JP3222228B2 - 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 in which the area of an intake passage is controlled by an intake control valve, and more particularly, to an improvement in combustion stability in a state where the intake air amount is small. The present invention relates to a structure capable of improving a fuel efficiency in a low-medium-speed, low-load operation range.

[0002]

2. Description of the Related Art In order to improve the fuel efficiency of an engine, it is necessary to stabilize combustion at a lean air-fuel ratio by generating a vertical vortex (tumble) in a combustion chamber by increasing the flow velocity even when the intake air amount is small. It is known to be effective. As an intake control device capable of generating such a tumble, the present applicant has arranged an intake control valve that narrows a bottom wall side portion of the intake passage at a low intake air amount, and has a portion of the intake passage downstream of the intake control valve. And a rectifying member for rectifying the intake air to flow along the top wall of the intake passage. −360129). According to the proposed device, even when the amount of intake air is small, it is possible to give a directionality flowing vertically in the cylinder axis direction to the intake air flow and generate a tumble.

[0003]

In such an intake control device, a tumble pump is required to stabilize combustion at a low intake air amount and to further improve a fuel efficiency in an operation range such as a low to middle speed range. There is a demand for a device that can more effectively generate the noise.

The present invention has been made in view of such a demand, and an object of the present invention is to provide an intake control device for an engine capable of generating a tumble more effectively.

[0005]

According to the present invention, the intake air is biased toward the top wall of the intake passage by narrowing the bottom wall of the intake passage into the bottom wall of the intake passage when the amount of intake air is low. A rectifying member for rectifying the intake air at least in a portion of the intake passage downstream of the intake control valve along the top wall of the intake passage; At least a portion of the rectifying member near the intake valve opening is located closer to the center of the combustion chamber than the valve stem of the intake valve.

[0006]

According to the intake control apparatus for an engine according to the present invention, when the intake air amount is small, the intake control valve narrows the bottom wall portion of the intake passage, and the rectifying member is located downstream of the intake control valve. Since the intake air is rectified along the ceiling wall side, the inhaled air flows unevenly to the ceiling wall side portion having a small passage area and increases in speed. As a result, the intake air flowing into the cylinder is given a vertical direction flowing in the cylinder axial direction. As a result, a tumble is generated and lean combustion is performed stably. When the intake air amount is high, the intake control valve pivots to the fully open position, whereby the intake control valve does not stay in the intake passage, and an increase in intake resistance can be avoided.

Further, since the straightening member has a portion near the intake valve opening located closer to the center of the combustion chamber than the valve stem of the intake valve, the cross-sectional shape of the ceiling wall downstream portion of the intake passage is cam. It is elongated horizontally long in the axial direction,
As a result, tumble is easily generated in the combustion chamber. As a result, even when the intake air amount is small, the combustion can be further stabilized, and the fuel efficiency in an operation range such as a low to middle speed range can be further improved.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIGS. 1 to 5 are views for explaining an intake control device for an engine according to a first embodiment of the present invention.

Referring to FIG. 1, reference numeral 1 denotes a water-cooled four-cycle four-valve engine, in which a cylinder block 3 and a cylinder head 4 are stacked on a crankcase 2 and fastened with head bolts. It has a structure in which the head cover 5 is mounted on the surface 4i. A piston 7 is slidably inserted into a cylinder bore 3a formed in the cylinder block 3, and the piston 7 is connected to a crankshaft (not shown) by a connecting rod 8.

[0010] A combustion recess 4b constituting a combustion chamber is formed in the cylinder block 4 mating surface 4a of the cylinder head 4 in a recessed manner. The combustion recess 4b has two intake valve openings 4c and two exhaust valve openings 4d. The openings 4c and 4d are respectively formed by the openings of the generally ring-shaped valve seats 27 and 28 mounted on these portions. A valve head 10a of the exhaust valve 10 can be opened and closed in each exhaust valve opening 4d, and a valve head 11a of the intake valve 11 can be opened and closed in each intake valve opening 4c. It is arranged to be able to contact the seat surface. The valve stems 10b and 11b of the exhaust and intake valves 10 and 11 extend obliquely upward in the cylinder axis direction so as to form a predetermined included angle when viewed in the cam axis direction.
13 are mounted. Each lifter 12,
On the exhaust / intake camshaft 1 which presses and drives it,
4 and 15 are arranged in a direction perpendicular to the cylinder axis and parallel to each other. Reference numerals 12a and 13a denote valve springs for urging the respective valves in the closing direction, and 29 denotes a spark plug whose electrode portion is located at the center of the combustion chamber.

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. It is connected. In addition, each intake valve opening 4c
Are respectively led to the rear wall 4g side of the cylinder head 4 by the intake passage 17. The two intake passages 17 are parallel to each other and linear when viewed in the cylinder axis direction, and are bent in an arc shape from the intake valve opening 4c to the cylinder rear wall 4g side when viewed in the cam axis direction. Later, it extends substantially linearly. And each wall opening 1 of each intake passage 17
A common cab joint 18 is connected to 7a, and merges into one passage in the joint 18.
One carburetor 19 is connected to the cab joint 18. The carburetor 19 includes a butterfly type throttle valve 19a which opens and closes by a throttle operation, and a piston valve 19 which automatically opens and closes when the engine intake negative pressure is applied.
b) of an automatic variable venturi type.

A switching valve 26 is provided in the cab joint 18. The switching valve 26 includes a valve shaft 26a disposed to penetrate the joint 18 in parallel with the cam shaft direction, and a valve plate 26b fixed to the valve shaft 26a to open and close the one intake passage 17. It is configured.

A valve hole 1 is provided downstream of each of the intake passages 17.
7c is formed penetrating in the cam axis direction. This valve hole 17
As for c, the axis thereof is located near the surface of the bottom wall 17d of the intake passage 17, the inner portion of the intake passage 17 is formed in a substantially semicircular shape, and communicates with two adjacent cylinder intake passages. . In the valve hole 17c, an intake control valve 21 for changing the passage sectional area and the sectional shape of each intake passage 17 is provided.
Are inserted and arranged. The intake control valve 21 is formed by cutting out a part of a round bar so as to form a continuous surface with the lower inner surface of the intake passage 17 to form a valve portion 21a that opens and closes each intake passage 17. Portion 21a has valve hole 17c
And the valve portion 21a rises substantially perpendicularly from the bottom wall 17d to narrow the intake passage 17 to approximately half, and to reduce the intake passage shape to a cam. It is rotatable between a fully closed position (see FIG. 1) where the shape changes to an elongated horizontally long shape in the axial direction. In this case, the valve 21a rotates so that the outer peripheral surface of the valve 21a is located on the upstream side.

A control pulley 22a is fixed to an outer end of the intake control valve 21, and the control pulley 22a is connected to a drive pulley 22b fixed to a control motor by a cable. A switching pulley 26c is fixed to an outer end of the switching valve 26, and the switching pulley 26c is connected to a driving pulley 26d fixed to a switching motor by a cable. The control motor and switching motor are ECU
23 controls its rotation. This ECU 23
Receives the opening signal a of the throttle valve 19a from the throttle opening sensor 24 and the engine speed signal b from the rotation sensor 25, and sets the intake control valve 21 to
A control signal A for rotating to the fully closed position side as the amount of intake air is small, such as a low-medium speed / low load operation range, and to the fully open position side, as the amount of intake air is large as in a high speed / high load operation range
To the control motor, and outputs a control signal B to the switching motor to close the switching valve 26 in an operating range where the intake air amount is equal to or less than a predetermined value and to open the switching valve 26 in an operating range exceeding the predetermined value.

A rectifying member 30 is provided at a downstream opening of each of the intake passages 17. Each rectifying member 30
Is sandwiched between the downstream opening end and the valve seat 27. As shown in FIG. 3, each rectifying member 30 includes a disc-shaped base 40 and a rectifying plate 43 attached thereto.

A circular hole 40a is formed in the base 40, and upright wall portions 41 and 42 are formed in a part of the inner peripheral surface thereof.
Are formed. These upright wall portions 41 and 42 are not arranged facing each other in the diameter direction of the hole 40a, but are arranged so as to be deviated by the amount of deviation e as shown in FIG. In addition, engaging recesses 41a and 42a are formed in the upright wall portions 41 and 42, respectively. On the other hand, the flow straightening plate portion 43 has a long hole 43a into which the valve stem 11b is inserted, and a relief portion 43b for preventing interference with the valve stem 11b. Both ends of the lower part of the straightening plate portion 43 are engaged with the respective engaging recesses 41a and 42a of the vertical wall portions 41 and 42, and these engaging portions are attached by brazing or welding. As a result, the hole 40a of the base 40 is divided into a large area portion 44 and a small area portion 45 having a generally arcuate shape, and the valve stem 11b is arranged in the large area portion 44. That is, the lower part of the rectifying plate portion 43 forming the portion near the intake valve opening is located closer to the center of the combustion chamber than the valve stem 11b of the intake valve 11. When the rectifying member 43 is attached to the intake passage 17, the rectifying plate portion 43 extends substantially in the direction of the center line of the intake passage 17, and its upstream end 43 c is located at the fully closed position. It is located at the upper end of the valve portion 21a of the intake control valve 21 described above. As a result, the rectifying member 30 connects the intake passage 17 to the top wall 17f side portion C and the bottom wall 17d side portion D.
And rectifies the intake air to flow along the top wall 17f. In addition, the cross-sectional shape of the portion near the intake valve opening of the portion C on the side of the ceiling wall 17f has a horizontally long and arcuate shape elongated in the cam axis direction by the small area portion 45.

Here, various modes can be adopted for attaching each rectifying member 30 to each of the intake passages 17. For example, as shown in FIG. 5A, the upright wall 41 of one rectifying member 30 and the upright wall 42 of the other rectifying member 30 are arranged inside (on the side of the ignition plug 29), or as shown in FIG. Each standing wall portion 41 is arranged outside as shown, or
As shown in (c), each of the upright walls 41 may be arranged inside. By arranging the flow regulating members 30 in this manner, the intake valve openings are arranged in the cam shaft direction (FIG. 5) near the center of the combustion chamber (the center of the spark plug 29).
It has an elongated bow shape in the left-right direction (the direction perpendicular to the paper of FIG. 2).

Next, the operation and effect of this embodiment will be described. In an operation region where the required intake air amount is small, such as at low / medium speed / low load, the control motor rotates the intake control valve 21 to the fully closed position shown in FIG. The control motor B causes the switching motor to rotate the switching valve 26 to the closed position shown in FIG. Then, the valve portion 21 a of the intake control valve 21 narrows the bottom wall 17 d side of each intake passage 17, and one of the intake passages 17 is fully closed by the switching valve 26. As a result, the intake air is concentrated on the intake passage 17 side without the other switching valve, and
7 flows along the top wall section C divided by the rectifying member 30 and flows into the cylinder only from the intake valve opening 4c of the intake passage 17 on the other side. As a result, even when the intake air amount is small, the flow has directionality, and the flow obliquely flows along the cylinder inner surface when viewed in the cylinder axis direction and flows vertically along the cylinder axis when viewed in the cam axis direction. Tumble occurs (see the mark → in FIG. 1).

In a medium speed / medium load operation range where the required intake air amount is medium, the intake control valve 21 rotates to the fully open position and the intake passage 1
7, the switching valve 26 is kept in a state in which one intake passage 17 is closed. Therefore, the intake air is concentrated in the other intake passage 17 and flows over the entire top wall and bottom wall passages C and D of the passage 17 while being rectified,
Flow into the cylinder. It should be noted that the intake control valve 21 may be positioned halfway open depending on the required intake air amount.

In a high-speed / high-load operation range where the required intake air amount is large, the intake control valve 21 is held at the fully open position, and the switching valve 26 opens one intake passage 17 fully. Therefore, the intake air flows into the cylinder through both intake passages 17 and 17 and from both intake valve openings 4c and 4c.

As described above, in this embodiment, the switching valve 26 is provided for closing the one intake passage 17 and allowing the intake air to flow in a concentrated manner to the other passage 17 side.
7 is provided with an intake control valve 21 that is biased to the side of the top wall 17f, and furthermore, the intake passage 17 is provided with a top wall side portion C and a bottom wall side portion D.
And a rectifying member 30 for rectifying the air to flow along the top wall, so that when the amount of intake air is small, the intake air flows from one intake valve opening along the cylinder inner surface and in the direction along the cylinder axis direction. Flow can be performed in a directional manner, and an oblique tumble that combines swirl and tumble can be generated. As a result, lean combustion can be stabilized, and the fuel efficiency can be improved.

In this embodiment, a part of the flow regulating member 30 is disposed closer to the spark plug than the valve stem, so that the top wall portion C of the intake passage 17 has a transversely elongated shape elongated in the cam axis direction. And the tumble is more easily generated in the combustion chamber. As a result, even when the intake air amount is small, the combustion can be further stabilized, and the fuel efficiency in an operation range such as a low to middle speed range can be further improved.

In the above embodiment, the upright wall portions 41 and 42 of the rectifying member 30 are arranged so as to be deviated by the amount of deviation e. However, the present invention is not limited to this. May be arranged so as to face the wall. In this case, the small area portion 45 becomes closer to the bow shape.

In the above embodiment, the upstream end of the flow regulating member 30 is configured to contact the upper end of the intake control valve 21.
As shown in FIG. 6, the rectifying member may be formed substantially parallel to the inner surface of the ceiling wall, and may be provided with an interval a between the rectifying member and the control valve. In this case, it is desirable to extend the upstream end to the upstream edge of the control valve 21. In this way, the flow of intake air when the control valve 21 is partially opened is smooth.

In the above embodiment, a switching valve for opening or closing any of the intake passages is provided. However, the present invention does not necessarily require this switching valve. it can. Further, in the above embodiment,
The case where the present invention is applied to a motorcycle engine has been described as an example. However, the present invention can of course be applied to an automobile engine.

FIGS. 7 to 9 are views for explaining a second embodiment of the present invention in which a tumble can be generated more effectively. In the second embodiment, by improving the shape of the intake valve in the first embodiment,
FIG. 7 is a schematic diagram showing the flow of intake air near the intake valve opening, and FIG. 8 is a schematic diagram showing the flow of intake air in the vicinity of the intake valve opening. FIG. 9 is a schematic diagram showing the flow, and FIG. 9 is a schematic diagram for explaining the problems of the conventional example.

In the first embodiment, by providing the intake control valve 21 and the rectifying member 30, the intake air is deflected toward the ceiling wall and flows into the combustion chamber from the center of the cylinder, thereby generating a tumble. However, in this case, as shown in FIG. 9, a small vortex is generated in the portion (a) in the combustion chamber, and there is a concern that the tumble flow in the combustion chamber is attenuated by the small vortex. This is, for example, as shown in FIGS.
It is considered that this is because intake air flows in the cylinder axial direction due to its inertia, the pressure in the combustion chamber (a) becomes low, and the intake is reversed because the vicinity of the intake valve opening is bent in the cylinder axial direction.

Therefore, in the second embodiment, the small vortex is eliminated by flowing the gas along the top wall surface 4b 'of the recessed portion 4b of the combustion chamber and the surface of the cylinder bore 3a where the intake air can be taken, so that the tumble is generated more effectively. Therefore, as shown in FIG. 7, the umbrella surface 1 of the valve head 11a of the intake valve 11
1a 'and the top wall 4b' are combined with the umbrella surface 11a '
1c is approximated to an angle θ2 between the valve axis L1 and the cylinder axis L2.
The angle θ between a ′ and the top wall 4b ′ of the combustion chamber is configured to be as large as possible (for example, 20 degrees).

According to the structure of the second embodiment, FIG.
As shown in (a) and (b), when the valve head 11a opens the intake valve opening 4c, the intake air flows toward the top wall side of the intake passage 17 into the combustion chamber, and the valve head 11a opens.
It is bent along the ceiling wall surface 4b 'by the umbrella surface 11a' of FIG. In this way, the intake air flows from the top wall surface 4b 'to the inside of the combustion chamber along the surface of the cylinder bore 3a, as shown by the arrow in FIG. 8, and the generation of the small vortex can be avoided. As a result, compared to the first embodiment, the tumble can be generated more effectively, the combustion at the lean air-fuel ratio can be more stabilized, and the fuel efficiency in the low-medium-speed / low-load operation range can be reduced. It can be improved more than the first embodiment. The second embodiment is particularly effective in an overscare type engine having a cylinder bore diameter larger than a piston stroke.

FIG. 10 is a view showing a third embodiment in which the operation range can be expanded by closing the intake control valve 21.

In the case where the intake control valve is provided, if the intake passage area in the state where the intake control valve is closed is set to be large, the range in which the intake control valve can be operated with the intake control valve closed can be expanded.
However, simply increasing the area of the intake passage at the time of closing described above decreases the flow velocity of the intake air at the time of the low intake air amount, so that the required tumble strength in the combustion chamber cannot be obtained, and it is difficult to obtain the effect of improving the combustion. On the other hand, if the closed area is reduced in order to obtain tumble strength, the range in which the control valve can be operated with the valve closed is reduced.

Therefore, in the third embodiment, the following configuration is employed to obtain the required tumble strength in the combustion chamber while increasing the closed area. In the figure, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts. In the first embodiment, as shown in FIGS. 1 and 2, the intake passage 17 is curved in the cylinder axial direction on the downstream side of the intake control valve 21. Therefore, the intake air flowing to the top wall side of the intake passage 17 has its curved direction changed in the cylinder axial direction at the curved portion, and further changed in the umbrella surface direction by the valve head 11a.

On the other hand, in the third embodiment, FIG.
As shown in (2), the intake passage 17 is formed almost linearly to the vicinity of the opening of the intake valve. That is, as described above, the first
The intake passage 17 of the embodiment has a portion that is bent in the cylinder axis direction and extends in the cylinder axis direction on the downstream side of the intake control valve. However, in this embodiment, this extension portion is eliminated.

Further, in this embodiment, the intake control valve 21 is disposed in a straight portion of the intake passage 17, so that the valve portion 21a has a linear shape while bringing the intake control valve 21 close to the intake valve opening 4c. Is formed flat so as to conform to the bottom wall 17d. Incidentally, in the first embodiment, since the intake control valve is disposed at the bent portion of the intake passage, the valve portion is formed into a curved surface in conformity with the curved bottom wall. In addition, 18
'Is a throttle body and 19a' is a throttle valve. Reference numeral 19 'denotes a fuel injection valve, which passes through the linear intake passage and straightens the member 30 and the intake control valve 21.
Is oriented.

In the second embodiment, the flow direction of the intake air passing through the intake control valve 21 is changed to the above-described extended portion and the valve head 1.
It flows into the combustion chamber without being deflected by 1a.

As described above, in the third embodiment, since there is no curved portion in the intake passage, when the intake air flows into the combustion chamber, the flow direction of the intake control valve 21 and the rectifying member 30 is substantially maintained while maintaining the flow direction. Umbrella surface 1
As the resistance due to 1a is small, the intake flow velocity is slightly attenuated. As a result, it is possible to reduce the required amount of speed increase of the intake air by the intake control valve 21. As a result, it is possible to set a relatively large passage area when the intake control valve is closed. Operating range can be expanded.

If the amount of attenuation of the intake air velocity is reduced by forming the intake passage in a straight line as in the third embodiment, the rectifying member 30 can be eliminated. That is, since the intake passage is formed linearly and the intake control valve is disposed at the linear portion of the intake passage and immediately near the opening of the intake valve, a sufficient tumble speed can be ensured while eliminating the rectifying member 30.

[0038]

As described above, according to the intake control system for an engine according to the present invention, the intake control valve for narrowing the bottom wall portion of the intake passage at the time of the low intake air amount is provided, and the intake air flows along the top wall. A rectifying member is provided to rectify the air flow so that even when the amount of intake air is small, it is possible to give a vertical direction to the intake air flow, and as a result, it is possible to reliably generate tumble and stabilize lean combustion, This has the effect of improving fuel economy.

Also, since the portion near the intake valve opening of the rectifying member is located closer to the center of the combustion chamber than the valve stem of the intake valve, the top wall section of the downstream portion of the intake passage can be made oblong. As a result, tumble is more easily generated in the combustion chamber. As a result, even when the amount of intake air is small, combustion can be more stabilized, and there is an effect that the fuel efficiency in an operation range such as a low to middle speed range can be further improved.

[Brief description of the drawings]

FIG. 1 is a sectional side view of an engine to which an intake control device according to a first embodiment of the present invention is applied.

FIG. 2 is an enlarged view of an intake control valve and a flow regulating member of the first embodiment.

FIG. 3 is an overall perspective view of the rectifying member of the first embodiment.

FIG. 4 is a sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is a sectional view taken along line VV of FIG. 1 or FIG. 2;

FIG. 6 is an enlarged view showing a modification of the rectifying member in the first embodiment.

FIG. 7 is a schematic view of the vicinity of a valve head according to a second embodiment of the present invention.

FIG. 8 is a schematic diagram showing a flow of intake air in a combustion chamber of the second embodiment.

FIG. 9 is a schematic diagram showing a conventional flow of intake air for explaining a problem in the second embodiment.

FIG. 10 is a sectional side view showing a third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 engine 3 cylinder block 4 cylinder head 4b combustion recess 5 head cover 11 intake valve 11b valve stem 17 intake passage 17d bottom wall 17f top wall 21 intake control valve 30 rectifying member

Claims (1)

(57) [Claims] 1. An intake control valve, in which the intake air is biased toward the top wall of the intake passage by narrowing the bottom wall portion of the intake passage into the bottom wall of the intake passage when the amount of intake air is low. A rectifying member that rectifies the intake air at least in a portion of the intake passage downstream of the intake control valve along the ceiling wall side of the intake passage, and at least near the intake valve opening of the rectifying member. An intake control device for an engine, wherein the portion is located closer to the center of the combustion chamber than the valve stem of the intake valve.