JP2016063624A - Rectifier motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent electromagnetic noise from being emitted from a rotary shaft part 9 without depending on grounding of the rotary shaft part 9, in a motor 1.SOLUTION: The motor 1 includes a metallic case 8 in which a rotor 4 is accommodated and which is grounded. The rotor 4 includes the rotary shaft part 9, a core part 10 and an insulation part 15 as follows. Namely, first of all, one end of the rotary shaft part 9 protrudes outside of the case 8. The core part 10 is provided at an outer peripheral side of the rotary shaft part 9, a coil 5 is wound around it and a magnetic flux generated in a permanent magnet 6 is passed. Further, the insulation part 15 is provided between the rotary shaft part 9 and the core part 10 and electrically insulates the rotary shaft part 9 and the core part 10. Thus, capacitive coupling is formed between the core part 10 and the rotary shaft part 9, and exchange of electromagnetic noise between the core part 10 and the rotary shaft part 9 is suppressed. Thus, emission of electromagnetic noise from the rotary shaft part 9 can be suppressed without depending on the grounding of the rotary shaft part 9.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a commutator motor.

  Conventionally, in a commutator motor, the rotor coil is energized by the sliding contact between the brush and the commutator, and the magnetic flux generated by the magnetic poles arranged on the outer peripheral side of the rotor is linked to the coil to generate torque. The structure to perform is well known. In such a commutator motor, electromagnetic noise is generated due to spark discharge generated when the commutator piece is separated from the brush in the rotational sliding contact between the brush and the commutator, and adversely affects other devices. It is regarded as a problem. Therefore, the electromagnetic noise is attenuated by incorporating inductance and capacitance into the circuit including the brush, commutator, and coil, or the metal case that houses the rotor is grounded to prevent electromagnetic noise emission. .

By the way, the rotor of the commutator motor has a rotating shaft part and a core part as described below as metal parts, and may become a radiation source of electromagnetic noise.
That is, the rotation shaft portion is a portion that forms the center of rotation, one end projects out of the case and functions as a torque output shaft, the core portion is provided on the outer peripheral side of the rotation shaft portion, and a coil is wound, Pass the magnetic flux generated by the magnetic pole. Further, the rotating shaft portion and the core portion are in direct contact and can be electrically connected. Furthermore, a capacitive coupling is formed between the coil and the core portion by a coil protection varnish, an insulator, etc., and a capacitive coupling is formed between the rotating shaft portion and the case by an oil film in the bearing. ing. For this reason, the rotating shaft portion and the core portion are in an electrically floating state.

As a result, when electromagnetic noise is delivered by capacitive coupling between the coil and the core, electromagnetic noise can be radiated to the outside of the motor from the portion of the rotating shaft that protrudes outside the case. There is sex.
Therefore, a structure is known in which electromagnetic noise is released from the rotating shaft portion to the ground through the case by pressing and contacting the rotating shaft portion with the case (see, for example, Patent Document 1).
However, according to the structure of Patent Document 1, when a component that generates a pressing force deteriorates and the pressing force becomes weak, grounding of the rotating shaft portion becomes unstable, and electromagnetic noise can be radiated from the rotating shaft portion. Will increase.

JP 2001-320849 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to suppress radiation of electromagnetic noise from the rotating shaft portion in a commutator motor regardless of grounding of the rotating shaft portion. It is to provide a structure that can.

  According to the first invention of the present application, the commutator motor energizes the rotor coil by the rotational sliding contact between the brush and the commutator, and chains the magnetic flux generated by the magnetic pole disposed on the outer peripheral side of the rotor to the coil. Generate torque by crossing. Further, the commutator motor includes a metal case that rotatably accommodates the rotor and is grounded, and the rotor includes the following rotating shaft portion, core portion, and insulating portion.

  First, the rotating shaft portion is made of metal and is a portion that forms the center of rotation, and one end projects out of the case. The core part is made of metal, is provided on the outer peripheral side of the rotating shaft part, is wound with a coil, and passes the magnetic flux generated by the magnetic pole. Further, the insulating portion is provided between the rotating shaft portion and the core portion, and electrically insulates the rotating shaft portion and the core portion.

  Thereby, capacitive coupling is formed between the core part and the rotating shaft part, and delivery of electromagnetic noise between the core part and the rotating shaft part is suppressed. For this reason, in the commutator motor, the emission of electromagnetic noise from the rotating shaft portion can be suppressed regardless of the grounding of the rotating shaft portion.

According to the second invention of the present application, the capacitance between the rotation shaft portion and the core portion is smaller than the capacitance between the rotation shaft portion and the case.
Accordingly, when considering a circuit from the coil to the case through the core portion and the rotating shaft portion, the potential of the rotating shaft portion can be suppressed to ½ or less of the potential of the core portion. For this reason, the radiation | emission of the electromagnetic noise from a rotating shaft part can be suppressed more reliably.

According to 3rd invention of this application, an impeller is attached to the part which has protruded out of the case among the rotating shaft parts, and comprises the air blower of a vehicle air conditioner.
In a vehicle air conditioner, since there is no conductive material around the impeller, if electromagnetic noise is radiated from the rotating shaft, it tends to adversely affect surrounding equipment. Furthermore, in vehicles, a radio or the like is often mounted in the vicinity of the air conditioner, and when electromagnetic noise is radiated from the rotating shaft portion, there is a high possibility that noise is generated in the radio.
For this reason, the effect of this invention can be acquired notably by comprising the air blower of a vehicle air conditioner with the commutator motor which employ | adopted this invention.

According to the fourth invention of the present application, the insulating portion is provided by coating a resin material or powder coating the outer peripheral surface of the rotating shaft portion or the inner peripheral surface of the core portion.
Thereby, an insulation part can be simply provided between a rotating shaft part and a core part.

(Example 1) which is sectional drawing containing the axial center of a commutator motor. It is sectional drawing perpendicular | vertical to the shaft center of a commutator motor, and shows the example which performed spline processing on the rotating shaft part (Example 1). (A) is a circuit diagram relating to electromagnetic noise, and (b) is a circuit diagram relating to electromagnetic noise in Patent Document 1 (Example 1). It is a characteristic diagram illustrating based correlation equation 1 in relation with Vsh / V1 and _{C c-s} (Example 1). (Example 2) which is sectional drawing containing the axial center of a commutator motor. (Example 3) which is sectional drawing containing the axial center of a commutator motor.

  The commutator motor of the embodiment will be described based on the following examples. In addition, an Example discloses a specific example, and it cannot be overemphasized that this invention is not limited to an Example.

[Configuration of Example 1]
A configuration of a commutator motor 1 (hereinafter referred to as a motor 1) according to the first embodiment will be described with reference to the drawings.
As shown in FIG. 1, the motor 1 energizes the coil 5 of the rotor 4 by rotational sliding contact between the brush 2 and the commutator 3, and generates magnetic flux generated by the magnetic pole 6 disposed on the outer peripheral side of the rotor 4. Torque is generated by interlinking with the coil 5. In addition, the magnetic pole 6 of an Example is a permanent magnet, and the magnetic pole 6 is made into the permanent magnet 6 in the following description.

In addition, the motor 1 includes a metal case 8 that rotatably accommodates the rotor 4 and is grounded. The rotor 4 includes the following rotary shaft portion 9 and core portion 10.
The case 8 is made of a magnetic metal such as iron and functions as a yoke through which the magnetic flux generated by the permanent magnet 6 passes. Further, the case 8 is provided in a bottomed cylindrical shape, the permanent magnet 6 is attached to the inner periphery of the cylindrical portion 8a, and the core portion 10 is permanent so as to be within the range where the permanent magnet 6 exists in the axial direction. It is arranged on the inner peripheral side of the magnet 6.

  A ball bearing 12 a that rotatably supports the other axial end of the rotary shaft portion 9 is accommodated in the bottom portion 8 b of the case 8. One end side in the axial direction of the case 8 is closed by a resin cover 13, and the brush 2 and the commutator 3 are accommodated in the cover 13. Further, the cover 13 also accommodates a ball bearing 12 b that rotatably supports the rotating shaft portion 9, and one end of the rotating shaft portion 9 projects outward from the cover 13 and the case 8. And the impeller (not shown) is attached to the part which protrudes out of the cover 13 and the case 8 among the rotating shaft parts 9, and comprises the air blower of a vehicle air conditioner.

  The rotating shaft 9 is made of, for example, S45C (carbon steel for mechanical structure), and is a portion that forms the center of rotation. The core portion 10 is made of an electromagnetic steel plate, and is provided on the outer peripheral side of the rotating shaft portion 9 so that the coil 5 is wound and the magnetic flux generated by the permanent magnet 6 is passed.

  Further, in the motor 1, electromagnetic noise is generated due to spark discharge generated when the commutator piece 3 a is separated from the brush 2 in the rotational sliding contact between the brush 2 and the commutator 3. The electromagnetic noise is attenuated by incorporating an inductance (not shown) or a capacitance (not shown) in a circuit including the brush 2, the commutator 3 and the coil 5, or the case 8 is grounded. Thus, radiation to the outside of the motor 1 is blocked.

Further, in the rotor 4 of the first embodiment, an insulating portion 15 that electrically insulates the rotating shaft portion 9 and the core portion 10 is provided between the rotating shaft portion 9 and the core portion 10. The commutator piece 3a is fixed to one end of the insulating portion 15, and the insulating portion 15 has a function of fixing the commutator piece 3a.
The insulating portion 15 is made of PBT (polyethylene sulfide) or PEEK (polyetheretherketone) such as “super engineering plastics” or “general engineering plastics” which is excellent in thermal stability, dimensional accuracy and electrical characteristics. Polybutylene terephthalate) is used as the material.

Various fixing methods between the rotating shaft portion 9 and the insulating portion 15 and fixing methods between the core portion 10 and the insulating portion 15 can be considered.
First, as a fixing method between the rotating shaft portion 9 and the insulating portion 15, insert molding in which a molten resin is injected and injected after the rotating shaft portion 9 is loaded as an insert part in a mold is conceivable. At this time, spline processing may be performed on the outer periphery of the rotating shaft portion 9, and the space between the rotating shaft portion 9 and the insulating portion 15 may be fixed more firmly (see FIG. 2). In addition to the spline processing, the fixing between the rotating shaft portion 9 and the insulating portion 15 can be reinforced by involute processing, knurling processing, serration processing, or the like.
Furthermore, between the rotating shaft part 9 and the insulating part 15, it can fix to the axial direction by providing the tenon 16 in the rotating shaft part 9. FIG.

Next, as a method for fixing between the insulating portion 15 and the core portion 10, pressure fitting, shrink fitting, cooling fitting, or the like can be considered. Moreover, you may fix between the core part 10 and the insulation part 15 by insert molding.
In addition, a hole 18a penetrating in the axial direction is provided in the bottom 8b of the case 8, and holes 18b and 18c penetrating in the axial direction and the radial direction are provided in the cover 13, respectively. Thereby, when the rotating shaft portion 9 rotates and the impeller rotates, an air flow is generated in the case 8 and the cover 13, and the coil 5, the core portion 10, the insulating portion 15, and the like can be cooled. For this reason, even during the operation of the motor 1, the temperature rise inside the motor 1 can be reduced to suppress the softening of the insulating portion 15.

[Effects of Example 1]
The motor 1 according to the first embodiment energizes the coil 5 of the rotor 4 by rotational sliding contact between the brush 2 and the commutator 3, and generates a magnetic flux generated by the permanent magnet 6 disposed on the outer peripheral side of the rotor 4. Torque is generated by linking them to each other. In addition, the motor 1 includes a metal case 8 that rotatably accommodates the rotor 4 and is grounded. The rotor 4 includes the following rotary shaft portion 9, core portion 10, and insulating portion 15.

  First, the rotating shaft portion 9 is made of metal and is a portion that forms the center of rotation, and one end protrudes outside the case 8. The core portion 10 is made of metal, is provided on the outer peripheral side of the rotating shaft portion 9, is wound with the coil 5, and passes the magnetic flux generated by the permanent magnet 6. Further, the insulating portion 15 is provided between the rotating shaft portion 9 and the core portion 10 to electrically insulate the rotating shaft portion 9 and the core portion 10.

Thereby, a capacitive coupling C _cs is formed between the core portion 10 and the rotating shaft portion 9 (see FIG. 3A), and electromagnetic noise between the core portion 10 and the rotating shaft portion 9 is reduced. delivery is suppressed (hereinafter, the value of the capacitance of the capacitive coupling C _c-s is denoted by C _c-s.).

That is, electromagnetic noise generated by the rotational sliding contact between the brush 2 and the commutator 3 can be greatly reduced by incorporating inductance and capacitance, grounding the case 8 and the like. However, there is a possibility that a part of this electromagnetic noise is transferred from the coil 5 to the core part 10 via the capacitive coupling _Cw-c formed between the coil 5 and the core part 10 (hereinafter, referred to as “the electromagnetic noise”). , the values of the capacitance of the capacitive coupling _{C w-c} denoted by _{C w-c.).}

The capacitive coupling _Cw-c is formed by a varnish or an insulator that protects the coil 5, and Cw _-c is 1000 pF or more. Also, capacitive coupling C _s-h are formed, capacitive coupling C _s-h also between the rotating shaft 9 and the case 8 is formed by a oil film in the ball bearing 12a, C _{s- h} is about 20 pF.

  By the way, in the structure of patent document 1, the core part 10 and the rotating shaft part 9 contact and are electrically connected, and the rotating shaft part 9 is press-contacting to the case 8. FIG. As a result, the rotating shaft 9 and the case 8 are conducted with low impedance, the voltage Vsh of the rotating shaft 9 becomes substantially zero, and electromagnetic noise is reduced in the rotating shaft 9 (see FIG. 2B). .

On the other hand, in the configuration of the first embodiment, by providing the insulating portion 15 between the rotating shaft portion 9 and the core portion 10, the capacitive coupling C _cs is formed, and the core portion 10 and the rotating shaft portion 9 are formed. The electromagnetic noise between the two.
Here, the ratio between the voltage Vsh of the rotating shaft 9 and the voltage V1 of the coil 5 in the first embodiment is expressed by the following mathematical formula 1.

[Formula 1]
Vsh / V1
= _Cw-C * _Ccs / ( _Cc-s * Cs _-h + Cs _-h * _Cw-c + _Cw-c * _Cc-s )

Therefore, for example, when 20 pF and 1000 pF are applied to C _s-h and C _w-c , respectively, the voltage Vsh is set to the voltage V1 by setting C _c-s to C _s-h or less (20 pF or less) 6 dB (see FIG. 4). For this reason, since the voltage Vsh can be suppressed to half of the voltage V <b> 1, electromagnetic noise can be reduced in the rotary shaft portion 9.
As a result, in the motor 1, radiation of electromagnetic noise from the rotating shaft portion 9 can be suppressed regardless of the grounding of the rotating shaft portion 9.

In order to set C _c-s to C _s-h or less (20 pF or less), for example, the following modes can be considered.
That is, when the radius a of the rotary shaft portion 9 is 3.5 mm, the inner peripheral diameter b of the core portion 10 is 4.5 mm, and the axial length L of the core portion 10 is 20 mm (see FIG. 1), the ratio. by dielectric constant εr uses 3 of the resin material in the insulating portion 15 _can be a _{C c-s} to 13 pF (20 pF or less).

Here, C _cs can be obtained by the following Equation 2.

[Formula 2]
C _c−s = 2 · π · ε · L / Log (b / a)

Equation 2 is a simple theoretical formula for obtaining the cylindrical capacitance, ε is the dielectric constant of the material forming the cylinder, and Log (b / a) is the natural logarithm of b / a. .

  Further, according to the structure of Patent Document 1, since the rotary shaft portion 9 is in rotational sliding contact with the case 8, an increase in driving load due to friction at the sliding portion, a change in rotational capacity after long-term use, and an increase in rotational fluctuation due to friction. May occur, and the performance of the motor 1 may not be stable. In particular, when the motor 1 is used to configure a blower of a vehicle air conditioner, the motor 1 has a small output of 200 W or less, so the adverse effect of increasing the driving load is great, and the motor 1 is disposed in the vehicle interior. Therefore, the noise caused by the rotation fluctuation is noticeable to the passenger.

For this reason, in the motor 1, by suppressing the radiation of electromagnetic noise from the rotating shaft portion 9 regardless of the grounding of the rotating shaft portion 9, it is possible to prevent an increase in driving load and noise caused by rotational fluctuations. .
Furthermore, according to the structure of Patent Document 1, a part for pressing the rotary shaft portion 9 is required, and the motor 1 is increased in size. On the other hand, according to the motor 1 of the first embodiment, a structure that reduces electromagnetic noise can be realized at low cost without increasing the size of the motor 1.

Further, in the vehicle air conditioner, since there is no conductive material around the impeller, if electromagnetic noise is radiated from the rotating shaft portion 9, the surrounding devices are likely to be adversely affected. Furthermore, in a vehicle, a radio or the like is often mounted in the vicinity of the air conditioner, and when electromagnetic noise is radiated from the rotating shaft portion 9, there is a high possibility that noise is generated in the radio.
For this reason, the reduction effect of electromagnetic noise can be acquired notably by comprising the air blower of a vehicle air conditioner with the motor 1 of Example 1. FIG.

The bottom 8b of the case 8 is provided with a hole 18a penetrating in the axial direction, and the cover 13 is provided with holes 18b and 18c penetrating in the axial direction and the radial direction.
Thereby, when the rotating shaft portion 9 rotates and the impeller rotates, an air flow is generated in the case 8 and the cover 13, and the coil 5, the core portion 10, the insulating portion 15, and the like can be cooled. For this reason, since the temperature rise inside the motor 1 can be reduced and softening of the insulating portion 15 can be suppressed, the fixing of the insulating portion 15 to the rotating shaft portion 9 and the core portion 10 is firmly performed even during operation of the motor 1. Can be maintained.

Further, by including the resin insulating portion 15 in the rotor 4, the weight of the rotor 4 can be reduced and the motor 1 can be reduced in weight.
In addition, even if the inner periphery of the core portion 10 is the insulating portion 15, the magnetic circuit is not affected, and the performance of the motor 1 is not affected by the presence of the insulating portion 15.

[Example 2]
According to the motor 1 of the second embodiment, the insulating portion 15 is provided by coating the outer peripheral surface of the rotating shaft portion 9 with a resin material or by powder coating (see FIG. 5).
Thereby, the insulation part 15 can be simply provided between the rotating shaft part 9 and the core part 10.

Example 3
According to the motor 1 of the third embodiment, the insulating portion 15 is provided by coating the inner peripheral surface of the core portion 10 with a resin material or powder coating (see FIG. 6).
Thereby, the insulation part 15 can be simply provided between the rotating shaft part 9 and the core part 10.

[Modification]
The mode of the motor 1 is not limited to the embodiment, and various modifications can be considered.
For example, according to the motor 1 of the embodiment, the voltage Vsh of the rotating shaft portion 9 was reduced by 6 dB with respect to the voltage V1 of the coil 5 (although the voltage Vsh was suppressed to half of the voltage V1), the voltage The reduction width of Vsh with respect to the voltage V1 may be larger or smaller than 6 dB.
Moreover, although the motor 1 of an Example comprised the air blower of the vehicle air conditioner, you may comprise apparatuses other than the air blower of the vehicle air conditioner with the motor 1. FIG.

DESCRIPTION OF SYMBOLS 1 Motor (commutator motor) 2 Brush 3 Commutator 4 Rotor 5 Coil 6 Permanent magnet (magnetic pole) 8 Case 9 Rotating shaft part 10 Core part 15 Insulation part

Claims (4)

The coil (5) of the rotor (4) is energized by the rotational sliding contact between the brush (2) and the commutator (3), and is generated by the magnetic pole (6) disposed on the outer peripheral side of the rotor (4). In the commutator motor (1) for generating torque by interlinking magnetic flux with the coil (5),
A metal case (8) which is rotatably grounded and accommodates the rotor (4);
The rotor (4)
A metal rotation shaft portion (9) that is a portion that forms a center of rotation and has one end protruding outside the case (8);
A metal core portion (10) provided on the outer peripheral side of the rotating shaft portion (9) and wound with the coil (5) to pass a magnetic flux generated by the magnetic pole (6);
An insulating portion (15) provided between the rotating shaft portion (9) and the core portion (10) and electrically insulating the rotating shaft portion (9) and the core portion (10). A commutator motor (1) characterized by that. In the commutator motor (1) according to claim 1,
A capacitance between the rotating shaft (9) and the core (10) is smaller than a capacitance between the rotating shaft (9) and the case (8). Commutator motor (1) In the commutator motor (1) according to claim 1 or 2,
A commutator motor (1), wherein an impeller is attached to a portion of the rotating shaft portion (9) protruding outside the case (8) to constitute a blower of a vehicle air conditioner. In the commutator motor (1) according to any one of claims 1 to 3,
The insulating portion (15) is provided by coating a resin material or powder coating the outer peripheral surface of the rotating shaft portion (9) or the inner peripheral surface of the core portion (10). A commutator motor (1) characterized in that

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