JPH0555691B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an intake port device used in a three-valve or four-valve type internal combustion engine, and particularly to a variable intake swirl type intake port device.

BACKGROUND ART One of the variable intake swirl type intake port devices used in internal combustion engines includes a straight port and a helical port, each of which is opened and closed by an intake valve, and an intake control valve provided in the middle of the straight port. An intake port device configured to communicate and cut off the straight port is already known.
It is shown in Publication No. 48715.

In the above-mentioned intake port device, when the intake control valve is closed, the straight port is blocked and substantially all of the intake air flows through the helical port and into the combustion chamber, creating a strong intake swirl. As a result, the lean air-fuel ratio limit of the combustible mixture is expanded, and when the intake control valve is open, the straight port is open, and the intake air flows through the straight port in addition to the helical port and flows into the combustion chamber. As a result, air intake is performed with high filling efficiency.

Problems to be Solved by the Invention When the intake control valve is closed and the straight port is blocked, the intake air drawn into the combustion chamber from the helical port creates a swirl flow that swirls around the cylinder bore axis of the combustion chamber. This intake flow has the effect of increasing the apparent flame propagation velocity and expanding the lean air-fuel ratio limit of the combustible mixture.However, if a swirl flow occurs in the combustion chamber, the centrifugal action causes the fuel to flow into the combustion chamber. The mixture is pushed toward the outer circumference, creating a gradient in the air-fuel ratio in the radial direction of the combustion chamber, and the air-fuel mixture in the center of the combustion chamber is leaner than in the outer circumference. If the average air-fuel ratio of the air-fuel ratio is close to the lean air-fuel ratio limit, a flammable mixture within the lean air-fuel ratio limit cannot be obtained in the center of the combustion chamber. If the spark plug is located in the area, a mixture with a combustible air-fuel ratio cannot be obtained in the vicinity of the spark plug, and there is a risk of ignition failure. For this reason, conventionally, even if a good intake air swirl is obtained within the combustion chamber, the lean air-fuel ratio limit of the combustible mixture cannot be expanded effectively enough.

SUMMARY OF THE INVENTION An object of the present invention is to provide an improved intake port device that solves the above-mentioned problems.

Means for Solving the Problems According to the present invention, the above-mentioned object is to provide a straight port and a helical port that are respectively opened and closed by intake valves, and a device that is provided in the middle of the straight port to allow communication and isolation of the straight port. In an intake port device for an internal combustion engine having an intake control valve that performs This is accomplished by an intake port arrangement having an auxiliary straight passageway open towards the installation.

The auxiliary straight passage as described above may have a passage cross-sectional area smaller than that of either the straight port or the helical port, and if the spark plug is provided in the central region of the combustion chamber, the auxiliary straight passage The straight passage may open in a direction that radially crosses a central portion of the combustion chamber toward the ignition plug installation portion.

Effects and Effects of the Invention According to the above-described configuration, the intake air drawn into the combustion chamber through the auxiliary straight passage causes a straight flow within the combustion chamber that traverses the combustion chamber in the radial direction and heads toward the installation part for the spark plug. As a result, when the intake control valve is closed, the fuel that was pushed toward the outer circumference of the combustion chamber due to the swirl flow of the intake air (air mixture) generated in the combustion chamber moves toward the ignition plug installation position. The fuel-containing air-fuel mixture also flows directly from the auxiliary straight passage to the spark plug installation position, and even if the average air-fuel ratio of the air-fuel mixture taken into the combustion chamber is set to a lean air-fuel ratio, the spark plug installation position is prevented. A combustible air-fuel mixture with an appropriate air-fuel ratio is stably present in the position region, and the lean air-fuel ratio limit of the combustible air-fuel mixture is further expanded. In addition, a large amount of microturbulence is generated in the combustion chamber due to the collision between the straight flow of intake air drawn into the combustion chamber through the auxiliary straight passage and the swirl flow, which improves the combustibility of the air-fuel mixture. This also further expands the lean air-fuel ratio limit of the combustible mixture.

When the intake control valve is open, intake air is drawn into the combustion chamber from the auxiliary straight passage in addition to the straight port and helical port, improving engine output by improving filling efficiency. When the intake control valve is open, the swirl flow of intake air flowing into the combustion chamber from the helical port and the straight flow of intake air flowing into the combustion chamber from the straight port and auxiliary straight passage collide with each other, causing A large amount of microturbulence is generated, and the air-fuel ratio of the air-fuel mixture is made uniform, resulting in rapid combustion.

Further, according to the above-described configuration, even if the ignition plug is provided in the central region of the combustion chamber, there will be no problem in ignitability of the air-fuel mixture, and the ignition plug is provided in a position biased to one side of the combustion chamber. The flame propagation distance of the air-fuel mixture in the combustion chamber is shorter than that in the combustion chamber, enabling so-called compact combustion, which expands the lean air-fuel ratio limit of the combustible air-fuel mixture and improves the mechanical octane number. It will be done.

EXAMPLES The present invention will now be described in detail by way of examples with reference to the accompanying drawings.

1 and 2 show one embodiment of an intake port device for an internal combustion engine according to the present invention. In the figure, 1 indicates a cylinder block and 2 indicates a cylinder head, and the cylinder block 1 and cylinder head 2 cooperate with a piston 4 provided in a cylinder bore 3 to define a combustion chamber 5. are doing.

The cylinder head 2 is provided with a straight port 6 and a helical port 7, and is further provided with two exhaust ports 8. The straight port 6 and the helical port 7 are configured such that their open ends facing the combustion chamber 5 are opened and closed by individual intake valves 9 and 10, respectively, and the exhaust port 8 is opened and closed toward the combustion chamber 5 by individual exhaust valves 11, respectively. The open end can be opened and closed.

The cylinder head 2 is provided with a spark plug hole 12 that opens toward the central region of the combustion chamber 5, and the spark plug hole has a spark plug 13.
is installed.

An intake control valve 14 is attached to the cylinder head 2. The intake control valve 14 is a butterfly valve type opening/closing valve, and opens and closes the straight port 6 midway to control communication and isolation of the straight port 6. Although not shown in the figure, the intake control valve 14 may be closed by an appropriate control device, for example, when the engine load is below a predetermined value, and may be opened when the engine load is above a predetermined value. .

The cylinder head 2 extends from its intake side end face, bypassing the intake control valve 14, and is directed toward the installation part of the spark plug 13 in the combustion chamber 5 near the opening end of the straight port 6 to the combustion chamber 5. An auxiliary straight passage 15 is provided which is open. That is, the auxiliary straight passage 15 has an intake inlet 16 opened at the intake side end surface of the cylinder head at one end.
The other end has an intake outlet 17 that opens near the opening end of the straight port 6 to the combustion chamber 5, and is located below the straight port 6 and slopes downward from the intake inlet 16 toward the intake outlet 17. There is.

The passage cross-sectional area of the auxiliary straight passage 15 is smaller than the passage cross-sectional area of either the straight port 6 or the helical port 7, and is set to about 1/5 of these. Intake outlet 17 of auxiliary straight passage 15
As clearly shown in FIG. 2, is provided on the side of the helical port 7 which is provided adjacent to one side of the straight port 6 in the vicinity of the opening end of the straight port 6 with respect to the combustion chamber 5. There is. The intake inlet 16 of the auxiliary straight passage 15 communicates via a lower pocket 19 with a manifold intake passage 20 of an intake manifold 18 provided on the intake side end face of the cylinder head 2 and connected to the straight port 6 and the helical port 7. Intake air is supplied from this.

According to the configuration described above, when the intake control valve 14 is closed and the straight port 6 is blocked, most of the intake air flows into the combustion chamber 5 through the helical port 7, causing a swirl around the cylinder bore center axis. Produces flow A. At the same time, a portion of the intake air flows into the combustion chamber 5 through the auxiliary straight passage 15, creating a straight flow B that radially crosses approximately the center of the combustion chamber 5 toward the spark plug 13. As a result, the swirl flow A is drawn into the straight flow B and heads toward the center of the combustion chamber 5, and due to the centrifugal action of the swirl flow A, the fuel that was mostly present in the outer peripheral area of the combustion chamber 5 is transferred to the area where the spark plug 13 is disposed. In addition, the straight flow B itself contains fuel, and this flows directly to the arranging part of the ignition plug 13, so that the air-fuel mixture existing around the ignition plug 13 is compared to the air-fuel mixture existing at the outer periphery of the combustion chamber 5. This will prevent it from becoming extremely thin. As a result, even if the average air-fuel ratio of the air-fuel mixture supplied into the combustion chamber 5 is a lean air-fuel ratio, a combustible air-fuel mixture with an appropriate air-fuel ratio is stably present near the spark plug 13, and the mixture The ignition of the air becomes reliable, and a large amount of microturbulence is generated in the combustion chamber 5 due to the collision between the swirl flow A and the straight flow B, which causes the combustible mixture to become diluted. Air-fuel ratio limits are expanded. In addition, the straight flow B reaches the end of the swirl flow A.
Since the straight flow B collides with the swirl flow A, the straight flow B does not greatly attenuate the swirl flow A.

When the intake control valve 14 is open, intake air flows into the combustion chamber 5 from the straight port 6 in addition to the helical port 7, which improves the charging efficiency. By flowing into the combustion chamber 5 through the auxiliary straight passage 15, the charging efficiency is further improved.

In addition, the fuel adhering to the wall flowing along the bottom of the manifold intake passage 20 passes through the downwardly sloped auxiliary straight passage 15 from the lower pocket part 19, and immediately goes to the vicinity of the opening end of the straight port 6 to the combustion chamber 5, whereupon the fuel is supplied to the combustion chamber 5. Responsiveness is also improved.

3 and 4 show another embodiment of the intake port device for an internal combustion engine according to the present invention.
In FIGS. 3 and 4, parts corresponding to those in FIGS. 1 and 2 are designated by the same reference numerals as in FIGS. 1 and 2.

In such an embodiment, the auxiliary straight passage 1
The intake inlet 16 of No. 5 is provided at the bottom of the intake port inlet.

In this embodiment as well, a portion of the intake air flows into the combustion chamber 5 through the auxiliary straight passage 15, so that a straight flow B radially crosses approximately the center of the combustion chamber 5 and heads towards the spark plug 13. occurs, and the same effects as in the embodiment described above can be obtained.

Further, when a fuel injector 21 is provided in the intake manifold 18 and fuel is injected from the fuel injector toward the intake port, some of the fuel injected from the fuel injector 21 toward the intake port may be directed toward the straight port 6. Even if the intake control valve 14 is closed at this time, the fuel flows into the combustion chamber 5 through the auxiliary straight passage 15,
This also expands the lean air-fuel ratio limit of the combustible mixture when the intake control valve 14 is closed.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited to these, and it is understood that various embodiments can be made within the scope of the present invention. It will be clear to those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of an intake port device for an internal combustion engine according to the present invention, and FIG.
FIG. 3 is a longitudinal sectional view showing another embodiment of the intake port device for an internal combustion engine according to the present invention; FIG.
3 is a plan cross-sectional view of the intake port device according to the invention shown in FIG. 3; FIG. 1...Cylinder block, 2...Cylinder head,
3...Cylinder bore, 4...Piston, 5...Combustion chamber,
6...Straight port, 7...Helical port, 8
...Exhaust port, 9,10...Intake valve, 11...Exhaust valve, 12...Spark plug hole, 13...Spark plug, 14...Intake control valve, 15...Auxiliary straight passage, 16...Intake inlet, 17...Intake outlet, 18 ...Intake manifold, 19...Lower pocket part, 20...
Manifold intake passage, 21...Fuel injector.

Claims (1)

[Scope of Claims] 1. An intake port for an internal combustion engine having a straight port and a helical port each opened and closed by an intake valve, and an intake control valve provided in the middle of the straight port to connect and cut off communication between the straight ports. The device includes an auxiliary straight passage that extends by bypassing the intake control valve and opens toward a portion where a spark plug is disposed in the combustion chamber near an opening end of the straight port with respect to the combustion chamber. Intake port device. 2. The intake port device according to claim 1, wherein the auxiliary straight passage has a passage cross-sectional area smaller than the passage cross-sectional area of either the straight port or the helical port. Port device. 3. In the intake port device according to claim 1, the spark plug is provided in a central region of the combustion chamber, and the auxiliary straight passage extends toward the center of the combustion chamber toward the installation portion of the spark plug. An intake port device characterized in that the opening is opened in a direction transverse to the radial direction.