JP2006166646A - Brush unit for small motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To constitute a brush unit in such a manner as not only the brush unit is applied to the external terminal of a short length, but also no problem is caused in insertion of the external terminal, while securing enough spring-like force in a receptacle terminal. <P>SOLUTION: A brush unit includes a brush, a brush arm with the brush fitted, a brush base which is combined with the brush arm, and the receptacle terminal which is combined with the brush base, and is put into contact with the external terminal. The receptacle terminal is formed so that it may protrude toward an external terminal side to be inserted by cutting and raising the brush base. A combined portion with the brush base which serves as a supporting point at the root side of the receptacle terminal formed by cutting and raising is fixed to a casing lid of resin near the insert port of the external terminal, and positioning inward as compared with the insert port, then a combined portion of the brush arm and the brush base is fixed to the casing lid. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a brush device for a small motor, and more particularly, to a brush device of a type including a receptacle terminal that contacts a power supply external terminal inserted from the outside of the motor.

  FIG. 10 shows a conventional brush device for a small motor (see Patent Document 1). Usually, a small motor houses a rotor formed by assembling various parts on a shaft together with a magnet as a stator side magnetic pole in a motor case, and a case lid is fitted into the opening of the motor case. It is constituted by. Further, this case cover is usually provided with a brush and its electrical and mechanical connection configuration. FIG. 10A is a view of such a case lid as viewed from the inner side of the motor. FIG. 10B is an enlarged view of the vicinity of the receptacle terminal.

  Each of the pair of brush devices includes a brush, a brush arm, and a brush base. In this conventional brush device, the brush arm is bent into an L shape and fixed to the brush base at a fixed portion. The tip of the brush base functions as a receptacle terminal, and the contact portion is in electrical contact with a pair of external terminals inserted from the external terminal insertion port.

  In such a brush device, it is required to be applied to an external terminal having a short length according to the type of connector to be externally connected. There is a potential demand for shortening the external terminals to reduce costs and improve workability. In order to adapt to a short external terminal, it is necessary to set the apex (contact portion) of the receptacle terminal to a position (L dimension) close to the external terminal insertion port, and therefore, there is a problem that the receptacle terminal cannot be lengthened. . If the receptacle terminal is short, a sufficiently good spring property cannot be secured. In other words, if the receptacle terminal is shortened, the influence of the sag of the receptacle terminal increases due to the thickness of the external terminal. Accordingly, the contact pressure variation between the external terminal and the receptacle terminal increases, and the contact reliability decreases. Further, in this structure, it is impossible to incorporate a burnout protection element such as PTC.

  In Patent Document 1, a receptacle terminal is formed by cutting and raising from one end of a brush base, as shown in FIG. 11, so as to be applicable to an external terminal having a short length while ensuring sufficient springiness. At the same time, the brush base is fixed to the case lid at two locations, one end of the brush base and the other end of the brush base joined to the brush arm. FIG. 11A is a view of such a case lid as viewed from the inner side of the motor. FIG. 11B is an enlarged view of the vicinity of the receptacle terminal.

  With the configuration shown in the drawing, it is possible to meet the requirement of shortening the external terminal (desiring to shorten the L dimension), but depending on the processing accuracy of the receptacle terminal portion, the state of the dotted line shown in FIG. There is a possibility that the problem may occur in the insertability of the external terminal by interfering with the terminal tip. For this reason, in the production process, a separate preliminary opening process for expanding the receptacle terminal insertion gap in advance is required, resulting in a decrease in productivity. Moreover, it is impossible to incorporate a burnout protection element such as PTC.

  FIG. 13 shows a receptacle terminal structure having a two-stage spring configuration (see Patent Document 2). The receptacle terminal with the external terminal inserted is shown on the left side of the figure, and the receptacle terminal without the external terminal is shown on the right side of the figure. The receptacle terminal is bent about two places, pivot point A and pivot point B. The receptacle terminal portion is generally V-shaped and contacts the external terminal at the apex of the V-shape.

  By bending the tip of the receptacle terminal substantially in the same direction as the external terminal insertion direction (that is, the receptacle terminal that has been directed from the bottom to the top in the figure is further from the top to the bottom), The problem about the insertability of the external terminal is eliminated. However, it is necessary to bend the receptacle terminal into a U-shape, and in addition, it is necessary to lengthen the straight portion of the receptacle terminal in order to ensure good springiness of the receptacle terminal, and the motor cannot be reduced in size. In addition, it is necessary to lengthen the material of the receptacle terminal, which increases the cost. Furthermore, since it is necessary to bend the pair of receptacle terminals from the outside to the inside (the direction in which they approach each other), there is a limit to increasing the distance between the receptacle terminals, and the pitch of the external terminals (the distance between the + and − terminals) ) Cannot be adopted when it becomes large.

In response to a request to shorten the external terminal, it is necessary to reduce the R of the U-shaped bent portion and bring the U-shaped bent portion closer to the external terminal contact portion. In this case, the distance between the fulcrum of the receptacle terminal and the working point Becomes shorter, and the stress when the external terminal is inserted concentrates on the spring fulcrum of the U-shaped bend. As a result, the spring sags, the contact pressure decreases and the variation increases, and the contact reliability decreases.
Japanese Patent No. 3523546 Japanese Utility Model Publication No. 2-122558

  The present invention solves such problems and makes it possible not only to be applied to an external terminal having a short length while ensuring sufficient springiness for the receptacle terminal, but also to have a configuration in which the problem of insertability of the external terminal does not occur. Thus, it is an object of the present invention to improve productivity by eliminating the need for a separate process for previously widening the insertion portion gap of the receptacle terminal.

  In addition, the present invention is flexible to change the design so as to increase the interval between the receptacle terminals corresponding to the pitch of the external terminals to be used or to incorporate a burnout protection element. It aims to make it possible to respond to

  A brush device for a small motor according to the present invention includes a pair of brushes that are in sliding contact with a commutator of the motor, a pair of brush arms each having the brush attached to one end, and a pair of brush arms that are coupled to the brush arm at one end. A brush base and a pair of receptacle terminals coupled to the brush base and supplied with power by contacting the external terminals inserted from the outside into a pair of external terminal insertion openings opened in the motor case lid; ing. This receptacle terminal is formed so as to protrude from the vicinity of the other end of the brush base to the side of the external terminal to be inserted. Resin case cover with the coupling portion with the brush base that becomes a fulcrum on the base side of the cut and raised receptacle terminal being positioned inward of the pair of external terminal insertion ports and inward of the external terminal insertion ports And the joint between the brush arm and the brush base is fixed to the case lid.

  According to the present invention, it is possible not only to make the receptacle terminal applicable to a short external terminal while ensuring sufficient springiness, but also to prevent an external terminal insertion problem.

  According to the present invention, since the receptacle terminal can be positioned from the oblique direction inside the motor with respect to the external terminal and the length thereof can be made relatively long, the contact pressure of the terminal against the variation in the thickness of the external insertion terminal The difference is small. This also makes it possible to improve the insertion workability of the external insertion terminal, reduce the preliminary opening process of the receptacle terminal, incorporate a burnout protection element, improve the contact reliability of the external terminal, and reduce the size of the motor.

  Furthermore, the size of the pitch of the external terminal can be accommodated by changing the position of the protrusion of the receptacle terminal and the protrusion of the case cover inward and outward, so the external terminal insertion port and the receptacle terminal The layout can be easily changed.

  FIG. 1 is a diagram showing the external shape of a small motor that embodies the present invention, wherein (A) is a left side view, (B) is a top view, (C) is a front view, and (D) is a front view. The right view seen from the case lid side is shown. 2 is a diagram showing the same small motor as in FIG. 1, FIG. 2 (A) is a top view corresponding to FIG. 1 (B), and FIG. 2 (B) is FIG. The front view corresponding to (C) shows the upper half in section.

  Except for the configuration of the brush device and the case lid to which the brush device is attached, the present invention is not particularly different from a conventional small motor known in the art. For example, as shown in FIG. 2B, this normal motor has a case cover made of a synthetic resin fitted in an opening portion of a motor case formed of a metal material in a bottomed hollow cylindrical shape. . A bearing for the shaft is accommodated in the central portion of the case lid. The other end of the shaft is supported by a bearing provided at the bottom center of the motor case. The shaft is normally provided with a laminated core, a winding wound on the laminated core, and a commutator, and constitutes a rotor of a small motor. And a pair of carbon brush which contacts this commutator is supported by the brush apparatus which is the characteristics of this invention so that the detail may mention later.

  3 is a view showing only the case lid taken out from the small motor shown in FIGS. 1 and 2, (A) is a view as seen from the upper surface side with the external terminal insertion port, and (B) is a view. It is the figure which looked at the inside from the inside. FIG. 4 is an enlarged perspective view showing the vicinity of the receptacle terminal shown in FIG. FIG. 5A is a view showing the brush base taken out, and FIG. 5B is a view showing a state where the brush arm is coupled to the end of the brush base by caulking. The illustrated brush device is provided with a pair of symmetrical configurations that can be used in common on the + side and the − side symmetrically, respectively, a carbon brush that is in sliding contact with the commutator, a brush arm that press-fits the brush, and a brush It is composed of an arm and a brush base joined by caulking. The brush arm material is, for example, beryllium copper, and the brush base material is, for example, phosphor bronze for spring or white for spring. This caulking is performed, for example, by inserting a protrusion provided on the coupling surface side of the brush base into a hole provided corresponding to the brush arm and then crushing the protrusion tip by applying pressure to the protrusion. The brush base is provided with a receptacle terminal formed by cutting and raising the central portion in the width direction from near the end opposite to the brush arm coupling end side. Therefore, the receptacle terminal is cut and raised from the brush base. When this occurs, a hole corresponding to this cut and raised is opened in the central portion of the brush base. Even after the cutting and raising, the brush bases on both sides and the base side of the receptacle terminal have at least enough width to allow a predetermined current to flow and to mechanically support the receptacle terminal.

  As shown in FIG. 3, the brush device having such a configuration is fixedly held on the case lid. The case lid can be made of synthetic resin, and can be fixed by a resin protrusion for fixing the brush device formed integrally with the case lid, and a groove formed by the protrusion. At that time, the brush device is fixed at three locations: a caulking joint portion between the brush arm and the brush base, a brush base tip side which is a base portion where the receptacle terminal is cut and raised, and a curved portion at the center of the brush base. With such a configuration, the length of the receptacle terminal can be sufficiently secured, and furthermore, the contact portion (operation point) with the external terminal can be provided at the external terminal insertion port even though the receptacle terminal is sufficiently long. Therefore, the present invention can be applied to an external terminal having a short length. A DC power supply for the motor is supplied from the pair of external terminals.

  As shown in FIG. 3 (B), the brush base end on the side integrally connected to the receptacle terminal, in other words, the fulcrum of the receptacle terminal is near the external terminal insertion port and closer to the outer periphery of the case lid than the external terminal insertion port. It is fixed between the outer peripheral wall of the case lid and the projection at an inward position along. Further, the other end of the brush base is fixed between the outer peripheral wall of the case lid and the protrusion at a position substantially opposite to the external terminal insertion port. A brush arm is caulked and fixed to the other end of the brush base.

  The receptacle terminal formed by cutting and raising from the brush base is formed so that the tip direction from the base (fulcrum) is the external terminal insertion direction and obliquely outward (the direction from the inside of both external terminals to the outside). Has been. In other words, the cut-and-raised base is in a position retracted inward along the outer peripheral wall of the case lid from the external terminal insertion port. As a result, even if the vertical distance from the external terminal insertion opening to the external terminal contact point is shortened, the receptacle terminal can be formed longer by the amount formed obliquely.

  Also, it must be adaptable to external terminals with different thicknesses. Generally speaking, when a thin external terminal is inserted, the contact pressure tends to be insufficient and a contact failure tends to occur. On the other hand, when a thick external terminal is inserted, the contact pressure becomes excessive and inserted. It tends to be difficult. According to the present invention, as described above, the fulcrum of the receptacle terminal can be provided at a position retracted in the horizontal direction, and the length of the receptacle terminal can be secured. Reliability is improved and the difference in contact pressure between the external terminal and the receptacle terminal due to a change in the thickness of the external terminal is reduced.

  As shown in FIG. 4, the fixed end portion of the brush base is fixed so as to be sandwiched between the resin case lid and the protrusion 1 integrally formed therewith. The receptacle terminal is cut and raised with the vicinity of the end as a base. The receptacle terminal is cut and raised so that it protrudes outward from the bent brush base surface (to the external terminal side). At the fulcrum of the cut and raised, it comes into contact with the case lid that fixes the brush base and becomes a fulcrum of the receptacle terminal. . In the receptacle terminal, when the external terminal comes into contact with the contact portion near the tip and receives contact pressure, the root portion integrally coupled with the brush base acts as a rotation fulcrum. Since the base side of the receptacle terminal is supported by the arcuate (R-shaped) surface of the resin protrusion, the stress acting on the base side of the rotating receptacle terminal can be dispersed.

  The brush base whose end is supported at a position inward of the external terminal insertion port (a direction in which the pair of external terminals approach each other) is directed toward the external terminal insertion port along the outer periphery of the case lid, and then the external terminal In order to avoid this in front of the insertion port, it is bent substantially vertically in the external terminal insertion direction, and then bent toward the outer periphery of the case lid at a position where the inserted external terminal does not reach. And it is bent again from the case lid outer peripheral side. The curved portion is fixed by being sandwiched between the resin protrusions 2, 3 and 4 integrally formed with the case lid (see FIG. 4). From there, the brush base is further extended and coupled to the brush arm at the position of the outer peripheral wall of the case lid substantially facing the external terminal insertion port. The coupling portion is sandwiched and fixed between the case lid outer peripheral wall and the protrusion.

  FIG. 6 shows another example of the brush device. FIG. 6 (A) is the same as FIG. 3 (B) described above except that a PTC is inserted, and details of the Y portion in the figure are shown in FIG. 6 (B). . A PTC is a resistor having an electrical resistance value of PTC (positive temperature coefficient) characteristics that increases with an increase in temperature, and is commonly used in, for example, an automobile door lock motor as a burnout protection element against overcurrent. It is used for. The PTC can be inserted into each of the pair of brush devices, but is usually inserted into only one of them.

  FIG. 7A shows the same brush base as shown in FIG. 5A, and FIG. 7B shows the brush base cut at the PTC insertion position. By disposing the PTC in the middle of the brush base, the PTC is connected in series to the receptacle terminal and the brush arm. FIG. 8 is a perspective view showing a view corresponding to FIG. 6B, FIG. 8A shows a state before PTC press-fitting, and FIG. 8B shows a state where PTC is press-fitted. . Each of the front and back surfaces of the PTC is an electrode. When the PTC is press-fitted, both ends on the cut side of the brush base come into contact with the electrodes on both the front and back surfaces of the PTC. Thus, the brush base of the present invention can be easily attached with the burnout protection element.

  FIG. 9 shows another example brush base different from that described above with reference to FIG. In the example described above, the receptacle terminal is formed by cutting and raising the central portion of the brush base in the width direction, whereas in the example shown in FIG. 9, either side of the brush base in the width direction is cut and raised. It is formed. The thus configured brush base and receptacle terminal are assembled and function in exactly the same manner as in the previous example.

It is a figure which shows the external appearance shape of the small motor which actualizes this invention. It is a figure which shows the same small motor as FIG. 1 with a diagram. It is a figure which shows only the case cover taken out from the small motor shown in FIG.1 and FIG.2. It is a perspective view which expands and shows the receptacle terminal vicinity shown in FIG.3 (B). (A) is a figure which takes out and shows a brush base, (B) is a figure shown in the state by which the brush arm was couple | bonded with the edge part of the brush base by caulking. It is a figure which shows another example of a brush apparatus. (A) is the same brush base as shown in FIG. 5 (A), and (B) is a diagram showing the brush base cut at the PTC insertion position. FIG. 6B is a perspective view showing a diagram corresponding to FIG. 6B, and FIG. 6A is a diagram showing a state before PTC press-fitting, and FIG. 6B is a diagram showing a state in which PTC is press-fitted. It is a figure which shows the brush base of an example different from what was mentioned above with reference to FIG. It is a figure which shows the brush apparatus of the conventional small motor. It is a figure which shows another brush apparatus of the conventional small motor. It is a figure explaining the insertability problem of an external terminal. It is a figure which shows another brush apparatus of the conventional small motor.

Claims (4)

A pair of brushes in sliding contact with the commutator of the motor; a pair of brush arms each having the brush attached to one end; a pair of brush bases coupled to the brush arm at one end; and the brush base coupled to the brush base And a pair of receptacle terminals to which power is supplied in contact with external terminals inserted from the outside into a pair of external terminal insertion openings opened in the motor case lid,
The receptacle terminal is formed so as to protrude from the vicinity of the other end of the brush base to the external terminal side to be inserted,
The coupling portion with the brush base that becomes a fulcrum on the base side of the cut and raised receptacle terminal is positioned near the pair of external terminal insertion ports and inward from the external terminal insertion ports, and is made of resin. Fixed to the case lid, and the joint between the brush arm and the brush base was fixed to the case lid,
This is a brush device for a small motor. The connection of the receptacle terminal to the brush base is fixed by being sandwiched between a protrusion formed integrally with the resin case lid and the outer peripheral wall of the resin case lid, and the receptacle terminal The brush device for a small motor according to claim 1, wherein the outer surface of the protrusion that contacts the base side is formed in an arc shape. 2. The brush device for a small motor according to claim 1, wherein the brush base is cut halfway, and a burnout protection element connected in series therewith is fixed to the case lid. The brush device for a small motor according to claim 1, wherein the receptacle terminal is formed by cutting and raising a central portion or an end portion of the brush base in the width direction.

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