1992-02-01

Anti-Lock Brake Sensor Rings with Corrosion and Chip Resistance 920220

As the social aaareness of the need for greater automobile safety has risen, autonolive parts manufacturers have focused a lot of new research and development to aulomotive brake systems. Aith the much rapid advances and steady cost reductions in microelectronics technology, highly reliable, electronically controlled lour-thee1 antilock brake systems (ABS) are beginning to gain broad acceptance.Horever, wide acceptance of ABS depends upon the system and having superior performance, and high reliability at an affordable price. The toothed wheels (sensor rings) used for measuring the wheel velocity in the ABS require high precision in the pitch error of the teeth and specific magnetic properties in order to accurately detect wheel velocity, which is the first signal for brake control. Moreover, as these sensor rings are located close to the wheel, they require increased corrosion resistance ability higher than any other automotive parts.By taking full advantage of the features of powder metallurgy, it is possible to manufacture complex parts with high precision and at a cost effective price. In taking this technology and combining it with a special*DACROTlZED®treatment process. re have been able to develop and manufacture sensor rings which satisfy the above requirements.Additionally, as many wheel sensor rings operate uncovered near the vehicle wheel position, chip resistance is also required as sand and gravel can directly hit the sensor rings directly during operation.As a results, a new sensor ring has been developed rhich has not only good corrosion resistance from muddy water or salt water, but also good protection from chipping from sand or gravel. These new sensor rings are protected rith a two layer plating. The first layer has good corrosion resistance, and the second layer is very hard. In measuring output voltage alter a shot peening test simulating gravel chipping and a 1800 ks salt spray test, this two layer plated sensor ring shored little decrease in output voltage.(DACROTIZED® is the trademark of Metal Coaling International Inc.)

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