JP3012024B2 - Engine intake control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake control system for an engine provided with an intake control valve for changing the cross-sectional area of an intake passage. To improve the shape and structure around the intake control valve so that the pressure does not increase.

[0002]

2. Description of the Related Art An intake control device for an engine generates a so-called vertical swirl by stabilizing lean air-fuel ratio combustion by increasing the flow velocity even when the intake air amount is small, such as at low speed rotation or low load operation. This is a device for improving the fuel consumption rate (hereinafter referred to as fuel efficiency). Conventionally, as an intake control device capable of generating such a vertical swirl, as disclosed in Japanese Patent Publication No. 59-5767, for example, an intake control plate is arranged so as to be able to undulate near an intake valve opening of an intake passage,
In some cases, the control plate is raised during low-speed rotation or low-load operation to reduce the intake passage area.

[0003]

However, in the above-mentioned conventional intake control device, the control plate remains in the intake passage even when it is fully opened due to the structure of raising and lowering the control plate. There is a problem that intake resistance becomes large.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide an intake control device for an engine which can avoid an increase in intake resistance at the time of high-speed rotation or the like.

[0005]

According to a first aspect of the present invention, an intake valve is disposed in an intake valve opening that opens to a combustion chamber, and the intake valve opening has a bent portion that is bent outward from the intake valve opening. Following this, in the intake control device for the engine, which extends to the outer wall of the cylinder head through an intake passage consisting of a linear portion which extends substantially linearly and whose axial line is inclined so that the axial line approaches the mating surface with the cylinder block toward the intake valve opening side. When the plate-shaped intake control valve for changing the cross-sectional area of the intake passage is viewed in the cam axis direction, the portion between the bottom wall surface of the linear portion of the cylinder head and the mating surface on the cylinder block side is closer to the tip end. The intake control valve is disposed so as to be able to advance and retreat in a state of being inclined away from the mating surface, and to be able to protrude from the bent portion into the intake passage. Protruding into the passage Is advanced to along approximately the bottom wall surface of the parts, at high load and high-speed rotation range is characterized in that so as to retract to the front end portion becomes the intake passage wall substantially flush.

[0006]

According to the intake control device of the present invention, when the intake air amount is small, such as during low-speed rotation, the intake control valve advances to the closed position to reduce the intake passage area from outside the bent portion. As a result, the flow velocity of the intake air is increased, and at the same time, the intake air flows along the ceiling wall of the intake passage, and is blown directionally near the center of the combustion chamber, so that vertical swirl is reliably generated.
Also, when the intake air amount is large, such as during high-speed rotation, the intake control valve is retracted to the open position, and the intake concave portion thereof is substantially flush with the wall surface of the air passage. It flows through the entire passage without resistance and is blown into the combustion chamber. As described above, in the present invention, the intake control valve has a plate shape,
In the low-load / low-speed rotation region, the bent portion protrudes into the intake passage, and the protruding portion is substantially along the bottom wall surface of the straight portion. Therefore, the flow of the intake air from the center of the combustion chamber in the axial direction becomes smooth, The intake air can be directed in the cylinder axis direction and flow into the cylinder bore, thereby reliably generating vertical swirl and improving the combustibility. Also, since the flow of the intake air to the center of the combustion chamber is smooth, fuel accumulation can be avoided. In addition, the control valve does not remain in the intake passage at the time of high-speed rotation or the like, and an increase in intake resistance due to the provision of the control valve can be avoided. Since the straight portion of the intake passage is inclined so as to be closer to the mating surface as the intake valve is opened, the intake control valve is inclined so as to be more distant from the mating surface as the tip side (intake valve opening side). Since the intake passage and the intake control valve are separated from each other, a space for disposing the drive mechanism of the intake control valve can be easily secured.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to 4 are views for explaining an intake control device for a four-valve engine according to an embodiment of the present invention.

In the figure, 1 is a water-cooled 4-cycle parallel 4
It is a four-cylinder cylinder engine,
The cylinder block 3 and the cylinder head 4 are stacked on the upper side in a forwardly inclined state, connected by a head bolt 6, and a head cover 5 is put on the upper mating surface of the cylinder head 4. A piston 7 is slidably inserted into each of the four cylinder bores 3a formed in the cylinder block 3, and each piston 7 is connected to a crankshaft (not shown) by a connecting rod 8.

A lower surface 4a of the cylinder head 4 on the side of the cylinder block 3 has a combustion recess 4b forming a combustion chamber.
Is recessed. An ignition plug 9 is screwed into the center of the combustion recess 4b, and two intake valve openings 4c and two exhaust valve openings 4d are opened around the plug 9. The valve plate 1 of the exhaust valve 10 is provided in each exhaust valve opening 4d.
In the intake valve opening 4c, a valve plate 11a of the intake valve 11 is disposed so as to open and close the openings 4d and 4c, respectively. The valve shafts 10b, 11b of the exhaust and intake valves 10, 11 extend obliquely in the cylinder axis direction so as to form a predetermined angle when viewed in the cam axis direction, and have exhaust and intake lifters 12, 13 at their upper ends. Are attached. Each lifter 1
Exhaust and intake camshafts 1 for driving them are provided on 2 and 13.
4 and 15 are arranged in a direction perpendicular to the cylinder axis and parallel to each other. Although not shown, the above exhaust,
A cam chain connecting the intake camshafts 14, 15 and the crankshaft is arranged in a chain chamber formed at the center of the four cylinder bores.

The two exhaust valve openings 4d are led out to the front wall 4f side of the cylinder head 4 through a bifurcated exhaust passage 16, and an exhaust pipe (not shown) is formed in the wall opening 16a of the exhaust passage 16. Is connected. The two intake valve openings 4c are led out to the rear wall 4g side of the cylinder head 4 through a forked intake passage 17. The intake passage 17 extends in a direction substantially perpendicular to the camshaft when viewed in the cylinder axis direction. When viewed in the camshaft direction, a bent portion bent in an arc shape from the intake valve opening 4c to the cylinder rear wall 4g side. 17b, and a straight portion 17d extending linearly from here. A carburetor 19 is connected to a wall opening 17 a of the intake passage 17 via a cab joint 18. The carburetor 19 is of an automatic variable venturi type having a butterfly type throttle valve 19a which opens and closes by a throttle operation, and a piston valve 19b which automatically opens and closes by negative pressure of the intake air of the engine. An air cleaner 20 is connected to a suction port 19 c of the vaporizer 19.

The straight portion 17d of the cylinder head 4
A guide groove 17c is formed between the cylinder and the lower joint surface 4a, one for each cylinder. The guide groove 17c penetrates from the cylinder rear wall 4g to the arc-shaped bent portion 17b of the intake passage, and is sandwiched between the axis of the straight portion 17d and a straight line perpendicular to the valve shaft 11b. Located within an angle. An intake control valve 2 for changing the passage cross-sectional area of the intake passage 17 is provided in the guide groove 17c.
1 is slidably disposed. The control valve 21 is a rectangular flat plate, and has a pair of intake recesses 21 at its tip.
a is formed in an arc shape. The intake recess 21a is formed in an arc shape and oblique so as to form a continuous surface with the bent portion 17b when fully opened. One end of a drive cable 22 is connected to the rear end of the control valve 21, and the other end of the cable 22 is connected to a throttle grip.
Reference numeral 22b denotes a bracket for fixing the drive cable 22 to the cylinder head, and reference numeral 22a denotes an urging spring for urging the control valve 21 to a fully closed position.

Next, the operation and effect of this embodiment will be described. When the intake air amount is small, such as when the engine is rotating at low speed or during low-load operation, as shown in FIG.
1 has advanced to the fully closed position. Therefore, the outside of the bent portion 17b of the intake passage 17 is narrowed, and only the center side is opened. As a result, the flow rate of the intake air is increased in the throttle section, and the air flows along the ceiling wall of the intake passage 17 and is blown directionally near the center of the combustion chamber. As shown by arrows in FIG. appear. In this case, since the intake control valve 21 is made to be plate-shaped and moved forward and backward,
The throttle portion can be provided in the immediate vicinity of the intake valve opening, and the directionality can be further ensured. As a result, even if the air-fuel ratio is made lean, the combustion can be stabilized, and the fuel efficiency can be improved.

When the intake air amount is large as in the case of high-speed rotation of the engine or high-load operation, as shown in FIG.
The intake control plate 21 retreats to the fully open position, whereby the intake concave portion 21a is substantially flush with the wall surface near the bent portion 17b of the air passage 17, and the intake control valve 21 does not become an intake resistance. Therefore, the large amount of intake air flows through the entire intake passage without resistance and is blown into the combustion chamber.

In this embodiment, the intake control valve 21 is disposed within an angle range formed by the axis of the straight portion 17d of the intake passage 17 and a line perpendicular to the valve shaft 11b. It protrudes along the bottom wall surface of the straight portion 17d. Therefore, the flow of the intake air becomes smooth, and the fuel does not accumulate in the protruding portion. Also, since the control valve 21 is arranged within the above-mentioned angle range, the reciprocating stroke of the control valve 21 can be small. By the way, if it is arranged outside the above angle range, for example, on the ceiling wall side of the intake passage 17, it will be arranged along the valve shaft 11b, and the reciprocating stroke will be greatly increased.
Furthermore, in this embodiment, since the intake control valve 21 is set to have a width corresponding to the intake passage 17, interference with the head bolt 6 can be avoided.

In the above-described embodiment, the shape of the intake recess 21a is adjusted to the shape of the intake passage 17, but the intake recess 21a may be formed in a U-shape as in the intake recess 21a 'shown by a two-dot chain line in FIG. good. By doing so, the intake passage can be narrowed further. In this case, as shown in FIG. 4, a dent a occurs in the intake concave portion of the intake passage at the time of full opening. However, since this control plate is plate-like and thin, it does not cause much problem. In the above embodiment, the intake control valve 21 is constituted by one piece. However, as shown by a two-dot chain line in FIG.
By arranging the control valve 22c on top of one another, a plurality of control valves can be configured. By doing so, the intake passage area when fully closed can be gradually narrowed, and the intake resistance when fully closed can be reduced.

As described above, according to the intake control apparatus for an engine according to the present invention, the intake control valve has a plate shape,
It is arranged so that it can advance and retreat, and the protrusion into the intake passage is roughly along the bottom wall surface of the straight part, so that the flow of intake air from the center of the combustion chamber in the axial direction is smooth, and the intake air is directed in the cylinder axis direction The vertical swirl can be reliably generated, the combustion characteristics can be improved, and the intake control valve can be prevented from remaining in the intake passage when fully opened, reducing the intake resistance. In addition, on the cylinder outer wall side, the intake passage and the intake control valve are separated from each other, and it is easy to secure a space for disposing the drive mechanism of the intake control valve.

[Brief description of the drawings]

FIG. 1 is a sectional side view showing an intake control device for an engine according to one embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III of FIG. 1;

FIG. 4 is a view corresponding to the time of high rotation of FIG. 3;

[Explanation of symbols]

 Reference Signs List 4 Cylinder head 4a Interfacing surface 4b Combustion recess (combustion chamber) 4c Intake valve opening 4g Rear wall 11 Intake valve 17 Intake passage 17b Bent portion 17d Linear portion 21 Intake control valve 21a Intake recess

Claims (1)

(57) [Claims] 1. A intake valve disposed in an intake valve opening which opens into the combustion chamber, the intake valve opening, extends substantially linearly followed by a bent portion that is bent outwardly from the intake valve opening, the Axis
Approaches the interface with the cylinder block closer to the intake valve opening side
In the intake control device of the engine led to the outer wall of the cylinder head through the intake passage composed of the linear portion inclined as
Looking at the plate-shaped intake control valve that changes the cross-sectional area of the intake passage in the cam axis direction,
The tip between the bottom wall and the mating surface on the cylinder block side
It is possible to move forward and backward in a state where the side is inclined away from the above joint surface
And the tip can protrude into the intake passage from the bent part.
The intake control valve at low load / low speed range.
The tip protrudes into the intake passage and
Move forward along the line, and at high load / high speed
Retract so that the end is almost flush with the intake passage wall
Intake control device for an engine is characterized in that the.