JP3318358B2 - 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 a vertical vortex (tumble) is generated in a combustion chamber by variably controlling an intake passage area, and more particularly, to a flow for canceling the tumble. The present invention relates to an improvement in a shape and a rotation direction of an intake control valve that can be suppressed.

[0002]

2. Description of the Related Art In order to improve the fuel efficiency of an engine, it is effective to stabilize lean combustion by increasing the flow rate of intake air even in an operation region where the amount of intake air is small to generate, for example, tumble in a combustion chamber. It is known that there is. As an intake control device capable of generating such a tumble, the present applicant arranges an intake control valve rotatably in the bottom wall of the intake passage, and narrows the bottom wall side portion of the intake passage when the amount of intake air is low. Thus, there has been proposed an intake control device in which intake air is caused to flow toward the ceiling wall side so as to flow vertically from the center side of the combustion chamber (for example, Japanese Patent Application No. Hei.
No. 111182).

[0003]

By the way, the intake control device according to the above proposal narrows the intake passage area when the amount of intake air is low, thereby generating a tumble flowing vertically from the center of the combustion chamber, thereby making lean. It stabilizes combustion. However, due to subsequent experimental research,
It has been found that an airflow in the direction of canceling the tumble (hereinafter referred to as a reverse swirl flow; a flow in a direction in which the tumble is generated is sometimes referred to as a forward swirl flow) is generated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an intake control device for an engine capable of suppressing a reverse swirling flow as much as possible and generating a tumble more reliably.

[0005]

As a result of experimental studies, the present inventors have found that the above-described reverse swirl flow occurs only when the intake valve is at a low lift and the intake control valve is within a predetermined opening range. I found to do.

FIGS. 2 to 4 are diagrams for explaining the method and the results of the above-mentioned experiments. In the drawings, reference numeral 17 denotes an intake passage;
Is an intake valve that opens and closes an intake valve opening, 21 is an intake control valve that controls the passage area of the intake passage 17, and 20 is a partition that defines the intake passage 17 downstream of the intake control valve into a top wall passage and a bottom wall passage. It is a board. The intake control valve 21 is formed by recessing a valve portion 21 a in a round bar so as to match the shape of the bottom wall side portion of the intake passage 17.

The tumble ratio in FIGS. 2 and 3 is
When the lift amount of the intake valve 11 is fixed to an intermediate opening degree of about 30% of the maximum lift amount, the number of turns of the vertical flow per one rotation of the crankshaft. -Indicates the number of turns in the opposite direction as a whole. In FIG. 4, the horizontal axis represents the opening of the intake control valve, and the vertical axis represents the tumble ratio. Curves C1 and C2 represent the intake control valve opening and the tumble ratio when the intake valve lift is fixed at a maximum of 2 mm, respectively. 6 is a characteristic curve showing the relationship.

In this experiment, the intake valve 11 was fixed at the maximum lift or the intermediate lift, and the reverse swirling flow was generated while the intake control valve 21 was rotated 360 degrees from full open (0 degrees).
The state of generation of a forward swirling flow was measured. In this case, the rotation direction is set to a direction in which the outer peripheral surface of the valve portion 21a starts to protrude into the passage from the upstream side of the intake passage (forward direction).

As is apparent from FIGS. 2 to 4, when the intake valve lift amount is the maximum, a swirling flow (tumble) is generally directed forward regardless of the opening degree of the intake control valve.
In the case of an intermediate lift, the swirling flow is in the opposite direction as a whole when the opening degree of the intake control valve is within a certain range.

This is considered to be due to the following reasons. That is, in principle, the flow from the bottom wall side portion (indicated by a in FIG. 2A) of the intake passage is a reverse swirling flow, and the flow from the top wall side portion (b) is a forward swirling flow. Cancel each other out, and as a whole, a reverse or forward swirling flow is generated. In this case, while the intake valve lift is small, the flow from the bottom wall side portion is strong, so that the flow becomes a reverse swirling flow as a whole depending on the opening degree of the intake control valve. On the other hand, as the intake valve lift increases, the flow from the bottom wall side portion decreases, and the flow becomes a forward swirling flow as a whole.

In the case of the above-mentioned halfway lift, a reverse swirling flow is generated until the intake control valve angle reaches 70 degrees from 0 degrees (fully open position) (see FIGS. Around 160 degrees) and finally from 320 degrees to 3 degrees.
It occurs up to 60 degrees (0 degrees).

Therefore, the reverse swirling flow is generated from the fully opened position to 70 degrees when the intake control valve is rotated in the forward direction, that is, in the range of 70 degrees, whereas the outer peripheral surface of the valve portion 21a is located on the downstream side. It can be seen that the rotation occurs only in the range of 320 degrees from the fully opened position, that is, in the range of 40 degrees when the rotation is made in the direction (reverse direction) protruding from.

Accordingly, the present invention provides an intake control valve for controlling the cross-sectional area of the intake passage at the bent portion of the bottom wall of the intake passage, which is bent in an arc shape from the intake valve opening to the cylinder wall side and then extends substantially linearly. The intake control valve is formed by recessing a valve portion in a cylindrical body along a bottom wall side inner surface of the intake passage and along a circular arc shape of the bent portion. A fully open position in which the control valve does not narrow the passage area by making the valve portion substantially flush with the inner surface on the bottom wall side,
When the valve portion protrudes into the intake passage in the upright state and is rotatable between a fully closed position where the passage area is reduced, and the intake control valve is closed from the fully open position to the fully closed position. An intake control device for an engine, wherein a rotation direction is set such that an outer peripheral surface of the valve portion protrudes from the downstream side and only from a bottom wall of the intake passage into the intake passage.

[0014]

According to the intake control apparatus for an engine of the present invention, when the intake air amount is low, the intake control valve pivots to the closed side to narrow the intake passage area. , Which causes a tumble to be generated and stabilizes lean combustion.

In the present invention, since the rotation direction of the intake control valve is set to the reverse direction, the angle range of the intake control valve in which the reverse swirling flow occurs is rotated in the forward direction. As a result, the width becomes narrower, and tumble is generated more reliably.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a diagram for explaining an intake control device for an engine according to one embodiment of the present invention. In the figure, 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 and fastened with head bolts. 5 is attached.

A combustion recess 4b constituting a combustion chamber is formed on the cylinder block side mating surface 4a of the cylinder head 4. The combustion recess 4b has two intake valve openings 4c and two exhaust valve openings 4d. An exhaust valve 10 is arranged at each exhaust valve opening 4d, and an intake valve 11 is arranged at each intake valve opening 4c so that each opening can be opened and closed. Exhaust and intake lifters 12 and 13 are mounted on the upper ends of the exhaust and intake valves 10 and 11, respectively. Are arranged in a direction perpendicular to the cylinder axis and parallel to each other.

The two exhaust valve openings 4d are led out to the front wall 4f side of the cylinder head 4 through a forked exhaust passage 16, and the intake valve openings 4c are connected to the forked intake passage 1.
At 7, it is led to the rear wall 4 g side of the cylinder head 4.
When viewed in the camshaft direction, the intake passage 17 is bent in an arc shape from the intake valve opening 4c toward the cylinder rear wall 4g.
It extends substantially linearly.

A common cab joint 18 is connected to each wall opening 17a of each intake passage 17, and merges into one passage in the joint 18. One carburetor 19 is connected to the 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.

A switching valve 26 is provided in the cab joint 18. The switching valve 26 has a valve shaft 26 disposed so as to penetrate the joint 18 in the cam shaft direction.
a and the one intake passage 17 fixed to the valve shaft 26a.
And a valve plate 26b for opening and closing the valve.

A circular valve hole 17c is formed in the bent portion 17b of each of the intake passages 17 near the intake valve opening so as to penetrate in the cam axis direction. The axis of the valve hole 17c is
7 is located near the surface of the bottom wall, and therefore, the inside of each intake passage 17 of the valve hole 17c has a substantially semicircular shape.

An intake control valve 21 for changing the cross-sectional area of the intake passage 17 is rotatably inserted into the valve hole 17c. The intake control valve 21 is formed by recessing a round bar with a valve portion 21a that forms a continuous surface with the lower inner surface of each intake passage 17. Also, this intake control valve 21
The fully open position where the valve portion 21a is immersed in the valve hole 17c and is flush with the inner surface of the intake passage, and the valve portion 21a stands almost perpendicularly from the bottom wall surface to narrow the intake passage 17 to approximately 1/2. It can rotate between the closed position.

A partition plate 20 is disposed downstream of the intake control valve 21 in the intake passage on which the switching valve 26 is not disposed. The partition plate 20 extends to the vicinity of the intake valve opening 4c along a substantially center line of the intake passage 17, and has substantially the same width as the intake passage 17. Thus, the partition plate 20 defines the intake passage 17 downstream of the intake control valve into a top wall side passage and a bottom wall side passage. Also, a small gap is provided between the upstream end of the partition plate 20 and the outer peripheral edge of the intake control valve 21 so as not to interfere even if the intake control valve 21 rotates 360 degrees. .

An end of the intake control valve 21 protrudes outward from the intake passage, and a control pulley 22a is fixed to the protruding end. The control pulley 22a is a driving pulley 22b fixed to a control motor. Connected to the cable. A switching pulley 26c is provided at the outer end of the switching valve 26.
Is fixed. The switching pulley 26c is connected by a cable to a driving pulley 26d fixed to the switching motor.

The control motor and the switching motor are controlled by the ECU 23
Controls its rotation. The ECU 23 is provided with a throttle valve 19a based on a throttle opening sensor 24.
Is input, and the engine speed signal b from the rotation sensor 25 is input.
The control motor outputs a control signal A to the control motor to rotate to the fully closed position as the amount of intake air is smaller as in a low load operation range and to the fully open position as the amount of intake air is larger as in a high speed / high load operation range. I do. In this case, the rotation direction of the intake control valve 21 is the valve portion 2 of the intake control valve 21 in the closing direction operation.
The opening side operation is set clockwise so that the downstream portion of 1a starts to protrude into the intake passage (counterclockwise in the figure).

The ECU 23 is provided with the switching valve 26
A control signal B is output to the switching motor to be closed in an operation range in which the intake air intake amount is equal to or less than a predetermined value, and open in an operation range in which the intake air amount exceeds the predetermined amount.

Next, the operation and effect of this embodiment will be described. In the present embodiment, the control signal A from the ECU 23 is used.
The control motor controls the opening and closing of the intake control valve 21 by the control motor, and the switching motor controls the switching valve 26 to open and close by the control signal B from the ECU 23. Here, the closing operation of the intake control valve 21 is performed so that the outer peripheral portion of the valve portion 21a projects upward from the downstream side, that is, counterclockwise in FIG. 1, and the opening operation is performed clockwise.

First, at the time of a high intake air amount such as a high speed and a high load, the switching valve 26 opens one intake passage 17, and the intake control valve 21 has its valve portion as shown by a solid line in FIG. Reference numeral 21a is located at a fully open position where it is immersed in the bottom wall of each intake passage 17.

When the amount of intake air is low, such as at low speed and low load, the control motor rotates the intake control valve 21 counterclockwise to the fully closed position as shown by a two-dot chain line in FIG. As a result, the valve portion 21a
Narrow down the bottom wall side. Also, a control signal B from the ECU 23
This causes the switching motor to rotate the switching valve 26 to the fully closed position shown by the two-dot chain line in FIG. Thereby, the intake air is concentrated on the other intake passage 17 side, and the partition plate 20 of the passage 17
And flows into the cylinder from the intake valve opening 4c of the intake passage 17 on the other side into the cylinder. As a result, even when the amount of intake air is small, the flow is given directionality, and flows obliquely 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.

When the high intake air amount state is reached again, the intake control valve 21 rotates clockwise to the fully opened position in FIG. 1, and the switching valve 26 opens one of the intake passages 17 fully. As a result, the intake air flows uniformly over the entire cross section of both intake passages 17.

As described above, in the present embodiment, the switching valve 26 is provided for closing the one intake passage 17 so as to concentrate the intake air toward the other passage 17, and the top wall of the other intake passage 17 is provided for the intake valve 17. The intake control valve 21 is provided so as to be deviated to the side, and the partition plate 20 for dividing the intake passage 17 into a top wall side portion C and a bottom wall side portion D is provided. It is possible to flow directionally from one intake valve opening along the cylinder inner surface and along the cylinder axis direction, and it is possible to generate an oblique tumble that combines swirl and tumble. As a result, lean combustion can be stabilized, and the fuel efficiency can be improved.

In the present embodiment, the closing operation of the intake control valve 21 is set in the counterclockwise direction (reverse direction) in FIG. 1 and the closing operation is set in the clockwise direction (forward direction). Therefore, the opening range of the intake control valve in which the reverse swirling flow occurs is narrowed, and tumble can be generated more reliably. That is, in the device according to the above-described proposal, the closing operation is clockwise, and the opening operation is counterclockwise. In this embodiment, the range in which the reverse swirling flow occurs can be greatly reduced to 40 degrees from the fully open position.

FIG. 5 is a view for explaining a second embodiment of the present invention, in which the same reference numerals as those in FIGS. 1 to 3 indicate the same or corresponding parts. In the present embodiment, the axis P of the intake control valve 21
Is located near the center between the center line of the intake passage and the bottom wall surface, and the notch of the valve portion 21a is made deeper than in the first embodiment to reduce the bottom thickness of the valve portion 21a. The bending R of the upstream end portion 20a of the partition plate 20 is made substantially the same as the radius of rotation of the valve portion 21a, and a slight gap that does not interfere with the rotation of the valve portion 21a is provided.

In the second embodiment, similarly to the first embodiment, the range of the intake control valve opening in which the reverse swirl flow occurs can be reduced, and the following effects can be obtained. Since the axis P of the intake control valve is located above the bottom surface of the intake passage, the intake control valve 21
Diameter can be reduced. Therefore, the intake control valve 21 can be disposed closer to the intake valve opening 4c, and since the recess in the bottom wall of the intake passage due to the valve hole can be small, fuel accumulation can be suppressed, and the driving force required for the intake control valve can be reduced. Can be reduced.

Although the above embodiment has been described with reference to the case where the partition plate 20 is provided, the present invention can be applied even when the partition plate 20 is not provided. Even in this case, the intake control valve 21 is
By performing the closing operation so as to protrude into the intake passage from the downstream portion of 1a, the opening range of the intake control valve in which the reverse swirling flow occurs can be reduced, and the tumble can be reliably generated. The switching valve 26 is not always necessary, and when the switching valve 26 is not provided, the partition plate 20 may be provided in both the intake passages.

[0036]

As described above, according to the intake control apparatus for an engine of the present invention, the closing direction of the intake control valve is adjusted so that the valve portion projects from the downstream side into the intake passage (counterclockwise direction in the figure).
Therefore, the opening range of the intake control valve in which the reverse swirl flow occurs when the intake valve is at a low lift can be reduced, the tumble can be generated more reliably, and the fuel efficiency can be improved.

[Brief description of the drawings]

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

FIG. 2 is a sectional side view for explaining the operation of the first embodiment.

FIG. 3 is a diagram for explaining the operation of the first embodiment.

FIG. 4 is a characteristic diagram showing a relationship between an intake control valve opening and a tumble direction for explaining the operation of the first embodiment.

FIG. 5 is a sectional side view for explaining a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 engine 17 intake passage 17d bottom wall 21 intake control valve 21a valve section

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Claims (1)

(57) [Claims] 1. An arc shape from an intake valve opening to a cylinder wall side.
The above-mentioned bending of the bottom wall of the intake passage which extends substantially linearly after bending.
An intake control valve for controlling the cross-sectional area of the intake passage in the music portion arranged, the intake control valve, the arc shape of the shape along the bottom wall inner surface and the bent portion of the intake passage in the cylinder
The intake control valve is formed by recessing the intake control valve so that the valve portion is substantially flush with the inner surface on the bottom wall side so as not to reduce the passage area, The valve portion protrudes into the intake passage in an upright state and is rotatable between a fully closed position where the passage area is reduced, and the intake control valve is fully opened.
The direction of rotation when closing from the position to the fully closed position side should be such that the outer peripheral surface of the valve portion is only from the downstream side and within the bottom wall of the intake passage.
Intake control device for an engine is characterized in that set so as to protrude et intake passage.