JP6607130B2 - Exhaust gas recirculation structure of cylinder head - Google Patents

Exhaust gas recirculation structure of cylinder head Download PDF

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JP6607130B2
JP6607130B2 JP2016075732A JP2016075732A JP6607130B2 JP 6607130 B2 JP6607130 B2 JP 6607130B2 JP 2016075732 A JP2016075732 A JP 2016075732A JP 2016075732 A JP2016075732 A JP 2016075732A JP 6607130 B2 JP6607130 B2 JP 6607130B2
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egr passage
cylinder head
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exhaust gas
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JP2017008923A (en
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洋臣 田中
正輝 勅使
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Suzuki Motor Co Ltd
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Description

本発明は、シリンダヘッドの排気還流構造に関し、特に、シリンダヘッドに形成され、吸気部と排気部とを連通するＥＧＲ通路を備えたシリンダヘッドの排気還流構造に関する。   The present invention relates to an exhaust gas recirculation structure for a cylinder head, and more particularly to an exhaust gas recirculation structure for a cylinder head provided with an EGR passage formed in the cylinder head and communicating an intake portion and an exhaust portion.

一般に、自動車等の車両に搭載される内燃機関においては、内燃機関から排出された排気ガスの一部を吸気側に還流し、ＮＯｘ（窒素酸化物）やポンピングロスを低減させる排気還流構造が設けられている。   In general, an internal combustion engine mounted on a vehicle such as an automobile is provided with an exhaust gas recirculation structure that recirculates part of exhaust gas discharged from the internal combustion engine to the intake side to reduce NOx (nitrogen oxide) and pumping loss. It has been.

この排気還流構造にあっては、排気ガスを高温の状態のままで吸気側へ還流すると、吸入空気が膨張して充填効率が低下するため、シリンダヘッドのウォータジャケット内にＥＧＲ（Exhaust Gas Recirculation）通路を配置し、このＥＧＲ通路を流れる排気ガス（ＥＧＲガス）を冷却するものがある。   In this exhaust gas recirculation structure, if the exhaust gas is recirculated to the intake side while being in a high temperature state, the intake air expands and the filling efficiency is lowered. Therefore, EGR (Exhaust Gas Recirculation) is provided in the water jacket of the cylinder head. There is a type that arranges a passage and cools exhaust gas (EGR gas) flowing through the EGR passage.

従来のこの種の排気還流構造としては、例えば、特許文献１に記載されたものが知られている。
この排気還流構造は、シリンダヘッドのウォータジャケットの内部に設置される熱交換器用偏平伝熱管を有し、熱交換器用偏平伝熱管が、ＥＧＲパイプの他端に連通される排気ガス流入端部と、ＥＧＲバルブに連通される排気ガス流出端部とを備えている。 As this type of conventional exhaust gas recirculation structure, for example, the one described in Patent Document 1 is known.
This exhaust gas recirculation structure has a flat heat transfer pipe for heat exchanger installed inside the water jacket of the cylinder head, and the flat heat transfer pipe for heat exchanger is connected to the other end of the EGR pipe, And an exhaust gas outflow end connected to the EGR valve.

排気ガス流入端部と排気ガス流出端部のそれぞれは、排気ガスの流れる方向に対して垂直な平面による断面において円形状に形成されており、排気ガス流入端部と排気ガス流出端部とのそれぞれが、シリンダヘッドの排気側および吸気側に鋳込まれることにより、熱交換器用偏平伝熱管がシリンダヘッドのウォータジャケットの内部に配設される。   Each of the exhaust gas inflow end portion and the exhaust gas outflow end portion is formed in a circular shape in a cross section by a plane perpendicular to the flow direction of the exhaust gas, and the exhaust gas inflow end portion and the exhaust gas outflow end portion are Each is cast on the exhaust side and the intake side of the cylinder head, so that the heat exchanger flat heat transfer tube is disposed inside the water jacket of the cylinder head.

特許第５４３４７５６号公報Japanese Patent No. 5434756

このような従来のシリンダヘッドの排気還流構造にあっては、熱交換器用偏平伝熱管の排気ガス流入端部と排気ガス流出端部とのそれぞれが、シリンダヘッドの排気側および吸気側に鋳込まれることにより、熱交換器用偏平伝熱管がシリンダヘッドのウォータジャケットの内部に配設される。
これにより、熱交換器用偏平伝熱管をシリンダヘッドに鋳込む作業が必要となり、シリンダヘッドの製造作業が面倒になる上に、シリンダヘッドの製造コストが増大してしまう。 In such a conventional exhaust recirculation structure of a cylinder head, the exhaust gas inflow end portion and the exhaust gas outflow end portion of the flat heat transfer tube for heat exchanger are respectively casted on the exhaust side and the intake side of the cylinder head. As a result, the heat exchanger flat heat transfer tube is arranged inside the water jacket of the cylinder head.
This necessitates the work of casting the heat exchanger flat heat transfer tube into the cylinder head, which complicates the manufacturing work of the cylinder head and increases the manufacturing cost of the cylinder head.

さらに、熱交換器用偏平伝熱管が高温のＥＧＲガスと低温の冷却水によって熱膨張と縮小を繰り返すため、熱交換器用偏平伝熱管の排気ガス流入端部と排気ガス流出端部とをシリンダヘッドに安定して固定することが困難となり、ＥＧＲガスを安定して冷却することができない。   Furthermore, since the heat exchanger flat heat transfer tube repeats thermal expansion and contraction due to high temperature EGR gas and low temperature cooling water, the exhaust gas inflow end and exhaust gas outflow end of the heat exchanger flat heat transfer tube are connected to the cylinder head. It becomes difficult to fix stably, and EGR gas cannot be cooled stably.

また、熱交換器用偏平伝熱管の排気ガス流入端部と排気ガス流出端部とが熱膨張と縮小を繰り返すことによる応力の変化により、排気還流構造の信頼性を確保するために熱交換器用偏平伝熱管の板厚を増大させる、熱交換器用偏平伝熱管として材料強度の大きな材料を選択する等の対応が必要になる。   In addition, the heat exchanger flatness is ensured in order to ensure the reliability of the exhaust gas recirculation structure due to the stress change caused by repeated expansion and contraction of the exhaust gas inflow end and exhaust gas outflow end of the heat exchanger flat heat transfer tube. It is necessary to take measures such as increasing the plate thickness of the heat transfer tube and selecting a material having a high material strength as the flat heat transfer tube for the heat exchanger.

本発明は、上記のような問題点に着目してなされたものであり、シリンダヘッドに排気還流構造を設ける場合であっても、信頼性を確保しつつＥＧＲガスの冷却性能を向上できるシリンダヘッドの排気還流構造を提供することを目的とするものである。   The present invention has been made paying attention to the above-described problems, and even when the cylinder head is provided with an exhaust gas recirculation structure, the cylinder head can improve the cooling performance of EGR gas while ensuring reliability. It is an object of the present invention to provide an exhaust gas recirculation structure.

本発明は、冷却水が流れるウォータジャケット、排気ガスを排出する排気部および吸入空気が導入される吸気部を有するシリンダヘッドに設けられた排気還流構造であって、前記シリンダヘッドに形成され、前記排気部と前記吸気部とを連通するＥＧＲ通路と、前記ＥＧＲ通路の内周部に外周部の少なくとも一部が接触するように前記ＥＧＲ通路に挿入され、前記ＥＧＲ通路の内周部との間で熱交換を行う内筒部材とを備え、前記ＥＧＲ通路は、前記ＥＧＲ通路の内周部と前記内筒部材の外周部との間に形成された外周側ＥＧＲ通路と前記内筒部材の内部に形成された内周側ＥＧＲ通路とを含んで構成され、前記ウォータジャケットが、前記ＥＧＲ通路に隣接するように前記シリンダヘッドに形成され、前記排気部が前記シリンダヘッドの一側面側に形成されるとともに、前記吸気部が前記シリンダヘッドの他側面側に形成され、前記ＥＧＲ通路は、前記シリンダヘッドの前記他側面に形成された開口端から前記排気部に向かって延びる第１のＥＧＲ通路と、前記第１のＥＧＲ通路の延びる方向の途中から分岐して前記吸気部に向かって延びる第２のＥＧＲ通路と、前記第１のＥＧＲ通路および第２のＥＧＲ通路の分岐部から前記開口端まで延びる分岐通路とを有し、前記分岐通路が閉止部材によって閉止されており、前記第１のＥＧＲ通路に前記内筒部材が挿入されているとともに、前記内筒部材が前記分岐通路まで延ばされており、前記ウォータジャケットは、前記分岐通路に隣接しているものから構成されている。
The present invention is an exhaust gas recirculation structure provided in a cylinder head having a water jacket through which cooling water flows, an exhaust part that exhausts exhaust gas, and an intake part into which intake air is introduced, and is formed in the cylinder head, An EGR passage communicating the exhaust portion and the intake portion is inserted between the EGR passage so that at least a part of the outer peripheral portion is in contact with the inner peripheral portion of the EGR passage, and between the EGR passage and the inner peripheral portion of the EGR passage. An inner cylinder member that exchanges heat with the EGR passage, and the EGR passage is formed between an inner periphery of the EGR passage and an outer periphery of the inner cylinder member, and an inner side of the inner cylinder member. configured within and a peripheral side EGR passage formed in the water jacket, wherein formed in the cylinder head adjacent to the EGR passage, one of the exhaust portion is the cylinder head The intake portion is formed on the other side surface of the cylinder head, and the EGR passage extends from an opening end formed on the other side surface of the cylinder head toward the exhaust portion. 1 EGR passage, a second EGR passage extending from the middle of the extending direction of the first EGR passage and extending toward the intake portion, and a branching portion of the first EGR passage and the second EGR passage A branch passage extending from the opening end to the opening end, the branch passage being closed by a closing member, the inner cylinder member being inserted into the first EGR passage, and the inner cylinder member being the branch The water jacket extends from the passageway and is adjacent to the branch passageway .

このように本発明によれば、シリンダヘッドに排気還流構造を設ける場合であっても、信頼性を確保しつつＥＧＲガスの冷却性能を向上できる。   As described above, according to the present invention, even when the exhaust gas recirculation structure is provided in the cylinder head, the cooling performance of the EGR gas can be improved while ensuring the reliability.

図１は、本発明のシリンダヘッドの排気還流構造の一実施の形態を示す図であり、シリンダヘッドを有するエンジンの要部側面図である。FIG. 1 is a view showing an embodiment of an exhaust gas recirculation structure for a cylinder head according to the present invention, and is a side view of a main part of an engine having a cylinder head. 図２は、本発明のシリンダヘッドの排気還流構造の一実施の形態を示す図であり、シリンダヘッドを有するエンジンの上面図である。FIG. 2 is a view showing an embodiment of an exhaust gas recirculation structure for a cylinder head according to the present invention, and is a top view of an engine having the cylinder head. 図３は、本発明のシリンダヘッドの排気還流構造の一実施の形態を示す図であり、図２のIII−III方向矢視断面図である。FIG. 3 is a view showing an embodiment of the exhaust gas recirculation structure for a cylinder head according to the present invention, and is a cross-sectional view taken along the line III-III in FIG. 図４は、本発明のシリンダヘッドの排気還流構造の一実施の形態を示す図であり、シリンダヘッドの側面断面図であり、図２のIII−III方向矢視断面図である。4 is a view showing an embodiment of the exhaust gas recirculation structure for a cylinder head according to the present invention, a side cross-sectional view of the cylinder head, and a cross-sectional view taken along the line III-III in FIG. 図５は、本発明のシリンダヘッドの排気還流構造の一実施の形態を示す図であり、内筒部材の斜視図である。FIG. 5 is a view showing an embodiment of the exhaust gas recirculation structure for a cylinder head according to the present invention, and is a perspective view of an inner cylinder member. 図６は、本発明のシリンダヘッドの排気還流構造の一実施の形態を示す図であり、図４のＶI−ＶI方向矢視断面図である。6 is a view showing an embodiment of the exhaust gas recirculation structure for a cylinder head according to the present invention, and is a cross-sectional view taken along the line VI-VI in FIG. 図７は、本発明のシリンダヘッドの排気還流構造の一実施の形態を示す図であり、ＥＧＲ通路に挿入される前の内筒部材の山部の形状とＥＧＲ通路の形状とを示す図である。FIG. 7 is a view showing an embodiment of an exhaust gas recirculation structure for a cylinder head according to the present invention, and shows a shape of a peak portion of an inner cylinder member and a shape of an EGR passage before being inserted into the EGR passage. is there. 図８は、本発明のシリンダヘッドの排気還流構造の一実施の形態を示す図であり、ＥＧＲ通路に挿入後の内筒部材の山部の形状とＥＧＲ通路の形状とを示す図である。FIG. 8 is a view showing an embodiment of an exhaust gas recirculation structure for a cylinder head according to the present invention, and is a view showing a shape of a peak portion of an inner cylinder member and a shape of an EGR passage after being inserted into an EGR passage. 図９は、本発明のシリンダヘッドの排気還流構造の一実施の形態を示す図であり、ＥＧＲ通路を流れるＥＧＲガスの状態を示す図である。FIG. 9 is a view showing an embodiment of an exhaust gas recirculation structure for a cylinder head according to the present invention, and is a view showing a state of EGR gas flowing through an EGR passage. 図１０は、本発明のシリンダヘッドの排気還流構造の一実施の形態を示す図であり、他の形状の内筒部材を有する排気還流構造の概略構成図である。FIG. 10 is a diagram showing an embodiment of an exhaust gas recirculation structure for a cylinder head according to the present invention, and is a schematic configuration diagram of an exhaust gas recirculation structure having an inner cylinder member of another shape. 図１１は、本発明のシリンダヘッドの排気還流構造の一実施の形態を示す図であり、他の形状の内筒部材が挿入されたシリンダヘッドの側面断面図である（図２のIII−III方向矢視断面に相当）。11 is a view showing an embodiment of the exhaust gas recirculation structure for a cylinder head according to the present invention, and is a side cross-sectional view of the cylinder head in which an inner cylinder member of another shape is inserted (III-III in FIG. 2). Equivalent to a cross section taken along the direction). 図１２は、本発明のシリンダヘッドの排気還流構造の一実施の形態を示す図であり、他の形状の内筒部材の斜視図である。FIG. 12 is a view showing an embodiment of the exhaust gas recirculation structure for a cylinder head according to the present invention, and is a perspective view of an inner cylinder member having another shape. 図１３は、本発明のシリンダヘッドの排気還流構造の一実施の形態を示す図であり、他の形状の内筒部材が挿入されたシリンダヘッドの側面断面図である（図２のIII−III方向矢視断面に相当）。13 is a view showing an embodiment of the exhaust gas recirculation structure for a cylinder head according to the present invention, and is a side cross-sectional view of the cylinder head in which an inner cylindrical member of another shape is inserted (III-III in FIG. 2). Equivalent to a cross section taken along the direction). 図１４は、本発明のシリンダヘッドの排気還流構造の一実施の形態を示す図であり、他の形状の内筒部材が挿入されたシリンダヘッドの側面断面図である（図２のIII−III方向矢視断面に相当）。FIG. 14 is a view showing an embodiment of the exhaust gas recirculation structure for a cylinder head according to the present invention, and is a side cross-sectional view of the cylinder head with an inner cylinder member of another shape inserted (III-III in FIG. 2). Equivalent to a cross section taken along the direction). 図１５は、本発明のシリンダヘッドの排気還流構造の一実施の形態を示す図であり、他の形状の内筒部材の斜視図である。FIG. 15 is a view showing an embodiment of the exhaust gas recirculation structure for a cylinder head according to the present invention, and is a perspective view of an inner cylinder member having another shape. 図１６は、本発明のシリンダヘッドの排気還流構造の他の実施の形態を示す図であり、内筒部材が挿入されたシリンダヘッドの側面断面図である（図２のIII−III方向矢視断面に相当）。16 is a view showing another embodiment of the exhaust gas recirculation structure of the cylinder head of the present invention, and is a side sectional view of the cylinder head with the inner cylinder member inserted (in the direction of arrows III-III in FIG. 2). Equivalent to a cross section). 図１７は、本発明のシリンダヘッドの排気還流構造の他の実施の形態を示す図であり、内筒部材および棒状部材の分解図である。FIG. 17 is a view showing another embodiment of the exhaust gas recirculation structure for a cylinder head according to the present invention, and is an exploded view of an inner cylinder member and a rod-like member. 図１８は、本発明のシリンダヘッドの排気還流構造の他の実施の形態を示す図であり、内筒部材および棒状部材の分解斜視図である。FIG. 18 is a diagram showing another embodiment of the exhaust recirculation structure for a cylinder head according to the present invention, and is an exploded perspective view of an inner cylinder member and a rod-shaped member. 図１９は、本発明のシリンダヘッドの排気還流構造の他の実施の形態を示す図であり、図１６のＸIＸ−ＸIＸ方向矢視断面図である。FIG. 19 is a view showing another embodiment of the exhaust gas recirculation structure for a cylinder head according to the present invention, and is a cross-sectional view taken along arrow XIX-XIX in FIG. 図２０は、本発明のシリンダヘッドの排気還流構造の他の実施の形態を示す図であり、ＥＧＲ通路に挿入された他の形状の内筒部材の断面図である（図１６のＸIＸ−ＸIＸ方向矢視断面に相当）。FIG. 20 is a view showing another embodiment of the exhaust gas recirculation structure of the cylinder head of the present invention, and is a cross-sectional view of another shape of the inner cylinder member inserted into the EGR passage (XIX-XIX in FIG. 16). Equivalent to a cross section taken along the direction).

以下、本発明に係るシリンダヘッドの排気還流構造の実施の形態について、図面を用いて説明する。
図１〜図２０は、本発明に係る一実施の形態のシリンダヘッドの排気還流構造を示す図である。なお、図１〜図２０において、上下左右方向は、車両に搭乗する運転者から見た方向を示している。 Embodiments of an exhaust gas recirculation structure for a cylinder head according to the present invention will be described below with reference to the drawings.
1 to 20 are views showing an exhaust gas recirculation structure of a cylinder head according to an embodiment of the present invention. 1 to 20, the up, down, left, and right directions indicate directions viewed from the driver on the vehicle.

まず、構成を説明する。
図１、図２において、車両には内燃機関としてのエンジン１が搭載されている。図１において、エンジン１は、シリンダブロック２と、シリンダブロック２の上部に設けられたシリンダヘッド３と、シリンダヘッド３の上部に設けられたシリンダヘッドカバー４とを備えている。 First, the configuration will be described.
1 and 2, an engine 1 as an internal combustion engine is mounted on the vehicle. In FIG. 1, the engine 1 includes a cylinder block 2, a cylinder head 3 provided on the top of the cylinder block 2, and a cylinder head cover 4 provided on the top of the cylinder head 3.

シリンダブロック２には図示しないシリンダ内に上下動自在に収容された図示しないピストンと、ピストンの上下運動を回転運動に変換する図示しないクランク軸等が収容されている。 図３において、シリンダヘッド３の上面には、図示しない吸気カムシャフトと排気カムシャフトとを回転自在に支持するロアハウジング３Ａが形成されている。   The cylinder block 2 accommodates a piston (not shown) that is accommodated in a cylinder (not shown) so as to freely move up and down, a crankshaft (not shown) that converts the vertical movement of the piston into a rotational motion, and the like. In FIG. 3, a lower housing 3 </ b> A that rotatably supports an intake camshaft and an exhaust camshaft (not shown) is formed on the upper surface of the cylinder head 3.

図２において、シリンダヘッド３の車両の前方に対向する一側面３ａには複数の排気ポート３Ｂが形成されており、排気ポート３Ｂは、シリンダブロック２のシリンダに連通している。シリンダヘッド３の一側面３ａには図示しない排気マニホールドが接続されており、排気マニホールドは、排気ポート３Ｂに連通している。   In FIG. 2, a plurality of exhaust ports 3 </ b> B are formed on one side surface 3 a of the cylinder head 3 facing the front of the vehicle, and the exhaust ports 3 </ b> B communicate with the cylinders of the cylinder block 2. An exhaust manifold (not shown) is connected to one side surface 3a of the cylinder head 3, and the exhaust manifold communicates with the exhaust port 3B.

図３において、シリンダヘッド３の車両の後方に対向する他側面３ｂには吸気ポート３Ｃが形成されており、吸気ポート３Ｃは、図示しない燃焼室に連通している。なお、燃焼室は、シリンダの内壁、ピストンの頂面およびシリンダヘッド３の下面によって囲まれる空間である。   In FIG. 3, an intake port 3C is formed on the other side surface 3b of the cylinder head 3 facing the rear of the vehicle, and the intake port 3C communicates with a combustion chamber (not shown). The combustion chamber is a space surrounded by the inner wall of the cylinder, the top surface of the piston, and the lower surface of the cylinder head 3.

図２において、シリンダヘッド３の他側面３ｂには吸気マニホールド５が接続されている。吸気マニホールド５には図示しない吸気管が接続されており、吸気マニホールド５には吸気管を通して外気が導入され、吸気マニホールド５に導入された吸入空気は、吸気ポート３Ｃを通してシリンダに導入される。   In FIG. 2, an intake manifold 5 is connected to the other side surface 3 b of the cylinder head 3. An intake pipe (not shown) is connected to the intake manifold 5. Outside air is introduced into the intake manifold 5 through the intake pipe, and the intake air introduced into the intake manifold 5 is introduced into the cylinder through the intake port 3C.

ピストンの上昇に伴って、排気ガスがシリンダから排気ポート３Ｂを通して排気マニホールドに排出され、この排気ガスは、排気マニホールドの下流に設置された図示しない触媒コンバータで浄化された後、外部に排出される。   As the piston rises, the exhaust gas is discharged from the cylinder to the exhaust manifold through the exhaust port 3B. The exhaust gas is purified by a not-shown catalytic converter installed downstream of the exhaust manifold and then discharged to the outside. .

図３、図４において、シリンダヘッド３の左端部にはＥＧＲ通路６が形成されており、ＥＧＲ通路６は、複数の排気ポート３Ｂのそれぞれに連通している。シリンダヘッド３にはＥＧＲ通路７が形成されており、ＥＧＲ通路７は、シリンダヘッド３に対して車両の前後方向に直線状に延びている。ＥＧＲ通路７は、上流端７ａがＥＧＲ通路６に連通しており、ＥＧＲ通路７には上流端７ａを通して排気ガスの一部であるＥＧＲガスが導入される。   3 and 4, an EGR passage 6 is formed at the left end portion of the cylinder head 3, and the EGR passage 6 communicates with each of the plurality of exhaust ports 3B. An EGR passage 7 is formed in the cylinder head 3, and the EGR passage 7 extends linearly in the longitudinal direction of the vehicle with respect to the cylinder head 3. The EGR passage 7 has an upstream end 7 a communicating with the EGR passage 6, and EGR gas that is part of exhaust gas is introduced into the EGR passage 7 through the upstream end 7 a.

ＥＧＲ通路７の下流端７ｂは、シリンダヘッド３の他側面３ｂに開口しており、下流端７ｂは、プラグ８によって閉止されている。なお、上流、下流とは、ＥＧＲガスや排気ガスの流れに方向に対して上流、下流を表す。ここで、本実施の形態のＥＧＲ通路７の下流端７ｂは、本発明の開口端を構成し、プラグ８は、本発明の閉止部材を構成する。また、ＥＧＲ通路６は、本発明の排気部を構成する。   A downstream end 7 b of the EGR passage 7 opens to the other side surface 3 b of the cylinder head 3, and the downstream end 7 b is closed by a plug 8. In addition, upstream and downstream represent upstream and downstream with respect to the direction of the flow of EGR gas and exhaust gas. Here, the downstream end 7b of the EGR passage 7 of the present embodiment constitutes an open end of the present invention, and the plug 8 constitutes a closing member of the present invention. Further, the EGR passage 6 constitutes an exhaust part of the present invention.

ＥＧＲ通路７は、シリンダヘッド３の他側面３ｂに形成された下流端７ｂからＥＧＲ通路６に向かって直線状に延びている。ＥＧＲ通路７は、このように構成されることで、下流端７ｂ側から図示しないドリル等の工具によってＥＧＲ通路６に連通する位置まで穴開け加工によって形成することができる。ここで、ＥＧＲ通路７は、本発明の第１のＥＧＲ通路を構成する。   The EGR passage 7 extends linearly from the downstream end 7 b formed on the other side surface 3 b of the cylinder head 3 toward the EGR passage 6. With this configuration, the EGR passage 7 can be formed by drilling from the downstream end 7b side to a position communicating with the EGR passage 6 with a tool such as a drill (not shown). Here, the EGR passage 7 constitutes a first EGR passage of the present invention.

ＥＧＲ通路７の延びる方向の途中からはＥＧＲ通路９が分岐しており、ＥＧＲ通路９は、ＥＧＲ通路７とＥＧＲ通路９の分岐部１０からシリンダヘッド３の他側面３ｂに向かって上方に傾斜するように直線状に延び、下流端９ａがシリンダヘッド３の他側面３ｂに開口している。   An EGR passage 9 is branched from the middle of the direction in which the EGR passage 7 extends, and the EGR passage 9 is inclined upward from the branch portion 10 of the EGR passage 7 and the EGR passage 9 toward the other side surface 3b of the cylinder head 3. The downstream end 9 a is open to the other side surface 3 b of the cylinder head 3.

ＥＧＲ通路７は、このように構成されることで下流端９ａ側からドリル等の工具によって分岐部１０に連通する位置まで穴開け加工によって形成することができる。ここで、ＥＧＲ通路９は、本発明の第２のＥＧＲ通路を構成する。   With such a configuration, the EGR passage 7 can be formed by drilling from the downstream end 9a side to a position where it communicates with the branch portion 10 with a tool such as a drill. Here, the EGR passage 9 constitutes a second EGR passage of the present invention.

ＥＧＲ通路９の下流端９ａは、吸気マニホールド５に連通しており、ＥＧＲ通路７からＥＧＲ通路９に導入されるＥＧＲガスは、吸気マニホールド５から吸気ポート３Ｃを通してシリンダに導入される。   The downstream end 9a of the EGR passage 9 communicates with the intake manifold 5, and EGR gas introduced from the EGR passage 7 into the EGR passage 9 is introduced into the cylinder from the intake manifold 5 through the intake port 3C.

このように不活性なガスを含むＥＧＲを導入することにより、燃焼室内において、燃焼温度が上昇し難くなり、ＮＯｘ（窒素酸化物）が低減する。また、酸素濃度が低くなることにより、吸入ガス量に比べてスロットルバルブを開き側にして出力調整でき、ポンピングロスを低減できる。ここで、吸気マニホールド５は、本発明の吸気部を構成しており、ＥＧＲ通路７、９がＥＧＲ通路６と吸気マニホールド５とを連通する本発明のＥＧＲ通路を構成している。   By introducing EGR containing an inert gas in this way, the combustion temperature is unlikely to rise in the combustion chamber, and NOx (nitrogen oxide) is reduced. In addition, since the oxygen concentration is lowered, the output can be adjusted with the throttle valve opened as compared with the intake gas amount, and the pumping loss can be reduced. Here, the intake manifold 5 constitutes the intake portion of the present invention, and the EGR passages 7 and 9 constitute the EGR passage of the present invention in which the EGR passage 6 and the intake manifold 5 are communicated.

図３、図４において、ＥＧＲ通路７、９の分岐部１０と下流端７ｂとの間のＥＧＲ通路７の部位は、分岐通路１１を構成しており、分岐通路１１は、本発明の分岐通路を構成している。 図１、図２において、シリンダヘッド３の左端部にはＥＧＲバルブ１６が設けられており、ＥＧＲバルブ１６は、ＥＧＲ通路６の流路面積を可変する図示しないバルブ部を有し、バルブ部の開度を調整することで、ＥＧＲ通路６を流れるＥＧＲガスの流量を調整する。   3 and 4, the portion of the EGR passage 7 between the branch portion 10 and the downstream end 7b of the EGR passages 7 and 9 constitutes a branch passage 11, and the branch passage 11 is the branch passage of the present invention. Is configured. 1 and 2, an EGR valve 16 is provided at the left end of the cylinder head 3, and the EGR valve 16 has a valve portion (not shown) that changes the flow area of the EGR passage 6. By adjusting the opening, the flow rate of the EGR gas flowing through the EGR passage 6 is adjusted.

本実施の形態のシリンダヘッド３において、ＥＧＲ通路７、９が穴開け加工された後に、分岐通路１１がプラグ８によって閉止されることで、ＥＧＲ通路７、９が密閉される。
このため、分岐通路１１は、ＥＧＲガスが流れるＥＧＲ通路７、９から外れた位置に設置されることになる。 In the cylinder head 3 of the present embodiment, after the EGR passages 7 and 9 are drilled, the branch passage 11 is closed by the plug 8 so that the EGR passages 7 and 9 are sealed.
For this reason, the branch passage 11 is installed at a position away from the EGR passages 7 and 9 through which the EGR gas flows.

図３、図４において、シリンダヘッド３には冷却水が流れるウォータジャケット１２が形成されており、ウォータジャケット１２は、シリンダヘッド３の中でも高温となるシリンダ側（燃焼室側）の底部、ＥＧＲ通路７、９の周囲および分岐通路１１の周囲に連続して形成される。すなわち、本実施の形態のウォータジャケット１２は、ＥＧＲ通路７、９および分岐通路１１に隣接するようにシリンダヘッド３に形成されている。   3 and 4, a water jacket 12 through which cooling water flows is formed in the cylinder head 3, and the water jacket 12 includes a bottom portion on the cylinder side (combustion chamber side) that becomes a high temperature in the cylinder head 3, and an EGR passage. 7 and 9 and the branch passage 11 are formed continuously. That is, the water jacket 12 of the present embodiment is formed in the cylinder head 3 so as to be adjacent to the EGR passages 7 and 9 and the branch passage 11.

図４において、ＥＧＲ通路７には内筒部材１３が設置されており、内筒部材１３は、ＥＧＲ通路７の下流端７ｂから分岐通路１１を通してＥＧＲ通路７に挿入される。   In FIG. 4, an inner cylinder member 13 is installed in the EGR passage 7, and the inner cylinder member 13 is inserted into the EGR passage 7 from the downstream end 7 b of the EGR passage 7 through the branch passage 11.

図５において、内筒部材１３は、多葉形状に形成されている。具体的には、図６において、内筒部材１３は、内筒部材１３の延びる方向の中心軸Ｏに対して直交する方向の断面形状が、山部１３Ａと山部１３Ａの間に位置する谷部１３Ｂとが円周方向において交互に繰り返す多葉形状に形成されている。   In FIG. 5, the inner cylinder member 13 is formed in a multi-leaf shape. Specifically, in FIG. 6, the inner cylinder member 13 is a valley in which the cross-sectional shape in a direction orthogonal to the central axis O in the extending direction of the inner cylinder member 13 is located between the peak portion 13A and the peak portion 13A. The part 13B is formed in a multi-leaf shape that repeats alternately in the circumferential direction.

ＥＧＲでは、凝縮水による腐食が懸念されるため、内筒部材１３は、ステンレス等の材料が使用される。内筒部材１３のその他の材料としては、シリンダヘッド３の材質と熱伝導性が同一の材料あるいは、シリンダヘッド３の材質よりも熱伝導性が高い材料が使用される。例えば、シリンダヘッド３がアルミニウムやアルミニウム合金等からなる場合には、内筒部材１３は、シリンダヘッド３の材料と同一の材料、あるいは銅等の材料により製造される。   In EGR, since corrosion due to condensed water is a concern, the inner cylinder member 13 is made of a material such as stainless steel. As the other material of the inner cylinder member 13, a material having the same thermal conductivity as that of the cylinder head 3 or a material having a higher thermal conductivity than the material of the cylinder head 3 is used. For example, when the cylinder head 3 is made of aluminum, an aluminum alloy, or the like, the inner cylinder member 13 is manufactured from the same material as the cylinder head 3 or a material such as copper.

図６において、内筒部材１３は、内筒部材１３の一部を構成する山部１３Ａの頂点１３ａがＥＧＲ通路７の内周部７ｃに接触しており、内筒部材１３は、ウォータジャケット１２の冷却水に晒されるＥＧＲ通路７の内周部７ｃとの間で熱交換を行うことにより、ＥＧＲガスを冷却する。すなわち、本実施の形態の内筒部材１３の外周部は、内筒部材１３の円周方向においてＥＧＲ通路７の内周部７ｃに断続的に接触している。   In FIG. 6, the inner cylinder member 13 is such that the apex 13 a of the peak portion 13 </ b> A constituting a part of the inner cylinder member 13 is in contact with the inner peripheral part 7 c of the EGR passage 7. The EGR gas is cooled by exchanging heat with the inner peripheral portion 7c of the EGR passage 7 exposed to the cooling water. That is, the outer peripheral portion of the inner cylindrical member 13 of the present embodiment is intermittently in contact with the inner peripheral portion 7 c of the EGR passage 7 in the circumferential direction of the inner cylindrical member 13.

図６において、ＥＧＲ通路７は、内筒部材１３の外周部とＥＧＲ通路７の内周部７ｃとの間に形成された外周側ＥＧＲ通路１４と、内筒部材１３の内部に形成された内周側ＥＧＲ通路１５とを備えている。   In FIG. 6, the EGR passage 7 includes an outer peripheral side EGR passage 14 formed between the outer peripheral portion of the inner cylindrical member 13 and the inner peripheral portion 7 c of the EGR passage 7, and an inner portion formed inside the inner cylindrical member 13. And a circumferential EGR passage 15.

図４において、内筒部材１３の端部には山部１３Ａの頂点１３ａを結んだ外周円よりも径の小さい円状の筒部１３Ｃが設けられており、筒部１３Ｃは、分岐通路１１まで延びている。   In FIG. 4, an end portion of the inner cylindrical member 13 is provided with a circular cylindrical portion 13 </ b> C having a diameter smaller than the outer peripheral circle connecting the apex 13 a of the peak portion 13 </ b> A, and the cylindrical portion 13 </ b> C extends to the branch passage 11. It extends.

すなわち、内筒部材１３は、ＥＧＲ通路７および分岐通路１１に挿入されている。これにより、内筒部材１３は、分岐通路１１において外周側ＥＧＲ通路１４を挟んでＥＧＲ通路９と内周側ＥＧＲ通路１５とを連通している。なお、谷部１３Ｂの外周を結んだ外周円は、円形となる。また、内筒部材１３の外周部は、山部１３Ａの頂点１３ａと、頂点１３ａを除いた山部１３Ａの部位と、谷部１３Ｂの外周部とから構成されるものであり、頂点１３ａが外周部の一部を構成している。   That is, the inner cylinder member 13 is inserted into the EGR passage 7 and the branch passage 11. Thus, the inner cylinder member 13 communicates the EGR passage 9 and the inner peripheral EGR passage 15 with the outer peripheral EGR passage 14 interposed therebetween in the branch passage 11. In addition, the outer periphery circle | round | yen which connected the outer periphery of the trough part 13B becomes circular. Moreover, the outer peripheral part of the inner cylinder member 13 is comprised from the vertex 13a of the peak part 13A, the site | part of the peak part 13A except the vertex 13a, and the outer peripheral part of the trough part 13B, and the vertex 13a is outer periphery. Part of the part.

次に、作用を説明する。
シリンダヘッド３に排気還流構造を形成するには、シリンダヘッド３の他側面３ｂにおいて、ＥＧＲ通路７の下流端７ｂ側からドリル等の工具によってＥＧＲ通路７に連通する位置まで穴開け加工を行うことで、ＥＧＲ通路７を形成する。 Next, the operation will be described.
In order to form the exhaust gas recirculation structure in the cylinder head 3, drilling is performed on the other side surface 3 b of the cylinder head 3 from the downstream end 7 b side of the EGR passage 7 to a position communicating with the EGR passage 7 with a tool such as a drill. Thus, the EGR passage 7 is formed.

次いで、シリンダヘッド３の他側面３ｂにおいて、ＥＧＲ通路９の下流端９ａ側からドリル等の工具によって分岐部１０に連通する位置まで穴開け加工によってＥＧＲ通路９を形成する。   Next, on the other side surface 3b of the cylinder head 3, the EGR passage 9 is formed by drilling from the downstream end 9a side of the EGR passage 9 to a position where the EGR passage 9 communicates with the branch portion 10 with a tool such as a drill.

次いで、ＥＧＲ通路７の下流端７ｂから分岐通路１１を通してＥＧＲ通路７に内筒部材１３を挿入した後、分岐通路１１にプラグ８を嵌合して、分岐通路１１を閉止する。ここで、図７に示すように、ＥＧＲ通路７に挿入される前の初期状態の内筒部材１３において、山部１３Ａの頂点１３ｂの曲率は、ＥＧＲ通路７の内周部７ｃの曲率よりも大きく形成されている。   Next, after inserting the inner cylinder member 13 into the EGR passage 7 from the downstream end 7b of the EGR passage 7 through the branch passage 11, the plug 8 is fitted into the branch passage 11, and the branch passage 11 is closed. Here, as shown in FIG. 7, in the inner cylinder member 13 in the initial state before being inserted into the EGR passage 7, the curvature of the apex 13 b of the peak portion 13 </ b> A is larger than the curvature of the inner peripheral portion 7 c of the EGR passage 7. Largely formed.

これにより、ＥＧＲ通路７の下流端７ｂから分岐通路１１を通してＥＧＲ通路７に内筒部材１３を挿入する過程で、山部１３Ａの頂点１３ｂがＥＧＲ通路７の内周部７ｃに沿って変形して曲率が小さくなる。このため、図８に示すように、山部１３Ａの頂点１３ａとＥＧＲ通路７の内周部７ｃとの接触面積が増大する。   Thus, in the process of inserting the inner cylinder member 13 from the downstream end 7b of the EGR passage 7 through the branch passage 11 into the EGR passage 7, the apex 13b of the peak portion 13A is deformed along the inner peripheral portion 7c of the EGR passage 7. Curvature decreases. For this reason, as shown in FIG. 8, the contact area of the apex 13a of the peak portion 13A and the inner peripheral portion 7c of the EGR passage 7 increases.

このように構成されたシリンダヘッド３において、図９に示すように、ＥＧＲ通路６からＥＧＲ通路７に導入された排気ガスは、実線の矢印Ｇ１で示すように外周側ＥＧＲ通路１４に沿って流れるとともに、破線の矢印Ｇ２で示すように内周側ＥＧＲ通路１５に沿って流れる。   In the cylinder head 3 configured as described above, as shown in FIG. 9, the exhaust gas introduced from the EGR passage 6 into the EGR passage 7 flows along the outer peripheral EGR passage 14 as shown by the solid line arrow G1. At the same time, it flows along the inner circumferential EGR passage 15 as indicated by a broken arrow G2.

外周側ＥＧＲ通路１４を流れるＥＧＲガスＧ１は、外周側ＥＧＲ通路１４からＥＧＲ通路９にそのまま流れる。ＥＧＲ通路９を流れるＥＧＲガスＧ３は、吸気マニホールド５から吸気ポート３Ｃを通してシリンダに導入される。   The EGR gas G1 flowing through the outer peripheral side EGR passage 14 flows from the outer peripheral side EGR passage 14 to the EGR passage 9 as it is. The EGR gas G3 flowing through the EGR passage 9 is introduced from the intake manifold 5 into the cylinder through the intake port 3C.

ＥＧＲ通路７に隣接してウォータジャケット１２が形成されており、内筒部材１３の山部１３Ａの頂点１３ａがＥＧＲ通路７の内周部７ｃに接触している。これにより、内筒部材１３は、ウォータジャケット１２の冷却水に晒されるＥＧＲ通路７の内周部７ｃとの間で熱交換され、外周側ＥＧＲ通路１４および内周側ＥＧＲ通路１５を流れるＥＧＲガスＧ１、Ｇ２が冷却される。また、ＥＧＲ通路９に隣接してウォータジャケット１２が形成されているため、ＥＧＲ通路９を流れるＥＧＲガスＧ３が冷却水によって冷却される。   A water jacket 12 is formed adjacent to the EGR passage 7, and the apex 13 a of the peak portion 13 </ b> A of the inner cylinder member 13 is in contact with the inner peripheral portion 7 c of the EGR passage 7. As a result, the inner cylinder member 13 exchanges heat with the inner peripheral portion 7 c of the EGR passage 7 exposed to the cooling water of the water jacket 12, and the EGR gas flowing through the outer peripheral EGR passage 14 and the inner peripheral EGR passage 15. G1 and G2 are cooled. Further, since the water jacket 12 is formed adjacent to the EGR passage 9, the EGR gas G3 flowing through the EGR passage 9 is cooled by the cooling water.

これにより、ＥＧＲガスが膨張することを防止して、吸気マニホールド５を通して吸気ポート３Ｃに吸入される吸入空気が膨張することを防止でき、充填効率が低下することを防止できる。   Thus, the EGR gas can be prevented from expanding, the intake air taken into the intake port 3C through the intake manifold 5 can be prevented from expanding, and the charging efficiency can be prevented from decreasing.

このように本実施の形態の排気還流構造によれば、ＥＧＲ通路７の内周部７ｃに外周部の少なくとも一部が接触するようにＥＧＲ通路７に挿入され、ＥＧＲ通路７との間で熱交換を行う内筒部材１３を備えている。
また、内筒部材１３が、ＥＧＲ通路７の内周部７ｃと内筒部材１３の外周部との間に外周側ＥＧＲ通路１４を形成するとともに、内筒部材１３の内部に内周側ＥＧＲ通路１５を形成する。 Thus, according to the exhaust gas recirculation structure of the present embodiment, the EGR passage 7 is inserted into the EGR passage 7 so that at least a part of the outer peripheral portion is in contact with the inner peripheral portion 7 c of the EGR passage 7. An inner cylinder member 13 for replacement is provided.
Further, the inner cylinder member 13 forms an outer periphery side EGR passage 14 between the inner periphery portion 7 c of the EGR passage 7 and the outer periphery portion of the inner cylinder member 13, and the inner periphery side EGR passage is formed inside the inner cylinder member 13. 15 is formed.

これに加えて、ウォータジャケット１２が、ＥＧＲ通路７の内周部７ｃに接触する内筒部材１３の外周部に隣接するように、シリンダヘッド３に形成される。
これにより、シリンダヘッド３に穴開け加工を施してＥＧＲ通路７、９を形成した後、ＥＧＲ通路７に内筒部材１３を挿入するだけの作業によってシリンダヘッド３に排気還流構造を形成できる。このため、シリンダヘッド３の外部にＥＧＲクーラを追加する必要が無く、エンジン１の製造コストを低減できる。 In addition, the water jacket 12 is formed on the cylinder head 3 so as to be adjacent to the outer peripheral portion of the inner cylindrical member 13 that contacts the inner peripheral portion 7c of the EGR passage 7.
As a result, the exhaust gas recirculation structure can be formed in the cylinder head 3 only by inserting the inner cylinder member 13 into the EGR passage 7 after forming the EGR passages 7 and 9 by drilling the cylinder head 3. For this reason, it is not necessary to add an EGR cooler outside the cylinder head 3, and the manufacturing cost of the engine 1 can be reduced.

特に、本実施の形態のシリンダヘッド３は、シリンダヘッド３の他側面３ｂに形成された開口端である下流端７ｂからＥＧＲ通路６に向かって延びるＥＧＲ通路７と、ＥＧＲ通路７の延びる方向の途中から分岐して吸気マニホールド５に向かって延びるＥＧＲ通路９と、ＥＧＲ通路７、９の分岐部１０と下流端７ｂとの間に形成される分岐通路１１とを含んで構成される。
これにより、穴開けによる簡単な作業でシリンダヘッド３に排気還流構造を形成でき、エンジン１の製造コストをより効果的に低減できる。 In particular, the cylinder head 3 of the present embodiment includes an EGR passage 7 extending from the downstream end 7b, which is an open end formed on the other side surface 3b of the cylinder head 3, toward the EGR passage 6, and a direction in which the EGR passage 7 extends. The EGR passage 9 is branched from the middle and extends toward the intake manifold 5, and the branch passage 11 is formed between the branch portion 10 of the EGR passages 7 and 9 and the downstream end 7b.
Thereby, the exhaust gas recirculation structure can be formed in the cylinder head 3 by a simple operation by drilling, and the manufacturing cost of the engine 1 can be more effectively reduced.

また、本実施の形態の内筒部材１３は、ステンレスで成形されているので、アルミニウムやアルミニウム合金に比べて内筒部材１３の板厚を薄くしても内筒部材１３の剛性を確保することができ、アルミニウムやアルミニウム合金に比べて内筒部材１３の熱伝導性を高くできる。したがって、ＥＧＲガスの冷却性能をより効果的に向上できる。   Moreover, since the inner cylinder member 13 of this Embodiment is shape | molded with stainless steel, the rigidity of the inner cylinder member 13 is ensured even if the plate | board thickness of the inner cylinder member 13 is made thin compared with aluminum and aluminum alloy. The thermal conductivity of the inner cylinder member 13 can be made higher than that of aluminum or aluminum alloy. Therefore, the cooling performance of EGR gas can be improved more effectively.

これに加えて、アルミニウムやアルミニウム合金よりも剛性の大きいステンレス製の内筒部材１３をプレス加工によって成形する場合に、内筒部材１３の板厚をアルミニウムやアルミニウム合金の内筒部材１３よりも薄くして成形できる。これにより、ＥＧＲ通路７の内周部７ｃに対する接触面積の大きい多葉形状の内筒部材１３を容易に成形できる。   In addition to this, when the inner cylinder member 13 made of stainless steel having a rigidity higher than that of aluminum or aluminum alloy is formed by press working, the plate thickness of the inner cylinder member 13 is thinner than that of the inner cylinder member 13 made of aluminum or aluminum alloy. Can be molded. Thereby, the multi-leaf shaped inner cylinder member 13 having a large contact area with the inner peripheral portion 7c of the EGR passage 7 can be easily formed.

また、本実施の形態の排気還流構造によれば、ＥＧＲ通路７に内筒部材１３を挿入して
内筒部材１３の山部１３Ａの頂点１３ａをＥＧＲ通路７の内周部７ｃに接触させている。
これにより、高温のＥＧＲガスと低温の冷却水とによって内筒部材１３が熱膨張と縮小を繰り返した場合であっても、従来の固定方法に比べて内筒部材１３に大きな応力が加わることがなく、内筒部材１３をシリンダヘッド３に安定して固定できる。このため、ＥＧＲ通路７に排気還流構造を設けた場合であっても、排気還流構造の信頼性を確保しつつ、ＥＧＲガスの冷却を安定して行うことができる。 Further, according to the exhaust gas recirculation structure of the present embodiment, the inner cylinder member 13 is inserted into the EGR passage 7, and the apex 13 a of the peak portion 13 </ b> A of the inner cylinder member 13 is brought into contact with the inner peripheral portion 7 c of the EGR passage 7. Yes.
Thereby, even when the inner cylinder member 13 repeats thermal expansion and contraction due to the high-temperature EGR gas and the low-temperature cooling water, a large stress is applied to the inner cylinder member 13 as compared with the conventional fixing method. The inner cylinder member 13 can be stably fixed to the cylinder head 3. For this reason, even when the exhaust gas recirculation structure is provided in the EGR passage 7, it is possible to stably cool the EGR gas while ensuring the reliability of the exhaust gas recirculation structure.

ここで、シリンダヘッド３は、穴開け加工によってＥＧＲ通路７、９を形成し、ＥＧＲ通路９を分岐部１０から斜め上方に傾斜して形成している。これにより、ＥＧＲガスが流れる正規のＥＧＲ通路７、９に対してＥＧＲガスの流れに関係のない分岐通路１１が形成される。このため、分岐通路１１にＥＧＲガスが滞留すると、ＥＧＲガスの冷却性能が低下するおそれがある。   Here, the cylinder head 3 forms the EGR passages 7 and 9 by drilling, and the EGR passage 9 is formed obliquely upward from the branch portion 10. As a result, a branch passage 11 that is not related to the flow of the EGR gas is formed with respect to the regular EGR passages 7 and 9 through which the EGR gas flows. For this reason, if the EGR gas stays in the branch passage 11, the cooling performance of the EGR gas may be deteriorated.

このため、本実施の形態の排気還流構造では、内筒部材１３の筒部１３Ｃを分岐通路１１まで延ばし、シリンダヘッド３に、分岐通路１１に隣接するウォータジャケット１２を形成した。
これにより、分岐通路１１に滞留するＥＧＲガスを冷却水によって冷却することができ、ＥＧＲガスの冷却性能を向上できる。 For this reason, in the exhaust gas recirculation structure of the present embodiment, the cylinder portion 13 </ b> C of the inner cylinder member 13 is extended to the branch passage 11, and the water jacket 12 adjacent to the branch passage 11 is formed in the cylinder head 3.
Thereby, the EGR gas staying in the branch passage 11 can be cooled by the cooling water, and the cooling performance of the EGR gas can be improved.

特に、本実施の形態の排気還流構造によれば、内筒部材１３が、内筒部材１３の円周方向において断続的にＥＧＲ通路７の内周部７ｃに接触し、内筒部材１３が、分岐通路１１において外周側ＥＧＲ通路１４を挟んで内周側ＥＧＲ通路１５とＥＧＲ通路９とを連通している。   In particular, according to the exhaust gas recirculation structure of the present embodiment, the inner cylinder member 13 intermittently contacts the inner peripheral portion 7c of the EGR passage 7 in the circumferential direction of the inner cylinder member 13, and the inner cylinder member 13 In the branch passage 11, the inner peripheral EGR passage 15 and the EGR passage 9 communicate with each other with the outer peripheral EGR passage 14 interposed therebetween.

これにより、内筒部材１３の内周側ＥＧＲ通路１５を通して分岐通路１１に流れるＥＧＲガスＧ２を冷却水によって冷却した後に、分岐通路１１から外周側ＥＧＲ通路１４を通してＥＧＲ通路９に流すことができる。   Thereby, after the EGR gas G2 flowing into the branch passage 11 through the inner peripheral side EGR passage 15 of the inner cylinder member 13 is cooled by the cooling water, it can flow from the branch passage 11 to the EGR passage 9 through the outer peripheral side EGR passage 14.

このため、ＥＧＲガスをより効果的に冷却しつつ、分岐通路１１から外周側ＥＧＲ通路１４を通してＥＧＲ通路９に流すことができ、ＥＧＲガスが分岐通路１１に滞留し続けることを防止できる。   For this reason, it is possible to flow the EGR gas from the branch passage 11 to the EGR passage 9 through the outer EGR passage 14 while cooling the EGR gas more effectively, and it is possible to prevent EGR gas from staying in the branch passage 11.

また、本実施の形態の排気還流構造によれば、内筒部材１３が、ＥＧＲ通路７の内周部７ｃに接触する頂点１３ａを有する山部１３Ａと、山部１３Ａの間に位置する谷部１３Ｂとが円周方向において交互に繰り返す多葉形状に形成される。   Further, according to the exhaust gas recirculation structure of the present embodiment, the inner cylinder member 13 has a peak portion 13A having a vertex 13a that contacts the inner peripheral portion 7c of the EGR passage 7, and a valley portion located between the peak portions 13A. 13B is formed in a multi-leaf shape that alternately repeats in the circumferential direction.

これにより、内筒部材１３とＥＧＲ通路７の内周部７ｃとの接触面積を増大させることができ、内筒部材１３と冷却水との熱交換の効率を向上できる。このため、内筒部材１３の外周側ＥＧＲ通路１４および内周側ＥＧＲ通路１５を流れるＥＧＲガスの冷却性能をより効果的に向上できる。   Thereby, the contact area of the inner cylinder member 13 and the inner peripheral part 7c of the EGR passage 7 can be increased, and the efficiency of heat exchange between the inner cylinder member 13 and the cooling water can be improved. For this reason, the cooling performance of the EGR gas flowing through the outer peripheral side EGR passage 14 and the inner peripheral side EGR passage 15 of the inner cylinder member 13 can be improved more effectively.

特に、本実施の形態の内筒部材１３は、山部１３Ａの頂点１３ａをＥＧＲ通路７の内周部７ｃに沿って変形させて圧入し、頂点１３ａの曲率を小さくすることで、山部１３Ａの頂点１３ａとＥＧＲ通路７の内周部７ｃとの接触面積を増大させることができる。これにより、内筒部材１３と冷却水との熱交換の効率をより効果的に向上できる。   In particular, the inner cylinder member 13 of the present embodiment deforms and press-fits the apex 13a of the peak portion 13A along the inner peripheral portion 7c of the EGR passage 7, thereby reducing the curvature of the apex 13a. The contact area between the apex 13a of the EGR passage 7 and the inner peripheral portion 7c of the EGR passage 7 can be increased. Thereby, the efficiency of heat exchange with the inner cylinder member 13 and cooling water can be improved more effectively.

これに加えて、山部１３Ａの頂点１３ａとＥＧＲ通路７の内周部７ｃとの接触面積を増大させることができるので、内筒部材１３をＥＧＲ通路７に安定して固定でき、内筒部材１３が熱膨張と縮小を繰り返した場合であっても、内筒部材１３をＥＧＲ通路７により効果的に安定して固定できる。   In addition to this, since the contact area between the apex 13a of the peak portion 13A and the inner peripheral portion 7c of the EGR passage 7 can be increased, the inner cylinder member 13 can be stably fixed to the EGR passage 7, and the inner cylinder member Even if 13 repeats thermal expansion and contraction, the inner cylinder member 13 can be effectively and stably fixed by the EGR passage 7.

これに加えて、シリンダヘッド３と内筒部材１３の材料が異なる場合に、内筒部材１３とシリンダヘッド３との熱膨張率の差によって内筒部材１３がＥＧＲ通路７に対して位置ずれすることを抑制できる。   In addition, when the materials of the cylinder head 3 and the inner cylinder member 13 are different, the inner cylinder member 13 is displaced with respect to the EGR passage 7 due to the difference in thermal expansion coefficient between the inner cylinder member 13 and the cylinder head 3. This can be suppressed.

また、内周側ＥＧＲ通路１５を流れるＥＧＲガスを、分岐通路１１においてウォータジャケット１２によって冷却することができるので、内周側ＥＧＲ通路１５を流れるＥＧＲガスの冷却性能をより効果的に向上できる。   In addition, since the EGR gas flowing through the inner peripheral EGR passage 15 can be cooled by the water jacket 12 in the branch passage 11, the cooling performance of the EGR gas flowing through the inner peripheral EGR passage 15 can be more effectively improved.

なお、本実施の形態の内筒部材１３は、分岐通路１１側に山部１３Ａの頂点１３ａの外周を結んだ外周円よりも径の小さい円状の筒部１３Ｃを有するが、これに限定される必要はない。例えば、図１０に示すように、内筒部材１３の延びる方向に亙って山部１３Ａを形成することで内筒部材１３を同一径としてもよい。   The inner cylindrical member 13 of the present embodiment has a circular cylindrical portion 13C having a smaller diameter than the outer peripheral circle connecting the outer periphery of the apex 13a of the peak portion 13A on the branch passage 11 side, but is not limited thereto. There is no need to For example, as shown in FIG. 10, the inner cylinder member 13 may have the same diameter by forming a mountain portion 13 </ b> A along the extending direction of the inner cylinder member 13.

このようにすれば、内筒部材１３の内周側ＥＧＲ通路１５の開口面積を内筒部材１３の延びる方向に向かって同一径で大きくできる。このため、内周側ＥＧＲ通路１５から分岐通路１１に流れるＥＧＲガスの背圧が大きくなることを防止できる。   In this way, the opening area of the inner peripheral EGR passage 15 of the inner cylinder member 13 can be increased with the same diameter in the direction in which the inner cylinder member 13 extends. For this reason, it is possible to prevent the back pressure of the EGR gas flowing from the inner circumferential EGR passage 15 to the branch passage 11 from increasing.

また、本実施の形態では、内筒部材１３をＥＧＲ通路７と分岐通路１１に亙って設けているが、これに限定されるものではない。   Moreover, in this Embodiment, although the inner cylinder member 13 is provided over the EGR channel | path 7 and the branch channel | path 11, it is not limited to this.

具体的には、図１１に示すように、内筒部材１３に加えて、ＥＧＲ通路９に内筒部材２０を設けてもよい。図１２において、内筒部材２０は、内筒部材２０の延びる方向の中心軸（車両の前後方向に延びる中心軸）に対して直交する方向の断面形状が、山部２０Ａと山部２０Ａの間に位置する谷部２０Ｂとが円周方向において交互に繰り返す多葉形状に形成されており、山部２０Ａの径は、内筒部材２０の延びる方向に亙って同一径に形成されている。   Specifically, as shown in FIG. 11, in addition to the inner cylinder member 13, an inner cylinder member 20 may be provided in the EGR passage 9. In FIG. 12, the inner cylinder member 20 has a cross-sectional shape in a direction orthogonal to a central axis (a central axis extending in the front-rear direction of the vehicle) in the direction in which the inner cylindrical member 20 extends, between the peak part 20A and the peak part 20A. Are formed in a multi-leaf shape that alternately repeats in the circumferential direction, and the diameter of the peak portion 20A is formed to be the same diameter in the extending direction of the inner cylindrical member 20.

内筒部材２０は、内筒部材２０の円周方向において断続的にＥＧＲ通路９の内周部９ｃに接触しており、ＥＧＲ通路９は、内筒部材２０の外周部とＥＧＲ通路９の内周部９ｃとの間に形成された外周側ＥＧＲ通路２１と、内筒部材２０の内部に形成された内周側ＥＧＲ通路２２とを備え、ウォータジャケット１２に上下方向で挟まれるようにしてＥＧＲ通路９に挿入されている。   The inner cylindrical member 20 is intermittently in contact with the inner peripheral portion 9c of the EGR passage 9 in the circumferential direction of the inner cylindrical member 20, and the EGR passage 9 is formed between the outer peripheral portion of the inner cylindrical member 20 and the EGR passage 9. An EGR passage 21 formed between the outer peripheral side 9c and the inner EGR passage 22 formed inside the inner cylinder member 20 is provided between the peripheral portion 9c and the EGR so as to be sandwiched between the water jacket 12 in the vertical direction. It is inserted in the passage 9.

このようにすれば、ＥＧＲ通路７および分岐通路１１から外周側ＥＧＲ通路２１に導入されるＥＧＲガスを、冷却水によって上下方向から冷却水で冷却できる。これにより、高温のＥＧＲガスと低温の冷却水とによって内筒部材２０が熱膨張と縮小を繰り返した場合であっても、従来のように内筒部材２０を固定するものに比べて内筒部材１３に大きな応力が加わることがなく、内筒部材２０をシリンダヘッド３に安定して固定できる。   In this way, the EGR gas introduced from the EGR passage 7 and the branch passage 11 into the outer peripheral EGR passage 21 can be cooled with the cooling water from above and below by the cooling water. Thereby, even when the inner cylinder member 20 repeats thermal expansion and contraction due to the high-temperature EGR gas and the low-temperature cooling water, the inner cylinder member is compared with the conventional case in which the inner cylinder member 20 is fixed. The inner cylinder member 20 can be stably fixed to the cylinder head 3 without applying a large stress to 13.

このため、ＥＧＲ通路７およびＥＧＲ通路９に排気還流構造を設けた場合であっても、排気還流構造の信頼性を確保しつつ、ＥＧＲガスの冷却を安定して行うことができる。特に、本実施の形態の排気還流構造は、ＥＧＲ通路７、９を流れるＥＧＲガスを内筒部材１３、２０によって冷却できるので、熱交換面積を大きくすることができ、ＥＧＲガスをより効果的に冷却することができる。   Therefore, even when the exhaust gas recirculation structure is provided in the EGR passage 7 and the EGR passage 9, it is possible to stably cool the EGR gas while ensuring the reliability of the exhaust gas recirculation structure. In particular, the exhaust gas recirculation structure of the present embodiment can cool the EGR gas flowing through the EGR passages 7 and 9 by the inner cylinder members 13 and 20, so that the heat exchange area can be increased, and the EGR gas can be more effectively used. Can be cooled.

また、内筒部材１３を廃止して、図１３に示すように、ＥＧＲ通路９に図１２に示す内筒部材２０を設けて構成してもよい。このようにしても、内筒部材２０の外周側ＥＧＲ通路２１を流れるＥＧＲガスを上下方向から冷却できる。また、内筒部材１３を廃止して内筒部材１３よりも短い内筒部材２０を設置することで、ＥＧＲ通路７、９を流れるＥＧＲガスが内筒部材２０から受ける抵抗を少なくできる。このため、ＥＧＲガスの圧力損失を低減できる。   Further, the inner cylinder member 13 may be eliminated and the EGR passage 9 may be provided with the inner cylinder member 20 shown in FIG. 12 as shown in FIG. Even in this case, the EGR gas flowing in the outer peripheral side EGR passage 21 of the inner cylinder member 20 can be cooled from the vertical direction. Moreover, the resistance which EGR gas which flows through the EGR passages 7 and 9 receives from the inner cylinder member 20 can be reduced by eliminating the inner cylinder member 13 and installing the inner cylinder member 20 shorter than the inner cylinder member 13. For this reason, the pressure loss of EGR gas can be reduced.

さらに、図１４に示すように、内筒部材２５を分岐部１０の手前、すなわち、分岐部１０よりも上流側まで延ばしてもよい。図１５において、内筒部材２５
は、内筒部材２５の延びる方向の中心軸（車両の前後方向に延びる中心軸）に対して直交する方向の断面形状が、山部２５Ａと山部２５Ａの間に位置する谷部２５Ｂとが円周方向において交互に繰り返す多葉形状に形成されており、山部２５Ａの径は、内筒部材２５の延びる方向に亙って同一径に形成されている。 Furthermore, as shown in FIG. 14, the inner cylinder member 25 may be extended to the front side of the branch portion 10, that is, to the upstream side of the branch portion 10. In FIG. 15, the inner cylinder member 25
The cross-sectional shape in a direction orthogonal to the central axis in the direction in which the inner cylinder member 25 extends (the central axis extending in the front-rear direction of the vehicle) is a trough 25B located between the peak 25A and the peak 25A. It is formed in a multi-leaf shape that repeats alternately in the circumferential direction, and the diameter of the peak portion 25 </ b> A is formed to be the same diameter in the extending direction of the inner cylinder member 25.

内筒部材２５は、内筒部材２５の円周方向において断続的にＥＧＲ通路７の内周部７ｃに接触しており、ＥＧＲ通路７は、内筒部材２５の外周部とＥＧＲ通路７の内周部７ｃとの間に形成された外周側ＥＧＲ通路２６と、内筒部材２５の内部に形成された内周側ＥＧＲ通路２７とを備えている。   The inner cylindrical member 25 is intermittently in contact with the inner peripheral portion 7 c of the EGR passage 7 in the circumferential direction of the inner cylindrical member 25, and the EGR passage 7 is formed between the outer peripheral portion of the inner cylindrical member 25 and the EGR passage 7. An outer peripheral EGR passage 26 formed between the peripheral portion 7 c and an inner peripheral EGR passage 27 formed inside the inner cylinder member 25 is provided.

このようにすれば、図４に示す内筒部材１３に比べて内筒部材２５の長さを短くできるので、ＥＧＲ通路７を流れるＥＧＲガスが内筒部材２５から受ける抵抗を少なくでき、ＥＧＲガスの圧力損失を低減できる。   In this way, since the length of the inner cylinder member 25 can be shortened compared to the inner cylinder member 13 shown in FIG. 4, the resistance received by the EGR gas flowing through the EGR passage 7 from the inner cylinder member 25 can be reduced, and the EGR gas Pressure loss can be reduced.

（他の実施の形態）
図１６において、ＥＧＲ通路７には内筒部材３１が挿入されている。図１７、図１８において、内筒部材３１は、内筒部材３１の延びる方向の中心軸Ｏ（図１７参照）に対して直交する方向の断面形状を、山部３２Ａと、隣り合う山部３２Ａの間に位置する谷部３２Ｂと、が円周方向において交互に繰り返す複数のフィン部３２を有する多葉形状に形成されている。 (Other embodiments)
In FIG. 16, an inner cylinder member 31 is inserted into the EGR passage 7. 17 and 18, the inner cylindrical member 31 has a cross-sectional shape in a direction orthogonal to the central axis O (see FIG. 17) in the direction in which the inner cylindrical member 31 extends, and a mountain portion 32A adjacent to the mountain portion 32A. Are formed in a multi-leaf shape having a plurality of fin portions 32 that repeat alternately in the circumferential direction.

図１９において、ＥＧＲ通路７の内周部７ｃとフィン部３２の外周部との間に外周側ＥＧＲ通路３４が形成されており、フィン部３２よりも内側には内周側ＥＧＲ通路３５が形成されている。   In FIG. 19, an outer peripheral EGR passage 34 is formed between the inner peripheral portion 7 c of the EGR passage 7 and the outer peripheral portion of the fin portion 32, and an inner peripheral side EGR passage 35 is formed inside the fin portion 32. Has been.

図１６において、ＥＧＲ通路７の内周部７ｂは、円周方向の一部がウォータジャケット１２に隣接しており、内筒部材３１は、山部３２Ａの一部である上側がウォータジャケット１２に隣接するＥＧＲ通路７の内周部７ｃの上側部分に接触している。   In FIG. 16, the inner peripheral portion 7 b of the EGR passage 7 is partially adjacent to the water jacket 12 in the circumferential direction, and the inner cylinder member 31 has an upper portion that is a part of the mountain portion 32 </ b> A at the water jacket 12. The upper part of the inner peripheral part 7c of the adjacent EGR passage 7 is in contact.

図１７、図１８において、内筒部材３１は、中実状の棒状部材３３を備えている。棒状部材３３は、谷部３２Ｂの内周部３２ｂに挿入自在に設けられており、谷部３２Ｂの内周部３２ｂに接触して内筒部材３１の延びる方向に延びている。   17 and 18, the inner cylinder member 31 includes a solid bar member 33. The rod-shaped member 33 is provided so as to be freely inserted into the inner peripheral portion 32b of the valley portion 32B, and extends in the direction in which the inner cylinder member 31 extends in contact with the inner peripheral portion 32b of the valley portion 32B.

図１７において、棒状部材３３は、内筒部材３１に挿入される前の状態（初期状態）において、谷部３２Ｂの内周部３２ｂを結んだ円３２Ｃの直径Ｒ１よりも大きい直径Ｒ２に形成されている。   In FIG. 17, the rod-shaped member 33 is formed to have a diameter R2 larger than the diameter R1 of the circle 32C connecting the inner peripheral portion 32b of the valley portion 32B in a state (initial state) before being inserted into the inner cylinder member 31. ing.

これにより、谷部３２Ｂの内周部３２ｂに棒状部材３３が挿入されると、谷部３２Ｂが棒状部材３３によって径方向外方に拡大し、フィン部３２が径方向外方に拡大するように変形する。 棒状部材３３の延びる方向の端部にはテーパ部３３Ａが形成されており、テーパ部３３Ａは、先細り形状に形成されている。   Thus, when the rod-shaped member 33 is inserted into the inner peripheral portion 32b of the valley portion 32B, the valley portion 32B is expanded radially outward by the rod-shaped member 33, and the fin portion 32 is expanded radially outward. Deform. A taper portion 33A is formed at the end of the rod-shaped member 33 in the extending direction, and the taper portion 33A is formed in a tapered shape.

次に、作用を説明する。
内筒部材３１をシリンダヘッド３に取付けるには、ＥＧＲ通路７の下流端７ｂから分岐通路１１を通してＥＧＲ通路７に内筒部材３１を挿入する。このとき、内筒部材３１には棒状部材３３が取付けられていないので、山部３３ＡとＥＧＲ通路７の内周部７ｃとは微小な隙間を介して離隔するか、低い圧力で接触しながら、内筒部材３１がＥＧＲ通路７に挿入される。 Next, the operation will be described.
In order to attach the inner cylinder member 31 to the cylinder head 3, the inner cylinder member 31 is inserted into the EGR passage 7 from the downstream end 7 b of the EGR passage 7 through the branch passage 11. At this time, since the rod-shaped member 33 is not attached to the inner cylindrical member 31, the mountain portion 33A and the inner peripheral portion 7c of the EGR passage 7 are separated from each other through a minute gap or while being in contact with a low pressure, The inner cylinder member 31 is inserted into the EGR passage 7.

この後、谷部３２Ｂの内周部３２ｂに対してテーパ部３３Ａから棒状部材３３を挿入する。これにより、谷部３２Ｂが棒状部材３３によって径方向外方に拡大し、フィン部３２が径方向外方に拡大するように変形する。   Thereafter, the rod-shaped member 33 is inserted from the tapered portion 33A into the inner peripheral portion 32b of the valley portion 32B. Thereby, the trough part 32B expands radially outward by the rod-shaped member 33, and the fin part 32 is deformed so as to expand radially outward.

このため、内筒部材３１がＥＧＲ通路７に挿入された状態において、棒状部材３３が谷部３２Ｂの内周部３２ｂに挿入される前に比べ、棒状部材３３が谷部３２Ｂの内周部３２ｂに挿入された方が、ＥＧＲ通路７に対する山部３２Ａの接触圧が高くなる。   For this reason, in the state in which the inner cylinder member 31 is inserted into the EGR passage 7, the rod-shaped member 33 is inserted into the inner peripheral portion 32b of the valley portion 32B, compared to before the rod-shaped member 33 is inserted into the inner peripheral portion 32b of the valley portion 32B. The contact pressure of the peak portion 32 </ b> A with respect to the EGR passage 7 becomes higher when inserted into the EGR passage 7.

本実施の形態の排気還流構造によれば、内筒部材３１が、谷部３２Ｂの内周部３２ｂに挿入自在に設けられ、谷部３２の内周部３２ｂに接触するようにして内筒部材３１の延びる方向に延びる棒状部材３３を有する。   According to the exhaust gas recirculation structure of the present embodiment, the inner cylindrical member 31 is provided so as to be freely inserted into the inner peripheral portion 32b of the valley portion 32B, and is in contact with the inner peripheral portion 32b of the valley portion 32. It has the rod-shaped member 33 extended in the direction where 31 extends.

棒状部材３３は、谷部３２Ｂの内周部３２ｂに挿入される前の状態において、谷部３２Ｂの内周部３２ｂを結んだ円３２Ｃの直径Ｒ１が棒状部材３３の直径Ｒ２よりも小さく形成されている。   The rod-shaped member 33 is formed such that the diameter R1 of the circle 32C connecting the inner peripheral portion 32b of the valley portion 32B is smaller than the diameter R2 of the rod-shaped member 33 before being inserted into the inner peripheral portion 32b of the valley portion 32B. ing.

特に、内筒部材３１がＥＧＲ通路７に挿入された状態において、棒状部材３３が谷部３２Ｂの内周部３２ｂに挿入される前に比べ、棒状部材３３が谷部３２Ｂの内周部３２ｂに挿入された方が、ＥＧＲ通路７に対する山部３２Ａの接触圧が高くなる。   In particular, in a state where the inner cylindrical member 31 is inserted into the EGR passage 7, the rod-shaped member 33 is located on the inner peripheral portion 32 b of the valley portion 32 </ b> B as compared to before the rod-shaped member 33 is inserted into the inner peripheral portion 32 b of the valley portion 32 </ b> B. The contact pressure of the peak portion 32 </ b> A with respect to the EGR passage 7 becomes higher when inserted.

これにより、内筒部材３１をＥＧＲ通路７に挿入する際に、山部３２ＡをＥＧＲ通路７の内周部７ｃに沿って変形させて圧入する必要がなく、ＥＧＲ通路７の内周部７ｃに圧入による痕跡が残ることを防止できる。
痕跡は、内筒部材３１をＥＧＲ通路７に圧入する際に、内筒部材３１によってＥＧＲ通路７の内周部７ｃに形成される凹状の引っ掻き傷であり、内筒部材３１の圧入方向に沿って形成される可能性がある。 Thus, when the inner cylinder member 31 is inserted into the EGR passage 7, there is no need to deform and press-fit the mountain portion 32 </ b> A along the inner peripheral portion 7 c of the EGR passage 7. It is possible to prevent traces due to press-fitting.
The trace is a concave scratch formed in the inner peripheral portion 7c of the EGR passage 7 by the inner cylinder member 31 when the inner cylinder member 31 is press-fitted into the EGR passage 7, and along the press-fitting direction of the inner cylinder member 31. May be formed.

このため、ＥＧＲガスに含まれる未燃の燃料（煤、炭化水素等）が凹状の痕跡に付着して徐々に堆積してデポジットとなり、このデポジットによってＥＧＲガスの圧力損失やシリンダヘッド３の腐食等が発生することを防止できる。   For this reason, unburned fuel (soot, hydrocarbons, etc.) contained in the EGR gas adheres to the concave traces and gradually accumulates to form deposits. This deposit causes pressure loss of the EGR gas, corrosion of the cylinder head 3, etc. Can be prevented.

また、本実施の形態のシリンダヘッド３によれば、ＥＧＲ通路７の内周部７ｂは、円周方向の一部がウォータジャケット１２に隣接しており、内筒部材３１は、山部３２Ａの一部である上側がウォータジャケット１２に隣接するＥＧＲ通路７の内周部７ｃの上側部分に接触している。
これにより、ＥＧＲ通路７の周囲を取り囲むようにウォータジャケット１２を形成する必要がないので、シリンダヘッド３の小型化を図ることができる。 Further, according to the cylinder head 3 of the present embodiment, the inner circumferential portion 7b of the EGR passage 7 is partially adjacent to the water jacket 12 in the circumferential direction, and the inner cylindrical member 31 is formed of the mountain portion 32A. A part of the upper side is in contact with the upper part of the inner peripheral part 7 c of the EGR passage 7 adjacent to the water jacket 12.
Thereby, since it is not necessary to form the water jacket 12 so that the circumference | surroundings of the EGR channel | path 7 may be enclosed, size reduction of the cylinder head 3 can be achieved.

但し、この場合には、ウォータジャケット１２側のＥＧＲ通路７の内周部７ｃに沿って流れるＥＧＲガスの冷却を効果的に行うことができる反面、ウォータジャケット１２と反対側のＥＧＲ通路７の内周部７ｃに沿って流れるＥＧＲガスの冷却を効果的に行うことができないおそれがある。   However, in this case, the EGR gas flowing along the inner peripheral portion 7c of the EGR passage 7 on the water jacket 12 side can be effectively cooled, but the inner side of the EGR passage 7 on the opposite side to the water jacket 12 is provided. There is a possibility that the EGR gas flowing along the peripheral portion 7c cannot be effectively cooled.

これに対して、本実施の形態の棒状部材３３は、谷部３２Ｂの内周部３２ｂに接触するようにして内筒部材３１の延びる方向に延びている。これにより、図１９の矢印Ｃで示すように、ウォータジャケット１２側のＥＧＲ通路７の内周部７ｃに接触する山部３２Ａに伝達される低温の熱をフィン部３２から谷部３２Ｂを介して棒状部材３３に伝達させることができる。   In contrast, the rod-shaped member 33 of the present embodiment extends in the direction in which the inner cylinder member 31 extends so as to be in contact with the inner peripheral portion 32b of the valley portion 32B. Accordingly, as indicated by an arrow C in FIG. 19, the low-temperature heat transmitted to the peak portion 32A that contacts the inner peripheral portion 7c of the EGR passage 7 on the water jacket 12 side is transferred from the fin portion 32 through the valley portion 32B. It can be transmitted to the rod-shaped member 33.

そして、棒状部材３３からウォータジャケット１２と反対側（棒状部材３３に対して下側）の谷部３２Ｂに熱を伝達し、この熱をフィン部３２から山部３２Ａを介してウォータジャケット１２に隣接していないＥＧＲ通路７の内周部７ｃに伝達できる。   Then, heat is transmitted from the bar-shaped member 33 to the valley 32B opposite to the water jacket 12 (lower side with respect to the bar-shaped member 33), and this heat is adjacent to the water jacket 12 from the fin 32 through the peak 32A. It can be transmitted to the inner peripheral portion 7c of the EGR passage 7 that is not.

これにより、温度の低いウォータジャケット１２に隣接するＥＧＲ通路７の内周部７ｃと温度の高いＥＧＲ通路７の内周部７ｃとの温度差を小さくして、内筒部材３１の外周側ＥＧＲ３４および内周側ＥＧＲ通路３５を流れるＥＧＲガスの冷却性能をより効果的に向上できる。   Thus, the temperature difference between the inner peripheral portion 7c of the EGR passage 7 adjacent to the low temperature water jacket 12 and the inner peripheral portion 7c of the high temperature EGR passage 7 is reduced, and the outer peripheral side EGR 34 of the inner cylinder member 31 and The cooling performance of the EGR gas flowing through the inner peripheral EGR passage 35 can be improved more effectively.

また、本実施の形態の内筒部材３１は、棒状部材３３の延びる方向の端部に先細り形状のテーパ部３３Ａが形成されている。これにより、棒状部材３３をテーパ部３３Ａ側から谷部３２Ｂの内周部３２ｂに挿入することで、内筒部材３３を谷部３２Ｂの内周部３２ｂに容易に挿入できる。   Further, in the inner cylinder member 31 of the present embodiment, a tapered portion 33 </ b> A having a tapered shape is formed at an end portion in the extending direction of the rod-shaped member 33. Thereby, the inner cylinder member 33 can be easily inserted in the inner peripheral part 32b of the trough part 32B by inserting the rod-shaped member 33 into the inner peripheral part 32b of the trough part 32B from the taper part 33A side.

なお、棒状部材３３は、中実形状ではなく、図２０に示すように、筒状の棒状部材３６としてもよい。このようにすれば、棒状部材３６の内部を通してＥＧＲガスを流すことができるので、ＥＧＲ通路７を流れるＥＧＲガスの圧力損失が発生することを抑制できる。   Note that the rod-shaped member 33 is not a solid shape, and may be a cylindrical rod-shaped member 36 as shown in FIG. In this way, since the EGR gas can flow through the inside of the rod-shaped member 36, the occurrence of pressure loss of the EGR gas flowing through the EGR passage 7 can be suppressed.

本発明の実施の形態を開示したが、当業者によっては本発明の範囲を逸脱することなく変更が加えられうることは明白である。すべてのこのような修正および等価物が次の請求項に含まれることが意図されている。   While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

３...シリンダヘッド、３ａ...一側面、３ｂ...他側面、５...吸気マニホールド（吸気部）、６...ＥＧＲ通路（排気部）、７...ＥＧＲ通路（第１のＥＧＲ通路、ＥＧＲ通路）、７ｂ...下流端（開口端）、７ｃ...内周部、８...プラグ（閉止部材）、９...ＥＧＲ通路（第２のＥＧＲ通路、ＥＧＲ通路）、１０...分岐部、１１...分岐通路、１２...ウォータジャケット、１３，２０，２５，３１...内筒部材、１３Ａ，２０Ａ，２５Ａ，３２Ａ...山部、１３ａ...頂点（外周部の一部）、１３Ｂ，２０Ｂ，２５Ｂ，３２Ｂ...谷部、１４，２１，２６，３４...外周側ＥＧＲ通路、１５，２２，２７，３５...内周側ＥＧＲ通路、３３...棒状部材   3 ... Cylinder head, 3a ... One side, 3b ... Other side, 5 ... Intake manifold (intake part), 6 ... EGR passage (exhaust part), 7 ... EGR passage ( 1st EGR passage, EGR passage), 7b ... downstream end (open end), 7c ... inner periphery, 8 ... plug (closing member), 9 ... EGR passage (second EGR passage) (Passage, EGR passage), 10 ... branching portion, 11 ... branching passage, 12 ... water jacket, 13, 20, 25, 31 ... inner cylinder member, 13A, 20A, 25A, 32A ... .Crest, 13a ... apex (part of outer periphery), 13B, 20B, 25B, 32B ... trough, 14, 21, 26, 34 ... outer periphery EGR passage, 15, 22, 27 35 ... Inner circumference EGR passage, 33 ... Rod-shaped member

Claims (8)

冷却水が流れるウォータジャケット、排気ガスを排出する排気部および吸入空気が導入される吸気部を有するシリンダヘッドに設けられた排気還流構造であって、
前記シリンダヘッドに形成され、前記排気部と前記吸気部とを連通するＥＧＲ通路と、
前記ＥＧＲ通路の内周部に外周部の少なくとも一部が接触するように前記ＥＧＲ通路に挿入され、前記ＥＧＲ通路の内周部との間で熱交換を行う内筒部材とを備え、
前記ＥＧＲ通路は、前記ＥＧＲ通路の内周部と前記内筒部材の外周部との間に形成された外周側ＥＧＲ通路と前記内筒部材の内部に形成された内周側ＥＧＲ通路とを含んで構成され、
前記ウォータジャケットが、前記ＥＧＲ通路に隣接するように前記シリンダヘッドに形成され、
前記排気部が前記シリンダヘッドの一側面側に形成されるとともに、前記吸気部が前記シリンダヘッドの他側面側に形成され、
前記ＥＧＲ通路は、前記シリンダヘッドの前記他側面に形成された開口端から前記排気部に向かって延びる第１のＥＧＲ通路と、前記第１のＥＧＲ通路の延びる方向の途中から分岐して前記吸気部に向かって延びる第２のＥＧＲ通路と、前記第１のＥＧＲ通路および第２のＥＧＲ通路の分岐部から前記開口端まで延びる分岐通路とを有し、
前記分岐通路が閉止部材によって閉止されており、
前記第１のＥＧＲ通路に前記内筒部材が挿入されているとともに、前記内筒部材が前記分岐通路まで延ばされており、
前記ウォータジャケットは、前記分岐通路に隣接していることを特徴とするシリンダヘッドの排気還流構造。 An exhaust gas recirculation structure provided in a cylinder head having a water jacket through which cooling water flows, an exhaust unit for exhaust gas exhaust, and an intake unit into which intake air is introduced,
An EGR passage formed in the cylinder head and communicating the exhaust part and the intake part;
An inner cylinder member that is inserted into the EGR passage so that at least a part of the outer peripheral portion is in contact with the inner peripheral portion of the EGR passage, and performs heat exchange with the inner peripheral portion of the EGR passage;
The EGR passage includes an outer peripheral side EGR passage formed between an inner peripheral portion of the EGR passage and an outer peripheral portion of the inner cylindrical member, and an inner peripheral side EGR passage formed inside the inner cylindrical member. Consists of
The water jacket is formed on the cylinder head so as to be adjacent to the EGR passage ;
The exhaust part is formed on one side of the cylinder head, and the intake part is formed on the other side of the cylinder head.
The EGR passage branches from a first EGR passage extending from an open end formed on the other side surface of the cylinder head toward the exhaust portion, and from the middle of the extending direction of the first EGR passage, and the intake air A second EGR passage extending toward the portion, and a branch passage extending from the branch portion of the first EGR passage and the second EGR passage to the opening end,
The branch passage is closed by a closing member;
The inner cylinder member is inserted into the first EGR passage, and the inner cylinder member is extended to the branch passage,
The exhaust recirculation structure for a cylinder head, wherein the water jacket is adjacent to the branch passage . 前記内筒部材の外周部は、前記内筒部材の円周方向において前記ＥＧＲ通路の内周部に断続的に接触し、
前記内筒部材は、前記分岐通路において、前記外周側ＥＧＲ通路を挟んで前記内周側ＥＧＲ通路と前記第２のＥＧＲ通路とを連通することを特徴とする請求項１に記載のシリンダヘッドの排気還流構造。 The outer peripheral part of the inner cylinder member intermittently contacts the inner peripheral part of the EGR passage in the circumferential direction of the inner cylinder member,
The inner cylinder member, in the branch passage, of the cylinder head according to claim 1, characterized by communicating the second EGR passage and the inner circumferential side EGR passage across the outer peripheral side EGR passage Exhaust gas recirculation structure. 前記内筒部材は、前記内筒部材の延びる方向の中心軸に対して直交する方向の断面形状が、前記ＥＧＲ通路の内周部に接触する山部と、前記山部の間に位置する谷部とが円周方向において交互に繰り返す多葉形状に形成されていることを特徴とする請求項１または請求項２に記載のシリンダヘッドの排気還流構造。 The inner cylinder member has a valley in which a cross-sectional shape in a direction orthogonal to a central axis in a direction in which the inner cylinder member extends is located between a peak part contacting the inner peripheral part of the EGR passage and the peak part. The exhaust recirculation structure for a cylinder head according to claim 1 or 2, wherein the portion is formed in a multi-leaf shape that alternately repeats in the circumferential direction . 前記内筒部材は、前記谷部の内周部に挿入自在に設けられ、前記谷部の内周部に接触するようにして前記内筒部材の延びる方向に延びる棒状部材を有し、
前記棒状部材は、前記谷部の内周部に挿入される前の状態において、前記谷部の内周部を結んだ円の直径が前記棒状部材の直径よりも小さく形成されていることを特徴とする請求項３に記載のシリンダヘッドの排気還流構造。 The inner cylinder member is provided so as to be freely inserted into the inner peripheral part of the valley part, and has a rod-like member extending in the extending direction of the inner cylinder member so as to be in contact with the inner peripheral part of the valley part,
In the state before the rod-shaped member is inserted into the inner peripheral portion of the valley, the diameter of the circle connecting the inner peripheral portions of the valley is smaller than the diameter of the rod-shaped member. The exhaust gas recirculation structure for a cylinder head according to claim 3 . 前記内筒部材が前記ＥＧＲ通路に挿入された状態において、前記棒状部材が前記谷部の内周部に挿入される前に比べ、前記棒状部材が前記谷部の内周部に挿入された方が、前記ＥＧＲ通路に対する前記山部の接触圧が高くなることを特徴とする請求項４に記載のシリンダヘッドの排気還流構造。 In a state where the inner cylindrical member is inserted into the EGR passage, the rod-shaped member is inserted into the inner peripheral portion of the valley portion compared to before the rod-shaped member is inserted into the inner peripheral portion of the valley portion. 5. The exhaust gas recirculation structure for a cylinder head according to claim 4 , wherein a contact pressure of the peak portion with respect to the EGR passage is increased . 前記棒状部材は、筒状に形成されていることを特徴とする請求項４または請求項５に記載のシリンダヘッドの排気還流構造。 The rod member is an exhaust gas recirculation structure of a cylinder head according to claim 4 or claim 5, characterized in that it is formed in a cylindrical shape. 前記棒状部材の延びる方向の端部に先細り形状のテーパ部が形成されていることを特徴とする請求項４ないし請求項６のいずれか１項に記載のシリンダヘッドの排気還流構造。 The exhaust gas recirculation structure for a cylinder head according to any one of claims 4 to 6 , wherein a tapered portion is formed at an end in the extending direction of the rod-shaped member . 前記ＥＧＲ通路の内周部は、円周方向の一部が前記ウォータジャケットに隣接しており、前記内筒部材は、前記山部の一部が前記ウォータジャケットに隣接する前記ＥＧＲ通路の内周部に接触していることを特徴とする請求項３ないし請求項７のいずれか１項に記載のシリンダヘッドの排気還流構造。 The inner periphery of the EGR passage has a part in the circumferential direction adjacent to the water jacket, and the inner cylinder member has an inner periphery of the EGR passage in which a part of the peak portion is adjacent to the water jacket. exhaust gas recirculation structure of a cylinder head according to any one of claims 3 to 7, characterized in that in contact with the part.
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