Air conditioner for vehicle

Abstract

An air conditioner for a vehicle comprises a refrigeration cycle including a variable displacement compressor for refrigerant which uses an engine as a drive source, a condenser, and an evaporator, a displacement adjustment means for outputting a displacement control signal to the compressor, and a compressor torque calculation means for calculating the torque of the compressor. The compressor torque calculation means includes at least two torque estimation means of a saturation region torque estimation means corresponding to a case where the compressor is driven at a maximum discharge displacement and a displacement control region torque estimation means corresponding to a case where it is driven at a discharge displacement other than the maximum discharge displacement, and also includes a correction means for correcting the calculation of the torque of the compressor when a change in engine rotational speed greater than a set value is detected. Even when the engine rotational speed changes rapidly, the torque of the compressor in the refrigeration cycle can be precisely calculated.

1 . An air conditioner for a vehicle comprising at least a refrigeration cycle which includes a variable displacement compressor capable of varying a displacement for discharge of refrigerant which uses an engine as a drive source, a condenser for refrigerant, and an evaporator for refrigerant, a displacement adjustment means for outputting a displacement control signal to said compressor, and a compressor torque calculation means for calculating a torque of said compressor, in which said compressor torque calculation means includes at least two torque estimation means of a saturation region torque estimation means corresponding to a case where said compressor is driven at a maximum discharge displacement and a displacement control region torque estimation means corresponding to a case where said compressor is driven at a discharge displacement other than said maximum discharge displacement, characterized in that said compressor torque calculation means has a correction means for adding a correction corresponding to a response delay of said compressor and said refrigeration cycle to said calculation of said torque of said compressor when a change in engine rotational speed greater than a set value is detected. 
     
     
         2 . The air conditioner for a vehicle according to  claim 1 , wherein said correction means reads a correction coefficient for said compressor torque calculation from a map, which is made in advance by employing a rotational speed change rate, that is a difference between a rotational speed immediately before a time when said engine rotational speed changes and a rotational speed at a time when said engine rotational speed has changed after a predetermined sampling time has passed, and a correction coefficient predetermined in correspondence with said rotational speed change rate, as parameters, and adds said correction based on said correction coefficient read. 
     
     
         3 . The air conditioner for a vehicle according to  claim 2 , wherein said map is made as a map in which a plurality of characteristic lines, each determining a relationship between said rotational speed change rate and said correction coefficient, are set selectively by further employing a load to said refrigeration cycle as a parameter. 
     
     
         4 . The air conditioner for a vehicle according to  claim 3 , wherein said load to said refrigeration cycle employed as said parameter is an outside air temperature. 
     
     
         5 . The air conditioner for a vehicle according to  claim 3 , wherein said load to said refrigeration cycle employed as said parameter is a pressure at a high-pressure side of said refrigeration cycle. 
     
     
         6 . The air conditioner for a vehicle according to  claim 1 , wherein a smaller value among values calculated by said saturation region torque estimation means and said displacement control region torque estimation means is selected as a torque estimate. 
     
     
         7 . The air conditioner for a vehicle according to  claim 1 , wherein said air conditioner further comprises an engine rotational speed detection means for detecting an engine rotational speed of a vehicle or referring to its signal, an outside air temperature detection means for detecting an outside air temperature, and a high pressure detection means for detecting a refrigerant pressure at a high-pressure side, said compressor is a variable displacement compressor capable of controlling a discharge displacement, and said displacement control region torque estimation means estimates said torque of said compressor based on at least a displacement control signal, said refrigerant pressure at said high-pressure side, said outside air temperature, and said engine rotational speed, and adds a correction determined by said correction means to said compressor torque calculation. 
     
     
         8 . The air conditioner for a vehicle according to  claim 7 , wherein said air conditioner further comprises means for detecting a physical amount having a correlation with an amount of air passing through said condenser, and said displacement control region torque estimation means estimates said torque of said compressor further referring to said physical amount having a correlation with an amount of air passing through said condenser. 
     
     
         9 . The air conditioner for a vehicle according to  claim 7 , wherein said air conditioner further comprises means for detecting a physical amount having a correlation with an amount of air passing through said evaporator, and said displacement control region torque estimation means estimates said torque of said compressor further referring to said physical amount having a correlation with an amount of air passing through said evaporator. 
     
     
         10 . The air conditioner for a vehicle according to  claim 7 , wherein said air conditioner further comprises a vehicle running speed recognition means for detecting a vehicle running speed or referring to its signal, and said displacement control region torque estimation means estimates said torque of said compressor further referring to said vehicle running speed. 
     
     
         11 . The air conditioner for a vehicle according to  claim 1 , wherein said air conditioner further comprises an engine rotational speed detection means for detecting an engine rotational speed of a vehicle or referring to its signal, a vehicle running speed recognition means for detecting a vehicle running speed or referring to its signal, an outside air temperature detection means for detecting an outside air temperature, and a high pressure detection means for detecting a refrigerant pressure at a high-pressure side, said compressor is a variable displacement compressor capable of controlling a discharge displacement, and said displacement control region torque estimation means estimates a power of said compressor based on at least a displacement control signal, said refrigerant pressure at said high-pressure side, said vehicle running speed and said outside air temperature, estimates said torque of said compressor from said engine rotational speed and said estimated power of said compressor, and adds a correction determined by said correction means to said compressor torque calculation. 
     
     
         12 . The air conditioner for a vehicle according to  claim 11 , wherein said air conditioner further comprises means for detecting a physical amount having a correlation with an amount of air passing through said condenser, and said displacement control region torque estimation means estimates said power of said compressor further referring to said physical amount having a correlation with an amount of air passing through said condenser, and estimates said torque of said compressor from said engine rotational speed and said estimated power of said compressor. 
     
     
         13 . The air conditioner for a vehicle according to  claim 11 , wherein said air conditioner further comprises means for detecting a physical amount having a correlation with an amount of air passing through said evaporator, and said displacement control region torque estimation means estimates said power of said compressor further referring to said physical amount having a correlation with an amount of air passing through said evaporator, and estimates said torque of said compressor from said engine rotational speed and said estimated power of said compressor. 
     
     
         14 . The air conditioner for a vehicle according to  claim 1 , wherein said air conditioner further comprises an engine rotational speed detection means for detecting an engine rotational speed of a vehicle or referring to its signal, and an outside air temperature detection means for detecting an outside air temperature, and said saturation region torque estimation means estimates said torque of said compressor based on at least said outside air temperature and said engine rotational speed, and adds a correction determined by said correction means to said compressor torque calculation. 
     
     
         15 . The air conditioner for a vehicle according to  claim 14 , wherein said air conditioner further comprises means for detecting a physical amount having a correlation with an amount of air passing through said condenser, and said saturation region torque estimation means estimates said torque of said compressor further referring to said physical amount having a correlation with an amount of air passing through said condenser. 
     
     
         16 . The air conditioner for a vehicle according to  claim 14 , wherein said air conditioner further comprises means for detecting a physical amount having a correlation with an amount of air passing through said evaporator, and said saturation region torque estimation means estimates said torque of said compressor further referring to said physical amount having a correlation with an amount of air passing through said evaporator. 
     
     
         17 . The air conditioner for a vehicle according to  claim 14 , wherein said air conditioner further comprises a vehicle running speed recognition means for detecting a vehicle running speed or referring to its signal, and said saturation region torque estimation means estimates said torque of said compressor further referring to said vehicle running speed. 
     
     
         18 . The air conditioner for a vehicle according to  claim 1 , wherein said saturation region torque estimation means employs a certain predetermined value as a torque estimate. 
     
     
         19 . The air conditioner for a vehicle according to  claim 1 , wherein said saturation region torque estimation means leads a torque estimate by employing a torque estimation map in which a torque estimate is predetermined relative to an outside air temperature, an engine rotational speed or a vehicle running speed. 
     
     
         20 . The air conditioner for a vehicle according to  claim 1 , wherein an information of a calculated torque estimate is sent to an engine control unit.