JPH071996B2 - Structure of a split mold for forming the brush housing area in the brush holder of an electric motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a split type for forming a brush accommodating area portion of a brush holder that retractably accommodates a brush slidingly contacting a commutator in an electric motor. It is a thing.

[Problems to be Solved by Prior Art and Invention] Generally, a brush of an electric motor of this kind is housed in a brush holder so that it can be retracted and retracted, and the brush is projected from the brush holder by a biasing force of an ammunition and pressed by a commutator. It is designed to come into sliding contact.

By the way, as a means for molding such a brush holder,
There is a method in which a plurality of split dies are combined and a space formed between the combined split dies is filled with a resin material and integrally molded, and many of them are actually adopted. However, in the case of resin molding by such a split split type method, the resin inevitably intrudes between the die-matching edge portions of the split split types, and this becomes a burr and appears in the product. This also applies as it is when forming the brush accommodating area formed in the brush holder.

That is, as shown in FIG. 5, the mating split mold of the portion forming the brush accommodating region is the front mating split mold 15 forming the outer surface of the front side wall 6b and the outer side surface of the rear side wall 6c opposite thereto. The rear mating split mold 16 to be formed, and the projecting mold piece 15b is projectingly formed on the front mating split mold 15 so as to form the pigtail insertion guide and the inner surface of the rear side wall. A pair of left and right protruding mold pieces 16b are formed to project from the rear side split mold 16 to form the inner side surface, and these protruding mold pieces 15b,
When the brush accommodating area S is formed by the overlapping portion of 16b, between the die matching edge portions U between the tip corner edge of one protruding die piece portion 15b and the side surface of the other protruding die piece portion 16b, the other The resin inevitably infiltrates between the tip corner edge of the protruding mold piece 16b and the side edge of the one protruding mold piece, and this resin forms a burr that protrudes into the brush accommodating area S of the brush holder 6. Will be done. As a result, there is a problem that the protruding burr interferes with the smooth operation of the brush and prevents the electric motor from being driven smoothly.

[Means for Solving the Problems] The present invention provides a structure of a split mold for forming a brush accommodating area portion in a brush holder of an electric motor, which can eliminate these drawbacks in view of the above-mentioned circumstances. The present invention was devised for the purpose of forming a brush accommodating area for accommodating a brush that is in sliding contact with a commutator with four side walls formed by front, rear, left, and right sides, and using one of the side walls. In order to integrally form a brush holder with a pigtail insertion guide extending from the brush on a certain front side wall, combining a plurality of split dies, and filling the space formed between the combined split dies with a resin material. In the structure of a split mold for molding a brush holder in the electric motor, the part of the split mold that forms the brush accommodating area is at least an outer surface for forming the outer surface of the front side wall. A front mating split mold having a side surface forming portion and a rear mating split mold having an outer surface forming portion for forming an outer surface of a rear side wall opposite to the front mating split mold. Passing through the insertion guide and the brush storage area from the outer surface forming portion so as to have left and right side surfaces for forming left and right guide end surfaces facing each other of the insertion guide, and a front end surface for forming an inner side surface of the rear side wall. And a rear side split mold for forming inner side surfaces for making surface contact with the left and right side surfaces of the protruding die piece, and for forming inner side surfaces of the left and right side walls, respectively. The left and right sides that penetrate the outer side surface and the position that is offset from the insertion wall facing position of the rear side wall so as to have the front end surface for forming the inner side surface of the front side wall and project through the brush accommodating area Form a pair of protruding mold pieces At the same time, at the tip corners of each of these protruding die pieces, a protruding portion is formed that protrudes further beyond the brush accommodating area, and the tip corner edge of each protruding die piece is on the other side. It is characterized in that the position in contact with the side surface of the one portion is retracted outside the brush accommodating area.

Further, according to the present invention, even if a burr appears on the mold matching portion, the burr does not hinder the retracting operation of the brush.

[Embodiment] Next, an embodiment of the present invention will be described with reference to the drawings. In the drawings, 1 is an electric motor, and the electric motor 1
Is a rotor 3 with a commutator 2, a magnet 5 fixed to a case 4, and a brush 7 housed in a brush holder 6 as described later.
All of them are the same as the conventional ones.

The brush holder 6 is integrally provided on a holder stay 8 that is fitted in the case 4, and has four sides surrounded by side walls 6b, 6c, 6e, 6e on the front, rear, left and right sides. Although the brush 7 has an S, and the brush 7 is housed in the housing area S so as to be retractable, the bottom portion 6a of the brush holder 6 is
The brush 7 is constantly biased by the biasing force of the ammunition machine 10 interposed between the brush 7 and the bottom surface of the brush 7 so as to project toward the axial center of the commutator 2 side. Reference numeral 11 is a pigtail planted in the brush 7, and the pigtail 11 is a brush holder 6
One side wall, which is conveniently referred to as the front side wall, is inserted into a notch-formed guide 12 in the front side wall 6b to be connected to an electrode terminal (not shown). Further, the rear side wall 6c opposed to the front side wall 6b is formed with a recessed groove-shaped engaging portion 13 with respect to the inner side surface 6f thereof.
By locking the leading edge of the brush 7 that is retracted into the brush holder 6 against the ammunition 10, the brush 7 can be locked in the retracted position in the brush holder 6 in a temporarily fixed state. I'm running. The temporarily fixed brush 7 is detached from the locking portion 13 by pulling the pigtail 11 in the direction of the arrow as shown in FIG. 3, whereby the brush 7 receives the urging force of the ammunition machine 10. So as to project toward the commutator 2 side. Further, 14 is an ammunition guide formed to project toward the inner surface 6f of the rear side wall.
The brush 7 is prevented from meandering, and is biased toward the front side wall 6b to bias the brush 7 at a position distant from the locking portion 13.

Then, the brush accommodating area S of the brush holder 6 configured in this way
Is formed by a pair of mating dies 15 and 16 that are opposed to each other in the front and rear. The structure of the part forming the brush accommodating area S of the halves 15 and 16 is as follows. I'm running.

That is, in the front split mold 15 on which the outer surface forming portion 15c for forming the outer surface 6i of the front side wall 6b is formed, the protruding die piece 15b is further formed to project from the outer surface forming portion 15c. However, the projecting mold piece portion 15b is formed with both left and right side surfaces 15d forming left and right guide end surfaces 12a of the guide 12 facing each other, and a front end surface 15e forming an inner side surface 6f of the rear side wall 6c, The protruding piece portion 15b passes through the guide 12 and the brush accommodating area S so that the front end surface 15e reaches the inner side surface 6f of the rear side wall 6c.

Further, in the rear mating mold 16 on which the outer surface forming portion 16c for forming the outer surface 6j of the rear side wall 6c is formed, a pair of left and right protruding mold pieces 16b further protrude from the outer surface forming portion 16c. Although formed, each of the protruding mold pieces 16b has an inner surface 16d that is in surface contact with the left and right outer surfaces 15d of the front protruding mold piece 15b.
And an outer surface 16e forming the inner surface 6k of the left and right side walls 6e,
A front end surface 16f forming an inner side surface 6g of the front side wall 6b is formed, and this protruding mold piece portion 16b penetrates the rear side wall 6c at a position displaced from the position of the guide 12 so as to be distorted, and The front end surface 16f passes through the brush storage area S and the front side wall 6b
It projects to reach the position of the inner surface of 6g. The rear wall
A cutout portion 6d is formed in a portion of 6c through which the protruding mold piece portion 16b penetrates.

Further, at the corners of the tip surfaces 15e and 16f of the protruding mold pieces 15b and 16b, the rear side wall 6c and the inner side surfaces 6f and 6g of the front side wall 6b are protruded further beyond the brush accommodating area S. The protrusions 15a and 16a that bite into the brush are respectively formed, and the positions X and Y at which the tip corner edges of the protruding mold pieces 15b and 16b contact the side surfaces of the protruding mold pieces 16b and 15b on the other side, respectively. Care is taken to evacuate outside the storage area S. As a result, when the brush holder 6 is resin-molded using the split molds 15 and 16, the mold matching edges of the split molds 15 and 16 are connected to the groove Z with respect to the brush accommodating area S. It is set to evacuate outside.

In the embodiment of the present invention configured as described above, the electric motor 1 is actuated by the brush 7 protruding from the brush holder 6 slidingly contacting the commutator 2 under the biasing force of the ammunition machine 10. All are the same as before, but when the brush housing area S of the brush holder 6 is resin-molded by using the front and rear pair of mating dies 15, 16, the tip surface 15e and the outer surface 15d of the protruding mold piece 15b are formed. Corner edge portions of the tip surface 16f and the inner side surface 16g of the protruding die piece portion 16b, and the side surface portions 16f, 1f of the protruding die piece portions 16b, 15b on the other side, respectively.
In the present invention, the protrusions 15a and 16a are formed on the corner edges that form the mold matching edges, and the mold matching edges are located outside the brush accommodating area S. It will be recessed into a Z-shape and be retracted. For this reason, even if the resin material penetrates into the die-matching edges and becomes a burr, it is effective that the burr only projects into the recessed groove Z that has been retracted, and even projects into the brush accommodating area S. Therefore, it is possible to prevent the operation of retracting the brush 7 from the brush holder 6 from being obstructed by the burr formed on the mold matching edge.

It should be noted that the present invention is not limited to the above-mentioned embodiment, but when the mating dies are combined to form the brush accommodating area portion of the brush holder, for example, the die matching edge is For example, as shown in FIG. 6B, when the brush is formed on the edge protruding from the brush holder 6, FIG.
As shown in FIG. 3, one of the mating dies 17 can be formed with a protrusion 17a at the tip corner edge so that the mate edge can be retracted from the brush accommodating area S to the outside. It can also be applied.

[Advantages] In summary, the present invention is configured as described above. Therefore, when the brush accommodating area of the brush holder is resin-molded by using a pair of front and rear mating dies, each of the brush accommodating areas is formed. A protruding portion is further formed on the tip corner edge of the protruding mold piece, and the matching edge of each protruding mold piece appearing in the brush accommodating area is retreated in a groove shape outside the brush accommodating area. Will be done. For this reason, when the brush holder is molded, the resin material infiltrates the mold matching edges, and even if this becomes a burr, the burr only projects into the recessed groove that is retracted from the brush accommodating area, and then it enters the brush accommodating area. It is possible to reliably prevent the brush from protruding, and therefore, it is possible to prevent the movement of the brush from the brush holder from being obstructed by burrs formed on the mold matching edge portion. The commutator is smoothly pressed and slid to ensure the drive of the electric motor.

[Brief description of drawings]

The drawings show one embodiment of the structure of a split mold for forming the brush accommodating area portion in the brush holder of the electric motor according to the present invention. FIG. 1 is a sectional view of the electric motor, and FIG.
A, B and C are front view, side view and tangential sectional view of the brush holder, FIG. 3 is an enlarged explanatory view of essential parts, and FIGS. 4A, B and C
Is a cross-sectional view of the brush accommodating region of the brush holder, a cross-sectional view showing a state in which the front-rear split mold is combined, a cross-sectional view showing a state in which the front-rear split mold is removed, and FIG. 5 is a brush accommodating region of a conventional brush holder. 6A and 6B are a radial cross-sectional view of the brush accommodating region of the brush holder of the second embodiment, and a tangential sectional view of the conventional brush holder corresponding thereto. In the figure, 1 is an electric motor, 2 is a commutator, 6 is a brush holder,
7 is a brush, 12 is a guide, 15 and 16 are split type, 15a and 16a
Is a protruding portion, 15b and 16b are protruding mold pieces, X and Y are mold matching edges,
S is a brush accommodating area.

Claims (1)

[Claims] 1. A brush accommodating area (S) for accommodating a brush (7) slidably contacting a commutator is surrounded by side walls on the front, rear, left and right sides, and is formed by one of the side walls. An insertion guide (12) for a pigtail (11) extending from the brush is formed on a certain front side wall (6b), and a brush holder (6) is formed between a plurality of mating dies by combining them. A structure of a split mold for molding a brush holder in an electric motor for filling a space with a resin material and integrally molding, wherein a part of the split mold that forms a brush accommodating area (S) is A front side split mold (15) having an outer side surface forming portion (15c) for forming an outer side surface (6i) of the front side wall (6c), and an outer side of a rear side wall (6c) opposite to this. Rear side split mold (16) having an outer side surface forming portion (16b) for forming a side surface (6j) And, wherein the front mating mold part (15), the insertion guide (12) of the opposing lateral guide edge surface (12a) left and right side surfaces to form a (15
d), and the insertion guide (12) and the brush storage area (S) from the outer side surface forming portion (15c) so as to have the front end surface (15e) for forming the inner side surface (6f) of the rear side wall (6c). A protruding mold piece (15b) is formed so as to protrude so that the rear side split mold (16) has left and right side surfaces (1) of the protruding mold piece (15b).
Inner surface (16d) for making surface contact with 5d), outer surface (16e) for forming inner surfaces (6k) of left and right side walls (6e), and further inner surface (6g) of front side wall (6b). To form a front surface (16f) for forming the outer surface forming portion (1
6c) forms a pair of left and right projecting die pieces (16b) penetrating through the rear side wall (6c) at a position displaced from the insertion guide facing position and projecting through the brush accommodating area (S). Protruding portions (15a, 16a) projecting further beyond the brush accommodating area (S) are formed at the tip corners of the protruding die pieces (15b, 16b), and the protruding die portions (15a, 16a) are formed. 15b, 16b)
The tip corner edge of the protruding type piece on the other side (16b, 15
The structure of a split mold for forming the brush accommodating area portion in the brush holder of the electric motor, characterized in that the position contacting the side surface of b) is retracted to the outside of the brush accommodating area (S).