JPH064085A - Active noise reducing device for vehicle - Google Patents

Abstract

PURPOSE:To obtain the active noise reducing device of simple constitution which securely reduces the undesired sound in a vehicle, specially, during a travel by outputting a proper sound wave canceling the noise into the cabin. CONSTITUTION:During the travel of the vehicle VH, an engine-side vibration detector ED detects the vibration of an engine 2 and an exhaust-pipe side vibration detector PD detects the vibration of an exhaust pipe 3; and their outputs signals are supplied to a filter means FM. An output signal corresponding to the residual noise in the cabin is supplied from a residual noise detector MC to a filter means FM. The filter means FM controls the driving of a sound wave output device SE according to those output signal and outputs the sound wave into the cabin so as to cancel the noise in the cabin. The filter coefficient of, for example, an adaptive filter 10f is updated in order according to adaptive algorithm corresponding to the output signal of the residual noise detector MC and control is so performed that the output signal of the residual noise detector MC becomes minimum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active noise reduction device mounted on a vehicle, and in particular, reduces noise by outputting a sound wave that can cancel the noise into a vehicle interior of a vehicle equipped with an engine and an exhaust pipe. The present invention relates to an active noise reduction device for a vehicle.

[0002]

2. Description of the Related Art Conventionally, an active noise attenuating device, that is, an active noise attenuator, which minimizes the sound pressure level in a closed space by interfering a secondary sound generated from a loudspeaker with a primary sound transmitted from a noise source. Mold noise reduction devices are known. For example, in Japanese Unexamined Patent Publication No. 3-203792, as an active noise control device, even if there are a plurality of noise sources, it is intended to reduce noise generated from these noise sources simultaneously and in a well-balanced manner. An apparatus configured as described above has been proposed.

That is, the noise generation states of a plurality of noise sources are detected by the noise generation state detection means, and the detected values are used as reference signals, and the number of control sound sources is individually set for each reference signal. Each of the adaptive filters is input to be subjected to filtering processing, and the outputs of the plurality of adaptive filters are added by the control sound source driving means for each control sound source and supplied to the control sound source, and the control sound based on the drive command is generated from the control sound source. An apparatus has been proposed that updates the filter coefficient of the adaptive filter so that the noise at the observation position is minimized based on the detection value of the residual noise at the observation position by the residual noise detection unit and the detection value of the noise generation state detection unit. .

In the above publication, various examples are given as a plurality of noise generation state detecting means.
Output signals from a crank angle sensor and a vibration pickup of a suspension are used for a muffled noise in a vehicle compartment due to engine vibration, an exhaust noise, and a road noise transmitted to the vehicle compartment due to unevenness of a road surface. Furthermore, as examples of the detection contents of the other noise generation state detecting means, there are listed pickup signals for wind noise, pickup signals for case vibration of the differential gear and the transmission, and the like. In addition, the same active noise control device is disclosed in Japanese Patent Application Laid-Open Nos. 3-203496 and 3-203497.

[0005]

However, in all the publications, the vibration transmitted to the vehicle body through the support member from the exhaust pipe, which has a great influence on the muffled sound, and the combination of the vibration and the engine vibration are mentioned. It has not been. The so-called muffled noise is generated because vibrations directly transmitted from the engine to the traveling vehicle and vibrations transmitted through the drive system parts, the exhaust pipe, etc., which are excited by the vibrations, are superposed. Processing is required according to the vibration state of the parts. In this regard, the engine and drive system components can be responsive to an allowable range even when the output signal of the crank angle sensor is used as a reference signal, but also with respect to the vibration transmitted to the vehicle body via the exhaust pipe support member. If the output signal of the crank angle sensor is used as a reference signal, a filter coefficient for a long time is required, and a satisfactory response cannot be obtained.
Therefore, it is difficult to properly suppress the muffled sound.

[0006] Therefore, the present invention provides an active noise reduction device for reducing the noise by outputting an appropriate sound wave, which can cancel out the muffled noise of a running vehicle with a simple structure, to the vehicle interior. The purpose is to do.

[0007]

To achieve the above object, the present invention provides a vehicle V as shown in FIG.
In the active noise reduction device that controls the sound wave output device SE by driving the sound wave output device SE in accordance with the noise generation state of H to output sound waves into the vehicle interior of the vehicle VH and cancel the noise in the vehicle interior, the engine 2 of the vehicle VH Engine side vibration detector ED arranged on an engine support member EM for supporting
An exhaust pipe side vibration detector PD for detecting a vibration state by arranging an exhaust pipe 3 connected to the engine 2 on an exhaust pipe support member PS for supporting a vehicle VH, and a residual noise detection for detecting a residual noise in a vehicle compartment. Sound output device such that the output signal of the residual noise detector MC is minimized according to the output signals of the residual noise detector MC and the engine side vibration detector ED and the exhaust pipe side vibration detector PD. A filter means FM for driving and controlling SE is provided.

In the above active noise reduction device, the engine side vibration detector ED and the exhaust pipe side vibration detector PD are respectively constituted by acceleration sensors, and the filter means FM is
Engine side vibration detector ED and exhaust pipe side vibration detector PD
It is assumed that a plurality of adaptive digital filters 10f each connected to
Each filter coefficient of 0f may be sequentially updated based on an adaptive algorithm corresponding to the output signal of the residual noise detector MC, and the output signal of the residual noise detector MC may be controlled to be the minimum.

[0009]

In the present invention having the above-described structure, while the vehicle VH is traveling, the engine side vibration detector ED detects the vibration of the engine 2 and the exhaust pipe side vibration detector PD.
The vibrations of the exhaust pipe 3 are detected by the, and these output signals are supplied to the filter means FM. On the other hand, an output signal corresponding to the residual noise in the vehicle compartment is supplied from the residual noise detector MC to the filter means FM. Then, in the filter means FM, the residual noise detector MC according to these output signals
The sound wave output device SE is drive-controlled so that the output signal of the signal is minimized. That is, a sound wave that can cancel the noise in the vehicle interior is output to the vehicle interior.

When the engine-side vibration detector ED and the exhaust pipe-side vibration detector PD are respectively composed of acceleration sensors, and the filter means FM is provided with a plurality of adaptive digital filters 10f, the respective sensors are used. The filter coefficient of each adaptive digital filter 10f which inputs the output signal of the acceleration sensor is sequentially updated based on the adaptive algorithm according to the output signal of the residual noise detector MC, and the output signal of the residual noise detector MC becomes the minimum. Controlled as. That is, the transfer function of each adaptive digital filter 10f is set to be equal to the transfer function in the vehicle interior based on the output signal of each acceleration sensor and according to the output signal of the residual noise detector MC. In response, the drive signal is output to the sound wave output device SE. In response to this drive signal, the sound wave output device SE outputs a sound wave that can cancel the noise into the vehicle interior, and the noise inside the vehicle interior is reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a vehicle active noise reduction device according to the present invention will be described below with reference to the drawings. FIG. 2 shows the overall construction of an embodiment of the present invention, in which an exhaust pipe 3 is connected to an engine 2, and these are supported by a vehicle body 1 via an engine mount 4 and an exhaust pipe support 5, respectively. In the present invention, the exhaust pipe 3 refers to an assembly including the catalytic converter 3a, the muffler 3b, and the like, and the exhaust pipe assembly is also referred to in the following description unless otherwise specified. The engine mount 4, which is an engine support member, is provided with an acceleration sensor 6, which functions as an engine-side vibration detector. An acceleration sensor 7 is also provided on the exhaust pipe support 5, which is an exhaust pipe support member, and this functions as an exhaust pipe side vibration detector.

On the other hand, speakers 8a to 8d, which are sound wave output devices for outputting sound waves, are arranged in the vehicle compartment 1a on both sides of the front seat and on the rear sides of the rear seat of the vehicle body 1, respectively. Microphones 9a to 9d, which are residual noise detectors, are arranged in the section so as to direct the vicinity of the head of each seat in the vehicle interior 1a. The microphones 9a to 9d and the acceleration sensors 6 and 7 are electrically connected to the controller 10, and the detection outputs are individually input to the controller 10. Further, the controller 10 is electrically connected to the speakers 8a to 8d, and is configured so that sound waves are output from the speakers 8a to 8d according to a drive signal output from the controller 10.

The controller 10 has respective speakers 8a to 8d (8 in FIG. 3) as shown in FIG.
a) and 8b only), each of which has four adaptive digital filters 10f (one of which is shown by a broken line in FIG. 3) for sequentially controlling the filter coefficients W _{111 and the} like. An adaptive algorithm LMS (Least Mean Square Algorithm) is configured. The transfer function of the adaptive digital filter 10f is the transfer function C ₁₁ in the passenger compartment 1a.
The filter coefficients W _{111 and the} like are sequentially updated by the adaptive algorithm LMS so as to identify them.

That is, the output signals of the acceleration sensors 6 and 7 are A
The signal is converted into a digital signal by a / D converter (not shown) and is input to the adaptive digital filter 10f as a reference signal, and the detection outputs of the microphones 9a to 9d are amplified through an input amplifier (not shown). After the aliasing noise is blocked by a singing filter (not shown), it is converted into a digital signal by an A / D converter (not shown) and input to the adaptive digital filter 10f. . The output digital signal of the adaptive digital filter 10f is converted into an analog signal by a D / A converter (not shown), smoothed by, for example, a smoothing filter (not shown), and then passed through a power amplifier (not shown). It is configured to be amplified and supplied to the speakers 8a to 8d as a drive signal.

As shown in FIG. 3, the output signal of the acceleration sensor 6 provided on the engine mount 4 is x ₁ (n) (sample value at the sampling time n), and the exhaust pipe support 5
X ₂ (n) is the output signal of the acceleration sensor 7 provided in, and y ₁ (n) and y ₂ (n) are the output signals that drive the speakers 8a and 8b.
Then, assuming that error signals indicating residual noise from the microphones 9a and 9b are e ₁ (n) and e ₂ (n), the adaptive digital filter 10f processes as follows.
Note that the first digit subscript (1 in this case) of the filter coefficient W _{111 and the} like shown in FIG. 3 corresponds to the subscripts of the signals x ₁ (n) and x ₂ (n),
The second digit subscript corresponds to the subscript of the signals y ₁ (n) and y ₂ (n), and is 3
The subscripts of the digits are attached so as to correspond to the subscripts of the signals e ₁ (n) and e ₂ (n), respectively. Further, the transfer function C ₁₁ is the speaker 8a.
The transfer function between (driven by the signal y ₁ (n)) and the microphone 9a (outputting the error signal e ₁ (n)) is shown, and the subscripts correspond to the subscripts of the respective signals. Although only the two speakers 8a and 8b and the two microphones 9a and 9b are shown in FIG. 3 for the sake of drawing, the four speakers 8a to 8d and the four microphones 9a to 9d shown in FIG. On the other hand, the configuration is twice as large as that shown in FIG.
16 transfer functions, C _{11 to} C ₄₄ , and filter coefficient W
₁₁₁ made a total of 32 pieces of ~W _244.

In the controller 10 of FIG. 3, the filter coefficients W ₁₁₁ and W of each adaptive digital filter 10f are first based on the output signal x ₁ (n) of the acceleration sensor 6.
₁₁₂ , W ₁₂₁ , W ₁₂₂ are calculated. Similarly, based on the output signal x ₂ (n) of the acceleration sensor 7, the filter coefficient W ₂₁₁ ,
W ₂₁₂ , W ₂₂₁ , W ₂₂₂ are calculated. Then, the filter coefficients W ₁₁₁ , W ₁₁₂ , W ₂₁₁ , and W ₂₁₂ are added, and the drive signal y ₁ (n) is set based on the addition result. The filter coefficients _{W 121, W 122, W 221} , W 22 2 is added, the drive signal y ₂ based on the sum (n) is set. These filter coefficients W ₁₁₁ , W ₁₂₁ , W ₂₁₁ ,
W ₂₂₁ is adapted to be modified and updated by the adaptive algorithm LMS calculated according to the error signal e ₁ (n). Similarly, the filter coefficient W ₁₁₂ ,
W ₁₂₂ , W ₂₁₂ , W ₂₂₂ are corrected by the adaptive algorithm LMS calculated according to the error signal e ₂ (n),
It is configured to be updated.

Next, the operation of the active noise reduction system of this embodiment will be described. While the vehicle is running, engine vibration of an order component proportional to the number of revolutions of the engine 2 and exhaust pipe vibration generated when the vibration is transmitted to the exhaust pipe 3 are transmitted to the vehicle body 1 and a so-called muffled noise is generated in the vehicle interior 1a. Occurs. The engine mount 4 is provided with an acceleration sensor 6, and the acceleration sensor 6 outputs an output signal x according to engine vibration.
₁ (n) is supplied to the controller 10. Similarly, the output signal x from the acceleration sensor 7 provided in the exhaust pipe support 5
₂ (n) is supplied to the controller 10. Controller 1
0, the output signals x ₁ (n) of the acceleration sensors 6 and 7,
x ₂ (n) and the error signals e of the microphones 9a and 9b
_The above-described processing is performed according to _{1 (n)} and e _{2 (n)} , and the driving signal y
₁ (n) and y ₂ (n) are output, and the speakers 8a and 8b are driven (hereinafter, the speakers 8a and 8b will also be referred to in accordance with FIG. 3).
Although b will be described, the same applies to the speakers 8c and 8d).

Thus, from the speakers 8a, 8b to the passenger compartment 1a
Sound waves are output inside. That is, sound waves are output so as to be combined with the noise in the vehicle interior 1a and cancel each other out. Then, the residual noise in the passenger compartment 1a is caused by the microphones 9a and 9b.
Detected by, and input to the adaptive digital filter 10f as error signals e ₁ (n) and e ₂ (n). Then, the output signal x of the acceleration sensors 6 and 7 is set by the adaptive algorithm LMS set according to the error signals e ₁ (n) and e ₂ (n).
_In order to identify the transfer function of the adaptive digital filter 10f as the transfer function between the speakers 8a, 8b and the microphones 9a, 9b in the vehicle interior 1a according to ₁ (n), x ₂ (n), the filter coefficient W _111, etc. Will be updated.

In other words, each adaptive digital filter 1
The filter coefficients W _{111 of} 0f are output signals x ₁ (n) and x ₂ (n) of the acceleration sensors 6 and 7 and the microphones 9a and 9b.
The error signal e ₁ (n), according to e ₂ (n), is sequentially updated according to the adaptive algorithm LMS, speaker as remaining noise signal serving as error signal _{e 1 (n), e 2} (n) is minimized 8
The drive signals y ₁ (n) and y ₂ (n) of a and 8b are output, and the sound waves output from the speakers 8a and 8b in response thereto cancel out the noise in the vehicle interior 1a.

Thus, in the present embodiment, the adaptive digital filter 10f is based on the output signals of the acceleration sensors 6 and 7, that is, the signals corresponding to the vibrations of the supporting portions of the engine 2 and the exhaust pipe 3 which greatly affect the muffled noise. Is controlled and the order (tap length) of the filter can be reduced, so that the calculation time is short and good responsiveness is obtained.

[0021]

Since the present invention is configured as described above, it has the following effects. That is, in the vehicle active noise reduction device of the present invention, the sound wave output device is configured to be driven and controlled by the filter means according to the output signals of the engine side vibration detector and the exhaust pipe side vibration detector. Since each of the vibration detectors is arranged at a position that greatly affects the muffled sound in the vehicle interior, the noise can be reliably reduced, and the order of the filter can be reduced as compared with the conventional device. Therefore, good responsiveness can be obtained.

When the engine-side vibration detector and the exhaust pipe-side vibration detector are each composed of an acceleration sensor and the filter means is provided with a plurality of adaptive digital filters, a simple structure and a good response are obtained. It is possible to secure the sex.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an active noise reduction device for a vehicle according to the present invention.

FIG. 2 is a perspective view showing the overall configuration of an embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a controller according to an embodiment of the present invention.

[Explanation of symbols]

 1 Car Body 2 Engine 3 Exhaust Pipe 4 Engine Mount (Engine Support Member) 5 Exhaust Pipe Support (Exhaust Pipe Support Member) 6 Acceleration Sensor (Engine Side Vibration Detector) 7 Acceleration Sensor (Exhaust Pipe Side Vibration Detector) 8a-8d Speaker (Sound wave output device) 9a to 9d Microphone (residual noise detector) 10 Controller (filter means) 10f Adaptive digital filter

Claims (2)

[Claims] 1. An active noise reduction device for a vehicle, which controls a sound wave output device to drive a sound wave output device to output a sound wave in a vehicle interior of the vehicle in accordance with a noise generation state of the vehicle and cancel the noise in the vehicle interior. In an engine-side vibration detector that is disposed on an engine support member that supports the engine of the vehicle and that detects a vibration state, and an exhaust pipe that is connected to the engine is disposed on an exhaust pipe support member that supports the vehicle. Exhaust pipe side vibration detector for detecting a state, residual noise detector for detecting residual noise in the vehicle compartment, output signal of the residual noise detector, engine side vibration detector and exhaust pipe side vibration detector And a filter means for driving and controlling the sound wave output device so that the output signal of the residual noise detector is minimized in accordance with the output signal of 1. 2. The engine-side vibration detector and the exhaust pipe-side vibration detector are each configured by an acceleration sensor, and the filter means is connected to the engine-side vibration detector and the exhaust-pipe-side vibration detector, respectively. A plurality of adaptive digital filters, the filter coefficients of each of the plurality of adaptive digital filters are sequentially updated based on an adaptive algorithm corresponding to the output signal of the residual noise detector, and the output signal of the residual noise detector is minimized. The active noise reduction device for a vehicle according to claim 1, wherein the active noise reduction device is controlled so that