Protective circuit in a device for reducing vibrations of a vehicle body

Abstract

The present invention relates to an electrical protective circuit, used when abnormality occurs, in a vibration suppressing apparatus which changes the load torque on a generator such as an alternator fixed on the engine to generate an angle moment on the generator body to cancel rough idling engine vibrations to suppress vehicle body vibrations due to the rough idling. In the inventive vibration suppressing apparatus, a generator is fixed on the engine which generator includes a voltage regulator to control a field winding current such that a fixed voltage is output to a battery. The generation of engine rough idling is detected on the basis of either a change in the engine speed or a change in the engine vibrations. If rough idling is detected, a high voltage circuit is connected to the field winding to increase the field winding current and hence the load torque on the generator. In the inventive protective circuit, the battery voltage is compared with a predetermined reference value when no rough idling is detected. If the battery voltage exceeds the reference value, a changeover signal is generated and the high voltage circuit is disconnected from the field winding in response to the changeover signal.