| 摘要 |
PURPOSE:To reduce an energy loss and accurately maintain a temperature in a casing by embedding heating wires in the circumference of housing openings, which are provided between a cold air inlet part and its outlet part and which are opened and closed by the vanes of a rotor, and disposing a detecting switch for supplying power to heaters when the rotor closes the openings. CONSTITUTION:A drive signal is sent to a motor 34 to allow a rotor 38 to rotate via a reduction gear 35, and the vaned 38b, 38c of the rotor 38 rotate in the direction in which two openings 25a, 25b provided in the annular recess 20a of a housing 20 are closed. In this case, pressure-sensitive, electrically-conductive rubber members 29 provided at the openings 25a, 25b are brought into contact with metal pieces 40 provided at the vanes 38b, 38c of the rotor 38, and when the rubber members are pressed under substantial pressure, the pressure-sensitive, electrically-conductive rubber members 29 conduct to cause the electric current of a signal to flow between two electrodes 28, thereby supplying power to heaters 27 and heating the outer frames 26 of the openings 25a, 25b. By this method wherein power is supplied to heating wires only when the rotor, which is most susceptible to freezing, continues the state of closing the openings, an energy loss can be made less than that in the case of the constant supply of power to the heaters. |
