Application of Electromagnets in Windshield Wipers

The most widely used type of windshield wiper system employs a coil spring for wiper arm pressure generation. This spring is fixed between the arm head (fixed part) and wiper arm (moving part) and the tension in the spring is responsible for pressure generation. The present arrangement although being unsophisticated design, has following drawbacks:

• Inability to change wiper arm pressure according to change in vehicle speed.
• Inability to provide constant arm pressure during the complete range of motion along varying curvature of windshield.
• Inability to reduce/remove the continuous pressure on wiper blade when vehicle is parked for long durations resulting in permanent deformation of wiper blade rubber.

This paper describes how electromagnets can be used to overcome the above stated inherent limitations of the windshield wiper system. An electromagnet is a device which produces magnetic field on application of electric current. It consists of electrical conductor wound around a magnetic core. Unlike a permanent magnet whose magnetic field is fixed, the magnetic field produced by electromagnets can be changed or even reversed very quickly by controlling the input current. Since, magnetic fields attract or repel each other depending upon their direction, hence, electromagnets can be used to produce variable force of attraction or repulsion. This enables electromagnets to be used as a spring with adjustable stiffness.