Mitsubishi Denki Kabushiki Kaisha

Takeshi Sugimoto

Fumio Matsuoka

Yusuke Yamada

Toshiaki Yamaguchi

Kouichi Negoro

Tetsuya Yamashita

Koji Takeda

A condenser (2), an electronic expansion valve (5), an evaporator (6), and a motorized suction throttle valve (8) are connected in series with a compressor. When a capacity is increased, the electronic expansion valve (5) is controlled to be in a throttling direction and the motorized suction throttle valve (8) is controlled to be in an unthrottling direction in association with the control of the electronic expansion valve (5), and when a capacity is decreased, the electronic expansion valve (5) is controlled to be in an unthrottling direction and the motorized suction throttle valve (8) is controlled to be in a throttling direction in association with the control of the electronic expansion valve (5). While a capacity control of a compressor by a throttle control is been carried out, such associated control is made between the electronic expansion valve (5) and the motorized suction throttle valve (8), realizing a fine temperature control in a refrigerating machine without hunting.

Refrigeration cycle system

A control transistor (3) is connected between a power supply terminal (1) and an output terminal (19). The base bias of the control transistor (3) is controlled by bias control transistors (12, 13), thereby the output voltage is maintained at a constant value. An overcurrent state is detected by a current control detecting transistor (22), and the base bias of the control transistor (3) is controlled by the bias control transistors (12, 13), so as to prevent the overcurrent. The current control detecting transistor (22) further detects the time when the potential of the output terminal (19) becomes approximately 0 V by, e.g., short-circuiting of a load, so as to control the base bias of the control transistor (3) through the bias control transistors (12, 13), thereby the current to the load is decreased to a value considerably smaller than a limited value for preventing the overcurrent.

Constant-voltage power supply circuit

Growing community of inventors

Wakayama, Japan

Takeshi Sugimoto