JP3431261B2 - Electric brush - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a structure for connecting a lead wire to a brush main body by a powder stopping method using a metal powder, and more particularly to an electric machine brush having a stable mounting resistance and excellent durability.

[0002]

2. Description of the Related Art As one means for connecting a lead wire to a brush body made of a carbonaceous molding or the like, a base end portion of the lead wire is inserted into a hole formed in the brush body and the periphery thereof is inserted. There is known a method of filling and crimping with a metal powder and connecting it, which is widely used as a powder stopping method.

Conventionally, copper powder has been used as a metal powder for a long time in the powder stopping method, but since the copper powder has a coefficient of thermal expansion different from that of the carbonaceous material constituting the brush main body, the copper powder is used at the connecting portion during use. Due to the effect of Joule heat generated and heat conduction heating received from the electric motor, a gap is gradually formed between the fixed metal powder and the lead wire, and the lead wire is often pulled out during use. Therefore, the structure using copper powder needs to be used at a temperature of 120 ° C. or lower, and cannot be applied to a high-performance electric motor.

In order to solve such a problem, a powder stopping brush made of metal powder having a coefficient of thermal expansion and a mounting resistance lower than that of copper powder has been proposed. For example, as the metal powder for fixing the lead wire, sponge iron powder (JP-A-56-71284) and sponge iron powder subjected to blue heat embrittlement treatment (JP-A-57-71284).
27587), silver-plated sponge iron powder (JP-A-57-27588), mixed powder of graphite powder and / or metal powder and sponge iron powder (JP-A-1-154480), 200 A mixture of copper powder and tin powder that can be used even at temperatures of ℃ or higher
No. 30079 gazette), etc.

[0005]

Recently, a brush used for an electric motor for a vehicle is subject to a temperature of about 200 ° C. in accordance with the progress of speeding up, and moreover, it is constantly subjected to a vibration impact from the vehicle body. Durability is no longer satisfied with the metal powder powder stopping structure. For this reason, there is a demand for a powder-stopping structure that has even lower attachment resistance and excellent lead wire pull-out strength.

An object of the present invention is to provide a brush for an electric machine having a powder stopping structure which maintains stable attachment resistance under severe operating conditions and exhibits excellent durability.

[0007]

In order to achieve the above object, an electric machine brush according to the present invention has a brush structure in which a lead wire is crimped and connected to a hole formed in a brush body through a metal powder. In the metal powder, Cu1.3-1.7
% By weight, Ni 1.6-4.4% by weight, Mo 0.25-
A structural feature is that a composite steel powder having a composition containing 0.55% by weight and the balance Fe as a main component is used.

As shown in FIG. 1, a brush for an electric machine of the present invention has a hole 2 formed in the head of a brush body 1 having a predetermined shape, and the base end of a lead wire 3 is inserted in the hole 2. It has a connection structure in which the lead wire 3 is fixed by inserting the metal powder 4 into the periphery and crimping the lead wire 3, and the brush body 1 is made of a carbonaceous molding such as graphite. Is formed by a stranded copper wire with a locking piece at the tip.

In the brush structure described above, 1.3 to 1.7% by weight of Cu and Ni are added to the metal powder for crimping and fixing the lead wire.
An important requirement of the present invention is to selectively use a composite steel powder having a composition in which 1.6 to 4.4% by weight, Mo 0.25 to 0.55% by weight, and the balance Fe as a main component. This composite steel powder is obtained by reducing atomized iron powder and mixing and sintering the above alloy components. As other alloy composition, Mn of 0.10% by weight or less and 0.05% by weight or less Of S
i may be included.

The composite steel powder preferably has a grain size of 80 mesh or less, preferably 100 mesh or less, and a stress relaxation amount of 3% or less. As shown in FIG. 2, the amount of stress relaxation is obtained by inserting 10.0 g of metal powder 4 into a mold 5 (inner diameter 20 mm, height 50 mm), descending the crosshead 7 of the autograph 6 and When the metal powder 4 is compressed and the load of 100 kgf is reached, the load is measured 30 minutes after stopping the crosshead 7 and the stress relaxation amount (%) = 100 kgf −30
It is the value calculated from the load (kgf) after the lapse of minutes. According to this evaluation method, when the crosshead 7 is stopped, the metal powder 4
Acts to relieve stress in a closed container, but this phenomenon is the same as the mechanism when crimping and fixing the lead wire to the hole of the brush main body through the metal powder. The smaller the amount, the better the durability.
By the way, the stress relaxation amount of copper powder by this evaluation method is 4-5%.
Is.

[0011]

In the present invention, the metal powder for powder-fixing the lead wire is a composite steel powder having a different composition from the copper powder and sponge iron powder used in the prior art, and has high green density and stress. It has low relaxation amount and excellent oxidation resistance.
Therefore, the brush for an electric machine, in which the connecting portion is configured by using this, has a low mounting resistance, and the resistance fluctuation is small even under a condition accompanied by vibration particularly under heating at about 200 ° C., so that it is harsh like an electric motor for a high speed vehicle. Even when used under various conditions, stable resistance performance and excellent durability without pulling out lead wires are maintained.

[0012]

EXAMPLES Examples of the present invention will be specifically described below in comparison with comparative examples.

Example 1 A brush body having a width of 32 mm, a height of 50 mm and a thickness of 12.5 mm made of an electrographitic material has a diameter of 6 mm and a depth of 15 mm at the head thereof.
The hole was formed, and the base end of the lead wire made of annealed copper wire was inserted into this hole, filled with metal powder, and crimped and fixed to form a connection. As the metal powder, Cu in weight%;
1.60, Ni; 0.31, Mo; 0.48, Si;
0.01, Mn; 0.05, C; 0.004, P;
005, S; 0.006, the balance being Fe, a composite steel powder having an apparent density of 2.97 g / cm ³ , a grain size of 100 mesh or less, and a fluidity of 23.9 sec / 50 g [Kawasaki KIP Sigmaloy 415S] manufactured by Iron and Steel Co., Ltd. was used.

The stress relaxation amount of the composite steel powder used, the caulking resistance of the obtained electric machine brush, the pull-out strength of the lead wire, the rate of increase in the weight of oxide, etc. were measured, and the results are shown in Table 1. The measurement conditions for the amount of stress relaxation are: sample; 10.0 g
, Mold size; diameter 20mm, height 50mm, crosshead; 1t capacity, 100kgf full scale, descending speed;
0.5m / min, maximum load: 100kgf, load measurement elapsed time: 30 minutes, caulking resistance is 200 ℃ at room temperature
At 100 ° C for 100 hours, and at 100 ° C for 100 hours while applying mechanical vibration, and at the time of vibration heating for 3 hours. It was defined as the weight increase rate after exposure to temperature for 50 hours.

Comparative Example 1 A sponge iron powder [MH100.28, manufactured by Heganes Co., Ltd.] was used instead of the metal powder, and the powder-measuring connection was performed under the same conditions as in Example 1 except that a brush for an electric machine was produced. The amount of stress relaxation of the sponge iron powder used and the characteristics of the electric machine brush measured in the same manner as in Example 1 are also shown in Table 1.

Comparative Example 2 A brush for an electric machine was manufactured by replacing the metal powder with copper powder [CE-5, manufactured by Fukuda Metal Co., Ltd.] under the same conditions as in Example 1 except for the above. The amount of stress relaxation of the copper powder used and the characteristics of the electric machine brush measured in the same manner as in Example 1 are also shown in Table 1.

[0017]

[Table 1]

From the results shown in Table 1, the amount of stress relaxation of the metal powder used in Example 1 was 3% or less, and the electric machine brush had stable caulking resistance and good pull-out strength.
On the other hand, the metallic copper powders of Comparative Examples 1 and 2 had a stress relaxation amount of more than 3%, and both caulking resistance and pull-out resistance were inferior to those of Example 1.

[0019]

As described above, according to the present invention, by using the composite steel powder having a specific composition as the powder metal powder, troubles such as stable mounting resistance and pulling out of the lead wire over a long period of time are always prevented. Provided is a high-performance electric machine brush that guarantees excellent durability that does not occur.
Therefore, it is useful as a brush for an electric machine used under severe conditions such as an electric motor of a high speed vehicle.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view showing the structure of a brush for an electric machine according to the present invention.

FIG. 2 is a cross-sectional explanatory view showing a stress relaxation amount measuring device.

[Explanation of symbols]

1 brush body 2 holes 3 lead wire 4 metal powder 5 mold 6 Autograph 7 crosshead

Continuation of the front page (56) References Japanese Patent Laid-Open No. 2-30079 (JP, A) Japanese Patent Publication No. 11-528 (JP, B1) Actual Publication No. 11-1964 (JP, Y1) (58) Fields investigated (Int .Cl. ⁷ , DB name) H01R 39/20 H02K 13/00

Claims (2)

(57) [Claims] 1. A brush structure in which a lead wire is pressure-bonded to a hole formed in a brush main body via a metal powder to connect the metal powder with Cu1.3 to 1.7% by weight and Ni1.6.
A brush for an electric machine, characterized in that a composite steel powder having a composition of ˜4.4 wt%, Mo 0.25˜0.55 wt%, and balance Fe as main components is used. 2. A composite steel powder having a grain size of 80 mesh or less,
The electric machine brush according to claim 1, wherein the amount of stress relaxation is 3% or less.