| 摘要 |
PURPOSE:To unnecessitate the judging of each conduction current of a semiconductor element at the time of high speed and low speed by short-circuiting the semiconductor element and a resistor at high speed and driving a motor by a conduction circuit through said semiconductor element and the resistor at low speed. CONSTITUTION:When a movable piece 10 contacts with a high speed contact 5, the motor 2 for ventilation is turned at high speed, and air is sent from the blower 2a. The semiconductor element 3a and the resistors 3b-3d are not conducted at that time. When the movable piece 10 contacts with an intermediate speed M2 contact 5, electricity is conducted in the order of a battery 1 the motor 2 the resistor 3b the semiconductor element 3a the movable piece 10 a grounding contact 9. When the movable contact contacts with an intermediate speed M1 contact 6, electricity is further conducted through the resistor 3c as compared to the case of the intermediate speed M2. When the movable piece 10 contacts with a low speed contact 7, electricity is further conducted through the resistor 3d as compared to the case of the intermediate speed M1. The semiconductor element 3a is arranged at the point where it is difficult to be subject to the radiant heat of the resistors 3b-3d. |
