JPH0261229B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plastic-bonded permanent magnet rotor having a hollow cylindrical or cup-like shape for electrically driven machines, especially small motors.

Such plastic-bonded permanent magnet rotors consist of a mixture of powdered permanent magnets and a plastic adhesive, which mixture is formed into a hollow cylindrical or pot-shaped rotor by pressing or, for example, injection molding. has been done. The surface of such a permanent magnet rotor is magnetized by alternating polarity poles.

In the case of such plastic-bonded permanent magnet rotors, there is a problem in centering and mounting the shaft inside the rotor. Due to the presence of a certain narrow air gap between the rotor and the stator, it must be ensured that the ring-shaped or rotor-shaped rotor is held securely and immovably on the shaft, and at the same time the coaxiality of the shaft and the rotor must be ensured. proper placement must be guaranteed. When manufacturing such a rotor, it is clear that the rotor cannot withstand tensile or tensile stresses. As a result, it was no longer possible to press-fit or injection mold the shaft directly into the magnet ring as economically as possible. This is because the body due to the resulting radial pressure is torn or partially destroyed.

It is already known to permanently arrange a shaft inside a thin permanent magnet ring made of oxide material for the rotor of an electric motor, in which case a cylindrical permanent magnet is supported by the shaft. The rotor is clamped between two supports provided with flanges, the flanges of which also act on the permanent magnet rotor in the axial direction so as not to be exposed to stresses in the radial direction. Furthermore, these supports made of plastic are constructed as pushers which are moved relative to each other in the axial direction, the shaft being press-fitted into one of the pushers and the other pusher being provided with ribs. . Such a fixed structure has the disadvantage that, during assembly, the hollow cylindrical permanent magnet rotor must be fitted into a device designed to position the outer peripheral surface of the rotor concentrically with respect to the axis. This increases assembly costs. Furthermore, since two supports configured as a push-piece are required and the manufacture of the supports must be carried out exactly coaxially, such a fastening structure as described above becomes an uneconomical structure (Germany). (Federal Republic Patent Application Publication No. 1212625).

The object of the invention is to provide a permanent magnet rotor of the above-mentioned type, which, while eliminating the above-mentioned disadvantages, makes it possible to fix the shaft to the rotor and at the same time automatically center the shaft inside the rotor. The goal is to provide the following.

In order to solve such problems, the present invention
It has a holding member which is disposed coaxially within the inner chamber of the permanent magnet rotor and is molded integrally with the permanent magnet rotor, and which is made of a non-magnetic material and which fixes the shaft inside the holding member. The fastening member and the fastening member are coupled by inserting the fastening member into the holding member or by press-fitting the fastening member into the holding member.

By means of the invention, an arbitrary permanent magnet rotor for electrically driven machines, especially small motors, which is constructed with simple measures and low assembly costs, is obtained, which permanent magnet rotor has a reliable fixing of the shaft. and at the same time guarantee accurate centering and thereby guarantee the maintenance of a constant air gap.

According to an advantageous embodiment of the invention, the retaining element, which is integrally formed and coaxially arranged with the permanent magnet rotor, has a ring-shaped cross-section. Moreover, the holding element can have another cross-sectional shape, for example a cruciform cross-sectional shape, as long as it is ensured that it is arranged coaxially within the interior space of the rotor. The tightening member that presses the shaft is
Depending on the cross-sectional shape of the holding element, the walls of the holding element are designed so as to be surrounded under the action of a clamping or pressing force. This ensures that the tensile or stretching forces are reduced.

According to a further advantageous embodiment, the mutually engaging walls of the clamping element and/or of the holding element are designed in a conical manner in order to ensure a reliable fixing of the clamping element. In order to obtain a further advantageous connection, the mutually engaging walls can additionally be glued.

The invention will be explained below with reference to the exemplary embodiments shown.

The rotor 1 shown in longitudinal section in FIG. 1 has a hollow cylindrical shape corresponding to the broken lines. As can be seen from Figure 2,
The rotor consists of a mixture of powdered permanent magnets, such as isotropic or anisotropic barium, strontium or lead ferrite, and a plastic adhesive. The mixture is formed into a rotor body by pressing or injection molding.

A retaining element 3 is arranged coaxially within the interior chamber 2 of the rotor and is further molded in one piece with the rotor during manufacture, this retaining element extending in the axial direction. In the illustrated embodiment, the holding element is tubular. As can be seen from FIG. 2, the holding member has a ring-like cross-sectional shape. Inside the holding member 3,
A clamping member 4 formed corresponding to the cross-sectional shape of the holding member is press-fitted. In order to ensure a fixed seating of the clamping element on the holding element, the mutually engaging parts can be designed conically.
The wall portions of the clamping element that engage with the holding element 3 can additionally be secured by gluing.

The clamping member 4 is made of injection moldable plastic;
For example, they are made of polystyrene or polyamide. In the embodiment described above, the clamping element has an annular groove in which the tubular retaining element engages. The clamping element 4 has a central hole 8 into which the rotor shaft 5 is press-fitted. This allows the clamping element 4 made of plastic to be attached to the centrally arranged shaft 5.
serves as a member for coupling with the permanent magnet rotor 1. Such a fastening arrangement has the advantage that the inserted clamping element 4 surrounds the wall 6 of the holding element 3 under the effect of a radial clamping or pressing force. Clamping forces acting in the radial direction are indicated by arrows in FIGS. 1 and 2.

The plastic-bonded permanent magnet body is not harmed by the pressing force. If, on the other hand, the shaft 5 were to be pushed directly into a plastic-bonded permanent magnet with holes, a radially outwardly acting force would be generated, which would tear the relatively brittle body. It will be. As shown in FIG. 2, the clamping member 4 has a cutout 12 in its inner region.
can have.

As can be seen in FIG. 2, the rotor is magnetized by alternating polarity poles. In this embodiment there are 12 poles, these poles are designated by the letters N and S in the drawing. The magnetic field extends in an arc, as evidenced by the dashed lines.

In the embodiment shown in FIG. 3, the permanent magnet rotor 1 has a conical shape. At the bottom 7 of the rotor top, a holding member 3 is arranged coaxially and is molded in one piece with the bottom of the rotor, the holding member having a cross-shaped cross-section as can be seen in FIG. are doing. The holding member 3 projects into the interior of the tip in the axial direction. A clamping element 4 with a corresponding cross-shaped recess is inserted into the holding element 3 and is fixedly connected by a clamping action. To ensure a secure connection, the clamping member 4
Alternatively, the mutually engaging walls 9 of the holding member 3 are formed to extend in a conical shape. The mutually engaging walls can additionally also be glued. The shaft 5 is pressed into the hole 8 of the clamping member 4 by a press fit. The clamping element 4 is made of injection moldable plastic, for example polyamide or polystyrene.

Tightening and centering of the clamping member 4 takes place on opposite sides of the cross-shaped holding member 3, as is clear from FIG. In this case, an air intermediate chamber exists between the end face 10 of the cross-shaped holding element and the face 11 of the clamping element.

In the case of such an embodiment as well, only a clamping or pressing force is exerted by the clamping member on the plastic-bonded retaining member made of a permanently magnetic material, and such forces do not harm the permanently magnetic material. Not added. The direction of the clamping force produced is indicated by the arrow in FIG.

The present invention is not limited to the above embodiments. The holding element 3 can also have other cross-sectional shapes, as long as the centering of the clamping element supporting the shaft is ensured.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of a first embodiment of a permanent magnet rotor according to the present invention, FIG. 2 is a sectional view taken along the - line in FIG. FIG. 4 is a sectional view taken along the - line in FIG. 3. 1... Rotor, 2... Inner chamber, 3... Holding member,
4...Tightening member, 5...Shaft, 6...Wall, 7...
Bottom, 8... Hole, 9... Wall, 10... End surface, 11
... Surface, 12 ... Notch part.

Claims (1)

[Scope of Claims] 1. A plastic-bonded permanent magnet rotor having a hollow cylindrical or cup-like shape for an electrically driven machine, which is arranged coaxially in the inner chamber of the permanent magnet rotor, and It has a holding member 3 integrally molded with the permanent magnet rotor, and the holding member and a fastening member 4, which is made of a non-magnetic material and has a shaft 5 fixed therein, hold the fastening member as a holding member. A permanent magnet rotor, characterized in that the rotor is coupled by press-fitting into the rotor. 2. The permanent magnet rotor according to claim 1, wherein the holding member 3 has a ring-shaped cross-sectional shape. 3. According to claim 2, the clamping member 4 is formed in accordance with the cross-sectional shape of the retaining member 3 so as to surround the wall 6 of the retaining member under the action of a clamping or pressing force. permanent magnet rotor. 4. The permanent magnet rotor according to claim 1, wherein the walls of the clamping member 4 and/or the holding member 3 that engage with each other extend in a conical shape. 5. The permanent magnet rotor according to claim 1, wherein the mutually engaging walls of the clamping member 4 and the holding member 3 are bonded together by adhesive. 6. A plastic-bonded permanent magnet rotor of hollow cylindrical or cup-like shape for electrically driven machines, which is arranged coaxially within the interior of the permanent magnet rotor and which is integral with the permanent magnet rotor. The holding member 3 has a holding member 3 molded into a shape, and the holding member and a fastening member 4 made of a non-magnetic material and having a shaft 5 fixed thereto are arranged so that the fastening member is inserted onto the holding member. A permanent magnet rotor characterized by being coupled together. 7. The permanent magnet rotor according to claim 6, wherein the holding member 3 has a cross-shaped cross-sectional shape. 8. The clamping member 4 is formed in accordance with the cross-sectional shape of the retaining member 3 in such a way that it surrounds the wall 9 of the retaining member under the action of a clamping or pressing force. Permanent magnet rotor. 9. The permanent magnet rotor according to claim 6, wherein the walls of the clamping member 4 and/or the holding member 3 that engage with each other extend in a conical shape. 10. The permanent magnet rotor according to claim 6, wherein the mutually engaging walls of the clamping member 4 and the holding member 3 are bonded together by adhesive.