Electric brush motor for electric power turning device

Abstract

A brush motor for an electric power steering system comprises a four-pole field portion 3, an armature 4 having windings 9 wound around a core 5 with 22 slots 8 to constitute a lap winding, hooks 12 which are formed on one ends of 22 commutator segments 10 respectively and on which the windings 9 are hooked, and a cylindrical commutator 7 constructed by molding integrally the commutator segments 10 with a resin, and four brushes 18 which contact slidably to outer peripheral surfaces of the commutator segments 10, wherein, when the commutator 7 to which a sliding contact portion of the brush 18 contacts is sectioned perpendicularly to an axial direction, a relationship of 0.18<=(AxN)/(DxD)<=0.23 is satisfied,where A is a sectional area of one commutator segment, N is a number of the commutator segments, and D is a diameter of outer peripheral surfaces of the commutator segments.

Description

technical field [0001] The present invention relates to reducing the brush temperature of a brush motor for an electric power steering apparatus, the motor having a cylindrical commutator having a plurality of commutator segments fixed with resin, and sliding on the outer peripheral surface of the commutator segments of the commutator. Contact brushes. Background technique [0002] In the existing brush motors for electric power steering devices, in order to reduce the temperature rise of the brushes, in addition to increasing the drop rate of the motor current, suppressing heat generation, or increasing the shape of the motor itself to increase the heat capacity, there are also tight Paste the brush holder device to absorb and dissipate the heat generated by the brush and reduce the temperature rise of the brush and other methods (for example, refer to Patent Document 1). [0003] [Patent Document 1] [0004] Japanese Patent Laid-Open No. 2002-153022 (paragraph [0005][000...

AI Technical Summary

Problems solved by technology

[0005] In conventional brush motors for electric power steering devices, in order to avoid overheating of the motor, the drop rate of the motor energized current is sometimes increased, and the energized current is limited to suppress heat generation. The boost torque increases, the steering torque of the driver increases, especially when the vehicle is running at low speed, the steering feel is not good

In addition, in the case of enlarging the shape of the motor itself to increase the heat capacity, in addition to the inconvenience of installation and the increase in noise due to the increase in the size of the motor, the moment of inertia and loss torque also increase, and the steering feel and the return of the steering wheel are poor. poor

In addition, when the heat sink is attached to the brush holder to reduce the temperature rise of the brush, there are problems such as an increase in the number of parts, an increase in the shape of the heat sink due to the addition of the heat sink, and an increase in noise.

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