Brushless motor

Abstract

It is possible to suppress generation of vibration without requiring an additional electronic part or modification of an existing arrangement. Yokes (41a to 41d) have a magnetic pole tooth (42) formed in such a way that the ratio of the length of side (44c) of the tip of the tooth (42) against the width b of the base of the tooth (42) is 65% or above and the ratio of its height h against the width b of the base is not smaller than 90% and not greater than 110%. Moreover, the maximum width in the circumferential direction is set a mechanical angle within 30 degrees. This changes the magnetic flux amount intersecting stator coils so as to make an induction voltage waveform of the stator coils (31a, 31b) to be a shape suppressing generation of torque causing vibration. As compared to the conventional technique, vibration level is significantly suppressed.

Description

technical field [0001] The present invention relates to a stepping motor, and more particularly, to a stepping motor capable of suppressing vibration, improving quietness, and the like. Background technique [0002] Stepping motors are used in various devices such as devices requiring position control. For example, in the air-conditioning device for motor vehicles, stepping motors are used as drive motors to control the opening of various air-conditioning dampers, and salient pole (magnetic pole teeth) type permanent magnet stepping motors are often used ( For example, refer to Patent Document 1). [0003] In such a stepping motor, it is difficult in its configuration to avoid vibrations caused by torque changes when rotation starts and stops. In particular, how to reduce vibration is an important issue when high quietness is required, such as an air conditioner for a vehicle. [0004] Among the countermeasures to reduce this type of vibration, there is a simpler method: ...

AI Technical Summary

Problems solved by technology

[0005] However, in order to obtain a drive signal having a desired waveform as described above, it is necessary to add a circuit for shaping the waveform of the drive signal to a desired signal waveform in the drive signal generation circuit provided inside or outside the stepping motor. The increase in the number of parts leads to an increase in the price of the device, and when there is a strong demand for the miniaturization of each structural part such as an air conditioner for a vehicle, it is difficult to implement a method of adding electronic parts to a stepping motor that does not have enough internal space.

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