PERMANENT MAGNET DIRECT CURRENT MOTOR

摘要

Disclosed is an improvement to the stability of D.C. motor brushes mounted in brush boxes with wings, is improved by angling the wings toward the commutator such that the brush spring contacts the brush at one or more points intermediate the ends of the brush. Improved cooling is provided by utilizing an end plate with apertures and a brush plate which, in combination with the commutator, provides a brush plate aperture for cooling air flow. In a preferred embodiment, speed variations of the motor can be achieved by selectively disconnecting one or more brushes in a four brush embodiment, reducing the torque and rotating speed of the motor. In a preferred embodiment, the use of a diode to interconnect same polarity brushes permits a speed change to be accomplished by selectively connecting one or the other end of the diode. In a further preferred embodiment, the stalling of the motor having power applied is indicated by an electronic output where voltage applied to one brush is filtered through an RC filter with the output amplified and voltage doubled. A ripple output indicating that the motor is rotating after amplification will light a light-emitting diode indicating proper operation of the motor.