KR100531255B1 - An electric motor rotor with permanent magnets - Google Patents

Abstract

The present invention relates to an electric motor rotor having a permanent magnet. The rotor comprises magnets 20 seated on the cylindrical outer surface 11 of the core 10 of the rotor and a pair of annular caps 40. Each annular cap 40 is seated and secured to an adjacent end face 12 of the core 10. The annular caps 40 limit the axial displacement of the magnets and provide a stop for the bidirectional circumferential displacement of each magnet 20. Facing side edges 21 of a pair of continuous magnets 20 are positioned by the annular caps 40 to define a predetermined minimum circumferential distance.

Description

AN ELECTRIC MOTOR ROTOR WITH PERMANENT MAGNETS}

The present invention relates to a structure of a brushless electric motor rotor having a metal core for supporting circumferentially arranged magnets on an outer surface thereof.

In the known construction of a brushless electric motor rotor, permanent magnets, usually in the form of an arched plate, are held on a cylindrical core, which is usually iron, the cylindrical core being laminated or bulky. And is mounted around the shaft of the electric motor. In these rotors, the magnets are installed in a housing defined by a longitudinal opening inside the metal core, or are seated on the cylindrical outer surface of the core by different fixing means, the fixing means being centrifugal force and electric motor. It is designed to give the mechanical structure the necessary resistance to operation.

In the rotor structure in which the magnets are attached to the cylindrical outer surface, one of the assembly problems is due to the need to keep the longitudinal axis of the magnets parallel to the longitudinal axis of the core. Such positioning is usually obtained by providing external radial protrusions incorporated into the surface of the rotor core, or by equipment for assembling the unit during the manufacturing process.

These techniques have the disadvantage of making the positioning of the magnets on the rotor surface difficult during manufacture, which positioning must be accurate in angle and provide some angular distance between the magnets. This difficulty is due to the longitudinal degrees of freedom present during assembly.

If the magnets are supported simultaneously on two opposing projections, because different thermal expansions of both the magnet and the core may generate high mechanical stresses concentrated on the magnets in the support area, either during operation of the motor or during mounting of the rotor. The positioning of the magnets on the rotor surface by the outer radial protrusions of the core causes assembly difficulties due to the magnets being supported by only one of the protrusions. Since the magnets are formed of a ceramic material, these stresses can cause failures caused by the destruction of the magnets. In some cases, even losing on just one protrusion can be dangerous.

After forming the rotor with the magnets correctly positioned around the core, the rotor must be positioned and mounted around the motor shaft when positioning means are required to align the rotor around the motor shaft during assembly of the rotor. do. These positioning means also position the rotor for subsequent magnetization of the magnets, which magnetization must be carried out at a predetermined position of the magnets relative to the motor structure. This positioning function is typically provided by bores formed in the magnetic core of the rotor, which reduces the amount of working material in the core, without compromising the efficiency of the motor or damaging the performance of the motor. Limit the minimum size rotors can have.

Another drawback of the prior art is that when the automatic positioning equipment is used, the manufacture of the rotor is high, depending on the high investment required.

1 is a longitudinal cross-sectional view schematically showing a rotor having an annular cap of the present invention disposed in accordance with a mounting embodiment.

2 is a perspective view showing a rotor with an annular cap of the present invention.

3 is a top plan view of the annular cap of FIG.

4 is a side view illustrating the annular cap of FIG. 3.

5 is a perspective view of the annular cap.

6 is a plan view schematically showing the rotor with a pair of annular caps acting on the magnets of the rotor.

7 is a partial plan view schematically showing another embodiment of the annular cap of the present invention.

FIG. 8 is a diagram schematically showing details of the periphery of the annular cap according to another embodiment of the present invention, for example using the cap shown in FIG. 7.

It is therefore an object of the present invention to provide an electric motor rotor with permanent magnets which makes it possible to accurately seat a magnet on the outer surface of the rotor core without the need for structural modification of the core or the need for precision devices. .

Another object of the present invention is to provide a motor rotor of the type which has a permanent magnet and simplifies the automatic mounting process of the rotor.

In order to achieve the above and other objects, according to the present invention, there is provided a motor rotor with a permanent magnet, comprising a core having a cylindrical outer surface on which magnets with opposite side edges are seated. The rotor includes a pair of annular caps, each annular cap seated and secured to an adjacent end face of the core, the annular caps limiting the axial displacement of the magnets, and each magnet Each of the annular caps is provided by the annular caps to provide a stop for a bidirectional circumferential displacement of the opposing side, wherein the facing side edges of the pair of continuous magnets are positioned by a predetermined minimum circumferential distance; Having positioning means, each of the positioning means limiting the circumferential displacement of each magnet in one direction of circumferential displacement, The circumferential displacement of each magnet is limited in both directions by two circumferential displacement limiting stops provided on one of the annular caps, the circumferential displacement limiting stops acting on the same magnet, An electric motor rotor with a permanent magnet is provided, which is seated at opposite ends.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

The present invention relates to a motor rotor of the type having a permanent magnet, which has a core (10) fixed around an extension of the motor shaft (S), the cylindrical outer surface (11) of the core (10). In the following, magnets 20, usually in the form of an arcuate magnet plate, are seated, and the magnets 20 each have a side edge portion 21 in which each of the side edge portions 21 faces an adjacent magnet. ) With respect to the core 10 so as to be spaced apart by a predetermined minimum distance, for example by adhesion or by the action of a tubular cylindrical cap 30.

According to the invention, the electric motor rotor also further comprises a pair of annular caps 40 made of a material having a significantly lower permeability than that of the core 10. The annular cap 40 is preferably made of a nonmagnetic material, each annular cap 40 being secured to the core 10 so as to cover or not cover the adjacent end of the magnet 20. It is seated on an adjacent end annular face 12. The annular caps 40 limit the axial displacement of the magnets 20 and provide a stop for the bidirectional circumferential displacement of each magnet 20. The facing side edges 21 of the pair of continuous magnets 20 are arranged in advance for the two continuous magnets 20 each of the side edges 21 during positioning of the magnets 20 on the rotor core. It is limited by the annular caps 40 so as not to exceed a defined minimum circumferential distance.

Each annular cap 40 bears circumferential displacement limiting stops 42 from its outer circumferential edge 41, which circumferential displacement limiting stops 42, for example, annular cap 40. In one piece. Each circumferential displacement limiting stop 42 limits the circumferential displacement of each magnet 20 in one direction of circumferential displacement. Each magnet 20 has a bidirectional circumferential displacement, which is limited by at least two circumferential displacement limiting stops 42. Each circumferential displacement limiting stop 42 is mounted to one of the annular caps 40 adjacent the end of the side edge 21 of the magnet. The circumferential displacement limiting stops 42 are adjacent to the ends of the opposite side edges 21 of the magnet.

In another embodiment of the present invention, at least one of the annular caps 40 is provided with circumferential displacement limiting stops 42 that limit bidirectional circumferential displacement of each magnet 20.

In one solution of the present invention, circumferential displacement limiting stops 42 are provided that are circumferentially aligned internally in accordance with the circumferential alignment of the outer surfaces of the magnets 20.

Fixing the annular cap 40 to the core 10 is performed suitably by the holding member 50, for example. The retaining member 50 extends longitudinally through the core 10 and secures the annular caps 40 to each other and also secures the annular caps 40 to the core 10.

Although not shown, other forms of means (such as rivets, screws, etc.) for retaining the annular caps 40 in the core 10 are possible within the inventive concept shown herein. This means may or may not extend over the entire axial length of the rotor core.

In the illustrated embodiments, each annular cap 40 is integrally provided with an outer annular flange 43, for example on a plane parallel to the face of the annular cap 40. The circumferential annular flange 43 is, for example, a circumferential displacement limiting stop 42 in the form of an axial protrusion which is integral with the annular cap 40 and protrudes from the surface of the circumferential annular flange 43. ) And these circumferential displacement limiting stops 42 are at an angle from each other and act on the ends of the side edges 21 of each magnet 20 when mounting the magnets around the rotor core. To provide a circumferential stop. The outer circumferential annular flange may be formed parallel to or parallel to the face of the annular cap 40.

The circumferential displacement limiting stops 42 are, for example, predetermined to be sufficient to allow deformation of the stop at which the circumferential displacement limiting stops 42 initiate the thermal expansion of the magnet acting as the circumferential displacement limiting means. Should have flexibility. The final deformation of the circumferential displacement limiting stops 42 avoids the high stress on the magnets 20 and the damage that results as a result of the magnets.

The annular caps 40 are attached to the rotor when, by their circumferential displacement limiting stops 42, the facing side edges 21 of the continuous pair of magnets 20 are mounted around the rotor core. It is reliably arranged at a predetermined predetermined minimum distance between the magnets.

According to the embodiment shown in FIGS. 1 to 6, the minimum circumferential distance is achieved by the cooperative action of the annular caps 40 on both sides. In this case, the annular caps 40 have one annular shape such that each of their circumferential displacement limiting stops 42 is circumferentially shifted by a value disposed in the magnets 20 with a minimum circumferential distance between the magnets. The cap 40 must be arranged with respect to the other annular cap 40. In the embodiment shown in FIGS. 7 and 8, circumferential displacement limiting stops 42 are provided in each annular cap 40 to define a minimum circumferential distance between each two adjacent magnets 20. have.

In the embodiment shown in FIG. 8, the circumferential displacement limiting stops 42 are arranged radially apart from each other by some angle so as to avoid mutual contact in any deformation condition of the magnets 20.

The length of the circumferential displacement limiting stop 42 is determined taking into account possible dimensional variations (and margins of error) of the length of the magnet 20. In the structure of FIGS. 7 and 8, the distance between each two adjacent circumferential displacement limiting stops 42 associated with each magnet 20 represents the variation (and margin of error) of the circumferential extension of the magnets 20. It is decided in consideration. The circumferential displacement limiting stop 42 of this solution is designed to ensure the desired relative positioning between the magnets when assembling the magnets 20 to the rotor core. However, the circumferential displacement limiting stop 42 does not necessarily contact the magnet 20 during this assembly condition or even after obtaining the retention condition of the magnets in the rotor core.

In the structure of FIG. 8, the annular caps 40 are attached to the rotor such that the respective circumferential displacement limiting stops 42 acting on the same side edge 21 of each magnet 20 are axially aligned with each other. do. However, in order to achieve positioning with a desired minimum distance, it is sufficient that only one of the annular caps have adjacent circumferential displacement limiting stops 42 which respectively limit the positioning of each magnet 20.

According to the embodiment shown in FIGS. 1 to 6, a pair of circumferential displacement limiting stops 42 of one of the opposite side edges 21 of each magnet 20 mounted to the core 10 is provided. Annular caps 40 are attached to the core 10 to respectively act at adjacent ends.

In the embodiments shown, the circumferential displacement limiting stops 42 are spaced at equal intervals from each other with respect to their action on the magnets 20. However, the distribution of the circumferential displacement limiting stops 42 throughout the outer circumferential annular flange 43 of each annular cap 40 acts on the circumferential displacement limiting stops 42 for each magnet 20. It is also possible to provide a variable spacing that is defined in relation to this.

Due to the level difference between the face of the annular cap 40 and its outer annular flange 43, it is possible to use a magnet having an axial length that can be larger or smaller than the axial length of the rotor core.

By attaching at least one of the annular caps 40 to the core 10, circumferential positioning for retaining each magnet 20 in the core 10 is determined. Also, by assembling the annular cap 40 adjacent the lower end face of the core 10, the axial retention of the magnets 20 with respect to the core 10 is confirmed. By this holding, each magnet 20 is seated on the inner surface of the outer annular flange 43 of the annular cap 40 disposed at the bottom of the core 10.

In an embodiment in which the circumferential displacement limiting stop 42 is in the form of an axial protrusion, the axial protrusion is formed of the same material as that of the corresponding annular cap 40, and (stamping, casting and injection molding). Or the like, and may be integrally incorporated into the annular cap 40, and may be manufactured by one of bending, stamping, bending, or the like, or riveting, welding, or the like. It may be attached to each annular cap 40 by any suitable method such as gluing or mechanical fastening. An axial protrusion attachable to the annular cap 40 may be obtained from a material different from the material forming the annular cap 40. The cooperative action of the pair of annular caps 40 on the core 10 determines the circumferential and longitudinal alignment of the magnets 20 seated on the rotor core.

According to the invention, each annular cap 40 is further provided with a positioning means 44 in the form of a portion which is drawn upwardly from the surface of the bore or annular cap 40. The means 44 enable angular positioning of the rotor upon assembly of the magnets (or finally during the formation or placement of the annular cap around the magnets). During assembly at any one of the mounting positions of the magnet or annular cap, when the cap is mainly annular, the positioning means 44 need to provide a bore in the magnetic core of the rotor, and the motor shaft S This eliminates the need to lock (lock) the rotor circumferentially.

In this structure, assembling involving accurate circumferential and longitudinal alignment of the magnets 20 with respect to the core 10 is achieved in a simple manner and does not form a bore in the core 10, it is possible to use a sophisticated device or There is no need to remove material from the core 10, which makes the motor more efficient and concise. The circumferential displacement limiting stopper 42 also avoids the concentration of mechanical stress due to heat, which usually causes destruction of the magnetic material.

For each annular cap 40 there are shown structures in which the magnets 20 are firmly arranged, in particular with respect to the respective circumferential annular flange 43 and the circumferential displacement limiting stop (axial projection) 42. 6 to 8, by means of these structures, the shaft is arranged between the magnet 20 and the outer annular flange 43 of the respective annular cap 40 and the circumferential displacement limiting stop (axial projection) 42. An assembly having directional and circumferential clearances is possible.

Although not shown, the annular cap 40 of the present invention may have a circumferential displacement limiting stop 42 in the form of a radial protrusion. Each radial protrusion may be provided with an axial extension orthogonal to the face of the annular cap, the radial protrusion serving as a circumferential locking means of at least one adjacent magnet 20.

Claims (15)

In a motor rotor with a permanent magnet, comprising a core 10 having a cylindrical outer surface on which magnets 20 with opposite side edges 21 are seated, The motor rotor includes a pair of annular caps 40, each annular cap 40 seated and secured to an adjacent end face 12 of the core 10, and the annular cap 40. Limit the axial displacement of the magnets 20 and also provide a stop for bidirectional circumferential displacement of each magnet 20, and face the side edges of the pair of continuous magnets 20. (21) are positioned by the annular caps 40 to define a predetermined minimum circumferential distance, each annular cap 40 having positioning means, each of which positioning means being Two circumferential displacements of each of the magnets 20 in one direction of circumferential displacement, each circumferential displacement of each of the magnets 20 being provided to one of the annular caps 40, respectively. Restricted in both directions by the directional displacement limiting stop 42 The motor rotor with a permanent magnet, characterized in that the circumferential displacement limiting stops (42) acting on one magnet (20) are seated at opposite ends of the side edges (21) of the magnet (20). 2. The circumferential displacement limiting stops (42) provided in both the annular caps (40) and acting on the same magnet (20) are provided in the adjacent side edges (21) of the magnet (20). An electric motor rotor with permanent magnets, each seated at its end. 3. The adjacent circumferential displacement limiting stops (42) of the annular cap (40), each of which limits the circumferential displacement of the magnet (20) in one displacement direction, between the magnets (20). A motor rotor with permanent magnets, characterized in that they are spaced apart from each other by a distance corresponding to a minimum circumferential distance to be maintained at. 2. The motor rotor according to claim 1, characterized in that the annular cap (40) is integrally provided with an outer annular flange (43) supporting the circumferential displacement limiting stops (42). . 5. A motor rotor according to claim 4, characterized in that the circumferential displacement limiting stops (42) are formed in the form of axial protrusions attached to the outer annular flange (43). 6. The motor rotor according to claim 5, wherein the axial protrusion is integrally formed with the annular cap (40). 7. The axial protrusion according to claim 6, wherein the axial protrusion is stamped, folded, and bent in an extension of the outer annular flange 43 of the annular cap 40. An electric motor rotor with a permanent magnet, characterized in that it is manufactured by one of. 8. The motor rotor of claim 7, wherein the axial protrusion is attached by one of riveting, welding, gluing, and mechanical fastening. The rotor of claim 1, wherein the annular cap (40) is obtained by one of stamping, injection molding and casting. A permanent according to claim 1, characterized in that the annular cap (40) and the circumferential displacement limiting stop (42) are made of a material having a lower permeability than that of the core (10). Electric motor rotor with magnet. The method of claim 1, wherein the angular positioning of the rotor with respect to the motor shaft (S) during assembly of the magnets 20 during any of the assembly conditions of the magnets 20 and the annular cap (40). The annular positioning means 44 having at least one of a function, a function of forming a cap around the magnets 20, and a function of circumferentially locking the rotor with respect to the motor shaft S. An electric motor rotor with a permanent magnet, characterized in that provided on the outer surface of each of the caps (40). 2. An annular cap (40) having an outer annular flange (43) and axial protrusions is obtained by one of stamping, injection molding, and casting, and the outer annular flange (43) and the axial direction. The projections are obtained by one of bending and bending the annular cap (40) during a stamping operation. delete delete delete