Intake manifold

Abstract

To provide an intake manifold capable of inhibiting recirculation gas distributed to each cylinder of an internal combustion engine from becoming non-uniform and of stabilizing an operation of the internal combustion engine.SOLUTION: In an intake manifold 1, a first partition wall part 21A is provided on an upper wall 2C of a surge tank 2. The first partition wall part 21A is located on a third communication port 2d side on the right side of a first communication port 2b located on the left side in an arrangement direction of a branch pipe and on the first communication port 2b side of a purge gas introduction port 7a. The first partition wall part 21A extends from a front wall 2A of the surge tank 2 to a rear wall side of a rear end part of the purge gas introduction port 7a. A lower end part 21a of the first partition wall part 21A is located below an upper end part of a suction port and above a center part of the suction port.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an intake manifold. [Background technology]

[0002] In the intake system of an internal combustion engine, recirculated gas such as purge gas in a fuel tank is mixed with intake air and flows into a combustion chamber, where it is combusted.

[0003] BACKGROUND ART A conventional intake manifold for this type of internal combustion engine is known from Patent Document 1.

[0004] The intake manifold of the internal combustion engine described in Patent Document 1 has a gas introduction pipe arranged near the opening of the intake port, and gases (evaporative fuel gas, EGR gas, blow-by gas, etc. (hereinafter referred to as external gases) are mixed by the airflow of the intake air and diffused into the surge tank. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-207469 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the intake manifold of the internal combustion engine described in Patent Document 1, intake air blowback occurs inside the intake piping due to the influence of the opening and closing timing of the intake valves of each cylinder, and external gas is affected by the intake air blowback flow of intake air flowing from a specific cylinder side, which may cause the external gas to be distributed unevenly to each cylinder. This may cause variations in the fuel supplied to each cylinder, which may lead to unstable operation of the internal combustion engine.

[0007] Here, intake air blowback refers to a phenomenon in which intake air is blown back from the combustion chamber into the intake port when the intake valve is open during the compression stroke.

[0008] The present invention has been made in light of the above-mentioned circumstances, and aims to provide an intake manifold that can suppress uneven distribution of recirculated gas to each cylinder of an internal combustion engine, thereby stabilizing the operation of the internal combustion engine. [Means for solving the problem]

[0009] The present invention is provided with a surge tank to which an intake pipe is connected, a plurality of branch pipes that distribute air introduced into the surge tank to cylinders of an internal combustion engine, and a recirculation gas introduction pipe that introduces recirculation gas into the surge tank, wherein the surge tank is configured to include one side wall having a plurality of communication ports to which the plurality of branch pipes are connected, another side wall that faces the one side wall in a direction perpendicular to the arrangement direction of the plurality of branch pipes and has an intake port to which the intake pipe is connected, and an upper wall that connects upper ends of the one side wall and the other side wall and has a recirculation gas introduction port to which the recirculation gas introduction pipe is connected, and the intake port is configured to connect at least the plurality of branch pipes in a direction perpendicular to the arrangement direction of the plurality of branch pipes. An intake manifold facing one of the communication ports located on the furthest side in the arrangement direction of the branch pipes, wherein a first partition portion is provided on the upper wall of the surge tank, wherein the first partition portion is located closer to the one of the communication ports than the other of the communication ports located on the furthest side in the arrangement direction of the branch pipes, and closer to the other of the communication ports than the reflux gas inlet, and wherein the first partition portion is located closer to the one of the side walls from the other of the side walls of the surge tank than at least the end of the reflux gas inlet on the one of the side walls, and wherein the lower end of the first partition portion is located lower than the upper end of the intake port and higher than the center of the intake port. [Effects of the Invention]

[0010] As described above, according to the present invention, it is possible to prevent the recirculated gas from being distributed unevenly to each cylinder of the internal combustion engine, thereby stabilizing the operation of the internal combustion engine. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a right side view of an intake manifold and an intake pipe according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of an intake manifold and an intake pipe according to one embodiment of the present invention. [Figure 3] 3 is a cross-sectional view taken along the line III-III in FIG. [Figure 4] 4 is a cross-sectional view taken along the line IV-IV in FIG. [Figure 5] 5 is a cross-sectional view taken along the arrows VV in FIG. [Figure 6] 6 is a cross-sectional view taken along the line VI-VI in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] An intake manifold according to one embodiment of the present invention includes a surge tank to which an intake pipe is connected, a plurality of branch pipes that distribute air introduced into the surge tank to cylinders of an internal combustion engine, and a recirculation gas introduction pipe that introduces recirculation gas into the surge tank. The surge tank includes one side wall having a plurality of communication ports to which the plurality of branch pipes are connected, another side wall that faces the one side wall in a direction perpendicular to the arrangement direction of the plurality of branch pipes and has an intake port to which the intake pipe is connected, and an upper wall that connects upper ends of the one side wall and the other side wall and has a recirculation gas introduction port to which the recirculation gas introduction pipe is connected. The intake port is arranged in a direction perpendicular to the arrangement direction of the plurality of branch pipes. An intake manifold that faces one of the communication ports located on the furthest side in the arrangement direction of at least a plurality of branch pipes in an orthogonal direction, and has a first partition portion provided on the upper wall of the surge tank, and the first partition portion is located on the one communication port side of the other communication port located on the furthest side in the arrangement direction of the plurality of branch pipes, and on the other communication port side of the reflux gas inlet, and the first partition portion is located on the one side wall side of at least the end of the reflux gas inlet on the one side wall side from the other side wall of the surge tank, and the lower end of the first partition portion is located below the upper end of the intake port and above the center of the intake port.

[0013] As a result, the intake manifold according to one embodiment of the present invention can suppress uneven distribution of recirculated gas to each cylinder of the internal combustion engine, thereby stabilizing the operation of the internal combustion engine. [Example]

[0014] An intake manifold according to an embodiment of the present invention will now be described with reference to the drawings. 1 to 6 are diagrams showing an intake manifold according to one embodiment of the present invention.

[0015] 1 to 6, the up / down, front / rear, left / right directions are defined relative to the intake manifold, with the intake pipe side being the front and the branch pipe side being the rear. The direction in which the branch pipes are arranged is defined as the left / right direction, and the vertical direction is defined as the up / down direction.

[0016] First, the configuration will be described. 1 and 2, an intake manifold 1 mounted on a vehicle includes a surge tank 2, and a first branch pipe 3, a second branch pipe 4, and a third branch pipe 5 that constitute branch pipes.

[0017] The surge tank 2 includes a front wall 2A, a rear wall 2B facing the front wall 2A in the front-rear direction, and an upper wall 2C connecting the upper ends of the front wall 2A and the rear wall 2B.

[0018] A cylindrical air intake 2a is formed in the front wall 2A, and the air intake 2a protrudes forward from the front wall 2A.

[0019] The rear end of an intake pipe 6 is connected to the intake port 2a. The front end of each intake pipe 6 is connected to a valve body that houses an intake valve (not shown). The intake pipe 6 introduces intake air purified by an air cleaner (not shown) from the intake port 2a into the surge tank 2.

[0020] As shown in FIGS. 4 and 5, a first communication port 2b, a second communication port 2c, and a third communication port 2d that constitute communication ports are formed in the rear wall 2B.

[0021] A first branch pipe 3, a second branch pipe 4 and a third branch pipe 5 are connected to the first communication port 2b, the second communication port 2c and the third communication port 2d, respectively, and the first branch pipe 3, the second branch pipe 4 and the third branch pipe 5 are arranged in the left-right direction.

[0022] The first branch pipe 3, the second branch pipe 4, and the third branch pipe 5 are connected to an internal combustion engine (not shown), and distribute the air introduced into the surge tank 2 to the first, second, and third cylinders (not shown) of the engine via an intake port (not shown) of the engine.

[0023] That is, the first branch pipe 3 is connected to the first cylinder via an intake port, the second branch pipe 4 is connected to the second cylinder via an intake port, and the third branch pipe 5 is connected to the third cylinder via an intake port. The engine of this embodiment is an in-line three-cylinder engine.

[0024] Hereinafter, the arrangement direction (left-right direction) of the first branch pipe 3, the second branch pipe 4 and the third branch pipe 5 will be referred to as the branch pipe arrangement direction.

[0025] The rear wall 2B faces the front wall 2A in a direction (front-rear direction) perpendicular to the arrangement direction of the branch pipes. In this embodiment, the rear wall 2B forms one of the side walls, and the front wall 2A forms the other side wall.

[0026] A purge gas introduction pipe 7 is connected to the front portion of the upper wall 2C, and a purge gas introduction port 7a of the purge gas introduction pipe 7 is formed in the front portion of the upper wall 2C. The purge gas introduction pipe 7 introduces evaporated fuel gas as purge gas into the surge tank 2. The purge gas introduction pipe 7 constitutes a reflux gas introduction pipe.

[0027] A blow-by gas introduction pipe 8 is connected to the upper wall 2C, and the blow-by gas introduction pipe 8 introduces blow-by gas into the surge tank 2.

[0028] In this embodiment, the purge gas introduced into the purge gas introduction pipe 7 constitutes a recirculation gas. Note that the gas introduced into the purge gas introduction pipe 7 may be a blow-by gas (in this case, for example, the purge gas is introduced into the blow-by gas introduction pipe 8), an EGR (Exhaust Gas Recirculation) gas, or the like, as long as it is a recirculation gas.

[0029] 5, the intake port 2a faces the second communication port 2c and the third communication port 2d, which are located on the right side in the arrangement direction of the branch pipes. In other words, the intake port 2a is located closer to the third communication port 2d than the first communication port 2b, which is located on the left side in the arrangement direction of the branch pipes.

[0030] In this embodiment, the first communication port 2b constitutes the other communication port located on the other side in the arrangement direction of the branch pipes, and the third communication port 2d constitutes the one communication port located on the one side in the arrangement direction of the branch pipes. Note that it is sufficient that the intake port 2a faces at least the third communication port 2d in the front-rear direction.

[0031] 3 and 5, the center O of the air intake port 2a is located to the right of the right end 2r of the second communication port 2c and to the left of the left end 2f of the third communication port 2d, and the center O is located above the second communication port 2c and the third communication port 2d. Note that the air intake port 2a, the second communication port 2c, and the third communication port 2d may be located at the same height.

[0032] As shown in Figure 5, the purge gas inlet 7a is located to the right of the first communication port 2b (towards the third communication port 2d) and to the left of the upper end 2e of the intake port 2a (towards the first communication port 2b) (see Figure 3).

[0033] 4 and 5, a first partition wall portion 21A is provided on the lower surface of the upper wall 2C inside the surge tank 2. The first partition wall portion 21A is located closer to the third communication port 2d than the first communication port 2b on the left side in the arrangement direction of the branch pipes, and closer to the first communication port 2b than the purge gas inlet port 7a, and faces the second branch pipe 4 in the front-rear direction.

[0034] 5, the first partition wall portion 21A extends from the front wall 2A of the surge tank 2 rearward of the rear end portion 7b of the purge gas inlet 7a. In this embodiment, the rear end portion 7b constitutes an end portion of the reflux gas inlet on one side wall side.

[0035] 3, the lower end 21a of the first partition wall portion 21A is located below the upper end 2e of the air intake port 2a and above the center O of the air intake port 2a. In other words, the lower end 21a of the first partition wall portion 21A is located between the upper end 2e of the air intake port 2a and the center O of the air intake port 2a in the vertical direction.

[0036] 4 and 5, a second partition wall portion 21B is provided on the lower surface of the upper wall 2C inside the surge tank 2. The second partition wall portion 21B extends from the rear end portion 21b of the first partition wall portion 21A in the arrangement direction of the branch pipes (left-right direction) and is integrated with the first partition wall portion 21A.

[0037] In this embodiment, the rear end 21b of the second partition wall portion 21B constitutes an end portion on one side wall side. The first partition wall portion 21A and the second partition wall portion 21B may be separate bodies.

[0038] The right end 21c of the second partition wall portion 21B is located at a position farther from the first communication port 2b than the center O of the intake port 2a. In this embodiment, the right end 21c of the second partition wall portion 21B forms the end of the second partition wall portion in the extending direction.

[0039] As shown in Figure 5, when the purge gas inlet 7a is viewed from below, the purge gas inlet 7a is surrounded by the front wall 2A, the first partition wall portion 21A, and the second partition wall portion 21B, and the right side of the purge gas inlet 7a is open.

[0040] As shown in Figure 3, the lower end 21f of the second partition portion 21B is formed in a linear shape that extends in a curved shape from the lower end 21a of the first partition portion 21A to follow the outer shape of the air intake port 2a, and then at a position higher than the lower end 21a of the first partition portion 21A and above the upper end 2e of the air intake port 2a.

[0041] Hereinafter, the curved portion of the second partition wall portion 21B will also be referred to as a curved portion 21d, and the straight portion will also be referred to as a straight portion 21e.

[0042] Next, the operation of the intake manifold 1 of this embodiment will be described. In an in-line three-cylinder engine, the crankshaft (not shown) installed in the engine has a phase angle of 120° for each cylinder. In a four-stroke engine, the crankshaft rotates twice (720° in crank angle) and all cylinders complete the four strokes of intake, compression, combustion, and exhaust.

[0043] The ignition order of an in-line three-cylinder engine is the first cylinder connected to the first branch pipe 3, the third cylinder connected to the third branch pipe 5, and the second cylinder connected to the second branch pipe 4, and the intake valves open in the order of the first intake valve, the third intake valve, and the second intake valve.

[0044] The intake valves open on the intake stroke, so when one cylinder's intake valve is open, the other cylinder's intake valves are closed. The exhaust valves open on the exhaust stroke, so when one cylinder's exhaust valve is open, the other cylinder's exhaust valves are closed.

[0045] During the intake stroke, the piston descends, creating a negative pressure inside the cylinder and drawing air into the cylinder. However, once the piston passes bottom dead center and begins to rise during the intake stroke, air is drawn in due to the inertia effect even as the piston enters the compression stroke.

[0046] In order to increase the efficiency of air filling, the intake valve is open until the beginning of the compression stroke, so the theoretical range over which the intake valve opens is 180° in crank angle, but the actual range over which the intake valve opens is greater than 180° in crank angle.

[0047] When the intake valve is closed, the intake port is under positive pressure, causing air to flow from the combustion chamber of the cylinder toward the surge tank 2. In other words, when the intake valve is open during the compression stroke, intake air is blown back from the combustion chamber toward the surge tank 2, a phenomenon known as intake air blowback.

[0048] In an inline three-cylinder engine, the same stroke is repeated every 240° of crank angle. In other words, the intake stroke (and other strokes are the same) is performed in a 240° phase in the order of the first cylinder, the third cylinder, the second cylinder, and then the first cylinder. Therefore, the range over which the intake valve is open is slightly greater than 180° of crank angle (less than 240° of crank angle), and there is only one cylinder with an open intake valve and exhaust valve on both the intake and exhaust sides. For this reason, intake backflow occurs over a range of crank angle slightly greater than 180°.

[0049] That is, for example, when the intake valve of the first cylinder is open during the compression stroke, intake air is blown back from the combustion chamber into the intake port.

[0050] In the intake manifold 1, when we look at the third cylinder that is connected to the third communication port 2d via the third branch pipe 5 and the second cylinder that is connected to the second communication port 2c via the second branch pipe 4, the second communication port 2c and the third communication port 2d are opposite the intake port 2a in the front-to-rear direction.

[0051] As a result, when intake air blowback occurs from the second branch pipe 4 and the third branch pipe 5 in a direction opposite to the intake main flow W1 (see Figures 5 and 6) drawn from the intake pipe 6 into the surge tank 2, the intake air blowback occurring in the second branch pipe 4 and the third branch pipe 5 is offset by the intake main flow W1.

[0052] Therefore, the purge gas introduced into the surge tank 2 from the purge gas introduction pipe 7 is not interfered with by the blowback, and the flow of the purge gas is not disturbed by the intake blowback.

[0053] On the other hand, the first cylinder, which is connected via the first branch pipe 3 to the first communication port 2b that is the farthest from the intake port 2a in the arrangement direction of the branch pipes, is less susceptible to the influence of the intake main flow W1. In other words, the intake main flow W1 is less likely to cancel out the intake blowback.

[0054] 5 and 6, the flow of intake air blowback W2 of the first branch pipe 3 (first cylinder) will be described.

[0055] When the intake valve of the first cylinder is open during the compression stroke, intake air is blown back from the combustion chamber to the intake port, causing intake backflow W2. The intake backflow W2 is returned to the surge tank 2 from the first branch pipe 3 through the first communication port 2b.

[0056] This intake air blowback W2 does not flow from the first branch pipe 3 to the third branch pipe 5, but collides with the front wall 2A of the surge tank 2 due to the momentum of being returned from the first branch pipe 3 through the first communication port 2b to the surge tank 2, and rises along the front wall 2A.

[0057] When the third cylinder transitions to the intake stroke, the intake backflow W2 that has risen along the front wall 2A is drawn toward the third branch pipe 5 (the third cylinder side), but this intake backflow W2 collides with the first partition portion 21A, loses momentum, and descends along the front wall 2A.

[0058] Purge gas is introduced into the surge tank 2 from the purge gas introduction pipe 7 through the purge gas introduction port 7a, but since the intake air blowback W2 is obstructed by the first partition wall portion 21A, the purge gas introduced into the surge tank 2 does not interfere with the intake air blowback W2 from the first branch pipe 3.

[0059] This prevents the purge gas from flowing to the third branch pipe 5 side (third cylinder side) and being introduced into the third cylinder during the intake stroke of the third cylinder.

[0060] Furthermore, when the intake air blowback W2 that collides with the first partition portion 21A flows around from the first partition portion 21A to the purge gas inlet 7a side, it is blocked by the second partition portion 21B, thereby preventing the purge gas introduced into the surge tank 2 from purge gas inlet 7a from interfering with the intake air blowback W2.

[0061] Therefore, it is possible to more effectively prevent the purge gas from flowing to the third branch pipe 5 side (third cylinder side) and being introduced into the third cylinder during the intake stroke of the third cylinder.

[0062] As described above, the intake manifold 1 of this embodiment includes the surge tank 2 to which the intake pipe 6 is connected, the first branch pipe 3, the second branch pipe 4, and the third branch pipe 5 that distribute the air introduced into the surge tank 2 to the cylinders of the engine, and the purge gas introduction pipe 7 that introduces recirculated gas into the surge tank 2.

[0063] The surge tank 2 is configured to include a rear wall 2B having a first communication port 2b, a second communication port 2c, and a third communication port 2d to which a first branch pipe 3, a second branch pipe 4, and a third branch pipe 5 are respectively connected; a front wall 2A facing the front wall 2A in a front-to-rear direction perpendicular to the arrangement direction of the branch pipes and having an intake port 2a to which an intake pipe 6 is connected; and an upper wall 2C connecting the upper ends of the front wall 2A and the rear wall 2B and having a purge gas inlet port 7a to which a purge gas inlet pipe 7 is connected.

[0064] The intake port 2a faces the second communication port 2c and the third communication port 2d located on the right side of the arrangement direction of the branch pipes in the front-rear direction perpendicular to the arrangement direction of the branch pipes.

[0065] A first partition wall portion 21A is provided on the upper wall 2C of the surge tank 2, and the first partition wall portion 21A is located on the third communication port 2d side, which is to the right of the first communication port 2b, which is located on the left side in the arrangement direction of the branch pipes, and on the first communication port 2b side, which is to the purge gas inlet port 7a.

[0066] In addition, the first partition wall portion 21A extends from the front wall 2A of the surge tank 2 toward the rear wall 2B beyond the rear end portion 7b of the purge gas inlet 7a.

[0067] As a result, in the situation between the closing of the first intake valve and the opening of the third intake valve, the intake backflow W2 from the first cylinder, which is less affected by the main intake flow W1, causes purge gas to flow toward the third branch pipe 5, suppressing it from being taken in during the intake stroke of the third cylinder and preventing purge gas from concentrating in the third cylinder.

[0068] Furthermore, according to the intake manifold 1 of this embodiment, the lower end 21a of the first partition wall portion 21A is located below the upper end 2e of the intake port 2a and above the center O of the intake port 2a.

[0069] This prevents the intake main flow W1 introduced into the surge tank 2 from the intake port 2a from interfering with the intake backflow W2, and allows the purge gas introduced into the surge tank 2 from the purge gas inlet 7a to flow into the first branch pipe 3.

[0070] As a result, it is possible to prevent the distribution of purge gas to each cylinder of the engine from becoming uneven, thereby stabilizing the operation of the engine.

[0071] Furthermore, according to the intake manifold 1 of this embodiment, a second partition wall portion 21B is provided on the upper wall 2C of the surge tank 2, and the second partition wall portion 21B extends from the rear end portion 21b of the first partition wall portion 21A in the arrangement direction of the branch pipes.

[0072] The right end 21c of the second partition wall portion 21B is located at a position farther from the first communication port 2b than the center O of the intake port 2a. In other words, the right end 21c of the second partition wall portion 21B faces the third communication port 2d in the front-rear direction.

[0073] This prevents the intake backflow W2 that collides with the first partition wall 21A from flowing around from the first partition wall 21A to the purge gas inlet port 7a side, and more effectively prevents the purge gas introduced into the surge tank 2 from purge gas inlet port 7a from interfering with the intake backflow W2. This more effectively prevents the purge gas from concentrating on the third cylinder.

[0074] Furthermore, by integrating the first partition wall portion 21A with the second partition wall portion 21B, the rigidity of the first partition wall portion 21A can be increased by the second partition wall portion 21B.

[0075] This prevents the first partition portion 21A from becoming unstable when the intake air blowback collides with the first partition portion 21A, and more effectively prevents the intake air blowback from interfering with the purge gas by the first partition portion 21A.

[0076] Furthermore, according to the intake manifold 1 of this embodiment, the lower end portion 21f of the second partition portion 21B has a straight portion 21e that extends in a straight line from the lower end portion 21a of the first partition portion 21A through a curved portion 21d that follows the outer shape of the intake port 2a, at a position higher than the lower end portion 21a of the first partition portion 21A and above the upper end portion 2e of the intake port 2a.

[0077] This prevents the straight portion 21e from interfering with the intake air introduced into the surge tank 2 from the intake port 2a, and prevents the second partition wall portion 21B from increasing intake resistance.

[0078] Furthermore, by connecting the lower end 21a of the first partition portion 21A and the straight portion 21e of the second partition portion 21B by the curved portion 21d, the vertical dimension of the second partition portion 21B can be secured by the curved portion 21d, and the intake air backflow W2 that flows from the first partition portion 21A around the curved portion 21d can be effectively prevented from coming into contact with the curved portion 21d and flowing around to the purge gas inlet 7a side.

[0079] Therefore, it is possible to more effectively prevent the purge gas introduced into the surge tank 2 from interfering with the intake air blowback W2 through the purge gas inlet 7a.

[0080] In the intake manifold 1 of this embodiment, the intake port 2a faces the second communication port 2c and the third communication port 2d in the front-rear direction perpendicular to the arrangement direction of the branch pipes, but it may face the first communication port 2b and the second communication port 2c in the front-rear direction perpendicular to the arrangement direction of the branch pipes, or it may face at least the first communication port 2b.

[0081] In this case, the first partition wall portion 21A is disposed closer to the first communication port 2b than the third communication port 2d on the right side in the arrangement direction of the branch pipes, and closer to the third communication port 2d than the purge gas inlet 7a. In this way, the first partition wall portion 21A can suppress the intake air blowback from the third branch pipe 5.

[0082] While an embodiment of the present invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made thereto without departing from the scope of the present invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0083] 1 intake manifold 2 surge tank 2A Front wall (other side wall) 2a Air intake 2B Back wall (one side wall) 2b First communication port (the other communication port located on the other side in the arrangement direction of the multiple branch pipes) 2C Upper wall 2c Second communication port 2d Third communication port (one of the communication ports located on the farthest side in the arrangement direction of multiple branch pipes) 2e Upper end (upper end of intake port) 3 First branch pipe (branch pipe) 4 Second branch pipe (branch pipe) 5 Third branch pipe (branch pipe) 6 Intake pipe 7 Purge gas inlet pipe (reflux gas inlet pipe) 7b Rear end (end on one side wall of the reflux gas inlet) 21A First partition 21a Lower end (lower end of first partition wall portion) 21B second partition wall 21c Right end (end in the direction in which the second partition wall portion extends) 21f Lower end (lower end of second partition wall) O Center of the air intake

Claims

1. a surge tank to which an intake pipe is connected, a plurality of branch pipes for distributing air introduced into the surge tank to cylinders of an internal combustion engine, and a recirculation gas introduction pipe for introducing recirculation gas into the surge tank; The surge tank is one side wall having a plurality of communication ports to which the plurality of branch pipes are connected; another side wall facing the one side wall in a direction perpendicular to the arrangement direction of the plurality of branch pipes, the other side wall having an intake port to which the intake pipe is connected; an upper wall that connects upper ends of the one side wall and the other side wall and has a reflux gas inlet to which the reflux gas inlet pipe is connected; the intake port is an intake manifold that faces at least one of the communication ports located on the most one side in the arrangement direction of the plurality of branch pipes in a direction perpendicular to the arrangement direction of the plurality of branch pipes, a first partition wall is provided on an upper wall of the surge tank; the first partition wall portion is located closer to the one communication port than the other communication port that is located furthest to the other in an arrangement direction of the plurality of branch pipes, and is located closer to the other communication port than the reflux gas inlet, the first partition wall is located at least closer to the one side wall than an end of the reflux gas inlet on the one side wall side from the other side wall of the surge tank, An intake manifold, wherein a lower end of the first partition wall is located below an upper end of the intake port and above a center of the intake port.

2. a second partition wall is provided on an upper wall of the surge tank, a rear end portion of the second partition wall portion extends from an end portion of the first partition wall portion on the one side wall side in an arrangement direction of the plurality of branch pipes, 2. The intake manifold according to claim 1, wherein an end portion of the second partition wall in the extending direction is located at a position farther from the other communication port than at least a center portion of the intake port.

3. 3. The intake manifold according to claim 2, wherein the lower end of the second partition wall is formed in a linear shape that extends linearly from the lower end of the first partition wall through a curved shape that follows the outer shape of the intake port, at a position higher than the lower end of the first partition wall and at least above the upper end of the intake port.

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