JP6193071B2 - DC motor - Google Patents

Description

  The present invention relates to a DC motor, and more particularly to a brushed DC motor suitable for use in a vehicle.

  Examples of conventional DC motors are described in Patent Documents 1 to 3. In the DC motors described in these publications, a stator having a permanent magnet is held in a metal yoke formed in a bottomed cylindrical shape, and a winding type rotor that generates a rotating magnetic field is arranged opposite to the stator. Then, a flat lid member is brought into contact with the bottomed cylindrical yoke via a brush holder.

  More specifically, in the rotating electrical machine described in Patent Document 1, the opening of the yoke of the electric motor is closed with the brush holder of the power supply unit. On the brush holder, a pair of power supply terminals connected to the brush are fixed by outsert molding. A predetermined interval is formed between the input side fixed column and the brush side fixed column on the brush holder, and a choke coil is installed between the brush side terminal and the input side terminal instead of the power supply terminal. It is possible.

  In addition, in the electric motor described in Patent Document 2, two annular ferrite cores and two capacitors are arranged in the brush holder in addition to the carbon brushes arranged at intervals of 90 degrees in order to prevent electrical noise. And it positions on a brush holder so that only the conductor part which the wiring which supplies electric power to a carbon brush may expose may be located in the center part of a ferrite core.

  Further, in the small motor described in Patent Document 3, three spaces are formed on the inner surface side of the case lid that covers the opening of the case and forms a sealed cylindrical container together with the case, and a chip capacitor is accommodated in each space. ing. As a result, the third capacitor can be connected in parallel to the two capacitors connected in series, and electrical noise can be reduced in the low frequency band.

JP 2012-138994 A JP 2012-70512 A International Publication No. WO01 / 39354

  In a DC motor having a brush, in order to reduce noise generated by the brush of the motor, a capacitor as a capacitance or a choke coil as an inductance may be provided inside or outside the motor. It is known that when an LC filter circuit is formed by a capacitor and a choke coil, particularly high frequency noise can be effectively reduced.

  By the way, in an in-vehicle DC motor, an allowable value of noise generated by a brush is strictly determined in order to eliminate adverse effects on other in-vehicle electric components. This regulation is called EMC (electric magnetic compatibility) and is internationally defined as, for example, the IEC standard.

  In Patent Document 1, in order to reduce the size of the electric motor regardless of the presence or absence of an element that reduces noise generated by the electric motor, a predetermined interval is set between the input side fixing column and the brush side fixing column on the brush holder. The feeding terminal and the choke coil can be selectively attached. However, this Patent Document 1 does not consider the influence on the capacitor due to the withstand voltage test of the motor when the capacitor is attached as a countermeasure against noise generated by the brush.

  In Patent Document 2, a ferrite core and a capacitor are used as a measure against electric noise, and these elements are arranged on the upper surface of the brush holder. In Patent Document 3, a chip capacitor is arranged on the upper surface of the brush holder. However, these Patent Documents 2 and 3 do not consider that the capacitor is influenced by the withstand voltage test of the motor.

  When a dielectric breakdown voltage test of a DC motor is performed with the capacitor connected, a current flowing through the capacitor is generated even when the load voltage is small, and this may be confused with the breakdown current. Further, when the load voltage is set to a large voltage, the withstand voltage of the capacitor may be exceeded and the capacitor may be broken down. For this reason, in the dielectric strength test of the electric motor, it is desirable that the capacitor is removed. However, after the capacitor is installed in the brush holder, it is difficult to remove the capacitor and perform the dielectric strength test. In order to solve this problem, if the capacitor is assembled to the brush holder after the withstand voltage test, the assembly process is increased.

  The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to make it possible to easily and reliably perform a withstand voltage test of a DC motor without increasing the shape of the DC motor for vehicle use. There is. Another object of the present invention is that when a choke coil and a capacitor are used as a countermeasure against noise generated by a brush in a 4-pole 6-slot type DC motor, protrusions other than electrodes are provided on the motor flange surface (metal cover surface). An object is to enable an easy dielectric strength test to be performed without forming.

A feature of the present invention that achieves the above object is that a permanent magnet is disposed on the inner peripheral side of the yoke, and an armature having windings and laminated steel plates is provided so as to face the permanent magnet, and is electrically connected to the armature. In a DC motor including a brush, an insulating brush plate to which a brush holder for holding the brush is attached, and a conductive metal cover that covers the open portion side of the yoke in combination with the brush plate are provided. The brush plate is provided with a choke coil on the surface side facing the armature, and the capacitor is provided in a groove provided on the surface side where the brush plate is combined with the metal cover, and one lead wire of the capacitor is the choke coil. are electrically connected to the other lead et provided to be electrically connected to the metal cover after withstand voltage test It lies in the fact that.

In this feature, the armature is constituted by four poles and six slots, and two brushes may be arranged on the brush plate at a pitch of approximately 90 degrees. It is even better if they are arranged approximately symmetrically on the side having a wide circumferential interval. Further, two capacitors are provided, and it is desirable that the capacitor and the choke coil are disposed with the brush plate interposed therebetween, and the vicinity of the groove on the brush plate for accommodating the capacitor. It is preferable that a protrusion is provided on the capacitor, the lead wire on the connection side of the capacitor with the metal cover is disposed on the upper surface of the protrusion , and the lead wire shape is a crank shape. Furthermore, an insert terminal for electrically connecting the capacitor and the choke coil may be disposed between the brush plate and the metal cover.

  According to the present invention, in the in-vehicle DC motor, a groove is provided on the surface side of the brush plate facing the metal cover, and a hole corresponding to the groove is provided in the metal cover, and an electromagnetic noise countermeasure capacitor is accommodated in the groove. Because one lead wire of the capacitor is electrically connected to the choke coil arranged on the back side of the brush plate, and the other lead wire of the capacitor is electrically connected to the metal cover after the dielectric strength test, the motor shape is greatly increased. Therefore, the dielectric strength test of the DC motor can be easily and reliably performed. In addition, in a 4-pole 6-slot type DC motor, a dielectric strength test can be easily performed without forming protrusions other than electrodes on the surface of the metal cover of the motor.

1 is an external perspective view of an embodiment of a DC motor according to the present invention. It is a longitudinal cross-sectional view of the DC motor shown in FIG. It is a perspective view of the metal cover with which the DC motor shown in FIG. 1 is provided. It is a perspective view of the brush plate with which the DC motor shown in FIG. 1 is provided. It is a top view of the brush plate shown in FIG. It is a rear view of the brush plate shown in FIG. It is a rear view of the brush plate shown in FIG. 4, and is a figure before mounting each component. It is a perspective view of the brush holder mounted in the brush plate shown in FIG. It is a perspective view of the insert terminal mounted in the brush plate shown in FIG. It is a perspective view of the capacitor | condenser mounted in the brush plate shown in FIG.

  Hereinafter, an embodiment of a DC motor according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an embodiment of a DC motor 100, showing a connection side with a driven member as an upper surface. FIG. 2 is a longitudinal sectional view of the DC motor 100 shown in FIG.

  The DC motor 100 according to the present embodiment is a brushed DC motor. A permanent magnet 16 that forms a field of the DC motor 100 and is arranged in an annular shape is fixed to an inner wall portion of a case (yoke) 12 in which an iron plate is formed in a substantially cup shape by pressing or the like. Case 12 and permanent magnet 16 constitute a stator of DC 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 rotary shaft 32 and rotationally drives a driven member such as a pump attached to one end of the DC motor 100 as the rotary shaft 32 rotates. One end portion of the rotating shaft 32 is supported by a rear 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. 2) of the case 12. In the present embodiment, the rear bearing holding portion 13 is formed in a convex shape inside the case 12. In the present embodiment, a gear 35 is attached to the distal end side of the rotating shaft 32, and is used to drive the driven member by decelerating or accelerating it.

  In order to supply power to the winding 42, the commutator 22 is attached to the rotating shaft 32. Two brushes 21 are urged against the commutator 22 by a coil spring 57. The brush 21 is electrically connected to the brush plate 17. A choke coil 55 is disposed on the brush plate 17 to which the brush 21 is not attached. As will be described in detail later, the choke coil 55 is electrically connected at one end to one lead wire 53 of a capacitor 50 attached to the opposite surface of the brush plate 17. The capacitor 50 includes a lead wire 52 on the side electrically connected to the metal cover 18, a lead wire 51 electrically connected to the choke coil 55, and a capacitor body 50.

  The opening of the case 12 is covered with a metal cover 18, and the metal cover 18 is engaged with the brush plate 17. An opening 59 (see FIG. 7) is formed at the center of the brush plate 17 and the metal cover 18 to hold the front rolling bearing 33. The front bearing holding portion 14 is connected to the opening 59. ing. The front bearing holding portion 14 a of the metal cover 18 holds the front rolling bearing 33 fixed to the rotating shaft 32 together with the front bearing holding portion 14 b (see FIG. 4) formed on the brush plate 17. A flange 11 is formed on the outer periphery of the case 12, and a bolt is inserted into an attachment hole 11 a with the driven member formed on the flange 11 to attach the DC motor 100 to the driven member.

  FIG. 3 is a perspective view showing a top view of the conductive metal cover 18 manufactured by pressing a steel plate or the like. As shown in FIG. 3, a plurality of holes 65 and grooves 61 are formed on the upper surface side of the metal cover 18, and the capacitor 50 is held by the brush plate 17 below the elongated hole 61. Is placed. The hole 65 is for positioning and fixing the brush plate 17 to the metal cover 18. After fitting the protrusion 73 (see FIG. 4) formed on the brush plate 17 into the hole 65, heat is applied. The protrusion of the brush plate 17 is deformed and fixed to the metal cover 18. The groove 62 is a groove for the terminal 24 for supplying electric power to the DC motor 100, and is provided at a substantially symmetrical position in the circumferential direction.

  Next, an embodiment of the brush plate 17 will be described with reference to FIGS. First, the state of the upper surface of the brush plate 17 will be described. FIG. 4 is a perspective view of the brush plate 17, with the surface facing the metal cover 18 being the top surface. FIG. 5 is a top view of FIG.

  The brush plate 17 of this embodiment is an insulator and is manufactured by resin injection processing or the like. The upper surface side of the brush plate 17 has a shape corresponding to a plurality of holes and grooves provided in the metal cover 18. That is, a terminal holding portion 71a with a slit in which a rectangular groove for penetrating the terminal 24 is formed, and the height is lower than the terminal holding portion 71a with a slit and is formed around the terminal holding portion 71a with a slit. Even when the cover 18 is attached, two terminal protrusions 71 including the base portion 71b that secures an insulation distance are provided at two axially symmetrical positions.

  Further, as described above, in order to ensure engagement with the metal cover 18, circular protrusions 73 are provided at a plurality of locations on the upper surface. Further, in order to stably hold the capacitor 50, the coil connection through which the lead wire 53 is passed for electrical connection between the capacitor holding means 75c having a groove depth deeper than the size of the capacitor body 51 and the choke coil 55. The capacitor holding means 75 is formed by the hole 75a and the lead wire holding groove 75b provided at the boundary between the coil connecting hole 75a and the capacitor holding means 78c. A peripheral portion of the capacitor holding means 75 forms a capacitor projection 72 that is an elliptical projection edge corresponding to the capacitor hole 61 formed in the metal cover 18. These are arranged substantially axisymmetrically below the line with reference to a line connecting the protrusions 71 for the terminal 24 in FIG.

  A lead wire holding projection 76 extending in a direction substantially perpendicular to the direction in which the lead wire 52 extends is formed in the vicinity of the capacitor projection 72 and on the portion where the lead wire 52 of the capacitor 50 is placed on the upper surface. . The lead wire holding projection 76 overlaps with the projection provided at the corresponding position of the metal cover 18, and when connecting the lead wire 52 to the metal cover 18 by spot welding or the like, the generated heat is concentrated and welding workability is improved. It is provided to improve.

  Next, the state of the back surface of the brush plate 17 will be described with reference to FIGS. 6 is a rear view of FIG. 4 in which various parts are mounted, and FIG. 7 is also a rear view of FIG. 4 showing the brush plate 17 alone before mounting the various parts.

  Slits 71 c through which the terminals 24 are inserted are formed on the left and right sides of the central bearing holding hole 59. With reference to the slit 71c, a brush holder locking groove 17e, which will be described in detail later, is provided on the upper side in FIG. The brush holder groove 17e is a groove having a depth approximately equal to the plate thickness of the brush holder 56, and is at the same height as the surface of the brush plate 17 when the brush holder 17e is locked. A protrusion 17h is formed in the brush holder groove 17e near the center in the left-right direction and the slit 71c for the terminal 24. A hole formed in the brush holder 56 is engaged with the protrusion 17 h to fix the brush holder 56 to the brush plate 17. On the outer peripheral side of the brush holder groove 17e, a coil holding projection 17b extending in the axial direction (the front side in FIG. 6 and FIG. 7) is provided. The coil holding projection 17b is provided to hold a coil spring that obtains an urging force when the brush 21 is brought into contact with the commutator 22.

  FIG. 8 is a perspective view of the brush holder 56. The lower side of the figure is the outer peripheral side, and the upper side of FIG. 8 is the inner peripheral side, that is, the side where the brush 21 contacts the commutator 22. The brush holder 56 includes a rectangular brush holding box portion 91 that accommodates a brush, a pigtail connection portion 94 located on the outer peripheral side, and a coil connection portion 92 located on the inner peripheral side. The coil connection portion 92 has a coil connection plate portion 92a bent at a right angle, and the lead wire 55a of the choke coil 55 is connected to the coil connection plate portion 92a. Holes 94a and 92b are formed in the pigtail connection portion 94 and the coil connection portion 92, respectively, and a protrusion 17h formed on the brush plate 17 is fitted therein. Then, by heating the brush plate 17, the protrusion 17 h is deformed and the brush holder 56 is fixed to the brush plate 17. A groove (not shown) is formed on one side surface of the brush holding box portion 91 of the brush holder 56 so that the pigtail 21b attached to the brush 21 can move as the brush 21 wears.

  A rectangular coil holding groove 17c is formed below the slit 71c in FIG. The coil holding groove is dug down so as not to interfere with the winding 42 of the opposing armature 43 when the choke coil 55 is held inside. Coil holding projections 17c are provided on the three sides around the coil holding groove 17d to prevent the choke coil 55 from vibrating or moving when the DC motor 100 is mounted on an automobile or the like.

  In FIG. 7, hatching indicates an insert terminal 80 disposed on the front side (back side in FIG. 7) of the brush plate 17 and between the metal cover 18. Two insert terminals 80 are arranged on the upper surface of the brush plate 17 excluding a portion where the two brush holders 56 are arranged, and are positioned with a slight gap on the lower side of FIG. The insert terminal 80 is insert-molded on the brush plate 17 and is already held in the mold when heat-caulked.

  As shown in FIG. 9, the insert terminal 80 has a shape obtained by bending a body plate. A terminal 24 for power input is bent at one end, and the other end is opposite to the terminal 24. A coil lead wire support portion 82 that holds the lead wire 55b of the choke coil 55 by bending in the direction is formed. A connection portion 81 to which one lead wire 53 of the capacitor 50 is connected is formed in the vicinity of the coil lead wire support portion 82. As shown in FIG. 7, a bent plane is formed between the connection portion 81 and the terminal 24.

  A groove 17g is formed around the coil holding groove 17d on the back side of the brush plate 17 and in the vicinity of the portion where the coil holding protrusion 17c is not formed. A support portion 82 that supports the lead wire 55b of the choke coil 55 formed in the insert terminal 80 is inserted into the groove 17g. In order to electrically connect the lead wire of the choke coil 55 to the lead wire 53 of the capacitor 50 in the vicinity of the groove 17g, a hole 17g for exposing the insert terminal 80 and a groove connected thereto are formed. By connecting the lead wire 55b of the choke coil 55 to the back side of the hole 17g and the lead wire 53 of the capacitor 50 to the surface side of the hole 17g, both are electrically connected.

  The connection of the capacitor 50 will be described with reference to FIG. The capacitor 50 is temporarily held in the groove 61 provided on the surface side of the brush plate 17 after the lead wire 53 on the side electrically connected to the connection portion 81 of the insert terminal 80 is connected in a substantially straight state. Is done. In this state, the DC motor 100 is assembled, a voltage higher than the voltage normally used is loaded between the terminals 24, and the dielectric strength test is performed. Thereby, insulation failure is extracted. At this time, since the other lead wire 52 of the capacitor 50 forms the crank portion 52b between the horizontal portions 52a and 52c, it is prevented from being brought into contact with the metal cover 18 to be conducted.

  After the dielectric strength test, the lead wire 52 is welded to the metal cover 18 by spot welding or the like so as to form an RC circuit that is a noise removal circuit in normal use. Here, since the height position of the lead wire 52 of the capacitor 50 is made lower than the flange surface of the metal cover 18, it is avoided that the axial length of the DC motor 100 becomes longer due to the addition of the capacitor 50.

  As described above, according to the present invention, the brushes are arranged at an interval of approximately 90 degrees on the back side of the brush plate, and a pair of choke coils are partially embedded on the wide side between the brushes. Further, the capacitor is arranged so as to be embedded on the surface side of the brush plate, and one lead wire thereof is electrically connected to the choke coil, so that the noise generated by the brush is reduced without increasing the size of the DC motor. An RC circuit can be formed.

  In addition, since the dielectric strength test can be performed without connecting the other terminal of the capacitor, it is possible to prevent the occurrence of a situation where the charge added as a result of connecting the capacitor flows into the capacitor and is detected as a leakage current. Since there is no internal work of the DC motor after the insulation test, it is only necessary to connect the terminal of the capacitor to the metal cover on the outside, and the processing is easy and the number of processing steps can be reduced.

DESCRIPTION OF SYMBOLS 11 ... Flange, 11a ... Mounting hole, 12 ... Case (yoke), 13 ... Rear bearing holding part, 14-14b ... Front bearing holding part, 16 ... Permanent magnet, 17 ... Brush plate, 17b ... Spring contact member, 17c Coil holding protrusion, 17d Coil holding groove, 17e Brush holder groove, 17f Pigtail stopper, 17g Coil lead wire support groove, 18 Metal cover, 21 Brush, 21b Pigtail, 22 Commutator, 24 ... terminal, 32 ... rotary shaft, 33 ... front (rolling) bearing, 34 ... rear (rolling) bearing, 35 ... gear, 41 ... laminated steel sheet, 42 ... winding, 43 ... armature, 50 ... capacitor 51 ... Capacitor body 52 ... Lead wire 52a ... Horizontal portion 52b ... Bent portion 52c ... Horizontal portion 53 ... Lead wire 55 ... Choke coil 55a, 55b ... Lead wire 56 ... Brush holder 56a ... Coil connection part 56b ... Pigtail connection part 57 ... Brush spring 59 ... Bearing holding hole 61 ... Capacitor hole 62 ... Terminal hole 65 ... Brush plate fixing hole 71 ... Terminal projection, 71a ... Terminal holding portion with slit, 71b ... Base portion, 71c ... Slit, 72 ... Capacitor projection, 73 ... Metal cover locking portion, 75 ... Capacitor holding means, 75a ... Hole for coil connection 75b: Lead wire holding groove, 75c: Capacitor body holding groove, 76: Lead wire holding projection, 80 ... Insert terminal, 81 ... Connecting portion, 82 ... Coil lead wire support portion, 83 ... Insert portion, 91 ... Brush holding Box part, 92 ... Coil connection part, 92a ... Coil connection plate part, 94 ... Pigtail connection part, 100 ... DC motor.

Claims (6)

In a DC motor having a brush disposed on the inner peripheral side of the yoke, provided with an armature having a winding and a laminated steel plate so as to oppose the permanent magnet, and having a brush conducting to the armature,
An insulator brush plate to which a brush holder for holding the brush is attached, and a conductive metal cover that covers the open side of the yoke in combination with the brush plate are provided, and the brush plate is attached to the armature. A choke coil is provided on the opposite surface side, a capacitor is provided in a groove provided on the surface side where the brush plate is combined with the metal cover, and one lead wire of the capacitor is electrically connected to the choke coil. The other lead wire is provided so that it can be electrically connected to the metal cover after the dielectric strength test.   2. The DC motor according to claim 1, wherein the armature is constituted by four poles and six slots, and two brushes are arranged on the brush plate at a pitch of approximately 90 degrees.   3. The DC motor according to claim 2, wherein the choke coils are disposed substantially symmetrically on a side between the brushes and on a wide circumferential interval. 4.   4. The DC motor according to claim 2, wherein two capacitors are provided, and the capacitor and the choke coil are arranged with the brush plate interposed therebetween. 5. Protrusion is provided on the brush plate in the vicinity of the groove for accommodating the capacitor, and the lead wire on the connection side with the metal cover of the capacitor is disposed on the upper surface of the protrusion , and the shape of the lead wire is The DC motor according to any one of claims 1 to 4, wherein the DC motor has a crank shape.   6. The DC motor according to claim 1, wherein an insert terminal for electrically connecting the capacitor and the choke coil is disposed between the brush plate and the metal cover.

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