JP2024039300A - Motor noise reduction device and motor - Google Patents

Abstract

To reduce noise without changing a mechanical structure of a motor.SOLUTION: A motor noise reduction device comprises: a microphone installed in a motor to collect sounds around the motor; a processing unit that generates a cancelling sound which becomes a phase for cancelling the sounds collected by the microphone; and a speaker installed in the motor to reproduce the cancelling sound generated by the processing unit.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to a noise reduction device for an electric motor and an electric motor.

Normally, when an electric motor is operating, various noises are generated, such as wind noise from an external fan installed in the electric motor, bearing noise generated by a bearing on the load side of the electric motor, and magnetic sound or magnetic excitation noise. However, conventional countermeasures for these noises include, for example, changing the shape of the external fan to counter the wind noise of the external fan, and adopting bearings with small gaps to counter the bearing noise. The mechanical structure had to be changed.

JP2022-068740A

However, if the mechanical structure of the motor is changed, the characteristics and capabilities of the motor, such as its cooling performance, may also change, so it is necessary to review the entire design from scratch. Furthermore, it is difficult to make mechanical changes to an electric motor that is already in use.

Therefore, the present invention provides a noise reduction device for an electric motor that can reduce noise without changing the mechanical structure of the electric motor, and an electric motor equipped with this noise reduction device.

A noise reduction device for an electric motor according to an embodiment includes: a microphone provided on an electric motor to collect sounds around the electric motor; a processing device that generates a canceling sound having a phase that cancels out the sound collected by the microphone; A speaker is provided on the electric motor and reproduces the canceling sound generated by the processing device.

Further, the electric motor according to the embodiment includes the above-described noise reduction device.

A diagram schematically showing an example of the configuration of an electric motor and a noise reduction device for the electric motor according to an embodiment A diagram showing an example of functional blocks of a motor noise reduction device according to an embodiment A diagram conceptually illustrating a sound collected by a microphone, a canceling sound generated by a processing device, and a result of canceling noise by reproducing the canceling sound, regarding a noise reduction device for an electric motor according to an embodiment.

Hereinafter, a noise reduction device for a motor and a motor according to one embodiment will be described with reference to the drawings. The electric motor 10 is connected to, for example, an external control device (not shown), and is driven by electric power output from an inverter (not shown) provided in the control device. The electric motor 10 is operated according to operating conditions in which, for example, the number of revolutions is set in advance.

The electric motor 10 illustrated in FIG. 1 includes a frame 11, bearing brackets 12 and 13, a fan cover 14, a rotating shaft 15, and a terminal box 16. Further, the electric motor 10 includes a stator and a rotor provided inside the frame 11, although details are not shown. The stator includes, for example, a stator core and a coil, and is fixed to the inner peripheral surface of the frame 11. The rotor includes, for example, a rotor iron core and a permanent magnet, and is rotatably provided inside the frame 11 together with the rotating shaft 15.

The frame 11, the bearing brackets 12 and 13, and the fan cover 14 constitute the outer shell of the electric motor 10. The frame 11 has, for example, a cylindrical space therein, and accommodates a stator and a rotor (not shown). The bearing brackets 12 and 13 are provided at both end portions of the frame 11, respectively, and rotatably support the rotating shaft 15. The fan cover 14 is provided on one end side of the frame 11 and accommodates a cooling external fan (not shown).

One end of the rotating shaft 15, in this case the left end in FIG. 1, is connected to an external fan (not shown) within the fan cover 14. Further, as shown in FIG. 1, the other end of the rotating shaft 15, in this case the right end in FIG. 1, is exposed to the outside from the bearing bracket 13 and is connected to a load (not shown). Note that the load (not shown) connected to the rotating shaft 15 can be any of various elements that can be driven by the electric motor 10, such as a pump.

In the following description, the side to which a load (not shown) is connected to the electric motor 10 is referred to as the "load side," and the side opposite to the load side, in this case, the side to which an external fan (not shown) is connected is referred to as the "counter-load side." ” is sometimes called. In the example of FIG. 1, the right side of the page is the "load side" and the left side of the page is the "anti-load side."

The terminal box 16 is fixed to the frame 11, for example. The terminal box 16 is configured, for example, integrally with the frame 11 or separately, and protrudes outward from the frame 11. The terminal box 16 accommodates connection terminals (not shown) connected to the coils of the stator.

A noise reduction device 20 is, for example, detachably attached to the electric motor 10 . In the case of this embodiment, the electric motor 10 includes a noise reduction device 20. The noise reduction device 20 includes a microphone 21, a speaker 22, and a processing device 23. The noise reduction device 20 includes multiple microphones 21 and multiple speakers 22. The noise reduction device 20 includes, for example, three or more microphones 21 and three or more speakers 22.

The microphone 21 is provided on the electric motor 10 and has a function of collecting sounds around the electric motor 10. The microphone 21 is provided, for example, on both end sides of the rotating shaft 15, that is, on the load side and the anti-load side of the rotating shaft 15. In this case, the microphone 21 provided on the load side mainly collects noise generated on the load side of the rotating shaft 15. Further, the microphone 21 provided on the opposite load side mainly collects noise caused by wind noise from an external fan (not shown).

The microphone 21 is provided on the outer surface of the electric motor 10, in this case, for example, on the outer surface of the bearing brackets 12 and 13. In the case of this embodiment, the microphone 21 collects sounds from outside the electric motor 10 . Note that the microphone 21 may be provided, for example, on the outer surface of the frame 11 or the fan cover 14. The microphones 21 are arranged, for example, at equal intervals along the rotation direction of the rotation shaft 15 on the outer surfaces of the bearing brackets 12 and 13.

The speaker 22 is provided in the electric motor 10 and has a function of reproducing the cancellation sound generated by the processing device 23. Each speaker 22 is provided near each corresponding microphone 21. The speakers 22 are provided, for example, on both end sides of the rotating shaft 15, that is, on the load side and the anti-load side of the rotating shaft 15. In this case, the speaker 22 provided on the load side generates a sound that cancels out the noise mainly generated on the load side of the rotating shaft 15. Furthermore, the microphone 21 provided on the opposite load side generates a sound that cancels out noise mainly caused by wind noise from an external fan (not shown).

The speaker 22 is provided on the outer surface of the electric motor 10, in this case, for example, on the outer surface of the bearing brackets 12 and 13. In the case of this embodiment, the speaker 22 generates a canceling sound to the outside of the electric motor 10. Note that the speaker 22 may be provided, for example, on the outer surface of the frame 11 or the fan cover 14. The speakers 22 are arranged, for example, at equal intervals along the rotational direction of the rotating shaft 15 on the outer surface of the bearing brackets 12 and 13.

The processing device 23 is provided in the electric motor 10. The processing device 23 is provided within the terminal box 16, for example. Note that the processing device 23 may be provided outside the terminal box 16. The processing device 23 has a function of generating a cancellation sound having a phase that cancels out the sound collected by each microphone 21. That is, the processing device 23 generates a cancellation sound to be played by each speaker 22 to cancel the sound based on the sound collected by each microphone 21, and causes each speaker 22 to play the cancellation sound.

The processing device 23 includes, for example, as shown in FIG. 2, a digital conversion section 231, a cancellation sound generation section 232, and a cancellation sound reproduction section 233. The digital conversion section 231, the cancellation sound generation section 232, and the cancellation sound reproduction section 233 can be configured with electric circuits mounted on one or more boards, for example.

The digital conversion unit 231 has a function of digitally converting the sound collected by each microphone 21. The cancellation sound generation unit 232 has a function of generating cancellation sound for canceling the sound collected by each microphone 21 based on the data digitally converted by the digital conversion unit 231. The canceling sound generation unit 232 generates a sound having an opposite phase to the sound collected by each microphone 21, as shown in FIG. 3, for example.

The noise generated by the electric motor 10 has the same period as the rotation period of the rotating shaft 15, for example. Therefore, as shown in FIG. 3, for example, the canceling sound generation unit 232 delays the period T of the sound collected by each microphone 21 by a certain period, for example, a half period T/2, so that each microphone The configuration may be such that a sound having an opposite phase to the sound collected in step 21 is generated. Further, the canceling sound generating unit 232 may be configured to generate a sound having an opposite phase to the sound collected by each microphone 21, for example, by inverting the data digitally converted by the digital converting unit 231. .

The cancellation sound reproduction section 233 has a function of causing each speaker 22 to reproduce the cancellation sound generated by the cancellation sound generation section 232. As a result, as shown in "Cancellation Result" in FIG. 3, the noise around the electric motor 10 collected by the microphone 21 is canceled by the cancellation sound reproduced from the speaker 22. As a result, the noise generated by the electric motor 10 is reduced or muffled. The cancellation sound reproduction section 233 can be configured to include, for example, an amplifier, a driver, etc. that operate the speaker 22.

According to the embodiment described above, the electric motor noise reduction device 20 includes a microphone 21, a speaker 22, and a processing device 23. The microphone 21 is provided on the electric motor 10 and has a function of collecting sounds around the electric motor 10 . The processing device 23 has a function of generating a cancellation sound having a phase that cancels out the sound collected by the microphone 21. The speaker 22 is provided in the electric motor 10 and has a function of reproducing the cancellation sound generated by the processing device 23. The electric motor 10 of this embodiment includes the noise reduction device 20 described above.

According to this, by canceling the noise around the electric motor 10 with the canceling sound generated by the speaker 22, it is possible to reduce or muffle the noise around the electric motor 10 without changing the mechanical structure of the electric motor 10. can. Note that the noise reduction device 20 can be included in the electric motor 10 or can be retrofitted to the existing electric motor 10.

Here, most of the noise generated by the electric motor 10 is generated inside the electric motor 10, in this case, in the internal space surrounded by the frame 11, the bearing brackets 12, 13, and the fan cover 14. For this reason, it is also possible to provide the microphone 21 and the speaker 22 inside the electric motor 10 to cancel the noise inside the electric motor 10.

However, the noise that users and others find problematic is mainly the noise coming from outside the electric motor 10 rather than the noise inside the electric motor 10. Furthermore, if the microphone 21 and speaker 22 are provided inside the electric motor 10, the canceled sound generated by the speaker 22 may reverberate inside the electric motor 10, and the microphone 21 may pick up the echoed sound. may increase.

Therefore, in this embodiment, the microphone 21 and the speaker 22 are provided on the outer surface of the electric motor 10. That is, the noise reduction device 20 includes a microphone 21 and a speaker 22 provided on the outer surface of the electric motor 10. That is, in this embodiment, the microphone 21 collects sounds from an open space outside the electric motor 10. Further, the speaker 22 generates a canceling sound toward the open space outside the electric motor 10. According to this, it is possible to efficiently and reliably reduce or muffle the noise external to the electric motor 10 that is a problem for users and the like.

Further, the microphone 21 and the speaker 22 are provided on both the load side and the anti-load side of the electric motor 10. According to this, the noise reduction device 20 can efficiently reduce both the noise generated on the load side of the rotating shaft 15 and the noise caused by the wind noise of the external fan generated on the opposite load side.

Although the present disclosure has been described based on examples, it is understood that the present disclosure is not limited to the examples or structures. The present disclosure also includes various modifications and equivalent modifications. In addition, various combinations and configurations, as well as other combinations and configurations that include only one, more, or fewer elements, are within the scope and scope of the present disclosure.

10... Electric motor, 20... Noise reduction device, 21... Microphone, 22... Speaker, 23... Processing device

Claims (4)

a microphone provided on the electric motor to collect sounds around the electric motor;
a processing device that generates a cancellation sound having a phase that cancels out the sound collected by the microphone;
a speaker provided on the electric motor and reproducing the canceling sound generated by the processing device;
A noise reduction device for an electric motor. The microphone and the speaker are provided on an outer surface of the electric motor,
The electric motor noise reduction device according to claim 1. The microphone and the speaker are provided on both a load side and an anti-load side of the electric motor,
The electric motor noise reduction device according to claim 1. An electric motor comprising the noise reduction device according to any one of claims 1 to 3.

Images