| 摘要 |
PURPOSE:To improve durability of brushes, by providing a defroster control circuit controlling energization of an excitation coil and a polarity inverting circuit and inverting polarity of an electric current flowing in the excitation coil at every operation of a compressor. CONSTITUTION:A defroster control circuit 620 and a temperature sensing element 600 provided in an evaporator 500 are connected to control the action of a refrigerating cycle with this detected temperature, simultaneously a polarity inverting circuit 800 is provided between a contact 760a of an actuator switch 760 and a contact 640b of the defroster control circuit 620 and brushes 2a, 2b. Then using input from the actuator switch 760 for a power source and a signal of a contact 640 for an input pulse, an output signal is inverted at every input of said pulse by a trigger flip flop 801 to invert polarity of the brushes 2a, 2b through contacts 805, 806. In this way, the brushes 2a, 2b are uniformly worn to improve their durability. |
