JP2008138608A - Vehicular muffler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular muffler capable of providing an excellent muffling effect close to that in arranging a silencer at an antinode position of a standing wave even when the silencer is arranged at a position deflected to the upstream or downstream side of an exhaust pipe from the antinode position of the standing wave on the exhaust pipe. <P>SOLUTION: The silencer 6 is arranged at a position deflected along the longitudinal direction of the exhaust pipe 3 from an antinode position P of a standing wave W generated in the exhaust pipe 3, and a group of small holes 21 is bored on an inner pipe 10 of the silencer 6 by being unevenly distributed closer to the antinode position P. Thereby, this vehicular muffler is structured as if a large-diameter virtual silencer 6' having a large-volume expansion chamber 11' around it were present around the group of small holes 21. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention comprises a silencer in the middle of the exhaust pipe from the exhaust manifold of the exhaust manifold of the vehicle engine to the atmosphere opening, and the silencer intervenes in the middle of the exhaust pipe, A housing for housing the inner cylinder and defining an expansion chamber there between, wherein the inner cylinder is provided with a small hole group communicating with the expansion chamber. Regarding improvement.

The exhaust noise of an engine mounted on a vehicle such as an automobile includes a mixture of explosion sounds in the engine cylinder, sound of the air flow caused by the flow of exhaust gas, standing waves in the exhaust pipe, and the like. In particular, standing waves cause air column resonance to increase sound pressure level and worsen exhaust noise when exhaust pulsation and frequency are matched in a specific engine speed range. In order to suppress such air column resonance, it is known that it is effective to provide a silencer at the antinode position (position where the amplitude is maximum) of the standing wave in the exhaust pipe (see Patent Document 1). .
Japanese Patent Publication No. 1-25242

  By the way, not only an exhaust system including an exhaust pipe and a silencer but also many components such as a fuel tank, a cross member, and a side member are arranged under the floor of the vehicle. Due to the restrictions imposed by the parts, the silencer may have to be placed on the exhaust pipe at a position deviated upstream or downstream from the antinode position of the standing wave.

  The present invention has been made in view of such circumstances. Even if a silencer is arranged on the exhaust pipe at a position shifted from the antinode position of the standing wave to the upstream side or the downstream side of the exhaust pipe, It is an object of the present invention to provide an exhaust silencer for a vehicle that can obtain a good silencing effect close to that when a silencer is arranged at the antinode position of the standing wave.

  In order to achieve the above object, according to the present invention, a silencer is provided at an intermediate portion of an exhaust pipe from an exhaust manifold of an exhaust manifold of a vehicle engine to an atmosphere opening, and the silencer is connected to the exhaust pipe. An inner cylinder that intervenes in the middle and a housing that accommodates the inner cylinder and defines an expansion chamber therebetween, and the inner cylinder is provided with a small hole group that communicates the inside with the expansion chamber Further, in the exhaust silencer for a vehicle, the silencer is disposed at a position displaced along the longitudinal direction of the exhaust pipe from the antinode position of the standing wave generated in the exhaust pipe, while the small hole group is disposed on the inner cylinder. It is a first feature that is unevenly distributed near the abdominal position.

  According to the present invention, in addition to the first feature, a partition tube for partitioning the expansion chamber into an inner expansion chamber on a radially inner side and an outer expansion chamber on a radially outer side is disposed in the housing. Secondly, the outer expansion chamber is filled with a sound absorbing material, and the partition tube is provided with a small hole group that communicates between the inner expansion chamber and the outer expansion chamber over substantially the entire length thereof. And

  The silencer corresponds to the pre-muffler 6 in the embodiment of the present invention described later.

  According to the first feature of the present invention, the silencer is disposed at a position displaced along the longitudinal direction of the exhaust pipe from the antinode position of the standing wave generated in the exhaust pipe, while being small on the inner cylinder of the silencer. Since the hole group is unevenly distributed closer to the abdominal position, there is a large-diameter virtual silencer having a large-capacity virtual expansion chamber around the small hole group. This large-diameter virtual silencer is close to the abdominal position by the distance that the small hole group is close to the abdominal position. Therefore, the high sound pressure at the abdominal position of the standing wave is It is attenuated by pressure drop due to expansion, and exhaust noise caused by standing waves can be effectively silenced.

  According to the second feature of the present invention, even if the small hole group of the inner cylinder is unevenly distributed, after the high sound pressure of the exhaust gas that has passed through the small hole group is distributed to the entire inner expansion chamber, it is applied to the substantially entire partition cylinder. The entire outer expansion chamber can be spread through the small group of holes, and can be applied to the entire sound absorbing material of the outer expansion chamber. Therefore, the high sound pressure can be effectively attenuated by using the entire sound absorbing material.

  Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

  FIG. 1 is a side view showing a relationship between an exhaust system of an engine equipped with an exhaust silencer of the present invention, an automobile body and a standing wave, and FIG. 2 is an enlarged longitudinal sectional view of a pre-muffler in the exhaust silencer, FIG. 3 is an enlarged view of part 3 of FIG. 2, and FIG. 4 is an enlarged sectional view taken along line 4-4 of FIG.

  First, in FIG. 1, an exhaust manifold 1 is attached to a multi-cylinder engine E mounted in an engine room at the front of an automobile body B, and an exhaust pipe 3 extending from an exhaust collecting portion 1 a of the exhaust manifold 1 to an atmosphere opening 2. Is arranged under the floor of the automobile body B.

  The exhaust pipe 3 is provided with a catalytic converter 5, a pre-muffler 6 and a main muffler 7 in order from the upstream side thereof, that is, from the engine E side. In the illustrated example, the pre-muffler 6 is preferably disposed at the antinode position P of the standing wave W in order to reduce the exhaust noise caused by the standing wave W generated inside the exhaust pipe 3. In order to avoid interference with other adjacent parts, it is unavoidable to be arranged at a position deviated from the anti-node position P by a certain distance L along the longitudinal direction of the exhaust pipe 3 upstream or downstream.

  Even in such a disadvantageous arrangement of the pre-muffler 6, the present invention arranges the pre-muffler 6 at the antinode position P of the standing wave W by improving the internal structure of the pre-muffler 6. An improved structure of the pre-muffler 6 will be described below, in which a silencing effect that is as close as possible to a good silencing effect is obtained.

  As shown in FIGS. 2 to 4, the pre-muffler 6 intervenes in the middle of the exhaust pipe 3 and divides it into an upstream exhaust pipe 3a on the exhaust manifold 1 side and a downstream exhaust pipe 3b on the atmosphere opening 2 side. And an inner cylinder 10 that houses the inner cylinder 10 and a housing 12 that defines an expansion chamber 11 therebetween. The housing 12 is configured in a sealed manner by an outer cylinder 13 that surrounds the inner cylinder 10 substantially concentrically and a pair of annular end plates 14 and 14 that are caulked and coupled to both ends of the outer cylinder 13. These end plates 14 and 14 have bosses 14a and 14a fitted to outer peripheral surfaces of both ends of the inner cylinder 10, and these bosses 14a and 14a and both ends of the inner cylinder 10 are connected to the upstream exhaust pipe 3a and The downstream exhaust pipe 3 b is fitted to the outer peripheral surfaces of the opposing ends and is airtightly connected by the annular welded portion 15. Thus, the upstream exhaust pipe 3a and the downstream exhaust pipe 3b are communicated with each other via the inner cylinder 10.

  In the housing 12, a partition cylinder 17 is provided that divides the expansion chamber 11 into an inner expansion chamber 11a on the radially inner side and an outer expansion chamber 11b on the radially outer side. The partition cylinder 17 is connected to a cylindrical body 18 that surrounds the inner cylinder 10 substantially concentrically and has both ends close to the end plates 14, 14 of the housing 12. The end walls 19, 19 are connected to the outer peripheral surface of the inner cylinder 10 through the welded portion 20. The bosses 19 a, 19 a formed on the inner peripheral ends of the end walls 19, 19 Is done.

  The inner cylinder 10 is provided with a large number of small holes 21, 21... That communicate with the inner expansion chamber 11 a. In this case, the small holes 21, 21... Are provided in an axial region A that extends over substantially the entire circumference of the inner cylinder 10 and is shorter than ½ of the entire length of the inner cylinder 10, and the small holes 21, 21. The group region A is arranged so as to be unevenly distributed on the antinode position P side from the axial center point of the inner cylinder 10.

  The cylindrical body 18 of the partition cylinder 17 is provided with a large number of small holes 22, 22... Communicating between the inner expansion chamber 11a and the outer expansion chamber 11b over substantially the entire circumference and the entire length.

  As described above, the inner cylinder 10 having the small holes 21, 21... And the cylindrical body 18 of the partition cylinder 17 having the small holes 22, 22. It is manufactured by rounding the punching plate into a cylindrical shape and butting both ends. In this case, it is desirable not to drill small holes 21 and 22 in the vicinity of the end portion where butt welding is performed in order to ensure welding strength.

  The outer expansion chamber 11b is filled with a sound absorbing material 23. In the illustrated example, the sound absorbing material 23 includes a first glass wool layer 23a having a particularly high heat resistance, and a second glass wool layer 23b surrounding the first glass wool layer 23a, which has a lower heat resistance but is less expensive. . With such a configuration, it is possible to obtain the sound absorbing material 23 that satisfies not only the sound absorbing property but also the heat resistance and cost.

  In order to prevent the sound absorbing material 23 from being drawn into the inner expansion chamber 11a from the small holes 22, 22..., A filter material 24 having high heat resistance, such as stainless wool, is collectively provided on the outer peripheral surface of the inner cylinder. .

  Next, the operation of this embodiment will be described.

  During operation of the engine E, exhaust gas discharged from the engine E is led to the exhaust pipe 3 through the exhaust manifold 1, and after the harmful components such as HC, CO and NOx are first removed by the catalytic converter 5, the pre-muffler 6 and the main muffler 7 are passed through in sequence and muffled and released to the atmosphere.

  By the way, the pre-muffler 6 cannot be stopped due to the above-described reason, and the pre-muffler 6 is displaced from the antinode position P of the standing wave W generated in the exhaust pipe 3 to the upstream or downstream side of the exhaust pipe 3 by a certain distance L. 2 is arranged so that the small holes 21, 21... Group of the inner cylinder 10 of the pre-muffler 6 are unevenly distributed on the abdominal position P side from the axial center point of the inner cylinder 10. As indicated by the chain line, there is a large-diameter virtual pre-muffler 6 ′ having a large-capacity virtual expansion chamber 11 ′ around the small holes 21, 21,. Therefore, the large-diameter virtual pre-muffler 6 'is close to the antinode position P by the distance that the small holes 21, 21, ... are close to the antinode position P. The high sound pressure at the antinode position P of the standing wave W is caused by the pressure drop due to the expansion in the expansion chamber 11 and the expansion chamber 1. And interference of the exhaust sound waves in, attenuated by the sound absorbing effect of the sound absorbing material 23, it is possible to mute the exhaust noise caused by the standing wave W effectively.

  In addition, the expansion chamber 11 is divided into an inner expansion chamber 11 a and an outer expansion chamber 11 b by a partition tube 17, and a plurality of small holes 22, 22... Communicating between the chambers 11 a, 11 b are cylindrical bodies of the partition tube 17. 18 is provided over almost the whole, and the outer expansion chamber 11b is filled with the sound absorbing material 23. Therefore, even though the small holes 21, 21... After the high sound pressure of the exhaust gas is distributed over the entire inner expansion chamber 11a, it is distributed over the entire outer expansion chamber 11b through the numerous small holes 22, 22. The high sound pressure can be effectively attenuated using the entire material 23.

  The present invention is not limited to the above embodiment, and various design changes can be made without departing from the scope of the invention. For example, the inner cylinder 10 of the pre-muffler 6 can be integrally formed continuously with the exhaust pipe 3.

The side view which shows the relationship between the exhaust system of an engine provided with the exhaust silencer of this invention, a motor vehicle body, and a standing wave The expanded longitudinal cross-sectional view of the pre muffler in the said exhaust silencer. 3 is an enlarged view of part 3 of FIG. FIG. 4 is an enlarged sectional view taken along line 4-4 of FIG.

Explanation of symbols

E ... Engine 1 ... Exhaust manifold 1a ... Exhaust collecting part 2 ... Air opening 3 ... Exhaust pipe 6 ... Silencer (pre-muffler)
6 '... virtual silencer (virtual pre-muffler)
DESCRIPTION OF SYMBOLS 10 ... Inner cylinder 11 ... Expansion chamber 11 '... Virtual expansion chamber 11a ... Inner expansion chamber 11b ... Outer expansion chamber 12 ... Housing 17 ... Partition cylinder 21 ... Small inner cylinder Hole 22 ... A small hole in the partition tube

Claims (2)

A silencer (6) is provided in the middle of the exhaust pipe (3) from the exhaust collecting part (1a) of the exhaust manifold (1) of the vehicle engine (E) to the atmosphere opening (2). (6) is an inner cylinder (10) intervening in the middle of the exhaust pipe (3), and a housing (12) that accommodates the inner cylinder (10) and defines an expansion chamber (11) therebetween In the exhaust silencer for a vehicle, the inner cylinder (10) is provided with a group of small holes (21, 21,...) Communicating with the expansion chamber (11).
The silencer (6) is disposed at a position displaced along the longitudinal direction of the exhaust pipe (3) from the antinode position (P) of the standing wave (W) generated in the exhaust pipe (3). An exhaust silencer for a vehicle, wherein the small holes (21, 21 ...) are unevenly distributed closer to the antinode position (P) on the cylinder (10). The exhaust silencer for a vehicle according to claim 1,
A partition tube (17) that divides the expansion chamber (11) into an inner expansion chamber (11a) radially inward and an outer expansion chamber (11b) radially outward in the housing (12). The outer expansion chamber (11b) is filled with a sound absorbing material (23) and the partition tube (17) is filled with the inner expansion chamber (11a) and the outer expansion chamber (11b) over substantially the entire length thereof. A small exhaust (22, 22...) Group communicating with each other is provided.

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