WO2013146703A1

WO2013146703A1 - Air intake device for internal combustion engine

Info

Publication number: WO2013146703A1
Application number: PCT/JP2013/058632
Authority: WO
Inventors: 田邉　和也; 良久保田
Original assignee: 本田技研工業株式会社
Priority date: 2012-03-30
Filing date: 2013-03-25
Publication date: 2013-10-03
Also published as: PH12014502192A1; BR112014019110A8; CO7141440A2; PE20142191A1; CN104114832B; BR112014019110A2; JPWO2013146703A1; BR112014019110B1; CN104114832A; JP5925878B2; AR094131A1

Abstract

An air intake device for an internal combustion engine wherein a throttle valve (22) and an air intake distribution valve (61) are provided in an air intake passage (P). The air intake passage is separated into an upper air intake passage (Up) and a lower air intake passage (Lp) by means of a partition plate (60) downstream from the air intake distribution valve (61). The air intake distribution valve (61) is pivotally mounted at a position (61a) near the upstream edge of the partition plate (60) and extends in the upstream direction. The rocking of the distribution valve (61) divides the intake air downstream from the air intake distribution valve into an upper flow and a lower flow and thus changes the ratio of the intake air flowing in the upper air intake passage (Up) and the lower air intake passage (Lp). The amounts of intake air flowing in the upper and lower passages can be allocated selectively and appropriately in response to the load state, and the strength of the eddy flow of the tumble can be adjusted, thereby achieving optimal combustion efficiency.

Description

Intake device for internal combustion engine

The present invention relates to an intake system for an internal combustion engine mounted on a vehicle.

In the low load region of the internal combustion engine, in order to improve fuel efficiency, tumble is generated in the intake air taken in the combustion chamber, fuel is fed around the spark plug in the upper portion of the combustion chamber, and combustion efficiency is improved. Inspiratory devices are known.

In this intake system, the intake port and the exhaust port extend from the intake valve port and the exhaust port on the ceiling surface of the combustion chamber of the cylinder head while curving away from each other, and the intake port guides the intake port to the combustion chamber Among them, the intake air taken into the combustion chamber from the inner edge side close to the cylinder axis of the intake valve port (the central axis line of the cylinder bore) flows down toward the exhaust side and descends the exhaust side of the cylinder bore. By bending the flow and raising the intake side, a longitudinal vortex, so-called tumble, is formed.

Therefore, in order to increase the ratio of intake air taken in from the inner edge side closer to the cylinder axis of the intake valve port, the inside of the intake port is divided by upper and lower passages by the partition wall, and the lower passage is opened and closed upstream of the partition wall Intake control valves are installed to close the lower passage immediately after engine start, so that the intake air flowing through the passage above the intake port is taken into the combustion chamber from the inner edge side of the intake valve port, which is an extension of the upper passage. Thus, an intake device that generates a strong vortex tumble has been proposed (see Patent Document 1).

JP, 2008-151078, A

In the intake system described in Patent Document 1, the shaft portion of the proximal end of the intake control valve provided on the upstream side of the partition wall of the intake port is pivotally connected to the lower wall of the intake port so as to be rotatable. By rotating the intake control valve around the shaft and lowering along the inner surface of the lower wall, the upstream opening of the lower passage opens, and intake flows in both the upper and lower passages, and the intake control valve By pivoting upward so that the end edge contacts the upstream edge of the partition wall, the upstream opening of the lower passage is closed, and the intake air flows only in the upper passage.
Therefore, immediately after the start of the engine, the intake control valve closes the upstream opening of the lower passage, and the intake passage flows in the upper passage and enters the combustion chamber to generate a strong vortex tumble to increase the combustion efficiency.

In the medium load region of the internal combustion engine, if the vortex of the tumble is too strong, rapid combustion may prevent reduction in fuel consumption, and crank noise may occur due to rapid combustion.
Therefore, in the medium load region, it is desirable to suppress intake air flowing in the passage above the intake port, but in intake control by the intake control valve described in Patent Document 1, only the upstream side opening of the upper passage is partially It can not be closed to suppress intake air flowing in the upper passage.

The present invention has been made in view of such a point, and the purpose of the present invention is to make it possible to selectively distribute the amount of intake air flowing in the upper and lower passages according to the load condition and adjust the strength of the vortex of the tumble. The point is to provide an intake system of an internal combustion engine capable of optimizing the combustion efficiency.
Another object of the present invention is to generate a strong vortex tumble in a low load region, suppress the occurrence of tumble in a medium load region, and maximize cylinder intake capacity in a high load region. The point is to provide an intake system for an internal combustion engine which can optimize the combustion efficiency by adjusting the strength of the vortex of the tumble according to the load condition.

In order to achieve the above object, according to the present invention, a combustion chamber is formed between a top surface of a piston slidably fitted in a cylinder bore of a cylinder block and a ceiling surface of a cylinder head opposite to the top surface. And an intake port and an exhaust port are formed extending from the intake valve port and the exhaust valve port opened in the ceiling surface of the cylinder head while being curved away from each other, and an inlet pipe is connected to the intake port to be continuous The inlet pipe is provided with a throttle valve and an intake distribution valve downstream of the throttle valve, and the intake The intake air is divided into the side intake passages and the intake flow control valve controls the intake air flowing through the upper intake passage and the lower intake passage, and the intake control means In the intake system of an internal combustion engine in which a vent valve is drive-controlled, the intake distribution valve is provided adjacent to the upstream edge of the partition plate, and distributes intake air downstream from the throttle valve up and down and the upper intake passage An intake system for an internal combustion engine is provided, wherein a ratio of intake air flowing through the lower intake passage is changed.

According to a preferred embodiment of the present invention, the intake distribution valve is pivotally attached at a proximal end thereof to the inlet pipe at a position adjacent to the upstream end edge of the partition plate to raise and lower a tip directed to the intake upstream side. It is a swingable flap valve.

In a preferred embodiment of the present invention, a passage cross-sectional area of the upper intake passage is smaller than a passage cross-sectional area of the lower intake passage.

Preferably, the downstream end of the divider is within the intake port and adjacent to the intake valve stem.

According to a preferred embodiment of the present invention, in the ceiling surface of the cylinder head, the intake valve port and the exhaust valve port face the combustion chamber one by one at mutually opposite positions with respect to a cylinder axis which is a central axis of a cylinder bore. The intake valve port is formed so as to be offset so as to have a crescent-shaped protruding portion which protrudes outside in the cylinder axial direction from the circular hole of the cylinder bore.

In the intake system of the internal combustion engine according to the present invention, when the internal combustion engine is in a low load state, the intake control means distributes the intake most to the upper part to flow through the upper intake passage at a low load position Positioning the intake distribution valve at a medium load position so as to suppress the intake air flowing in the upper intake passage by dividing the ratio of the intake air upwards from the lower when the medium load state and when the load state is high Operates to position the intake distribution valve at a high load position so as to distribute the intake air vertically to the ratio divided by the partition plate.

In a preferred embodiment of the present invention, an upper injector and a lower injector for injecting fuel into the upper intake passage and the lower intake passage of the inlet pipe, respectively, are provided, and the upper side according to the swing state of the intake distribution valve. The injection amount of the injector and the lower injector is controlled.

According to the intake system of the internal combustion engine of the present invention, the intake distribution valve is provided adjacent to the upstream edge of the partition plate, and distributes intake air downstream from the throttle valve up and down to the upper intake passage and the lower intake passage. Since the ratio of intake air flowing is changed, the amount of intake air flowing through the upper and lower passages can be appropriately selectively distributed according to the load state, and the strength of the vortex of the tumble can be adjusted to optimize the combustion efficiency.

Since the intake distribution valve is a flap valve, the proximal end of which is pivotally supported by the inlet pipe at a position adjacent to the upstream end edge of the partition plate so that the tip toward the intake upstream side can swing up and down. The rate at which the intake air is divided up and down can be easily changed according to the swing position of the tip of the valve.

The passage cross-sectional area of the upper intake passage is smaller than the passage cross-sectional area of the lower intake passage, so that in a low load state, the intake air flows rapidly through the narrow upper intake passage and is sucked into the combustion chamber. Vortex tumble can be generated to improve combustion efficiency.

Since the downstream end of the partition plate is in the intake port and located in the vicinity of the intake valve stem, the intake air passing through the upper intake passage can be guided to the vicinity of the intake valve port under a low load condition. Tumble can be easily generated.

An intake valve port is formed by offsetting one intake valve port formed on the ceiling surface of the cylinder head so as to have a crescent-shaped protruding portion that protrudes outward in a cylinder axial direction from the circular hole of the cylinder bore The ratio of the opening circumferential length of the protruding part to the entire opening length of the opening can be secured, and the intake to the combustion chamber of the intake from the outer edge side (protruding part side) of the intake valve port is blocked. By suppressing the generation of the reverse tumble which suppresses the tumble generated due to the inhalation, the generation of the strong vortex tumble can be promoted.

When the internal combustion engine is in a low load state, the intake control means can position the intake flow distribution valve at a low load position to form a strong vortex tumble flow so that the intake air is mostly distributed upward and flows through the upper intake passage. In the medium load state, the intake distribution valve is positioned at the medium load position so that the intake flow is distributed to the upper intake passage by reducing the ratio of the upper part lower than the lower part to minimize the vortex vortices of the tumble and prevent rapid combustion. When the load is high, the intake distribution valve is positioned at the high load position to distribute the intake air vertically to the ratio divided by the partition plate so that sufficient intake flows in the upper intake passage, so that the vortex flow is moderate. Tumble can be generated and intake efficiency can be favorably maintained, and the strength of the vortex of the tumble can be adjusted according to the load state of the internal combustion engine to optimize the combustion efficiency. It is possible to reduce the fuel consumption.

An upper injector and a lower injector performing fuel injection to the upper intake passage and the lower intake passage of the inlet pipe, respectively, and controlling the injection amount of the upper injector and the lower injector according to the swing state of the intake distribution valve Thus, the combustion efficiency is further improved and the air fuel ratio is optimized by optimally controlling the injection amounts of the upper injector and the lower injector according to the swing state of the intake air distribution valve, that is, the vertical distribution state of the intake flow rate. Can.

FIG. 1 is a right side view of a motorcycle equipped with an internal combustion engine equipped with an intake system according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional right sectional view of the same internal combustion engine. It is a top view of a cylinder block. It is a bottom view of a cylinder head. It is expansion explanatory drawing of the ceiling surface of a combustion chamber. FIG. 2 is a cross-sectional view of an essential part of the internal combustion engine in a low load state. FIG. 2 is a cross-sectional view of an essential part of the internal combustion engine in a medium load state. FIG. 2 is a cross-sectional view of an essential part of the internal combustion engine in a high load state. It is the IX-IX sectional view taken on the line of FIG. FIG. 7 is a cross-sectional view taken along the line XX in FIG. It is a graph which shows control of intake distribution valve-opening degree (phi) with respect to throttle-opening degree (theta), and the change of tumble ratio Rt. It is principal part sectional drawing of an internal combustion engine provided with the intake device which concerns on another embodiment. FIG. 13 is a cross-sectional view taken along line XIII-XIII of FIG. 13 is a graph showing control of an intake distribution valve opening degree φ and a fuel injection ratio r with respect to a throttle opening degree θ in the embodiment of FIG. 12;

Hereinafter, an embodiment according to the present invention will be described based on FIGS. 1 to 11.
FIG. 1 is an overall side view of a motorcycle 1 equipped with an internal combustion engine 10 equipped with an intake system according to the present embodiment.

The body frame 2 of the motorcycle 1 has a pair of left and right

main frame pipes

2b, 2b extending rearward from the head pipe 2a, and the

main frame pipes

2b, 2b extend rearward and then bend downward. The steep slopes 2ba and 2ba are formed. Lower portions of the steep slopes 2ba and 2ba are bent forward and reach lower ends.
Further, a pair of left and right down

frame pipes

2c, 2c extend downward from the head pipe 2a at a steep angle, substantially in parallel to the steeply inclined portion 2ba of the main frame pipe 2b in a side view.

Seat rails

2d, 2d extend rearward from the upper portions of the steep slopes 2ba, 2ba of the

main frame pipes

2b, 2b, and connect the central portions of the

seat rails

2d, 2d with the lower portions of the steep slopes 2ba, 2ba Back stays 2e, 2e support the

seat rails

2d, 2d.

In the vehicle body frame 2 as described above, the front fork 3 is pivotally supported by the head pipe 2a, the front wheel 4 is pivotally supported at its lower end, and the pivot plate 2f is fixed to the lower front of the

main frame pipes

2b, 2b. A rear fork 5, whose front end is pivotally supported by the pivot plate 2f, extends rearward, a rear wheel 6 is pivotally supported at the rear end, and a rear is interposed between the rear of the rear fork 5 and the central portions of the

seat rails

2d, 2d. A cushion 7 is interposed.
A fuel tank 8 is installed on the

main frame pipes

2b and 2b, and a seat 9 is supported by

seat rails

2d and 2d behind the fuel tank 8.

The internal combustion engine 10 mounted on the vehicle body frame 2 is a SOHC type two-valve single-cylinder four-stroke internal combustion engine, with the crankshaft 12 (FIG. 2) oriented in the vehicle width direction with respect to the vehicle It is suspended in the standing posture.

As shown in FIG. 2, in the crankcase 11 rotatably supporting the crankshaft 12 of the internal combustion engine 10, a transmission gear is provided between the main shaft 13 and the countershaft 14 disposed behind the crankshaft 12. A mechanism 15 is arranged. The counter shaft 14 is an output shaft, and a chain (not shown) is bridged between the counter shaft 14 and the rotation shaft of the rear wheel 6, and power is transmitted from the output shaft to the rear wheel 6 through the chain.

Referring to FIG. 2, on the crankcase 11 is mounted a cylinder block 16 in which a cast iron cylinder liner 16L is cast, and a cylinder head 17 is mounted on the cylinder block 16 via a gasket. The cylinder block 16 and the cylinder head 17 are integrally fastened by stud bolts, and the cylinder head cover 18 covers the upper side of the cylinder head 17.
The cylinder block 16, the cylinder head 17, and the cylinder head cover 18, which are stacked on the crankcase 11, extend upward in a posture slightly inclining from the crankcase 11 (see FIGS. 1 and 2).

The inlet pipe 20 extends rearward from the cylinder head 16 erected slightly forward of the internal combustion engine 10 mounted on the vehicle body frame in this manner via the connecting pipe 19, and the inlet pipe 20 receives a throttle valve. A butterfly type throttle body 21 having a built-in 22 is provided, an injector 23 is mounted, and an intake air distribution valve 61 described later is provided.

As shown in FIG. 1, the air cleaner 24 connected to the rear end of the inlet pipe 20 is disposed in a space surrounded by the steeply inclined portion 2ba of the main frame 2b, the seat rail 2d and the backstay 2e in a side view. (See Figure 1).
Further, an exhaust pipe 27 extending forward from the cylinder head 17 is bent downward and further bent backward so as to be disposed rearward and rightward along the lower surface of the crankcase 11 and disposed on the right side of the rear wheel 6 It is connected to the muffler 26.

Referring to FIG. 2, the crankcase 11 is divided into right and left portions and consists of left and right crankcase halves, and the lower end portion of the cylinder liner 16L is fitted into the opening formed in the mating surface of the left and right crankcase halves. Slightly forward and protruding upward. A piston 25 is slidably fitted in a cylinder bore 16b of the cylinder liner 16L in a reciprocating manner, and a connecting rod 26 is connected between a piston pin 25p of the piston 25 and a crank pin 12p of the crankshaft 12 to provide a crank mechanism. Are configured.

A combustion chamber 40 is formed between the top surface 25 t of the piston 25 sliding in the cylinder bore 16 b of the cylinder block 16 and the ceiling surface 41 of the cylinder head 17 opposite to the top surface 25 t.
In the cylinder head 17, an intake valve port 42 and an exhaust valve port 43 (FIG. 4, FIG. 6) are provided at the ceiling surface 41 one by one at diametrically opposite positions with respect to the cylinder axis C which is the central axis of the cylinder bore 16b. The intake port 44 and the exhaust port 45 extend from the intake valve port 42 and the exhaust valve port 43 while curving in directions away from each other.

In FIG. 2, the intake port 44 extends from the intake valve port 42 to the rear of the two-wheeled vehicle and communicates with the inlet pipe 20 via the connection pipe 19, and the exhaust port 45 is connected to the exhaust pipe 27 (FIG. 1).
An intake valve 46 and an exhaust valve 47 slidably supported by valve guides 34 i and 34 e integrally fitted to the cylinder head 16 are driven by a valve mechanism 30 provided on the cylinder head 13, The intake valve port 42 of the intake port 44 and the exhaust valve port 43 of the exhaust port 45 are opened and closed in synchronization with the rotation of the crankshaft 12.

The valve operating mechanism 30 is a valve operating mechanism of the SOHC type internal combustion engine in which one cam shaft 31 is axially supported on the cylinder head 17 in the left-right direction. Rocker arm shafts 32e and 32i are supported diagonally front and rear of cam shaft 31, and intake rocker arm 33i is pivotally pivotally supported at the rear by rocker arm shaft 32i at the center, and exhaust rocker arm 33e is freely pivotable at front rocker arm shaft 32e. The center is centrally supported.

One end of the intake rocker arm 33i is in contact with the intake cam lobe of the camshaft 31, and the other end is in contact with the upper end of the valve stem 46s of the intake valve 46 biased by a spring via an adjustment screw, and one end of the exhaust rocker arm 33e is a cam The other end is in contact with the upper end of the valve stem 47s of the exhaust valve 47, which is in contact with the exhaust cam lobe of the shaft 31 by a spring, via an adjustment screw, and the intake rocker arm 33i and the exhaust rocker arm 33e swing by rotation of the camshaft 31 Then, the intake valve 46 and the exhaust valve 47 are driven to open and close.

FIG. 3 is a top view of the cylinder block 16. A circular hole of the cylinder bore 16b and a rectangular hole of a chain chamber 16c for inserting a chain for transmitting power to the valve mechanism 30 are bored in the mating face 16f with the cylinder head 17. It is done.
FIG. 4 is a bottom view of the cylinder head 17 superimposed on the cylinder block 16. The ceiling surface 41 of the combustion chamber 40 is recessed corresponding to the cylinder bore 16b in the mating surface 17f opposite to the mating surface 16f in the cylinder block 16. And a chain chamber 17c communicating with the chain chamber 16c.

The circular opening edge 41s of the ceiling surface 41 of the combustion chamber 40 at the mating surface 17f of the cylinder head 17 coincides with the circular hole of the cylinder bore 16b.
A large-diameter intake valve port 42 opens on the rear side of the ceiling surface 41, and an exhaust valve port 43 having a diameter slightly smaller than that of the intake valve port 42 opens on the front side of the ceiling surface 41.
Further, in the ceiling surface 41, a plug hole 48 is formed in which a spark plug (not shown) projects a tip end.

FIG. 5 is a view of the combustion chamber 40 of the cylinder head 17 in the axial direction of the cylinder axis C, ie, in the cylinder axial direction. Referring to FIG. 5, the intake valve port 42 is a combustion chamber A part of the intake valve port peripheral portion protrudes outward and is offset from the circular ceiling surface opening edge 41s corresponding to the circular hole of the cylinder bore 16b of the ceiling surface 41 of 40, and the intake valve port 42 It has a crescent-like protruding portion 42a (portion indicated by a scattering point in FIG. 5) protruding from the ceiling surface opening edge 41s.

Assuming that the ratio of the opening circumferential length of the protruding portion 42a to the entire circumferential length of the opening edge 42s of the intake valve port 42 is a masking ratio Rm, the masking ratio Rm by the offset of the main intake valve port 42 is about 20 to 50%.

Further, referring to FIG. 5, the ceiling surface 41 is formed with a dome-shaped concave portion 51 having an elliptical cross-sectional shape surrounding the intake valve port 42 and the exhaust valve port 43 on both sides in the major axis direction, In the ceiling surface 41,

squish

52, 52 is formed on a pair of left and right crescent-shaped portions outside the dome-shaped recess 51, respectively.

Then, around the outer periphery of the intake valve port 42, a pair of guide wall surfaces 53, 53 curved along the opening edge 42s of the intake valve port 42 from both ends of the crescent-shaped protruding portion 42a of the intake valve port 42, They are formed so as to face each other and gradually expand toward the exhaust valve port 43 side.

With respect to the ceiling surface 41 of the combustion chamber 40 of the cylinder head 17 formed as described above, the cylinder bore 16b of the cylinder block 16 corresponds to the cylinder of the cylinder bore 16b as shown in FIGS. The rear end of the opening edge on the head 17 side facing the protruding portion 42a of the intake valve port 42 is cut out along the periphery of the bulk portion 46p of the intake valve 46 in the moving direction of the intake valve 46 to the maximum valve lift position A circular curved surface 55 is formed.

As shown in FIGS. 7, 8 and 9, the notched circular curved surface 55 covers the upper end surface of the flangeless cylinder liner 16L of the aluminum alloy cylinder block 16 into which the cast iron cylinder liner 16L is cast. It is cut out and formed in a part at an angle.

Since the periphery of the bulk portion 46p of the intake valve 46 moves close to the notch circular curved surface 55 along the notch circular curved surface 55, the intake valve opening 42 moves while the intake valve 46 opens and moves to the maximum valve lift position. The intake air from the outer edge side (protruding part 42a side) of the valve must pass through a very narrow gap between the rim 46p edge of the intake valve 46 and the notched circular curved surface 55, and the intake to the combustion chamber 40 is blocked substantially. In a state of being

Therefore, masking is performed from the outer edge side of the intake valve port 42, and only a small amount of intake air is drawn into the combustion chamber 40, and the intake from the inner edge side of the intake valve port 42 becomes main. Has a structure that is easy to occur.
The maximum valve lift position of the intake valve 46 may be slightly beyond the notch circular curved surface 55.

As shown in FIG. 6, a portion of the peripheral portion of the top surface 25t of the piston 25 facing the protruding portion 42a of the intake valve port 42 is cut out parallel to the end face of the peripheral portion 46pf of the intake valve 46 to cut the piston The notch surface 56 is formed (see FIG. 6), and when the intake valve 46 is opened and lifted as the piston 25 descends in the intake stroke, the inflow direction of the intake air from the outer edge side of the intake valve port 42 Since the notch surface (56) is vertical, the intake of the intake air is not prompted from the outer edge side of the intake valve port 42 to the combustion chamber 40, and the occurrence of reverse tumble is further suppressed.

Then, in the intake system, the intake passage P from the inlet pipe 20 to the intake port 44 via the connection pipe 19 passes from the downstream portion of the inlet pipe 20 to the curved portion of the intake port 44 by the partition plate 60 to the upper intake passage Up and down. It is divided into the side intake passage Lp.

The partition plate 60 is integrally formed with the inlet pipe 20, and the upstream end of the partition plate 60 is provided inside the inlet pipe 20 so as to divide the upper and lower portions, and the extension portion greatly projecting downstream is the intake port 44. Is inserted in the
As shown in FIG. 9, both side edges of the strip-like extending portion of the partition plate 60 extend along the inner peripheral surface of the intake port 44.
The partition plate 60 moves the intake passage P upward, and the passage cross-sectional area of the upper intake passage Up is smaller than the passage cross-sectional area of the lower intake passage Lp (see FIG. 9).

The elongated extension of the partition plate 60 is bent along the curved shape of the intake port 44, and as shown in FIG. 10, the downstream end 60 e of the tip is an intake valve located at the curved portion of the intake port 44. The intake valve stem 46s reaches 46 and the downstream end 60e is formed with a recess 60u which is recessed in a U-shape from the tip edge, and the intake valve stem 46s penetrates the U-shaped recess 60u .

The downstream end 60 e is a flat, non-curved plate and is linearly inserted into the curved portion of the intake port 44, and the left and right sides of the downstream end 60 e are opposed to the left and right of the curved portion of the intake port 44. It is inserted into the formed left and right recessed

grooves

44v and 44v and fixedly supported.

In the inlet pipe 20, an intake air distribution valve 61 is provided upstream of the partition plate 60 downstream of the throttle valve 22.
Referring to FIGS. 6, 7 and 8, in the intake air distribution valve 61, the pivot shaft 61a at the base end is pivoted on the inlet pipe 20 in the vicinity of the upstream edge of the partition plate 60 and directed to the intake upstream side. It is a flap valve in which the tip end is pivotable up and down, and is pivoted by the motor drive mechanism 62.

The intake air distribution valve 61 swings its tip toward the upstream throttle valve 22 to distribute the intake air downstream of the throttle valve 22 up and down and change the ratio of intake air flowing through the upper intake passage Up and the lower intake passage Lp. can do.

The ECU (electronic control unit) 65 (FIG. 2) for controlling the internal combustion engine 10 is provided with an intake control means 66, analyzes the operating state of the internal combustion engine 10 and uses the intake control means 66 to The injector 23 is driven and controlled, but the intake distribution valve 61 is also driven and controlled by the intake control means 66.

Referring to FIG. 6, the throttle opening degree θ of the throttle valve 22 is fully open when it is rotated from the fully closed position and becomes parallel to the intake passage, and indicates the load state of the internal combustion engine 10.
The intake distribution valve 61 is controlled to swing according to the load state of the internal combustion engine 10, and the intake distribution valve opening degree φ, which is the swing angle of the intake distribution valve 61, corresponds to the intake distribution in the low load state shown in FIG. The swing angle increases clockwise in FIG. 6 with the low load position of the valve 61 as the reference 0 degree.

The state of the tumble can be represented by a tumble ratio Rt which is the number of revolutions of the tumble per revolution of the crankshaft 12.
Tumble Ratio Rt = Tumble Rotational Angular Velocity / Crankshaft Angular Velocity If the tumble ratio Rt is large, strong vortex tumble occurs.

FIG. 11 shows a change in the intake distribution valve opening degree φ and a change in the tumble ratio Rt that perform swing control of the intake distribution valve 61 according to the throttle opening degree θ.
Hereinafter, the swing control of the intake air distribution valve 61 and the tumble ratio Rt according to the load state of the internal combustion engine 10 will be considered with reference to FIG.

When the internal combustion engine 10 is in a low load operation state, as shown in FIG. 6, the throttle valve 22 is opened small (throttle opening degree θ: small), and the leading edge of the intake distribution valve 61 is on the lower side of the intake passage P. Because the intake distribution valve 61 is positioned at a low load position (intake distribution valve opening degree φ = 0 degree) in contact with the circumferential surface, the intake distribution valve 61 distributes the intake air mostly to the upper side, and the intake flows through the upper intake passage Up.

Therefore, the intake air passing through the slightly open opening of the throttle valve 22 is guided and flowed to the relatively narrow upper intake passage Up mostly by the intake distribution valve 61, and the intake port 44 is further curved. Is guided to a position close to the intake valve port 42 by the partition plate 60 extending to the intake valve stem 46s located in the lower part, so most of the intake air is from the inner edge side (cylinder axis C side) of the intake valve port 42 As shown in FIG. 6, a strong vortex tumble occurs (the tumble ratio Rt increases).

The intake valve port 42 is offset so as to have a crescent-shaped protruding portion 42a that protrudes outward in a cylinder axial direction from the circular hole of the cylinder bore 16b, and the outer edge side (protruding portion 42a side) of the intake valve port 42 is masked. And, since there is almost no intake air passing through the lower intake passage Lp, there is no intake air to be taken into the combustion chamber 40 from the outer edge side of the intake valve port 42, and no reverse tumble that interferes with tumble occurs, which makes the tumble stronger. The tumble ratio Rt becomes high, and the combustion efficiency at low load can be improved.

When the internal combustion engine 10 is in a medium load operation state, as shown in FIG. 7, the throttle valve 21 opens to the middle opening degree (throttle opening degree θ: middle), and the intake distribution valve 61 has a tip edge at the upper side of the intake passage P. It is positioned at a middle load position (intake distribution valve opening degree φ = β degree) approaching the circumferential surface. Therefore, the intake air distribution valve 61 distributes the intake air at a lower rate than the lower side.
Therefore, as indicated by the arrows in FIG. 7, sufficient intake air flows through the lower intake passage Lp, but intake air flowing through the upper intake passage Up is suppressed.

Therefore, even if the suppressed intake air flowing through the upper intake passage Up enters the combustion chamber 40 from the inner edge side of the intake valve port 42, the suppressed intake air is weak and only a weak swirl of tumble flow is generated. Since there is some intake air sucked into the combustion chamber 40 from the outer edge side of 42 and a reverse tumble is generated to suppress the tumble, the tumble is suppressed as much as possible and the tumble ratio Rt is reduced.

When the internal combustion engine 10 is in a high load operation state, as shown in FIG. 8, the throttle valve 21 is fully opened (throttle opening degree θ: fully open) and the intake distribution valve 61 is in a high load position flush with the partition plate 60. It is positioned at (intake distribution valve opening degree φ = α degree). For this reason, the intake air distribution valve 61 distributes the intake air vertically to a ratio at which the intake air is divided by the partition plate (60).

Therefore, as indicated by arrows in FIG. 8, sufficient intake air flows through the upper intake passage Up and the lower intake passage Lp, and intake air flowing through the upper intake passage Up flows from the inner edge side of the intake valve port 42 to the combustion chamber 40. A tumble is generated by suction, and the intake air flowing through the lower intake passage Lp enters the combustion chamber 40 from the outer edge side of the intake valve port 42 and causes some reverse tumble while being masked, but from the upper intake passage Up Since a sufficient intake amount is inhaled, it is possible to generate moderate tumble flow tumbles having a relatively high tumble ratio Rt, and to maintain good intake efficiency with sufficient intake.

As described above, the intake system of the internal combustion engine 10 can optimize the combustion efficiency by adjusting the strength of the vortex of the tumble according to the load state of the internal combustion engine.

The intake distribution valve 61 is a flap valve in which a pivot shaft 61a at the base end is axially supported by the inlet pipe 20 in the vicinity of the upstream end edge of the partition plate 60 so that the tip toward the intake upstream side can swing up and down. Because of this, it is possible to easily change the rate at which the intake air is divided up and down depending on the swing position of the tip.

In the intake system according to the above-described embodiment, the injectors 23 are attached only to the upper intake passage Up among the upper intake passage Up and the lower intake passage Lp divided into upper and lower portions in the partition plate 60, but the lower intake passage Lp An embodiment equipped with an injector is also shown in FIG. 12 and FIG.
The upper injector 71 is attached to the upper intake passage Up, and the lower injector 72 is attached to the lower intake passage Lp. The other members are the same as those in the above embodiment, and the same reference numerals are used.

The fuel injection ratio r (lower injection amount / upper injection amount) of the upper injector 71 and the lower injector 72 is shown in FIG.
As the throttle opening degree θ increases, the intake air distribution valve opening degree φ is simply raised from 0 degree in the low load state to α degree in the high load state.

In the low load state, that is, when the intake air flows only in the upper intake passage Up, the fuel injection ratio r is 0% and the lower injector 72 does not inject fuel but injects only the upper injector 71.
As the throttle opening degree θ increases and the load increases, the amount of fuel injection of the lower injector 72 is increased as the proportion of intake air flowing through the lower intake passage Lp to the upper intake passage Up is increased by increasing the intake distribution valve opening φ. Increase the fuel injection ratio r.
Then, in the high load state, the fuel injection ratio r is made substantially equal to the ratio (the ratio of the intake air flowing in the lower intake passage Lp to the upper intake passage Up) with which the partition plate 60 divides the intake passage P up and down.

As described above, the injection amount (fuel injection ratio r) of the upper injector 71 and the lower injector 72 is optimally controlled according to the swing state of the intake air distribution valve 61, that is, the upper and lower distribution state (intake distribution valve opening degree φ) of the intake flow rate. Thus, the combustion efficiency can be further improved, and the air-fuel ratio (A / F) can be optimized.

DESCRIPTION OF SYMBOLS 1 ... Motorcycle, 2 ... Body frame, 10 ... Internal combustion engine, 11 ... Crank case, 12 ... Crankshaft, 13 ... Main axis, 14 ... Counter axis, 16 ... Cylinder block, 16b ... Cylinder bore, 17 ... Cylinder head, 18 ... Cylinder head cover, 19 ... Coupling pipe,
Reference Signs List 20: inlet pipe, 21: throttle body, 22: throttle valve, 23: injector, 24: air cleaner, 25: piston, 26: connecting rod,
Reference Signs List 30 valve operating mechanism 31 cam shaft 32 e 32 i rocker arm shaft 33 i intake rocker arm 33 e exhaust rocker arm 34 i 34 e valve guide
40 combustion chamber 41 ceiling surface 42 intake valve port 42a protruding part 43 exhaust valve port 44 intake port 45 exhaust port 46 intake valve 46pf bulkhead 46s intake Valve stem, 47 ... exhaust valve, 48 ... plug hole,
51: dome-shaped concave portion, 52: squish, 53: guide wall surface, 55: notched circular curved surface, 56: piston notched surface,
DESCRIPTION OF SYMBOLS 60 ... Partition plate, 61 ... Intake distribution valve 62 ... Motor drive mechanism, 65 ... ECU, 66 ... Intake control means, 71 ... Upper injector, 72 ... Lower injector.
Up ... upper intake passage, Lp ... lower intake passage, P ... intake passage.

Claims

Combustion occurs between the top surface of the piston (25) slidably fitted in the cylinder bore (16b) of the cylinder block (16) and the ceiling surface (41) of the cylinder head (17) opposite to the top surface A room (40) is constructed,
While the intake port (44) and the exhaust port (45) are curved away from each other from the intake valve port (42) and the exhaust valve port (43) opened in the ceiling surface (41) of the cylinder head (17) Extended out,
An inlet pipe (20) is connected to the intake port (44) to form a continuous intake passage (P),
The inlet pipe (20) is provided with a throttle valve (22) and an intake air distribution valve (61) downstream thereof.
The intake passage (P) is divided into an upper intake passage (Up) and a lower intake passage (Lp) partially by a partition plate (60) downstream of the intake distribution valve (61), and the intake distribution valve (P) 61) controls the intake air flowing through the upper intake passage (Up) and the lower intake passage (Lp),
In an intake system of an internal combustion engine in which the intake distribution valve (61) is drive-controlled by an intake control means (66),
The intake distribution valve (61) is provided adjacent to the upstream end edge of the partition plate (60), and distributes intake air downstream from the throttle valve (22) up and down and the upper intake passage (Up) and the lower portion. An intake system for an internal combustion engine, wherein a ratio of intake air flowing through a side intake passage (Lp) is changed.
The intake distribution valve (61) is pivotally attached at a base end thereof to the inlet pipe (20) at a position adjacent to the upstream end edge of the partition plate (60) and swings the tip directed to the intake upstream side up and down 2. An intake system for an internal combustion engine according to claim 1, wherein said intake valve is a flexible flap valve.
The intake system for an internal combustion engine according to claim 1 or 2, wherein a passage sectional area of the upper intake passage (Up) is smaller than a passage sectional area of the lower intake passage (Lp).
The downstream end (60e) of the partition (60) is located in the intake port (44) and adjacent to the intake valve stem (46s). An intake system for an internal combustion engine according to any one of the above.
In the ceiling surface (41) of the cylinder head (17), the intake valve port (42) and the exhaust valve port (43) are disposed opposite to each other with respect to a cylinder axis (C) which is a central axis of the cylinder bore (16b). ) Is opened toward the combustion chamber (40), and the intake valve port (42) has a crescent-shaped protruding portion (42a) protruding outward from the circular hole of the cylinder bore (16b) in the cylinder axial direction. The intake system for an internal combustion engine according to any one of claims 1 to 4, which is formed offset.
When the internal combustion engine is in a low load state, the intake control means (66) positions the intake distribution valve (61) at a low load position so as to distribute intake mostly to the upper part and to flow through the upper intake passage (Up). When the medium load condition, the intake distribution valve (61) is positioned at the medium load position so that the ratio of the intake to the upper part of the lower part is small and the intake air flowing through the upper intake passage (Up) is suppressed. The internal combustion engine according to claim 5, characterized in that the intake air distribution valve (61) is positioned at a high load position so as to distribute the intake air vertically at a ratio divided by the partition plate (60) in the loaded state. Inspiratory system.
An upper injector (71) and a lower injector (72) for injecting fuel into the upper intake passage (Up) and the lower intake passage (Lp) of the inlet pipe (20);
The intake control means (66) controls the injection amount of the upper injector (71) and the lower injector (72) according to the swing state of the intake distribution valve (61). An intake system for an internal combustion engine according to any one of claims 1 to 6.