Title: Improvements and Applications of Permanent Magnet Materials in Automotive Sensors
text: Advancement of automotive electronic technology is leading to a greater use of permanent magnet materials. New vehicle specifications demand sensors and D.C. motors to be lighter and more efficient. Magnet manufacturers are developing materials and processes to meet these needs, both for the present and the future. Permanent magnets today are used in a wide range of industrial, domestic, automotive and aerospace applications. Their special, technological importance derives from their ability to act contactlessly on ferromagnetic material, either by attraction or repulsion, and to provide a permanent magnetic flux with no energy input and, hence, at no operating cost. The current usage of permanent magnets in domestic applications averages 50 per household in the United States, as illustrated in Figure 1. Perhaps the most surprising range of permanent magnet uses are the numerous applications in a modern passenger vehicle. These applications include an array of D.C. electric motors such as the starter, heater and air conditioner blower, windshield wiper, window lift, door lock and fuel pump motors. A fully equipped car can have more than 30 D.C. electric motors. Other uses include actuators, gauges and sensors, as shown in Figure 2. In all these examples, higher performance magnetic materials may afford the advantages of increased operating efficiency and reduction in size and weight. The continuing improvement in magnetic materials together with advances in power and integrated electronics has seen the development of a wide range of devices in which field coil windings are replaced by permanent magnets. These developments have also led to a dramatic increase in the use of permanent magnets in automotive sensor applications.