JPH0217838A - Permanent magnet synchronous motor - Google Patents

Abstract

PURPOSE:To prevent the slippage or coming off of a permanent magnet by connecting a tile-like permanent magnet to the peripheral surface of a cylindrical yoke, providing a protective pipe consisting of a shape memory material to the peripheral surface of the magnet and diecasting a formed rotor body. CONSTITUTION:A rotor 1 laminates a doughnut type electromagnetic steel plate 2 and is clamped by engaging an interlocking projection 3, and a rotor body 8 is constituted of a yoke 5 with a force-fit hole of a shaft to the inside thereof, four pieces of tile-like permanent magnets 6 adhered to the peripheral surface of the yoke and a protective pipe 7 consisting of a shape memory alloy fitted and inserted in the peripheral surface of the permanent magnet 6, an aluminum diecast is applied to the body to fix the permanent magnet 6 firmly to the yoke 5, and, at the same time, an end ring 9 is formed to constitute. A cylindrical shape having a minor diameter with the same size as that of an outside diameter of the peripheral surface of the permanent magnet 6 or a little short is memorized to the protective pipe 7.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a permanent magnet synchronous motor using permanent magnets in its rotor.

(B) Conventional technology Conventionally, the rotor of this type of permanent magnet synchronous motor has a plurality of tile-like structures on the outer peripheral surface of a cylindrical yoke, as described in, for example, Japanese Patent Application Laid-Open No. 57-177263. After gluing a permanent magnet, the outer circumferential surface of the magnet is coated with a synthetic resin containing glass fiber, or
As described in the publication, a plurality of tile-shaped permanent magnets are adhered to the outer peripheral surface of a cylindrical yoke, and then the outer peripheral surface of the magnets is covered with a protective pipe made of a non-magnetic material such as stainless steel. Many other proposals have been made. These devices protect the magnet from damage by using a pipe made of synthetic resin containing glass fiber or a non-magnetic material.

(c) Problems to be Solved by the Invention However, according to the former method, unevenness is likely to be formed on the outer peripheral surface of the rotor due to glass fibers, etc., and the circularity of the rotor is reduced. In the latter case, the outer circumferential surface of the rotor is a metal pipe, making it easy to adjust the air gap size, but the magnets are fixed to the yoke with adhesive, etc. There was a problem that there was a risk that the magnet would shift in the axial direction and fall off during rotation.

For this reason, as a means of fixing the magnet, a method has been proposed in which a non-magnetic pipe is inserted into the magnet and then aluminum die-casting is performed, but in this case, molten metal flows into the gap between the pipe and the magnet during die-casting. The problem is that the pipe swells locally due to the pressure of the hot water, and that it is difficult to create an air gap when it is incorporated into a motor.

The present invention has been made in view of the above, and an object of the present invention is to provide a permanent magnet synchronous motor that completely prevents displacement and falling off of rotating permanent stones and allows easy adjustment of air gap dimensions.

(d) Means for Solving the Problems The present invention comprises a cylindrical yoke, a plurality of tile-shaped permanent magnets joined to the outer circumferential surface of the yoke, and a shaped magnet fitted to the outer circumferential surface of the magnet. A rotor body is formed from a protection pipe made of a memory material, and the rotor is formed by die-casting this body from aluminum, zinc, or the like.

(E) Function The permanent magnet synchronous motor of the present invention has the above-mentioned structure, which not only firmly fixes the permanent magnets to the yoke by die-casting and reliably prevents the magnets from shifting or falling off during rotation, but also prevents the magnets from being exposed to heat during die-casting. By returning the protective vibrator made of shape memory material to a pre-memorized shape, that is, a cylindrical shape with an inner diameter that is the same as or slightly smaller than the outer diameter of the permanent magnet, it is possible to almost eliminate the gap between the magnet and the pipe. This prevents molten metal from entering between the magnet and the pipe, thereby preventing local swelling of the pipe and improving the dimensional accuracy of the air gap.

(f) Example Embodiments of the present invention will be described below based on the drawings.

1 is a rotor that constitutes a permanent magnet synchronous motor. This rotor is constructed by laminating donut-shaped electromagnetic steel plates 2 and clamping them by engaging engagement protrusions 3, and forming a yoke 5 with a press-fit hole 4 for the shaft formed inside, and adhesive bonded to the outer peripheral surface of this yoke. A rotor main body 8 is formed by four tile-shaped permanent magnets 6 bonded together with an adhesive and a protective vibe 7 made of a shape memory alloy that is fitted onto the outer peripheral surface of the magnets. The permanent magnet 6 is firmly fixed to the yoke 5, and an end ring 9 is formed. Here, the shape memory alloy used as the material of the protective vibrator 7 is a unidirectional movement type whose main component is nickel, titanium, etc. The rotor constructed as described above is manufactured by the following method. First, York 5
Four permanent magnets 6 are fixed to the outer peripheral surface of the magnet with adhesive. Next, a rotor main body 8 is formed by fitting a protective vibe 7 made of a shape memory alloy having a diameter slightly larger than the diameter of the permanent magnet 6 onto the outer peripheral surface of the permanent magnet 6.

At this time, the protective vibe 7 is preliminarily memorized with a cylindrical shape having an inner diameter that is the same as or smaller than the outer diameter of the outer peripheral surface of the permanent magnet 6 by a micron order. Thereafter, the rotor body 8 is set in a mold and die-cast from aluminum.

By this die-casting, the permanent magnet 6 and the protective vibe 7 are integrally and firmly fixed to the yoke 5, and the end ring 9 is completely formed. Here, the protective vibrator 7 is completely heated by the heat during die-casting and is restored to the pre-memorized shape. That is, the protective vibrator 7 is reduced in diameter and tightly tightens the outer peripheral surface of the permanent magnet 6. As a result, the gap between the magnet 6 and the pipe 7 is almost eliminated.
It is possible to prevent molten metal from entering the gap during die casting, eliminate local swelling of the protective vibe 7, and improve the dimensional accuracy of the air gap.

In this embodiment, the protective vibrator 7 is made of a unidirectional movement type shape memory alloy mainly composed of nickel, titanium, etc., but it is also possible to use a copper-based memory alloy or a two direction movement type shape memory alloy. However, as long as it is a shape memory material that can bring the protective vibe and the magnet into close contact during die-casting, it does not depart from the scope of the present invention. Furthermore, the hot water used during die casting is not limited to aluminum or zinc.

(G) Effects of the Invention As described above, according to the present invention, it is possible to completely prevent the permanent magnet from shifting or falling off during rotation, and it is also possible to improve the dimensional accuracy of the air gap, resulting in excellent performance and reliability. Permanent magnet synchronous motors can be provided.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a rotor showing an embodiment of the present invention, and FIG. 2 is a longitudinal cross-sectional view of the rotor. 1... Rotor, 5... Yoke, 6... Permanent magnet, 7... Protective vibe, 8... Rotor 1 body.

Claims (1)

[Claims] (1) The rotor body consists of a cylindrical yoke, a plurality of tile-shaped permanent magnets bonded to the outer circumferential surface of the yoke, and a protective pipe made of a shape memory material fitted to the outer circumferential surface of the magnets. A permanent magnet synchronous motor characterized in that a rotor is formed by die-casting this main body from aluminum, zinc, etc.