JPH0777993A - Noise controller - Google Patents

Abstract

PURPOSE:To prevent the entering of a foreign matter into a device and to prevent the occurrence of the corrosion, etc., by providing a cut-off means cutting off the inside from the outside of a duct on the opening part and on the way of the inside of the duct and open/close controlling the cut-off means. CONSTITUTION:A cap 5 turning by a motor 6 is mounted on the opening part of the duct 2. The motor 6 controlling the opening degree of the cap 5 is controlled according to the on/off of an engine key 11. By a motor driving means 10, when the engine key 11 is turned on, a forward voltage is applied to the motor 6 for a prescribed time, and the motor 6 is rotated in the direction of opening the cap 5. When the engine key 11 is turned off, the motor 6 is rotated in the direction of closing the cap 5 by the motor driving means 10. Then, when the engine is driven, the opening part of the duct part 2 becomes full open, and when the engine is stopped, the opening part of the duct 2 becomes full close by the cap 5. That is, by closing the opening part of the duct 2 in nonuse, the devide is protected from corrosion, and muffler performance is maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects noise from a noise source and creates a signal having a phase substantially opposite to that of the noise and equal sound pressure.
The present invention relates to a noise control device that reduces noise by outputting the signal as a sound wave using an electric signal / sound wave converter such as a speaker.

[0002]

2. Description of the Related Art Conventionally, a passive muffler such as a muffler has been used for noise generated from an internal combustion engine or the like, but improvements have been desired from the viewpoints of exhaust efficiency, size, muffling characteristics and the like. On the other hand, conventionally, the speaker outputs the noise generated from the noise generation source and the compensation sound of approximately the opposite phase and equal sound pressure,
An active noise control device that cancels noise has been proposed.

In recent years, a signal processing technique using a digital circuit has been developed, and the frequency range that can be handled has been expanded as a result of a dramatic improvement in the signal processing speed.
Many practical noise control devices have been proposed. FIG. 7 shows an example of the configuration of the noise control device which is the premise of the present invention, which has been already proposed by the present applicant in Japanese Patent Application No. 3-195449.

The noise control device outputs a speaker 3 for eliminating the noise transmitted from the engine of the automobile, which is the noise source 100, through the exhaust pipe near the muffling point P (in the figure), and the output to the speaker 3. An amplifier 201 for amplification and a D / A converter (Digital To Analo) for converting a digital signal into an analog signal in order to supply the analog signal to the amplifier 201.
g Converter) 202.

A microphone 101 installed in a lower part of a rear bumper or the like for converting a residual sound of the noise generated by canceling the noise emitted from the noise generating source 100 with the sound wave from the speaker 3 into an electric signal, and the microphone 101 of the microphone 101. An amplifier 301 for amplifying an electric signal and an A / A for converting an analog signal of the amplifier 301 into a digital signal
A D converter (Analog To Digital Converter) 302.

Based on this digital signal, adaptive filtering means 103 for controlling a filter coefficient to form a compensating signal for canceling noise to the speaker 3, and ignition timing from the engine of the automobile which is the noise generating source, A timing signal from the rotation timing (rotation speed) is input, and a noise signal from the microphone 102 or the like, or
Input the noise reproduction signal from the difference signal calculation means 105,
The noise cycle is detected and the cycle change is predicted.

The period detection control means 104 for controlling the adaptive filtering means 103 according to this cycle prediction change so as to follow a steep change, and the noise source 10
A microphone 102 installed near 0, an amplifier 601 for amplifying the output of the microphone 102, an A / D converter 602 for converting an analog output signal of the amplifier 601 into a digital signal, and the adaptive filtering means 103. The difference signal calculating means 10 is connected to the output, and from the output point via the speaker 3 and the microphone 101.
Transfer characteristic simulation means 1 for simulating the transfer characteristic up to the input of 5
06, the output of the transfer characteristic simulating means 106 and the A / D
It includes a difference signal calculation means 105 for calculating a difference signal with the output of the converter 302, and a switch means 107 for selectively selecting the input means of the adaptive filtering means 103. Here, the adaptive filtering means 103, the cycle detection control means 104, etc. are a DSP (Digital Signal Processor).
It is composed of.

With this configuration, when the engine speed fluctuates significantly during acceleration / deceleration, etc., in response to a shift signal from a transmission (not shown) and an accelerator / brake signal linked with accelerator pedals and brake pedals (not shown). , A noise signal from the microphone 102 is selected as an input signal of the adaptive filtering means 103, and when there is almost no change in the engine speed during constant speed traveling, the noise reproduction signal from the difference signal calculating means 105 is adaptive filtering means. The switching means 107 is controlled so as to be selected as the input signal of 103.

Then, the adaptive filtering means 103
A compensating signal having a substantially equal sound pressure is generated in a phase substantially opposite to that of the noise from the noise generating source, is reproduced as a sound wave by the speaker 3, and the noise is erased at the sound deadening point P. Further, by inputting the residual sound of noise and sequentially controlling the filter coefficient of the adaptive filtering means 103 according to the residual sound, the residual sound can be further reduced, that is, the noise can be more completely eliminated. A compensation signal is created and output as a sound wave from the speaker 3.

Next, FIG. 8 shows the structure near the outlet of the exhaust pipe in such a noise control device. As shown in FIG. 8, a duct 2 incorporating a speaker 3 in the noise control device of FIG. 7 described above is provided in parallel near the outlet of an exhaust pipe 1 of an automobile. As in the configuration of the exhaust pipe 1, a catalytic converter and a sub-muffler are provided in the middle of the exhaust pipe as in the conventional case, but the main muffler is eliminated, and the sub-muffler eliminates noise in the high-pitched part of noise that is difficult to follow. The noise control device mainly mutes the low-pitched portion of noise that is easy to follow. By eliminating this main muffler, the back pressure is lowered and the exhaust efficiency is improved, which is also effective in terms of the power performance of the vehicle.

Further, by using the exhaust pipe 1 and the duct 2 of the noise control device as separate systems, the exhaust gas does not damage the speaker or the like of the noise control device, and the exhaust control does not cause exhaust interference. There was an advantage.

[0012]

However, in the conventional noise control device, as shown in FIG. 8, the duct end for transmitting the compensation sound of the noise control device is open, so that the speaker or the like is always exposed directly to the outside air. In addition, the foreign matter entering the noise control device causes the noise control device to deteriorate in durability and muffling performance. In particular, if a noise control device is installed to control the exhaust noise of a car, dust, raindrops, insects, etc. may enter the device when parking, or water may enter during a car wash, resulting in speaker damage or corrosion in the duct. There was a problem in durability due to deterioration caused by the above. Further, even if a durable speaker or duct is used, foreign matter may adhere to the surface of the speaker or be accumulated in the duct, and the silencing ability may be deteriorated.

It is an object of the present invention to protect a noise control device and improve its durability.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention creates a compensating signal having a phase substantially opposite to the noise from a noise source and equal sound pressure, and incorporates an electric signal / sound wave converter. In a noise control device that reduces the noise by outputting a compensation sound that reproduces the compensation signal from an opening of a duct arranged near the noise generation source, in the opening of the duct and inside the duct. At least one of them is provided with a blocking means for blocking the inside and outside of the duct, and the opening / closing of the blocking means is controlled.

Further, the noise generated from the noise source has a phase substantially opposite to that of the noise.
By creating a compensation signal of equal sound pressure and outputting a compensation sound that reproduces the compensation signal from the opening of the duct which is built in the electric signal / sound wave converter and is arranged near the noise source, In a noise control device for reducing, a resonance box having at least one end provided so as to cover both the opening of the duct and the outlet of the noise,
It is characterized in that the opening of the resonance box is provided with a blocking means for blocking the inside and the outside of the resonance box, and the opening and closing of the blocking means is controlled.

[0016]

A duct is arranged near the exit of the noise from the noise source as a transmission path of the compensating sound having substantially the opposite phase and equal sound pressure to the noise, and the duct is provided in at least one of the opening and the inside of the duct. By providing a shut-off device that shuts off the inside and outside of the equipment, and by controlling the opening / closing of the shut-off means, foreign matter such as water is prevented from entering the noise control device, and it is protected from corrosion etc. and maintains the same noise control performance. can do. In particular, it is possible to improve the durability of the noise control device in a vehicle used outdoors or in a factory where dust is generated.

Next, when a resonance box having at least one open end is provided so as to cover both the open portion of the duct through which the compensation sound is output and the noise outlet, the noise and the compensation sound are not diverged in the resonance box. Is resonated with. The opening of the resonance box is provided with a blocking means for blocking the inside and the outside of the resonance box, and by controlling the opening / closing of the blocking box, the noise control device and the noise generation source are blocked from the outside, and together with the noise control device. The noise source can be protected from corrosion and the like caused by the intrusion of foreign matter.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a noise control device according to an embodiment of the present invention, and FIG. 2 is a perspective view thereof, showing an example adapted to silencing exhaust noise of an automobile. As shown in the figure, the exhaust pipe 1 of the automobile and the duct 2 of the noise control device are separate parallel systems, and the duct 2 is installed near the outlet of the exhaust pipe 1 of the automobile. Then, for example, the speaker 3 outputs a compensating sound for noise control, which has an approximately opposite phase and equal sound pressure to the noise created by the configuration of the noise control device of FIG. 7. The noise control noise is transmitted through the duct 2 and is emitted from the opening. As a result, the noise from the outlet of the exhaust pipe 1 and the compensating sound resonate and cancel each other, thereby performing noise control.

The noise control device in this embodiment is provided with a lid 5 which is rotated by a motor 6 at the opening of the duct 2 of the noise control device. The control of the motor 6 that controls the opening degree of the lid 5 is performed according to the on / off state of the engine key 11 connected to the battery power source + B. When the engine key 11 is turned on, the motor driving means 10 applies a voltage in the positive direction to the motor 6 for a predetermined time to rotate the motor 6 in the direction in which the lid 5 opens. When the engine key 11 is turned off, the motor driving means 10 applies a negative voltage to the motor 6 for a predetermined time to rotate the motor 6 in the direction in which the lid 5 closes. As a result, when the engine is driven, the opening of the duct 2 is fully opened, and when the engine is stopped, the opening of the duct 2 is fully closed by the lid 5 (dotted line in FIG. 1). ).

By closing the opening of the duct 2 when the noise control device is not used, it is possible to prevent dust, water, insects, etc. from entering the noise control device through the duct 2 when parking or washing a car. Silencing performance can be maintained by protecting the control device from corrosion and damage. Incidentally, the lid 5 or the duct 2
It is desirable that the opening has a waterproof structure including a rubber packing or the like.

Further, as shown in FIG. 3, a rotating plate-shaped opening / closing plate 7 is installed in the middle of the duct 2 in the noise control device, or the opening of the duct 2 or the duct 2 as shown in FIG.
Similarly, the noise control device is protected by installing a plurality of divided opening / closing plates 8 which are connected by gears or the like in the middle. Also in this case, similarly to the above, the rotation of the motor 6 is controlled by the motor driving means 10 in accordance with the ON / OFF of the engine key 11, and the opening / closing plates 7 and 8 are opened / closed. When the engine key 11 is turned on, the open / close plate 7 and the open / close plate 8 are held horizontally with respect to the axial direction of the duct 2.
When 1 is off, the open / close plate 7 and the open / close plate 8 are held in a direction perpendicular to the axial direction of the duct 2.

A lid 5 for blocking the opening of the duct 2
FIG. 5 shows an embodiment in which is used as a reflection plate for compensation sound. When the noise suppression effect is enhanced by reflecting the compensation sound of the noise control device with the lid 5, the opening degree of the lid 5 when the noise control device is used is regulated to a predetermined angle, and the motor 6 is operated in the same manner as described above. To control the opening and closing of the lid 5. The angle of the lid 5 at this time may be set by experimentally obtaining a reflection angle at which the detected residual noise is minimized.

Next, FIG. 6 shows a sectional view of a noise control device provided with a resonance box which is partially opened so as to cover the opening of the duct 2 and the outlet of the exhaust pipe 1 of the noise control device. The noise control device is installed by bringing the outlet of the exhaust pipe 1 and the opening of the duct 2 of the noise control device close to each other, so that both the outlet of the exhaust pipe 1 and the opening of the duct 2 of the noise control device are covered. A muffler cutter 9 is provided as an open resonance box. This muffler cutter 9 can prevent the noise and the compensation sound of the noise control from diverging and resonate.

Then, similarly to the case where the shutoff lid is installed at the open portion of the duct 2 of the noise control device, the rotatable lid 5 for shutting off from the outside is provided at the open portion of the muffler cutter 9. As a result, foreign matter can be prevented from entering and the exhaust pipe 1 can be protected together with the noise control device, as described above. still,
Even when the ducts of the plurality of noise control devices are installed around the noise outlet, the blocking means may be provided in each duct.

[0025]

The present invention makes it possible to protect a noise control device and improve its durability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a noise control device of the present invention.

FIG. 2 is a perspective view showing an embodiment of a noise control device of the present invention.

FIG. 3 is a sectional view showing a second embodiment of the noise control device of the invention.

FIG. 4 is a sectional view showing a third embodiment of the noise control device of the invention.

FIG. 5 is a sectional view showing a fourth embodiment of the noise control device of the invention.

FIG. 6 is a sectional view showing a fifth embodiment of the noise control device of the invention.

FIG. 7 is a diagram showing a configuration of a noise control device.

FIG. 8 is a cross-sectional view showing a configuration near an outlet of an exhaust pipe of a conventional noise control device.

[Explanation of symbols]

 1 ... Exhaust pipe 2 ... Duct 3 ... Speaker 4 ... Speaker box 5 ... Blocking lid 6 ... Motor 7,8 ... Open / close plate 9 ... Muffler cutter 10 ... Motor drive means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Ishikawa 1-2-2 Gosho-dori, Hyogo-ku, Kobe-shi, Hyogo Prefecture Fujitsu Ten Limited (72) Inventor Shinichi Iwamoto 1-chome, Gosho-dori, Hyogo-ku, Hyogo Prefecture No. 2 to 28 in Fujitsu Ten Limited

Claims (2)

[Claims] 1. A compensating signal having a phase substantially opposite to that of a noise from a noise source and an equal sound pressure is created, and an electric signal / sonic wave converter is built-in from an opening of a duct arranged near the noise source. In a noise control device for reducing the noise by outputting a compensation sound that reproduces a compensation signal, at least one of the opening of the duct and the inside of the duct shuts off the inside and the outside of the duct. A noise control device comprising means for controlling the opening and closing of the blocking means. 2. A compensating signal having substantially the opposite phase and equal sound pressure from the noise from the noise source is created, and an electric signal / sound wave converter is built-in from the opening of the duct arranged near the noise source. In a noise control device that reduces the noise by outputting a compensation sound that reproduces a compensation signal, a resonance having at least one end provided so as to cover both the opening of the duct and the outlet of the noise. A noise control device, comprising: a box; and a shutoff means for shutting off the inside and the outside of the resonance box at the opening of the resonance box, and the opening / closing control of the shutoff means.