Drive unit for variable displacement electric compressor

Abstract

A compressor is actuated by a motor and varies the displacement by the operation of an electromagnetic actuator. A drive unit of the compressor includes a power source, a motor drive circuit located on a power supply path between the motor and the power source, and an actuator drive circuit located on a power supply path between an electromagnetic actuator and the power source. The motor drive circuit drives the motor and the actuator drive circuit drives the electromagnetic actuator. The motor drive circuit and the actuator drive circuit share a smoothing circuit and a filter circuit. Therefore, the actuator drive circuit does not require its own smoothing circuit and a filter circuit. This reduces the number of parts of the drive unit, thereby reducing the size and the cost of the drive unit.

1 . A drive unit of a compressor that is actuated by a motor to compress gas and varies the displacement by the operation of an electromagnetic actuator, the drive unit comprising: 
 a power source;    a motor drive circuit located on a power supply path between the motor and the power source, wherein the motor drive circuit drives the motor in accordance with an external command signal; and    an actuator drive circuit located on a power supply path between the electromagnetic actuator and the power source, wherein the actuator drive circuit drives the electromagnetic actuator in accordance with an external command signal, and wherein one of the drive circuits includes an electric element, which electrically affects the other drive circuit.    
     
     
         2 . The drive unit according to  claim 1 , wherein one of the drive circuits has an output terminal, wherein the other drive circuit has an input terminal, and wherein the output terminal is connected to the input terminal.  
     
     
         3 . The drive unit according to  claim 1 , wherein the electric element forms a smoothing circuit for stabilizing the applied voltage from the power source.  
     
     
         4 . The drive unit according to  claim 3 , wherein the drive circuits share the smoothing circuit.  
     
     
         5 . The drive unit according to  claim 1 , wherein the electric element forms a filter circuit for filtering noise from the power source.  
     
     
         6 . The drive unit according to  claim 5 , wherein the drive circuits share the filter circuit.  
     
     
         7 . The drive unit according to  claim 1 , wherein the power source is a direct-current power source, which has a high potential terminal and a low potential terminal, and the actuator drive circuit includes a switching element, which has a first terminal and a second terminal, wherein the electromagnetic actuator includes a coil, which has a first terminal and a second terminal, wherein the first terminal of the switching element is connected to the high potential terminal of the direct-current power source, and the first terminal of the coil is connected to the low potential terminal of the direct-current power source, and wherein the second terminal of the switching element is connected to the second terminal of the coil.  
     
     
         8 . The drive unit according to  claim 7 , wherein a shunt resistor is arranged between the low potential terminal of the direct-current power source and the first terminal of the coil, and wherein the shunt resistor is used for detecting the value of the current flowing through the coil.  
     
     
         9 . The drive unit according to  claim 1 , wherein the power source is a direct-current power source, which has a high potential terminal and a low potential terminal, and the actuator drive circuit includes a switching element, which has a first terminal and a second terminal, wherein the electromagnetic actuator includes a coil, which has a first terminal and a second terminal, wherein the first terminal of the switching element is connected to the low potential terminal of the direct-current power source, and the first terminal of the coil is connected to the high potential terminal of the direct-current power source, and wherein the second terminal of the switching element is connected to the second terminal of the coil.  
     
     
         10 . The drive unit according to  claim 9 , wherein the motor is an AC motor, and the motor drive circuit includes a plurality of phase inverter circuits, wherein each phase inverter circuit includes a high-side switching element, which has a first terminal and a second terminal, and a low-side switching element, which has a first terminal and a second terminal, wherein the first terminal of the high-side switching element is connected to the high potential terminal of the direct-current power source, and the first terminal of the low-side switching element is connected to the low potential terminal of the direct-current power source, wherein the second terminal of the high-side switching element and the second terminal of the low-side switching element are connected to the AC motor via a common AC output terminal, and wherein the low-side switching element and the switching element of the actuator drive circuit are driven by a common drive source.  
     
     
         11 . The drive unit according to  claim 1 , wherein the motor is a DC motor.  
     
     
         12 . The drive unit according to  claim 11 , wherein a power line extending from the motor drive circuit to the motor and a power line extending from the actuator drive circuit to the electromagnetic actuator are partially shared.  
     
     
         13 . The drive unit according to  claim 1 , wherein the compressor includes a control chamber and a control valve, wherein the control valve has the electromagnetic actuator, and the opening degree of the control valve is adjusted by the electromagnetic actuator to change the pressure in the control chamber, and wherein the displacement of the compressor is varied in accordance with the pressure in the control chamber.  
     
     
         14 . The drive unit according to  claim 1 , wherein the compressor is incorporated in an air-conditioner of a vehicle, and wherein the compressor is actuated by selectively using the engine of the vehicle and the motor.  
     
     
         15 . A drive unit of a compressor that is actuated by a motor to compress gas, wherein the compressor includes a control chamber and a control valve, wherein the control valve has an electromagnetic actuator, and the opening degree of the control valve is adjusted by the electromagnetic actuator to change the pressure in the control chamber, and wherein the displacement of the compressor is varied in accordance with the pressure in the control chamber, the drive unit comprising: 
 a power source;    a motor drive circuit located on a power supply path between the motor and the power source to drive the motor;    an actuator drive circuit located on a power supply path between the electromagnetic actuator and the power source to drive the electromagnetic actuator;    a command device, which sends a command signal to each of the drive circuits to control the drive circuits; and    a single smoothing circuit for stabilizing the voltage applied to the motor drive circuit from the power source and the voltage applied to the actuator drive circuit from the power source.    
     
     
         16 . The drive unit according to  claim 15 , further comprising a single filter circuit, wherein the filter circuit filters noise from the power source to the motor drive circuit and noise from the power source to the actuator drive circuit.  
     
     
         17 . The drive unit according to  claim 15 , wherein the power source is a direct-current power source, which has a high potential terminal and a low potential terminal, and the actuator drive circuit includes a switching element, which has a first terminal and a second terminal, wherein the electromagnetic actuator includes a coil, which has a first terminal and a second terminal, wherein the first terminal of the switching element is connected to the high potential terminal of the direct-current power source, and the first terminal of the coil is connected to the low potential terminal of the direct-current power source, and wherein the second terminal of the switching element is connected to the second terminal of the coil.  
     
     
         18 . The drive unit according to  claim 17 , wherein a shunt resistor is arranged between the low potential terminal of the direct-current power source and the first terminal of the coil, and wherein the shunt resistor is used for detecting the value of the current flowing through the coil.  
     
     
         19 . The drive unit according to  claim 15 , wherein the power source is a direct-current power source, which has a high potential terminal and a low potential terminal, and the actuator drive circuit includes a switching element, which has a first terminal and a second terminal, wherein the electromagnetic actuator includes a coil, which has a first terminal and a second terminal, wherein the first terminal of the switching element is connected to the low potential terminal of the direct-current power source, and the first terminal of the coil is connected to the high potential terminal of the direct-current power source, and wherein the second terminal of the switching element is connected to the second terminal of the coil.  
     
     
         20 . The drive unit according to  claim 19 , wherein the motor is an AC motor, and the motor drive circuit includes a plurality of phase inverter circuits, wherein each phase inverter circuit includes a high-side switching element, which has a first terminal and a second terminal, and a low-side switching element, which has a first terminal and a second terminal, wherein the first terminal of the high-side switching element is connected to the high potential terminal of the direct-current power source, and the first terminal of the low-side switching element is connected to the low potential terminal of the direct-current power source, wherein the second terminal of the high-side switching element and the second terminal of the low-side switching element are connected to the AC motor via a common AC output terminal, and wherein the low-side switching element and the switching element of the actuator drive circuit are driven by a common drive source.  
     
     
         21 . The drive unit according to  claim 15 , wherein the motor is a DC motor, and wherein a power line extending from the motor drive circuit to the motor and a power line extending from the actuator drive circuit to the electromagnetic actuator are partially shared.