JP2005155396A - Intake device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make an intake device for an internal combustion engine compact. <P>SOLUTION: In the intake device for the internal combustion engine provided with a variable valve system capable of continuously varying valve lift characteristics of an intake valve 1, regulating intake air quantity by controlling the variable valve system, and having a plurality of air intake branches 43 communicating to an intake port 34 of the internal combustion engine project in a collector 38 arranged in an intake air downstream side of an air cleaner 46, a duct 50 connecting a collector 38 and the air cleaner 46 is provided with an air flow meter 51 detecting air flow rate in the duct 50, and is positioned in a root side of the intake branch 43 in the collector 38 than air intake branch opening part 47 opening in the collector 38. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an intake device for an internal combustion engine.

Patent Document 1 discloses an internal combustion engine in which an air cleaner incorporated in a collector is disposed at a position deviated from the direction in which an intake branch protrudes, and the collector is directly attached to a side wall of a cylinder head or its attachment member. An air intake apparatus is disclosed. In Patent Document 1, for example, the support rigidity of the collector is improved and the vibration input acting on the collector is reduced as compared with the case where the collector is attached to the protruding end portion of the intake branch. In addition, the collector is disposed close to the side wall of the cylinder head, and the intake branch is substantially built in the collector, so that the intake device is made compact and the engine mountability is improved.
JP 2002-276487 A

  However, in Patent Document 1, when an air flow meter is installed in the intake system, a duct having a sufficient straight portion downstream of the air cleaner is required. However, since the collector and the air cleaner are integrated, if the duct is installed, the intake system size becomes large, and if the duct is bent to maintain the size, the pressure loss may increase and the performance may deteriorate. In addition, from the viewpoint of preventing deterioration of the air cleaner due to combustion gas, the protruding direction of the intake branch is set at a position away from the air cleaner, so that there is a problem that the branch length in the collector is limited by the air cleaner.

  Therefore, the present invention includes a variable valve mechanism that can continuously change the valve lift characteristics of the intake valve, and controls the variable valve mechanism to adjust the intake air amount and communicate with the intake port of the internal combustion engine. In an intake system of an internal combustion engine in which a plurality of intake branches projecting into a collector disposed on the intake downstream side of the air cleaner, the duct connecting the collector and the air cleaner is an air flow meter that detects the air flow rate in the duct It is characterized by being located on the base side of the intake branch in the collector rather than the intake branch opening that opens in the collector.

  According to the present invention, the duct having the air flow meter can be inserted into the collector without being limited to the intake branch opening, and the collector and the air cleaner can be disposed adjacent to each other, so that the intake system can be made compact. .

  Hereinafter, an embodiment in which the present invention is applied to a four-cylinder gasoline internal combustion engine will be described in detail with reference to the drawings. First, referring to FIG. 9, a variable valve mechanism that can change the valve lift characteristics (valve timing and valve lift amount) of the intake valve 1 will be described as a configuration common to all the embodiments. This variable valve mechanism can change the operating angle change mechanism 10 that can change the operating angle and valve lift amount of the intake valve 1, and the phase (for example, the center phase) of the operating angle of the intake valve with respect to the crankshaft (not shown). And a phase change mechanism 20.

  The operating angle changing mechanism 10 includes a drive shaft 11 and a control shaft 12 that extend in parallel to each other in the cylinder row direction. The drive shaft 11 rotates around the shaft by the rotational power transmitted from the crankshaft. A swing cam 13 that can contact the valve lifter 2 of the intake valve 1 is rotatably fitted on the drive shaft 11, and an eccentric cam 14 is fixed or integrally formed for each cylinder. The axis of the outer peripheral surface of the eccentric cam 14 is eccentric with respect to the axis of the drive shaft 11, and a ring-shaped first link 15 is rotatably fitted on the outer peripheral surface of the eccentric cam 14.

  A control cam 16 is fixed or integrally formed on the control shaft 12 for each cylinder. The axis of the outer peripheral surface of the control cam 16 is eccentric with respect to the axis of the control shaft 12, and the central portion of the rocker arm 17 is rotatably fitted on the outer peripheral surface of the control cam 16. One end of the rocker arm 17 is rotatably connected to the tip of the first link 15, and the other end of the rocker arm 17 is rotatably connected to one end of the rod-shaped second link 18. The other end of the second link 18 is rotatably connected to the tip of the swing cam 13.

  Therefore, when the drive shaft 11 rotates around the shaft in conjunction with the rotation of the crankshaft, the first link 15 fitted on the eccentric cam 14 operates in a substantially translation direction, and the translational motion of the first link 15 is the rocker arm. The swing cam 13 swings through the second link 18 after being converted into the swing motion of 17. This swinging swing cam 13 abuts against and presses the valve lifter 2 of the intake valve 1, whereby the intake valve 1 is driven to open and close against the reaction force of a valve spring (not shown).

  Further, when the control shaft 12 is rotationally driven by the actuator 19, the center position of the control cam 16 which is the rocking center of the rocker arm 17 is changed, and the posture of the rocker arm 17 and the links 15, 18 is changed to be rocked. The swing characteristic of the cam 13 changes. Thereby, both the operating angle of the intake valve 1 and the valve lift amount are continuously changed.

  In the operating angle changing mechanism 10 having such a configuration, since the swing cam 13 that opens and closes the intake valve 1 is coaxially attached to the drive shaft 11, the shaft misalignment between the swing cam 13 and the drive shaft 11, etc. In addition to being excellent in control accuracy, the rocker arm 17 and the links 15 and 18 can be gathered around the drive shaft 11 to achieve compactness and excellent in engine mountability. Further, since many of the connecting portions between the members, such as the bearing portion of the eccentric cam 14 and the first link 15 and the bearing portion of the control cam 16 and the rocker arm 17, are in surface contact, lubrication is performed. Easy, durable and reliable. Further, when the operating angle changing mechanism 10 is applied to a general fixed valve system having a fixed cam and a camshaft, the swing cam 13 and the drive shaft 11 are placed at the positions of the fixed cam and the camshaft. The layout can be arranged and the layout can be changed very little, so that the application is very easy.

  The phase changing mechanism 20 continuously changes the center phase of the lift operating angle of the intake valve by changing the phase of the drive shaft 11 (camshaft in the case of a fixed valve system) with respect to the crankshaft. A type using a vane, a type using a helical spline, and the like are known, and detailed description thereof is omitted.

  The ECU (engine control unit) 4 as a control means performs general engine control such as fuel injection control based on the engine operating state detected by various sensors and the like, and also includes an actuator 19 of the operating angle changing mechanism 10 and The operation of the phase change mechanism 20 (actuator thereof) is controlled to change and control the valve lift characteristic of the intake valve.

  By using such a variable valve mechanism, for example, a response delay in reducing the pressure in the collector that occurs when the automobile is decelerated is eliminated, and the degree of freedom in designing the collector volume is increased.

  Next, a description will be given of a first embodiment of an intake device for an internal combustion engine according to the present invention. As shown in FIG. 1, one end of intake ports 34 of a plurality (four in this embodiment) of cylinders is opened on the side wall 32 on the intake side of the cylinder head 30. A mounting bracket 36 is fixed to the side wall 32 so as to cover the opening 35. The mounting bracket 36 is directly attached with one collector 38 made of a lightweight resin material and having an elongated cross-sectional shape in the vertical direction substantially along the side wall 32. More specifically, the collector 38 has a dimension in the engine vertical direction (vertical direction in FIG. 1) substantially along the side wall 32 of the cylinder head 30 (in the horizontal direction in FIG. 1). ) Is set longer than the dimension of. In addition, 31 in FIG. 1 is a cylinder block to which the cylinder head 30 is attached.

  As shown in FIGS. 2 and 3, the intake device has a linear shape over the entire length connecting the collector 38, the air cleaner 46 adjacent to the intake upstream side of the collector 38, and the collector 38 and the air cleaner 46. The duct 50 is generally composed of.

  The air cleaner 46 is generally constituted by an air cleaner body dust side 46a, an air cleaner body clean side 46b, and an element 46c for purifying (filtering) air. The air cleaner 46 has an elongated shape in the vertical direction of the engine (vehicle), that is, in the vertical direction in FIG. 1 or FIG. The air cleaner 46 is divided into an upper portion and a lower portion by an element 46 c at a substantially central position along the vertical direction, an air cleaner body dust side 46 a is formed above the element 46, and an air cleaner body clean side 46 b is formed below the element 46. Is formed.

  In the duct 50, an air flow meter 51 that detects the amount of air flowing through the duct 50 (intake air amount), and an intake air downstream side of the air flow meter 51, a minimum negative pressure is generated in the collector 38. A negative pressure control valve 52 is attached. The air flow meter 51 and the negative pressure control valve 52 are disposed in the duct 50 so as to be located in the collector 38.

  As shown in FIG. 4, the collector 38 includes a collector main body 39 constituting the main body of the collector 38, a collector upper part 40 constituting the upper portion of the collector 38, an intake branch unit 41 attached to the collector main body 39, a collector The collector side wall 42 is attached to the main body 39 after the intake branch unit 41 is enclosed in the main body 39. The intake branch unit 41 is formed by integrating a plurality of intake branches 43 communicating with the intake port 34. That is, the intake branch 43 is built in the collector 38, so that the intake device is made compact.

  Here, 44 in FIG. 4 is a main body side protruding wall provided in the collector main body 39, and these main body side protruding walls 44 are positioned between the adjacent intake branches 43, 43. Further, 45 in FIG. 4 is a side wall portion side protruding wall provided on the collector side wall portion 42, and these side wall portion side protruding walls 45 are also located between the adjacent intake branches 43, 43. When the collector side wall 42 is assembled to the collector main body 39, the tip portions of the main body side protruding wall 44 and the side wall protruding wall 45 corresponding to each other come into contact with each other, and the collector 38 in the engine width direction is in contact with each other. Strength is improved. The collector main body 39, the collector upper part 40, the intake branch unit 41, and the collector side wall part 42 are connected to each other with a seal member (not shown) interposed therebetween.

  Each intake branch 43 is curved and extends upward from the inner wall surface of the collector main body in the engine vertical direction. In other words, the intake branch 43 protrudes from the long side portion 48 of the collector 38 along the longitudinal direction of the collector 38 on an elongated cross section substantially orthogonal to the cylinder row direction of the collector 38. Each intake branch opening 47 of the intake branch 43 that opens into the collector 38 is directed upward in FIGS. 1 to 3.

  This is due to the fact that in consideration of the vehicle mountability of the engine, there are many restrictions in the entire width direction of the engine. As described above, the controllability of the collector volume is increased by controlling the intake air amount of the engine using the variable valve mechanism. Since the fully open output decreases as the collector capacity decreases, the collector capacity should be increased in terms of output performance. Thus, when the intake air amount is adjusted by changing the valve lift characteristic of the intake valve closer to the combustion chamber than the collector, the collector capacity can be sufficiently increased without concern about a decrease in intake response. However, in order to secure the collector volume, when it is arranged vertically in the engine room, it is restricted by the full width of the vehicle, and the full width of the engine is also restricted. In addition, when the engine room is placed horizontally, the full width of the engine is limited by the length of the engine room in the vehicle front-rear direction. Therefore, if the collector volume is limited to a certain limited engine full width, in order to secure the length of the intake branch, the intake branch opening is directed upward in the engine vertical direction as in this embodiment, or will be described later. As in the second embodiment, the engine is directed downward in the vertical direction of the engine. Further, when the collector is mounted on the engine as in the third embodiment described later, the height of the collector is limited by the bonnet hood. Will open in the direction.

  Each intake branch 43 has a communication passage 44 that communicates with the intake port 34, protrudes into the collector 38, and opens each intake branch 43 of the intake branch 43 that is an opening of the communication passage 44 that opens into the collector 38. The portion 47 is formed so as to be directed upward in the vertical direction along the side wall 32 of the cylinder head 30, that is, upward in FIG. 1 or FIG. 3.

  Here, the duct 50 is attached to the branch root side from the intake branch opening 47. More specifically, on the collector cross section perpendicular to the cylinder row direction as shown in FIG. 1, the first inner wall surface 54 that faces the inner wall surface 53 that faces the intake branch opening 47 among the inner wall surfaces of the collector 38. The duct 50 is connected to the collector 38 so that the duct opening 50 a is located between the intake branch 43 in the collector 38, in other words, below the intake branch 43.

  Further, the duct 50 is connected so as to protrude in the cylinder row direction into the collector 38 so as to overlap with at least one intake branch 43 in the cylinder row direction. In this embodiment, the intake branch is seen in the cylinder row direction. A duct opening 50a is located between 43a and the intake branch 43b.

  This is because if the duct 50 and the intake branch opening 47 are arranged on the same side in the collector 38, the duct 50 cannot be inserted deeply into the collector 38 beyond the intake branch 43 closest to the duct 50. This is to prevent the intake device from becoming relatively large due to the necessity of taking up the space of the duct 50 between the two. Further, the intake branch opening 47 must be set so as not to intersect the surface extending in the downstream direction of the flow from the duct 50 so as not to become a resistance by preventing the main flow of the air flowing out from the duct 50. This is to prevent the branch 43 from being shortened and the volume efficiency from being lowered. That is, in this embodiment, since the intake branch 43 can be lengthened, volume efficiency can be improved.

  Further, the curvature of the fillet portion 57 inside the collector facing the duct opening 50a is the curvature of the fillet portion inside the collector not facing the duct opening, for example, the curvature of the fillet portions 58, 59, 60, etc. in FIG. It is set to be larger.

  Further, as shown in FIG. 5 (a cross-sectional view along the line AA in FIG. 1), the collector internal cross-sectional area excluding the intake branch 43 on the collector cross section orthogonal to the opening direction of the intake branch opening 47 is shown. The minimum value S is set to be larger than the sum of the opening areas of the intake branch openings 47.

  In the first embodiment, the duct 50 and the intake branch opening 47 are arranged opposite to each other, that is, the duct 50 is connected to the collector side closer to the root of the intake branch 43 than the intake branch opening 47 that opens into the collector 38. 38, the duct 50 can be inserted into the collector 38, and the collector 38 and the air cleaner 46 can be disposed adjacent to each other, so that the intake system can be made compact.

  Further, the duct 50 is disposed in the space below the intake branch 43 in the collector 38, that is, between the root 55 of the intake branch 43 and the first inner wall surface 54. Therefore, the collector 38 can be made thinner in the direction orthogonal to the direction in which the intake branch opening 47 is directed, that is, in the engine width direction, and the intake system can be made more compact.

  Further, since the duct 50 protrudes into the collector 38 so as to wrap with the at least one intake branch 43 in the cylinder row direction, the distance from the duct opening 50a to each intake branch opening 47 varies. Can be reduced, and equalization of air distribution can be promoted.

  Furthermore, since the duct opening 50a is located between the adjacent intake branches 43 and 43 (43a and 43b), the air discharged from the duct opening 50a is not subjected to the resistance of the intake branch 43. It can be led to the intake branch opening 47.

  Since the duct 50 is linearly formed over the entire length, the air in the duct 50 can be guided into the collector 38 without suffering a pressure loss due to bending, and the amount of air by the air flow meter 51 Measurement accuracy can be improved.

  Further, since the duct 50 includes a negative pressure control valve 52 in addition to the air flow meter 51, it is not necessary to install a duct or the like having only the negative pressure control valve separately from the duct 52, and the intake system It can be made compact.

  Further, since the air flow meter 51 and the negative pressure control valve 52 provided in the duct 50 are disposed inside the collector 38, the air cleaner 46 and the collector 38 can be disposed adjacent to each other, and the intake system is made compact. be able to.

  The curvature of the fillet portion 57 inside the collector 38 facing the duct opening 50a is set to be larger than the curvature of the fillet portions 58, 59, 60 inside the collector 38 not facing the duct opening 50a. Therefore, the air that collides with the fillet portion 57 discharged from the duct opening portion 50 a can be guided to the intake branch opening portion side while suppressing pressure loss due to the relatively large curvature of the fillet portion 57.

  Further, on the collector cross section orthogonal to the opening direction of the intake branch opening 47, the minimum value S of the collector internal cross-sectional area excluding the intake branch 43 is larger than the sum of the opening areas of the intake branch openings 47. Since it is set, the pressure loss until the air that has flowed into the collector 38 flows into the intake branch opening 47 can be suppressed.

  In the first embodiment described above, the air cleaner 46 is divided into the air cleaner body clean side 46b and the air cleaner body dust side 46a in the vertical direction of the engine by the element 46c. However, as shown in FIG. The element 46c may be inclined with respect to the direction, and the air cleaner 46 may be divided into an air cleaner body clean side 46b and an air cleaner body dust side 46a obliquely with respect to the engine vertical direction. In this case, since the surface area of the element is larger than the surface area of the element of the first embodiment described above, the thickness of the element is relatively reduced.

  Next, a description will be given of a second embodiment of the intake device for an internal combustion engine according to the present invention. In each embodiment described below, the same components as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  In the intake device according to the second embodiment, as shown in FIG. 7, the intake branch 43 is curved and extends downward from the inner wall surface of the collector main body 39 in the engine vertical direction. In other words, the intake branch 43 projects from the long side portion 48 of the collector 38 along the longitudinal direction of the collector on an elongated cross section substantially perpendicular to the cylinder row direction of the collector 38. Each intake branch opening 47 of each intake branch 43 that opens into the collector 38 is directed downward in FIG.

  In addition, as the intake branch 43 curves and extends downward in the vertical direction of the engine, in this second embodiment, the duct 50 is arranged so that the duct opening 50a is positioned above the intake branch 43. The collector 38 is connected.

  That is, the intake device in the second embodiment has the same configuration as that of the first embodiment described above, except for the protruding direction of the intake branch 43 and the connection position of the duct 50 to the collector 38.

  In such a second embodiment, the same operational effects as those of the first embodiment described above can be obtained.

  FIG. 8 shows a third embodiment of an intake device for an internal combustion engine according to the present invention. In the third embodiment, a first intake branch 70 is built in a collector 38 located above the cylinder head (above the engine), and the first intake branch 70 is located on the left side in the engine width direction from the inner wall surface of the collector main body 39. It curves and extends toward (in FIG. 8). Each intake branch opening 71 of each first intake branch 70 that opens into the collector 38 is directed to the left side in the engine width direction in FIG.

  The collector 38 is attached to the tip of the second intake branch 72. The second intake branch 72 communicates with the intake port 34, extends from the side wall 32 toward the upper side of the engine, and is provided on the mounting bracket 36. These second intake branches 72 communicate with corresponding first intake branches 71 built in the collector 38, respectively.

  That is, the first intake branch 71 in the third embodiment corresponds to the intake branch 43 in the first embodiment described above, and this third embodiment is substantially the same as the first embodiment described above. Similarly, the intake branch 43 (first intake branch 71) protrudes from the long side portion 48 of the collector 38 along the longitudinal direction of the collector on an elongated cross section substantially perpendicular to the cylinder row direction of the collector. Yes.

  Therefore, the intake device in the third embodiment has substantially the same configuration as that of the first embodiment described above, except that the collector 38 is positioned above the cylinder head 30.

  In the third embodiment, the same effects as those of the first embodiment described above can be obtained, and the collector 38 is positioned above the engine and is wrapped with the engine in the engine width direction. Compared to the first embodiment, the degree of freedom of design in the engine width direction of the intake system can be relatively increased.

  The technical idea of the present invention that can be grasped from the above embodiment will be listed together with the effects thereof.

  (1) An intake device for an internal combustion engine includes a variable valve mechanism that can continuously change the valve lift characteristics of the intake valve, and controls the variable valve mechanism to adjust the intake air amount. A plurality of intake branches communicating with the intake port protrude into a collector disposed on the intake downstream side of the air cleaner, and a duct connecting the collector and the air cleaner detects an air flow rate in the duct. An air flow meter is provided, and is located closer to the root of the intake branch in the collector than the intake branch opening that opens into the collector. Accordingly, the duct having the air flow meter can be inserted into the collector without being limited to the intake branch opening, and the collector and the air cleaner can be disposed adjacent to each other, so that the intake system can be made compact.

  (2) In the configuration described in (1) above, the collector has an elongated shape in a cross section substantially perpendicular to the cylinder row direction, and the intake branch extends from the long side portion of the collector to the longitudinal direction of the collector on the elongated cross section. A duct opening between a first inner wall surface of the collector inner wall surface facing the inner wall surface facing the intake branch opening and a root of the intake branch in the collector. The part is located. As a result, the collector can be thinned in a direction orthogonal to the direction in which the intake branch opening is directed, and the intake system can be made more compact.

  (3) In the configuration described in (1) or (2) above, the duct is formed so that the duct opening projects into the collector so as to wrap in at least one intake branch in the cylinder row direction. As a result, the variation in distance from the duct opening to each intake branch opening is reduced, and the equalization of air distribution can be promoted.

  (4) In the configuration according to any one of (1) to (3), the duct opening is located between adjacent intake branches. As a result, the air discharged from the duct opening can be guided to each intake branch opening without receiving the resistance of the intake branch.

  (5) In the configuration according to any one of (1) to (4), the duct is formed linearly over the entire length. As a result, the air in the duct can be guided into the collector without suffering a pressure loss due to bending, and the air amount measurement accuracy by the air flow meter can be improved.

  (6) In the configuration according to any one of (1) to (5), the duct is provided with a negative pressure control valve. Thereby, it is not necessary to separately install a duct or the like having only the negative pressure control valve, and the intake system can be made compact.

  (7) In the configuration described in (6) above, the air flow meter and the negative pressure control valve are arranged in the duct so as to be located in the collector. Accordingly, the air cleaner and the collector can be disposed adjacent to each other, and the intake system can be made compact.

  (8) In the configuration described in any one of (1) to (7) above, the curvature of the fillet portion inside the collector facing the duct opening is the curvature of the fillet portion inside the collector not facing the duct opening. It is set to be larger. Thereby, the air which collides with the fillet part facing the duct opening part can be guided to the intake branch opening part side while suppressing the pressure loss by the relatively large curvature of the fillet part.

  (9) In the configuration described in any one of (1) to (8) above, on the collector cross section orthogonal to the opening direction of the intake branch opening, the minimum value of the collector internal cross-sectional area excluding the intake branch is It is set to be larger than the total opening area of the intake branch opening. Thereby, the pressure loss until the air that has flowed into the collector flows into the intake branch opening can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows schematic structure of 1st Embodiment of the intake device of the internal combustion engine which concerns on this invention. 1 is a cross-sectional view of a main part of a first embodiment of an intake device for an internal combustion engine according to the present invention. Sectional drawing along the BB line of FIG. The exploded perspective view of a collector. Sectional drawing along the AA line of FIG. The principal part sectional drawing of other embodiment of the intake device of the internal combustion engine which concerns on this invention. Explanatory drawing which shows schematic structure of 2nd Embodiment of the intake device of the internal combustion engine which concerns on this invention. Explanatory drawing which shows schematic structure of 3rd Embodiment of the intake device of the internal combustion engine which concerns on this invention. The perspective view of the variable valve mechanism common to all the embodiments.

Explanation of symbols

4 ... ECU
DESCRIPTION OF SYMBOLS 10 ... Operating angle change mechanism 20 ... Phase change mechanism 30 ... Cylinder head 32 ... Side wall 34 ... Intake port 36 ... Mounting bracket 38 ... Collector 43 ... Intake branch 46 ... Air cleaner 50 ... Duct 51 ... Air flow meter 52 ... Negative pressure control valve

Claims (9)

A variable valve mechanism capable of continuously changing the valve lift characteristics of the intake valve is provided. The variable valve mechanism is controlled to adjust the amount of intake air, and a plurality of intake branches communicating with the intake port of the internal combustion engine are provided. In the intake device of the internal combustion engine that protrudes into the collector disposed on the intake downstream side of the air cleaner,
The duct connecting the collector and the air cleaner is equipped with an air flow meter that detects the air flow rate in the duct, and is located closer to the root of the intake branch in the collector than the intake branch opening that opens in the collector. An intake device for an internal combustion engine. The collector has an elongated shape in a cross section substantially perpendicular to the cylinder row direction, and on this elongated cross section, the intake branch projects from the long side portion of the collector along the longitudinal direction of the collector,
The duct opening is located between the first inner wall facing the inner wall facing the intake branch opening of the inner wall of the collector and the root of the intake branch in the collector, The intake device for an internal combustion engine according to claim 1.   3. The intake system for an internal combustion engine according to claim 1, wherein the duct is formed so that a duct opening projects into the collector so as to wrap in at least one intake branch in the cylinder row direction.   The intake device for an internal combustion engine according to any one of claims 1 to 3, wherein the duct opening is located between adjacent intake branches.   The intake device for an internal combustion engine according to any one of claims 1 to 4, wherein the duct is formed linearly over the entire length.   The intake device for an internal combustion engine according to any one of claims 1 to 5, wherein the duct is provided with a negative pressure control valve.   The intake device for an internal combustion engine according to claim 6, wherein the air flow meter and the negative pressure control valve are disposed in the duct so as to be located in the collector.   The curvature of the fillet part inside the collector facing the duct opening is set to be larger than the curvature of the fillet part inside the collector not facing the duct opening. An intake device for an internal combustion engine according to claim 1. On the collector cross section perpendicular to the opening direction of the intake branch opening, the minimum value of the collector internal cross-sectional area excluding the intake branch is set to be larger than the sum of the opening areas of the intake branch openings. The intake device for an internal combustion engine according to any one of claims 1 to 8.

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