JPH07174012A - Noise eliminator for automobile - Google Patents

Abstract

PURPOSE:To improve sound absorbing effect without increasing the outside diameter dimention, in the case of an outer cylinder in which a sound absorbing material is filled and the cross sections are formed in non-circular shapes and the inner pipe which vertically passes through the outer cylinder, by mutually arranging them in the same direction as well as to form their cross sections in similar shapes. CONSTITUTION:A noise eliminator for an automobile, for example, a submuffler 2 is made up in a sound absorbing type, and front/back end parts of an inner pipe 7A having many panching holes 8 perforated thereto are respectively inserted and fixed to respective burring parts 5a, 6a of both outer plates attached to the both ends of an outer cylinder 4 whose cross section is formed in a non-circular shape. A stainless wool 9 and a glass wool 10 which ar respectively sound absorbing materials are filled between the outer cylinder 4 and an inner pipe 7A. Further, both exhaust pipes 11, 12 are respectively connected to both front/back ends of the submuffler 2. In this case, the outer cylinder 4 and the inner pipe 7A are mutually arranged in the same direction as well as to mutually form their cross sectional shapes in the similar figure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silencer for an automobile internal combustion engine.

[0002]

2. Description of the Related Art As shown in FIG. 4, an exhaust system of an internal combustion engine for an automobile has a catalytic converter 1, a sub muffler 2,
The main muffler 3 is connected and arranged under the floor of the automobile.

As the sub-muffler 2, a so-called sound absorbing silencer is used and has a structure shown in FIGS. 5 (a) and 5 (b). Because it is placed under the floor of the car, due to space constraints,
The outer shell 4 having an elliptic cylindrical shape has outer plates 5 and 6 attached to the front and rear ends thereof. These outer plates 5 and 6 are attached to the outer shell 4 by curling.

Further, circular burrings 5a and 6a are formed on the outer plates 5 and 6, respectively.
An end of a cylindrical inner pipe 7 is inserted and fixed inside 6a. Reference numeral 8 denotes a large number of small holes formed in the inner pipe 7, which are punched over the range indicated by reference numeral B. However, in the drawing, only two punching holes are shown and the other punching holes are omitted. .

Reference numeral 9 is stainless wool provided around the inner pipe 7, and 10 is glass wool filled in the space of the sub-muffler 2. These stainless wool 9 and glass wool 10 act as a sound absorbing material.

Reference numerals 11 and 12 denote exhaust pipes connected to the front part and the rear part of the sub muffler 2. The outer shell 4 is formed in an elliptic cylindrical shape in order to increase the sound absorbing effect by increasing the amount of the sound absorbing material, and because of space constraints, as shown in FIG. The major axis is defined horizontally and the minor axis is defined vertically (up and down).

[0007]

SUMMARY OF THE INVENTION In the above conventional technique,
Since the outer shell 4 has an elliptic cylindrical shape, the inner pipe 7 has a cylindrical shape, and the axes of the two are the same, the thickness of the sound absorbing material composed of the stainless wool 9 and the glass wool 10 is smaller than the outer shell 4 in the minor axis direction ( However, there is a problem in that the sound absorption volume is insufficient in the vertical direction) and the sound absorbing effect is insufficient to obtain a sufficient silencing effect.

[0008] Therefore, an object of the present invention is to provide a sound absorbing type muffler for automobiles which can solve the above problems.

[0009]

In order to achieve the above object, the first invention is a silencer in which the outer cylinder has a non-circular cross-sectional shape and the outer cylinder is filled with a sound absorbing material. 4) The inner pipe (7A, 7B) longitudinally passing through 4) and the outer cylinder (4) are formed so that the cross-sectional shape thereof is substantially similar to each other.
Moreover, the outer cylinder (4) and the inner pipes (7A, 7B) are arranged in substantially the same direction.

A second invention is the first invention, wherein the outer cylinder (4) is provided.
And the inner pipes (7A, 7B) are oval in cross-sectional shape. A third aspect of the invention is the first or second aspect of the invention, which is characterized in that the inner pipe (7B) has a non-circular cross-sectional shape in a part of the outer cylinder (4) in the longitudinal direction.

[0011]

The minimum thickness of the sound absorbing material can be increased because the cross section of the inner pipe has a short diameter in the short diameter direction (vertical direction) of the outer cylinder cross section. Therefore, the sound absorption volume can be increased without changing the external dimensions of the silencer.

[0012]

1 (a) and 1 (b) show a first embodiment of the present invention.
Reference numeral 4 is an elliptic cylinder-shaped outer cylinder having an elliptical cross section. Reference numerals 5 and 6 denote outer plates, and 7A denotes an inner pipe having a large number of punched holes 8, both ends of which are inserted and fixed in burring portions 5a and 6a of the outer plates 5 and 6, respectively.

The inner pipe 7A has an elliptic cylindrical shape, and the cross-sectional shape thereof is an elliptical shape which is substantially similar to that of the outer cylinder 4, and the inner pipe 7A is longitudinally arranged. The inner pipe 7A is the outer cylinder 4
Are arranged in the same direction as. That is, the major axis of the inner pipe 7A is arranged in the same horizontal direction as the major axis of the outer cylinder 4 (FIG. 1 (b)).

Reference numeral 9 is stainless wool provided around the inner pipe 7A, and 10 is outer cylinder 4 and stainless wool 9.
It is a glass wool filled between. Although many small holes 8 of the inner pipe 7A are opened in the range of the reference numeral B, only two are shown in the drawing and the others are omitted. Also, the burring 5 of the outer plates 5 and 6
The a and 6a are formed in an elliptical shape in accordance with the outer diameter of the inner pipe 7A.

Reference numerals 11 and 12 denote exhaust pipes connected to the front end and the rear end of the sub-muffler 2, respectively. The connecting portion to the sub-muffler 2 has a cross-sectional shape of the inner pipe 7.
The tapered portions 11a and 11b are formed in an elliptical shape in accordance with A and gradually become cylindrical as they are farther from the sub muffler 2.
Are formed.

FIG. 2 shows a second embodiment of the present invention, in which the inner pipe 7B has an elliptical cross section within a length L ₂ which is a part of the length L ₁ of the outer cylinder 4 in the longitudinal direction. Is different from the first embodiment. According to the second embodiment, the inner pipe 7B is provided over the range of the length L _2.
It is easy to make the elliptic cylinder shape with a large diameter.

When the length L ₂ is a non-circular section as in the second embodiment, the inner pipe 7B is of a so-called monaca type and press-molded as shown in FIGS. 3 (a) and 3 (b). If the upper portion 7a and the lower portion 7b are put together and welded to each other, they can be easily manufactured. If it is formed integrally from a pipe, there is a restriction from the expansion limit of the pipe, but if the non-circular cross section is made by monaque type press molding as shown in Fig. 3,
This is because there are no such restrictions. Further, the upper portion 7a and the lower portion 7b may be opened after the press working, or may be formed by pressing the opened plate.

If only the non-circular cross-section portion is formed separately and welded to a pipe having a circular cross-section, the cross-sectional area of the non-circular cross-section portion can be set large. Further, the non-circular cross section may be formed by winding a plate material. The cross-sectional shape of the inner pipe and the cross-sectional shape of the outer cylinder are not limited to ellipses, and may be any cross-sectional shape such as an oval cross section or a triangular cross section.

[0019]

Since the muffler of the present invention is constructed as described above, the minimum thickness of the sound absorbing material can be increased without changing the outer dimensions of the muffler, and the muffling effect is improved. Moreover, since the cross-sectional area of the flow passage in the cross section of the inner pipe can be increased, the sound deadening effect can be improved and the back pressure can be reduced.

[Brief description of drawings]

FIG. 1 is a first embodiment of the present invention, (a) is a vertical plan view,
(B) is a horizontal cross-sectional view of the AA cross-sectional view of FIG.

FIG. 2 is a schematic diagram of a second embodiment of the present invention.

FIG. 3 is a diagram of an inner pipe of a third embodiment of the present invention,
(A) is a perspective view and (b) is a cross-sectional view.

FIG. 4 is a plan view showing an arrangement of silencers in an exhaust system of an automobile.

FIG. 5 is a conventional silencer, (a) is a vertical plan view,
(B) is a cross-sectional view taken along the line A-A of FIG.

[Explanation of symbols]

 2 Sub muffler (silencer) 4 Outer cylinder 7A, 7B Inner pipe 9 Stainless wool (sound absorbing material) 10 Glass wool (sound absorbing material)

Claims (3)

[Claims] 1. In a muffler having a non-circular cross section of an outer cylinder and a sound absorbing material filled in the outer cylinder, a cross section of an inner pipe extending vertically through the outer cylinder and a cross section of the outer cylinder are alternate with each other. A muffler for an automobile, characterized in that the outer cylinder and the inner pipe are arranged in substantially the same shape, and the outer cylinder and the inner pipe are arranged in substantially the same direction. 2. The silencer for an automobile according to claim 1, wherein the outer cylinder and the inner pipe have an elliptical cross-sectional shape. 3. The silencer for an automobile according to claim 1, wherein a cross section of the inner pipe is a non-circular shape in a part of the outer cylinder in the vertical direction.