JPH0868319A - Exhaust double-pipe structure - Google Patents
Exhaust double-pipe structureInfo
- Publication number
- JPH0868319A JPH0868319A JP20225294A JP20225294A JPH0868319A JP H0868319 A JPH0868319 A JP H0868319A JP 20225294 A JP20225294 A JP 20225294A JP 20225294 A JP20225294 A JP 20225294A JP H0868319 A JPH0868319 A JP H0868319A
- Authority
- JP
- Japan
- Prior art keywords
- pipe
- inner pipe
- thermal expansion
- outer pipe
- exhaust
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Exhaust Silencers (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、内燃機関の排気系に用
いられる排気二重管の構造に関し、とくに内管と外管と
の周方向の熱膨張差に起因する熱応力による排気管の損
傷を防止することが可能な排気二重管の構造に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an exhaust double pipe used in an exhaust system of an internal combustion engine, and more particularly to an exhaust pipe due to thermal stress caused by a difference in thermal expansion between an inner pipe and an outer pipe in a circumferential direction. The present invention relates to a structure of an exhaust double pipe capable of preventing damage.
【０００２】[0002]
【従来の技術】自動車における排気ガス浄化触媒の暖機
性能を向上させる一手段として、排気系部品の熱容量を
低減することが行われており、低熱容量化のため二重管
構造とした排気管が採用されている。二重管構造の排気
管の一例として、実開平５−１９５２２号公報が知られ
ている。本公報の排気管では、内管と外管は一端で固定
され他端を自由端とすることにより、内管と外管の軸方
向の熱膨張差を吸収するようにしている。図１３は、従
来の二重管構造の排気管の一例を示している。内管１と
外管２は一端のみがスポット溶接等の固定部４により固
定されている。内管１と外管２の他端側には、内管１と
外管２との隙間を一定に保つように周方向に延びるワイ
ヤメッシュ３が設けられている。2. Description of the Related Art As one means for improving the warm-up performance of an exhaust gas purifying catalyst in an automobile, the heat capacity of exhaust system parts has been reduced, and an exhaust pipe having a double pipe structure for lowering the heat capacity. Has been adopted. As an example of an exhaust pipe having a double pipe structure, Japanese Utility Model Laid-Open No. 19522/1993 is known. In the exhaust pipe of this publication, the inner pipe and the outer pipe are fixed at one end and the other end is made to be a free end so as to absorb the difference in thermal expansion between the inner pipe and the outer pipe in the axial direction. FIG. 13 shows an example of a conventional exhaust pipe having a double pipe structure. Only one end of the inner pipe 1 and the outer pipe 2 is fixed by a fixing portion 4 such as spot welding. On the other end side of the inner pipe 1 and the outer pipe 2, a wire mesh 3 extending in the circumferential direction is provided so as to keep a gap between the inner pipe 1 and the outer pipe 2 constant.
【０００３】[0003]
【発明が解決しようとする課題】しかし、上記の実開平
５−１９５２２号公報および図１３に示す二重管構造の
排気管では、内管と外管との排気管軸方向の熱膨張差は
吸収できるが、周方向の熱膨張差を吸収することができ
ない。そのため、図１４に示すように、内管１と外管２
との固定部（溶接部）４およびその近傍には、周方向に
大きな熱応力が発生し、繰り返しの熱サイクルにより内
管１の固定部近傍の部位には破断部６が生じる。However, in the exhaust pipe having the double pipe structure shown in Japanese Utility Model Laid-Open No. 5-19522 and FIG. 13, there is a difference in thermal expansion between the inner pipe and the outer pipe in the axial direction of the exhaust pipe. It can absorb, but cannot absorb the difference in thermal expansion in the circumferential direction. Therefore, as shown in FIG. 14, the inner pipe 1 and the outer pipe 2 are
A large thermal stress is generated in the circumferential direction in the fixing portion (welding portion) 4 and the vicinity thereof, and a fracture portion 6 is generated in a portion near the fixing portion of the inner pipe 1 due to repeated thermal cycles.
【０００４】本発明の目的は、内管と外管との周方向の
熱膨張差に起因する熱応力により排気管が損傷を防止す
ることが可能な排気二重管構造を提供することにある。It is an object of the present invention to provide an exhaust double pipe structure capable of preventing the exhaust pipe from being damaged by thermal stress caused by a difference in thermal expansion between the inner pipe and the outer pipe in the circumferential direction. .
【０００５】[0005]
【課題を解決するための手段】この目的を達成するため
の排気二重管構造は、つぎのように構成されている。 （１）内管と外管とを固定して成る排気二重管におい
て、該内管と外管との固定部に、内管と外管との周方向
の熱膨張差を吸収する熱膨張吸収手段を設けることを特
徴とする排気二重管構造。 （２）熱膨張吸収手段は、固定部における内管の周方向
外面に凹凸部を形成し、該凸部と外管とを固定して成る
上記（１）記載の排気二重管構造。 （３）内管と外管とを固定して成る排気二重管におい
て、該内管と外管との周方向の熱膨張量がほぼ同じとな
るように内管と外管との熱膨張率を変えたことを特徴と
する排気二重管構造。An exhaust double pipe structure for achieving this object is constructed as follows. (1) In an exhaust double pipe formed by fixing an inner pipe and an outer pipe, a thermal expansion for absorbing a difference in thermal expansion between the inner pipe and the outer pipe in a circumferential direction at a fixed portion between the inner pipe and the outer pipe. An exhaust double pipe structure characterized by being provided with an absorbing means. (2) The exhaust double pipe structure according to the above (1), wherein the thermal expansion absorbing means is formed by forming a concavo-convex portion on the outer circumferential surface of the inner pipe in the fixing portion, and fixing the convex portion and the outer pipe. (3) In an exhaust double pipe in which the inner pipe and the outer pipe are fixed, the inner pipe and the outer pipe are thermally expanded so that the inner pipe and the outer pipe have substantially the same thermal expansion amount in the circumferential direction. Exhaust double pipe structure characterized by changing the rate.
【０００６】[0006]
【作用】上記（１）の排気二重管構造においては、内管
と外管との固定部に熱膨張吸収手段が設けられるので、
内管と外管との周方向の熱膨張差は熱膨張吸収手段によ
って吸収され、固定部およびその近傍には、大きな熱応
力は発生しない。したがって、内管と外管の固定部およ
びその近傍には、熱膨張差に起因する熱応力による損傷
は発生せず、排気管の耐久信頼性が高められる。上記
（２）の排気二重管構造においては、内管の周方向外面
に形成された凹凸部のうち凸部が外管に固定されるの
で、熱膨張差は凹部の変形によって吸収され、内管と外
管の固定部およびその近傍には、大きな熱応力は生じな
い。上記（３）の排気二重管構造においては、内管と外
管の熱膨張率が異なるので、内管の熱膨張量と外管の熱
膨張量とをほぼ同じにすることができる。したがって、
内管と外筒との熱膨張差が生じなくなり、内管と外管の
固定部およびその近傍には、大きな熱応力は生じない。In the exhaust double pipe structure of the above (1), since the thermal expansion absorbing means is provided at the fixed portion between the inner pipe and the outer pipe,
The thermal expansion difference between the inner tube and the outer tube in the circumferential direction is absorbed by the thermal expansion absorbing means, and no large thermal stress is generated in the fixed portion and its vicinity. Therefore, the fixed portion of the inner pipe and the outer pipe and the vicinity thereof are not damaged by the thermal stress due to the difference in thermal expansion, and the durability reliability of the exhaust pipe is enhanced. In the exhaust double pipe structure of the above (2), since the convex portion of the uneven portion formed on the outer circumferential surface of the inner pipe is fixed to the outer pipe, the difference in thermal expansion is absorbed by the deformation of the concave portion. No large thermal stress occurs in the fixed portion between the tube and the outer tube and its vicinity. In the exhaust double pipe structure of the above (3), since the thermal expansion coefficients of the inner pipe and the outer pipe are different, the thermal expansion amount of the inner pipe and the thermal expansion amount of the outer pipe can be made substantially the same. Therefore,
A difference in thermal expansion between the inner tube and the outer tube does not occur, and large thermal stress does not occur in the fixed portion of the inner tube and the outer tube and in the vicinity thereof.
【０００７】[0007]
【実施例】図１および図２は本発明の第１実施例を示し
ており、図３ないし図５は第１実施例の変形例を示して
いる。図６および図７は本発明の第２実施例を示してい
る。図８および図９は本発明の第３実施例を示してお
り、図１０および図１１は第３実施例の変形例を示して
いる。図１２は本発明の第４実施例を示している。ま
ず、各実施例にわたって共通な構成を、例えば図１を参
照して説明する。ただし、共通構成部分には各実施例に
わたって同一符号の使用している。1 and 2 show a first embodiment of the present invention, and FIGS. 3 to 5 show a modification of the first embodiment. 6 and 7 show a second embodiment of the present invention. 8 and 9 show a third embodiment of the present invention, and FIGS. 10 and 11 show a modification of the third embodiment. FIG. 12 shows a fourth embodiment of the present invention. First, a configuration common to each embodiment will be described with reference to FIG. 1, for example. However, common components are denoted by the same reference numerals throughout the embodiments.
【０００８】図１に示すように、１０は排気管を示して
おり、排気管１０は、内管１２と外管１４から構成され
ている。外管１４は、内管１２の外周に配置されてい
る。内管１２および外管１４は、金属材料からなるパイ
プから構成されている。内管１２の肉厚は、外管１４の
肉厚よりも薄くなっている。外管１４の一端は、内径が
内管１２の外径とほぼ同一になるように縮径されてい
る。軸方向端部を除く内管１２と外管１４との間には、
周方向に延びる隙間１５が形成されている。内管１２と
外管１４の一方の軸方向端部は、溶接等により接合され
ている。内管１２は、この溶接等による固定部１６によ
り、外管１４に固定されている。As shown in FIG. 1, reference numeral 10 denotes an exhaust pipe, and the exhaust pipe 10 is composed of an inner pipe 12 and an outer pipe 14. The outer pipe 14 is arranged on the outer periphery of the inner pipe 12. The inner pipe 12 and the outer pipe 14 are pipes made of a metal material. The wall thickness of the inner pipe 12 is smaller than the wall thickness of the outer pipe 14. One end of the outer pipe 14 is reduced in diameter so that the inner diameter is substantially the same as the outer diameter of the inner pipe 12. Between the inner pipe 12 and the outer pipe 14 excluding the axial end portion,
A gap 15 extending in the circumferential direction is formed. One axial ends of the inner pipe 12 and the outer pipe 14 are joined by welding or the like. The inner pipe 12 is fixed to the outer pipe 14 by a fixing portion 16 formed by welding or the like.
【０００９】つぎに、各実施例に共通な作用について説
明する。排気管１０に流入した排気ガスは、内管１２お
よび外管１４を加熱し、下流側に流れる。内管１２は排
気ガスと直接接触するので、外管１４よりも高温とな
り、内管１２の熱膨張量は外管１４の熱膨張量よりも大
となり、内管と外筒には熱膨張差が生じる。内管１２と
外管１４は、一方の軸方向端部のみが固定されているの
で、内管１２と外管１４は軸方向にはそれぞれ自由に熱
膨張することができ、内管１２と外管１４の軸方向の熱
膨張差は吸収される。Next, the operation common to each embodiment will be described. The exhaust gas flowing into the exhaust pipe 10 heats the inner pipe 12 and the outer pipe 14, and flows to the downstream side. Since the inner pipe 12 is in direct contact with the exhaust gas, the temperature becomes higher than that of the outer pipe 14, the thermal expansion amount of the inner pipe 12 becomes larger than the thermal expansion amount of the outer pipe 14, and the thermal expansion difference between the inner pipe and the outer cylinder is large. Occurs. Since only one axial end portion of the inner pipe 12 and the outer pipe 14 is fixed, the inner pipe 12 and the outer pipe 14 can freely thermally expand in the axial direction, respectively. The axial thermal expansion difference of the tube 14 is absorbed.
【００１０】つぎに、第１実施例に特有な構成および作
用について説明する。図１および図２に示すように、内
管１２の軸方向端部の固定部１６には、熱膨張吸収手段
としての凹凸部２０が形成されている。本実施例では、
凹凸部２０のうち凸部２０ａが突き出し部からなり、凹
部２０ｂが突き出し部以外の部位からなっている。凸部
２０ａは、周方向に一定の間隔をもって設けられてい
る。凸部２０ａは、半径方向外方に突出しており、断面
形状が半円状となっている。凸部２０ａは、軸方向に所
定の距離Ｗ1 だけ延びている。凸部２０ａの頂部は、溶
接等による固定部１６により外管１４の内周面と接合さ
れている。内管１２と外管１４の排気管軸方向の他端側
には、内管１２と外管１４との隙間１５を一定に保つた
めの周方向に延びるワイヤメッシュ（図示略）が設けら
れている。Next, the structure and operation peculiar to the first embodiment will be described. As shown in FIG. 1 and FIG. 2, a concavo-convex portion 20 as a thermal expansion absorbing means is formed in the fixed portion 16 at the axial end portion of the inner pipe 12. In this embodiment,
The convex portion 20a of the concave-convex portion 20 is a protruding portion, and the concave portion 20b is a portion other than the protruding portion. The convex portions 20a are provided at regular intervals in the circumferential direction. The convex portion 20a protrudes outward in the radial direction and has a semicircular cross section. The convex portion 20a extends in the axial direction by a predetermined distance W 1 . The top portion of the convex portion 20a is joined to the inner peripheral surface of the outer pipe 14 by the fixing portion 16 formed by welding or the like. A wire mesh (not shown) extending in the circumferential direction is provided on the other end side of the inner pipe 12 and the outer pipe 14 in the exhaust pipe axial direction so as to keep a gap 15 between the inner pipe 12 and the outer pipe 14 constant. There is.
【００１１】第１実施例においては、内管１２に形成さ
れた複数の凸部２０ａの頂部が外管１４に固定されてい
るので、内管１２と外管１４との周方向の熱膨張差が生
じた場合は、外管１４と固定されていない凹部２０ｂの
変形により、周方向の熱膨張差は吸収される。これによ
り、加熱冷却時の膨張または収縮量の差から生じる周方
向の熱応力が低減され、固定部１６およびこの近傍の部
位に作用する熱応力は小となる。したがって、肉厚の薄
い内管１２が損傷することはなくなる。In the first embodiment, since the tops of the plurality of projections 20a formed on the inner pipe 12 are fixed to the outer pipe 14, the difference in thermal expansion between the inner pipe 12 and the outer pipe 14 in the circumferential direction. In the case of occurrence of, the difference in thermal expansion in the circumferential direction is absorbed by the deformation of the recess 20b that is not fixed to the outer tube 14. As a result, the thermal stress in the circumferential direction caused by the difference in expansion or contraction amount during heating and cooling is reduced, and the thermal stress acting on the fixed portion 16 and the portion in the vicinity thereof becomes small. Therefore, the thin inner tube 12 is not damaged.
【００１２】図３ないし図５は、第１実施例の変形例を
示している。第１実施例では、凹凸部２０が軸方向に所
定の距離だけ延びているが、図５に示すように、本変形
例では凹凸部２０が内管１２の全長にわたって形成され
ている。これにより、内管１２と外管１４との間の隙間
１５は一定に保たれ、ワイヤメッシュを用いる必要がな
くなる。また、凹凸部２０を内管１２の全長にわたって
形成することにより、内管１２の曲げ剛性が高くなるの
で、熱変形を抑制することができ、内管１２の薄肉化が
可能となる。さらに、内管１２の薄肉化が可能となるこ
とから、排気管１０の熱容量が小さくなり、排気ガス浄
化触媒の暖機性能の向上が図れる。なお、凸部２０ａと
外管１４とを接合する固定部１６は、第１実施例と同様
に軸方向端部の一方のみである。3 to 5 show a modification of the first embodiment. In the first embodiment, the uneven portion 20 extends in the axial direction by a predetermined distance, but as shown in FIG. 5, the uneven portion 20 is formed over the entire length of the inner pipe 12 in this modification. Thereby, the gap 15 between the inner pipe 12 and the outer pipe 14 is kept constant, and it is not necessary to use a wire mesh. Further, since the unevenness 20 is formed over the entire length of the inner pipe 12, the bending rigidity of the inner pipe 12 is increased, so that thermal deformation can be suppressed and the inner pipe 12 can be made thin. Furthermore, since the inner pipe 12 can be made thin, the heat capacity of the exhaust pipe 10 is reduced, and the warm-up performance of the exhaust gas purification catalyst can be improved. The fixing portion 16 that joins the convex portion 20a and the outer pipe 14 is only one of the axial end portions, as in the first embodiment.
【００１３】つぎに、第２実施例に特有な構成および作
用について説明する。図６および図７に示すように、内
管１２の軸方向端部の固定部１６には、熱膨張吸収手段
としての凹凸部２２が形成されている。本実施例では、
凹凸部２２は波形となっており、凸部２２ａが山の部分
であり、凹部２２ｂが谷の部分となっている。凹凸部２
２は、排気管軸方向に所定の距離Ｗ2 だけ延びている。
凸部２２ａの頂部は、溶接等による固定部１６により外
管１４の内周面と接合されている。内管１２と外管１４
の排気管軸方向の他端側には、内管１２と外管１４との
隙間１５を一定に保つための周方向に延びるワイヤメッ
シュ（図示略）が設けられている。Next, the structure and operation peculiar to the second embodiment will be described. As shown in FIG. 6 and FIG. 7, a concavo-convex portion 22 as a thermal expansion absorbing means is formed on the fixed portion 16 at the axial end portion of the inner pipe 12. In this embodiment,
The concavo-convex portion 22 has a wavy shape, and the convex portion 22a is a peak portion and the concave portion 22b is a valley portion. Uneven portion 2
2 extends a predetermined distance W 2 in the axial direction of the exhaust pipe.
The top of the convex portion 22a is joined to the inner peripheral surface of the outer pipe 14 by the fixing portion 16 formed by welding or the like. Inner tube 12 and outer tube 14
On the other end side of the exhaust pipe in the axial direction, a wire mesh (not shown) extending in the circumferential direction is provided to keep the gap 15 between the inner pipe 12 and the outer pipe 14 constant.
【００１４】第２実施例においては、内管１２に形成さ
れた凹凸部２２お凸部２２ａの頂部が外管１４に固定さ
れているので、内管１２と外管１４との周方向の熱膨張
差が生じた場合は、外管１４と固定されていない凹部２
２ｂが変形するので、周方向の熱膨張差は吸収される。
本実施例では凹凸部２２には連続的に凸部２２ａと凹部
２２ｂが形成されるので、第１実施例に比べて熱膨張差
により自由変形できる部分が長くなり、熱応力の低減効
果がより大きくなる。したがって、排気管１０の熱疲労
強度をさらに向上することができる。In the second embodiment, since the tops of the projections and depressions 22a and the projections 22a formed on the inner pipe 12 are fixed to the outer pipe 14, the heat generated in the circumferential direction between the inner pipe 12 and the outer pipe 14 is increased. When a difference in expansion occurs, the outer tube 14 and the recessed portion 2 that is not fixed
Since 2b is deformed, the difference in thermal expansion in the circumferential direction is absorbed.
In this embodiment, since the projections 22a and the recesses 22b are continuously formed in the uneven portion 22, the portion which can be freely deformed due to the difference in thermal expansion becomes longer as compared with the first embodiment, and the effect of reducing the thermal stress is further improved. growing. Therefore, the thermal fatigue strength of the exhaust pipe 10 can be further improved.
【００１５】つぎに、第３実施例に特有な構成および作
用について説明する。図８および図９に示すように、内
管１２の軸方向端部の固定部１６には、熱膨張吸収手段
としての凹凸部２４が形成されている。本実施例では、
凹凸部２４のうち凸部２４ａが突起部からなり、凹部２
４ｂは突起部以外の部位からなっている。凸部２４ａ
は、周方向に一定の間隔をもって設けられている。凸部
２４ａは、半径方向外方に突出しており、半球面状に形
成されている。凸部２４ａの頂部は、溶接等による固定
部１６により外管１４の内周面と接合されている。内管
１２と外管１４の排気管軸方向の他端側には、内管１２
と外管１４との隙間を一定に保つための周方向に延びる
ワイヤメッシュ（図示略）が設けられている。Next, the structure and operation peculiar to the third embodiment will be described. As shown in FIGS. 8 and 9, a concavo-convex portion 24 as a thermal expansion absorbing means is formed in the fixed portion 16 at the axial end portion of the inner pipe 12. In this embodiment,
The convex portion 24a of the concave-convex portion 24 is a protrusion portion, and the concave portion 2
4b is composed of a portion other than the protruding portion. Convex portion 24a
Are provided at regular intervals in the circumferential direction. The convex portion 24a projects outward in the radial direction and is formed in a hemispherical shape. The top portion of the convex portion 24a is joined to the inner peripheral surface of the outer pipe 14 by the fixing portion 16 formed by welding or the like. On the other end side of the inner pipe 12 and the outer pipe 14 in the exhaust pipe axial direction, the inner pipe 12
A wire mesh (not shown) extending in the circumferential direction is provided to keep the gap between the outer tube 14 and the outer tube 14 constant.
【００１６】第３実施例においては、内管１２に形成さ
れた複数の凸部２４ａの頂部が外管１４に固定されてい
るので、内管１２と外管１４との周方向の熱膨張差が生
じた場合は、内管１２と外管１４と固定されていない凹
部２４ｂの変形により、周方向の熱膨張差は吸収され
る。これにより、加熱冷却時の膨張または収縮量の差か
ら生じる周方向の熱応力が低減され、固定部１６および
この近傍の部位に作用する熱応力は小となる。したがっ
て、肉厚の薄い内管１２の損傷が回避される。In the third embodiment, since the tops of the plurality of protrusions 24a formed on the inner pipe 12 are fixed to the outer pipe 14, the difference in thermal expansion between the inner pipe 12 and the outer pipe 14 in the circumferential direction. In the case of occurrence of, the difference in thermal expansion in the circumferential direction is absorbed by the deformation of the recess 24b that is not fixed to the inner tube 12 and the outer tube 14. As a result, the thermal stress in the circumferential direction caused by the difference in expansion or contraction amount during heating and cooling is reduced, and the thermal stress acting on the fixed portion 16 and the portion in the vicinity thereof becomes small. Therefore, damage to the thin inner tube 12 is avoided.
【００１７】図１０ないし図１１は、第３実施例の変形
例を示している。第３実施例では、凹凸部２４が固定部
１６にのみ設けられていたが、図１１に示すように、本
変形例では凹凸部２４は内管１２の全長にわたって形成
されている。これにより、内管１２と外管１４との間の
隙間は一定に保たれ、ワイヤメッシュを用いる必要がな
くなる。また、凹凸部２４を内管１２の全長にわたって
形成することにより、内管１２の曲げ剛性が高くなるの
で、熱変形を抑制することができ、内管１２の薄肉化が
可能となる。内管１２の薄肉化が可能となることから、
排気管１０の熱容量が小さくなり、排気ガス浄化触媒の
暖機性能の向上が図れる。さらに、曲げ加工が容易とな
るので、排気管１０の曲管部への適用も可能となる。な
お、凸部２４ａと外管１４とを接合する固定部１６は、
第３実施例と同様に軸方向端部の一方のみである。10 to 11 show a modification of the third embodiment. In the third embodiment, the uneven portion 24 is provided only on the fixed portion 16, but as shown in FIG. 11, the uneven portion 24 is formed over the entire length of the inner pipe 12 in this modification. As a result, the gap between the inner tube 12 and the outer tube 14 is kept constant, and there is no need to use a wire mesh. Further, since the unevenness 24 is formed over the entire length of the inner pipe 12, the bending rigidity of the inner pipe 12 is increased, so that thermal deformation can be suppressed and the inner pipe 12 can be made thin. Since it is possible to make the inner tube 12 thinner,
The heat capacity of the exhaust pipe 10 is reduced, and the warm-up performance of the exhaust gas purification catalyst can be improved. Furthermore, since the bending process is facilitated, the exhaust pipe 10 can be applied to the curved pipe portion. The fixing portion 16 that joins the convex portion 24a and the outer tube 14 is
Similar to the third embodiment, only one of the axial end portions is provided.
【００１８】つぎに、第４実施例に特有な構成および作
用について説明する。図１２に示すように、内管１２と
外管１４は、熱膨張率が異なる金属材料から構成されて
いる。内管１２と外管１４の熱膨張率は、内管１２と外
管１４の周方向の熱膨張量がほぼ同じとなるような値に
設定されている。内管１２は、高温の排気ガスが直接接
触するので、熱膨張量を小に抑えるために熱膨張率は小
となっており、外管１４は内管１２よりも温度が多少低
くなるので、熱膨張率は内管１２に比べて大となってい
る。Next, the structure and operation peculiar to the fourth embodiment will be described. As shown in FIG. 12, the inner pipe 12 and the outer pipe 14 are made of metal materials having different coefficients of thermal expansion. The thermal expansion coefficients of the inner pipe 12 and the outer pipe 14 are set to values such that the thermal expansion amounts of the inner pipe 12 and the outer pipe 14 in the circumferential direction are substantially the same. Since the high temperature exhaust gas is in direct contact with the inner pipe 12, the coefficient of thermal expansion is small in order to keep the amount of thermal expansion small, and the temperature of the outer pipe 14 is slightly lower than that of the inner pipe 12. The coefficient of thermal expansion is larger than that of the inner tube 12.
【００１９】第４実施例では、内管１２と外管１４の熱
膨張量がほぼ同じとなるので、周方向の熱膨張差はほと
んど生じない。したがって、内管１２と外管１４の固定
部１６およびその近傍には大きな熱応力は生じなくな
り、内管１２が薄肉であっても損傷は生じない。また、
熱膨張差がほとんど生じないことから、第１実施例ない
し第３実施例のように、熱膨張吸収手段としての凹凸部
２０、２２、２４も不要となり、排気管１０の構造は従
来と同じでよい。In the fourth embodiment, the thermal expansion amounts of the inner tube 12 and the outer tube 14 are substantially the same, so there is almost no difference in thermal expansion in the circumferential direction. Therefore, large thermal stress does not occur in the fixed portion 16 of the inner pipe 12 and the outer pipe 14 and the vicinity thereof, and no damage occurs even if the inner pipe 12 is thin. Also,
Since there is almost no difference in thermal expansion, the concave and convex portions 20, 22, and 24 as the thermal expansion absorbing means are unnecessary as in the first to third embodiments, and the structure of the exhaust pipe 10 is the same as the conventional one. Good.
【００２０】第１実施例ないし第３実施例における凹凸
部２０、２２、２４の成形方法として、金型プレス成
形、ロール転写成形、液圧成形を用いるのが生産効率の
点から望ましいが、これに限定されるものではない。From the viewpoint of production efficiency, it is preferable to use die press molding, roll transfer molding, or hydraulic molding as a method of molding the uneven portions 20, 22, 24 in the first to third embodiments. It is not limited to.
【００２１】[0021]
（１）請求項１の排気二重管構造によれば、内管と外管
との固定部に、内管と外管との周方向の熱膨張差を吸収
する熱膨張吸収手段を設けるようにしたので、固定部お
よびその近傍には熱膨張差に起因する大きな熱応力は発
生しなくなり、熱応力による排気管の損傷を防止するこ
とができる。 （２）請求項２の排気二重管構造によれば、固定部にお
ける内管の周方向外面に形成された凹凸部のうちの凸部
に、外管を固定しているので、凹部の変形によって熱膨
張差を吸収することができる。 （３）請求項３の排気二重管構造によれば、内管と外管
との周方向の熱膨張量がほぼ同じとなるように内管と外
管との熱膨張率を変えたので、周方向の熱膨張差がほと
んど生じなくなり、排気管の構造を変えることなく、熱
応力による排気管の損傷を防止することができる。(1) According to the exhaust double pipe structure of claim 1, a thermal expansion absorbing means for absorbing a thermal expansion difference between the inner pipe and the outer pipe in the circumferential direction is provided in the fixed portion between the inner pipe and the outer pipe. Therefore, large thermal stress due to the difference in thermal expansion does not occur in the fixed portion and its vicinity, and damage to the exhaust pipe due to thermal stress can be prevented. (2) According to the exhaust double pipe structure of claim 2, since the outer pipe is fixed to the convex portion of the uneven portion formed on the outer circumferential surface of the inner pipe in the fixing portion, the concave portion is deformed. Can absorb the difference in thermal expansion. (3) According to the exhaust double pipe structure of the third aspect, the thermal expansion coefficients of the inner pipe and the outer pipe are changed so that the thermal expansion amounts of the inner pipe and the outer pipe in the circumferential direction are substantially the same. The difference in thermal expansion in the circumferential direction hardly occurs, and damage to the exhaust pipe due to thermal stress can be prevented without changing the structure of the exhaust pipe.
【図１】本発明の第１実施例に係る排気二重管構造の要
部断面図である。FIG. 1 is a sectional view of an essential part of an exhaust double pipe structure according to a first embodiment of the present invention.
【図２】図１のＡ−Ａ線に沿う断面図である。FIG. 2 is a sectional view taken along line AA of FIG.
【図３】図１の変形例を示す断面図である。FIG. 3 is a cross-sectional view showing a modified example of FIG.
【図４】図３のＢ−Ｂ線に沿う断面図である。4 is a cross-sectional view taken along the line BB of FIG.
【図５】図３の内管の斜視図である。5 is a perspective view of the inner tube of FIG.
【図６】本発明の第２実施例に係る排気二重管構造の要
部断面図である。FIG. 6 is a sectional view of an essential part of an exhaust double pipe structure according to a second embodiment of the present invention.
【図７】図６のＣ−Ｃ線に沿う断面図である。7 is a cross-sectional view taken along the line CC of FIG.
【図８】本発明の第３実施例に係る排気二重管構造の要
部断面図である。FIG. 8 is a sectional view of an essential part of an exhaust double pipe structure according to a third embodiment of the present invention.
【図９】図８のＤ−Ｄ線に沿う断面図である。9 is a sectional view taken along the line DD of FIG.
【図１０】図８の変形例を示す断面図である。10 is a cross-sectional view showing a modified example of FIG.
【図１１】図１０の内管の斜視図である。11 is a perspective view of the inner pipe of FIG.
【図１２】本発明の第４実施例に係る排気二重管構造の
要部断面図である。FIG. 12 is a cross-sectional view of a main part of an exhaust double pipe structure according to a fourth embodiment of the present invention.
【図１３】従来の排気二重管構造の断面図である。FIG. 13 is a cross-sectional view of a conventional exhaust double pipe structure.
【図１４】図１３の部分拡大断面図である。14 is a partially enlarged sectional view of FIG.
１２ 内管 １４ 外管 １６ 固定部 ２０ 熱膨張吸収手段 ２０ａ 凸部 ２２ｂ 凹部 ２２ 熱膨張吸収手段 ２２ａ 凸部 ２２ｂ 凹部 ２４ 熱膨張吸収手段 ２４ａ 凸部 ２４ｂ 凹部 12 inner pipe 14 outer pipe 16 fixing part 20 thermal expansion absorbing means 20a convex portion 22b concave portion 22 thermal expansion absorbing means 22a convex portion 22b concave portion 24 thermal expansion absorbing means 24a convex portion 24b concave portion
Claims (3)
において、該内管と外管との固定部に、内管と外管との
周方向の熱膨張差を吸収する熱膨張吸収手段を設けるこ
とを特徴とする排気二重管構造。1. In an exhaust double pipe formed by fixing an inner pipe and an outer pipe, a fixed portion between the inner pipe and the outer pipe absorbs a difference in thermal expansion between the inner pipe and the outer pipe in a circumferential direction. An exhaust double-pipe structure characterized by comprising thermal expansion absorbing means.
の周方向外面に凹凸部を形成し、該凸部と外管とを固定
して成る請求項１記載の排気二重管構造。2. The exhaust double pipe structure according to claim 1, wherein the thermal expansion absorbing means is formed by forming a concavo-convex portion on a circumferential outer surface of the inner pipe in the fixing portion, and fixing the convex portion and the outer pipe.
において、該内管と外管との周方向の熱膨張量がほぼ同
じとなるように内管と外管との熱膨張率を変えたことを
特徴とする排気二重管構造。3. An exhaust double pipe having an inner pipe and an outer pipe fixed to each other, wherein the inner pipe and the outer pipe are arranged so that the thermal expansion amounts of the inner pipe and the outer pipe are substantially the same. An exhaust double-pipe structure characterized by changing the coefficient of thermal expansion.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20225294A JPH0868319A (en) | 1994-08-26 | 1994-08-26 | Exhaust double-pipe structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20225294A JPH0868319A (en) | 1994-08-26 | 1994-08-26 | Exhaust double-pipe structure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0868319A true JPH0868319A (en) | 1996-03-12 |
Family
ID=16454475
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20225294A Pending JPH0868319A (en) | 1994-08-26 | 1994-08-26 | Exhaust double-pipe structure |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0868319A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20020061821A (en) * | 2001-01-18 | 2002-07-25 | (주)부성파이프 | An exhaust pipe appendage for vehicles |
| KR20020061822A (en) * | 2001-01-18 | 2002-07-25 | (주)부성파이프 | An exhaust pipe appendage for vehicles |
| JP2007154694A (en) * | 2005-12-01 | 2007-06-21 | Nissan Motor Co Ltd | Double-tube type exhaust pipe |
| JP2007321569A (en) * | 2006-05-30 | 2007-12-13 | Honda Motor Co Ltd | Muffler structure |
| JP2011127607A (en) * | 2009-12-19 | 2011-06-30 | J Eberspecher Gmbh & Co Kg | Exhaust gas treatment device |
-
1994
- 1994-08-26 JP JP20225294A patent/JPH0868319A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20020061821A (en) * | 2001-01-18 | 2002-07-25 | (주)부성파이프 | An exhaust pipe appendage for vehicles |
| KR20020061822A (en) * | 2001-01-18 | 2002-07-25 | (주)부성파이프 | An exhaust pipe appendage for vehicles |
| JP2007154694A (en) * | 2005-12-01 | 2007-06-21 | Nissan Motor Co Ltd | Double-tube type exhaust pipe |
| JP4692252B2 (en) * | 2005-12-01 | 2011-06-01 | 日産自動車株式会社 | Double-pipe exhaust pipe |
| JP2007321569A (en) * | 2006-05-30 | 2007-12-13 | Honda Motor Co Ltd | Muffler structure |
| JP2011127607A (en) * | 2009-12-19 | 2011-06-30 | J Eberspecher Gmbh & Co Kg | Exhaust gas treatment device |
| EP2336518B1 (en) * | 2009-12-19 | 2017-06-21 | Eberspächer Exhaust Technology GmbH & Co. KG | Exhaust gas treatment device |
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