To perform continuous displacement control of a compressor not based on feedback control.
An arithmetic processing unit 22 outputs a displacement increase/ decrease command to a displacement adjusting operation part 24 regardless of the actual displacement of the compressor on the basis of the difference between the outlet temperature of water (present water temperature) and the target temperature, and further adds an increase/decrease value based on the displacement increase/decrease command, to a displacement computed value when the displacement computed value is not maximum or minimum displacement. A maximum/minimum displacement time operation stop part 25 stops a valve motor of the displacement adjusting operation part 24 when the actual displacement of the compressor becomes the maximum or minimum displacement. Continuous displacement control not based on feedback control is thus performed to eliminate a potentiometer with the frequent occurrence of failures and wear and to enhance the reliability of the continuous displacement control device 21. At this time, the function of the maximum/minimum displacement time operation stop part 25 prevents a control range from becoming narrower than the actual control range due to the occurrence of a discrepancy between the actual displacement of the compressor and the displacement computed value and prevents also damage caused by excessive control.
KINOKAMI KENJI
MORI TAKUJI
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