JP4877825B2

JP4877825B2 - EGR pipe

Info

Publication number: JP4877825B2
Application number: JP2007235765A
Authority: JP
Inventors: 隆之鈴木; 和秀紀平
Original assignee: Daihatsu Motor Co Ltd; Toyota Motor Corp
Current assignee: Daihatsu Motor Co Ltd; Toyota Motor Corp
Priority date: 2007-09-11
Filing date: 2007-09-11
Publication date: 2012-02-15
Anticipated expiration: 2027-09-11
Also published as: JP2009068377A

Description

本発明は、排気系と吸気系とを結ぶＥＧＲ配管、特に、排気系から排気ガスを取り出すＥＧＲパイプの管路途中に設けられた蛇腹部を有するＥＧＲ配管に関するものである。 The present invention relates to an EGR pipe connecting an exhaust system and an intake system, and more particularly to an EGR pipe having a bellows portion provided in the middle of an EGR pipe that extracts exhaust gas from the exhaust system.

ディーゼルエンジンは、熱効率が高く、燃費が良いため、地球温暖化防止という観点から優れた特徴を持っているが、排気中に粒子状物質（ＰＭ）や窒素酸化物（ＮＯｘ）が含まれているため、昨今の環境保護意識の高まりにつれて、規制が急速に厳しくなってきている。ＥＧＲ（Exhaust Gas Recirculation、排気ガス再循環）装置は、ディーゼルエンジンからの排気ガスの一部を吸気系に戻し、混合気が燃焼する時の燃焼温度を所定の温度以下にしてＮＯｘの生成量を抑える装置であり、ＥＧＲクーラは、排気ガスの一部を吸気系に戻す途中に装着され、排気ガスを冷やしてエンジンに送り込む働きをする。ディーゼルエンジンの排気系から排出された排気ガスは、ＥＧＲ配管を介してこのようなＥＧＲ装置ないしはＥＧＲクーラに導入され、エンジンの吸気系に還流されている。 Diesel engines have excellent characteristics from the viewpoint of preventing global warming because they have high thermal efficiency and good fuel efficiency, but they contain particulate matter (PM) and nitrogen oxides (NOx) in the exhaust. Therefore, regulations are becoming stricter rapidly as the recent awareness of environmental protection increases. The EGR (Exhaust Gas Recirculation) device returns part of the exhaust gas from the diesel engine to the intake system, and reduces the combustion temperature when the air-fuel mixture burns to a predetermined temperature or less to reduce the amount of NOx produced. The EGR cooler is a device that suppresses a part of the exhaust gas and returns it to the intake system to cool the exhaust gas and send it to the engine. Exhaust gas discharged from the exhaust system of the diesel engine is introduced into such an EGR device or an EGR cooler via the EGR pipe, and is returned to the intake system of the engine.

このエンジンの排気系と吸気系とを結ぶＥＧＲ配管は、その上流側端部がエンジンヘッド内の排気ポートから分岐してヘッド側部に開口する排気ガス取り出しポートのＥＧＲポート開口部に接続され、その下流側端部がＥＧＲ装置ないしはＥＧＲクーラのＥＧＲ導入開口部に接続される。このＥＧＲ配管には、ＥＧＲポート開口部とＥＧＲ導入開口部に接続する際の組み付け作業性や、ＥＧＲ配管内を流れる排気ガスの温度変化による膨張負荷、膨張収縮の繰り返し負荷などに対する耐性を向上させるため、その管路途中に、軸心方向ならびに軸心と垂直な方向に対して可撓性を有する蛇腹部（ベローズ）が設けられている（特許文献１、２参照）。 The EGR pipe connecting the exhaust system and the intake system of this engine is connected to the EGR port opening of the exhaust gas take-out port whose upstream end branches off from the exhaust port in the engine head and opens to the head side, The downstream end is connected to the EGR introduction opening of the EGR device or the EGR cooler. This EGR pipe improves the assembly workability when connecting to the EGR port opening and the EGR introduction opening, and resistance to expansion load due to temperature change of exhaust gas flowing in the EGR pipe, and repeated expansion and contraction load Therefore, a bellows having flexibility with respect to the axial direction and the direction perpendicular to the axial center is provided in the middle of the pipe (see Patent Documents 1 and 2).

例えば、特許文献１に開示されたＥＧＲ装置では、ＥＧＲガスの浄化を行う触媒の上流側または下流側に位置するいずれか一方のＥＧＲ管路に、軸方向に伸縮可能または円周方向に回動可能な可動部材（ベローズ）が設けられている。また、特許文献２に開示されたＥＧＲ配管では、半径方向に変位して、軸方向の変位を吸収する可撓性機構、あるいは、軸方向へ潰れて、且つ、半径方向外方へ膨張する蛇腹状部分が介装されている。 For example, in the EGR device disclosed in Patent Document 1, it can be expanded or contracted in the axial direction or rotated in the circumferential direction to one of the EGR pipes located upstream or downstream of the catalyst for purifying EGR gas. A possible movable member (bellows) is provided. In the EGR pipe disclosed in Patent Document 2, a flexible mechanism that is displaced in the radial direction and absorbs the axial displacement, or a bellows that is crushed in the axial direction and expands outward in the radial direction. Shaped part is interposed.

しかしながら、ＥＧＲ配管に設けられた蛇腹部（ベローズ）は、表面積が大きく、車両走行中はかなりな高温になるため、多大な輻射熱が周囲に放射される。また一方では、近年、車両走行性能や燃費性能の向上、排ガス中のＮＯｘ削減等の観点から、数多くの電装品がエンジン搭載空間の周辺部に組み込まれ、排気ガス取り出しポート周辺も非常に手狭な状態になってきており、例えば、この排気ガス取り出しポート周辺には、エンジンを冷却するための冷却水配管等の多くの部品が近接して配置されている。このような限られた空間の中で、この蛇腹部の周辺に配置される冷却水配管等の部品が蛇腹部から放射される輻射熱により熱的ダメージを受けることになる。したがって、冷却水配管等の周辺部品を蛇腹部から放射される輻射熱から保護する必要があるが、上記の特許文献、には全くこの点について触れられていない。 However, the bellows portion (bellows) provided in the EGR pipe has a large surface area and becomes very high temperature while the vehicle is traveling, so that a large amount of radiant heat is radiated to the surroundings. On the other hand, in recent years, from the viewpoints of improving vehicle running performance and fuel efficiency, reducing NOx in exhaust gas, etc., many electrical components have been incorporated in the periphery of the engine mounting space, and the area around the exhaust gas extraction port is very narrow. For example, in the vicinity of the exhaust gas take-out port, many parts such as a cooling water pipe for cooling the engine are arranged close to each other. In such a limited space, components such as cooling water pipes arranged around the bellows portion are thermally damaged by the radiant heat radiated from the bellows portion. Therefore, it is necessary to protect peripheral parts such as cooling water pipes from radiant heat radiated from the bellows part, but the above-mentioned patent document does not mention this point at all.

このような課題に関して、例えば、特許文献３は、排気管の継手装置に関するものであるが、上流側管と下流側管の継手部に耐熱弾性体を設ける構造において、上・下流側管やベローズからの高温の輻射熱により耐熱弾性体が熱劣化することを防止するため、熱遮蔽手段を耐熱弾性体から離間して設置することを開示している。
特開２００３−２１４２６１号公報特開２００６−０２９１９７号公報特開平１０−２５９７２０号公報 Regarding such a problem, for example, Patent Document 3 relates to a joint device for an exhaust pipe. In a structure in which a heat-resistant elastic body is provided in a joint portion between an upstream pipe and a downstream pipe, upper and downstream pipes and bellows are provided. In order to prevent the heat-resistant elastic body from being thermally deteriorated by the high-temperature radiant heat from the heat-dissipating element, it is disclosed that the heat shielding means is installed apart from the heat-resistant elastic body.
JP 2003-214261 A JP 2006-029197 A JP-A-10-259720

特許文献３には、第１実施例として、図８に示すように、上流側管１１と下流側管１２とが、伸縮、撓み可能なベローズ１３にて気密に接続され、上流側管１１の外周面に固定された支持腕１４（第１の支持手段）と下流側管１２の外周面に固定された支持腕１５（第２の支持手段）とでゴムまたは樹脂からなる耐熱弾性体１６を挟持するとともに、上流側管１１、下流側管１２およびベローズ１３からの輻射熱が耐熱弾性体１６を直撃しないように遮断する熱遮蔽手段１７を耐熱弾性体１６から離間した状態で支持腕１４に支持して配置している。特許文献３には、上記の形態の他に、第２〜第６実施例が記載されているが、いずれも上流側管１１に固定された第１の支持手段１４と下流側管１２に固定された第２の支持手段１５とで耐熱弾性体１６を挟持するものであり、第１または第２の支持手段１４、１５により支持された熱遮蔽手段１７を耐熱弾性体１６から離間して配置している。 In Patent Document 3, as shown in FIG. 8, as a first example, an upstream pipe 11 and a downstream pipe 12 are hermetically connected by a bellows 13 that can be expanded and contracted, and the upstream pipe 11 A heat-resistant elastic body 16 made of rubber or resin is composed of a support arm 14 (first support means) fixed to the outer peripheral surface and a support arm 15 (second support means) fixed to the outer peripheral surface of the downstream pipe 12. While being sandwiched, the heat shield means 17 that blocks the radiant heat from the upstream pipe 11, the downstream pipe 12 and the bellows 13 from directly hitting the heat resistant elastic body 16 is supported by the support arm 14 in a state of being separated from the heat resistant elastic body 16. It is arranged. Patent Document 3 describes the second to sixth examples in addition to the above-described embodiment, and both are fixed to the first support means 14 and the downstream pipe 12 fixed to the upstream pipe 11. The heat-resistant elastic body 16 is sandwiched between the second support means 15 and the heat shielding means 17 supported by the first or second support means 14, 15 is spaced from the heat-resistant elastic body 16. is doing.

このように遮熱板（熱遮蔽手段１７）の支持部（第１または第２の支持手段１４、１５）が蛇腹部（ベローズ１３）の上流側と下流側との間に跨って配置されている構造を、排気管よりもさらに高温の排気ガスが流れるＥＧＲ配管に適用しようとすると、遮熱板と蛇腹部との間に形成された空間に熱がこもり、遮熱板自体も高温となり、周辺部品に対する遮熱効率が低下することになる。また、遮熱板に寸法吸収手段を設ける必要が生じ、構造が複雑となる。 In this way, the support portion (first or second support means 14, 15) of the heat shield (heat shield means 17) is disposed between the upstream side and the downstream side of the bellows part (bellows 13). If the structure is applied to EGR piping through which exhaust gas having a temperature higher than that of the exhaust pipe flows, heat is trapped in the space formed between the heat shield plate and the bellows part, and the heat shield plate itself becomes high temperature, The heat shielding efficiency with respect to peripheral parts will fall. In addition, it is necessary to provide dimension absorption means on the heat shield plate, and the structure becomes complicated.

したがって、従来、蛇腹部から放射される輻射熱により冷却水配管等の周辺部品が熱的ダメージを受けるのを防止するため、冷却水配管には熱害に対するプロテクタを巻いて遮熱するなどの対策が一般的には採られてきた。しかしながら、プロテクタを巻く遮熱対策はコスト的に高価なものとなる。 Therefore, conventionally, in order to prevent the peripheral parts such as the cooling water pipe from being thermally damaged by the radiant heat radiated from the bellows portion, the cooling water pipe is provided with a protector against heat damage and shielded from heat. Generally taken. However, the heat shield measures around the protector are costly.

また、ＥＧＲ配管には、高温の排気ガスが導入されるため、車両走行中においてはＥＧＲ配管の上流側ではかなりの高温（最高温度６００℃程度）になり、ＥＧＲクーラに接続される下流側では１００〜２００℃程度の比較的低い温度になる。また、エンジン停止が停止されて、ＥＧＲ配管に排気ガスが導入されない状態では、ＥＧＲ配管の上流側の温度も低下し、その状態が長く維持されると、室温近くにまで低下する。遮熱板が溶接によりＥＧＲ配管に取り付けられる位置によっては、溶接部に、車両走行時と停止時との間で大きな温度変化が生じることになり、この温度変化の繰り返しによる熱疲労が溶接部にかかり、溶接部に熱疲労クラックが発生することもある。熱疲労クラックが進展して、遮熱板がＥＧＲ配管から脱落するような事態になると、車両の安全走行を脅かし、万一の場合には事故発生に繋がることもあり得る。 In addition, since high-temperature exhaust gas is introduced into the EGR pipe, the temperature is considerably high (up to about 600 ° C.) upstream of the EGR pipe while the vehicle is running, and on the downstream side connected to the EGR cooler. It becomes a relatively low temperature of about 100 to 200 ° C. Further, in a state where the engine stop is stopped and no exhaust gas is introduced into the EGR pipe, the temperature on the upstream side of the EGR pipe also decreases, and when this state is maintained for a long time, the temperature decreases to near room temperature. Depending on the position at which the heat shield plate is attached to the EGR pipe by welding, a large temperature change occurs in the welded part between when the vehicle travels and when it stops, and thermal fatigue due to repeated temperature changes occurs in the welded part. This may cause thermal fatigue cracks in the weld. If the thermal fatigue crack progresses and the heat shield plate falls off the EGR pipe, it may threaten the safe driving of the vehicle, and in the unlikely event, an accident may occur.

本発明は、以上のような課題に鑑みて為されたものであり、遮熱板から外方に位置する冷却水配管等の周辺部品に蛇腹部からの輻射熱の影響が及ぶのを防止するとともに、遮熱板をＥＧＲパイプに取り付ける溶接部に熱疲労クラックが発生することを防止して、溶接部の品質ならびに信頼性を向上させることができるＥＧＲ配管を提供することを目的としている。 The present invention has been made in view of the problems as described above, and prevents the influence of radiant heat from the bellows part on peripheral parts such as cooling water pipes located outward from the heat shield plate. An object of the present invention is to provide an EGR pipe capable of preventing the occurrence of thermal fatigue cracks in the welded portion where the heat shield plate is attached to the EGR pipe and improving the quality and reliability of the welded portion.

上記課題を解決することを目的として、請求項１に係る発明のＥＧＲ配管は、排気系と吸気系とを結ぶＥＧＲ配管において、排気系から排気ガスを取り出すＥＧＲパイプの管路途中に設けられた蛇腹部の下流側に、該蛇腹部の少なくとも一方の側面を覆う遮熱板が溶接により取り付けられ、前記遮熱板は、前記ＥＧＲパイプへの取付部と、該取付部から上流側に向けて拡幅され、前記ＥＧＲパイプから次第に離間するように形成された扇状部と、該扇状部からさらに上流側に向けて延設され、前記蛇腹部から離間した状態で断面円弧状または断面直線状に形成されて前記蛇腹部の少なくとも一方の側面を覆う遮熱部とを備えていることを特徴とするものである。 In order to solve the above problems, the EGR pipe of the invention according to claim 1 is provided in the EGR pipe connecting the exhaust system and the intake system in the middle of the EGR pipe for extracting the exhaust gas from the exhaust system. A heat shield plate covering at least one side surface of the bellows portion is attached to the downstream side of the bellows portion by welding, and the heat shield plate is attached to the EGR pipe and from the attachment portion toward the upstream side. A fan-shaped portion that is widened and formed so as to be gradually separated from the EGR pipe, and extends further upstream from the fan-shaped portion, and is formed in a cross-section arc shape or a straight cross-section shape in a state of being separated from the bellows portion. And a heat shield portion covering at least one side surface of the bellows portion .

請求項１に係る発明のＥＧＲ配管によれば、遮熱板が蛇腹部の少なくとも一方の側面を覆うことによって、遮熱板から外方に位置する冷却水配管等の周辺部品に、蛇腹部からの輻射熱の影響が及ぶのを防止することができる。また、遮熱板が蛇腹部の下流側で溶接により取り付けられることによって、高温の排気ガスがＥＧＲ配管の管路途中で冷却されながら蛇腹部の下流側に至るため、蛇腹部の下流側位置におけるＥＧＲパイプの温度は上流側に比べて低くなる。したがって、エンジン始動および車両走行によって、ＥＧＲ配管に高温の排気ガスが流れ、ＥＧＲパイプおよび蛇腹部は高温の状態となるが、蛇腹部の下流側位置においては温度変化が上流側位置よりも少なく、この温度変化によって遮熱板の取付部（溶接部）にかかる熱疲労の程度が軽減されるため、溶接部に熱疲労クラックが発生することを確実に防止することができ、溶接部の品質ならびに信頼性を向上させることができる。 According to the EGR pipe of the invention according to claim 1, the heat shield plate covers at least one side surface of the bellows part, so that the peripheral parts such as the cooling water pipe positioned outward from the heat shield plate are connected from the bellows part. It is possible to prevent the influence of radiant heat. Moreover, since the heat shield plate is attached by welding on the downstream side of the bellows portion, the hot exhaust gas reaches the downstream side of the bellows portion while being cooled in the middle of the EGR pipe, so that the heat shield plate is located at the downstream position of the bellows portion. The temperature of the EGR pipe is lower than that on the upstream side. Therefore, when the engine starts and the vehicle travels, high-temperature exhaust gas flows through the EGR pipe, and the EGR pipe and the bellows part are in a high temperature state, but the temperature change at the downstream position of the bellows part is less than the upstream position, This temperature change reduces the degree of thermal fatigue applied to the heat shield plate mounting part (welded part), so it is possible to reliably prevent the occurrence of thermal fatigue cracks in the welded part, Reliability can be improved.

請求項２に係る発明のＥＧＲ配管は、請求項１に記載のＥＧＲ配管において、前記遮熱板は、前記ＥＧＲパイプへの取付部と、該取付部から上流側に向けて拡幅され、前記ＥＧＲバイプから次第に離間するように形成された扇状部と、該扇状部からさらに上流側に向けて延設され、前記蛇腹部から離間した状態で断面円弧状に形成されて前記蛇腹部の少なくとも一方の側面を覆う遮熱部とを備えることを特徴とするものである。 An EGR pipe according to a second aspect of the present invention is the EGR pipe according to the first aspect, wherein the heat shield plate is widened from the mounting portion to the EGR pipe and from the mounting portion toward the upstream side. A fan-shaped portion formed so as to be gradually separated from the vip, and further extended toward the upstream side from the fan-shaped portion, and is formed in a circular arc shape in a state of being separated from the bellows portion, and at least one of the bellows portions The heat-shielding part which covers a side surface is provided, It is characterized by the above-mentioned.

また、遮熱板が取付部と扇状部と遮熱部とを備えて構成され、遮熱板のＥＧＲパイプへの取付部と蛇腹部の少なくとも一方の側面を覆う遮熱部との間に扇状部が介在することにより、片持ち構造からなる簡単な構造の遮熱板とすることができ、ＥＧＲパイプへの取付部を蛇腹部から離れた下流側の適所に配置することができる。これにより、取付部（溶接部）にかかる熱疲労を軽減して溶接部に熱疲労クラックが発生することを確実に防止することができる。また、扇状部が上流側に向けて拡幅され、ＥＧＲバイプから次第に離間するように形成されるため、取付部（溶接部）の寸法を小さく（遮熱板重量を低減して取付工数を削減）するとともに、冷却水配管等の周辺部品に対して蛇腹部からの輻射熱の影響が及ばない適正な大きさ、形状の遮熱部を蛇腹部から離間した状態で形成することができる。そして、その結果、蛇腹部からの輻射熱が遮熱部および扇状部で遮られて、冷却水配管等の周辺部品に蛇腹部からの輻射熱の影響が確実に及ばないようにすることができる。 Further, the heat shield plate is configured to include an attachment portion, a fan-like portion, and a heat shield portion, and a fan-like shape is provided between the attachment portion of the heat shield plate to the EGR pipe and the heat shield portion covering at least one side surface of the bellows portion. By interposing the part, a heat shield plate having a simple structure having a cantilever structure can be obtained, and the attaching part to the EGR pipe can be arranged at a suitable position on the downstream side away from the bellows part. Thereby, the thermal fatigue concerning an attachment part (welding part) can be reduced, and it can prevent reliably that a thermal fatigue crack generate | occur | produces in a welding part. In addition, the fan-shaped part is widened toward the upstream side and is formed so as to be gradually separated from the EGR vip, so the size of the mounting part (welded part) is reduced (the heat shield plate weight is reduced and the mounting man-hour is reduced). In addition, an appropriate size and shape of the heat shield portion that is not affected by the radiant heat from the bellows portion with respect to peripheral components such as cooling water pipes can be formed in a state of being separated from the bellows portion. As a result, the radiant heat from the bellows part is blocked by the heat shield part and the fan-like part, and the peripheral parts such as the cooling water pipe can be reliably prevented from being affected by the radiant heat from the bellows part.

請求項２に係る発明のＥＧＲ配管は、請求項１に記載のＥＧＲ配管において、前記遮熱部の前記ＥＧＲパイプの軸心に垂直な方向の両端部すなわち、前記扇状部から延設された前記遮熱部の、延設された方向に平行な両側端部は前記蛇腹部の表面から離間して、前記遮熱部と前記蛇腹部との間が開口されていることを特徴とするものである。 An EGR pipe according to a second aspect of the present invention is the EGR pipe according to the first aspect , wherein both ends of the heat shield portion in a direction perpendicular to the axis of the EGR pipe, that is, the fan-shaped portion are extended. Both end portions of the heat shield portion parallel to the extending direction are separated from the surface of the bellows portion, and the space between the heat shield portion and the bellows portion is opened. is there.

請求項２に係る発明のＥＧＲ配管によれば、遮熱部のＥＧＲパイプの軸心に垂直な方向の両端部すなわち、前記扇状部から延設された前記遮熱部の、延設された方向に平行な両側端部が蛇腹部の表面から離間して、遮熱部と蛇腹部との間が開口されているため、遮熱部と蛇腹部との間に形成される空間が風の通路となって、蛇腹部の放熱冷却が妨げられることがない。これによって、遮熱部と蛇腹部との間に形成される空間に熱がこもらず、ＥＧＲパイプ、蛇腹部および遮熱板の冷却と遮熱部の外方に位置する冷却水配管等の周辺部品への遮熱の両者が促進されることになる。 According to the EGR pipe of the invention according to claim 2 , both ends of the heat shield portion in the direction perpendicular to the axis of the EGR pipe, that is, the extending direction of the heat shield portion extended from the fan-shaped portion. Since both side end portions parallel to the surface of the bellows portion are spaced apart from each other and the space between the heat shield portion and the bellows portion is opened, the space formed between the heat shield portion and the bellows portion is a wind passage. Thus, the heat radiation cooling of the bellows portion is not hindered. As a result, heat does not accumulate in the space formed between the heat shield and the bellows, and the periphery of the EGR pipe, the bellows and the heat shield plate, and the cooling water pipe located outside the heat shield Both heat insulation to the parts will be promoted.

本発明によれば、ＥＧＲ配管において、遮熱板から外方に位置する冷却水配管等の周辺部品に蛇腹部からの輻射熱の影響が及ぶのを防止するとともに、遮熱板をＥＧＲパイプに取り付ける溶接部に熱疲労クラックが発生することを防止して、溶接部の品質ならびに信頼性を向上させることができる。また、遮熱板自体を簡単な構造のものとし、周辺部品に蛇腹部からの輻射熱の影響が及ばない適正な大きさ、形状のものとすることができる。 According to the present invention, in the EGR pipe, the peripheral parts such as the cooling water pipe positioned outward from the heat shield plate are prevented from being affected by the radiant heat from the bellows portion, and the heat shield plate is attached to the EGR pipe. The occurrence of thermal fatigue cracks in the welded portion can be prevented, and the quality and reliability of the welded portion can be improved. Further, the heat shield plate itself can have a simple structure, and can have a proper size and shape so that the peripheral parts are not affected by the radiant heat from the bellows part.

以下、本発明のＥＧＲ配管に係る最良の実施の形態について、図面に基づき詳細に説明する。なお、下記に開示される実施の形態はすべての点で例示であって、制限的なものではないと考えられるべきである。本発明の技術的範囲は、実施の形態で開示された内容ではなく、特許請求の範囲の記載によって示され、さらに、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれると解されるべきである。 DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best embodiment according to the EGR pipe of the present invention will be described in detail with reference to the drawings. It should be understood that the embodiments disclosed below are illustrative in all respects and are not restrictive. The technical scope of the present invention is shown not by the content disclosed in the embodiment but by the description of the scope of claims, and further includes all modifications within the meaning and scope equivalent to the scope of claims. Should be understood.

（実施の形態１）
先ず、本発明の実施の形態１に係るＥＧＲ配管１の配置位置周辺の状態およびＥＧＲ配管１の構造と形状について、図１〜図５に基づき説明する。図１は、本発明の実施の形態１に係るＥＧＲ配管の配置位置周辺の状態を説明するための平面図であり、また、図２は、このＥＧＲ配管の構造と形状を説明するための平面図であり、図２は、このＥＧＲ配管の構造と形状を説明するための側面図である。さらに、図４は、ＥＧＲ配管に取り付けられた遮熱板周辺の状態の構造と形状を説明するための断面図であり、図５は、この遮熱板の構造と形状を説明するための、（ａ）はＥＧＲパイプの軸心に垂直な方向での断面図であり、（ｂ）はＥＧＲパイプの軸心に平行な方向での断面図である。 (Embodiment 1)
First, the state around the arrangement position of the EGR pipe 1 according to the first embodiment of the present invention and the structure and shape of the EGR pipe 1 will be described with reference to FIGS. FIG. 1 is a plan view for explaining a state around an arrangement position of an EGR pipe according to Embodiment 1 of the present invention, and FIG. 2 is a plan view for explaining the structure and shape of the EGR pipe. FIG. 2 is a side view for explaining the structure and shape of the EGR pipe. Further, FIG. 4 is a cross-sectional view for explaining the structure and shape of the state around the heat shield plate attached to the EGR pipe, and FIG. 5 is a diagram for explaining the structure and shape of the heat shield plate. (A) is sectional drawing in the direction perpendicular | vertical to the axis of an EGR pipe, (b) is sectional drawing in the direction parallel to the axis of an EGR pipe.

本実施の形態１において、エンジンの排気系と吸気系とを結ぶＥＧＲ配管１は、上流側ＥＧＲパイプ２と、下流側ＥＧＲパイプ３と、上流側ＥＧＲパイプ２と下流側ＥＧＲパイプ３との間に接続された蛇腹部４と、蛇腹部４の下流側に溶接により取り付けられた遮熱板５とで構成されている。上流側ＥＧＲパイプ２の上流側端部２ａがエンジンヘッド７内の排気ポートから分岐してヘッド７側部に開口する排気ガス取り出しポート８のＥＧＲポート開口部８ａに接続され、下流側ＥＧＲパイプ３の下流側端部３ａがＥＧＲクーラ９のＥＧＲ導入開口部９ａに接続されている。 In the first embodiment, the EGR pipe 1 that connects the exhaust system and the intake system of the engine includes an upstream EGR pipe 2, a downstream EGR pipe 3, and an upstream EGR pipe 2 and a downstream EGR pipe 3. And a heat shield 5 attached to the downstream side of the bellows portion 4 by welding. The upstream end 2a of the upstream EGR pipe 2 branches from the exhaust port in the engine head 7 and is connected to the EGR port opening 8a of the exhaust gas take-out port 8 that opens to the side of the head 7 and is connected to the downstream EGR pipe 3 The downstream end 3 a of the EGR is connected to the EGR introduction opening 9 a of the EGR cooler 9.

蛇腹部４は、ＥＧＲ配管１の管路途中にあって軸心方向ならびに軸心と垂直な方向に対して可撓性を有する配管部分であり、ＥＧＲポート開口部８ａとＥＧＲ導入開口部９ａに接続する際の組み付け作業性や、ＥＧＲ配管１内を流れる排気ガスの温度変化による膨張負荷、膨張収縮の繰り返し負荷などに対する耐性を向上させるとともに、エンジン６からの振動がＥＧＲクーラ９側に伝達されるのを抑止するものである。 The bellows part 4 is a pipe part that is in the middle of the EGR pipe 1 and has flexibility in the axial center direction and the direction perpendicular to the axial center, and is provided in the EGR port opening 8a and the EGR introduction opening 9a. Assembling workability at the time of connection, resistance to expansion load due to temperature change of exhaust gas flowing in the EGR pipe 1, and repeated expansion and contraction load are improved, and vibration from the engine 6 is transmitted to the EGR cooler 9 side. Is deterred.

本実施の形態１において、ＥＧＲ配管１は、蛇腹部４の少なくとも一方の側面、すなわち、周辺に配置される冷却水配管１０等の部品に対向する側の側面を覆う形状に形成された遮熱板５が蛇腹部４の下流側に溶接により取り付けられている。 In the first embodiment, the EGR pipe 1 is a heat shield formed in a shape that covers at least one side surface of the bellows portion 4, that is, a side surface facing a component such as the cooling water pipe 10 disposed in the periphery. A plate 5 is attached to the downstream side of the bellows portion 4 by welding.

遮熱板５は、下流側ＥＧＲパイプ３への取付部５ａと、この取付部５ａから上流側に向けて拡幅され、下流側ＥＧＲバイプ３から次第に離間するように形成された扇状部５ｂと、この扇状部５ｂからさらに上流側に向けて延設され、蛇腹部４から離間するように形成された遮熱部５ｃとを備えている。 The heat shield 5 is attached to the downstream EGR pipe 3 with a mounting portion 5a, and the fan-shaped portion 5b that is widened from the mounting portion 5a toward the upstream side and gradually separated from the downstream EGR vip 3, A heat shield portion 5c is provided extending from the fan-shaped portion 5b toward the upstream side and formed so as to be separated from the bellows portion 4.

本実施の形態１において、遮熱板５は、取付部５ａが下流側ＥＧＲパイプ３に外接する断面円弧形状に形成され、遮熱部５ｃがＥＧＲパイプ２、３および蛇腹部４と同心円状の断面円弧形状に形成されている。また、扇状部５ｂは、ＥＧＲパイプ２、３および蛇腹部４と同心円状の断面円弧形状をもって下流側ＥＧＲパイプ３への取付部５ａから上流側に向けて拡幅されるとともに、蛇腹部４から次第に離間する形状に形成され、下流側で取付部５ａに、上流側で遮熱部５ｃに接続している。また、取付部５ａの下流側端部と側方側の両端部とが溶接され、溶接部５ｄにより下流側ＥＧＲパイプ３に固定されている（図４参照）。 In the first embodiment, the heat shield plate 5 is formed in a circular arc shape in which the mounting portion 5a circumscribes the downstream EGR pipe 3, and the heat shield portion 5c is concentric with the EGR pipes 2, 3 and the bellows portion 4. The cross-sectional arc shape is formed. The fan-shaped portion 5b is widened from the attachment portion 5a to the downstream EGR pipe 3 toward the upstream side with a concentric circular arc shape concentric with the EGR pipes 2, 3 and the bellows portion 4, and gradually from the bellows portion 4. It is formed in a spaced shape, and is connected to the mounting portion 5a on the downstream side and to the heat shield portion 5c on the upstream side. Further, the downstream end portion and the both side end portions of the attachment portion 5a are welded and fixed to the downstream EGR pipe 3 by the weld portion 5d (see FIG. 4).

遮熱部５ｃのＥＧＲパイプ２、３の軸心方向（長手方向）の長さＬ１が蛇腹部４の軸心方向の長さＬ２と略同じ長さに設定され、遮熱部５ｃが蛇腹部４の軸心に平行に配設されることにより、遮熱部５ｂはその長手方向において蛇腹部４の一方の側面を覆うように構成されている。 The length L1 in the axial direction (longitudinal direction) of the EGR pipes 2 and 3 of the heat shield 5c is set to be substantially the same as the length L2 of the bellows 4 in the axial direction, and the heat shield 5c is the bellows. The heat shield 5b is configured to cover one side surface of the bellows 4 in the longitudinal direction by being disposed in parallel with the axis 4.

また、遮熱部５ｃにおけるＥＧＲパイプ２、３（蛇腹部４）の円周方向への展開角θが１３０°に設定されており、遮熱部５ｃのＥＧＲパイプ２、３の軸心に垂直な方向の両側端部５ｅは、蛇腹部４の表面から離間しており、遮熱部５ｃと蛇腹部４との間が開口されている。 Further, the deployment angle θ in the circumferential direction of the EGR pipes 2 and 3 (the bellows portion 4) in the heat shield portion 5c is set to 130 °, and is perpendicular to the axis of the EGR pipes 2 and 3 in the heat shield portion 5c. Both end portions 5e in the right direction are separated from the surface of the bellows portion 4, and an opening is formed between the heat shield portion 5c and the bellows portion 4.

遮熱板５が蛇腹部４の下流側に溶接により取り付けられることによって、高温の排気ガスがＥＧＲ配管１の管路途中で冷却されながら蛇腹部４の下流側に至るため、蛇腹部４の下流側位置における下流側ＥＧＲパイプ３の温度は上流側に比べて低くなる。特に、表面積の大きな蛇腹部４において多く放熱されるため、蛇腹部４の下流側における温度は相当低くなる。したがって、エンジン始動および車両走行によって、ＥＧＲ配管１に高温の排気ガスが流れ、上流側ＥＧＲパイプ２および蛇腹部４は高温の状態となるが、蛇腹部４の下流側位置においては温度変化が上流側位置よりも少なく、この温度変化によって遮熱板５の溶接部５ｄにかかる熱疲労の程度が軽減されるため、溶接部５ｄに熱疲労クラックが発生することを確実に防止することができ、溶接部５ｄの品質ならびに信頼性を向上させることができる。 Since the heat shield plate 5 is attached to the downstream side of the bellows portion 4 by welding, the hot exhaust gas reaches the downstream side of the bellows portion 4 while being cooled in the middle of the EGR pipe 1. The temperature of the downstream EGR pipe 3 at the side position is lower than that at the upstream side. In particular, since a large amount of heat is radiated in the bellows portion 4 having a large surface area, the temperature on the downstream side of the bellows portion 4 becomes considerably low. Therefore, when the engine starts and the vehicle travels, high-temperature exhaust gas flows through the EGR pipe 1, and the upstream EGR pipe 2 and the bellows part 4 are in a high temperature state, but the temperature change is upstream at the downstream position of the bellows part 4. Since the degree of thermal fatigue applied to the welded portion 5d of the heat shield plate 5 is reduced by this temperature change less than the side position, it is possible to reliably prevent thermal fatigue cracks from occurring in the welded portion 5d, The quality and reliability of the welded part 5d can be improved.

また、遮熱板５は、蛇腹部４の下流側に取り付けられることによって、蛇腹部４の上流側に取り付けられるよりも、温度の低くなった下流側ＥＧＲパイプ３から遮熱板５への熱伝達が少なくなるため、低い温度になる。 Further, the heat shield plate 5 is attached to the downstream side of the bellows portion 4, so that the heat from the downstream EGR pipe 3 having a lower temperature than the heat shield plate 5 is attached to the upstream side of the bellows portion 4. Lower temperature due to less transmission.

さらに、遮熱板５が取付部５ａと扇状部５ｂと遮熱部５ｃとを備えて構成され、遮熱板５の下流側ＥＧＲパイプ３への取付部５ａと蛇腹部４の少なくとも一方の側面を覆う遮熱部５ｃとの間に扇状部５ｂが介在することにより、片持ち構造からなる簡単な構造の遮熱板５とすることができ、下流側ＥＧＲパイプ３への取付部５ａを蛇腹部４から離れた下流側の適所に配置することができる。これにより、溶接部５ｄにかかる熱疲労を軽減して溶接部５ｄに熱疲労クラックが発生することを確実に防止することができる。 Furthermore, the heat shield plate 5 includes an attachment portion 5 a, a fan-like portion 5 b, and a heat shield portion 5 c, and at least one side surface of the attachment portion 5 a to the downstream EGR pipe 3 of the heat shield plate 5 and the bellows portion 4. The fan-shaped portion 5b is interposed between the heat-shielding portion 5c and the heat-shielding plate 5 having a simple structure having a cantilever structure, and the attachment portion 5a to the downstream EGR pipe 3 is connected to the bellows. It can be arranged at a suitable location on the downstream side away from the section 4. Thereby, thermal fatigue applied to the welded portion 5d can be reduced, and the occurrence of thermal fatigue cracks in the welded portion 5d can be reliably prevented.

また、扇状部５ｂが上流側に向けて拡幅され、下流側ＥＧＲバイプ３から次第に離間するように形成されるため、取付部５ａ（溶接部５ｄ）の寸法を小さく（遮熱板５の重量を低減して取付工数を削減）するとともに、冷却水配管１０等の周辺部品に対して蛇腹部４からの輻射熱の影響が及ばない適正な大きさ、形状の遮熱部５ｃを蛇腹部４から離間した状態で形成することができる。そして、その結果、蛇腹部４からの輻射熱が遮熱部５ｃおよび扇状部５ｂで遮られて、冷却水配管１０等の周辺部品に蛇腹部４からの輻射熱の影響が確実に及ばないようにすることができる。 Moreover, since the fan-shaped part 5b is widened toward the upstream side and is formed so as to be gradually separated from the downstream EGR vip 3, the size of the mounting part 5a (welded part 5d) is reduced (the weight of the heat shield plate 5 is reduced). And the heat shield 5c having an appropriate size and shape that is not affected by the radiant heat from the bellows portion 4 with respect to peripheral components such as the cooling water pipe 10 is separated from the bellows portion 4. Can be formed. As a result, the radiant heat from the bellows portion 4 is blocked by the heat shield portion 5c and the fan-shaped portion 5b, so that the peripheral heat components such as the cooling water pipe 10 are not affected by the radiant heat from the bellows portion 4 with certainty. be able to.

また、遮熱部５ｃにおけるＥＧＲパイプ２、３（蛇腹部４）の円周方向への展開角θが１３０°に設定され、遮熱部５ｃと蛇腹部４との間が開口されることによって、遮熱部５ｃと蛇腹部４の間の空間に空気が流通可能な風の通路が形成されている。車両走行中においては、遮熱部５ｃと蛇腹部４の間の空間を空気が流通し、蛇腹部４の放熱冷却が妨げられることがない。これによって、遮熱部５ｃとＥＧＲパイプ２、３および蛇腹部４との間に形成される空間に熱がこもらず、ＥＧＲパイプ２、３、蛇腹部４および遮熱板５の冷却と遮熱部５ｃの外方に位置する冷却水配管１０等の周辺部品への遮熱の両者が促進されることになる。 Further, the deployment angle θ in the circumferential direction of the EGR pipes 2 and 3 (the bellows portion 4) in the heat shield portion 5c is set to 130 °, and the gap between the heat shield portion 5c and the bellows portion 4 is opened. In the space between the heat shield part 5c and the bellows part 4, a wind passage through which air can flow is formed. While the vehicle is running, air flows through the space between the heat shield 5c and the bellows 4, and the heat radiation cooling of the bellows 4 is not hindered. As a result, heat does not accumulate in the space formed between the heat shield 5c and the EGR pipes 2, 3 and the bellows 4, and the EGR pipes 2, 3, the bellows 4 and the heat shield 5 are cooled and shielded from heat. Both heat insulation to peripheral parts such as the cooling water pipe 10 located outside the portion 5c is promoted.

本実施の形態１においては、遮熱部５ｃにおける蛇腹部４の円周方向への展開角θが１３０°に設定されることによって、遮熱部５ｃと蛇腹部４の間の空間に空気が流通可能な風の通路が形成されているが、この遮熱部５ｃの展開角θは１８０°以下に設定され、周辺に配置される冷却水配管１０等の部品に輻射熱の影響が及ばないように構成されていれば良い。遮熱部５ｃの展開角θが１８０°を超えると、遮熱部５ｃと蛇腹部４の間の空間での空気の流通が阻害されるため、望ましくない。より好ましくは、遮熱部５ｃの展開角θは１３５°以下に設定されるのが良く、この場合、遮熱部５ｃと蛇腹部４の間の空間での空気の流通がより促進され、遮熱板５が冷却されるので、冷却水配管１０等の周辺部品に輻射熱の影響が及ぶのをより効果的に防止することができる。 In the first embodiment, by setting the development angle θ in the circumferential direction of the bellows part 4 in the heat shield part 5c to 130 °, air is introduced into the space between the heat shield part 5c and the bellows part 4. Although a wind passage that can be circulated is formed, the expansion angle θ of the heat shield 5c is set to 180 ° or less so that the radiant heat does not affect the components such as the cooling water pipe 10 arranged in the vicinity. It is sufficient if it is configured. If the expansion angle θ of the heat shield 5c exceeds 180 °, the air flow in the space between the heat shield 5c and the bellows 4 is hindered, which is not desirable. More preferably, the deployment angle θ of the heat shield 5c should be set to 135 ° or less. In this case, the air flow in the space between the heat shield 5c and the bellows 4 is further promoted, and the shield. Since the hot platen 5 is cooled, it is possible to more effectively prevent peripheral components such as the cooling water pipe 10 from being affected by radiant heat.

（実施の形態２）
次に、本発明の実施の形態２に係るＥＧＲ配管１’に取り付けられた遮熱板５’の構造と形状について、図６、図７に基づき説明する。図６は、本発明の実施の形態２に係るＥＧＲ配管の構造と形状を説明するための側面図であり、図７は、このＥＧＲ配管に取り付けられた遮熱板の構造と形状を説明するための、（ａ）はＥＧＲパイプの軸心に垂直な方向での断面図であり、（ｂ）はＥＧＲパイプの軸心に平行な方向での断面図である。なお、この遮熱板５’のＥＧＲパイプ３への取付構造について、実施の形態１において説明したと同様であるので、ここではその説明を省略する。 (Embodiment 2)
Next, the structure and shape of the heat shield 5 ′ attached to the EGR pipe 1 ′ according to Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 6 is a side view for explaining the structure and shape of the EGR pipe according to the second embodiment of the present invention, and FIG. 7 explains the structure and shape of the heat shield attached to the EGR pipe. For this reason, (a) is a cross-sectional view in a direction perpendicular to the axis of the EGR pipe, and (b) is a cross-sectional view in a direction parallel to the axis of the EGR pipe. Since the structure for attaching the heat shield 5 'to the EGR pipe 3 is the same as that described in the first embodiment, the description thereof is omitted here.

本実施の形態２に係る遮熱板５’は、遮熱部５ｃ’が平板形状（断面直線状）に形成されており、扇状部５ｂ’が下流側ＥＧＲパイプ３との取付部５ａでの円弧形状から上流側に向けて平板形状に遷移しながら拡幅され、遮熱部５ｃ’に接続している。 In the heat shield plate 5 ′ according to the second embodiment, the heat shield portion 5 c ′ is formed in a flat plate shape (straight section), and the fan-like portion 5 b ′ is at the attachment portion 5 a with the downstream EGR pipe 3. It is widened while making a transition from a circular arc shape to a flat plate shape toward the upstream side, and is connected to the heat shield 5c ′.

遮熱部５ｃ’のＥＧＲパイプ２、３の軸心方向（長手方向）の長さＬ１が蛇腹部４の軸心方向の長さＬ２と略同じ長さに設定され、遮熱部５ｃ’が蛇腹部４の軸心方向に対して平行になるように配設されることにより、遮熱部５ｃ’はその長手方向において蛇腹部４の一方の側面を覆うように構成されている。 The length L1 in the axial direction (longitudinal direction) of the EGR pipes 2 and 3 of the heat shield part 5c ′ is set to be substantially the same as the length L2 in the axial direction of the bellows part 4, and the heat shield part 5c ′ By being arranged so as to be parallel to the axial center direction of the bellows portion 4, the heat shield portion 5c ′ is configured to cover one side surface of the bellows portion 4 in the longitudinal direction.

また、遮熱部５ｃ’におけるＥＧＲパイプ２、３（蛇腹部４）の円周方向への展開角θが９０°に設定されており、遮熱部５ｃ’のＥＧＲパイプ３の軸心に垂直な方向の両側端部５ｅは、端部側に至るに従って蛇腹部４の表面から次第に離間しており、遮熱部５ｃ’と蛇腹部４との間が実施の形態１で示したものよりも広く開口されることによって、遮熱部５ｃ’と蛇腹部４の間の空間に空気が流通可能なより大きな風の通路が形成されている。車両走行中においては、この広く形成された開口を介して、遮熱部５ｃ’と蛇腹部４の間の空間を多くの空気が流通し、蛇腹部４の放熱冷却が妨げられることがない。これによって、遮熱部５ｃ’とＥＧＲバイプ２、３および蛇腹部４との間に形成される空間に熱がこもらず、ＥＧＲパイプ２、３、蛇腹部４および遮熱板５’の冷却と遮熱部５ｃ’の外方に位置する冷却水配管１０等の周辺部品への遮熱の両者が促進されることになる。 Further, the deployment angle θ in the circumferential direction of the EGR pipes 2 and 3 (the bellows portion 4) in the heat shield portion 5c ′ is set to 90 °, and is perpendicular to the axis of the EGR pipe 3 in the heat shield portion 5c ′. Both side end portions 5e in a certain direction are gradually separated from the surface of the bellows portion 4 toward the end portion side, and the space between the heat shield portion 5c ′ and the bellows portion 4 is more than that shown in the first embodiment. Due to the wide opening, a larger air passage through which air can flow is formed in the space between the heat shield 5c ′ and the bellows 4. During traveling of the vehicle, a large amount of air flows through the space between the heat shield 5c 'and the bellows part 4 through the wide opening, and the heat radiation cooling of the bellows part 4 is not hindered. As a result, no heat is accumulated in the space formed between the heat shield 5c ′ and the EGR vipes 2, 3 and the bellows 4, and the EGR pipes 2, 3, the bellows 4 and the heat shield 5 ′ are cooled. Both of heat shielding to peripheral parts such as the cooling water pipe 10 located outside the heat shielding part 5c ′ are promoted.

上記の実施の形態１、２では、蛇腹部４の一方の側面を覆う遮熱部５ｃ、５ｃ’を有する遮熱板５、５’が蛇腹部４の下流側に溶接により取り付けられ、この遮熱板５、５’（遮熱部５ｃ、５ｃ’）の外方に位置する冷却水配管１０等の周辺部品に蛇腹部４からの輻射熱の影響が及ぶのを防止する形態を示したが、ＥＧＲ配管１の周辺に配設される複数の部品に対して蛇腹部４からの輻射熱の影響が及ぶのを防止するため、当然ながら、複数の側面を覆う遮熱部５ｃ、５ｃ’を有する遮熱板５、５’が蛇腹部４の下流側に取り付けられても良い。また、一方の側面を覆う遮熱部５ｃ、５ｃ’を有する遮熱板５、５’が複数個蛇腹部４の下流側に取り付けられても良い。 In the first and second embodiments, the heat shield plates 5 and 5 ′ having the heat shield portions 5c and 5c ′ covering one side surface of the bellows portion 4 are attached to the downstream side of the bellows portion 4 by welding. Although the heat plate 5 and 5 ′ (heat shield portions 5c and 5c ′) have been shown in the form of preventing the influence of radiant heat from the bellows portion 4 on peripheral components such as the cooling water pipe 10 positioned outside the heat plate 5, In order to prevent the influence of the radiant heat from the bellows part 4 on a plurality of components arranged around the EGR pipe 1, it is natural that the shields have heat shielding parts 5c and 5c ′ covering a plurality of side surfaces. The hot plates 5 and 5 ′ may be attached to the downstream side of the bellows portion 4. Further, a plurality of heat shield plates 5 and 5 ′ having heat shield portions 5 c and 5 c ′ covering one side surface may be attached to the downstream side of the bellows portion 4.

また、上記の実施の形態１、２では、遮熱部５ｃ、５ｃ’の長手方向の長さＬ１が蛇腹部４の軸心方向の長さＬ２と略同じ長さに設定されていたが、長さＬ１と長さＬ２とが必ずしも同じ長さに設定される必要がなく、蛇腹部４からの輻射熱が遮熱部５ｃ、５ｃ’および扇状部５ｂで遮られて、冷却水配管１０等の周辺部品に蛇腹部４からの輻射熱の影響が及ばないように設定されれば良く、遮熱部５ｃ、５ｃ’の長さＬ１が蛇腹部４の長さＬ２よりも短い寸法に設定されても良く、あるいは、長い寸法に設定されても良い。 In the first and second embodiments, the length L1 in the longitudinal direction of the heat shield portions 5c and 5c ′ is set to be substantially the same as the length L2 in the axial direction of the bellows portion 4. The length L1 and the length L2 do not necessarily have to be set to the same length, and the radiant heat from the bellows portion 4 is blocked by the heat shield portions 5c, 5c ′ and the fan-shaped portion 5b, so that the cooling water pipe 10 or the like The peripheral parts may be set so as not to be affected by the radiant heat from the bellows part 4, and the length L1 of the heat shield parts 5c and 5c ′ may be set to be shorter than the length L2 of the bellows part 4. Alternatively, it may be set to a long dimension.

また、上記の実施の形態１、２では、遮熱部５ｃ、５ｃ’の長手方向が蛇腹部４の軸心方向に対して平行になるように配設されていたが、遮熱部５ｃ、５ｃ’が蛇腹部４の軸心に対して傾斜するように配設されても良い。さらに、遮熱部５ｃ、５ｃ’が蛇腹部４の軸心を通る平面に対して左右対称となる形状をもって配設されていたが、遮熱部５ｃ、５ｃ’が蛇腹部４の軸心を通る平面に対して非対称となる（傾斜する）ように配設されても良い。要は、蛇腹部４からの輻射熱が遮熱部５ｃ、５ｃ’および扇状部５ｂで遮られて、冷却水配管１０等の周辺部品に蛇腹部４からの輻射熱の影響が及ばないように、軸心に対する傾斜角度、軸心を通る平面に対する傾斜角度が設定されれば良い。遮熱部５ｃ、５ｃ’を蛇腹部４の軸心あるいは軸心を通る平面に対して傾斜させることにより、ＥＧＲ配管１が狭隘な空間に配置される場合にあっても、蛇腹部４からの輻射熱の影響が冷却水配管１０等の周辺部品に及ばないように、遮熱板５、５’を配置することができる。 In the first and second embodiments, the heat shield portions 5c and 5c ′ are arranged so that the longitudinal direction thereof is parallel to the axial direction of the bellows portion 4, but the heat shield portions 5c, 5c 'may be arrange | positioned so that it may incline with respect to the axial center of the bellows part 4. FIG. Furthermore, although the heat shields 5c and 5c ′ are arranged in a shape that is bilaterally symmetric with respect to the plane passing through the axis of the bellows part 4, the heat shields 5c and 5c ′ are arranged on the axis of the bellows part 4. You may arrange | position so that it may become asymmetrical (inclined) with respect to the plane which passes. In short, the radiant heat from the bellows portion 4 is blocked by the heat shield portions 5c, 5c ′ and the fan-shaped portion 5b so that the peripheral parts such as the cooling water pipe 10 are not affected by the radiant heat from the bellows portion 4. The inclination angle with respect to the center and the inclination angle with respect to the plane passing through the axis may be set. Even if the EGR pipe 1 is disposed in a narrow space by inclining the heat shields 5c and 5c ′ with respect to the axis of the bellows part 4 or a plane passing through the axis, The heat shield plates 5 and 5 ′ can be arranged so that the influence of the radiant heat does not reach the peripheral parts such as the cooling water pipe 10.

上記の実施の形態に示された本発明によれば、遮熱板から外方に位置する冷却水配管等の周辺部品に蛇腹部からの輻射熱の影響が及ぶのを防止するとともに、遮熱板をＥＧＲパイプに取り付ける溶接部に熱疲労クラックが発生することを防止して、溶接部の品質ならびに信頼性を向上させることができる。したがって、このような遮熱板を備えたＥＧＲ配管は、周辺に冷却水配管等の部品が配置された配管部分に好適に使用することができる。 According to the present invention shown in the above-described embodiment, it is possible to prevent the influence of radiant heat from the bellows part on peripheral parts such as cooling water pipes that are located outward from the heat shield, and the heat shield. Can prevent the occurrence of thermal fatigue cracks in the welded portion attached to the EGR pipe, thereby improving the quality and reliability of the welded portion. Therefore, the EGR pipe provided with such a heat shield plate can be suitably used for a pipe portion in which parts such as a cooling water pipe are arranged in the periphery.

本発明の実施の形態１に係るＥＧＲ配管の配置位置周辺の状態を説明するための平面図である。It is a top view for demonstrating the state of the arrangement position periphery of EGR piping which concerns on Embodiment 1 of this invention. 本発明の実施の形態１に係るＥＧＲ配管の構造と形状を説明するための平面図である。It is a top view for demonstrating the structure and shape of EGR piping which concern on Embodiment 1 of this invention. 本発明の実施の形態１に係るＥＧＲ配管の構造と形状を説明するための側面図である。It is a side view for demonstrating the structure and shape of EGR piping which concerns on Embodiment 1 of this invention. 本発明の実施の形態１に係るＥＧＲ配管に取り付けられた遮熱板周辺の状態を説明するための断面図である。It is sectional drawing for demonstrating the state of the heat-shielding board periphery attached to EGR piping which concerns on Embodiment 1 of this invention. 本発明の実施の形態１に係るＥＧＲ配管に取り付けられた遮熱板の構造と形状を説明するための、（ａ）はＥＧＲパイプの軸心に垂直な方向での断面図であり、（ｂ）はＥＧＲパイプの軸心に平行な方向での断面図である。(A) is sectional drawing in the direction perpendicular | vertical to the axial center of an EGR pipe for demonstrating the structure and shape of the heat shield attached to EGR piping which concerns on Embodiment 1 of this invention, (b ) Is a cross-sectional view in a direction parallel to the axis of the EGR pipe. 本発明の実施の形態２に係るＥＧＲ配管の構造と形状を説明するための側面図である。It is a side view for demonstrating the structure and shape of EGR piping which concerns on Embodiment 2 of this invention. 本発明の実施の形態２に係るＥＧＲ配管に取り付けられた遮熱板の構造と形状を説明するための、（ａ）はＥＧＲパイプの軸心に垂直な方向での断面図であり、（ｂ）はＥＧＲパイプの軸心に平行な方向での断面図である。(A) is sectional drawing in the direction perpendicular | vertical to the axial center of an EGR pipe for demonstrating the structure and shape of the heat-shielding board attached to EGR piping which concerns on Embodiment 2 of this invention, (b ) Is a cross-sectional view in a direction parallel to the axis of the EGR pipe. 従来の排気管に取り付けられた遮熱板の構造と形状を説明するための、（ａ）は排気管の軸心に垂直な方向の断面図であり、（ｂ）は排気管の軸心に平行な方向での断面図である。For explaining the structure and shape of a heat shield plate attached to a conventional exhaust pipe, (a) is a cross-sectional view perpendicular to the axis of the exhaust pipe, and (b) is the axis of the exhaust pipe. It is sectional drawing in a parallel direction.

Explanation of symbols

１ＥＧＲ配管
２上流側ＥＧＲパイプ
３下流側ＥＧＲパイプ
４蛇腹部
５遮熱板
５ａ取付部
５ｂ扇状部
５ｃ遮熱部
５ｄ溶接部
５ｅ側端部
６エンジン
７エンジンヘッド
８排気ガス取り出しポート
８ａＥＧＲポート開口部
９ＥＧＲクーラ
９ａＥＧＲ導入開口部
１０冷却水配管 1 EGR pipe 2 upstream EGR pipe 3 downstream EGR pipe 4 bellows portion 5 heat shield plate 5a mounting portion 5b fan-shaped portion 5c heat shielding portion 5 d weld 5e end 6 engine 7 engine head 8 exhaust gas taking-out port 8a EGR Port opening 9 EGR cooler 9a EGR introduction opening 10 Cooling water piping

Claims

In EGR piping connecting the exhaust system and the intake system,
A heat shield covering at least one side surface of the bellows portion is attached by welding to the downstream side of the bellows portion provided in the middle of the EGR pipe that extracts exhaust gas from the exhaust system ,
The heat shield plate has an attachment portion to the EGR pipe, a fan-shaped portion that is widened toward the upstream side from the attachment portion, and is formed so as to be gradually separated from the EGR pipe, and further upstream from the fan-like portion. An EGR pipe comprising: a heat shield portion extending toward the bellows and formed in a cross-sectional arc shape or a straight cross-sectional shape in a state of being separated from the bellows portion and covering at least one side surface of the bellows portion .

Both end portions of the heat shield portion extending from the fan-shaped portion and parallel to the extending direction are separated from the surface of the bellows portion, and an opening is formed between the heat shield portion and the bellows portion. The EGR pipe according to claim 1, wherein the EGR pipe is provided.