JP3861365B2 - Engine intake system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine intake device provided with an intake flow control valve upstream of an intake port in order to generate a vortex flow in a combustion chamber.
[0002]
[Prior art]
2. Description of the Related Art Various types of intake devices for an engine have conventionally been provided with an intake flow control valve (Swirl Control Valve: SV) upstream of the intake port so that a vortex is generated in the combustion chamber when the intake flow control valve is closed. Are known.
[0003]
For example, in Japanese Patent Application Laid-Open No. 8-218881, an intake flow control valve is disposed on the upstream side of an intake port having a common portion branched downstream into two port portions, and the intake flow control valve is partially cut out. Intake air that is configured to generate swirl (lateral vortex) and tumble (longitudinal vortex) in the combustion chamber by intake air flowing downstream of the intake port through the opening when the valve is fully closed The device is shown. The swirl and tumble contribute to improving the combustibility, and the swirl strengthening is effective for improving the combustibility in the case of lean burn by stratified combustion.
[0004]
[Problems to be solved by the invention]
The intake flow control valve in this type of intake device enhances swirl or tumble by considering the shape and position of the opening. In order to increase the swirl component, as shown in FIG. 14, an opening portion Va is provided on one side of the intake flow control valve V, and one of the two downstream port portions branched downstream of the valve V is downstream. It is good to increase the intake flow velocity at the port.
[0005]
However, according to the inventor's investigation of the specification of FIG. 14 through experiments and simulations, although a high swirl ratio can be obtained (see specification (3) of FIG. 11), The ratio of the fuel adhesion amount (ratio of the fuel adhesion amount in the intake port to the total fuel injection amount) is relatively large despite the intake stroke injection (see the specification (3) in FIG. 12). When the ratio is large, the amount of fuel supplied into the combustion chamber between the cycles and between the cylinders varies, and the air-fuel ratio fluctuation between the cycles and between the cylinders tends to increase.
[0006]
This is also a factor that the lean set air-fuel ratio in the lean burn operation region cannot be increased. The fuel adhesion mechanism in the intake port in this specification (3) is the same as that in FIG. 17 showing the behavior of the fuel spray downstream of the intake flow control valve V in the partial load / low rotation range of the engine. A description will be given based on the investigation result of FIG. 15 showing the intake flow downstream of the intake flow control valve V.
[0007]
The behavior of the fuel spray in the intake stroke is as follows. The fuel spray F injected to the vicinity of the 60 ° crank angle (ATDC 60 deg) after the top dead center in FIG. 17A is downstream from the common portion of the intake port in the ATDC 90 deg in FIG. A part of the fuel spray F in the downstream port portion P (hereinafter referred to as P port) on one side corresponding to the position of the opening portion Va of the intake flow control valve V reaches the combustion chamber. In the ATDC 120 deg after the middle of the intake stroke in FIG. 5C, the fuel spray F at the P port is almost lost, but the fuel spray F at the other port portion S (hereinafter referred to as S port) stays. Yes.
[0008]
The stay of the fuel spray F in the S port increases the amount of fuel adhering in the intake port, and the stay of the fuel spray F is considered to be due to the intake air flow in the intake port. 15 (a), (b), and (c) showing the intake flow are the same as the crank angles in FIGS. 17 (a), (b), and (c), and the intake flow in the intake stroke is shown in FIG. In the ATDC 60 deg, a forward intake flow is generated in both the P port and the S port. In the ATDC 90 deg in FIG. 5B, a strong intake flow is generated in the P port, and the intake flow in the S port is weakened. Further, in the ATDC 120 deg of FIG. 10C, an intake air flow fb in the reverse direction is generated in the S port. Then, it is considered that the injected fuel spray F in the forward direction is blocked by the intake air flow fb in the reverse direction, and the fuel spray F stays in the S port as shown in FIG.
[0009]
This phenomenon is due to the fact that the vortex that circulates behind the intake flow control valve V (directly downstream) because the common portion and the intake flow control valve V are separated from each other as the intake flow rate and intake flow velocity of the P port increase. It is growing in a form attracted by. (Refer to the vortices ws, wm, and wl in FIGS. 15A, 15B, and 15C) FIG. 16 is a schematic diagram of the intake flow in FIG. The intake air that has flowed into the combustion chamber is returned to the S port in a state in which the lift amount of the intake valve is large and the combustion chamber and the intake port are well ventilated.
[0010]
In view of the above circumstances, the present invention provides an engine intake device capable of ensuring a high swirl ratio while reducing the amount of fuel adhering to the intake port when the intake flow control valve is fully closed. Objective.
[0011]
[Means for Solving the Problems]
A first invention of the present application includes an intake port having a common portion that bifurcates from an upstream port portion to two downstream port portions, and the downstream ends of both downstream port portions each open to a combustion chamber via an intake valve, An intake flow control valve having an opening partly cut away and disposed at an upstream position spaced apart from the common part, and a fuel injection valve for injecting fuel to each of the downstream port parts, In an intake system for an engine in which a swirl is generated in a combustion chamber by closing the flow control valve in a predetermined operating region, both sides of the intake flow control valve are arranged on one side in the column direction where the two downstream port portions are aligned. A first opening for generating an intake main flow with respect to a downstream port portion on one side of the downstream port portions is provided, and at least one of the intake port wall and the intake flow control valve, on the other side portion in the row direction, A second opening for generating an auxiliary intake air flow is provided for the downstream port part on the other side of the downstream port part, and the size of the second opening part is separated from the second opening part. A bulge space is provided above the intake port downstream of the intake flow control valve. The opening is provided with a downward bias .
[0012]
According to this configuration, when the intake flow control valve is fully closed, the intake main flow is generated in the downstream port portion on one side by the intake air flowing downstream through the first opening, and a strong swirl is generated in the combustion chamber. , And the growth of vortices generated on the back side of the intake flow control valve by the small amount of intake air flowing downstream through the second opening is suppressed, and the intake air flow in the reverse direction of the downstream port portion on the other side is suppressed. By preventing the generation, the amount of fuel adhering in the intake port can be reduced, and the combustibility can be improved while reducing the fluctuation of the air-fuel ratio between cycles and between cylinders. Further, since the distance from the fuel injection valve to the combustion chamber is short, the fuel spray section in the intake port is short, and the time until the injected fuel enters the combustion chamber is also shortened. The amount of fuel adhering can be reduced, and the intake flow that has passed through the second opening is not weakened by the bulging space, and the area of the second opening can be reduced correspondingly, and a higher swirl ratio can be obtained.
[0013]
According to a second invention of the present application, in the engine intake device according to the first invention, the first opening is provided in the row direction so as to be biased toward the one side with respect to a center position of the intake flow control valve, And the area ratio of said 2nd opening part with respect to this 1st opening part is set to 20% or less.
[0014]
According to this configuration, the main intake air flow in the downstream port portion on one side through the first opening is less likely to be weakened by the second opening, and a high swirl ratio (the number of swirling of the horizontal vortex in the combustion chamber / engine Rotation number) is obtained.
[0015]
According to a third aspect of the present invention, in the engine intake device according to the first aspect of the present invention, fuel is bifurcated from one fuel injection valve to the downstream port portions, and the center line of the fuel injection and the intake valve Or the intersection with the inner wall of the downstream port near the intake valve is set within the range from the valve shaft to the valve shaft of both intake valves in the row direction, and the second opening is set in the intake direction in the row direction. It is provided apart from the other end of the flow control valve.
[0016]
According to this configuration, since the second opening corresponds to the fuel collision position of the downstream port portion on the other side, the second opening can be reduced and fuel is injected toward the center of the combustion chamber. Therefore, the air-fuel mixture can be stratified in the center of the combustion chamber (around the spark plug) by the strong swirl.
[0017]
According to a fourth aspect of the present invention, in the engine intake device according to the second aspect of the present invention, a rotation shaft that allows the intake flow control valve to rotate from a fully closed state to a fully open state is provided in the row direction. The first opening is notched in the vertical direction across the rotation shaft, and the second opening is notched below the rotation shaft.
[0018]
According to this structure, although it is a simple structure, the amount of fuel adhesion in an intake port can be reduced and a strong swirl can be generated.
[0019]
A fifth aspect of the present gun, in suction device of an engine according to any one of the aforementioned second to fourth, form an intake port straight across to the intake valve position near the position upstream of the intake flow control valve In addition, the downstream end of the common portion is disposed above the peripheral portion of the combustion chamber.
[0020]
According to this configuration, a high swirl ratio can be obtained while reducing the intake flow resistance.
[0021]
Sixth aspect of the present gun, in suction device of an engine according to any one of the above-described third to fifth, as in the operating range of part load close the intake flow control valve, at least the intake stroke in this operation range The fuel is injected in the first half.
[0022]
According to this configuration, fuel injection is performed in the first half of the intake stroke because of the partial load operation region where the fuel injection amount is small, so that the air-fuel mixture is centered in the combustion chamber (around the spark plug) while reducing the amount of fuel adhering in the intake port The air-fuel ratio in this operating region can be made leaner.
[0023]
According to a seventh aspect of the present invention, in the engine intake device according to the first or fifth aspect of the present invention, a second opening of the intake flow control valve is provided below the rotation shaft, and the intake air is controlled when the engine is cold. The flow control valve is configured to be closed.
[0024]
According to this configuration, the combustibility by swirl is enhanced while reducing the amount of fuel adhering in the intake port when the engine is cold.
[0025]
Eighth aspect of the present gun, in suction device of an engine according to any one of the above first to sixth, the angle of the fully closed valve face of the intake flow control valve with respect to the axis of the upstream intake port section 90 ° This is set to a substantially right angle state of ± 6 °.
[0026]
According to this configuration, a higher swirl ratio can be obtained while reducing the intake flow resistance.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. 1 and 2 show the overall structure of an intake device according to an embodiment of the present invention. In these drawings, the engine body composed of a cylinder block 1 and a cylinder head 2 and the like includes a plurality of cylinders, and a combustion chamber 3 is formed between each piston (not shown) and the lower surface of the cylinder head. The downstream end of the intake port 4 and the upstream end of the exhaust port 5 are opened in the combustion chamber 3.
[0028]
The intake port 4 has a common portion 4c that branches from the upstream port portion to the two downstream port portions 4a and 4b, and enters the combustion chamber 3 with the downstream port portions 4a and 4b aligned in the cylinder row direction. It is open. And each opening part of both the downstream port parts 4a and 4b is opened and closed by the intake valves 6 and 6, respectively.
[0029]
Above the intake port 4, a bulging portion 4 h is formed on the upstream side of the common portion 4 to guide the fuel spray injected in a forked manner from the injector 23 to the downstream port portions 4 a and 4 b. The exhaust port 5 also has two upstream port portions 5 a and 5 b that open to the combustion chamber, and each opening is opened and closed by the exhaust valve 7. A spark plug 8 is provided in the center of the combustion chamber 3.
[0030]
The intake manifold 10 connected to the engine body has an intake passage 12 for each cylinder connected to the surge tank 11, and these intake passages 12 are bent on the upstream side and linearly extend obliquely downward on the downstream side. The intake manifold 10 is connected to the cylinder head 2 with the downstream side of each intake passage 12 communicating with the intake port 4.
[0031]
A swirl control valve 15 (hereinafter referred to as SV15), which is an intake flow control valve for generating a swirl in the combustion chamber 3 by controlling the intake flow, is provided on the upstream side of the intake port 4. . The SV 15 is located in the vicinity of the downstream end of the intake passage 12 and is rotatable from a fully closed state to a fully opened state around a rotation shaft 16 extending in the cylinder row direction (a direction in which both downstream port portions 4a and 4b are arranged). It has become.
[0032]
The rotating shaft 16 extends rotatably across each intake passage 12 and is rotatably supported by a support portion 17 provided at an end portion on the downstream side of the intake manifold 10. It is connected to the actuator 20 via a link 18 and a rod 19. The support portion 17 is provided with a stopper 21 that contacts the link 18 when the SV 15 is fully closed, and a stopper 22 that contacts the link 18 when the SV 15 is fully opened.
[0033]
The SV 15 is provided with a first opening 150 and a second opening 151, each of which is partially cut away from the periphery. In this embodiment, as shown in FIG. 2 and as shown in FIG. 4 which is a cross-section IV-IV of FIG. A first opening 150 cut out in the vertical direction across the rotation shaft 16 is provided at one side of the center line C in the longitudinal direction of the circular SV 15. The size of the first opening 150 is preferably set in a range of 0.25 to 0.45 times the intake passage area of the SV15 arrangement portion.
[0034]
In addition, the SV 15 has a second opening cut out below the rotating shaft 16 at the other side of the center line C so as to correspond to the downstream port 4b on the other side (hereinafter referred to as the S port 4b). 151 is provided, and the second opening 151 is located between the center line C in the axial direction of the rotating shaft 16 and the other end, and from the valve shaft 6a of the intake valve 6 of the S port 4b. This corresponds to the collision position of the fuel spray F from the P port 4a side. As shown in FIG. 8, the size of the second opening 151 is preferably set to an opening area a of 20% or less with respect to the area A of the first opening 150 in order to obtain a high swirl ratio. .
[0035]
As shown in FIG. 6, the valve body shape of the SV 15 is such that the first opening 150 is formed by an upper notch 150a and a lower notch 150b in consideration of the attachment of the rotating shaft 16. Yes. C is a center line of the SV 15 in the direction of the rotation shaft 16, 151 is a second opening, and 152 is a screw-up hole for attaching the rotation shaft 16.
[0036]
The shape of the opening portion of the SV 15 is not limited to that shown in FIG. 4. For example, as shown in FIG. 7 , the second opening portion 30 b may be formed by the intake manifold 30 that forms the intake passage 12 and the SV 35. Good. Incidentally, Oite 10a in FIG. 4 is a mounting hole of an intake Manihodo 10 side of the injector 23. In FIG. 7 , reference numeral 350 denotes a first opening formed by an upper notch 350a and a lower notch 350b. Reference numeral 30a denotes a mounting hole for the injector 23 on the intake manifold 30 side.
[0037]
FIG. 3 shows the SV15 in a fully closed state. As shown in FIG. 3, the angle α of the valve surface when the SV15 is fully closed is an axis L (in FIG. 3) extending from the downstream side of the intake passage 12 to the upstream side of the intake port 4. More specifically, sin6 ° = 0.1 (10%) is considered as the tolerance of assembly of SV15, and the valve surface of SV15 when fully closed with respect to the above axis is regarded as the tolerance of assembly of SV15. The angle α is set in the range of 90 ° ± 6 °. The arrangement of the stoppers 21 and 22 is set so that the SV 15 can be opened and closed over the fully closed state and the fully opened state in which the valve surface of the SV 15 is substantially in the same direction as the axis L.
[0038]
The opening / closing operation of the SV 15 by the actuator 20 is controlled according to the operating state by a control unit (not shown), and the SV 15 is fully closed in a predetermined operating range. For example, the SV 15 is fully closed in the partial load operation region. Alternatively, the SV 15 is fully closed when the engine is cold.
[0039]
The intake passage 12 and the intake port 4 are formed in a straight shape from at least the position where the SV 15 is arranged to the downstream end 4d of the common portion 4c (a position where both the ports 4a and 4b are completely separated), and particularly shown in the drawing. In the embodiment, the intake port 4 is formed in a straight shape from a position upstream from the SV 15 to a position in the vicinity of the intake valve 6, and the downstream end 4 d of the common portion 4 c is positioned above the peripheral portion of the combustion chamber 3. Is arranged.
[0040]
The injector 23 provided above the downstream end side of the intake passage 12 has a fuel spray center line FC, FC injected in a bifurcated manner on the front side of the umbrella portion 6a of the intake valve 6 at both ports 4a, 4b. In the direction in which both ports 4a and 4b are arranged (on the intake upstream side), the direction from the valve shaft 6b toward the center of the combustion chamber 3 is directed.
[0041]
According to the intake device of the present embodiment as described above, when the SV 15 is fully closed in the partial load operation region, the intake air flowing downstream through the first opening 150 of the SV 15 causes P-port. A swirl is generated in the combustion chamber 3 via the throat 4a. In this case, a small amount of intake air passing through the second opening 151 does not cause a backflow of intake air in the S port 4b, and the amount of fuel adhering in the S port 4b can be suppressed to a low level. The attenuation of the intake air flow velocity at the port 4a is small.
[0042]
These actions will be specifically described with reference to FIGS. In addition, the swirl ratio shown in FIG. 8 and FIG. 11 means the swirl ratio by an impulse meter.
[0043]
FIG. 8 is data showing the relationship between the ratio of the opening area a of the second opening 151 to the opening area A of the first opening 150 and the swirl ratio, and a / A of SV15 is In the fully closed state, the swirl ratio is set to about 18%, which is 20% or less that can be maintained high. The ratio of the opening area A of the first opening 150 to the cross-sectional area of the intake passage 12 where the SV 15 is arranged is set to about 30%.
[0044]
FIG. 9 is simulation data for examining the flow of intake air in the intake port 4 when the SV 15 is fully closed, and FIG. 10 is actual measurement data for examining the behavior of fuel spray in the intake port 4 in this state. It is. FIG. 9 represents the intake flow in the intake port as a vector (arrow), and the longer the arrow, the higher the intake flow velocity and the denser the intake flow. FIG. 10 shows the behavior of the fuel spray in the intake port 4 after that in the fuel injection in the first half of the intake stroke after the end of injection near the 60 deg crank angle after the top dead center. In these drawings, (a), (b), and (c) indicate the respective crank angle points within the same intake stroke period.
[0045]
According to SV15 on the data of Figure 9 in a state where a fully closed, intake air flow past the first opening 150 of SV15 is the ATDC60deg shown in FIG. 9 (a), P port - DOO 4a, S port - DOO 4b to both produce a forward air flow, the ATDC90deg shown in FIG. 9 (b), mainly P port - DOO 4a to produce a forward air flow, the ATDC120deg shown in FIG. 9 (c), substantially Only the P port 4a generates a forward intake flow. A small amount of intake air flow that has passed through the second opening 151 suppresses the growth of vortices due to the intake air flow that has passed through the first opening 150 that wraps around the back side of the SV 15 (vortices W1, W2, (See W3), there is no reverse flow of the intake of the S port 4b even at the ATDC 120 deg after the middle of the intake stroke. Since the SV 15 is closed at a substantially right angle with respect to the axis L of the intake passage 12, it is possible to prevent the intake air flow that has passed through the first opening 150 from entering the back side of the SV 15 as compared with the case where the SV 15 is closed at an angle. Therefore, the growth of vortices generated on the back side of the SV 15 is suppressed.
[0046]
As shown in FIG. 11, the swirl ratio of the specification (1) of the first embodiment is much lower than the specification (3) having only the first opening 150 equivalent due to such intake air flow. A high swirl ratio is obtained. The specification (2) is a specification of the reference example and is based on the shape of the SV 25 shown in FIG. In FIG. 5, the second opening 251 is positioned above the rotation shaft 16. In FIG. 5, 10a is a mounting hole for the injector 23 on the intake manifold 10 side, 250 in FIG. 5 is a first opening, and as shown in FIG. 6 (b), an upper notch 250a and It is formed by a notch 250b on the lower side. Reference numeral 252 denotes a screw-up hole for attaching the rotating shaft 16.
[0047]
Furthermore, the behavior of the fuel spray in the intake port 4 due to the intake air flow is such that the fuel spray F stays in the intake port 4 as shown in FIGS. 10 (a), (b), and (c). (Particularly, there is no retention of the fuel spray F in the S port 4b at ATDC 120 deg), and the amount of fuel adhering in the intake port 4 can be kept small. As shown in FIG. The ratio of the fuel adhering amount in the intake port to the total fuel injection amount in the configuration specification (1) is considerably smaller than the specification (3) having only the first opening 150 equivalent. The specification (2) is a specification of the reference example and is based on the shape of the SV 25 shown in FIG.
[0048]
In the partial load operation region, SV15, SV25, and SV35 are closed, and the fuel is injected into the first half of the intake stroke for each cylinder by the injector 23, whereby the lean burn operation is performed. At this time, the air-fuel mixture is stratified around the spark plug while the amount of fuel adhering in the intake port 4 is kept small, and stratified combustion is promoted. As a result, as shown in FIG. 13, the lean air-fuel ratio set value G2 can be set to the lean side, and the fuel efficiency is improved. In this figure, N1 shows the tendency of NOx emission from the combustion chamber with respect to the air-fuel ratio, and N2 shows the tendency of NOx emission after passing through the catalyst with respect to the air-fuel ratio. G1 is a set value of the lean air-fuel ratio of the specification (3) having only the first opening 150 equivalent, and the specification (1) of the first embodiment is a catalyst for ΔN compared to this specification (3). NOx emissions after passing are reduced.
[0049]
As the control of the SV15, the SV15 may be closed when the engine is cold, and in this way, fuel vaporization is performed by both the first opening 150 and the second opening 151. flammability of the cold is improved by promotion of atomization.
[0050]
【The invention's effect】
In the present invention, when the intake flow control valve is fully closed, the swirl can be effectively generated while suppressing the amount of fuel adhering in the intake port, and the fluctuation of the air-fuel ratio between cycles and between cylinders is reduced. can do.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an intake device according to an embodiment of the present invention.
FIG. 2 is a partially cutaway schematic plan view showing the intake device.
FIG. 3 is an enlarged cross-sectional view of an intake flow control valve arrangement portion.
4 is a cross-sectional view taken along the line IV-IV in FIG. 1, showing a first example of the opening of the intake flow control valve.
FIG. 5 is a view showing a reference example of an opening of an intake flow control valve.
6A and 6B show the shape of the valve body of the intake flow control valve, wherein FIG. 6A is a diagram showing the first example, and FIG. 6B is a diagram showing the reference example .
FIG. 7 is a view showing a second example of the opening of the intake flow control valve.
FIG. 8 is data showing the relationship between the ratio of the opening area a of the second opening to the opening area A of the first opening and the swirl ratio.
FIGS. 9A, 9B and 9C are simulation data obtained by examining the flow of intake air in the intake port for each crank in the intake stroke when the intake flow control valve of the present embodiment is fully closed. .
FIGS. 10A, 10B, and 10C are measured data obtained by examining the behavior of fuel spray in the intake port for each crank in the intake stroke when the intake flow control valve of the present embodiment is fully closed. .
FIG. 11 is actual measurement data showing a swirl ratio according to each embodiment.
FIG. 12 is actual measurement data showing the ratio of the fuel adhesion amount in the intake port to the total fuel injection amount according to each embodiment.
FIG. 13 is a diagram showing the relationship between the set value of the lean air-fuel ratio and the NOx emission amount with respect to the air-fuel ratio.
FIG. 14 is a view showing an example of an opening of an intake flow control valve provided with only one opening, which is a comparison object with the configuration of the present invention.
FIGS. 15A, 15B, and 15C show the flow of intake air in the intake port for each crank in the intake stroke when the intake flow control valve of the configuration of the present invention and the comparison target example are fully closed. It is the simulation data which investigated.
FIG. 16 is a diagram schematically showing the flow of intake air in FIG. 15 (c).
17 (a), (b) and (c) show the state of fuel spray in the intake port for each crank in the intake stroke when the intake flow control valve of the configuration of the present invention and the comparison target example are fully closed. It is the simulation data which investigated the behavior .
[Explanation of symbols]
3 Combustion chamber 4 Intake port 4a, 4b Downstream port 4c Common 6 Intake valve 10 Intake manifold 15, 25, 35 SV
150, 250, 350 First opening 151, 251, 30b Second opening 16 Rotating shaft 23 Injector

Claims (8)

An intake port having a common portion bifurcated from the upstream port portion to the two downstream port portions, the downstream ends of both downstream port portions each opening to the combustion chamber via an intake valve, and an opening portion partially cut away And an intake flow control valve disposed at an upstream position separated from the common portion, and a fuel injection valve for injecting fuel to each of the downstream port portions, and the intake flow control valve is disposed in a predetermined operating range. In an intake system of an engine that generates swirl in the combustion chamber by closing,
A first opening for generating an intake main flow with respect to the downstream port portion on one side of the downstream port portions is provided on one side portion of the intake flow control valve in the row direction in which the both downstream port portions are arranged, A second opening that generates an auxiliary intake air flow with respect to the downstream port portion on the other side of the downstream port portions at the other side portion in the row direction of at least one of the intake port wall and the intake flow control valve. And setting the size of the second opening smaller than the first opening provided apart from the second opening ,
An engine in which a bulge space where the tip of the fuel injection valve is provided is provided above the intake port downstream of the intake flow control valve, and the second opening is provided in a downwardly biased manner. Inhalation device.   The first opening is provided in the row direction so as to be biased to the one side from the center position of the intake flow control valve, and the area ratio of the second opening to the first opening is 20% or less. 2. The engine intake system according to claim 1, wherein   Fuel is bifurcatedly injected from one fuel injection valve to both downstream port portions, and the intersection of this fuel injection center line and the inner wall of the downstream port portion in the vicinity of the intake valve or intake valve is defined as both intake air in the row direction. 2. The valve shaft of the valve is set within a range from the valve shaft, and the second opening is provided away from the other end of the intake flow control valve in the row direction. Engine intake system. A rotation shaft that enables the intake flow control valve to rotate from a fully closed state to a fully open state is provided in the row direction, and the first opening is notched in a vertical direction across the rotation shaft. 3. The engine intake system according to claim 2, wherein the second opening is notched below the rotating shaft. The intake port is formed in a straight shape from a position upstream from the intake flow control valve to a position near the intake valve, and the downstream end of the common portion is disposed above the peripheral portion of the combustion chamber. The intake device for an engine according to any one of claims 2 to 4 , characterized in that: In operation range of part load to close the intake flow control valve, at least the operation range by the intake device for an engine according to claim 1 or 3 to 5, characterized in that to the fuel injected into the intake stroke first half . The second opening of the intake flow control valve is provided below the rotating shaft, of an engine according to claim 1 or 5, characterized in that to close the intake flow control valve during cold engine Intake device. The engine according to any one of claims 1 to 6 , wherein the angle of the valve surface when the intake flow control valve is fully closed with respect to the axis of the upstream intake port portion is set to a substantially right angle state of 90 ° ± 6 °. Inhalation device.

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