JP2010252477A - Method for mounting permanent magnet on rotor of motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for mounting magnetized permanent magnets easily on the surface of the rotor core of a surface magnet type motor. <P>SOLUTION: A rotor is inserted into a cylindrical ring and is fixed together with the rotary shaft of the rotor coinciding with the longitudinal direction shaft of the cylindrical ring. Then, magnetized permanent magnets are inserted into the space formed between the fixed rotor and cylindrical ring down to a prescribed position. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for mounting a permanent magnet on a rotor of an electric motor, and in particular, a method for mounting a permanent magnet on the rotor of a motor having a rotor having a plurality of permanent magnets fixed to the outer periphery, a so-called surface magnet motor. About.

  In recent years, with the introduction of powerful rare earth magnets on the market, small-sized, high-efficiency, high-power permanent magnet synchronous motors using rare earth magnets for rotors have been developed, and power sources and controls in various fields. Used as a drive source.

  A surface magnet motor having a rotor on which a plurality of permanent magnets are fixed on the outer periphery is used in many fields as a motor with less noise and vibration. The method of magnetizing the permanent magnet of the rotor of the surface magnet motor is to magnetize after incorporating the magnet into the rotor (hereinafter referred to as post-magnetization), and to magnetize before incorporating the magnet into the rotor. It is roughly divided into methods (hereinafter referred to as first magnetization).

  In post-magnetization, a permanent magnet that is not magnetized is mounted on a rotor, and then the rotor is installed in a magnetizing device, and magnetized by passing a large current through the magnetizing device. Therefore, in the post-magnetization, it is necessary to manufacture a magnetizing device that meets the specifications of the rotor. In addition, after mounting an unmagnetized magnet on the rotor, there is a method of magnetizing the permanent magnet by incorporating the rotor into the stator and flowing a large current instantaneously through the stator winding (for example, Patent Document 1).

  On the other hand, since pre-magnetization is magnetized before the magnet is incorporated into the rotor, the stronger the magnet used, the easier it is to arrange and fix the magnet after magnetizing on the surface of the rotor core. is not. For this reason, the manufacture of a rotor by fixing a permanent magnet magnetized by pre-magnetization to the rotor is extremely difficult and is not generally employed.

JP 2006-304556 A

  When an electric motor is manufactured by a method in which an unmagnetized permanent magnet is fixed to a rotor and then magnetized, the permanent magnet on the rotor is placed on the end side in the rotation direction of the rotor and on the center side in the radial direction. There are parts that cannot be fully magnetized. For this reason, the total amount of magnetic flux cannot be increased, and the demagnetization resistance cannot be improved by designing the magnet to be thick (large in the radial direction).

  The present invention provides a method for simply attaching a magnetized permanent magnet to the surface of a rotor core of a surface magnet motor.

  That is, the present invention provides a method for mounting a permanent magnet on a rotor in the manufacture of an electric motor including a rotor having a plurality of permanent magnets on the outer periphery. Specifically, the rotor is inserted into a cylindrical ring. A gap formed between the fixed rotor and the cylindrical ring, the cylindrical ring and the rotor being fixed in a state where the rotation axis of the rotor and the longitudinal axis of the cylindrical ring coincide with each other. In addition, a magnetized permanent magnet is inserted.

  In a further embodiment of the method of the invention, the cylindrical ring is non-magnetic.

  In a further embodiment of the method of the present invention, the air gap includes a portion having a first radial spacing of the rotor and a portion having a second spacing, the first spacing being a permanent magnet. And the second distance is smaller than the thickness of the permanent magnet.

In a further embodiment of the method of the present invention, when the maximum thickness of the permanent magnet is set to t _max , the interval between the adjacent permanent magnets in the rotation direction of the rotor is 0.5 × t _max or less. It is characterized by.

  In a further embodiment of the present invention, before inserting the permanent magnet into the gap, an adhesive is applied to the outer peripheral surface of the rotor to which the permanent magnet is fixed.

  The method of the present invention eliminates the need for a magnetizing device for magnetizing a permanent magnet according to the shape and model of the rotor, so there is no need to manufacture a magnetizing device depending on the shape of the rotor, In addition, the power supply device attached thereto is not necessary, and the manufacturing cost of the surface magnet motor can be reduced.

  In the method according to the present invention, a permanent magnet magnetized by pre-magnetization is attached to the rotor, so that a reverse magnetic field and demagnetization due to high temperature that occur in the case of poor magnetization do not occur. Further, it is possible to manufacture a highly efficient surface magnet motor with a strong permanent magnet sufficiently magnetized without being limited by the power supply capacity of the magnetizing device. Furthermore, since a permanent magnet that is pre-magnetized is used, a thick permanent magnet that is sufficiently magnetized in the thickness direction (radial direction of the rotor) can be used. It becomes possible to produce a surface magnet motor with excellent proof stress.

It is a figure explaining the mounting method of the permanent magnet to the rotor of the surface magnet motor concerning the present invention. It is the elements on larger scale of the rotor surface of the conventional surface magnet electric motor magnetized by the back magnetization.

  A method of mounting a permanent magnet on a rotor of a surface magnet motor according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a view for explaining a method of attaching a permanent magnet to a rotor of a surface magnet motor according to the present invention. On the outer periphery of the rotor 1, guide convex portions 6 for defining the position of the permanent magnet 2 in the rotation direction (circumferential direction) of the rotor are arranged at regular intervals. The cylindrical ring 3 is made of a nonmagnetic material and has a cylindrical shape. The axial length of the cylindrical ring 3 has at least the axial length of the portion on which the magnet on the rotor is mounted, or more. The permanent magnet 2 attached to the rotor 1 is formed into a predetermined shape and magnetized by a known method before being attached to the rotor 1.

  The permanent magnet 2 is mounted on the rotor outer peripheral recess 4 between the guide protrusions 6 of the rotor 1 by the following method.

  The rotor 1 and the cylindrical ring 3 before mounting the magnet are arranged and fixed so that the rotation axis of the rotor 1 and the longitudinal axis of the cylindrical ring 3 coincide.

  The permanent magnet 2 is inserted into the gap defined by the outer periphery of the rotor 1 and the inner periphery of the cylindrical ring 3 while sliding in the axial direction. An adhesive for fixing the permanent magnet 2 may be applied in advance to the outer peripheral surface of the rotor 1 to which the permanent magnet 2 is fixed. Thereby, after the permanent magnet 2 is inserted to a predetermined position, it can be reliably fixed.

  The void has a void portion A having a radial interval t1 and a void portion B having a distance t2. An interval t1 between the rotor outer peripheral recessed portion 4 and the cylindrical ring inner peripheral surface 5 of the cylindrical ring 3 in the gap portion A is larger than the thickness tm of the permanent magnet. Further, the gap t2 between the radially outer end of the guide protrusion 6 and the cylindrical ring inner peripheral surface 5 in the gap portion B is smaller than the thickness tm of the permanent magnet.

  Since the cylindrical ring 3 is a non-magnetic material, the permanent magnet 2 slides along the rotor 1 side, which is a ferromagnetic material, when inserted between the rotor 1 and the cylindrical ring 3. Until inserted. Since the interval t2 is smaller than the thickness tm of the permanent magnet, the permanent magnet does not move over the guide convex portion 6 and move to the adjacent rotor outer peripheral concave portion 4 during insertion, and is stably inserted to a predetermined position. can do.

  FIG. 2 is a partially enlarged view of a rotor surface of a conventional surface magnet motor magnetized by post-magnetization.

  In the surface magnet motor, adjacent permanent magnets have opposite polarities. Therefore, in the case of post-magnetization, it is extremely difficult to magnetize all the permanent magnets uniformly in the rotation direction and radial direction (magnet thickness direction) of the rotor. Therefore, a part that is not magnetized or a part that is not sufficiently magnetized remains on the center side of the rotor and the both end sides in the rotation direction of the rotor of the permanent magnets after the magnetization. The width W2 in the rotation direction of the unmagnetized portion shown in FIG. 2 is substantially proportional to the thickness tm of the permanent magnet. Therefore, when the thickness tm of the permanent magnet to be mounted is increased, the width W2 of the non-magnetized portion is increased and the width W1 of the appropriately magnetized portion is decreased. As a result, it is difficult to increase the total magnetic flux amount of one pole.

Generally, the maximum demagnetizing force Ha applied to the permanent magnet of the permanent magnet motor is expressed by the following equation.
Ha = k · N · Ia / (P · tm)
Here, k is a constant, N is the number of turns of the coil per phase, Ia is the maximum current in normal driving, P is the number of poles, and tm is the thickness of the magnet. When the maximum allowable demagnetizing force in a range where the permanent magnet does not cause permanent demagnetization is Hm, the demagnetization resistance is expressed by Hm / Ha × 100. That is, when the thickness tm of the permanent magnet is increased, the demagnetization resistance of the permanent magnet can be improved.

  However, as described above, in the case of post-magnetization, if the thickness tm of the permanent magnet is increased, the width W1 of the portion that is appropriately magnetized is reduced. Therefore, demagnetization can be achieved by designing the permanent magnet to be thick. It is difficult to improve the yield strength.

  On the other hand, in pre-magnetization, individual permanent magnets can be magnetized under optimum conditions, so that they are uniformly distributed in the magnet thickness direction (rotor radial direction) and width direction (rotor rotation direction). It can be magnetized and the total amount of magnetic flux can be increased. Further, even if the magnet is made thicker, it can be uniformly magnetized in the thickness direction, so that an electric motor having a permanent magnet with high demagnetization resistance can be manufactured.

The method of attaching the permanent magnet to the rotor of the surface magnet motor according to the present invention is preferably configured so that the maximum thickness of the permanent magnet (fixed in the radial direction of the rotor) is fixed to the outer peripheral surface of the rotor. ) With respect to t _max , when the interval between the permanent magnets adjacent to each other in the rotation direction of the rotor is 0.5 × t _max or less, even better operational effects can be obtained.

  In the description of the embodiment of the present invention, the cylindrical ring has been described as a ring having a cylindrical shape, but the present invention is not limited to this, and the inserted permanent magnet is guided to a predetermined position. It should be noted that the same effect can be obtained even if it has such a shape. Furthermore, in the description of the embodiment of the present invention, the embodiment has been described in which the guide protrusion 6 that fixes the circumferential position of the permanent magnet is provided on the outer periphery of the rotor. However, the present invention is not limited to this. However, the outer periphery of the rotor does not have the guide protrusion 6, and the same effect can be obtained even with a structure having the guide protrusion protruding from the inside of the cylindrical ring toward the center of the rotor. Note that you can.

1: Rotor 2: Permanent magnet 3: Cylindrical ring 4: Rotor outer peripheral concave portion 5: Cylindrical ring inner peripheral surface 6: Guide convex portion

Claims (5)

In the manufacture of an electric motor including a rotor having a plurality of permanent magnets on the outer periphery, a method of mounting the permanent magnets on the rotor,
The rotor is inserted into a cylindrical ring, and the cylindrical ring and the rotor are fixed in a state where the rotation axis of the rotor and the longitudinal axis of the cylindrical ring coincide with each other,
Inserting a magnetized permanent magnet to a predetermined position into a gap formed between the fixed rotor and the cylindrical ring;
A method of attaching a permanent magnet to the rotor of an electric motor.   The method of claim 1, wherein the cylindrical ring is non-magnetic. The gap has a portion having a first interval in the radial direction of the rotor and a portion having a second interval,
The first interval is larger than the thickness of the permanent magnet (the radial length),
The second spacing is less than the thickness of the permanent magnet;
The method according to claim 1 or 2. When placing the maximum thickness of the permanent magnet and t _max, spacing of the permanent magnets adjacent to each other in the rotational direction of the rotor is less 0.5 × t _max, to any one of claims 1 to 3 The method described.   The method according to any one of claims 1 to 4, wherein an adhesive is applied to an outer peripheral surface of the rotor to which the permanent magnet is fixed before the permanent magnet is inserted into the gap.

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