JPH116417A - Exhaust muffler for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the increase of the generation of all area exhaust noise since two muffling regions are moved through interference according to a valve opening and improve the output of an engine by preventing the increase of an exhaust pressure loss. SOLUTION: An inlet tube 7 to introduce exhaust gas from an engine and a tail tube 10 to discharge exhaust gas to the atmosphere are respectively communicated with an expansion chamber 2. A first volume chamber 3 is communicated with the expansion chamber 2 through a first pass tube 11, a second volume chamber 4 is communicated with the first volume chamber 3 through a second pass tube 13, and the first volume chamber 3 is communicated with an expansion chamber 2 through a third pass tube 12. A valve 14 opening when a pressure in the first or third pass tube 11 or 12 exceeds a given pressure is arranged at the end part of the first or third pass tube 11 or 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for reducing noise generated from an exhaust system of an automobile or the like.

[0002]

2. Description of the Related Art As a conventional automobile exhaust silencer,
The present inventor has proposed a technique described in the specification and drawings of Japanese Patent Application No. 8-121703. The purpose of this application is to achieve both reduction of exhaust noise and reduction of exhaust pressure loss at low engine speed and high engine speed. FIG. 21 shows this prior art. When the valve 114 is closed, the exhaust gas that enters from the inlet tube 107 is opened to the atmosphere via the expansion chamber 102, the first volume chamber 103, and the second pass tube 113. Are acting on the expansion chamber 102. Third pass tube 112
The resonance element composed of the second chamber 104 and the expansion chamber 1
02. Valve 11 when engine is running at low speed
Since 4 is in the closed state, two resonance elements work together to reduce exhaust noise. When the flow rate of the exhaust gas increases, as in the case of middle and high rotation, the pressure in the second pass tube 113 increases, and the valve 1 provided at the end of the second pass tube 113
14 is opened, and the exhaust gas flows from the first pass tube 111 to the first volume chamber 103 to the second pass tube 113 to the second volume chamber 1
Gas flows to 04. Therefore, the exhaust pressure loss is reduced and the output can be improved. Further, the pressure wave passing through this path and the path from the inlet tube 107 to the expansion chamber 102 interferes with each other in the porous portion 115 provided in the tail tube 110 and cancels each other, thereby reducing exhaust noise (hereinafter, referred to as interference effect). Since this interference effect moves with a change in valve opening due to an increase in engine rotation (an increase in flow rate), it is possible to further reduce exhaust noise. Incidentally, 10 in the figure
1 is a muffler, 105 is an end plate, 106 is an end plate, 108 is a porous portion, and 109 is a sound absorbing chamber.

[0003]

However, in the above-mentioned prior art, the two regions that have been silenced by the action of the two resonators existing when the valve 114 is closed are separated from the resonance element by the opening of the valve 114. Although the first muffling area can be further expanded by the interference effect due to the change to the expansion element, there is a problem that the muffling volume in the second area becomes insufficient. The present invention has been made in view of such a conventional problem, and an inlet tube for introducing an exhaust gas of an engine and a tail tube for discharging the exhaust gas to the atmosphere respectively communicate with an expansion chamber. Communicates a first volume chamber via a first pass tube, communicates a second volume chamber to the first volume chamber via a second pass tube, and the first volume chamber communicates with a third pass tube. A structure provided with a valve that communicates with the expansion chamber through the first pass tube or the third pass tube and that opens at the end of the first pass tube or the third pass tube when the pressure in the first pass tube or the third pass tube becomes a predetermined pressure or more. By doing so, it is intended to solve the above problems.

[0004]

According to a first aspect of the present invention, an exhaust tube for introducing exhaust gas from an engine and the exhaust gas are discharged into the atmosphere. The tail tubes each communicate with an expansion chamber, the expansion chamber communicates with a first volume chamber via a first pass tube, and the first volume chamber communicates with a second volume chamber via a second pass tube. The first volume chamber communicates with the expansion chamber via a third pass tube,
The end of the first pass tube or the third pass tube was provided with a valve that opens when the pressure in the first pass tube or the third pass tube becomes equal to or higher than a predetermined pressure.

[0005] In the vehicle exhaust silencer according to the second aspect, the inlet tube for introducing the exhaust gas of the engine and the tail tube for discharging the exhaust gas to the atmosphere respectively communicate with the expansion chamber, and the expansion chamber has a first path. The first volume chamber communicates via a tube, the first volume chamber and the second volume chamber communicate via a second pass tube, and the second volume chamber communicates with the expansion chamber via a third pass tube. The end of the third pass tube is provided with a valve that opens when the pressure in the third pass tube becomes equal to or higher than a predetermined pressure.

According to a third aspect of the present invention, in the vehicle exhaust silencer according to the first or second aspect, the first pass tube is formed integrally with the inlet tube, and the inlet tube communicates with the expansion chamber. A plurality of small holes in the inlet tube so that when the valve is set in the first pass tube formed integrally with the inlet tube, the pressure in the first pass tube is increased in the first volume chamber. The plurality of pressures provided in the inlet tube such that the pressure is equal to or higher than the pressure, or when the valve is set in the third pass tube, the pressure in the third pass tube is equal to or higher than the expansion chamber pressure. The opening ratio of the small holes to the expansion chamber was adjusted.

According to a fourth aspect of the present invention, in the vehicle exhaust silencer according to the first or second aspect, the first pass tube partially overlaps or is substantially coaxial with the inlet tube. To form a gap, the inlet tube is configured to communicate with the expansion chamber through the gap, and when a valve is set to the first pass tube, the pressure in the first pass tube is reduced to the third pass tube. The gap was adjusted so as to be equal to or higher than the pressure in the one-volume chamber, or so that the pressure in the third pass tube was equal to or higher than the pressure in the expansion chamber when the valve was set in the third pass tube.

According to a fifth aspect of the present invention, in the vehicle exhaust silencer according to the first or second aspect, the first pass tube is formed integrally with the inlet tube, and the inlet tube communicates with the expansion chamber. A branch pipe is formed in the middle of the inlet tube so that the pressure in the first pass tube is equal to or higher than the pressure in the first volume chamber when the valve is set in the first pass tube, or When the valve was set to the third pass tube, the inner diameter of the branch pipe was adjusted such that the pressure in the third pass tube was equal to or higher than the pressure in the expansion chamber.

According to a sixth aspect of the present invention, in the vehicle exhaust silencer according to any one of the first to fifth aspects, one end of the first pass tube or the third pass tube provided with the valve has a volume chamber. It was configured to be open at the position of the end plate or protruding into the volume chamber.

According to a seventh aspect of the present invention, in the vehicle exhaust silencer according to any one of the first to fifth aspects, the third pass tube is connected between the expansion chamber and the first volume chamber or the second volume chamber. The end plate has an opening provided therein, and a valve for opening the opening when the pressure in the first volume chamber or the second volume chamber becomes equal to or higher than a predetermined pressure is provided on the end plate.

[0011]

In the vehicle exhaust silencer of the present invention, the sound path is one when the valve is closed, and a desired noise reduction performance can be obtained. On the other hand, when the internal pressure of the tube provided with the valve increases and the valve opens, the acoustic path becomes two paths,
The region where the sound is muted changes due to the interference of the pressure waves in the two paths. In this case, the two muffling areas move in accordance with the valve opening that changes with pressure, and the muffling area can be expanded by interference. Therefore, it is possible to prevent an increase in exhaust noise over the entire area and not to increase exhaust pressure loss. I can do it.

[0012]

FIG. 1 shows a first embodiment of the present invention.
FIG. The muffler 1 is divided into an expansion chamber 2, a first volume chamber 3, and a second volume chamber 4 by end plates 5 and 6. An inlet tube 7 for introducing exhaust gas from an engine (not shown) opens to the expansion chamber 2 through a plurality of small holes 8 provided on the downstream side of the exhaust gas. A sound absorbing chamber 9 is provided in the expansion chamber 2 in order to release the introduced exhaust gas to the atmosphere.
Is connected to the tail tube 10 provided in the middle. The first volume chamber 3 is connected to the expansion chamber 2 via a first pass tube 11 formed integrally with the inlet tube 7. Further, the first volume chamber 3 is connected to the expansion chamber 2 via the third pass tube 12. Second volume chamber 4
Is connected to the first volume chamber 3 via the second pass tube 13. A valve 14 is provided at an open end of the second pass tube 13 to the second volume chamber 4. The valve 14 is set to start opening when the pressure in the third pass tube 12 becomes equal to or higher than a predetermined pressure. Therefore, when the valve 14 is closed, the first pass tube 11, the first volume chamber 3, the second pass tube 13, and the second volume chamber 4 constitute a two-stage resonator, and when the valve 14 is open, the first volume chamber 3 is expanded. And the second pass tube 13 and the second volume chamber 4
The first volume chamber 3 changed into the expansion chamber 2
Will work.

The plurality of small holes 8 provided in the inlet tube 7 so as to communicate with the expansion chamber 2 are such that the pressure in the third pass tube 12 becomes higher than the pressure in the second volume chamber 4 when the engine is operating. Set the number 8

FIGS. 13 and 14 show an example of a valve 14 for closing the end of the third pass tube 12. FIG. The valve 14 is swingably supported by a shaft 18. The shaft 18 is fixedly supported by a bracket 19. When the valve 14 is closed, the valve 14 comes into contact with the cushioning material 21 provided on the seating surface 20 so that exhaust gas does not flow. The cushioning material 21 is for reducing the tapping sound generated when the valve 14 directly hits the seating surface 20.
Needless to say, it may not be necessary if the hitting sound is low. The seat surface 20 is fixed to the end plate 5, and the third pass tube 12 is fixed to the seat surface 20 by press-fitting or the like via an opening 16 provided in the end plate 5. As the return spring 17, for example, a torsion coil spring is used, and the return spring 17 operates with the shaft 18 as a center axis. Return spring 1
One end of 7 comes into contact with the valve 14 and the other end comes into contact with the bracket 19 so as to generate an initial biasing force. The initial biasing force refers to a force for closing the valve 14 until the pressure in the third pass tube 12 reaches a predetermined pressure.

FIGS. 15 and 16 show other examples of the valve 14. FIG. Valve 1 shown in FIGS. 13 and 14
4 in that the bracket 19 is formed integrally with the seat surface 20. Since the seating surface 20 and the valve 14 can be fixed to the end plate 5 after being assembled in advance, the valve configuration has a high assembling accuracy.

Next, the operation and effect of this embodiment will be described.
First, the operation when the valve 14 is closed will be described. Expansion room 2
Since the internal pressure of the third pass tube 12 is higher than the internal pressure, the opening ratio of the small holes 8 provided in the inlet tube 7 to the expansion chamber 2 is very small, and as a result, the expansion ratio becomes large. High silencing performance. In addition, two noise reduction regions exist due to the action of the two-stage resonator, and exhaust noise is further reduced.

Next, the operation when the valve 14 is open will be described. There are two acoustic paths when the valve 14 is open. One is the path 1 through which gas normally flows when the valve 14 is closed, and is from the inlet tube 7 → the small hole 8 → the expansion chamber 2 → the tail tube 10. The other is a path 2 on the valve 14 open side, which is a path of the inlet tube 7 → the first pass tube 11 → the first volume chamber 3 → the third pass tube 12 → the valve 14 → the expansion chamber 2 → the tail tube 10. is there. Since these two paths meet at the entrance of the tail tube 10, the pressure waves interfere with each other and cancel each other. In this case, since the valve opening changes with an increase in the exhaust gas flow rate, the regions that are silenced by the interference move according to the valve opening. In particular, the second silencing region moves to the silencing frequency of the resonator constituted by the second pass tube 13 and the second volume chamber 4 according to the opening of the valve 14. Similarly, in the conventional example, the interference region moves, but in the two regions where the sound is muted by the action of the two resonators existing when the valve is closed, all the resonance elements are changed to expansion elements by opening the valve. As a result, the first silencing region can be further expanded by the interference effect, but the silencing volume in the second region becomes insufficient. On the other hand, since the two silencing regions move due to interference in accordance with the valve opening, the silencing region can be expanded by the interference effect, so that it is possible to prevent an increase in exhaust noise over the entire area and increase exhaust pressure loss. Since it is not performed, the output of the engine can be improved.

FIG. 2 is a diagram showing a second embodiment. As compared with the first embodiment, each chamber partitioned by the end plates 5 and 6 is arranged so as to be the expansion chamber 2, the second volume chamber 4, and the first volume chamber 3 from the exhaust gas upstream side. Since the first pass tube 11 can be set longer, the resonance frequency on the low-frequency side of the two-stage resonator when the valve 14 is closed can be set to a lower frequency, in addition to the operational effects of the first embodiment. The noise reduction characteristics of the frequency can be improved.

FIG. 3 is a diagram showing a third embodiment. As compared with the first embodiment, each chamber partitioned by the end plates 5 and 6 is arranged so as to be the second volume chamber 4, the expansion chamber 2, and the first volume chamber 3 from the exhaust gas upstream side. And a second pass tube 1 for communicating the first volume chamber 3 with the second volume chamber 4.
3, the resonance frequency on the low frequency side of the two-stage resonator when the valve 14 is closed can be set to a lower frequency in addition to the operation and effect of the first embodiment, thereby improving the low-frequency silencing characteristics. it can.

FIG. 4 is a diagram showing a fourth embodiment. The inlet tube 7 and the first pass tube 11 are overlapped on the same axis in the expansion chamber 2, and the inner diameter of the first pass tube 11 is made larger than the outer diameter of the inlet tube 7, thereby forming a gap 15 between the tubes. The pressure in the third pass tube 12 is set to be equal to or higher than the pressure in the expansion chamber 2. Increasing the length of the overlap between the inlet tube 7 and the first pass tube 11 is equivalent to disposing a small-diameter pipe between the inlet tube 11 and the expansion chamber 2. In addition, the noise reduction characteristics when the valve 14 is closed are greatly improved.

FIG. 5 is a diagram showing a fifth embodiment. The first pass tube 11 is formed integrally with the inlet tube 7, a branch pipe 22 is formed in the inlet tube 7 so as to communicate the inlet tube 7 and the expansion chamber 2, and the valve 14 is connected to the end of the third pass tube 12. The inner diameter of the branch pipe 22 is adjusted so that the pressure in the third pass tube 12 is equal to or higher than the pressure in the expansion chamber 2. The small-diameter branch pipe 22 is disposed between the inlet tube 7 and the expansion chamber 2, and in addition to the operation and effect of the first embodiment, the noise reduction characteristics when the valve 14 is closed is greatly improved.

FIG. 6 shows the sixth embodiment. In contrast to the first embodiment, the valve 14 is connected to the first pass tube 11
The airflow noise generated by the valve 14 when the valve 14 is opened passes through the first volume chamber 3 and the expansion chamber 2 which have been changed to expansion elements in two stages. Therefore, the airflow noise can be further suppressed as compared with the first embodiment. Needless to say, the same operation and effect can be obtained even if the same valve arrangement is provided in the second embodiment.

FIG. 7 shows a seventh embodiment. Each chamber partitioned by the end plates 5 and 6 is partitioned into a first volume chamber 3, a second volume chamber 4, and an expansion chamber 2 from the exhaust gas upstream side. The inlet tube 7 is opened to the expansion chamber 2 by a plurality of small holes 8, and the end of the inlet tube 7 is
3 blocks the exhaust gas from flowing. A first pass tube 11 branching from the inlet tube 7 is formed and connected to the first volume chamber 3. Since it is not necessary to make the first pass tube 11 the same diameter as the inlet tube 7, in addition to the effects of the first embodiment, the valve 14
The degree of freedom in designing the resonance frequency of the two-stage resonator at the time of closing is expanded. It is needless to say that a similar effect can be obtained even if the first volume chamber 3 and the second volume chamber 4 are replaced.

FIG. 8 is a diagram showing an eighth embodiment. Compared to the seventh embodiment, the arrangement of the second volume chamber 4 and the expansion chamber 2 is replaced, and the tail tube 10 can be lengthened. Can be further improved, and the second pass tube 13 can be lengthened, so that the resonance frequency of the two-stage resonator when the valve 14 is closed can be set to a lower frequency, and the low-frequency noise reduction characteristic can be improved. Can be improved.

FIG. 9 shows a ninth embodiment. In contrast to the seventh embodiment, the valve 14 is connected to the first pass tube 11
When the valve 14 is opened, the valve 14
The airflow noise generated in the first volume chamber 3 changed into an expansion element
And two stages of the expansion chamber 2, the airflow noise can be suppressed more than in the seventh embodiment.

FIG. 10 shows a tenth embodiment. The inlet tube 7 and the tail tube 10 communicate with the expansion chamber 2, respectively. The expansion chamber 2 communicates with the first volume chamber 3 via the first pass tube 11, and the first volume chamber 3 and the second volume chamber 4 The second pass tube 13 communicates with the second pass tube 13, and the second pass tube 13 communicates with the expansion chamber 2 via the third pass tube 12. Since the valve 14 opens when the pressure becomes equal to or higher than the predetermined pressure, the second pass tube 13 that connects the first volume chamber 3 and the second volume chamber 4 can be set longer than in the first embodiment. Therefore, the valve 14
The resonance frequency on the low frequency side of the two-stage resonator at the time of blockage can be set to a lower frequency, and the silencing characteristics of the low frequency can be improved. Further, compared to the other embodiments, the number of tubes is smaller, and the layout for one cross section of the muffler and the degree of freedom in designing the maximum tube diameter are expanded.

FIG. 11 shows the eleventh embodiment. As compared with the first embodiment, an opening 16 that connects the first volume chamber 3 and the expansion chamber 2 is formed in the end plate 5, and the opening 16 is opened when the pressure in the first volume chamber 3 reaches a predetermined pressure. A valve 14 is provided on the end plate 5. Examples of the valve 14 include those shown in FIGS. Valve 1
4 is swingably supported by a shaft 18. The shaft 18 is fixedly supported by a bracket 19. A seating surface 20 is press-formed on the end plate 5. When the valve 14 is closed, the valve 14 comes into contact with the cushioning material 21 provided on the seating surface 20, and closes the opening 16 so that the exhaust gas does not flow. The cushioning member 21 is for reducing the tapping sound generated when the valve 14 directly hits the seating surface 20, and it is needless to say that the buffering member 21 may be omitted when the tapping sound is low. As the return spring 17, for example, a torsion coil spring is used, and the return spring 17 operates with the shaft 18 as a center axis.
One end of the return spring 17 is attached to the valve 14 and the other end thereof is in contact with the bracket 19 to generate an initial biasing force. The initial biasing force refers to a force for closing the valve 14 until the pressure in the third pass tube 12 reaches a predetermined pressure. Since the size of the opening 16 can be freely changed, the degree of freedom in performance design is further expanded. Further, the opening 16 of the present embodiment is different from the other embodiments.
Needless to say, the valve 14 is applicable.

FIG. 12 shows a twelfth embodiment. In contrast to Embodiment 2, the end of the third pass tube 12 opening to the expansion chamber 2 is formed on the same plane as the end plate 5, and the valve 14 is closed so as to close the opening end of the third pass tube 12. Is provided. As the valve 14, FIG.
9, there is one as shown in FIG. Valve 14 is shaft 1
8 for swinging support. The shaft 18 is fixedly supported by a bracket 19. The end plate 6 has a seating surface 20.
Is press-formed. Seat 2 when valve 14 is closed
The valve 14 comes into contact with the cushioning material 21 provided at the position 0 so that the exhaust gas does not flow. The cushioning member 21 is for reducing the tapping sound generated when the valve 14 directly hits the seating surface 20, and it is needless to say that the buffering member 21 may be omitted when the tapping sound is low.

The third pass tube 12 is fixed to the opening 16 provided in the end plate 5 by press fitting or the like. As the return spring 17, for example, a torsion coil spring is used.
It is configured to operate with 8 as the central axis. One end of the return spring 17 is attached to the valve 14 and the other end thereof is in contact with the bracket 19 to generate an initial biasing force. The initial biasing force refers to a force for closing the valve 14 until the pressure in the third pass tube 12 reaches a predetermined pressure. By changing the hole diameter of the end plate supporting the third pass tube 12, the diameter of the communication pipe can be changed.
4. Since the bracket 19 can be used in common, there is no change in parts due to a difference in vehicle type, and the cost is reduced. Also, the third pass tube 1 of the present embodiment is similarly applied to other embodiments.
Needless to say, the valve 2 and the valve 14 can be applied.

As described above, according to the present invention, the inlet tube 7 for introducing the exhaust gas of the engine and the tail tube 10 for discharging the exhaust gas to the atmosphere communicate with the expansion chamber 2, respectively. The first chamber 3 communicates with the expansion chamber 2 via the first pass tube 11,
The first volume chamber 3 communicates with the second volume chamber 4 via the second pass tube 13, and the first volume chamber 3 communicates with the expansion chamber 2 via the third pass tube 12, The end of the tube 11 or the third pass tube 12 is provided with a valve 14 that opens when the internal pressure of the first pass tube 11 or the third pass tube 12 exceeds a predetermined pressure. In accordance with, the two silencing regions move by interference, and the silencing region can be expanded by the interference effect. Therefore, it is possible to prevent an increase in exhaust noise over the entire area and not to increase the exhaust pressure loss.
The output of the engine can be improved.

The second embodiment differs from the first embodiment in that the chambers separated by the end plates 5 and 6 become the expansion chamber 2, the second volume chamber 4, and the first volume chamber 3 from the exhaust gas upstream side. In addition to the operation and effect of the first embodiment, the resonance frequency on the low frequency side of the two-stage resonator when the valve 14 is closed can be set to a lower frequency, thereby improving the low-frequency noise reduction characteristics. it can.

In the third embodiment, as compared with the first embodiment, the muffler 1 is partitioned by the end plates 5 and 6 from the exhaust gas upstream side into the second volume chamber 4, the expansion chamber 2, and the first volume chamber 3 respectively. In addition to the operation and effect of the first embodiment, the resonance frequency on the low frequency side of the two-stage resonator when the valve 14 is closed can be set to a lower frequency. Characteristics can be improved.

In the fourth embodiment, the inlet tube 7 and the first pass tube 11 are overlapped on the same axis in the expansion chamber 2, and the inner diameter of the first pass tube 11 is made larger than the outer diameter of the inlet tube 7. Since the gap 15 between the tubes was set so that the pressure in the third pass tube 12 was equal to or higher than the pressure in the expansion chamber 2, a small-diameter pipe was disposed between the inlet tube 7 and the expansion chamber 2. This is equivalent to the above, and in addition to the operation and effect of the first embodiment, the noise reduction characteristic when the valve 14 is closed is greatly improved.

In the fifth embodiment, the first pass tube 11 is formed integrally with the inlet tube 7, and a branch pipe 22 is formed in the inlet tube 7 so as to communicate the inlet tube 7 and the expansion chamber 2. The third pass tube 12 is set at the end of the third pass tube 12,
Branch pipe 22 so that the pressure inside
Is adjusted and the small-diameter branch pipe 22 is arranged between the inlet tube 7 and the expansion chamber 2. Therefore, the small-diameter branch pipe 22 is arranged between the inlet tube 7 and the expansion chamber 2. In addition to the functions and effects of the first embodiment, the silencing characteristics when the valve 14 is closed are greatly improved.

The sixth embodiment differs from the first embodiment in that the valve 14 is provided at the end of the first pass tube 11 on the first volume chamber 3 side.
The airflow noise generated by the above can be further suppressed.

In the seventh embodiment, each chamber divided by the end plates 5 and 6 of the muffler 1 is divided into a first volume chamber 3, a second volume chamber 4, and an expansion chamber 2 from the exhaust gas upstream side. The tube 7 is opened in the expansion chamber 2 by a plurality of small holes 8. The end of the inlet tube 7 is closed by a stopper 23 so that exhaust gas does not flow, and a first pass tube 11 branched from the inlet tube 7 is formed. , The first pass tube 1 is connected to the first volume chamber 3.
Since it is not necessary to make 1 the same diameter as the inlet tube 7, in addition to the operation and effect of the first embodiment, the degree of freedom in designing the resonance frequency of the two-stage resonator when the valve 14 is closed increases.

In the eighth embodiment, as compared with the seventh embodiment, the structure in which the arrangement of the second volume chamber 4 and the expansion chamber 2 is replaced is adopted, so that the noise reduction characteristics of the whole area can be further improved and the second path can be improved. Since the tube 13 can be lengthened, the resonance frequency of the two-stage resonator at the time of closing the valve 14 can be set to a lower frequency, and the number of times of the exhaust stagnation is reduced.

In the ninth embodiment, as compared with the seventh embodiment, the valve 14 is provided in the first pass tube 11, so that the airflow noise generated by the valve 14 when the valve 14 is opened can be further suppressed.

In the tenth embodiment, the inlet tube 7
And the tail tube 10 communicate with the expansion chamber 2, and the expansion chamber 2 is connected to the first volume chamber 3 through the first path tube 11.
The first volume chamber 3 and the second volume chamber 4 communicate with each other via a second pass tube 13, and the second path tube 13 communicates with the expansion chamber 2 via a third pass tube 12. Since the end of the pass tube 12 is provided with a valve 14 that opens when the pressure in the third pass tube 12 becomes equal to or higher than a predetermined pressure, the first volume chamber 3 differs from that of the first embodiment.
The length of the second pass tube 13 that communicates with the second volume chamber 4 can be set longer, so that the resonance frequency on the low frequency side of the two-stage resonator when the valve 14 is closed can be set to a lower frequency, and the low frequency noise can be reduced. Characteristics can be improved. In addition, since the number of tubes is small, the layout with respect to the muffler cross section and the design flexibility of the maximum tube diameter are expanded.

The eleventh embodiment differs from the first embodiment in that
The opening 16 communicating the first volume chamber 3 and the expansion chamber 2 is formed by the end plate 5.
Since the opening 16 is formed on the end plate 5 and the opening 16 is opened when the pressure in the first volume chamber 3 reaches a predetermined pressure, the size of the opening 16 can be freely changed. And the degree of freedom in performance design is further expanded.

Embodiment 12 differs from Embodiment 2 in that
Since the end of the third pass tube 12 opening to the expansion chamber 2 is formed on the same plane as the end plate 6 and the valve 14 is provided so as to close the opening end of the third pass tube 12, Since the diameter of the third pass tube 12 can be changed by changing the hole diameter of the end plate supporting the third pass tube 12, the valve 14 and the bracket 19 can be shared,
There are no parts changes due to differences in vehicle types, and costs are reduced.

[0042]

As described above, according to the present invention, the inlet tube for introducing the exhaust gas of the engine and the tail tube for discharging the exhaust gas to the atmosphere communicate with the expansion chamber. The chamber communicates a first volume chamber via a first pass tube, the first volume chamber communicates a second volume chamber via a second pass tube,
The first volume chamber communicates with the expansion chamber via a third pass tube, and the end of the first pass tube or the third pass tube has a pressure in the first pass tube or the third pass tube equal to or higher than a predetermined pressure. The structure provided with a valve that opens when it comes to an off state, the two noise reduction areas move by interference according to the valve opening, and the noise reduction area can be expanded by the interference effect, so that the exhaust noise throughout the area increases. Can be prevented, and the exhaust pressure loss can be prevented from increasing, so that the output of the engine can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an exhaust silencer for an automobile according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an exhaust silencer for an automobile according to a second embodiment of the present invention.

FIG. 3 is a diagram showing an exhaust silencer for an automobile according to a third embodiment of the present invention;

FIG. 4 is a diagram illustrating an exhaust silencer for an automobile according to a fourth embodiment of the present invention.

FIG. 5 is a diagram showing an exhaust silencer for an automobile according to a fifth embodiment of the present invention.

FIG. 6 is a diagram illustrating an exhaust silencer for an automobile according to a sixth embodiment of the present invention.

FIG. 7 is a diagram illustrating an exhaust silencer for an automobile according to a seventh embodiment of the present invention.

FIG. 8 is a diagram showing an exhaust silencer for an automobile according to an eighth embodiment of the present invention.

FIG. 9 is a diagram showing an exhaust silencer for an automobile according to a ninth embodiment of the present invention.

FIG. 10 is a diagram showing an exhaust silencer for an automobile according to a tenth embodiment of the present invention.

FIG. 11 is a diagram showing an automobile exhaust silencer according to Embodiment 11 of the present invention.

FIG. 12 is a diagram showing an automobile exhaust silencer according to a twelfth embodiment of the present invention.

FIG. 13 is a view showing a valve structure according to one embodiment of the present invention.

14 is a sectional view taken along the line AA in FIG.

FIG. 15 is a view showing a valve structure according to another embodiment of the present invention.

16 is a sectional view taken along line AA in FIG.

FIG. 17 is an enclosure showing a valve structure provided on an end plate according to one embodiment of the present invention.

18 is a sectional view taken along line AA in FIG.

FIG. 19 is a view showing a valve structure provided on an end plate according to another embodiment of the present invention.

20 is a sectional view taken along line AA in FIG.

FIG. 21 is a diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Muffler 2 Expansion chamber 3 First volume chamber 4 Second volume chamber 5 End plate 6 End plate 7 Inlet tube 8 Small hole 9 Sound absorption chamber 10 Tail tube 11 First pass tube 12 Third pass tube 13 Second pass tube 14 Valve 15 Clearance 16 Opening 17 Return spring 18 Shaft 19 Bracket 20 Seat surface 21 Buffer material 22 Branch pipe 23 Plug

Claims (7)

[Claims] An inlet tube for introducing exhaust gas from an engine and a tail tube for discharging exhaust gas to the atmosphere are respectively connected to an expansion chamber, and the expansion chamber is connected to a first volume chamber via a first pass tube. The first volume chamber communicates with a second volume chamber via a second pass tube, and the first volume chamber communicates with an expansion chamber via a third pass tube. An exhaust muffler for automobiles, characterized in that an end portion of the pass tube is provided with a valve that opens when the pressure inside the first pass tube or the third pass tube exceeds a predetermined pressure. 2. An inlet tube for introducing exhaust gas from the engine and a tail tube for discharging exhaust gas to the atmosphere communicate with an expansion chamber, and the expansion chamber communicates with a first volume chamber via a first pass tube. The first volume chamber and the second volume chamber communicate with each other via a second pass tube, the second volume chamber communicates with the expansion chamber via a third pass tube, and an end of the third pass tube. An exhaust muffler for an automobile, wherein the portion includes a valve that opens when the pressure in the third pass tube becomes equal to or higher than a predetermined pressure. 3. A first pass tube is formed integrally with the inlet tube, a plurality of small holes are formed in the inlet tube so as to communicate the inlet tube with an expansion chamber, and a valve is formed integrally with the inlet tube. When the pressure is set to the first pass tube, the pressure in the first pass tube is equal to or higher than the pressure in the first volume chamber, or when the valve is set to the third pass tube, 3. The vehicle according to claim 1, wherein an opening ratio of the plurality of small holes provided in the inlet tube to the expansion chamber is adjusted such that a pressure in the third pass tube is equal to or higher than the pressure in the expansion chamber. Exhaust silencer. 4. A gap is formed by partially overlapping or approaching the first path tube on the same axis with respect to the inlet tube to form a gap, and the inlet tube is configured to communicate with the expansion chamber through the gap. When the valve is set to the first pass tube, the pressure in the first pass tube is equal to or higher than the pressure in the first volume chamber, or when the valve is set to the third pass tube. 3. The exhaust muffler for a vehicle according to claim 1, wherein the gap is adjusted so that the pressure in the third pass tube is equal to or higher than the pressure in the expansion chamber. 5. A first pass tube is formed integrally with an inlet tube, a branch pipe is formed in the inlet tube so as to communicate the inlet tube with an expansion chamber, and the valve is set to the first pass tube. If the pressure in the first pass tube is equal to or higher than the pressure in the first volume chamber, or if the valve is set to the third pass tube, the pressure in the third pass tube is the The inner diameter of the branch pipe is adjusted to be equal to or higher than the expansion chamber pressure.
A vehicle exhaust silencer according to any of the preceding claims. 6. One end of the first pass tube or the third pass tube provided with the valve is open at a position of an end plate of the volume chamber or protruding into the volume chamber. 6. A vehicle exhaust silencer according to any one of claims 1 to 5. 7. The third pass tube is constituted by an opening provided in an end plate between the expansion chamber and the first volume chamber or the second volume chamber, and the pressure of the first volume chamber or the second volume chamber is reduced. 6. The vehicle exhaust silencer according to claim 1, further comprising a valve on the end plate for opening the opening when the pressure exceeds a predetermined level.