초록 ▼

A spring return rotary actuator incorporating a DC brush commutated electric motor and a pulse width modulation drive circuit which reduces the voltage at which current is supplied to the motor once a rotation sensor senses that the actuator output shaft has stalled. The drive circuit also includes

A spring return rotary actuator incorporating a DC brush commutated electric motor and a pulse width modulation drive circuit which reduces the voltage at which current is supplied to the motor once a rotation sensor senses that the actuator output shaft has stalled. The drive circuit also includes a temperature responsive feature which increases the voltage at which current is supplied to the motor in the event a sensed temperature exceeds a temperature limit.

대표청구항 ▼

[ The embodiments of the invention in which an exclusive property or right is claimed are defined as follow:] [1.]1. A drive circuit for an actuator having an output shaft, a spring coupled to the shaft operable to bias the shaft for rotation toward a rest position, and an electric motor coupled to

[ The embodiments of the invention in which an exclusive property or right is claimed are defined as follow:] [1.]1. A drive circuit for an actuator having an output shaft, a spring coupled to the shaft operable to bias the shaft for rotation toward a rest position, and an electric motor coupled to the shaft and energizable by electric current at at least a predetermined average voltage to rotate the shaft against the bias of the spring away from the rest position, the spring being operable to return the shaft to the rest position when the motor is not energized, the drive circuit comprising:input means for providing current at at least the predetermined average voltage when it is desired to rotate the shaft away from the rest position;a rotation sensor operable to produce a first signal indicative of whether or not the actuator output shaft is rotating; anda modulation circuit operable in response to both current received from said input means and the first signal indicating rotation of the actuator output shaft to supply current at a first average voltage adequate to energize the electric motor to continue to rotate the output shaft away from the rest position against the bias of the spring, and operable in response to current received from said input means to supply current at a second average voltage less than the first average voltage, but sufficient to hold the actuator output shaft in position against the bias of the spring when the first signal indicates that the actuator output shaft has stalled.