Intake Manifold

Abstract

To provide an intake manifold capable of suppressing the generation of deposit due to the occurrence of a blowing-back phenomenon.SOLUTION: An intake manifold 10 has a surge tank 21, an air introducing portion 22, and a gas introducing portion 25. The air introducing portion 22 is connected to the surge tank 21 so as to have an inside that forms a cylindrical shape configuring a main passage 22M and introduce air to the inside of the surge tank 21 through the main passage 22M. The gas introducing portion 25 forms a structure in which EGR gas passes through the inside, and introduces the EGR gas into the surge tank 21. The gas introducing portion 25 has a sub passage 43S extending along the main passage 22M. The sub passage 43S extends so that a lower end 431 that is an end portion on the surge tank 21 side in the extending direction merges with the main passage 22M, and a part other than the lower end 431 is blocked to the main passage 22M.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to an intake manifold of an internal combustion engine.

Background Art

[0002] An internal combustion engine is provided with an intake manifold that forms part of the intake system (see Patent Document 1). This intake manifold has a surge tank, an air introduction part that communicates the inside and outside of the surge tank, and a plurality of branch pipes with one end connected to the surge tank. The air introduction part is connected to a portion on the upstream side in the intake flow direction in the intake passage of the internal combustion engine. The plurality of branch pipes are connected to each intake port of the internal combustion engine. With such an intake manifold, the air inhaled into the intake passage is distributed to each cylinder of the internal combustion engine.

[0003] Patent Document 1 proposes integrally providing an EGR part for introducing a part of the exhaust of an internal combustion engine (so-called EGR gas) into the intake manifold. The EGR part constitutes a part of an EGR passage for recirculating a part of the exhaust in the exhaust passage of the internal combustion engine to the intake passage. The EGR part is connected to a portion on the upstream side in the EGR gas flow direction in the EGR passage.

[0004] Conventionally, an intake manifold having a structure in which the EGR part is integrally provided in the air introduction part in a manner where one end of the EGR part is connected and communicated with the air introduction part is known.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In intake manifolds, there is a risk of a phenomenon known as backflow, where air that has been introduced into the manifold flows back into the intake passage upstream of the intake airflow direction. In intake manifolds with an EGR passage connected to the air intake, if backflow occurs, EGR gas will flow back into the upstream intake passage along with the intake air, albeit temporarily. This backflow can cause deposit formation in the upstream intake passage.

[0007] Furthermore, the above problem is not limited to intake manifolds with an integrated EGR section, but also occurs in intake manifolds with an integrated blow-by gas section for introducing combustion gases (so-called blow-by gases) that have leaked from the combustion chamber of the internal combustion engine into the crankcase. The above problem also occurs in intake manifolds with an integrated purge gas section for introducing evaporated fuel (so-called purge gases) from the fuel tank of the internal combustion engine. [Means for solving the problem]

[0008] An intake manifold for solving the above problems comprises a surge tank, an air introduction section connected to the surge tank in such a manner that it has a cylindrical shape with its interior forming a main passage and introduces air into the surge tank through the main passage, and a gas introduction section with one end connected to the peripheral wall of the air introduction section and introducing an introduction gas other than air into the main passage, wherein the gas introduction section has a sub-passage extending along the main passage inside, and the end of the sub-passage on the surge tank side in the direction of extension of the sub-passage merges with the main passage, and the portion other than the end is closed off from the main passage.

[0009] According to the above configuration, the introduced gas in the secondary passage flows along the airflow in the main passage toward the junction with the main passage, specifically toward the surge tank. Therefore, the introduced gas from the secondary passage to the main passage can be introduced in such a manner that the airflow in the main passage and the introduced gas flow in the secondary passage, both of which are toward the surge tank, are merged at the connecting point between the main passage and the secondary passage. This makes it easier for the introduced gas introduced into the main passage to flow toward the surge tank (downstream in the direction of airflow). As a result, the generation of deposits caused by blowback can be suppressed. [Brief explanation of the drawing]

[0010] [Figure 1] This is a front view of an intake manifold according to one embodiment. [Figure 2] This is a rear view of the intake manifold. [Figure 3] This is a side view of the intake manifold. [Figure 4] This is a disassembled side view of the intake manifold. [Figure 5] This is a side cross-sectional view of the intake manifold. [Figure 6] This is a front view of the second and third components of the intake manifold. [Figure 7] This is a rear view of the first component of the intake manifold. [Figure 8] This is a cross-sectional view of the gas inlet and its surrounding area along line 8-8 in Figure 2. [Figure 9] This is a cross-sectional view of the gas inlet and its surrounding area along the line 9-9 in Figure 8. [Figure 10] This is a cross-sectional view of the air intake section along the line 10-10 in Figure 9. [Modes for carrying out the invention]

[0011] Hereinafter, one embodiment of the intake manifold will be described with reference to Figures 1 to 10. In this embodiment, the vertical direction in Figure 1 will be considered the vertical direction of the intake manifold 10, the left-right direction in Figure 1 will be considered the left-right direction of the intake manifold 10, and the direction perpendicular to the plane of the paper in Figure 1 will be considered the front-to-back direction of the intake manifold 10.

[0012] As shown in Figures 1 to 5, the intake manifold 10 is composed of three divided parts (first member 11, second member 12, and third member 13) separated in the front-to-back direction. The three divided parts are arranged from the front in the order of first member 11, second member 12, and third member 13. These first member 11, second member 12, and third member 13 are all made of a hard synthetic resin material. The intake manifold 10 has a structure in which the first member 11, second member 12, and third member 13 are stacked on top of each other (as shown in Figure 3), and these members 11 to 13 are fixed to each other by vibration welding.

[0013] The intake manifold 10 includes a surge tank 21, an air inlet 22, a plurality (three in this embodiment) of branch pipes 23, a mounting flange 24, and a gas inlet 25.

[0014] <Surge Tank> The surge tank 21 forms the central part of the intake manifold 10. The surge tank 21 functions as a volumetric section for temporarily storing air.

[0015] <Air intake section> As shown in Figures 2, 3, 6, and 7, the air inlet 22 is cylindrical in shape, with one end connected to the surge tank 21. The inside of the air inlet 22 forms a main passage 22M that connects the inside of the surge tank 21 to the outside of the intake manifold 10. In the intake manifold 10, air is introduced into the surge tank 21 through the main passage 22M of the air inlet 22.

[0016] The air introduction part 22 has an inlet part 31 and a curved part 32. The inlet part 31 constitutes the upstream part of the intake air flow direction in the air introduction part 22. The upstream end of the inlet part 31 in the intake air flow direction is a fixing part 221 to which the upstream part of the intake air flow direction in the intake passage of the internal combustion engine (specifically, the throttle mechanism) is fixed. The inlet part 31 extends in a substantially straight line forward and obliquely downward starting from the fixing part 221.

[0017] The curved part 32 constitutes the downstream part of the intake air flow direction in the air introduction part 22. The curved part 32 extends in a manner connecting the downstream end of the inlet part 31 in the intake air flow direction and the left side part of the surge tank 21. Specifically, the curved part 32 starts from the downstream end of the inlet part 31 in the intake air flow direction and extends while curving to the right. And the downstream end of the curved part 32 in the intake air flow direction (specifically, the right side part of the curved part 32) communicates with the left side part in the surge tank 21.

[0018] <State detection part> As shown in FIGS. 2, FIGS. 3 and FIG. 6, a state detection part 26 is provided in the air introduction part 22. The state detection part 26 is cylindrical and extends in a manner protruding rearward from the rear wall part (hereinafter, rear wall 22R) on the rear side of the air introduction part 22. The front end of the state detection part 26 opens on the inner surface of the rear wall 22R of the air introduction part 22. A pressure sensor 27 is attached to the rear end of the state detection part 26. The rear end of the state detection part 26 is closed by the pressure sensor 27. By this pressure sensor 27, the internal pressure of the state detection part 26 is detected as the internal pressure of the intake manifold 10 (specifically, the main passage 22M).

[0019] <Branch pipe> As shown in Figures 2, 5, and 6, the multiple branch pipes 23 are individually connected to the lower part of the surge tank 21. The multiple branch pipes 23 are distribution passages that distribute the air inside the surge tank 21. Each branch pipe 23 extends from the lower rear to the upper front of the intake manifold 10, curving in a convex shape toward the rear. The base end 231 portion of each branch pipe 23 is formed integrally with the rear wall (hereinafter referred to as the rear wall 21R) and the upper wall of the surge tank 21 without any gaps. The base end 231 of each branch pipe 23 opens on the inner surface of the rear wall 21R of the surge tank 21. The tip 232 of each branch pipe 23 opens toward the outside.

[0020] <Mounting flange> As shown in Figures 1, 3, and 5, the mounting flange 24 is integrally provided on the tip 232 of each branch pipe 23. The mounting flange 24 extends in the direction in which the tips 232 of the two branch pipes 23 are aligned. The mounting flange 24 is plate-shaped and extends in the vertical and horizontal directions. By fixing this mounting flange 24 to the outer wall of the internal combustion engine (not shown), each branch pipe 23 of the intake manifold 10 is connected to each intake port of the internal combustion engine.

[0021] As shown in Figures 2, 6, and 7, the intake manifold 10 has through holes 28 and 29 used for fixing the mounting flange 24. Specifically, as shown in Figure 7, the second member 12 has a boss portion 281 that protrudes rearward from its inner surface and a through hole 28 that extends in the front-rear direction, passing through the boss portion 281. Also, as shown in Figure 6, the third member 13 has a boss portion 291 that protrudes forward from its inner surface and a through hole 29 that extends in the front-rear direction, passing through the boss portion 291. As shown in Figures 2, 6, and 7, the through hole 28 of the second member 12 and the through hole 29 of the third member 13 are connected in such a way that they form a single through hole extending in the front-rear direction.

[0022] As shown in Figures 1 and 3, the intake manifold 10 is provided with reinforcing ribs 50. The reinforcing ribs 50 protrude from the outer wall of the mounting flange 24, the outer wall of the branch pipe 23, and the outer wall of the surge tank 21. The reinforcing ribs 50 are plate-shaped and extend in the front-rear and up-down directions. The reinforcing ribs 50 extend from the mounting flange 24 through the tip of the branch pipe 23 to the surge tank 21. Reinforcing ribs 50 are provided separately for each of the three branch pipes 23.

[0023] <Gas inlet section> As shown in Figures 1 to 3, the gas inlet section 25 is basically cylindrical in shape, extending in the left-right direction. As shown in Figures 6 to 9, one end of the gas inlet section 25 (specifically, the right end) is connected to the peripheral wall of the air inlet section 22. The gas inlet section 25 has a structure through which a portion of the exhaust gas from the internal combustion engine (so-called EGR gas) passes. The gas inlet section 25 is for introducing EGR gas into the airflow portion inside the intake manifold 10 (in this embodiment, the main passage 22M of the air inlet section 22). In this embodiment, the EGR gas corresponds to the introduction gas other than air.

[0024] As shown in Figures 1, 8, and 9, the gas introduction section 25 has an upstream section 41, a downstream section 43, an opening 44, and a flow path resistance member 45. <Upstream> The upstream section 41 constitutes the upstream side (specifically, the left side) of the gas inlet section 25 in the direction of EGR gas flow. The upstream section 41 extends linearly in the left-right direction. The left end of the upstream section 41, which is the upstream end in the direction of EGR gas flow, is a fixing section 251 to which the upstream portion of the EGR passage in the direction of EGR gas flow (specifically, the EGR pipe) is fixed. The right end of the upstream section 41, which is the downstream end in the direction of EGR gas flow, is connected to the downstream section 43.

[0025] <Downstream> The downstream section 43 constitutes the portion of the gas inlet section 25 that is downstream in the direction of EGR gas flow (specifically, the right side). The right end of the downstream section 43, which is the downstream end in the direction of EGR gas flow, is connected to the peripheral wall of the air inlet section 22, more specifically, to the outer side in the curvature direction of the curved section 32. The downstream section 43 has a flared shape in which the passage cross-sectional area increases as it moves away from the upstream section 41. Specifically, the distance between opposing walls in the vertical direction of the peripheral wall of the downstream section 43 gradually increases as it moves away from the upstream section 41, that is, as it approaches the air inlet section 22. In addition, the distance between opposing walls in the front-rear direction of the peripheral wall of the downstream section 43 remains approximately constant.

[0026] <Sub-passage> In this embodiment, the interior of the downstream section 43 constitutes the sub-passage 43S. As shown in Figure 9, the sub-passage 43S has a shape that extends along the main passage 22M of the air intake section 22. Specifically, the sub-passage 43S has a shape that extends in the vertical and longitudinal directions.

[0027] The upstream section 41 is connected to the sub-passage 43S in such a manner that it discharges EGR gas in a direction perpendicular to the extension direction LS (LS is not shown in the figure) of the sub-passage 43S (in this embodiment, the left-right direction). The upstream section 41 is also connected to the middle portion of the sub-passage 43S in the extension direction LS. Specifically, the upstream section 41 is connected to the middle portion of the sub-passage 43S in the vertical direction. As a result, the upper part of the sub-passage 43S extends above the communication portion between the sub-passage 43S and the upstream section 41. In this embodiment, some of the EGR gas flowing into the sub-passage 43S from the communication portion flows upward above the communication portion and then returns downward. Therefore, the velocity of the EGR gas in the sub-passage 43S is kept lower compared to a configuration where the upstream section 41 is connected to the upper end of the sub-passage 43S. Consequently, the velocity of the EGR gas flowing from the sub-passage 43S into the main passage 22M is kept low.

[0028] As shown in Figures 8 to 10, the opening 44 is provided in the peripheral wall of the air inlet 22. The opening 44 is a through hole that penetrates the peripheral wall of the air inlet 22. In this embodiment, the main passage 22M of the air inlet 22 and the secondary passage 43S of the gas inlet 25 are connected through this opening 44. The opening 44 is provided at the lower end 431 of the secondary passage 43S, which is the end on the surge tank 21 side in the extension direction LS of the secondary passage 43S. As a result, the secondary passage 43S extends in such a manner that its lower end 431 and the main passage 22M merge. In this embodiment, the portion of the secondary passage 43S other than the lower end 431 is closed off from the main passage 22M.

[0029] The opening 44 is provided on the outer portion of the curved portion 32 in the curvature direction of the peripheral wall of the air introduction section 22. The opening 44 is located on the outer side of the curved portion 32 in the curvature direction and opens on the inner surface of the curved portion 32. In this embodiment, the sub-passage 43S of the gas introduction section 25 is connected to the main passage 22M of the air introduction section 22 in the outer portion of the curved portion 32 in the curvature direction.

[0030] As shown in Figures 9 and 10, the opening shape of the opening 44, which is the confluence portion where the main passage 22M and the sub-passage 43S merge, is an elongated hole in the extension direction LM (LM is not shown) of the air introduction section 22 (specifically, the main passage 22M). More specifically, the opening shape of the opening 44 is tapered, with the portion PB closer to the surge tank 21 being narrower than the portion PU further away from the surge tank 21 in the extension direction LM of the main passage 22M.

[0031] As shown in Figures 6 and 7, the opening 44 is located closer to the surge tank 21 in the extension direction LM than the opening of the state detection unit 26 on the inner surface of the air intake unit 22, i.e., it is located downstream in the intake air flow direction. In other words, the state detection unit 26 is located further away from the surge tank 21 in the extension direction LM than the opening 44, i.e., upstream in the intake air flow direction.

[0032] The gas introduction section 25 has a structure in which the first member 11 and the second member 12 are integrally joined. Specifically, as shown in Figures 3 and 4, the intake manifold 10 has a first member 11 and a second member 12 that are divided along the extension direction LG (LG is not shown, in this embodiment the left-right direction) of the gas introduction section 25. The first member 11 includes the entire upstream section 41 of the gas introduction section 25 and the front part of the downstream section 43. The second member 12 includes the rear part of the downstream section 43 of the gas introduction section 25. In this embodiment, the first member 11 and the second member 12 are joined to each other in a joined state. In this way, the passage-shaped gas introduction section 25 is partitioned inside the intake manifold 10. In this embodiment, the first member 11 corresponds to the first divided body, and the second member 12 corresponds to the second divided body.

[0033] As shown in Figures 7 to 10, a blocking wall portion 111 is provided protruding from the inner surface of the first member 11. The blocking wall portion 111 is provided at a position on the inner surface of the first member 11 corresponding to the communication portion between the gas introduction portion 25 and the air introduction portion 22. The blocking wall portion 111 has a shape that blocks a part of the gas introduction portion 25 at the communication portion. The blocking wall portion 111 constitutes a part of the wall portion of the gas introduction portion 25 and also constitutes a part of the peripheral wall of the air introduction portion 22. The shape of the blocking wall portion 111 is such that the main passage 22M inside the air introduction portion 22 extends with substantially the same cross-sectional shape and substantially the same cross-sectional area. As a result, although a part of the peripheral wall of the air introduction portion 22 is composed of the blocking wall portion 111, air flows smoothly inside the air introduction portion 22 (more specifically, the main passage 22M).

[0034] As shown in Figures 8 and 10, the portion of the gas introduction section 25 that is blocked by the blocking wall 111 has a structure in which the tip of the blocking wall 111 and the inner surface of the second member 12 are positioned opposite each other. Therefore, in this portion, a gap W is formed between the tip of the blocking wall 111 and the inner surface of the second member 12.

[0035] <Flow resistance component> As shown in Figures 6, 7, and 9, a flow resistance member 45 is provided inside the downstream portion 43 of the gas introduction section 25.

[0036] Figure 8 shows the internal structure of the gas inlet 25 when viewed from the extension direction LG (specifically, the left side) of the gas inlet 25. As shown in Figure 8, in this embodiment, the upper part of the gas inlet 25 where the gap W is formed is defined as the first part 25U when viewed from the extension direction LG of the gas inlet 25. The lower part of the gas inlet 25 where the gap W is not formed is defined as the second part 25B when viewed from the extension direction LG of the gas inlet 25.

[0037] As shown in Figures 6, 7, and 9, the flow resistance member 45 is shaped to make the flow resistance of the EGR gas within the first portion 25U greater than the flow resistance of the EGR gas within the second portion 25B. The flow resistance member 45 is composed of a first projection 112 provided on the first member 11 and a second projection 121 provided on the second member 12.

[0038] <First Protrusion> As shown in Figures 7 to 9, the portion of the first member 11 that constitutes the downstream portion 43 of the gas introduction section 25 has a roughly C-shape in cross-section that opens towards the rear (see Figure 8) and extends in the left-right direction. The first projection 112 is provided protruding from the inner surface of the first member 11. The first projection 112 is roughly flat and extends in the vertical and front-rear directions. The front and upper ends of the first projection 112 are integral with the inner surface of the first member 11. The lower end of the first projection 112 is spaced apart from the inner surface of the first member 11.

[0039] <Second Pierce> As shown in Figures 6, 8, and 9, the portion of the second member 12 that constitutes the downstream portion 43 has a roughly C-shaped cross-section that opens forward (see Figure 8) and extends in the left-right direction. The second projection 121 is provided protruding from the inner surface of the second member 12. The second projection 121 is a flat plate shape that extends in the vertical and front-rear directions. The rear end of the second projection 121 is integral with the inner surface of the second member 12. The upper and lower ends of the second projection 121 are spaced apart from the inner surface of the second member 12.

[0040] As shown in Figures 6, 7, and 9, the first projection 112 and the second projection 121 are arranged alternately in the extending direction LG of the gas introduction section 25. In this embodiment, the first projection 112, the second projection 121, and the closing wall section 111 are arranged in the order of the first projection 112, the second projection 121, and the closing wall section 111 from the upstream side (left side in Figure 9) in the EGR gas flow direction. The first projection 112 and the second projection 121 extend parallel to each other. In this embodiment, the first projection 112 and the second projection 121 are provided in such a manner that the rear portion of the first projection 112 and the front portion of the second projection 121 overlap when viewed from the extending direction LG of the gas introduction section 25 (see Figures 3 and 4).

[0041] The flow resistance member 45 has a so-called labyrinth structure in which the first projection 112 and the second projection 121 form a maze-like flow path. The maze-like flow path is composed of (flow path A) to (flow path E) as described below. (flow path A) A flow path consisting of the gap between the rear end of the first projection 112 and the inner surface of the second member 12. (flow path B) A flow path consisting of the gap between the right surface of the first projection 112 and the left surface of the second projection 121. (flow path C) A flow path consisting of the gap between the front end of the second projection 121 and the inner surface of the first member 11. (flow path D) A flow path consisting of the gap between the upper end of the second projection 121 and the inner surface of the first member 11. (flow path E) A flow path consisting of the gap between the right surface of the second projection 121 and the left surface of the closing wall portion 111.

[0042] In this embodiment, the flow resistance member 45 (specifically, the first projection 112 and the second projection 121) is provided on the first portion 25U which constitutes the upper part of the gas introduction section 25, while it is not provided on the second portion 25B which constitutes the lower part of the gas introduction section 25. That is, the flow resistance member 45 is provided only on the first portion 25U of the two portions 25U and 25B. In this embodiment, the flow resistance member 45 is also provided at a position on the side of the closing wall portion 111 rather than the center of the extension direction LG in the gas introduction section 25 (indicated as "PA" in Figure 9).

[0043] As shown in Figures 9 and 10, in the intake manifold 10 of this embodiment, regulated air (indicated by arrow GA in the figures) is introduced into the surge tank 21 via the air inlet 22 through the operation of the throttle mechanism. EGR gas (indicated by arrow GE in the figures) is also introduced into the surge tank 21 via the gas inlet 25. The air and EGR gas introduced into the surge tank 21 are then distributed and supplied to each intake port of the internal combustion engine via each branch pipe 23 (Figure 5).

[0044] <Effects and Effects> The following describes the effects and benefits of the intake manifold 10 of this embodiment. (1) The gas introduction section 25 has a secondary passage 43S that extends along the main passage 22M inside. The secondary passage 43S extends such that its lower end 431, which is the end on the surge tank 21 side in the extension direction LS, merges with the main passage 22M, and the portion other than the lower end 431 is closed off from the main passage 22M.

[0045] According to this embodiment, within the sub-passage 43S, the EGR gas flows along the airflow in the main passage 22M toward the opening 44, which is the junction with the main passage 22M, specifically toward the surge tank 21. Therefore, the airflow in the main passage 22M and the EGR gas flow in the sub-passage 43S, both of which are toward the surge tank 21, can be merged at the connecting portion of the main passage 22M and the sub-passage 43S. By introducing the EGR gas from the sub-passage 43S to the main passage 22M in this way, the EGR gas introduced into the main passage 22M can be made to flow more easily toward the surge tank 21, i.e., toward the downstream side in the direction of airflow. As a result, backflow of the EGR gas introduced into the main passage 22M toward the upstream side in the direction of airflow can be suppressed, and thus the generation of deposits caused by the blowback phenomenon can be suppressed.

[0046] (2) The upstream portion 41 of the gas introduction portion 25 is connected to the downstream portion 43 (more specifically, its sub-passage 43S) in such a manner that the EGR gas is discharged in a direction perpendicular to the extension direction LS of the sub-passage 43S (to the right in this embodiment).

[0047] In this embodiment, as is clear from Figures 3 and 9, the EGR gas flowing from the upstream section 41 into the sub-passage 43S of the downstream section 43 collides with the inner surface of the sub-passage 43S, specifically the left side of the first protrusion 112 and the second protrusion 121. This causes turbulence in the flow of the EGR gas within the sub-passage 43S. The EGR gas in this turbulent state can then be introduced into the main passage 22M. This allows for a suitable mixing of the air in the main passage 22M with the EGR gas introduced into the main passage 22M from the sub-passage 43S.

[0048] (3) The air introduction section 22 has a curved section 32 that curves in the extension direction LM. The sub-passage 43S of the gas introduction section 25 is in communication with the main passage 22M inside the curved section 32 at the outer portion of the curved section 32 in the direction of curvature. Here, the density of the gas flowing inside the curved section 32 tends to be higher in the outer portion in the direction of curvature. According to this embodiment, the introduction of EGR gas from the sub-passage 43S to the main passage 22M can be carried out in the outer portion in the direction of curvature, that is, in the portion where the gas density is relatively high. Therefore, the EGR gas introduced from the sub-passage 43S to the main passage 22M can be suitably pushed downstream in the direction of airflow by utilizing the relatively high-density airflow. This effectively prevents the EGR gas introduced into the main passage 22M from flowing back upstream in the direction of airflow.

[0049] (4) The opening 44, which is the confluence of the main passage 22M and the sub-passage 43S, has an elongated shape in the extension direction LM. According to this embodiment, the introduction of EGR gas from the sub-passage 43S to the main passage 22M through this opening 44 can be carried out over a wide area in the extension direction LM of the main passage 22M, in other words, in the airflow direction. As a result, compared to the case in which EGR gas is introduced intensively in a narrow area in the extension direction LM, the air and EGR gas are mixed using the wide space within the main passage 22M, so that the air and EGR gas can be mixed well.

[0050] (5) The opening shape of the opening 44 is tapered, with the portion PB closer to the surge tank 21 being narrower than the portion PU further away from the surge tank 21 in the extending direction LM of the air introduction section 22. According to this embodiment, more EGR gas can be introduced into the upstream portion of the opening 44 in the airflow direction (the portion PU) than into the downstream portion in the airflow direction (the portion PB). This makes it less likely for the EGR gas introduced from portion PB of the opening 44 to interfere with the EGR gas introduced from portion PU of the opening 44 within the main passage 22M.

[0051] (6) A state detection unit 26 is provided at a position upstream of the opening 44 in the air intake unit 22 in the direction of airflow. According to this embodiment, the state detection unit 26 can be provided at a position upstream of the opening 44 in the direction of airflow, that is, at a position where it is difficult for the EGR gas introduced through the opening 44 to come into contact with it. As a result, the state detection unit 26 can be made less susceptible to the effects of the EGR gas, and thus a decrease in the detection performance and durability of the pressure sensor 27 provided in the state detection unit 26 can be suppressed.

[0052] <Example of changes> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0053] The state detection unit 26 and the pressure sensor 27 can be omitted. • The reinforcing rib 50 can be omitted. Multiple first protrusions 112 can be provided on the inner surface of the first member 11. Similarly, multiple second protrusions 121 can be provided on the inner surface of the second member 12. In this case, the first protrusions 112 and the second protrusions 121 should be arranged alternately in the extending direction LM of the gas introduction section 25.

[0054] - Instead of providing the flow resistance member 45 at a position closer to the closing wall portion 111 than the central PA in the extending direction LG of the gas introduction section 25, it may be provided at a position corresponding to the central PA in the extending direction LG. Alternatively, instead of providing the flow resistance member 45 at a position closer to the closing wall portion 111 than the central PA in the extending direction LG of the gas introduction section 25, it may be provided at a position further away from the closing wall portion 111 than the central PA in the extending direction LG.

[0055] In addition to providing the flow path resistance member 45 at a position on the side of the closing wall portion 111 that is closer to the central PA in the extending direction LG of the gas introduction portion 25, it can also be provided at a position corresponding to the central PA, or at a position that is further away from the closing wall portion 111 than the central PA.

[0056] In addition to providing the flow resistance member 45 in the first portion 25U of the gas introduction section 25, it may also be provided in the second portion 25B of the gas introduction section 25. In this case, the shape of each part of the flow resistance member 45 should be determined such that the flow resistance of the first portion 25U is greater than the flow resistance of the second portion 25B.

[0057] • The flow resistance member 45 can be anything other than a labyrinth structure. For example, the flow resistance member 45 can be a perforated plate, a number of cylindrical bodies, or a sponge-like material.

[0058] • The flow resistance member 45 can be omitted. The opening shape of the opening 44 may be such that the portion PB closer to the surge tank 21 is wider than the portion PU further away from the surge tank 21 in the extension direction LM of the main passage 22M. In addition, the opening shape of the opening 44 may be such that it extends with the same width from portion PU to portion PB.

[0059] The shape of the opening 44 is not limited to being a long elongated hole in the extension direction LM, but can be any shape. For example, the shape of the opening 44 can be a long elongated hole in the direction perpendicular to the extension direction LM, or it can be circular or square.

[0060] The opening 44 can be provided in the inner portion of the curved portion 32 in the direction of curvature of the peripheral wall of the air intake section 22, or in the portion of the peripheral wall of the air intake section 22 corresponding to the inlet 31. The portion of the peripheral wall of the air intake section 22 in which the opening 44 is provided can be changed as desired.

[0061] The intake manifold according to the above embodiment can also be applied to intake manifolds of the type in which the air intake section does not have a curved section and the entire air intake section extends in a straight line.

[0062] The upstream portion 41 of the gas introduction section 25 may be connected to the sub-passage 43S in such a manner that the EGR gas flows out in a direction that intersects the extension direction LS of the sub-passage 43S at an angle other than "90 degrees". With this configuration as well, the EGR gas flowing from the upstream portion 41 into the sub-passage 43S of the downstream portion 43 can be made to collide with the inner surface of the sub-passage 43S, thereby causing turbulence in the flow of EGR gas within the sub-passage 43S.

[0063] Furthermore, when the EGR gas is brought into contact with the inner surface of the sub-passage 43S, the closer the collision angle is to "90 degrees", the stronger the turbulence that can be generated inside the sub-passage 43S. The strongest turbulence can be generated inside the sub-passage 43S when the collision angle is set to "90 degrees". For this reason, in order to generate strong turbulence inside the sub-passage 43S, it is preferable to connect the upstream part 41 of the gas introduction section 25 to the sub-passage 43S in a manner that causes the EGR gas to flow out in a direction perpendicular to the extension direction LS of the sub-passage 43S.

[0064] Alternatively, the upstream portion 41 of the gas introduction section 25 may be connected to the upper end portion of the sub-passage 43S. • As a gas inlet, a system can be adopted to introduce combustion gases (so-called blow-by gases) that have leaked from the combustion chamber of the internal combustion engine into the crankcase into the air inlet. In this configuration, the blow-by gas corresponds to the introduced gas. Alternatively, a system can be adopted to introduce evaporated fuel (so-called purge gases) from the fuel tank of the internal combustion engine into the air inlet. In this configuration, the purge gas corresponds to the introduced gas.

[0065] <Note> The above embodiment includes the configuration described in the following appendix. [Note 1] An intake manifold comprising a surge tank, an air introduction section connected to the surge tank in such a manner that it has a cylindrical shape in which the interior constitutes a main passage and introduces air into the surge tank through the main passage, and a gas introduction section having one end connected to the peripheral wall of the air introduction section and introducing an introduction gas other than air into the main passage, wherein the gas introduction section has a sub-passage extending inside along the main passage, and the end of the sub-passage on the surge tank side in the direction of extension of the sub-passage merges with the main passage, and the portion other than the end is closed off from the main passage.

[0066] [Note 2] The intake manifold as described in [Note 1], wherein the portion of the gas introduction section upstream of the sub-passage in the flow direction of the introduced gas is connected to the sub-passage in such a manner that the introduced gas flows out in a direction intersecting the extension direction of the sub-passage.

[0067] [Note 3] The intake manifold according to [Note 1] or [Note 2], wherein the air intake section has a curved section that extends in a curved manner in the direction of extension of the air intake section, and the sub-passage communicates with the main passage inside the curved section at the outer portion of the curved section in the direction of curvature.

[0068] [Note 4] The intake manifold according to any one of [Note 1] to [Note 3], wherein the opening shape of the confluence portion where the main passage and the sub-passage merge is an elongated hole that is long in the extending direction of the air introduction portion.

[0069] [Note 5] The intake manifold as described in [Note 4], wherein the opening shape of the confluence portion is tapered in the portion closer to the surge tank than in the portion further away from the surge tank in the extending direction of the air introduction portion.

[0070] [Note 6] The intake manifold according to any one of [Note 1] to [Note 5], wherein the air intake section is provided with a state detection unit for detecting the internal state of the main passage at a position further away from the surge tank in the extending direction of the air intake section than the confluence portion where the main passage and the sub-passage merge. [Explanation of Symbols]

[0071] 10…Intake Manifold 11…First component 111...Closing wall part 112...First Pier 12...Second component 121...Second Pier 13…Third component 21... Surge tank 21R…Rear wall 22...Air intake 221…Fixed part 22M…Main passage 22R…Rear wall 23... Branch pipe 231...Proximal end 232...Tip 24…Mounting flange 25...Gas inlet 251…Fixed part 25U…1st part 25B…Second part 26... State detection unit 27…Pressure sensor 28, 29… Through holes 281,291... Boss section 31…Entrance 32... Curved section 41…Upstream 43…Downstream part 431...lower end 43S…Sub-passage 44…Opening 45...Flow resistance member 50…Reinforcement ribs

Claims

1. A surge tank, and an air inlet connected to the surge tank in such a manner that the inside of the air inlet forms a cylindrical shape and introduces air into the inside of the surge tank through the main passage, In an intake manifold comprising a gas introduction section, one end of which is connected to the peripheral wall of the air introduction section and which introduces an introduction gas other than air into the main passage, The gas introduction section has a secondary passage inside, The aforementioned sub-passage extends along the main passage, merges with the main passage at the end of the sub-passage closest to the surge tank, and the portion of the sub-passage other than that end is blocked from the main passage. Intake manifold.

2. The gas introduction section is connected to the sub-passage in such a manner that the portion upstream of the sub-passage in the flow direction of the introduced gas is directed toward the inner surface of the sub-passage. The intake manifold according to claim 1.

3. The air intake section has a curved section that extends in a curved manner. The aforementioned secondary passage is connected to the main passage inside the curved portion at the outer portion opposite to the center of curvature of the curved portion. The intake manifold according to claim 1.

4. The opening shape of the confluence portion where the main passage and the sub-passage merge is an elongated hole that is long in the direction of airflow in the main passage. The intake manifold according to claim 1.

5. The opening shape of the aforementioned confluence is tapered, with the downstream portion being narrower than the upstream portion in the airflow direction of the main passage. The intake manifold according to claim 4.

6. The air intake section is provided with a state detection unit for detecting the internal state of the main passage, located upstream in the airflow direction of the main passage from the confluence point where the main passage and the sub-passage merge. The intake manifold according to claim 1.

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