JP3433097B2 - Insulated exhaust pipe for engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of fixing one end of an inner pipe and an outer pipe which are arranged inside and outside doubly.
The present invention relates to an improvement in a warm exhaust pipe of an engine including an exhaust manifold having an annular mesh member interposed between the other end portions thereof to enable relative sliding therebetween. 2. Description of the Related Art An annular mesh member in such a heat-insulating exhaust pipe secures an adiabatic space between an inner pipe and an outer pipe, and also has a thermal expansion in the axial direction of the inner pipe and the outer pipe due to exhaust gas. It has the function of absorbing the difference between the two and suppressing the vibration of the free end of the inner tube. [0003] Conventionally, as a structure for holding a mesh member in such a heat retaining type exhaust pipe, a mesh member welded to the inner peripheral surface of an outer pipe (for example, Japanese Patent Laid-Open No. 9-280).
No. 046) and a mesh member fixedly held in an annular groove formed in the inner peripheral surface of the outer tube (Japanese Utility Model Laid-Open No.
129830). [0004] In any of the above-mentioned conventional ones, the mesh member is fixed to the outer tube, so that only the inner peripheral surface of the mesh member serves as a sliding surface and the outer peripheral surface of the inner tube. And can slide relative to each other. Therefore, the difference in the thermal expansion between the inner pipe and the outer pipe due to the exhaust gas is absorbed only by the sliding between the inner peripheral surface of the mesh member and the outer peripheral surface of the inner pipe. If foreign matter such as enters the slide pipe, the sliding is immediately inhibited, and thermal distortion occurs in each part of the exhaust pipe, which may impair its durability. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it has been made possible to use both the inner and outer peripheral surfaces of an annular mesh member as sliding surfaces so that one of the sliding surfaces can be used. Even if a sliding failure occurs, the relative displacement between the inner pipe and the outer pipe is not hindered, and the difference in thermal expansion in the axial direction between the two pipes can be reliably absorbed. The purpose is to provide. [0006] To achieve the above object, according to an aspect of the present invention includes an upper flange, and a plurality of exhaust single pipe coupling each upstream end to the upper flange, these exhaust An exhaust manifold connected to the downstream end of the single pipe, and a lower flange connected to the downstream end of the exhaust manifold;
Each tube portion is constituted by a double wall, in heat insulation type exhaust manifold of the engine, constitute the exhaust collecting pipe, the inner collecting pipe and the outer collecting pipe arranged on the inner and outer double, the inner current
The upstream end of the joint pipe, the upstream end of the outer collecting pipe and the
Integrate the three parts with the downstream end of the exhaust pipe at the same location
Secured to, wherein the annular recess formed in the downstream end portion peripheral surface of the outer collection tube, an annular mesh member slidably supporting the outer circumferential surface of the inner collector pipe, sliding with respect to the annular recess freely mounted, and feature that combines the lower flange on the downstream end of the outer collecting pipe. [0007] According to this feature, the difference in axial thermal expansion of the inner monotube and outer monotube, inner single tube and the mesh member, be absorbed by sliding between the outer monotube mesh member Can be. Therefore, even if a sliding failure occurs due to foreign matter being caught in one of the sliding parts, the difference in the thermal elongation in the axial direction can be absorbed without any trouble by the operation of the other sliding part. The durability of the exhaust manifold can be improved. In addition, when the two sliding portions operate normally, the difference in thermal expansion between the inner tube and the outer tube in the axial direction is shared by the two sliding portions. Can be reduced by half as compared with the conventional case having only one sliding portion, which can contribute to the improvement of the durability of the mesh member. In particular, the upstream end of the inner collecting pipe and the outer end
The upstream end of the collecting pipe and the downstream end of the exhaust pipe are
Are integrally fixed to each other at the same place. Embodiments of the present invention will be described below based on embodiments of the present invention shown in the accompanying drawings. FIG. 1 is a side view of an engine provided with a warmed exhaust manifold according to a first embodiment of the present invention, and FIG.
FIG. 3 is a perspective view of the exhaust manifold, FIG. 3 is a partially longitudinal front view of the exhaust manifold, FIG.
5 is a sectional view taken along line 5-5 in FIG. 1, FIG. 6 is a sectional view taken along line 6-6 in FIG. 5, and FIG. 7 is a vertical sectional front view of an exhaust manifold showing a second embodiment of the present invention. First, a description will be given of a first embodiment of the present invention with reference to FIGS. [0013] In FIG. 1, the front surface of the cylinder head 1 of a four-cylinder engine E, in correspondence with its cylinder four exhaust ports ₂₁ to ₂₄ are opened, these exhaust ports 2 ₁
Induces exhaust gas discharged from 21 _{to 24,} the exhaust manifold M as insulation type exhaust pipe of the present invention is mounted by a plurality of stud bolts 3 and nuts 4 on the cylinder head 1. [0014] As shown in FIGS. 2 to 4, the exhaust manifold M includes a four exhaust monotube 5 ₁ to 5 ₄ of which communicates separately with the four exhaust ports _{21 to 24} of ,
These are referred to as first to fourth exhaust single tubes from the left side in FIG. [0015] The first to the first to the upper flange 7 is connected to the fourth upstream end of the exhaust monotube 5 ₁ to 5 _4, the downstream end of the second and third exhaust monotube 5 _2, 5 ₃ exhaust collecting pipe ₆₁ is connected, the second to the downstream end of the first and fourth exhaust monotube 5 ₁ 5 ₄
Exhaust collecting pipe 6 ₂ are connected. The lower flange 8 is connected to the downstream end of the first and second exhaust manifolds 6 ₁ , 6 ₂ . The upper flange 7 is fixed to the cylinder head 1 by the stud bolts 3 and the nuts 4, and the lower flange 8 is connected to a common catalytic converter (exhaust gas purifier) (not shown) arranged under the floor of the vehicle. The intermediate exhaust pipe 21 is connected. The above-mentioned catalytic converter can be directly connected to the lower flange 8. [0016] Each exhaust monotube 5 ₁ to 5 _4, made of an inner monotube 10 and the outer single tube 11 was placed inside and outside double, cylindrical insulation space is between the inner and outer monotube 10,11 12 are formed. The inner single pipe 10 is made of a thin stainless steel pipe, and the outer single pipe 11 is also made of a stainless steel pipe, but is thicker than the inner single pipe 10. The upstream end of the outer tube 11 is connected to the inner tube 1
0 is reduced in diameter to fit the upstream end outer peripheral surface of, their upstream end upper flange 7, fitted to a through hole _131-134 leading to the corresponding exhaust port ₂₁ to ₂₄ together we are engaged, is fixed by welding to the inner peripheral surface of the through hole _131-134 (see FIG. 4). At the downstream end of the inner single tube 10, there is formed an annular projection 14 having an arc-shaped cross section which rises to the outer peripheral surface due to the diameter expansion from the inner peripheral side.
1 is slidably fitted to the inner peripheral surface. Thus, the downstream end of the inner single pipe 10 is slidably supported by the outer single pipe 11. Each of the exhaust manifolds 6 ₁ , 6 ₂ is composed of an inner manifold 15 (inner pipe) and an outer manifold 1 arranged in an inner / outer double.
6 (outer tube), the inner and outer collecting tubes 1
A heat insulating space 17 is also formed in 5 and 16. Inner collecting pipe 1
Reference numeral 5 denotes a structure in which a pair of inner collecting pipe halves 15a and 15b made of a thin stainless steel plate are opposed to each other at opposite ends, and the entire overlapping portion is welded. At that time, the inner collecting pipe 1
5 are formed at the upstream end thereof with two corresponding outer single tubes 11, 11.
Is inserted at the downstream end. The outer collecting pipe 16 is also formed by overlapping opposing ends of a pair of outer collecting pipe halves 16a and 16b made of stainless steel and welding the entire overlapping portion. Is thicker than the inner collecting pipe 15. At the upstream end of the outer collecting pipe 16, outer bifurcated pipes 19, 19 respectively covering the inner bifurcated pipes 18, 18 are formed. The distal ends of the outer bifurcated pipes 19, 19 are connected to the inner bifurcated pipes 18, 18
The outer diameters of the outer single tubes 11 and 11 are fixed to each other by welding. As shown in FIG. 5 and FIG.
The lower flange 8 is fixed to a downstream end of the lower flange 6 by welding. An annular concave portion 21 is formed on the inner peripheral surface of the downstream end portion of the outer collecting pipe 16, and an annular split mesh member 20 formed by knitting a stainless steel wire into the annular concave portion 21, that is, a pair of mesh half bodies 20a, 20b is slidably mounted, and the downstream end of the inner collecting pipe 15 is slidably fitted to the inner peripheral surfaces of the mesh halves 20a and 20b. At this time, a pair of mesh halves 20a, 20a
b, the inner collecting pipe half 1 constituting the inner collecting pipe 15
5a, 15b weld 22 and outer collecting pipe half 16a,
16b welding part 23 is arranged. Thus, by sequentially inserting the pair of mesh halves 20a and 20b into the annular concave portion 21, the mesh member 20 can be easily mounted on the outer collecting pipe 16, and furthermore, the mesh halves 2a and 20b can be easily inserted.
By interposing a weld 22 protruding outwardly of the inner collecting pipe halves 15a and 15b between 0a and 20b, interference between the weld 22 and the mesh member 20 is avoided, and each mesh half 20a, Unnecessary rotation of 20b can be restrained. Next, the operation of the first embodiment will be described. [0024] During operation of the engine E, an exhaust port 2 ₁ of the exhaust gas is four, ₂ 2, 2 _4, 2 ₃ from the first exhaust monotube 5 _1,
Second exhaust monotube 5 _2, fourth exhaust monotube 5 _4, the third exhaust monotube 5
_It is sequentially discharged to ₃ . The exhaust gas which has passed through the first and fourth exhaust monotube 5 _1, 5 ₄ merged in the first exhaust collecting pipe _61, which has passed through the second and third exhaust monotube 5 _2, 5 ₃ and the second merge at an exhaust merging pipe 6 _2, then, the exhaust gas while further merges with the intermediate exhaust pipe 21, is guided to a common catalytic converter (not shown) to be purified. By the way, the exhaust monotube 5 ₁ to 5 ₄ are composed of an inner monotube 10 and the outer single tube 11 of the inner and outer double arrangement,
The inner single tube 10 is formed to be thin, and a heat insulating space 12 is formed between the inner and outer single tubes 10 and 11.
Each of the exhaust manifolds 6 ₁ , 6 ₂ is also composed of an inner manifold 15 and an outer manifold 16 in a double inner / outer arrangement. The inner manifold 15 is formed to be thin, and the inner and outer manifolds 15, 16 are formed. The heat insulating space 17 is also formed between the inner single pipe 10 and the inner collecting pipe 15 having a small heat mass.
It is heated by the high-temperature exhaust gas flowing through the inside thereof and quickly rises in temperature, and this is kept warm by the heat insulating spaces 12 and 17. Therefore, the subsequent exhaust gas can be guided to the catalytic converter while suppressing its temperature decrease, thereby promoting its activation and improving the purification efficiency of the exhaust gas. [0026] Meanwhile, in the exhaust monotube 5 ₁ to 5 _4, the thermal expansion of greater axial than the outer single tube 11 side inside the single tube 10 is caused, downstream of the inner monotube 10 along with its elongation The annular projection 14 on the outer peripheral surface of the side end slides on the inner peripheral surface of the outer single tube 11 supporting the same, and the inner and outer single tubes 1 are moved.
The difference in thermal expansion in the axial direction of 0, 11 is absorbed. In each of the exhaust manifolds 6 ₁ and 6 ₂ ,
Thermal expansion in the axial direction of the inner collecting pipe 15 is larger than that of the outer collecting pipe 16, and the downstream end of the inner collecting pipe 15 slides with respect to the outer collecting pipe 16 via the mesh member 20 with the expansion. Then, the difference in the thermal expansion between the inner and outer collecting pipes 15, 16 in the axial direction is absorbed. It should be noted that both the inner peripheral surface and the outer peripheral surface of the annular mesh member are sliding surfaces. Therefore, when a difference in thermal elongation in the axial direction occurs between the inner single tube 10 and the outer single tube 11, the inner single tube 1
0 and mesh member 20, outer single tube 11 and mesh member 2
In this case, sliding occurs between the values of 0 and the difference in thermal elongation can be absorbed. Therefore, even if one of the inner peripheral surface side and the outer peripheral surface side of the mesh member 20 causes sliding failure due to foreign matter biting in, the difference in thermal elongation can be absorbed by the other sliding member without hindrance. Therefore, the durability of the exhaust manifold M can be improved. Moreover, when both the inner peripheral surface and the outer peripheral surface of the mesh member 20 can slide normally, the difference in the thermal expansion between the inner single tube 10 and the outer single tube 11 in the axial direction is absorbed. Since the inner and outer peripheral surfaces are shared, the sliding amount of each sliding part is 1 unit.
It is halved as compared with the conventional case having only a portion, and the durability of the mesh member 20 can be improved. Unnecessary movement of the mesh member 20 is restricted by the end surface of the annular concave portion 21 of the outer single tube 11. Since the downstream ends of the inner and outer collecting pipes 15 and 16 have relatively large diameters, the difference in the thermal expansion in the circumferential direction cannot be ignored, but the difference is caused by the compressive deformation of the mesh member 20. Absorbed. Further, the mesh member 20 is formed by the inner single pipe 10.
, That is, the free end, that is, the downstream end, can be suppressed from generating noise due to the vibration. [0031] Thus, in thermal insulation type exhaust manifold M, the downstream end of each exhaust monotube 5 ₁ to 5 ₄ a sliding portion for absorbing the difference in axial thermal expansion of the inner and outer double wall and the exhaust by providing divided into the downstream end of the collecting pipe 6 _and 62, it is possible to set a sliding stroke in the sliding portions small, in sliding, the inclination of the sliding portion mutually This hardly occurs, and it is possible to effectively prevent the occurrence of thermal distortion in each part of the exhaust manifold M, and to improve the durability thereof. The insulation type exhaust manifold M in accordance with a third embodiment of the present invention shown in FIG. 7 is obtained by connecting a single common exhaust collecting pipe 6 to the four exhaust monotube 5 ₁ to 5 _4, the The heat retaining structure and the thermal elongation absorbing structure are substantially the same as those of the first embodiment. In the drawing, the same reference numerals are given to the parts corresponding to those of the first embodiment, and the description is omitted. . Although the embodiment of the present invention has been described in detail, various design changes can be made in the present invention without departing from the gist thereof. For example, the number and shape of the single exhaust pipe and the exhaust collecting pipe can be freely selected according to the number and type of cylinders of the engine. Further, the heat insulating spaces 12 and 17 can be filled with a heat insulating material. As described above , according to the present invention , an upper flange, a plurality of exhaust pipes connecting each upstream end to the upper flange, and a downstream end of these exhaust pipes are provided. An exhaust manifold connected to the exhaust manifold, and a lower flange connected to a downstream end of the exhaust manifold, wherein each of the pipes is formed of a double wall. The pipe is composed of an inner collecting pipe and an outer collecting pipe arranged in a double inner and outer pipe, and the upstream end of the inner collecting pipe and the
The upstream end of the outer collecting pipe and the downstream end of the exhaust single pipe;
Mutually fixed integrally, wherein the annular recess formed in the downstream end portion peripheral surface of the outer collection tube, an annular mesh member slidably supporting the outer circumferential surface of the inner collector pipe, the annular concave
Part slidably mounted with respect to the so bound the lower flange, the difference in axial thermal expansion of the inner side collecting pipe and the outer collecting pipe, the inner side collecting pipe at the downstream end of the outer collecting pipe and between the mesh member, it is possible to absorb I by the one of the sliding <br/> between the outer collecting pipe and the mesh member. Therefore,
Even if sliding failure occurs due to foreign matter being caught in one of the sliding parts, the difference in thermal expansion in the axial direction can be absorbed without any trouble by the operation of the other sliding part. Can be improved. In addition, when both sliding parts operate normally, the difference in thermal expansion between the inner collecting pipe and the outer collecting pipe in the axial direction is shared by the two sliding parts. It is small and can contribute to improving the durability of the mesh member. In particular, the upstream end of the inner collecting pipe and the outer end
The upstream end of the collecting pipe and the downstream end of the exhaust pipe are
Are integrally fixed to each other at the same place.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of an engine provided with a heat retaining type exhaust manifold according to a first embodiment of the present invention. FIG. 2 is a perspective view of the exhaust manifold. FIG. FIG. 4 is an enlarged view of part 4 in FIG. 3 FIG. 5 is a sectional view taken along line 5-5 of FIG. 1 FIG. 6 is a sectional view taken along line 6-6 of FIG. 5 FIG. exemplary longitudinal sectional front view of the exhaust manifold of an example eXPLANATION oF REFERENCE nUMERALS E · · · · · engine M · · · · · exhaust manifold ₂₁ to ₂₄ ... exhaust port 5 ₁ to 5 ₄ ... exhaust single Pipes 6 ₁ , 6 ₂ , 6 ... Exhaust collecting pipe 15 ... Inner pipe (inner collecting pipe) 16 ... Outer pipe (outer collecting pipe) 17 ... Insulated space 20 ... Mesh member

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Taku Komatsuda 1-4-1 Chuo, Wako-shi, Saitama Pref. Inside of Honda R & D Co., Ltd. (72) Tatsumi Yamada 1-4-1 Chuo, Wako-shi, Saitama Pref. Inside the Honda R & D Co., Ltd. (72) Inventor Seiji Kato 1-4-1, Chuo, Wako-shi, Saitama Prefecture Stock Company Inside the Honda R & D Co., Ltd. (72) Koichi Fujimori 1-4-1, Chuo Wako-shi, Saitama Stock Company Within the Technical Research Institute (72) Inventor Kazuhiro Furuhashi 508-1, Yutakamachi, Hamamatsu-shi, Shizuoka Prefecture Inside Yutaka Giken Co., Ltd. (56) References JP-A-7-42547 (JP, A) JP-A 8-74566 (JP) , A) JP-A-9-280046 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F01N 7/10 F01N 7/08 F01N 7/14

Claims (1)

(57) and the Patent Claims 1] upper flange (7), a plurality of exhaust single pipe coupling each upstream end to the upper flange (7) (5
And _{1-5 4),} the downstream exhaust collecting pipe which is coupled to an end portion (6 _1, 6 _2, 6), the exhaust collecting pipe (6 ₁ of the exhaust monotube (5 ₁ to 5 _4), 6 _2, 6) and a lower flange (8) which is coupled to the downstream end of each tube portion is constituted by a double wall, in heat insulation type exhaust manifold of an engine, the exhaust collecting pipe (6 _1, 6 ₂ , 6) are composed of an inner collecting pipe (15) and an outer collecting pipe (16) arranged in an inner and outer doubly, and the upstream end of the inner collecting pipe (15) and the outer collecting pipe (15).
The exhaust monotube the upstream end of the collecting pipe (16) (5 ₁ to 5
₄ ) and the downstream end of the outer collecting pipe (16) are integrally fixed to each other at the same location, and the annular recess (21) formed on the inner peripheral surface of the downstream end of the outer collecting pipe (16). Is the inner collecting pipe (15)
Annular mesh member (2) that slidably supports the outer peripheral surface of
0) is slidably mounted on the annular recess (21) ,
A warm exhaust manifold for an engine, wherein the lower flange (8) is connected to a downstream end of the outer collecting pipe (16).