JP2005256754A - Exhaust system structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust system structure which can raise the resistance to stress at a portion where members having different diameters are connected to each other while suppressing an increase in weight and cost, so as to improve the durability of the members and the whole of the exhaust system. <P>SOLUTION: The exhaust system of the invention includes front pipes joined to exhaust manifolds of an engine, catalyst converters, center pipes, a muffler 4 and a tail pipe 5 which are connected successively. The muffler 4 includes an end plate 41 which is a member having a relatively large maximum diameter, and an inner pipe 42 having a smaller diameter. The inner pipe 42 is press-fitted in and connected to an end portion 412 of the end plate 41. By press-fitting the tail pipe 5 in the inner pipe 42, the muffler 4 and the tail pipe 5 having the maximum diameters different from each other are connected to each other. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an exhaust system structure.

An exhaust system provided in an internal combustion engine such as a vehicle is generally configured by connecting components such as a front pipe, a catalytic converter, a center pipe, a muffler, and a tail pipe. In addition, for example, an inner pipe, an outlet pipe, and the like are also provided in the muffler, and these are connected to each other and the muffler is connected to a center pipe and a tail pipe. Usually, joining by welding is employed for mutual connection of these constituent members. Further, for example, Patent Document 1 discloses a muffler in which an inlet-side inner pipe provided inside is connected to the outlet-side inner pipe by press-fitting. This muffler is intended to reduce the cost by omitting the cushioning material that has been used when connecting inner pipes having substantially the same diameter, and improving the assemblability.
JP-A-6-26334

  However, in an exhaust system in which constituent members are connected by conventional welding, in a severe usage environment where vibrations are excessively large, a large stress caused by external input vibration is applied to the welded part where the constituent members are joined together. Tend to occur. Therefore, in order to suppress stress corrosion and metal fatigue at the welded part and increase the durability of the component member and the entire exhaust system, measures such as increasing the thickness of the component member or reinforcing it with another reinforcing member are required. . In this case, inconveniences such as an increase in weight and an increase in cost occur.

  When connecting components having different diameters (circumferential diameters), the outer shape of the component having a larger diameter (muffler, catalytic converter, etc.) is formed so as to be tapered toward the tip of the member, for example. Are often connected. In this case, a large stress is likely to be concentrated at the connecting portion compared to the case where members having substantially the same tube diameter are connected, and it is necessary to further increase the strength and durability. For this reason, when welding is used to connect components having different diameters, measures such as further increasing the thickness of the components or increasing the number of reinforcing members are required. Also, in this case, as described in the above-mentioned conventional publication, even if the inner pipes having substantially the same diameter provided inside the muffler are press-fitted together, it is not sufficient as a countermeasure for the welded portion where stress concentration is a concern. Absent.

  Therefore, the present invention has been made in view of such circumstances, and while suppressing an increase in weight and an increase in cost, it is possible to increase resistance to stress at a connection portion between constituent members having different diameters, and thus the constituent members. And it aims at providing the exhaust system structure which can improve the durability of the whole exhaust system.

  In order to solve the above problems, an exhaust system structure according to the present invention includes a plurality of constituent members, and among the plurality of constituent members, a plurality of constituent members having different maximum diameters are connected by press-fitting. .

  In such an exhaust system structure, constituent members are connected to each other to form an exhaust system. Among the plurality of constituent members, a plurality of constituent members having different maximum diameters (for example, the maximum diameter of the pipe portion) are press-fitted and connected to each other (normally, the end portions that are abutted overlap each other) Is brought into contact with the other outer surface. Therefore, even if vibrations are transmitted to the exhaust system and bending stress, tensile stress, torsional stress, etc. due to the input vibration are applied to the connection parts of the component members, those stresses are applied to the component members. It is applied to the entire press-fitting surface. That is, the stress can be applied to the entire pressure surface.

  Therefore, in a connection part of a plurality of constituent members having different maximum diameters, the stress concentration on the part connected to the constituent member having the larger maximum diameter is tapered or narrowed and connected to the constituent member having the smaller maximum diameter is remarkable. However, stress resistance and durability can be improved without taking measures such as increasing the thickness of the connection site.

  Moreover, it may be connected in a state where not two but three or more components overlap. For example, a muffler having an internal structure such as an inner pipe itself has a plurality of constituent members. More specifically, for example, a straight tubular inner pipe and an end provided so as to cover the periphery thereof. The plate is connected to the end of the member. Therefore, at a connection portion between the muffler having such a structure and an exhaust pipe such as a tail pipe, a plurality of members constituting the muffler and the exhaust pipe can be connected in a triple manner.

  In this case, the inner pipe and the end plate of the muffler are in a relationship of a plurality of constituent members having different maximum diameters, and the exhaust pipes such as the muffler and the tail pipe made of the plurality of constituent members have different maximum diameters. It is a plurality of constituent members. In this example, the end plate of the muffler has an outer shape in which the diameter is gradually reduced toward the end portion of the muffler that is the connection site, so that stress is easily concentrated there. Therefore, the present invention is very effective for such a connection form of a plurality of constituent members.

  That is, as an example, it is particularly useful when a plurality of constituent members having different maximum diameters are a muffler and an exhaust pipe provided at the front stage or the rear stage of the muffler.

  By the way, in a connection part of a component having a different maximum diameter, such as a connection between a muffler having the end plate and a tail pipe, the end (corresponding to the connection part) of the member having the largest maximum diameter is burred (for example, predetermined Need to be stretched or flanged). At this time, in order to ensure the press-fitting of the constituent members, it is necessary to secure a certain burring height (length of the burred end) as a connection margin. However, there may be a case where a desired burring height cannot be secured due to manufacturing reasons.

  In such a case, some of the constituent members having different maximum diameters may be joined by welding. For example, in the above-described example, when the burring height is not sufficiently secured at the end of the end plate of the muffler, the end plate and the inner pipe are joined by welding, It is preferable to press-fit the end plate.

  Further, among the plurality of constituent members having different maximum diameters, the maximum diameter of the constituent member having the larger maximum diameter is more than twice the diameter at the connecting portion with the constituent member having the smaller maximum diameter. There is a possibility that the stress concentration at the connection site becomes extremely large, and therefore the present invention is more effective in this case.

  According to the exhaust system structure of the present invention, since the plurality of constituent members having different maximum diameters are connected to each other by press-fitting, the stress that can be generated by external input vibration can be received on the entire press-fitting surface of the connection part. Thus, while suppressing an increase in weight and cost, it is possible to increase the stress resistance at the connection portion between the constituent members having different diameters, thereby improving the durability of the constituent members and the entire exhaust system.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

  FIG. 1 is a plan view showing a preferred embodiment of an exhaust system structure according to the present invention. The exhaust system 1 (exhaust system structure) is connected to two exhaust manifolds (both not shown) provided in a V-type engine provided in a vehicle. The exhaust system 1 includes a front pipe 11, a catalytic converter 21, and a center pipe 31 connected to one exhaust manifold, and a front pipe 12, a catalytic converter 22, and a center pipe 32 connected to the other exhaust manifold. Further, a muffler 4 (component member) and a tail pipe 5 (component member, exhaust pipe) are connected to the rear ends of the center pipes 31 and 32.

  Here, FIG. 2 is a diagram schematically showing a main part of a cross section taken along line II-II in FIG. The muffler 4 is provided with an inner pipe 42 (component) inside an end plate 41 (component). The end plate 41 is obtained by burring the end portion 412 of the curved surface portion 411 that has a curved shape so that the circumferential diameter gradually decreases toward the end portion on the tail pipe 5 side. The inner pipe 42 is integrally connected to the end plate 41 by press-fitting the end 422 of the body 421 into the end 412 of the end plate 41. Further, the end portion 422 of the body portion 51 of the tail pipe 5 is press-fitted into the end portion 422 of the inner pipe 42, whereby the muffler 4 and the tail pipe 5 having different maximum diameters are connected.

The method for press-fitting between these exhaust system members is not particularly limited, and the load pressure depends on the thickness of the member, but the end plate 41 has a thickness of 1.0 to 1.2 mm, for example. Sometimes it is preferably about 1000 to 5000 kgf / m ² (10 to 50 kPa). Moreover, when the thickness and load pressure of the end plate 41 are such, about -1 mm can be illustrated as press-fit (tightening). Furthermore, in order to press-fit the inner pipe 42 into the end plate 41, it is desirable to secure a certain burring height H (length of the end portion 412) of the end plate 41. For example, the burring height H is preferably 20 mm or more, More preferably, it is 30 mm or more. If the burring height H is insufficient, the area where the end portions 412 and 422 are in contact with each other, that is, the area of the press-fitting surface becomes excessively small.

  However, as described above, there may be a case where the burring height H cannot be sufficiently secured in order to reduce the manufacturing reason and weight. In such a case, welding may be combined.

  As an example, FIG. 3 is a diagram schematically showing a cross section of a main part (cross section taken along the line III-III shown in FIG. 1) of an exhaust system including a muffler having a different form from the muffler shown in FIG. This exhaust system is configured in the same manner as the exhaust system shown in FIG. 1 except that it includes a muffler 6 (component) instead of the muffler 4. The muffler 6 has an inner pipe 44 (configuration) with an end plate 43 (component) having a curved surface portion 431 having an end portion 432 having a burring height shorter than that of the end plate 41, with a constant tube diameter until the end. Member) is joined by welding. The welded portion W is provided on the entire circumference along the end portion 432 of the muffler 6. In this way, the constituent members of the muffler 6 are joined together by welding, and the tail pipe 5 is press-fitted into the pipe end of the inner pipe 44, thereby connecting the muffler 6 and the tail pipe 5 having different maximum diameters. ing.

  According to the exhaust system 1 configured as described above, the muffler 4 is configured by press-fitting the inner pipe 42 to the end plate 41 that has the curved surface portion 411 and tends to concentrate stress on the end portion 412. Therefore, even if a bending stress, a tensile stress, a torsional stress, or the like is applied to the connecting portion of both members 41 and 42 due to the input vibration to the exhaust system 1, the inner surface of the end portion 412 and the outer surface of the end portion 422 are formed. Those stresses can be received by the entire pressed-in surface. Therefore, even if the stress concentration is remarkable, the stress resistance of the connecting portion can be increased without taking measures such as increasing the thickness of the connecting portion between the end plate 41 and the inner pipe 42, and consequently the muffler 4 and The durability of the entire exhaust system 1 can be improved.

  Further, the muffler 4 and the tail pipe 5 formed by connecting the end plate 41 and the inner pipe 42 have different maximum diameters, but the tail pipe 5 is press-fitted into the inner pipe 42 of the muffler 4 so that both are connected. Therefore, in the same manner as described above, the stress resistance at the abutting portions of the end portions 422 and 52 which are connection sites is sufficiently strengthened, and the durability of the exhaust system 1 can be further improved.

  Further, the muffler 6 and the tail pipe 5 to which the end plate 43 and the inner pipe 44 are connected have different maximum diameters, but the tail pipe 5 is press-fitted into the inner pipe 44 of the muffler 6 and the two are connected. Therefore, also in this case, the stress resistance at the contact portion between the end portion 52 and the inner pipe 44 which is a connection site is sufficiently strengthened, and the durability of the exhaust system 1 can be further improved.

  In particular, when the maximum diameter of the muffler 4 (that is, the maximum diameter of the end plate 41) is more than twice the maximum diameter (tube diameter) of the end portion 412 that is a connection portion with the tail pipe 5, the end portion 412 is reached. The stress concentration tends to be very remarkable. Therefore, even in such a case, since the stress generated by the vibration input is received by the entire press-fitting surfaces of the end plate 41, the inner pipe 42, and the tail pipe 5, the stress resistance is sufficiently enhanced, and the durability of the exhaust system 1 is increased. Can be increased sufficiently.

  Further, when the burring height H is preferably 20 mm or more, the area of the press-fit surface where the end portions 412 and 422 abut, that is, the stress receiving surface can be surely widened. It becomes easier to further improve the durability.

  Furthermore, in the muffler 6, since the end plate 43 and the inner pipe 44 are joined by welding when the burring height of the end portion 432 is short, the burring height cannot be sufficiently secured due to manufacturing restrictions. Even in this case, by connecting the muffler 6 and the tail pipe 5 by press-fitting, it is possible to increase the stress resistance of the connecting portions of both. Further, since the weight of the end 432 is reduced by the small burring height, the weight can be reduced.

  In addition, this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible in the limit which does not change the summary. For example, in the present invention, not only the connection between the mufflers 4 and 6 and the tail pipe 5 but also the connection between the mufflers 4 and 6 and the center pipes 31 and 32, the catalytic converters 21 and 22 and the front pipes 11 and 12 or the center pipes 31 and 32. It may be applied to other connections. When the exhaust system 1 includes a sub muffler, the present invention may of course be applied to the connection between the sub muffler and the exhaust pipe. Furthermore, the present invention may of course be used not only for an exhaust system connected to a V-type engine but also for an exhaust system connected to an in-line engine.

  The exhaust system structure according to the present invention can increase the resistance to stress at the connecting portion between components having different diameters while suppressing an increase in weight and cost, and consequently the durability of the components and the exhaust system as a whole. Since it can improve, it can utilize widely for apparatuses, motives, facilities, etc., such as vehicles provided with an exhaust system etc. which were connected to an internal-combustion engine.

1 is a plan view showing a preferred embodiment of an exhaust system structure according to the present invention. It is a figure which shows typically the principal part of the cross section which follows the II-II line in FIG. It is a figure which shows typically the principal part cross section (cross section which follows the III-III line shown in FIG. 1) of an exhaust system provided with the muffler of a form different from the muffler shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Exhaust system (exhaust system structure), 4, 6 ... Muffler (component), 5 ... Tail pipe (component, exhaust pipe), 11, 12 ... Front pipe, 21, 22 ... Catalytic converter, 31, 32 ... Center pipe , 41, 43 ... end plate (component), 42, 44 ... inner pipe (component), 43 ... end plate (component), 51, 421 ... trunk, 52, 412, 422, 432 ... end, 411, 431 ... curved surface portion, W ... welded portion.

Claims (4)

Comprising a plurality of components,
Among the plurality of constituent members, a plurality of constituent members having different maximum diameters are connected by press-fitting,
Exhaust system structure. A part of the plurality of constituent members having different maximum diameters is joined by welding,
The exhaust system structure according to claim 1. Among the plurality of constituent members having different maximum diameters, the maximum diameter of the constituent member having the larger maximum diameter is at least twice the diameter at the connection site with the constituent member having the smaller maximum diameter.
The exhaust system structure according to claim 1 or 2. A plurality of exhaust system members having different maximum diameters are a muffler and an exhaust pipe provided at a front stage or a rear stage of the muffler.
The exhaust system structure according to any one of claims 1 to 3.

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