JPS6176055A - Rotor for brushless motor - Google Patents

Abstract

PURPOSE:To exactly fix a permanent magnet for a permanent magnet rotor and easily detect magnetic poles with a hole element, by placing a ferromagnetic body in a hole of a metal fittings and by passing the magnetic flux of the permanent magnet outside the metal fittings easily. CONSTITUTION:The magnetic flux of a permanent magnet 4 of a permanent magnet rotor 10 flows concentrated on a ferromagnetic body 6 provided for a fixing appliance 5a as shown in the figure. The flux is detected by a hole element 8, and a switching element for control circuit is switched by the detection signal, and a stator winding 12 is controlled to be electrically conducted. In this manner, the permanent magnet 4 of the permanent magnet rotor 10 can be exactly fixed with metal fittings 5a, 5b and can be positioned, and the flux of the permanent magnet 4 is concentrated on the ferromagnetic body 6 through the metal fittings 5a, 5b, and so magnetic poles can be easily detected with the hole element 8.

Description

DETAILED DESCRIPTION OF THE INVENTION "Techniques of the Invention 4+ Eaves" The present invention relates to a rotor of a brushless motor that detects the magnetic pole position of a permanent magnet rotor using a Hall element or the like.

[Technical background of the invention and its problems]

In a brushless motor, the magnetic pole position of a permanent magnet rotor is generally detected by a Hall element or the like provided on the side of the rotor facing the permanent magnet, and the current flowing through the stator windings is controlled based on the detection signal. Conventionally, in such brushless motors, an adhesive is used between the permanent magnet and the rotating shaft.
Furthermore, heat-shrinkable tubes are wound around the outer periphery of the permanent magnet and fixed thereto, but these have the disadvantage that the adhesive force in the axial direction is weaker than the adhesive force in the radial direction. Attempts have been made to attach fixing devices made of non-magnetic material to the ends of the rotor magnets as a way to solve these drawbacks. A new problem arises in that the distance between the element and the element becomes large, making it difficult to detect the magnetic flux.

[Purpose of the invention]

The present invention can securely fix a permanent magnet to a permanent magnet rotor,
Another object of the present invention is to provide a brushless motor rotor whose magnetic poles can be easily detected using a Hall element or the like.

[Summary of the invention]

The present invention fixes both axial ends of the permanent magnets of a permanent magnet rotor with fixtures made of non-magnetic material, and also provides holes in a part of the fixture facing the permanent magnets on the side where the Hall element is installed. The rotor of a brushless motor has a structure in which a ferromagnetic material is interposed in this hole, and by interposing a ferromagnetic material in the hole of the fixture, the magnetic flux of the permanent magnet can easily pass through to the outside of the fixture. This is what I did.

[Embodiment of the Invention] The present invention will be described below with reference to an embodiment shown in FIGS. 1@J to 4. FIG. 1 is a perspective view of the stator of a brushless motor, FIGS. 2(a) and ib) are a front view and an H-B sectional view of a fixture for fixing permanent magnets to the rotor, respectively, and FIG. is an upper half sectional view of the brushless motor. In the figure, the frame 1 is a frame of a rotating electric machine, and a stator 3 having a winding 12 wound thereon is attached to the inside of the frame 1, and brackets 2 are provided at both ends. The rotor 10 is supported by a bracket 2Vc via a bearing 14, and the Hall element 8 is attached to the bracket 2 via a spacer 13 and a Hall element printed circuit board 7, facing the side end surface of the rotor 10. The stator 10 has a permanent magnet 4 on its outer periphery, and non-magnetic fixtures 5a and 5b are attached to both ends thereof to support the axial force of the permanent magnet.

Of these, on the fixture 5a on the Hall element side, ferromagnetic bodies 6 are provided at four equally spaced locations approximately in the center of the end face of the permanent magnet, as shown in FIG. 2(a).

This fixture 5a not only fixes the rotor with a permanent magnet, but also positions the rotor in the radial direction when adhering the permanent magnet. 1
Reference numeral 1 designates a control circuit protection cover, inside which a circuit element 9 of the control circuit is attached via a spacer 13.

Next, the operation of one embodiment of the present invention constructed as described above will be explained. FIG. 4 is a diagram showing the magnetic flux of a permanent magnet with a ferromagnetic material at one end, and the same reference numerals as in FIGS. 1 and 2 are used. The magnetic flux of the permanent magnets of the permanent magnet rotor flows in a concentrated manner through the ferromagnetic body 6' provided on the V1 fixture 5atC, as shown in FIG. The Hall element detects this magnetic flux, and the detection signal switches the switching element of the control circuit to control the energization of the stator winding 12.

According to the above-mentioned embodiment, the permanent magnets of the permanent magnet rotor can be securely fixed and positioned using the fixture, and the magnetic flux of the permanent magnets is concentrated on the ferromagnetic material and passed through the identification fixture, so that the permanent magnets of the permanent magnet rotor can be reliably fixed and positioned. Since the magnetic pole can be easily detected by the element, the energization control of the stator winding 12 can be performed reliably, improving reliability.

In the above-described embodiment of the present invention, the ferromagnetic material 6 is attached to the fixture 53, but the ferromagnetic material is driven into the permanent magnet, a convex portion is provided at the end of the permanent magnet, etc., and the ferromagnetic material 6 is fixed. A permanent magnet may be fixed to the tool by providing a ferromagnetic material or a hole that fits into a convex portion of the magnet.

〔Effect of the invention〕

As described above, according to the present invention, the permanent magnets of the permanent magnet rotor can be reliably fixed and positioned at R1q, and the magnetic poles can also be easily detected by the Hall element.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the rotating shaft of a brushless motor, Figure 2 (
a) and (bl are the front view of the fixture and its BB cross-sectional view, the third factor is a cross-sectional view of the upper body of the brushless motor, and the fourth factor is a cross-sectional view of the upper body of the brushless motor.
Figure 2 is a diagram showing the magnetic flux of a permanent magnet in a state where it has a ferromagnetic material at one end. 4...Permanent magnet, 5a, 5b... Fixture. 6...Ferromagnetic material, 8...Hall element. Agent: Patent attorney Kensuke Chika (and 1 other person) Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1. A brushless motor in which the rotational position of a permanent magnet rotor is detected by a Hall element and the stator windings are sequentially energized according to the detection output, wherein the permanent magnets of the permanent magnet rotor are Both ends in the axial direction are fixed with fixtures made of a non-magnetic material, and a hole is provided in at least one part of the fixture facing the permanent magnet, and a ferromagnetic material is interposed in this hole. A brushless motor rotor characterized by: 2. The rotor of a brushless motor according to claim 1, wherein the ferromagnetic material is formed in the hole of the fixture made of a non-magnetic material. 3. The rotor of a brushless motor according to claim 1, wherein the ferromagnetic material is formed at an end of the permanent magnet.