Compressor device and control method for the same

A compressor device comprising:

• a compressor for compressing refrigerant in a refrigerant cycle system by using motive power from a vehicle engine, the compressor being provided with a displacement changing mechanism for changing displacement of the compressor per rotation thereof;
• and
• a control unit for changing a current value supplied to the displacement changing mechanism in accordance with a thermal load of the refrigerant cycle system, and for relatively changing the displacement of the compressor by changing the current value, wherein:
• the control unit changes the displacement such that the displacement of the compressor is increased by decreasing the current value toward a minimum current value;
• and
• the control unit controls a lower limit of the current value between the minimum current value and a first predetermined value that is set larger than the minimum current value, when the rotational speed of the vehicle engine is lower than the first predetermined rotational speed.

A control method of controlling a compressor for compressing refrigerant in a refrigerant cycle system by using motive power from a vehicle engine, the compressor including a displacement changing mechanism for changing displacement of the compressor per rotation thereof, the control method comprising:

• controlling a current value supplied to the displacement changing mechanism in accordance with a thermal load of the refrigerant cycle system;
• and
• relatively changing the displacement of the compressor by the controlled current value, based on a first control where the displacement of the compressor is increased by increasing the current value toward the maximum current value, or a second control where the displacement of the compressor is increased by decreasing the current value toward a minimum current value, wherein:
• in the first control, an upper limit of the current value is controlled between the maximum current value and a first predetermined value that is set smaller than the maximum current value when a rotational speed of the vehicle engine is lower than a first predetermined rotational speed;
• and
• in the second control, a lower limit of the current value is controlled between the minimum current value and a second predetermined value that is set larger than the minimum current value when the rotational speed of the vehicle engine is lower than the first predetermined rotational speed.