JP2012222942A - Electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve conductivity and workability while adopting a resin front cover and to reduce weight of an electric motor.SOLUTION: A casing ground type electric motor 100 includes: a case 11 formed in a cup shape; a front cover 17 covering an opening of the case; an armature 43 housed inside the case and provided with winding 42; and a permanent magnet 16 housed in the case facing the armature. The electric motor further includes a rotary shaft 32 for which a rear side rolling bearing 34 is attached to an end, a front side rolling bearing 33 is attached to an intermediate part, and the armature is fixed and attached between the bearings. The front cover is made of a resin, a ground plate 51 electrically connected to the ground side of the winding and a positive pole plate 71 electrically connected to the positive pole side of the winding are electrically insulated from each other and arranged inside the resin front cover, and resin integrated molding is executed.

Description

  The present invention relates to an electric motor, and more particularly to an electric motor with a brush that is suitable for a sealed earth type housing.

  Examples of conventional brushed motors are described in Patent Documents 1 and 2. In the electric motors described in these publications, an electric motor main body having a rotor and a stator is substantially cup-shaped so that an imbalance of the rotor mass can be corrected, or in order to reduce the axial dimension by shortening the rotor shaft. The case is housed in a steel case formed on the front side, and the front cover closes the front side opening of the case.

  Then, a brush holding plate made of an insulating material is fixed inside the front cover, and a brush holder pair in which the brush is held on the brush holding plate at an interval of 180 degrees in the circumferential direction is connected to the brush holder pair and the circumferential direction. A pair of other brush holders holding the brush are attached at intervals of 90 degrees. One pair of brushes is electrically connected to the front cover, and the other pair of brushes is electrically connected to an input terminal fitting inserted in an insulating member held by the front cover.

  Further, the central portion of the front cover is bent by a press or the like, and holds the outer ring of the rolling bearing attached to the rotating shaft. On the other hand, the outer peripheral portion of the front cover is fixed to the case in a state where it is press-fitted into the inner periphery of the end of the peripheral wall portion of the case on the opening side.

  An example of a conventional motor pump device is described in Patent Document 3. The motor pump described in this publication is a piston pump used in an anti-lock system of a vehicle, and the motor part is a pot-shaped casing composed of a cylindrical outer peripheral wall and end walls provided at both ends of the outer peripheral wall. Inside, the rotor and the field magnet are accommodated. One end wall has a tubular bearing collar that protrudes in the direction of the pump concentrically with respect to the outer peripheral wall. A bearing is fixed in the radial direction and the axial direction in the bearing collar.

JP 2001-119906 A JP 2007-236144 A JP 2000-130354 A

  In any of the above patent documents, the electric motor accommodates the rotor and the field magnet in a steel pot-shaped casing, and the iron or steel front cover is mechanically adhered so as to cover the opening of the casing. ing. Then, electric power is supplied to the windings constituting the rotor via the brush, and one brush is electrically connected to an extraction terminal provided on the front cover and insulated from the front cover, and the other brush is the front cover. Is electrically connected to the casing to form a so-called housing ground.

  Those described in these patent documents utilize the advantage that the front cover is made of conductive iron or steel, and have a high likelihood of electrical connection. However, on the other hand, since it is iron or steel, the weight is large, and accuracy of fitting with the rotating shaft or the bearing attached to the rotating shaft is required, resulting in a problem that the number of processing steps increases. For this reason, the use of a resin front cover is desired from the viewpoint of weight reduction, but it is difficult to ensure the above-mentioned fitting accuracy and secure the conductive part. Was not.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to reduce the weight of an electric motor by improving conductivity and workability while adopting a resin front cover. Another object of the present invention is to maintain high assembly accuracy of an electric motor while employing a resin front cover.

  To achieve the above object, the present invention provides a case formed in a cup shape, a front cover that covers the opening of the case, an armature housed in the case and having a winding, and facing the armature A permanent magnet housed in the case, a first bearing at one end, and a second bearing at the middle, and the armature fixed between the first and second bearings. In the case ground type electric motor having a rotating shaft, the front cover is made of resin, and a ground plate electrically connected to the ground side of the winding in the resin front cover, and the winding The positive electrode plate electrically connected to the positive electrode side is disposed so as to be electrically insulated from each other and molded integrally with resin.

  In this aspect, a commutator is attached to the rotating shaft, a first brush that electrically connects the winding and the positive electrode plate, and a second that electrically connects the winding and the ground plate. It is preferable that the outer peripheral surface of the ground plate is exposed from the front cover. Preferably, a plurality of protrusions are formed on the inner peripheral surface of the front cover, and the protrusion is plastically deformed when the front cover is fitted to the outer ring of the second bearing. The peripheral surface and the second bearing may be partially fitted in the axial direction of the second bearing.

  According to the present invention, since the ground plate that can contact the casing is inserted into the resin front cover, the conductivity and workability of the front cover are improved, and the weight of the motor can be reduced. In addition, since the resin front cover has a shape that can be plastically deformed at the contact portion with the rotation shaft of the resin front cover or the bearing held on the rotation shaft, the motor can maintain high assembly accuracy.

It is the longitudinal cross-sectional view and right view of one Example of the electric motor with a brush which concerns on this invention. It is a perspective view of the front cover which the electric motor shown in FIG. 1 has. FIG. 3 is a front view of a ground plate and a positive electrode plate inserted in the front cover shown in FIG. 2. It is sectional drawing and the enlarged front view of the A section of FIG. It is a figure explaining a mode that a front cover is created.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a view of an embodiment of an electric motor with a brush according to the present invention. FIG. 1 (a) is a longitudinal sectional view thereof and FIG. 1 (b) is a side view thereof. The electric motor shown in FIG. 1 is used for an anti-lock system (ABS) of a brake device provided in a vehicle, but the present invention is not limited to that used for ABS.

  In the electric motor 100 with a brush, an annular permanent magnet 16 constituting a field of the electric motor 100 is fixed to a peripheral wall portion 12 of a case (yoke) 11 in which an iron plate is formed in a cup shape by pressing or the like. The case 11 and the permanent magnet 16 constitute a stator of the electric motor 100. An armature 43 is disposed so as to face the permanent magnet 16. The armature 43 includes a laminated steel plate (core) 41 formed by laminating die-cut silicon steel plates and the like, and a winding 42 wound around a convex pole formed on the laminated steel plate 41. . In addition, the outer surface side of the laminated steel plate 41 is molded with a mold resin to ensure insulation.

  The laminated steel plate 41 around which the winding 42 is wound is attached to the rotating shaft 32, and the pump 95 attached to one end side of the electric motor 100 is rotationally driven as the rotating shaft 32 rotates. An end portion of the rotating shaft 32 is supported by a rear side rolling bearing 34 held by a rear bearing holding portion 13 formed by pressing or the like at the center portion of the bottom portion (left end portion in FIG. 1A) of the case 11. Here, the rear bearing holding portion 13 is formed in a convex shape inside the case 11.

  In order to supply power to the winding 42, a commutator 22 is attached to the rotating shaft 32, and two brushes 21 are pressed against the commutator 22 by a spring or the like (not shown). One brush 21 is electrically connected to a power line 25 attached to the front cover 17 described later. The power supply line 25 is protected from insulation by an insulating tube 83 attached to the connecting portion 82 of the front cover 17. The other brush 21 is electrically connected to the case 11.

  The opening of the case 11 is covered with a front cover 17, and the front cover 17 is held in the case 11 by being crimped at a plurality of locations in the circumferential direction by a crimping portion 19 formed in the case 11. An opening for holding the front side rolling bearing 33 is formed at the center of the front cover 17, and a part of the front side rolling bearing 33 fixed to the rotating shaft 32 is held.

  Next, details of the front cover 17 which is a feature of the present invention will be described with reference to FIGS. FIG. 2 is a perspective view of the front cover 17. In the present invention, the front cover 17 is changed from a conventional iron plate to a resin. In the case of a front cover made of an iron plate, the weight of the front cover is heavy, and as long as a press is used for molding, the number of press processing steps increases, which contributes to an increase in cost.

  In order to eliminate these problems, the front cover is made of resin in the present invention. Therefore, it is necessary to secure an energization path. Until now, the front cover 17 has been used as a connection terminal with a brush that is electrically connected to the ground-side pole of the winding 42. That is, a brush terminal that conducts to the winding 42 is connected to an arbitrary location on the inner surface of the case 10 of the front cover 17, and the brush terminal that conducts to the ground side of the winding 42 is directly connected to the front cover 17 from the front cover 17. An energization path was secured to the case 11 in contact therewith. In the present invention, this route is secured by the following method.

  A ground plate 51 and a positive electrode plate 71 for forming a ground electrode were inserted in an intermediate portion in the axial direction of the front cover 17 made of non-conductive resin. FIG. 3 shows details of the ground plate 51 and the positive electrode plate 71. The ground plate 51 is a conductive material, specifically a copper plate, and has a circular arc part 52 from which a part of the circular ring is removed, and a radius part 54 formed at both ends and almost the center of the circular arc part. .

  The thickness t of the ground plate 51 is about t = 2 mm, and the width w of the radius portion is set in consideration of the energization amount, the contact resistance with the case 11, and the like. Since the end surface of the radius portion 54 of the ground plate 51 becomes a contact end surface 55 with the inner peripheral surface 56 of the case 11, the contact end surface 55, which is an end portion of the ground plate 51, is brought into contact with each other when the case 11 is crimped. Is exposed from the resin front cover 17. A support hole 53 for insert processing, which will be described in detail later, is formed in the arc portion 52 and the radius portion 54 of the ground plate 51.

  In the front cover 17, a positive electrode plate 71 is disposed at a circumferential portion where the arc portion of the ground plate 51 is not disposed. The positive electrode plate 71 is an L-shaped conductive material, which is a copper plate in this embodiment. The L-shaped bent upper portion 72 has a width narrower than the width of the rectangular bottom plate portion 74, so that the power line of the power line 25 can be connected. A support hole 73 for insert processing is also formed in the bottom plate portion 74 of the positive electrode plate 71. The thickness t of the positive electrode plate 71 is substantially the same as the thickness of the ground plate 51. A line (not shown) connected to the brush 21 that is electrically connected to the winding 42 of the armature 43 is connected to the surface opposite to the direction in which the upright portion 72 of the positive electrode plate 71 extends.

  By the way, the front cover 17 is used for positioning and holding the pump main body 95 which is a driving target of the electric motor 100 in addition to the energization path to the winding 42 of the armature 43. That is, the rotating shaft 32 extends to the pump body 95 side as shown in FIG. 1, and the outer ring of the front side rolling bearing 33 attached to the rotating shaft 32 is fitted to the mounting portion of the pump body 95, The pump body 95 and the electric motor 100 are positioned. At the same time, as described above, the inner peripheral surface 84 at the center of the front cover 17 is also fitted to the outer ring of the front side rolling bearing 33. That is, the front cover 17 is in a fitted state only at a part of the front side rolling bearing 33 in the axial direction.

  Conventionally, as shown in Patent Document 2, the center opening of the front cover 17 is double-folded into a U-shaped section, and the front side rolling bearing 33 is fitted into the inner opening and the pump body 95 is fitted outside. It was like that. Or as shown in patent document 1 and patent document 3, the opening part of the center part of the front cover 17 protrudes in one side, the rolling bearing 33 is formed in the inner peripheral side of the formed convex part, and the pump main body in the outer peripheral side. 95 was fitted.

  In the former case, the inside and outside of the opening are processed with tight tolerances of up to several tens of μm, and in order to process the front cover by pressing, precise pressing is required and the number of man-hours increases. ing. In the latter case, if the plate thickness of the front cover is constant, theoretically the dimensional tolerance on the outer peripheral side should be satisfied if it is pressed so as to satisfy the dimensional tolerance on the inner diameter side. Even if a plate with a constant plate thickness is originally pressed, it is fully conceivable that the plate thickness changes on the order of several tens of μm due to chucking, pressurizing force, die fitting condition, etc. Requires a lot of time and man-hours.

  Therefore, in the present invention, as shown in FIG. 4, by utilizing the feature that the front cover 17 is resinous, the molding accuracy is made uniform by molding with resin, and the necessary accuracy that may still occur. The difference from the above is that a plurality of protrusions 81 are provided on the inner peripheral side 84 of the opening of the front cover, and the protrusions 81 are plastically deformed at the time of assembly to be fitted to the outer ring of the front side rolling bearing 33 attached to the rotary shaft 32. ing.

  Thus, the electric motor 100 and the pump main body 95 can be assembled while maintaining the concentricity without applying an excessive external force to the rotating shaft 32. The protrusion 81 has a height h from the inner peripheral surface 84 of about h = 0.4 to 1.0 mm. In this embodiment, since the pump body 95 is fitted to the front side rolling bearing 33 and the electric motor 100 is cantilevered by the front side rolling bearing 33, the front side rolling bearing 33 and the rear side rolling bearing are provided. The eccentric force generated by the assembly error in the bearing 34 part and the eccentric force generated by the pump can be absorbed by the pump main body 95 side, and the occurrence of abnormality in the electric motor 100 due to these eccentric forces can be prevented.

  Next, a method for inserting the conductive ground plate 51 and the positive electrode plate 71 into the resin front cover 17 will be described with reference to FIG. FIG. 5 is a longitudinal sectional view of the resin processing apparatus. The resin processing apparatus has an upper die 92 formed with the shape of the upper surface of the front cover 17 (the right side surface in FIG. 1A) and the shape of the lower surface of the front cover 17 (the back surface of the right side surface in FIG. 1A). The formed lower mold 93 is hermetically combined.

  In order to hold the ground plate 51 and the positive electrode plate 71 in the middle of the space 90 formed by the upper die 92 and the lower die 93, the positive electrode plate 71 is formed with a plurality of support holes 73 as shown in FIG. ing. Similarly, a plurality of support holes 53 are formed in the ground plate 51. Stepped support pins 94 are disposed at positions corresponding to the support holes 53 and 73 and fixed to the lower mold 93. By inserting the end portion of the support pin 94 to the stepped portion into the support holes 73 and 53 of the positive plate 71 and the ground plate 51, the ground plate 51 and the positive plate 71 are not in contact with each other and the upper die 92 and It is held almost horizontally in the space 90 formed by the lower mold 93. At this time, the end surface 55 of the ground plate 51 is in contact with the upper die 92 or the lower die 93. Next, insert molding into the resin is performed by injecting the resin material to be molded from the injection port 91 formed in the upper die 92. Thereby, a front cover and an electrode are integrally molded.

  As described above, according to the present embodiment, the front cover is resin-molded, and the ground plate and the positive electrode plate are inserted into the resin-molded front cover. The weight of the cover can be reduced, and the weight reduction required when the vehicle is mounted can be realized. Further, since a protrusion is formed in the center portion of the front cover and the protrusion is plastically deformed to center the front cover, it is possible to reduce the eccentric load applied to the rotating shaft and the bearing of the motor. Furthermore, according to the present embodiment, press working can be omitted in the processing of the front cover, and the processing accuracy of the mounting portion of the electric motor can be improved.

DESCRIPTION OF SYMBOLS 11 ... Case (yoke), 12 ... Peripheral wall part, 13 ... Rear bearing holding part, 14 ... Flange, 15 ... Pump mounting hole, 16 ... Permanent magnet, 17 ... Front cover, 19 ... Caulking part 21 ... Brush, 22 ... Rectification , 25 ... power line, 32 ... rotating shaft, 33 ... front side rolling bearing, 34 ... rear side rolling bearing, 41 ... laminated steel plate, 42 ... winding, 43 ... armature, 51 ... ground plate, 52 ... arc part , 53 ... support hole, 54 ... radius part, 55 ... contact end face, 56 ... inner peripheral surface, 57 ... inner surface part, 71 ... positive electrode plate, 72 ... upright part, 73 ... support hole, 74 ... bottom plate part, 81 ... projection , 82 ... connection part, 83 ... insulating pipe, 84 ... inner peripheral surface, 91 ... spout, 92 ... upper mold, 93 ... lower mold, 94 ... support pin, 95 ... pump body, 100 ... electric motor.

Claims (5)

A case formed in a cup shape, a front cover covering the opening of the case, an armature housed in the case and having a winding, a permanent magnet facing the armature and housed in the case, A housing grounding type having a first bearing at one end and a second bearing at an intermediate portion thereof, and a rotating shaft having the armature fixed between the first and second bearings. In the electric motor,
The front cover is made of resin, a ground plate electrically connected to the ground side of the winding in the resin front cover, and a positive plate electrically connected to the positive side of the winding An electric motor characterized by being electrically insulated from each other and integrally molded with resin.   A commutator is attached to the rotating shaft, and a first brush that electrically connects the winding and the positive electrode plate, and a second brush that electrically connects the winding and the ground plate are provided. The electric motor according to claim 1.   The electric motor according to claim 1, wherein an outer peripheral surface of the ground plate is exposed from the front cover.   4. A plurality of protrusions are formed on an inner peripheral surface of the front cover, and the protrusions are plastically deformed when the front cover is fitted to an outer ring of the second bearing. The electric motor according to any one of the above.   The inner peripheral surface of the front cover and the second bearing are partially fitted in the axial direction of the second bearing, according to any one of claims 1 to 4. Electric motor.

Images