CN117948208A

CN117948208A - Throttle valve device and air suction system

Info

Publication number: CN117948208A
Application number: CN202310996614.9A
Authority: CN
Inventors: 田中直记; 岩间和茂
Original assignee: Mikuni Corp
Current assignee: Mikuni Corp
Priority date: 2022-10-27
Filing date: 2023-08-09
Publication date: 2024-04-30
Also published as: JP2024064142A

Abstract

The invention provides a throttle valve device and an air suction system, which can reduce the number of parts, simplify the structure, lower the cost and reduce the passage resistance. The throttle valve device includes: a throttle body defining a main passage that constitutes a part of the main intake passage and a sub-passage that branches from the main passage and constitutes a part of the sub-intake passage; and a butterfly valve that rotates around an axis in order to open and close the main passage, the butterfly valve including: an opening/closing plate having a first half portion that moves toward the upstream side and a second half portion that moves toward the downstream side when the valve is opened; and a protruding portion protruding downstream from the first half portion in the valve-closed state, wherein the branch port of the sub-passage is located downstream of the opening/closing plate in the valve-closed state, and is formed at a position facing the second half portion when the butterfly valve is opened, and wherein an opening area communicating with the main passage upstream of the opening/closing plate increases according to an opening degree of the butterfly valve until the butterfly valve reaches a predetermined opening degree.

Description

Throttle valve device and air suction system

Technical Field

The present invention relates to a throttle device and an intake system for an internal combustion engine mounted on a vehicle, for example, a motorcycle.

Background

As an intake system of a conventional internal combustion engine, an intake system including: an intake passage that guides air (intake air) introduced from the outside to a combustion chamber of the internal combustion engine; an intake valve for opening and closing an intake port constituting a part of the intake passage; an injector disposed in the vicinity of the intake port and injecting fuel; a first throttle valve disposed in the middle of the intake passage and opening and closing the intake passage; a second throttle valve disposed downstream of the first throttle valve and opening and closing the intake passage; and a sub-passage that branches from the suction passage between the first throttle valve and the second throttle valve and merges with the downstream side of the injector (for example, refer to patent document 1).

In the intake system, at the time of partial load, only the first throttle valve on the upstream side is opened in a state where the second throttle valve on the downstream side is closed, and air introduced from the outside is made to flow to the sub-passage and is guided to the passage on the downstream side of the injector, and is mixed with the injected fuel, whereby atomization of the fuel is promoted.

However, in the above-described intake system, since two throttle valves (first throttle valve and second throttle valve) are rotatably provided in a main body defining an intake passage and are individually opened and closed, two throttle valves are required, and a mechanism for opening and closing each throttle valve is required, which leads to an increase in the number of parts, an increase in cost, and a complication in the structure. Further, at the time of full opening, since two throttle valves are arranged in the passage, the passage resistance increases compared to the case of one throttle valve.

As another air intake system, an air intake apparatus is known which includes: an intake pipe defining an intake passage that guides intake air introduced from the outside to a combustion chamber of the internal combustion engine; an intake valve that opens and closes an intake passage at a position facing the combustion chamber; an injector provided in the intake pipe for injecting fuel in the middle of the intake passage; a throttle valve provided in an intake pipe for opening and closing an intake passage; a partition plate that partitions the intake passage into an upper intake passage and a lower intake passage at a downstream side of the throttle valve; and an intake distribution valve provided in the intake pipe at a position downstream of the throttle valve and adjacent to an upstream end edge of the partition plate, wherein the intake device changes the ratio of air flowing through the upper intake passage and the lower intake passage by rotating the intake distribution valve appropriately (for example, refer to patent document 2).

However, in the above-described intake device, an intake distribution valve is required, and a mechanism for driving the throttle valve and the intake distribution valve separately is required, which results in high cost and complicated structure. When the throttle valve is fully opened, the shaft supporting the intake air distribution valve and the intake air distribution valve becomes an obstacle to the flow of intake air, and the passage resistance increases.

[ Prior Art literature ]

[ Patent literature ]

[ Patent document 1] Japanese patent laid-open No. 2002-327665

[ Patent document 2] Japanese patent publication No. 5925878

Disclosure of Invention

[ Problem to be solved by the invention ]

The present invention has been made in view of the above circumstances, and an object thereof is to provide a throttle valve device and an intake system capable of increasing a flow rate of intake air flowing through a sub intake passage and generating swirling flow such as swirl flow or tumble flow in a combustion chamber by reducing the number of components, simplifying the structure, reducing the cost, reducing the passage resistance, and the like.

[ Means of solving the problems ]

The throttle device of the present invention is applied to an intake system of an internal combustion engine including: a main intake passage that guides intake air to the combustion chamber and is opened and closed by an intake valve at a position facing the combustion chamber; and a sub-intake passage that branches from a middle portion of the main intake passage and merges with the main intake passage on an upstream side of the intake valve, the throttle device including: a throttle body defining a main passage that constitutes a part of the main intake passage and a sub-passage that branches from the main passage and constitutes a part of the sub-intake passage; and a butterfly valve that rotates around a predetermined axis in order to open and close the main passage, wherein the throttle device is configured to: the butterfly valve includes: an opening/closing plate having a first half moving upstream and a second half moving downstream when the valve is opened, and opening/closing the main passage; and a protruding portion protruding downstream from the first half portion in the valve-closed state, wherein the branch port of the sub-passage is located downstream of the opening/closing plate in the valve-closed state, and is formed at a position facing the second half portion when the butterfly valve is opened, and wherein an opening area communicating with the main passage upstream of the opening/closing plate increases according to an opening degree of the butterfly valve until the butterfly valve reaches a predetermined opening degree.

In the throttle device, the following structure may be adopted: the protruding portion is a flat back plate fixed with a predetermined gap from the opening/closing plate.

In the throttle device, the following structure may be adopted: the butterfly valve is formed so that suction gas can pass between the opening/closing plate and the back plate when in a fully opened state.

In the throttle device, the following structure may be adopted: the back plate has an outer contour corresponding to the first half of the opening/closing plate.

In the throttle device, the following structure may be adopted: the branch port of the sub-passage is located further downstream side than the axis in the main passage.

In the throttle device, the following structure may be adopted: the main passage is circular in section, the auxiliary passage is circular in section, and the branch port of the auxiliary passage is circular or elliptical.

In the throttle device, the following structure may be adopted: the branch ports of the sub-passages are arranged so that the centers thereof are located on a plane including the center line of the main passage and the center line of the opening/closing plate perpendicular to the axis.

In the throttle device, the following structure may be adopted: the sub-passage is formed to extend from the branch port to the downstream side at a predetermined inclination angle with respect to the center line of the main passage.

In the throttle device, the following structure may be adopted: the throttle body has a connector portion that connects passage members defining the sub-intake passage.

In the throttle device, the following structure may be adopted: the throttle body includes a bypass passage bypassing the butterfly valve, and a branch port of the sub-passage is disposed at a position offset from a closed port of the bypass passage.

In the throttle device, the following structure may be adopted: the throttle body includes a detection port that detects the pressure in the main passage on the downstream side of the butterfly valve, and the branch port of the sub-passage is arranged at a position offset from the detection port.

In addition, the inhalation system of the present invention comprises: a main intake passage that guides intake air to the combustion chamber and is opened and closed by an intake valve at a position facing the combustion chamber; a butterfly valve that rotates around a predetermined axis in order to open and close the main intake passage; a sub-intake passage branching from a middle portion of the main intake passage and merging with the main intake passage upstream of the intake valve; and a fuel injection valve that injects fuel in the middle of the main intake passage or injects fuel into the combustion chamber, wherein the intake system is configured to: the butterfly valve includes: an opening/closing plate having a first half moving upstream and a second half moving downstream when the valve is opened, and opening/closing the main intake passage; and a protruding portion protruding downstream from the first half portion in the valve-closed state, wherein a branch port of the sub-intake passage is located downstream of the opening/closing plate in the valve-closed state, and is formed at a position facing the second half portion when the butterfly valve is opened, and wherein an opening area communicating with the main intake passage upstream of the opening/closing plate increases according to an opening degree of the butterfly valve until the butterfly valve reaches a predetermined opening degree.

In the suction system, the following structure may be adopted: the protruding portion is a flat back plate fixed with a predetermined gap from the opening/closing plate.

In the suction system, the following structure may be adopted: the butterfly valve is formed so that suction gas can pass between the opening/closing plate and the back plate when in a fully opened state.

In the suction system, the following structure may be adopted: the back plate has an outer contour corresponding to the first half of the opening/closing plate.

In the suction system, the following structure may be adopted: the branch port of the sub-intake passage is located on the downstream side of the axis in the main intake passage.

In the suction system, the following structure may be adopted: the main suction passage has a circular cross section, the auxiliary suction passage has a circular cross section, and the branch port of the auxiliary suction passage has a circular or oval shape.

In the suction system, the following structure may be adopted: the branch port of the sub-suction passage is disposed so that its center is located on a plane including the center line of the main suction passage and the center line of the opening/closing plate perpendicular to the axis.

In the suction system, the following structure may be adopted: the sub-intake passage is formed to extend from the branch port to the downstream side at a predetermined inclination angle with respect to the center line of the main intake passage.

In the suction system, the following structure may be adopted: the orifice of the sub-intake passage is oriented in a direction to generate a swirl flow in the combustion chamber on the upstream side of the intake valve.

In the suction system, the following structure may be adopted: the combined port of the sub-intake passage is oriented in a direction to generate tumble flow in the combustion chamber at an upstream side of the intake valve.

[ Effect of the invention ]

By forming the throttle device and the intake system having the above-described structures, it is possible to reduce the number of parts, simplify the structure, reduce the cost, reduce the passage resistance, and the like, and at the same time, to increase the flow rate of intake air flowing through the sub-intake passage, and to generate swirl flow such as swirl flow or tumble flow in the combustion chamber, thereby contributing to an improvement in combustion efficiency.

Drawings

Fig. 1 is a cross-sectional view schematically showing an intake system of an internal combustion engine including a throttle device according to an embodiment of the present invention.

FIG. 2 is a partial perspective view of an air induction system including an embodiment of a throttle device.

Fig. 3 is a perspective view of the throttle device according to the embodiment, as viewed obliquely from the upstream side.

Fig. 4 is a perspective view of the throttle device according to the embodiment as viewed obliquely from the downstream side.

Fig. 5 is a cross-sectional view of a throttle device according to an embodiment, taken along a plane including the center line of a main passage that constitutes a part of a main intake passage and the center line of a butterfly valve that is perpendicular to the axis of a rotary shaft.

Fig. 6 is a perspective cross-sectional view of the throttle device according to the embodiment, the cross-sectional view being cut in a plane including the center line of the main passage forming a part of the main intake passage and the center line of the butterfly valve perpendicular to the axis of the rotary shaft.

Fig. 7 is a perspective cross-sectional view of a throttle device according to an embodiment, taken along a plane including the center line of a main passage and the axis of a rotary shaft, which form part of a main intake passage.

Fig. 8 is a perspective cross-sectional view of a rotary shaft and a butterfly valve included in a throttle device according to an embodiment, cut off on a plane perpendicular to an axis.

Fig. 9 is a perspective view of a butterfly valve included in the throttle device of an embodiment.

Fig. 10 is a cross-sectional view schematically showing the positional relationship between the main passage, the sub-passage, and the butterfly valve and the operation of the butterfly valve in the throttle device according to the embodiment.

Fig. 11 is a cross-sectional view schematically showing the flow of intake air when the butterfly valve is at a predetermined angular position of the valve opening in the throttle device according to the embodiment.

Fig. 12 is a sectional view schematically showing the flow of intake air when the butterfly valve is in the full open position in the throttle apparatus of the embodiment.

Fig. 13 is a cross-sectional view showing the relationship among the inner diameter of the main passage, the inner diameter of the sub passage, the position of the sub passage with respect to the axis of the rotary shaft, and the inclination angle of the sub passage in the throttle device according to the embodiment.

Fig. 14 is a diagram showing an intake flow diagram of a cross section obtained by simulating the intake flow of the main intake passage (main passage) and the sub intake passage (sub passage) when the butterfly valve is slightly opened (about 10 degrees) from the fully closed position, and by cutting the plane perpendicular to the axis of the rotation shaft and including the center line of the main intake passage (main passage) and the sub intake passage (sub passage), in the throttle valve device according to the embodiment.

Fig. 15 shows a result of simulation of the flow of intake air flowing into the combustion chamber from the main intake passage and the sub intake passage in the throttle apparatus according to the embodiment, and is an intake air flow diagram viewed from a direction perpendicular to the upper surface of the piston.

Fig. 16 is a graph showing a relationship among the opening degree of the butterfly valve, the flow rate of the entire passage flowing through the main intake passage and the sub intake passage, and the flow rate of the sub intake passage in the intake system including the throttle apparatus of the present invention.

Fig. 17 is a cross-sectional view of a throttle device according to another embodiment of the present invention, taken along a plane including a center line of a main passage that forms a part of a main intake passage and a center line of a butterfly valve that is perpendicular to an axis of a rotary shaft.

Fig. 18 is a cross-sectional view schematically showing an intake system of an internal combustion engine according to another embodiment of the present invention.

[ Description of symbols ]

E: internal combustion engine

IS: suction system

3A: air suction port (Main air suction passage)

3B, 113b: auxiliary port (auxiliary inhalation passage)

3B ₁、113b₁: confluence port of auxiliary suction passage

4A: suction valve

7: Air suction pipe

7A: main air suction passage

8: Auxiliary air suction pipe (passage component)

8A: auxiliary suction passage

9: Fuel injection valve

M: throttle valve device

10: Throttle valve body

12: Main passage (Main suction passage)

L: center line of main passage

14: Bypass passage

14B ₁: confluence port of bypass passage

16: Detection port

17. 117: Auxiliary passage (auxiliary suction passage)

17A, 117a: branching port of sub-passage

Beta: angle (inclination angle)

L2: center line of the sub-passage

18: Connector part

20: Rotary shaft

S: an axis line

Θ: prescribed opening degree

30: Butterfly valve

31: Opening and closing plate

31A: first half body

31B: second half body

32: Back panel (protruding part)

33: Connecting part

L3: center line of butterfly valve

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In an intake system of an internal combustion engine mounted on a motorcycle as an example, a throttle device of the present invention is mounted on a middle of an intake pipe on a downstream side of an air cleaner.

As shown in fig. 1, a throttle device M of an embodiment is applied to an intake system that guides intake air to a combustion chamber C of an internal combustion engine E.

The internal combustion engine E includes a cylinder block 1, a piston 2, a cylinder head 3, an intake valve 4a, an exhaust valve 4b, an exhaust pipe 5, an intake system IS, and the like.

The cylinder head 3 defines a combustion chamber C in cooperation with the upper surface of the piston 2, and includes: an intake port 3a forming part of the main intake passage, a sub port 3b forming part of the sub intake passage, and an exhaust port 3c, and the cylinder head 3 accommodates a driving mechanism (not shown) for opening and closing the intake valve 4a and the exhaust valve 4b, a spark plug (not shown), and the like.

The sub-port 3b is formed to merge with the intake port 3a on the nearest upstream side of the intake valve 4 a. That is, the sub-intake passage (sub-port 3 b) includes a merging port 3b ₁ that merges with the main intake passage (intake port 3 a) on the upstream side of the intake valve 4 a.

The merging port 3b ₁ of the sub port 3b is oriented in a direction to generate a swirl (transverse swirl) in the combustion chamber C. Specifically, as shown in fig. 15, the merging port 3b ₁ of the sub port 3b is formed to merge obliquely with respect to the intake port 3a so that intake air flows into the tangential direction of the inner wall surface of the combustion chamber C.

The suction system IS includes: the intake port 3a and the auxiliary port 3b of the cylinder head 3, the air cleaner 6 for taking in outside air, the intake pipe 7 as a passage member, the auxiliary intake pipe 8 as a passage member, the fuel injection valve 9 disposed midway in the intake pipe 7, and the throttle device M disposed midway in the intake pipe 7 on the upstream side of the fuel injection valve 9.

The intake pipe 7 is formed of a metal, a resin material, or the like, defines a main intake passage 7a having a circular cross section so as to pass intake air sucked by the air cleaner 6, and the intake pipe 7 is disposed so as to be interposed between the air cleaner 6 and the intake port 3a of the cylinder head 3.

The sub-intake pipe 8 is formed of a metal, a resin, a rubber material, or the like, defines a sub-intake passage 8a having a circular cross section so as to allow intake air to pass therethrough, and is disposed so as to be interposed between the throttle device M and the sub-port 3b of the cylinder head 3.

The fuel injection valve 9 is disposed in the intake pipe 7, and injects fuel into the main intake passage 7a on the side close to the intake port 3 a.

As shown in fig. 2 to 7, the throttle device M includes: the throttle valve includes a throttle body 10, a rotary shaft 20 centered on an axis S, a butterfly valve 30, a driving unit 40 for opening and closing the butterfly valve 30, an adjusting valve 50, and a sensor unit U. Here, the sensor unit U includes: an angular position sensor 60, a pressure sensor 70, a temperature sensor 80.

The throttle body 10 is formed of a metal material such as aluminum or a resin material, and includes: the upstream side connection portion 11a, the downstream side connection portion 11b, the main passage 12, the shaft hole 13 through which the rotation shaft 20 passes, the bypass passage 14, the housing portion 15 housing the adjustment valve 50, the detection port 16, the sub-passage 17, and the connector portion 18.

The upstream connection portion 11a is connected to the intake pipe 7 connected to the upstream side of the air cleaner 6.

The downstream connection portion 11b is connected to an intake pipe 7 connected to the cylinder head 3 of the internal combustion engine E on the downstream side of the intake port 3 a.

The main passage 12 functions as a part of a main intake passage that guides intake air to the combustion chamber C, has a circular cross section centered on a center line L perpendicular to the axis S, and is formed in a cylindrical shape extending in the direction of the center line L. As shown in fig. 5, the main passage 12 is formed in a conical surface shape in which the passage area is enlarged toward the upstream side connection portion 11a and the downstream side connection portion 11b from a predetermined region where the butterfly valve 30 is rotatably arranged.

As shown in fig. 7, the shaft hole 13 is formed as a circular hole so that the rotary shaft 20 passes through rotatably about the axis S, and an annular recess 13a into which the lip seal Rs is fitted is formed on the outer side in the axis S direction.

As shown in fig. 5 to 7, the bypass passage 14 includes: an upstream side passage 14a branched from the main passage 12 on the upstream side of the butterfly valve 30, a downstream side passage 14b merging with the main passage 12 on the downstream side of the butterfly valve 30, and a communication passage (not shown) interposed between the upstream side passage 14a and the downstream side passage 14b and having a passage area adjusted by the adjustment valve 50.

That is, the bypass passage 14 branches from the main passage 12 at the branch port 14a ₁ located on the upstream side of the butterfly valve 30 to introduce the intake air, bypasses the butterfly valve 30, and introduces the intake air to the main passage 12 at the merging port 14b ₁ located on the downstream side of the butterfly valve 30.

As shown in fig. 5 and 6, the housing portion 15 is a region in which the valve body 51 of the regulator valve 50 is reciprocatingly housed, and also functions as a communication path that communicates the upstream side passage 14a with the downstream side passage 14 b.

As shown in fig. 7, the detection port 16 is formed to open at the main passage 12 on the downstream side of the butterfly valve 30, so that the pressure sensor 70 provided to the sensor unit U is exposed to the suction air in the main passage 12.

As shown in fig. 5 and 6, the sub passage 17 is formed so that the sub passage 17 branches from the main passage 12 downstream of the butterfly valve 30, and extends downstream from a branching port 17a, which is the start point of the sub passage 17, by a predetermined length at a predetermined inclination angle with respect to the center line L of the main passage 12. Specifically, the sub-passage 17 is formed in a circular cross section centered on a center line L2 that forms an angle β with the center line L of the main passage 12, and is formed as a cylindrical hole that extends in the direction of the center line L2. Therefore, the branch port 17a of the sub-passage 17 is formed in an oblong shape in the direction of the center line L of the main passage 12.

As shown in fig. 10, the branch port 17a of the sub-passage 17 is disposed at a position downstream of the axis S of the rotary shaft 20 by a distance Δl in the main passage 12, and the center (center line L2) thereof is disposed on a plane (cross section shown in fig. 5 and 10) including the center line L of the main passage 12 and the center line L3 of the butterfly valve 30 perpendicular to the axis S of the rotary shaft 20.

In this way, the branch port 17a is arranged in the center of the main passage 12 and the butterfly valve 30 in the axis S direction, and therefore the intake air can be efficiently guided to the sub-passage 17.

As shown in fig. 7, the branch port 17a of the sub-passage 17 is disposed at a position offset from the merging port 14b ₁ of the bypass passage 14 and at a position offset from the detection port 16.

In this way, the branch port 17a is disposed at the position of the deflection flow port 14b ₁ and the detection port 16, so that the mutual influence can be prevented, and the respective functions can be realized.

Further, as shown in fig. 10, the branch port 17a of the sub-passage 17 is located downstream of the butterfly valve 30 in the closed state, and is formed at a position where the opening area a communicating with the main passage 12 upstream of the butterfly valve 30 increases according to the opening degree of the butterfly valve 30 until the butterfly valve 30 reaches the predetermined opening degree θ.

Specifically, in fig. 10, when the butterfly valve 30 rotates clockwise from the fully closed position, the opening area a of the branch port 17a communicating with the main passage 12 on the upstream side of the second half body 31b of the opening/closing plate 31 of the butterfly valve 30 gradually increases as the butterfly valve 30 rotates, as shown in fig. 10 and 11, and when the butterfly valve 30 rotates to the predetermined opening degree θ, the opening area a of the branch port 17a becomes maximum.

In this rotation region, as shown in fig. 11, the intake air flowing from the main passage 12 on the upstream side of the butterfly valve 30 is guided along the opening/closing plate 31 of the butterfly valve 30, is directed toward the second half body 31b inclined particularly toward the downstream side, and is positively directed toward the branch port 17a to flow into the sub-passage 17.

On the other hand, of the intake air flowing from the main passage 12 upstream of the butterfly valve 30, the intake air flowing around the first half 31a flows into the rear of the rear plate 32 and is disturbed, and the flow of the intake air flowing through the main passage 12 falls back. Therefore, the flow rate of the suction air flowing into the sub-passage 17 is relatively increased as compared with the case where the back plate 32 is not present.

In the region where the butterfly valve 30 is rotated from the predetermined opening degree θ to the fully open position, the opening area of the branch port 17a is not changed, and the butterfly valve 30 is parallel to the center line L (horizontal in fig. 12) of the main passage 12. Therefore, as shown in fig. 12, the suction gas flowing through the main passage 12 is lost by the action of the butterfly valve 30 (the opening/closing plate 31) toward the orientation of the sub-passage 17, and flows toward the downstream side in the main passage 12.

In particular, the butterfly valve 30 is provided with a gap between the opening/closing plate 31 and the back plate 32, so that the suction air flows therebetween. Therefore, even if the back plate 32 is provided, the suction air can smoothly flow.

In this way, the branch port 17a of the sub-passage 17 is arranged so as to face the second half body 31b that moves downstream (is inclined toward the downstream) when the butterfly valve 30 is opened, and the intake air in the main passage 12 is positively guided to flow into the sub-passage 17 by the guiding action of the butterfly valve 30 until the predetermined opening degree θ is reached. In particular, since the back plate 32, which is a protruding portion protruding rearward of the first half 31a, disturbs the flow of the suction gas flowing into the main passage 12 on the downstream side of the first half 31a, and drops the flow of the suction gas flowing into the main passage 12, the flow rate of the suction gas flowing into the sub passage 17 can be relatively increased.

The connector 18 is formed of a metal cylindrical tube, and is press-fitted into the throttle body 10 to communicate with the sub-passage 17. The upstream end of the sub-suction pipe 8 as a passage member is connected to the connector 18.

Here, the connector portion 18 is shown as an example formed as a separate member, but may be formed integrally with the throttle body 10.

The rotation shaft 20 is formed of a metal material or the like so as to extend in the axis S direction in a circular cross section, and as shown in fig. 7, the rotation shaft 20 includes: a slit 21 and two screw holes 22 of the butterfly valve 30 are fitted in the central region, a coupling portion 23 to which the drive unit 40 is coupled at one end side, and a bottomed cylindrical portion 24 at the other end side. In addition, a double-sided wide portion 21a is formed at the outer periphery of the region of the slit 21 to reduce the passage resistance in the main passage 12.

The coupling portion 23 includes a double-sided wide portion for integrally rotatably fitting the drum 41 of the driving unit 40.

The bottomed cylindrical portion 24 includes a permanent magnet 24a on the inner peripheral surface, and is formed such that the cylindrical angular position sensor 60 of the sensor unit U is housed inside in a noncontact manner.

In a state where the rotation shaft 20 passes through the shaft hole 13 of the throttle body 10, the butterfly valve 30 fitted into the slit 21 is fastened by the screw b2, and the butterfly valve 30 is held openable and closable. Further, the rotary shaft 20 is sealed on the outer side in the axial direction S from the shaft hole 13 by a lip seal Rs.

As shown in fig. 5 to 9, the butterfly valve 30 includes: an opening/closing plate 31, a back plate 32 as a protruding portion, and two connecting portions 33.

The opening/closing plate 31 opens and closes the main passage 12, and is formed in a substantially disk shape, and includes: the first half 31a moving upstream when the valve is opened, the second half 31b moving downstream when the valve is opened, and two circular holes 31c through which the screws b2 pass.

The back plate 32 is disposed with a predetermined gap from the opening/closing plate 31, and is fixed to the opening/closing plate 31 by two coupling portions 33. The back plate 32 has an outer contour corresponding to the first half 31a of the shutter plate 31, that is, is formed in a semicircular shape.

The two coupling portions 33 are formed as: between the opening/closing plate 31 and the back plate 32, the suction gas can pass through in the fully opened state, and the projected area in the flow direction is as small as possible so as not to increase the passage resistance.

Here, the opening/closing plate 31, the back plate 32, and the coupling portion 33 of the butterfly valve 30 may be integrally formed of a resin material or the like, or may be formed of a metal material or the like, and fastened and fixed to each other by screws or the like.

The butterfly valve 30 forming the structure is configured as follows: after the rotation shaft 20 passes through the shaft hole 13, the opening/closing plate 31 is passed through the slit 21, and in the closed state, the back plate 32 is positioned downstream of the first half 31a (i.e., protrudes downstream from the first half 31 a), and is fixed to the rotation shaft 20 by the screw b2 to open and close the main passage.

When the butterfly valve 30 is driven by the driving unit 40 to open the valve, that is, when it is moved from the fully closed position to the fully open position, as shown in fig. 10, the posture is changed as follows: the first half 31a is inclined and becomes horizontal toward the upstream side of the main passage 12, and the second half 31b is inclined and becomes horizontal toward the downstream side of the main passage 12.

As shown in fig. 3, 4, and 7, the driving unit 40 rotationally drives the rotary shaft 20 about the axis S, and includes a drum 41 and a coil spring 42, the drum 41 being coupled to and fixed to the coupling portion 23 of the rotary shaft 20, the coil spring 42 being disposed between the drum 41 and the throttle body 10 about the rotary shaft 20.

The drum 41 includes: a locking hole 41a for locking a wire connected to the throttle lever, a locking portion 41b for locking the coil spring 42, and a contact rod 41c.

As shown in fig. 3, one end 42a of the coil spring 42 is engaged with the engagement portion 41b of the drum 41, and the other end is engaged with an engagement portion (not shown) of the throttle body 10, thereby imparting a rotational force to the butterfly valve 30 in the closing direction.

As shown in fig. 3, the abutment lever 41c abuts against the adjustment screw 11c provided to the throttle body 10 by the rotational force applied by the coil spring 42. Therefore, by appropriately adjusting the feed amount of the adjusting screw 11c, the valve opening of the butterfly valve 30 at the stop position can be set to a desired position.

As shown in fig. 3 to 6, the regulator valve 50 includes a valve body 51, an electromagnetic actuator 52, and a pressing member 53, the electromagnetic actuator 52 includes a screw that reciprocally drives the valve body 51 in a direction parallel to the axis S, and the pressing member 53 fixes the electromagnetic actuator 52 to the throttle body 10.

The adjustment valve 50 is configured to adjust the flow rate of the intake air flowing through the bypass passage 14 by increasing or decreasing the passage area of the bypass passage 14 (communication passage) in the engine idle operation region.

As shown in fig. 7, the angular position sensor 60 is provided in the sensor unit U, is formed in a cylindrical shape with hall elements buried therein, and detects the rotation angle of the rotary shaft 20 in cooperation with the permanent magnet 24a disposed in the bottomed cylindrical portion 24 coupled to the rotary shaft 20.

As shown in fig. 7, the pressure sensor 70 is provided in the sensor unit U, and includes, for example, a pressure receiving portion such as a diaphragm having a semiconductor strain gauge, a protective cover, and the like. The pressure sensor 70 detects the pressure of the intake air through the detection port 16 leading to the main passage 12.

Here, since the detection port 16 is formed at a position offset from the branch port 17a of the sub-passage 17 in the direction of the center line L and in the circumferential direction around the center line L, the pressure of the suction air can be detected without being affected by the suction air flow in the vicinity of the branch port 17 a.

The temperature sensor 80 detects the temperature of the intake air flowing through the main passage 12, and is, as shown in fig. 6, a lead sensor including a temperature sensing element 81 such as a thermistor, provided in the sensor unit U. The temperature sensor 80 is housed in a cylindrical portion 82 protruding from the body of the sensor unit U, and is disposed so as to protrude into the main passage 12 on the upstream side of the butterfly valve 30, thereby detecting the temperature of intake air.

In this configuration, as shown in fig. 13, the following tends to be applied to the values of the inner diameter Φd1 of the main passage 12, the inner diameter Φd2 of the sub passage 17, the distance H in the direction of the center line L from the axis S of the rotary shaft 20 to (the upstream side edge of) the branch port 17a, and the inclination angle (angle β) of the center line L2 of the sub passage 17 with respect to the center line L.

(1) The inner diameter phid 1 of the main passage 12 has a small influence on the flow rate ratio of the sub passage 17.

(2) As the inner diameter phid 2 of the sub-passage 17 increases, the flow rate ratio of the sub-passage 17 tends to increase.

(3) As the distance H decreases, the flow rate ratio of the sub-passage 17 tends to increase.

(4) As the angle β decreases, that is, as the flow rate ratio of the sub-passage 17 increases when it extends obliquely toward the downstream side from the center line L perpendicular to the main passage 12.

In view of the above, the branch port 17a of the sub-passage 17 is preferably located downstream of the axis S of the rotary shaft 20 and is disposed at a position closest downstream of the axis S. The sub-passage 17 is preferably formed to extend downstream at a small inclination angle (angle β) with respect to the center line L of the main passage 12. Further, when it is desired to increase the flow rate ratio flowing through the sub-passage 17 in a region where the opening degree of the butterfly valve 30 is small, it is preferable to set the inner diameter Φd2 of the sub-passage 17 to be large. Therefore, based on the characteristics, it is preferable to set various parameters (Φd1, Φd2, H, β) so as to set the flow rate of the intake air flowing through the sub-passage 17 according to the specification of the internal combustion engine E.

In the intake system IS configured as described above, the main intake passage 7a defined by the intake pipe 7 between the air cleaner 6 and the throttle device M, the main intake passage 12 defined by the throttle device M, the main intake passage 7a defined by the intake pipe 7 between the throttle device M and the intake port 3a, and the intake port 3a defined by the cylinder head 3 form a main intake passage that guides intake air to the combustion chamber C and IS opened and closed by the intake valve 4a at a position facing the combustion chamber C.

The auxiliary intake passage 17 defined by the throttle device M, the auxiliary intake passage 8a defined by the auxiliary intake pipe 8 between the throttle device M and the auxiliary port 3b, and the auxiliary intake passage 3b defined by the cylinder head 3 form an auxiliary intake passage (main passage 12) that branches in the middle of the main intake passage and merges with the main intake passage (intake port 3 a) upstream of the intake valve 4a.

Next, the operation of the internal combustion engine E including the intake system IS will be described.

First, when the internal combustion engine E is in the idle operation region, the butterfly valve 30 is in a valve-closed state in which the main passage 12 is closed, and the intake air taken in from the air cleaner 6 flows through the main intake passage 7a, the main passage (main intake passage) 12, flows through the bypass passage 14 so as to bypass the butterfly valve 30, flows into the main passage (main intake passage) 12 on the downstream side again, and flows into the combustion chamber C as a mixture gas together with the fuel injected from the fuel injection valve 9 in the main intake passage 7a via the main intake passage 7a and the intake port (main intake passage) 3a.

In this state, the regulator valve 50 regulates the passage area of the bypass passage 14 (communication passage) to keep the idling operation of the internal combustion engine E in a steady state.

On the other hand, when the internal combustion engine E is in an operation region other than the idling operation region (low load to medium load to high load), the butterfly valve 30 opens to open the main passage 12.

Therefore, the intake air flowing through the main passage 12 flows through the main passage 12 or the sub-passage 17 without passing through the bypass passage 14, and is sucked into the combustion chamber C.

That is, in the low-load to medium-load operation region in which the butterfly valve 30 is opened from the fully closed position to the predetermined opening θ, the opening area a of the branch port 17a communicating with the main passage 12 on the upstream side of the second half body 31b of the butterfly valve 30 gradually increases as the butterfly valve 30 rotates.

Therefore, as shown in fig. 11 and 14, the intake air flowing from the main passage 12 upstream of the butterfly valve 30 is guided by the second half body 31b of the butterfly valve 30 inclined toward the downstream, and is positively directed to the branch port 17a to flow into the sub-passage 17.

Here, of the suction air flowing from the main passage 12 upstream of the butterfly valve 30, the suction air flowing around the first half 31a flows into the back of the back plate 32 to be disturbed, and the flow of the suction air flowing through the main passage 12 falls back. Therefore, the flow rate of the suction air flowing into the sub-passage 17 is relatively increased as compared with the case where the back plate 32 is not present.

As a result, the amount of intake air flowing through the sub intake passage (sub passage 17, sub intake passage 8a, sub port 13 b) increases, and as shown in fig. 15, a swirl (lateral swirl) is generated in the mixture gas flowing into the combustion chamber C. The swirling flow promotes atomization of the fuel and homogenization of the mixture of the intake air and the fuel, so as to improve combustion efficiency.

In the high load operation region in which the butterfly valve 30 is rotated from the predetermined opening degree θ to the full open position, the opening area of the branch port 17a is not changed, and the butterfly valve 30 is parallel to the center line L of the main passage 12. Therefore, as shown in fig. 12, there is substantially no effect of the suction gas flowing through the main passage 12 being directed toward the sub-passage 17 by the butterfly valve 30, and flows toward the downstream side within the main passage 12. In particular, since a gap is formed between the opening/closing plate 31 and the back plate 32 of the butterfly valve 30, the intake air flows not only around the butterfly valve 30 but also to the downstream side through the gap. As a result, in the high load operation region, the intake air amount flowing through the main intake passage (main intake passage 7a, main intake passage 12, main intake passage 7a, intake port 3 a) increases, the combustion speed increases, and efficient combustion is promoted.

That is, as shown in fig. 16, when the butterfly valve 30 is opened from the fully closed position to the fully open position, the proportion of intake air flowing through the sub-intake passage (sub-passage 17, sub-intake passage 8a, sub-port 13 b) increases in the operation region from the low load to the medium load. In the medium-to-high-load operation region, the proportion of intake air flowing through the sub-intake passage (sub-passage 17, sub-intake passage 8a, sub-port 13 b) decreases, and the proportion of intake air flowing through the main intake passage (main intake passage 7a, main passage 12, main intake passage 7a, intake port 3 a) increases.

Thus, in the low-load to medium-load operation region, a swirl flow can be generated in the combustion chamber C to improve combustion efficiency, and in the high-load operation region, the high-speed intake air flow rate mainly flowing through the main passage 12 increases, the combustion speed increases, and combustion with good efficiency is promoted.

In the throttle device M of the above-described embodiment, the sub-passage 17 is shown as extending in the direction forming the inclination angle (angle β) with respect to the main passage 12, but as shown in fig. 17, a sub-passage 117 extending downstream after branching perpendicular to the main passage 12 may be employed.

In the above embodiment, the branch port 117a of the sub-passage 117 is located downstream of the opening/closing plate 31 in the closed state, and is formed at a position facing the second half body 31b when the butterfly valve 30 is opened, and the opening area a communicating with the main passage 12 upstream of the opening/closing plate 31 increases according to the opening degree of the butterfly valve 30 until the butterfly valve 30 reaches the predetermined opening degree θ. The branch port 117a of the sub-passage 117 is circular open with respect to the main passage 12.

In the intake system IS including the throttle device M of the above-described embodiment, the structure in which the merging port 3b ₁ of the sub-intake passage (sub-port 3 b) IS oriented in the direction of generating the swirl flow in the combustion chamber C on the upstream side of the intake port 4a IS shown, but as shown in fig. 18, the following structure may be adopted: the fuel injection valve 9 is configured to directly inject fuel to the combustion chamber C, and the merging port 113b ₁ of the sub-intake passage (sub-port 113 b) is oriented in a direction to generate tumble flow (longitudinal swirl) in the combustion chamber C at the upstream side than the intake valve 4 a.

As described above, according to the throttle device M of the present invention, the intake system IS applied to the internal combustion engine E, the intake system IS including: a main intake passage (7 a, 3 a) that guides intake air to the combustion chamber C and is opened and closed by an intake valve 4a at a position facing the combustion chamber C, and sub-intake passages (8 a, 3 b) that branch from midway of the main intake passage and merge with the main intake passage (3 a) on the upstream side of the intake valve 4a, the throttle device M including: a throttle body 10 defining a main passage 12 that forms part of a main intake passage and a sub-passage 17 that branches from the main passage 12 and forms part of a sub-intake passage; and a butterfly valve 30 that rotates around a predetermined axis S to open and close the main passage 12, the butterfly valve 30 including: an opening/closing plate 31 having a first half 31a that moves toward the upstream side and a second half 31b that moves toward the downstream side when the valve is opened, and opening/closing the main passage 12; and a protruding portion (in the embodiment, the back plate 32) protruding downstream from the first half portion 31a in the closed state, the branch port 17a of the sub-passage 17 being located downstream of the opening/closing plate 31 in the closed state, and being formed at a position facing the second half portion 31b when the butterfly valve 30 is opened, and being a position where an opening area a communicating with the main passage 12 on the upstream side of the opening/closing plate 31 increases according to the opening degree of the butterfly valve 30 until the butterfly valve 30 reaches the prescribed opening degree θ.

Accordingly, the suction air flowing through the main passage 12 can be guided to positively flow into the sub-passage 17 by the second half 31b of the butterfly valve 30 in the operation region corresponding to the low to medium load up to the predetermined opening θ while achieving reduction in the number of parts, simplification of the structure, reduction in the cost, reduction in the passage resistance, and the like. By increasing the flow rate of the intake air flowing through the sub-intake passages (17, 8a, 3 b), a swirling flow (swirl flow or tumble flow) can be generated in the combustion chamber C. In particular, since the protruding portion protruding from the first half 31a toward the downstream side is provided, the flow of the suction gas flowing into the back of the first half 31a is disturbed by the protruding portion, and the flow of the suction gas flowing through the main passage 12 falls back. The flow rate of the suction gas flowing into the sub-passage 17 can be relatively increased.

The protruding portion protruding downstream from the first half portion 31a is a flat plate-like back plate 32 fixed with a predetermined gap from the opening/closing plate 31.

Accordingly, the butterfly valve 30 can be made lighter and the formability and manufacturability can be improved as compared to a case where the protruding portion is in a solid form such as a ridge portion or a bulge portion.

The butterfly valve 30 is formed so that, when in the fully open state, intake air can pass between the opening/closing plate 31 and the back plate 32.

Accordingly, in the fully opened state, the suction air can pass through between the opening/closing plate 31 and the back plate 32, and thus the passage resistance can be reduced as compared with the case of forming a solid member in which the opening/closing plate and the back plate are closed.

The back plate 32 is formed to have an outer contour corresponding to the first half 31a of the shutter plate 31.

Accordingly, when the butterfly valve 30 is opened from the fully closed state, the flow of the intake air flowing into the sub-passage 17 can be relatively increased by obtaining the effect of disturbing the flow of the intake air on the downstream side in the range of the predetermined opening degree.

In addition, the branch port 17a of the sub passage 17 is arranged downstream of the axis S in the main passage 12.

Accordingly, when the butterfly valve 30 is rotated about the axis S to open the opening/closing plate 31, the branch port 17a can be easily disposed so that the branch port 17a faces the second half body 31b moving downstream, and the second half body 31b of the opening/closing plate 31 inclined downstream can be effectively used as a guide member for the intake air to guide the intake air to the sub-passage 17.

In addition, the method is formed as follows: the main passage 12 has a circular cross section, the sub passage 17 has a circular cross section, and the branch port 17a of the sub passage 17 has a circular or elliptical shape.

Accordingly, by adopting the channel having a shape that is easy to process, it is possible to reduce the passage resistance of the passage through which the suction gas flows while realizing low cost.

The branch port 17a of the sub passage 17 is disposed such that the center L2 thereof is located on a plane including the center line L of the main passage 12 and the center line L3 of the butterfly valve 30 perpendicular to the axis S of the rotary shaft 20.

Accordingly, the branch port 17a is arranged at the center of the main passage 12 and the butterfly valve 30 in the axis S direction, and thus the intake air can be efficiently guided toward the sub passage 17.

The sub-passage 17 is formed to extend downstream from the branch port 17a by a predetermined length at a predetermined inclination angle (angle β) with respect to the center line L of the main passage 12.

Accordingly, the suction air flowing through the main passage 12 can be guided to the sub-passage 17 while reducing the passage resistance caused by the bending loss.

The throttle body 10 further includes a connector portion 18, and the connector portion 18 connects passage members (sub-intake pipes 8) defining the sub-intake passage 8 a.

Accordingly, when the throttle device M IS disposed in the middle of the intake system IS, the passage member (sub intake pipe 8) defining the sub intake passage 8a can be easily assembled, and workability can be improved.

The throttle body 10 includes a bypass passage 14 bypassing the butterfly valve 30, and the branch port 17a of the sub-passage 17 is disposed at a position offset from the merging port 14b ₁ of the bypass passage 14. The throttle body 10 further includes a detection port 16, the detection port 16 detecting the pressure in the main passage 12 on the downstream side of the butterfly valve 30, and a branch port 17a of the sub-passage 17 is disposed at a position offset from the detection port 16.

Accordingly, the branch port 17a is disposed at the position of the deflection flow port 14b ₁ and the detection port 16, and thus the influence of each other can be prevented, and the respective functions can be realized.

In the intake system IS of the above-described embodiment, the throttle device M including the throttle body 10 IS disposed in the middle of the intake pipe 7, but a configuration may be adopted in which a butterfly valve IS disposed in a passage member defining a main intake passage, and a fuel injection valve IS disposed in the middle of the main intake passage to inject fuel or directly into a combustion chamber, instead of providing a dedicated throttle body.

That is, the following inhalation system can be formed: comprising a main intake passage, a butterfly valve, a sub intake passage, and a fuel injection valve, the butterfly valve comprising: an opening/closing plate having a first half moving upstream and a second half moving downstream when the valve is opened, and opening/closing the main passage; and a protruding portion protruding downstream from the first half portion in the valve-closed state, wherein a branch port of the sub-intake passage is located downstream of the opening/closing plate in the valve-closed state, and is formed at a position facing the second half portion when the butterfly valve is opened, and wherein an opening area communicating with the main intake passage upstream of the opening/closing plate increases according to an opening degree of the butterfly valve until the butterfly valve reaches a predetermined opening degree.

In the above embodiment, the butterfly valve 30 using the back plate 32 as the protruding portion protruding downstream from the first half portion 31a in the valve-closed state is shown, but the present invention is not limited to this, and any solid protruding portion or ridge protruding downstream from the first half portion or other protruding portion may be used as long as it is a member that disrupts the action of the intake air flowing into the back of the first half portion 31 a.

In the above embodiment, the case where the main intake passage (main passage) and the sub intake passage (sub passage) are circular in cross section and the branch ports of the sub intake passage (sub passage) are circular or elliptical has been described, but the present invention is not limited to this, and other forms of the main intake passage (main passage), the sub intake passage (sub passage) and the branch ports may be used.

In the above embodiment, the case where the vehicle mounted with the internal combustion engine to which the throttle device and the intake system of the present invention are applied is shown as a motorcycle, but the present invention is not limited to this, and the present invention can be applied to an internal combustion engine mounted on an automobile or the like.

As described above, the throttle device and the intake system according to the present invention can increase the flow rate of intake air flowing through the sub intake passage while achieving reduction in the number of parts, simplification of the structure, reduction in the cost, reduction in the passage resistance, and the like, and thus can generate swirling flow such as swirl flow or tumble flow in the combustion chamber, contributing to improvement in combustion efficiency, and therefore, can be applied to an internal combustion engine mounted on a motorcycle or the like, and can be effectively applied to an internal combustion engine mounted on an automobile or an internal combustion engine mounted on another vehicle.

Claims

1. A throttle device adapted for use in an intake system of an internal combustion engine, the intake system of the internal combustion engine comprising: a main intake passage that guides intake air to a combustion chamber and is opened and closed by an intake valve at a position facing the combustion chamber; and a sub-intake passage that branches from a middle of the main intake passage and merges with the main intake passage on an upstream side of the intake valve, wherein the throttle device includes: a throttle body defining a main passage that constitutes a part of the main intake passage and a sub-passage that branches from the main passage and constitutes a part of the sub-intake passage; and a butterfly valve which rotates around a predetermined axis for opening and closing the main passage, and

The butterfly valve includes: an opening/closing plate having a first half part moving upstream and a second half part moving downstream when the valve is opened, and opening/closing the main passage; and a protruding portion protruding from the first half portion toward the downstream side in a valve-closed state,

The branch port of the sub-passage is located downstream of the opening/closing plate in the closed state, is formed at a position facing the second half body when the butterfly valve is opened, and is a position where an opening area communicating with the main passage on the upstream side of the opening/closing plate increases according to an opening degree of the butterfly valve until the butterfly valve reaches a predetermined opening degree.

2. A throttle device as defined in claim 1, wherein,

The protruding portion is a flat plate-shaped back plate fixed to the opening/closing plate with a predetermined gap.

3. A throttle device as defined in claim 2, wherein,

The butterfly valve is formed so that suction gas can pass between the opening/closing plate and the back plate when in a fully opened state.

4. A throttle device as defined in claim 2, wherein,

The back plate has an outer contour corresponding to the first half of the opening/closing plate.

5. A throttle device as defined in claim 1, wherein,

The branch port of the sub-passage is located further downstream than the axis in the main passage.

6. A throttle device as defined in claim 1, wherein,

The main passage is of circular cross-section,

The secondary passageway is of circular cross-section,

The branch port of the auxiliary passage is round or oval.

7. The throttle device according to any one of claims 1 to 6, characterized in that,

The branch port of the sub passage is arranged so that its center is located on a plane including a center line of the main passage and a center line of the opening/closing plate perpendicular to the axis.

8. The throttle device according to any one of claims 1 to 6, characterized in that,

The sub-passage is formed to extend from the branch port to a downstream side at a predetermined inclination angle with respect to a center line of the main passage over a predetermined length.

9. The throttle device according to any one of claims 1 to 6, characterized in that,

The throttle body has a connector portion that connects passage members that define the sub-intake passage.

10. The throttle device according to any one of claims 1 to 6, characterized in that,

The throttle body includes a bypass passage bypassing the butterfly valve,

The branch port of the sub-passage is disposed at a position offset from the closed port of the bypass passage.

11. The throttle device according to any one of claims 1 to 6, characterized in that,

The throttle body includes a detection port that detects a pressure in the main passage at a downstream side than the butterfly valve,

The branch port of the sub-passage is arranged at a position offset from the detection port.

12. An inhalation system, comprising:

A main intake passage that guides intake air to a combustion chamber and is opened and closed by an intake valve at a position facing the combustion chamber;

A butterfly valve that rotates around a predetermined axis in order to open and close the main intake passage;

A sub-intake passage branching from a middle portion of the main intake passage and merging with the main intake passage on an upstream side of the intake valve; and

A fuel injection valve that injects fuel in the middle of the main intake passage or injects fuel into the combustion chamber, and

The butterfly valve includes: an opening/closing plate having a first half moving upstream and a second half moving downstream when the valve is opened, and opening/closing the main intake passage; and a protruding portion protruding from the first half portion toward the downstream side in a valve-closed state,

The branch port of the sub intake passage is located downstream of the opening/closing plate in the closed state, is formed at a position facing the second half body when the butterfly valve is opened, and is a position where an opening area communicating with the main intake passage upstream of the opening/closing plate increases according to an opening degree of the butterfly valve until the butterfly valve reaches a predetermined opening degree.

13. The aspiration system of claim 12 wherein the device comprises a valve,

14. The aspiration system of claim 13 wherein the device comprises a valve,

15. The aspiration system of claim 13 wherein the device comprises a valve,

16. The aspiration system of claim 12 wherein the device comprises a valve,

The branch port of the sub-intake passage is located on the downstream side of the axis line in the main intake passage.

17. The aspiration system of claim 12 wherein the device comprises a valve,

The main suction passage has a circular cross section,

The secondary suction passage has a circular cross section,

The branch port of the auxiliary suction passage is circular or elliptical.

18. An inhalation system according to any one of claims 12 to 17, wherein,

The branch port of the sub suction passage is disposed so that its center is located on a plane including a center line of the main suction passage and a center line of the opening/closing plate perpendicular to the axis.

19. An inhalation system according to any one of claims 12 to 17, wherein,

The sub-intake passage is formed to extend from the branch port to a downstream side at a predetermined inclination angle with respect to a center line of the main intake passage over a predetermined length.

20. An inhalation system according to any one of claims 12 to 17, wherein,

The orifice of the sub-intake passage is oriented in a direction to generate a swirl flow in the combustion chamber on an upstream side of the intake valve.

21. An inhalation system according to any one of claims 12 to 17, wherein,

The orifice of the sub-intake passage is oriented in a direction to generate tumble flow in the combustion chamber on an upstream side of the intake valve.