JP5975355B2 - Noise elimination device and muffler motor - Google Patents

Description

  The present invention relates to a noise removal device that reduces noise generated by a noise source such as a vehicle drive motor and other motors used in a hybrid vehicle or an electric vehicle, and a muffler motor used in a vehicle drive motor.

  In recent years, an automobile having a motor for propelling a vehicle such as a hybrid car, an electric car, or a fuel cell car is increasing. In these automobiles, reducing noise and vibration generated by the motor leads to improvement of comfort for passengers. Therefore, as a countermeasure against this, anti-vibration materials and sound-absorbing materials are attached to the outside of the motor housing. Damping material is interposed in the part that attaches to the car body.

  In addition, a damping material (damper) is provided to secure a path through which oil for lubrication and cooling can pass between the stator of the motor and the housing, and to prevent vibrations from the stator from being transmitted to the housing as much as possible. Motors for automobiles have also been proposed (see, for example, Patent Document 1).

  The vibration damping material is preferably formed of an elastic material such as resin or rubber adjusted to an appropriate hardness. This is because if the damping material is soft, the vibration of the stator increases and the stator contacts the housing to generate noise, and if it is hard, the stator vibration cannot be absorbed and transmitted to the housing as it is to generate noise. .

JP 2006-166554 A

Although noise with a relatively high frequency can be absorbed and removed by the sound absorbing material among the noise caused by the motor, it is a reality that low frequency noise has high energy and cannot be removed without being absorbed much by using the sound absorbing material.
A damping material can be used to suppress low frequency vibrations, but in that case a large damping material is required. However, in reality, the engine room of a hybrid vehicle equipped with a motor and an inverter in addition to a gasoline engine cannot afford to mount a large damping material outside the motor. As described above, there is a problem that it is extremely difficult to suppress vibration at a relatively low frequency with a small damping material.

  The object of the present invention has been made in view of the above-mentioned problems, so that low-frequency noise can be reduced among noises generated from a motor that is a noise generation source while using a relatively small vibration absorber. An object of the present invention is to provide a noise removing device and a muffler motor used therefor.

  In order to solve the above problems and achieve the object of the present invention, a noise removing device of the present invention includes a vibrating body, a sensor disposed near the vibrating body and detecting 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 for driving the actuator by multiplying a signal of the sensor by a predetermined coefficient. Then, the noise generated by the vibrating body is reduced by driving the actuator so as to have a phase opposite to that of the sensor signal.

In a preferred embodiment of the present invention, a second sensor that detects vibration or noise of the vibrating body at a position away from the vibrating body is provided, and the adaptive filter obtains a coefficient from the signal of the second sensor by a predetermined algorithm, and calculates the coefficient. The actuator is driven by multiplying the sensor signal. And a coefficient is adjusted so that the signal of a 2nd sensor may become small.
Further, the adaptive filter according to a preferred embodiment of the present invention is an LMS filter, and the algorithm is an LMS (Least Mean Square) algorithm. The sensor is a film-like polymer piezoelectric element.

  As one of the preferred embodiments of the present invention, the sensor is wound concentrically around the vibrating body so as to cover the vibrating body, and the actuator is wound concentrically around the sensor so as to cover the sensor. It is like that. Furthermore, the intermediate member is an elastic member that absorbs vibrations in a part of the frequency band among vibrations generated by the vibrating body.

  The noise reduction motor of the present invention is disposed near the motor, a sensor disposed near the motor to detect vibration or noise of the motor, an intermediate member disposed near the sensor, and the intermediate member. And an actuator. The actuator is driven to have a phase opposite to that of the sensor signal by an output of an adaptive filter that multiplies the sensor signal by a predetermined coefficient. Further, the predetermined coefficient is adjusted based on a signal of the second sensor arranged at a position different from the sensor.

  According to the noise removing device and the muffling motor of the present invention described above, it is possible to reduce relatively low-frequency noise generated when a brake of a hybrid vehicle or an electric vehicle is stepped on. Further, the noise removing device and the muffling motor of the present invention can be used as a device for reducing vibration noise of a motor used for driving a lens of a digital camera, in addition to a motor of an automobile.

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 silencer motor of this invention. It is a figure explaining the noise removal apparatus of this invention using the muffler motor of FIG. It is a figure which shows the structure of an adaptive filter. It is a figure which shows the example using a some microphone. It is a figure explaining the noise removal effect by simulation.

Embodiments of a noise removing device and a muffler motor according to the present invention will be described below with reference to the drawings. As for the noise removing device, a case where the noise source is a motor mounted on a hybrid vehicle or the like will be described.
FIG. 1 is a diagram for explaining two modes of noise generated by vibration of a motor 101 mounted on a hybrid vehicle or the like. One is FIG. As shown in 1A, when the motor 101 is in contact with the fixed plate, the vibration of the motor 101 is transmitted through the fixed plate and is heard as noise, and mainly low frequency noise is heard. The other is FIG. As shown in FIG. 1B, the vibration of the motor 101 is directly transmitted to the air and can be heard as noise, and mainly high-frequency noise can be heard.

  These motor noises occur 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 sound “boo” generated at that time is low-frequency noise in which the vibration transmitted to the fixed plate is amplified and amplified depending on the situation, as shown in FIG.

  High-frequency noise is attenuated when propagating through a strong housing in which the motor is housed, or is sound-insulated by a sound-absorbing material provided inside the bonnet, so that it does not cause much problem. The problem is low frequency noise.

FIG. 2 is a diagram for explaining the principle of the noise removing apparatus of the present invention that removes the low-frequency noise described above, and shows a case where low-frequency noise is transmitted directly from the motor 101 to the air.
In this figure, the noise of the motor 101 is detected by microphones 102 and 103 provided at two locations. The microphone 102 detects sound near the motor, the microphone 103 detects sound at a position slightly away from the motor, and any signal is input to the adaptive filter 104.

  Adaptive filter 104 outputs a signal obtained by multiplying the signal of microphone 102 by a coefficient to amplifier 105. The adaptive filter 104 controls the magnitude of the coefficient to be multiplied according to the signal from the microphone 103, and controls the coefficient so that the signal from the microphone 103 becomes zero as much as possible. Once the coefficient of the adaptive filter 104 is determined, it is not necessary for the microphone 103 to detect sound, and low-frequency noise can be removed by the configuration excluding the microphone 103 from FIG.

  In the case of FIG. 2, there is some transfer function H (s) between the microphone 102 and the microphone 103. When adjusting the coefficient 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 noise generated by the motor 101 and reaching the microphone 103.

  FIG. 3 is a diagram showing a configuration of a noise removing device that uses a polymer piezoelectric element as a vibration sensor that fixes a motor to a fixed plate and detects vibrations of the fixed plate transmitted from the motor. A film-like polymer piezoelectric element 202 that functions as a vibration sensor instead of the microphone 102 in FIG. 2 is attached to the motor 201, and a film-like polymer piezoelectric element 203 that functions as a vibration sensor in place of the microphone 103 in FIG. The fixing plate 208 is installed. Since the time for transmitting the vibration of the motor 201 to the film-shaped polymer piezoelectric element 203 needs to be equal to or longer than the signal processing time in the adaptive filter 204, the film-shaped polymer piezoelectric element 202 and the film-shaped polymer piezoelectric element 203 are required. It is necessary to take a certain distance between.

  The vibration signal 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 will be described later with reference to FIG. As a result, the vibration signal of the motor 201 detected by the film-like polymer piezoelectric element 202 is multiplied by a coefficient, the phase is inverted 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 a structure of a muffler 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 an embodiment of the present invention.

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

  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, vibration of 1 KHz or more) among vibrations generated by the motor 201. For this reason, the vibration transmitted to the actuator 206 becomes a vibration with a relatively low frequency (for example, vibration of 1 KHz or less), and the vibration with a relatively low frequency is reduced by the actuator 206.

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

Next, with reference to FIG. 5 and FIG. 6, the noise removal apparatus of the embodiment of the present invention will be described.
FIG. 5 is a diagram showing a configuration of a noise removal apparatus including the noise reduction motor of FIG. 4, a microphone 203 that detects 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, signals from 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 the internal configuration of the adaptive filter 204. In FIG. 5, the microphone 203 is used instead of the vibration sensor 203 of FIG. 3, but it goes without saying that a piezoelectric element may be used instead of the microphone 203.

  In adaptive filter 204, as shown in FIG. 6, the signal of microphone 203 is input to coefficient correction algorithm 211, and the coefficient obtained by a predetermined algorithm is output to coefficient adjustment unit 212. At that time, the coefficient is adjusted according to the transfer function from the motor 201 to the microphone 203. The signal of the form-like polymer piezoelectric element 202 that has detected the vibration of the muffler motor is input to the coefficient adjustment unit 212, and this input is multiplied by the coefficient output by the coefficient correction algorithm 211 to be the output of the coefficient adjustment unit 212. Output. The output of the adaptive filter 204 is amplified by the amplifier 205, phase-inverted, 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 canceled out, and the noise from the motor approaches zero as much as possible.
The above is description of the noise removal apparatus in the embodiment of this invention.

  By the way, since the signal of the microphone 203 is used only for coefficient adjustment of the coefficient adjustment unit 212 of the adaptive filter 204, it may be removed once coefficient adjustment is completed. Even if the microphone 203 is removed from FIG. 5, it functions sufficiently as a noise removing device and can remove motor noise. However, since the vibration of the motor 201 is not always the same, the microphone 203 or a piezoelectric element that replaces the microphone 203 may be steadily installed to adjust the coefficient of the adaptive filter 204 in real time.

  5 shows an example in which 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. You may arrange | position 203a-203d. As a result, noise vibrations in the four directions around the motor 201 can be picked up, and the adaptive filter 204 can perform more accurate coefficient adjustment.

8 is a waveform of a noise signal 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.
It can be seen from FIG. 8 that the noise of the motor 201 is removed extremely effectively by combining the adaptive filter 204 with the film-shaped polymer piezoelectric element 202 and the film-shaped actuator 206 arranged concentrically.
Although this simulation deals with the case of using a small motor, noise can be similarly removed from a motor mounted on a hybrid vehicle or the like.

  Although the form of the adaptive filter is not particularly limited in the present embodiment, it can be an LMS adaptive filter using the LMS algorithm, and is a modified complex LMS algorithm (Complex Least Mean Square Algorithm) or Normalized LMS algorithm. (Normalized Least Mean Square Algorithm).

  In addition to these LMS algorithms, a 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. Similar processing is performed with other adaptive filters such as Adaptive Filter using Discrete Cosine Transform, SAN Filter (Single Frequency Adaptive Notch Filter), Neural Network, and Genetic Algorithm. be able to.

  The noise removal device of the present invention has been described above by taking an automobile motor such as a hybrid vehicle as an example. However, the present invention is not limited to the automobile motor described above. For example, focus adjustment used for a camera is performed. It can also be used as a technique for suppressing vibration noise of a motor for use. The present invention is not limited to the embodiments described in the specification, and includes various modifications and application examples without departing from the scope of the claims.

101, 201 ... motor,
102, 103 ... microphone,
104, 204 ... adaptive filter,
105, 205 ... amplifiers,
106, 206 ... actuators,
200 ... Rotating shaft 202 ... Polymer piezoelectric element,
203 ... Polymer piezoelectric element or microphone,
207 ... an elastic member,
208... Fixed plate,
211 .. Coefficient correction algorithm,
212 ... Coefficient adjustment unit

Claims (10)

A vibration body, and a sensor that is disposed in the vicinity of the vibration body and detects vibration or noise of the vibration body;
An intermediate member disposed in the vicinity of the sensor; 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,
The sensor is wound concentrically around the vibrating body so as to cover the vibrating body,
The actuator is wound concentrically around the sensor so as to cover the sensor,
A noise removing apparatus that reduces noise generated by the vibrating body by driving the actuator so as to have a phase opposite to the signal of the sensor. A second sensor for detecting vibration or noise of the vibrating body at a position away from the vibrating body;
The adaptive filter obtains the coefficient from the signal of the second sensor by a predetermined algorithm, multiplies the signal of the sensor by the coefficient, drives the actuator, and sets the coefficient so that the signal of the second sensor becomes small. The noise removing device according to claim 1, wherein the noise removing device is adjusted.   The noise removing apparatus according to claim 1, wherein the adaptive filter is an LMS filter, and the algorithm is an LMS (Least Mean Square) algorithm.   The noise removing device according to claim 1, wherein the sensor is a film polymer piezoelectric element.   The noise removing apparatus according to claim 1, wherein the intermediate member is an elastic member that absorbs vibrations in a part of a frequency band among vibrations generated by the vibrating body.   The noise removing apparatus according to claim 1, wherein the vibrating body is a motor mounted on an electric vehicle or a hybrid vehicle. A motor and 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;
An actuator disposed in the vicinity of the intermediate member,
The sensor is wound concentrically around the motor so as to cover the motor,
The actuator is wound concentrically around the sensor so as to cover the sensor,
The silencer motor, wherein the actuator is driven so as to have a phase opposite to that of the sensor signal by an output of an adaptive filter that multiplies the signal of the sensor by a predetermined coefficient.   The noise removing device according to claim 8, wherein the coefficient is adjusted based on a signal of a second sensor arranged at a position different from the sensor.   9. The muffler motor according to claim 8, wherein the sensor is a film polymer piezoelectric element.   The muffler motor according to claim 8, wherein the intermediate member is an elastic member that absorbs vibrations in a part of frequency bands among vibrations generated by the motor.

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