JP2005304257A - Rotating motor, motor for electric power steering, and manufacturing method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotating motor, a motor for electric power steering and a manufacturing method for the same, capable of forming a carbon film having a uniform thickness on the outer peripheral surface of a commutator, without requiring a special mechanism and component, and shortening a manufacturing time by shortening a time for running-in. <P>SOLUTION: This DC motor includes the commutator 11 provided at a rotatably supported armature, and a brush 18 of which the top 21 is brought into slide-contact with the peripheral surface of the commutator 11 when the rear end is energized by a coil spring. The running-in is performed for the DC motor immediately after assembling by supplying a load current and then supplying a non-load current. The carbon film 16 is formed on the outer peripheral surface of the commutator 11 in the running-in by supplying the load current, and the thickness of the carbon film 16 is made uniform in the circumferential direction by the running-in supplying the non-load current. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a rotary electric motor, and more particularly to a method of running-in that improves the sliding property between a commutator and a brush provided in the rotary electric motor.

  Generally, in a DC motor immediately after assembly, the sliding state between the brush and the commutator is not stable, and sliding noise is generated or the commutation becomes unstable as the commutator rotates. Therefore, conventionally, in a DC motor immediately after assembly, a running-in operation is performed in which a relatively small current is applied to rotate the armature to stabilize the sliding state between the brush and the commutator. However, in recent years, it has been desired to reduce the time required for the break-in operation from the viewpoint of shortening the manufacturing time.

  As a method for reducing the time required for the break-in operation while stabilizing the sliding state between the brush and the commutator, there is a method of forming a carbon film on the outer peripheral surface of the commutator. As a method for forming the carbon film, there are a method in which the carbon film is formed in the assembly process of the DC motor, and a method in which the carbon film is formed during the break-in operation after assembly.

  As a method of forming a carbon film in the assembly process, for example, there is a method of manufacturing a rotary electric motor disclosed in Patent Document 1. In this method, first, a basic structure of a DC motor is formed by assembling an armature having a commutator, a brush device having a brush made of carbon, a bracket, and the like in a yoke. Thereafter, the armature is rotated from outside while energizing the brush. Thereby, a brush and a commutator will be slidably contacted in an energized state. When the brush and the commutator are in sliding contact with each other, the brush is worn, and the carbon of the worn brush adheres to the outer peripheral surface of the commutator to form a carbon film. Patent Document 1 also discloses a method in which an armature is rotatably supported by an external mechanism, and a carbon film is formed by rotating the armature with the treated graphite rod in contact with the commutator. Yes. By forming the carbon film as described above, the time required for the break-in operation is shortened.

  Another method for forming a carbon film in the assembly process is a method for manufacturing a rotary motor disclosed in Patent Document 2. In this method, the carbon film is formed on the commutator using a familiar brush for forming a carbon film made of copper and carbon, which is different from the brush for performing the rectification. This conforming brush is pressed toward the outer peripheral surface of the commutator provided in the armature. Then, the armature is rotated without energization, and the conforming brush and the outer peripheral surface of the commutator slide. When the familiar brush and the outer peripheral surface of the commutator slide, a carbon film is formed on the outer peripheral surface of the commutator. Thereafter, the familiar brush is removed, and the armature is accommodated in the space formed by the yoke and the bracket to complete the DC motor. By forming the carbon film in this manner, the time required for the break-in operation is shortened as in Patent Document 1.

As a method of forming the carbon film during the break-in operation after assembly, there is a method of supplying a large current to the commutator through a brush in order to perform the break-in operation in a short time. According to this method, the time for the break-in operation is shortened by forming the carbon film in a short time with the current supplied to the commutator.
JP 2003-250250 A JP 2003-134746 A

  However, in the method for manufacturing a rotary electric motor disclosed in Patent Document 1 and Patent Document 2, the time required for break-in operation is reduced by forming a carbon film on the outer peripheral surface of the commutator in the assembly process. However, since the process for forming the carbon film is added, it is difficult to expect the overall manufacturing time to be shortened. In addition, when forming the carbon film, a mechanism for rotating the armature from the outside, a mechanism for rotatably supporting the armature, and the like are required. Therefore, a separate mechanism is not provided for forming the carbon film. Don't be.

  Moreover, in the manufacturing method of the rotary motor disclosed in Patent Document 2, a familiar brush for forming a carbon film on the outer peripheral surface of the commutator is required in addition to the brush for commutation. Accordingly, the number of parts required for manufacturing the direct current motor increases and the manufacturing cost increases. In addition, the familiar brush must be removed after the carbon film is formed on the outer peripheral surface of the commutator, which increases the number of manufacturing steps and increases the manufacturing time.

  On the other hand, in the method of forming the carbon film during the running-in operation, a large load current is supplied to the DC motor in order to form the carbon film in a short time. Since the carbon film formed by this large load current has a non-uniform thickness in the circumferential direction, the sliding state of the brush may be deteriorated.

  The present invention has been made in view of such circumstances, and its purpose is to reduce the time required for the break-in operation, thereby reducing the manufacturing time, and without requiring a special mechanism and parts. An object of the present invention is to provide a rotary electric motor, an electric power steering motor, and a manufacturing method thereof that can form a carbon film having a uniform thickness on the outer peripheral surface of the child.

  In order to solve the above-described problem, the invention according to claim 1 is directed to a commutator provided in a rotatably supported armature, and biased toward the commutator by a biasing means, and the tip portion is A brush that is in sliding contact with the outer circumferential surface of the commutator, and the commutator is formed by a first running-in operation in which a load current is applied to the outer circumferential surface and a second running-in operation in which a no-load current is supplied. Carbon film.

According to a second aspect of the present invention, in the rotary electric motor according to the first aspect, the tip of the brush is sharpened so as to narrow the width of the commutator in the axial direction.
According to a third aspect of the present invention, in the rotary electric motor according to the first or second aspect, the tip of the brush is formed in an arc shape along the outer peripheral surface of the commutator, and the commutator And a sliding surface having a radius of curvature larger than the radius of.

  According to a fourth aspect of the present invention, there is provided a commutator provided in an armature that is rotatably supported, and a biasing means that biases the commutator toward the commutator so that a tip portion slides on the outer peripheral surface of the commutator. A method of manufacturing a rotary electric motor including a brush to be contacted, comprising: a break-in process for performing a break-in operation for blending the outer peripheral surface of the commutator and the tip of the brush, wherein the break-in process includes a load A carbon film forming step of forming a carbon film on the outer peripheral surface of the commutator by energizing an electric current and operating the rotary motor, and an operation of the carbon film by energizing a no-load current and operating the rotary electric motor. And a carbon film homogenizing step for making the thickness uniform.

According to a fifth aspect of the present invention, in the method for manufacturing a rotary electric motor according to the fourth aspect, the tip of the brush is formed to be sharpened so as to narrow the width in the axial direction of the commutator.
According to a sixth aspect of the present invention, in the method of manufacturing a rotary electric motor according to the fourth or fifth aspect, the tip of the brush is formed in an arc shape along the outer peripheral surface of the commutator, A sliding surface having a radius of curvature larger than the radius of the commutator is provided.

According to a seventh aspect of the present invention, an electric power steering motor is manufactured using the method for manufacturing a rotary electric motor according to any one of the fourth to sixth aspects.
(Function)
According to the first and fourth aspects of the invention, the carbon film formed on the outer peripheral surface of the commutator is formed by a break-in operation. No mechanism and parts for film formation are required. The break-in operation is performed by first applying a load current to the rotary motor and then supplying a no-load current. In a break-in operation in which a load current is applied, since wear of the brush is promoted, a carbon film is easily formed on the outer peripheral surface of the commutator, and the carbon film can be formed in a short time. In the running-in operation in which no-load current is applied, the thickness of the carbon film formed by applying the load current and performing the running-in operation is made uniform. Therefore, the running-in operation of the rotary motor is performed by supplying the load current, and then supplying the no-load current, thereby shortening the running-in time and shortening the manufacturing time, and uniforming the outer peripheral surface of the commutator. A carbon film with a sufficient thickness can be formed to stabilize the sliding state between the brush and the commutator.

  According to invention of Claim 2, 5, since the front-end | tip part of a brush is sharpened so that the width | variety of the axial direction of a commutator may be narrowed, the area which slidably contacts with the outer peripheral surface of a commutator is obtained. narrow. Therefore, since the biasing load by the biasing means is concentrated on the tip portion having a narrow axial width, the tip portion of the brush is more easily worn, and a carbon film is easily formed on the outer peripheral surface of the commutator. As a result, the carbon film is formed earlier, and the time required for the break-in operation is further shortened. In addition, since the area where the brush slides on the outer peripheral surface of the commutator is small, the tip of the brush and the outer peripheral surface of the commutator are easily compatible.

  According to invention of Claim 3, 6, the front-end | tip part of a brush is formed in circular arc shape along the outer peripheral surface of a commutator, and is a sliding surface which has a curvature radius larger than the radius of this commutator. Therefore, the tip of the brush and the outer peripheral surface of the commutator are in sliding contact with each other at one point on the sliding surface in the circumferential direction. Accordingly, since the biasing load by the biasing means is concentrated at one point in the circumferential direction, the tip of the brush is more easily worn, and a carbon film is more easily formed on the outer peripheral surface of the commutator. Further, in the case of the inventions according to claims 2 and 5, since the area where the commutator is in sliding contact with the commutator in the axial direction is small at the front end of the brush, wear of the front end is further promoted, and the commutator is further improved. It is easy to form a carbon film on the outer peripheral surface. As a result, the carbon film is formed more quickly, and the time required for the break-in operation is further reduced. In addition, since the area where the brush contacts the commutator is small, the tip of the brush and the outer peripheral surface of the commutator are easily compatible.

  According to the seventh aspect of the invention, the electric power steering motor is formed with the effects of the fourth to sixth aspects, the sliding state between the brush and the commutator is stabilized, and the manufacturing time is short. Is obtained.

  According to the present invention, the manufacturing time is shortened by shortening the time required for the break-in operation, and a carbon film having a uniform thickness is formed on the outer peripheral surface of the commutator without requiring a special mechanism and parts. The rotary electric motor, the electric power steering motor, and the manufacturing method thereof can be provided.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, the configuration of the DC motor 1 of the present embodiment will be described. FIG. 1 shows a DC motor 1 as a rotary motor. The DC motor 1 is an electric power steering motor used in a so-called power steering device (not shown), and is attached to a steering column (not shown).

  The DC motor 1 is accommodated in a space surrounded by a bottomed cylindrical yoke housing 2, an end frame 3, a magnet 4 fixed to the inner peripheral surface of the yoke housing 2, and the yoke housing 2 and the end frame 3. Armature 5 and brush device 6 are provided.

  The end frame 3 is formed in a substantially disk shape, and a central hole 3a is formed at the center thereof. Such an end frame 3 is fixed to the yoke housing 2 with screws 7 so as to close the opening of the yoke housing 2.

  The armature 5 includes a rotating shaft 8, a core 9 fixed to the rotating shaft 8, a winding 10 wound around the core 9, and a commutator 11 fixed to the rotating shaft 8 on the end frame 3 side. And. The rotating shaft 8 is supported by a bearing 12 provided at the upper end at the center of the bottom of the yoke housing 2 and rotated at a lower end by a bearing 13 fixed to the inner periphery of the central hole 3a of the end frame 3. Held possible. Incidentally, the lower end side of the rotating shaft 8 protrudes outside from the central hole 3a while being rotatably supported by the bearing 13. A substantially cylindrical joint 14 is fixed to the protruding lower end portion of the rotating shaft 8. A joint hole 14a is formed in the joint 14, and an upper end portion of a driven shaft 15 (a steering shaft in this embodiment) of a driven device (not shown) is press-fitted and fixed in the joint hole 14a.

  The commutator 11 has a substantially cylindrical shape, and is provided with a plurality of segments 11a on the outer peripheral surface thereof. The winding 10 is connected to each segment 11a. A carbon film 16 made of carbon is formed on the outer peripheral surface of the commutator 11, that is, the outer surface of the segment 11a. The carbon film 16 is formed on a portion where a brush 18 described later comes into sliding contact.

  The brush device 6 is disposed on the end frame 3 at a position adjacent to the commutator 11. As shown in FIG. 2, the brush device 6 includes a brush holder 17, a brush 18, and a coil spring 19 as an urging means.

  The brush holder 17 has a bottomed cylindrical shape. The brush holder 17 is disposed with the opening thereof facing the commutator 11 and is fixed to the end frame 3 with screws 20 (see FIG. 1). A brush 18 is accommodated in the brush holder 17.

  The brush 18 is made of carbon and copper. As shown in FIG. 3, the brush 18 has a substantially rectangular parallelepiped shape. As for the front-end | tip part 21 of the brush 18, the surface facing the outer peripheral surface of the commutator 11 is comprised from the sliding surface 21a and the taper surface 21b. The sliding surface 21 a is formed on the lower end side in the axial direction of the commutator 11 at the tip portion 21. As shown in FIG. 4, the sliding surface 21 a is formed in an arc shape along the outer peripheral surface of the commutator 11, and is formed in an arc shape having a radius of curvature R <b> 2 larger than the radius R <b> 1 of the commutator 11. . As shown in FIG. 2, the tapered surface 21 b is inclined so as to gradually move away from the outer peripheral surface of the commutator 11 from the upper end portion of the sliding surface 21 a toward the upper side in the axial direction of the commutator 11. . That is, the tip 21 is formed to be sharpened so as to narrow the width of the commutator 11 in the axial direction. Such a brush 18 is urged by a coil spring 19 disposed in a compressed state between a rear end portion 22 of the brush 18 and a bottom portion 17a of the brush holder 17, as shown in FIG. The tip portion 21 is in sliding contact with the outer peripheral surface (segment 11a) of the commutator 11. At this time, the brush 18 is inclined in the brush holder 17 so as to keep the rear end portion 22 away from the end frame 3. That is, the tip portion 21 of the brush 18 is in sliding contact with the outer peripheral surface of the commutator 11 at the upper end of the sliding surface 21a in the axial direction, and is in sliding contact with the outer peripheral surface at one point on the sliding surface 21a in the circumferential direction.

  A pigtail 24 is connected to the upper surface 23 of the brush 18. As shown in FIG. 1, a power feeding unit 25 is assembled to the end frame 3. The power supply unit 25 supplies power to the brush 18 from the outside via the pigtail 24. Then, when power is supplied from the power supply unit 25 to the armature 5 via the brush 18 and the commutator 11, the armature 5 rotates and the rotating shaft 8 rotates.

Next, a method for manufacturing the DC motor 1 configured as described above will be described.
First, the armature 5 including the commutator 11, the brush device 6, the end frame 3, and the like are assembled to the yoke housing 2 to form the DC motor 1. At this time, the carbon film 16 is not formed on the outer peripheral surface of the commutator 11. The DC motor 1 of the present embodiment is, for example, a DC motor having a no-load current 1 [A], a no-load rotation speed 2000 [rpm], a binding torque 10 [Nm], and a binding current 100 [A].

  Next, a break-in operation is performed with the assembled DC motor 1 (break-in process). This step includes a carbon film forming step for supplying a load current to the DC motor 1 and a carbon film equalizing step for supplying a no-load current to the DC motor 1 thereafter.

  In the carbon film forming step, the load current supplied to the DC motor 1 is the same current as the current supplied to the DC motor 1 when the maximum load applied when the DC motor 1 is used. In the present embodiment, the load current is set to 50 [A], which is a substantially central value between the no-load current 1 [A] and the constraint current 100 [A]. When such a load current is applied to the DC motor 1 to perform a break-in operation (first break-in operation), the tip 21 of the brush 18 is worn as shown in FIG. A carbon film 16 is formed on the outer peripheral surface of the commutator 11 by adhering to the outer peripheral surface of the commutator 11. At this time, since a large current is supplied to the DC motor 1, the wear of the tip portion 21 of the brush 18 is promoted, and the carbon film 16 formed on the outer peripheral surface of the commutator 11 is formed in a short time. .

  The DC motor 1 after the completion of the carbon film forming process is supplied with a no-load current to perform the carbon film homogenizing process. In the carbon film forming step, since the DC motor 1 is operated by supplying a large value of load current, the thickness of the carbon film 16 formed on the outer peripheral surface of the commutator 11 becomes uneven in the circumferential direction. ing. Therefore, the thickness of the carbon film is made uniform in the circumferential direction by conducting a break-in operation (second break-in operation) by applying a no-load current. In the carbon film homogenization step, the no-load current supplied to the DC motor 1 is 1 [A] in the present embodiment. Further, the DC motor 1 is operated at a high speed rotation by applying a maximum voltage among the voltages applied when the DC motor 1 is used or a voltage at a limit rotational speed. When the running-in operation is performed with the DC motor 1 under such conditions, the formation of the carbon film 16 is suppressed because the value of the supplied current is small, and the tip portion 21 (sliding surface 21a) of the brush 18 and the commutator. 11 outer peripheral surfaces are mechanically accustomed. As a result, the convex portion of the carbon film 16 whose thickness is not uniform in the circumferential direction is scraped off, and the thickness of the carbon film 16 is uniformed in the circumferential direction. When the carbon film forming step is completed, the DC motor 1 is completed.

  With respect to the DC motor 1 manufactured by the above manufacturing method, the result of measuring the magnetic sound is shown in FIG. 6, and the result of measuring the sliding sound by the brush 18 is shown in FIG. In FIG. 6, the magnetic sound is measured by operating the DC motor 1 under the conditions of a load current of 10 [A] and a rotational speed of 1000 [rpm]. In FIG. 7, the sliding sound by the brush 18 is measured by operating the DC motor 1 under the conditions of no-load current 1 [A], applied voltage 11 [V], and rotation speed 2000 [rpm]. As shown in FIG. 6, the magnetic noise of the DC motor 1 is improved by reducing the value when the running-in operation is performed by supplying a load current immediately after assembly. Further, even if the running-in operation is performed by supplying a no-load current, the improved value is maintained by conducting the running-in operation by supplying a load current. Therefore, it can be seen that the state in which the magnetic sound is improved is maintained by performing the carbon film homogenization process after the carbon film formation process. Further, as shown in FIG. 7, the sliding sound by the brush 18 becomes large when the running-in operation is performed by applying a load current to the DC motor 1 immediately after assembly. However, when the running-in operation is performed by further applying a no-load current, the sliding sound by the brush 18 is improved to a small value that is the same as or less than that of the DC motor 1 immediately after assembly. Therefore, it can be seen that the sliding sound by the brush 18 is reduced and improved by performing the carbon film homogenizing process after the carbon film forming process.

  8 and 9 show the results of measuring the magnetic sound and the sliding sound by the brush 18 for a DC motor manufactured by performing only the running-in operation in which the load current is applied. FIGS. 10 and 11 show magnetic noise and sliding sound generated by the brush 18 with respect to a DC motor manufactured by conducting a running-in operation by applying a no-load current and then conducting a running-in operation by applying a load current. The measurement results are shown. 8 and 10, the magnetic sound is measured by operating a DC motor under conditions of a load current of 10 [A] and a rotational speed of 1000 [rpm]. 9 and 11, the sliding sound by the brush 18 is measured by operating a DC motor under the conditions of no-load current 1 [A], applied voltage 11 [V], and rotation speed 2000 [rpm]. Yes.

  When only the running-in operation in which the load current is applied is performed, the magnetic sound is improved as shown in FIG. 8 by performing the running-in operation. However, the sliding sound caused by the brush 18 as shown in FIG. The value increases and gets worse. In addition, when the running-in operation is performed by supplying a load current after conducting a running-in operation with no-load current, the magnetic noise is improved as shown in FIG. 10, but as shown in FIG. In addition, it can be seen that the sliding sound by the brush 18 is getting worse. From the above measurement results, in order to improve the magnetic sound and the sliding sound by the brush 18, it is optimal that the break-in operation is performed by supplying a load current and then a non-load current. Understand.

As described above, the present embodiment has the following effects.
(1) Since the carbon film 16 formed on the outer peripheral surface of the commutator 11 is formed during the break-in operation, a process only for forming the carbon film 16 is not required, and the carbon film shape 16 is separately formed. The configuration and parts are not required. The break-in operation is performed by first applying a load current to the DC motor 1 and then supplying a no-load current. In a break-in operation (carbon film forming step) in which a load current is applied, wear of the tip 21 of the brush 18 is promoted in order to supply a large current, and the carbon film 16 is formed on the outer peripheral surface of the commutator 11. Therefore, the carbon film 16 can be formed in a short time. In a running-in operation in which a no-load current is applied, the current that is applied is small, and the DC motor 1 is rotated at high speed. Therefore, the thickness of the carbon film 16 formed in the carbon film forming process can be made uniform. Accordingly, the manufacturing time is shortened by shortening the time required for the break-in operation, and the carbon film 16 having a uniform thickness is formed on the outer peripheral surface of the commutator 11 without requiring a special mechanism and parts. Can do. By forming such a carbon film 16, the sliding state between the brush 18 and the commutator 11 can be stabilized.

  (2) The tip 21 is formed of a sliding surface 21a and a tapered surface 21b. That is, since the tip 21 of the brush 18 is formed to be sharpened so as to narrow the width of the commutator 11 in the axial direction, the area in sliding contact with the outer peripheral surface of the commutator is small. Therefore, since the biasing load by the coil spring 19 is concentrated on the sliding surface 21a formed with a narrow axial width, the tip portion 21 of the brush 18 is more easily worn, and the outer peripheral surface of the commutator 11 is carbonized. The film 16 is easily formed. As a result, the carbon film 16 is formed earlier, and the time required for the break-in operation is further shortened. Further, since the area where the brush 18 is in sliding contact with the outer peripheral surface of the commutator 11 is small, the tip portion 21 of the brush 18 and the outer peripheral surface of the commutator 11 are easily compatible.

  (3) The tip portion 21 is formed along the outer peripheral surface of the commutator 11, and includes a sliding surface 21a having a curvature radius R2 larger than the radius R1 of the commutator. The tip 21 and the outer peripheral surface of the commutator 11 are in sliding contact with each other at one point on the sliding surface 21a in the circumferential direction. Therefore, since the biasing load by the coil spring 19 is concentrated at one point in the circumferential direction, the tip 21 of the brush 18 is more easily worn, and the carbon film 16 is more easily formed on the outer peripheral surface of the commutator 11. In particular, in the present embodiment, the tip portion 21 is formed to be sharpened so as to narrow the width of the commutator 11 in the axial direction, so that the area of the tip portion 21 that is in sliding contact with the outer peripheral surface of the brush 18 is further narrowed. Furthermore, wear of the tip 21 is promoted. As a result, the carbon film 16 can be formed more quickly, and the time required for the break-in operation can be further reduced. Further, since the area in which the brush 18 is in sliding contact with the outer peripheral surface of the commutator 11 is narrower, the tip portion 21 of the brush 18 and the outer peripheral surface of the commutator 11 are more easily adapted.

  (4) In the break-in process, after performing a carbon film forming process in which a load current is applied to perform a break-in operation, a carbon film homogenizing process in which a no-load current is applied to perform a break-in operation is performed. Therefore, the carbon film 16 is quickly formed by conducting a running-in operation with a load current applied, and the convex portion of the carbon film 16 formed in the carbon film forming process by carrying out a running-in operation with a no-load current applied. And the thickness of the carbon film 16 is uniformly re-formed in the circumferential direction. By performing the break-in operation in this order, the magnetic sound and the sliding sound by the brush 18 can be improved.

In addition, you may change embodiment of this invention as follows.
In the above embodiment, the tip 21 of the brush 18 is composed of the sliding surface 21a and the tapered surface 21b, but it may be configured as shown in FIGS. The brush 30 shown in FIG. 12 has a substantially rectangular parallelepiped shape. And the front-end | tip part 31 of the brush 30 is comprised from the projection part 31a and the taper surface 31b. The protrusion 31 a extends along the circumferential direction of the commutator 11 on the axial upper end side of the tip 31. In addition, although the front-end | tip of the projection part 31a is formed in the circular arc shape along the outer peripheral surface of the commutator 11, it may be formed in linear form in FIG. The tapered surface 31b is inclined so as to gradually move away from the outer peripheral surface of the commutator 11 from the lower end portion of the protruding portion 31a toward the lower side in the axial direction of the commutator 11.

  The brush 40 shown in FIG. 13 has a substantially rectangular parallelepiped shape. And the front-end | tip part 41 of the brush 40 is comprised from the projection part 41a and the taper surface 41b. The protruding portion 41 a is formed to be sharpened so as to narrow the circumferential width on the upper end side in the axial direction of the commutator 11 at the distal end portion 41. In other words, it extends along the axial direction on the upper end side in the axial direction of the tip portion 41. The tapered surface 41b is inclined so as to gradually move away from the outer peripheral surface of the commutator 11 from the lower end side of the protrusion 41a toward the lower side in the axial direction of the commutator 11. In FIG. 13, the tip portion 41 has a configuration including a tapered surface 41b, but may have a configuration in which the protruding portion 41a is formed from the upper end to the lower end in the axial direction without the tapered surface 41b.

  Even if comprised in this way, abrasion of the brushes 30 and 40 is accelerated | stimulated, the carbon film 16 can be formed earlier, and the time concerning a running-in operation can be shortened. In the brushes 30 and 40, the same effect can be obtained even if the protrusions 31a and 41a are formed on the lower end side in the axial direction.

  In the above embodiment, the sliding surface 21 a is formed on the lower end side in the axial direction of the commutator 11 at the tip portion 21, but may be formed on the upper end side. In this case, the tapered surface 21b is formed so as to gradually move away from the outer peripheral surface of the commutator 11 as it goes downward in the axial direction from the lower end side of the sliding surface 21a.

  In the above embodiment, the sliding surface 21a is formed in an arc shape having a radius of curvature R2 larger than the radius R1 of the commutator 11. However, the present invention is not limited to this. For example, the sliding surface 21a may be formed in an arc shape having a curvature radius R2 equal to the radius R1 of the commutator 11. The sliding surface 21a may be formed in an arc shape having a radius of curvature R2 that is smaller than the radius R1 of the commutator 11.

  In the above embodiment, the sliding surface 21 a is formed in an arc shape along the outer peripheral surface of the commutator 11, but in an arc shape that is curved in the direction opposite to the outer peripheral surface of the commutator 11. It may be formed. If comprised in this way, since the brush 18 will slide-contact with the outer peripheral surface of the commutator 11 at one point in the sliding surface 21a, abrasion of the brush 18 will be accelerated | stimulated. As a result, the carbon film 16 can be formed on the outer peripheral surface of the commutator 11 more quickly.

  In the above embodiment, the tip 21 of the brush 18 is formed with a taper surface 21b to narrow the axial width. However, the present invention is not limited thereto, and the distal end portion 21 may have a configuration in which an arcuate sliding surface 21a is formed from the upper end to the lower end in the axial direction.

  In the above embodiment, the tip portion 21 of the brush 18 is formed to be narrowed and sharpened in the axial direction, so that it slides on the outer peripheral surface of the commutator 11 at one location on the sliding surface 21a in the axial direction. This is not limited to this. For example, it is good also as a structure by which the circular-arc-shaped sliding surface 21a was formed in two places, the upper end side and lower end side of an axial direction.

  In the above embodiment, the break-in operation in the carbon film forming step is performed by supplying a load current of 50 [A]. Further, the break-in operation in the carbon film homogenizing step is performed by supplying a no-load current of 1 [A]. However, the current values of the load current and the no-load current are not limited to this, and are desirably set as appropriate according to the DC motor to be manufactured.

  In the above embodiment, the DC motor 1 is an electric power steering motor, but may be a DC motor other than the electric power steering motor. In addition to the DC motor 1, the present invention may be applied to a rotary electric motor including the brush 18 and the commutator 11.

The technical idea that can be grasped from each of the above embodiments will be described below.
(A) In the rotary electric motor according to claim 1 or 2, the tip of the brush includes a protrusion formed along a circumferential direction of the commutator. If comprised in this way, in the projection part, the area which slidably contacts with the outer peripheral surface of a commutator is narrow. Therefore, the wear of the brush is promoted, the carbon film is formed in a short time, and the time required for the break-in operation can be further shortened.

  (B) The rotary electric motor according to claim 1, wherein a tip portion of the brush is provided with a protrusion formed along an axial direction of the commutator. If comprised in this way, in the projection part, the area which slidably contacts the outer peripheral surface of a commutator is narrow. Therefore, the wear of the brush is promoted, the carbon film is formed in a short time, and the time required for the break-in operation can be further shortened.

  (C) In the rotary electric motor according to any one of (1) to (3) and (a) and (b), the tip of the brush is directed to one axial direction of the commutator. A rotary electric motor comprising a tapered surface away from the outer peripheral surface of the commutator. If comprised in this way, the area which slidably contacts with the outer peripheral surface of a commutator will become narrow in the front-end | tip part of a brush by forming the taper surface. Therefore, the wear of the brush is promoted with a simple configuration that only forms the tapered surface, and the time required for forming the carbon film can be further shortened.

  (D) In the method for manufacturing a rotary electric motor according to claim 4 or 3, the tip of the brush includes a protrusion formed along a circumferential direction of the commutator. A method of manufacturing a rotary motor.

  (E) In the method of manufacturing a rotary electric motor according to claim 4, the tip of the brush is provided with a protrusion formed along the axial direction of the commutator. Method.

  (F) In the method of manufacturing a rotary electric motor according to any one of claims 4 to 6 and (d) (e), the tip of the brush is directed in one axial direction of the commutator. A method of manufacturing a rotary electric motor, comprising a tapered surface that moves away from the outer peripheral surface of the commutator.

Sectional drawing which shows the DC motor of this embodiment. The schematic diagram which shows the assembly | attachment state of a brush. The perspective view which shows the brush of this embodiment. The schematic diagram which shows the sliding contact state of a brush and a commutator. The schematic diagram which shows the process in which a carbon film is formed. The graph which shows the result of having measured the magnetic sound about the DC motor manufactured by energizing a load current and performing a running-in operation, and then energizing a no-load current and performing a running-in operation. The graph which shows the result of having measured the sliding sound of the brush about the direct current motor manufactured by energizing load current and running in and carrying out running-in by supplying no-load current. The graph which shows the result of having measured the magnetic sound about the direct current motor manufactured by performing only the running-in operation which supplies load current. The graph which shows the result of having measured the sliding sound of the brush about the direct current motor manufactured only by running-in which energizes load current. The graph which shows the result of having measured the magnetic sound about the direct current motor manufactured by energizing a no-load current and performing a running-in operation, and then energizing the load current and performing a running-in operation. The graph which shows the result of having measured the sliding sound of the brush about the direct current motor manufactured by energizing with a no-load current and performing a break-in operation, and then performing a break-in operation with a load current. The perspective view which shows the brush of another example. The perspective view which shows the brush of another example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... DC motor as a rotary motor, 5 ... Armature, 11 ... Commutator, 16 ... Carbon film, 18, 30, 40 ... Brush, 19 ... Coil spring as urging means, 21, 31, 41 ... Tip 21a: sliding surface, R1: radius, R2: radius of curvature.

Claims (7)

A commutator provided in an armature rotatably supported;
A brush that is urged toward the commutator by an urging means and whose tip is in sliding contact with the outer peripheral surface of the commutator;
The commutator has a carbon film formed on the outer peripheral surface thereof by a carbon film formed by a first running-in operation in which a load current is passed and a second running-in operation in which a no-load current is passed. The rotary electric motor according to claim 1,
The tip of the brush is formed so as to be sharpened so as to narrow the width of the commutator in the axial direction. In the rotary electric motor according to claim 1 or 2,
The tip of the brush is formed in an arc shape along the outer peripheral surface of the commutator, and includes a sliding surface having a radius of curvature larger than the radius of the commutator. . A rotation provided with a commutator provided in an armature that is rotatably supported, and a brush that is urged toward the commutator by an urging means and whose tip is in sliding contact with the outer peripheral surface of the commutator. A method of manufacturing an electric motor,
Including a break-in process for performing a break-in operation for conforming the outer peripheral surface of the commutator and the tip of the brush;
The break-in process includes a carbon film forming process in which a carbon film is formed on the outer peripheral surface of the commutator by energizing a load current to operate the rotary motor, and a non-load current is energized to operate the rotary motor. And a carbon film homogenizing step for making the thickness of the carbon film uniform. In the manufacturing method of the rotary electric motor according to claim 4,
The method of manufacturing a rotary electric motor, wherein the tip of the brush is formed to be sharpened so as to narrow the width of the commutator in the axial direction. In the manufacturing method of the rotary electric motor according to claim 4 or 5,
The tip of the brush is formed in an arc shape along the outer peripheral surface of the commutator, and includes a sliding surface having a radius of curvature larger than the radius of the commutator. Manufacturing method.   The motor for electric power steering manufactured using the manufacturing method of the rotary electric motor of any one of Claim 4 thru | or 6.

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