JP2000020073A - Muffler device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a noise according to a noise characteristic is a cabin and to improve a muffler effect even in various cabins with different constitution by measuring the transfer characteristic in the cabin itself, calculating a noise transfer function and correcting an input or an output signal of an adaptive control means with the noise transfer function. SOLUTION: A noise is detected by a reference sensor 31 for a noise source outside the cabin 8, and a control sound in an opposite phase sound is emitted from a speaker 34 for the noise propagated from the cabin 8 outside into the cabin 8 to attenuate the noise. However, since the control sound from the speaker 34 generated based on the detection of the reference sensor 31 doesn't correspond precisely to the noise in the cabin 8, and the muffler effect sometimes are reduced. Then, a filter 36 is provided, and the detected signal of the reference sensor 31 is corrected so as to correspond to the noise propagated through the cabin 8 by the noise transfer function based on the vibration characteristic of the cabin 8 for the noise of the cabin 8 outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a configuration of an active silencer for attenuating noise in a cabin mounted so as to cover a driving section of a work vehicle.

[0002]

2. Description of the Related Art Conventionally, in a work vehicle such as a tractor, a combine, or a backhoe, noise detecting means is provided, the noise is detected by the noise detecting means, and a vibration having an opposite phase to the detected noise is generated. Active silencers configured to provide and reduce the noise are well known. Conventionally,
The noise detecting means is disposed at a specific noise generating location, for example, near the engine or the transmission case outside the cabin, and detects noise in opposite phase to the noise by detecting the noise by the noise detecting means. The noise is output to the cabin of the vehicle and can be attenuated for noise propagating in the cabin. For example, Japanese Unexamined Utility Model Publication No. 5-55198 and Japanese Unexamined Patent Application Publication No. 8-76772. In addition, adaptive control means that configures the control sound source based on the detection values of the noise detection means and the muffling effect detection means so that the detection value of the muffling effect detection means is minimized generally has a human hearing characteristic. The corresponding filter is used before and after the adaptive control means so as to improve the silencing effect of the control sound in a sound range that is easily perceived by humans, and the frequency characteristic of the sound input to the adaptive control means is made flat. The adaptive control means is configured to perform accurate signal processing.

[0003]

In order to most effectively obtain the noise reduction effect in the cabin, it is important that the noise reduction control sound be an anti-phase sound that accurately corresponds to the noise characteristics in the cabin. However, due to the transmission characteristics based on the material and support structure of the cabin itself, noise at a certain frequency is amplified while the noise passes through the cabin. When,
The frequency characteristics are different from the propagation noise at the time when the sound propagates in the cabin and reaches a place where the sound is synthesized with the control sound from the control sound source. Since the control sound from the control sound source is based on the detection of the noise detection means, it corresponds to the noise near the noise detection position.Therefore, the control sound from the control sound source passes through the cabin from the noise detection position. There is a problem that the frequency noise amplified by the vibration characteristics of the cabin remains without being silenced because the frequency noise does not accurately correspond to the noise that has been propagated. The arrangement of the filter in the above-mentioned prior art is to attenuate a constant frequency sound assuming a sound range perceived by a human, out of the noise in the cabin that is not sufficiently attenuated. Is effective in increasing the precision of the signal processing of the adaptive control means, but in any case, it does not emit a control sound accurately in response to the propagation noise in the cabin, so that the noise reduction effect is improved. There is a limit.

[0004]

The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described. First, an active silencer that generates a control sound that attenuates noise propagating in the cabin supported by the fuselage and silences the interior of the cabin, comprising: a noise detection unit;
A control sound source for generating the control sound, an adaptive control means for inputting a detection signal of the noise detection means and outputting a control signal related to the control sound to the control sound source, and a muffling effect detecting means; The noise transfer function is calculated by measuring the transfer characteristic of the adaptive control means, and one or a plurality of correction means for correcting the input or output signal of the adaptive control means by the noise transfer function are provided. In the above configuration, the noise transfer function is based on a transfer characteristic of the cabin itself to noise or vibration of the engine, or based on a transfer characteristic of the cabin itself to noise or vibration through the cabin support point, or It is a combination of both. Further, in the same configuration, the correction means based on the noise transfer function and the anti-aliasing filter are connected back and forth as one correction means, and are provided on the path of the input or output signal of the adaptive control means. .

[0005]

Next, an embodiment of the present invention will be described. FIG. 1 is an overall side view showing a tractor equipped with a cabin, and FIG. 2 shows a first embodiment of an active silencer for silencing in a cabin provided with means for correcting a transfer function 1 based on cabin vibration characteristics with respect to engine noise. FIG. 3 is a side view showing a second embodiment of an active silencer for silencing in a cabin provided with a correction means for a noise via a cabin support point by a transfer function 2 based on a cabin vibration characteristic. Is a block diagram showing a control circuit of the active silencer in the first and second embodiments, FIG. 5 is a diagram showing an example of noise transmission characteristics based on the transmission characteristics of the cabin 8,
FIG. 6 is a side view showing a third embodiment of an active silencer for muffling in a cabin provided with a plurality of correction means using transfer functions 1 and 2, and FIG. 7 is a plurality of transfer functions in the third and fourth embodiments. FIG. 8 is a block diagram showing a control circuit of an active silencer in a case where a plurality of correction means are provided. It is a control circuit diagram of the active silencer in a case.

First, the overall configuration of a tractor equipped with a cabin according to the present invention will be described with reference to FIG. A hood 4 is disposed at the front of the machine which suspends the front wheel 2 and the rear wheel 3 at the front and rear, and an engine 5 is built in the hood 4.
A steering handle 6 is provided behind the hood 4, and a seat 7 is provided behind the steering handle 6. A front window and a rear window (not shown) are provided on the front and rear surfaces of the cabin 8, and a door window 9 is formed on a side portion of the cabin 8, and a side window 10 is provided behind the door window 9. Is formed. Said windshield and rear glass,
The door window 9 and the side window 10 are supported by a metal frame 8a. The steps of the cabin 8 are made of sheet metal or the like. The steering handle 6 is provided above a dashboard 21 provided in the cabin 8, and the dashboard 21 is made of a member made of resin or the like. The dashboard 2
At the rear of the seat 1, there is provided a seat 7 for housing a cushion. On the side of the seat 7, a traveling speed change lever, an accelerator lever, a brake lever, and the like of the work vehicle are disposed.

A clutch housing 13 is connected to the rear of the engine 5, and a transmission case 14 is connected to the rear of the clutch housing 13.
To be driven. The driving force of the engine 5 is transmitted to a power take-off shaft 15 protruding from the rear end of the transmission case 14 to drive the power take-off shaft 15 and drive a work machine connected to a work machine mounting device 16 at the rear end of the machine body. It is configured to be.

Next, the configuration of the cabin 8 will be described. As shown in FIG.
A dashboard 21 made of a resin material is disposed at a front part of the inside, and a steering handle 6 is disposed at an upper part of the dashboard 21. Further, a clutch pedal 22 is provided below the dashboard 21. The clutch pedal 22 is connected to the above-described clutch housing 13 via a link mechanism, and is configured to be capable of controlling transmission of power from the engine 5 to the transmission case 14. A support point is provided on the floor portion of the cabin 8 and the like, and the cabin 8 is supported on a part of the body such as the clutch housing 13 and the transmission case 14 via the support point.

The active silencer of the present invention is a device for silencing noise in the cabin 8 mounted on the body (tractor) as described above. The overall configuration of this silencer will be described with reference to FIGS. As shown in FIG. 2, a reference sensor 31 serving as a noise detecting unit is provided.
Is disposed near the noise source of the body outside the cabin 8 (for example, near the engine in the hood) to detect noise. In the cabin 8, a monitor microphone 33 as a noise reduction effect detecting means is provided, and a speaker 34 as a noise control sound source is provided. Further, a controller 32 is provided on the body of the work vehicle or the like (may be inside the cabin 8), and the controller 32 includes the reference sensor 31, the monitor microphone 33, and the speaker 3.
4 are connected. The controller 32 outputs a control sound having an opposite phase to the sound wave of the noise from the speaker 34 based on the noise detected from the reference sensor 31, and a noise reduction effect by the control sound is output to the monitor microphone 3.
3 to enable detection.

The reference sensor 31 is a means for detecting information relating to vibration caused by noise. The reference sensor 31 may be a means for directly detecting vibration of a certain member, or may be a device for detecting fluctuations in air pressure caused by vibration of a noise source. What is detected (for example, a microphone) may be used.

The reference sensor 31 is connected to a controller 32 so that an electrical signal relating to noise detected by the reference sensor 31 can be input to the controller 32. On the other hand, a monitor microphone 33 serving as a muffling effect detecting means is provided on the roof 11 constituting the upper part of the cabin 8. Thus, the monitor microphone 33 detects noise near the operator, and can detect a muffling effect. The monitor microphone 3
Numeral 3 is connected to the controller 32, and outputs a detection value detected by the monitor microphone 33 to the controller 3.
2 can be input.

Behind the roof 11 of the cabin 8,
A muffling speaker 34, which is a control sound source, is provided, and a control sound for reducing the noise can be output from the speaker 34. Since the speaker 34 is disposed on the roof 11 as described above,
Accordingly, it is possible to prevent the sound wave output from the speaker 34 from wrapping around the rear of the speaker 34, improve the bass output characteristics of the speaker 34, and reduce the distortion of the output sound wave. The speaker 34 is connected to the controller 32, and detection values detected by the reference sensor 31 and the monitor microphone 33 are calculated in the controller 32, and a sound for reducing noise in the cabin 8 is output from the speaker 32. 34. A single speaker or a plurality of speakers 34 can be provided as necessary, and the speaker 34 is configured by combining a small-diameter speaker having a high-frequency output characteristic and a large-diameter speaker having a high-low-frequency characteristic. Things are also possible. This makes it possible to eliminate the distortion of the output by the speaker 34.

The active noise reduction device for attenuating noise in the cabin basically performs noise detection by the reference sensor 31 on the noise source outside the cabin 8 as described above. This is a structure in which a speaker 34 emits a control sound, which is an anti-phase sound, to attenuate the transmitted noise. However, the problem is that the speaker 3 generated based on the detection of the reference sensor 31 outside the cabin is problematic.
The control sound from No. 4 does not accurately correspond to the noise in the cabin, and the noise reduction effect is reduced. About this, FIG.
A more detailed description will be given. FIG. 5 is a diagram illustrating noise transmission characteristics of the cabin 8. As described above, the noise source of the noise in the cabin is mainly the engine noise outside the cabin, but its resonance (vibration) based on the material and shape of the cabin, the support structure, and the like.
Due to the characteristics, at the time of transmission in the cabin 8,
A constant frequency noise is amplified. Therefore, as shown in FIG. 5, the vibration propagating sound transmitted into the cabin 8 is not uniform over the entire frequency range, and is f1, f2, f3.
As shown by f4 and f5, a specific frequency exists in an amplified state. The high frequency of the transfer characteristic changes depending on the configuration and shape of the cabin or the members disposed in the cabin (that is, the transfer characteristic varies depending on the cabin). Therefore, the cabin 8
In the above, it is possible to improve the noise reduction effect by outputting a control sound corrected so as to attenuate the frequencies f1, f2, f3, f4, f5 or vibrations near the frequencies. In the present invention, a filter (band-pass filter) 36 corresponding to the vibration characteristics of each cabin 8 is used as such a correction means.

The filter 36 corrects the detection signal of the reference sensor 31 so as to correspond to the noise propagating in the cabin by a noise transfer function based on the vibration characteristic of the cabin 8 with respect to the noise outside the cabin. The noise that propagates in the cabin includes various elements, such as the dashboard 21 directly from the engine.
And the noise propagating through the cabin support point. Therefore, the transfer function of the filter 36 has to be set depending on what kind of noise is caused even in the same cabin 8.

FIG. 2 shows an embodiment in which a filter 36 having a transfer function 1 for engine noise is provided. The transfer function 1 for this engine noise is obtained by measuring in advance what kind of vibration (resonance) characteristics the cabin 8 has with respect to the engine noise (vibration), and the transfer function corresponding to this measured value is obtained. The filter 36 having the function 1 is provided. In the cabin noise, the ratio of the engine noise (vibration) transmitted through the dashboard 21 and the like occupies a high ratio. By providing a filter 36 corresponding to this, it is effective to enhance the noise reduction effect of the cabin noise. is there.

FIG. 3 shows an embodiment in which a filter 36 having a transfer function 2 for noise (vibration) propagating through the cabin support point is provided. Transfer function 2 for noise (vibration) through this cabin support point
Is determined by measuring in advance what vibration characteristics the cabin 8 has at the cabin support point, and a filter 36 having a transfer function 2 corresponding to the measured value is provided.
In this case, of the noise in the cabin, the noise that propagates into the cabin 8 via the cabin support point can be effectively attenuated by the control sound from the speaker 34 after being corrected by the filter 36. A plurality of cabin support points, such as three points and four points, are provided. The cabin vibration characteristics with respect to noise (vibration) through the respective support points are measured, and the propagation through the respective cabin support points is performed. It is also possible to generate a control sound corresponding to the noise.

Here, especially when the reference sensor 31 is provided near the engine, the cabin 8 serving as the basis of the transfer function 1 is utilized by using the reference sensor 31.
A method of measuring the vibration (resonance) characteristics with respect to the engine noise (vibration) will be described. When the engine is not started, sound waves for measurement are emitted from the speaker 34, and the reference sensor 31
The output sound wave from is detected. That is, the measurement sound wave generated by the speaker 34 in the cabin 8 is detected by the reference sensor 31 outside the cabin 8, and the sound wave detected by the reference sensor 31 is compared with the sound emitted from the speaker 34. Thus, the transmission characteristics of the cabin 8 with respect to the engine noise can be measured. If the reference sensor 31 detects noise passing through the cabin support point, the vibration (resonance) characteristic of the cabin 8 based on the transfer function 2 with respect to the noise (vibration) through the cabin support point can be measured. . The noise transfer function can be calculated from the vibration (resonance) characteristics of the cabin 8 thus measured. Then, the filter 36 having a characteristic corresponding to the calculated noise transfer function is selected as a means for correcting the detected noise.
Alternatively, it is also conceivable to make the filter 36 variable so as to adjust the characteristics according to the calculated noise transfer function.

As described above, the filter 36 serving as the correction means is used.
At the time of setting, the noise transmission characteristic of the cabin 8 can be measured by a muffling mechanism constituted by the reference sensor 31, the muffling speaker 34, the monitor microphone 33, and the controller 32 without using any special device, and provided near the engine. The reference sensor 31,
Cabin 8 provided with a muffling mechanism composed of a muffling speaker 34, a monitor microphone 33, and a controller 32
It is possible to perform noise control according to the transmission characteristics for the noise near the engine.

Next, the silencing mechanism in the first and second embodiments will be described with reference to a block diagram. 4, a noise N is detected by a reference sensor 31. The noise N itself is the cabin 8, the cabin support point,
Alternatively, through the dashboard 21 or the like, the vibration (resonance) characteristic causes the constant frequency sound to be amplified and changed to noise N ′ as described with reference to FIG. On the other hand, a detection signal (analog signal) related to the noise N detected by the reference sensor 31 is corrected via a filter 36 which is a correction unit configured according to a noise transfer function based on the vibration characteristics of the cabin 8. Therefore, the analog signal substantially corresponds to the noise N ′, and the controller 3
2 is input. The controller 32 forms a noise control sound, and the mute speaker 34 outputs a control sound S that is an anti-phase sound to the noise N ′ (the noise N corrected by the filter 36). As a result, the noise N ′ and the control sound S are synthesized, and the control sound S causes the noise N ′.
Is attenuated. Thereafter, the mute effect is detected by the monitor microphone 33, and the controller 32
In, the control sound S is corrected.

In the controller 32, the electric signal (analog signal) inputted from the reference sensor 31 and the monitor microphone 33 is converted into a digital signal, and various processes of calculation and correction are performed as a digital signal. The digital signal subjected to the processing is converted into an analog signal by the controller 32 and then output from the speaker 34 as a noise control sound.

In the controller 32, the digital signal based on the detection of the reference sensor 31 and the digital signal based on the feedback from the monitor microphone 33 are finally passed through the adaptive filter 32a,
In the A circuit 32b, the sound is converted into an anti-phase sound for noise attenuation and output to the speaker 34 as an analog signal. The characteristic of the adaptive filter 32a is variable, and the characteristic can be changed according to conditions such as the atmospheric pressure, temperature, and humidity inside and outside the cabin 8. If the humidity is high, the higher the frequency of the sound, the easier it is to be absorbed into the atmosphere,
The output characteristics of the muffling speaker 34 may change.
Further, the sound propagation speed changes depending on the temperature, and the propagation characteristic of the control sound output from the speaker 34 changes. Therefore, the control sound output from the sound deadening speaker 34 is adjusted by the adaptive filter 32a to improve the sound deadening effect. It is possible.

An analog feedback signal from the monitor microphone 33 is converted into a digital signal via an A / D circuit as a monitor information calculation circuit 32d in the controller 32.
It is taken in. The input information from the reference sensor 31 is also taken into the correction circuit 32c, and the correction information based on the propagation characteristics of the sound from the speaker 34 to the monitor microphone 33 is sent from the correction circuit 32c to the monitor information calculation circuit 32d. To the monitor information calculation circuit 32
The calculation is performed at d to update the filter coefficient.

Next, a third embodiment of the present invention in which filters corresponding to the transfer functions 1 and 2 are provided will be described with reference to FIG. In FIG. 6, the reference sensor 3
The reference numeral 1a is provided near the engine such as in the hood and the reference sensor 31b is disposed at the cabin support point to detect noise transmitted to the cabin 8. Also,
In the cabin 8, a monitor microphone 33 serving as a muffling effect detecting means is provided, and a speaker 3 serving as a noise control sound source is provided.
4 are provided.

As described above, in the third embodiment, the transfer function 1 corresponding to the engine noise and the transfer function 2 corresponding to the noise passing through the cabin support point correspond to the respective elements in the propagation noise in the cabin. Accordingly, the detection signals can be corrected by the reference sensors 31a and 31b in response to the propagation noise, and the noise reduction effect can be further improved.

Since the above configuration is employed, it is possible to detect noise through the cabin 8 near the engine and at the cabin support point. Therefore, by comparing the sound wave or vibration detected by the reference sensors 31a and 31b with the sound radiated from the speaker 34,
The vibration (resonance) characteristics of the sound wave of the cabin 8 can be measured. Further, it is possible to calculate a noise transfer function from the vibration (resonance) characteristics of the sound wave. That is, the reference sensors 31a and 31b for noise detection between the vicinity of the engine and the cabin support point,
4, the noise transmission characteristic of the cabin 8 can be measured by a noise reduction mechanism composed of the monitor microphone 33 and the controller 32. The reference sensors 31a and 31b, the noise reduction speaker 34, the monitor microphone 33, and the controller 3
Cabin 8 provided with a silencing mechanism constituted by 2
It is possible to perform noise control according to the transmission characteristics of the noise near the engine and the noise from the cabin support point.

The silencing mechanism in the third embodiment will be described with reference to a block diagram. In FIG. 7, a noise N1 near the engine is detected by a reference sensor 31a, and a noise N2 from a cabin support point is detected by a reference sensor 31b. The reference sensor 3
The noises detected by 1a and 31b are, respectively, a filter 36a that is a correction means as a noise transfer function based on the vibration characteristics of the cabin with respect to the noise near the engine,
The noise or vibration from the cabin support point is corrected via a filter 36b as a noise transfer function based on the vibration characteristic of the cabin based on the vibration characteristics of the cabin, and then input to the controller 32. In the controller 32,
A noise control sound, which is an anti-phase sound wave of the input sound wave signal, is formed, and the control sound S 1 is output from the muffling speaker 34.
On the other hand, the noises N1 and N2 are changed into noises N1 'and N2' in the cabin via the cabin 8, respectively, but are detected by the reference sensors 31a and 31b corrected by the filters 36a and 36b. The signals substantially correspond to the noises N1 'and N2', respectively. Therefore, the control sound S1 is a substantially accurate anti-phase sound with respect to the noises N1 ′ and N2 ′, and
2 and the control sound S1, the noise N1 · N
2 is attenuated. Thereafter, the mute effect is detected by the monitor microphone 33, and the controller 3
2, the control sound S1 is corrected.

As in the first to third embodiments, the reference sensor 31a and the reference sensor 31b
The control noise can be output by performing a correction in consideration of the transmission characteristics of the cabin 8 with respect to each of the noises detected by the above, and the noise reduction effect of the above-described noise reduction mechanism can be improved.

Next, a fourth embodiment of the present invention will be described. As shown in FIG. 8, in the noise reduction control mechanism, the reference sensor 31 (which may detect noise near the engine or may detect noise or vibration from the cabin support point) may be provided via a filter 36c. The controller 32 is connected to the controller 32 so that noise detected by the reference sensor 31 can be input to the controller 32. The filter 36c is configured by connecting a filter 56a, which is a means capable of correcting noise with a noise transfer function calculated based on the vibration (resonance) characteristics of the cabin 8, and an anti-aliasing filter (low-pass filter) 57a. I have. Therefore, the filter 36c
Accordingly, noise can be corrected using the noise transfer function.

The controller 32 includes a filter 36
It is connected to the muffling speaker 34 via d, and the control sound signal to the muffling speaker 34 can be corrected. The filter 36d is configured by connecting a filter 56b and an anti-aliasing filter 57b, which are means capable of correcting a control sound with a noise transfer function based on the vibration characteristics of the cabin 8, in a connected manner. Therefore, the filter 36d
Thus, the control sound can be corrected using the noise transfer function of the cabin 8.

In order to configure the silencing control mechanism as described above,
The number of filters constituting the silencing control mechanism can be reduced, and the silencing control mechanism can be made compact.
As a result, it is possible to improve the degree of freedom of a place where the noise reduction control mechanism is disposed, and it is possible to improve the degree of freedom in design. Further, it is possible to reduce the cost for configuring the silencing control mechanism.

[0031]

As described above, the present invention has the following advantages. That is, an active silencer for generating a control sound for attenuating a noise propagating in a cabin supported by an airframe and muffling the inside of the cabin, wherein the noise detection means and the control sound A control sound source to be generated and a detection signal of the noise detection unit are input, and the adaptive control unit that outputs a control signal related to a control sound to the control sound source and a noise reduction effect detection unit are provided. The noise transfer function is calculated by measurement, and one or a plurality of correction means for correcting the input or output signal of the adaptive control means with the noise transfer function are provided. It can be done accordingly. For this reason, the noise reduction effect can be improved even in various types of cabins having different configurations.

According to the first aspect of the present invention, the noise transfer function is based on a transfer characteristic of the cabin itself to the noise or vibration of the engine, so that the noise or vibration of the engine is reduced. Is propagated due to the cabin resonance and becomes noise in the cabin, the signal is corrected with a noise transfer function based on the cabin's transmission characteristics with respect to engine noise or vibration. It is possible to improve the noise reduction effect of the transmission noise in the cabin caused by the noise. Further, since the noise can be controlled by the engine noise and the noise transmission characteristics of the cabin, it is not necessary to consider the compatibility between the engine mounted on the body and the noise surface of the cabin, and the degree of freedom in design can be improved.

[0033] In the muffler according to the first aspect,
According to a third aspect of the present invention, the noise transfer function is based on a transmission characteristic of the cabin itself with respect to noise or vibration through the cabin support point, so that noise and vibration through the cabin support point are reduced. When the noise is propagated by resonance and becomes noise in the cabin, the signal is corrected by the noise transfer function based on the cabin transfer characteristic with respect to the noise or vibration at the cabin support point, resulting from the vibration at the cabin support point. It is possible to improve the noise reduction effect of the noise in the cabin. Further, since the noise in the cabin due to the cabin support point can be eliminated, the degree of freedom in the arrangement of the cabin support point can be improved.

[0034] Further, in the muffler according to the first aspect,
As described in claim 4, the noise transfer function is based on a transfer characteristic of the cabin itself to noise or vibration of the engine and a transfer function based on a transfer characteristic of the cabin itself to noise or vibration through the cabin support point. When the engine noise (vibration) and the noise (vibration) at the cabin support point propagate by resonance of the cabin and become noise in the cabin, the engine noise (vibration)
The signal is corrected by a noise transfer function based on the cabin transfer characteristic with respect to the noise (vibration) through the cabin support point, and the noise (vibration) of the engine and the noise (vibration) through the cabin support point are corrected. (Vibration) can be improved.

According to a first aspect of the present invention, in the noise suppressor according to the fifth aspect, the correction means based on the noise transfer function and the anti-aliasing filter are connected in front and rear to form one correction means, and the adaptive control means is provided. By providing the input or output signal path, the reproducibility of the control sound corresponding to the noise can be improved, and the number of correction means for performing the noise correction can be reduced. It is easy and can improve assemblability and durability. Also,
Manufacturing costs can be reduced.

[Brief description of the drawings]

FIG. 1 is an overall side view showing a tractor equipped with a cabin.

FIG. 2 is a side view showing a first embodiment of an active noise reduction device for noise reduction in a cabin provided with means for correcting a transfer function 1 based on cabin vibration characteristics with respect to engine noise.

FIG. 3 is a side view showing a second embodiment of an active noise reduction device for noise reduction in a cabin, provided with a correction means using a transfer function 2 based on cabin vibration characteristics with respect to noise via a cabin support point.

FIG. 4 is a block diagram showing a control circuit of the active silencer in the first and second embodiments.

FIG. 5 is a diagram showing an example of a noise transmission characteristic based on the transmission characteristic of the cabin 8;

FIG. 6 is a side view showing a third embodiment of an active noise reduction device for in-cabin noise reduction provided with a plurality of correction means based on transfer functions 1 and 2.

FIG. 7 is a block diagram showing a control circuit of an active silencer in a case where a plurality of correction means based on a plurality of transfer functions are provided in the third and fourth embodiments.

FIG. 8 is a control circuit diagram of an active silencer in the case where a filter that is a combination of a filter that is a transfer function correcting means based on a cabin vibration characteristic and an anti-aliasing filter is provided.

[Explanation of symbols]

 7 seat 8 cabin 11 cabin roof 21 dashboard 22 clutch pedal 31 reference sensor 32 controller 33 monitor microphone 34 speaker 36 filter 36a / 36b filter 56a / 56b filter 57a / 57b anti-aliasing filter

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shigeki Tada 1-32 Chayacho, Kita-ku, Osaka, Osaka Inside Yanmar Diesel Co., Ltd. (72) Eiji Koizumi 1-32 Chayacho, Kita-ku, Osaka, Osaka F-term in Yanmar Diesel Co., Ltd. (reference) 3D020 BA10 BA11 BB05 BB06 BB07 BC01 BD05 BE04 5D061 FF02 5H004 GB12 HA12 HA20 HB12 HB15 JB08 JB15 JB19 KC12 KC45 LA13 MA11 MA12

Claims (5)

[Claims] 1. An active silencer for generating a control sound for attenuating noise propagating in a cabin supported by an airframe and for silencing the inside of the cabin, comprising: a noise detecting means; and a control sound source for generating the control sound. And an adaptive control means for inputting a detection signal of the noise detection means and outputting a control signal relating to a control sound to the control sound source, and a noise reduction effect detection means,
A noise reduction device characterized by providing one or more correction means for measuring a transfer characteristic of the cabin itself to calculate a noise transfer function and correcting an input or output signal of the adaptive control means with the noise transfer function. . 2. The muffler according to claim 1, wherein the noise transfer function is based on a transfer characteristic of the cabin itself to noise or vibration of the engine. 3. The silencer according to claim 1, wherein the noise transfer function is based on a transfer characteristic of the cabin itself to noise or vibration via a cabin support point. 4. The noise reduction device according to claim 1, wherein the noise transfer function is based on a transfer characteristic of the cabin itself with respect to engine noise or vibration and a noise transfer function of the cabin itself with respect to noise or vibration via a cabin support point. A silencer characterized by being combined with one based on transfer characteristics. 5. The noise reduction apparatus according to claim 1, wherein the correction means based on the noise transfer function and the anti-aliasing filter are connected back and forth as one correction means, and an input or output signal of the adaptive control means is provided. A muffler characterized by being interposed in a path of a vehicle.