JP2012223014A - Electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric motor capable of improving assembly workability by easily fitting an end of a rotary shaft of an armature to a support hole of a metal bearing.SOLUTION: A metal bearing 10 is installed to a bottom wall 2b of a yoke 2. The end of a rotary shaft 8 of an armature 3 is freely rotatably fitted to a support hole 18 of the metal bearing 10. The metal bearing 10 includes the support hole 18 for freely rotatably supporting the end of the rotary shaft 8, and a tapered surface 22 recessed toward the support hole 18 and formed on an end face in an axial direction. An outer diameter of the tapered surface 22 is set to be larger than a fluctuation width of the end of the rotary shaft 8 when the armature 3 is inclined to the maximum in a range of an air gap with a permanent magnet 4 when the end of the rotary shaft 8 is inserted to the support hole 18.

Description

  The present invention relates to an electric motor in which a permanent magnet is disposed on an inner peripheral surface of a bottomed cylindrical yoke, and an armature rotates inside the permanent magnet.

  As an electric motor, there is known a brushed electric motor in which a plurality of permanent magnets are installed on the inner peripheral surface of a bottomed cylindrical yoke, and an armature is disposed inside the permanent magnet via an air gap. Many of this type of electric motor has a substantially cylindrical metal bearing fixedly installed at the center of the bottom wall of the yoke. When the armature is assembled inside the yoke, the end of the armature's rotating shaft is the support hole of the metal bearing. (See, for example, Patent Document 1).

Japanese Utility Model Publication No. 5-8033

By the way, in this type of electric motor, when a neodymium magnet or the like is used as a permanent magnet disposed on the inner peripheral surface of the yoke, it is difficult to magnetize the permanent magnet from the outside after assembling the armature in the yoke. A permanent magnet preliminarily magnetized is fixedly installed on the inner peripheral surface of the yoke, and then the armature is inserted and arranged in an inner space surrounded by the permanent magnet. At this time, the end of the rotary shaft of the armature is inserted into a support hole of a metal bearing installed on the bottom wall side of the yoke.
However, in the assembly work of the armature, it is difficult to fit the end of the rotating shaft into the support hole of the metal bearing, coupled with the fact that the armature receives the strong magnetic attractive force of the permanent magnet from the side.

  Therefore, the present invention is intended to provide an electric motor capable of improving the assembling workability by allowing the end of the rotary shaft of the armature to be easily fitted into the support hole of the metal bearing.

The electric motor according to the present invention employs the following means in order to solve the above problems.
The invention according to claim 1 provides an air gap between the bottomed cylindrical yoke, the permanent magnet installed on the inner peripheral surface of the yoke, and the permanent magnet on the inner peripheral side of the yoke. In an electric motor comprising: an armature that is rotatably arranged; and a substantially cylindrical metal bearing that is installed on a bottom wall of the yoke and rotatably supports a rotation shaft of the armature. A support hole for rotatably supporting the rotation shaft by inserting the rotation shaft of the armature; and a tapered surface formed in an axial end surface on the side where the rotation shaft is inserted and recessed toward the support hole; The outer diameter of the tapered surface is the rotation when the armature is inclined to the maximum in the range of the air gap with the permanent magnet when the end of the rotating shaft is inserted into the support hole. Shaft width at the end of the shaft And it is characterized in that it is also set larger.
As a result, when the armature is inserted into the yoke during assembly, even if the armature tilts to the maximum in the range of the air gap with the permanent magnet, the end of the armature's rotating shaft is reliably brought into contact with the tapered surface of the metal bearing. The rotating shaft is guided to the support hole of the metal bearing by the guide action by the tapered surface.

According to a second aspect of the present invention, in the electric motor according to the first aspect, an axial end surface of the armature core of the armature is radially covered by an insulator attached to a coil covering portion of the armature core. It is characterized by that.
As a result, even when the armature is tilted in the yoke when the armature is inserted into the yoke, the insulator first contacts the permanent magnet to avoid direct contact between the armature and the permanent magnet.

  According to a third aspect of the present invention, in the electric motor according to the second aspect, the insulator is formed so as to protrude radially outward from a radially outer end of the armature core. is there.

  According to the first aspect of the present invention, the outer diameter of the tapered surface provided in the metal bearing is set larger than the maximum deflection width of the rotary shaft of the armature at the time of assembly, and the end of the rotary shaft is at the time of assembly. Since it is structured to be surely guided into the support hole by the tapered surface, the rotary shaft of the armature can be easily fitted into the support hole of the metal bearing. Therefore, according to this invention, assembly workability | operativity can be improved.

  According to the invention of claim 2, the axial end surface of the radially outer end of the armature core is covered by the insulator, and when the armature is inclined during assembly, the insulator contacts the permanent magnet prior to the armature core. Because of the structure, damage and deformation of the permanent magnet and the armature core due to the armature core being in direct contact with the permanent magnet can be prevented.

  According to the invention of claim 3, since the insulator is formed to project radially outward from the radially outer end of the armature core, interference between the armature core and the permanent magnet is more reliably prevented. be able to.

It is sectional drawing along the axial direction of the electric motor of one Embodiment of this invention. It is the side view to which a part of armature of the electric motor of one embodiment of this invention was expanded. It is sectional drawing to which the metal bearing part of the electric motor of one Embodiment of this invention was expanded. It is sectional drawing similar to FIG. 1 which shows the assembly | attachment state of the armature of the electric motor of one Embodiment of this invention. It is sectional drawing to which a part of FIG. 4 of one Embodiment of this invention was expanded.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view along the axial direction of the electric motor 1 according to this embodiment.
The electric motor 1 is a motor with a brush used for a power window, a sunroof, an electric seat, or the like of a vehicle, and an armature 3 is rotatably accommodated inside a yoke 2 that also serves as a part of a housing.

  The yoke 2 is formed in a bottomed cylindrical shape with a metal such as iron, and a plurality of permanent magnets 4 are fixedly installed on the inner peripheral surface of the outer peripheral wall 2a near the bottom wall 2b at equal intervals in the circumferential direction. For example, a neodymium magnet or the like is used as the permanent magnet 4, and the N pole and S pole surfaces facing the center side of the yoke 2 are alternately arranged along the circumferential direction. A brush holder 6 that holds a pair of energizing brushes 5 is attached to the opening end of the outer peripheral wall 2a of the yoke 2 as a lid.

  In addition to the brush 5, a terminal (not shown) for connecting the electrical system to an external power source and circuit components (not shown) for suppressing current noise and preventing overheating are mounted on the brush holder 6. Yes. A spherical plain bearing 7 is installed at the axial center of the brush holder 6, and the rotation shaft 8 of the armature 3 that protrudes outside through the brush holder 6 is supported by the brush holder 6 via the spherical plain bearing 7. ing. In the following, the end of the armature 3 on the side of the rotating shaft 8 that passes through the brush holder 6 and protrudes to the outside will be referred to as the distal end, and the opposite end will be referred to as the proximal end. .

  Further, a boss portion 9 that protrudes outward along the central axis o of the yoke 2 is provided at the center portion of the bottom wall 2 b of the yoke 2. A metal bearing 10 described later is press-fitted and fixed to the inner peripheral surface of the boss portion 9, and the base end portion of the rotating shaft 3 is rotatably supported by the metal bearing 10.

  The armature 3 includes the rotary shaft 8 disposed at the axial center, an armature core 11 having a plurality of teeth 14 projecting in the radial direction and fitted and fixed to the outer peripheral surface of the rotary shaft 8, and the armature core 11. Armature coil 12 wound around each tooth 14 and a commutator 13 fixedly installed at a position spaced apart from the armature core 11 on the rotating shaft 8 in the axial direction.

FIG. 2 is an enlarged side view of a part of the armature 3.
As shown in FIG. 2, the armature core 11 is formed by laminating a plurality of electromagnetic steel plates or a plurality of iron plates, and each tooth 14 includes a winding body (not shown) around which the armature coil 12 is wound, And an arcuate wall 14a projecting in a T shape in the circumferential direction from the front end side of the body portion. A resin insulator 15 is attached to the winding body of each tooth 14, and the armature coil 12 is wound around each tooth 14 via the insulator 15. The outer peripheral surface of the arc wall 14a of each tooth 12 faces the permanent magnet 4 fixedly installed on the inner peripheral surface of the yoke 2 with a slight air gap.

  The insulator 15 attached to each tooth 14 extends further outward in the radial direction from the winding body (coil covering portion) at both ends in the axial direction of the tooth 14, and the extending piece 15 a has an arc wall 14 a ( It covers the end face in the axial direction of the armature core 11 at the radially outer end). The extending piece 15a of each insulator 15 is formed so as to protrude further radially outward than the radially outer end of the tooth 14 (armature core 11). In addition, when the armature coil 12 is wound around each of the teeth 14, a restriction protrusion 16 for restricting the armature coil 12 from dropping outwardly protrudes from the extension piece 15 in the axial direction.

  As shown in FIG. 1, the commutator 13 has a plurality of segments 17 made of a metal plate spaced apart at equal intervals on the outer peripheral surface, and each segment 17 is connected to a corresponding armature coil 12. The pair of brushes 5 held by the brush holder 6 abuts on the outer peripheral surface of the commutator 13 where the segments 17 are arranged, and the segments 17 that are in contact with and connected to the brushes 5 change continuously as the armature 3 rotates. It is like that.

FIG. 3 is an enlarged cross-sectional view showing a mounting portion of the metal bearing 10 on the bottom wall 2b of the yoke 2.
As shown in the figure, the metal bearing 10 is entirely formed of a metal material in a substantially cylindrical shape, and the shaft center portion thereof has a support hole 18 for rotatably supporting the base end portion of the rotary shaft 8, and A ball receiving hole 19 having an inner diameter larger than that of the support hole 18 is formed coaxially. The ball housing hole 19 is formed near the bottom side of the boss portion 9, and a steel ball 20 that contacts the end surface of the base end portion of the rotating shaft 8 is rotatably accommodated therein. A metal thrust plate 21 is disposed at the bottom of the boss portion 9 so that a thrust load acting on the steel ball 20 is received by the thrust plate 21. The metal bearing 10 is fixed to the boss portion 9 on the yoke 2 side by press-fitting, but the press-fitting region with respect to the boss portion 9 is set not to cover the outer surface of the region A in which the support hole 18 is formed. .
Further, a taper surface 22 that is recessed toward the support hole 18 is formed on the end surface in the axial direction facing the opening end side of the yoke 2 of the metal bearing 10 (the end surface in the axial direction on the side where the rotating shaft 8 is inserted). ing.

4 and 5 are views showing a state when the armature 3 is assembled to the yoke 2.
The outer diameter (radius on the outermost peripheral side) r of the tapered surface 22 shown in FIG. 3 is the same as that of the armature 3 when the proximal end portion of the rotating shaft 8 is inserted into the support hole 18 as shown in FIGS. Is set larger than the radial displacement width w (see FIG. 5) of the base end portion of the rotating shaft 8 when it is inclined to the maximum within the range of the air gap with the permanent magnet 4. In this specification, “blur width” means a distance from the central axis.

  When the electric motor 1 is assembled, the permanent magnet 4 disposed in the yoke 2 is preliminarily magnetized in advance, and the magnetized permanent magnet 4 is fixedly installed on the inner peripheral surface of the yoke 2 and the bottom wall of the yoke 2 is fixed. The thrust plate 21 and the steel ball 20 are accommodated in the boss portion 2b, and the metal bearing 10 is press-fitted and fixed in the boss portion 9 in this state. After that, as shown in FIGS. 4 and 5, the armature 3 is inserted into the yoke 2 from the opening end side, and the base end portion of the rotating shaft 8 of the armature 3 is inserted into the support hole 18 of the metal bearing 10. To do.

Thus, when the base end portion of the rotating shaft 8 of the armature 3 is fitted into the support hole 18 of the metal bearing 10, the armature 3 receives a strong magnetic attractive force by the permanent magnet 4 from the side, The armature 3 is easily inclined with respect to the central axis o in the range of the air gap with the permanent magnet 4.
However, in this electric motor 1, the outer diameter r of the tapered surface 22 provided on the end surface of the metal bearing 10 is larger than the radial displacement width w of the base end portion of the rotating shaft 8 when the armature 3 is inclined to the maximum. Therefore, when the armature 3 is inserted into the yoke 2, the base end portion of the rotating shaft 8 is surely brought into contact with the tapered surface 22 of the metal bearing 10, and the rotating shaft is guided by the guide action by the tapered surface 22. 8 is guided into the support hole 18 of the metal bearing 10.

  Therefore, in the electric motor 1, when the armature 3 is inserted into the yoke 2, the end of the rotating shaft 8 can be guided into the support hole 18 by the taper 22 of the metal bearing 10 even when the armature 3 is inclined to the maximum. Therefore, the rotating shaft 8 can be easily fitted into the support hole 18 of the metal bearing 10.

  Further, when the armature 3 is largely inclined with respect to the central axis o when the armature 3 is inserted into the yoke 2, the end portions (edge portions) on both axial sides of the radially outer end of the armature core 11 are the permanent magnets 4. However, since the end face in the axial direction of the radially outer end of the armature core 11 is covered by the extending piece 15a of the resin insulator 15, the armature 3 is made permanent by the resin insulator 15 portion. It comes into contact with the magnet 4.

  Therefore, in this electric motor 1, it is possible to avoid the hard armature core 11 from coming into direct contact with the permanent magnet 4 when the armature 3 is assembled. Therefore, the permanent magnet 4 by the armature core 11 coming into direct contact with the permanent magnet 4. In addition, damage and deformation of the armature core 11 can be prevented. Further, in the electric motor 1, when the armature 3 is assembled, the resin insulator 15 is in contact with the permanent magnet 4, so that the insertion of the armature 3 is hardly hindered by the magnetic force of the permanent magnet 4.

  In particular, in the electric motor 1 of this embodiment, the extending piece 15a of the insulator 15 is formed so as to protrude radially outward from the radially outer end portion (arc wall 14a) of the armature core 11. Interference between the armature core 11 and the permanent magnet 4 can be prevented more reliably.

  In the case of the electric motor 1, a resin member that covers the radially outer end (arc wall 14 a) of the armature core 11 is provided integrally with the insulator 15 that is attached to the coil-attached portion of the armature core 11. Since the extension piece 15a is constituted, even when the extension piece 15a is in strong contact with the permanent magnet 4 when the armature 3 is assembled, the extension piece 15a is not easily detached from the armature core 11 and can be easily assembled to the armature core 11. There is an advantage.

  Furthermore, in the electric motor 1 of this embodiment, since the press-fitting region with respect to the boss portion 9 of the metal bearing 10 is set not to cover the outer surface of the region A in which the support hole 18 is formed, It is possible to prevent the roundness and inner diameter accuracy of the support hole 18 of the metal bearing 10 from being lowered by press fitting, and it becomes difficult to insert the rotating shaft 8 into the support hole 18.

  In addition, this invention is not limited to said embodiment, A various design change is possible in the range which does not deviate from the summary.

DESCRIPTION OF SYMBOLS 1 ... Electric motor 2 ... Yoke 3 ... Armature 4 ... Permanent magnet 8 ... Rotating shaft 10 ... Metal bearing 11 ... Armature core 15 ... Insulator 18 ... Support hole 22 ... Tapered surface r ... Outer diameter w ... Swing width

Claims (3)

A bottomed cylindrical yoke,
A permanent magnet installed on the inner peripheral surface of the yoke;
An armature that is rotatably disposed on the inner peripheral side of the yoke with an air gap between the yoke and the permanent magnet;
In an electric motor comprising: a substantially cylindrical metal bearing installed on the bottom wall of the yoke and rotatably supporting the rotation shaft of the armature;
The metal bearing is formed with a support hole in which the rotation shaft of the armature is inserted to rotatably support the rotation shaft, and an end face in the axial direction on the side where the rotation shaft is inserted, which is recessed toward the support hole. And a tapered surface,
The outer diameter of the tapered surface is such that when the end of the rotating shaft is inserted into the support hole, the end of the rotating shaft when the armature is tilted to the maximum in the range of the air gap with the permanent magnet. An electric motor characterized in that it is set to be larger than the fluctuation width.   2. The electric motor according to claim 1, wherein an end face in an axial direction of a radially outer end of the armature core of the armature is covered by an insulator attached to a coil covering portion of the armature core.   The electric motor according to claim 2, wherein the insulator is formed so as to protrude radially outward from an end portion on the radially outer side of the armature core.

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