JP7003681B2 - Internal combustion engine intake manifold - Google Patents

Description

The present disclosure relates to an intake manifold of an internal combustion engine.

As an intake system structure of this type of internal combustion engine, for example, Patent Document 1 includes two intake ports for one cylinder, one intake port as a swirl port, and the other intake port as a tumble port. The structure is disclosed.

Japanese Unexamined Patent Publication No. 2016-133082

By the way, of the two intake ports, the EGR gas is recirculated from the exhaust gas recirculation system (hereinafter referred to as the EGR device) to one of the intake ports, and the EGR gas and fresh air enter the cylinder from the intake port. If the air-fuel mixture is vigorously introduced, the air-fuel mixture may flow into the vicinity of the spark plug on the cylinder axis side and cause misfire or the like. Therefore, it is desired to improve the intake air flow introduced into the cylinder from the intake port.

The technique of the present disclosure is intended to improve the intake air flow introduced into the cylinder from the intake port.

The technique of the present disclosure is an intake manifold of an internal combustion engine including a first intake port and a second intake port for introducing intake air into a cylinder, which is connected to the first intake port and takes intake air to the first intake port. A first intake pipeline to be introduced and a second intake pipeline connected to the second intake port to introduce intake air into the second intake port are provided, and at least an outlet portion of the first intake pipeline is provided. The opening diameter is formed to be smaller than the opening diameter of at least the inlet portion of the first intake port, and a step portion is formed at the connection portion between the first intake pipeline and the first intake port. do.

Further, it is preferable that the opening diameter of at least the outlet portion of the front second intake pipe is formed to be the same as the opening diameter of at least the inlet portion of the second intake port.

Further, an exhaust gas recirculation flow path for recirculating exhaust gas from the exhaust system of the internal combustion engine to the intake system is connected to the first intake pipe, and the second intake pipe is connected to the second intake pipe. It is preferable that an injector for injecting fuel is provided in the intake flow path of the above.

Further, it is preferable that the first intake pipe and the second intake pipe are formed by an integrated intake manifold.

Further, it is preferable that the first intake port is a swirl port and the second intake port is a tumble port.

Further, the injector may inject natural gas as the fuel.

According to the technique of the present disclosure, it is possible to improve the intake air flow introduced into the cylinder from the intake port.

It is a schematic whole block diagram which shows the intake / exhaust system of the internal combustion engine which concerns on this embodiment. It is a schematic sectional drawing which shows the cylinder head, the intake manifold, and the exhaust manifold which concerns on this embodiment. It is a schematic diagram explaining the mixed intake layer formed in the cylinder (combustion chamber) which concerns on this embodiment. It is a schematic cross-sectional view which looked at the fuel injection structure which concerns on this embodiment from the axial direction of the intake flow path. FIG. 4 is a cross-sectional view taken along the line AA of FIG. (A) is a schematic cross-sectional view showing a connection portion between the first upper supply flow path of the intake manifold and the first intake port (swirl port) of the cylinder head according to the present embodiment, and (B) is a schematic cross-sectional view. It is a schematic cross-sectional view which shows the connection part of the 1st lower supply flow path of the intake manifold which concerns on this embodiment, and the 2nd intake port (tumble port) of a cylinder head.

Hereinafter, the intake manifold of the internal combustion engine according to the present embodiment will be described with reference to the accompanying drawings. The same parts are designated by the same reference numerals, and their names and functions are also the same. Therefore, detailed explanations about them will not be repeated.

[overall structure]
FIG. 1 is a schematic overall configuration diagram showing an intake / exhaust system of an internal combustion engine according to the present embodiment. The engine E as an internal combustion engine mainly includes an engine body 10 including a cylinder head, a cylinder block, and the like.

The cylinder block of the engine body 10 is provided with a plurality of cylinders C (hereinafter, also referred to as cylinders) for accommodating pistons (not shown) so as to be reciprocating. Further, the cylinder head of the engine body 10 is provided with intake ports 11 and 12 for introducing intake air into each cylinder C and an exhaust port 16 for drawing out exhaust gas from each cylinder C. An intake valve 13 is provided in each of the intake ports 11 and 12, and an exhaust valve 17 is provided in each of the exhaust ports 16. The intake valve 13 and the exhaust valve 17 are opened and closed by a valve operating mechanism (not shown).

In the illustrated example, the engine E is shown as an in-line 4-cylinder engine, but the engine E is not limited to this, and may be a single-cylinder engine or a multi-cylinder engine other than the 4-cylinder engine. Further, the engine E is shown as a 4-valve engine provided with two intake ports 11 and 12 and two exhaust ports 16 for each cylinder C, but has two intake ports and an exhaust port. It may be a 3-valve engine provided with one.

An intake manifold 20 that distributes intake air to the intake ports 11 and 12 is attached to the intake side of the cylinder head of the engine body 10. An intake pipe 70 is connected to the intake manifold 20, and the intake pipe 70 is provided with an air cleaner 71, a compressor 81 of a supercharger 80, an intercooler 72, an intake throttle valve 73, and the like in this order from the intake upstream side. .. The detailed structure of the intake manifold 20 will be described later.

An exhaust manifold 90 that collects exhaust gas from each exhaust port 16 is attached to the exhaust side of the cylinder head of the engine body 10. An exhaust pipe 91 is connected to the exhaust manifold 90. The exhaust pipe 91 is provided with a turbine 82 of the turbocharger 80, an exhaust purification device 93, and the like in order from the exhaust upstream side.

The EGR (Exhaust Gas Recirculation) device 94 is a so-called high-pressure EGR device, and has an EGR pipe 95 that branches from the exhaust manifold 90 (or an exhaust pipe 91 on the exhaust upstream side of the turbine 82) and joins the intake manifold 20. The EGR cooler 96 provided in the EGR pipe 95 and the EGR valve 97 provided in the downstream side of the EGR cooler 96 of the EGR pipe 95 are provided. In the EGR device 94, the EGR gas amount (EGR rate) is appropriately adjusted by controlling the opening degree of the EGR valve 97 by a control unit (not shown) according to the operating state of the engine E. There is.

[Intake / exhaust system structure]
Next, the detailed structure of the intake manifold 20, the cylinder head CH, the exhaust manifold 90, and the EGR device 94, which are the main parts of the intake / exhaust system structure according to the present embodiment, will be described with reference to FIG.

FIG. 2 is a schematic cross-sectional view showing a cylinder head CH, an intake manifold 20, and an exhaust manifold 90 of the engine E according to the present embodiment. As shown in the figure, the cylinder head CH is provided with a first intake port 11, a second intake port 12, and two exhaust ports 16 corresponding to each cylinder C. Further, four spark plugs P1 to P4 having their tip portions positioned at substantially the axial center of the cylinder C are attached to the cylinder head CH for each cylinder C.

The first intake ports 11A to D are swirl ports in which the vicinity of the opening on the cylinder C side is formed in a spiral shape. That is, since the first intake ports 11A to D are swirl ports, the intake air flowing into the cylinder C from the first intake ports 11A to D becomes an air flow that swirls around the axis in the vicinity of the opening on the cylinder C side. It is introduced into the cylinder C and is configured to be a swirl that swivels laterally in the cylinder C.

The second intake ports 12A to D are tumble ports (tangential ports) in which the vicinity of the opening on the cylinder C side extends in the tangential direction of the circle centered on the axis of the cylinder C and has less intake resistance than the swirl port. ). That is, since the second intake ports 12A to D are tumble ports, the intake air flowing into the cylinder C from the second intake ports 12A to D is introduced so as to be biased to one side with respect to the center line of the cylinder C. , It is configured to be a tumble that swivels in the substantially central portion of the cylinder C in the vertical direction.

An exhaust manifold 90 for collecting exhaust gas is connected to the exhaust port 16. Further, an inlet portion of the exhaust pipe 91 and an inlet portion of the EGR pipe 95 are connected to the exhaust collecting portion 90A of the exhaust manifold 90, respectively.

The intake manifold 20 includes a first distribution section 21 on the inlet (upstream) side, a second distribution section 30 (first intake line) on the outlet (downstream) side, and a third distribution section 40 (second intake line). And have. These first to third distribution units 21, 30, 40 are preferably integrally formed.

The downstream end flange of the intake pipe 70 (or the housing of the intake throttle valve 73 shown in FIG. 1) is fixed to the opening flange portion 22 of the first distribution portion 21 by bolts and nuts (not shown). The downstream side of the first distribution unit 21 is bifurcated into an upper branch flow path 23 extending diagonally upward and a lower branch flow path 24 extending diagonally downward. That is, the fresh air that has flowed from the intake pipe 70 into the first distribution section 21 is distributed to the upper branch flow path 23 and the lower branch flow path 24, respectively.

The second distribution unit 30 is provided above the third distribution unit 40. Specifically, the second distribution unit 30 includes an upper distribution flow path 31, a first upper supply flow path 32, a second upper supply flow path 33, a third upper supply flow path 34, and a fourth upper supply flow path. It is provided with a flow path 35.

The upper distribution flow path 31 extends in the cylinder arrangement direction (longitudinal direction of the engine E). The outlet portion of the upper branch flow path 23 is connected to a substantially intermediate position in the longitudinal direction of the upper flow path 31. Further, an outlet portion of the EGR pipe 95 is connected to one end portion (right end portion in the illustrated example) of the upper distribution flow path 31 in the longitudinal direction. That is, the fresh air flowing from the upper branch flow path 23 into the upper flow path 31 and the EGR gas flowing from the EGR pipe 95 into the upper flow path 31 are effectively in the process of flowing in the upper flow path 31. It is designed to be mixed. The connection points of the upper branch flow path 23 and the EGR pipe 95 with respect to the upper distribution flow path 31 are not limited to the illustrated examples, and can be appropriately set according to the layout and the like.

The first to fourth upper supply flow paths 32, 33, 34, 35 are branched from the upper flow path 31, and inside the first to fourth upper flow paths 32, 33, 34, 35, fresh air and EGR gas mixed in the upper flow path 31 are formed. Air-fuel mixture (hereinafter, also referred to as EGR mixed intake air) flows in. Further, the outlet portions of the first to fourth upper supply flow paths 32, 33, 34, 35 are connected to the inlet portions of the first intake ports 11A to D formed as swirl ports, respectively. That is, the EGR mixed intake air flowing from the upper distribution flow path 31 into the first to fourth upper supply flow paths 32, 33, 34, 35 is distributed to each of the first intake ports 11A to D and introduced into each cylinder C. It is configured to be.

The third distribution unit 40 is provided below the second distribution unit 30. Specifically, the third distribution unit 40 includes a lower distribution flow path 41, a first lower supply flow path 42, a second lower supply flow path 43, and a third lower supply flow path 44. It is provided with a fourth lower supply flow path 45.

The lower distribution flow path 41 extends below the upper distribution flow path 31 in the cylinder arrangement direction (longitudinal direction of the engine E). The outlet portion of the lower branch flow path 24 is connected to a substantially intermediate position in the longitudinal direction of the lower flow path 41. That is, the fresh air that has flowed from the intake pipe 70 into the lower branch flow path 24 of the first distribution section 21 is introduced from the lower branch flow path 24 into the lower flow path 41. The connection point of the lower branch flow path 24 with respect to the lower distribution flow path 41 is not limited to the illustrated example, and can be appropriately set according to the layout and the like.

The first to fourth lower supply channels 42, 43, 44, 45 are branched from the lower distribution channel 41, and fresh air flowing in the lower distribution channel 41 flows into the inside thereof. .. Further, the outlet portions of the first to fourth lower supply flow paths 42, 43, 44, 45 are connected to the inlet portions of the second intake ports 12A to D formed as tumble ports, respectively. Further, the first to fourth lower supply channels 42, 43, 44, 45 are injected with fuel (for example, natural gas in this embodiment) accumulated in a common rail (not shown). Injectors 51, 52, 53, 54 are provided, respectively.

That is, the fresh air flowing from the lower flow path 41 into the first to fourth lower supply channels 42, 43, 44, 45 and the fuel injected from the first to fourth injectors 51, 52, 53, 54. Is mixed in the first to fourth lower supply channels 42, 43, 44, 45, and the mixture of fresh air and fuel (hereinafter, also referred to as fuel mixed intake) is each second intake. It is configured to be supplied to the ports 12A to D and introduced into each cylinder C.

According to the intake / exhaust system structure of the present embodiment described in detail above, the first to fourth upper supply flow paths 32, 33, 34, 35 of the intake manifold 20 for circulating the EGR mixed intake air (fresh air and EGR gas) are provided. By connecting to the first intake port (swirl port) 11A to D, it is introduced into the cylinder C from the first to fourth upper supply flow paths 32, 33, 34, 35 via the first intake port 1A to D. The EGR mixed intake air is configured to be a swirl that swirls laterally in the cylinder C. Further, the first to fourth lower supply channels 42, 43, 44, 45 of the intake manifold 20 for circulating the fuel mixed intake (fuel and fresh air) are connected to the second intake ports (tumble ports) 12A to D. As a result, the fuel mixed intake air introduced into the cylinder C from the first to fourth lower supply flow paths 42, 43, 44, 45 via the second intake ports 12A to D is vertically inside the cylinder C. It is configured to be a swiveling tumble.

That is, as shown in FIG. 3, a swirl EGR mixed intake layer M1 that swirls along the wall surface of the cylinder C is formed in the cylinder C (combustion chamber), and a substantially central portion in the cylinder C is vertically formed. A fuel-mixed intake layer M2 of a tumble that swivels in a direction is formed (Note that M3 in the figure conceptually indicates an intermediate mixed intake layer of these M1 and M2). As a result, the fuel mixed intake air having a high fuel concentration can be effectively flowed into the vicinity of the center of the cylinder C where the spark plugs P1 to 4 are located, and the combustion efficiency can be surely improved. Further, by swirling the EGR mixed intake air as a swirl along the inner wall of the cylinder C without flowing into the center of the cylinder C where the spark plugs P1 to 4 are located, it is possible to effectively suppress misfire. Become. Further, by effectively securing the amount of EGR gas, it is possible to reduce the pumping loss due to the decrease in the intake / exhaust flow rate, and it is possible to surely improve the fuel efficiency performance. Further, by ensuring the amount of EGR gas, deterioration of exhaust emissions can be effectively prevented.

[Fuel injection structure]
Next, the details of the fuel injection structure according to the present embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 is a schematic cross-sectional view of the fuel injection structure according to the present embodiment as viewed from the axial direction of the intake flow path, and FIG. 5 is a cross-sectional view taken along the line AA of FIG. As described above, the first to fourth injectors 51, 52, 53, 54 of the present embodiment are the first to fourth intake manifolds 20 connected to the second intake ports (tumble ports) 12A to D. It is provided in each of the lower supply flow paths 42, 43, 44, 45, respectively. Since each of these fuel injection structures is basically configured in the same manner, the fuel injection structure of the first injector 51 and the first lower supply flow path 42 will be described below, and other description will be omitted.

As shown in FIG. 4, the first lower supply flow path 42 of the intake manifold 20 has a substantially circular cross-sectional shape of the flow path. Further, a boss portion 60 for attaching the first injector 51 is provided at a portion of the intake manifold 20 corresponding to the first lower supply flow path 42.

The boss portion 60 is formed in a substantially cylindrical shape having a through hole 61 having a substantially circular cross section communicating with the first lower supply flow path 42. The tip nozzle portion 51A of the first injector 51 is inserted into the through hole 61. An opening 62 that opens in a substantially elliptical shape is formed at the connection portion between the through hole 61 and the first lower supply flow path 42.

The boss portion 60 is provided so that the hole axis C2 of the through hole 61 (the injection axis of the first injector 51) is offset from the flow path axis C1 of the first lower supply flow path 42. Specifically, the downstream end of the inner peripheral surface 61A of the through hole 61 is connected in the tangential direction to the inner peripheral surface 42A of the first lower supply flow path 42.

That is, as shown by the broken line in FIG. 4, the fuel F is configured to be injected from the tip nozzle portion 51A of the first injector 51 toward the inside of the first lower supply flow path 42 from the tangential direction. As a result, the fuel F injected into the first lower supply flow path 42 is flown along the inner peripheral surface 42A of the first lower supply flow path 42.

Further, as shown in FIG. 5, the boss portion 60 is formed by the hole axis C2 of the through hole 61 (the injection axis of the first injector 51) and the flow path axis C1 of the first lower supply flow path 42. The angle θ is provided so as to be inclined toward the intake upstream side with respect to the flow path axis C1 of the first lower supply flow path 42 so that the angle θ becomes a predetermined acute angle on the intake upstream side.

That is, as shown by the broken line in FIG. 5, the fuel F is obliquely directed toward the intake upstream side from the tip nozzle portion 51A of the first injector 51 along the inner peripheral surface 42A of the first lower supply flow path 42. It is configured to be jetted. As a result, the fuel F injected into the first lower supply flow path 42 spirally swirls inside the first lower supply flow path 42 and further inside the second intake port (tumble port) 12A. However, it will be introduced into the cylinder C.

According to the fuel injection structure of the present embodiment described in detail above, the fuel is injected from the first injector 51 into the first lower supply flow path 42 in the tangential direction and diagonally toward the intake upstream side. Is configured to flow downstream while spirally swirling inside the first lower supply flow path 42 and the second intake port (tumble port) 12A. As a result, the mixing of fresh air and fuel can be effectively promoted, and the fuel efficiency can be reliably improved. Further, by swirling the fuel in a spiral shape, it is possible to promote mixing of fresh air and fuel in a short distance, and the first injector 51 is provided adjacent to the second intake port 12A on the layout. The degree of freedom in design and the miniaturization of the entire device can be achieved.

[Intake system structure]
Next, the details of the intake system structure according to the present embodiment will be described with reference to FIG. FIG. 6A is a schematic cross-sectional view showing a connection portion between the first upper supply flow path 32 of the intake manifold 20 and the first intake port (swirl port) 11A of the cylinder head CH according to the present embodiment. 6 (B) is a schematic cross-sectional view showing a connection portion between the first lower supply flow path 42 of the intake manifold 20 and the second intake port (tumble port) 12A of the cylinder head CH according to the present embodiment. Is. Since other connection parts are configured in substantially the same manner, detailed description thereof will be omitted.

As shown in FIG. 6A, a first flange portion 66 fixed to the side wall of the cylinder head CH is provided at the outlet end (downstream end) of the first upper supply flow path 32 of the intake manifold 20. .. Further, the flow path diameter (opening diameter of the first flange portion 66) of at least the outlet portion of the first upper supply flow path 32 is larger than the opening flow path diameter of the inlet portion (upstream end) of the first intake port (swirl port) 11A. It is formed to have a small diameter (and a smaller diameter than the flow path diameter of the first lower supply flow path 42 shown in FIG. 6B). That is, at the connection portion between the first upper supply flow path 32 and the first intake port 11A, the side wall 66A of the first flange portion 66 facing the inside of the first intake port 11A and the inner circumference of the upstream end of the first intake port 11A. The surface 66B forms a substantially annular step portion 67 that is recessed radially outward from the inner peripheral surface 32A of the first upper supply flow path 32.

As described above, when the step portion 67 is provided at the connection portion between the first upper supply flow path 32 and the first intake port 11A, the EGR gas flowing through the substantially central portion in the first upper supply flow path 32 and the fresh air The air-fuel mixture (EGR mixed intake air) M1 flows into the first intake port 11A substantially linearly, while the EGR mixed intake air M2 flowing along the inner peripheral surface 32A of the first upper supply flow path 32 has a step portion 67. It becomes a vortex that is drawn to the side. As a result, the energy (or flow velocity) of the EGR mixed intake air flowing in the first intake port 11A is reduced, and is introduced into the cylinder C from the first intake port 11A along the inner wall surface of the cylinder C. It is possible to effectively weaken the swirl of the swirling EGR mixed intake air.

As shown in FIG. 6B, a second flange portion 68 fixed to the side wall of the cylinder head CH is provided at the outlet end (downstream end) of the first lower supply flow path 42 of the intake manifold 20. There is. Further, as for the flow path diameter of the first lower supply flow path 42, at least the flow path diameter of the outlet portion (the opening diameter of the second flange portion 68) is the inlet portion (upstream end) of the second intake port (tumble port) 12A. The diameter is gradually increased toward the downstream side so as to have substantially the same diameter as the opening flow path diameter. That is, the connection portion between the first lower supply flow path 42 and the second intake port 12A is a smooth connection flow path having no stepped portion or the like.

When the first lower supply flow path 42 and the second intake port 12A are smoothly connected in this way, the fresh air I flowing in the first lower supply flow path 42 and the fuel F injected from the first injector 51 are connected. The air-fuel mixture (fuel mixed intake air) M with and is flowed in the second intake port 12A in a state where the decrease in energy (or flow velocity) is effectively suppressed. This makes it possible to effectively strengthen the tumble of the fuel mixed intake air introduced from the second intake port 12A to the substantially center of the cylinder C.

According to the intake system structure of the present embodiment described in detail above, the step portion 67 is passed through by providing the step portion 67 at the connection portion between the first upper supply flow path 32 and the first intake port (swirl port) 11A. The EGR mixed intake air in the first intake port 11A is configured to generate a vortex flow drawn toward the step portion 67 side. As a result, the energy of the EGR mixed intake air introduced into the cylinder C from the first intake port 11A is effectively reduced, and the excessive swirl of the EGR mixed intake air in the cylinder C is suppressed, and the EGR mixing is suppressed. It is possible to effectively prevent the intake air from flowing into the vicinity of the spark plugs P1 to 4 (center of the cylinder C) and further, misfire.

Further, by smoothly connecting the first lower supply flow path 42 and the second intake port (tumble port) 12A, the energy loss of the fuel mixed intake introduced into the cylinder C from the second intake port 12A is effective. It is configured to be deterred. This makes it possible to effectively concentrate the fuel-mixed intake air with a high fuel concentration near the center of the cylinder C where the spark plugs P1 to 4 are located, and while improving the combustion efficiency, the fuel efficiency performance is surely improved. be able to.

[others]
It should be noted that the present disclosure is not limited to the above-described embodiment, and can be appropriately modified and implemented without departing from the spirit of the present disclosure.

For example, in the above embodiment, the first distribution unit 21, the second distribution unit 30, and the third distribution unit 40 have been described as being formed as an integrated intake manifold 20, but these are two separate systems. It may be formed as an intake manifold. In this case, the intake pipe 70 may be branched into two systems and connected to each intake manifold. Further, the arrangement relationship between the first to fourth upper supply channels 32, 33, 34, 35 and the first to fourth lower supply channels 42, 43, 44, 45 is configured by exchanging the upper and lower sides thereof. You may.

Further, a step portion 67 is provided at the connection portion between the first upper supply flow path 32 and the first intake port (swirl port) 11A, and the first lower supply flow path 42 and the second intake port (tumble port) 12A are provided. Although it has been described that the connection portion of the above is smoothly formed, a step portion may be provided at the connection portion between the first lower supply flow path 42 and the second intake port 12A, depending on the purpose or the like. Further, although the step portion 67 has been described as being formed in an annular shape, it may be partially formed. Further, the step portion 67 can be formed by making the hole diameter of the gasket interposed between the intake manifold 20 and the first intake port 11A smaller than the opening diameter of the first intake port 11A.

Further, although the engine E has been described as using natural gas as a fuel, the engine E is not limited to this, and can be widely applied to other internal combustion engines such as a gasoline engine.

E Engine CH Cylinder Head C Cylinder (Cylinder)
P1-4 Spark plug 10 Engine body 11A-D 1st intake port (swirl port)
12A to D 2nd intake port (tumble port)
13 Intake valve 16 Exhaust port (exhaust system)
17 Exhaust valve 20 Intake manifold 21 1st distribution section 22 Open flange section 23 Upper branch flow path 24 Lower branch flow path 30 2nd distribution section (1st intake pipeline)
31 Upper distribution flow path 32 First upper supply flow path 33 Second upper supply flow path 34 Third upper supply flow path 35 Fourth upper supply flow path 40 Third distribution section (second intake line)
41 Lower flow path 42 1st lower supply channel 43 2nd lower supply channel 44 3rd lower supply channel 45 4th lower supply channel 51 1st injector 52 2nd injector 53 3rd injector 54 4th injector 60 Boss part 61 Through hole 67 Step part 70 Intake pipe 90 Exhaust manifold (exhaust system)
91 Exhaust pipe (exhaust system)
94 EGR equipment 95 EGR piping

Claims (5)

An intake manifold of an internal combustion engine having a first intake port and a second intake port for introducing intake air into a cylinder.
A first intake line connected to the first intake port and introducing intake air into the first intake port,
A second intake line connected to the second intake port and introducing intake air into the second intake port is provided.
The opening diameter of at least the outlet portion of the first intake pipe is formed to be smaller than the opening diameter of at least the inlet portion of the first intake port, and the connection portion between the first intake pipe and the first intake port is formed. A step is formed in
The first intake port is a swirl port, and the second intake port is a tumble port.
The intake manifold of an internal combustion engine is characterized by that. The intake manifold of an internal combustion engine according to claim 1, wherein the opening diameter of at least the outlet portion of the second intake pipe is formed to be the same as the opening diameter of at least the inlet portion of the second intake port. An exhaust gas recirculation flow path for recirculating exhaust from the exhaust system of the internal combustion engine to the intake system is connected to the first intake pipeline, and the intake air of the second intake pipeline is connected to the second intake pipeline. The intake manifold of an internal combustion engine according to claim 1 or 2, wherein an injector for injecting fuel is provided in the flow path. The intake manifold of an internal combustion engine according to any one of claims 1 to 3, wherein the first intake pipe and the second intake pipe are formed of an integrated intake manifold. The intake manifold of an internal combustion engine according to claim 3 , wherein the injector injects natural gas as the fuel.

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