CA2028349A1

CA2028349A1 - Support structure for engine mufflers

Info

Publication number: CA2028349A1
Application number: CA002028349A
Authority: CA
Inventors: Toyoaki Shimizu
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 1989-10-24
Filing date: 1990-10-23
Publication date: 1991-04-25
Also published as: DE4033858A1; DE4033858C2; GB2237327A; GB9023152D0

Abstract

ABSTRACT OF THE DISCLOSURE

A support structure supports an engine muffler on an automotive body, the engine muffler including a muffler case of a resin with a single metallic exhaust pipe extend-ing therethrough. The support structure includes attachment supports mounted on the exhaust pipe near the muffler case.

Description

SUPPORT STR~CTURE FOR ENGINE MUFFLERS

BACKGROUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to a structure for supporting an engine muffler, and more particularly to a structure for supporting an automotive engine muffler having a muffler case of resin, on an automotive body.

2. Description of the Relevant Art:
U.S. Patent No. 4,589,516 discloses a muffler for internal combustion engines. The disclosed muffler has an outer box or case made of resin in order to reduce the weight of the muffler. As with ordinary mufflers of metal, the disclosed muffler case is intended to be supported on an automotive body.
The muffler case is relatively complex in shape since it has an attachment member to be fastened to the automotive body. Therefore, the process of molding the muf-fler case to desired shape is complex and the muffler case ls expensive to manufacture.
The present inventlon has been made in an effort to effectlvely solve the aforesaid problems of the conventional support structure for engine mufflers.
SUMMARY OF THE INVENTION
It is an ob;ect of the present invention to provide a support structure for engine mufflers, which can be manu-~= .

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factured by a relatively simple process and hence ls lesscostly to manufacture.
To achieve the above ob;ect, there is provided in accordance with the present invention a support structure for supporting an engine muffler on an automotive body, the engine muffler including a muffler case of a resin having an inner layer of a sound-absorbing insulation material and a single metallic exhaust pipe extending through the muffler case, the support structure comprising attachment supports adapted to be attached to the automotive body, the attach-ment supports being mounted on the exhaust pipe near the muffler case.
The above and further ob;ects, details and advan-tages of the present invention will become apparent from the following detailed description of a preferred embodiment thereof, when read in con~unction with the accompanying drawlngs.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view, partly in cross section, of a support structure for an engine muffler according to a preferred embodiment of the present invention;
FIG. 2 is a cross-sectional view taken along line II - II of FIG. l;
: FIG. 3 ls a cross-sectional view taken along line III - III of FIG. l;
FIG. 4 is an enlarged cross-sectional view of an enclrcled portion lndicated by IV in FIG. l;
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FIG. 5 is an enlarged cross-sectlonal vlew of an enclrcled portion indlcated by V in FIG. 2; and FIG. 6 is an enlarged cross-sectional view of an encircled portion indicated by vI in FIG. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1 through 3 show ln cross sectlon a support structure 100 for an engine muffler according to a preferred embodiment of the present invention.
The engine muffler, generally denoted at 3, is con-nected to an exhaust pipe 1 coupled to an internal combus-tion engine (not shown). The engine muffler 3 has an inner layer 4 of a sound-absorbing insulation material disposed in a muffler case s, the inner layer 4 being attached to the inner surface of the muffler case 5.
The exhaust pipe 1 comprises a front pipe member 11 whose upstream end is connected to the engine, a tail pipe member 12 whose downstream end is vented to atmosphere, and an intermediate pipe member 13 positioned between and inter-connecting the front and tail pipe members 11, 12 and located within the muffler 3. The pipe members 11, 12, 13 are made of a metallic material such as an iron-base material. The exhaust pipe 1 composed of the pipe members 11, 12, 13 which are ~oined together is in the form of a single unitary continuous pipe of a bent shape.
The sound-absorbing insulation material of the inner layer 4 may be glass wool, for example. The inner ~ .. ~. .. ~.. ...

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layer 4 is divided into upper and lower layer members 41, 45.
The muffler case 5 comprlses a pair of ~olned upper and lower halves 51, 55 each made of hard resin, and is in the form of a box which has a relatively small thickness in the vertical direction as compared with its transverse and longitudinal dimensions. With the upper and lower halves 51, 55 joined together, the upper and lower layer members 41, 45 bonded to their inner surfaces have confronting inner surfaces jointly defining three sound-absorbing resonant chambers A, B, C which are successively positioned in the muffler 3. The intermediate pipe member 13 of the exhaust pipe 1 extends successively through the sound-absorbing res-onant chambers A, B, C and has groups of holes a, b, c defined therein which are positioned respectively in these chambers A, B, C.
Outer tubes 2 of an iron-base metallic material are ~oined at their ends to the intermediate pipe 13 at the downstream end of the front pipe member 11 and the upstream end of the tail pipe member 12, respectively. The outer tubes 2 extend toward and into the muffler case 5. More specifically, as shown in FIGS. 3 and 4, the outer tubes 2 have smaller-diameter ends 21 fitted over the intermediate pipe member 13 respectively at the downstream end of the front pipe member 11 and the upstream end of the tail pipe member 12. The outer tubes 2 also have opposite open ends ~,~, - .
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22 extending into the muffler case 5 and grlpped by corre-sponding portions of the upper and lower case halves 51, 55.
Flanges 23 of an iron-base metallic material are securely fitted respectively over the open ends 22 of the outer tubes 2. The upper and lower layer members 41, 45 include contlnuous extensions 42, 46 which are stuffed in the outer tubes 2.
AS shown in FIG. 5, when the muffler case 5 is assembled, peripheral edges 52, 56 of the respective upper and lower case halves 51, 55 are first superposed on each other with the upper and lower layer members 41, 45 posi-tioned inside in sandwiching relation to the intermediate pipe member 13. The mating surfaces of the peripheral edges 52, 56 are bonded to each other by adhesive layers 6 which have been applied in advance. Then, a side sealing strip 7 which is molded of a resin is fitted over the bonded periph-eral edges 52, 56 SO as to extend therealong. Thereafter, as shown in FIG. 6, the outer tubes 2 are fitted over the continuous extensions 42, 26 pro~ecting out of the muffler case 5. The outer tubes 2 are pushed into the muffler case 5 until flanges 23 flxedly mounted on the outer tubes 2 abut against end flanges 53, 57 of the upper and lower case halves 51, 55. The flanges 53, 57 and the flanges 23 are bonded to each other by adheslve layers 8 which have been applied to the mating surfaces of the these flanges 53, 57, 23 in advance. Finally, sealing rings 9 which are molded of , ~

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a resin are fitted over the entire perlpheral edges of the flanges 53, 57, 23. Now, the muffler case 5 is completely assembled. The intermediate pipe member 13 is of a bent configuration such that upstream and downstream ends 13a, 13b of the intermediate pipe member 13, whlch are supported by the muffler case 5, are positioned out of coaxial align-ment with each other, or are offset from each other.
As shown in FIG. 4, each of the outer tubes 2 pro-jects from the muffler case 5 by a length ~.
In order to attach the muffler 3 to an automotive body (not shown)~ the support structure 100 includes attach-ment supports 14, 15 in the form of brackets which are mounted on the front and tail pipe members 11, 12 near the muffler case 5, as shown in FIG. 1.
The attachment supports 14, 15 of the support structure 100 for attachment to the automotive body are mounted on the metallic exhaust pipe 1 near the muffler case 5, the exhaust pipe 1 being in the form of a single pipe extending through the muffler case 5 of resin. Since the muffler case 5 ltself does not have any attachment supports to be attached to the automotive body, the muffler case 5 is of a relatively simple shape, can be manufactured by a sim-ple process, and is inexpensive to manufacture.
With the support structure 100, the muffler case 5 which is relatively light in weight is supported by the exhaust pipe 1 which is of relatively high strength.

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Therefore, any stresses applled to the muffler case 5 at its regions which are ~oined to the exhaust pipe 1 are greatly reduced. As a result, the muffler case 5 is highly durable in use. Since the portions of the exhaust pipe 1 which are joined to the muffler case 5, i.e., the upstream end 13a and the downstream end 13b of the intermediate pipe member 13 are held out of coaxial alignment with each other, the muffler case 5 is substantially not sub;ect to circu-mferential moments at the ends 13a, 13b of the intermediate pipe member 13. The bent configuration of the intermediate pipe member 13 is therefore effective to make the construc-tion by which the muffler case 5 is attached to the exhaust pipe 1, more reliable and durable, and also to increase the durability of the muffler case 5 itself. If the muffler case 5 of resin itself were attached directly to the automo-tive body and the metallic exhaust pipe 1 were supported by the muffler case 5, then the weight of the exhaust pipe 1 would be applied to the muffler case 5, and the muffler case S would be sub~ect to much larger stresses.
The exhaust pipe 1 also serves as a reinforcing member for the muffler case 5.
In the regions where the muffler case 5 is sup-ported on the exhaust pipe 1, the exhaust pipe 1 is of a double-walled construction due to the metallic outer tubes 2 which are positioned in and near the junctions between the muffler case 5 and the exhaust pipe 1. Fhe double-walled . : -J ~ ~ ~, ,? ~

construction provides a thermal insulation structure in which the ends of the muffler case 5 are joined to the outer circumferential surfaces of the outer tubes 2 by the flanges 53, 57, 23 and the layer extensions 42, 46 of sound-absorbing insulation material are filled between the outer circumferential surface of the exhaust pipe 1 and the inner circumferential surfaces of the outer tubes 2. The thermal insulation extensions 42, 46, which are positioned within the outer tubes 2 and extend over the length ~ by which the outer tubes 2 project from the muffler case 5, prevent the heat from being transmitted from the outer circumferential surface of the exhaust pipe 1 to the muffler case 5. The heat which is radiated from the exhaust pipe 1 through the outer tubes 2 toward the muffler case 5 is dissipated by the thermal insulation extensions 42, 46 and the outer tubes 2 over the length ~. Consequently, the temperature of the portions of the muffler case 5 which are held in contact with the outer tubes 2 is maintained at an allowable temper-atùre level. The length ~ by which the outer tubes 2 pro-~ect from the muffler case 5 and the thickness of the thermal insulation extensions 42, 46 may be adjusted suita-bly as desired. The area through which the flanges 23 of the outer tubes 2 and the flanges 53, 57 of the muffler case 5 are ~oined to each other is greater than the area through which the exhaust pipe 1 would be joined to the case halves 51, 55 if the exhaust pipe 1 were simply gripped between the ,~. , , ~J ~ J 3 'L ~

case halves 51, 55. Therefore, the exhaust pipe 1 and the muffler case 5 are jolned to each other through a secure joint structure.
Instead of the continuous thermal insulation exten-sions 42, 46 of the layers 41, 45, thermal insulation layers other than or separate from the thermal insulation layers 41, 45 may be stuffed in the outer tubes 2.
Although there has been described what is at pre-sent considered to be the preferred embodiment of the pre-sent invention, it will be understood that the invention may be embodied in other specific forms without departing from the essential characteristics thereof. The present embodi-ment is therefore to be considered in all aspects as illustrative, and not restrictive. The scope of the inven-tion is indicated by the appended claims rather than by tne foregoing description.

Claims

1. A support structure for supporting an engine muffler on an automotive body, the engine muffler including a muffler case of a resin having an inner layer of a sound-absorbing insulation material and a single metallic exhaust pipe extending through the muffler case, said support struc-ture comprising:
attachment supports adapted to be attached to the automotive body, said attachment supports being mounted on the exhaust pipe near the muffler case.

2. A support structure according to claim 1, fur-ther including metallic outer tubes mounted on said exhaust pipe near portions thereof which are joined to said muffler case, and layers of a thermal insulation material stuffed between inner circumferential surfaces of said outer tubes and outer circumferential surfaces of said exhaust pipe, said muffler case having ends connected to the outer cir-cumferential surfaces of said outer tubes.

3. A support structure according to claim 1, wherein said exhaust pipe has upstream and downstream por-tlons which are joined to said muffler case, said upstream and downstream portions being held out of coaxial alignment with each other.