JPH02280648A - Motor brush - Google Patents

Abstract

PURPOSE:To protect a brush against cut or crack, when a pigtail is fixed thereto, and to maintain good commutation characteristic of split type brush by providing thick sections on a plurality of thin board brushes to be laminated splittably. CONSTITUTION:A brush 4 contacting with a commutator 1 comprises two thin board brushes 6, 7 having contact faces 6a, 6b and 7a, 7b contacting each other along the axial direction of the commutator 1. A thick portion 8 is provided on the end face at the opposite side from the end section 6a. In the thick portion 8, a pigtail fixing hole 12 is made in the tapered face 8a at the corner of top face 8c and a pin fixing hole 13 for securing the tip of a pigtail 10 inserted into the fixing hole 12 is made in the side face 8b. Since the pigtail is fixed at the thick portion, the brush is protected against cut of crack when the pigtail is fixed. Furthermore, since levitation due to eccentricity of armature is absorbed by means of a split type brush, degradation of commutation due to production of spark can be prevented.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to brushes for DC motors.

(Prior Art) Generally, a rotor of a DC motor is composed of an armature core, an armature winding, a commutator, and the like. Among these, the commutator consists of commutator pieces with a wedge-shaped cross section and thin mica plates arranged alternately to insulate adjacent commutator pieces from each other. 1. A flow element and a mica plate are arranged in a cylindrical shape.

One end of each commutator segment is connected to the fill lead wire via a riser.

The brush that elastically contacts the commutator and supplies current is held by a brush holder so as to be movable in the radial direction of the commutator, and is pressed against the commutator surface with an appropriate pressure by the elastic force of the brush spring, thereby commutating. In order to improve the contact resistance, it is necessary to have a suitable contact resistance.

In a DC motor having a radial brush holder, the plate-shaped brush that contacts the outer periphery of the commutator in the axial direction is cut in half in the brush thickness direction, and each portion is divided by v1.
It is known that a pigtail is attached to a thin plate-like brush.

(Problem to be Solved by the Invention) However, according to the conventional split type thin plate brush of such a DC motor, as the motor becomes smaller, the thickness of the thin plate brush becomes thinner. There are problems in that the brush may be chipped when opening the pigtail attachment hole, or the brush may crack due to caulking or the like when the pigtail is attached, making it difficult to divide or thin the brush.

The present invention uses a thin plate-shaped split brush that is less likely to break or break during the machining of the pigtail mounting hole of the brush and when installing the pigtail. The purpose is to provide.

(Means for Solving the Problems) The electric motor brush of the present invention for solving the above problems includes:
A rotatable commutator, a plurality of thin plate brushes whose longitudinal end surfaces abut against the outer periphery of the commutator in the axial direction, and which are overlapped so as to be divisible in the thickness direction; a brush holder that holds stacked thin plate brushes movably in the radial direction of the commutator; The present invention is characterized in that it includes a brush spring that presses the end faces into contact with each other, and a pigtail that is connected to the end face opposite to the longitudinal end face of the thin plate brush and having a thick wall width in the plate thickness direction.

(Function) According to the electric motor brush of the present invention, a plurality of thin plate-like brushes divided in the front and rear directions in the rotation direction of the commutator,! Since the floating of the brush that occurs due to the eccentricity and unevenness of the first flow element is absorbed, the rectifying action is performed satisfactorily. In addition, since the pigtail is attached to the thick end face of the thin brush, when drilling holes in the thin brush, the pigtail mounting hole is formed on the end face that is relatively thick, so there is no possibility of brush chipping. It is less likely to crack, and the brush is less likely to be cracked or damaged when the pigtail is caulked and fixed to the pigtail mounting hole of the brush.

(Example) Embodiments of the present invention will be described below based on the drawings.

1 and 2 show a first embodiment of the electric motor brush of the present invention.

As shown in Fig. 1, the commutator 1 consists of conductive commutator pieces 2 having a wedge-shaped cross section and insulating thin mica plates arranged alternately so that adjacent commutator pieces 2 are insulated. arranged in a cylindrical shape. FIG. 1 shows the portions of the commutator pieces 2 arranged in two cylindrical shapes that come into contact with the brushes 4. In FIG.

The brush 4 in contact with the commutator l is composed of two thin plate brushes 6.
．． 7, each end face 6a.

The longitudinal direction of 7a abuts against the outer periphery of commutator l along its axial direction.

As shown in FIG. 2, the end surface 6a of the thin plate-like brush 6 has a concave shape whose longitudinal direction extends in the axial direction of the commutator and whose plate thickness direction forms a part of the arc of the commutator's outer circumference. .

On the end surface 6b opposite to the end surface 6a, a thick wall portion 8 is provided which is thick in the plate thickness direction from the middle portion to the end portion. The thick portion 8 has a tapered surface 8a at the corner of its top surface 8c, and a pigtail attachment hole 12 for inserting the pigtail 10 is opened in the tapered surface 8a. Side surface 8b of thick wall portion 8
shows pigtail 1 inserted into pigtail mounting hole 12.
A bottle attachment hole 13 for fixing the tip of the bottle is opened in the thickness direction of the plate.

As shown in FIG. 1, the bottom surface 8e of the thick portion 8 is separated from the end surface 7b of the other thin plate-like brush 7 by a distance δ shown in the figure. This is because the clearance δ absorbs the lifting caused by the vertical movement of the brush 6 or 7 caused by eccentricity of the commutator l or unevenness of the commutator surface when the armature rotates, and rectification is caused by the generation of sparks at the end face 6a or 7a. This is to prevent deterioration of the condition.

Then, a stepped portion 15 is formed on the inside of the top surface 8c that is continuous with the Taber surface 8a.
A concave brush spring sliding surface 14 is formed to be flat. The brush spring sliding surface edge 14a extending in a direction perpendicular to the commutator axial direction is connected to the other thin plate-like brush 7.
The brush is brought into contact with the brush sliding edge 20a of the brush. A brush spring 22 that urges the thin plate brush 6.7 in the radially inward direction of the commutator 1 is pressed into contact with the brush spring sliding surface 14.20.

A pigtail 1O whose one end is connected to the pigtail attachment hole 12.25 of the tapered surface 8a, 24a of the thin plate brush 617
The other end of 126 is fixed together with a flat plate 28.

The structure of the thin plate brush 7 superimposed on the thin plate brush 6 is basically the same as that of the Q plate brush 6, and these thin plate brushes 6.7 are connected to the commutator l by a brush holder (not shown). On the other hand, it is housed so as to be movable in the radial direction, is biased radially inwardly with respect to the commutator l by the brush spring 22, and the end surfaces 6a and 7a are pressed into contact with the outer peripheral surface of the commutator l with appropriate contact resistance.

According to such a configuration, the brush spring sliding surface 14.22 of the portion where the brush spring 22 comes into contact has two parts in the axial direction.
Since it is configured to be divided, the brush spring 2
2 urges the thin plate-shaped brush 6.7 in the radial inward direction, which is distributed between the two thin plate-shaped brushes 6 and 7 and acts equally, so that the force is rectified by the end surfaces 6a and 7a of the thin plate-shaped brush 6.7. The contact resistance with the child 1 becomes good. Furthermore, since the brush spring sliding surfaces 14 and 20 are divided into two parts in the axial direction, it is possible to eliminate the plate in this portion, thereby simplifying the structure.

Furthermore, the pigtail 10.26 is attached to the thin plate brush 6.
．． 7, which is thick in the thickness direction of the plate, it is possible to increase the plate thickness at the tapered surfaces 8a and 24a at the corners. Processing is easier, the brush is less likely to be damaged or chipped, and the brush is less likely to break due to caulking, etc. when attaching the pigtail.

FIG. 3 shows a brush for an electric motor according to a second embodiment of the present invention. This thin plate-shaped brush 30.32 has an end face 3
0a and 32a are in the shape of a right triangle and extend in the radial direction of the commutator in the form of a triangular prism, and the surfaces extending above and below the pillars with the hypotenuse of the right triangle as one side are overlapped with each other. A brush spring (not shown) is pressed downward in FIG. 3 on a diagonal line 34 of the top surface 30b%32b. Top surface 30b, 3
There are pigtail mounting holes 36 and 38 near the axial end of 2b.
are opened, and pigtails 10.26 are connected to these pigtail attachment holes 36.38, respectively, and the other ends of these pigtails 10.26 are fixed together with a plate 28, not shown, as shown in FIG. 1.

In the second embodiment, the thin plate brushes 30 and 32 are divided on the diagonal lines of a rectangle whose two sides are the axial direction and the circumferential direction of the commutator. In such a configuration, pigtail attachment holes 36.3 are provided on the thick side of the top surfaces 30b, 32b.
8 is open, so there is no risk of brush breakage during hole drilling or damage to the brush due to caulking during pigtail installation.

In the above-mentioned embodiment, the pigtail is attached to the brush by caulking, but the present invention is not limited to the means for attaching and fixing the pigtail. For example, the pigtail may be fixed to the brush with copper powder or the like. Of course, the present invention can be applied.

(Effects of the Invention) As explained above, according to the electric motor brush of the present invention, since the split type thin plate brush has a thick portion, the brush is not chipped when forming the pigtail attachment hole in the brush. This also avoids the occurrence of brush cracking due to caulking etc. when attaching pigtails to the brush, and also prevents brush cracking due to eccentricity or unevenness of the armature due to the plurality of thin plate brushes that are divided into front and rear in the rotation direction. This has the effect of absorbing the floating of the brush and reliably preventing deterioration in rectification due to the generation of sparks.

[Brief explanation of drawings]

Fig. 1 is a schematic perspective view showing a brush for an electric motor according to an embodiment of the present invention, Fig. 2 is a perspective view showing the brush and a pigtail, and Fig. 3 shows a brush for an electric motor according to a second embodiment of the invention. It is a schematic perspective view. 6, 7 6a, 7a 8, 24 8a, 24a 10, 26 12, 25 14.20... Commutator. ...brush, ...thin brush. ...End face (longitudinal end face), ...Thick walled part, ...Taber surface, ...Pigtail. ...Pigtail mounting hole, -Brush spring sliding surface. ...Brush spring.

Claims (1)

[Claims] (1) A rotatable commutator, and a plurality of thin plate-like brushes whose longitudinal end surfaces are in contact with the outer periphery of the commutator in the axial direction, and which are stacked so as to be divisible in the thickness direction. a brush holder that holds the stacked thin plate brushes movably in the radial direction of the commutator; and a brush holder that urges the thin plate brushes in the radial direction of the commutator to attach the thin plate brushes to the commutator. a brush spring that presses the longitudinal end face of the thin plate-like brush into contact with each other; and a pigtail that is connected to an end face opposite to the longitudinal end face of the thin plate-shaped brush and having a thick wall width in the plate thickness direction. Characteristic brushes for electric motors.