JPH07194065A - Brush device for starter motor - Google Patents

Abstract

PURPOSE:To improve durability of a brush device by using black graphite, which contains a large quantity of copper, for a brush, and making the content of copper in a brush on a positive pole smaller than that in a brush on a negative pole. CONSTITUTION:An insulating board 13 is fixed to a board 11 by a burring section 12. A brush 16 on a positive pole is retained movably in the radial direction of an armature 8 with a U-shaped section. A brush bolding frame 14 is fixed to the insulating board 13 with a fastening part 15, and also it is insulated from the board 11. A brush 23 on a negative pole is retained capacity of shifting in the radial direction of the armature 8 with a brush holding frame 21. Here, the brush 16 on the positive pole is a mixture which contains copper (copper powder) by 52wt.%, graphite by 40wt.%, and other ingredients by 8wt.%. The brush 23 on the negative pole is a mixture which contains copper by 60wt.%, graphite by 32wt.%, and other ingredients by 8wt.% the same as before. As a result, the abrasion resistance improves by reducing the copper content of the brush on the positive pole to 52%, and the abrasion speed on the same level as the brush on the negative pole can be gotten.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brush device for a starter motor, and more particularly to a brush device suitable for a starter motor for an automobile.

[0002]

2. Description of the Related Art As a conventional one for improving the durability of a metallic graphite brush used for a starter motor for an automobile, there is known one disclosed in Japanese Patent Publication No. 4-74939. In the case of starter motors for automobiles,
The copper content of the brush is 50-80% by weight (percent)
(Hereinafter, all copper contents are based on weight%). In the case of starter motors for automobiles, the field is often a 4-pole winding-type field magnet or a 6-pole permanent magnet-type field magnet. Individuals are common.

Here, in a DC motor including a starter motor, when the type of winding of the rotating armature is wave winding, the number of brushes is at least one positive electrode and one negative electrode regardless of the number of magnetic poles on the electric circuit. Although there is no problem at all, it is known that the decrease in the number of brushes causes an increase in the current density per brush at the same current, and that the heat of the brush causes a thermal factor to affect the wear of the brush. There is. Further, as described in Japanese Patent Publication No. 4-74939,
For high output such as starter motors, a metal graphite brush with a high copper content is preferable, but the higher the copper content, the greater the amount of wear of the brush as the number of times the starter motor is used increases. Is also known.

Further, in a starter motor using a brush having a high copper content, if the number of brushes is reduced, the energization of the starter motor is cut off after the engine is started, and then a braking force for inertial rotation of the rotating armature by a brush pressing spring. Therefore, the inertial rotation time of the rotating armature is extended and the brush wear due to mechanical factors due to friction between the commutator and the brush is increased. Along with this, a phenomenon in which the abrasion of the positive electrode side brush is larger than the abrasion of the negative electrode side brush becomes prominent.

4 to 7 show a conventional brush device for a starter motor. FIG. 4 is a plan view of the brush device.
5 is a side view showing a state in which the starter motor is partially attached, FIG. 6 is a characteristic diagram showing a current of the starter motor at the time of engine start, and FIG. 7 is a characteristic diagram showing a wear amount of the brush. In these figures, 1 is a starter motor and 2 is a yoke. 3 is a field magnetic pole made of a permanent magnet, which is attached inside the yoke 2 and has 6 poles. Reference numeral 4 denotes a bracket, which rotatably supports a rotary shaft 9 of a rotary armature 6 described later via a bearing metal 5.

Reference numeral 6 denotes a rotary armature, which is constructed as follows. 7 is a cylindrical iron core, and 6 field magnetic poles 3
It is provided so as to face the field magnetic pole in a cylindrical space formed inside. On the iron core 7, a wave winding armature coil (not shown) is wound. A commutator 8 is connected to the armature coil. Reference numeral 9 denotes a rotating shaft, and the iron core 7 and the commutator 8 are fitted on the rotating shaft 9 to form a rotating armature 6 that integrally rotates.

Reference numeral 10 is a brush device, which is constructed as follows. Reference numeral 11 denotes a disk-shaped substrate, which is formed by punching a steel plate. 12 is a burring portion of the substrate 11,
Reference numeral 13 is an insulating plate, and the insulating plate 13 is fixed by caulking to the substrate 11 by two burring portions 12.
Reference numeral 14 denotes a positive electrode side brush holding frame, which is formed from a steel plate by press working and holds a positive electrode side brush 16 described later by its U-shaped portion so as to be movable in the radial direction of the commutator 8. 1
Reference numeral 5 denotes a crimping portion of the brush holding frame 14, which is formed by burring. The brush holding frame 14 is fixed to the insulating plate 13 by the caulking portion 15 and is insulated from the substrate 11. 16 is a brush on the positive electrode side, 17 is a lead wire connected to the brush 16 on the positive electrode side, 18 is a connection terminal connected to the positive electrode of a power source (not shown), 19 is an insulating bush, and the lead wire 17 is the bracket 4 (see FIG. 5). ) Is insulated. A brush spring 20 presses the brush 16 against the commutator 8.

Reference numeral 21 denotes a brush holding frame on the negative electrode side, which is also made of a steel plate. Reference numeral 22 denotes a crimping portion of the brush holding frame 21, which is formed by burring.
The brush holding frame 21 is fixed to the substrate 11 by the caulking portion 22 without being insulated by caulking. Reference numeral 23 denotes a negative brush, which is held by the brush holding frame 21 so as to be movable in the radial direction of the commutator 8. 24 is a lead wire, one side of which is connected to the negative electrode side brush 23 and the other side of which is the substrate 11
It is electrically connected to (earth) by welding. 25
Is a brush spring and presses the negative electrode side brush 23 against the commutator 8. Reference numeral 26 is a screw for fixing the substrate 11, that is, the brush device 10, to the bracket 4 (FIG. 5).

One brush on the positive electrode side and one brush on the negative electrode side configured as described above are used. This brush is a so-called metallic graphite brush formed by mixing and molding copper powder and graphite powder. The dimensions are width (dimension in the circumferential direction of the commutator) x depth (dimension in the coaxial direction) x height is 4 x 20 x 12 [mm]. The same component is used for both the positive electrode side brush and the negative electrode side brush, and the component is a mixture of 60% by weight of copper (copper powder), 32% by weight of graphite and 8% by weight of other components.

A starter motor equipped with the brush device 10 having the brushes 16 and 23 is mounted on an automobile engine. And every time the engine is started,
A large current is applied to the rotating armature 6 for a few seconds through the brushes 16 and 23, and a pinion (not shown) coupled to the rotating armature meshes with the ring gear to start the engine. By repeating this start, the brush gradually wears, and when the predetermined wear limit amount, 7.5 mm in this example, is reached, the pressing force by the brush springs 20 and 25 can be reduced and the brush can be moved in the direction of the commutator. The size is restricted by the structure of the brush holding frames 14 and 21, so that the brush holding frames 14 and 21 cannot be used.

By the way, in order to grasp the progress of wear due to the repeated use of the brushes 16 and 23, 12 [V] and 1.2 [k] to which the brush device 10 is attached are attached.
The w) starter motor was attached to an engine with a displacement of 1600 [cc], and a repeating test of tens of thousands of cycles was performed with 2 seconds of driving and 15 seconds of rest as one cycle, and the amount of brush wear after each cycle was measured. .

At this time, the current flowing through the brushes 16 and 23 is a peak current of about 500 [A] and an average current of about 150 [A] in each cycle, as shown in FIG. FIG. 7 shows the test results conducted as described above. In FIG. 7, A shows the progress of wear of the positive electrode side brush 16, and B shows the progress of wear of the negative electrode side brush 23. The amount of wear of the positive electrode side brush 16 is large, and the brush wear limit (7.5
[Mm]), the amount of abrasion of the brush 23 on the negative electrode side is as small as about 4 [mm], and it can be understood that the brush 23 can endure more than 10,000 cycles.

[0013]

Conventionally, in the starter motor, the copper content of the brush, the number of brushes, and the wear of the brush have the above-mentioned relationships, but in the case of a mass-produced starter motor, the standardization is also aimed at. The same brush material is generally used for both the positive electrode side and the negative electrode side. However,
When using a brush with a high copper content and reducing the number of brushes from the viewpoint of high output and cost reduction, the positive electrode side brush reaches the wear limit first and the negative electrode side brush wears out from the above relationship. Although the wear allowance is still left to the limit, there is a problem that the function of the starter motor will not be fulfilled in the middle of the service life. The present invention has been made to solve the above problems, and an object thereof is to obtain a brush device for a starter motor having high output and high durability.

[0014]

In a brush device for a starter motor according to the present invention, the brush is made of metal graphite having a high copper content, and when the number of positive electrode side brushes and the number of negative electrode side brushes are the same, The copper content of the side brush is smaller than that of the brush on the negative electrode side. Further, when the number of positive electrode side brushes is twice the number of negative electrode side brushes, the copper content of the negative electrode side brush is made smaller than the copper content of the positive electrode side brush.

[0015]

The brush of the brush device for the starter motor is used at a relatively high current density, and from the viewpoint of wear resistance, a metal graphite material having a copper content of about 50 to 80% by weight is preferable, but a copper content is preferable. The larger the amount, the faster the wear rate and the greater the difference depending on the polarity used. The starter motor brush device according to the present invention eliminates the difference due to the polarity of brush wear by using brushes having different copper contents on the positive electrode side and the negative electrode side, and is a metal-graphite brush having a high copper content. However, the brush can be used without waste up to the wear limit of the brush on both the positive electrode side and the negative electrode side.

That is, when the number of the positive electrode brushes and the number of the negative electrode brushes are the same, the wear resistance of the positive electrode brushes is improved by making the copper content of the positive electrode brushes smaller than that of the negative electrode brushes. Wear should proceed to about the same degree.

When the number of positive electrode side brushes is twice the number of negative electrode side brushes, the wear resistance of the negative electrode side brush is improved by making the copper content of the negative electrode side brush smaller than that of the positive electrode side brush. Then, wear of the brushes should proceed to the same degree on both sides.

[0018]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. A positive electrode side brush having a small copper content is used in place of the positive electrode side brush 16 shown in FIG. 4, and the positive electrode side brush has a copper content (copper powder) of 52% by weight and a graphite content of 40% by weight. , And 8% by weight of other components. The negative electrode side brush is a mixture having a copper content of 60% by weight, a graphite content of 32% by weight, and other components of 8% by weight, similar to the one shown in FIG.

A brush device using such a brush on the positive electrode side and a brush on the negative electrode side is incorporated into a starter motor having an output of 1.2 [kw] just like the conventional device of FIG.
The amount of wear of the brush after each cycle was compared by setting it to a 00 cc engine and driving for 2 seconds and resting for 15 seconds as one cycle. The results are shown in Fig. 1. In FIG. 1, C is a line showing the progress of wear of the positive electrode side brush, and D is a line showing the progress of wear of the negative electrode side brush. According to this, the copper content of the positive electrode side brush is reduced to 52%. By doing so, the wear resistance is improved and the wear rate is similar to that of the negative brush,
It can be seen that the brush device can be used for more than 30,000 cycles.

Further, as is clear from the test results shown in FIG. 1, the wear rate of the positive electrode side brush is made to be equal to that of the negative electrode side brush by decreasing the copper content of the positive electrode side brush to slightly less than 52% by weight. Can be the same. In addition,
Since the wear rate of each brush changes depending on the current density used and the length of time per starting cycle, the components of each brush can be appropriately selected regardless of the above-mentioned embodiment.

For example, the component of the brush on the positive electrode side is copper 50 to 5
5% by weight, graphite 42 to 37% by weight, other 8% by weight, and the copper content of the negative electrode side brush is 60% by weight.
Needless to say, the same effect can be obtained, and the copper content of the negative electrode side brush may be increased or decreased from 60% by weight within the range not impairing the object of the present invention. Further, the same effect can be obtained even if the number of positive brushes and the number of negative brushes are both the same.

With the above-described structure, the abrasion of the positive electrode brush and the negative electrode brush progresses at substantially the same speed, and the abrasion of the brush on one side limits the number of times the starter motor can be started. Without increasing the life of the starter motor.

Example 2. FIG. 2 is a plan view of a brush device showing another embodiment of the present invention. In this embodiment, there are two positive electrode side brushes and one negative electrode side brush. In FIG. 2, reference numeral 30 is a brush device, which is configured as follows. The positive electrode side brush 16 has the same copper content as that of the positive electrode side brush shown in FIG. 1 and has a copper content of 60% by weight, graphite of 32% by weight, and other components of 8% by weight. As shown in the drawing, two vertically identical structures having the same structure are provided symmetrically with respect to the horizontal center line in the figure, and both are connected to the connection terminal 18 via the lead wire 17. In this case, the positive brush 1
The current per one of 6 is half that shown in FIG.

Reference numeral 31 denotes a negative electrode side brush provided on the negative electrode side, which is composed of the same components as those used as the positive electrode side brush in Example 1, and has a copper (copper powder) content of 5
2% by weight, 40% by weight of natural graphite and 8% by weight of others. Other configurations are similar to those of the conventional one shown in FIGS. 4 and 5, and therefore, corresponding components are designated by the same reference numerals and description thereof is omitted.

A brush device 30 having such two brushes on the positive electrode side and one brush on the negative electrode side was mounted on a starter motor, and an engine starting test was conducted under the same conditions as in Example 1. The results obtained are shown in FIG. In FIG. 3, E is a line showing the progress of wear of each positive electrode side brush 16, and F is the progress of wear of the negative electrode side brush 31. As is clear from FIG. 4, the current per unit of the positive electrode side brush 16 is reduced, and the wear resistance is improved because the copper content of the negative electrode side brush 31 is small. It can be seen that the abrasion speed of the brush is almost the same on both sides, and the brush can be used 30,000 times or more.

Also in this Example 2, the copper content of the positive electrode side brush 16 is slightly changed centering on 60% by weight, and the copper content of the negative electrode side brush 31 is selected in the range of about 50 to 55% by weight, if necessary. Even if it does, the same effect is produced.

As described above, according to the second embodiment of the present invention, a starter motor having a larger current than that of the first embodiment can be dealt with by using the brush having the same size as that of the first embodiment, and the brush holding can be performed. Since only one frame is required, it is possible to further reduce the number of parts by standardizing the parts, and it is possible to use a starter motor over a wide current range in combination with a brush having the most suitable composition. Further, in the metal graphite brush, artificial graphite may be used as the graphite.

[0028]

As described above, according to the present invention, in the brush device having the same number of brushes on the positive electrode side and the negative electrode side, the positive electrode side brush has a lower copper content than the negative electrode side brush. In a brush device including a brush in which the number of side brushes is twice the number of negative side brushes, the copper content of the negative side brush is smaller than that of the positive side brush. The speed of wear of the brush can be made substantially the same, and the durability of the brush can be improved.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a comparison result of abrasion states of brushes in an engine starting test of a starter motor equipped with a brush device according to an embodiment of the present invention.

FIG. 2 is a plan view of a brush device showing another embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a comparison result of abrasion states of brushes in an engine starting test of a starter motor equipped with the brush device shown in FIG. 2 of the present invention.

FIG. 4 is a plan view showing a conventional brush device.

FIG. 5 is a side view showing a cutaway part of a starter motor equipped with a conventional brush device.

FIG. 6 is a characteristic diagram showing a current flowing through a starter motor in one test cycle.

FIG. 7 is a characteristic diagram showing a comparison result of abrasion states of brushes in an engine start test of a starter motor equipped with a conventional brush device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Starter motor 6 Rotating armature 8 Commutator 14 Brush holding frame on the positive side 16 Brush on the positive side (copper content 60% by weight) 21 Brush holding frame on the negative side 30 Brush device 31 Brush on the negative side (copper content 52% by weight) )

Claims (4)

[Claims] 1. A brush device for a starter motor, comprising the same number of brushes on the positive electrode side and on the negative electrode side in sliding contact with a commutator of the starter motor, wherein each brush is made of metal graphite containing copper, A brush device for a starter motor, characterized in that the copper content of the brush is lower than the copper content of the negative electrode side brush by weight percent. 2. The brush device for a starter motor according to claim 1, wherein the positive electrode side brush has a copper content of 50 to 55 weight percent and the negative electrode side brush has a copper content of about 60 weight percent. 3. A brush device for a starter motor, comprising a brush in which the number of brushes on the positive electrode side in sliding contact with the commutator of the starter motor is twice the number of brushes on the negative electrode side,
Each of the above brushes is made of metallic graphite containing copper,
A brush device for a starter motor, characterized in that the negative electrode side brush has a lower copper content in weight percent than the positive electrode side brush. 4. A brush device for a starter motor according to claim 3, wherein the negative electrode side brush has a copper content of 50 to 55 weight percent and the positive electrode side brush has a copper content of about 60 weight percent.