Intake pipe structure

Abstract

To provide an intake pipe structure which stabilizes intake airflow in a transient state while making a structure of an engine compact.SOLUTION: An intake pipe structure includes: a throttle valve disposed at a position located at the intake air downstream side of a compressor and the intake air upstream side of an intercooler; and an extension part 30 which is provided so as to be arranged along a first intermediate intake pipe 11, a portion between the compressor and the throttle valve in an intake pipe 10, and expand from the first intermediate intake pipe 11, and expands the cubic capacity of the first intermediate intake pipe 11. The first intermediate intake pipe 11 has a bending part 11a, and the extension part 30 is formed at the inner arc side of the bending part 11a. A communication hole 33 communicating with the extension part 30 is provided in a peeling area R where an intake airflow peels from a wall surface, in the first intermediate intake pipe 11.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The technology disclosed herein belongs to the technical field relating to intake pipe structures. [Background technology]

[0002] 2. Description of the Related Art A structure in which a chamber is attached to an intake pipe in order to smooth the flow of intake air through the intake pipe has been conventionally known.

[0003] For example, in the intake pipe structure described in Patent Document 1, an intake chamber is provided midway through an intake duct main body that communicates with an intake manifold, and a bent portion is formed in the intake duct main body that is inserted into the intake chamber, and multiple communication holes that open into the intake chamber are drilled in the area excluding the outer portion of the bent portion facing the intake chamber.

[0004] In the intake pipe structure of Patent Document 1, intake air is discharged from a communication hole into an intake chamber in the medium to low speed range where the intake air flow speed is relatively slow, thereby reducing intake pulsation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-130065 A Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, in order to maximize engine output while keeping the engine compact, engines are sometimes equipped with turbochargers. When an engine is equipped with a turbocharger, it is common to provide an intercooler in the intake pipe downstream of the turbocharger compressor. In this case, when the throttle valve is provided downstream of the intercooler, the volume of the intake pipe from the compressor to the throttle valve can be increased to a certain extent, but when the throttle valve is provided upstream of the intercooler, the volume of the intake pipe from the compressor to the throttle valve becomes smaller.

[0007] If the volume of the intake pipe from the compressor to the throttle valve is small, when the throttle valve is slightly closed, the pressure in the intake pipe from the compressor to the throttle valve becomes high. Therefore, when the throttle valve opens during engine transients, high-pressure intake air may suddenly flow into the cylinder, causing hunting. In order to suppress hunting, a configuration has been considered in which the intake air downstream of the compressor is bled, but in that case, the amount of intake air in the intake pipe from the compressor to the throttle valve is reduced, making it difficult to generate a smooth intake flow during engine transients.

[0008] In particular, if there is a bend in the intake pipe from the compressor to the throttle valve, the intake air will separate at the bend, causing the intake flow to become turbulent, making control difficult during transients. As a result, hunting will easily occur.

[0009] In Patent Document 1, a chamber is provided in a portion of the intake pipe upstream of the throttle valve, but no consideration is given to the positional relationship with a turbocharger or an intercooler. Even if a chamber as described in Patent Document 1 were placed in the portion of the intake pipe from the compressor to the throttle valve, the chamber in Patent Document 1 would need to cover the intake pipe, which would inevitably increase the size of the entire engine and make it difficult to achieve a compact configuration.

[0010] The technology disclosed herein has been made in consideration of the above points, and its purpose is to stabilize the intake flow during transients while making the engine configuration compact. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention is disclosed 1. The technology is directed to an intake pipe structure of an engine having a turbocharger compressor and an intercooler arranged downstream of the compressor in the intake air direction, and is directed to a turbocharger arranged downstream of the compressor and upstream of the intercooler in the intake air direction. Tas and an expansion portion that is provided along an intermediate intake pipe, which is a portion of the intake pipe between the compressor and the throttle valve, and that expands the volume of the intermediate intake pipe, the intermediate intake pipe having a curved portion and the expansion portion being formed on the inner arc side of the curved portion, and a first communication hole that communicates with the expansion portion is provided in a separation region of the intermediate intake pipe where the intake flow separates from the wall surface. and the first communication hole is formed in the curved portion. The structure is as follows.

[0012] With this configuration, the throttle valve is located downstream of the compressor and upstream of the intercooler, so the intermediate intake pipe itself, which is the portion of the intake pipe between the compressor and the throttle valve, has a relatively small volume. By providing an expansion section, the volume of the intermediate intake pipe can be increased by the amount of the expansion section. This makes it possible to prevent high pressure in the intermediate intake pipe as much as possible, even when the throttle valve is slightly closed.

[0013] In addition, during engine transients, the intake air is sucked out from the extension section to suppress turbulence in the intake air flow and generate a smooth intake air flow. In particular, since the first communication hole is provided in the separation area where the intake air flow separates from the wall surface, the intake air can be efficiently sucked out from the extension section by utilizing the negative pressure generated by the separation of the intake air.

[0014] Furthermore, since the expansion portion is provided on the inner arc side of the curved portion of the intermediate intake pipe, it is possible to minimize the increase in size of the engine due to the expansion portion.

[0015] Therefore, the engine configuration can be made compact while stabilizing the intake flow during transients.

[0016] In order to solve the above problem, the second technology disclosed herein is directed to an intake pipe structure of an engine having a turbocharger compressor and an intercooler arranged downstream of the compressor in the intake direction, and includes a throttle valve arranged in the intake pipe at a position downstream of the compressor and upstream of the intercooler in the intake direction, and an expansion section arranged to extend along an intermediate intake pipe, which is a portion of the intake pipe between the compressor and the throttle valve, and to bulge from the intermediate intake pipe, thereby expanding a volume of the intermediate intake pipe, the intermediate intake pipe having a curved section and a straight section extending linearly from the downstream end of the curved section, the expansion section being formed on the inner arc side of the curved section and along the curved section and the straight section, a first communication hole communicating with the expansion section is provided in a separation region in the intermediate intake pipe where the intake flow separates from the wall surface, and the first communication hole is formed in a portion of the straight section in the vicinity of the curved section.

[0017] With this configuration, because the straight section extends from the downstream end of the curved section, separation of the intake air is particularly likely to occur near the boundary between the curved section and the straight section. In contrast, because the first communication hole is formed in the straight section near the curved section, the intake air can be efficiently sucked out of the expansion section by utilizing the negative pressure caused by the separation of the intake air. This makes it possible to further stabilize the intake air flow during a transition.

[0018] In the embodiment, a second communication hole communicating with the extension portion may be provided at a position on the straight portion away from the first communication hole on the intake downstream side.

[0019] According to this configuration, since the intake air can also be drawn out from the second communication hole, the intake air flow during a transition can be made more stable.

[0020] In the intake pipe structure, a plurality of ribs may be provided within the extension portion, the ribs extending in a direction intersecting with the longitudinal direction of the extension portion.

[0021] According to this configuration, it is possible to suppress the membrane vibration that occurs when air is sucked out from the extension portion, thereby suppressing the generation of radiated sound and increasing the rigidity of the extension portion.

[0022] In the intake pipe structure, the expansion portion may be configured to be composed of a main body portion that is formed integrally with the intermediate intake pipe and has an opening on the side opposite the intermediate intake pipe, and a cover portion that is formed separately from the main body portion and closes the opening of the main body portion.

[0023] According to this configuration, the volume of the extension part can be easily changed by changing the volume of the lid part in accordance with the configuration of the engine. As a result, it is possible to stabilize the intake flow during a transition while making the configuration of various engines compact.

[0024] In the intake pipe structure, the compressor is provided on the exhaust side at the top of the engine, the throttle valve is provided on the intake side at the top of the engine, the intermediate intake pipe is provided on the upper side of the engine body so as to cross the engine body in a planar view, the curved portion is curved in the cylinder row direction of the engine body, and the extension portion is provided on the inner arc side of the curved portion so as to bulge from the intermediate intake pipe in the cylinder row direction.

[0025] That is, since both the compressor and the throttle valve are provided on the upper part of the engine and the intermediate intake pipe is arranged to cross the engine body, the length of the intermediate intake pipe is short. This makes the engine configuration more compact, but the volume of the intermediate intake pipe is particularly likely to be small. Therefore, by providing the extension part, the effect of stabilizing the intake flow during engine transients can be appropriately achieved.

[0026] In addition, because the bent portion is bent in the cylinder row direction and the expanded portion bulges out from the intermediate intake pipe in the cylinder row direction, the engine is appropriately prevented from expanding in the height direction, thereby making the engine configuration more compact. Effect of the Invention

[0027] As described above, according to the technology disclosed herein, it is possible to stabilize the intake flow during a transient state while making the engine configuration compact. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a schematic diagram of an engine having an intake pipe structure according to an exemplary embodiment. [Diagram 2] FIG. 2 is a perspective view of the engine. [Diagram 3] FIG. 3 is a plan view of the engine. [Figure 4] FIG. 4 is a plan view of the intake pipe including the extension portion. [Diagram 5] FIG. 5 is a cross-sectional view taken along a horizontal plane passing through the extension portion. [Figure 6] FIG. 6 is a schematic diagram showing the flow of intake air, where (a) shows the case without the extension part and (b) shows the case with the extension part. [Figure 7] FIG. 7 is a cross-sectional view of an expanded portion of an intake pipe structure according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, exemplary embodiments will be described in detail with reference to the drawings. In the following description, the front, rear, left, right, top, and bottom of a vehicle will be simply referred to as the front, rear, left, right, top, and bottom, respectively. With respect to the left-right direction, the left side when looking from the rear to the front side is referred to as the left, and the right side is referred to as the right.

[0030] 1 is a schematic diagram of an engine 1 having an intake pipe structure according to an exemplary embodiment. The engine 1 has an engine body 2. The engine body 2 has, for example, six cylinders (not shown) arranged in series. In this embodiment, the engine body 2 is placed vertically in an engine room at the front of the vehicle such that the cylinders are aligned in the front-rear direction.

[0031] The engine 1 has an intake pipe 10 and an exhaust pipe 20 connected to a cylinder head 2a of an engine body 2. As shown in FIG. 2 and FIG. 3, the downstream end of the intake pipe 10 is connected to the left side surface of the cylinder head 2a. As shown in FIG. 1 to FIG. 3, the intake pipe 3 has a compressor 4a of a turbocharger 4, a throttle valve 5, and an intercooler 6 therein. The intake pipe 10 is also provided with an expansion section 30, which will be described later. These are merely examples of some of the devices disposed in the intake pipe 10, and do not exclude devices other than these being disposed in the intake pipe 10. In this embodiment, the intake pipe 10 includes all of the parts constituting the intake passage, and even if the parts in which the compressor 4a and the throttle valve 5 are disposed are chamber-shaped, these parts are also included in the intake pipe 10.

[0032] The compressor 4a is rotated by the rotation of the turbine 4b by the exhaust gas, compresses the intake air introduced into the intake pipe 10, and releases it downstream of the intake air. The intercooler 6 is disposed downstream of the compressor 4a and cools the intake air compressed by the compressor 4a. The intercooler 6 may be air-cooled or water-cooled. The throttle valve 5 is disposed in the intake pipe 10 at a position downstream of the compressor 4a and upstream of the intercooler 6. The throttle valve 5 changes its opening in response to depression of an accelerator pedal disposed in the vehicle cabin to adjust the amount of intake air introduced into the engine body 2.

[0033] The exhaust pipe 20 has an upstream end connected to the right side surface of the cylinder head 2a. The exhaust pipe 20 has a turbine 4b of the turbocharger 4 therein. The turbine 4b is merely an example of a portion of the devices disposed in the exhaust pipe 20, and does not exclude devices other than the turbine 4b from being disposed in the exhaust pipe 20.

[0034] 2 and 3, the portion of the intake pipe 10 from the compressor 4a to the intercooler 6 is disposed along the periphery of the engine body 2. Specifically, the compressor 4a is provided on the right side (exhaust side) of the upper part of the engine 1, the throttle valve 5 is provided on the left side (intake side) of the upper part of the engine 1, and the intercooler 6 is provided at a position lower than the throttle valve 5 on the left side (intake side) of the engine 1. The intake pipe 10 has a first intermediate intake pipe 11 that connects the position where the compressor 4a is provided to the position where the throttle valve 5 is provided, and a second intermediate intake pipe 12 that connects the position where the throttle valve 5 is provided to the position where the intercooler 6 is provided.

[0035] The first intermediate intake pipe 11 is provided above the engine body 2, particularly above the cylinder head 2a, so as to cross the engine body 2 in a plan view. Since the compressor 4a and the throttle valve 5 are provided at the top of the engine 1, the first intermediate intake pipe 11 is relatively short. The first intermediate intake pipe 11 is made of resin.

[0036] The second intermediate intake pipe 12 extends downward from the position of the throttle valve 5, and then bends and extends forward. The second intermediate intake pipe 12 is made of resin.

[0037] Although not shown in the figures, the intake pipe 10 has an upstream intake pipe that forms a passage upstream of the position of the compressor 4a. The upstream intake pipe extends rearward from the position of the compressor 4a, and then extends leftward and forward so as to bypass the engine body 2. Only the intake downstream end of the upstream intake pipe is shown in Figures 2 and 3.

[0038] In this embodiment, a special effort has been put into the configuration of the first intermediate intake pipe 11. The first intermediate intake pipe 11 will be described in detail below.

[0039] 3 to 5, the first intermediate intake pipe 11 has a bent portion 11a that is bent in the cylinder row direction of the engine body 2, and a straight portion 11b that extends linearly from the intake downstream end of the bent portion 11a. The bent portion 11a is bent toward the rear. The straight portion 11b extends at an incline toward the rear toward the left so as to be continuous with the intake downstream end of the bent portion 11a.

[0040] An expansion section 30 that expands the volume of the first intermediate intake pipe 11 is provided in the portion on the inner arc side of the bent portion 11a of the first intermediate intake pipe 11, i.e., the rear portion of the first intermediate intake pipe 11. The expansion section 30 is provided so as to fit along the bent portion 11a and the straight portion 11b of the first intermediate intake pipe 11 and to bulge rearward from the first intermediate intake pipe 11. The expansion section 30 is made of resin.

[0041] As shown in Figures 4 and 5, the extension portion 30 is composed of a main body portion 31 which is formed integrally with the first intermediate intake pipe and has an opening on the side opposite (rear side) from the first intermediate intake pipe 11, and a cover portion 32 which is formed separately from the main body portion 31 and which closes the opening of the main body portion 31 from the rear side.

[0042] The end of the main body 31 on the first intermediate intake pipe 11 side is integrally formed with the first intermediate intake pipe 11 over the entirety. As shown in Figs. 4 and 5, the main body 31 bulges in a direction substantially perpendicular to the pipe axis direction of the straight portion 11b. The open end of the main body 31 has a first parallel portion 31a extending parallel to the pipe axis direction from the right side in a plan view, an inclined portion 31b extending from the left end of the first parallel portion 31a toward the left side in a plan view, and a second parallel portion 31c extending parallel to the pipe axis direction from the left end of the inclined portion 31b in a plan view. A flange 31d is provided at the open end of the main body 31. A plurality of outer ribs 31e are formed in a mesh pattern over the entire outer peripheral surface of the main body 31 (only the outer ribs 31e on the upper surface portion are shown in Fig. 4).

[0043] As shown in Fig. 5, the lid portion 32 has an opening on the side of the main body portion 31. As shown in Fig. 3, the portion of the lid portion 32 opposite the opening (the rear portion) has a curved and inclined shape so as to avoid surrounding components. A flange 32a corresponding to the flange 31d of the main body portion 31 is formed at the open end of the lid portion 32. A plurality of outer ribs 32b are formed on the outer peripheral surface of the lid portion 32.

[0044] The flanges 31d, 32a of the main body 31 and the cover 32 are overlapped with each other and the flanges 31d, 32a are welded to each other around the entire circumference to form the extension portion 30. As a result, the extension portion 30 is not connected to anything other than the first intermediate intake pipe 11.

[0045] As shown in FIG. 5, inside the extension section 30, the main body section 31 is provided with a plurality of (here, three) inner ribs 31f extending in a direction intersecting the longitudinal direction of the extension section 30, specifically toward the lid section 32 side. The inner ribs 31f are provided at the position of the first parallel section 31a, the position of the inclined section 31b, and the position of the second parallel section 31c in the longitudinal direction of the extension section 30. The end of each inner rib 31f on the lid section 32 side does not reach the opening of the main body section 31, and is located on the first intermediate intake pipe 11 side of the opening. The end of each inner rib 31f on the first intermediate intake pipe 11 side is integrated with the first intermediate intake pipe 11. Inside the extension section 30, the lid section 32 is provided with a plurality of (here, two) inner ribs 32c extending in a direction intersecting the longitudinal direction of the extension section 30, specifically toward the main body section 31. Each inner rib 32c is provided slightly offset from the inner rib 31f of the main body 31 in the longitudinal direction of the expansion section 30. The end of each inner rib 32c on the main body 31 side does not reach the opening of the lid section 32, but is located just before the opening. This forms a gap between the inner rib 31f of the main body 31 and the inner rib 32c of the lid section 32.

[0046] In the first intermediate intake pipe 11, downstream of the bent portion 11a and in a separation region R where the intake air flow separates from the wall surface, a communication hole 33 that communicates with the inside of the extension portion 30 is provided. Specifically, the communication hole 33 is formed in a portion of the straight portion 11b near the bent portion 11a. By providing the communication hole 33, when the intake air passes through the first intermediate intake pipe 11, air can be sucked out from inside the extension portion 30, making the flow of the intake air smoother.

[0047] FIG. 6 shows the flow of intake air when it passes through a curved portion of the intake pipe. That is, as shown in FIG. 6(a), when the intake air passes through a curved portion, separation of the intake air occurs on the inner arc side of the curved portion. If the communication hole 33 is not provided, a vortex is generated by the separation of the intake air in the region where the separation of the intake air occurs, disturbing the flow of the intake air. On the other hand, as shown in FIG. 6(b), if the communication hole 33 is provided in the separation region, when the separation of the intake air occurs, the negative pressure generated by the separation of the intake air can be used to suck air out from the communication hole 33. This makes it possible to suppress the formation of vortexes over a wide area and reduce the disturbance of the intake air flow. This makes it possible to smooth the flow of the intake air.

[0048] Here, if the throttle valve 5 is disposed upstream of the intercooler 6 as in this embodiment, the capacity of the portion of the intake pipe 10 between the compressor 4a and the throttle valve 5 (corresponding to the first intermediate intake pipe 11 in this embodiment) becomes small. In particular, if the compressor 4a and the throttle valve 5 are disposed in the upper part of the engine 1 and the first intermediate intake pipe 11 is disposed so as to cross the upper side of the engine body 2 as in this embodiment, the first intermediate intake pipe 11 becomes short, and the capacity of the first intermediate intake pipe 11 becomes small. If the expansion section 30 is not provided and the volume of the first intermediate intake pipe 11 is small, the pressure in the first intermediate intake pipe 11 becomes high when the throttle valve 5 is slightly closed. In particular, since the turbocharger 4 rotates due to inertia even if the depression amount of the accelerator pedal becomes 0, the intake air compressed by the compressor 4a is pushed into the first intermediate intake pipe 11, and the pressure becomes high. As a result, when the throttle valve 5 is open during a transitional period of the engine 1, high-pressure intake air flows into the cylinder all at once, which may cause hunting. In order to suppress hunting, a configuration in which the intake air in the first intermediate intake pipe 11 is bled to lower the pressure in the first intermediate intake pipe 11 is conceivable. In that case, however, the amount of intake air present in the first intermediate intake pipe 11 is reduced, making it difficult to generate a smooth intake flow during a transitional period of the engine 1. In particular, when the first intermediate intake pipe 11 has a bent portion 11a as in this embodiment, separation of the intake air occurs at the bent portion 11a, which tends to disturb the intake flow, making it difficult to control during a transitional period. As a result, hunting becomes more likely to occur.

[0049] In contrast, in this embodiment, the expansion section 30 is provided, and a communication hole 33 that communicates with the expansion section 30 is provided in the separation region R in the straight section 11b. This allows the volume of the first intermediate intake pipe 11 to be increased by the expansion section 30. This allows the first intermediate intake pipe 11 to be prevented from becoming high pressure as much as possible, even when the throttle valve 5 is slightly closed. Furthermore, during a transient state of the engine 1, the negative pressure generated by the separation of the intake air at the bent section 11a is used to suck air out of the expansion section 30, thereby preventing turbulence in the intake flow and generating a smooth intake flow. Furthermore, since the expansion section 30 is provided on the inner arc side of the bent section 11a in the first intermediate intake pipe 11, the size of the engine 1 due to the expansion section 30 can be prevented as much as possible. Therefore, the configuration of the engine 1 can be made compact while stabilizing the intake flow during a transient state.

[0050] In this embodiment, the extension section 30 is composed of a main body section 31 that is formed integrally with the first intermediate intake pipe 11 and has an opening on the side opposite to the first intermediate intake pipe 11, and a lid section 32 that is formed separately from the main body section 31 and closes the opening of the main body section 31. This makes it possible to easily change the volume of the extension section 30 by changing the volume of the lid section 32 in accordance with the configuration of the engine 1. As a result, it is possible to stabilize the intake flow during a transition while making the configuration of various engines 1 compact.

[0051] In this embodiment, the extension section 30 is provided with a plurality of inner ribs 31f, 32c extending in a direction intersecting the longitudinal direction of the extension section 30. This configuration can suppress membrane vibrations that occur when air is sucked out of the extension section 30, and can suppress the generation of radiated sound. In addition, the rigidity of the extension section 30 can be increased.

[0052] (Modification) FIG. 7 shows a modified example of this embodiment. In this modified example, the configuration of the first intermediate intake pipe 11 is different from that of the above embodiment. Specifically, as shown in FIG. 7, this modified example differs from the above embodiment in that a downstream communication hole 234 communicating with the extension section 30 is provided at a position away from the communication hole 33 in the straight section 11b of the first intermediate intake pipe 11 on the intake downstream side. The downstream communication hole 234 communicates the downstream end of the extension section 30 in the intake flow direction with the straight section 11b. By providing the downstream communication hole 234, intake air can also be drawn out from the downstream communication hole 234. This makes it possible to further stabilize the intake flow during the transition of the engine 1.

[0053] (Other embodiments) The technology disclosed herein is not limited to the above-described embodiment, and may be substituted without departing from the spirit and scope of the claims.

[0054] For example, in the embodiment described above, only one communication hole 33 is provided in the separation region R on the intake downstream side of the bent portion 11a of the first intermediate intake pipe 11. However, the present invention is not limited to this, and multiple communication holes 33 may be provided in the separation region R.

[0055] In the modified example of the embodiment described above, only one downstream communication hole 234 is provided. However, this is not limiting, and multiple downstream communication holes 234 may be provided as long as they are located away from the communication hole 33 in the straight section 11b on the intake downstream side.

[0056] In the above embodiment, the first intermediate intake pipe 11 has the bent portion 11a as a curved portion. However, the curved portion may be a curved portion that curves in the cylinder row direction. The first intermediate intake pipe 11 may be composed of only a curved portion without having a straight portion 11b. In this case, the communication hole 33 is provided in a separation region on the intake downstream side of the curved portion of the first intermediate intake pipe 11.

[0057] The above-described embodiments are merely illustrative and should not be construed as limiting the scope of the present disclosure. The scope of the present disclosure is defined by the claims, and all modifications and variations within the scope of the claims are within the scope of the present disclosure. [Industrial Applicability]

[0058] The technology disclosed herein is useful as an intake pipe structure for an engine having, inside the intake pipe, a turbocharger compressor and an intercooler disposed downstream of the compressor in the intake direction. [Explanation of symbols]

[0059] 1 Engine 2 Engine body 4. Turbocharger 4a Compressor 5 Throttle valve 6. Intercooler 10 Intake pipe 11 First intermediate intake pipe 11a Bend part 11b Straight section 30 Extension 31 Main body 31f Inner rib 32 Lid 32c inner rib 33 Communication hole (first communication hole) 234 Downstream communication hole (second communication hole)

Claims

1. An intake pipe structure of an engine having a compressor of a turbocharger and an intercooler arranged downstream of the compressor in an intake air flow direction, a throttle valve disposed in an intake pipe at a position downstream of the compressor and upstream of the intercooler; an expansion portion that is provided along an intermediate intake pipe that is a portion of the intake pipe between the compressor and the throttle valve and that expands from the intermediate intake pipe, and expands a volume of the intermediate intake pipe, The intermediate intake pipe has a bent portion, The expansion portion is formed on the inner arc side of the curved portion, a first communication hole communicating with the expansion portion is provided in a separation region of the intermediate intake pipe where the intake air flow separates from a wall surface, An intake pipe structure, wherein the first communication hole is formed in the curved portion.

2. An intake pipe structure of an engine having a turbocharger compressor and an intercooler arranged downstream of the compressor, a throttle valve disposed in an intake pipe at a position downstream of the compressor and upstream of the intercooler; an expansion portion that is provided along an intermediate intake pipe that is a portion of the intake pipe between the compressor and the throttle valve and that expands from the intermediate intake pipe, and expands a volume of the intermediate intake pipe, the intermediate intake pipe has a curved portion and a straight portion extending linearly from a downstream end of the curved portion, The expansion portion is formed on the inner arc side of the curved portion and along the curved portion and the straight portion, a first communication hole communicating with the expansion portion is provided in a separation region of the intermediate intake pipe where the intake air flow separates from a wall surface, An intake pipe structure, wherein the first communication hole is formed in a portion of the straight portion adjacent to the curved portion.

3. The intake pipe structure according to claim 2, an intake pipe structure, characterized in that a second communication hole communicating with the expansion portion is provided at a position in the straight portion away from the first communication hole on the intake downstream side, the second communication hole being connected to the expansion portion;

4. In the intake pipe structure according to any one of claims 1 to 3, An intake pipe structure, characterized in that a plurality of ribs are provided within the expansion portion, the ribs extending in a direction intersecting with the longitudinal direction of the expansion portion.

5. In the intake pipe structure according to any one of claims 1 to 4, An intake pipe structure characterized in that the expansion portion is composed of a main body portion that is formed integrally with the intermediate intake pipe and has an opening on the side opposite the intermediate intake pipe, and a cover portion that is formed separately from the main body portion and closes the opening of the main body portion.

6. In the intake pipe structure according to any one of claims 1 to 5, The compressor is provided on the exhaust side at an upper portion of the engine, The throttle valve is provided on the intake side of an upper portion of the engine, The intermediate intake pipe is provided on an upper side of the engine body so as to cross the engine body in a plan view, the curved portion is curved in a cylinder row direction of the engine body, The expansion portion is provided on an inner arc side of the curved portion so as to bulge from the intermediate intake pipe in the cylinder row direction.

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