JP2008259258A - Permanent magnet commutator motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a permanent magnet commutator motor comprising a stator having a stator yoke structure capable of altering the profile of a stator yoke easily, and facilitating assembly of the stator yoke and a permanent field magnet. <P>SOLUTION: The stator yoke 11 is formed of a sintered compact of a ferromagnetic material, protrusions 31e and 31f for latching field magnets 12a and 12b are provided on the inner circumferential surface of the stator yoke 11, and the field magnets 12a and 12b are clamped by the latching protrusions 31e and 31f and a spring member 41f thus bonding the field magnets 12a and 12b easily to the inner circumferential surface of the stator yoke 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a permanent magnet commutator motor, and more particularly to a permanent magnet commutator motor that is driven by a battery or an AC power source and that is suitable as a drive motor constituting an electric tool.

  Permanent magnet commutator motors are widely used as a drive source for electric tools that require a large starting torque because they have a large starting torque and can be shifted.

  The permanent magnet commutator motor includes a motor housing, a stator, an armature, and a brush as disclosed in, for example, Patent Document 1 below. The stator includes a cylindrical stator yoke including an oval cross-sectional outer shape, and a field magnet (permanent magnet) included in the stator yoke. The field magnet is fitted or fixedly attached to the inner peripheral surface of the cylindrical stator yoke. The stator yoke is constituted by a laminated body in which a plurality of plate-like annular bodies made of, for example, an iron material are coaxially laminated, and the plurality of annular bodies constituting the laminated body are caulked on each annular body. They are squeezed and fixed to each other by the portions. The length of the stator yoke in the central axial direction can be adjusted by changing the number of annular bodies to be stacked with the axial thickness of the annular body as a minimum unit.

  Therefore, when manufacturing various types of stator yokes having different axial lengths, a permanent magnet commutator motor having a stator yoke that is inexpensive to manufacture without requiring replacement of the manufacturing machine is provided. be able to. Further, by providing a protrusion (protrusion) on the inner peripheral surface of the annular stator yoke, the field magnet is held on the inner peripheral surface of the stator yoke, so that the stator yoke and the field magnet It has been devised to facilitate assembly.

JP 2004-129329 A

  The above-described permanent magnet commutator motor is advantageous in terms of production cost when mounted on a power tool for mass production (for example, production of 10,000 or more units per month), but for small production (for example, thousand units per month) In the case of mounting on a product of the following production), there is a disadvantage that the production cost becomes expensive. The reason for this is that the manufacturing cost of the plate-shaped annular body for manufacturing the iron plate-shaped annular body constituting the stator core becomes expensive, making it unsuitable for application to a small-volume product.

  Accordingly, it is an object of the present invention to provide a permanent magnet commutator motor having a stator yoke that can eliminate the above-mentioned conventional drawbacks and can easily change the shape of the stator yoke.

  Another object of the present invention is to provide a permanent magnet commutator motor having a stator that facilitates assembly of a stator yoke and a permanent field magnet.

  Still another object of the present invention is to provide a permanent magnet commutator motor configured so as to prevent the magnetic path by the stator from being obstructed by facilitating accurate alignment during assembly of the stator yoke and the permanent field magnet. It is to provide.

  Among the inventions disclosed in accordance with the present invention in order to solve the above problems, the characteristics of typical ones will be described as follows.

  According to one aspect of the present invention, a stator including a stator yoke and a pair of opposing field magnets provided on an inner peripheral surface of the stator yoke, an axis of the inner peripheral surface of the stator, An armature having a coaxial rotating shaft and having an outer peripheral surface close to the inner peripheral surface of the stator, and generating a field magnetic pole in the inner peripheral surface of the stator by the field magnet. In the permanent magnet commutator motor for rotating the stator, the stator yoke is composed of a sintered body of a ferromagnetic material, and an inner peripheral surface of the sintered body of the stator yoke is provided with the pair of field magnets. A pair of projecting portions for locking the opposing one end portions are integrally formed, and spring members made of an elastic material are engaged with the opposing other end portions of the pair of field magnets. The one end is configured to be pressed from the other end so as to be engaged with the corresponding pair of protrusions. That.

  According to another aspect of the present invention, a width and a height of the protrusion integrally formed on the inner peripheral surface of the stator yoke are defined to be equal to or less than a thickness of the field magnet.

  According to still another aspect of the present invention, the thickness of the stator yoke in the portion including the field magnet is equal to the thickness of the stator yoke in the portion not including the field magnet. It is formed thinner than the maximum value.

  According to the above feature of the present invention, the stator yoke is composed of a sintered body of a ferromagnetic material, so that it is more stable than a permanent magnet commutator motor having a stator yoke in which iron plate-like annular bodies are laminated. Low cost and easy handling for small volume production.

  According to the present invention, since the permanent field magnet is held so as to be locked to the protrusion of the stator yoke, it is possible to provide a permanent magnet commutator motor including a stator that facilitates assembly of the permanent field magnet. .

  According to the present invention, the protrusion functioning as the locking portion of the permanent field magnet facilitates accurate alignment during the assembly of the stator yoke and the permanent field magnet, thereby obstructing the magnetic path by the stator. A permanent magnet commutator motor configured so as not to be provided can be provided.

  The above and other objects, and the above and other features and advantages of the present invention will become more apparent from the following description of the present specification and the accompanying drawings.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description thereof will be omitted. First, an embodiment of the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 and 2, the permanent magnet motor 1 has a housing 1 a, a stator 10, an armature 20, a pair of brushes 13, and a commutator 24.

  The housing 1a has a cylindrical shape including a true cylindrical shape or a substantially cylindrical shape. An outer peripheral surface of a cylindrical stator yoke 11 to be described later is fixed or attached to a part of the cylindrical inner peripheral surface. The housing 1a is made of, for example, a synthetic resin material.

  The stator 10 includes a stator yoke 11 and a pair of field magnets 12a and 12b that function as at least a pair of N poles and S poles.

  As will be described later, the stator yoke 11 (see FIG. 2) is formed of a sintered body of a ferromagnetic material according to the present invention, and has a cylindrical shape. The outer peripheral surface of the stator yoke 11 is fitted or fixed to the inner peripheral surface of the housing 1a.

  On the inner peripheral surface of the cylindrical stator yoke 11 (sintered body), a pair of locking projections (projections) 31e and 31f, which will be described later, are formed integrally with the inner peripheral surface of the sintered body. A pair of field magnets 12a and 12b are sandwiched between locking projections 31e and 31f and a spring member 41f described later, and are attached so as to be inscribed in the inner peripheral surface of the cylindrical stator yoke 11. ing.

  The pair of field magnets 12a and 12b are N-pole and S-pole permanent magnets, and have a shape like a plate-like permanent magnet curved in an arc shape. The arcuate curved outer peripheral surfaces of the field magnets 12 a and 12 b are inscribed in the shape of the inner peripheral surface of the stator yoke 11, and the pair of field magnets 12 a and 12 b is a part of the inner peripheral surface of the stator 10. Parts. The pair of field magnets 12a and 12b are symmetrically arranged and fixed at opposite positions in the diametrical direction of the stator yoke 11 in order to obtain as efficient rotational torque as possible of the motor. Therefore, as shown in FIG. 2, when viewed in the radial cross section of the housing 1a, the field magnet 12a or 12b, the stator yoke 11, and the housing 1a are arranged in that order in the radial direction of the housing 1a. It is arranged outward from the center. Thus, a pair of field magnets 12a and 12b arranged symmetrically generates a pair of field magnetic poles in the stator 10, and a field flux having a high magnetic flux density is generated between the pair of field magnetic poles. It is configured as follows.

  As shown in FIG. 1 and FIG. 2, an armature 20 is provided in the vicinity of the inner peripheral surface of the stator 10. The armature 20 includes a shaft 21, a rotor core 22 attached to the shaft 21, and a coil 23 wound around the rotor core 22.

  One end 21a (see FIG. 1) of the shaft 21 is supported by a bearing portion 14 provided on the housing lid portion 1b, and the other end of the shaft 21 is supported by a bearing portion 15 provided on the fixed portion 16. . Thus, the shaft 21 is supported so as to be rotatable about the axis of the stator yoke 11 (stator 10).

  A core (iron core) 22 is fixed to a part of the shaft 21. The outer peripheral surface of the core 22 is disposed close to the inner peripheral surface formed by the pair of field magnets 12a and 12b. A plurality of slots (not shown) are formed in the core 22 in parallel with the rotation axis direction, and a conductive wire is wound in the slots so as to cross the field magnetic flux generated by the pair of field magnets 12a and 12b. The wound conducting wire forms a coil 23 and a current is supplied from a pair of brushes 13 described later. Rotational torque generated by the armature 20 is transmitted to the other end side (left side of the drawing in FIG. 1) of the shaft 21 supported by the bearing portion 15 with the shaft 21 as a rotation output shaft, and is not shown. Drive the tip tool.

  As shown in FIG. 1, a cylindrical commutator 24 is coaxially fixed to the shaft 21 on one end 21 a side of the shaft 21 so as to rotate together with the shaft 21 and the core 22. It is configured. The commutator 24 has a plurality of commutator pieces (not shown) exposed along the outer peripheral surface of the cylinder, and is electrically connected to each end of the coil 23 by the commutator pieces.

  As shown in FIG. 1, a pair of upper and lower brushes 13 are arranged on one end 21 a side (right end side) of the shaft 21 so as to face each other. Each brush 13 is housed and held in a brush holder 13a fixed to the inner peripheral surface of the housing 1a. The brush 13 held in the brush holder 13a is urged in the direction of the commutator 24 by a spring (not shown) provided in the brush holder 13a, and protrudes toward the commutator 24 (commutator piece) to the commutator 24. Electrical connection (contact). The other ends of the pair of brushes 13 are electrically connected to, for example, a DC power source via lead wires (not shown), and supply current from the power source to the coil 23 via the brush 13 and the commutator 24. The child 20 is configured to generate rotational torque.

  The cooling fan 17 is provided on the other end side of the shaft 21 so as to rotate integrally with the shaft 21, and cools the heat generated in the armature 20.

  The structure of the stator 10 according to the present invention will be described in more detail with reference to FIGS.

  As described above, a pair of locking projections (protrusions) for locking one end of each of the pair of field magnets 12a and 12b is formed on the cylindrical inner peripheral surface of the stator yoke 11 (sintered body). Part) 31e and 31f are provided integrally. For example, the outer diameter of the stator yoke 11 is 49 mm, the length is 39 mm, the thickness in the radial direction is 3 mm to 10 mm, the width (w) in the inner circumferential direction of the protrusions (projections) 31e and 31f is 1.5 mm, and the radius The height h in the direction is 0.5 mm. The protrusions (projections) 31e and 31f of the stator yoke 11 do not need to be formed over the entire axial length (eg, 39 mm) of the stator yoke 11, as shown in FIG. Any length may be used as long as one end of the pair of field magnets 12a and 12b can be stably locked.

  The sintered body of the stator yoke 11 is manufactured, for example, by insulating the surface of pure iron fine powder with an inorganic insulator and mixing it with a small amount of an organic resin binder, followed by compression molding and heat treatment.

  As shown in FIG. 4B, one end of the pair of field magnets 12a and 12b is inserted by inserting a spring member 41f for fixing the field magnet into the other end of the pair of field magnets 12a and 12b. The portions are pressed (biased) to the protrusions 31e and 31f (see (1) in FIG. 4) to fix the pair of field magnets 12a and 12b in the stator yoke 11.

  The field magnet fixing spring member 41f is formed of an elastic member, and is formed of a metal material such as spring steel bent in a horseshoe shape (U-shape) as shown in FIG. . Moreover, the spring member formed with the resin material which has spring property other than a metal member may be sufficient. In the modification shown in FIG. 5, the spring member 41f is configured by bending a plate-shaped synthetic resin material into a curved shape to provide elasticity.

  As described above, the field magnets 12a and 12b are sandwiched between the protrusions 31e and 31f and the spring member 41f, whereby the field magnets 12a and 12b are used on the inner peripheral surface of the stator yoke 11, and an adhesive is used. And can be easily fixed.

  As shown in FIG. 3, the height (step difference) h and the circumferential width w of the protrusions 31e and 31f provided on the inner peripheral surface of the stator yoke 11 are smaller than the thickness t of the field magnets 12a and 12b. It is desirable to specify. The reason for this is to prevent the main magnetic flux in the stator yoke 11 from leaking or decreasing due to the formation of the protrusions 31e and 31f.

  By the way, in the manufacture of the stator yoke by press bending pipe processing of the conventional yoke plate material, when the radial thickness of the stator yoke is 3 mm or less, the pipe yoke of the stator yoke is cut from the outer peripheral surface. It is possible to provide a protruding portion (convex portion) on the inner peripheral surface of the stator yoke by locally bending it. However, when the protrusions are formed in this way, the notched portion becomes a gap, and the yoke portion of the stator yoke does not work effectively as the magnetic path of the main magnetic flux, so that the main magnetic flux generated by the field magnet is reduced. . As a result, the efficiency of the permanent magnet commutator motor is reduced. As another method of forming the protrusion, it is possible to apply an external force to the pipe yoke portion of the stator yoke from the outer periphery to plastically deform the stator yoke and provide a protrusion on the inner surface. However, the yoke part of the deformed stator yoke is reduced in thickness in the radial direction of the stator yoke by bending or pulling and compressing, so a decrease in the main magnetic flux is inevitable and rotational torque is generated. descend.

  On the other hand, according to the above-described embodiment of the present invention, since no gap is formed in the formation part of the protrusions 31e and 31f, the main magnetic flux of the stator yoke 11 does not decrease, and the permanent magnet A reduction in efficiency of the commutator motor can be prevented. Further, according to the present invention, since the stator yoke 11 is formed as a sintered body, the shapes of the protrusions 31e and 31f can be easily realized.

  As shown in FIG. 3, the stator yoke 11 described in the above embodiment has a circular outer shape (perfect circle), and the thickness of the stator yoke 11 excluding the protrusions 12a and 12b in the radial direction is It is constant. That is, as shown in FIG. 3, the inner periphery and the outer periphery of the stator yoke 11 are formed concentrically, and the thickness of the stator yoke 11 is constant over the entire periphery.

  However, as shown in FIG. 6, when the outer periphery and inner periphery of the stator yoke 11 are concentric circles, the main magnetic flux Bm generated from the pair of field magnets 12a and 12b increases as the thickness of the stator yoke 11 increases. On the other hand, the armature magnetomotive force is generated by the current flowing through the coil 23 (see FIG. 1) of the armature 20 when the commutator motor is driven, and the armature reaction magnetic flux Br is easily generated. The armature reaction magnetic flux Br obstructs the flow of the main magnetic flux Bm generated from the field magnets 12a and 12b and causes the rotational torque of the armature 20 to be reduced. As a result, the efficiency of the commutator motor is reduced. It becomes.

  In order to improve the efficiency reduction of the commutator motor due to the armature reaction magnetic flux Br, according to another embodiment of the present invention, as shown in FIGS. 7 and 8, the outer peripheral shape of the stator yoke 11 is substantially elliptical. It is formed into a shape.

  That is, as shown in FIGS. 7 and 8, the shape of the stator yoke 11 is the minimum value t1 of the thickness of the stator yoke portion 11d along the field magnets 12a and 12b fixed to the inner peripheral surface thereof. (See FIG. 7) is formed to be thinner than the maximum thickness t2 (see FIG. 7) of the thickness 11e of the stator yoke that does not extend along the field magnets 12a and 12b. Thus, the structure of the stator yoke 11 in which the thickness t1 of the portion of the stator yoke 11d where the field magnets 12a and 12b are stacked is thinner than the thickness t2 of the portion of the stator yoke 11e where the field magnets 12a and 12b are not stacked. According to the present invention, since the stator yoke 11 is formed of a sintered body, it can be easily manufactured as compared with the case where the plate yoke is manufactured by press working or the like.

  Therefore, if the structure of the stator 10 as shown in FIG. 7 or FIG. 8 is used, the magnetic path cross-sectional area of the stator yoke 11 at the substantially central position of the field magnetic poles 12a and 12b can be reduced, so that the magnetic resistance is increased. Thus, the efficiency of the commutator motor can be improved by effectively contributing the main magnetic flux Bm (see FIG. 6) to the torque.

  As shown in FIG. 8, when the outer periphery of the stator yoke 11d including the field magnets 12a and 12b is planar, the field magnet is formed after sintering the cylindrical stator yoke. It is good also as the shape which cut the outer peripheral part of the stator yoke which includes 12a, 12b in the shape of a straight line.

  As mentioned above, although the invention made | formed by this inventor was demonstrated based on various embodiment, this invention is not limited to the said embodiment, A various change is possible within the range which does not deviate from the summary. .

The principal part sectional view showing the permanent magnet commutator motor concerning the embodiment of the present invention. Sectional drawing of the permanent magnet commutator motor along the XX line shown in FIG. Sectional drawing of the stator which comprises the permanent magnet commutator motor shown in FIG. Sectional drawing of the stator along the AA line and BB line shown in FIG. The perspective view which shows the modification of the spring member used for the stator shown in FIG. The conceptual diagram which shows the magnetic path of the main magnetic flux of a stator and the magnetic path of an armature reaction magnetic flux in the permanent magnet commutator motor shown in FIG. Sectional drawing which shows the stator of the permanent magnet commutator motor which concerns on other embodiment of this invention. Sectional drawing which shows the stator of the permanent-magnet commutator motor which concerns on other embodiment of this invention.

Explanation of symbols

1: Permanent magnet commutator motor 1a: Housing 1a: Housing lid portion 10: Stator 11: Stator yoke 12a, 12b: Field magnet 13: Brush 13a: Brush holder 14: Bearing portion 15: Bearing portion 16: Bearing fixed Part 17: Cooling fan 20: Armature 21: Shaft 22: Core 23: Coil 24: Commutator 31e, 31f: Projection (convex part)
41f: Spring member

Claims (3)

A stator having a stator yoke and a pair of opposing field magnets provided on the inner peripheral surface of the stator yoke, and a rotation axis coaxial with the central axis of the inner peripheral surface of the stator, the fixed And a permanent magnet commutator motor that rotates the armature by generating a field magnetic pole in the inner peripheral surface of the stator by the field magnet. In
The stator yoke is composed of a sintered body of a ferromagnetic material, and the inner peripheral surface of the sintered body of the stator yoke is used to lock both opposing ends of the pair of field magnets. A pair of protrusions are integrally formed,
The opposite ends of the pair of field magnets are engaged with spring members made of an elastic material so that the one ends are engaged with the corresponding pair of protrusions. A permanent magnet commutator motor characterized by being configured to be pressed from a portion.   2. The permanent magnet commutator motor according to claim 1, wherein a width and a height of the protrusion formed integrally on the inner peripheral surface of the stator yoke are equal to or less than a thickness of the field magnet.   The thickness of the stator yoke that includes the field magnet is formed to be thinner than the maximum value of the thickness of the stator yoke that does not include the field magnet. The permanent magnet commutator motor according to claim 1 or 2, wherein the permanent magnet commutator motor is provided.

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