JP2000186640A - Intake device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a manufacturing cost through simplification of the variable structure of the intake system of a V-type engine and to prevent the occurrence of unevenness in valve operation between right and left banks. SOLUTION: An intake manifold comprises an intake manifold parallel part 2 at which the main passage parallel part 11 of each cylinder is formed and an intake manifold branch part 3 having a main passage 12 branched into the right and left banks. A disc-form main passage cutoff valve 4 to control opening and closing of each passage is arranged in a position where the main passage 12 crosses the right and left banks of the intake manifold branch part 3. The main passage cutoff valve is fixed on a single shaft 5 by means of screws 8. At each cylinder, two auxiliary passages 13 have end parts on one side opened to a spot situated right upper stream from the main passage cutoff valve 4 and the end part on the other side are confluent to the main passage 12 at a connection part between cylinder heads 6 and 7 and the intake manifold branch part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an intake system for an internal combustion engine, and more particularly to an intake system for an internal combustion engine employing a V-shaped or horizontally opposed cylinder arrangement.

[0002]

2. Description of the Related Art Conventionally, in order to achieve both fuel consumption performance and output performance of an internal combustion engine, an intake device is provided with a main passage shutoff valve for controlling opening and closing of a main passage, and a sub passage which bypasses the main passage shutoff valve. There is known a technology in which a main passage shutoff valve is closed and air is taken in only from a sub passage in a middle to low speed rotation region, and a main passage shutoff valve is opened in a high rotation speed region to intake air from both a main passage and a sub passage.

[0003] According to such an intake device, in the middle and low speed rotation region, the gas flow in the combustion chamber is enhanced by the intake from the sub-passage to realize stable lean combustion, and in the high rotation region, air is sucked from both passages. Thus, the intake resistance can be reduced, and a high output can be obtained by homogeneous combustion with a large amount of intake air.

An example in which such an intake device having a main passage shut-off valve and a sub passage is applied to a V-type engine having left and right banks is disclosed, for example, in Japanese Patent Application Laid-Open No. Hei 6-10859. According to this conventional technique, as shown in FIG. 7, an independent intake passage for each cylinder of a V-type six-cylinder engine has a primary passage 63a (corresponding to the sub passage) and a secondary passage 63b (corresponding to the main passage). ), And a control valve 68 (corresponding to the above-described main passage shut-off valve) for switching between the flow and the shutoff of the intake air to each secondary side passage 63b is provided.

[0005] Then, three control valves 68 are provided for each bank so as to be switched between an intake cutoff state and an intake supply state by two actuators 69 provided independently for the left and right via shafts for the left and right banks. I have.

When these control valves 68 are closed, the intake air is supplied into the combustion chamber only from the primary side passage 63a, and swirl is generated in the combustion chamber by the intake air. When the control valve 68 is opened, The intake air is supplied from both the primary side passage and the secondary side passage into the combustion chamber, so that the swirl is eliminated or weakened.

[0007]

However, in the above-mentioned conventional intake system, the main passage shut-off valves of the left and right banks are controlled by left and right independent actuators via different shafts, respectively. The structure is complicated and the manufacturing cost increases, and the operation of the main passage shutoff valve varies between the left and right banks. The intake shutoff is not sufficient when the valve is closed, or the valve cannot be opened even when the valve is open, increasing the intake resistance. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to simplify the variable structure of the intake system to suppress the manufacturing cost and to reduce the variation in valve operation between the left and right banks. An object of the present invention is to provide an intake device for an internal combustion engine that can be eliminated.

[0009]

According to the first aspect of the present invention,
In order to solve the above problems, in an intake device for an internal combustion engine in which a plurality of cylinders forming left and right banks are arranged in a V-shape or horizontally opposed type, a main passage to each cylinder in a left bank and each cylinder in a right bank A main passage shut-off valve that controls opening and closing of the main passage to each cylinder of the left and right banks with one shaft at a position where the main passage intersects with the main passage, and one end is opened immediately upstream of the main passage shut-off valve. A sub-passage having the other end opened downstream of the main-passage shut-off valve.

According to a second aspect of the present invention, there is provided an intake system for an internal combustion engine according to the first aspect, wherein
The gist of the invention is that the shape of the main passage shutoff valve is circular. According to a third aspect of the present invention, there is provided an intake system for an internal combustion engine according to the first or second aspect, wherein each of the main passages is provided above the main passage in a crankshaft direction of the internal combustion engine. The gist is that two sub-passages are provided with the.

According to a fourth aspect of the present invention, there is provided an intake system for an internal combustion engine having a main passage controlled by a main passage shut-off valve for each cylinder and an auxiliary passage. The passage and the sub-passage diverge in the intake manifold, merge at the cylinder head, and at the joining surface of the intake manifold to the cylinder head, the cross-sectional area of the main shape of the main passage is AS, the main passage and the sub-passage are If the protruding area of the boss of the sub-passage at the part where the diverging portion protrudes from the main passage is AB, and the cross-sectional area of the sub-passage is AF, (AS-AB) / AS> 0.7, (A
S−AB + AF) / AS> 0.9 so that
It is assumed that AS, AB, and AF are set.

According to a fifth aspect of the present invention, there is provided an intake system for an internal combustion engine having a main passage whose opening and closing are controlled by a main passage shutoff valve and a sub passage for each cylinder. The passage and the sub-passage diverge in the intake manifold, merge at the cylinder head, and at the joining surface of the cylinder head to the intake manifold, the cross-sectional area of the basic shape of the main passage is AS, the escape portion for the sub-passage. If the area of is An, then (AS
+ A N) / A S <A S <1.3.

According to a sixth aspect of the present invention, there is provided an intake system for an internal combustion engine having a main passage whose opening and closing are controlled by a main passage shut-off valve and a sub passage for each cylinder. The gist of the angle θF between the extension of the center line of the passage and the sliding direction of the piston is 50 ° to 70 °.

According to a seventh aspect of the present invention, there is provided an intake system for an internal combustion engine having a main passage, which is controlled to be opened and closed by a main passage shut-off valve, and a sub passage for each cylinder. The distance X between the intersection of the extension of the center line of the passage and the upper wall of the combustion chamber and the axis of the valve is set so that 0.12 <X / φ <0.5, where φ is the intake valve diameter. It is assumed that is set.

[0015]

According to the first aspect of the present invention, in an intake system for an internal combustion engine in which a plurality of cylinders forming left and right banks are arranged in a V-shape or horizontally opposed type, respectively, each cylinder of a left bank is connected to a cylinder of a left bank. A main passage shut-off valve for controlling opening and closing of a main passage to each cylinder of both the left and right banks by one shaft at a position where a main passage of the right bank intersects with a main passage to each cylinder of the right bank; By providing a sub-passage having one end opened immediately upstream of the valve and having the other end opened downstream of the main passage shut-off valve, the main passage shut-off valve is closed and the sub-passage is closed at the time of lean burn in a medium to low speed rotation region. Since fresh air can be introduced into the cylinder, the gas flow in the combustion chamber is increased, and lean fuel-air mixture is reliably burned for low fuel consumption operation. resistance Since reducing the large amount of fresh air can be introduced into the cylinder, there is an effect that it is possible to secure the output performance of the high speed range.

Further, since the opening and closing of the main passages of both the left and right banks can be controlled by operating one shaft, the structure of the intake device is simplified, and the opening and closing of the main passages of the left and right banks are eliminated. It is possible to switch the combustion mode in a simple manner, and to reduce the intake resistance when the main passage is opened to improve the output performance.

According to the second aspect of the present invention, since the shape of the main passage shutoff valve is circular, the airflow resistance when the main passage shutoff valve is opened is further reduced, and high output performance can be obtained. This has the effect.

According to the third aspect of the present invention, the main passage is closed by providing two sub passages above each of the main passages with the main passage interposed therebetween in the crankshaft direction of the internal combustion engine. In this case, the fresh air sucked through the sub-passage forms a tumble flow as a gas flow in the cylinder, and there is an effect that the lean combustion can be reliably obtained by the tumble flow.

According to a fourth aspect of the present invention, in the intake system for an internal combustion engine having a main passage whose opening and closing are controlled by a main passage shutoff valve and a sub passage for each cylinder, the main passage and the sub passage are provided. Means a portion that diverges in the intake manifold and joins at the cylinder head, and at the joining surface of the intake manifold to the cylinder head, the cross-sectional area of the basic shape of the main passage is AS, and the main passage and the sub-passage are divided. If the overhang area of the boss of the sub passage overhangs to the main passage is AB and the cross-sectional area of the sub passage is AF,
(AS-AB) / AS> 0.7 and (AS-AB + AF)
) / AS, AB, AF so that /AS>0.9 holds.
Is set, the airflow resistance when the main passage shutoff valve is opened with respect to the thickness of the entire intake manifold is optimized, and an effect that high output performance can be obtained.

According to a fifth aspect of the present invention, in the intake system for an internal combustion engine having a main passage whose opening and closing are controlled by a main passage shut-off valve and a sub passage for each cylinder, the main passage and the sub passage are provided. Means branching in the intake manifold and merging at the cylinder head, and at the joining surface of the cylinder head to the intake manifold, the sectional area of the basic shape of the main passage is AS, and the area of the relief portion for the sub passage is AN, Then, (AS + AN) / AS <
Since AS and AN were set so that 1.3 was satisfied, fresh air flowing into the cylinder head from the intake manifold was suppressed from separating from the passage wall surface, and the expansion loss was reduced, and the main passage shut-off valve was opened. This has the effect of optimizing the airflow resistance at the time and obtaining high output performance.

According to the sixth aspect of the present invention, in an intake device for an internal combustion engine having a main passage whose opening and closing are controlled by a main passage shut-off valve and a sub passage for each cylinder, the center line of the sub passage is Angle θF between extension and piston sliding direction
Is arranged so as to be at 50 ° to 70 °, so that when closing the main passage shut-off valve and sucking fresh air only from the sub passage,
This produces the effect that smooth gas flow rotation occurs in the cylinder and a strong tumble flow is obtained.

According to the seventh aspect of the present invention, in an intake system for an internal combustion engine provided with a main passage of which opening and closing is controlled by a main passage shutoff valve and a sub passage for each cylinder, the center line of the sub passage is The distance X between the intersection of the extension and the upper wall of the combustion chamber and the valve shaft center is 0.12 <X if the intake valve diameter is φ.
Since X is set so that /φ<0.5 holds, when closing the main passage shut-off valve and sucking fresh air only from the sub passage,
This has the effect of reducing the resistance of the intake valve and obtaining a strong tumble flow.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of a main part showing a configuration of an embodiment of an intake device for an internal combustion engine according to the present invention,
Although an example in which the present invention is applied to a V-type six-cylinder engine is shown, the present invention is applicable to an engine having a different number of cylinders and a horizontally opposed engine.

As shown in FIG. 1, an intake device 1 for an internal combustion engine
The main passage parallel portion 11 for each cylinder of the left and right banks is formed in parallel, and one end 13 of the sub passage 13 for each cylinder.
Intake manifold parallel parts 2 each opening a
An intake manifold branch portion 3 connected to the outlet side of the intake manifold parallel portion 2, each main passage 12 is formed so as to branch for the right bank and the left bank, and has each sub passage 13; Six main passage shutoff valves 4 provided in the section 3 for opening and closing the main passages 12 for the respective cylinders, and the intake manifold branching section 3 is vertically penetrated in the front-rear direction of the engine (crankshaft direction), and each main passage is shut off. One rotatable shaft 5 to which the valve 4 is fixed is connected to the left bank outlet of the intake manifold branching portion 3 and the main passage 12 and the sub passage 13 for each cylinder of the left bank are merged. The left bank cylinder head 6 is connected to an outlet for the right bank of the intake manifold branching section 3 and has a main passage for each cylinder of the right bank. 12 and a right bank cylinder head 7 for combining the sub-passage 13, and a.

Each of the left bank cylinder head 6 and the right bank cylinder head 7 has an intake port 14 for each cylinder,
An exhaust port 15, a combustion chamber 16, two intake valves 17 for each cylinder, and two exhaust valves 18 for each cylinder are provided.

The intake manifold parallel portion 2 introduces the intake air purified by an air cleaner (not shown) into the main passage parallel portion 11 for each cylinder via an intake collector (not shown). Further, at the end of the intake manifold parallel part 2 on the side of the intake manifold branching part 3, one end 13a of the sub-passage 13 for each cylinder is opened.
The main passage parallel portion 11 is branched into a main passage 12 for each cylinder and two sub-passages 13 for each cylinder.

FIG. 2 shows the intake manifold branch 3
FIG. 5 is a view showing a joint surface of the intake manifold with the intake manifold parallel part 2. As shown in the drawing, a main passage 12 having a circular cross section perpendicular to an axis is formed for each cylinder, and two sub-passages 13 are formed for each cylinder.

Returning to FIG. 1 again, the shaft 5 is provided in the intake manifold branching section 3 immediately below the joint surface with the intake manifold parallel section 2 so as to be orthogonal to the center line of each main passage 12 in the engine front-rear direction. The main passage shut-off valve 4 using a metal disk is fixed to the shaft 5 by a screw 8 for each main passage 12.

When the shaft 5 is rotated by an actuator such as a motor (not shown), each main passage shut-off valve 4 becomes parallel or perpendicular to the main passage axis, and the main passage 12 for each cylinder is fully opened. It can be switched between the state and the fully closed state.

Therefore, the right bank and the left bank can simultaneously open and close the main passage shut-off valve 4 by the rotation of the single shaft 5, and can also eliminate the variation in the opening and closing operations of the left and right banks. it can. Further, the structure of the drive system for driving the main passage shutoff valve is simplified, and the manufacturing cost and the maintenance cost can be reduced.

The internal combustion engine provided with the intake device 1 has two combustion modes, a lean combustion mode in which the fuel consumption performance in the low-speed rotation region is emphasized, and an output combustion mode in which the output performance in the high-speed rotation region is emphasized. It has.

That is, in the lean combustion mode in the low-to-medium-speed rotation region, the main passage shut-off valve 4 is closed to take in air only from the sub passage 13 to generate a tumble flow in the combustion chamber 16.
The lean mixture can be reliably burned by this tumble flow.

In the output combustion mode in the high-speed rotation region, the main passage shut-off valve 4 is opened, and a large amount of fresh air is taken in from the main passage 12 and the sub passage 13 to obtain a high output.

FIG. 3 shows the intake manifold branch 3
FIG. 3 is a view showing an intake manifold side (a), a cylinder head side (b), and a side surface (c) of an intake port 14 of a joint surface between the cylinder head 7 and a right bank cylinder head 7.

In the intake manifold parallel part 2 of FIG. 1, the sub-passage 13 branched from the main passage parallel part 11 immediately upstream of the main passage shut-off valve 4 is a separate passage from the main passage 12 in the intake manifold branch part 3. Make up,
The main passage 12 and the sub-passage 13 are joined at the junction between the intake manifold branch portion 3 and the cylinder heads 6 and 7 of the left and right banks.

In FIG. 3A, which is a cross-sectional view of the junction at the intake manifold branch 3 side, two sub-passages 13 having a circular cross section and a boss of the sub-passage with respect to the basic shape of an ellipse are shown. The main passage 12 having an overhanging shape is open.

The sectional area of the elliptical main passage basic shape cross section is AS, the projecting area of the projecting portion of the sub passage boss projecting into the main passage basic shape is AB (total of two projecting portions),
If the sectional area of the sub passage is AF (for two sub passages), (A
S−AB) / AS> 0.7 and (AS−AB + AF) /
AS, AB, and AF are set so that AS> 0.9 is satisfied.

The reason is that if (AS-AB) / AS is 0.7 or less, that is, if the ratio AB / AS of the overhang portion of the boss for the sub passage to the basic shape of the main passage is 0.3 or more, This is because the flow of the intake air in the main passage is separated by the sub passage boss overhang, and the ventilation resistance rapidly increases. If (AS -AB + AF) / AS does not exceed 0.9, the intake resistance increases due to a decrease in the effective passage cross-sectional area when branching into the main passage and the sub-passage.

FIG. 3B is a cross-sectional view of the joining portion between the intake manifold branching portion 3 and the cylinder heads 6 and 7 of the left and right banks on the cylinder head side.
A substantially concave intake port 14 having a round cross section at each corner is open. The shape of this intake port opening is
It has a shape in which two sub-passage relief portions are added to the oval main passage basic shape.

Assuming that the cross-sectional area of the oval main passage basic shape cross-section is AS and the area of the auxiliary passage escape portion is AN (total of two locations), (AS + AN) / AS becomes smaller than 1.3. Is set as follows.

The reason is that if (AS + AN) / AS is 1.3 or more, that is, if AN / AS is 0.3 or more, the separation of the intake air occurs at the time of expansion from the main passage to the escape portion for the sub passage. This is due to a sudden increase in ventilation resistance.

FIG. 4 is a graph showing the tendency as a result of simulating the ventilation resistance by changing the ratio of AB, AF and AN to AS. FIG. 4A is a graph showing the tendency of a result obtained by simulating a change in airflow resistance with respect to (AS-AB) / AS with the sub-passage closed. As can be seen from the figure, (AS -AB) / AS = 1.0
As (AS−AB) / AS decreases (AB increases) from (AB = 0), the airflow resistance gradually decreases, but the airflow sharply increases at (AS−AB) /AS=0.7 as a boundary. Peeling occurs and ventilation resistance deteriorates.

FIG. 4B shows (AS-AB + AF) / A
9 is a graph showing a tendency of a result of simulating a change in airflow resistance with respect to S 2. As shown in FIG.
In the region where (AB + AF) / AS is 0.9 or more, the ventilation resistance is almost constant, and (AS-AB + AF) / AS is 0.9.
In the following regions, as (AS-AB + AF) / AS decreases, the effective passage cross-sectional area decreases and the ventilation resistance deteriorates.

FIG. 4C is a graph showing the tendency of the simulation result of the change of the airflow resistance with respect to (AS + AN) / AS. As shown in the figure, (AS + AN)
In the region where / AS is less than 1.3, the airflow resistance is almost constant, but when (AS + AN) / AS exceeds 1.3, the passage expansion when flowing into the cylinder head from the main passage of the intake manifold becomes large. As a result, the separation of the intake air from the wall surface occurs, and the airflow resistance increases rapidly.

FIG. 5 is a graph (a) showing the result of simulating the intensity of the tumble flow with respect to the angle θF between the extension of the center line of the auxiliary passage and the sliding direction of the piston, and FIG.
It is a schematic diagram which shows the example of a flow in the combustion chamber when F is excessive (b), appropriate (c), and excessive (d). According to FIG. 5 (a), the tumble strength is the strongest when θF is about 65 °, and as shown in FIG. 5 (c), the intake air becomes a large and strong tumble flow that recirculates in the entire combustion chamber.

As θF decreases from 65 °, the tumble strength gradually decreases, and in a region where θF is too small, FIG.
As shown in (d), the intake air is divided into a flow along the piston crown which is the bottom of the combustion chamber and a flow along the cylinder wall,
A strong tumble flow cannot be obtained. ΘF is 65
As the angle increases from 0 °, the tumble strength rapidly decreases, and in a region where θF is excessive, the intake air is divided into a flow toward the ceiling of the combustion chamber and a flow along the cylinder wall surface, and a strong tumble flow cannot be obtained. Therefore, the proper range of θF is 50 ° to 70 °.

FIG. 6 shows the intake valve diameter φ at a distance X between the intersection of the extension of the center line FTCL of the sub passage and the upper wall of the combustion chamber and the intake valve axis (the center line of the intake valve is indicated by IVCL).
(A) showing the result of simulating the change in the tumble strength with respect to X / φ when the ratio to X / φ is X / φ, and X / φ being too small (b), appropriate (c), and excessive (d). It is a figure showing the example of each case.

According to FIG. 6A, X / φ is about 0.35
When tumble is strong in the range of 0.12 <X / φ <0.5, and X / φ is too small, FIG.
As shown in (2), the intake air from the auxiliary passage 12 is blocked near the center of the intake valve, the intake resistance increases, and the intensity of the intake air flowing into the combustion chamber decreases, so that the intensity of the tumble decreases. Conversely, if X / φ is excessive, as shown in FIG. 6D, the intake air from the sub-passage 12 is repelled to the intake port side wall, which also increases the intake resistance and increases the combustion chamber. The strength of the tumble is reduced because the strength of the intake air flowing into the air is reduced.

As a result, as shown in FIGS. 6A and 6C, the distance X between the extension of the center line FTCL of the auxiliary passage and the intersection of the upper wall of the combustion chamber and the center line IVCL of the intake valve is determined. A strong tumble strength can be obtained in the range of 0.12 to 0.5 times the intake valve diameter φ.

As described above, in the present invention, by forming the intake passage in the above numerical range, the passage resistance when the main passage shut-off valve is opened is small, and when the main passage shut-off valve is closed, An intake device for an internal combustion engine capable of obtaining a strong tumble flow in a combustion chamber can be provided.

In this embodiment, two sub-passages are provided above the main passage of each cylinder so as to sandwich the main passage in the crankshaft direction, so that the tumble flow into the combustion chamber is achieved. Although a case has been shown, the swirl flow can be formed in the combustion chamber by providing one or two sub-passages for each cylinder and providing them asymmetrically in the crankshaft direction.

In this embodiment, an example in which the present invention is applied to a V-type six-cylinder engine has been described.
The present invention is also applicable to a V-type engine having a number of cylinders other than 6, such as 4, 8, 10, and the like, and a horizontally opposed engine having left and right banks similarly to the V-type engine. Furthermore, it goes without saying that the fourth, fifth, sixth and seventh aspects of the present invention can also be applied to, for example, an in-line cylinder engine and have the same effect.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part showing a configuration of an embodiment of an intake device for an internal combustion engine according to the present invention.

FIG. 2 is a cross-sectional view showing a shape of a joint between an intake manifold parallel portion and an intake manifold branch portion in FIG. 1;

FIG. 3 is a sectional view (a) showing the shape of a joint between an intake manifold branch and a cylinder head in FIG. 1,
(B) and an intake port side view (c).

FIG. 4 is a graph of simulation results showing the effect of the area of each part on the airflow resistance with respect to the main passage basic shape cross-sectional area AS, (a): airflow resistance with respect to (AS−AB) / AS, (b): ( The airflow resistance to (AS-AB + AF) / AS is shown, and the airflow resistance to (c) :( AS + AN) / AS is shown.

FIG. 5A is a graph showing the result of simulating the tumble strength with respect to the angle θF between the extension of the center line of the auxiliary passage and the sliding direction of the piston, and the schematic diagram of the tumble flow in the combustion chamber in each region of θF. b), (c), (d)
It is.

FIG. 6 shows the ratio of the distance X between the intersection of the extension of the center line FTCL of the sub passage and the upper wall of the combustion chamber and the intake valve axis (center line: IVCL) to the intake valve diameter φ as X / φ. , A graph (a) showing a result of simulating a change in tumble strength with respect to X / φ, and a diagram showing an example in each case where X / φ is too small (b), appropriate (c), and too large (d). .

FIG. 7 is a system configuration diagram showing a configuration of a conventional intake device for an internal combustion engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Intake device 2 Intake manifold parallel part 3 Intake manifold branch part 4 Main passage shutoff valve 5 Shaft 6 Left bank cylinder head 7 Right bank cylinder head 8 Screw 11 Main passage parallel part 12 Main passage 13 Sub passage 14 Intake port 15 Exhaust port 16 Combustion chamber 17 Intake valve 18 Exhaust valve

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G031 AA24 AA28 AB03 AB05 AB07 AB08 AB09 AC01 AC03 AC04 AD03 AD08 BA02 BA07 BB06 CA02 DA32 DA38 EA02 FA03 GA05 HA04 HA08 HA10

Claims (7)

[Claims] 1. An intake system for an internal combustion engine in which a plurality of cylinders forming left and right banks are arranged in a V-shape or horizontally opposed type, respectively, wherein a main passage to each cylinder of a left bank and a cylinder to each cylinder of a right bank are provided. A main passage shut-off valve for controlling opening and closing of the main passage to each of the cylinders of the left and right banks with a single shaft at a position where the main passage intersects; one end of which is opened immediately upstream of the main passage shut-off valve; An intake device for an internal combustion engine, comprising: a sub-passage having the other end opened downstream of the main passage shut-off valve. 2. The intake device for an internal combustion engine according to claim 1, wherein the shape of the main passage shutoff valve is circular. 3. The internal combustion engine according to claim 1, wherein two sub-passages are provided above each of the main passages so as to sandwich the main passage in the crankshaft direction of the internal combustion engine. Engine intake device. 4. An intake device for an internal combustion engine having a main passage whose opening and closing are controlled by a main passage shut-off valve and a sub passage for each cylinder, wherein the main passage and the sub passage are branched in an intake manifold. And at the joining surface of the intake manifold to the cylinder head, the sectional area of the basic shape of the main passage is AS
The area of the boss of the sub-passage where the main passage and the sub-passage diverge is projected to the main passage, AB, and the cross-sectional area of the sub-passage is A
F, (AS -AB) / AS> 0.7 and (AS
−AB + AF) / AS> 0.9
An intake device for an internal combustion engine, wherein S, AB, and AF are set. 5. An intake system for an internal combustion engine having a main passage whose opening and closing are controlled by a main passage shutoff valve and a sub passage for each cylinder, wherein the main passage and the sub passage are branched in an intake manifold. At the joining surface of the cylinder head and the intake manifold, the cross-sectional area of the basic shape of the main passage is defined as AS
Assuming that the area of the escape portion for the sub passage is AN, (AS +
An) An intake device for an internal combustion engine, wherein AS and AN are set such that the following condition is satisfied. 6. An intake system for an internal combustion engine having a main passage whose opening and closing are controlled by a main passage shut-off valve and a sub passage for each cylinder, wherein an extension of a center line of the sub passage, a sliding direction of a piston, Wherein the angle θF is between 50 ° and 70 °. 7. An intake system for an internal combustion engine having a main passage whose opening and closing are controlled by a main passage shut-off valve and a sub passage for each cylinder, wherein an extension of a center line of the sub passage and an upper wall of a combustion chamber are provided. X is set so that 0.12 <X / φ <0.5 is satisfied, where X is the diameter of the intake valve. Intake device.