| 摘要 |
<p>PURPOSE:To make it possible to use a small capacity, relay, by adding a fail- safe relay having normally open contacts in a source power supply line for an electromagnetic clutch in a power transmission path, and by deenergizing the relay to disengage the clutch when occurrence of an abnormality is judged. CONSTITUTION:In a motor driven type power steering device, the power transmission between a worm wheel shaft 15 rotated by a DC motor 13 and a pinion shaft 17 meshed with a tooth section 6b of a rack shaft 6 is cut off by an electromagnetic clutch 16. In this arrangement, a fail-safe relay 91 is composed of a drive coil 91a connected at its one end to the positive terminal of a battery 11 through a key switch 12, and normally open contacts 91b including a contact 91b1 connected to an input terminal of the electromagnetic clutch 16, is provided in the control unit 9. Further, the energization of the drive coil 19a is controlled by means of a drive circuit 99 which cuts off the power to the drive coil 19a when occurrence of an abnormality is judged in accordance with a steering torque signal and a vehicle speed signal.</p> |
