JP2855004B2 - Carbon brush - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon brush used in a generator, a commutator motor, or the like, and in sliding contact with a commutator.

[0002]

2. Description of the Related Art Carbon brushes used in commutator motors and the like are made of carbon as a main component, compressed and solidified using a binder, and baked at a high temperature. It is configured by connecting pigtails consisting of Synthetic resin is usually employed as the binder, and the pigtail is embedded and fixed in a fixing hole provided at an end of the main part of the brush opposite to the end which is in sliding contact with the commutator. And the brush main part of the conventional carbon brush used for the electric blower of a vacuum cleaner is formed with a single type of carbon as a main component. In addition, since it is necessary to increase resistance rectification in order to reduce the occurrence of sparks due to the sliding contact between the main part of the brush and the commutator, carbon, which is a main component of the conventional carbon brush, is generally used. 1
Carbon having a high resistance value of 30,000 μΩ or more per square cm has been employed. Thus, when a plurality of commutator pieces of the commutator come into contact with the tip end surface of the carbon brush, the current value for short-circuiting between the commutator pieces through the carbon brush is reduced, and the occurrence of sparks can be reduced.

[0003]

However, as described above, in the structure of the conventional carbon brush in which the total electric resistance of the brush main part is large (about 0.2Ω), the resistance loss in the brush main part is large (carbon brush). From about 20W per piece)
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 main portion of the brush. For example, in a resin-bound type carbon brush using a synthetic resin as a carbon binder, thermal deterioration of the resin is easily caused. In addition, there is a high possibility that the synthetic resin portion that insulates the commutator pieces of the commutator will be thermally degraded. In particular, commutator motors used in electric blowers for vacuum cleaners tend to be smaller and have higher power, and the current density of carbon brushes increases accordingly. As described above, when the brush main portion has a high resistance, the heat generation thereof tends to be extremely large, and thus there is a problem that the life of the carbon brush and the commutator is shortened. By the way, the conventional resin-bound type carbon brush has a temperature of 20
It is known that when the temperature exceeds 0 ° C., the transverse rupture force is rapidly reduced. An object of the present invention is to provide a carbon brush that can reduce resistance loss and improve the life.

[0005]

Means for Solving the Problems] To solve the above problems
According to a first aspect of the present invention , a pigtail formed of a material having a lower resistivity than a material forming the main part is connected to a main part of the brush which is formed mainly of carbon and is worn in contact with the commutator. The commutator side portion of the pigtail is located inside the brush main portion .
And is provided over substantially the entire length of the main portion in the main current direction. Also, to achieve the same task
The invention of Item 2 is based on the fact that carbon is formed as a main component.
This main part is attached to the main part of the brush which is worn in contact with the commutator.
Pigtail made of a material with lower resistivity than the material
The carbon brush with the
A hole is provided in the main part of the main
Rectification of the pigtail into the hole
Insert the child side part and lower it than the brush main part.
A resistor that fills around the commutator side and hardens
Commutator side portion of the pigtail via copper powder
Is embedded in the main part of the brush, and the main current of this main part is
Direction, and the commutator side portion and
And the cross-sectional area of the copper powder is smaller than the cross-sectional area of the brush main part.
That's bad.

[0006]

In the carbon brush according to the first aspect of the invention, the brush main part having a high resistivity has a lower resistivity than the brush main part.
Since the commutator-side portion of the pigtail that directly guides the current extends in the main current direction of the brush main portion and is provided so as to be buried over substantially the entire length of the brush main portion, the commutation of the pigtail provided on the brush main portion is performed. Electricity can be conducted by using the child side portion as a main conductive path, and the total electric resistance of the brush main portion can be reduced. For this reason, the current loss in the brush main part can be reduced. At the same time, heat generation of the brush main part can be reduced. In addition, since the cross section of the pigtail is much smaller than the cross section of the main part of the brush, there is no significant reduction in the rectification resistance as compared with the case where the entire brush is made of a low-resistance electric conductor. In addition, since the total electric resistance of the brush main portion is small, a material having good seating properties of the brush main portion with respect to the commutator (that is, characteristics of the carbon brush maintaining contact with the commutator surface) can be used. Therefore, the occurrence of sparks with the commutator can be reduced.
Moreover, as described above, the pick tail
The commutator side is surrounded by the main part of the brush.
The external force acting upon the contact of the commutator with the commutator
Regardless, it does not come off from the main part of the brush. Claims
In the carbon brush according to the second aspect, the brush main part
Has a higher resistivity than the main part of the brush, which has a higher resistivity.
Insert the commutator side of the pigtail that directly leads the current
While filling with copper powder around it and hardening
According to the configuration described above, the commutator side portion is easily
The main power of the brush main part does not move inadvertently in the hole.
Extend in the flow direction and extend over substantially the entire length of the main part of the brush.
Can be opened. Thereby, in the main part of the brush
The main part is the commutator side of the pigtail
It can conduct electricity as a conducting path,
Total electric resistance can be reduced. For this reason, the brush
Current loss can be reduced. With this, the main part of the brush
Heat generation can be reduced. In addition, the cross section of the pigtail
Because it is much smaller than the cross section of the main part of the brush, the brush
Rectifier resistor compared to the case where the whole is made of low resistance electrical conductor
There is no significant drop in resistance. In addition, all the electrical resistance of the main part of the brush
Because of the low resistance, the main part of the brush against the commutator
Materials with good riding properties can be used. Therefore, rectification
The occurrence of sparks with the child can be reduced. Moreover,
The commutator side of the picktail that conducts the current directly as described above
The part is surrounded by the main part of the brush.
Irrespective of the external force acting when the part contacts the commutator,
It does not come off from the main part of the brush. Moreover, the cross-sectional area
The thickness of the main part of the brush increases due to the size of
Combined with the strength of the main part of the brush,
The layer of copper powder that generates heat when current flows
And the amount is small, the copper powder layer
The force applied to the main part of the brush with thermal expansion can be reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. In FIG. 3, reference numeral 1 denotes a metal motor case, which is formed of a case main body 2 and a case end plate 3.

The case body 2 is formed by opening a side of the cylindrical portion 4 having the bottom 4a opposite to the bottom 4a, and integrally providing a mounting portion 5 at a peripheral portion of the opening. The mounting part 5
It is formed by an annular flat portion 6, a cylindrical portion 7, and a protruding edge 8. The annular flat portion 6 is formed integrally from the opening edge of the case main body 2 so as to protrude outward from the main body 2, and is formed into a cylindrical portion 7.
Is bent from the outer periphery of the annular flat portion 6 toward the bottom 4a to be formed parallel to the case body 2, and the protruding edge 8 is formed to be bent at a right angle outward from the tip of the cylindrical portion 7. . An exhaust hole 9 is provided on the bottom 4a side of the cylindrical portion 4, and an exhaust hole (not shown) is also provided on the bottom 4a. At the center of the bottom 4a, a bearing mounting portion 11 that houses the bearing 10 is formed.

The case end plate 3 has, for example, a substantially band-like shape having a planar shape extending in the radial direction so as to cross one end opening of the case body 2 in the radial direction. The attachment portion 13 is formed integrally. Both ends of the case end plate 3 are screwed to the annular flat portion 6. For this reason, one end opening of the case main body 2 is partially opened without being completely closed.

A stator 14 and a rotor 16 with a commutator 15 disposed inside the stator 14 are housed in the case body 2. The outer diameter of the stator core of the stator 14 when viewed from the axial direction is substantially square, and the four chamfered corners are fixed to the case body 2 so as to be in close contact with the inner surface of the cylindrical portion 4. Due to this fixation, air passages 19 are respectively 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 the rotor shaft 17 passes through 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 15 a made of synthetic resin that rotates integrally with the rotor shaft 17,
A large number of commutator pieces 15b are provided on the outer periphery of the boss 15a at intervals in the circumferential direction. Commutator piece 1
The ends of the rotor windings are electrically connected to the commutator pieces 15b.

A brush device 18 on the positive electrode side and a brush device 18 on the negative electrode side are mounted on the cylindrical portion 4 of the case body 2 with a commutator 15 interposed therebetween. Hereinafter, the details of the brush device 18 will be described with reference to FIGS.

The brush holder 21 provided in the brush device 18
Is formed of an electrically insulating material such as a synthetic resin, and its main body 22 has an insertion hole 23 and has a substantially rectangular cylindrical shape.
The main body 22 has a support piece 24 overlapping the outer surface of the case main body 2.
Are protruded integrally. As shown in FIG. 3, the brush boulder 21 has a mounting opening 4 b for opening the main body 22 to the cylindrical portion 4.
, And the support piece 24 is fixed to the case body 2 by tightening the support piece 24 to the cylindrical portion 4 with a screw 26.

As shown in FIG. 2, a metal brush guide 27 is fitted in the insertion hole 23 of the brush holder 21. The brush guide 27 projects from the main body 22 toward the commutator 15. Commutator 15 of this guide 27
At the opposite end, a retaining piece 28 that catches on 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 face of the main body 22 is pulled. A cut-and-raised piece 25 is formed. The cut-and-raised piece 25 sandwiches the main body 22 between the cut-and-raised piece 25 and the retaining piece 28, and
7 is fixed.

The main body 22 of the brush holder 21 has a terminal mounting hole 29. The mounting hole 29 is provided in the insertion hole 2
3, and a terminal metal fitting 30 for current supply is mounted inside thereof.

The terminal fitting 30 is made of sheet metal, and
3 and a terminal attachment hole 29
And the stopper piece 32 to be inserted into the body. The retaining piece 32 has a convex portion 33 curved in an arc-shaped cross section.
An elastically deformable bent portion 34 is formed continuous with the convex portion 33 and bent into a mountain shape. The convex portion 33 and the top of the bent portion 34 are pressed against the inner surface of the terminal mounting hole 29. Have been. The distal end of the bent portion 34 protrudes from the terminal mounting hole 29 to the inside of the main body case 2, and a locking piece 35 that hooks on the end face of the main body 22 is integrally cut and raised at the protruding portion 34 a. The locking piece 35 is provided between the terminal mounting hole 2 and the cap piece 31 with the main body 22 interposed therebetween.
9 to prevent the terminal fitting 30 from coming off. As shown in FIG. 3, 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. .

A carbon brush 41 is accommodated in the brush guide 27 so as to be movable in the axial direction. The brush 41 has a pigtail 45 connected to a brush main portion 42 as shown in FIGS.

The brush main portion 42 is formed by compression-molding a conductive material containing carbon as a main component together with a binder made of synthetic resin, and sintering the material to form a rod having a square cross section as a whole. ing. A hole 44 is provided at the center of the brush main portion 42 over substantially the entire length in the axial direction (that is, extending in the main current direction of the brush main portion 42). In FIG. 1, reference symbol A indicates a portion of the brush main portion 42 that is worn by contact with the commutator 15, that is, a length range of an effective use length portion.

The pigtail 45 is formed by twisting three bundles each of which is made up of 27 copper wires each having a diameter of 0.08 mm. The pigtail 45 is longer than the conventional one by a length substantially corresponding to the effective use length A of the brush main portion 42, and the commutator-side portion 4 at one end thereof is extended.
5a is inserted and fixed in the hole 44 up to its far end. Since the commutator side portion 45a is made of copper, the (electrical) resistivity is lower than the (electrical) resistivity of the conductive material forming the brush main portion 42, and the diameter of the commutator side portion 45a is vertical and horizontal in the cross section of the brush main portion 42. Each smaller than the dimensions.

The commutator side portion 45a of the pigtail 45 is fixed to the brush main portion 42 via a copper powder 43. That is, the inside of the hole 44 is filled with copper powder 43 around the commutator-side portion 45a and compacted.
The powder portion 43a located at the opening end on the anti-commutator side of
The pigtail 45 is fixed to the brush main part 42 by impregnating and curing the liquid adhesive.

The tip of the commutator-side portion 45a embedded in the brush main portion 42 in this manner is connected to the tip 4 of the brush main portion 42 at the initial stage of use of the carbon brush 41.
2a. The other end of the pigtail 45 is spot-welded to the cap piece 31 which closes the opening of the insertion port 23.

A compression coil spring 46 is interposed between the other end surface of the carbon brush 41 and the cap piece 31 that closes the opening end of the insertion opening 23. Compression coil spring 46
Always presses the carbon brush 41 toward the commutator 15. Due to this pressing, the commutator side end of the carbon brush 41 protrudes from the brush guide 27 and is slidably pressed against the outer peripheral surface of the commutator 15.

The motor case 1 and the bearing 1 described above
The commutator motor for the electric blower used for, for example, an electric vacuum cleaner is formed by the 0, 12, the stator 14, the rotor 16, and the brush device 18.

As shown in FIG. 3, a centrifugal fan 52 that rotates integrally with the rotor shaft 17 via a nut 51 is attached to an end of the rotor shaft 17 that protrudes outside the motor case 1. The fan 52 has a suction port 53 at the center and a discharge port 54 at the periphery. The centrifugal fan 52 is covered with a fan cover 55. The cover 55 is fitted and mounted on the mounting portion 5 of the main body case 2, and the fan cover 55 has an opening 56 for sucking air. Opening 56
Has entered the suction port 53. Therefore, when the centrifugal fan 52 is rotated, air is sucked through the opening 56, and the sucked air is discharged from the outlet 5 of the centrifugal fan 52.
4 is discharged.

Between the centrifugal fan 52 and the mounting part 5,
A disk-shaped rectifying plate 57 that guides the air discharged from the centrifugal fan 52 into the motor case 1 is provided. Rectifier plate 5
Numeral 7 rectifies the air discharged from the centrifugal fan 52 and changes the pressure of the air from the dynamic pressure to the static pressure in the rectification process, and is screwed to the frame end plate 3. The air rectified by the rectifying plate 57 flows into the motor case 1 and flows through the air passage 19,
It is discharged from the exhaust port 9 to the outside of the motor case 1.

In the electric blower having the above-described structure, the current flowing between the portion of the pigtail 45 located outside the brush main portion 42 and the commutator piece 15b of the commutator 15 during operation thereof is supplied to the brush main portion 42 inside the brush main portion. Carbon brush 4
1 mainly flows through the commutator side portion 45a. The commutator side portion 45 a has a lower electric resistance than the brush main portion 42, extends in the main current direction of the carbon brush 41, and is embedded in the brush main portion 42 over substantially the entire length thereof .
And without any intermediary members
Since the flow is passed , the total electric resistance of the carbon brush 41 can be reduced. Therefore, the resistance loss of the current in the carbon brush 41 can be reduced, and the operating efficiency of the commutator motor for the electric blower can be improved accordingly.

As described above, since the total electric resistance of the carbon brush 41 can be reduced, the brush main portion 42
Heat generation can be reduced. In addition, the occurrence of sparks between the brush main part 42 and the commutator 15 can be reduced for the following reasons. First, since the diameter of the commutator-side portion 54a of the pigtail 45 serving as the main conductive path is smaller than the vertical and horizontal dimensions of the cross section of the brush main portion 42, the commutator-side portion 45a is smaller than the brush main portion 42. The cross-sectional area of the layer of the copper powder 43 and the commutator-side portion 45 a at the contact surface with the commutator 15 is smaller than the cross-sectional area of the brush main part 42. Therefore, the rectification resistance does not significantly decrease as compared with the case where the entire brush main portion 42 is made of a low-resistance electric conductor, so that the short-circuit current during rectification can be reduced. Second, since the electric resistance of the entire brush main portion 42 is small as described above, the main portion 42 can be formed using a material having good seating properties, for example, a resin-binding type conductive material. The elastic coefficient of the entire brush main portion 42 can be reduced. As described above, since the heat generated by the brush main part 42 itself is small and the heating by the spark is also small, the temperatures of the brush main part 42 and the commutator 15 can be suppressed low.

Therefore, since the brush main portion 42 and the commutator 15 can be prevented from being thermally degraded, their life and hence the life of the commutator motor can be improved, and the commutator motor is suitable for high input and downsizing. . In addition, since the temperature rise of the brush main portion 42 and the commutator 15 is small as described above, the brush main portion 42 can be reduced accordingly, and the axial length of the commutator 15 can be reduced. Therefore, the length of the rotor shaft 17 can be shortened, and accordingly, the entire electric blower can be downsized in the axial direction.

In the early stage of using the carbon brush 41, the tip 42a of the brush main part 42 closes the end of the hole 44 filled with copper powder on the commutator side. Copper having different physical properties and the carbon material of the brush main portion 42 do not make sliding contact with the commutator 15 when the contact of the carbon brush 41 is not familiar.
Therefore, the initial performance is stable, and the copper powder 43, the pigtail 45, and the brush main part 42 are slid on the commutator 15 in a state where the contact of the brush main part 42 with the commutator 15 becomes familiar with use. It can be in dynamic contact. In addition, since the tip portion 42a of the brush main portion 42 forms the bottom of the hole 44, the workability when the hole 44 is filled with the copper powder 43 can be improved.

The commutator side portion 4 of the pigtail 45
5a is arranged inside the brush main part 42 and is surrounded by the brush main part 42, so that the commutator-side part 45a and the commutator-side part 45a
It is possible to prevent the layer of the copper powder 43 for fixing the same from peeling off from the brush main part 42. Moreover, the commutator side portion
Brush the cross-sectional area of 45a and the layer of copper powder 43 around it
Since the cross-sectional area of the main part 42 was made smaller,
The thickness of the brush main part 42 is increased, and the brush main part 4 is correspondingly thickened.
2 can be strengthened. In addition, the passage of current
The layer of copper powder 43 that generates heat is
On the other hand, the copper powder
The force applied to the brush main part 42 due to the thermal expansion of the layer 43
Can be smaller. Therefore, the brush main part 42 and the
The commutator-side portion 45a embedded therein and the copper powder around it
The brush main part 4 is used at the time of use based on the difference in thermal expansion with the layer of the powder 43.
2 can be less likely to be damaged.

FIGS. 4 and 5 show a second embodiment of the present invention. In this embodiment, the brush main portion 42 is provided with a stepped hole 44 from the side opposite to the commutator. The hole 44 includes a large-diameter portion 44a and a small-diameter portion 44b, and extends in the main current direction of the brush main portion 42 and is formed over substantially the entire length of the brush main portion 42. The large diameter portion 44a is the brush main portion 4
2 is opened at the end face on the anti-commutator side. Pigtail 4
The commutator-side portion 45 a of 5 penetrates the large-diameter portion 44 a of the hole 44 and is inserted in contact with the inner surface of the small-diameter portion 44 b of the hole 44. The large-diameter portion 44a of the hole 44 is filled with copper powder 43 and compacted, and by impregnating the powder 43 with a liquid adhesive, the brush main portion 42 is formed.
Is fixed to the pigtail 45.

Since the configuration other than the above is the same as that of the first embodiment, the same components as those of the first embodiment are denoted by the same reference numerals and the description thereof will be omitted. Also, in the configuration of the second embodiment, the intended object of the present invention can be achieved by the same operation as that of the first embodiment.

Further, the present invention is said to each embodiment is not limited. For example, a spiral hole is provided inside the brush main part 42, and a commutator side end 45 a of the pigtail 45 is attached thereto, and this commutator side part 45 a is used as a main current of the brush main part 42. It may be provided over substantially the entire length in the direction.

[0034]

As described in detail above, the invention of claim 1 is described.
In the carbon brush according to the present invention, since the total electrical resistance of the brush can be reduced by using a pigtail that directly leads a current, the operation efficiency of a commutator motor or the like using the carbon brush can be improved. Above, the heat generation of the brush main part is small and the occurrence of sparks between the brush and the commutator can be reduced, so that the temperature rise of the brush main part is suppressed, and the life of the carbon brush itself and the commutator motor using the same becomes longer. Can be improved, and the commutator side of the pigtail
The separation of the components can be prevented by the brush main part .
Further, in the carbon brush according to the invention of claim 2,
Also use the pigtail to direct the current
Since the total electrical resistance can be reduced, this carbon brush
The operating efficiency of the commutator motor used can be improved,
Above, less heat is generated in the main part of the brush, and between the commutator and
Of the main part of the brush
Temperature rise is suppressed, and the carbon brush itself and this
The life of commutator motors and the like that use
Commutator side part of pigtail and copper fixing this part
The main part of the brush prevents the powder layer from peeling off
You. In addition, embedding pigtails in the main part of the brush
Is easy and with the brush main part and embedded in it
Brush based on the difference in thermal expansion between the pigtail and copper powder
The risk of the main part being damaged can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view of a brush device provided with a carbon brush according to a first embodiment of the present invention.

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

FIG. 3 is a side view showing a partially sectioned electric blower provided with the brush device shown in FIG. 1;

FIG. 4 is a longitudinal sectional side view of a brush device provided with a carbon brush according to a second embodiment of the present invention.

FIG. 5 is a sectional view taken along the line YY of FIG. 4 according to the first embodiment;

[Explanation of symbols]

15: commutator, 41: carbon brush, 42: main part of brush, 43: copper powder, 44: hole, 45: pigtail, 4
5a: Commutator side portion of pigtail.

Continuation of the front page (56) References JP-A-62-171434 (JP, A) JP-A-57-189267 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01R 39 / 00-39/64 H02K 13/00-13/14

Claims (2)

(57) [Claims] 1. A carbon formed by connecting a pigtail formed of a material having a lower resistivity than a material forming the main part to a main part of the brush which is formed mainly of carbon and wears in contact with the commutator. In the brush, a commutator side portion of the pigtail is buried inside the brush main portion.
The carbon brush is provided over substantially the entire length of the main portion in the main current direction. 2. When molded with carbon as a main component,
This main part is attached to the main part of the brush which is worn in contact with the commutator.
Pigtail made of a material with lower resistivity than the material
The carbon brush with the
A hole is provided in the main part of the main
Rectification of the pigtail into the hole
Insert the child side part and lower it than the brush main part.
A resistor that fills around the commutator side and hardens
Commutator side portion of the pigtail via copper powder
Is embedded in the main part of the brush, and the main current of this main part is
Direction, and the commutator side portion and
And the cross-sectional area of the copper powder is smaller than the cross-sectional area of the brush main part.
A carbon brush, characterized by a comb.