JPS58127552A - Brushless motor - Google Patents

Abstract

PURPOSE:To reduce the entire volume of an outer rotor brushless motor of flat shape or the like by effectively utilizing a space by disposing a speed detector, a drive circuit and the like between the inner surface of the stator and the outer surface of a rotational shaft. CONSTITUTION:A brushless motor is composed of a stator having a coil 7 and a core 6, a rotor having a permanent magnet 3 covered with a yoke 2 at the outer periphery, a rotational shaft 1, a magnetic sensitive element 8, a speed detector 10, and a motor drive circuit and the like. The detector 10 and the drive circuit 22 are at least disposed between the inner surface of the stator and the outer surface of the shaft. For example, a speed generator, a speed detector 10 such as a rotary encoder and a motor drive circuit 11 such as a power transistor are disposed in the space between the core securing cylinder 13 secured to the base frame 4 of a flat motor and a housing 5.

Description

[Detailed Description of the Invention] The present invention provides a brushless motor in which a rotor rotates around the outer circumference of a stator (hereinafter referred to as an outer rotor brushless motor).
The present invention relates to a brushless motor in which a speed detector, a drive circuit, etc. are arranged in the space between the inner surface of the stator and the outer surface of the rotating shaft.

Figure 1 shows the structure of a conventional outer rotor brushless motor. A yoke 2 to which a rotating shaft IK is fixed and a permanent magnet 3 attached to the yoke constitute a rotor. An iron core 6 is fixed to a housing 5 fixed to a pace frame 4, and a coil 7 is wound around the iron core 6. The position of the rotor permanent magnet 3, of which the stator is composed of the iron core 6 and the coil 7 I/C, is detected by the magnetically sensitive element 8, and in synchronization with this, the coil 7 is excited and the rotor is rotated. It is.

FIG. 2 shows the structure of this flat type motor with a large diameter and a low height.

The speed detection device 10 is located at the base 7 of the motor in Figure 1.2.
The drive circuit is also placed outside the motor.

The iron core between the part of the iron core 6 in FIG. 2 where the coil 7 is wound and the fixed part of the Howdan Gallo (part 14 in FIG. 2) constitutes a magnetic circuit. Magnetic saturation at 14 parts cannot be achieved due to the structure, so the number of iron cores may be reduced.

The purpose of the present invention is to reduce the number of iron cores in section 14 in FIG. 2 and arrange a speed detector, drive circuit, etc. in the space between the housing and the housing, thereby making effective use of the space.

Hereinafter, the present invention will be explained in detail based on Examples.

FIG. 3 shows an embodiment of the invention.

3 and 4 show embodiments of the present invention.

A yoke 2 to which a permanent magnet 3 is adhered is fixed to a rotating shaft 1 and rotates. 4 has a 7-pace frame, and the ib housing 5 and the yoke fixing cylinder 13 are fixed to each other.

6 is a yoke on which a coil 7 is wound. 8 is a magnetically sensitive element that detects the polarity of the permanent magnet 3 and provides the excitation timing of the coil 7. 9 is a bearing. 10 is a speed detection device such as a speed generator or a rotation encoder.

11 is a motor drive circuit such as a power transistor for passing current through the coil. 12 is bearing 9
This is a fixed ring for preloading. 13 is a cylinder for fixing the yoke 6 and is fixed to the base frame 4.

In another embodiment, several arm-shaped iron cores were left for fixing to the housing, and the remaining parts were left blank to create a space in which a drive circuit and a speed detector were placed.

As described above, a space is created by cutting out a part of the iron core and arranging a speed detector, a drive circuit, etc. in the space, and the method of cutting out a part of the iron core is not limited to the above two sides.

According to the present invention, the speed detection device and drive circuit, which were conventionally attached to the outside of the motor, can be housed inside the motor, and the volume of the entire motor including the drive circuit and speed detection device can be reduced. Ta. Motors built into thin devices must be flat motors with a lower height compared to the diameter. The present invention is effective for flat-shaped motors, and can be used to reduce the volume occupied by motors in VTRs, information equipment, digital magnetic memories, etc., which are designed to be thinner.

[Brief explanation of drawings]

1 and 2 are sectional views of a conventional outer rotor, FIG. 3 is a plan sectional view of a motor based on the present invention, and FIG. 4 is an elevational view of a motor based on the present invention. 1 is a rotating shaft, 2 is a yoke, 3 is a permanent magnet, 4 is a pace frame, 5 is a housing, 6 is an iron core, 7 is a coil, 8 is a magnetically sensitive element, 9 is a bearing, IO is a speed detector, 11 is A drive circuit 12, a fixing ring 13 a cylinder for fixing the yoke, and 14 a part of the yoke 6. Applicant: Souwa Seikosha Co., Ltd. Agent: Patent Attorney Mogami

Claims (1)

[Claims] A brushless motor includes a stator consisting of a coil and an iron core, a rotor consisting of a permanent magnet whose outer periphery is covered with a yoke, a rotating shaft, a magnetically sensitive element, a speed detector, and a motor drive circuit, at least the speed detector. , a brushless motor characterized in that a drive circuit is disposed between the inner surface of the stator and the outer surface of the rotating shaft.