WO2021149571A1 - Commutator, electric motor, and method for manufacturing commutator - Google Patents

Abstract

A commutator comprising a resin molded body, and a plurality of commutator pieces fixed to the resin molded body. Each of the plurality of commutator pieces has a contact surface in contact with the outer peripheral surface of the resin molded body, and a facing surface that is exposed from the resin molded body and faces the adjacent commutator piece of the plurality of commutator pieces. The maximum depth of surface micro-recesses in the contact surface is greater than the maximum depth of surface micro-recesses in the facing surface.

Description

Commutator, motor and commutator manufacturing method

The present disclosure relates to a commutator, a motor equipped with a commutator, and a method for manufacturing the commutator.

Motors are widely used in the field of electrical equipment such as automobiles, as well as in the field of household electrical appliances such as vacuum cleaners. For example, in an electric blower mounted on a vacuum cleaner, an electric motor is used to rotate a rotating fan.

As electric motors, commutator motors that use brushes and brushless motors that do not use brushes are known. The commutator motor includes a stator, a rotor, a commutator attached to the rotating shaft of the commutator, and a brush that is in sliding contact with the commutator.

The commutator used in the commutator motor includes, for example, a tubular commutator body having a through hole into which a rotating shaft is inserted, and a plurality of commutator pieces fixed at equal intervals on the outer peripheral surface of the commutator body. Have. As a commutator having such a configuration, a molded commutator in which a plurality of commutator pieces are molded with a resin is known. In the molded commutator, the commutator body is a resin molded body made of resin.

In a commutator motor used for automobiles or electric vacuum cleaners, the rotor rotates at high speed, so the commutator attached to the rotating shaft of the rotor also rotates at high speed. At this time, if a commutator is used as the commutator, the commutator piece fixed to the resin molded body may float from the resin molded body due to centrifugal force during high-speed rotation.

Therefore, conventionally, in order to suppress the commutator piece from floating when the commutator is rotated, a technique for roughening the contact surface of the commutator piece with the resin molded body has been proposed (for example, Patent Document 1, Patent Document 1, See 2). By roughening the surface of the commutator piece, the adhesion to the resin molded body can be improved, so that the commutator piece can be suppressed from floating during high-speed rotation.

However, it was found that if the entire surface of the commutator piece is roughened, another problem occurs in which the side surface of the commutator piece (the surface facing the adjacent commutator) is also roughened. Therefore, if another problem does not occur, it becomes impossible to prevent the commutator piece from floating when the commutator rotates.

Japanese Unexamined Patent Publication No. 2002-51506 JP-A-2017-158416

An object of the present disclosure is to provide a commutator, a method for manufacturing a commutator, and the like, which can suppress the floating of a commutator piece when the commutator rotates while suppressing the occurrence of another defect. ..

In order to achieve the above object, one aspect of the commutator according to the present disclosure includes a resin molded body and a plurality of commutator pieces fixed to the resin molded body, and each of the plurality of commutator pieces is provided. The surface of the contact surface, which has a contact surface in contact with the outer peripheral surface of the resin molded body and a facing surface exposed from the resin molded body and facing an adjacent commutator piece among the plurality of commutator pieces. The maximum depth of the micro-recess of the surface is deeper than the maximum depth of the micro-recess on the surface of the facing surface.

Further, one aspect of the electric motor according to the present disclosure includes the commutator, a rotor having a rotating shaft to which the commutator is attached, and a stator that generates a magnetic force acting on the commutator.

Further, in one aspect of the commutator manufacturing method according to the present disclosure, a resin molded body having a through hole into which a rotating shaft of an electric motor is inserted and a plurality of commutator pieces arranged in an annular shape around the rotating shaft are formed. A method of manufacturing a commutator to be provided, wherein the plurality of commutator pieces are arranged in a cylindrical basket in an annular shape, and at least a part of the surface of each of the plurality of commutator pieces is roughened. A step of forming the resin molded body in which the plurality of commutator pieces are fixed by injecting a liquid resin into the inner peripheral portion of the basket in which the plurality of commutator pieces are arranged and curing the liquid resin. including.

Another aspect of the commutator manufacturing method according to the present disclosure is a resin molded body having a through hole inserted into the rotating shaft of an electric motor and a plurality of commutator pieces arranged in an annular shape around the rotating shaft. A method of manufacturing a commutator including the above, wherein at least a part of the surface of a tubular commutator base material serving as a base material of the plurality of commutator pieces is roughened, and the commutator base material The step of forming the resin molded body to which the commutator base material is fixed by injecting a liquid resin into the inner peripheral portion and curing the commutator base material, and separating the commutator base material into the plurality of commutator pieces. Including steps.

While suppressing the occurrence of another problem, it is possible to prevent the commutator piece from floating when the commutator rotates.

It is external perspective view of the electric blower which concerns on embodiment. It is a half cross-sectional view of the electric blower which concerns on embodiment. It is a perspective view of the commutator which concerns on embodiment. It is a side view of the commutator which concerns on embodiment. It is sectional drawing of the commutator in line IVb-IVb of FIG. 4A. It is sectional drawing of the commutator in IVc-IVc line of FIG. 4A and FIG. 4B. It is a flowchart of the commutator manufacturing method (basket construction method) which concerns on embodiment. It is a perspective view of the commutator piece (state before hook bending) used in the commutator manufacturing method which concerns on embodiment. It is a perspective view of the basket used in the manufacturing method of the commutator which concerns on embodiment. It is a figure for demonstrating the process of arranging a commutator piece in a basket in the method of manufacturing a commutator which concerns on embodiment. It is a figure for demonstrating the process of arranging a commutator piece in a basket in the method of manufacturing a commutator which concerns on embodiment. It is a figure for demonstrating the process of roughening a commutator piece in the commutator manufacturing method which concerns on embodiment. It is a figure for demonstrating the process of resin molding a resin molded body in the manufacturing method of the commutator which concerns on embodiment. It is a figure for demonstrating the process of removing a basket in the method of manufacturing a commutator which concerns on embodiment. It is a figure for demonstrating the process of hook bending of a commutator piece in the method of manufacturing a commutator which concerns on embodiment. It is a flowchart of another commutator manufacturing method (undercut method) which concerns on embodiment. It is a figure which shows the cross-sectional SEM image at the contact interface between a resin molded body and a commutator piece about the commutator actually manufactured by the manufacturing method using the basket construction method. It is a figure for demonstrating the strength of the commutator of an Example. It is a perspective view of another commutator piece (state before hook bending) used in the commutator manufacturing method which concerns on embodiment. It is a side view of another commutator piece (state before hook bending) used in the commutator manufacturing method which concerns on embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. It should be noted that all of the embodiments described below show a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, arrangement positions of the components, connection forms, and the like shown in the following embodiments are examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, the components not described in the independent claims indicating the highest level concept of the present disclosure will be described as arbitrary components.

Note that each figure is a schematic view and is not necessarily exactly illustrated. In each figure, substantially the same configuration is designated by the same reference numerals, and duplicate description will be omitted or simplified.

(Embodiment)
First, the electric blower 1 will be described as an example of the electric device in which the commutator according to the present disclosure is used. FIG. 1 is an external perspective view of the electric blower 1 according to the embodiment. FIG. 2 is a half cross-sectional view of the electric blower 1. FIG. 2 shows a cross section when cut in a plane passing through the axis C of the rotating shaft 13. The arrow shown in FIG. 2 indicates the flow of air sucked into the electric blower 1.

As shown in FIGS. 1 and 2, the electric blower 1 is discharged from the electric motor 2 having the rotor 11 and the stator 12, the rotary fan 3 attached to the rotary shaft 13 of the motor 2, and the rotary fan 3. An air guide 4 through which air flows, a fan case 5 covering the rotary fan 3 and the air guide 4, a frame 6 for accommodating the rotor 11 and the stator 12, and a bracket 7 arranged so as to straddle the opening of the frame 6. And.

The electric motor 2 is a fan motor that rotates the rotating fan 3. The electric motor 2 is a commutator electric motor with a brush. The electric motor 2 includes a rotor 11, a stator 12, a rotating shaft 13, a commutator 14, a brush 15, a first bearing 16, and a second bearing 17. The electric motor 2 is a direct current electric motor (DC motor) driven by direct current.

The rotor 11 (rotor) generates a magnetic force acting on the stator 12. The direction of the main magnetic flux generated by the rotor 11 is a direction orthogonal to the direction of the axis C of the rotating shaft 13 (rotating axis direction).

The rotor 11 has a rotating shaft 13. The rotor 11 rotates about the rotation shaft 13 by the magnetic force generated by the stator 12. That is, the rotor 11 rotates about the axis C of the rotating shaft 13 as the center of rotation. The rotor 11 rotates at high speed, for example, at 40,000 rpm (revolutions per minutes).

The rotor 11 is arranged via the stator 12 and the air gap. Specifically, there is a minute air gap between the surface of the rotor 11 and the surface of the stator 12. The rotor 11 in the present embodiment is an inner rotor and is arranged inside the stator 12.

The rotor 11 is an armature. The rotor 11 has a rotor core (rotor core) 11a and a winding coil 11b (rotor coil) wound around the rotor core 11a.

The rotor core 11a is an armature core around which a winding coil 11b is wound. The rotor core 11a is a laminated body in which a plurality of electromagnetic steel sheets are laminated in the direction of the axis C of the rotating shaft 13. The rotor core 11a is not limited to a laminated body of electromagnetic steel sheets, and may be a bulk body made of a magnetic material.

The rotor core 11a has a plurality of teeth. The plurality of teeth extend radially in a direction (radial direction) orthogonal to the axis C of the rotation axis 13. The plurality of teeth exist at equal intervals along the rotation direction of the rotation shaft 13.

The winding coil 11b is wound around the rotor core 11a. The winding coil 11b has a coil wound around each of the plurality of teeth. The coil is wound around the teeth multiple times. Specifically, the coil is a distributed winding coil that is wound around a tooth via an insulator.

The winding coil 11b is electrically connected to the commutator 14. Specifically, the winding coil 11b is electrically connected to the commutator piece of the commutator 14. When a current flows through the winding coil 11b via the commutator 14, the rotor 11 generates a magnetic force acting on the stator 12.

The stator 12 (stator) is located facing the rotor 11 and generates a magnetic force acting on the rotor 11. The stator 12 constitutes a magnetic circuit together with the rotor 11 which is an armature.

Specifically, the stator 12 is arranged so as to surround the rotor core 11a of the rotor 11. The stator 12 is configured such that the north pole and the south pole of the magnetic pole appear alternately in the circumferential direction on the air gap surface. In this case, the stator 12 may be configured such that a plurality of permanent magnets are arranged along the circumferential direction, or is composed of a stator core having a plurality of teeth and a winding coil wound around the stator core. It may have been done. The stator 12 is a field assembly in which a winding coil is wound around a tooth of a stator core in which a plurality of electromagnetic steel sheets are laminated. The stator 12 is fixed to the frame 6, for example.

The rotating shaft 13 is a long shaft that serves as a center when the rotor 11 rotates. The rotating shaft 13 is, for example, a metal rod. The rotating shaft 13 is fixed to the center of the rotor 11. Specifically, the rotating shaft 13 is fixed to the rotor core 11a in a state of penetrating the center of the rotor core 11a of the rotor 11 so as to extend to both sides of the rotor 11. The rotating shaft 13 is fixed to the rotor core 11a by press-fitting or shrink-fitting into the central hole formed in the rotor core 11a.

The first portion 13a of the rotating shaft 13 protruding from the rotor 11 to one side (rotating fan 3 side) is supported by the first bearing 16. In the present embodiment, the first portion 13a of the rotating shaft 13 is a portion (output shaft) on the output side of the rotating shaft 13. Specifically, the first portion 13a of the rotating shaft 13 projects from the first bearing 16. A rotary fan 3 is attached to the tip of the first portion 13a of the rotary shaft 13 protruding from the first bearing 16 as a load driven by the motor 2.

On the other hand, the second portion 13b of the rotating shaft 13 protruding from the rotor 11 to the other side is supported by the second bearing 17. In the present embodiment, the second portion 13b of the rotating shaft 13 is a portion (anti-output shaft) on the counter-output side of the rotating shaft 13.

The commutator 14 is attached to the rotating shaft 13. Therefore, the commutator 14 rotates together with the rotating shaft 13. The commutator 14 is attached to the second portion 13b of the rotating shaft 13. Specifically, the commutator 14 is attached to a portion of the rotating shaft 13 between the rotor core 11a and the second bearing 17. The detailed configuration of the commutator 14 will be described later.

The brush 15 is in contact with the commutator 14. Specifically, the brush 15 is in contact with any of the plurality of commutator pieces of the commutator 14. The brush 15 is a power supply brush for supplying electric power to the winding coil 11b of the rotor 11. When the brush 15 comes into contact with the commutator piece, the armature current supplied to the brush 15 via the power supply terminal flows to the winding coil 11b via the commutator piece.

As an example, the brush 15 is a conductive carbon brush made of carbon. Specifically, the brush 15 is a carbon brush containing a metal such as copper. The brush 15 is a long rod-shaped member. The brush 15 is a long, substantially rectangular parallelepiped. The brush 15 can be produced, for example, by crushing a kneaded product obtained by kneading graphite powder, copper powder, a binder resin, and a curing agent, compression molding into a substantially rectangular parallelepiped, and firing.

A pair of brushes 15 are provided so as to be slidable with the commutator 14. The pair of brushes 15 are arranged so as to sandwich the commutator 14 so as to sandwich the commutator 14. Specifically, the inner tips of the pair of brushes 15 are in contact with the commutator 14. More specifically, each brush 15 is pressed toward the commutator 14 by a brush spring such as a torsion spring, and is in contact with the commutator 14. The end surface of the brush 15 on the inner side (rotating shaft 13 side) in the longitudinal direction is the contact surface with the commutator 14. The brush 15 is housed in a brush box.

The first bearing 16 and the second bearing 17 rotatably support the rotating shaft 13. The rotating shaft 13 is supported by the first bearing 16 and the second bearing 17 in a rotatable state. The first bearing 16 and the second bearing 17 are, for example, bearings. Specifically, the first bearing 16 and the second bearing 17 are ball bearings, but the present invention is not limited thereto. The first bearing 16 and the second bearing 17 may be other bearings such as a sliding bearing. The first bearing 16 is fixed to the bracket 7. The second bearing 17 is fixed to the bottom of the frame 6.

In the motor 2 configured as described above, the current supplied to the brush 15 flows through the commutator 14 to the winding coil 11b wound around the rotor core 11a as an armature current (drive current). As a result, magnetic flux is generated in the rotor 11. The magnetic force generated by the interaction between the magnetic flux generated in the rotor 11 and the magnetic flux generated in the stator 12 becomes the torque for rotating the rotor 11. At this time, the direction in which the current flows is switched depending on the positional relationship when the commutator piece of the commutator 14 and the brush 15 are in contact with each other. By switching the direction in which the current flows in this way, a rotational force in a fixed direction is generated by the repulsive force and the attractive force of the magnetic force generated between the rotor 11 and the stator 12, and the rotor 11 rotates. do.

As the rotor 11 rotates, the rotating shaft 13 to which the rotor 11 is attached rotates around the axis C. As a result, the rotating fan 3 attached to the rotating shaft 13 of the electric motor 2 rotates.

The rotating fan 3 sucks air into the outer housing (housing) composed of the fan case 5 and the frame 6. As an example, the rotary fan 3 is a centrifugal fan that can obtain a high suction pressure. Wind pressure is generated by the rotation of the rotary fan 3, air is sucked from the intake port 5a formed in the fan case 5, and air is discharged from the rotary fan 3. The air discharged from the rotary fan 3 flows into the air guide 4.

The air guide 4 has a plurality of diffuser blades arranged on the outer circumference of the rotary fan 3 as a guide plate for rectifying the flow of gas. For example, the air guide 4 rectifies the flow of air sucked from the intake port 5a formed in the fan case 5 by the rotation of the rotating fan 3 to generate a swirling flow, and the sucked gas is smoothly transferred to the frame 6. Pour in.

The fan case 5 is a cover that covers the rotating fan 3. The fan case 5 is fixed to the frame 6. The fan case 5 has an intake port 5a for sucking outside air. As the rotating fan 3 rotates, air flows into the fan case 5 from the intake port 5a formed in the fan case 5.

The frame 6 is a housing (case) for accommodating the motor 2. The frame 6 is a bottomed tubular body having an opening. The frame 6 is made of a metal material such as aluminum. The frame 6 may be made of a resin material. A plurality of exhaust ports 6a are provided on the side wall of the bottom of the frame 6 in order to discharge the air sucked by the rotation of the rotary fan 3 to the outside.

The bracket 7 is a plate member that covers the opening of the frame 6 together with the air guide 4. The bracket 7 partially covers the opening of the frame 6 without completely closing the opening of the frame 6. The bracket 7 is arranged so as to straddle the opening of the frame 6. As a result, when the bracket 7 is attached to the frame 6, the frame 6 has an opening as a ventilation path for air rectified by the air guide 4. The air rectified by the air guide 4 passes through this opening and flows into the frame 6. The bracket 7 is also formed with an opening hole through which the air rectified by the air guide 4 passes.

In the electric blower 1 configured in this way, when the rotor 11 included in the electric motor 2 rotates, the rotating fan 3 rotates, and air is sucked into the fan case 5 from the intake port 5a of the fan case 5. As a result, air flows into the rotary fan 3. The air sucked by the rotary fan 3 is compressed to a high pressure by the fan blades of the rotary fan 3 and discharged in the radial direction from the outer peripheral side portion of the rotary fan 3. The air discharged from the outer peripheral side of the rotary fan 3 is guided to the outer peripheral portion of the fan case 5 by the diffuser blades of the air guide 4 surrounding the rotary fan 3. The air guided to the outer peripheral portion of the fan case 5 becomes a swirling flow in the space between the air guide 4 and the fan case 5, and flows into the frame 6. The air that has flowed into the frame 6 is discharged to the outside of the electric blower 1 from the exhaust port 6a of the frame 6.

As described above, the electric motor 2 of the present embodiment includes a commutator 14, a rotor 11 having a rotating shaft 13 to which the commutator 14 is attached, and a stator 12 that generates a magnetic force acting on the commutator 11. To be equipped.

[Commutator configuration]
Next, the detailed configuration of the commutator 14 used in the electric motor 2 of the electric blower 1 according to the present embodiment will be described with reference to FIGS. 3, 4A, 4B, and 4C. FIG. 3 is a perspective view of the commutator 14 according to the embodiment. FIG. 4A is a side view of the commutator 14. FIG. 4B is a cross-sectional view of the commutator 14 on the IVb-IVb line of FIG. 4A. FIG. 4C is a cross-sectional view of the commutator 14 on the IVc-IVc line of FIGS. 4A and 4B.

As shown in FIGS. 3, 4A, 4B, and 4C, the commutator 14 has a resin molded body 20 and a plurality of commutator pieces 30. The commutator 14 is a molded commutator, and a plurality of commutator pieces 30 are molded with resin.

The resin molded body 20 is a resin portion of the commutator 14 which is a mold commutator. The resin molded body 20 is the main body (commutator main body) of the commutator 14. The resin molded body 20 has a through hole 21 into which the rotating shaft 13 of the electric motor 2 is inserted. The resin molded body 20 is a substantially tubular body having a central axis of the through hole 21 as a tubular axis. The direction of the cylinder axis of the resin molded body 20 coincides with the direction of the axis C of the rotating shaft 13. That is, the axis of the resin molded body 20 coincides with the axis C of the rotating shaft 13. The circumferential direction of the resin molded body 20 coincides with the rotation direction of the rotating shaft 13.

The resin molded body 20 is made of a resin material such as a thermosetting resin. As the thermosetting resin constituting the resin molded body 20, for example, a phenol resin can be used. The resin molded body 20 can be formed into a predetermined shape by transfer molding using a mold for transfer molding. The resin molded body 20 may be made of a resin material in which reinforcing fibers such as glass fibers are dispersed. Thereby, the durability of the resin molded body 20 can be improved.

The plurality of commutator pieces 30 are arranged in a ring shape so as to surround the rotation shaft 13. The plurality of commutator pieces 30 are arranged in an annular shape along the circumferential direction of the rotation shaft 13. That is, the plurality of commutator pieces 30 are arranged in an annular shape along the circumferential direction of the resin molded body 20.

Each of the plurality of commutator pieces 30 has a long shape extending along the axial direction of the rotating shaft 13. The commutator pieces 30 are arranged in a posture in which the longitudinal direction thereof is parallel to the direction of the axis C of the rotating shaft 13. Specifically, the plurality of commutator pieces 30 surround the resin molded body 20, and the longitudinal direction of each commutator piece 30 is in the tubular axis direction of the resin molded body 20 in the circumferential direction of the resin molded body 20. They are evenly spaced along.

The plurality of commutator pieces 30 are conductive terminals made of a conductive material made of a metal material such as copper. Each commutator piece 30 is made of a copper alloy. The plurality of commutator pieces 30 are arranged in a state of being isolated from each other along the circumferential direction of the rotating shaft 13. That is, the two commutator pieces 30 adjacent to each other are isolated from each other in the rotation direction of the rotation shaft 13.

The plurality of commutator pieces 30 are fixed to the resin molded body 20. Specifically, each commutator piece 30 is fixed to the resin molded body 20 by being partially embedded in the resin molded body 20 so that a part of the surface is exposed. That is, each commutator piece 30 is in contact with the outer peripheral surface of the resin molded body 20.

Each of the plurality of commutator pieces 30 has an exposed portion 31 in which at least a part of the surface is exposed from the resin molded body 20, an embedded portion 32 embedded in the resin molded body 20, and windings of the rotor 11 of the electric motor 2. It has a hook portion 33 to which the coil 11b is connected.

The exposed portion 31 functions as a sliding contact portion with which the brush 15 of the electric motor 2 is in sliding contact. The exposed portion 31 has a front surface 31a and a side surface 31b as exposed surfaces exposed from the resin molded body 20. The front surface 31a is a first exposed surface, which is a contact surface with which the brush 15 of the electric motor 2 comes into contact. The side surface 31b is a second exposed surface, which is a facing surface facing the adjacent commutator piece 30 among the plurality of commutator pieces 30. That is, the two commutator pieces 30 adjacent to each other are arranged with a gap, and in the two commutator pieces 30 adjacent to each other, the facing surface of one commutator piece 30 and the facing surface of the other commutator piece 30. Is facing through the gap.

Further, as shown in FIG. 4C, the length W1 along the circumferential direction on the outer peripheral side in the interval between two adjacent commutator pieces 30 among the plurality of commutator pieces 30 is the inner peripheral side in the interval. It is longer than the length W2 along the circumferential direction (W1> W2).

The exposed portion 31 further has a back surface 31c as a contact surface in contact with the outer peripheral surface of the resin molded body 20. The back surface 31c is a surface facing the front surface 31a and is not exposed from the resin molded body 20.

The buried portion 32 is provided on the back surface 31c of the exposed portion 31. Specifically, the embedded portion 32 is provided so as to project from the back surface 31c toward the resin molded body 20 side. Each commutator piece 30 is provided with two embedded portions 32. The two embedded portions 32 are arranged along the longitudinal direction of the commutator piece 30 with a gap.

The embedded portion 32 has an embedded surface 32c as a contact surface in contact with the outer peripheral surface of the resin molded body 20. Since the entire embedded portion 32 is embedded in the resin molded body 20, the entire surface of the embedded portion 32 is in contact with the outer peripheral surface of the resin molded body 20. That is, the entire surface of the buried portion 32 is the buried surface 32c.

At the root of the buried portion 32 on the exposed portion 31 side, a constricted portion is formed in which a part of the buried portion 32 is constricted. The cross-sectional shape of the buried portion 32 is an inverted trapezoidal shape.

The hook portion 33 is provided at the end of the commutator piece 30. Specifically, the hook portion 33 is provided at one end of the exposed portion 31. The hook portion 33 is provided at the end portion of the exposed portion 31 on the rotor 11 side. The hook portion 33 is formed by bending a part of the commutator piece 30.

As described above, each commutator piece 30 has a back surface 31c of the exposed portion 31 and an embedded surface 32c of the embedded portion 32 as contact surfaces in contact with the outer peripheral surface of the resin molded body 20. The back surface 31c and the embedded surface 32c are surfaces on the back side of the commutator piece 30, and are in surface contact with the outer peripheral surface of the resin molded body 20.

In the commutator piece 30, the maximum depth of the surface minute recesses on the back surface 31c and the embedded surface 32c, which are the contact surfaces with the resin molded body 20, is the surface on the side surface 31b, which is the facing surface facing the adjacent commutator piece 30. It is deeper than the maximum depth of the minute recesses in. The maximum depth of the surface micro-recesses on the back surface 31c and the buried surface 32c is coarser than the maximum depth of the surface micro-recesses on the front surface 31a.

That is, the centerline average roughness of the back surface 31c and the buried surface 32c, which are contact surfaces in contact with the outer peripheral surface of the resin molded body 20, is the centerline average roughness of the side surface 31b and the front surface 31a, which are exposed surfaces exposed from the resin molded body 20. It is coarser than that.

Specifically, the back surface 31c and the buried surface 32c, which are contact surfaces of the commutator piece 30 in contact with the outer peripheral surface of the resin molded body 20, are roughened. As a result, the back surface 31c and the buried surface 32c are rough surfaces. That is, the entire surface of the buried portion 32 is roughened. The arithmetic mean roughness (Ra) of the roughened back surface 31c and the buried surface 32c is, for example, 1 μm or more.

When the back surface 31c and the buried surface 32c are roughened without roughening the front surface 31a and the side surface 31b, the upper limit of the arithmetic mean roughness (Ra) of the back surface 31c and the buried surface 32c is not particularly limited. However, the arithmetic mean roughness (Ra) of the back surface 31c and the buried surface 32c is, for example, 50 μm or less, preferably 10 μm or less.

As the roughening treatment, a chemical treatment for etching the surface of the commutator piece 30 with an etching solution may be used, or a machining treatment for unevenly processing the surface of the commutator piece 30 by knurling or the like may be used. ..

On the other hand, the side surface 31b of the commutator piece 30 facing the adjacent commutator piece 30 is not roughened. The front surface 31a, which is the contact surface of the commutator piece 30 in contact with the brush 15, is also not roughened. Therefore, the side surface 31b and the front surface 31a remain solid metal surfaces.

As described above, the surface of the exposed portion 31 is partially roughened, and among the front surface 31a, the side surface 31b and the back surface 31c of the exposed portion 31, the back surface 31c is roughened, but the front surface 31a and the front surface 31a and The side surface 31b is not roughened.

In the present embodiment, both the back surface 31c and the buried surface 32c are deeper than the side surface 31b and the maximum depth of the minute recesses on the surface. However, it is sufficient that at least one of the back surface 31c and the buried surface 32c has a deeper maximum depth of the micro-recess on the surface than the side surface 31b. The front surface 31a and the side surface 31b are not roughened. However, if one or both of the back surface 31c and the buried surface 32c have a deeper maximum depth of the micro-recesses on the surface than the side surface 31b, even if one or both of the front surface 31a and the side surface 31b are roughened. good. That is, one or both of the front surface 31a and the side surface 31b may be roughened surfaces. Alternatively, one or both of the side surface 31b and the front surface 31a may be mechanically or chemically smoothed. That is, one or both of the front surface 31a and the side surface 31b may be smooth surfaces. Further, the surface of the hook portion 33 may or may not be roughened.

[Commutator manufacturing method]
Next, a method of manufacturing the commutator 14 according to the embodiment will be described with reference to FIGS. 5 to 12. FIG. 5 is a flowchart of a method for manufacturing the commutator 14 according to the embodiment. 6 to 12 are diagrams for explaining each step in the method for manufacturing the commutator 14.

The commutator 14 in this embodiment is manufactured by the basket construction method. Specifically, the commutator 14 is manufactured by arranging a plurality of commutator pieces in a basket that serves as a mold for resin molding and molding the resin molded body with resin. Hereinafter, the method for manufacturing the commutator 14 according to the present embodiment will be described in detail.

First, before the commutator piece is resin-molded, as shown in FIGS. 5 to 7, the commutator piece 30M is prepared in advance (step S11), and the basket 100 is prepared in advance (step S12). ..

Specifically, as the commutator piece 30 in the state before forming the hook portion 33, the commutator piece 30M having the shape shown in FIG. 6 is manufactured (step S11). FIG. 6 is a perspective view of a commutator piece (state before hook bending) used in the commutator manufacturing method according to the embodiment. As shown in FIG. 6, the commutator piece 30M (tater bar) is a metal piece on which the exposed portion 31 and the buried portion 32 are formed. The commutator piece 30M is made of a copper alloy. Specifically, the commutator piece 30M can be manufactured by performing a press punching process on a copper plate. The commutator piece 30M has the same shape as the commutator piece 30 except that the hook portion 33 and the rough surface are not formed.

Further, as a jig used when molding the commutator piece 30M into resin, a basket 100 having the shape shown in FIG. 7 is manufactured (step S12).

FIG. 7 is a perspective view of the basket used in the commutator manufacturing method according to the embodiment. As shown in FIG. 7, the basket 100 is a holder that holds the commutator piece 30M when the commutator piece 30M is resin-molded, and is a container that stores the commutator piece 30M. Specifically, the basket 100 is a substantially cylindrical member, and has a plurality of recesses 110 as storage portions for storing the plurality of commutator pieces 30M. Each recess 110 is formed in a groove shape so as to extend in the tubular axis direction of the basket 100, and has a shape in which the commutator piece 30M is fitted. The plurality of recesses 110 are arranged in an annular shape along the inner peripheral surface of the basket 100 in a top view. The basket 100 has a protrusion 120 located between two adjacent recesses 110. The convex portion 120 is formed in a ridge so as to extend in the tubular axis direction of the basket 100.

The basket 100 can be formed by injection molding using, for example, a resin material. By using the resin basket 100, the basket 100 easily adapts to the shape of the commutator piece 30M due to heat and pressure.

The basket 100 is not limited to resin, but may be made of metal. Since the metal basket 100 has higher rigidity and is more resistant to heat and pressure than the resin basket 100, it can be used repeatedly and many times.

In this way, the commutator piece 30M is manufactured and the basket 100 is manufactured before the commutator piece 30M is resin-molded. However, which of the commutator piece 30M manufacturing process and the basket 100 manufacturing process comes first? You may go to. Further, the manufacturing step of the commutator piece 30M and the manufacturing step of the basket 100 may be performed at the same time.

Next, as shown in FIGS. 5, 8A and 8B, the commutator piece 30M shown in FIG. 6 is placed in the tubular basket 100 shown in FIG. 7 (step S13). In this case, a plurality of commutator pieces 30M are assembled into the tubular basket 100 so as to form an annular arrangement.

Specifically, as shown in FIG. 8A, the commutator piece 30M is inserted into the recess 110 of the basket 100 so that the embedded portion 32 of the commutator piece 30M faces inward. FIG. 8A is a diagram for explaining a step of arranging the commutator piece 30M in the basket in the commutator manufacturing method according to the embodiment. That is, the commutator piece 30M is inserted into the recess 110 of the basket 100 so that the front surface 31a of the commutator piece 30M faces the outside (inner surface side of the basket 100) and the back surface 31c of the commutator piece 30M faces inward. At this time, the commutator piece 30M is inserted into all of the plurality of recesses 110 provided in the basket 100. As a result, as shown in FIG. 8B, the plurality of commutator pieces 30M are arranged in an annular shape and are stored and held in the basket 100. FIG. 8B is a diagram for explaining a step of arranging the commutator piece 30M in the basket in the commutator manufacturing method according to the embodiment. In this state, the commutator piece 30M is not fixed to the recess 110 of the basket 100, but is arranged in a loosely fitted state with respect to the recess 110.

In the commutator piece 30M arranged in the basket 100, the front surface 31a and the side surface 31b of the exposed portion 31 are covered with the basket 100. Specifically, in the commutator piece 30M inserted into the recess 110, the front surface 31a and the side surface 31b are in close contact with the recess 110 of the basket 100. On the other hand, the back surface 31c of the exposed portion 31 and the buried surface 32c of the buried portion 32 in the commutator piece 30M are in a state of facing the inside of the basket 100 without being covered by the basket 100. That is, the back surface 31c and the buried surface 32c are exposed.

Next, as shown in FIGS. 5 and 9, at least a part of the surface of each of the plurality of commutator pieces 30M is roughened (step S14). Specifically, the surface of the commutator piece 30M can be roughened by subjecting the commutator piece 30M to a roughening treatment. As the roughening treatment, a chemical treatment is used in which the surface of the commutator piece 30M is etched with an etching solution. For example, FIG. 9 is a diagram for explaining a step of roughening the commutator piece 30M in the commutator manufacturing method according to the embodiment. As shown in FIG. 9, a basket 100 in which a plurality of commutator pieces 30M are arranged is placed in an etching tank containing an etching solution 200, and the plurality of commutator pieces 30M are immersed in the etching solution 200 together with the basket 100. Then, a part of the surface of the commutator piece 30M is roughened.

At this time, since the back surface 31c of the exposed portion 31 and the buried surface 32c of the buried portion 32, which are the back surfaces of the commutator piece 30M, are exposed in the commutator piece 30M, the back surface 31c and the buried surface 32c of the commutator piece 30M are exposed. The surface is roughened by etching with the etching solution 200. As a result, minute irregularities are formed on the surfaces of the back surface 31c and the buried surface 32c of the commutator piece 30M. Since the commutator piece 30M is made of a copper alloy, the etching solution 200 used is one capable of roughening the copper alloy.

On the other hand, since the front surface 31a and the side surface 31b of the commutator piece 30M are in close contact with the basket 100, they are not exposed to the etching solution 200. That is, since the front surface 31a and the side surface 31b of the commutator piece 30M are masked by the basket 100, the etching solution 200 is not applied and the surface is not roughened.

In this way, the commutator piece 30M is roughened. However, instead of roughening the entire surface of the commutator piece 30M, a part of the surface of the commutator piece 30M is selectively roughened. Specifically, in the commutator piece 30M, of the contact surface with the resin molded body 20 and the facing surface facing the adjacent commutator piece 30M, only the contact surface with the resin molded body 20 is selectively roughened. It is surfaced. More specifically, of the back surface 31c and the buried surface 32c and the front surface 31a and the side surface 31b of the commutator piece 30M, only the back surface 31c and the buried surface 32c are selectively roughened. That is, in the step of roughening the commutator piece 30M, the roughening treatment is not performed on the side surface 31b which is the facing surface facing the adjacent commutator piece 30M and the front surface 31a which is the contact surface in contact with the brush 15. ..

As a result, the maximum depth of the surface micro-recesses on the back surface 31c and the buried surface 32c, which are the contact surfaces with the resin molded body 20, is the surface micro-recesses on the side surface 31b, which is the facing surface facing the adjacent commutator piece 30M. It is deeper than the maximum depth of the surface, and is deeper than the maximum depth of the minute recesses on the surface of the front surface 31a, which is the contact surface with the brush 15.

As described above, the commutator 14 of the present embodiment includes the resin molded body 20 and the plurality of commutator pieces 30M fixed to the resin molded body 20, and each of the plurality of commutator pieces 30M is made of resin. It has a contact surface 31c in contact with the outer peripheral surface of the molded body 20 and a facing surface 31b exposed from the resin molded body 20 and facing the adjacent commutator piece 30M among the plurality of commutator pieces 30M. The maximum depth of the micro-recess on the surface is deeper than the maximum depth of the micro-recess on the surface on the facing surface 31b.

As a result, it is possible to suppress the commutator piece 30M from floating when the commutator 14 is rotated, while suppressing the occurrence of another problem.

Further, the resin molded body 20 has a through hole 21 into which the rotating shaft 13 of the electric motor 2 is inserted, and the commutator piece 30M has a front surface 31a in contact with the brush 15 of the electric motor 2 and is a surface of the contact surface 31c. The maximum depth of the micro-recess is preferably deeper than the maximum depth of the micro-recess on the surface of the front surface 31a.

Further, the length of the plurality of commutator pieces 30M along the circumferential direction on the outer peripheral side in the interval between two adjacent commutator pieces 30M is longer than the length along the circumferential direction on the inner peripheral side in the interval. Is preferable.

Next, after roughening a part of the surface of the commutator piece 30M, the resin molded body 20 is formed by resin molding as shown in FIGS. 5 and 10 (step S15). Specifically, as shown in FIG. 10, the plurality of commutator pieces 30M are fixed by injecting a liquid resin into the inner peripheral portion of the basket 100 in which the plurality of commutator pieces 30M are arranged and curing the liquid resin. The resin molded body 20 is formed. FIG. 10 is a diagram for explaining a step of resin molding a resin molded body in the commutator manufacturing method according to the embodiment.

In this case, the liquid resin is injected inside the plurality of commutator pieces 30M. That is, the liquid resin is injected into the region surrounded by the plurality of commutator pieces 30M. At this time, when the liquid resin is cured, the liquid resin shrinks in the direction (that is, inward) opposite to the commutator piece 30M side. However, since the commutator piece 30M arranged in the basket 100 is not fixed to the basket 100, it can follow the shrinkage of the resin. That is, the commutator piece 30M moves inward in the radial direction as the resin shrinks during resin molding of the resin molded body 20. As a result, the resin molded body 20 and the commutator piece 30M are not separated from each other, so that it is possible to prevent the interface between the resin molded body 20 and the commutator piece 30M from being separated from each other as the resin shrinks. Therefore, the resin molded body 20 and the commutator piece 30M can be firmly joined.

As the resin molding of the resin molded body 20, transfer molding or injection molding can be used. A thermosetting resin made of a phenol resin is used as the resin constituting the liquid resin. When the resin molded body 20 is resin-molded, a through hole 21 is also formed in the resin molded body 20.

Next, as shown in FIGS. 5 and 11, the basket 100 is removed (step S16). For example, by extruding the basket 100, the basket 100 can be removed from the resin molded body 20 to which the plurality of commutator pieces 30M are fixed. As a result, the resin molded body 20 to which the plurality of commutator pieces 30M are fixed and the basket 100 are separated, and as shown in FIG. 11, the resin molded body 20 to which the plurality of commutator pieces 30M are fixed to the outer peripheral surface is separated. Can be obtained. FIG. 11 is a diagram for explaining a step of removing the basket in the commutator manufacturing method according to the embodiment.

Next, as shown in FIGS. 5 and 12, annealing treatment is performed (step S17). For example, the resin molded body 20 to which a plurality of commutator pieces 30M are fixed is annealed under the conditions that the temperature is 200 ° C. or higher and 300 ° C. or lower and the annealing time is 16 hours or more and 24 hours or less. As a result, the resin of the resin molded body 20 can be completely solidified.

Next, as shown in FIG. 5, the plurality of commutator pieces 30M fixed to the resin molded body 20 are surface-treated and hook-bent (step S18). For example, after performing surface treatment such as scraping the surface of the commutator piece 30M by performing machining such as cutting to adjust the inner and outer diameters, hook bending is performed by forming to make each commutator piece 30M. The hook portion 33 is formed.

As a result, as shown in FIG. 5, the commutator 14 is completed (step S19). Specifically, as shown in FIG. 12, the commutator 14 having the commutator piece 30 on which the hook portion 33 is formed is completed. FIG. 12 is a diagram for explaining a step of bending the hook of the commutator piece in the commutator manufacturing method according to the embodiment.

In the above-mentioned manufacturing method, after performing the step of arranging the plurality of commutator pieces 30M in the basket 100, the step of roughening at least a part of the surface of each of the plurality of commutator pieces 30M was performed. However, it is not limited to this.

For example, after performing a step of roughening at least a part of the surface of each of the plurality of commutator pieces 30M, a step of arranging the plurality of commutator pieces 30M in the basket 100 may be performed. In this case, a plurality of commutator pieces 30M are arranged in the basket 100 so that the roughened surface faces inward. That is, after roughening the back surface 31c and the buried surface 32c of the commutator piece 30M by roughening by etching or the like, a plurality of commutator pieces 30M are basketd so that the back surface 31c and the buried surface 32c face inward. Place at 100.

When the commutator piece 30M is roughened first, only the back surface 31c and the buried surface 32c of the commutator piece 30M are roughened without roughening the front surface 31a and the side surface 31b of the commutator piece 30M. It is good to change. For example, when roughening by etching, the front surface 31a and the side surface 31b of the commutator piece 30M are masked and an etching solution is applied to selectively roughen only the back surface 31c and the buried surface 32c of the commutator piece 30M. It can be surfaced.

As described above, the method for manufacturing the commutator 14 of the present embodiment includes a plurality of resin molded bodies 20 having a through hole 21 into which the commutator 13 of the electric motor 2 is inserted and a plurality of commutators 14 arranged in an annular shape around the commutator 13. A method of manufacturing a commutator 14 including the commutator piece 30M of the above, wherein a plurality of commutator pieces 30M are arranged in an annular shape in a tubular basket 100, and a surface of each of the plurality of commutator pieces 30M. The plurality of commutator pieces 30M were fixed by the step of roughening at least a part of the surface and by injecting a liquid resin into the inner peripheral portion of the basket 100 in which the plurality of commutator pieces 30M were arranged and curing the liquid resin. The step of forming the resin molded body 20 is included.

This makes it possible to prevent the commutator piece from floating when the commutator rotates, while suppressing the occurrence of another problem.

Further, after performing the step of arranging the plurality of commutator pieces 30M in the basket 100, a step of roughening at least a part of the surface of each of the plurality of commutator pieces 30M may be included.

Further, each of the plurality of commutator pieces 30M is exposed from the contact surface 31c in contact with the outer peripheral surface of the resin molded body 20 and the resin molded body 20, and faces the adjacent commutator pieces 30M among the plurality of commutator pieces 30M. In the step of roughening the commutator piece 30M having the facing surface 31b, only the contact surface 31c of the contact surface 31c and the facing surface 31b may be roughened by performing the roughening treatment.

Further, the basket 100 may be made of resin.

In the present embodiment, the commutator 14 is manufactured by the basket construction method using the basket 100. However, it is not limited to this.

For example, the commutator 14 may be manufactured by an undercut method that does not use the basket 100. When the commutator 14 is manufactured by the undercut method, the commutator 14 can be manufactured by the flow shown in FIG. FIG. 13 is a flowchart of another commutator manufacturing method (undercut method) according to the embodiment.

In this case, first, a tubular commutator base material serving as a base material for the plurality of commutator pieces 30 is produced (step S21). Specifically, a cylindrical commutator base material made of a metal material such as copper is produced.

Next, at least a part of the surface of the commutator base material is roughened (step S22). Specifically, the surface of the surface of the commutator base material corresponding to the back surface 31c and the buried surface 32c of the commutator piece 30 is roughened by etching or the like.

Next, a resin molded body is formed by resin molding (step S23). Specifically, a resin molded body to which the commutator base material is fixed is formed by injecting a liquid resin into the inner peripheral portion of a cylindrical commutator base material whose surface is partially roughened and hardening the liquid resin. Form.

Next, the commutator base material is separated into a plurality of commutator pieces 30 (step S24). Specifically, by forming a slit in the commutator base material with a metal saw, the commutator base material to which the resin molded body is fixed is separated into a plurality of commutator pieces 30.

After that, the commutator 14 can be completed by sequentially performing the annealing treatment (step S17), the surface processing, and the hook bending (step S18) in the same manner as in the above embodiment (step S19).

As described above, in another method of manufacturing the commutator 14 of the present embodiment, the resin molded body 20 having the through hole 21 inserted into the rotating shaft 13 of the electric motor 2 and the rotating shaft 13 are arranged in an annular shape. A method for manufacturing a commutator 14 including a plurality of commutator pieces 30M, wherein at least a part of the surface of a tubular commutator base material serving as a base material for the plurality of commutator pieces 30M is roughened. The process of forming the resin molded body 20 to which the commutator base material is fixed by injecting a liquid resin into the inner peripheral portion of the commutator base material and curing it, and the process of forming the commutator base material into a plurality of commutators. Includes a step of separating into pieces.

[Action effect]
Next, the action and effect of the commutator 14 according to the present embodiment will be described including the background to the present disclosure.

As described above, conventionally, in order to prevent the commutator piece from floating when the commutator rotates, a technique for roughening the contact surface of the commutator piece with the resin molded body has been proposed.

However, when I actually made a commutator with the entire surface of the commutator piece roughened, it was found that another problem occurred.

For example, if the entire surface of the commutator piece is roughened, the side surface of the commutator piece (the surface facing the adjacent commutator) is also roughened. In this case, if the depth of the minute irregularities on the surface of the commutator piece becomes too large due to the roughening, when the commutator is manufactured by the basket method, when the commutator piece is placed in the basket and resin molding is performed, There was a problem that liquid resin leaked from the gap between the side surface of the commutator piece and the basket.

As a result of diligent studies on such problems, the inventors of the present application have obtained the idea of selectively roughening the surface of the commutator piece instead of roughening the entire surface of the commutator piece. rice field. Specifically, I got the idea that the surface of the commutator piece is partially formed with minute recesses so that the maximum depth of the minute recesses is partially different.

In the commutator 14 of the present embodiment, in each commutator piece 30, the maximum depth of the surface minute recesses on the back surface 31c and the buried surface 32c, which are the contact surfaces with the resin molded body 20, is the adjacent commutator pieces 30. It is deeper than the maximum depth of the minute recesses on the surface of the side surface 31b, which is the facing surface facing the surface.

With this configuration, the depth of the minute recess is reduced on the side surface 31b of the commutator piece 30. Therefore, as described above, when the commutator 14 is manufactured by the basket construction method, when the commutator piece 30M is arranged in the basket 100 and resin is molded, the side surface 31b of the commutator piece 30M and the convex portion 120 of the basket 100 It is possible to prevent the liquid resin from leaking from the gap between the two. That is, the back surface 31c and the buried surface 32c, which are the contact surfaces with the resin molded body 20, are rectified while increasing the depth of the minute recesses to increase the joint strength between the resin molded body 20 and the rectifying element 30. With respect to the side surface 31b of the child piece 30, the depth of the minute recesses can be reduced to suppress resin leakage during resin molding of the resin molded body 20. As a result, it is possible to prevent the commutator piece 30 from floating when the commutator 14 is rotated, while suppressing the occurrence of a problem of resin leakage during resin molding. When resin leakage occurs, (1) it becomes difficult to separate the basket 100 from the commutator piece 30, (2) the posture of the commutator piece 30 deteriorates, and (3) resin leakage occurs when the motor is driven. It causes problems such as damage to the brush due to the resin that has been derived and cured.

In the commutator 14 of the present embodiment, in the commutator piece 30, the maximum depth of the surface minute recesses on the back surface 31c and the buried surface 32c, which are the contact surfaces with the resin molded body 20, is the contact surface with the brush 15. It is deeper than the maximum depth of the minute recesses on the surface of a certain front surface 31a.

In the commutator 14 of the present embodiment, as shown in FIG. 4C, the length (W1) of the plurality of commutator pieces 30 along the circumferential direction on the outer peripheral side at the distance between two adjacent commutator pieces 30. ) Is longer than the length (W2) along the circumferential direction on the inner peripheral side at the interval. Specifically, between two adjacent commutator pieces 30, the length on the outer peripheral side is longer than the length on the inner peripheral side.

With this configuration, it is possible to further suppress the commutator piece 30 from floating when the commutator 14 rotates. This point will be described below.

The mold commutator is manufactured by resin molding. In this case, a plurality of commutator pieces are arranged in a ring shape on a mold for transfer molding, and a liquid thermosetting resin is injected into the mold with the plurality of commutator pieces fixed to the mold to form a plurality of commutators. By curing the liquid thermosetting resin inside the piece, it is possible to manufacture a molded commutator having a structure in which a part of each of the plurality of commutator pieces is embedded in the resin molded body. In addition to transfer molding, a mold commutator can be manufactured by injection molding.

At this time, if the commutator piece is fixed with a mold so that the commutator piece does not move and resin molding is performed, the liquid thermosetting resin injected into the mold is cured and molded as a resin molded body. , The liquid thermosetting resin injected into the inside of the plurality of commutator pieces shrinks in the direction opposite to the commutator one side (that is, inward in the radial direction). As a result, the commutator piece located outside the resin molded body and the resin molded body are separated from each other, and a gap occurs at the interface between the commutator piece and the resin molded body. Therefore, even if the surface of the commutator piece is roughened, it may not be possible to sufficiently suppress the commutator piece from floating when the rotor rotates.

On the other hand, in the commutator 14 in the present embodiment, the length on the outer peripheral side is longer than the length on the inner peripheral side between the two adjacent commutator pieces 30.

With this configuration, when the commutator 14 is manufactured by the basket construction method, when the liquid resin is injected into the inside of the plurality of commutator pieces 30M arranged in the basket 100 and the resin molded body 20 is resin-molded, the above-mentioned As described above, the commutator piece 30M arranged in the recess 110 of the basket 100 is not fixed to the recess 110 of the basket 100, but is held in the recess 110 in a movable state. Therefore, the commutator piece 30M arranged in the recess 110 of the basket 100 can move inward in the radial direction as the resin shrinks. As a result, the resin molded body 20 and the commutator piece 30M are not separated from each other, so that the resin molded body 20 and the commutator piece 30M can be firmly joined. Therefore, it is possible to further suppress the commutator piece 30 from floating when the commutator 14 is rotated.

At the base of the buried portion 32 on the exposed portion 31 side, a constricted portion is formed in which a part of the buried portion 32 is constricted. By forming the constricted portion in the embedded portion 32 in this way, the resin constituting the resin molded body 20 enters the recess of the constricted portion. As a result, the bonding strength between the embedded portion 32 and the resin molded body 20 can be improved by the anchor effect of the constricted portion. Therefore, it is possible to further prevent the commutator piece 30 from floating from the resin constituting the resin molded body 20 when the rotor 11 rotates.

As described above, according to the commutator 14 according to the present embodiment, it is possible to suppress the commutator piece 30 from floating when the commutator 14 is rotated, while suppressing the occurrence of the above-mentioned other trouble.

Further, since the electric motor 2 according to the present embodiment includes the commutator 14, it is possible to provide an electric motor having high reliability.

[Example]
Hereinafter, the commutator 14 of the actually manufactured example will be described.

FIG. 14 shows a cross-sectional SEM (Scanning Electron Microscope) image (5000 times) at the contact interface between the resin molded body 20 and the commutator piece 30 with respect to the commutator 14 actually manufactured by the manufacturing method using the above basket method. It is a figure which shows. Specifically, a cross-sectional SEM image at the contact interface between the back surface 31c of the exposed portion 31 of the commutator piece 30 and the outer peripheral surface of the resin molded body 20 is shown.

As shown in FIG. 14, it can be seen that the back surface 31c of the exposed portion 31 of the commutator piece 30 is roughened by etching in the roughening process. In FIG. 14, it can be seen that the back surface 31c of the commutator piece 30 is formed with an uneven portion having a minute recess having a maximum depth of about several μm.

Although FIG. 14 shows the surface state of the exposed portion 31 of the commutator piece 30 on the back surface 31c, the buried surface 32c of the buried portion 32 of the commutator piece 30 is also etched and roughened in the same manner as the back surface 31c. Since it was surfaced, the buried surface 32c also had a surface condition as shown in FIG.

Further, since the strength of the commutator actually manufactured was evaluated, the evaluation result will be described with reference to FIG.

FIG. 15 is a diagram for explaining the strength of the commutator of the embodiment. In FIG. 15, Example 1 is a commutator 14 manufactured by an undercut method. Examples 2, 3 and 4 are commutators 14 produced by the basket construction method. In Examples 2, 3 and 4, the depth of unevenness of the minute recesses on the back surface 31c and the buried surface 32c was changed by adjusting the time of immersion in the etching solution 200 when performing the roughening treatment by etching. In this case, the unevenness depth can be increased by lengthening the time of immersion in the etching solution 200. On the other hand, a comparative example is a commutator manufactured by the basket method without performing roughening treatment (etching treatment).

In Examples 1 to 4, when the roughening treatment (etching treatment) is performed, the back surface 31c and the buried surface of the back surface 31c and the buried surface 32c and the front surface 31a and the side surface 31b of the commutator piece 30 are described as described above. Only 32c was selectively roughened. As the commutator piece of each commutator, a commutator piece made of a copper alloy was used.

For the commutators of Examples 1 to 4 that had been roughened, the unevenness depth of the commutator pieces was measured. The unevenness depth of each commutator was calculated as follows. Specifically, as a sample cross section of the contact surface of the commutator piece with the resin molded body, cross-sectional SEM images of 10 areas are discretely acquired, and each of the 10 areas is obtained based on the cross-sectional SEM image. The maximum depth of the minute recesses (see FIG. 14) was measured, the average value of the maximum depths of the 10 areas was calculated, and the average value was taken as the unevenness depth of each commutator. As a result, as shown in FIG. 15, the uneven depths of the commutators of Examples 1, 2, 3 and 4 were 20 μm, 5 μm, 10 μm and 20 μm, respectively.

In addition, the strength of each of these commutators was measured and evaluated relatively. Specifically, the load required to extrude the resin molded body 20 and separate the resin molded body and the commutator piece was measured, and the load was evaluated as the strength of each commutator. In FIG. 15, the intensity of the commutator of Example 4 is set to 1, and the intensities of the commutators of Comparative Examples and Examples 1 to 3 are standardized and shown relatively.

As a result, as shown in FIG. 15, the commutators of Examples 1 to 4 can obtain higher strength than the commutators of Comparative Examples, and the commutator pieces are less likely to be separated from the resin molded body. I found out. That is, by selectively roughening only the back surface 31c and the buried surface 32c of the back surface 31c and the buried surface 32c and the front surface 31a and the side surface 31b of the commutator piece 30, the commutator piece 30 can be removed from the resin molded body 20. A commutator 14 that is difficult to separate can be obtained.

It can be seen that the commutator of the second embodiment has the same strength as the commutator of the first embodiment even though the unevenness depth is smaller than that of the commutator of the first embodiment. It can be seen that the commutator of Example 4 has more than twice the strength of the commutator of Example 1. This is because the commutator is manufactured by the basket method, so that the commutator piece moves inward in the radial direction as the resin shrinks during resin molding of the resin molded body, and the resin molded body and the commutator piece do not separate from each other. It is considered that this is because they are firmly joined. That is, by manufacturing the commutator by the basket method instead of the undercut method, it is possible to obtain a commutator that can effectively suppress the floating of the commutator piece.

As can be seen from the commutators of Examples 2 to 4, when the commutator is manufactured by the basket method, a commutator having high strength can be obtained by setting the unevenness depth of the commutator piece to 10 μm or more. can. Specifically, the commutator of the third embodiment can obtain about twice the strength by doubling the unevenness depth as compared with the commutator of the second embodiment. Although the commutator of No. 4 has twice the unevenness depth as that of the commutator of Example 3, only the same strength as that of the commutator of Example 3 is obtained. That is, when the unevenness depth is 10 μm or more, the strength of the commutator is not proportional to the unevenness depth of the commutator piece and is saturated. Therefore, when the commutator is manufactured by the basket method, it is better that the uneven depth of the commutator piece is 10 μm or more.

(Modification example)
The commutator and the motor or the like including the commutator according to the present disclosure have been described above based on the embodiment, but the present disclosure is not limited to the above embodiment.

For example, in the above embodiment, as the commutator piece 30M arranged in the basket 100, a commutator piece 30M in which the connecting portion between the wide portion and the narrow portion in the exposed portion 31 is at a right angle is used, but the present invention is not limited to this. For example, as in the commutator piece 30MA shown in FIGS. 16A and 16B, a commutator piece 30MA in which the connecting portion 34 between the wide portion and the narrow portion in the exposed portion 31 is curved and marked with R may be used. FIG. 16A is a perspective view of another commutator piece (state before hook bending) used in the commutator manufacturing method according to the embodiment. FIG. 16B is a side view of the commutator piece shown in FIG. 16A. This makes it easier to insert the commutator piece 30MA into the recess 110 of the basket 100.

Further, in the above embodiment, the commutator 14 is attached to the second portion 13b of the rotating shaft 13, but the present invention is not limited to this. For example, the commutator 14 may be attached to the first portion 13a of the rotating shaft 13. In this case, the commutator 14 is attached to, for example, a portion of the rotating shaft 13 between the rotor core 11a and the first bearing 16.

Further, the electric blower 1 in the above embodiment can be used for, for example, a vacuum cleaner, an air towel, or the like. Further, the electric blower 1 is not limited to a vacuum cleaner or an air towel, and may be applied to automobile equipment, or may be applied to other household equipment or industrial equipment.

Further, in the above embodiment, the case where the motor 2 is used for the electric blower 1 has been described, but the present invention is not limited to this. The electric motor 2 may be used for an electric device other than the electric blower. In this case, the motor 2 can be used for various products such as household equipment or industrial equipment.

In addition, it is realized by arbitrarily combining the components and functions in each embodiment within the range obtained by applying various modifications to the above-described embodiment and not deviating from the purpose of the present disclosure. Forms are also included in this disclosure.

The technology of the present disclosure can be used as a commutator for a commutator motor. The technique of the present disclosure can be widely used not only for commutators but also for various electric devices such as electric motors equipped with commutators, electric blowers equipped with electric motors, and vacuum cleaners equipped with electric blowers.

1 Electric blower 2 Motor 3 Rotating fan 4 Air guide 5 Fan case 5a Intake port 6 Frame 6a Exhaust port 7 Bracket 11 Rotor 11a Rotor iron core 11b Winding coil 12 Stator 13 Rotating shaft 13a First part (output shaft)
13b 2nd part (anti-output shaft)
14 Commutator 15 Brush 16 1st bearing 17 2nd bearing 20 Resin molded body 21 Through holes 30, 30M, 30MA Commutator piece 31 Exposed part 31a Front surface 31b Side surface (opposing surface)
31c back (contact surface)
32 Buried part 32c Buried surface 33 Hook part 100 Basket 110 Concave part 120 Convex part 200 Etching liquid

Claims (9)

1. Resin molded body and
   A plurality of commutator pieces fixed to the resin molded body are provided.
   Each of the plurality of commutator pieces
   A contact surface in contact with the outer peripheral surface of the resin molded body and
   It has a facing surface that is exposed from the resin molded body and faces the adjacent commutator piece among the plurality of commutator pieces.
   The maximum depth of the surface micro-recesses on the contact surface is deeper than the maximum depth of the surface micro-recesses on the facing surface.
   Commutator.
2. The resin molded body has a through hole into which the rotating shaft of the motor is inserted.
   The commutator piece has a front surface in contact with the brush of the motor.
   The maximum depth of the surface micro-recesses on the contact surface is deeper than the maximum depth of the surface micro-recesses on the front surface.
   The commutator according to claim 1.
3. The length along the circumferential direction on the outer peripheral side in the distance between two adjacent commutator pieces among the plurality of commutator pieces is longer than the length along the circumferential direction on the inner peripheral side in the distance.
   The commutator according to claim 1 or 2.
4. The commutator according to any one of claims 1 to 3 and
   A rotor having a rotating shaft to which the commutator is attached, and a rotor
   The stator includes a stator that generates a magnetic force acting on the rotor.
   Electric motor.
5. A method for manufacturing a commutator including a resin molded body having a through hole into which a rotating shaft of an electric motor is inserted and a plurality of commutator pieces arranged in an annular shape around the rotating shaft.
   The process of arranging the plurality of commutator pieces in a tubular basket in an annular shape, and
   A step of roughening at least a part of the surface of each of the plurality of commutator pieces, and
   The step includes a step of forming the resin molded body to which the plurality of commutator pieces are fixed by injecting a liquid resin into the inner peripheral portion of the basket in which the plurality of commutator pieces are arranged and curing the liquid resin. ,
   How to manufacture a commutator.
6. After performing the step of arranging the plurality of commutator pieces in the basket, the step of roughening at least a part of the surface of each of the plurality of commutator pieces is included.
   The method for manufacturing a commutator according to claim 5.
7. Each of the plurality of commutator pieces has a contact surface in contact with the outer peripheral surface of the resin molded body and a facing surface exposed from the resin molded body and facing an adjacent commutator piece among the plurality of commutator pieces. Have,
   In the step of roughening the commutator piece, only the contact surface among the contact surface and the facing surface is roughened by performing a roughening process.
   The method for manufacturing a commutator according to claim 6.
8. The basket is made of resin.
   The method for manufacturing a commutator according to any one of claims 5 to 7.
9. A method for manufacturing a commutator including a resin molded body having a through hole inserted into a rotating shaft of an electric motor and a plurality of commutator pieces arranged in an annular shape around the rotating shaft.
   A step of roughening at least a part of the surface of the tubular commutator base material which is the base material of the plurality of commutator pieces, and
   A step of forming the resin molded body to which the commutator base material is fixed by injecting a liquid resin into the inner peripheral portion of the commutator base material and curing the resin.
   A step of separating the commutator base material into the plurality of commutator pieces is included.
   How to manufacture a commutator.

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