Back to results
US 2013/0278098 A1Published application
Linear actuator
AssigneeJohnson Electric S.A.
InventorsYvan BOURQUI, Miha FURLAN
Life of this patent
Estimating the term…
Abstract
A linear actuator with a high holding force providing good irreversibility, has a high efficiency, low friction screw mechanism and a stepper motor with high magnetic detent torque but a low output torque ripple. The phase torque is modified to minimize the effect of the detent torque on the output. torque. Preferably, the motor has asymmetric phases to compensate for the detent torque.
Claims19
An electric motor, comprising:
- a stator having a plurality of phase windings forming a number of magnetic poles;
- a rotor having a rotor core and a permanent magnet fixed to the rotor core;
- an output shaft, coupled to the rotor core;
- and
- a detent mechanism arranged to magnetically attract the rotor to the stator to hold the rotor in a desired rotational orientation with respect to the stator with a predetermined detent torque, the detent torque producing a corresponding torque variation;
- wherein the phase windings are asymmetric and produce different excited torques which when combined with the detent torque produce a combined output torque having a desired torque ripple.
3 more elements
A linear stepper motor, comprising:
- a stator having a plurality of phase windings forming a number of magnetic poles;
- a rotor having a rotor core and a permanent magnet fixed to the rotor core;
- an output shaft, coupled to the rotor core via a screw mechanism such that rotation of the rotor core produces linear movement of the output shaft;
- and
- a detent mechanism arranged to magnetically attract the rotor to the stator to hold the rotor in desired rotational orientation with respect to the stator with a predetermined detent torque,
- wherein the number of pole pairs of the stator is greater than ten and the screw efficiency of the screw mechanism is 50% or more.
3 more elements
Dependencies are inferred from the claim text.