WIPER AND WASHER SYSTEMS
A Windshield Wiper is a device used in the vehicle’s windscreen to remove ice, dust and water at different weather conditions for a clear vision to the driver.
General. The following types of wiper and washer systems are used
- Single-speed wiper (for rear wiper).
- 2-speed wiper.
- Intermittent wiper.
- Intermittent wiper with intermittent time adjuster.
- Washer-linked wiper.
- Front washer and rear washer with separate motors.
- Front washer and rear washer sharing the same motor.
The wiper and washer system consists of the components:
1. Wiper motor. Ferrite magnet type motors, which use the permanent magnets, are used for the wiper motors. The wiper motors are consists of the motor itself and the gears, which reduce the output of speed by the motor. A cam switch is incorporated into the gear section so that the wipers will stop at the same position each time.
The ferrite type wiper motor uses three brushes: a low-speed brush, a high-speed brush and a common brush (for ground).
The cam switch consists of a notched cam plate and three contact points. When the notch
in the cam plate a arrives at the contact points, the power supply to the motor is cut off and the motor stops. It is then braked electrically to prevent continued rotation due to inertia.
Switching motor speeds
A counter-electromotive force is generated in the armature coils when the motor turns, which acts to limit the speed of the motor’s rotation.
Low-speed operation. When current is flowing in the armature coils from the low-speed brush, a large counter-electromotive force is generated, with the result that the motor turns at low speed.
High-speed operation. When current is flowing in the armature coils from the high-speed brush, a small counter electromotive force is generated, with the result that the motor turns at high speed.
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