Westinghouse Air Brake Company

Barry J. Kahr

John H. Corvin

Barry J Kahr

John H Corvin

A pulse width modulated drive circuit drives a solenoid operated valve in response to an input voltage signal from a control apparatus. The solenoid operated valve includes a coil that is energizable in response to energy received from the pulse width modulated drive circuit. The pulse width modulated drive circuit includes a pulse generator stage and an output stage. The pulse generator stage receives the input voltage signal from the control apparatus and a feedback signal from the coil which ultimately combine to form a control voltage in response to which the pulse generator stage generates a pulse width modulated signal whose duty cycle depends on the control voltage. The output stage receives the pulse width modulated signal from the pulse generator stage and generates in response thereto a pulse width modulated output signal across the coil. The pulse width modulated output signal has pulse width generally proportional to the control voltage and carries energy from a source of energy. The pulse width modulated output signal energizes the coil thereby enabling the coil to generate a force generally proportional to the average current carried by the pulse width modulated output signal.

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Fountain Inn, SC, United States of America

Barry J Kahr