Intake device for internal combustion engine

Abstract

The present invention relates to an intake apparatus of an internal combustion engine, the intake apparatus of the internal combustion engine including: a main pipe having an upstream end forming a suction port and a downstream end configured to be connected to an intake port of a main body of the internal combustion engine; a compressor of a supercharger provided in the main pipe; an intercooler provided at a position downstream of the compressor in the main pipe and including a cooling portion, an upstream header provided upstream of the cooling portion, and a downstream header provided downstream of the cooling portion; a throttle valve arranged at a position downstream of the intercooler in the main pipe; a bypass pipe having a first end and a second end, the bypass pipe being connected to a portion of the main pipe between the cooling portion and the throttle valve; and a water collector tank provided in the bypass pipe and configured to collect condensed water.

Description

Technical Field

[0001] The present invention relates to an air intake device of an internal combustion engine. Background Art

[0002] Conventionally, an intake device for an internal combustion engine includes an intake pipe communicating with a combustion chamber, a compressor of a supercharger (turbocharger) disposed in the intake pipe, an intercooler disposed in the intake pipe downstream of the compressor, a throttle valve disposed in the intake pipe downstream of the intercooler, and an intake manifold disposed in the intake pipe downstream of the throttle valve (e.g., JP2014-169654A). Fuel injected by a fuel injection device is combusted together with air introduced into the combustion chamber via the intake pipe.

[0003] The intake device disclosed in JP2014-169654A also includes a condensate drain device, which includes a water tank. The water tank has the function of storing condensate generated by cooling the air in the intercooler. This reduces the risk of intake pipe corrosion caused by condensate. This condensate drain device includes: a supply pipe, one end of which is connected to the water tank and the other end is connected to the portion of the intake pipe located downstream of the intercooler and upstream of the throttle valve; and a drain pipe, one end of which is connected to the water tank and the other end is connected to the intake manifold. Because the pressure in the intake manifold is negative, the condensate stored in the water tank is discharged into the intake manifold via the drain pipe.

[0004] Prior art literature

[0005] Patent Literature

[0006] In the intake device disclosed in JP2014-169654A, when the internal combustion engine is idling, for example, the throttle valve closes the intake passage, which increases the negative pressure in the intake manifold. As a result, a large amount of condensed water is introduced into the intake manifold within a predetermined period of time while idling, potentially causing misfire of the fuel in the combustion chamber. Summary of the Invention

[0007] In view of the above background, a main object of the present invention is to provide an intake device for an internal combustion engine that can prevent misfire when the internal combustion engine is idling.

[0008] In order to achieve the above-mentioned purpose, one aspect of the present invention provides an intake device 4 of an internal combustion engine 1, which includes: a main pipe 14, the main pipe having an upstream end forming a suction port 13 and a downstream end configured to be connected to the intake port 10 of the internal combustion engine body 3; a compressor 18 of a supercharger 17 arranged in the main pipe; an intercooler 19, the intercooler being arranged in the main pipe at a position downstream of the compressor and including a cooling portion 26, an upstream collector 27 arranged upstream of the cooling portion, and a downstream collector 28 arranged downstream of the cooling portion; a throttle valve 20, the throttle valve being arranged in the main pipe at a position downstream of the intercooler; a bypass pipe 30, the bypass pipe having a first end 30A and a second end 30B, the bypass pipe being connected to a portion of the main pipe located between the cooling portion and the throttle valve; and a water collecting tank 31, the water collecting tank being arranged in the bypass pipe and configured to collect condensed water.

[0009] According to this configuration, since the first and second ends of the bypass pipe, which includes the water header tank, are connected to the portion of the main pipe located downstream of the intercooler and upstream of the throttle valve, a large pressure difference is unlikely to be generated between the first end of the bypass pipe and the water header tank even when the internal combustion engine is idling. Therefore, it is unlikely that a large amount of water will be discharged from the water header tank every predetermined time, and the intake device can prevent misfire of the internal combustion engine when idling.

[0010] Preferably, the air intake device further includes a resonator 43 connected to the bypass pipe.

[0011] According to this configuration, noise generated in the air intake device can be suppressed.

[0012] Preferably, the resonator is connected to a portion of the bypass pipe located downstream of the water collecting tank.

[0013] According to this configuration, the portion of the bypass pipe connected to the resonator can be used as a part of the resonator, thereby improving the degree of freedom in designing the resonator.

[0014] Preferably, the bypass pipe includes: a first part 32, the first part including the first end and connected to the inlet of the water collecting tank; and a second part 33, the second part including the second end and extending upward from the outlet of the water collecting tank, and the resonator includes: a main body 44, the main body defining a volume chamber and being arranged to be higher than the water collecting tank; and a connecting pipe part 45, the connecting pipe part extending downward from the bottom surface of the main body and connected to the second part.

[0015] According to this configuration, since the resonator is arranged above the water collecting tank and the communication pipe portion extends downward from the bottom surface of the main body, condensed water in the resonator can be discharged to the bypass pipe.

[0016] Preferably, the cooling portion of the intercooler includes a plurality of heat dissipation pipes 29 extending along a first axial direction, the main pipe includes a middle portion 15 extending from the downstream collector in a direction perpendicular to the first axial direction, and the first portion of the bypass pipe is connected to the downstream collector and extends along the first axial direction.

[0017] According to this configuration, the condensed water is easily guided to the inside of the bypass pipe due to inertial force.

[0018] Preferably, the cooling portion, the downstream header, and the first portion of the bypass pipe extend in a lateral direction of a vehicle on which the internal combustion engine is mounted, and the intermediate portion extends upward from the downstream header relative to the vehicle.

[0019] According to this configuration, the condensed water generated by the intercooler is more easily guided to the inside of the bypass pipe.

[0020] Preferably, the second portion of the bypass pipe has a smaller cross-sectional area than a cross-sectional area of ​​the middle portion of the main pipe.

[0021] According to this configuration, the sound absorbing effect of the resonator is improved.

[0022] Preferably, the water collecting tank includes: a shell 35, which is cylindrical and has a central axis extending in the up-down direction; an inlet pipe 36, which extends from the upper part of the outer peripheral surface of the shell in a tangential direction; an outlet pipe 37, which extends from the upper end of the shell along the central axis toward the inside of the shell; and a partition wall 41, which is connected to the outlet pipe and the inner surface of the shell, the inlet pipe is connected to the first part, the upper end of the outlet pipe is connected to the second part, and the lower end of the outlet pipe is arranged so that a predetermined gap is defined between the lower end of the outlet pipe and the bottom surface of the shell.

[0023] According to this configuration, the condensed water (and air) guided into the water collection tank hits the partition wall, thereby effectively separating the condensed water and air. In addition, since the outlet pipe opens downward, the condensed water can be discharged to the middle portion according to the magnitude of the negative pressure.

[0024] Preferably, a lower edge of an open end of the inlet pipe on the housing side is arranged to be higher than a lower end of the outlet pipe.

[0025] According to this configuration, the liquid level of the condensed water is maintained lower than the open end of the inlet pipe on the case side, so that backflow of the condensed water can be prevented.

[0026] According to this aspect of the present invention, there is provided an intake apparatus for an internal combustion engine that can prevent misfire when the internal combustion engine is idling. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a front view of an internal combustion engine provided with an air intake device according to one embodiment of the present invention;

[0028] Figure 2 It is a three-dimensional diagram of the air intake device;

[0029] Figure 3 It is a three-dimensional diagram of the water collecting tank of the air intake device;

[0030] Figure 4 It is along Figure 3 A cross-sectional view of the water collecting tank taken along line IV-IV;

[0031] Figure 5 It is along Figure 3 A cross-sectional view of the water collecting tank taken along line VV in FIG; and

[0032] Figure 6 is a graph showing the relationship between the intake sound attenuation amount and the intake sound frequency in the intake device. DETAILED DESCRIPTION

[0033] Hereinafter, an embodiment of the air intake device according to the present invention applied to an automobile internal combustion engine will be described in detail with reference to the accompanying drawings. The internal combustion engine may be a known engine such as a gasoline engine, a diesel engine, a homogeneous charge compression ignition (HCCI) engine, etc.

[0034] In this embodiment, if Figure 1 As shown in the figure, the internal combustion engine 1 includes an internal combustion engine body 3 in which a cylinder (not shown in the figure) is formed, an intake device 4 for supplying intake air to the internal combustion engine body 3, and an exhaust device (not shown in the figure) for discharging exhaust gas generated in the internal combustion engine body 3. The cylinder of the internal combustion engine body 3 receives a piston (not shown in the figure) therein so that the piston can reciprocate. The upper end portion of the cylinder forms a combustion chamber (not shown in the figure). The internal combustion engine body 3 includes an intake port (not shown in the figure) and an exhaust port (not shown in the figure) both extending from the combustion chamber to the outer surface of the internal combustion engine body 3.

[0035] The intake system 4 includes a main pipe 14 having an upstream end forming the intake port 13 and a downstream end connected to the intake port of the internal combustion engine body 3. Main pipe 14 defines an intake passage extending from the intake port 13 to the intake port. The intake passage is provided with, in order from the upstream side, an air filter 16, a compressor 18 of a turbocharger 17 serving as a supercharger, an intercooler 19, a throttle valve 20, and an intermediate manifold 21. Air is drawn in through the intake port 13, and after foreign matter is removed by the air filter 16, it is pressurized by the compressor 18. The air is then cooled in the intercooler 19, and after its flow rate is adjusted by the throttle valve 20, it is supplied to the combustion chamber.

[0036] The exhaust system includes an exhaust passage communicating with the air intake. The exhaust passage is provided with, in order from the upstream side, a turbine of the turbocharger 17, a catalytic converter, a muffler, and an exhaust outlet (all of which are not shown). Exhaust gas (combustion gas) generated by combustion in the combustion chamber passes through the turbine, is then purified by the catalytic converter, passes through the muffler, and is released into the atmosphere through the exhaust outlet.

[0037] The turbocharger 17 is composed of a compressor 18 and a turbine. The compressor 18 includes a hollow compressor housing serving as an outer shell and a compressor wheel (compressor impeller) rotatably received in the compressor housing. The compressor housing has a compressor inlet connected to a portion of the main pipe 14 located downstream of the air filter 16 and a compressor outlet connected to a portion of the main pipe 14 located upstream of the intercooler 19.

[0038] The intercooler 19 includes a cooling section 26, an upstream header 27 positioned upstream of the cooling section 26, and a downstream header 28 positioned downstream of the cooling section 26. The cooling section 26 includes a plurality of heat dissipation pipes 29 extending along a first axis. In this embodiment, the first axis extends transversely of the vehicle in which the internal combustion engine 1 is mounted. Furthermore, the upstream header 27, the cooling section 26, and the downstream header 28 also extend transversely of the vehicle. The intercooler 19 is positioned at the lower front portion of the vehicle.

[0039] The upstream header 27 is connected to the downstream end of the portion of the main pipe 14 located between the compressor 18 and the intercooler 19. The downstream header 28 is connected to the upstream end of the portion of the main pipe 14 located between the intercooler 19 and the throttle valve 20 (hereinafter, this portion of the main pipe 14 will be referred to as the intermediate portion 15). The intermediate portion 15 extends in a direction perpendicular to the first axis direction. In this embodiment, the intermediate portion 15 extends upward from the downstream header 28 relative to the vehicle.

[0040] A bypass pipe 30 having a first end 30A and a second end 30B is connected to a portion of the main pipe 14 between the cooling portion 26 and the throttle valve 20. In this embodiment, the bypass pipe 30 is connected to the intermediate portion 15 of the main pipe 14 and the downstream header 28.

[0041] The bypass pipe 30 includes a first portion 32 including a first end 30A connected to the inlet of the header tank 31 and a second portion 33 including a second end 30B extending upward from the outlet of the header tank 31. The header tank 31 has a function of storing condensed water generated by the air cooled by the intercooler 19.

[0042] The first end 30A (first portion 32) of the bypass pipe 30 is connected to the downstream header 28 of the intercooler 19. In another embodiment, the first portion 32 may be connected to the intermediate portion 15. The first portion 32 extends along the first axis. That is, in this embodiment, the first portion 32 extends in the transverse direction of the vehicle in which the internal combustion engine 1 is installed.

[0043] The second end 30B (second portion 33) of the bypass pipe 30 is connected to a substantially central portion of the intermediate portion 15 of the main pipe 14 in the vertical direction. Figure 2 As shown in FIG, the second part 33 includes: an outlet pipe upper portion 40 (see FIG) from the water collecting tank 31; Figure 3 and Figure 4 ) upstream portion 33A extending upward, curved portion 33B extending from the distal end of upstream portion 33A toward intermediate portion 15, and downstream portion 33C extending substantially transversely from the distal end of curved portion 33B. Upstream portion 33A extends substantially parallel to intermediate portion 15 of main pipe 14. The distal end of downstream portion 33C is connected to intermediate portion 15. Downstream portion 33C extends substantially transversely. Second portion 33 has a smaller cross-sectional area than that of intermediate portion 15 of main pipe 14. In this embodiment, upstream portion 33A and curved portion 33B have smaller cross-sectional areas than that of intermediate portion 15.

[0044] like Figure 3 and Figure 4 As shown in the figure, the water collecting tank 31 includes: a shell 35 which is cylindrical and has a central axis extending in the up-down direction, an inlet pipe 36 extending in a tangential direction from the upper part of the outer peripheral surface of the shell 35, and an outlet pipe 37 extending from the upper end of the shell 35 along the central axis toward the inside of the shell 35.

[0045] The end of the inlet pipe 36 defines the inlet of the water collecting tank 31. The inlet pipe 36 is connected to the first portion 32 of the bypass pipe 30. Figure 5The outlet pipe 37 includes a lower portion 39 extending downward (toward the interior of the housing 35) from the upper end of the housing 35, and an upper portion 40 extending upward from the upper end of the housing 35. Both the lower portion 39 and the upper portion 40 extend vertically along the central axis. The upper end of the upper portion 40 defines the outlet of the water collecting tank 31. The upper end of the upper portion 40 is connected to the second portion 33 (upstream portion 33A) of the bypass pipe 30.

[0046] The lower edge of the open end of the inlet pipe 36 on the housing 35 side is arranged higher than the lower end of the outlet pipe 37. Figure 5 As shown in FIG, the outer diameter of the inlet pipe 36 is substantially the same as the distance between the inner surface of the housing 35 and the outer surface of the lower portion 39 of the outlet pipe. Figure 4 , the lower end of the outlet pipe lower portion 39 is arranged so that a predetermined gap is defined between the lower end of the outlet pipe lower portion 39 and the bottom surface of the housing 35. The inner diameter of the outlet pipe lower portion 39 gradually increases downward. In another embodiment, the outlet pipe lower portion 39 may have a constant inner diameter.

[0047] like Figure 5 As shown in , the water collecting tank 31 further includes a partition wall 41 connected to the inner surface of the outlet pipe 37 and the shell 35. The partition wall 41 extends substantially parallel to the inlet pipe 36. The partition wall 41 extends in the up-down direction, and the upper end of the partition wall 41 is connected to the upper wall of the shell 35. Preferably, the partition wall 41 and the base end of the inlet pipe 36 are smoothly connected. In this way, the inner surface of the inlet pipe 36, the inner surface of the shell 35, the outer surface of the outlet pipe lower portion 39 and the partition wall 41 define a flow passage 42. In this embodiment, as shown in Figure 4 As shown in FIG, the lower end of the partition wall 41 and the lower end of the outlet pipe 37 are located at substantially the same height. In another embodiment, the lower end of the partition wall 41 may be arranged to be lower or higher than the lower end of the outlet pipe 37.

[0048] In addition, if Figure 1 and Figure 2 As shown in FIG, the resonator 43 is connected to the bypass pipe 30. In the present embodiment, the resonator 43 is connected to a portion of the bypass pipe 30 that is located downstream of the water collecting tank 31, that is, to the second portion 33 of the bypass pipe 30. More specifically, the resonator 43 is connected to the bent portion 33B of the bypass pipe 30. The resonator 43 includes a main body 44 that defines a volume chamber and is arranged to be higher than the water collecting tank 31, and a connecting pipe portion 45 that extends downward from the bottom surface of the main body 44 and is connected to the second portion 33. The connecting pipe portion 45 is connected to the bent portion 33B of the bypass pipe 30. The connecting pipe portion 45 has a cross-sectional area that is substantially the same as that of the second portion 33. In the present embodiment, the connecting pipe portion 45 has a cross-sectional area that is substantially the same as that of the upstream portion 33A and the bent portion 33B.

[0049] Next, the operating modes of the internal combustion engine 1 and the intake device 4 provided therein will be described. Air drawn in through the intake port 13, after having foreign matter removed by the air filter 16, is introduced into the compressor 18 and pressurized therein. The air is then introduced into the cooling section 26 of the intercooler 19 via the upstream header 27 and cooled there. At this point, some moisture in the air condenses, forming condensed water. The air and condensed water are then directed via the downstream header 28 to the first portion 32 of the bypass pipe 30 or the intermediate portion 15 of the main pipe 14.

[0050] In the present embodiment, the cooling portion 26, the downstream header 28, and the first portion 32 extend in the lateral direction, and the middle portion 15 extends upward from the downstream header 28. Therefore, due to inertial force, condensed water having a relatively large mass may be guided to the first portion 32 of the bypass duct 30, while air having a relatively small mass may be guided to the middle portion 15.

[0051] like Figure 5 As shown in , the condensed water (and part of the air) guided to the first part 32 flows through the flow passage 42 in the shell 35 and then hits the partition wall 41. The condensed water flows downward along the partition wall 41 and is stored in the lower part of the shell 35 to form a storage part 50. Therefore, the air intake device 4 according to the embodiment of the present invention can effectively separate the condensed water and the air, and can effectively store the condensed water in the water collecting tank 31 (shell 35). In addition, since the lower edge of the open end of the inlet pipe 36 on the shell 35 side is arranged to be higher than the lower end of the outlet pipe 37, the liquid level 51 of the storage part 50 is maintained lower than the open end of the inlet pipe 36 on the shell 35 side. Therefore, the backflow of the condensed water can be prevented.

[0052] Because the pressure in bypass pipe 30 on the second end 30B side becomes negative relative to the pressure in water header tank 31 due to the downward stroke of the piston of engine body 3, the condensed water stored in storage portion 50 is drawn from liquid surface 51 into the lower end of outlet pipe lower portion 39 while being captured by the airflow in housing 35. As the amount of condensed water introduced into housing 35 increases and the distance between liquid surface 51 and the lower end of outlet pipe lower portion 39 becomes relatively shorter, the amount of condensed water drawn from storage portion 50 increases. On the other hand, as the distance between liquid surface 51 and the lower end of outlet pipe lower portion 39 becomes relatively longer, the amount of condensed water drawn from storage portion 50 decreases. Thus, the distance between the upper end (water surface) of storage portion 50 and the lower end of outlet pipe lower portion 39 is maintained at a substantially constant value.

[0053] like Figure 1 and Figure 2As shown in FIG, condensed water drawn from storage portion 50 flows through outlet pipe 37 and second portion 33 to merge into middle portion 15 of main pipe 14. At this point, some of the condensed water intrudes into communication pipe portion 45 of resonator 43. In this embodiment, since resonator 43 is arranged above water collection tank 31 and communication pipe portion 45 extends downward from the bottom surface of main body 44, even if condensed water intrudes into communication pipe portion 45, it is guided downward by gravity, and thus is less likely to remain in resonator 43. Consequently, the risk of corrosion of resonator 43 caused by condensed water is reduced.

[0054] Incidentally, during operation of the internal combustion engine 1, when the opening degree of the throttle valve 20 decreases in response to a deceleration operation such as releasing the accelerator pedal, the piston of the internal combustion engine body 3 reciprocates under the condition of a reduced intake air supply, thereby increasing the magnitude of the negative pressure in the portion of the main pipe 14 downstream of the throttle valve 20. In this embodiment, the first end 30A and the second end 30B of the bypass pipe 30 are connected to the portion of the main pipe 14 downstream of the intercooler 19 and upstream of the throttle valve 20. Therefore, even when the internal combustion engine 1 is idling and the magnitude of the negative pressure in the portion of the main pipe 14 downstream of the throttle valve 20 increases, a large amount of water can be prevented from being discharged from the header tank 31 every predetermined period of time. Consequently, misfires can be prevented while the internal combustion engine 1 is idling.

[0055] On the other hand, at high rotational speeds, the piston in the combustion chamber reciprocates with the throttle valve 20 open, causing a significant negative pressure on the second end 30B side of the bypass pipe 30 relative to the pressure in the header tank 31. As a result, a relatively large amount of condensed water is guided from the interior of the header tank 31. However, at this time, the temperature in the combustion chamber remains relatively high, allowing combustion to proceed without misfiring in the internal combustion engine 1.

[0056] Next, we will refer to Figure 6 The effects of resonator 43 in this embodiment will now be described. Resonator 43 is a member for reducing intake sound generated in intake device 4 by applying the principle of Helmholtz resonance. Due to fluid friction in communication pipe portion 45 and reflection of the intake sound by main body 44, the intake sound caused by the pulsation of intake air flowing through main pipe 14 is converted from acoustic vibration energy into heat energy.

[0057] Figure 6Graph showing the relationship between the intake sound attenuation amount (vertical axis) and the intake sound frequency (horizontal axis) generated during operation of the internal combustion engine 1. In this graph, the solid line represents the measurement results for the intake device 4 including the resonator 43 and the bypass pipe 30 according to the present embodiment, the dotted line represents the measurement results for the intake device including no bypass pipe but including the resonator in the intermediate portion 15 whose communicating pipe portion is connected to the main pipe 14, and the single-dot chain line represents the measurement results for the intake device including neither the resonator nor the bypass pipe.

[0058] In the intake device shown by the dashed line, the attenuation of intake sound reaches a peak at approximately 120 Hz and significantly decreases at approximately 160 Hz. In the intake device shown by the single-dash line, there is no peak in the attenuation, but the attenuation of intake sound does decrease significantly at approximately 160 Hz. In contrast, in the intake device 4 according to the present embodiment, shown by the solid line, the attenuation of intake sound reaches a peak at approximately 135 Hz. Furthermore, the attenuation of intake sound does not decrease significantly at approximately 160 Hz.

[0059] The above results demonstrate that the intake device 4 of the present embodiment, including the resonator 43 and the bypass duct 30, can exhibit sufficient sound absorption. Furthermore, because the connecting duct portion 45 of the resonator 43 is connected to the second portion 33 (the bent portion 33B) of the bypass duct 30, the second portion 33 of the bypass duct 30 can exhibit a function similar to that of the connecting duct portion 45 of the resonator 43. Therefore, the intake device 4 of the present embodiment can absorb intake sound in a desired frequency band while maintaining a relatively short length of the connecting duct portion 45, thereby enabling the resonator 43 to be compactly dimensioned.

[0060] While specific embodiments of the present invention have been described above, the present invention is not limited to the aforementioned embodiments and may be modified or altered in various ways. For example, the cross-sectional areas of the intermediate portion 15, the second portion 33, and the communicating pipe portion 45 may be determined to be appropriate for the resonator 43 to effectively attenuate intake air sound within a desired frequency band. Furthermore, while the communicating pipe portion 45 is connected to the curved portion 33B of the second portion 33 in the aforementioned embodiment, in another embodiment, the communicating pipe portion 45 may be connected to either the upstream portion 33A or the downstream portion 33C.

Claims

1. An air intake device for an internal combustion engine, comprising: a main pipe having an upstream end forming a suction port and a downstream end configured to be connected to an air intake port of the internal combustion engine body; a compressor of a supercharger disposed in the main pipe; an intercooler provided in the main pipe at a position downstream of the compressor and including a cooling portion, an upstream header provided upstream of the cooling portion, and a downstream header provided downstream of the cooled portion; a throttle valve disposed in the main pipe at a position downstream of the intercooler; a bypass pipe having a first end and a second end, the bypass pipe being connected to a portion of the main pipe between the cooling portion and the throttle valve; a water collecting tank disposed in the bypass pipe and configured to collect condensed water; as well as The resonator connected to the bypass pipe, wherein the resonator is connected to a portion of the bypass pipe located downstream of the water collecting tank, Wherein, the bypass pipe comprises: a first portion including the first end and connected to an inlet of the header tank; and a second portion including the second end and extending upwardly from the outlet of the header tank, and The resonator comprises: a main body defining a volume chamber and arranged higher than the water collecting tank; and A communication pipe portion extends downward from a bottom surface of the main body and is connected to the second portion.

2. The air intake device for an internal combustion engine according to claim 1, wherein: The cooling portion of the intercooler includes a plurality of heat dissipation pipes extending along a first axis direction, The main pipe includes a middle portion extending from the downstream header in a direction perpendicular to the first axis direction, and The first portion of the bypass pipe is connected to the downstream header and extends along the first axis direction.

3. The air intake device for an internal combustion engine according to claim 2, wherein: The second portion of the bypass pipe has a smaller cross-sectional area than the middle portion of the main pipe.

4. The air intake device for an internal combustion engine according to claim 2 or 3, wherein: The cooling portion, the downstream header, and the first portion of the bypass pipe extend in a lateral direction of a vehicle on which the internal combustion engine is mounted, and The intermediate portion extends upwardly from the downstream collector relative to the vehicle.

5. The air intake device for an internal combustion engine according to any one of claims 1 to 3, wherein: The water collecting tank comprises: a housing, the housing being cylindrical and having a central axis extending in an up-down direction; an inlet pipe extending tangentially from an upper portion of an outer peripheral surface of the housing; an outlet pipe extending from an upper end of the housing along the central axis toward an interior of the housing; and a partition wall connected to the outlet pipe and an inner surface of the housing, The inlet pipe is connected to the first portion, The upper end of the outlet pipe is connected to the second portion, and The lower end of the outlet pipe is arranged such that a predetermined gap is defined between the lower end of the outlet pipe and a bottom surface of the housing.

6. The air intake device for an internal combustion engine according to claim 5, wherein: A lower edge of an open end of the inlet pipe on the housing side is arranged higher than a lower end of the outlet pipe.

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