JP2000280831A - Active type noise controlling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a noise in a cabin arising from low frequency road noise. SOLUTION: This noise controlling device is provided with a control means for inputting a signal which is highly related to a sound from a source of noise as a reference signal while generating a noise cancellation signal having a reverse phase against that of a noise in a cabin, a cancellation sound generating means which is provided in the cabin and generates a noise cancellation sound following the noise cancellation signal outputted from the control means, and a microphone for verification of noise reduction of the noise in the cabin, and the control means lowers an output signal level from the microphone. In this case, microphones 26, 27 are provided near left and right roof rail 34, 35 of a vehicle 20 so as to oppose against an ear of an occupant seating on front seats 36, 37 of the vehicle 20, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active noise control device for canceling out noise in a vehicle interior by canceling the noise by a secondary noise having a phase opposite to that of the noise, and more particularly, to an inner and outer ear of an occupant in the vehicle interior. The present invention relates to an active noise control device for canceling vehicle interior noise based on noise, particularly low frequency road noise (20 to 150 Hz).

[0002]

2. Description of the Related Art An active noise control device for canceling vehicle interior noise generated by road noise uses an active control by feedforward control as shown in FIG.

[0003] In the conventional active noise control device, when canceling the noise in the cabin 24 of a vehicle, a suspension vibration and a vibration of each part of the vehicle body, which are highly correlated with the cabin noise, are detected by a sensor, and this detection signal is used as a reference signal. , The reference signal is supplied to the adaptive digital filter 21 and the digital filter 22 set to have the same transfer characteristics as the transfer characteristics for the vehicle interior sound in the vehicle cabin, and the output of the digital filter 22 is
Adaptive digital filter 21 based on LMS algorithm
, Wi of the filter coefficients w1, w2, w3,..., Wi of the filter coefficients w1, w2, w3,.
1, w2, w3,..., Wi are applied to the adaptive digital filter 21.
, And a speaker 25 as a secondary noise generation source provided in a vehicle room 24 as a sound field is driven by the output from the adaptive digital filter 21, and the output of the speaker 25 and the noise in the vehicle room 24 are compared with each other. The difference is detected by a microphone 26 provided in the vehicle cabin 24 for silencing confirmation, and an output signal of the microphone 26 is sent to the filter coefficient update operation circuit 23 as an error signal so that the square of the error signal becomes zero. , Wi are calculated.

Here, an adaptive digital filter 21, a digital filter 22, and a filter coefficient update operation circuit 23
Constitutes control means for inputting a signal highly relevant to the sound from the noise source as a reference signal and for generating a noise canceling signal having a phase opposite to that of the noise in the passenger compartment 24. And a noise canceling means for receiving a noise canceling signal output from the control means and generating a noise canceling sound.

As described above, the secondary noise that cancels the vehicle interior noise is generated from the speaker, so that the vehicle interior noise is canceled by the secondary noise output from the speaker, and the noise in the vehicle interior 24 is reduced. ing.

[0006]

However, in the conventional active noise control device, a microphone for sound-absorbing confirmation is provided on the headrest side of the front seat, as disclosed in Japanese Patent Application Laid-Open No. 5-273987. Thus, noise is detected at positions near both ears of the occupant to mute the sound.
In this case, the transmission characteristics for the vehicle interior sound,
Understanding the transfer characteristics between the loudspeaker as the secondary noise source and the microphone for noise reduction has an important effect on noise reduction.

[0007] However, when a microphone for silencing confirmation is provided in the headrest of the front seat, the position of the front seat can be moved back and forth. As a result, the relative position between the loudspeaker as a secondary noise source and the microphone for noise reduction changes in the vehicle interior, and as a result, the microphone for noise reduction confirmation in the vehicle interior The transfer function between the loudspeaker and the loudspeaker as the secondary noise source changes, and there is a problem that the noise cannot be sufficiently eliminated.

This problem similarly occurs when the angle of the backrest of the front seat is changed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an active noise control device capable of silencing vehicle interior noise based on low-frequency road noise.

[0010]

Means for Solving the Problems Claim 1 according to the present invention.
The active noise control device described above is provided with control means for inputting a signal highly relevant to a sound from a noise source as a reference signal, and generating a noise canceling signal having a phase opposite to the vehicle interior noise, and provided in the vehicle interior. And a noise canceling means for generating a noise canceling sound in response to a noise canceling signal output from the control means, and a microphone for confirming the muffling of vehicle interior noise, wherein the control means outputs an output signal from the microphone. In the active noise control device for lowering the level, the microphones are separately provided at positions near the left and right roof rails of the vehicle and opposite to ears of a seated occupant of the vehicle.

According to the active noise control device of the first aspect of the present invention, in the active noise control device for lowering the output signal level from the microphone, the microphone is located near the left and right roof rails of the vehicle. The noise at the position of the occupant's ear is eliminated by separately providing the occupant at the position facing the occupant's ear in the vehicle.

The reason why the microphone is provided at this position is that the sound pressure level of the vehicle interior noise at a position near the left and right roof rails of the vehicle and at a position facing the ears of a seated occupant of the vehicle and the sound pressure level of the vehicle. This is because the sound pressure level of the vehicle interior noise at the position of the occupant's ear is substantially equal.

According to a second aspect of the present invention, there is provided an active noise control apparatus which inputs a signal highly relevant to a sound from a noise source as a reference signal and generates a noise canceling signal having a phase opposite to that of the vehicle interior noise. Control means for providing, a canceling sound generating means provided in the vehicle interior and receiving a noise canceling signal output from the control means to generate a noise canceling sound, and a microphone for confirming the noise reduction of the vehicle interior noise, In the active noise control device for lowering the output signal level from the microphone by the control means, the microphone is located at substantially the center position between the left and right roof rails of the vehicle and at the passenger compartment side ear of a seated occupant of the vehicle. It is characterized in that it is provided at a position facing the same.

According to the active noise control device of the second aspect of the present invention, in the active noise control device for lowering the output signal level from the microphone, the microphone is positioned substantially at the center between the left and right roof rails of the vehicle. In addition, by providing the occupant in the vehicle at a position opposite to the ear on the passenger compartment side of the seated occupant, the noise at the position of the ear on the passenger compartment side of the occupant in the seated state on the vehicle is muted.

The reason that the microphone is provided at this position is that the sound pressure level of the vehicle interior noise in the vicinity of the ear on the passenger compartment side of the seated occupant of the vehicle is higher than the sound pressure level of the vehicle interior noise in the position near the ear portion on the vehicle window side. Although it is high, the sound pressure level is approximately equal to the sound pressure level of the vehicle interior noise at the position substantially at the center between the left and right roof rails of the vehicle and at the position facing the passenger compartment side ear of the seated occupant of the vehicle.

In the active noise control device according to the first or second aspect, a microphone may be further provided at a position near the center console.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An active noise control device according to the present invention will be described below with reference to an embodiment.

FIG. 1 is a schematic block diagram showing an installation position of a microphone for confirming silence and an installation position of a speaker as a secondary noise generation source in the active noise control apparatus according to one embodiment of the present invention. The active noise control device according to one embodiment of the present invention is for canceling vehicle interior noise of the vehicle 20 and illustrates a case where the vehicle 20 is a sedan.

In the active noise control apparatus 10 according to one embodiment of the present invention, the speaker 25 as a secondary noise generating source, which is a canceling sound generating means, is provided on the rear tray 33 of the vehicle 20, for example. Microphone 2 for
Reference numerals 6 and 27 are respectively provided near the right and left roof rails 34 and 35 and at positions facing the ears of the front seat occupant of the vehicle 20.

A digital filter, an adaptive digital filter, and a filter coefficient calculation circuit (not shown) which constitute a part of the active noise control device 10 are provided at appropriate positions on the vehicle 20. In FIG. 1, reference numerals 36 and 37 indicate left and right front seats, and reference numerals 38 and 39 indicate left and right rear seats.

The mounting positions of the microphones 26 and 27 will be further described by taking the microphone 27 as an example.

FIG. 2 is a cross-sectional view taken along the line II-II 'in FIG. 1, and is a diagram showing the details of the installation position of the microphone for confirming the silencing.

The microphone 27 is located on the garnish 43 with respect to the roof rail 35 formed by the ceiling outer panel 40 and the roof rail inner 41 of the vehicle 20 and at a position substantially opposed to the left ear of the occupant sitting on the left front seat. It is attached. Similarly, for the microphone 26,
It is mounted on the garnish 43 for the roof rail formed by the ceiling outer panel 40 and the roof rail inner 41 of the vehicle 20 and substantially opposite to the right ear of the occupant sitting on the right front seat. Reference numeral 44 indicates roof lining.

The configuration of the active noise control device using the microphones 26 and 27 is shown in the block diagram of the solid line in FIG. In this case, as shown in FIG. 3, the reference signal is converted into an adaptive digital filter 21a and a digital filter 22a set to have a transfer characteristic equivalent to that of the vehicle interior noise between the speaker 25 and the microphone 26.
The noise detection signal detected by the microphone 26 is used as an error signal, and the error signal and the output of the digital filter 22a are used as a filter coefficient update operation circuit 23a
, W3a,..., W3 based on the LMS algorithm so that the square of the error signal becomes substantially zero in the filter coefficient update operation circuit 23a.
ia, and filter coefficients w1a, w2a, w3
.., wia are set in the adaptive digital filter 21a.

Similarly, the reference signal is input to the adaptive digital filter 21b and the digital filter 22b set to have a transfer characteristic equivalent to that of the vehicle interior noise between the speaker 25 and the microphone 27. Using the detected noise detection signal as an error signal, the error signal and the output of the digital filter 22b are input to a filter coefficient update operation circuit 23b, and the square of the error signal becomes substantially zero in the filter coefficient update operation circuit 23b. , Wib, w3b,..., Wib are calculated based on the LMS algorithm.
The filter coefficients w1b, w2b, w3b,..., Wib are set in the adaptive digital filter 21b.

The output signal of the adaptive digital filter 21a in which the filter coefficient is set and the output signal of the adaptive digital filter 21b in which the filter coefficient is set are added to an adder 21d.
, And adds the signals, and the speaker 25 is driven by the output signal of the adder 21d to mute the noise at the positions of the microphones 26 and 27.

Next, the reason why the microphones 26 and 27 are separately provided at positions near the left and right roof rails 34 and 35 and opposite to the ears of the front seat occupant of the vehicle 20 will be described.

First, as described above, the microphones 26, 27 for confirming the silencing are connected to the left and right roof rails 34, 35.
, And are provided separately at positions facing the ears of the front-seat occupant of the vehicle 20, the positions are fixed positions. Therefore, the relative position between the speaker 25 and the microphones 26 and 27 is constant,
The transfer function for the noise in the passenger compartment during this period is not changed as in the related art by changing the position of the front seat.

Next, the transmission characteristic of the room noise from the speaker 25 to the position near the roof rail facing the ear position of the occupant sitting on the front seat and the room noise from the speaker 25 to the position near the ear position of the occupant sitting on the front seat 4 (a) and 4 (b) are shown by solid lines and broken lines, respectively, and are almost the same within the frequency range of 0 to 150 Hz. In FIG. 4, a solid line indicates a transmission characteristic for the vehicle interior noise from the speaker 25 to a position near the roof rail facing the ear of the occupant sitting in the front seat, and a broken line indicates the vicinity of the ear position of the occupant sitting in the front seat from the speaker 25. The figure shows the transmission characteristics for the vehicle interior noise. FIG. 4A shows the phase characteristic, and FIG.
(B) shows amplitude characteristics, which are based on data measured immediately before traveling.

On the other hand, the sound pressure level of the vehicle interior noise from the speaker 25 of the vehicle 20 during running to the vicinity of the roof rail position facing the ear of the front seat occupant, and the ear level of the front seat occupant from the speaker 25 of the vehicle 20 during running. The sound pressure level of the vehicle interior noise near the position is as shown by the solid line and the broken line in FIG. 5, and there is almost no difference at 40 Hz and at 80 Hz. In FIG. 5, the solid line indicates the sound pressure level of the vehicle interior noise from the speaker 25 to the position near the roof rail facing the ear position of the front seat occupant, and the broken line indicates the vehicle interior noise from the speaker 25 to the position near the ear of the front seat occupant. Shows the sound pressure levels of

As described above, the transmission characteristics of the vehicle interior noise from the speaker 25 near the position of the roof rail facing the ear position of the occupant sitting in the front seat and the vehicle interior from the speaker 25 near the ear position of the front seat occupant. The transmission characteristics with respect to noise are almost the same, and the sound pressure level of the vehicle interior noise near the position of the roof rail facing the ear position of the occupant sitting in the front seat from the speaker 25 and the vicinity of the ear position of the front seat occupant from the speaker 25 The microphones 26 and 27 are respectively located at positions near the left and right roof rails 34 and 35 and opposite to the ears of the front seat occupant of the vehicle 20 because the sound pressure levels of the vehicle interior noise are almost the same. It was provided.

Further, as a result of analyzing the cavity resonance mode of the passenger compartment of the passenger car including the trunk room 45 by the finite element method, the acoustic eigenmode at a low frequency is shown in FIG. A primary mode occurs, and a secondary mode occurs in the vehicle front-rear direction at frequencies near 80 Hz as shown in FIG.

On the other hand, when traveling on a rough road surface, the sound pressure distribution of vehicle interior noise based on road noise at a frequency near 40 Hz is shown in FIG. Measurement points 1 to 7 indicated by ○
8 (b). Similarly, when traveling on a rough road surface, the sound pressure distribution of vehicle interior noise based on road noise at a frequency near 80 Hz is indicated by a circle in the front-rear direction of the vehicle compartment in FIG. 9A schematically showing the vehicle compartment. As shown in FIG. 9B, the measurement points 1 to 7 indicated by. 8A and 9A, reference numerals 37 and 39 indicate a front seat and a rear seat, respectively.

As is clear from comparing FIG. 6 with FIG. 8 (b) and comparing FIG. 7 with FIG. 9 (b), the vehicle interior noise based on the low frequency road noise is affected by the acoustic eigenmode. You can see that they are strongly affected by These are the same whether the vehicle 20 is a sedan or a station wagon, and the same can be said regardless of the shape of the vehicle.

As described above, in the case of a low-frequency cabin sound,
Although the sound pressure distribution greatly fluctuates in the front-rear direction (running direction) of the vehicle compartment 24, the vehicle compartment 24 exhibits a relatively uniform distribution in the left-right direction and the vertical direction. This is because the transmission characteristics of the vehicle interior noise from the speaker 25 to the position of the roof rail facing the ears of the front seat occupant and the transmission characteristics of the vehicle interior noise from the speaker 25 to the vicinity of the ear position of the front seat occupant match at most frequencies. The sound pressure of the vehicle interior sound from the speaker 25 during traveling to the position of the roof rail facing the front seat occupant's ear and the speaker 2 during traveling
The reason is that the sound pressure of the room sound from No. 5 to the vicinity of the ear position of the front seat occupant has almost no difference.

Therefore, microphones 26 and 27 for silencing confirmation are separately provided at positions near the left and right roof rails 34 and 35 and opposite to the ears of the occupant sitting on the front seat, and the output is provided. By using the error signal, the active noise control device 10 can effectively cancel the vehicle interior noise based on the low-frequency road noise.

Further, a microphone 2 for confirming mute is provided.
6 and 27, respectively, left and right roof rail 3
The microphones 26 and 27 are fixed at positions near the earphones 4 and 35 and opposed to the ears of the occupant sitting on the front seat of the vehicle 20, respectively. 27, the head positions of the occupant in the driver's seat and the occupant in the front passenger's seat are sandwiched, so that it is possible to obtain a wide noise reduction area in the left-right direction of the head height (left-right direction relative to the traveling direction of the vehicle). Become. FIG. 10 shows microphones 26, 2
7 shows the sound deadening effect at a position near 7, and the solid line in FIG. 10 shows the case where the noise control is performed, and the broken line shows the case where the noise control is not performed. FIG. 11 shows the noise reduction effect in the vicinity of the ear position of the occupant sitting on the front seat. In FIG. 11, the solid line shows the case where noise control is performed, and the broken line shows the case where noise control is not performed. From now on, 4
It is clear that a great noise reduction effect is obtained in the frequency range near 0 Hz and in the frequency range near 80 Hz.

Next, as shown in FIG. 12, in addition to the microphones 26 and 27 for silencing confirmation, a microphone 28 for silencing confirmation may be further provided near the center console, for example, at the armrest position on the right front seat. Good.

When the microphone 28 is further provided, the adaptive digital filter 2 shown by a broken line in FIG.
1c, a digital filter 22c and a filter coefficient update operation circuit 23c set to have the same transfer characteristics as the transfer characteristics for the cabin noise between the speaker 25 and the microphone 28 are provided, and the output of the digital filter 22c and the output from the microphone 28 are provided. LMS receiving error signal
The filter coefficient w1 of the adaptive digital filter 21c is set so that the square of the error signal becomes substantially zero based on the algorithm.
c, w2c, w3c,..., wick are calculated, the operation filter coefficient is set in the adaptive digital filter 21c, the output of the adaptive digital filter 21c is supplied to the adder 21d, and the output of the adaptive digital filter 21a, 21b is added. Then, the speaker 25 is driven to mute the noise.

In such a case, the sound formed on the surface formed by the microphones 26, 27 and 28 indicated by oblique lines in FIG. 12 is silenced.

When the sound pressure level of the vehicle interior noise at the window-side (outer) ear of the occupant sitting in the seat (solid line) is compared with the sound pressure level of the vehicle interior noise at the inner ear (dashed line), As shown in FIG. 13, the sound pressure level of the vehicle interior noise to the ear inside the occupant is large for the vehicle interior noise of 40 Hz, and the vehicle pressure level to the window side ear of the occupant is 80 Hz for the vehicle interior noise of 80 Hz. The sound pressure level of the room noise is large.

Therefore, as shown in FIG. 14, in addition to the microphone 28, it is located substantially at the center between the left and right roof rails of the vehicle 20 and faces the ear of the front seat occupant of the vehicle 20 on the passenger compartment side. A microphone 29A and a microphone 29B are provided at a position and a substantially center position between the left and right roof rails of the vehicle and a position facing the passenger compartment side ear of the rear seated occupant of the vehicle 20, respectively. May be used as the error signal.

The sound pressure level of the vehicle interior noise at a position substantially at the center between the left and right roof rails of the vehicle 20 and the position facing the passenger compartment side ear of the vehicle occupant in the vehicle 20 and the vehicle seating This is because the sound pressure level of the vehicle interior noise at the position near the passenger compartment side ear portion of the occupant in the state is substantially the same, and thus the vehicle is located substantially at the center between the left and right roof rails and in front of the vehicle 20. By providing the microphone at a position facing the passenger compartment side ear of the seated occupant, the passenger compartment noise at the ear position on the passenger compartment side of the passenger having a large sound pressure level of the passenger compartment noise can be muted.

[0044]

As described above, according to the active noise control apparatus of the present invention, the same noise reduction effect as obtained at the installation position of the microphone for noise reduction confirmation can be obtained near the occupant's ear position. effective.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing an installation position of a microphone and a speaker as a secondary noise generation source for confirming silencing in an active noise control device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing details of an installation position of a microphone for silencing confirmation in the active noise control device according to one embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of an active noise control device according to one embodiment of the present invention.

FIG. 4 is a diagram showing a transfer characteristic from a speaker in the active noise control device according to one embodiment of the present invention;

FIG. 5 is a diagram showing a spectrum of room sound during traveling when the active noise control device according to one embodiment of the present invention is used.

FIG. 6 is an explanatory diagram showing an acoustic mode analysis result (for 40 Hz) of a vehicle compartment by a finite element method.

FIG. 7 is an explanatory diagram showing an acoustic mode analysis result (for 80 Hz) of a vehicle compartment by a finite element method.

FIG. 8 is a schematic diagram showing a sound pressure distribution (for 40 Hz) of vehicle interior noise based on low-frequency road noise.

FIG. 9 is a schematic diagram showing a sound pressure distribution (for 80 Hz) of vehicle interior noise based on low-frequency road noise.

FIG. 10 is a schematic diagram showing a noise canceling effect at a microphone position when the active noise control device according to the embodiment of the present invention is used.

FIG. 11 is a schematic diagram showing a noise canceling effect at an occupant ear position when the active noise control device according to one embodiment of the present invention is used.

FIG. 12 is a schematic block diagram showing another position of the microphone for silencing confirmation in the active noise control device according to one embodiment of the present invention.

FIG. 13 is a diagram showing a spectrum of room sound at an occupant's ear position during traveling in the case of the active noise control device according to one embodiment of the present invention.

FIG. 14 is a schematic block diagram showing yet another position of a microphone for silencing confirmation in the active noise control device according to one embodiment of the present invention.

FIG. 15 is a block diagram showing a configuration of a conventional active noise control device.

[Explanation of symbols]

Reference Signs List 20 vehicle 21, 21a, 21b, 21c ... adaptive digital filter 21d adder 22, 22a, 22b, 22c ... digital filter 23, 23a, 23b, 23c ... filter coefficient update operation circuit 24 ... vehicle room 25 ... speakers 26, 27, 28, 29A, 29B: Microphone for sound reduction confirmation 33: Rear tray 34, 35, 42 ... Roof rail 36, 37 ... Front seat 38, 39 ... Rear seat 40 ... Ceiling outer panel 41 ... Roof rail inner 43 ... Garnish 44 ... Roof lining

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hisashi Sano 1-4-1 Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Inventor Akira Takahashi 1-4-1-1 Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Inventor Kenichi Terai 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 72) Inventor Isao Kakuhari 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term (reference) 3D020 BA11 BB01 BC04 BC08 BD09 BE03 5D061 FF02 5J023 DB03 DC06 DD03

Claims (3)

[Claims] 1. A control means for inputting a signal highly relevant to a sound from a noise source as a reference signal and generating a noise canceling signal having a phase opposite to that of the vehicle interior noise, and provided in the vehicle interior and the control means. Noise canceling means for receiving a noise canceling signal output from the apparatus and generating a noise canceling sound, and a microphone for confirming muffling of vehicle interior noise, wherein the control means reduces the output signal level from the microphone. In the active noise control device, the microphones are separately provided at positions near the left and right roof rails of the vehicle and at positions facing the ears of a seated occupant of the vehicle. . 2. A control means for inputting a signal highly relevant to a sound from a noise source as a reference signal and generating a noise canceling signal having a phase opposite to that of the vehicle interior noise, and a control means provided in the vehicle interior. Noise canceling means for receiving a noise canceling signal output from the apparatus and generating a noise canceling sound, and a microphone for confirming muffling of vehicle interior noise, wherein the control means reduces the output signal level from the microphone. In the active noise control device, the microphone is provided at a position substantially at the center between the left and right roof rails of the vehicle and at a position facing the passenger compartment side ear of a seated occupant of the vehicle. Control device. 3. The active noise control device according to claim 1, wherein a microphone is further provided near the center console.