JPH07168581A - Actuator of noise control device - Google Patents

Abstract

PURPOSE:To improve an actuator of a noise control device constituted with loudspeakers outputting a cancel sound. CONSTITUTION:In an actuator of a noise control device which has a loudspeaker unit 2 canceling a noise included in exhaust gas near a tail pipe 1 releasing exhaust gas of an engine, a relaxation section 4 which forms a space in front of the loudspeaker in order to relax a peak and a dip of a reproduction frequency characteristic and produce efficiently a cancel sound is provided, the relaxation section 4 turns reflection of a cancel sound of the loudspeaker unit 2 toward an exit along an axis of the tail pipe 1 and performs optimization of reducing capacity. The relaxation section 4 is made double structure for the tail pipe 1, the outside of it is extended and throttled at an exit, and a clearance in which air is made to flow between the tail pipe is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise control device for canceling noise, and particularly to the present invention relates to an actuator composed of a speaker for outputting a cancel sound.

[0002]

2. Description of the Related Art Conventionally, as a technique in such a field, there is a noise control device described below. This noise control device is installed in a vehicle, for example, and is intended to control noise generated by the engine of the vehicle. A noise control device is generally used for forming a cancel sound to a controller by detecting a speaker that outputs a cancel sound having a phase opposite to that of the noise and equal sound pressure, a controller that forms a cancel signal, and a residual sound that cancels the noise. It consists of a feedback microphone. An actuator composed of the speaker is attached near a tail pipe through which exhaust gas is discharged into the atmosphere through an exhaust pipe of a vehicle. Further, in order to alleviate the peak and dip of the reproduction frequency characteristic and radiate the canceling sound efficiently, the alleviation part which forms a space in front of the speaker is provided.

[0003]

In the structure of the actuator of the above noise control device, environmental resistance and workability are important issues. In particular, in the structure around the actuator and the exhaust pipe, in the relaxation section, a complicated reflection of the sound wave from the speaker occurs, and the interference of these reflected sounds causes peaks and dips in the frequency characteristics of the output sound pressure. There's a problem. Furthermore, the tail pipe becomes hot because the exhaust gas of the engine passes through,
If this is transmitted to the speaker, there is a structural problem of the actuator in that the speaker is thermally damaged and the cancellation sound is hindered.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an actuator of a noise control device which can improve frequency characteristics and prevent thermal damage in view of the above problems.

[0005]

In order to solve the above problems, the present invention provides a noise control device having a speaker unit for canceling noise contained in exhaust gas in the vicinity of a tail pipe for discharging exhaust gas of an engine. The actuator is provided with a relaxation portion that forms a space in front of the speaker to relax the peak and dip of the reproduction frequency characteristic by having a smoothly changing shape and radiate the cancel sound efficiently, and the space of the relaxation portion. Has an inclination that causes reflection of the cancel sound of the speaker unit to be directed toward the outlet along the axis of the tail pipe.

The relaxation portion has a double structure with respect to the tail pipe, and the outside is stretched and squeezed at the outlet. The relaxing portion is provided with a clearance through which air flows between itself and the tail pipe. The relaxing portion is
Connect the outlet to the punching pipe of the tail pipe,
A hole for taking in air from the outside is provided in this joint.

The easing portion is a canceling sound guiding portion for guiding the canceling sound to the tail pipe by winding and branching the glass wool provided on the outside of the punching pipe of the tail pipe at the outlet neck portion, which is more than the outlet neck portion. The other end having a large diameter is mounted with a certain clearance. The relaxing portion includes a cancel sound guiding portion that connects the outlet neck portion and the tail pipe to guide the cancel sound to the tail pipe, and a hole is provided in the middle of the cancel sound guiding portion.

The relaxing portion is a canceling sound guiding portion for branching the tail pipe to guide a canceling sound to the tail pipe, and the relaxing portion is fixed to the other end portion having a diameter larger than that of the exit neck portion. It is fitted with clearance.

[0009]

According to the actuator of the noise control device of the present invention, by having a shape that changes smoothly, a space is provided in front of the speaker in order to mitigate the peak and dip of the reproduction frequency characteristic and efficiently emit the cancel sound. A relaxation portion to be formed is provided, and the space of the relaxation portion has an inclination that causes reflection of the cancel sound of the speaker unit to be directed toward the outlet along the axis of the tail pipe, thereby reducing complex reflection and interference. it can. In addition, by forming this slope to optimize the volume reduction by adjusting the relaxation function, the reflection of the cancellation sound to the outlet can be further reduced, the interference due to complicated reflection is reduced, and the frequency characteristic of the output sound pressure peaks. , There is no dip and it is flattened. Since the relaxing portion has a double structure with respect to the tail pipe, the influence of radiant heat from the tail pipe on the speaker unit is eliminated, and the outside is stretched and throttled at the outlet, so that the exhaust sound and the cancel sound are interfered with each other. Is easily done. By providing a clearance through which air flows between the relaxing portion and the tail pipe, heat damage to the speaker unit is eliminated. The cancellation sound from the relaxation section is guided into the tail pipe to cancel the exhaust sound. In this case, the negative pressure generated by the discharge of the exhaust gas is used to cancel the atmospheric air. The air sucked into the guide portion cools the heat from the tail pipe and keeps the pressure on the front surface of the speaker unit at atmospheric pressure to ensure stable reproduction.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a diagram showing an actuator structure of a noise control device according to a first embodiment of the present invention, and FIG.
3 is a side sectional view of the actuator of FIG. As shown in FIG. 1, the end portion of the engine exhaust gas is discharged to the atmosphere, and the glass wool 1b is internally provided to suppress heat release to the outside.
The actuator of the noise control device provided on the tail pipe 1 having a front end is an axis of the tail pipe 1 in order to output a canceling sound with respect to the noise (exhaust sound) emitted from the tail pipe outlet 1a together with the exhaust gas. Speaker unit 2 disposed toward the speaker unit, a speaker box 3 surrounding the rear of the speaker unit 2, a diaphragm of the speaker unit 2 and a speaker for easing the difference in hardness of the atmosphere and radiating a cancel sound efficiently. 3 and a relaxing portion 4 forming a space. The relaxing portion 4 has a heat shield pipe 4a provided outside the tail pipe 1 with a clearance so that the radiant heat from the tail pipe 1 does not affect the speaker unit 3, and an outer pipe provided outside the heat shield pipe 4a. 4b, a narrowed portion 4c that extends the outer pipe 4b and narrows the outlet of the relaxing portion 4 in the direction of the outlet of the tail pipe 1, and a canceling sound from the speaker unit 2 that is the rear portion of the relaxing portion 4 and reflects the reflected sound. A slanting cut portion 4e directed toward the exit direction of the easing portion 4, and the slanting cut portion 4e are provided to correspond to the clearance between the tail pipe 1 and the heat shield pipe 4a and to form an air flow in this clearance. A hole 4e, and a connecting portion 4f for connecting the relaxing portion 4 and the speaker box 3 to each other. The capacitance of the shaded portion of the alleviating portion 4 is necessary to alleviate the difference in hardness between the diaphragm of the speaker unit 2 and the atmosphere and efficiently emit the cancel sound. Illustrated narrowing length L
1, the clearance L2 and the joint outlet length L3 can be adjusted to various conditions.

Conventionally, since the rear part of the relaxation section 4 is a space as shown by a dotted line, the cancel sound from the speaker unit 2 is reflected in the space and these interfere with each other to cause peaks and dips in the frequency characteristics of the output sound pressure. However, since the canceling sound is reflected by the slanting cut portion 4e according to the present embodiment and travels toward the exit of the relaxing portion 4, unnecessary interference is reduced and the frequency characteristic of the canceling sound is flattened. Further, the volume is reduced by adjusting with the relaxation function, and the volume becomes smaller than the conventional one, so that complicated reflection and interference can be reduced.

Further, not only is the clearance between the tail pipe 1 and the heat shield pipe 4a hindering the transmission of radiant heat, but also air is introduced from the traveling direction of the vehicle by the hole 4e provided in the oblique cut portion 4e, and the heat shield pipe is The inside of 4a is cooled to prevent the radiant heat from the tail pipe 1 from being transmitted to the speaker unit 2. As shown in FIG. 2, the speaker box 3 has a circular shape with the top and bottom cut. This is because the upper part considers other structures of the vehicle and the lower part prevents contact with the ground. Corresponding to this, speaker box 3
Has an elliptical shape. The opening of the outlet of the tail pipe 1 has an inclination of θ with respect to the ground as shown in the figure to prevent rainwater from directly entering. Prevents direct entry of rainwater into the area.

FIG. 3 is a diagram showing an actuator structure of a noise control device according to a second embodiment of the present invention. As shown in this figure, what is different from FIG. 2 is a relaxation part 4, and a certain range from the outlet part 1 a of the tail pipe 1 is punched.
Then, the punching pipe 1c is connected to the outlet of the relaxation section 4 and the cancel sound is sent into the tail pipe 1 to cancel the noise. A hole portion 4g into which air from the traveling direction flows is provided in this joint portion. At this time, in the punching pipe 1c, the exhaust gas is released into the atmosphere at a high speed, so that the relaxation portion 4 has a negative pressure.
Atmospheric air is sucked in through the space between a and the tail pipe 1, and the air is punched through the hole 4g to the punching pipe 1c.
Through the punching pipe 1c. By doing so, the heat from the punching pipe 1c is cooled to the speaker unit 2 and is not transferred to the speaker unit 2. When air is sucked in, the pressure of the relaxation portion (4) becomes atmospheric pressure, and the diaphragm of the speaker unit vibrates stably.

FIG. 4 is a diagram showing an actuator structure of a noise control device according to a third embodiment of the present invention. The front of the speaker unit 2 is directed rearward in parallel with the axis to the tail pipe 1, the speaker box 3 surrounds the rear of the speaker unit 2, and the relaxing portion 4 is formed by enlarging the space in front of the speaker unit 2. Glass wool 1a that passes the cancel sound but blocks heat is wound outside the punching pipe 1c of the tail pipe 1. The glass wool 1a is accommodated in the end portion 5a of the cancel sound guide portion 5 and is coupled to the punching pipe 1c to provide the cancel sound guide portion 5 for guiding the cancel sound. The other end 5b of the cancel sound guide portion 5 receives the cancel sound and receives the cancel sound.
The outlet is made thinner and is fitted over the outside with a certain clearance from the outlet neck. In this way, the air sucked from the gap between the ends 5b due to the negative pressure formed by the exhaust gas passing through the punching pipe 1c flows into the tail pipe 1 through the glass wool 1d and the punching pipe 1c and cools the joint portion. To do. Therefore, it is possible to prevent the heat transfer from the joint portion to the speaker unit 2 in combination with the glass wool. Further, since the canceling sound guiding portion 5 and the relaxing portion 4 are not in direct contact with each other, there is an effect of interrupting heat transfer.

FIG. 5 is a diagram showing an actuator structure of a noise control system according to the fourth embodiment. As shown in the figure, the front surface of the speaker unit 2 is arranged in parallel with the axis of the tail pipe (or exhaust pipe) 1. Speaker box 3
Surrounds the rear surface of the speaker unit 2 as described above. The mitigation section 4 on the front surface of the speaker unit 2 is a tube that branches the cancel sound before the exit of the tail pipe 1, and a cancel sound guide section 5 that guides the cancel sound to the tail pipe 1 is provided. The speaker unit 2 and the relaxation unit 4 are separated from the tail pipe 1 by a certain distance, and there is no direct heat transfer from the tail pipe 1. Then, the cancel sound guide portion 5 is provided with an atmosphere introduction opening 5c for taking in air and flowing it to the outlet of the tail pipe 1. Air is introduced from the outside due to the negative pressure of the exhaust gas flowing through the punching pipe 1c at the air introduction opening 5a. The cancellation sound from the speaker unit 2 is canceled by being superimposed on the noise at the joint portion of the tail pipe 1 and the cancellation sound guide portion 5. The flow of air from the air introduction opening 5a cools the coupling portion of the cancel sound guide portion 5 and cuts off heat transfer to the speaker unit 2.

FIG. 6 is a diagram showing an actuator structure of a noise control system according to the fifth embodiment of the present invention. In this figure, what is different from FIG. 5 is a cancellation sound guide portion 5, and one end 5a thereof is connected to the punching pipe 1c and emits a cancellation sound for canceling the noise contained in the exhaust gas. The other end portion 5b of the cancel sound guide portion 5 has a diameter larger than that of the outlet neck portion of the relaxing portion 4 so as to receive the cancel sound, and is fitted over the outside of the outlet neck portion to secure a certain gap therebetween. To be done. In this way
The air sucked from the gap of the end portion 5b by the negative pressure formed by the exhaust gas passing through the punching pipe 1c flows into the tail pipe 1 through the glass wool 1d and the punching pipe 1c, and cools the joint portion. Therefore, it is possible to prevent the heat transfer from the joint portion to the speaker unit 2 in combination with the glass wool. Further, since the canceling sound guiding portion 5 and the relaxing portion 4 are not in direct contact with each other, there is an effect of interrupting heat transfer.

[0017]

As described above, according to the present invention, by having the shape that changes smoothly, the peak and dip of the reproduction frequency characteristic are alleviated and the space in front of the speaker is emitted in order to efficiently emit the cancel sound. The relaxation part directs the reflection of the cancellation sound of the speaker unit toward the outlet along the axis of the tail pipe, and further reduces the volume, so that the cancellation sound interferes with the reflection up to the outlet. Decreases and the frequency characteristic of the output sound pressure peaks and dips and disappears. Since the relaxing portion has a double structure with respect to the tail pipe, the influence of radiant heat from the tail pipe on the speaker unit is eliminated, and the outside is stretched and throttled at the outlet, so that the exhaust sound and the cancel sound are interfered with each other. Is easily done. By providing a clearance through which air flows between the relaxing portion and the tail pipe, heat damage to the speaker unit is eliminated.

[Brief description of drawings]

FIG. 1 is a diagram showing an actuator structure of a noise control device according to a first embodiment of the present invention.

FIG. 2 is a side sectional view of the actuator of FIG.

FIG. 3 is a diagram showing an actuator structure of a noise control device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing an actuator structure of a noise control device according to a third embodiment of the present invention.

FIG. 5 is a diagram showing an actuator structure of a noise control device according to a fourth embodiment of the present invention.

FIG. 6 is a diagram showing an actuator structure of a noise control device according to a fifth embodiment of the present invention.

[Explanation of symbols]

 1 ... Tail pipe 2 ... Speaker unit 3 ... Speaker box 4 ... Relaxation section 5 ... Cancel sound guide section

Front page continued (72) Inventor Kazuya Sako 1-2-2 Goshodori, Hyogo-ku, Kobe-shi, Hyogo Prefecture Fujitsu Ten Limited (72) Inventor Osamu Ishikawa 1-2-2 Goshodori, Hyogo-ku, Kobe No. 28 in Fujitsu Ten Limited (72) Inventor Hiroshi Kitazaki 1 Ochaya, Hashime-cho, Okazaki-shi, Aichi Futaba Sangyo Co., Ltd. (72) Kunio Komori 1 Ochaya, Hashime-cho, Aichi-ken, Aichi Within Ba Sangyo Co., Ltd.

Claims (7)

[Claims] 1. An actuator of a noise control device having a speaker unit (2) for canceling noise contained in exhaust gas in the vicinity of a tail pipe (1) for discharging engine exhaust gas, the peak of reproduction frequency characteristics. , A relaxation section (4) forming a space in front of the speaker for relaxing the dip and efficiently radiating the cancellation sound, and the space of the relaxation section (4) reflects the cancellation sound of the speaker unit (2). An actuator for a noise control device, characterized in that it has an inclination that causes reflections to direct sound along the axis of the tail pipe (1) towards the outlet. 2. The tail pipe (1) includes the relaxing portion (4).
The actuator of the noise control device according to claim 1, wherein the actuator has a double structure, and the outside is stretched and squeezed at the outlet. 3. The actuator of the noise control device according to claim 1, wherein the easing portion (4) is provided with a clearance through which air flows between the easing portion (4) and the tail pipe (1). 4. The relaxing portion (4) has an outlet connected to a punching pipe (1c) of the tail pipe (1), and the connecting portion is provided with a hole (4g) for taking in air from the outside. The actuator of the noise control device according to claim 1. 5. The relief portion (4) comprises the outlet neck portion,
A cancel sound guide portion (5) for guiding the cancel sound to the tail pipe (1) by winding and branching the glass wool provided outside the punching pipe (1c) of the tail pipe (1) and is larger than the exit neck portion. The actuator of the noise control device according to claim 1, wherein the actuator is mounted on the other end having a diameter with a constant clearance. 6. The canceling sound guiding part (5) is provided with the canceling sound guiding part (5) for guiding the canceling sound to the tail pipe (1) by connecting the outlet neck part and the tail pipe (1). The actuator of the noise control device according to claim 1, wherein a hole (5c) is provided in the middle of 5). 7. The relaxation portion (4) comprises the outlet neck portion,
A cancel sound guide portion (5) for branching the tail pipe (1) to guide the cancel sound to the tail pipe (1), and is attached to the other end portion having a diameter larger than the outlet neck portion with a certain clearance. The actuator of the noise control device according to claim 1, wherein: