Alliedsignal Truck Brake Systems Company

Alliedsignal Truck Brake Systems

Alliedsignal Truke Brake Systems

Tamas Imre Pattantyus

Ronald E Squires

Steven J Griggs

A multi-channel wheel speed sensor having a custom integrated interface circuit. The interface circuit is configured with voltage programmable threshold adjustment allowing the circuit sensitivity to be specially tuned to detect wheel speeds in very specific ranges for a variety of applications. This feature can be implemented in ABS and/or traction control systems wherein in ABS mode a lower sensitivity adjustment can be used since wheel speeds below 5 mph do not need to sensed and processed precisely and in traction control mode very low wheel speeds, 1-1.5 mph are sensed and processed especially at non-drive wheels which provide speed reference for slipping or spinning drive wheels. The interface circuit is also configured with a test circuit for testing the integrity of the speed sensors and for providing information to the controller about the sensor/tone wheel gap.

Custom integrated wheel-speed sensor circuit with sensitivity adjustment

In accordance with the teachings of the present invention, a wheel speed sensor signal conditioning circuit is provided for conditioning sensor output signals received from a variable reluctance wheel speed sensor. The conditioning circuit includes filtering circuitry and peak detecting circuitry that detects the positive and negative voltage peaks of a sensor output signal irrespective of the sensor output signal crossing a reference voltage level. When the sensor output signal exceeds a predetermined peak to peak voltage level, the peak detecting circuitry limits the amplitude of the output signal and forms a dynamic high pass filter. A comparator circuit is coupled to the peak detecting circuitry and outputs a first signal when the peak detecting circuitry detects a positive voltage peak and outputs a second signal when the peak detecting circuitry detects a negative voltage peak of the sensor output signal.

Circuit and method for conditioning a wheel speed sensor signal

An electronic interface custom integrated circuit which provides interfacing between micro-controller devices and field effect transistors in truck or car anti-lock braking systems for controlling solenoid valves to modulate the pressure in the brake chambers or brake cylinders. The interface circuit includes built-in diagnostic and safety features including fault protection interlock, safety interlocks, status indication outputs and a special purpose analog output for enhancing the performance of anti-lock braking system electronic control units.

Solenoid driver interface custom integrated circuit

A speed signal conditioning and test circuit includes a comparator which is connected to a digital input port of a microprocessor and which switches its output in response to the alternating current generated by the sensor when sensing wheel speed. A test sequence is initiated by injecting a signal into a tuned circuit formed by the inductance of the sensor coil, the filtering capacitors, and associated circuit resistances. The voltage output of the tuned circuit increases exponentially and switches the comparator to provide a test pulse of a predetermined time period. The microprocessor times the pulse to establish that an operative sensor is present. Since the inductance of the coil is switched out of the circuit in the case of an open or shorted sensor coil, no pulse is generated and the microprocessor accordingly determines that a defective sensor is present.

Speed sensor and conditioning circuit

A brake pressure control mechanism for establishing a pressure level in a brake actuator includes a valve controlled by the current in a solenoid coil. The current in the coil is controlled in a first mode by switching the current in the coil off and on and allowing the current to increase and decay in the normal manner. However, when a fast decrease in brake pressure is demanded, the fly-back voltage across the coil is allowed to rapidly increase to a level greater than and in opposition to the voltage applied to the coil, thereby quickly driving the current lower. Current is driven to zero in the case of a fast brake pressure decay being demanded by the adaptive braking system or when the vehicle operator releases the brakes. When the error signal demands a fast decay, the fast decay mode is initiated and then returned to the normal control when the error between the demanded braking pressure and the pressure corresponding to the current of the coil is back within predetermined limits.

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North Olmsted, OH, United States of America

Tamas Imre Pattantyus