JPH04355649A - Small motor having assembled commutator - Google Patents

Abstract

PURPOSE:To make an assembly work easy and reduce a cost by a method wherein a flange part having receptacle trenches is formed on a hollow insulating cylinder near its one side end, a cylindrical metal conductor is divided into a plurality of commutator segments having circular arc cross sections, retaining parts which can be inserted into the receptacle trenches and a terminal part pressed against the flange part are formed together in each commutator segment and the commutator segments are inserted into the receptacle trenches. CONSTITUTION:A flange part 2 is formed on a hollow insulating cylinder 1 near its one side end by one-piece molding. A plurality of receptacle trenches 3 are provider in the root part of the flange part 2 along the circumference of the cylinder 1. On the other hand, a cylindrical metal conductor is divided into a plurality of commutator segments 4 having circular arc cross sections. In each commutator segment, a plurality of retaining parts 6 which can be inserted into the receptacle trenches 3 are formed along its axial direction and a base part 5 between the retaining parts 6 is bent to a radial direction to form a terminal part 7 as an integral part of the commutator segment 4. The retaining parts 6 of the commutator segment 4 are inserted into the receptacle trenches 3 and the terminal part 7 is presses against the flange part 2. Then the protruding parts of the retaining parts 6 are bent and pressed against the outside of the flange part 2. With this constitution, positioning, assembly and manufacture can be out easily and the cost can be reduced.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a small DC motor used to drive, for example, electric tools, car mirrors, door locks, etc., and particularly relates to a small motor equipped with an assembly type commutator. be.

0002

2. Description of the Related Art FIG. 16 is a vertical cross-sectional front view of essential parts of an example of a small motor equipped with an assembly type commutator, which is the object of the present invention. In FIG. 16, 51 is a motor housing;
For example, it is formed in the shape of a hollow cylinder with a bottom, and a field magnet 52 is fixed to the inner peripheral surface. An end plate 53 is attached to the open end of the motor housing 51. 54 is a motor shaft, which includes a rotor core 55 and a commutator 5.
6 is attached and rotatably supported by bearings 57 and 58 provided on the motor housing 51 and the end plate 53.

A rotor winding 59 is formed by being wound around the rotor core 55. 60 is the terminal,
It is held by an end plate 53. 61 is a brush arm, 62 is a carbon brush, and terminal 60
The commutator 56 is electrically connected to the outer surface of the commutator 56, and is slidably contacted with the outer surface of the commutator 56.

[0004] With the above configuration, from the terminal 60,
Brush arm 61, carbon brush 62 and commutator 5
By supplying current to the rotor winding 59 through the rotor 6, the rotor 63, which is present in the magnetic field formed by the field magnet 52 fixed to the inner peripheral surface of the motor housing 51, rotates.

There are two types of commutator 56, which is a component of the small motor having the above structure: a molded type and an assembled type. The classification of the two types in use depends on the number of rotations of the motor shaft 54, the environmental temperature in which they are used, etc., but in general, it is said that the assembly type is preferable for those with a low rotational speed, and the molded type is preferable for those with heat resistance.

[0006]

[Problem to be solved by the invention] In a molded commutator, annular commutator pieces are integrally molded using thermosetting resin, and then slits are machined to form slits between the commutator pieces. It is most commonly produced by means of working. However, due to differences in thermal expansion coefficients between the metal material that makes up the commutator piece and the thermosetting resin that makes up the cylinder, or because the adhesion between the two during molding is not necessarily sufficient, the commutator Undesirable phenomena such as variations in the width of the slit and insufficient roundness of the outer circumferential surface occur after the motor is completed, resulting in a problem of deterioration of motor characteristics. Another problem is that burrs are generated in the slits between the commutators due to the slitting process, which lengthens the manufacturing process by requiring secondary processing to remove burrs, resulting in higher processing costs.

On the other hand, assembling type commutators do not have the problems that exist in the molded type commutators, because they are mechanically assembled from component parts that have been manufactured separately in advance.
There are problems in strength as well as the following. 17 and 18 are a partially longitudinal sectional front view and a side view, respectively, showing an example of a conventional prefabricated commutator, and the same parts are designated by the same reference numerals as in FIG. 16. In FIGS. 17 and 18, 56a is a commutator piece, which is made of a conductive material such as copper and has an arcuate cross-sectional shape, and a cylindrical body 64 that is made of an insulating material and has a cylindrical shape. For example, three pieces are connected via a ring 65 made of an insulating material.
Fixed at equal intervals in the cylindrical direction. Reference numeral 56b denotes a terminal portion for connecting the terminal lead wire of the rotor winding 59 shown in FIG. 16. 66 is a slit, and the commutator piece 56a
, 56a.

The assembly type commutator 56 having the above structure has a cylindrical body 6
4. Since the commutator piece 56a and the ring 65 are manufactured separately in advance, there is an advantage that dimensional accuracy can be increased, but there is a problem that the fixing strength of the commutator piece 56a is not necessarily sufficient. That is, commutator piece 56
Since the fixation of part a to the outer circumferential surface of the cylinder 64 depends only on the crimping by the ring 65, there is a limit to the fixing strength due to clamping or crimping, and vibrations and other external forces may cause
There is a risk that the commutator piece 56a may be misaligned and the width of the slit 66 in the circumferential direction may become uneven.

Furthermore, since the ring 65 is required during assembly, it is not only disadvantageous in terms of cost, but also the presence of the ring 65 limits the effective length of the commutator piece 56a in the axial direction. It is also necessary to increase the axial length of the commutator 56, which also has the problem of hindering miniaturization of the entire small motor.

On the other hand, in recent years, the requirements for this type of small motor have become more and more severe, and there is a growing demand not only for smaller size and higher performance, but also for further cost reduction. There is a problem that the above request cannot be met with a system that has children.

[0011]

[Means for Solving the Problems] The present invention solves the problems existing in the above-mentioned prior art, and provides high adhesion strength of commutator pieces, easy assembly work, and low cost. The object of the present invention is to provide a small motor with a certain prefabricated commutator.

[0012] In order to achieve the above object, the first invention includes a cylinder made of an insulating material, and a plurality of cylinders fixed to the outer peripheral surface of the cylinder and made of a conductive material and having an arcuate cross section. In a small motor equipped with a prefabricated commutator consisting of commutator pieces, a flange portion formed with an external dimension larger than the external dimension of the cylindrical body is provided near one end of the cylindrical body, and is integrated with the cylindrical body. A receiving groove is provided in the flange portion at the boundary with the cylindrical body, and the receiving groove is formed in an arcuate cross-sectional shape and passes through the receiving groove in the axial direction. A locking portion is provided to penetrate into the receiving groove of the flange portion, and the tip of the locking portion is cut in the axial direction, and at least one of the cut pieces is plastically deformed in the circumferential direction of the cylinder, thereby locking. A technical measure was adopted in which the commutator was constructed by fixing the part to the flange part.

Next, in the second invention, in the above-mentioned technical means, a protrusion is provided on the outer inner circumferential surface of the receiving groove to have a width smaller than the circumferential width of the receiving groove. A technical measure has been added in which the locking part is configured to be pressed in the axial direction and brought into close contact with the inner peripheral surface of the receiving groove.

[0014]

[Operation] With the above configuration, in the first invention, the locking portion formed at one end of the commutator piece penetrates into the receiving groove of the flange portion, and at least one of the cut pieces at the tip thereof Since one side is fixed to the flange portion by so-called caulking or crushing, the commutator pieces are positioned and fixed, and a small motor equipped with an assembly type commutator having a predetermined performance can be obtained.

Next, in the second invention, in addition to the above-mentioned effects, the projection provided in the receiving groove of the flange portion provides
The locking portion is pressed in the axial direction of the cylindrical body and comes into close contact with the cylindrical body, and has an action capable of resisting vibrations and external forces.

[0016]

[Embodiment] FIGS. 1 and 2 are a vertical sectional front view and a left end view of essential parts showing a commutator in an embodiment of the present invention, respectively, and FIG.
is a cross-sectional developed view taken along the line A-A in FIG. 1. In these figures, 1 is a cylindrical body, which is formed into a hollow cylindrical shape from thermosetting resin such as epoxy resin, and has an outer diameter or outer diameter larger than the outer diameter of the cylindrical body 1 near one end. A flange portion 2 formed to a dimension is provided integrally with the cylinder body 1.

Next, reference numeral 3 denotes a receiving groove, which is formed to have an arcuate cross section, and is provided so as to pass through the flange portion 2 at the boundary with the cylindrical body 1 and parallel to the axis. 4 is a commutator piece, which is made of a conductive material such as copper, and
As will be described later, the base portion 5, the locking portion 6, and the terminal portion 7 are each provided integrally.

FIGS. 4 and 5 are perspective views showing the cylinder 1 and commutator piece 4 in FIGS. 1 and 2, respectively, and the same parts are designated by the same reference numerals as in FIGS. 1 and 2. First, in FIG. 4, reference numeral 8 indicates concave grooves, which are arranged radially on the end face of the flange portion 2 and at equal intervals in the circumferential direction, and are used for positioning commutator pieces 4, which will be described later.

Next, in FIG. 5, the base portion 5 of the commutator piece 4
is formed to have an arcuate cross section corresponding to the outer circumferential surface of the cylinder 1 shown in FIG. 4. A locking portion 6 and a terminal portion 7 are provided at one end of the commutator piece 4. Two locking portions 6 are provided along the edge of the commutator piece 4, and the terminal portion 7 is provided at one end of the commutator piece 4. It is formed to protrude outward from the intermediate portion of the stop portion 6 along the end surface of the flange portion 2 shown in FIG.

[0020] Next, the assembly of the commutator using the above configuration will be described. First, as shown in FIGS. 1 to 3, the commutator piece 4 is arranged on the outer periphery of the cylindrical body 1, the locking part 6 is inserted into the receiving groove 3 provided in the flange part 2, and the terminal part 7 is engaged in a groove 8 (not shown, see FIG. 4) provided on the end surface of the flange portion 2 to perform positioning in the circumferential direction and the axial direction.

FIG. 6 is a perspective view showing a state in which the commutator pieces 4 are arranged and positioned on the outer circumferential surface of the cylindrical body 1. As shown in FIG. 6, the locking portion 6 passes through the receiving groove 3 in the flange portion 2 and protrudes from the opposite end surface of the flange portion 2. Next, between the protruding locking parts 6, 6, a cutting blade 9 as shown in FIG. The commutator piece 4 is fixed to the cylindrical body 1 by plastically deforming the cut piece 6b in the circumferential direction and press-fitting it to the flange portion 2. In this case, it is preferable to grip or hold the outer periphery of the base portion 5 of the commutator piece 4 using, for example, a collet chuck.

FIGS. 7 and 8 are partially sectional exploded views showing modified examples of the receiving groove 3 and the locking portion 6 in the embodiment of the present invention, and correspond to FIG. 3 described above. First, in FIG. 7, the axial length of the flange portion 2 is formed to be slightly larger than the axial length of the locking portion 6. By forming it in this way, the tip of the locking part 6 does not protrude from the flange part 2, thereby preventing undesired contact with the rotor winding (not shown, see reference numeral 59 in FIG. 11). It can be prevented.

Next, the one shown in FIG. 8 is one in which the number of locking portions 6 to be provided on the commutator piece 4 is one. In addition, in FIG. 8, the cut pieces 6b, 6b are plastically deformed from the cut 6a to both sides. Forming in this way is effective for ensuring the width dimension of the locking portion 6 and obtaining a predetermined fixing strength, especially when a multipolar commutator, for example, seven or more commutator pieces 4 are required. .

FIGS. 9 and 10 are enlarged perspective views of essential parts showing modified examples of the terminal portion 7, respectively. 9 and 10, numerals 10 and 11 each represent a protrusion, which is integrally provided at the tip of the terminal portion 7. In FIG. These protrusions 10 and 11 are for connection to the terminal lead wire of the rotor winding or for attachment of other components such as a varistor.

FIGS. 11 and 12 are a vertical sectional front view and a left end view of essential parts of a commutator according to another embodiment of the present invention, and the same parts are designated by the same reference numerals as in FIGS. 1 and 2, respectively. show. 11 and 12, reference numeral 10 denotes a protrusion, which is formed on the outer inner circumferential surface of the receiving groove 3 and has a width smaller than the width of the receiving groove 3 in the circumferential direction.

With the above configuration, if the commutator piece 4 is arranged on the outer periphery of the cylindrical body 1 and the locking portion 6 is press-fitted into the receiving groove 3 provided in the flange portion 2, the locking portion 6 will be It is pressed in the axial direction by the protrusion 10 and is tightly attached and fixed to the inner circumferential surface of the receiving groove 3 . Note that the cutting of the tip of the locking portion 6 and the manner of plastic deformation in the circumferential direction are similar to those shown in FIGS. 3, 7, and 8.

FIG. 13 is a longitudinal cross-sectional front view of essential parts showing a modification of the flange portion 2 and the protrusion 10. As shown in FIG. In Figure 13,
2a is a recessed portion provided on the left end surface of the flange portion 2. Next, the projection 10 is formed so that its axial length is smaller than the axial length of the receiving groove 3. In addition, the tip of the locking part 6 is
It is formed so as not to protrude from the end face of the flange portion 2.

[0028] With the above structure, it is possible to prevent an undesired situation caused by the tip of the locking part 6 protruding from the flange part 2, as in the case shown in FIGS. 7 and 8. 14 and 15 are longitudinal cross-sectional front views of essential parts showing commutators in still other embodiments of the present invention, in which the base portions 5 of the commutator pieces 4 are slightly tapered. Note that the same parts are indicated by the same reference numerals as in the previous embodiment. First, in Fig. 14, 11 is a protrusion,
It is provided on the inner peripheral surface of the receiving groove 3 provided in the flange portion 2 and closer to the left end surface of the flange portion 2 than the protrusion 10 . Next, Figure 15
The outer peripheral surface of the cylindrical body 1 and the inner peripheral surface of the receiving groove 3 corresponding to the base portion 5 and the locking portion 6 of the commutator piece 4 are provided with a taper having an angle θ with respect to the axis.

With the above configuration, the base portion 5 of the commutator piece 4
And/or a larger pressing force is applied to the locking part 6 in the axial direction by the protrusion 10 provided in the receiving groove 3 of the flange part 2, and the commutator piece 4 is brought into close contact with the cylinder body 1. degree can be ensured. The manner of machining of the tip of the locking portion 6 is the same as in the previous embodiment.

In the above embodiment, an example was described in which the cylindrical body and the flange portion were made of thermosetting resin, but they may also be made of thermoplastic resin, and known molding methods such as injection molding may be used. Molding means can be used. Further, the shape and dimensions of the receiving groove to be provided in the flange portion can be appropriately selected depending on the relationship with the locking portion to be provided in the commutator piece.

[0031]

[Effects of the Invention] Since the present invention has the structure and operation as described above, it can achieve the following effects. (1) Since the adhesion strength of the commutator piece to the cylinder is high,
Even when vibrations due to motor rotation or other external forces are applied, problems such as misalignment of the commutator pieces or uneven width of the slits do not occur, making it possible to create a small motor with high performance and high reliability. can. (2) Since there is no need for a ring to secure the commutator pieces, the number of component parts is small and assembly work is easy.
Manufacturing man-hours and costs can be reduced. (3) Since no fixing ring is required, not only is there no restriction on the axial length of the commutator piece, but it is also possible to downsize the small motor as a whole.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional front view of a main part of a commutator in an embodiment of the present invention.

FIG. 2 is a left end view showing a commutator in an embodiment of the present invention.

FIG. 3 is a cross-sectional developed view taken along line A-A in FIG. 1;

FIG. 4 is a perspective view showing the cylindrical body in FIGS. 1 and 2. FIG.

FIG. 5 is a perspective view showing the commutator piece in FIGS. 1 and 2. FIG.

FIG. 6 is a perspective view showing a state in which commutator pieces are arranged and positioned on the outer peripheral surface of a cylindrical body.

FIG. 7 is a partially sectional exploded view showing a modified example of the receiving groove and the locking portion in the embodiment of the present invention.

FIG. 8 is a partially sectional exploded view showing another modification of the receiving groove and the locking portion in the embodiment of the present invention.

FIG. 9 is an enlarged perspective view of a main part showing a modified example of the terminal portion.

FIG. 10 is an enlarged perspective view of a main part showing a modified example of the terminal portion.

FIG. 11 is a vertical cross-sectional front view of a main part of a commutator in another embodiment of the present invention.

FIG. 12 is an end view showing a commutator in another embodiment of the invention.

FIG. 13 is a vertical cross-sectional front view of a main part showing a modified example of a flange portion and a protrusion.

FIG. 14 is a vertical cross-sectional front view of a main part showing a commutator piece in still another embodiment of the present invention.

FIG. 15 is a longitudinal cross-sectional front view of a main part showing a commutator piece in still another embodiment of the present invention.

FIG. 16 is a vertical cross-sectional front view of a main part of an example of a small motor equipped with an assembly type commutator, which is a subject of the present invention.

FIG. 17 is a partially longitudinal cross-sectional front view showing an example of a conventional prefabricated commutator.

FIG. 18 is a side view showing an example of a conventional prefabricated commutator.

[Explanation of symbols]

1 Cylindrical body 2 Flange part 3 Receiving groove 4 Commutator piece 6 Locking part 7 Terminal section 10 Protrusion

Claims (2)

[Claims] [Claim 1] A prefabricated commutator comprising a cylindrical body made of an insulating material and a plurality of commutator pieces fixed to the outer peripheral surface of the cylindrical body and made of a conductive material and having an arcuate cross section. In a small motor, a flange portion having an external dimension larger than the external dimension of the cylindrical body is provided near one end of the cylindrical body integrally with the cylindrical body, and a cross section of a circular cross section is provided within the flange portion at the boundary with the cylindrical body. A receiving groove formed in an arc shape and penetrating in the axial direction is provided, a locking portion passing through the receiving groove is provided at one end of the commutator piece, and this locking portion is inserted into the receiving groove of the flange portion. The commutator has a configuration in which the tip of the locking part is cut in the axial direction, and at least one of the cut pieces is plastically deformed in the circumferential direction of the cylinder, thereby fixing the locking part to the flange part. A small motor equipped with a prefabricated commutator. [Claim 2] A protrusion formed on the outer inner circumferential surface of the receiving groove with a width smaller than the circumferential width of the receiving groove is provided to press the locking part in the axial direction within the receiving groove and Claim 1 characterized in that it is configured to be brought into close contact with the inner peripheral surface of the
A small motor with a prefabricated commutator as described.