| 摘要 |
PURPOSE:To make it possible to carry out a high precision position detection by installing magnetic resistance elements in motor driving devices and feeding back the positions of doors detected by the magnetic resistance elements. CONSTITUTION:A door 11 carries out changeover of an air intake port. Air taken in is heated by a heater 8, and is cooled depending on the opening degree of a door 21 to a suitable temperature by a cooler 9. Thus, the air is ventilated through respective blow-off ports by the opening or closing of doors 31, 32 and 33. Motors 1a, 2a and 3a are contained in motor driving devices 1, 2 and 3, and magnetic resistance elements 1b, 2b and 3b are provided therein. Signals of a sensor 6 and an operating switch 5 enter into a control circuit 4d, and a positional signal is emitted therefrom. The position of this signal is compared with the current position. When the former position deviates from the latter, the motor 2a is driven by a drive circuit 4a, and the door 21 is moved to a predetermined position to control the temperature of air. The positional signal knowing the current position detects a magnetic flux variation due to the rotation of the motor by the magnetic resistance element 3b, and is detected as a rotational pulse.Hence, it is possible to know the current position. With respect to the doors 11, 31, 32 and 33, similar procedures are carried out.
|
