| 摘要 |
1483033 Supply circuits for vehicle window heaters FORD MOTOR CO Ltd 11 Feb 1976 05294/76 Heading H2H A circuit for de-icing and de-misting a vehicle window comprises a first switch 51 for connecting a heating element 30 to an output terminal A of a generator, a second switch 52a, 52b normally occupying a first state and a control circuit 32 responsive to a manual actuation to switch the second switch to a second state for a limited period of time and thereafter to return the second switch to its first state. The generator may be an alternator having a field winding 22 and when the switch 51 is closed, the alternator supplies power to the heating element to demist the window. In order to de-ice the window a switch 53 is closed and the control circuit 32 causes the switch 52a, 52b to occupy its second state. In this position an ignition warning light 14 is short circuited and a voltage regulator 18 is supplied only from the battery 12 so that the high field winding current causes a high output from the alternator. Since the switch 52a is open, this output is fed only to the heating element 30. After a predetermined time, a timer circuit in the control circuit 32 causes the switch 52a, 52b to return to its first state. A thermistor in the timing circuit may vary the de-ice period in dependence on the interior temperature of the vehicle. A battery voltage sensor in the circuit 32 prevents de-icing being initiated if the battery voltage is low. The switches 51, 52a, 52b may be transistors or thyristors. |
