Delphi Technologies, Inc.

Delco Electronics Corporation

James C Bach

Kevin M Gertiser

Gregory J Manlove

John L Kastura

Gerald A Kilgour

Gerlad A Kilgour

Richard J Szep

Robert Joseph Stock

John J Baker

A variable reluctance sensor interface module having a variable attenuation circuit and a rectifier and differential to single-ended conversion circuit for operating in a current mode to attenuate a differential input voltage. The variable attenuation circuit receives an input differential voltage from a magnetic sensor, converts the differential voltage to current, and variably attenuates the current. The rectifier and differential to single-ended conversion circuit converts the variably attenuated current to a voltage output. The input circuit includes an RC filter that attenuates high frequency signals. An initial threshold circuit generates an initial threshold voltage that compensates for internal resistance variations.

Variable attenuation circuit for a differential variable reluctance sensor with enhanced initial threshold accuracy

An improved method of measuring vehicle speed based on the output signal of a variable reluctance speed sensor responsive to the teeth of a transmission output gear adjusts the sensitivity of a signal processing circuit in dependence on the mode of operation of the vehicle so as to reduce sensitivity to output signals produced by gear tooth vibration. The signal processing circuit only passes portions of the sensor output signal that have an amplitude greater than a predefined threshold and a frequency less than a predefined frequency, except when an electronic controller identifies a condition of potentially erroneous speed sensing characterized by substantially stationary vehicle operation with the engine decoupled from the output gear and an engine speed in excess of a calibrated threshold. Under the identified condition, the controller reduces the sensitivity of the signal processing circuit by raising the predefined amplitude threshold and lowering the predefined cut-off filter frequency so that only large amplitude, low frequency signals are passed.

Signal processing method for a variable reluctance vehicle speed sensing mechanism

A modulator has an FET output driver for applying repetitive pulses to an inductive load. A predriver comprises a resistor and capacitor in parallel across the FET source and gate for shaping the control voltage. A constant current source, turned on and off by an input signal, couples the shaping circuit to ground. The resistor and capacitor values determine the rate of control voltage change which is the same for turn-on and turn-off, to control the driver current slew rate for minimizing RFI emissions.

Reduced RFI power pulse modulator

An inductive load energized by a variable duty cycle pulse signal contains ripple at steady state conditions, and the average current is used as feedback to a controller. The average current is obtained without filtering by synchronously sampling the local maxima and minima of the current and averaging the last two samples. The maxima and minima are detected by sampling at the falling and rising edges of the pulse signal. The method is implemented by software in a microprocessor or by hardware comprising a pulse generator, sample and hold circuits, and an averager. The resulting average value is then asynchronously sampled by a microprocessor.

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Carmel, IN, United States of America

James C Bach