JP4811117B2 - Engine exhaust gas recirculation system - Google Patents

Description

The present invention attaches an intake manifold to a cylinder head of a multi-cylinder engine via a spacer, and interposes a gasket including at least a first communication hole and a second communication hole between the cylinder head and the spacer, Exhaust gas that opens an exhaust gas introduction hole for introducing exhaust gas from the exhaust port at one end portion in the cylinder row direction of the joint surface of the cylinder head and connects the exhaust gas introduction hole and the intake passage of each cylinder. A reflux passage is formed from a passage divided into a passage provided in a joint portion of the cylinder head and a passage provided in a joint surface of the spacer at a joint portion between the cylinder head and the spacer;
The exhaust gas recirculation passage communicates with the gas introduction passage extending from the exhaust gas introduction hole to the center side in the cylinder row direction, and the downstream end portion of the gas introduction passage through the first communication hole and branches in the cylinder row direction. The second gas is formed in a tournament type including a first gas passage and a second gas passage that communicates with each downstream end of the first gas passage through the second communication hole and branches in the cylinder row direction. The present invention relates to an exhaust gas recirculation device for an engine in which a plurality of downstream end portions of a passage are respectively communicated with a plurality of the intake passages.

  In an engine such as an automobile, in order to prevent the exhaust gas introduction hole from interfering with an intake passage or a fuel injection valve of each cylinder, an exhaust gas is provided at one end portion in the cylinder row direction of the joint surface of the cylinder head with respect to the spacer. An introduction hole is opened. For this reason, if a flow path for communicating the exhaust gas introduction hole and the intake passage is provided for each intake passage, the length of each flow path is different and the exhaust gas cannot be evenly distributed to each intake passage. Therefore, the exhaust gas recirculation passage is formed in a tournament type, and the length of each flow path from the exhaust gas introduction hole to each intake passage is made equal so that the exhaust gas is evenly distributed to each intake passage.

Conventionally, as a technique for forming an exhaust gas recirculation passage in a tournament type, there has been a technique in which an exhaust gas recirculation passage is formed at a lower end portion of a spacer (see Patent Document 1). However, according to this structure, there is a problem that the spacer becomes larger in the direction perpendicular to the cylinder row direction, and the mountability of the engine to the vehicle is deteriorated. This problem also occurs in the technology for forming the exhaust gas recirculation passage at the joint between the cylinder head and the spacer (the technology described in the “Technical Field” section at the beginning). That is, when the exhaust gas recirculation passage is formed in the joint, generally, each of the gas introduction passage, the first gas passage branched in the cylinder row direction from the downstream end portion of the gas introduction passage, and the first gas passage The second gas passage branching from the downstream end portion in the cylinder row direction is formed in a state of being arranged at a predetermined interval in a direction orthogonal to the cylinder row direction, and a space is required for the interval. Thus, the joint (cylinder head and spacer) becomes larger in the direction perpendicular to the cylinder row direction. As a result, the mountability of the engine to the vehicle deteriorates, and the number of members (mounting bolts as an example) for connecting the cylinder head and the spacer increases by the amount of the enlarged joint, and the cylinder head and the spacer are assembled. Workability is reduced.
Japanese Patent Laid-Open No. 2005-83312

  As a means for solving the above problem, a means for simply shortening the interval and bringing the gas introduction path and the first gas path, and the first gas path and the second gas path close to each other in the radial direction of the flow path can be considered. . However, according to this structure, the upstream portion of the first gas passage (near the branch portion of the first gas passage) due to the proximity of the gas introduction passage and the first gas passage in the radial direction of the passage. Then, due to the inertia of the exhaust gas flowing through the downstream end portion of the gas introduction path, the exhaust gas easily flows in the same direction as the flow direction of the exhaust gas in the gas introduction path. As a result, the flow rate of the exhaust gas in one of the branched first gas passage portions increases, the flow rate of the exhaust gas in the other first gas passage portion decreases, and the exhaust gas is evenly distributed to each first gas passage portion. It becomes impossible to distribute. Similarly, because the first gas passage and the second gas passage are close to each other in the radial direction of the flow path, the first gas passage and the second gas passage are first in the upstream portion (near the branch portion of the second gas passage). Due to the inertia of the exhaust gas flowing through the downstream end portion of the gas passage, the exhaust gas easily flows in the same direction as the flow direction of the exhaust gas in each downstream end portion of the first gas passage. As a result, the flow rate of the exhaust gas in one of the branched second gas passage portions increases, the flow rate of the exhaust gas in the other second gas passage portion decreases, and the exhaust gas is evenly distributed to each second gas passage portion. It becomes impossible to distribute. Therefore, the exhaust gas cannot be evenly distributed from each second gas passage portion to each intake passage.

  The present invention has been made in view of the above circumstances, and the object thereof is to improve the mountability of the engine to the vehicle and to improve the workability of assembling the cylinder head and the spacer. Another object of the present invention is to provide an exhaust gas recirculation device for an engine that can easily distribute the exhaust gas evenly to the intake passages of the cylinders.

A feature of the present invention is an exhaust gas recirculation device for an engine described in the “Technical field” at the beginning.
The gas introduction path is formed on the joint surface of the spacer so as to extend in the cylinder row direction along the lower side of the intake passage,
The first gas passage is formed on the joint surface of the cylinder head so as to face the gas introduction passage , and is adjacent to the first gas passage at the center in the cylinder row direction of the intake passages. connect the recesses extending between the intake passage is disposed,
Furthermore, each downstream end portion of the first gas passage is disposed between intake passages disposed adjacent to each other on both outer sides in the cylinder row direction in the respective intake passages,
And a portion of the boss shape of the head flange surrounding the internally threaded portion and its periphery provided in the head flange of the cylinder head along the lower side of the first gas passage, at a position overlapping with the recess in the direction perpendicular to the cylinder row partially said towards the recess is projected into the first gas passage side from the head flange as well as arranged respectively,
Forming a curved portion projecting toward the concave portion along a boss-shaped portion of a head flange surrounding the female screw portion at a downstream portion of the gas introduction path;
The first communication hole is disposed in a portion of the curved portion that overlaps the female screw portion and the concave portion in a direction orthogonal to the cylinder row,
The second gas passage, so as to form on the bonding surface of the spacer, is communicated downstream portion and communicating said first gas passage by the second communication hole,
Forming a first extension in the curved portion that extends further downstream of the gas introduction path than the first communication hole;
A second extension portion is formed in the downstream portion of the first gas passage so as to extend further downstream of the first gas passage than the second communication hole.

According to this configuration,
A gas introduction path is formed on either the spacer joining surface or the cylinder head joining surface, and the cylinder head joining surface or spacer joining is performed so that the first gas passage faces the gas introduction passage with the gasket interposed therebetween. Since it is formed in either one of the surfaces, the gas introduction path and the first gas path can be arranged at positions close to each other in a direction orthogonal to the cylinder row direction. The second gas passage is formed on one of the joint surface of the spacer and the joint surface of the cylinder head so as to face each downstream end portion of the first gas passage with the gasket interposed therebetween. The two gas passages and the downstream end portions of the first gas passage can be arranged at positions close to each other in a direction orthogonal to the cylinder row direction. Thereby, the size of the exhaust gas recirculation passage can be reduced in the direction perpendicular to the cylinder row direction, and the cylinder head and the spacer can be made compact in the direction perpendicular to the cylinder row direction.

  The exhaust gas discharged from the exhaust gas introduction hole flows into the gas introduction path. Then, the exhaust gas flows toward the center side in the cylinder row direction, flows from the downstream end portion of the gas introduction path through the first communication hole of the gasket into the first gas passage, and branches and flows in the cylinder row direction. . Further, the exhaust gas flows from the downstream end portions of the first gas passages through the second communication holes of the gasket into the second gas passages, branches and flows in the cylinder row direction, and flows downstream of the second gas passages. It flows into each intake passage from the end.

  Since the 1st extension part extended in the downstream of a gas introduction path rather than the 1st communicating hole is formed in the downstream end part of a gas introduction path, it is upstream (the 1st extension from the 1st extension part of a gas introduction path). The exhaust gas flowing toward the first extension portion on the upstream side of the communication hole and the exhaust gas flowing back into the first extension portion collide with each other in the vicinity of the first communication hole, and thereby the first extension. The inertia of the exhaust gas flowing toward the part side can be reduced or canceled by the returning exhaust gas. As a result, the exhaust gas flowing into the first gas passage from the first communication hole is the same as the flow direction of the exhaust gas in the gas introduction path upstream of the first extension (upstream of the first communication hole). The problem of facilitating flow in the direction can be avoided, and the exhaust gas can be easily distributed evenly to the first gas passage portions.

  And since the 2nd extension part extended in the downstream of the 1st gas passage rather than the 2nd communicating hole is formed in the downstream end part of the 1st gas passage, rather than the 2nd extension part of the 1st gas passage The exhaust gas flowing toward the second extension portion on the upstream side (upstream side of the second communication hole) and the exhaust gas flowing back into the second extension portion are caused to collide in the vicinity of the second communication hole. The inertia of the exhaust gas flowing toward the second extension part side can be reduced or canceled by the returning exhaust gas. As a result, the exhaust gas flowing into the second gas passage from the second communication hole has a flow direction of the exhaust gas in the first gas passage on the upstream side of the second extension (upstream side of the second communication hole). The problem of facilitating flow in the same direction can be avoided, exhaust gas can be evenly distributed to each second gas passage portion, and exhaust gas can be easily evenly distributed from each second gas passage portion to each intake passage. .

In the present invention,
When the downstream gas introduction path portion including the first extension portion is curved to form a curved portion, and the first communication hole communicates with the curved portion, the following effects can be achieved.

  That is, the exhaust gas that flows upstream from the first extension of the gas introduction path (upstream of the first communication hole) toward the first extension and the first extension of the gas introduction path The inertia of the exhaust gas flowing toward the first extension portion can be reduced or canceled by colliding the turned-up exhaust gas while curving in the vicinity of the first communication hole. Thereby, compared with the case where both exhaust gases collide front, the said inertia can be reduced or canceled gently, and it can control that the flow velocity of the exhaust gas which flows into the 1st gas passage is reduced too much. .

In the present invention,
If the bolt insertion hole for inserting the mounting bolt for fixing the spacer to the cylinder head is formed in the spacer portion radially inward from the inner peripheral portion of the curved portion, the following effect is obtained. be able to.

  As a means for preventing the bolt insertion hole from interfering with the gas introduction path, for example, the gas introduction path is formed in a straight line in the cylinder row direction on the joining surface on the spacer side or the joining surface on the cylinder head side, and the bolt insertion hole Is disposed on the outer side of the gas introduction path in a direction orthogonal to the cylinder row direction, the space for forming the gas introduction passage and the space for forming the bolt insertion hole are The cylinder heads and the spacers are enlarged in the direction perpendicular to the cylinder row direction. On the other hand, according to the above-described configuration of the present invention, the bolt insertion hole is formed in the spacer portion radially inward from the inner peripheral portion of the bending portion. The portion and the bolt insertion hole can be arranged at overlapping positions in the direction perpendicular to the cylinder row direction, and both can be brought closer in the direction perpendicular to the cylinder row direction. As a result, the cylinder head and the spacer can be made more compact in the direction orthogonal to the cylinder row direction.

According to the present invention,
The cylinder head and spacer can be made compact in the direction perpendicular to the cylinder row direction, so that the engine can be mounted on the vehicle and the assembly work of the cylinder head and spacer can be improved. The exhaust gas is easily distributed evenly from the gas introduction path to each first gas passage portion and from each first gas passage portion to each second gas passage portion, so that the exhaust gas is evenly distributed to the intake passage of each cylinder. It was possible to provide an exhaust gas recirculation device for an engine that can be easily made.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
1 to 3 show an exhaust gas recirculation device 100 for an automobile engine. This exhaust gas recirculation device 100 attaches a mounting flange 4 of an intake manifold 3 to a head flange 2 of a cylinder head 1 of a four-cylinder engine (an example of a multi-cylinder engine) via a spacer 5. A thin gasket 6 is interposed therebetween, and an exhaust gas introduction hole 7 for introducing exhaust gas from the exhaust port is opened at one end portion 1A in the cylinder row direction K of the joint surface 1M of the cylinder head 1 with respect to the spacer 5. In addition, an exhaust gas recirculation passage 9 that connects the exhaust gas introduction hole 7 and the intake passages 8A to 8D of the respective cylinders is formed at the joint portion 12 between the cylinder head 1 and the spacer 5.

  The cross-sectional shape of the exhaust gas introduction hole 7 is set to be vertically long, and the cross-sectional shapes of the intake passages 8A to 8D are set to be horizontally long. Reference numeral 10 denotes a plurality of fuel injection valve mounting holes formed in the cylinder head 1. An EGR valve V is attached to one side of the cylinder head 1 outside the exhaust gas introduction hole 7 in the cylinder row direction K. As shown by the solid line arrows and the broken line arrows in FIG. 1, the exhaust gas discharged from the combustion chamber through the exhaust port (not shown) is discharged from the exhaust gas introduction hole 7 through the EGR valve V. .

  A plurality (ten in this embodiment) of female screw portions 13 to which mounting bolts (not shown) are screwed are formed on the outer peripheral side of the head flange 2 of the cylinder head 1 in a dispersed manner. Also, a plurality of bolt insertion holes 14A, 14B, and 14C through which mounting bolts are inserted are formed on the outer peripheral side of the mounting flange 4 of the intake manifold 3, the outer peripheral side of the spacer 5, and the outer peripheral side of the gasket 6, respectively. is there. Then, a plurality of mounting bolts are respectively inserted into a plurality of bolt insertion holes 14A on the mounting flange 4 side, a plurality of bolt insertion holes 14B on the spacer 5 side, and a plurality of bolt insertion holes 14C on the gasket 6 side. The male screw portion of the bolt is screwed and fastened to each of a plurality of female screw portions 13 on the cylinder head 1 side (FIG. 1 is an exploded perspective view, and the state where the mounting bolt is screwed and fastened to the female screw portion 13 is not shown. Absent). That is, the mounting flange 4 is fixed to the head flange 2 together with the spacer 5 with the plurality of mounting bolts, so that the mounting flange 4 is mounted to the head flange 2 via the spacer 5 as described above.

  As shown in FIGS. 2, 3, and 4, the exhaust gas recirculation passage 9 is connected to the gas introduction passage 17 extending from the exhaust gas introduction hole 7 toward the center in the cylinder row direction, and the downstream end 17 </ b> K of the gas introduction passage 17. A tournament including a first gas passage 21 branched in two in the cylinder row direction K and a second gas passage 22 branched in two in the cylinder row direction K from each downstream end 21K of the first gas passage 21. It is formed into a mold. Further, the downstream end portion 17K of the gas introduction path 17 is formed between the center pair 16 in the cylinder row direction where the pair of central intake passages 8B and 8C are located on both sides, more specifically, between the pair of central intake passages 8B and 8C. Located on the lower side 24. The cylinder row direction center portion 16 is a portion including a center space 23 between a pair of intake passages 8B and 8C and both upper and lower sides thereof. You may arrange | position the downstream edge part 17K of the gas introduction path 17 in 23 between a pair of center intake passages 8B and 8C.

  Each downstream end portion 21K of the first gas passage 21 is disposed between the intake passages adjacent to each other on both outer sides of the cylinder row direction central portion 16 (between 8A and 8B, between 8C and 8D) 25, The plurality of downstream end portions 22K of the two gas passages 22 are individually communicated with the plurality of intake passages 8A to 8D. With this structure, the length of each flow path from the exhaust gas introduction hole 7 to each intake passage 8A to 8D is made equal, and the exhaust gas from the exhaust gas introduction hole 7 is evenly distributed to each intake passage 8A to 8D. .

  The exhaust gas recirculation passage 9 will be described in more detail. The gas introduction passage 17 is formed on the joint surface 5M of the spacer 5 with respect to the joint surface 1M of the cylinder head 1 so as to be positioned below the intake passages 8A to 8D. The gas introduction path 17 is communicated with the exhaust gas introduction hole 7 through the circular gas introduction path communication hole 50 formed in FIG. As shown in the schematic diagrams of FIGS. 3 to 6, one first gas passage portion of the pair of first gas passage portions 21 a and 21 b positioned with the branch portion 21 </ b> B of the first gas passage 21 interposed therebetween. The first gas passage 21 is formed on the joint surface 1M on the cylinder head 1 side so that 21a faces the gas introduction passage 17 with the gasket 6 interposed therebetween. In addition, a circular first communication hole 31 that allows the downstream end portion 17 </ b> K of the gas introduction path 17 and the branch portion 21 </ b> B of the first gas passage 21 to communicate with each other is formed in the gasket 6.

  Reference numeral 26 in FIG. 2 denotes an end of a pipe on the cylinder head 1 side that forms the intake passages 8A to 8D. The thickness of the end portion 26 of the pipe, the thickness of the lower end portion 1K of the cylinder head 1 located on the opposite side of the end portion 26 of the pipe across the first gas passage 21, and the exhaust gas introduction hole 7 are formed. The thickness of the end portion 27 of the pipe is set to be substantially the same. The first gas passage 21 also serves as a recess for reducing the weight of the cylinder head 1. Reference numeral 11 denotes a light weight recess formed between a pair of central intake passages 8B and 8C, and communicates with the first gas passage 21. Reference numeral 53 is a light weight recess and communicates with the first gas passage 21. The bottoms of the gas introduction path 17, the first gas passage 21, and the second gas passage 22 each have a circular arc shape in cross section. The first gas passage 21 is formed deeper than the gas introduction passage 17 and the second gas passage 22.

  The second gas passage 22 is formed on the joint surface 5M of the spacer 5 so as to face each downstream end portion 21K of the first gas passage 21 with the gasket 6 interposed therebetween. Each of the gaskets in contact with each downstream end 21K of the first gas passage 21 is formed with a circular second communication hole 32 that allows the downstream end 21K of the first gas passage 21 to communicate with the branching portion 22B of the second gas passage 22. Each of the portions 28 is formed.

  The second gas passage 22 includes four second gas passage portions 22a communicating with the four intake passages 8A to 8D, respectively. The four second gas passage portions 22a are in a posture along the cylinder row direction K. Two second communication holes 32 are provided for one downstream end portion 21K of the first gas passage 21, for a total of four, and one second communication hole 32 is provided for each second gas passage portion 22a. Is communicated with the downstream end 21K of the first gas passage 21. The four second gas passage portions 22a are separated from each other, and the adjacent second gas passage portions 22a are not in communication with each other on the downstream side of the second communication hole 32. Since FIG. 3 is a schematic diagram, FIG. 3 is simplified by a structure in which one second communication hole 32 is provided for one downstream end 21K of the first gas passage 21, a total of two. It is.

  A first extension 41 is formed at the downstream end 17K of the gas introduction path 17 so as to extend further downstream of the gas introduction path 17 than the first communication hole 31, and a downstream gas introduction path including the first extension 41 is formed. The portion is curved upward to form the first bending portion 51 (see FIG. 2). The first bending portion 51 is located on the lower side 24 between the pair of intake passages 8 </ b> B and 8 </ b> C in the center in the cylinder row direction K, and the first communication hole 31 communicates with the first bending portion 51. The lower gas introduction path portion between the intake passage 8D closest to the exhaust gas introduction hole 7 and the intake passage 8C adjacent to the intake passage 8D is also curved upward to form the second curved portion 52. The arrows in each figure indicate the flow direction of the exhaust gas. As shown in FIG. 3, exhaust gas that flows upstream from the first extension 41 of the gas introduction path 17 toward the first extension 41 and exhaust gas that flows into the first extension 41 and turns back. Collide in the vicinity of the first communication hole 31, and the inertia of the exhaust gas flowing toward the first extension 41 side is reduced or canceled by the returning exhaust gas.

  One bolt insertion hole 14B (a bolt insertion hole through which a mounting bolt for fixing the spacer 5 to the cylinder head 1) is inserted among the plurality (10 in this embodiment) of the bolt insertion holes 14B. The spacer portion 33 is formed on the radially inner side of the inner peripheral portion 51N of the curved portion 51. Similarly, another bolt insertion hole 14B among the plurality of bolt insertion holes 14B is formed in the spacer portion 34 on the radially inner side with respect to the inner peripheral portion 52N of the second bending portion 52. . As shown in FIGS. 2 and 3, a second extension 42 is formed at the downstream end 21 </ b> K of the first gas passage 21, which extends further downstream of the first gas passage 21 than the second communication hole 32. With this structure, the exhaust gas that flows upstream from the second extension 42 of the first gas passage 21 toward the second extension 42 and the exhaust gas that flows back into the second extension 42 are returned. The inertia of the exhaust gas that collides near the second communication hole 32 and flows toward the second extension portion 42 side is reduced or canceled by the returning exhaust gas.

  The inventor has the exhaust gas recirculation device 100 of the present invention having the above structure and the exhaust gas recirculation device that does not include the first extension portion 41 and the second extension portion 42 (the first extension portion 41 and the second extension portion 42). The other structure was the same as that of the exhaust gas recirculation device of the present invention having the above-described structure, and an experiment for comparing the effect with the “exhaust gas recirculation device of the comparative example” was conducted. FIG. 7 shows the experimental results. In FIG. 7, # 1 is the first cylinder, # 2 is the second cylinder, # 3 is the third cylinder, # 4 is the fourth cylinder, and the intake passage 8A corresponds to the first cylinder # 1, The passage 8B corresponds to the second cylinder # 2, the intake passage 8C corresponds to the third cylinder # 3, and the intake passage 8D corresponds to the fourth cylinder # 4. The circles indicate the experimental results of the exhaust gas recirculation device of the present invention, and the Δ marks indicate the experimental results of the exhaust gas recirculation device of the comparative example. 0 on the vertical axis indicates that the distribution amount of the exhaust gas is uniform.

  As shown in FIG. 7, in the exhaust gas recirculation device of the comparative example, the flow rate of the exhaust gas in one branched first gas passage portion 21b (see FIG. 3) increases, and the intake passage 8A of the first cylinder # 1 is increased. And the distribution amount of the exhaust gas to the intake passage 8B of the second cylinder # 2 is increased. Conversely, the amount of exhaust gas distributed to the intake passage 8C of the third cylinder # 3 and the intake passage 8D of the fourth cylinder # 4 is reduced. On the other hand, in the exhaust gas recirculation device 100 of the present invention, the distribution amount of the exhaust gas to the intake passage 8A of the first cylinder # 1 and the intake passage 8B of the second cylinder # 2 is increased for the reasons described above. Further, the distribution amount of the exhaust gas to the intake passage 8C of the third cylinder # 3 and the intake passage 8D of the fourth cylinder # 4 can be suppressed.

[Another embodiment]
(1) Although not shown, the gas introduction path 17 is formed on the joint surface 1M of the cylinder head 1 so that the gas introduction path 1 communicates with the exhaust gas introduction hole 7, and the first gas passage portion 21a The first gas passage 21 is formed on the joint surface 5M of the spacer 5 so as to face the gas introduction passage 17 with the second gas passage 22 interposed between the gaskets 6 and the downstream ends of the first gas passage 21. The present invention can also be applied to a structure formed on the joint surface 1M of the cylinder head 1 so as to face the portion 21.
(2) As shown in FIG. 8, the first extension 41 of the downstream end 17 </ b> K of the gas introduction path 17 may be formed in a rectangular shape wider than the upstream gas introduction path.

Disassembled perspective view of exhaust gas recirculation device Diagram showing cylinder head joint surface, gasket joint surface, and spacer joint surface Schematic diagram of exhaust gas recirculation system AA sectional view of FIG. Enlarged schematic diagram of the main part of the exhaust gas recirculation system BB sectional view of FIG. The figure which shows the experimental result of the exhaust-gas recirculation apparatus of this invention, and the exhaust-gas recirculation apparatus of a comparative example Schematic diagram showing another embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder head 1A One end part of the cylinder head joint surface in the cylinder row direction 1M Cylinder head joint surface 3 Intake manifold 5 Spacer 5M Spacer joint surface 6 Gasket K Cylinder row direction 7 Exhaust gas introduction holes 8A, 8B, 8C, 8D Intake passage 9 Exhaust gas recirculation passage 12 Joint portion 14B Bolt insertion hole 16 through which mounting bolt is inserted 16 Cylinder row direction central portion 17 Gas introduction passage 17K Downstream end portion 21 of gas introduction passage First gas passages 21a, 21b First gas passage portions 21B Branch portion 21K of the first gas passage 21K Downstream end portion 22 of the first gas passage Second gas passage 22B Branch portion 22K of the second gas passage Downstream end portion 25 of the second gas passage 25 Adjacent to each other on both sides of the central portion in the cylinder row direction Between the intake air passages 28 Gasket portion 31 First communication hole 32 Second communication hole 33 Spacer portion 41 First extension portion 42 Second extension For 50 gas introduction path communicating hole 51 bend (gas introducing path portion)
51N Inner peripheral portion of curved portion 100 Exhaust gas recirculation device for engine

Claims (1)

An intake manifold is attached to a cylinder head of a multi-cylinder engine via a spacer, and a gasket having at least a first communication hole and a second communication hole is interposed between the cylinder head and the spacer, and the cylinder head is joined to the spacer. An exhaust gas recirculation passage that opens an exhaust gas introduction hole for introducing exhaust gas from an exhaust port and communicates the exhaust gas introduction hole and the intake passage of each cylinder at one end portion in the cylinder row direction of the surface, Formed from a passage divided into a passage provided in the joint portion of the cylinder head and a passage provided in the joint surface of the spacer at the joint portion between the cylinder head and the spacer;
The exhaust gas recirculation passage communicates with the gas introduction passage extending from the exhaust gas introduction hole to the center side in the cylinder row direction, and the downstream end portion of the gas introduction passage through the first communication hole and branches in the cylinder row direction. The second gas is formed in a tournament type including a first gas passage and a second gas passage that communicates with each downstream end of the first gas passage through the second communication hole and branches in the cylinder row direction. An exhaust gas recirculation device for an engine in which a plurality of downstream end portions of a passage are individually communicated with a plurality of the intake passages,
The gas introduction path is formed on the joint surface of the spacer so as to extend in the cylinder row direction along the lower side of the intake passage,
The first gas passage is formed on the joint surface of the cylinder head so as to face the gas introduction passage , and is adjacent to the first gas passage at the center in the cylinder row direction of the intake passages. connect the recesses extending between the intake passage is disposed,
Furthermore, each downstream end portion of the first gas passage is disposed between intake passages disposed adjacent to each other on both outer sides in the cylinder row direction in the respective intake passages,
And a portion of the boss shape of the head flange surrounding the internally threaded portion and its periphery provided in the head flange of the cylinder head along the lower side of the first gas passage, at a position overlapping with the recess in the direction perpendicular to the cylinder row partially said towards the recess is projected into the first gas passage side from the head flange as well as arranged respectively,
Forming a curved portion projecting toward the concave portion along a boss-shaped portion of a head flange surrounding the female screw portion at a downstream portion of the gas introduction path;
The first communication hole is disposed in a portion of the curved portion that overlaps the female screw portion and the concave portion in a direction orthogonal to the cylinder row,
The second gas passage, so as to form on the bonding surface of the spacer, is communicated downstream portion and communicating said first gas passage by the second communication hole,
Forming a first extension in the curved portion that extends further downstream of the gas introduction path than the first communication hole;
Exhaust gas recirculation device for an engine is formed a second extension extending downstream of said first gas passageway than said second communicating hole to the downstream portion of the first gas passage.

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