JPH05103447A - Brush and commutator motor - Google Patents

Abstract

PURPOSE:To lessen the resistance loss of a brush, and improve the life together with an armature, and improve the operation efficiency, concerning the a commutator motor which is equipped with the brush being used for a generator, a commutator motor, etc., and sliding on the commutator and a brush device using this brush, and is adopted for the electrically-driven part of the electric blower or the like of, for example, an electric cleaner. CONSTITUTION:A brush 41 comprises a brush main part 42, which is molded with carbon as chief ingredients, and conductors 43, which are made of conductive material such as copper wires, etc., smaller in electric resistance than the main part 42 of the brush and are buried over the approximately overall length being dispersed inside the main part 42 of the brush. And this brush 41 is used for commutator motor adopted for the electrically-driven part of an electric blower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with a brush used in a generator, a commutator motor, etc., which comes into sliding contact with a commutator, and a brush device using the brush, for example, an electric blower for an electric vacuum cleaner. The present invention relates to a commutator motor used in the electric section of

[0002]

2. Description of the Related Art Conventionally, brushes used in commutator motors and the like are roughly classified into carbon type brushes and noble metal type brushes, and carbon type brushes are generally used. The carbon-based brush is formed by compressing and solidifying carbon as a main component using a binder and baking it at a high temperature, and a synthetic resin is usually used as the binder. A conventional brush used in, for example, an electric blower of an electric vacuum cleaner is formed of a single type of carbon as a main component. Moreover, in order to reduce the generation of sparks due to the sliding contact between the brush and the commutator, it is necessary to increase the resistance rectification. Therefore, carbon, which is the main component of the conventional brush, generally has a resistivity Carbon having a high resistance value of 30,000 μΩ or more was adopted. Therefore, when a plurality of commutator pieces of the commutator come into contact with the tip surface of the brush, the current value for short-circuiting the commutator pieces through the brush is reduced, and the occurrence of sparks can be reduced.

[0003]

However, as described above, in the conventional brush configuration in which the total electric resistance of the brush is large (about 0.2 Ω), the resistance loss in the brush is large (about 20 W per brush). Therefore, there is a problem that the operating efficiency of a commutator motor or the like using this brush is reduced.

At the same time, the loss is converted into heat generated by the brush. Therefore, for example, in a resin-bound type brush using a synthetic resin as a carbon binder, thermal deterioration of the resin is likely to occur and the commutator There is a high possibility that the synthetic resin portion that insulates the commutator pieces from each other is thermally deteriorated. In particular, commutator motors used in electric blowers for vacuum cleaners tend to be smaller and have higher input, and the current density of the brushes accordingly increases. Therefore, when the brush has a high resistance, the heat generated by the brush is likely to be extremely large, and the life of the brush and the commutator is shortened. By the way, it has been known that the conventional resin-binding type brush has a drastic decrease in transverse rupture force when the temperature thereof exceeds 200 ° C. By the way, in order to extend the life of the brush and commutator, make them larger and reduce the current density,
And it is possible if the heat radiation from the surface is improved. However, doing so causes a problem that the axial length of the commutator motor becomes large.

An object of the present invention is to obtain a brush which can reduce the resistance loss and improve the life of the commutator together with the brush. Another object of the present invention is to obtain a commutator motor capable of improving the operation efficiency and reducing the axial length.

[0006]

According to a first aspect of the present invention, there is provided a brush in which substantially the entire length of a portion that is worn by contacting a commutator is made of two or more kinds of conductive materials having different resistivities. The brush main portion formed of a conductive material having a high resistivity, and a conductor formed of another conductive material having a lower resistivity than the conductive material of the brush main portion, and the conductor inside the brush main portion. A plurality of these are dispersed and embedded along the longitudinal direction of the brush main part.

According to the invention of claim 2, a stator and this stator are provided.
Motor case with built-in rotor, rotor shaft and this
With a commutator fixed to the inside of the stator.
And is rotatably supported by the motor case.
And a brush that makes sliding contact with the commutator.
And a brush device attached to the electric motor case.
In the commutator motor, the brush is the commutator.
About the entire length of the part that wears by contacting the
Formed of the conductive material above, of the conductive material
The brush main part made of a conductive material with the highest resistivity, and
Of other conductive material whose resistivity is lower than the conductive material of the brush main part of
It consists of a formed conductor and is placed inside the main part of the brush.
Multiple conductors are dispersed and embedded along the longitudinal direction of the brush main part.
It was set up.

[0008]

According to the brush of the first aspect of the invention, the brush main portion is formed of the conductive material having the highest resistivity among the two or more types of conductive materials having different resistivity forming the brush. Since a conductor is formed of another conductive material having a resistivity lower than that of the conductive material, and a plurality of the conductors are dispersed inside the brush main portion and embedded along the longitudinal direction of the brush main portion, The electric resistance can be reduced, the loss of current in the brush can be reduced, and the heat generation of the brush can be reduced. Moreover, since a plurality of conductors are embedded in the brush main portion in a dispersed manner, the heat dissipation characteristics of the brush can be improved.

According to the commutator motor of the invention of claim 2,
Since the brush according to claim 1 is used, the loss of current in the brush can be reduced and the heat generation of the brush can be reduced, so that the operation efficiency can be improved and the axial length of the commutator can be reduced, and accordingly the commutator can be reduced. The axial length of the electric motor can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the first embodiment of the present invention is shown in FIGS.
It will be explained based on. In FIG. 3, reference numeral 1 denotes a metal electric motor case, which is composed of a case body 2 and a case end face plate 3.

The case body 2 is formed of a cylindrical portion 4 having a bottomed cylindrical shape, and the side of the cylindrical portion 4 opposite to the bottom portion 4a is opened.
The mounting portion 5 is formed integrally with the peripheral portion of this opening. The mounting portion 5 includes an annular flat surface portion 6, a tubular portion 7, and a projecting edge 8.
It is formed by and. The annular flat portion 6 is formed integrally with the opening edge of the case main body 2 so as to project outwardly toward the outer side of the main body 2, and the tubular portion 7 is bent from the outer periphery of the annular flat portion 6 toward the bottom portion 4a side. Is formed parallel to 2,
In addition, the projecting edge 8 is formed by bending at a right angle from the tip of the tubular portion 7 toward the outside. An exhaust hole 9 is provided in the side wall of the cylindrical portion 4 on the bottom 4a side, and an exhaust hole (not shown) is also provided in the bottom 4a. A bearing mounting portion 11 accommodating the bearing 10 is formed at the center of the bottom portion 4a of the cylindrical portion 4.

The case end face plate 3 has, for example, a substantially band plate shape whose planar shape extends in the radial direction so as to traverse the opening of the case main body 2 in the radial direction, and a bearing mounting in which a bearing 12 is housed in the central portion thereof. The part 13 is formed integrally. Both ends of the case end face plate 3 are screwed to the annular flat surface portion 6. For this reason, the opening of the case body 2 is partially covered with the opening portion without being completely closed.

A stator 14 and a rotor 16 with a commutator 15 arranged inside the stator 14 are housed in the case body 2. The stator core of the stator 14 has a substantially quadrangular outer shape when viewed from the axial direction, and the four chamfered corners thereof are fixed to the case body 2 in close contact with the inner surface of the cylindrical portion 4. By this fixing, air passages 19 are formed between the inner surface of the cylindrical portion 4 and the outer surface of the stator core. Rotor 16
The rotor shaft 17 is rotatably supported by the bearings 10 and 12, and one end of the rotor shaft 17 penetrates the bearing 12 and the bearing mounting portion 13.

The commutator 15 is located on the bearing 10 side and is fixed to the rotor shaft 17. The commutator 15 includes a boss portion 15a made of synthetic resin that rotates integrally with the rotor shaft 17, and a large number of commutator pieces 15b provided on the outer periphery of the boss portion 15a at intervals in the circumferential direction. ing. Commutator piece 15
The ends of the rotor windings are electrically connected to these commutator pieces 15b.

A pair of brush devices 18 are attached to the cylindrical portion 4 of the case body 2 with a commutator 15 interposed therebetween. The details of these brush devices 18 will be described below with reference to FIGS. 1 and 2.
Will be described.

A brush holder 21 provided in the brush device 18.
Is made of an electrically insulating material such as synthetic resin, and the main body 22 has an insertion hole 23 and has a substantially rectangular tube shape.
The main body 22 includes a support piece 24 that overlaps the outer surface of the case main body 2.
Are projected integrally. As shown in FIG. 3, in the brush holder 21, the main body portion 22 is inserted into the mounting opening 4b opening in the cylindrical portion 4 of the case main body 2, and the support piece 24 is fixed to the cylindrical portion 4 by the screw 26, so that the case main body 2 Fixed to.

A metal brush guide 27 is fitted and fixed in the insertion hole 23 of the brush holder 21. One end of the brush guide 27 extends from the main body 22 to the commutator 1
It projects toward 5. At the other end of this guide 27, a retaining piece 28 that is hooked at the opening edge of the insertion hole 23 is bent, and at the base of the brush guide 27 protruding from the main body 22, the end surface of this main body 22 is formed. A cut-and-raised piece 25 that is caught on is formed. The main body 22 is sandwiched by the cut-and-raised pieces 25 and the retaining pieces 28, and the brush guide 27 is fixed to the brush holder 21.

A terminal mounting hole 29 is formed in the main body portion 22 of the brush holder 21. This terminal mounting hole 29
Is provided substantially parallel to the insertion hole 23, and a terminal fitting 30 for supplying current is attached to the inside thereof. The terminal fitting 30 is made of sheet metal and integrally includes a cap piece 31 that covers the open end of the insertion hole 23 and a retaining piece 32 that is inserted into the terminal mounting hole 29. Retaining piece 3
2 has a convex portion 33 curved in an arcuate cross section, and an elastically deformable bending portion 34 which is bent into a mountain shape continuously from the convex portion 33. The top of the portion 34 is pressed against the inner surface of the terminal mounting hole 29. The tip of the bent portion 34 projects from the terminal mounting hole 29 toward the inside of the case body 2, and the projecting portion 34a
A locking piece 35 that is hooked on the end surface of the main body 22 is integrally cut and raised. The locking piece 35 prevents the terminal fitting 30 from coming off from the terminal mounting hole 29.
The protruding portion 34a is inserted into a connection terminal (not shown) of a terminal block 36 attached to the stator core of the stator 14, and is connected to the stator winding via this terminal.

Inside the brush guide 27, a rod-shaped brush 41 having a rectangular cross section as a whole is housed so as to be movable in the axial direction. A portion of the brush 41 that is worn by contacting at least the commutator 15 (a portion having an effective use length A)
Is a rod-shaped brush main portion 42, and a plurality of the brush main portions 42 are dispersed in the brush main portion 42 in the longitudinal direction (brush 4
1 and the conductor 43 embedded along the direction in which the main current flows. The brush main portion 42 is formed of a conductive material having the highest resistivity, and specifically, a conductive material containing carbon as a main component is compression-molded together with a binder made of synthetic resin and sintered. It is formed by A hole 44 into which one end of the pigtail 45 is inserted is formed at the center of one end of the brush main part 42.
The conductor 43 is formed of a conductive material having a resistivity lower than that of the conductive material forming the brush main portion 42, for example, a copper wire or copper powder formed into a linear shape. Are embedded in the brush main part 42 in a distributed manner along the longitudinal direction thereof (about 10 to 15).

Then, the brush 41 is made as follows. First, a thin layer of carbon particles containing a binder made of a synthetic resin is laid thinly, and a plurality of (three or four) linearly formed copper wires or copper powder are arranged at a distance from each other.
In addition, it is formed by repeatedly laying a thin layer of carbon particles containing a binder made of synthetic resin on it several times, compressing it into a square pole shape, and then sintering this. ing. That is, the brush main portion 42 and the conductor 43 that form the brush 41 are simultaneously molded. In the embodiment, the conductor 43 is made of copper wire or copper powder and formed into a linear shape, but a thin plate may be used. Alternatively, the copper powder may be used as it is as particles and arranged linearly in a thin shape and simultaneously molded at the time of compression.

In the brush 41, the end edge of the conductor 43 embedded in the brush main portion 42 on the commutator 15 side is exposed from the tip surface 42a of the brush main portion 42 at the initial stage of use of the brush 41. OK, or this tip surface 4
It may be covered with 2a. In the brush 41, the length of the linear or thin plate conductor 43 may be long or short, and it does not matter. In short, it suffices that the brush main portion 42 is embedded over the entire wear portion (the portion having the effective use length A).

One end of a pigtail 45 is connected to the brush 41. That is, one end of the pigtail 45 is inserted into the hole 44, and is fixed by the copper powder packed around the hole 44. The other end of the pigtail 45 is spot-welded to the cap piece 31 that covers the opening end of the insertion hole 23. A compression coil spring 46 is interposed between the other end surface of the brush 41 and the cap piece 31 that covers the opening end of the insertion hole 23. The compression coil spring 46 causes the brush 41 to always face the commutator 15. Being pressed. Due to this pressing, the end of the brush 41 on the commutator 15 side projects from the brush guide 27 and is slidably pressed against the outer peripheral surface of the commutator 15. The motor case 1, the bearings 10, 12, the stator 14, the rotor 16, and the brush device 18 described above form a commutator motor.

As shown in FIG. 3, a centrifugal fan 52 that rotates integrally with the rotor shaft 17 is attached to an end portion of the rotor shaft 17 that protrudes from the electric motor case 1 via a nut 51. The fan 52 has a suction port 53 formed in the central portion and a discharge port 54 formed in the peripheral portion. The centrifugal fan 52 is covered with a fan cover 55. The cover 55 is fitted and attached to the attachment portion 5 of the main body case 2, and the fan cover 55 is attached.
An opening 56 for sucking air is formed in the central portion of the so as to face the suction port 53 of the fan 52.

Therefore, when the centrifugal fan 52 rotates, air is sucked through the opening 56, and the sucked air passes through the suction port 53 of the centrifugal fan 52 and is discharged from the discharge port 54. A rectifying plate 57 that guides the air discharged from the centrifugal fan 52 into the electric motor case 1 is provided between the centrifugal fan 52 and the mounting portion 5. The rectifying plate 57 rectifies the air discharged from the centrifugal fan 52 and converts the pressure of the air from dynamic pressure to static pressure in the rectifying process, and is screwed to the case end face plate 3. The air rectified by the rectifying plate 57 flows into the motor case 1, passes through the air passage 19 and is discharged from the exhaust port 9 to the outside of the motor case 1.

In the electric blower having the above structure, the current flowing through the brush 41 during operation thereof mainly flows through the conductor 43. As described above, since the brush 41 has the structure in which the conductor 43 having a smaller electric resistance than the brush main portion 42 is embedded over substantially the entire length of the brush main portion 42, the total electric resistance of the brush 41 can be reduced. By the way, the total electric resistance of the brush 41 in this embodiment was about 0.05Ω, which was about ¼ of the conventional value. Therefore, the resistance loss of the current in the brush 41 can be reduced, and the operating efficiency of the commutator motor for the electric blower can be improved accordingly.

Further, since the total electric resistance of the brush 41 can be reduced as described above, the heat generation of the brush 41 can be reduced. In addition, the occurrence of sparks between the brush 41 and the commutator 15 can be reduced for the following reasons. First, since the cross-sectional area of the conductor 43 at the contact surface with the commutator 15 is smaller than the cross-sectional area of the brush main portion 42, the rectification resistance is lower than that when the entire brush 41 is made of a low-resistance electric conductor. Since there is no significant decrease in the current, the short-circuit current during rectification can be reduced. Secondly, as described above, since the electric resistance of the entire brush 41 is small, it is possible to use a material having good seatability for the brush main portion 42, for example, a resin binding type conductive material.
Thereby, the elastic coefficient of the entire brush 41 can be lowered. As described above, since the brush 41 itself generates less heat and is less heated by sparks, the temperatures of the brush 41 and the commutator 15 can be suppressed low.

Further, since the conductor 43 of the brush 41 is embedded inside the brush main portion 42, the reliability of holding the conductor 43 on the brush main portion 42 is improved, and sliding contact with the commutator 15 is achieved. Irrespective of the external force or the like acting with
Can be prevented from coming off from the brush main portion 42.

Further, since the conductor 43 is directly embedded in the brush main portion 42, abrasion powder generated when the brush main portion 42 and the conductor 43 both come into sliding contact with the commutator 15 due to the abrasion of the brush 41. Does not contain a substance that hinders the flow of current between the brush 41 and the commutator piece 15b. By the way, in the structure in which the conductor 43 is adhered to the brush main portion 42 using an adhesive, electric resistance is newly generated due to abrasion powder of the adhesive, but such a problem does not occur in the brush 41 having the above structure.

Further, the brush main portion 4 which constitutes the brush 41
2 and the conductor 43 are molded at the same time, and after the brush main part is molded in advance, copper powder is filled in the holes of this brush main part to form an electric conductor to form a brush. The manufacturing process can be simplified. Moreover, conductor 4
Since a plurality of 3 are embedded in a dispersed manner, the heat dissipation characteristics of the brush 41 can be improved, and since the conductor 43 is formed thin as one, the conductor 43 is
Even if is formed of copper powder, it does not fall off in the middle.

Therefore, according to the present invention, the thermal deterioration of the brush 41 and the commutator 15 can be prevented, so that the service life of the brush 41 and the commutator motor can be improved and the service life of the commutator motor can be improved. It is suitable. Moreover, as described above, the temperature rises of the brush 41 and the commutator 15 are small, and the heat dissipation characteristics of the brush 41 can be improved.
1 can be made small and the axial length of the commutator 15 can be made small. Therefore, the length of the rotor shaft 17 can be shortened, and accordingly, the entire electric blower can be downsized in the axial direction.

[0031]

According to the brush of the first aspect of the invention, since the total electric resistance of the brush is small, the operation efficiency of a commutator motor or the like using this brush can be improved, and in addition, the heat generated by the current is small and the commutation is performed. Since the occurrence of sparks with the child can be reduced, the temperature rise of the brush can be suppressed, and the life of the brush itself and the commutator motor or the like using the brush can be improved. Moreover, since a plurality of conductors are dispersed and embedded, the heat dissipation characteristics of the brush can be improved.

According to the commutator motor of the invention of claim 2,
Since the resistance loss of the current in the brush can be reduced, the operating efficiency can be improved, and since the temperature rise of the brush and the commutator can be reduced, the axial length of the commutator can be reduced,
Accordingly, a commutator motor having a small axial length can be provided.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a brush device including a brush according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line ZZ of FIG. 1 according to the embodiment of the present invention.

FIG. 3 is a vertical cross-sectional side view of the electric blower according to the embodiment of the present invention.

[Explanation of symbols]

 1 Motor Case 14 Stator 15 Commutator 16 Rotor 18 Brush Device 41 Brush 42 Brush Main Part (Conductive Material with Highest Resistivity) 43 Conductor (Conductive Material with Low Resistivity)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuya Ikegami 43 Horiyamashita, Hadano City, Kanagawa Prefecture Tokyo Electric Co., Ltd. Hadano Factory

Claims (2)

[Claims] 1. A brush formed by using a conductive material having the highest resistivity among the conductive materials in a brush in which substantially the entire length of a portion that is worn in contact with a commutator is formed of two or more conductive materials having different resistivities. A main part and a conductor formed of another conductive material having a resistivity lower than that of the conductive material of the brush main part, and a plurality of the conductors are dispersed inside the brush main part so that the longitudinal direction of the brush main part. A brush characterized by being buried along. 2. A stator, an electric motor case having the stator built therein, a rotor shaft and a commutator fixed to the rotor shaft, which are arranged inside the stator and are rotatably supported by the electric motor case. And a brush device attached to the electric motor case, the brush device having a brush that makes sliding contact with the commutator, and the brush resists substantially the entire length of a portion that is worn by being in contact with the commutator. A brush main part formed of a conductive material having the highest resistivity among the conductive materials, and having a resistivity higher than that of the conductive material of the brush main part. A commutator motor, comprising a conductor formed of another low conductive material, wherein a plurality of the conductors are dispersed inside the brush main portion and embedded along the longitudinal direction of the brush main portion.