WO2021070458A1

WO2021070458A1 - Electric motor and electrical apparatus

Info

Publication number: WO2021070458A1
Application number: PCT/JP2020/029866
Authority: WO
Inventors: 圭策中野; 和雄遠矢; 知子従野; 貴洋浅野
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2019-10-09
Filing date: 2020-08-04
Publication date: 2021-04-15
Also published as: CN114223116A; JPWO2021070458A1

Abstract

This electric motor comprises: a rotor having a rotating shaft, a commutator attached to the rotating shaft, an energizing brush in contact with the commutator, and an auxiliary brush in contact with the commutator, wherein the commutator has a plurality of commutator segments provided along the circumferential direction of the rotating shaft, the energizing brush and the auxiliary brush are electrically connected to each other via a non-linear element, the auxiliary brush is disposed so as to be in contact with a commutator segment immediately after the energizing brush is separated, among the plurality of commutator segments, when the plurality of commutator segments rotate around the rotating shaft, and the breakdown voltage of the non-linear element is higher than the voltage between two adjacent commutator segments among the plurality of commutator segments, and is less than or equal to an arc voltage in a spark generated between the energizing brush and the commutator segment immediately after the energizing brush is separated among the plurality of commutator segments.

Description

Electric motors and electrical equipment

This disclosure relates to electric motors and electrical equipment.

Electric motors are used in various products such as electric blowers installed in vacuum cleaners. As an electric motor, a commutator electric motor (commutator motor) that uses a brush and a commutator, or a brushless electric motor that does not use a brush and a commutator is known.

The commutator motor includes, for example, a stator, a rotor, a commutator attached to the rotating shaft of the rotor, and an energizing brush that is in sliding contact with the commutator. The commutator has a plurality of commutator segments provided at equal intervals along the circumferential direction of the rotation axis of the rotor. A winding coil wound around the core of the rotor is electrically connected to each of the plurality of commutator segments.

In this commutator motor, the energizing brush and commutator are used to energize the winding coil of the rotor. In this case, when the winding coil that is energized by the rotation of the commutator is switched (that is, at the moment when the energizing brush separates from the commutator segment), a spark (also called spark) is generated between the energizing brush and the commutator segment. I have something to do. When sparks occur, the energizing brush wears faster. This reduces the life of the motor.

Therefore, conventionally, in order to suppress the generation of sparks and extend the life of the energizing brush, an auxiliary brush is provided in addition to the energizing brush, and an electronic component for absorbing the arc voltage in the spark is connected to the auxiliary brush. Have been proposed (see, for example, Patent Documents 1 and 2). Specifically, in the commutator motor disclosed in

Patent Documents

1 and 2, the energizing brush and the auxiliary brush are connected via a Zener diode.

However, with the configurations disclosed in

Patent Documents

1 and 2, it may not be possible to sufficiently suppress the spark generated between the energizing brush and the commutator segment.

Japanese Unexamined Patent Publication No. 52-54903 JP-A-2017-192233

This disclosure is made to solve such problems. It is an object of the present disclosure to provide an electric motor capable of suppressing a spark generated between an energizing brush and a commutator segment, and an electric device including the electric motor.

In order to achieve the above object, one aspect of the electric motor according to the present disclosure includes a rotor having a rotating shaft, a commutator attached to the commutator, an energizing brush in contact with the commutator, and an auxiliary brush in contact with the commutator. , The commutator has a plurality of commutator segments provided along the circumferential direction of the axis of rotation, and the energizing brush and the auxiliary brush are electrically connected via a non-linear element to assist. When a plurality of commutator segments rotate around the axis of rotation, the brush is arranged so as to be in contact with the commutator segment immediately after the energizing brush is separated from the plurality of commutator segments. In a spark that is higher than the voltage between two adjacent commutator segments in a plurality of commutator segments and is generated between the commutator segment and the energizing brush immediately after the energizing brush is separated from the plurality of commutator segments. It is below the arc voltage.

Further, one aspect of the electric device according to the present disclosure is the one using the above-mentioned electric motor.

According to the present disclosure, it is possible to suppress the spark generated between the energizing brush and the commutator segment.

It is sectional drawing of the electric motor which concerns on embodiment. It is a figure which shows the circuit structure for suppressing the occurrence of the spark in the electric motor which concerns on embodiment. It is a figure for demonstrating the principle of spark generation. It is a figure for demonstrating the principle of spark generation. It is a figure which shows the voltage and current between an energizing brush and a commutator segment in the electric motor of an experimental example. It is a figure for demonstrating the principle for suppressing the occurrence of a spark in the electric motor which concerns on embodiment. It is a figure for demonstrating the principle for suppressing the occurrence of a spark in the electric motor which concerns on embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The embodiments described below are specific examples 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 are described as arbitrary components.

Note that each figure is a schematic view and is not necessarily exactly illustrated. Further, in each figure, the same reference numerals are given to substantially the same configurations, and duplicate description will be omitted or simplified.

(Embodiment)
First, the configuration of the electric motor 1 according to the embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view of the electric motor 1 according to the embodiment. FIG. 2 is a diagram showing a circuit configuration for suppressing the generation of sparks in the electric motor 1. In FIG. 2, thin black arrows indicate current flow.

The electric motor 1 is a commutator electric motor. As shown in FIGS. 1 and 2, the electric motor 1 includes a stator 10, a rotor 20, a commutator 30, an energizing brush 40, an auxiliary brush 50, and a frame 60 for accommodating the stator 10 and the rotor 20. .. The rotor 20 is rotated by the magnetic force of the stator 10. The commutator 30 is attached to the shaft 21 of the rotor 20. The energizing brush 40 comes into contact with the commutator 30. The auxiliary brush 50 contacts the commutator 30. The frame 60 houses the stator 10 and the rotor 20.

The electric motor 1 is a DC motor (DC motor) driven by direct current. In the electric motor 1, a magnet 11 is used as the stator 10, and an armature having a winding coil 22 is used as the rotor 20.

The electric motor 1 can be used for various electric devices. For example, the electric motor 1 can be used for an electric blower mounted on a vacuum cleaner, an air towel, or the like. Further, the electric motor 1 can also be used for an electric device, an electric tool, or the like mounted on an automobile.

Hereinafter, each component of the electric motor 1 will be described in detail.

The stator 10 (stator) generates a magnetic force acting on the rotor 20. The stator 10 constitutes a magnetic circuit together with the rotor 20 which is an armature. The stator 10 has a plurality of magnetic poles. Specifically, the stator 10 is configured such that N poles and S poles alternately exist on the air gap surface with the rotor 20 along the circumferential direction of the shaft 21. The stator 10 is composed of a plurality of magnets 11 (magnets). The magnet 11 is a field magnet that creates a magnetic flux for generating torque. The magnet 11 is, for example, a permanent magnet having an S pole and an N pole.

The plurality of magnets 11 constituting the stator 10 are arranged so that the north and south poles are alternately and evenly present along the circumferential direction of the shaft 21. Therefore, the direction of the main magnetic flux generated by the stator 10 (magnet 11) is a direction orthogonal to the direction of the axis C of the shaft 21. The plurality of magnets 11 are arranged at equal intervals along the circumferential direction so as to surround the rotor 20. The plurality of magnets 11 are located on the outer peripheral side of the rotor core 23 in the radial direction of the rotor 20. Specifically, a plurality of magnets 11 in which the north pole and the south pole are magnetized are arranged so that the center of the magnetic pole of the north pole and the center of the magnetic pole of the south pole are evenly spaced along the circumferential direction.

As an example, each of the plurality of magnets 11 has an arc shape having a substantially constant thickness when viewed from above. The plurality of magnets 11 are fixed to the frame 60. Specifically, each magnet 11 is adhesively fixed to the inner peripheral surface of the frame 60.

The rotor 20 (rotor) generates a magnetic force acting on the stator 10. The direction of the main magnetic flux generated by the rotor 20 is a direction orthogonal to the direction of the axis C of the shaft 21. The rotor 20 rotates around the shaft 21 by the magnetic force of the stator 10.

The rotor 20 is an inner rotor and is arranged inside the stator 10. Specifically, the rotor 20 is surrounded by a plurality of magnets 11 constituting the stator 10. The rotor 20 is arranged with the stator 10 via an air gap. Specifically, there is a minute air gap between the outer peripheral surface of the rotor 20 and the inner surface of each magnet 11.

The rotor 20 has a shaft 21. The rotor 20 is an armature. The rotor 20 has a winding coil 22 and a rotor core 23.

The shaft 21 is a rotating shaft having an axis C. The shaft 21 is a long rod-shaped member that serves as a center when the rotor 20 rotates. The longitudinal direction (extension direction) of the shaft 21 is the direction of the axis C (axis direction). The shaft 21 is rotatably held by a bearing such as a bearing. Although details are not shown, for example, the first end 21a, which is one end of the shaft 21, is supported by a first bearing held by a bracket fixed to the frame 60 or directly held by the frame 60. There is. The second end 21b, which is the other end of the shaft 21, is supported by a second bearing held by a bracket fixed to the frame 60 or directly held by the frame 60. The bracket is fixed to the frame 60 so as to cover the opening of the frame 60, for example.

The shaft 21 is fixed to the center of the rotor 20. The shaft 21 is, for example, a metal rod. The shaft 21 is fixed to the rotor core 23 so as to penetrate the rotor core 23. For example, the shaft 21 is fixed to the rotor core 23 by press-fitting or shrink-fitting into the center hole of the rotor core 23.

The winding coil 22 (rotor coil) is wound so as to generate a magnetic force acting on the stator 10 when an electric current flows. The winding coil 22 is wound around the rotor core 23 via the insulator 24. Specifically, the winding coil 22 has a main coil wound around each of the plurality of teeth of the rotor core 23. The main coil is provided for each slot of the rotor 20.

The winding coil 22 is electrically connected to the commutator 30. Specifically, the winding coil 22 is electrically connected to the commutator segment 31 of the commutator 30. When a current flows through the winding coil 22 via the commutator 30, the rotor 20 generates a magnetic force acting on the stator 10.

In addition to the main coil, the winding coil 22 includes a crossover wire that connects the commutator segments 31 to each other and electrically connects them. The crossover is integrally formed with the main coil. That is, the crossover wire and the main coil are one continuous conductive wire without being cut in the middle. In this case, the crossover wire may be a portion of one conductive wire that connects two adjacent main coils, or may be a portion before the main coil starts to be wound, or the main coil. It may be the part after the winding is finished. The crossover wire and the main coil may not be one continuous conductive wire, but may be a separate conductive wire connected by the commutator segment 31 or the like.

The rotor core 23 is an armature core around which the winding coil 22 is wound. The rotor core 23 is, for example, a laminated body in which a plurality of punched electrical steel plates formed in a predetermined shape are laminated in the direction of the axis C of the shaft 21. The rotor core 23 is not limited to a laminated body of electromagnetic steel sheets, and may be a bulk body made of a magnetic material. There is a minute air gap between the outer peripheral surface of the rotor core 23 and the inner surface of each magnet 11 of the stator 10.

The rotor core 23 has a plurality of teeth. The plurality of teeth extend in a direction (radial direction) orthogonal to the axis C of the shaft 21 in a direction away from the rotation axis. The plurality of teeth are present at equal intervals along the rotation direction of the shaft 21.

The commutator 30 is attached to the shaft 21. Therefore, the commutator 30 rotates together with the shaft 21 as the rotor 20 rotates. The commutator 30 is attached to the first end 21a of the shaft 21.

The commutator 30 has a plurality of commutator segments 31. As shown in FIG. 2, the plurality of commutator segments 31 are provided along the circumferential direction of the shaft 21. Specifically, the plurality of commutator segments 31 are arranged in an annular shape at equal intervals so as to surround the shaft 21. In this embodiment, the commutator 30 has twelve commutator segments 31.

Each of the plurality of commutator segments 31 is a commutator piece extending in the longitudinal direction of the shaft 21. Each of the plurality of commutator segments 31 is a conductive terminal made of a metal material such as copper. Each of the plurality of commutator segments 31 is electrically connected to the winding coil 22 of the rotor 20. As an example, the commutator 30 is a mold commutator. As shown in FIG. 1, the commutator 30 has a configuration in which a plurality of commutator segments 31 are resin-molded. In this case, the plurality of commutator segments 31 are embedded in the mold resin 32 so that the surface is exposed. The plurality of commutator segments 31 may be electrically connected to each other by a pressure equalizing wire so as to have the same potential (equalizing pressure).

As shown in FIG. 2, the commutator 30 is in contact with the energizing brush 40 and the auxiliary brush 50. Specifically, the energizing brush 40 and the auxiliary brush 50 are in sliding contact with the commutator segment 31 of the commutator 30. Although not shown, the energizing brush 40 and the auxiliary brush 50 are slidably held by the brush holder. For example, the energizing brush 40 and the auxiliary brush 50 are housed in the storage portion of the brush holder. In this case, the energizing brush 40 and the auxiliary brush 50 slide inside the storage portion of the brush holder. Further, although not shown, the electric motor 1 is provided with a brush spring such as a coil spring or a torsion spring in order to press the energizing brush 40 and the auxiliary brush 50 against the commutator 30. The brush spring applies pressure to the energizing brush 40 and the auxiliary brush 50 by utilizing the elasticity of the spring. Each of the energizing brush 40 and the auxiliary brush 50 is in a state where the surface of the tip portion is always in contact with the commutator segment 31 of the commutator 30 under the pressing force from the brush spring. The surface on which each of the energizing brush 40 and the auxiliary brush 50 and the commutator segment 31 slide is a sliding surface. The brush spring is provided for each energizing brush 40 and for each auxiliary brush 50, but the present invention is not limited to this.

The energizing brush 40 and the auxiliary brush 50 are conductive conductors. As an example, the energizing brush 40 and the auxiliary brush 50 are long, substantially rectangular parallelepiped carbon brushes made of carbon. Specifically, the energizing brush 40 and the auxiliary brush 50 are carbon brushes containing a metal such as copper. For example, the energizing brush 40 and the auxiliary brush 50 can be produced by crushing a kneaded product obtained by kneading graphite powder, copper powder, a binder resin, and a curing agent, compression molding into a rectangular parallelepiped, and firing. In this case, the energizing brush 40 and the auxiliary brush 50 may be metallic graphite brushes containing a large amount of metal components such as copper (for example, 30% metal components and 70% carbon components), or have rubber elasticity. It may be a resin brush in which the characteristics of the resin remain (for example, the resin component is 20% and the carbon component is 80%).

The energizing brush 40 is a power feeding brush that supplies electric power to the rotor 20 by coming into contact with the commutator 30. Specifically, the tip portion of the energizing brush 40 comes into contact with the commutator segment 31 of the commutator 30. Therefore, the energizing brush 40 is connected to an electric wire through which a current supplied from a power source 70 provided outside the electric motor 1 flows. For example, the energizing brush 40 is electrically connected to an electrode terminal that receives electric power from the power source 70 via an electric wire such as a pigtail wire. Specifically, the other end of the pigtail wire whose one end is connected to the electrode terminal is connected to the rear end of the energizing brush 40, and the energizing brush 40 comes into contact with the commutator segment 31. , The armature current supplied to the energizing brush 40 via the pigtail wire flows through each winding coil 22 of the rotor 20 via the commutator segment 31.

The energizing brush 40 is configured so that there is a state in which the energizing brush 40 is in contact with the two adjacent commutator segments 31. That is, the width of the energizing brush 40 in the rotation direction of the rotor 20 is larger than the length of the distance between the two adjacent commutator segments 31. As a result, the energizing brush 40 can short-circuit the winding coil 22 connected between the two commutator segments 31. For example, as shown in FIG. 2, when one energizing brush 40 is in contact with both of two adjacent commutator segments 31, the winding coil 22 connected to these two commutator segments 31 is short-circuited. ..

A plurality of energizing brushes 40 are provided. Each of the plurality of energizing brushes 40 is in contact with the commutator 30. Specifically, the plurality of energizing brushes 40 include a first energizing brush 41 and a second energizing brush 42 as a pair of energizing brushes 40. The first energizing brush 41 and the second energizing brush 42 are arranged so as to sandwich the commutator 30. That is, the first energizing brush 41 and the second energizing brush 42 are arranged line-symmetrically about the axis C of the shaft 21. Each of the first energizing brush 41 and the second energizing brush 42 is in contact with the commutator segment 31 of the commutator 30 in a direction (radial direction) orthogonal to the axis C of the shaft 21. The first energizing brush 41 and the second energizing brush 42 are connected to the power supply 70. The power source 70 is a DC power source. The first energizing brush 41 is an anode side brush connected to the anode side (positive electrode side) of the power supply 70 which is a DC power supply, and the second energizing brush 42 is a cathode side (negative electrode side) of the power supply 70 which is a DC power supply. It is a cathode side brush connected to. As an example, the power supply 70 is a 12V DC power supply. In this case, the input voltage V _IN of the electric motor 1 becomes 12 V. That is, a DC voltage of 12 V is applied to the pair of energizing brushes 40.

The auxiliary brush 50 is a brush added to the energizing brush 40. Specifically, the auxiliary brush 50 is a spark suppressing brush for suppressing sparks generated by separating the energizing brush 40 and the commutator segment 31. The auxiliary brush 50 is arranged so as to be in contact with the commutator segment 31 immediately after the energizing brush 40 is separated from the plurality of commutator segments 31.

A plurality of auxiliary brushes 50 are arranged. Each of the plurality of auxiliary brushes 50 is in contact with the commutator 30. Specifically, the plurality of auxiliary brushes 50 include a first auxiliary brush 51 and a second auxiliary brush 52 as a pair of auxiliary brushes 50. Each of the first auxiliary brush 51 and the second auxiliary brush 52 is arranged so as to be in contact with the commutator segment 31 of the commutator 30.

Specifically, the first auxiliary brush 51 is arranged so as to be in contact with the commutator segment 31 immediately after the first energizing brush 41 is separated from the plurality of commutator segments 31. That is, the first auxiliary brush 51 is arranged so as to come into contact with the one commutator segment 31 when the first energizing brush 41 separates from the commutator segment 31 of one of the two adjacent commutator segments 31. ing. At this time, the first energizing brush 41 is the other commutator segment 31 of the two commutator segments 31 located behind the one commutator segment 31 in contact with the first auxiliary brush 51 in the rotation direction of the rotor 20. It touches the child segment 31.

Similarly, the second auxiliary brush 52 is arranged so as to be in contact with the commutator segment 31 immediately after the second energizing brush 42 is separated from the plurality of commutator segments 31. That is, the second auxiliary brush 52 is arranged so as to come into contact with the commutator segment 31 when the second energizing brush 42 separates from the commutator segment 31 of the two adjacent commutator segments 31. ing. At this time, the second energizing brush 42 is the other commutator segment 31 of the two commutator segments 31 located behind the one commutator segment 31 in contact with the second auxiliary brush 52 in the rotation direction of the rotor 20. It touches the child segment 31.

The energizing brush 40 and the auxiliary brush 50 are arranged on the same plane. Specifically, the energizing brush 40 and the auxiliary brush 50 are arranged on the same plane orthogonal to the direction of the axis C of the shaft 21. The first energizing brush 41, the second energizing brush 42, the first auxiliary brush 51, and the second auxiliary brush 52 are arranged on the same plane in the frame 60 without being displaced in the direction of the axis C of the shaft 21. There is.

The energizing brush 40 and the auxiliary brush 50 are electrically connected via a Zener diode 80. That is, the Zener diode 80 is connected between the energizing brush 40 and the auxiliary brush 50. The energizing brush 40, the auxiliary brush 50, and the Zener diode 80 are electrically connected by, for example, an electric wire such as a lead wire.

The Zener diode 80 is an example of a non-linear element having a breakdown voltage (Zener voltage) as a breakdown voltage. As the Zener diode 80, for example, a Zener diode 80 having a breakdown voltage of 3 V or 2.5 V can be used.

The Zener diode 80 functions as a spark suppression unit that suppresses sparks generated between the energizing brush 40 and the commutator segment 31. Specifically, a voltage is generated across the winding coil 22 by the counter electromotive force generated by the self-induction action of the winding coil 22 at the moment when the energizing brush 40 separates from the commutator segment 31. However, this voltage is applied in the opposite direction to the Zener diode 80. At this time, when a voltage larger than the breakdown voltage is applied to the Zener diode 80, a current flows from the anode to the cathode, and the voltage across the Zener diode 80 is maintained at the breakdown voltage. As a result, the voltage between the energizing brush 40 and the commutator segment 31 is maintained at a breakdown voltage lower than the voltage generated across the winding coil 22 by the counter electromotive force, so that the energizing brush 40 and the commutator segment 31 are maintained. Sparks generated between the segment 31 and the segment 31 can be suppressed.

In the present embodiment, a plurality of Zener diodes 80 are used as in the energizing brush 40 and the auxiliary brush 50. Specifically, the Zener diode 80 includes a first Zener diode 81 and a second Zener diode 82.

The first energizing brush 41 and the first auxiliary brush 51 are electrically connected via a first Zener diode 81. That is, the first Zener diode 81 is inserted in the wiring path between the first energizing brush 41 and the first auxiliary brush 51. Specifically, in the first Zener diode 81, the anode side terminal of the first Zener diode 81 is connected to the first auxiliary brush 51, and the cathode side terminal of the first Zener diode 81 is connected to the first energizing brush 41. There is. Therefore, the cathode side terminal of the first Zener diode 81 has the same potential as the anode of the power supply 70, which is a DC power supply.

Similarly, the second energizing brush 42 and the second auxiliary brush 52 are electrically connected via the second Zener diode 82. That is, the second Zener diode 82 is inserted in the wiring path between the second energizing brush 42 and the second auxiliary brush 52. Specifically, in the second Zener diode 82, the anode side terminal of the second Zener diode 82 is connected to the second energizing brush 42, and the cathode side terminal of the second Zener diode 82 is connected to the second auxiliary brush 52. There is. Therefore, the cathode side terminal of the second Zener diode 82 has the same potential as the cathode of the power source 70, which is a DC power source.

The first Zener diode 81 and the second Zener diode 82 may be built in the electric motor 1 or may be arranged outside the electric motor 1.

Next, the features of the electric motor 1 will be described, including the background to the present invention.

Conventionally, there has been known a technique for suppressing sparks generated between the energizing brush and the commutator segment by inserting a Zener diode between the energizing brush and the auxiliary brush. However, it has been found that the conventional configuration may not be able to sufficiently suppress the generation of sparks.

As a result of the examination by the present inventors, it was found that the generation of sparks may not be suppressed depending on the number of commutator segments, the input voltage of the electric motor, and the material of the energizing brush. That is, if the breakdown voltage of the Zener diode is not within a predetermined range according to the number of commutator segments, the input voltage of the motor, and the material of the energizing brush, it may not be possible to sufficiently suppress the generation of sparks. It turned out that there was.

Therefore, the present inventors have focused on the state at the time of spark generation and examined the optimum breakdown voltage of the Zener diode.

Here, first, the principle of spark generation will be described with reference to FIGS. 3A and 3B. 3A and 3B are diagrams for explaining the principle of spark generation. The electric motor shown in FIGS. 3A and 3B has a configuration in which the auxiliary brush 50 and the Zener diode 80 are not provided in the electric motor 1 shown in FIG.

As shown in FIG. 3A, when one energizing brush 40 is in contact with both the first commutator segment 31a and the second commutator segment 31b, which are two adjacent commutator segments 31, the first commutator The winding coil 22 inserted between the child segment 31a and the second commutator segment 31b is short-circuited.

When the commutator 30 rotates due to the rotation of the rotor 20 from this state, the state shown in FIG. 3B is obtained. That is, the energizing brush 40 is separated from the first commutator segment 31a and comes into contact with only the second commutator segment 31b located behind the first commutator segment 31a in the rotational direction.

At this time, at the moment when the first commutator segment 31a separates from the energizing brush 40, a counter electromotive force is generated by the self-induction action of the winding coil 22, and the recirculation voltage due to the counter electromotive force is the energizing brush 40 and the first commutator. It is applied between the child segment 31a and an arc discharge is generated. As a result, an arc voltage Va is generated between the energizing brush 40 and the first commutator segment 31a, and sparks are generated. That is, in this case, the first commutator segment 31a becomes a spark generator piece.

In examining the optimum breakdown voltage of the Zener diode, the present inventors experimentally measured the voltage and current between the energizing brush 40 and the commutator segment 31 when a spark occurred. The result is shown in FIG. FIG. 4 is a diagram showing the voltage and current between the energizing brush 40 and the commutator segment 31 in the electric motor of the experimental example, and shows the measured values.

Here, the electric motor of the experimental example used in this experiment has a configuration in which the auxiliary brush 50 and the Zener diode 80 are not provided in the electric motor 1 in the above embodiment, and other than that, the electric motor 1 in the above embodiment It has the same configuration. In this case, as the commutator segment 31, a commutator segment 31 made of copper was used. The total number of commutator segments 31 in the commutator 30 was 12. The power supply 70 was a DC power supply, and the power supply voltage (input voltage) was 12V. The energizing brush 40 was a first energizing brush 41 and a second energizing brush 42, both of which were metallic graphite brushes. Therefore, the current path from the first energizing brush 41 to the second energizing brush 42 is a parallel circuit in which two current paths passing through the six commutator segments 31 and the six winding coils 22 are connected in parallel. The voltage between the two commutator segments 31 that match (the voltage between the adjacent commutators) is 12V / 6 = 2V.

4, the data line L1 shows the voltage _{V B-S} between the current brush 40 and commutator segments 31. Specifically, the data line L1 shows the voltage between the first energizing brush 41 and the first commutator segment 31a in FIGS. 3A and 3B. The data line L1 shows the change in voltage with the passage of time.

4, the data line L2 shows the current _{I B-S} between the current brush 40 and commutator segments 31. Specifically, the data line L2 shows the current between the first energizing brush 41 and the first commutator segment 31a in FIGS. 3A and 3B. First power supply brush 41 shown in Figure 3A and 3B, since it is the positive brushes, a first power supply brush 41 current _{I B-S} between the first commutator segment 31a is first energized brushes 41 Flows in the direction from the first commutator segment 31a. The data line L2 shows the change in current with the passage of time.

As shown in the data line L1 in FIG. 4, at the moment when the current brush 40 and the commutator segment 31 is disconnected, the voltage V _B-S between the current brush 40 and the commutator segments 31 is increased, spark initiation You can see that it does. Voltage _{V B-S} in this case is about 4V. That is, the spark starting voltage is 4V, if the voltage V _B-S exceeds 4V, spark initiates an arc discharge occurs. During the arc duration (that is, during spark generation) in which the arc discharge continues, the arc voltage is fixed at a substantially constant voltage value. In FIG. 4, the arc voltage is about 13V.

The arc discharge continues until the spark is extinguished. That is, while the arc discharge continues, the energy of the winding coil 22 (see FIGS. 3A and 3B) between the first commutator segment 31a and the second commutator segment 31b is released and wound. The current flowing through the wire coil 22 is consumed by the arc voltage. When the current flowing through the winding coil 22 between the first commutator segment 31a and the second commutator segment 31b disappears, the arc voltage becomes zero and the spark is extinguished.

As a result of repeating the above experiments by changing the number of commutator segments 31, the input voltage of the electric motor, and the material conditions of the energizing brush 40, the present inventors, the spark starting voltage is about 3V to 4V regardless of the conditions. I found out that it was a degree.

Further, in FIG. 4, the arc voltage is about 13V, but experiments have shown that when the energizing brush 40 is a metallic graphite brush, the arc voltage falls within the range of 10V or more and 15V or less. As a result of conducting the same experiment by replacing the energizing brush 40 with the resin brush, it was also found that when the energizing brush 40 is a resin brush, the arc voltage is within the range of 13V or more and 20V or less.

As a result of diligent studies based on the above experiments, the present inventor, as shown in FIGS. 5A and 5B, adjoins the Zener diode 80 when the Zener diode 80 is connected between the energizing brush 40 and the auxiliary brush 50. Focusing on the voltage between the two commutator segments 31 and the arc voltage at the time of spark generation, the optimum breakdown voltage _VBR range of the Zener diode 80 capable of effectively suppressing the spark was found. 5A and 5B are diagrams for explaining the principle for suppressing the generation of sparks in the electric motor 1 according to the embodiment. The electric motor 1 uses a Zener diode 80 having _{such a breakdown voltage VBR.}

Specifically, in the electric motor 1 according to this embodiment, the breakdown voltage V _BR of the Zener diode 80, the voltage between the two commutator segments 31 adjacent the plurality of commutator segments 31 (adjacent stator pieces It is set to be higher than the voltage) and lower than the arc voltage in the spark generated between the commutator segment 31 and the energizing brush 40 immediately after the energizing brush 40 is separated from the plurality of commutator segments 31.

More specifically, the breakdown voltage V _BR of the Zener diode 80, as shown in FIGS. 5A and 5B, higher than the first commutator segment 31a adjacent the voltage between the second commutator segment 31b Moreover, it is set to be equal to or lower than the arc voltage in the spark generated between the first commutator segment 31a and the energizing brush 40 immediately after the energizing brush 40 is separated.

In this way, by the breakdown voltage V _BR of the Zener diode 80 below the arc voltage at the spark, effectively a spark generated between the commutator segments 31 immediately after the energization brush 40 leaves the current brush 40 Can be suppressed. If the breakdown voltage _VBR is lower than the voltage between two adjacent commutator segments 31, a current always flows through the Zener diode 80. Therefore, as described above, by making the breakdown voltage _VBR higher than the voltage between the two adjacent commutator segments 31, it is possible to pass a current through the Zener diode 80 only when a spark occurs.

Thus, the breakdown voltage V _BR of the Zener diode 80 by setting the above range, the number of commutator segments 31, regardless of the quality difference of the input voltage and current brushes 40 of the motor 1, the zener diode 80 The arc voltage at the time of spark generation can be effectively absorbed. Therefore, the spark generated between the commutator segment 31 and the energizing brush 40 can be sufficiently suppressed.

The upper limit of the breakdown voltage V _BR of the Zener diode 80, it is preferable to set the voltage between the two commutator segments 31 adjacent to the reference. Specifically, the breakdown voltage _VBR is preferably 150% or less of the voltage between two adjacent commutator segments 31.

That is, the total number of commutator segments 31 of the commutator 30 and _{N SEG,} the input voltage of the motor 1 (the direct current voltage of the power supply 70) and _{V IN,} the voltage between the two commutator segments 31 adjacent _{V S-} When _S, the breakdown voltage _{V BR} of the Zener diode 80, it may satisfy the following equation (1).

V _IN / (N _SEG / 2) x 100% <V _BR ≤ V _IN / (N _SEG / 2) x 150% ... (1)
As described above, in the electric motor 1 of the present embodiment, the voltage between the nearest neighboring two commutator segments 31, because it is 12V / 6 = 2V, the breakdown voltage V _BR of the Zener diode 80 is adjacent The voltage between the two commutator segments 31 is set to 150% = 2V × 150% = 3V.

The breakdown voltage _VBR is preferably 140% or less, more preferably 130% or less, still more preferably 125% or less, of the voltage between two adjacent commutator segments 31.

The value of the breakdown voltage V _BR of the Zener diode 80 is lower is better. In this case, the breakdown voltage _{V BR} of the Zener diode 80 may is not more than 80% of the arc voltage, preferably 70% or less, more preferably 50% or less, more preferably 30% or less.

As described above, when the Zener diode 80 having an arc voltage of about 13 V and a breakdown voltage V _BR of 3 V is used, the breakdown voltage V _BR is about 23% of the arc voltage.

As described above, as a result of repeated experiments by the present inventors, it was found that the spark starting voltage is about 3V to 4V regardless of the conditions. Further, in the above embodiment, the voltage between two adjacent commutator segments 31 was 2V.

In view of this, when the voltage between the two commutator segments 31 adjacent is less than 2V, the breakdown voltage V _BR of the Zener diode 80, may is 2V or 3V or less.

By setting a voltage between two adjacent commutator segments 31 and the breakdown voltage V _BR of the Zener diode 80 in such a range, the spark is generated between the power brush 40 and commutator segments 31 Can be suppressed. That is, it is possible to avoid the occurrence of sparks.

As described above, when the energizing brush 40 is a metallic graphite brush, the arc voltage is 10 V or more and 15 V or less. When the energizing brush 40 is a resin brush, the arc voltage is 13 V or more and 20 V or less.

Thus, it is possible to appropriately set the breakdown voltage V _BR of the Zener diode 80 in accordance with the material of the current brush 40. Therefore, the generation of sparks can be effectively suppressed.

Further, by _{setting the breakdown voltage VBR} to be equal to or lower than the spark start voltage between the energizing brush 40 and the commutator segment 31, it is possible to suppress the generation of sparks between the energizing brush 40 and the commutator segment 31. .. That is, it is possible to achieve the effect that it is possible to avoid the occurrence of sparks.

As described above, the electric motor 1 of the present embodiment includes a rotor 20 having a rotating shaft corresponding to the shaft 21, a commutator 30 attached to the rotating shaft, an energizing brush 40 in contact with the commutator 30, and a commutator. An auxiliary brush 50 in contact with 30 is provided. The commutator 30 has a plurality of commutator segments 31 provided along the circumferential direction of the rotation axis. The energizing brush 40 and the auxiliary brush 50 are electrically connected via a non-linear element corresponding to the Zener diode 80. The auxiliary brush 50 is arranged so as to be in contact with the commutator segment 31 immediately after the energizing brush 40 is separated from the plurality of commutator segments 31 when the plurality of commutator segments 31 rotate around the rotation axis. .. The breakdown voltage of the non-linear element is higher than the voltage between two adjacent commutator segments in the plurality of commutator segments 31, and the commutator segment 31 of the plurality of commutator segments 31 immediately after the energizing brush 40 is separated. It is equal to or less than the arc voltage in the spark generated between the energizing brush 40 and the energizing brush 40.

This makes it possible to suppress sparks generated between the energizing brush and the commutator segment.

(Modification example)
Although the electric motor 1 according to the present disclosure has been described above based on the embodiment, the present disclosure is not limited to the above embodiment.

For example, in the above embodiment, the Zener diode 80 is used as a spark suppressing component to be inserted into the wiring path between the energizing brush 40 and the auxiliary brush 50, but the present invention is not limited to this. Specifically, other non-linear elements such as a varistor and a MOSFET (Metal-Oxide-Semiconductor Field-Effective Transistor) may be inserted in the wiring path between the energizing brush 40 and the auxiliary brush 50. That is, the energizing brush 40 and the auxiliary brush 50 may be connected via a non-linear element such as a varistor or a MOSFET. In this case, the breakdown voltage of the non-linear element is higher than the voltage between two adjacent commutator segments 31 in the plurality of commutator segments 31, and immediately after the energizing brush 40 of the plurality of commutator segments 31 is separated. It may be set to be equal to or lower than the arc voltage of the spark generated between the commutator segment 31 and the energizing brush 40.

In the above embodiment, the number of the energizing brush 40 and the auxiliary brush 50 is two, but the number is not limited to this. Specifically, the energizing brush 40 and the auxiliary brush 50 may be one or three or more.

In the above embodiment, the stator 10 is composed of the magnet 11, but the stator 10 is not limited to this. For example, the stator 10 may be composed of a stator core and a winding coil wound around the stator core.

In the above embodiment, the rotor 20 has a core, but the rotor 20 is not limited to this. The electric motor 1 can also be applied to a coreless motor having no core. For example, the electric motor 1 can be applied to a coreless motor which is a flat flat motor in which the magnetic fluxes of the stator 10 and the rotor 20 are generated in the direction of the axis C of the shaft 21.

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

This disclosure can be used for various products equipped with an electric motor, such as a vacuum cleaner or an automobile.

1 Electric motor 10 Stator 11 Magnet 20 Rotor 21 Shaft 21a 1st end 21b 2nd end 22 Winding coil 23 Rotor core 24 Insulator 30 Commutator 31 Commutator segment 31a 1st commutator segment 31b 2nd commutator segment 32 Molded resin 40 Energizing brush 41 1st energizing brush 42 2nd energizing brush 50 Auxiliary brush 51 1st auxiliary brush 52 2nd auxiliary brush 60 Frame 70 Power supply 80 Zener diode 81 1st Zener diode 82 2nd Zener diode

Claims

A rotor with a rotating shaft and
With the commutator attached to the rotating shaft,
An energizing brush in contact with the commutator and
With an auxiliary brush in contact with the commutator,
The commutator has a plurality of commutator segments provided along the circumferential direction of the rotation axis.
The energizing brush and the auxiliary brush are electrically connected via a non-linear element.
The auxiliary brush is arranged so as to be in contact with the commutator segment immediately after the energizing brush is separated from the plurality of commutator segments when the plurality of commutator segments rotate about the rotation axis.
The breakdown voltage of the non-linear element is higher than the voltage between two adjacent commutator segments in the plurality of commutator segments, and the commutator of the plurality of commutator segments immediately after the energizing brush is separated. It is less than or equal to the arc voltage in the spark generated between the segment and the energizing brush.
Electric motor.
The yield voltage is less than or equal to the spark starting voltage between the energizing brush and the commutator segment.
The electric motor according to claim 1.
The non-linear element is a Zener diode.
The breakdown voltage is the breakdown voltage of the Zener diode.
The electric motor according to claim 1 or 2.
The breakdown voltage is 150% or less of the voltage between the two adjacent commutator segments.
The electric motor according to claim 3.
The breakdown voltage is 125% or less of the voltage between the two adjacent commutator segments.
The electric motor according to claim 3.
The voltage between the two adjacent commutator segments is less than 3V, and the breakdown voltage is 2V or more and 3V or less.
The electric motor according to any one of claims 3 to 5.
The breakdown voltage is 80% or less of the arc voltage.
The electric motor according to any one of claims 3 to 6.
When the energizing brush is a metallic graphite brush, the arc voltage is 10 V or more and 15 V or less.
The electric motor according to any one of claims 1 to 7.
When the energizing brush is a resin brush, the arc voltage is 13 V or more and 20 V or less.
The electric motor according to any one of claims 1 to 7.
The energizing brush has a first energizing brush connected to the cathode side of the DC power supply and a second energizing brush connected to the negative electrode side of the DC power supply.
The auxiliary brush has a first auxiliary brush and a second auxiliary brush.
The non-linear element includes a first non-linear element and a second non-linear element.
The first energizing brush and the first auxiliary brush are electrically connected via the first nonlinear element.
The second energizing brush and the second auxiliary brush are electrically connected via the second nonlinear element.
The electric motor according to any one of claims 1 to 9.
An electric device using the electric motor according to any one of claims 1 to 10.