WO2013118421A1

WO2013118421A1 - Noise elimination device and muted motor

Info

Publication number: WO2013118421A1
Application number: PCT/JP2012/083914
Authority: WO
Inventors: 佐藤　寧
Original assignee: 国立大学法人九州工業大学
Priority date: 2012-02-08
Filing date: 2012-12-27
Publication date: 2013-08-15
Also published as: JP5975355B2; JPWO2013118421A1

Abstract

The present invention reduces noise signals with a comparatively low frequency from a motor (201) in a hybrid vehicle or electric vehicle, for example. A vibration detection sensor (202) is positioned at a location near the periphery of the motor (201), and in addition to detecting vibrations from the motor, detects vibrations from the motor even at locations slightly distant from the motor. Two detection signals are supplied to a least mean squares (LMS) adaptive filter (204), the phase of an output signal from the LMS adaptive filter (204) is reversed relative to a vibration detection signal for the motor (201), and the output signal is supplied to an actuator (206) positioned concentrically to the motor (201). The actuator (206) is driven so as to attenuate vibrations from the motor.

Description

Noise removal device and noise reduction motor

The present invention relates to a noise removal device for reducing noise generated by noise sources such as a vehicle drive motor and other motors used in, for example, a hybrid vehicle or an electric vehicle, and a noise reduction motor used in a vehicle drive motor.

In recent years, there are an increasing number of vehicles having a motor for propulsion of the vehicle, such as hybrid vehicles, electric vehicles or fuel cell vehicles. In these vehicles, reducing noise and vibration generated from the motor leads to improved comfort for the occupants, and as a countermeasure, a vibration absorbing material or sound absorbing material is attached to the outside of the motor housing, or the housing The damping material intervenes in the part which attaches to the vehicle body.

In addition, a damping material (damper) is provided between the motor's stator and the housing to secure a passage through which oil for lubrication and cooling can pass, and to minimize transmission of vibrations from the stator to the housing. Motors for automobiles have also been proposed (see, for example, Patent Document 1).

In addition, as this damping material, it is said that it is good to form with the material which has elasticity like resin and rubber | gum which were adjusted to moderate hardness. If the damping material is soft, the vibration of the stator becomes large and the stator contacts the housing to generate noise, and if it is hard, the vibration of the stator can not be absorbed and the noise is transmitted to the housing as it is. .

JP, 2006-166554, A

Although relatively high frequency noise of motor noise can be absorbed and removed by the sound absorbing material, it is a reality that low frequency noise can not be removed without much absorption even using the sound absorbing material because energy is high.
A damping material can be used to suppress low frequency vibrations, but in that case a large damping material is required. However, it is also a reality that in the engine room of a hybrid vehicle equipped with a motor and an inverter in addition to a gasoline engine, there is no room for mounting a large damping material outside the motor. As described above, there is a problem that it is extremely difficult to suppress relatively low frequency vibration with a small damping material.

The object of the present invention is made in view of the above-mentioned problems, and it is possible to reduce low frequency noise among noises generated from a motor which is a noise generation source while using a relatively small vibration absorber. Another object of the present invention is to provide a noise removal device and a noise reduction motor used therein.

In order to solve the above problems and achieve the object of the present invention, a noise removal device of the present invention comprises: a vibrating body; a sensor disposed in the vicinity of the vibrating body to detect vibration or noise of the vibrating body; An intermediate member disposed in the vicinity of the sensor, an actuator disposed in the vicinity of the intermediate member, and an adaptive filter that drives the actuator by multiplying a signal of the sensor by a predetermined coefficient. Then, by driving the actuator so as to have a phase opposite to that of the sensor signal, the noise generated by the vibrator is reduced.

In a preferred embodiment of the present invention, a second sensor for detecting vibration or noise of a vibrating body at a position away from the vibrating body is provided, and the adaptive filter determines a coefficient from a signal of the second sensor by a predetermined algorithm and calculates the coefficient. The signal of the sensor is multiplied to drive the actuator. And a coefficient is adjusted so that the signal of a 2nd sensor may become small.
Furthermore, the adaptive filter of the preferred form of the present invention is an LMS filter, and the algorithm is an LMS (Least Mean Square) algorithm. Also, the sensor is a film-like polymeric piezoelectric element.

Also, as a preferred embodiment of the present invention, the sensor is concentrically wound around the vibrating body so as to cover the vibrating body, and the actuator is concentrically wound around the sensor so as to cover the sensor. It is supposed to be. Furthermore, the intermediate member is an elastic member that absorbs the vibration of a part of the frequency band of the vibration generated by the vibrator.

The noise reduction motor according to the present invention includes a motor, a sensor disposed in the vicinity of the motor for detecting vibration or noise of the motor, an intermediate member disposed in the vicinity of the sensor, and a proximity of the intermediate member. And an actuator. The actuator is driven so as to be in the opposite phase to the sensor signal by the output of the adaptive filter which multiplies the sensor signal by a predetermined coefficient. Also, the predetermined coefficient is adjusted based on the signal of the second sensor disposed at a position different from the sensor.

According to the noise eliminator and the noise reduction motor of the present invention described above, it is possible to reduce relatively low frequency noise generated when the brake of a hybrid car or an electric car is stepped on. Further, the noise removal device and the noise reduction motor of the present invention can also be used as devices for reducing vibration noise of a motor used for driving a lens of a digital camera other than a motor of a car.

It is a figure explaining the noise of a motor. It is a figure explaining the principle of the noise removal apparatus of this invention. It is a figure which shows the structure of the noise removal apparatus using a vibration sensor. It is a figure which shows the structure of the muffling motor of this invention. It is a figure explaining the noise removal apparatus of this invention using the muffling motor of FIG. It is a figure which shows the structure of an adaptive filter. It is a figure showing an example using a plurality of microphones. It is a figure explaining a noise removal effect by simulation.

Hereinafter, embodiments of the noise removal device and the noise reduction motor of the present invention will be described with reference to the drawings. The noise reduction device will be described in the case where the noise source is a motor mounted on a hybrid vehicle or the like.
FIG. 1 is a view for explaining two aspects of noise generated by vibration of a motor 101 mounted on a hybrid vehicle or the like. One is FIG. 1 FIG. As shown in FIG. 1A, when the motor 101 is in contact with the fixed plate, the vibration of the motor 101 is transmitted through the fixed plate to be heard as noise, and mainly low frequency noise is heard. Another one is shown in FIG. As shown in FIG. 1B, the vibration of the motor 101 is transmitted directly into the air to be heard as noise, and mainly high frequency noise is heard.

These motor noises are generated especially when the driver steps on the brakes. A motor used in a hybrid vehicle or the like changes to a generator mode and generates noise when the brake is depressed. The low noise that is generated at that time is a low frequency noise in which the vibration transmitted to the fixed plate is amplified and increased depending on the situation as shown in FIG. 1 FIG. 1A.

High frequency noise is less of a problem as it is dampened as it travels through a rigid housing in which the motor is housed, or because it is insulated by a sound absorbing material provided inside the bonnet. The problem is low frequency noise.

FIG. 2 is a view for explaining the principle of the noise removal device of the present invention for removing the low frequency noise described above, and shows a case where the low frequency noise is transmitted directly from the motor 101 into the air.
In this figure, the noise of the motor 101 is detected by the

microphones

102 and 103 provided at two places. The microphone 102 detects sound in the vicinity of the motor, and the microphone 103 detects sound in a position slightly away from the motor, and both signals are input to the adaptive filter 104.

The adaptive filter 104 outputs a signal obtained by multiplying the signal of the microphone 102 by a coefficient to the amplifier 105. The adaptive filter 104 controls the magnitude of the coefficient to be multiplied according to the signal of the microphone 103, and controls the coefficient so that the signal of the microphone 103 becomes 0 without limit. Once the coefficient of the adaptive filter 104 is determined, the microphone 103 does not have to detect sound, and low frequency noise can be removed by the configuration in which the microphone 103 is removed from FIG.

In the case of FIG. 2, some transfer function H (s) exists between the microphone 102 and the microphone 103. When adjusting the coefficients of the adaptive filter 104, the transfer function H (s) and the transfer function of the adaptive filter 104 are adjusted to be the same. The adaptive filter 104, which will be described in detail later, is a filter provided to minimize the signal of the microphone 103, and it is possible to minimize the noise generated by the motor 101 and reaching the microphone 103.

FIG. 3 is a view showing a configuration of a noise removal device using a polymer piezoelectric element as a vibration sensor that fixes a motor to a fixed plate and detects a vibration of the fixed plate transmitted from the motor. A film-shaped polymeric piezoelectric element 202 functioning as a vibration sensor is attached to the motor 201 instead of the microphone 102 in FIG. 2, and a film-shaped polymeric piezoelectric element 203 functioning as a vibration sensor instead of the microphone 103 in FIG. It is attached to the fixed plate 208 installed. The time required for the vibration of the motor 201 to be transmitted to the film-shaped polymeric piezoelectric element 203 needs to be longer than the time for signal processing in the adaptive filter 204. Therefore, the film-shaped polymeric piezoelectric element 202 and the film-shaped polymeric piezoelectric element 203 It is necessary to take some distance between them.

A signal of vibration of the motor 201 detected by the film-like polymer piezoelectric element 202 is sent to the adaptive filter 204. Then, using the signal of the polymer piezoelectric element 203, the coefficient of the adaptive filter 204 is adjusted as described later with reference to FIG. As a result, the signal of the vibration of the motor 201 detected by the film-like polymer piezoelectric element 202 is multiplied by a coefficient, phase-reversed by the amplifier 205, and supplied to the actuator 206. Since the vibration generated by the actuator 206 acts to cancel the vibration of the motor, the vibration transmitted from the motor 201 to the vibration sensor 203 is reduced and reduced, and the noise generated from the fixed plate 208 is reduced.

FIG. 4 shows the structure of a muffling motor in which a film-like polymer piezoelectric element 202 and a film-like actuator 206 are arranged concentrically around the motor 201 as an example of the embodiment of the present invention.

As shown in FIG. 4, a motor 201 having a rotating shaft 200 is provided with a film-like polymeric piezoelectric element 202 wound around the periphery thereof. The film-like polymer piezoelectric element 202 is a piezoelectric element that generates an electrical signal according to the magnitude of the vibration when the vibration of the motor 201 is transmitted.
A slightly rigid elastic member 207 such as silicone rubber is wound around the film-like polymer piezoelectric element 202, and an actuator 206 is concentrically wound around the outer periphery of the elastic member 207. The actuator 206 is a piezoelectric element that converts an electrical signal, when it is supplied, into mechanical vibration.

The elastic member 207 is set to have a thickness of about 5 to 10 mm, and has an effect of attenuating a relatively high frequency component (for example, a vibration of 1 KHz or more) of the vibration generated by the motor 201. Therefore, the vibration transmitted to the actuator 206 is a relatively low frequency vibration (for example, a vibration of 1 KHz or less), and the relatively low frequency vibration is reduced by the actuator 206.

In the example of FIG. 4, the elastic member 207 represented by silicon rubber is provided as an intermediate member to be interposed between the film-like polymeric piezoelectric element 202 and the film-like actuator 206, but it is particularly necessary to be an elastic member. Absent. It may be an intermediate member that delays the vibration of the motor 201 by a time corresponding to the time of signal processing in the adaptive filter 204 described later.

Next, with reference to FIG. 5 and FIG. 6, the noise removal device of the embodiment of the present invention will be described.
FIG. 5 is a diagram showing the configuration of the noise removal device including the noise reduction motor of FIG. 4, a microphone 203 for detecting the noise of the noise reduction motor at a position slightly away from the noise reduction motor, an adaptive filter 204 and an amplifier 205. As shown in the figure, the signals of the microphone 203 and the film-like polymer piezoelectric element 202 are input to the adaptive filter 204, and the output of the adaptive filter 204 is input to the amplifier 205 to drive the actuator 206. FIG. 6 is a schematic block diagram showing an internal configuration of adaptive filter 204. Referring to FIG. Although the microphone 203 is used in place of the vibration sensor 203 in FIG. 3 in FIG. 5, it goes without saying that a piezoelectric element may be used in place of the microphone 203.

In the adaptive filter 204, as shown in FIG. 6, the signal of the microphone 203 is input to the coefficient correction algorithm 211, and the coefficient obtained by the predetermined algorithm is output to the coefficient adjustment unit 212. At this time, the coefficients are adjusted in accordance with the transfer function from the motor 201 to the microphone 203. The signal of the form polymer piezoelectric element 202 which has detected the vibration of the muffling motor becomes the input of the coefficient adjustment unit 212, and this input is multiplied by the coefficient output by the coefficient correction algorithm 211 to become the output of the coefficient adjustment unit 212. It also becomes the output of The output of the adaptive filter 204 is amplified and phase-inverted by the amplifier 205 and supplied to the actuator 206. The predetermined coefficient correction algorithm 211 adjusts the coefficient of the coefficient adjustment unit 212 so that the signal of the microphone 203 becomes zero as much as possible when configured as shown in FIG.

The actuator 206 is formed of a film-like polymer piezoelectric element, like the film-like polymer piezoelectric element 202, and vibrates in the opposite phase to the polymer piezoelectric element 202. Therefore, the vibration of the polymer piezoelectric element 202 and the vibration of the actuator 206 are offset, and the noise by the motor approaches 0 without limit.
The above is the description of the noise removal device in the embodiment of the present invention.

Since the signal of the microphone 203 is used only for the coefficient adjustment of the coefficient adjusting unit 212 of the adaptive filter 204, it may be removed after the coefficient adjustment is completed. Even if the microphone 203 is removed from FIG. 5, the device functions sufficiently as a noise removal device, and the noise of the motor can be removed. However, since the vibration of the motor 201 is not always the same, the microphone 203 or a piezoelectric element instead thereof may be constantly installed to adjust the coefficient of the adaptive filter 204 in real time.

In the example shown in FIG. 5, one microphone 203 is provided at a position slightly away from the motor 201. However, as shown in FIG. 7, a plurality of microphones, for example, four microphones are provided around the motor 201. 203a to 203d may be arranged. As a result, noise and vibration in four directions around the motor 201 can be picked up, and coefficient adjustment of the adaptive filter 204 can be performed more accurately.

FIG. 8 shows waveforms of noise signals obtained by simulating the noise removal apparatus of FIG. 5 when noise removal is performed using the adaptive filter 204 (noise processing ON) and when noise removal is not performed (noise processing OFF). It shows the difference between the two.
From FIG. 8, it can be seen that the noise of the motor 201 is extremely effectively removed by combining the adaptive filter 204 and the film-like polymer piezoelectric element 202 and the film-like actuator 206 arranged concentrically.
Although this simulation deals with the case where a small motor is used, noise can be similarly eliminated for a motor mounted on a hybrid vehicle or the like.

Although the form of the adaptive filter is not particularly limited in this embodiment, it may be an LMS adaptive filter using an LMS algorithm, or a modified LMS algorithm (Complex Least Mean Square Algorithm) or Normalized LMS algorithm which is a modification thereof. (Normalized Least Mean Square Algorithm) can also be used.

Furthermore, besides these LMS algorithms, projection algorithm (Projection Algorithm), SHARF algorithm (Simple Hyperstable Adaptive Recursive Filter Algorithm), RLS algorithm (Recursive Least Square Algorithm), FLMS algorithm (Fast Least Mean Square Algorithm), and DCT are used. The same processing is performed with other adaptive filters such as Adaptive Filter using Discrete Cosine Transform, SAN Filter (Single Frequency Adaptive Notch Filter), Neural Network (Neural Network), and Genetic Algorithm. be able to.

Although the noise eliminator according to the present invention has been described by taking the motor for motor vehicle such as a hybrid vehicle as an example, the present invention is not limited to the motor for motor vehicle described above. For example, focus adjustment used in a camera It can also be used as a technique for suppressing the vibration noise of the motor for motor use. Further, the present invention is not limited to the embodiments described in the specification, and includes various modifications and applications without departing from the scope of the claims.

101, 201 ... motor,
102, 103 ... Mike,
104, 204 ... adaptive filter,
105, 205 ... amplifier,
106, 206 ··· Actuator,
200: rotation shaft 202: polymeric piezoelectric element,
203: Polymer piezoelectric element or microphone
207 ... elastic member,
208 ... fixed plate,
211 · · Coefficient correction algorithm,
212: Coefficient adjustment unit

Claims

A vibrator, and a sensor disposed in the vicinity of the vibrator to detect vibration or noise of the vibrator;
An intermediate member disposed in the vicinity of the sensor, and an actuator disposed in the vicinity of the intermediate member;
An adaptive filter for driving the actuator by multiplying a signal of the sensor by a predetermined coefficient;
A noise eliminator characterized by reducing noise generated by the vibrator by driving the actuator so as to have a phase opposite to that of the sensor signal.
A second sensor for detecting vibration or noise of the vibrating body at a position away from the vibrating body;
The adaptive filter determines the coefficient from the signal of the second sensor according to a predetermined algorithm, multiplies the signal of the sensor by the coefficient to drive the actuator, and causes the coefficient to decrease the signal of the second sensor. The noise removal device according to claim 1, wherein the noise is adjusted.
The noise reduction device according to claim 1, wherein the adaptive filter is an LMS filter, and the algorithm is an algorithm of LMS (Least Mean Square).
The noise eliminating device according to any one of claims 1 to 3, wherein the sensor is a film-like polymeric piezoelectric element.
The sensor may be concentrically wound around the vibrator so as to cover the vibrator, and the actuator may be concentrically wound around the sensor so as to cover the sensor. The noise removal device according to any one of claims 1 to 4.
6. The noise eliminator according to any one of claims 1 to 5, wherein the intermediate member is an elastic member that absorbs vibration of a partial frequency band of the vibration generated by the vibrator.
The noise eliminator according to any one of claims 1 to 6, wherein the vibrator is a motor mounted on an electric vehicle or a hybrid vehicle.
A motor, and a sensor disposed in the vicinity of the motor to detect vibration or noise of the motor;
An intermediate member disposed in the vicinity of the sensor;
An actuator disposed in the vicinity of the intermediate member;
The motor according to claim 1, wherein the actuator is driven to be in opposite phase to the signal of the sensor by an output of an adaptive filter which multiplies the signal of the sensor by a predetermined coefficient.
The noise removal device according to claim 8, wherein the coefficient is adjusted based on a signal of a second sensor disposed at a position different from the sensor.
10. The muffling motor according to claim 8, wherein the sensor is a film-like polymeric piezoelectric element.
The sensor may be concentrically wrapped around the motor so as to cover the motor, and the actuator may be concentrically wrapped around the sensor so as to cover the sensor. The noise reduction motor according to any one of 8 to 10.
The silencer motor according to any one of claims 8 to 11, wherein the intermediate member is an elastic member that absorbs vibration of a partial frequency band of vibrations generated by the motor.