JP2010200572A - Rotary electric machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary electric machine (starter), capable of suppressing the damage of a brush 6, and greatly prolonging the service life of the brush 6. <P>SOLUTION: In a motor, two brushes 6 are juxtaposed in the axis direction to a commutator 5, and brush springs 8 are arranged at the two brushes 6, respectively. Moreover, in the brush 6 on the negative electrode side, a pigtail 6a is welded at a cut-and-raised piece 9a cut to be raised in the axial direction from a holder plate 9. In the two brushes 6 arranged in the axial direction to the commutator 5, both dimension and material can be changed. Thereby, supplied current can be regulated according to the intrinsic resistance of each brush 6. Moreover, in the two brush springs 8, the surface pressure of the commutator 5 and the brush 6 can be adjusted, by setting up spring loads properly to the two brushes 6, respectively, so that the supplied currents of the two brushes 6 are made nearly equal to each other. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rotating electrical machine including a commutator and a brush.

As a prior art, for example, there is a starter described in Patent Document 1. In this starter, a brush is arranged on the outer periphery in the radial direction of a commutator assembled in a cylindrical shape, and this brush is pressed against the outer peripheral surface of the commutator by a brush spring.
By the way, since the generation | occurrence | production of a commutation spark has a big influence on the lifetime by abrasion of a brush, in order to extend the lifetime of a brush, reduction of a commutation spark is essential. As a means for reducing this rectifying spark, for example, a technique is known in which two types of carbon materials having different resistances are stacked to form a two-layer brush. Further, when there is a demand for extending the brush life, there is a method of reducing the copper content of the brush and lengthening the brush in the radial direction or the axial direction with respect to the commutator.

JP-A-4-156249

However, when the copper content of the brush is reduced, there arises a problem that the output decreases due to an increase in electric resistance. Moreover, since the method of lengthening the brush in the radial direction with respect to the commutator is limited by the yoke diameter, there are many cases where the length cannot be made sufficient.
On the other hand, in the method of lengthening the brush in the axial direction with respect to the commutator, the pressing force of the brush spring decreases at both ends in the axial direction of the brush far from the load point of the brush spring, so that the entire brush cannot be pressed uniformly. As a result, the brush jumps at the segment step of the commutator surface and the rectification deteriorates, so that the brush wear is promoted and the brush may be damaged.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a rotating electrical machine that can suppress brush damage and improve the brush life.

(Invention according to Claim 1)
The present invention provides a rotation having a cylindrical commutator provided on one end of an armature shaft, a brush disposed on the outer periphery of the commutator, and a brush spring that presses the brush against the outer peripheral surface of the commutator. In the electric machine, a plurality of brushes are arranged in the axial direction with respect to the commutator, and a brush spring is arranged for each brush.
According to the above configuration, since the plurality of brushes arranged in the axial direction with respect to the commutator are not pressed by one brush spring, but each brush spring is arranged for each brush. It is transmitted uniformly throughout. As a result, since the brush can be prevented from jumping, deterioration of rectification can be suppressed, and damage to the brush can be suppressed. Further, by arranging a plurality of brushes in the axial direction with respect to the commutator, the current value supplied to each brush can be reduced, so that the wear of the brush can be suppressed and the brush life can be improved.

(Invention according to Claim 2)
The rotating electric machine according to claim 1, wherein the plurality of brushes arranged side by side in the axial direction with respect to the commutator have uniform dimensions and materials.
By unifying the standards (dimensions and materials) of multiple brushes, there is no need to use brushes with different standards, that is, there is no need to increase the types of brushes. It is possible to suppress an increase in cost associated with arranging them side by side.

(Invention according to claim 3)
The rotating electric machine according to claim 1, wherein the plurality of brushes arranged side by side in the axial direction with respect to the commutator have different dimensions and materials.
For example, when two brushes with uniform standards (dimensions and materials) are arranged side by side in the axial direction, the brush arranged on the armature side of the commutator (the one closer to the armature coil) is the commutator. Since the current flows more easily as the circuit resistance becomes smaller than the brush arranged on the side opposite to the armature (the far side from the armature coil), there is a possibility that the amount of wear of the two brushes is biased. On the other hand, by using brushes having different dimensions and materials according to the mounting position in the axial direction with respect to the commutator, it becomes possible to adjust the energization current according to the specific resistance of each brush. As a result, the circuit resistance depending on the mounting position of each brush can be made substantially equal, so that the uneven wear amount of each brush can be suppressed.

(Invention of Claim 4)
The rotary electric machine according to claim 2 or 3, wherein the brush spring arranged for each brush has a different spring load for each brush.
Since the surface pressure between the commutator and the brush increases when the pressing force (spring load) of the brush spring that presses the brush against the outer peripheral surface of the commutator is large or small, the energization of the brush The current increases. Therefore, in the present invention, the spring load is appropriately set for each brush so that the energization currents of the brushes are substantially equal, and the surface pressure between the commutator and the brush is adjusted to thereby reduce the wear of each brush. The amount of bias can be suppressed.
Also, by adjusting the spring load, the radial runout of the commutator can be adjusted.

(Invention according to claim 5)
The rotating electrical machine according to any one of claims 1 to 4, further comprising: a brush holder for holding a brush; and a metal holder plate to which the brush holder is fixed. The holder plate is cut in an axial direction. A raised and raised piece is provided, and a pigtail of a negative electrode brush arranged on a low potential side (ground side) with respect to the armature is welded to the raised piece.
According to the above configuration, the pigtail of the negative electrode side brush does not need to be welded to the surface of the holder plate, and is welded to the cut and raised pieces cut and raised in the axial direction from the holder plate. The lengths of the pigtails of the plurality of arranged brushes (negative electrode side brush) can be made equal. By making the lengths of the pigtails equal, it is not necessary to use brushes of different standards, and it is not necessary to increase the types of brushes.

Further, when the pigtail of the negative electrode side brush is directly welded to the surface of the holder plate, water may reach the welded portion of the pigtail along the surface of the holder plate when water is immersed inside the rotating electrical machine. In this case, the water adhering to the pigtail is transmitted to the brush by capillary action, and rusting may occur in the buried portion of the pigtail, leading to an increase in resistance.
On the other hand, the rotating electrical machine of the present invention cuts and raises the pigtail of the negative electrode side brush and welds it to the piece, so that a predetermined distance can be secured between the surface of the holder plate and the welded portion of the pigtail. In other words, the pigtail weld is away from the surface of the holder plate, so that even if water gets inside the rotating electrical machine, the moisture cuts and rises from the surface of the holder plate and reaches the pigtail weld through the piece. Can be suppressed. As a result, moisture is hardly transmitted to the brush through the pigtail, and it is possible to prevent an increase in resistance due to rusting in the pigtail embedded portion.

(Invention of Claim 6)
The present invention provides a rotation having a cylindrical commutator provided on one end of an armature shaft, a brush disposed on the outer periphery of the commutator, and a brush spring that presses the brush against the outer peripheral surface of the commutator. In the electric machine, the brush spring is a coil spring, and the brush has a length in the axial direction so that a plurality of coil springs can be arranged in the axial direction.
According to said structure, wear of a brush can be suppressed and the brush lifetime can be improved by lengthening the axial direction length of a brush and increasing a contact area with a commutator. Moreover, the whole brush can be uniformly pressed with respect to a commutator by arranging a plurality of coil springs (brush springs) side by side in the axial direction with respect to the brush having a long axial length. Thus, even if the length of the brush in the axial direction is increased, the pressing force of the coil spring does not decrease at both ends of the brush in the axial direction. Can be suppressed.

It is a general view including a partial cross section of a starter. (Example 1) which is sectional drawing which shows arrangement | positioning of the brush with respect to a commutator. It is an expanded view which shows the welding part of the pigtail of a negative electrode side brush. (Example 2) which is sectional drawing which shows arrangement | positioning of the brush with respect to a commutator.

  The best mode for carrying out the present invention will be described in detail by the following examples.

In the first embodiment, an example in which the rotating electrical machine of the present invention is applied to a starter 1 will be described.
As shown in FIG. 1, the starter 1 includes a motor 2 that generates rotational force, an electromagnetic switch 3 that turns on / off a current supplied from the battery to the motor 2, a pinion gear 4 that outputs the rotational force of the motor 2, and the like. After the pinion gear 4 is engaged with an engine ring gear (not shown), the rotational force of the motor 2 is transmitted from the pinion gear 4 to the ring gear, and the ring gear is rotated to start the engine. .
The motor 2 is a commutator motor that has a commutator 5 on one end side of the armature shaft, and is energized to the armature through a brush 6 that is in sliding contact with the outer peripheral surface of the commutator 5.

The commutator 5 is configured by arranging a plurality of segments (commutator pieces) molded in a resin member (not shown) in a cylindrical shape, and the resin member is fitted to one end side outer periphery of the armature shaft by press fitting or the like. And fixed. The plurality of segments are insulated from each other by a resin member, and each segment is connected to an armature coil (not shown).
The brush 6 is held by the brush holder 7 and is disposed on the outer periphery in the radial direction of the commutator 5, and is pressed against the outer peripheral surface of the commutator 5 by the brush spring 8. In the motor 2 of this embodiment, as shown in FIG. 2, two brushes 6 are arranged side by side in the axial direction (the left-right direction in the drawing) with respect to the commutator 5, and each of the two brushes 6 has a brush spring. 8 is arranged. 2 shows the brush 6 on the negative electrode side, the brush 6 on the positive electrode side also has two brushes 6 arranged side by side in the axial direction, like the negative electrode side, and each brush 6 has a brush spring 8. Needless to say, is arranged.

The brush holder 7 is made of resin, for example, and holds the two brushes 6 arranged side by side in the axial direction with respect to the commutator 5 so as to be movable in the radial direction with respect to the commutator 5. The brush holder 7 is fixed to a metal holder plate 9.
The holder plate 9 is disposed in contact with the end surface of the end frame 11 that closes the rear end of the motor yoke 10, and is fixed to the end frame 11 by tightening screws or the like. The holder plate 9 is provided with a rectangular cut-and-raised piece 9a cut and raised in the axial direction. As shown in FIG. 3, a pigtail 6a of the negative-side brush 6 is welded to the cut-and-raised piece 9a. (Reference numeral 6b in the figure is a welded portion of the pigtail 6a). Note that FIG. 3 is a drawing in which, for example, two sets of negative-side brushes 6 arranged at 90 ° different positions in the circumferential direction of the commutator 5 are developed on a plane. On the other hand, the positive brush 6 is connected to the M terminal 13 of the electromagnetic switch 3 through the motor lead wire 12 (see FIG. 1).

(Operation and Effect of Example 1)
In the motor 2 shown in the first embodiment, the two brushes 6 are arranged in the axial direction with respect to the commutator 5, and the brush springs 8 are respectively arranged on the two brushes 6. The pressing force is uniformly transmitted to the entire brush. Thereby, since the brush 6 does not incline with respect to the commutator 5 and the splashing of the brush 6 can be prevented, deterioration of the rectification can be suppressed and damage to the brush 6 can be avoided. Further, by arranging two brushes 6 in the axial direction with respect to the commutator 5, it is possible to reduce the value of the current supplied to each brush 6, so that the wear of the brush 6 can be suppressed and the life of the brush 6 is improved. it can.

  The two brushes 6 arranged in the axial direction with respect to the commutator 5 can be unified in size and material. In this case, since there is no need to increase the types of brushes 6, it is possible to suppress an increase in cost associated with using two brushes 6. However, the standards (dimensions and materials) of the two brushes 6 can be changed. For example, when two brushes 6 having the same dimensions and materials are arranged side by side in the axial direction, the brush 6 (the left brush 6 in FIG. 2) arranged on the armature side of the commutator 5 is rectified. Since the current flows more easily as the circuit resistance becomes smaller than the brush 6 disposed on the side opposite to the armature of the child 5 (the right brush 6 in FIG. 2), the wear amount of the two brushes 6 is biased. There is a fear. On the other hand, by using the brushes 6 having different dimensions and materials according to the axial mounting position with respect to the commutator 5, the energization current can be adjusted according to the specific resistance of each brush 6. As a result, the circuit resistances depending on the mounting positions of the two brushes 6 can be made substantially equal, so that it is possible to suppress the uneven wear amount of each brush 6.

  The two brush springs 8 can set different spring loads for the two brushes 6. That is, when the spring load is large and when the spring load is small, the surface pressure between the commutator 5 and the brush 6 increases when the spring load is large, and the energization current of the brush 6 increases. Therefore, by appropriately setting the spring loads for the two brushes 6 so that the energization currents of the two brushes 6 are substantially equal, the surface pressure between the commutator 5 and the brushes 6 is adjusted. It is also possible to suppress the uneven wear amount of the two brushes 6.

  Furthermore, the negative electrode side brush 6 disposed on the low potential side with respect to the armature is connected to the ground side via the holder plate 9, but the pigtail 6 a of the brush 6 is not welded to the surface of the holder plate 9. Since the pigtail 6a is welded to the cut and raised piece 9a cut and raised in the axial direction from the holder plate 9, the lengths of the pigtails 6a of the two brushes 6 can be made equal as shown in FIG. Further, when the pigtail 6 a of the brush 6 is welded to the surface of the holder plate 9, moisture may reach the welded portion of the pigtail 6 a along the surface of the holder plate 9 when water is generated inside the motor 2. . In this case, the water adhering to the pigtail 6a is transmitted to the brush 6 by capillary action, and rusting may occur in the buried portion of the pigtail 6a, leading to an increase in resistance.

  On the other hand, in the motor 2 of this embodiment, the pigtail 6a of the negative electrode side brush 6 is welded to the cut and raised piece 9a of the holder plate 9, so that the welded portion 6b of the pigtail 6a from the surface of the holder plate 9 (FIG. 3). A predetermined distance can be ensured. That is, since the welded portion 6b of the pigtail 6a is separated from the surface of the holder plate 9, even when water is immersed in the motor 2, the moisture is cut and raised from the surface of the holder plate 9 through the piece 9a and the pigtail 6a It can suppress reaching to the welding part 6b. As a result, moisture is hardly transmitted to the brush 6 through the pigtail 6a, and it is possible to prevent an increase in resistance due to rusting in the embedded portion of the pigtail 6a.

The second embodiment is an example in which the length of the brush 6 in the axial direction is increased and a plurality of brush springs 8 are disposed on the brush 6. Specifically, as shown in FIG. 4, two brush springs 8 (coil springs) are arranged for one brush 6 whose dimension in the axial direction (left-right direction in the drawing) is increased. In other words, the length of the brush 6 in the axial direction has a dimension that allows the two brush springs 8 to be arranged side by side in the axial direction.
Since the brush 6 of the present embodiment can increase the contact area with the commutator 5 by making the length in the axial direction longer than the single brush 6 shown in the first embodiment, the wear of the brush 6 can be suppressed. The life of the brush 6 can be improved.
Further, since the two brush springs 8 (coil springs) are arranged side by side in the axial direction with respect to the brush 6 having a longer axial length, the entire brush can be pressed uniformly against the commutator 5. Accordingly, even if the axial length of the brush 6 is increased, the pressing force of the brush spring 8 does not decrease at both ends of the brush 6 in the axial direction, so that the brush 6 is prevented from tilting or jumping with respect to the commutator 5. The deterioration of rectification and damage to the brush 6 can be suppressed.

(Modification)
In the first embodiment, an example in which two brushes 6 are arranged in the axial direction with respect to the commutator 5 has been described. However, the number of brushes 6 is not limited to two, and three or more brushes 6 are arranged in the axial direction. It is also possible to arrange a brush spring 8 for each brush 6.
Moreover, in Example 1 and 2, although the coil spring is used for the brush spring 8, a leaf | plate spring can also be used.

1 Starter (Rotating electric machine)
5 Commutator 6 Brush 6a Pigtail of Brush 7 Brush Holder 8 Brush Spring 9 Holder Plate 9a Cut and Raised Piece Provided on Holder Plate

Claims (6)

A cylindrical commutator provided on one end of the armature shaft;
A brush arranged on the outer periphery of the commutator;
In a rotating electrical machine having a brush spring that presses this brush against the outer peripheral surface of the commutator,
A rotating electrical machine comprising: a plurality of brushes arranged in an axial direction with respect to the commutator; and the brush springs arranged for each brush. In the rotating electrical machine according to claim 1,
A plurality of the brushes arranged side by side in the axial direction with respect to the commutator have individual dimensions and materials that are unified. In the rotating electrical machine according to claim 1,
The plurality of brushes arranged side by side in the axial direction with respect to the commutator are different in size and material from each other. In the rotating electrical machine according to claim 2 or 3,
The rotating electrical machine according to claim 1, wherein the brush spring disposed for each brush has a different spring load for each brush. In any one of the rotating electrical machines according to claims 1 to 4,
A brush holder for holding the brush;
It has a metal holder plate to which this brush holder is fixed,
The holder plate is provided with a cut and raised piece cut and raised in the axial direction,
A rotating electric machine characterized in that a pigtail of a negative electrode side brush arranged on a low potential side with respect to an armature is welded to the cut and raised piece. A cylindrical commutator provided on one end of the armature shaft;
A brush arranged on the outer periphery of the commutator;
In a rotating electrical machine having a brush spring that presses this brush against the outer peripheral surface of the commutator,
The brush spring is a coil spring,
The rotating electric machine according to claim 1, wherein the brush has a dimension in which an axial length can arrange the plurality of coil springs in an axial direction.

Images