Motor vehicle cooling apparatus with electric motor surge current inhibitor

摘要

A cooling apparatus for automotive use wherein speed of an electric cooling fan is controlled solely at a predetermined speed. When a relay switch is switched on, voltage of a battery is applied to a lag circuit. Output of the lag circuit is applied to a gate G of a MOS transistor, but rise of the gate-applied voltage is delayed by the lag circuit according to a time constant thereof, and increases slowly. When the gate-applied voltage reaches the threshold voltage of the MOS transistor, the MOS transistor begins to switch on. However, when the gate-applied voltage is low, the drain current flowing through the MOS transistor is limited and thereby surge current at the motor is minimized.