JP2009011051A - Motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor which can be manufactured more inexpensively by promoting simplification of the magnet profile. <P>SOLUTION: In a motor having a stator where a pair of magnets are arranged at positions facing each other across the center of the rotor in a yoke while facing the same poles each other, the pair of magnets are formed planarly. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a motor, and in particular, has a stator in which a pair of magnets having the same poles facing each other are disposed at positions facing each other across the central axis of a rotor in a yoke that receives the rotor inside. It relates to motors.

  An inner rotor type motor using a stator in which a plurality of magnets are arranged side by side on the inner peripheral surface of a cylindrical yoke so that the magnetic poles are staggered is known (see, for example, Patent Document 1).

  In this motor, magnets with a uniform thickness are arranged opposite each other with a small gap over the entire outer circumference of the rotor (armature), and the outer contour of the motor is substantially a perfect circle. It was. Therefore, it has been virtually impossible to reduce the thickness of the motor.

In order to cope with such inconveniences and realize a thinner motor, the same applicant as the present invention accepts a rotor as a stator of an inner rotor type motor inside a yoke whose outer contour is generally rectangular (oval). And a pair of homopolar magnets are arranged at positions that are line-symmetric with respect to the central axis of the rotor, and both the rotor and the pair of magnets have different polarities from the pair of magnets. Japanese Patent Application No. 2006-260163 has proposed a circular arc surface that is opposed to the outer peripheral surface with a minute gap.
JP 2003-324868 A

  However, this improved stator has a disadvantage in that the yield is low because cutting is required to form an arc surface corresponding to the outer peripheral surface of the rotor. In particular, sintered Nd magnets and the like have a large shrinkage ratio of about 50% during sintering, so that the entire surface needs to be cut to form an arc surface after sintering, and the yield is further reduced. there were.

  The present invention has been devised to eliminate such inconveniences, and its main object is to provide a motor that can be manufactured at a lower cost by promoting the simplification of the magnet shape.

In order to achieve such an object, the present invention includes a rotor shaft 4a, a rotor 4 fixed to the rotor shaft 4a and made of a magnetic material, a yoke 3 that rotatably supports and accommodates the rotor shaft 4a, The motor 1 having a pair of magnets 12 disposed on the yoke 3 and facing each other across the rotor 4 with the same poles facing each other is configured as follows.
Claim 1: A pair of magnets are formed into a flat plate shape.
Claim 2: The portion (flat portion 3b) where the magnet is disposed in the yoke is flattened.
(3) A portion having a circular arc surface facing the outer peripheral surface of the rotor with a minute gap at a position shifted by 90 degrees in the rotation direction of the rotor shaft from the position where the pair of homopolar magnets is provided in the yoke Part 3a) is provided.
According to a fourth aspect of the present invention, the auxiliary magnetic pole 13 made of a magnetic material having a circular arc surface facing the outer peripheral surface of the rotor with a minute gap is provided on the surface of the magnet facing the outer peripheral surface of the rotor.
Claim 5: A hole (rectangular hole 3c) having a circular arc surface facing the outer peripheral surface of the rotor with a minute gap at a position facing each other across the rotor center in the yoke and receiving a magnet inside thereof. The part (magnet mounting part 3d) which has is provided.
Claim 6: The pair of magnets are rare earth magnets.
Claim 7: The rotor shaft has a worm portion, and the worm portion is configured such that the output shaft 10 for transmitting the rotational force of the motor to the external load is engaged with the worm speed reducer 2 provided in a direction crossing the rotor shaft. The

  According to such a configuration of the first aspect of the present invention, since the magnet is formed in a flat plate shape, it is easy to process and the yield of the material is increased, and the applicable range is widened without selecting the magnet material. Therefore, it is possible to achieve a great effect in promoting the reduction in the thickness of the motor and reducing the manufacturing cost. In particular, the cogging torque of the motor can be lowered by arranging the flat magnet so as to be close to only a part of the outer periphery of the rotor. Since the other pole constituent part which becomes a magnetic pole opposite to the magnetic pole by the magnet is formed on the yoke, a magnetic circuit equivalent to a motor provided with a four-pole magnet can be configured even if the number of magnets is reduced. Therefore, not only the manufacturing cost of the motor can be reduced, but also the reduction in thickness and weight of the entire motor by reducing the thickness of the portion where the magnet is not provided is significant.

  According to the configuration of the second aspect, the yoke can be easily molded, which is effective for reducing the manufacturing cost.

  According to the configuration of the third aspect, the portion of the yoke where the pair of homopolar magnets is provided and the other pole constituent portion which is a magnetic pole opposite to the magnetic pole of the magnet at a position shifted by 90 degrees with respect to the magnet Since the air gap between the rotor and the rotor becomes uniform even if a flat magnet is used, the magnetic flux is reduced and the magnetic flux of the magnet can be used without loss. can do.

  According to the configurations of the fourth and fifth aspects, even if a flat magnet is used, the air gap between the rotor and the rotor can be made uniform, so that magnetic flux spots are reduced and the rotation of the rotor is stabilized. be able to.

  According to the sixth aspect of the present invention, there is no problem of moldability even if a rare earth magnet is used, and the small and strong magnetic force of the rare earth magnet can be utilized, which is advantageous for miniaturization and high output of the motor.

  According to the structure of Claim 7, since the diameter dimension of the part which does not provide a pair of magnet becomes short, the motor by this invention can be comprised as a flat type motor. Such a flat motor is applied to, for example, a wiper motor disposed in an automobile engine room, a power window motor disposed in an automobile door, a wiper motor disposed in an automobile engine room, and the like. Thus, high space efficiency can be obtained.

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

  FIG. 1 is a cross-sectional view taken along a plane orthogonal to the axis of a rotor shaft 4a showing an example of a motor 1 to which a stator S according to the present invention is applied. The stator S of the motor 1 has a generally rectangular outer contour, a bottomed cylindrical yoke 3 made of a substantially uniform wall, and the same poles (for example, N poles) facing each other so that the yoke 3 It consists of a pair of magnets 12 fixed to the inner surface on the short side.

  A flat portion 3b is formed on the short side where the magnet 12 of the yoke 3 is assembled, and the yoke 3 faces outward on the long side which is orthogonal to the short side of the yoke 3 and connects the short sides. The bulging part 3a is formed in the. And the magnet 12 fixed to the inner surface of the flat part 3b of the yoke 3 using an adhesive, for example, is formed in a flat plate shape.

  The inner peripheral surface of the bulging portion 3a in the yoke 3 forms an arc surface so as to face the outer peripheral surface of the rotor 4 received inside thereof with a minute gap. And in the example of illustration, the clearance gap between the inner peripheral surface of this bulging part 3a and the outer peripheral surface of the rotor 4, and the clearance gap of the part closest to the outer peripheral surface of the rotor 4 of a pair of flat magnets 12, The dimensions are substantially the same.

  This illustrated example has a structure corresponding to a so-called four-pole motor, and the pair of magnets 12 are arranged to face each other with the rotor shaft 4 a interposed therebetween, and the bulging portion 3 a of the yoke 3 includes a pair of magnets 12 and 12. They are arranged with a phase difference of 90 degrees.

  In the stator S configured as described above, since the pair of magnets 12 face each other with the N poles facing each other, the center part of the bulging portion 3a of the yoke 3 has an S pole with a different polarity from the magnet 12. Will occur. As a result, the same magnetic circuit as that in which the four-pole magnet is disposed is configured by the pair of magnets 12 and the pair of bulging portions 3a of the yoke 3.

  Further, as shown in FIG. 1, by using a flat magnet 12 and arranging the magnet 12 so as to be close to only a part of the outer periphery of the rotor 4, the outer periphery of the rotor 4 from the magnet center toward the magnet end. And the air gap gradually increases. For this reason, a cogging torque can be made low. In this case, since the effective magnetic flux amount is reduced by about 16%, it is preferable to increase the length of the surface of the magnet 12 that faces the outer peripheral surface of the rotor 4 by that amount.

  In this regard, in the illustrated example, the outer diameter of the bulging portion 3a is smaller than that of a configuration in which magnets are provided on all four poles (described in Patent Document 1), and therefore the magnet on the yoke inner wall is bonded. The width of the magnet connecting surface in the direction perpendicular to the rotor axis with respect to the surface can be relatively large in the dimension of the magnet 12 along the short side of the yoke 3. For this reason, there is no problem in increasing the length of the magnet 12.

  When a rare earth magnet such as a sintered Nd magnet is used as the magnet 12, the shrinkage rate during sintering is as large as about 50%, and it is difficult to match the size of the shape after sintering. After cutting out a plurality of cube-shaped magnets from a large sintered body, a cutting process is performed on the entire surface to make each of the magnets a circular arc surface corresponding to the outer peripheral surface of the rotor 4, so that much Although the amount of the material was excessive, the present invention uses a flat magnet, so it is possible to cut out a plurality of magnets from a single large sintered body, and the overall amount of magnet usage is rather reduced. Is done.

  The yoke 3 is formed by laminating thin plates obtained by punching and molding magnetic steel sheets, and a powder magnetic core obtained by kneading a ferromagnetic metal powder such as iron powder into a molten resin material, molding it, and thermosetting the resin. A yoke having a well-known configuration, such as the one used or one obtained by deep drawing from a single plate, can be equally used.

  FIG. 2 is a cross-sectional view similar to FIG. 1, showing a second embodiment of the present invention. In the illustrated example, a protruding portion 3 d that protrudes inward of the yoke 3 is formed on the short side of the yoke 3. Further, a rectangular hole 3c for fitting the flat magnet 12 is formed between the outer wall on the short side of the yoke 3 and the protruding portion 3d.

  The projecting portion 3d on the short side of the yoke 3 has an arc surface so as to face the outer peripheral surface of the rotor 4 with a minute gap. Further, the protruding portion 3d and the long side portion of the yoke 3 are arranged at a predetermined interval SP. Thereby, the predetermined interval SP becomes a magnetic resistance increasing means for the magnet 12 and the yoke 3 that can form a magnetic path, and the magnetic flux passing through the predetermined interval SP is suppressed.

  The formation of the bulging portion 3 a on the long side wall of the yoke 3 is the same as in the first embodiment, and in this case as well, the gap between the inner peripheral surface of the bulging portion 3 a and the outer peripheral surface of the rotor 4. And the clearance gap between the inner peripheral surface of the magnet mounting part 3d and the outer peripheral surface of the rotor 4 is made into the substantially same dimension. As a result, even if a flat magnet is used, the air gap between the rotor 4 and the rotor 4 becomes uniform, so that magnetic flux spots are reduced and the magnetic flux of the magnet can be used without loss, so that the motor can have high output. .

  Even in the stator S having this configuration, similarly to the first embodiment, the same magnetic circuit as that in which a four-pole magnet is disposed is configured by the pair of magnet mounting portions 3d and the pair of bulging portions 3a. The

  FIG. 3 is a sectional view similar to FIG. 1 showing a third embodiment of the present invention. In the illustrated example, the magnet 12 is fixed to the short side of the yoke 3, that is, the inner surface of the flat portion 3b, as in the first embodiment, but the gap between the magnet 12 and the outer peripheral surface of the rotor 4 is the same. Further, an auxiliary magnetic pole 13 having an arc surface is provided so as to face the outer peripheral surface of the rotor 4 with a small gap.

  As with the yoke 3, the auxiliary magnetic pole 13 is formed by laminating thin sheets obtained by punching and forming electromagnetic steel sheets. Ferromagnetic metal powder such as iron powder is kneaded into a molten resin material, and the resin is thermoset. What is formed using a known technique such as a machined powder magnetic core or a machined ferromagnetic metal material may be fixed to the magnet 12 using an adhesive or the like.

  In this example as well, the bulging portion 3a constituting the different pole is formed on the long side of the yoke 3 in the same manner as in the first and second embodiments. In this case as well, the inner circumference of the bulging portion 3a The clearance between the surface and the outer peripheral surface of the rotor 4 and the clearance between the inner peripheral surface of the auxiliary magnetic pole 13 and the outer peripheral surface of the rotor 4 are substantially the same size. Thus, similarly to the second embodiment, since the air gap between the magnet 12 and the rotor 4 can be made uniform after using a flat magnet, magnetic flux spots are reduced, and the magnetic flux of the magnet is reduced. Since it can be used without loss, the motor can have high output.

  Even in the stator S having this configuration, similarly to the first and second embodiments, a four-pole magnet is provided with the pair of magnets 12 provided with the auxiliary magnetic poles 13 and the pair of bulging portions 3a. The same magnetic circuit is constructed.

  FIG. 4 is an automotive power window to which the present invention is applied. This is constituted by a motor 1 and a reduction gear 5 provided integrally with the motor case 2. The motor 1 includes a rotating shaft 6 supported at one end in the axial direction by the motor case 2, a rotor 7 provided coaxially and integrally with the rotating shaft 6, and the motor case 2 so as to surround the rotor 7. And a plurality of magnets 12 (not shown in the cross section in the figure) disposed on the corresponding inner peripheral surface.

  In the figure, the side of the rotating shaft 6 that protrudes from the motor case 2 extends into the speed reducer 5 and is pivotally supported at two locations. A worm 6a is integrally provided at the intermediate portion of the protruding rotating shaft 6. It has been. A worm wheel 8 is gear-coupled to the worm 6a, and the reduction gear 5 is constituted by these worm gears. The shaft of the worm wheel 8 is used as an output shaft of the motor device, and a regulator link mechanism for opening and closing a window (not shown) is driven on the output shaft.

  This specific example can also be applied as a four-pole motor as described above. According to this motor 1, compared to a conventional motor in which magnets are provided on all four poles whose outline is shown by a two-dot chain line in FIG. Since the installation space of the motor 1 can be reduced, the installation space of the vehicle 1 is required. In particular, a wiper motor with a narrow installation space and a power window motor that is desired to be reduced due to the limitation of the door width. It is suitable for such as.

It is sectional drawing which shows 1st Embodiment of the stator based on this invention. It is sectional drawing which shows 2nd Embodiment of the stator based on this invention. It is sectional drawing which shows 3rd Embodiment of the stator based on this invention. It is a principal part fracture side view showing the power window for vehicles to which the present invention was applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 2 Motor case 3 Yoke 3a Expansion part 3b Flat part 3c Rectangular hole 3d Protrusion part 4 Rotor 4a Rotor shaft 12 Magnet 13 Auxiliary magnetic pole

Claims (7)

A rotor shaft, and a rotor fixed to the rotor shaft and formed of a magnetic material;
A yoke that rotatably supports and accommodates the rotor shaft;
A motor having a pair of magnets disposed on the yoke and facing each other across the rotor, with the same poles facing each other,
The motor characterized in that the pair of magnets has a flat plate shape.   The motor according to claim 1, wherein a portion of the yoke where the magnet is disposed is formed flat.   A portion having a circular arc surface facing the outer peripheral surface of the rotor with a minute gap is provided at a position shifted by 90 degrees in the rotation direction of the rotor shaft from the position where the pair of homopolar magnets is provided in the yoke. The motor according to claim 1 or 2, wherein   4. An auxiliary magnetic pole made of a magnetic material having an arc surface opposed to the outer peripheral surface of the rotor with a minute gap is provided on a surface of the magnet facing the outer peripheral surface of the rotor. The motor according to any one of the above.   A portion having a circular arc surface facing the outer peripheral surface of the rotor with a minute gap and a hole for receiving the magnet is provided inside the yoke at a position facing each other across the rotor center. The motor according to any one of claims 1 to 3, wherein   The motor according to any one of claims 1 to 5, wherein the pair of magnets are rare earth magnets.   The rotor shaft includes a worm portion, and the worm portion meshes with a worm speed reducer provided in a direction intersecting the rotor shaft so that an output shaft that transmits the rotational force of the motor to an external load is provided. The motor according to any one of claims 1 to 6.

Images