JP7396023B2 - motor - Google Patents

Description

The present invention relates to a motor.

Motors equipped with electronic components such as inverters are known. For example, Patent Document 1 describes a high voltage circuit for driving a motor including an inverter as an electronic component.

Japanese Patent Application Publication No. 2010-112261

In the above motor, electromagnetic noise is generated from electronic components. Therefore, for example, by surrounding the electronic component with a metal case, leakage of electromagnetic noise generated from the electronic component to the outside of the motor is suppressed. However, in this case, the metal case tends to be relatively large, and the entire motor may become large.

In view of the above circumstances, one of the objects of the present invention is to provide a motor having a structure that can suppress electromagnetic noise generated from electronic components from leaking to the outside while suppressing enlargement.

One aspect of the motor of the present invention includes a rotor having a shaft centered on a central axis, a stator facing the rotor in the radial direction through a gap, and housing the rotor and the stator, and accommodating the rotor and the stator on one side in the axial direction. A first reference member having an opening at the front thereof, and a circuit board provided on the opening side of the first reference member and spaced apart from the first reference member in the axial direction. An electronic component and a pattern layer connected to the electronic component are provided on the surface of the circuit board on the first reference member side. One of the patterned layers on the circuit board is a metal layer extending along the board surface of the circuit board. The motor further includes a plurality of metal pillars extending in the axial direction between the circuit board and the first reference member and connecting the circuit board and the first reference member. When viewed along the axial direction, each of the plurality of pillar portions surrounds the electronic component and is arranged at intervals from each other.

According to one aspect of the present invention, it is possible to suppress electromagnetic noise generated from electronic components from leaking to the outside while suppressing an increase in the size of the motor.

FIG. 1 is a sectional view showing the motor of the first embodiment. FIG. 2 is a sectional view showing a part of the motor of the first embodiment. FIG. 3 is a diagram of a part of the motor control device of the first embodiment viewed from above. FIG. 4 is a sectional view showing a part of the motor of the second embodiment.

The Z-axis direction appropriately shown in each figure is an up-down direction in which the positive side is the "upper side" and the negative side is the "lower side." A central axis J shown as appropriate in each figure is a virtual line that is parallel to the Z-axis direction and extends in the vertical direction. In the following explanation, the axial direction of the central axis J, that is, the direction parallel to the vertical direction is simply referred to as the "axial direction," and the radial direction centered on the central axis J is simply referred to as the "radial direction." The circumferential direction centered on is simply called the "circumferential direction."

Note that the terms "vertical direction, upper side," and "lower side" are simply names used to explain the arrangement of each part, and the actual arrangement may be other than those indicated by these names. It's okay.

<First embodiment>
As shown in FIG. 1, the motor 10 of this embodiment includes a housing 11, a rotor 20, a stator 30, a bearing holder 40, bearings 51 and 52, and a control device 60. Housing 11 accommodates rotor 20, stator 30, bearing holder 40, and bearings 51 and 52. The housing 11 is cylindrical and opens upward. More specifically, the housing 11 has a cylindrical shape centered on the central axis J. In this embodiment, the housing 11 is made of metal.

The rotor 20 has a shaft 21 and a rotor body 22. The shaft 21 has a cylindrical shape that extends in the axial direction centering on the central axis J. The rotor body 22 is fixed to the outer peripheral surface of the shaft 21. Although not shown, the rotor main body 22 includes a rotor core and a rotor magnet.

The stator 30 faces the rotor 20 in the radial direction with a gap therebetween. In this embodiment, the stator 30 is located outside the rotor 20 in the radial direction. Stator 30 includes a stator core 31, an insulator 34, and a plurality of coils 35. The stator core 31 has an annular core back 32 centered on the central axis J, and a plurality of teeth 33 extending radially inward from the core back 32. The plurality of coils 35 are attached to each of the plurality of teeth 33 via the insulator 34.

The bearing holder 40 is fixed to the inner peripheral surface of the housing 11. Bearing holder 40 holds bearing 52.

The control device 60 is a device that controls the drive of the motor 10. Control device 60 is located above housing 11 . The control device 60 is exposed to the outside of the housing 11. The control device 60 is supported from below by a plurality of pillars 80 extending from the housing 11 and fixed to the housing 11. As shown in FIGS. 1 and 2, the control device 60 includes a circuit board 61 and an electronic component 70. The motor 10 includes a circuit board 61, an electronic component 70, and a plurality of pillars 80.

The circuit board 61 is a multilayer board having a plurality of pattern layers stacked in the axial direction. In this embodiment, the circuit board 61 is a two-layer board having a pattern layer. The circuit board 61 is in contact with the housing 11. Circuit board 61 is located above stator 30 . The circuit board 61 covers the upper opening of the housing 11 . In this embodiment, the circuit board 61 has a disk shape centered on the central axis J.

As shown in FIG. 2, the circuit board 61 includes a board body 61a, a metal layer 61b, and a wiring pattern 61c. The substrate main body 61a is a disc-shaped insulating member. The metal layer 61b is a metal layer that extends along the board surface of the circuit board 61. The metal layer 61b is one of the plurality of pattern layers on the circuit board 61. In this embodiment, the metal layer 61b is the uppermost pattern layer among the plurality of pattern layers on the circuit board 61. The metal layer 61b is a so-called solid pattern. In this embodiment, the metal constituting the metal layer 61b is a nonmagnetic material. The metal forming the metal layer 61b is, for example, copper.

The wiring pattern 61c is a metal pattern that is electrically connected to the electronic component 70. The wiring pattern 61c is one of the pattern layers on the circuit board 61. That is, the circuit board 61 has a metal layer 61b and a wiring pattern 61c as two pattern layers. In this embodiment, the wiring pattern 61c is the lowest pattern layer among the plurality of pattern layers on the circuit board 61. The wiring pattern 61c is provided on the lower surface of the substrate body 61a.

A connector 91 is fixed to the lower surface of the circuit board 61. Metal wiring 91a is electrically connected to wiring pattern 61c. As shown in FIG. 3, for example, three cables 92a, 92b, and 92c extend radially outward from the connector 91. The cable 92a is a power line that supplies power to the electronic component 70. The cable 92b is a signal line for signal transmission with the electronic component 70. Cable 92c is a GND line between electronic component 70. Each of the cables 92a, 92b, and 92c extends from the connector 91 axially between the housing 11 and the circuit board 61 to the outside in the radial direction of the circuit board 61. Although not shown, the cables 92a, 92b, and 92c are electrically connected to the electronic component 70 via the wiring pattern 61c.

As shown in FIG. 2, the circuit board 61 is supported from below and fixed to the housing 11 by a column 80 that passes through the circuit board 61 in the axial direction. The circuit board 61 is electrically connected to the housing 11. In this embodiment, the pillar portion 80 and the metal layer 61b are soldered. Thereby, the circuit board 61 is electrically connected to the housing 11 via the metal layer 61b and the pillar portion 80. In this embodiment, the housing 11 is a first reference member having a first reference potential. That is, the circuit board 61 is electrically connected to the housing 11, which is a first reference member having a first reference potential, and is grounded.

The electronic component 70 is attached to the housing 11 side of the board surface of the circuit board 61 . Therefore, electromagnetic noise emitted upward from the electronic component 70 can be blocked by the circuit board 61. In this way, since part of the electromagnetic noise generated from the electronic component 70 can be blocked using the circuit board 61, leakage of electromagnetic noise to the outside of the motor 10 can be suppressed without covering the control device 60 with a metal case. . As a result, the motor 10 can be miniaturized by not providing a metal case, leading to cost reduction. Therefore, it is possible to suppress the electromagnetic noise generated from the electronic component 70 from leaking to the outside of the motor 10 while suppressing the enlargement of the motor 10 .

In this embodiment, a plurality of electronic components 70 are provided. Electronic component 70 includes an inverter 71, a rotation sensor 72, a capacitor 73, a converter 74, and a microcomputer 75.

At least two of the plurality of electronic components 70 are electrically connected to form an electronic circuit 70a. In this embodiment, the electronic circuit 70a is configured by electrically connecting an inverter 71, a rotation sensor 72, a capacitor 73, a converter 74, and a microcomputer 75. In this embodiment, each electronic component 70 that constitutes the electronic circuit 70a is electrically connected via a wiring pattern 61c. In the present embodiment, in the electronic circuit 70a, the ground portion 63 included in the wiring pattern 61c penetrates the substrate body 61a in the axial direction and is connected to the metal layer 61b. As a result, the electronic circuit 70a is electrically connected to the housing 11, which is the first reference member, via the metal layer 61b and the pillar portion 80, and is grounded. In this way, according to the present embodiment, the electronic circuit 70a can be grounded by connecting it to the metal layer 61b provided on the circuit board 61. Therefore, it is easy to ground the electronic circuit 70a.

In this embodiment, the electronic circuit 70a is connected to the metal layer 61b only through the grounding portion 63, and there is only one location on the metal layer to which the electronic circuit 70a is electrically connected for grounding. Therefore, a closed circuit passing through the metal layer, the housing 11, and the electronic circuit 70a is not formed. As a result, even if an eddy current is generated in the metal layer or the housing 11 and a potential difference is generated in the metal layer or the housing 11, current is prevented from flowing through the metal layer and the housing 11 to the electronic circuit 70a. be done. Therefore, unnecessary current can be suppressed from flowing through the electronic circuit 70a, and malfunction of the electronic circuit 70a can be suppressed.

Note that in this specification, "the electronic circuit is electrically connected to only one location on the metal layer for grounding" means that the electronic circuit is electrically connected to only one location on the metal layer. The plurality of parts electrically connected to the metal layer in the electronic circuit are all connected to one location on the metal layer. Moreover, "one location" of the metal layer includes a portion of the metal layer that is electrically regarded as one location. Specifically, if the impedance is within a range where a potential difference is unlikely to occur because the impedance is relatively small, it can be electrically considered as one location.

Inverter 71 has multiple transistors. Inverter 71 is electrically connected to coil 35 of stator 30 . Coil 35 is supplied with power from inverter 71 . In this embodiment, the circuit board 61 is located above the stator 30. Therefore, it is easy to electrically connect the coil 35 to the inverter 71.

Rotation sensor 72 detects rotation of rotor 20. The rotation sensor 72 is a magnetic sensor that detects the rotation of the rotor 20 by detecting the magnetic field of a sensor magnet (not shown) attached to the upper end of the shaft 21 . The rotation sensor 72 is, for example, a magnetoresistive element. As described above, the metal constituting the metal layer 61b is a nonmagnetic material. Note that the rotation sensor 72 may be a Hall element such as a Hall IC.

A portion of the housing 11 extends in the axial direction, and the plurality of pillar portions 80 are located between the circuit board 61 and the housing 11 . In this embodiment, the pillar portion 80 connects the opening of the housing 11 and the surface of the upper metal layer 61b of the circuit board 61.

As shown in FIG. 3, in this embodiment, eight pillar portions 80 are provided, for example. The plurality of pillar portions 80 are arranged along the circumferential direction at intervals. In this embodiment, the column portion 80 is located radially outward from the electronic component 70. Thereby, the plurality of column parts 80 surround the electronic component 70 and are arranged at intervals from each other when viewed along the axial direction.

In this way, each of the plurality of pillar parts 80 surrounding the electronic component 70 when viewed along the axial direction is electrically connected to the metal layer 61b by soldering. Therefore, at least a portion of the electromagnetic noise emitted radially outward from the electronic component 70 can be blocked by the pillar portion 80. Thereby, even without providing a metal case, it is possible to further block electromagnetic noise generated from the electronic component 70 by utilizing the pillar portion 80 located between the circuit board 61 and the axial direction. Therefore, it is possible to further suppress leakage of electromagnetic noise generated from the electronic component 70 to the outside of the motor 10 while suppressing the increase in the size of the motor 10.

In this embodiment, when the wavelength of the highest frequency among the frequencies of electromagnetic noise generated from the electronic component 70 is set to λ, the distance L between adjacent column parts 80 when viewed along the axial direction is 0. The relationship <L<λ/4 is satisfied. The distance L is the straight-line distance between the pillar portions 80 when viewed along the axial direction. In FIG. 3, the distance L is shown as the distance between the column parts 80 adjacent to each other in the circumferential direction. Further, in this embodiment, the axial distance between the metal layer 61b and the housing 11, which is the first reference member, satisfies the relationship 0<H<λ/4. As shown in FIG. 2, the distance H is the axial distance between the metal layer 61b and the housing 11.

Electromagnetic noise cannot pass between the parts that block electromagnetic noise when the distance between the parts that block electromagnetic noise is smaller than 1/4 of the wavelength of the electromagnetic noise. Therefore, when the relationships 0<L<λ/4 and 0<H<λ/4 are satisfied, electromagnetic noise of all frequencies generated from the electronic component 70 passes between the pillar parts 80 in the circumferential direction. Can not do it. Thereby, electromagnetic noise emitted radially outward from the electronic component 70 can be more suitably blocked by the plurality of pillar portions 80.

As an example, when the clock frequency of the microcomputer 75 is 100 MHz, the highest frequency of the electromagnetic noise generated from the microcomputer 75 is, for example, about 2 GHz, which is 20 times the clock frequency. Therefore, the wavelength λ of the highest frequency among the frequencies of electromagnetic noise generated from the microcomputer 75 is 0.15 m. Therefore, if the distance L and the distance H are smaller than 0.0375 m, the plurality of pillars 80 can block electromagnetic noise emitted from the microcomputer 75 to the outside in the radial direction.

As described above, according to the present embodiment, the electromagnetic noise emitted from the electronic component 70 to both sides in the axial direction can be blocked by the metal layer 61b and the housing 11, which is the first reference member, and the metal layer 61b and the column portion 80 can block electromagnetic noise emitted radially outward from the electronic component 70. Therefore, by using the circuit board 61 and the plurality of pillar sections 80, electromagnetic noise generated from the electronic component 70 can be more suitably blocked. Thereby, it is possible to suppress electromagnetic noise from leaking to the outside of the motor 10 more preferably while suppressing an increase in the size of the motor 10. In this embodiment, the axial distance H between the metal layer 61b and the housing 11, which is the first reference member, is smaller than the distance L, for example.

Further, according to the present embodiment, since the pillar portions 80 are arranged side by side with intervals, the cables 92a, 92b, 92c, etc. described above can be drawn out from between the pillar portions 80. Therefore, wiring of the electronic component 70 can be made easier than when a metal case is provided. Furthermore, air from outside the motor 10 can be taken in between the pillar parts 80. Therefore, the heat dissipation performance of the control device 60 can be improved.

In this embodiment, the pillar portion 80 is provided to surround the wiring area C on the circuit board 61 when viewed along the axial direction. The wiring area C is an area of the lower surface of the circuit board 61 where the wiring pattern 61c is provided. Thereby, the column portion 80 can block electromagnetic noise generated from the wiring pattern 61c. Therefore, leakage of electromagnetic noise to the outside of the motor 10 can be further suppressed. In the example of FIG. 3, the wiring area C is a circular area centered on the central axis J. The pillar portion 80 is located on the wiring area C.

Although not shown, the diameter of the metal layer 61b may be smaller than the diameter of the housing 11, which is the first reference member. When the wavelength of the highest frequency among the frequencies of electromagnetic noise generated from the electronic component 70 is set to λ, the radial distance R between the outer peripheral edge of the metal layer 61b and the inner diameter of the housing 11, which is the first reference member, is: The relationship 0<R<λ/4 is satisfied. At this time, it is even better if the relationships 0<L<λ/4 and 0<H<λ/4 are also satisfied.

Electromagnetic noise cannot pass between the parts that block electromagnetic noise when the distance between the parts that block electromagnetic noise is smaller than 1/4 of the wavelength of the electromagnetic noise. Therefore, if the relationships 0<R<λ/4, 0<L<λ/4, and 0<H<λ/4 are satisfied, the electromagnetic noise of all frequencies generated from the electronic component 70 will be absorbed by the metal layer 61b. cannot pass between the outer peripheral edge of the housing 11 and the inner diameter of the housing 11, which is the first reference member. Thereby, electromagnetic noise emitted radially outward from the electronic component 70 can be more suitably blocked.

<Second embodiment>
As shown in FIG. 4, in the motor 110 of this embodiment, the circuit board 161 is fixed to the housing 11 by soldering. The column portion 180 passes through a through hole 161d provided in the circuit board 161 and comes into contact with the metal layer 161b. Thereby, the metal layer 161b is electrically connected to the housing 11 and grounded.

A connector 196 is fixed to the lower surface of the circuit board 161. A metal wiring 196a is provided inside the connector 196. Metal wiring 196a is electrically connected to ground portion 163 of wiring pattern 161c. A cable 197 extends from the connector 196. Cable 197 is pulled radially outward from connector 196.

The cable 197 is electrically connected to a housing DH of a device (not shown) in which the motor 110 is mounted. Thereby, the electronic circuit 170a is electrically connected to the housing DH via the metal wiring 196a and the cable 197 and grounded. The housing DH is a second reference member having a second reference potential. The housing 11, which is the first reference member, and the housing DH, which is the second reference member, are insulated from each other. Therefore, no current flows between the metal layer 161b and the electronic circuit 170a, and it is possible to further suppress unnecessary current from flowing through the electronic circuit 170a. Therefore, malfunction of the electronic circuit 170a can be further suppressed.

The present invention is not limited to the above-described embodiments, and other configurations may be adopted. The number of electronic components is not particularly limited and may be one. The electronic circuit may be composed of only some of the plurality of electronic components. A plurality of electronic circuits may be provided. The method of grounding the electronic circuit is not particularly limited. For example, screws may be used to electrically connect the metal layer and the housing. In this case, for example, the screw passes through the circuit board in the axial direction, but the wiring pattern and the screw are insulated. The connector 196 described in the second embodiment may be provided on the metal layer 161b side above the circuit board 161.

The circuit board may be a multilayer board with three or more layers as long as it is a multilayer board. In this case, the metal layer in the circuit board may be a layer sandwiched between insulating layers in the axial direction. The direction in which the circuit board is arranged with respect to the stator may be a direction other than the axial direction, and may be, for example, the radial direction.

The column portion is not particularly limited. The pillar portion may be separate from the housing. The pillar portion may be a spacer member, for example. The distance L between the pillar portions may be greater than λ/4. The column portion may include a metal portion. The material of the housing is not particularly limited. The housing may be made of resin. In this case, the first reference member may be a housing in which the motor is mounted.

The use of the motor of the embodiment described above is not particularly limited. The motor of the embodiment described above is mounted on, for example, a vacuum cleaner or the like. Note that the configurations described in this specification can be combined as appropriate within a mutually consistent range.

DESCRIPTION OF SYMBOLS 10, 110... Motor, 11... Housing (first reference member), 20... Rotor, 21... Shaft, 30... Stator, 61, 161... Circuit board, 61b, 161b... Metal layer, 70... Electronic component, 70a, 170a ...Electronic circuit, 71...Inverter, 72...Rotation sensor, 73...Capacitor, 74...Converter, 75...Microcomputer, 80, 180...Column, DH...Casing (second reference member) H, L, R...Distance, J...Central axis, λ...Wavelength

Claims (10)

A motor,
a rotor having a shaft centered on a central axis;
a stator that faces the rotor in the radial direction with a gap therebetween;
a first reference member that accommodates the rotor and the stator and has an opening on one side in the axial direction;
a circuit board located away from the first reference member on one side in the axial direction ;
Equipped with
The circuit board has a plurality of pattern layers stacked in the axial direction,
An electronic component is provided on the other axial surface of the circuit board,
The plurality of pattern layers are
a wiring pattern connected to the electronic component;
a metal layer located on one side of the wiring pattern in the axial direction and extending along the board surface of the circuit board ;
The motor further includes a plurality of metal pillars connecting the circuit board and the first reference member in the axial direction ,
In the motor, each of the plurality of column parts surrounds the electronic component and is spaced apart from each other when viewed from the axial direction. The motor according to claim 1, wherein the metal layer is a pattern layer located closest to one side in the axial direction among the plurality of pattern layers on the circuit board. When the wavelength of the highest frequency among the frequencies of electromagnetic noise generated from the electronic component is λ, the linear distance L between the adjacent columnar parts when viewed from the axial direction is 0<L<λ/ 3. The motor according to claim 1, wherein the motor satisfies the following relationship. When the wavelength of the highest frequency among the frequencies of electromagnetic noise generated from the electronic component is λ,
The motor according to any one of claims 1 to 3, wherein the axial distance H between the circuit board and the first reference member satisfies the relationship 0<H<λ/4. When the wavelength of the highest frequency among the frequencies of electromagnetic noise generated from the electronic component is λ,
The distance R in the radial direction between the outer peripheral edge of the metal layer and the inner diameter of the first reference member satisfies the relationship 0<R<λ/4 according to any one of claims 1 to 4. motor. The motor according to any one of claims 1 to 5, wherein the first reference member is a housing of the motor. A plurality of electronic components are provided,
At least two of the plurality of electronic components are electrically connected to constitute an electronic circuit,
The motor according to any one of claims 1 to 6, wherein the electronic circuit is electrically connected to the first reference member and grounded. 8. The motor of claim 7, wherein the electronic circuit is electrically connected to ground at only one location on the first reference member. A plurality of electronic components are provided,
At least two of the plurality of electronic components are electrically connected to constitute an electronic circuit,
the electronic circuit is electrically connected to and grounded to a second reference member having a second reference potential;
The motor according to any one of claims 1 to 8, wherein the first reference member and the second reference member are insulated from each other. The motor according to claim 9, wherein the second reference member is a housing of a device in which the motor is mounted.

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