JP2001140627A - Exhaust silencer for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust silencer for an automobile which can ensure silence by preventing deterioration of an exhaust noise level not only when engine rotating speed is in a high rotating range but also when it is in a low rotating range. SOLUTION: A chamber 16 is disposed to a bypass pipe 14 for delivering exhaust led into a muffler main body 12 to the atmosphere in short-circuit, a control valve 18 for controlling a leading quantity of exhaust toward the chamber 16 is disposed. When the control valve 18 is closed, the chamber 16 is functioned as a resonance chamber, and it is functioned as an expansion chamber when the control valve 18 is opened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle exhaust silencer, and more particularly to a silencer having a chamber provided in a bypass pipe.

[0002]

2. Description of the Related Art FIG. 17 shows a conventional vehicle exhaust muffler (muffler) having a bypass pipe outside a muffler body.
FIG. As shown in FIG. 1, this type of muffler has a muffler main body 100 and a bypass pipe 102, and the bypass pipe 102 is provided with a control valve 104 of an electric control type. Control valve 10
Numeral 4 is opened and closed by driving the wire 108 by the actuator 106 to control the amount of exhaust gas introduced into the bypass pipe 102.

The opening and closing of the control valve 104 is controlled by the engine EC.
The control is performed based on the engine speed and the throttle opening detected by U110. When the engine speed is in a low speed range, the control valve 104 is closed, and the exhaust gas is guided to the muffler body 100 having a large air flow resistance to achieve quiet operation. I try to enhance the nature. On the other hand, when the engine speed is in the high engine speed range, the control valve 104 is opened, and most of the exhaust gas is led to the bypass pipe 102 having a low airflow resistance to improve the engine output.

[0004]

However, in the case of the above-described conventional silencer, the quietness is improved when the control valve 104 is closed, but when the engine speed is in a high engine speed range. However, there is a problem that the quietness is greatly impaired because the control valve 104 is opened and a low-ventilation-resistance-oriented path is used in which most of the exhaust gas flows through the bypass pipe 102.

The present invention has been proposed in order to cope with such circumstances, and the exhaust noise level is deteriorated not only when the engine speed is in a low speed range but also in a high speed range. It is an object of the present invention to provide an automobile exhaust silencer capable of preventing noise and ensuring quietness.

[0006]

Means for Solving the Problems (1) In order to achieve the above object, a muffler main body having a plurality of expansion chambers having different muffling characteristics, and an exhaust gas introduced into the muffler main body is short-circuited to the atmosphere. In a vehicle exhaust silencer having a bypass pipe for discharging, a chamber is provided in the bypass pipe, and a control valve for controlling an amount of exhaust gas introduced into the chamber is provided, and the chamber is closed when the control valve is closed. Is designed to function as a resonance chamber.

(2) In order to achieve the above object, there is provided a muffler main body provided with a plurality of expansion chambers having different muffling characteristics, and a bypass pipe for short-circuiting exhaust gas introduced into the muffler main body and discharging the exhaust gas to the atmosphere. In a vehicle exhaust silencer, a chamber is provided in the bypass pipe,
A control valve for controlling the amount of exhaust gas introduced into the chamber is provided, and when the control valve is open, the chamber functions as an expansion chamber.

(3) In order to achieve the above object, there is provided a muffler main body having a plurality of expansion chambers having different muffling characteristics, and a bypass pipe for short-circuiting the exhaust gas introduced into the muffler main body and discharging the exhaust gas to the atmosphere. In a vehicle exhaust silencer, a chamber is provided in the bypass pipe,
A control valve for controlling the amount of exhaust gas introduced into the chamber is provided. When the control valve is closed, the chamber functions as a resonance chamber, and when the control valve is open, the chamber functions as an expansion chamber. To make it work.

(4) In the above items (1) to (3),
Control means for detecting an engine speed or an accelerator opening is provided, and an actuator for opening and closing the control valve according to the engine speed or the accelerator opening detected by the control means.

(5) In the above items (1) to (3),
The control valve is an exhaust pressure sensitive valve that opens when the exhaust pressure becomes equal to or higher than a predetermined value and guides exhaust gas to the bypass pipe, and closes the bypass pipe when the exhaust pressure is lower than the predetermined value.

(6) In the above item (5), the control valve can increase or decrease the amount of exhaust flowing into the bypass pipe and the chamber as the exhaust pressure increases or decreases.

(7) In the above item (5), when the control valve is closed, a resonance chamber of the muffler main body and a resonance chamber formed by the chamber have independent resonance chambers.

(8) In the above items (1) to (7),
The reduced inner diameter of the chamber cross section is set to be 1.2 to 2.5 times the inner diameter of the bypass pipe.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an exhaust silencer for a vehicle according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 to FIG. 4 are views showing a vehicle exhaust silencer according to a first embodiment of the present invention. In FIG. 1, a muffler main body 12 includes
, A bypass pipe 14, a chamber 16, a control valve 18, and the like.

A plurality of expansion chambers are formed in the muffler main body 12, and a bypass pipe 14 for guiding a part of exhaust gas is provided. As shown in FIG. 2, the bypass pipe 14 has 14A on the inlet side and the outlet side of the exhaust gas,
A chamber 16 having an inner diameter larger than that of the bypass pipe 14 is connected between the bypass pipes 14A and 14B.
The inner diameter of the chamber 16 is desirably set to 1.2 to 2.5 times the inner diameter of the bypass pipe 14. Also,
A control valve 18 is provided between the bypass pipe 14B and the chamber 16.

The control valve 18 is driven to open and close by an actuator (not shown). As shown in FIG. 3, the control valve 18 includes a butterfly valve 20 to minimize the influence of the exhaust pressure on the control valve 18. ing. The butterfly valve 20 is formed in a disk shape having substantially the same diameter as the inner diameter of the bypass pipe 14, and a shaft 22 is fixed to a portion passing through the center of the disk. The shaft 22 is connected to the bypass pipe 1 by bushes 24, 24.
4 so as to be rotatable. Also, the shaft 22
The upper end of the lever protrudes from the bypass pipe 14. The upper end of the lever includes a spring 26 for urging the butterfly valve 20 to rotate in the closing direction, a plate 28 for regulating the spring 26, a drum 30, and an arc-shaped pulley 31. Plate 32 is attached by nut 34.

A bracket 36 attached to the control valve 18 is fixed to the bypass pipe 14, and a sleeve end of a driving wire connected to an actuator (not shown) is attached. Thus, the butterfly valve 20, which is normally biased to rotate in the closing direction, can rotate against the biasing force of the spring 26 by the action of the actuator.

Next, the internal structure of the muffler main body 12 will be described. In FIG. 4, the muffler body 12 includes a pipe 38 into which exhaust gas is introduced, a first expansion chamber 40, and a second expansion chamber 42.
, A third expansion chamber 44, a fourth expansion chamber 46, and a sound absorbing tube 48.
And a tail pipe 50.

The first expansion chamber 40 is an end plate 52 and a partition 54, the second expansion chamber 42 is a partition 54 and a partition 56, the third expansion chamber 44 is a partition 56 and a partition 58, and a fourth expansion chamber 46.
Are defined by a partition wall 58 and an end plate 60, respectively. Each adjacent expansion room 40, 42, 44, 4
The six spaces are connected by a pipe. Further, the bypass pipe 14 connects the first expansion chamber 40 and the fourth expansion chamber 46. The opening and closing operation of the control valve 18 provided in the bypass pipe 14 is controlled by an actuator 62. The actuator 62 is connected to the control means 64, and the control means 64 controls the actuator 62 according to the detected engine speed or the accelerator opening.
Is driven to open and close the control valve 18.

Here, the expansion chamber, the resonance chamber, and the exhaust pulsation sound, which are the internal structures of the silencer, will be described. FIG. 5 is a diagram showing the relationship between the shape of the expansion chamber and the noise reduction characteristics. As shown in the graph of the figure, the noise reduction effect has a characteristic that changes periodically, and the longer the expansion room, the more the noise reduction effect is exerted on low-frequency to high-frequency exhaust noise. Therefore, even when the extension room cannot be long, a high noise reduction effect can be obtained with respect to the exhaust noise in the high frequency range.

FIGS. 6 to 8 are diagrams showing the relationship between the shape of the resonance chamber and the noise reduction characteristics. As shown in these figures, the resonance chamber has a remarkable noise reduction effect in a frequency band near the resonance frequency, and this resonance frequency can be changed by adjusting the resonance chamber capacity and the length of the resonance chamber neck. That is,
Even when the resonance chamber capacity cannot be sufficiently secured, the resonance frequency can be set within a certain range by changing the length of the bypass pipe (resonance chamber neck).

The exhaust pulsation noise is a fluid noise generated by the opening and closing of the exhaust valve, and is a periodic noise related to the engine speed and the number of cylinders.
(rpm), f (Hz) for a 4-cycle engine
= Z × (N / 60) × 0.5 fundamental frequency f
(Hz) and its harmonics. As can be understood from the above equation, the engine speed and the frequency of the exhaust pulsation sound are in a proportional relationship.

Generally, in the low engine speed range (up to about 3000)
In the vehicle noise at (rpm), the ratio of the exhaust pulsation noise is very large, and the pulsation sound level of the fundamental frequency f (Hz) is dominant in the exhaust pulsation noise. Therefore, in order to improve the quietness in the low engine speed region, it is effective to combine several extension rooms having a long extension room length and remove low-frequency noise. In addition, for noise in a specific frequency band that cannot be completely suppressed by the combination of the expansion rooms, it is effective to provide a resonance chamber in the muffler body and mute the resonance by adjusting the resonance frequency to that frequency band. is there.

The operation of the first embodiment will be described below based on the characteristics of the expansion chamber, the resonance chamber, and the exhaust pulsation noise described above.

First, when the engine speed is lower than the set value N ₁ (engine speed ≦ N ₁ ), as shown in FIG. 4, the control valve 18 is in the closed state, and the control valve 18 is connected from the pipe 38 to the muffler main body 12. The incident exhaust noise first enters the first expansion chamber 40, and then passes through the second expansion chamber 42, the third expansion chamber 44, the fourth expansion chamber 46, and the sound absorbing tube 48 in this order.
It is released to the atmosphere through the tail pipe 50. In this case, 1 is provided by the chamber 16 and the bypass pipe 14A.
Four resonance chambers (hatched portions in FIG. 4) 66 are formed. That is, the muffler of the first embodiment is of a type in which the resonance chamber 66 is completely separated from the muffler main body 12.

As a result, each expansion chamber in the muffler main body 12 can be made larger, and exhaust pulsation noise in a low frequency band that occurs when the engine speed is low can be efficiently eliminated. Further, the separated resonance chamber 66 can be set to a desired frequency by adjusting the length and the like of the bypass pipe 14 and changing the capacity thereof.
Further, quietness can be improved.

When the engine speed is higher than the set value N ₁ (engine speed> N ₁ ), as shown in FIG.
The butterfly valve 20 of the control valve 18 is opened, and most of the exhaust gas is supplied to the path having the lowest airflow resistance, ie, the pipe 38,
First expansion chamber 40, bypass pipe 14A, chamber 1
6, bypass pipe 14B, fourth expansion chamber 46, sound absorbing pipe 4
8 and short-circuit in order, and are discharged from the tail pipe 50 to the atmosphere. In the case of the present embodiment, the control of the control valve 18 uses the actuator 62, so there is a concern that the exhaust sound level is deteriorated when the butterfly valve 20 is opened. However, the chamber 16 installed in the bypass pipe 14 is , The deterioration can be reduced.

FIG. 10 shows a silencer according to a second embodiment, in which four expansion chambers are formed in the first embodiment, whereas three expansion chambers are formed in the present embodiment. However, the difference is that a part of the muffler body 12 'is used as the resonance chamber.

The muffler body 12 ′ includes a pipe 38 ′ into which exhaust gas is introduced, a first chamber 68 forming a resonance chamber, a first expansion chamber 70, a second expansion chamber 72, and a third expansion chamber 74. , A sound absorbing tube 48 and a tail pipe 50. First
The chamber 68 is formed by the end plate 52 and the partition 54 ′, the first expansion chamber 70 is formed by the partition 56 and the partition 58, the second expansion chamber 72 is formed by the partition 54 ′ and the partition 56, and the third expansion chamber 74 is formed by the partition 58 and the end plate 60. Each is defined.
The adjacent expansion chambers 70, 72, 74 are communicated by pipes. A small hole 7 for introducing exhaust gas into the first expansion chamber 70 is provided on an outer peripheral surface of the pipe 38 ′ facing the first expansion chamber 70.
6 are perforated. The same members as those in the first embodiment, such as the bypass pipe 14, the control valve 18, and the actuator 62, are denoted by the same reference numerals as those in the first embodiment, and description thereof will be omitted.

The operation of the second embodiment configured as described above is as follows. First, when the engine speed is lower than the set value N ₁ (engine speed ≦ N ₁ ), as shown in FIG. 10, the exhaust noise incident on the muffler main body 12 ′ from the pipe 38 ′ passes through the small hole 76. Through the first expansion room 7
0, and the second expansion chamber 72, the third expansion chamber 74,
After passing through the sound absorbing tube 48 in this order, it is released to the atmosphere through the tail pipe 50.

In this embodiment, the first chamber 68 and the bypass pipe 14 are closed by closing the control valve 18.
A and the chamber 16 function as one resonance chamber 78 (hatched portion) as a whole. That is, the resonance chamber 7 of the present embodiment
8 uses an externally mounted chamber 16 to expand the capacity thereof, so that the muffler main body 12 ′ is conventionally used.
The size of the first chamber 68 in the muffler main body 12 'can be reduced as compared with the case where the resonance chamber is provided only inside the muffler. Accordingly, the length of the first expansion chamber 70, the second expansion chamber 72, and the third expansion chamber 74 formed in the muffler main body 12 'can be made longer, and the exhaust in the low frequency band can be performed. Noise can be efficiently silenced.

When the engine speed is higher than the set value N ₁ (engine speed> N ₁ ), as shown in FIG.
0 opens, and most of the exhaust gas passes through the path having the smallest ventilation resistance, that is, the pipe 38 ', the first chamber 68, the bypass pipe 14A, the chamber 16, the bypass pipe 14B, the third expansion chamber 74, and the sound absorbing pipe 48 in this order. And tail pipe 50
Is released into the atmosphere. When the butterfly valve 20 is opened, the chamber 16 functions as an expansion chamber, so that the deterioration of quietness can be minimized.

Next, a third embodiment will be described.
FIGS. 12 to 16 show a muffler according to a third embodiment. In the above-described first and second embodiments, the control valve 18 is driven to be opened and closed by the actuator 62. The difference is that an exhaust pressure sensitive control valve 80 that opens and closes using the exhaust pressure is used. Since the structure of the muffler body is the same as that of the second embodiment, the same portions are denoted by the same reference numerals and description thereof will be omitted.

As shown in FIGS. 12 to 14, the control valve 80 is attached to the end of the opening of the bypass pipe 14A inserted into the chamber 16. The control valve 80 is mainly configured by a flap valve 82 that is cantilevered and rotatably supported by exhaust pressure. The flap valve 82 is formed in a bowl shape so as to close the opening of the bypass pipe 14A.
4 rotatably supported by a shaft 86.

A lower end and an upper end of the shaft 86 are supported by bushes 87A and 87B integrally attached to the surface of the chamber 16, respectively, and are disposed in a spring holder 88. By being connected to one end (not shown) of the 89, it is normally urged to rotate so as to close the opening of the bypass pipe 14A. The spring holder 88
A nut 90 is fixed on the chamber 16 by being screwed into a threaded portion on the upper portion of the shaft 86.

The urging force of the spring 89 is applied to the flap valve 8.
2 is set to open when an exhaust pressure equal to or more than a predetermined value acts (the engine speed at this time is assumed to be N _{2 c} ), and as the engine speed increases, the opening of the flap valve 82 increases. become large, the engine rotational speed N _20,
As shown by the two-dot chain line in FIG.

The operation of the third embodiment configured as described above is as follows. First, when the engine speed is lower than the set value N _2c (engine speed ≦ N _2c ), FIG.
As shown in the figure, since the flap valve 82 is closed,
The first chamber 68 and the bypass pipe 14A partitioned by the partition wall 54 'and the end plate 52 form a resonance chamber 91.
(Shaded area). Also, bypass pipe 1
4B and the chamber 16 form a resonance chamber 92 (shaded area).

Exhaust noise that has entered the muffler main body 12 ′ from the pipe 38 ′ passes through the small hole 76 and enters the first expansion chamber 70. Hereinafter, the second expansion chamber 72, the third expansion chamber 74, and the sound absorbing pipe After passing in the order of 48, it is released to the atmosphere through the tail pipe 50. Thus, in the present embodiment, when the engine speed is lower than the set value N _2c, it means having two resonance chambers 91, 92 independently, the exhaust noise in a low frequency band effectively silencing It is possible to

When the engine speed is higher than the set value N _2c (engine speed> N _2c ), as shown in FIG. 16, when the pressure of the exhaust applied to the flap valve 82 in the chamber 16 exceeds the set value. The flap valve 82 starts to rotate gradually against the urging force of the spring 89. For this reason,
The first chamber 68 functioning as the resonance chamber 91 starts functioning as the expansion chamber. In this case, in addition to the flow shown in FIG. 15 described above, a part of the exhaust is pipe 38 ', first chamber 68, bypass pipe 14A, chamber 16, bypass pipe 14B, third expansion chamber 74, and sound absorbing pipe. After passing through 48, it is released from the tail pipe 50.

When the engine speed increases and the exhaust pressure further increases, the amount of rotation of the flap valve 82 increases, the bypass pipe 14A is completely opened, and the exhaust gas entirely shifts to the flow shown in FIG. . When the flap valve 82 is fully opened, the chamber 16 functions as an expansion chamber, so that high-frequency exhaust noise associated with an increase in the engine speed can be effectively silenced.

As described above, since the control valve 80 of the third embodiment performs the opening / closing operation by using the exhaust pressure, the engine speed can be reduced as in the first and second embodiments. Control means 64 and actuator 6 for detecting
2 is unnecessary and the configuration can be simplified, and as a result, the cost of the silencer itself can be significantly reduced.

[0042]

As described above, according to the present invention,
A chamber is provided in the bypass pipe of the silencer, and a control valve for controlling the introduction of exhaust gas into the chamber is provided. When the control valve is closed, the chamber is used as a resonance chamber. When the control valve is open, the chamber is used as an expansion chamber. For this reason, efficient noise reduction of exhaust noise is possible.

[Brief description of the drawings]

FIG. 1 is an overall view showing a first embodiment of a vehicle exhaust silencer according to the present invention.

FIG. 2 is a partial cross-sectional view showing, on an enlarged scale, a chamber which is a main part of the muffler according to the first embodiment.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is an explanatory diagram showing the operation of the vehicle noise reduction device of the first embodiment.

FIG. 5 is a diagram showing the relationship between the shape of the expansion chamber and the noise reduction characteristics.

FIG. 6 is a diagram showing the relationship between the shape of the resonance chamber and the noise reduction characteristics.

FIG. 7 is a diagram showing the relationship between the shape of the resonance chamber and the noise reduction characteristics.

FIG. 8 is a diagram showing the relationship between the shape of the resonance chamber and the noise reduction characteristics.

FIG. 9 is an explanatory diagram showing the operation of the vehicle noise reduction device of the first embodiment.

FIG. 10 is an explanatory diagram showing an operation of the vehicle noise reduction device of the second embodiment.

FIG. 11 is an explanatory view showing the operation of the vehicle noise reduction device of the second embodiment.

FIG. 12 is an overall view showing a third embodiment of the vehicle exhaust silencer according to the present invention.

FIG. 13 is a partial cross-sectional view showing, on an enlarged scale, a chamber which is a main part of the muffler according to the third embodiment.

FIG. 14 is a sectional view taken along line BB of FIG. 12;

FIG. 15 is an explanatory diagram illustrating the operation of the vehicle noise reduction device according to the third embodiment.

FIG. 16 is an explanatory diagram illustrating the operation of the vehicle noise reduction device according to the third embodiment.

FIG. 17 is a diagram showing a configuration of a conventional automobile noise reduction device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Silencer for automobiles 12 12 'Muffler main body 14 14A 14B Bypass pipe 16 Chamber 18 80 Control valve 20 Butterfly valve 22 86 Shaft 24 Bush 26 89 Spring 28 Plate 30 Drum 31 Pulley 32 Lever plate 34 90 Nut 36 Bracket 38 38' Pipe 40 70 First expansion chamber 42 72 Second expansion chamber 44 74 Third expansion chamber 46 Fourth expansion chamber 48 Sound absorbing tube 50 Tail pipe 52 60 End plate 54 54 '56 58 Partition wall 62 Actuator 64 Control means 66 78 91 92 Resonance chamber 68 First chamber 76 Small hole 82 Flap valve 84 Support piece 88 Spring holder

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kazuhiko Taguchi 292 Oaza Bessho, Ota-shi, Gunma Sakamoto Kogyo Co., Ltd. (72) Inventor Makoto Sato 292 Oaza Bessho, Ota-shi, Gunma Sakamoto Kogyo F-term ( Reference) 3G004 AA01 CA01 CA11 DA03 DA24 EA02

Claims (8)

[Claims] 1. An exhaust muffler for a vehicle, comprising: a muffler main body having a plurality of expansion chambers having different muffling characteristics; and a bypass pipe for short-circuiting exhaust gas introduced into the muffler main body and discharging the exhaust air to the atmosphere. An automobile, wherein a pipe is provided with a chamber, and a control valve for controlling an amount of exhaust gas introduced into the chamber is provided, and the chamber functions as a resonance chamber when the control valve is closed. Exhaust silencer. 2. An exhaust muffler for a vehicle, comprising: a muffler main body including a plurality of expansion chambers having different muffling characteristics; and a bypass pipe that short-circuits exhaust gas introduced into the muffler main body and discharges the air to the atmosphere. A vehicle, wherein a pipe is provided with a chamber, and a control valve for controlling the amount of exhaust gas introduced into the chamber is provided, and the chamber functions as an expansion chamber when the control valve is open. Exhaust silencer. 3. An exhaust muffler for a vehicle, comprising: a muffler main body having a plurality of expansion chambers having different muffling characteristics; and a bypass pipe for short-circuiting exhaust gas introduced into the muffler main body and discharging the exhaust air to the atmosphere. A pipe is provided with a chamber, and a control valve for controlling the amount of exhaust gas introduced into the chamber is provided. When the control valve is closed, the chamber functions as a resonance chamber, and when the control valve is open. A vehicle exhaust silencer wherein the chamber functions as an expansion chamber. 4. A control means for detecting an engine speed or an accelerator opening, and an actuator for opening and closing the control valve according to the engine speed or the accelerator opening detected by the control means. The automobile exhaust silencer according to claim 1, wherein: 5. An exhaust pressure-sensitive control valve that opens when the exhaust pressure becomes equal to or higher than a predetermined value and guides exhaust gas to the bypass pipe, and closes the bypass pipe when the exhaust pressure is lower than the predetermined value. The exhaust muffler for an automobile according to any one of claims 1 to 3, wherein the exhaust muffler is a valve. 6. The vehicle exhaust silencer according to claim 5, wherein the control valve is capable of increasing or decreasing exhaust flowing into the bypass pipe and the chamber as exhaust pressure increases or decreases. 7. The resonance chamber according to claim 5, wherein when the control valve is closed, a resonance chamber of the muffler main body and a resonance chamber formed by the chamber are provided independently of each other. Exhaust silencer for cars. 8. A vehicle exhaust silencer according to claim 1, wherein the reduced inner diameter of the cross section of the chamber is set to be 1.2 to 2.5 times the inner diameter of the bypass pipe. .