JP2009005541A - Brush motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brush motor improved in productivity and produced inexpensively. <P>SOLUTION: A means of the present invention for solving the problem to achieve the purpose includes a brush motor 1 comprising: a cylindrical case 2; and a cylindrical stator 3 fixed within the case 2. The stator 3 comprises: a stator core 4 cylindrically formed, and having a plurality of magnetic poles 4a swelling on an inner circumference; and permanent magnets 5, 5 embedded two by two within each magnetic pole 4a in the stator core 4. A slit 4b is provided between the permanent magnets 5, 5 on an outer circumference of each magnetic pole 4a in the stator core 4 along an axial line of the stator core 4. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a motor with a brush.

  Generally, in a motor having a cylindrical stator, the stator is integrated into the case by press-fitting the cylindrical stator into the cylindrical case (see, for example, Patent Document 1).

By the way, since a motor with a brush usually causes a case to function as a yoke, an arc-shaped permanent magnet is bonded to the inner periphery of the case at equal intervals. When a stator is configured to be embedded with permanent magnets for use, it is assumed that a method such as press-fitting is adopted in order to integrate the stator into the case, as in a general motor. .
Japanese Patent Laying-Open No. 2006-333657 (FIG. 1)

  However, since the motor case described above has a bottomed cylindrical shape, it is often formed by deep drawing press processing, and this deep drawing press processing cannot achieve high dimensional accuracy, and the cylindrical shape of the stator. However, there is a limit to the compression in the radial direction, so even if it is press-fitted, the inner diameter of the case is smaller than the outer diameter of the stator so that the stator cannot be inserted into the case. There is a possibility that the stator becomes larger and the stator cannot be fixed in the case.

  In order to avoid this, high-accuracy dimensional management is forced on both the case and the stator, so that the productivity of the motor deteriorates and the processing cost also increases.

  Accordingly, the present invention has been developed to improve the above-described problems, and an object of the present invention is to provide a brushed motor that can improve productivity and can be produced at low cost. .

  In order to achieve the above-described object, the problem-solving means of the present invention is a brushed motor including a cylindrical case and a cylindrical stator fixed in the case. The stator is formed in a cylindrical shape. A stator core having a plurality of magnetic pole portions whose inner peripheral side bulges, and a permanent magnet embedded in each magnetic pole portion of the stator core two by two, and a permanent magnet on the outer periphery of at least one magnetic pole portion of the stator core A slit is provided along the axis of the stator core.

  According to the invention of each claim, when press-fitting the stator into the case, the outer periphery of the stator core is provided with a slit, and the presence of this slit makes it easier to reduce the diameter of the stator core than that without the slit. Thus, the range of diameter reduction allowed by the stator core is increased, so that the stator can be reliably press-fitted into the case and fixed even if the dimensional accuracy of the case or the stator core is not high.

  Further, since the diameter reduction range allowed by the stator core is increased, a large press-fitting allowance can be secured, and the stator can be firmly fixed to the case.

  Since the stator can be securely press-fitted and fixed to the case simply by providing a slit, there is no need to perform post-processing to obtain dimensions on the case or the stator, and the press-fit property is improved. It is possible to achieve both productivity improvement and low-cost production.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a brush motor according to an embodiment of the present invention. FIG. 2 is an AA cross-sectional view of the brush motor according to the embodiment of the present invention. FIG. 3 is a partially enlarged cross-sectional view of a motor in which the stator structure according to the embodiment of the present invention is embodied.

  As shown in FIGS. 1 and 2, the brushed motor 1 according to the embodiment includes a bottomed cylindrical case 2, a cylindrical stator 3 fixed to the inner periphery of the case 2, and a case 2. Both ends are supported by an annular cap 6 attached to the opening, a ball bearing 7 fixed to the top of the case 2, and a ball bearing 8 fixed to the inner periphery of the cap 6, and rotate toward the inner periphery of the stator 3. The rotor 9 is inserted freely, the commutator 10 is provided on the lower end side of the rotor 9, and the brush 11 is in sliding contact with the outer periphery of the commutator 10.

  Hereinafter, the stator 3 will be described in detail. The stator 3 is formed in a cylindrical shape and has a plurality of magnetic pole portions 4a formed by expanding the inner peripheral side to increase the thickness, and each magnetic pole of the stator core 4 The rare earth permanent magnets 5 are embedded in the portion 4a two by two, and a slit is formed between the permanent magnets 5 and 5 on the outer periphery of each magnetic pole portion 4a of the stator core 4 along the axis of the stator core 4. 4b is provided.

  In the case of this embodiment, the magnetic pole portion 4a in the stator core 4 is provided with four magnetic pole portions 4a, and the brushed motor 1 is configured as a four-pole motor.

  More specifically, as shown in FIG. 1, both end portions in the arc direction of the surface facing the rotor 9 on the inner peripheral side of each magnetic pole portion 4a are inclined so as to be away from the outer periphery of the rotor 9 to form a tapered surface 4c. In addition, two plate-like permanent magnets 5 and 5 are arranged in a square shape and embedded in the thickness of each magnetic pole portion 4a. Specifically, each magnetic pole portion 4a is provided with a hole 4d in which the permanent magnets 5 and 5 are fixed, and the permanent magnets 5 and 5 are fixed in the hole 4d by adhesion or the like. The permanent magnets 5 and 5 embedded in the same magnetic pole portion 4a are arranged so that the magnetic pole portion 4a functions as one magnetic pole, for example, when the magnetic pole portion 4a functions as an N pole, the N pole side is connected to the rotor 9. When the magnetic pole part 4a functions as an S pole, the S pole side is arranged toward the rotor 9 side.

  Thus, since the permanent magnet 5 is embedded in the arc-shaped magnetic pole portion 4a in the above arrangement, as shown in FIG. 3, the end portion 5a on the end side in the arc direction of the magnetic pole portion 4a in each permanent magnet 5 is the magnetic pole portion. The magnetic pole portion 4a is inclined so as to approach the inner peripheral side of the magnetic pole portion 4a, and is disposed in the magnetic pole portion 4a. Will be.

  Here, although the magnetic flux concentrates on the back side of the end portion 5a of the permanent magnet 5, the magnetic path cross-sectional area in the magnetic flux concentration portion B is ensured by ensuring the thickness of the magnetic pole portion 4a on the back side of the end portion 5a. Therefore, saturation of the magnetic flux is suppressed. Thus, if the two permanent magnets 5 are arranged in a square shape in one magnetic pole portion 4a, a large magnetic path cross-sectional area in the magnetic flux concentrating portion B can be secured.

  Further, the slit 4b is provided on the back surface of the magnetic pole part 4a of the stator core 4 and between the permanent magnets 5 and 5, and the magnetic path M formed by the permanent magnets 5 and 5 embedded in each magnetic pole part 4a is a slit. Since it is formed on both sides with 4b as a boundary, even if the slit 4b is provided, there is no magnetic adverse effect.

  And since the permanent magnet 5 is embedded in the magnetic pole part 4a of the stator core 4, the member used only for protection of the permanent magnet 5, such as a protector and a holder, and scattering prevention is provided in the motor 1 with a brush. It is possible to eliminate waste.

  The stator core 4 is configured to realize the above-described shape by laminating a plurality of steel plates, but may be configured to realize the above-described shape by sintering forming in addition to the lamination of steel plates. .

  Next, as shown in FIG. 1, the rotor 9 includes a shaft 12, a rotor core 13 having 22 slots fixed to the outer periphery of the shaft 12, and a winding 14 wound around the rotor core 13. It is set as the known structure provided.

  As shown in FIG. 1, the magnetic pole portion 4 a of the stator core 4 is configured such that the end in the arc direction gradually moves away from the outer periphery of the rotor core 13 due to the formation of the tapered surface 4 c.

  Therefore, since the gap between the magnetic core 4a and the rotor core 13 is larger at both ends in the circumferential direction than at the center, the cogging torque can be reduced. That is, according to the stator 3, it is possible to reduce the cogging torque without making the shape of the permanent magnet 5 particularly an arc shape and reducing the thickness at both ends in the circumferential direction. A uniform torque can be generated in the motor 1.

  As described above, the two plate-like permanent magnets 5 are arranged in one magnetic pole portion 4a of the stator core 4 so that each magnetic pole portion 4a constitutes one magnetic pole. Therefore, it is not necessary to form the permanent magnet 5 in an arc shape, and even if the permanent magnet 5 is a rare earth magnet, the cost is not increased, and there is no problem in strength. Furthermore, even if the permanent magnet 5 is a rare earth magnet, the shape of the permanent magnet 5 to be used can be all plate-like and the same shape, so that the manufacturing process is not complicated and both ends need to be thin. Since there is not, the possibility of demagnetization can be reduced.

  In this way, a plurality of plate-like permanent magnets 5 are arranged in one magnetic pole part 4a of the stator core 4 so that each magnetic pole part 4a constitutes one magnetic pole. Even if the magnet 5 is a rare earth magnet, there is no fear that the manufacturing cost of the motor 1 will be deteriorated, no problem in strength occurs, and the magnetic path cross-sectional area is secured, so that saturation of the magnetic flux is suppressed and the brushed motor 1 is sufficient. Since torque can be generated and cogging torque can be reduced, the axial length of the permanent magnet 5 in the vertical direction in FIG. 2 can be shortened by the large magnetic force of the rare earth magnet. It is possible to reduce the axial length of the brushed motor 1 without causing undesirable adverse effects.

  On the other hand, the case 2 in which the stator 3 is accommodated and fixed has a bottomed cylindrical shape, and is provided with a convex portion 2a on the inner periphery. When the stator 3 is fixed in the case 2, the convex portion 2a becomes the stator core. 4, the function of positioning the stator 3 in the circumferential direction with respect to the case 2 is exhibited and the function of preventing the stator 3 from idling in the circumferential direction is exhibited.

  In the brush motor 1 configured as described above, when the stator 3 is press-fitted into the case 2, a slit 4b is provided on the outer periphery of the stator core 4, and the presence of the slit 4b causes the stator core 4 to be Since the diameter reduction range allowed by the stator core 4 is increased because it is easier to reduce the diameter than those without a slit, the stator 3 is securely press-fitted into the case 2 even if the dimensional accuracy of the case 2 and the stator core 4 is not high. And can be fixed.

  Further, since the diameter reduction range allowed by the stator core 4 is increased, a large press-fitting allowance can be secured and the stator 3 can be firmly fixed to the case 2.

  Since the stator 3 can be securely press-fitted and fixed to the case 2 simply by providing the slit 4b, there is no need to perform post-processing to obtain dimensions on the case 2 or the stator 3, and the press-fit property is improved. Therefore, it is possible to achieve both improvement in productivity of the motor 1 with brush and low-cost production.

  Further, the stator 3 is positioned at a correct position in the circumferential direction with respect to the case 2 by the convex portion 2a provided on the inner circumference of the case 2, and the idling of the stator 3 in the circumferential direction is prevented. It is not necessary to provide an anti-spinning measure depending on the processing and members, and the brushed motor 1 can be produced at a much lower cost.

  Further, considering only the improvement of press fit, the slit 4b may be provided at any position on the outer periphery of the stator core 4, but the slit 4b is provided on the back surface of the magnetic pole portion 4a of the stator core 4 and between the permanent magnets 5 and 5. The slit 4b does not affect the magnetic path M and does not decrease the magnetic path cross-sectional area of the magnetic path M, and the thickness of the stator core 4 is increased except for the portion where the slit 4b is provided. Since the thickness does not decrease, the magnetic path cross-sectional area of the magnetic path M is not reduced at this point, so that the torque of the brushed motor 1 is not reduced.

  The slits 4b do not have to be provided in a number equal to the number of the magnetic pole portions 4a, and can be arbitrarily set within a reduced diameter range that should be allowed by the stator core 4.

  Moreover, what is necessary is just to set arbitrarily the number of the convex parts 2a provided in the case 2 by making the number of the slits 4b into an upper limit.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

It is a cross-sectional view of the motor with a brush in one embodiment of the present invention. It is AA sectional drawing of the motor with a brush in one embodiment of this invention. 1 is a partially enlarged cross-sectional view of a motor in which a stator structure according to an embodiment of the present invention is embodied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 2 with brush 2 Case 2a Projection part 3 Case 4 Stator core 4a Stator core magnetic pole part 4b Stator core slit 4c Stator core taper surface 4d Stator core hole 5 Permanent magnet 5a Permanent magnet end 6 Cap 7, 8 Ball bearing 9 Rotor 10 Commutator 11 Brush 12 Shaft 13 Rotor core 14 Winding B Magnetic flux concentrating part M in stator core Magnetic path in stator core

Claims (2)

In a brushed motor including a cylindrical case and a cylindrical stator fixed in the case, the stator is formed in a cylindrical shape and includes a stator core having a plurality of magnetic pole portions that bulge on the inner peripheral side; A permanent magnet embedded in each magnetic pole portion of the stator core, and a slit is provided along the axis of the stator core between the permanent magnets on the outer periphery of at least one magnetic pole portion of the stator core. A motor with a brush. The brush motor according to claim 1, wherein a convex portion that enters the slit is provided on an inner periphery of the case.

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