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In the field of vehicle diagnostics accurate instantaneous engine speed information enables the detection and diagnosis of many engine problems, even subtle ones. Currently, there is a limited choice in the ways of obtaining such information. For example, it is known that one can tap into the crank sensor wiring, or use a separate, intrusive method, such as mounting a sensor in the bell housing to sense the rotation of the ring gear. However, the shortcomings of these approaches are locating and gaining access to the crank sensor connector, the location of which varies from vehicle to vehicle. Thus, authors proposed a novel, robust and manufacturing friendly speed sensor. The concept is based on the Villari effect. The sensor, which is attached to the front end of the engine crankshaft, consists of a coil of magnetostrictive wire supplied with AC current. During engine rotation the magnetostrictive wire become stressed due to centrifugal force.

This paper describes a dual-track magnetic crankshaft and camshaft position sensor configuration. It uses semiconductor sensors such as magnetoresistors to pick up the magnetic flux modulation created by a toothed wheel rotating across a permanent magnet. This sen-sor's magnetic configuration, with a complementary geometry, enhances the accuracy and repeatability of the position pulses. This is critical in obtaining the engine-velocity measurement precision necessary to detect engine misfires as mandated by the OBD-II legislation. The complementary geometry also makes for a more robust design. Finally, the concept can be used for cam-shaft position sensing, with power-on capability.

MAGNECODE uses laser surface heating to pattern permanent magnets for position sensor applications. Thermal and magnetic models provide good predictions of the geometry of the laser heated regions and the resulting spatial variations in the magnetic field. Important design factors are discussed and a comparison with other magnetic sensor technologies is given.

Auto theft has become a serious and costly problem for our society. Approximately one million motor vehicles have been stolen each year for the past several years. A new approach to help solve this problem was introduced in 1986. It was developed after careful study of theft techniques and is based on the philosophy that introducing an unavoidable time delay for the thief is the most effective countermeasure. It satisfies all the restrictive design constraints imposed on a vehicle manufacturer offering the system as standard equipment. The Vehicle Anti-Theft System - VATS utilizes an electrical code (a resistor pellet) embedded in the ignition key, in addition to the mechanical code. The electronic module that reads the electrical code and enables engine operation is in a remote location and not readily accessible to the thief. While no system will make a car theft proof, VATS will delay the thief an additional 15 to 20 minutes on the average.