduced in pressure by the pressure reducing means;    refrigerant pipes for connecting the variable displacement compressor, the condenser, the pressure reducing means, and the evaporator; and    a pressure detection means for detecting pressure of refrigerant from the variable displacement compressor to the pressure reducing means,    wherein the method comprises:    a first drive torque estimation means for calculating a first estimated drive torque of the variable displacement compressor, which is calculated based on at least a physical quantity other than pressure of refrigerant detected by the pressure detection means and gradually increases with lapse of time after the variable displacement compressor begins to compress the refrigerant; and    a second drive torque estimation means for calculating a second estimated drive torque of the variable displacement compressor using pressure of refrigerant detected by the pressure detection means, and    the first estimated drive-torque and the second estimated drive torque are compared and the one with the value closer to an actual drive torque is employed as an estimated drive torque of the variable displacement compressor.    
   
   
       9 . The method for estimating a drive torque of a variable displacement compressor as set forth in  claim 2 , wherein the first drive torque estimation means' calculates the first estimated drive torque using the lapse of time after the variable displacement compressor begins to compress the refrigerant and a value stored in advance in accordance with the lapse of time.  
   
   
       10 . A system for controlling a drive source rotation speed, wherein the variable displacement compressor is driven by a drive source and the estimated drive torque calculated by the method for estimating a drive torque of a variable displacement compressor as set forth in  claim 2  is used to control rotation speed of the drive source.  
   
   
       11 . The system for controlling a drive source rotation speed as set forth in  claim 6 , wherein the rotation speed calculation means calculates a target idle rotation speed of the drive source.