JP3278173B2 - Vehicle noise control device - Google Patents

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 noise in a vehicle cabin caused by road noise and the like. More specifically, the present invention relates to noise collected by a microphone or the like and a reference signal corresponding to noise and vibration. The present invention relates to a vehicle noise control device that outputs a sound for reducing the noise from a speaker.

[0002]

2. Description of the Related Art Noise in the interior of a motor vehicle increases the fatigue of drivers and other occupants and causes discomfort.

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

[0004] Among them, road noise and the like have a great influence on people in the vehicle, and the occupant's discomfort increases as the noise increases.

[0005] The ratio of these noises that travel through the body or the like and reach the vehicle interior is larger than the ratio of direct radiation from the road surface into the vehicle interior, and there is a limit to soundproofing measures using sound insulation members. 2. Description of the Related Art Active soundproofing measures have been attracting attention, so as to output noise in phase opposite to that of road noise, etc., to actively cancel the noise, and to make people in the vehicle feel as if no road noise, etc. are being emitted.

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

That is, in 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 a vehicle interior 110. Have been. The noise collected by the microphone 112 is converted into an electric signal and transmitted to the control unit 113.

On the other hand, a reference signal is generated in a reference signal generator 115 based on an engine rotation detection signal from a sensor for detecting the number of revolutions of the engine 102. The control unit 113 controls 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 as to output a sound for canceling the vehicle interior noise (a sound having a phase opposite to the noise).

[0009]

However, in the method of generating a reference signal based on a signal from a sensor as described above, when engine noise is a problem, a signal from one sensor (for example, an IG pulse detector) is used. For example, when road noise is a problem, the number of tires that contact the road surface is four, and a sensor for detecting vibration in each of three axes is required. It becomes necessary to attach individual sensors to the vehicle body.

When a large number of noise input points are present, a large number of reference sensors are required to generate a reference signal based on a signal from the reference sensor, and the configuration of the apparatus becomes complicated.

The present invention has been made in view of such circumstances, and a vehicle noise control device capable of greatly reducing the number of reference sensors for generating reference signals and simplifying the device configuration. The purpose is to provide.

[0012]

To achieve the above object, the present invention has the following configuration. That is, sound collecting means for collecting vehicle interior noise having a constant peak frequency regardless of the running state of the vehicle specific to the vehicle type,
A speaker that outputs sound that can reduce noise in the vehicle interior;
A reference signal generating unit that generates a reference signal corresponding to the noise and vibration, and a noise in the vehicle compartment from the speaker based on the noise collected by the sound collecting unit and the reference signal generated by the reference signal generating unit. A vehicle noise control device comprising control means for controlling output of a sound that can be reduced, wherein the reference signal generation means stores a plurality of types of frequency information corresponding to the peak frequency; and And signal synthesizing means for synthesizing a frequency signal corresponding to a plurality of types of frequency information stored in the storage means at a predetermined mixing ratio according to a running state of the vehicle.

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 frequency signal according to the plurality of types of frequency information is synthesized at a predetermined mixing ratio according to the running state of the vehicle to generate a reference signal.

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

[0015]

According to the above arrangement, 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 sequentially obtaining the vibration information from the reference sensor. Then, this peak frequency is extracted when necessary.

That is, for example, noise such as road noise has a plurality of noise-specific peak frequencies,
This is determined 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 or the suspension) is measured in advance, and the frequency information is stored. Even without obtaining vibration information from the reference sensor, it is possible to generate a reference signal based on the stored frequency information.

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

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

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

Therefore, according to the vehicle noise control device of the present invention having the above-described configuration, a reference sensor is not required to generate vibration information about constant frequency noise when generating a reference signal, so that the number of reference sensors 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 diagram 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, the apparatus comprises a microphone 2 embedded at the position of a headrest 1 of each seat, a controller 3 to which an electric signal obtained by converting a sound collected by the microphone 2 is inputted, and a controller 3 An audio front speaker 4 that is driven and outputs a sound that cancels noise in the vehicle at the position of each passenger'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, a switch 5 is provided near the front panel of the driver's seat for appropriately switching the type of noise to be turned on / off or canceled out by the occupant.

The loudspeaker 4 is a general audio loudspeaker which converts a sound signal from a CD, a magnetic tape, a tuner or the like into a sound and outputs the sound, and simultaneously outputs such a sound and the noise canceling sound. , Or only one of them.

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 transmitted from the microphone 2 and amplified by the amplifier 6 and digitally converted by the A / D converter 7 is input to the controller 3. 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, applied to the speaker 4, and outputs a desired sound from the speaker 4.

As shown in FIG. 3, the controller 3
Reference signal generating means for generating a reference signal
And an 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 for generating sine wave signals having different periods from each other, and sine wave signals output from these sine wave And a mixer 24 that synthesizes at a mixing ratio of

FIG. 4 shows three sine wave generators 21 to 23. The sine wave generator 21 outputs a sine wave signal having a frequency f1. The sine wave generator 22 outputs a sine wave signal having a frequency f2. Further, the sine wave generator 23 outputs a sine wave signal having a frequency f3.

The set frequencies f1 to f1 of the sine wave generators 21 to 23
f3 corresponds to the peak frequency of the vehicle-specific noise and vibration that forms the road noise.

That is, when the noise vibration that forms the road noise is analyzed, there are natural vibration of the tire (for example, 80 Hz), resonance of coupled vibration of the wheel and the suspension, resonance vibration of the tire cavity, and the like. It corresponds to each peak of the noise level on the axis.

Since the peak frequencies of these vibrations are specific to the type of vehicle and are already determined at the time of completion of the vehicle body, these peak frequencies are measured in advance, and a sine wave is generated based on these peak frequencies. Container 21 ~
23 frequency setting values will be determined.

The mixer 24 combines 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. This mixing ratio is obtained by changing the vehicle speed or the road surface condition in advance, measuring the amplitude ratio of each peak frequency at that time, and storing the value obtained based on the measured data in the memory in the mixer 24. Keep it.

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

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

The adaptive control means 11 adjusts the phase and the gain 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. Thus, the sound output from the speaker 4 is controlled.

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

At this time, processing is performed so that the deviation J takes the minimum value by using the following recurrence formula.

[0042]

(Equation 1)

In this LMS system, as shown in FIG. 5, the adaptive mechanism 32 receives a transfer function H33 between the speaker 4 and the microphone 2, and considers the transfer function H33 to calculate the coefficient of the adaptive filter 31. To be adjusted,
Thus, the spatial distance between the speaker 4 and the microphone 2 is so-called interpolated.

The noise control device for a vehicle according to the present invention is not limited to the above embodiment, and various other modifications are possible.

For example, the number of the sine wave generators described above is not limited to three, but may be two or four or more. It is not limited to the embodiment.

In the above-described embodiment, the noise of road noise is reduced. However, the present invention can be applied to other noise reduction.

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

The adaptive control means 11 includes an LMS
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 microphone 2 for the sensor is attached to the ears of all the occupants, and noise control is performed for all the occupants. However, only a specific occupant, for example, the driver or the occupant of the driver and the passenger seat It is also possible to perform noise control only for the specific occupant. In this case, a signal from the microphone 2 at the ear of the specific occupant may be input to the controller 3.

[Brief description of the drawings]

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

FIG. 2 is a block diagram schematically showing the apparatus shown in FIG.

FIG. 3 is a block diagram showing the inside of the controller shown in FIG. 2;

FIG. 4 is a block diagram showing the inside of a reference signal generation unit shown in FIG. 3;

FIG. 5 is a block diagram showing the inside of the adaptive control means shown in FIG. 3;

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 the front page (72) Inventor Hiroshi Uchida 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References JP-A-3-282032 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) G10K 11/178 B60R 11/02 F01N 1/00 F01N 1/06 H04R 3/00 310

Claims (3)

(57) [Claims] 1. Regardless of the running condition of a vehicle specific to the vehicle type
Sound collection means for collecting vehicle interior noise having a constant peak frequency, a speaker for outputting a sound capable of reducing the noise in the vehicle interior, reference signal generation means for generating a reference signal corresponding to noise and vibration, Control means for controlling the speaker to output a sound capable of reducing the noise in the cabin based on the noise collected by the sound collecting means and the reference signal generated by the reference signal generating means. the vehicle noise control device comprising Te, the reference signal generating means comprises memory means in which a plurality kinds storing frequency information corresponding to the peak frequency, depending on the plural types of frequency information stored in said storage means the frequency signal consisting of a signal synthesizing means for synthesizing in a predetermined mixture ratio according to the running state of the vehicle, and wherein the this Vehicle noise control device. (2) Check that the running state of the vehicle is road surface information
The vehicle noise control device according to claim 1, wherein: (3) Check that the running state of the vehicle is vehicle speed information.
The vehicle noise control device according to claim 1, wherein: