US 4,395,668 AGranted

Motors

OwnerFumito Komatsuinventor

Life of this patent

Estimating the term…

Loading patent…

Abstract

A synchronous motor comprising a permanent-magnet rotor and a stator which, at startup, uses rectifiers for supplying the stator coil with rectified current and a commutator consisting of sliders and brushes both rotary in union with the rotor in order to supply only the rectified component, effective to energize the rotor's rotation, from the AC power-supply, and which is provided with a mechanical conversion device designed such that, when the rotor's rotation has reached nearly the speed of synchronous rotation, the slider is allowed to move in the direction along the rotary shaft to become released from contact with the brush, for removal of contact load and at the same time to supply the stator directly with the power-supply AC.

Claims5

Dependent claims

In a synchronous motor having a permanent-magnet motor, a stator, rectifiers for converting the AC power supply into rectified current, and a commutator for switching the direction of current as the rotor rotates during start-up, and means for switching the AC supply directly to the stator when the rotor approaches synchronous speed;

the improvement wherein the commutator comprises a rotary component which rotates with the rotor and engages fixed switching elements for effecting switching of the current to rectify current for the motor, said rotary component being axially displaceable to release it from contact with said switching elements, and means are provided for effecting said displacement when the rotor approaches synchronous speed, said displacement allowing said switching elements to contact each other to permit the AC current to be supplied directly to the stator by way of said switching elements.

Dependencies are inferred from the claim text.