Variable displacement type compressor, air conditioner with the variable displacement type compressor, and method for controlling displacement in the variable displacement type compressor

Abstract

A variable displacement type compressor circulates a fluid in an air conditioning circuit. The compressor has a compression mechanism and a displacement control valve. The compression mechanism compresses the fluid. The displacement control valve controls discharge amount of the fluid of the compressor. In a first predetermined range of discharge pressure, suction pressure decreases at a first variation as the discharge pressure increases. In a second predetermined range of the discharge pressure that is higher than the first predetermined range, the suction pressure varies at a second variation as the discharge pressure increases. The second variation is constituted of at least one of a third variation that is smaller than the first variation and at which the suction pressure decreases as the discharge pressure increases, a fourth variation at which the suction pressure increases as the discharge pressure increases, and substantially zero.

What is claimed is:  
     
         1 . A variable displacement type compressor that circulates a fluid in an air conditioning circuit, the fluid being drawn into a suction region before compression, the pressure in the suction region being defined as suction pressure, tho fluid being discharged to tho discharge region after compression, the pressure in the discharge region being defined as discharge pressure, the suction region being connected to the discharge region, the compressor comprising: 
 a compression mechanism for compressing the fluid; and    a displacement control valve for controlling discharge amount of the fluid of the compressor, in a first predetermined range of the discharge pressure the suction pressure decreasing at a first variation as the discharge pressure increases, in a second predetermined range of the discharge pressure that is higher than the first predetermined range the suction pressure varying at a second variation as the discharge pressure increases, the second variation being constituted of at least one of a third variation that is smaller than the first variation and at which the suction pressure decreases as the discharge pressure increases, a fourth variation at which the suction pressure increases as the discharge pressure increases, and substantially zero.    
     
     
         2 . The variable displacement type compressor according to  claim 1 , wherein the suction pressure increases or is maintained to a predetermined value as the discharge pressure increases in the second predetermined range.  
     
     
         3 . The variable displacement type compressor according to  claim 1 , wherein the suction pressure increases as the discharge pressure increases in a third predetermined range of the discharge pressure that is lower than the first predetermined range.  
     
     
         4 . The variable displacement type compressor according to  claim 3 , wherein the discharge amount is controlled by introducing the compressed fluid from the discharge region to a crank chamber pressure region, the displacement control valve further comprising: 
 a communication route communicating the discharge region and the crank chamber pressure region;    a valve body for opening and closing the communication route by sensing the suction pressure and the discharge pressure; and    an urging means for enabling to urge the valve body so as to open or close the communication route, the urging means urging the valve body so as to open the communication route in the second predetermined range.    
     
     
         5 . The variable displacement type compressor according to  claim 4  wherein the urging means urges the valve body so as to close the communication route in the third predetermined range.  
     
     
         6 . The variable displacement type compressor according to  claim 5 , the urging means further comprising: 
 a rod for contacting the valve body in the third predetermined range;    a rod supplementing member for urging the valve body so as to open the communication route in the second predetermined range; and    a spring for applying elastic urging force to the rod and the rod supplementing member, the rod and the rod supplementing member being operated based on a balance between the discharge pressure of the fluid and the elastic urging force of the spring.    
     
     
         7 . The variable displacement type compressor according to  claim 3 , wherein the suction pressure and the discharge pressure have a first inflectional point that connects the third predetermined range to the second predetermined range.  
     
     
         8 . The variable displacement type compressor according to  claim 1 , wherein the suction pressure and the discharge pressure have a second inflectional point that connects the first predetermined range to the second predetermined range.  
     
     
         9 . An air conditioner comprising: 
 an air conditioning circuit including a fluid;    a condenser in the air conditioning circuit for condensing the fluid;    an expansion valve in the air conditioning circuit for expanding the condensed fluid;    an evaporator in the air conditioning circuit for evaporating the expanded fluid to exchange heat between the fluid and air in a room; and    a variable displacement type compressor in the air conditioning circuit for compressing the evaporated fluid, the fluid being drawn into a suction region before compression, the pressure in the suction region being defined as suction pressure, the fluid being discharged to the discharge region after compression, the pressure in the discharge region being defined as discharge pressure, the suction region being connected to the discharge region, the compressor comprising;    a compression mechanism for compressing the fluid; and    a displacement control valve for controlling discharge amount of the fluid of the compressor, in a first predetermined range of the discharge pressure the suction pressure decreasing at a first variation as the discharge pressure increases, in a second predetermined range of the discharge pressure that is higher than the first predetermined range the suction pressure varying at a second variation as the discharge pressure increases, the second variation being constituted of at least one of a third variation that is smaller than the first variation and at which the suction pressure decreases as the discharge pressure increases, a fourth variation at which the suction pressure increases as the discharge pressure increases, and substantially zero.    
     
     
         10 . A method for controlling displacement in a variable displacement type compressor that circulates a fluid in an air conditioning circuit, the fluid being drawn into a suction region before compression, the pressure in the suction region being defined as suction pressure, the fluid being discharged to the discharge region after compression, the pressure in the discharge region being defined as discharge pressure, the suction region being connected to the discharge region, the method comprising the steps of: 
 decreasing the suction pressure at a first variation as the discharge pressure increases in a first predetermined range of the discharge pressure;    setting a third variation that is smaller than the first variation and at which the suction pressure decrease as the discharge pressure increases in a second predetermined range of the discharge pressure that is higher than the first predetermined range;    setting a fourth variation at which the suction pressure increases as the discharge pressure increases in the second predetermined range;    setting a second variation by using at least one of the third variation, the fourth variation, and substantially zero in the second predetermined range; and    varying the suction pressure at the second variation as the discharge pressure increases in the second predetermined range.    
     
     
         11 . The method for controlling displacement in the variable displacement type compressor according to  claim 10 , wherein the second variation setting step comprises increasing tho suction pressure or maintaining to a predetermined value as the discharge pressure increases.  
     
     
         12 . The method for controlling displacement in the variable displacement type compressor according to  claim 11 , comprising the additional step of increasing the suction pressure as the discharge pressure increases in a third predetermined range of the discharge pressure that is lower than the first predetermined range.  
     
     
         13 . The method for controlling displacement in the variable displacement type compressor according to  claim 12 , comprising the additional step of providing the suction pressure and the discharge pressure with a first inflectional point that connects the third predetermined range to the second predetermined range.  
     
     
         14 . The method for controlling displacement in the variable displacement type compressor according to  claim 10 , comprising the additional step of providing the suction pressure and the discharge pressure with a second inflectional point that connects the first predetermined range to the second predetermined range.