JPH056188A - Noise control device for vehicle - Google Patents

Abstract

PURPOSE:To simplify the structure of a noise control device by greatly reducing reference sensors for generating reference signals. CONSTITUTION:A reference signal generating means 10 is composed of a plurality of sinusoidal wave generators 21 through 23 for delivering sinusoidal frequency signals having different cycle periods, and a mixer for synthesizing these signals delivered from sinusoidal wave generators 21 through 23 with a predetermined mixing ratio. The set frequencies f1 through f3 of the generators 21 through 23 are coincident respectively with peak frequencies of noise vibrations which is inherent to a kind of vehicle and which constitute load noise. Further, the mixer 24 synthesizes the sinusoidal signals delivered from the generators 21 through 23 with a predetermined mixing ratio (gain ratio) in accordance with vehicle speed data and road surface data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle noise control device for reducing the noise in the passenger compartment caused by road noise or the like. More specifically, it is based on a noise collected by a microphone or the like and a reference signal corresponding to the noise vibration. The present invention relates to a vehicle noise control device that outputs a sound for reducing the noise from a speaker.

[0002]

BACKGROUND OF THE INVENTION Noise in the interior of a vehicle increases fatigue and discomfort to the driver and other occupants.

[0003] Such a vehicle interior noise is generally 20
There are low frequencies (crowded noise) of 0Hz to 300Hz or less, and medium and high frequency sounds such as engine noise, exhaust system radiation noise, road noise, and wind noise.

Among these, road noise and the like have a great influence on people in the vehicle, and as the noise increases, the occupant's discomfort increases.

These noises have a higher rate of reaching the vehicle interior through the body than the rate of being directly radiated from the road surface into the vehicle interior, and there is a limit to the soundproofing measures using the sound insulating member, rather. Active noise control measures are attracting attention, which is to say that the noise in the vehicle is output in a phase opposite to that of the road noise and the noise is positively canceled to make people in the car feel as if the road noise is not present.

[0006] As a conventional technique relating to such a positive soundproofing measure, a vehicle interior based on noise collected by a microphone mounted near the headrest of the occupant (near the position of the occupant's ear) and the reference signal from the reference sensor. It is known that a speaker attached to the speaker outputs a sound having a phase opposite to the noise to cancel the noise (Japanese Patent Publication No. 1-501344).

That is, according to the technique described in this publication, as shown in FIG. 6, a plurality of microphones 112 for collecting vehicle interior noise and two speakers 111 constituting a secondary sound source are installed at a predetermined position in the vehicle interior 110. Has been done. The noise collected by the microphone 112 is converted into an electric signal and sent to the control unit 113.

On the other hand, the reference signal generator 115 generates a reference signal based on the engine rotation detection signal from the sensor for detecting the rotation speed of the engine 102. The control unit 113 adjusts the adaptive filter 114 according to the input reference signal and the output signal from the microphone 112.
From the two speakers 111 by changing the filter constant of
The speaker 111 is driven so that a sound that cancels the vehicle interior noise (a sound having a phase opposite to the noise) is output.

[0009]

However, in the method of generating the reference signal based on the signal from the sensor as described above, the signal from one sensor (eg, IG pulse detector) is used when engine noise is a problem. Although the reference signal can be generated by, for example, when road noise is a problem, the number of tires that come into contact with the road surface is four, and sensors for detecting vibrations in each of the three axes are required. It becomes necessary to attach individual sensors to the vehicle body.

When there are many noise input points in this way, a large number of reference sensors are required to generate a reference signal based on the signal from the reference sensor, which complicates the apparatus configuration.

The present invention has been made in view of the above circumstances, and the number of reference sensors for generating a reference signal can be significantly reduced, and the vehicle noise control device can be simplified. It is intended to provide.

[0012]

SUMMARY OF THE INVENTION A vehicle noise control device of the present invention includes a sound collecting means for collecting vehicle interior noise, a speaker for outputting a sound capable of reducing noise in the vehicle interior, and a noise vibration. It is possible to reduce the noise in the vehicle interior from the speaker based on the reference signal generation unit that generates a corresponding reference signal, the noise collected by the sound collection unit, and the reference signal generated by the reference signal generation unit. In a vehicle noise control device including control means for controlling to output a sound, the reference signal generation means stores a plurality of types of frequency information according to a peak frequency of natural vibration of a noise source. A storage unit and a frequency signal corresponding to a plurality of types of frequency information stored in the storage unit are set to a predetermined value according to a running state of the vehicle. And it is characterized in that comprising a signal combining means for combining in a mixing ratio.

That is, a plurality of types of frequency information corresponding to the peak frequency of the natural vibration of the noise source are stored,
The reference signal is generated by synthesizing the frequency signals corresponding to the plurality of types of frequency information at a predetermined mixing ratio according to the traveling state of the vehicle.

Here, the running state of the vehicle includes all the various factors related to the running of the vehicle such as the road surface state and the vehicle speed.

[0015]

According to the above configuration, when the reference signal is generated, the peak frequency of the natural vibration of the noise source is measured in advance and stored, instead of successively obtaining the vibration information from the reference sensor. However, this peak frequency is taken out when necessary.

That is, noise such as road noise has a plurality of peak frequencies of noise peculiar to the vehicle type,
This is decided for each vehicle type when the vehicle body is completed.

Therefore, the peak frequency of such constant frequency noise (for example, the natural frequency of the tire, the resonance point of the coupled vibration of the wheel and the suspension) is measured in advance, and the frequency information is stored in advance. It is possible to generate the reference signal based on the stored frequency information without obtaining the vibration information from the reference sensor.

Further, according to the above configuration, the reference signal is generated by synthesizing the frequency signals corresponding to the plurality of stored frequency information at a predetermined mixing ratio according to the running state of the vehicle.

That is, the relative ratio of the levels of the noise factors forming such a noise peak changes depending on the vehicle speed and the condition of the road surface. For example, at low speeds, the level of coupled vibration of the wheel and suspension is not very high,
Therefore, the relative ratio of this vibration at a low speed becomes small.

Therefore, when the reference signal is actually generated, the situation is changed by changing the mixing ratio of the frequency signals corresponding to the respective vibrations according to the factors affecting the relative ratio of the respective vibration levels. It is possible to generate a highly accurate reference signal according to

Therefore, according to the vehicle noise control device of the present invention having the above-mentioned configuration, when the reference signal is generated, the reference sensor is not required to obtain the vibration information about the constant frequency noise, so that the reference sensor is greatly reduced. It is possible to simplify the configuration of the device.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view showing a state in which a vehicle noise control device according to an embodiment of the present invention is mounted inside a vehicle.

That is, this device is composed of a microphone 2 embedded in the position of the headrest 1 of each seat, a controller 3 to which an electric signal obtained by converting a sound collected by the microphone 2 is input, and a controller 3. It is composed of an audio front speaker 4 that is driven and outputs a sound that cancels the noise in the vehicle at the position of each occupant's ear.

The microphone 2 is arranged at a position corresponding to the position of both ears of each occupant, so that an electric signal corresponding to the sound actually heard by each occupant is input to the controller 3. Becomes

Further, near the front panel of the driver's seat, there is provided a switch 5 for appropriately turning on / off the device or switching the type of noise to be canceled by the occupant.

The speaker 4 is a general audio speaker for converting a sound signal from a CD, a magnetic tape, a tuner or the like into a sound and outputting the sound. Such a sound and the noise canceling sound are simultaneously produced. , Or only one of them is output.

FIG. 2 is a block diagram showing the outline of the present apparatus.

That is, according to FIG. 2, the electric signal carrying the noise information sent from the microphone 2, which is amplified by the amplifier 6 and converted into a digital signal by the A / D converter 7, is input to the controller 3, Further, the speaker drive signal sent from the controller 3 is converted into an analog signal by the D / A converter 8, amplified by the amplifier 9 and applied to the speaker 4, so that the speaker 4 outputs a desired sound.

This controller 3 is, as shown in FIG.
Reference signal generating means for generating a reference signal
10 and adaptive control means 11 for outputting an appropriate speaker drive signal based on the reference signal generated by the reference signal generation means 10 and the microphone output signal output from the microphone 2.

Further, the reference signal generating means 10
As shown in FIG. 4, a plurality of sine wave generators 21 to 23 that generate sine wave signals having mutually different periods, and the sine wave signals output from these sine wave generators 21 to 23 are mutually predetermined. It is composed of a mixer 24 which can be synthesized at a mixing ratio of.

In FIG. 4, three sine wave generators 21 to 23 are shown. The sine wave generator 21 outputs a sine wave signal of frequency f1, and the sine wave generator 22 outputs a sine wave signal of frequency f2. Further, the sine wave generator 23 outputs each sine wave signal of frequency f3.

Setting frequency f1 of each sine wave generator 21-23
f3 corresponds to the peak frequency of noise and vibration that forms road noise and is unique to the vehicle type.

That is, when analyzing the noise vibrations that form road noise, there are natural vibrations of the tire (for example, 80Hz), resonance of coupled vibrations of wheels and suspensions, resonance vibrations of the tire cavity, etc. It corresponds to each peak of the noise level on the axis.

Since the peak frequencies of these vibrations are peculiar to the vehicle type and have already been determined when the vehicle body is completed, these peak frequencies are measured in advance and sine waves are generated by these peak frequencies. Bowl 21 ~
The frequency setting value of 23 will be decided.

Further, the mixer 24 synthesizes the sine wave signals from the sine wave generators 21 to 23 at a predetermined mixing ratio (gain ratio) according to the input vehicle speed information and road surface information. For this mixing ratio, the vehicle speed or the road surface condition is changed in advance, the amplitude ratio of each peak frequency at that time is measured, and the value obtained based on the measured data is stored in the memory in the mixer 24. I'll do it.

Therefore, when the reference signal is generated,
Based on the input vehicle speed information and road surface information, a predetermined mixing ratio data is output from the memory in the mixer 24, and the sine wave signals are synthesized based on this data.

The vehicle speed information is obtained based on the signal from the vehicle speed sensor, and the road surface information is obtained based on the signal from the road surface sensor.

Further, the adaptive control means 11 performs phase adjustment and gain adjustment in the adaptive filter 20 based on the reference signal so that the frequency component included in the reference signal is not included in the microphone output signal. Then, the sound output from the speaker 4 is controlled.

That is, the adaptive control means 11 of the apparatus of this embodiment
Adopts the LMS method (Least Mean Square method), and as shown in FIG. 5, the adaptive mechanism 32 adjusts the filter constant based on the microphone output signal for the adaptive filter 31 to which the reference signal is input.

At this time, the following recurrence formula is used so that the deviation J takes a minimum value.

[0042]

[Equation 1]

In the LMS system, the adaptive mechanism 32 receives the transfer function H33 between the speaker 4 and the microphone 2 as shown in FIG. 5, and the coefficient of the adaptive filter 31 is taken into consideration in consideration of the transfer function H33. To adjust,
As a result, the spatial distance between the speaker 4 and the microphone 2 is interpolated, so to speak.

The vehicle noise control device of the present invention is not limited to the above-mentioned embodiment, but various modifications can be made.

For example, the number of the above-mentioned sine wave generators is not limited to three, but can be two or four or more, and also as information representing the running state input to the mixer. It is not limited to the example.

Further, although the above embodiment is intended to reduce the noise of road noise, it can be applied to the case of reducing other noises.

It is of course possible to add a reference signal from a general reference sensor to the reference signal generated in the device of the present invention to generate a final reference signal.

As the adaptive control means 11, LMS is used.
However, instead of this, the simplex (S
Of course, it is also possible to adopt the implex method or the Powell method.

In the apparatus of this embodiment, the microphones 2 for sensors are attached to the ears of all occupants to control the noise of all occupants. However, only a specific occupant, for example, the driver or the occupants in the passenger and passenger seats. It is also possible to perform noise control only for this case. In this case, the signal from the microphone 2 at the ear of the specific occupant may be input to the controller 3.

[Brief description of drawings]

FIG. 1 is a schematic view showing a mounting position of a vehicle noise control device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an outline of the apparatus shown in FIG.

FIG. 3 is a block diagram showing the inside of the controller shown in FIG.

FIG. 4 is a block diagram showing the inside of the reference signal generating means shown in FIG.

5 is a block diagram showing the inside of the adaptive control means shown in FIG.

FIG. 6 is a block diagram for explaining a conventional technique.

[Explanation of symbols]

 2 Microphone 3 Controller 4 Speaker 10 Reference signal generating means 11 Adaptive control means 21, 22, 23 Sine wave generator 24 Mixer 31 Adaptive filter 32 Adaptive mechanism

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroshi Uchida 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Motor Corporation

Claims (1)

Claim: What is claimed is: 1. A sound collecting unit that collects vehicle interior noise, a speaker that outputs a sound that can reduce the vehicle interior noise, and a reference that generates a reference signal corresponding to noise vibration. Based on the signal generation means, the noise collected by the sound collection means and the reference signal generated by the reference signal generation means, control is performed so that the speaker outputs a sound capable of reducing the noise in the vehicle interior. In a vehicle noise control device including a control unit, the reference signal generation unit stores a plurality of types of frequency information corresponding to the peak frequency of the natural vibration of the noise source, and the storage unit. Signal synthesis for synthesizing frequency signals according to stored multiple types of frequency information at a predetermined mixing ratio according to the running state of the vehicle Vehicle noise control apparatus characterized by comprising a stage.