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Emerald Group Publishing Limited
Copyright © 1998, MCB UP Limited
Keywords Automotive, Sensors, Spectrol Electronics.
Spectrol Electronics, in Ontario, California, designed its exhaust-valve position (EVP) sensor to withstand temperatures up to 175°C, vibration, humidity, and dust in a critical under-the-hood application on Ford Motor Co. vehicles including the Mustang and Explorer.
The EVP is essentially a linear potentiometer with a voltage output signal proportional to the displacement of the input plunger. In the Ford application, this sensor is mounted on the vacuum actuator of the exhaust recirculation valve, which in turn is mounted on the intake manifold.
The valve recirculates exhaust gas into the intake manifold to help control nitrogen oxides. As the valve moves the sensor shaft, the contact slides along the ceramic element of the sensor, contacting a proprietary resistive ink formulated to resist the temperature and vibration extremes.
The movement of the contact changes the output voltage. By sensing the position of the valve at any instant, the sensor is able to signal the engine-control computer to help adjust various engine parameters.
Ford and Spectrol engineers obtained field results from more than 4,000 vehicles representing approximately 100 million vehicle test miles, which demonstrated that the Spectrol sensor qualifies as a 150,000-mile component.