JP3868583B2 - Vehicle silencer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle silencer interposed in an exhaust system passage of a vehicle engine.
[0002]
[Prior art]
Conventionally, as shown in FIG. 1, it is known that a pre-chamber 3 as a sub silencer is provided in the exhaust system path 1 of the engine so as to be located upstream of the main silencer 2.
[0003]
The pre-chamber 3 generally has a sound absorbing shape in which a shell 30 having a circular cross section or an oval cross section is passed through an inner pipe 31 having a through hole in a peripheral wall portion, and a sound absorbing material is filled between the shell 30 and the inner pipe 31. It consists of a silencer. The inner pipe 31 is disposed concentrically with the shell 30.
[0004]
As shown in FIG. 2, the pre-chamber 3 is disposed between a step 4a formed on the floor 4 and a rear subframe 6 on which a fuel tank 5 and a rear suspension (not shown) are mounted. Here, in terms of the exhaust system, as shown in FIG. 1, the exhaust pipe 1b on the downstream side is offset to one side in the vehicle width direction with respect to the exhaust pipe 1a on the upstream side of the pre-chamber 3. The axis of the inner pipe 31 of the pre-chamber 3 connecting the pipes 1a and 1b is inclined in the vehicle width direction. And conventionally, since the shell 30 and the inner pipe 31 of the pre-chamber 3 are concentrically arranged, the axis of the shell 30 is also inclined in the vehicle width direction.
[0005]
[Problems to be solved by the invention]
It is necessary to secure clearance between the pre-chamber 3 and the floor step portion 4a and between the pre-chamber 3 and the rear sub frame 6 to prevent interference. It is necessary to store the prechamber 3 in the space of the distance L excluding the clearance.
[0006]
Here, when the axis of the shell 30 is inclined in the vehicle width direction as in the above-described conventional example, the axial length L ′ of the shell 30 is made shorter than L and the lateral width is increased in order to fit the shell 30 in the space of the distance L. Accordingly, the axial length L ′ needs to be shortened, and it becomes difficult to increase the volume of the shell 30.
[0007]
In view of the above points, an object of the present invention is to provide a vehicle silencer capable of improving the silencing performance by increasing the volume of the shell.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, in the present invention, an upstream side exhaust pipe and a downstream side exhaust pipe, which are disposed between a stepped portion formed on a floor panel and a rear subframe behind the stepped part, are offset in the vehicle width direction. A vehicle silencer to be connected , comprising a shell and an inner pipe that penetrates the shell and has a through hole in a peripheral wall portion, and an upstream exhaust pipe and a downstream exhaust pipe are connected to both ends of the inner pipe. In the one, the inner pipe is arranged so that the axis of the inner pipe is inclined with respect to the axis of the shell over the entire length in correspondence with the offset amount in the vehicle width direction of the upstream side exhaust pipe and the downstream side exhaust pipe . The axis of the shell is made parallel to the vehicle length direction, and the axis of the inner pipe is aligned with the axes of the upstream and downstream exhaust pipes at the connecting portions at both ends of the inner pipe .
[0009]
According to this, when the exhaust pipe on the upstream side and the exhaust pipe on the downstream side of the silencer are offset in the vehicle width direction, the silencer is made to correspond to the offset in the vehicle width direction of both exhaust pipes, and the inner When the pipe axis is inclined in the vehicle width direction, the shell axis can be parallel to the vehicle length direction. Therefore, the axial length of the shell can be made equal to the distance in the vehicle length direction of the silencer arrangement space, and the lateral width of the shell can be increased, and the volume of the shell is increased as much as possible to improve the silencing performance. be able to.
[0010]
Although a sound absorbing material may be filled between the shell and the inner pipe, an outer pipe that surrounds the inner pipe in a space is provided in the shell, and a through hole is formed in the peripheral wall portion of the outer pipe. If the sound absorbing material is filled between the shell and the outer pipe, in addition to the sound absorbing effect by the sound absorbing material, the expansion noise reducing effect by the space between the outer pipe and the inner pipe can be obtained, so that the sound deadening performance is improved. In this case, if the outer pipe is arranged substantially concentrically with the shell, it is advantageous that the cross-sectional area of the outer pipe can be increased to enhance the expansion and silencing effect.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 3 shows an exhaust system of an engine mounted on a vehicle. The basic structure is not particularly different from that of the conventional exhaust system shown in FIG. Yes.
[0012]
Referring to FIG. 4, the arrangement space of pre-chamber 3 as a sub silencer is a space between floor step portion 4a and rear sub frame 6 as in the prior art. As shown in FIGS. 5 and 6, the pre-chamber 3 surrounds the inner pipe 31 provided in the shell 30 with a space, with the shell 30 having an oval cross section, the inner pipe 31 penetrating the shell 30. An outer pipe 32 is provided, and an upstream exhaust pipe 1a and a downstream exhaust pipe 1b are connected to a front end and a rear end of the inner pipe 31, respectively.
[0013]
The inner pipe 31 is disposed such that its axis is inclined with respect to the axis of the shell 30. When the pre-chamber 3 is arranged so that the axis of the inner pipe 31 is inclined in the vehicle width direction so as to correspond to the offset in the vehicle width direction of the downstream exhaust pipe 1b with respect to the upstream exhaust pipe 1a, The axis is parallel to the vehicle length direction. Therefore, in the space between the floor step portion 4a and the rear subframe 6, the shell length is set such that the predetermined vehicle length direction distance L in which the pre-chamber 3 is to be accommodated, excluding the clearance for preventing interference, is equal to the axial length. 30 and the width of the shell 30 can be increased. Thus, the volume of the shell 30 can be increased as much as possible to improve the silencing performance.
[0014]
Further, the inner pipe 31 is disposed so as to be offset downward from the cross-sectional center of the shell 30. Therefore, a wide cross-sectional area of the shell 30 can be secured above the inner pipe 31, and the volume of the shell 30 can be increased without reducing the minimum ground clearance.
[0015]
A large number of through holes 31a and 32a are formed in the peripheral wall portions of the inner pipe 31 and the outer pipe 32, respectively. A stainless steel wool 33 as a first sound absorbing material is wound around the outer periphery of the outer pipe 32 and a silica mat 34 as a second sound absorbing material is wound around the outer periphery of the outer pipe 32, and a third portion is interposed between the silica mat 34 and the shell 30. Glass wool 35 as a sound absorbing material is filled. Further, the outer pipe 32 is arranged substantially concentrically with the shell 30 so as to have a large cross-sectional area.
[0016]
As the pre-chamber 3, the inventive product of the above embodiment and a comparative product in which the outer pipe 32 is omitted and a sound absorbing material is filled between the inner pipe 31 and the shell 30 are used. When the noise during acceleration was measured, the result shown in FIG. 7 was obtained. In FIG. 7, a1 and c1 indicate the noise levels of the A characteristic and C characteristic when the inventive product is used as the pre-chamber 3, and a2 and c2 indicate the A and C characteristics when the comparative product is used as the pre-chamber 3. Indicates the noise level. As is clear from the figure, the silencer performance of the invention product is improved. This is because in the case of the invention, in addition to the sound absorbing effect by the sound absorbing material, the expansion and silencing effect by the space between the inner pipe 31 and the outer pipe 32 is obtained.
[0017]
Although the embodiment in which the present invention is applied to the pre-chamber 3 has been described above, the present invention can be similarly applied to other silencers interposed in the exhaust system passage of the engine.
[0018]
【The invention's effect】
As apparent from the above description, according to the first and second aspects of the invention, the volume of the shell can be increased as much as possible, and the sound deadening performance can be improved. As a result, the silencing performance can be further improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a layout of a conventional exhaust system. FIG. 2 is a side view showing an arrangement portion of a pre-chamber of the exhaust system of FIG. 1. FIG. 3 shows a layout of an exhaust system having a pre-chamber to which the present invention is applied. FIG. 4 is a side view showing an arrangement part of the prechamber of the exhaust system of FIG. 3. FIG. 5 is a cross-sectional view taken along line VV in FIG. 4. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. ] Graph showing the measurement results of exhaust noise [Explanation of symbols]
1 Exhaust system passage 3 Pre-chamber (silencer)
30 Shell 31 Inner pipe 32 Outer pipe 31a, 32a Through hole 33, 34, 35 Sound absorbing material

Claims (2)

A muffler for a vehicle that is disposed between a stepped portion formed on a floor panel and a rear subframe behind the stepped portion and connects an upstream exhaust pipe and a downstream exhaust pipe that are offset in the vehicle width direction ,
A shell and an inner pipe that penetrates the shell and has a through-hole in the peripheral wall portion, and an upstream exhaust pipe and a downstream exhaust pipe are connected to both ends of the inner pipe ,
So as to correspond to the offset amount of the vehicle width direction of the upstream side exhaust pipe and downstream exhaust pipe, by arranging such that the axis line of the inner pipe is inclined with respect to the axis of the shell over the inner pipe its entire length, the axis of the shell To be parallel to the vehicle length direction,
The vehicle silencer is characterized in that the axis of the inner pipe coincides with the axis of the upstream and downstream exhaust pipes at the connecting portions at both ends of the inner pipe . The outer pipe that surrounds the inner pipe in a space in the shell is arranged almost concentrically with the shell, and a through hole is formed in the outer wall of the outer pipe, and a sound absorbing material is filled between the shell and the outer pipe. the vehicle muffler according to claim 1, wherein the.

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