JP4595674B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor having a commutator and a brush.

Conventionally, in an electric motor having a commutator and a brush, for example, as shown in FIG. 8, a plurality of grooves 120 are formed at substantially equal intervals on the surface (commutator surface) of the commutator 110 on which the brush 100 slides. A technique for improving the performance of an electric motor by stabilizing the contact state (sliding state) between the commutator 110 and the brush 100 is known (see Patent Documents 1 and 2).
JP 62-118732 A JP 2004-229352 A

However, in the above-described known technique, the sliding surface of the brush 100 that slides on the commutator surface also needs to be processed to be uneven. That is, it is necessary to process the uneven shape on the sliding surface of the brush 100 in advance in accordance with the uneven shape of the commutator surface. On the other hand, when the processing accuracy is poor, the contact state between the commutator 110 and the brush 100 may be deteriorated. Therefore, when processing the concavo-convex shape on the sliding surface of the brush 100, high processing accuracy is required, which causes an increase in processing cost and a factor of reducing productivity.
The present invention has been made based on the above circumstances, and its object is to stabilize the contact state (sliding state) between the commutator and the brush of the electric motor, reduce the processing cost, and improve the productivity. It is to provide a technology capable of improving the quality.

(Invention of Claim 1)
The present invention has a commutator provided in an armature and a brush that is disposed on the surface of the commutator and slides on the commutator surface by rotation of the armature. Each of which is provided with a plurality of recesses and protrusions, and the recesses and protrusions are alternately provided at a plurality of locations in a direction orthogonal to the circumferential direction of the commutator surface. The total length of the top surfaces of all the convex portions included in the sliding range of the brush in the direction orthogonal to the direction is L, and the brush sliding surface on the commutator surface When the width of the brush in the direction orthogonal to the sliding direction is B,
L / B ≦ 1/3 ……………… （1）
The relationship (1) is established.

  According to the above configuration, compared to the case where the commutator surface is not an uneven shape but smooth, the brush sliding surface (hereinafter referred to as the brush sliding surface) is adjusted before the commutator surface conforms to the shape of the commutator surface. The surface pressure at the convex portion provided on the commutator surface is three times or more of the moving surface. For this reason, even if the brush sliding surface is unprocessed (planar state), if the rotation operation is performed by continuous energization for a predetermined time (for example, about 1 minute), the energization current flows in a concentrated manner on the convex portion. As the brush sliding surface wears according to the shape of the portion, the shape of the brush sliding surface can be adjusted so as to match the uneven shape of the commutator surface. Therefore, even if there is no special processing on the brush sliding surface, the brush sliding can be made to match the irregular shape of the commutator surface by performing a rotation operation by continuous energization for a short time in the operation test before product shipment. The familiarity of the surface can be completed. As a result, since it is not necessary to process a highly accurate uneven shape on the brush sliding surface in advance, the processing cost can be reduced and the productivity can be improved.

Further, the invention according to claim 1 is characterized in that the top surface of the top surface of the convex portion provided on the commutator surface is rougher than the surface roughness of the portion other than the top surface. .
In this case, since the surface roughness of the top surface of the convex portion is rough, the initial wear of the brush sliding surface is promoted, so that the familiarity of the brush sliding surface can be completed in a shorter time.

(Invention of Claim 2 )
In the electric motor according to claim 1, the convex portion provided on the commutator surface has an inverted V shape in which a width in a direction orthogonal to the circumferential direction of the commutator surface gradually decreases toward the top surface, The top surface is pointed.
According to this configuration, since the surface pressure at the convex portion with respect to the brush sliding surface can be maximized, the familiarity of the brush sliding surface can be completed in a shorter time.

(Invention of Claim 3 )
The electric motor according to claim 1 or 2, wherein the commutator is formed in a cylindrical shape on an outer periphery of the armature shaft.
In this case, since the commutator surface has a cylindrical shape, a plurality of recesses and projections are provided alternately in the axial direction of the commutator surface.

(Invention of Claim 4 )
The electric motor according to claim 1 or 2, wherein the commutator is configured in a direction orthogonal to the armature axis.
In this case, since the commutator surface has a disk shape orthogonal to the armature axis, a plurality of recesses and projections are provided alternately in concentric circles around the armature axis.

(Invention of Claim 5 )
Any one of the electric motors described in claims 1 to 4 is a starter motor for starting the internal combustion engine.
Since the starter motor needs to generate a large starting torque in order to start the internal combustion engine, a large current is applied in a short time. Accordingly, when a rotation operation by continuous energization is performed, a large energization current flows intensively on the convex portion provided on the commutator surface, so that rotation operation by a short time continuous energization (for example, no load continuous for about 1 minute) It is possible to complete the familiarity of the brush sliding surface with respect to the irregular shape of the commutator surface.

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

The first embodiment is an example in which the electric motor of the present invention is applied to a starter motor for starting an internal combustion engine. FIG. 1 shows an armature 1 of the starter motor.
The starter motor has an armature 1 that is rotatably supported inside a field (a permanent magnet or a field coil) (not shown), and the armature 1 is generated by an electromagnetic force that acts between the field and the armature 1. It is a known DC motor that generates a rotational force.
The armature 1 includes an armature shaft 2, an armature core 3 that is serrated and fitted onto the outer periphery of the armature shaft 2, an armature coil 4 wound around the armature core 3, and an armature. The commutator 5 is provided at one end of the shaft 2.

The commutator 5 is configured by arranging a plurality of commutator pieces 50 held by the insulating material 6 in a cylindrical shape on the outer periphery of the armature shaft 2, and each commutator piece 50 is connected to the armature coil 4. They are mechanically and electrically connected. On the surface (commutator surface) of the commutator piece 50, as shown in FIG. 1, a plurality of concave portions 7 and convex portions 8 that make a round in the circumferential direction of the commutator 5 are formed. The concave portions 7 and the convex portions 8 are provided alternately and continuously in the axial direction of the commutator 5 (the horizontal direction in the figure), and the adjacent convex portions 8 and the convex portions 8 are provided at substantially equal intervals. .
A plurality of carbon brushes 9 are disposed on the outer periphery of the commutator 5 and are pressed against the commutator surface by a brush spring (not shown).

As shown in FIG. 2, a flat top surface having a predetermined width A in the axial direction is left on the convex portion 8 provided on the commutator surface.
Here, in the axial direction of the commutator surface, the total length A of the top surfaces of all the convex portions 8 included in the sliding range of the brush 9 is L (in FIG. 2, the sliding range of the brush 9 is within the sliding range). 5 is included, and therefore, when L = 5 × A) and the width of the brush 9 in the axial direction of the commutator surface (brush sliding width) is B, the following relationship (1) is satisfied. It is established.
L / B ≦ 1/3 ……………… （1）
That is, the total length L of the top surfaces A of all the convex portions 8 included in the sliding range of the brush 9 is set to 1/3 or less of the brush sliding width B.

(Effect of Example 1)
According to the above configuration, the sliding surface of the brush 9 is rectified as compared with the case where the commutator surface is smooth rather than uneven, that is, when the plurality of concave portions 7 and convex portions 8 are not formed on the commutator surface. Before the conformity to the shape of the child surface, the surface pressure at the convex portion 8 with respect to the sliding surface of the brush 9 sliding on the commutator surface by the rotation of the armature 1 becomes three times or more. For this reason, even if the brush sliding surface is unprocessed (planar state), if the rotation operation by continuous energization is performed, the energizing current flows in a concentrated manner on the convex portion 8, so the brush follows the shape of the convex portion 8. When the sliding surface is worn, the shape of the brush sliding surface can be adjusted so as to match the uneven shape of the commutator surface.

It should be noted that the time until the brush sliding surface is adapted from the flat state to match the concave and convex shape of the commutator surface (hereinafter referred to as the familiarization completion time) is the magnitude of the energizing current and the convex portion 8 with respect to the brush sliding surface. Depends on the surface pressure. Therefore, if the magnitude of the energizing current is the same, the higher the surface pressure at the convex portion 8 with respect to the brush sliding surface, in other words, the top of all the convex portions 8 included in the sliding range of the brush 9. The shorter the total length L of the surfaces, the shorter the familiarization time of the brush shape.
According to the experimental data, as shown in FIG. 3, the total length L of the top surfaces of all the convex portions 8 included in the sliding range of the brush 9 is 1 / B of the brush sliding width B. If the relationship of (1) or less is established, the familiarity of the brush shape is completed in a no-load continuous energization time of 1 minute or less.

  By the way, the starter motor to which the electric motor of the present invention is applied is energized with a large current in order to generate a rotational force necessary for starting the internal combustion engine. There is a fear. Therefore, it is desirable to shorten the no-load continuous energization time as much as possible. On the other hand, in the electric motor described in the first embodiment, the total length L of the top surfaces of all the convex portions 8 included in the sliding range of the brush 9 is 1 / of the brush sliding width B. 3 or less, that is, since the relationship (1) is established, the no-load continuous energization time can be suppressed to 1 minute or less.

As a result, even if there is no special processing on the brush sliding surface in advance, the commutator surface uneven shape can be obtained simply by performing a rotation operation by continuous energization (about 1 minute) for a short time in the operation test before product shipment. The familiarity of the brush sliding surface with respect to can be completed. As a result, since it is not necessary to process a highly accurate uneven shape on the brush sliding surface in advance, the processing cost can be reduced and the productivity can be improved.
Moreover, since the no-load continuous energization time can be suppressed to 1 minute or less, the starter motor is not heated abnormally, and the familiarity of the brush shape can be completed safely and in a short time.

FIG. 4 is a half sectional view of the armature 1 according to the second embodiment, and FIG. 5 is an enlarged sectional view showing the uneven shape of the commutator surface.
The armature 1 shown in the second embodiment is configured such that the commutator 5 is substantially orthogonal to the armature shaft 2 as shown in FIG. Specifically, a part of the armature coil 4 taken out from the slot 3 a of the armature core 3 in the axial direction is arranged substantially in parallel with the end face of the armature core 3 and used as the commutator piece 50. .

  The armature coil 4 has the same number of lower layer coil bodies 40 and upper layer coil bodies 41 as the number of slots 3 a of the armature core 3, and the linear portion 40 a of the lower layer coil body 40 and the linear portion 41 a of the upper layer coil body 41. Are inserted into the slot 3a in a two-layer state and assembled into the armature core 3, and the end of the lower layer coil body 40 and the end of the upper layer coil body 41 taken out from the different slots 3a are joined together Is done.

The upper layer coil body 41 is provided with a coil end portion 41b extending radially inward from one end of the linear portion 41a inserted into the slot 3a substantially parallel to the end face of the armature core 3, and the coil end portion 41b is a commutator piece. 50 is used.
A carbon brush 9 is in contact with the surface (commutator surface) of the commutator piece 50 from the axial direction and is pressed against the commutator surface by a brush spring (not shown).
A plurality of concave portions 7 and convex portions 8 are formed concentrically around the armature shaft 2 on the outer side surface in the axial direction of the coil end portion 41b forming the commutator surface. The concave portions 7 and the convex portions 8 are provided alternately and continuously in the radial direction (the vertical direction in the figure) of the commutator surface, and the adjacent convex portions 8 and the convex portions 8 are provided at substantially equal intervals. Yes. Further, as shown in FIG. 5, a flat top surface having a predetermined width A in the radial direction of the commutator surface is left on the convex portion 8.

Here, in the radial direction of the commutator surface, the total length A of the top surfaces A of all the convex portions 8 included in the sliding range of the brush 9 is L (in FIG. 5, the sliding range of the brush 9 is within the sliding range). 5 is included, and when L = 5 × A) and the width of the brush 9 in the radial direction of the commutator surface (brush sliding width) is B, the following relationship (1) is satisfied. It is established.
L / B ≦ 1/3 ……………… （1）
That is, the total length L of the top surfaces A of all the convex portions 8 included in the sliding range of the brush 9 is set to 1/3 or less of the brush sliding width B.

(Effect of Example 2)
The electric motor shown in the second embodiment is different from the first embodiment only in the configuration of the commutator 5, and is provided with a plurality of concave portions 7 and convex portions 8 on the commutator surface so that the brush shape conforms to the concave and convex shapes. The same is true. That is, as in the first embodiment, since the relationship (1) is established, even if there is no special processing on the brush sliding surface in advance, a short-time continuous energization ( Only by performing the rotation operation by about 1 minute), the familiarity of the brush sliding surface with the uneven shape of the commutator surface can be completed. As a result, since it is not necessary to process a highly accurate uneven shape on the brush sliding surface in advance, the processing cost can be reduced and the productivity can be improved. Moreover, since the no-load continuous energization time can be suppressed to 1 minute or less, the starter motor is not heated abnormally, and the familiarity of the brush shape can be completed safely and in a short time.

FIGS. 6 and 7 are enlarged cross-sectional views showing the uneven shape of the commutator surface.
In Example 3, in the cylindrical commutator 5 described in Example 1 and the face-type commutator 5 described in Example 2, the shape of the convex portion 8 is as shown in FIGS. Further, it has an inverted V-shape that gradually narrows toward the tip of the convex portion 8, and the tip of the convex portion 8 is pointed. That is, the width A of the top surface of the convex portion 8 described in the first and second embodiments is in a state as close as possible to “0”.
According to this configuration, since the surface pressure at the convex portion 8 with respect to the brush sliding surface can be further increased, the familiarity of the brush sliding surface with respect to the uneven shape of the commutator surface is completed in a shorter time (less than 1 minute). be able to.

The fourth embodiment is characterized in that the surface roughness of the top surface of the convex portion 8 provided on the commutator surface is formed to be rougher than the surface roughness of the portion other than the top surface.
In this case, since the surface roughness of the top surface of the convex portion 8 is rough, the initial wear of the brush sliding surface is promoted, so the brush sliding surface becomes more familiar to the uneven shape of the commutator surface in a shorter time. Can be completed.

(Modification)
In Example 1, although the example which applied the electric motor of this invention to the starter motor was demonstrated, it is not limited to a starter motor, It can apply widely to the electric motor which has the commutator 5 and the brush 9. FIG.
The electric motor described in the second embodiment uses a part of the armature coil 4 (coil end 41b of the upper layer coil body 41) as the commutator piece 50. However, the commutator piece 50 is the armature coil 4. It is also possible to configure with a separate member.

(Example 1) which is a half sectional view of the armature used for a starter motor. FIG. 3 is an enlarged cross-sectional view illustrating the uneven shape of the commutator surface according to the first embodiment. It is a graph which shows the familiarization completion time of a brush sliding surface. (Example 2) which is a semi-sectional view of the armature used for a starter motor. FIG. 6 is an enlarged cross-sectional view illustrating a concavo-convex shape of a commutator surface according to a second embodiment. FIG. 6 is an enlarged cross-sectional view illustrating a concavo-convex shape of a commutator surface according to Example 3. FIG. 6 is an enlarged cross-sectional view illustrating a concavo-convex shape of a commutator surface according to Example 3. It is an enlarged view which shows the uneven | corrugated shape of the commutator surface which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Armature 2 Armature shaft 5 Commutator 7 Concave part 8 Convex part 9 Brush A Width of top surface of convex part B Brush sliding width

Claims (5)

A commutator provided in the armature;
A brush arranged on the surface of the commutator (referred to as a commutator surface) and sliding on the commutator surface by rotation of the armature;
The commutator surface is provided with recesses and projections that make one round in the circumferential direction, and the recesses and projections are alternately provided at a plurality of locations in a direction orthogonal to the circumferential direction of the commutator surface. Because
L is the total length of the top surfaces of all the convex portions included in the sliding range of the brush in a direction perpendicular to the circumferential direction of the commutator surface;
In the sliding surface of the brush that slides on the commutator surface, when the width of the brush in the direction orthogonal to the sliding direction of the brush is B,
L / B ≦ 1/3 ……………… （1）
The relationship of (1) above is established ,
The electric motor according to claim 1, wherein the top portion of the convex portion provided on the commutator surface is formed such that the surface roughness of the top surface is rougher than the surface roughness of a portion other than the top surface . The electric motor according to claim 1,
The convex portion provided on the commutator surface has an inverted V shape in which a width in a direction orthogonal to a circumferential direction of the commutator surface is gradually narrowed toward the top surface, and the top surface is pointed. motor, characterized in that is. In the electric motor according to claim 1 or 2,
The commutator is configured in a cylindrical shape on an outer periphery of an armature shaft . In the electric motor according to claim 1 or 2 ,
The commutator is configured in a direction orthogonal to the armature axis. One of the motor according to claim 1-4, the electric motor, which is a starter motor for starting the internal combustion engine.

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