JPH05249986A - Reducing device for vehicle interior noise - Google Patents

Abstract

PURPOSE:To perform the interference of a noise with a control sound at optimum even in any microphone point in a vehicle chamber in a reducing device of vehicle interior noise for detecting a standard signal synchronized to the vibration of a noise source, providing a speaker and a microphone in the vehicle chamber, identifying the reversed transmitting characteristic of the transmitting characteristic to the microphone of the vibrating system of a vehicle body by use of the space transmitting characteristic between the speaker and the microphone preliminarily measured by white noise, and controlling the speaker by an adaptive controller so that the input of the microphone is minimized. CONSTITUTION:A plurality of speakers 14a-14d, a plurality of microphones 13a-14h, and one adaptive controller 2A, 2B are combined together to form a control system to a plurality of substantially independent acoustic spaces divided in a vehicle chamber 10. The acoustic space is preferably formed of the front seat 15A space of the vehicle and the rear seat 15B space, and the speaker for each acoustic space is provided on the floor surface of the vehicle and directed to the microphone in each acoustic space provided on the ceiling of the vehicle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle interior noise reduction device, and more particularly to a vehicle interior noise reduction device for use in a device for actively reducing low frequency noise in a vehicle interior such as an automobile. Is.

[0002]

2. Description of the Related Art Noise in the interior of a vehicle, such as an automobile, is due to the resonance phenomenon of the interior of a vehicle that forms a wide closed space under certain conditions. It is considered that this is due to a rotational order component or the like due to the explosion of an engine, and attempts have been recently made to adaptively reduce such vehicle interior noise, and an example thereof is shown in FIG.

In the figure, 1 is a vehicle such as an automobile, 10 is a passenger compartment in the vehicle 1, 11 is an engine, and 12 is an engine 11.
An engine vibration sensor or an engine speed sensor as a means for detecting a reference signal synchronized with the rotation of the vehicle, 13 is a microphone for detecting the noise level in the vehicle interior 10, 14 is a speaker for producing a noise reducing noise, and 15 is a passenger compartment 1
It is a sheet within 0.

Further, 2 is a sensor 1 installed in the vehicle 1.
2 and a controller for identifying the reverse transfer characteristic of the transfer characteristic of the vehicle interior space transfer system including the vibration system of the vehicle body which is excited by the output of the microphone 13 by the vibration of the engine A for converting the analog output of the sensor 12 into a digital output / D converter 2
1 and the spatial transfer characteristic G between the speaker and the microphone measured in advance for the digital output signal of the A / D converter 21.
A filter 22 that gives D, an adaptive filter 23 that inputs the output signal of the filter 22 as a reference signal, and D / that converts the output signal of the adaptive filter 23 into an analog signal.
A converter 24, a switch 25 for turning on / off this analog signal, a power amplifier 25 for amplifying the output signal of this switch 25 and giving it to the speaker 14, and an analog output of the microphone 13 converted to a digital signal for adaptation. An A / D converter 27 for giving a control signal to the filter 22, a white noise source 31, a switch 32 for turning on / off white noise from the white noise source 27, and a digital signal from the switch 32 is converted into an analog signal. D / A supplied to the speaker 14 via the power amplifier 25
It is composed of a converter 34 and a timer 35 that controls the switches 25 and 32 based on whether the key switch 16 is turned on or off.

In the operation of the configuration shown in FIG.
It can be divided into the initial setting identification mode of FIG. 5 and the normal identification mode of FIG. 6, and when the key switch 16 is turned on, the timer 35 turns on the switch 32 and turns off the switch 25 for a certain period of time. After the initial identification mode is entered and a certain period of time has passed, the latest adaptive filter 3
The tap coefficient of 3 is copied to the filter 22 as the spatial transfer function GD, and the timer 35 turns off the switch 32 and turns on the switch 25 to shift to the normal identification mode of FIG.

First, the initial identification mode shown in FIG. 5 will be described. The atmospheric pressure, temperature, humidity, etc. differ depending on the vehicle environment.
If the transmission delay between the speaker and the microphone is not taken into consideration, the control becomes uncontrollable or the operation becomes unstable, the convergence time is delayed, and the effect of reducing the residual noise deteriorates. Therefore, the spatial transfer characteristic (acoustic characteristic) GD between the speaker and the microphone is 5 does not use the vibration component from the engine 11, but instead the white noise of the digital signal generated from the white noise (random number sequence) source 31 provided in the controller 2 is D An analog signal is converted by the A / A converter 34 and the amplifier 26 and output from the speaker 14, and the white noise signal is picked up by the microphone 13 via the passenger compartment 10 and converted into a digital signal by the A / D converter 25. Then, the adaptive filter 33 receiving the white noise is controlled.

FIG. 7 shows a configuration example of the above adaptive filter 33. As the adaptive algorithm in this case, there are known known steepest descent method, learning identification method, LMS method, etc. The method is as follows.

That is, Z ^-1 represents a delay element for delaying the input signal X (n) for each sample, and h (0) to h (n-
1) is a filter (tap) coefficient for multiplying the output signal of each delay element Z ⁻¹ , and each filter coefficient is L
Updated sample by sample according to the MS algorithm: h (n + 1) = h (n) +2 μe (n) X (n). However, n = 0 ... i,
μ is the above step size, and by selecting the step size μ in this case, the output to the speaker 14 is performed by performing the convolution operation of multiplying and adding the filter coefficient to the input signal X (n) of each sample. Signal y
(n) is required.

By transmitting the speaker output y (n) to the microphone 13 via the vehicle compartment 10, the error component e reduced from the microphone 13 by the component Y (n) attenuated by the vehicle compartment 10. (n) = Y (n) -y (n) is generated,
If the filter coefficient is updated for each sample so that the microphone output e (n) is converged to the minimum value by the LMS algorithm, the characteristic GD of the vehicle interior space transfer system can be identified.

In this way, the characteristic G of the vehicle interior space transmission system
Since D was actually measured and obtained, in the adaptive control of the normal identification mode shown in FIG. 6, the spatial transfer characteristic GD from the speaker 14 to the microphone 13 and from the engine mount to the speaker 14 are obtained.
The transmission characteristic GP from the engine mount to the microphone 13 is GP = GD + G.
Therefore, after the fixed time set by the timer 35 has elapsed, only the remaining transfer characteristic GC is identified by the adaptive filter 23 in FIG.

In the case of the adaptive control shown in FIG. 6, the input signal becomes the engine vibration component X (n) from the vibration sensor 12, and the component Y (n) corresponds to the noise around the ears of the passenger in the seat. Become.

Thus, the speaker measured in advance is
The filter 22 of the spatial transfer characteristic GD between the microphones has a filter configuration as shown in FIG. 8 by being given the filter coefficients h1 ... hn obtained by the adaptive filter 33, and by inserting this filter before the adaptive filter 23, The adaptive control can be applied from the beginning in consideration of the transmission delay between the speaker and the microphone, and it follows the frequency change due to the engine speed change, and follows the characteristic change of the vibration transmission system from engine vibration to vehicle interior noise. In addition, the transmission characteristics that change depending on the number of passengers are followed, the degree of convergence is improved, and the effect of reducing residual noise is also improved.

On the other hand, in the passenger compartment of a passenger car or the like, the number of control (evaluation) points at which noise is desired to be reduced is not limited to one as described above, and the sound pressure level (magnitude) at each control point is different. The frequency also changes depending on the engine rotation, which is different and is a noise source.

From this point of view, various conventional techniques in which a plurality of microphones and speakers are combined have been proposed.
For example, in Japanese Patent Laid-Open No. 3-203490, as schematically shown in FIG. 9, microphones 13a to 13d are installed near the front seat 15A, microphones 13e to 13h are installed near the rear seat 15B, and the vehicle interior 10 The speakers 14a and 14b are installed in the front part of the above, and the speakers 14c and 14d are installed in the rear part.

A controller 2 for controlling the output of the speakers 14a to 14d based on the output signals of the microphones 13a to 13f is provided. Although not shown, the controller 2 receives an output signal of a vibration sensor as a means for detecting a reference signal synchronized with the rotation of the engine, and further, a microphone 1 provided on the front seat 15A side in the vehicle compartment.
Sum of squares of information from 3a to 13d and sum of squares of information from microphones 13e to 13h provided on the side of the rear seat 15B,
Due to the difference, one controller 2 has four speakers 1
The outputs of 4a to 14d are controlled.

[0016]

However, in the prior art in which such a plurality of speakers and microphones are combined, the acoustic paths from each speaker to the control point of each microphone are set for all combinations in the example of FIG. Among these acoustic paths, as shown by the dotted line, of the paths formed when the outputs of the front seat side speakers 14a and 14b are simultaneously controlled from the rear seat side microphones 13e to 13h, for example. In this case, since the driver in the front driver's seat is located in the middle of the control sound path from the speaker 14a to the microphone 13f as shown in FIG. 10, for example,
Rather than hearing the result of sound wave interference between the engine noise and the control sound (cancellation sound) from the speaker 14a, the control sound from the speaker 14a is directly observed, which is worse than in the uncontrolled state.

Further, in the case of this Japanese Patent Laid-Open No. 3-203490, since the outputs of the front seat side microphone and the rear seat side microphone are simultaneously controlled from the front, rear, left and right speakers, the noise reduction of each seat should be averaged. Although effective, for example, when the noise level of the front seat <the noise level of the rear seat,
As indicated by the diagonal lines in 1, the observation sound of the front seat, which is the midpoint of the acoustic path from the front seat side speaker to the rear seat side microphone, becomes almost the same as the rear seat noise level.
There is a problem that the noise reduction effect of the front seats is not exerted.

Therefore, according to the present invention, a reference signal synchronized with the vibration of a noise source is detected, a speaker and a microphone are provided in the vehicle compartment, and the spatial transfer characteristic between the speaker and the microphone, which is measured in advance by white noise, is used. A vehicle interior noise reduction device in which an adaptive controller controls the speaker so as to identify a reverse transmission characteristic of a transmission characteristic of a vibration system of a vehicle body to the microphone by a reference signal and minimize the input of the microphone. The objective is to optimize the interference between noise and control sound at any microphone point.

[0019]

In order to solve the above problems, in a vehicle interior noise reduction device according to the present invention, a plurality of speakers, a plurality of microphones, and one adaptive controller are combined in the vehicle interior. A control system for a plurality of divided acoustic spaces that are substantially independent of each other is configured.

Further, in the present invention, the acoustic space is composed of a front seat space and a rear seat space of the vehicle, and the speakers of each acoustic space are provided near the floor surface of the vehicle and provided on the ceiling of the vehicle. It may be directed to a microphone in each acoustic space.

[0021]

According to the present invention, since the acoustic spaces of a plurality of control systems each constituted by a combination of a plurality of speakers, a plurality of microphones and one adaptive controller are substantially independent in the vehicle interior, In the acoustic space, control sounds from other acoustic spaces are less likely to be received, so that the ears of the passengers in each acoustic space can reduce annoying speaker control sound as an intermediate sound until the control sound reaches the microphone. ..

Further, when the above acoustic space is composed of a front seat space and a rear seat space of the vehicle, each speaker in each acoustic space is provided on the floor surface of the vehicle, and these speakers are installed in the vehicle. If the microphones are arranged so as to face the microphones in each acoustic space provided on the ceiling (near the occupants' ears), the independence of each acoustic space will be further improved, and the leakage noise from other acoustic spaces will be reduced as much as possible. Therefore, it is possible to reduce the speaker control sound which is still jarring.

Further, the acoustic space is composed of a front seat space and a rear seat space of the vehicle, and a speaker in each acoustic space is provided near the floor surface of the vehicle and a microphone in each acoustic space is provided on the ceiling of the vehicle. By directing it, it is possible to reduce the vehicle interior noise with only two control systems.

[0024]

1 shows an embodiment of a vehicle interior noise reduction device according to the present invention. The difference between this embodiment and the conventional example shown in FIG. 9 is that the front seat 15A side is different. Microphone 13a ~
13d, the front seat 15A side speakers 14a and 14b, and the controller 2A are combined, and the front seat 1
5A independent acoustic control system is formed, and the rear seat 15B side microphones 13e to 13h and the rear seat 15B side speaker 14 are formed.
The point is that the c, 14d and the controller 2B are combined to form an independent acoustic control system for the rear seat 15B.

Therefore, in the control system of the front seat 15A, the engine is designed so that the acoustic interference effect at these control points is maximized from the speakers 14a and 14b to the microphones 13a to 13d as shown by the dotted line. The controller 2A performs control in response to the output signal of the vibration sensor (not shown) as a means for detecting the reference signal synchronized with the rotation of the. Further, in the control system of the rear seat 15B, the speakers 14c and 14d to the microphone 13e to
The controller 2B also receives the output signal of the vibration sensor and performs control so that the acoustic interference effect at these control points becomes maximum with respect to 13h.

In such an embodiment, in particular, the speakers 14a to 14d are provided on the vehicle floor portion or the door portion in the front portion of the seat and the front seat side speaker 14 as shown in FIG.
a and 14b are installed toward the microphones 13a to 13d, and the rear seat side speakers 14c and 14d are microphones 13e to 13d.
By installing toward the h, the front seat space and the rear seat space become physically independent from each other, and the acoustic interference effect at the control point is optimized.

As shown in FIG. 2, the control sounds from the front seat side speakers 14a and 14b are transmitted to the rear seat side microphone 13.
e to 13h also slightly leaks, and the rear seat side speaker 1 similarly.
Control sounds from 4c and 14d are front seat side microphones 13a to
Although it slightly leaks to 13d as well, since the front seat control system and the rear seat control system are substantially independent, no abnormal phenomenon such as oscillation of the control system occurs.

That is, each of the above leakage sounds is the interference result γ = between the engine noise α and the leakage sound β at each microphone point.
Since α + β is input from each of the microphones 13a to 13h and a control sound is output from each dedicated speaker, an abnormal phenomenon such as oscillation of the control system does not occur, and control can be executed without problems.

3 (1) and 3 (2) respectively show the front seat 15
The experimental data of the engine noise α in A and the rear seat 15B and the control sound from the speaker are shown, and as can be seen from these graphs, the noise reduction is successful over a relatively wide range.

Further, from the above, the front seat 15
The control can be executed naturally without being particularly disturbed by the conversation between the passengers in A and the rear seat 15B.

[0031]

As described above, in the vehicle interior noise reduction device according to the present invention, a plurality of speakers, a plurality of microphones, and a single adaptive controller are combined to be substantially independent of each other. Since the control system for the plurality of acoustic spaces is configured, it is possible to reduce the occupant from directly receiving the control sound from the speaker, and it is possible to remove the offensive sound.

Further, the above acoustic space is composed of a front seat space and a rear seat space of the vehicle, a speaker of each acoustic space is provided on the floor of the vehicle, and a microphone in each acoustic space is provided on the ceiling of the vehicle. If it is configured so as to be directed to, it is possible to reduce the vehicle interior noise with only two control systems.

[Brief description of drawings]

FIG. 1 is a block diagram schematically showing a configuration of an embodiment when a vehicle interior noise reduction device according to the present invention is seen in a plan view.

FIG. 2 is a diagram schematically showing an embodiment when a vehicle interior noise reduction device according to the present invention is viewed laterally.

FIG. 3 is a graph showing the sound reduction effect of the vehicle interior noise reduction device according to the present invention.

FIG. 4 is a block diagram showing a configuration example of a conventional vehicle interior noise reduction device.

FIG. 5 is a block diagram showing a configuration for measuring a spatial transfer characteristic between a speaker and a microphone in an initial identification mode.

FIG. 6 is a block diagram showing a configuration for measuring a reverse transfer characteristic with respect to a transfer characteristic of a vehicle interior space transfer system including a vehicle body vibration system in a normal identification mode.

FIG. 7 is a block diagram showing a configuration of an adaptive filter used in a vehicle interior noise reduction device according to the present invention and a conventional example.

FIG. 8 is a block diagram showing a configuration of a filter having filter coefficients obtained by initial identification.

FIG. 9 is a block diagram showing a conventional example disclosed in Japanese Patent Laid-Open No. 3-203490.

FIG. 10 is a schematic diagram for explaining a drawback of the conventional example.

FIG. 11 is a graph diagram for explaining a defect of the conventional example.

[Explanation of symbols]

 1 Vehicle 2 (2A, 2B) Controller 10 Cabin 11 Engine 12 Engine Vibration Sensor (Engine Rotation Speed Sensor) 13 (13a-13h) Microphone 14 (14a-14d) Speaker 15A Front Seat 15B Rear Seat 22 Filter 23, 33 Adaptive filter 31 White noise source In the drawings, the same reference numerals indicate the same or corresponding portions.

Front Page Continuation (72) Inventor Kazumi Yamaguchi 8 Soil Shelf, Fujisawa City, Kanagawa Prefecture Transtron Fujisawa Office

Claims (2)

[Claims] 1. A reference signal synchronized with vibration of an engine is detected, a speaker and a microphone are provided in a vehicle compartment, and a spatial transfer characteristic between the speaker and the microphone, which is measured in advance by white noise, is used to detect the reference signal of the vehicle body. In a vehicle interior noise reduction device in which an adaptive controller controls the speaker so as to identify a reverse transfer characteristic of a transfer characteristic of the vibration system to the microphone and minimize the input of the microphone, a plurality of speakers and a plurality of microphones are provided. And a single adaptive controller in combination to form a control system for a plurality of substantially independent acoustic spaces divided in the vehicle interior. 2. The acoustic space is composed of a front seat space and a rear seat space of a vehicle, the speakers of each acoustic space are provided near the floor of the vehicle, and the acoustics provided on the ceiling of the vehicle. The vehicle interior noise reduction device according to claim 1, wherein the device is directed to a microphone in a space.