JPH0481522A - Intake device of engine - Google Patents

Abstract

PURPOSE:To improve combustibility under a high engine speed by arranging respective side intake passages in their portions in the vicinity of an intake valve in a substantially vertical direction compared to that of a center intake passage, and providing a passage opening/closing valve which closes the passage under a low speed and low load condition of an engine on one of the side intake passage along which the center intake passage is laid. CONSTITUTION:A shutter valve 16 is opened under a condition of a low engine speed and a low load, a side intake port 12 is interrupted, and intake air is supplied to a combustion chamber 4 from a center intake port 14 and a side intake port 13, respectively. With high swirl generation effect due to the port 14, combustibility is improved at the time of low engine speed and low load. The valve 16 is closed under a high engine speed condition, the intake air is supplied to the combustion chamber through all of the ports 12, 13, 14. With high turnbull flow generation effect due to the side ports 12, 13, the swirl caused by the port 14 is obstructed to prevent combustion adhesion of the peripheral wall of the combustion chamber 4. Combustibility is improved under a high engine speed, HC is reduced and a fuel consumption ratio is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intake system for an engine having three intake valve holes for combustion.

[Prior Art and its Problems] Conventionally, it has been proposed that three intake valve holes are provided in the combustion chamber to increase the filling efficiency of the air-fuel mixture. (Refer to Japanese Unexamined Patent Publication No. 1985-192859, etc.) However, in such a three-valve engine, the flow rate of the mixture decreases, especially at low speeds and low loads, resulting in poor combustibility. The combustibility is improved by increasing the turbulence of the air-fuel mixture by forming a swirl.

However, in the conventional structure, the intake air flow path is as light even at high speeds (high speeds) as at low speeds, so a swirl flow is generated that is stronger at high speeds than at low speeds, and the centrifugal force of the swirl flow causes the fuel to flow. There was a problem in that unburned HC would adhere to the peripheral wall of the fuel chamber, increasing the amount of unburned HC and deteriorating fuel efficiency.

[Object of the Invention] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an intake system for an engine that can improve combustibility when the engine is running at high speed.

[Means for Solving the Problems] Therefore, the engine intake system according to the present invention communicates with the central intake valve hole along at least one of the side intake passages that communicate with the intake valve holes on both sides. A central intake passage is formed, and the vicinity of the intake valve hole of the central intake passage is oriented horizontally to generate a swirl flow, while the vicinity of the intake valve hole of each side intake passage is oriented to generate a turnbull flow. The intake passage is formed so as to be oriented perpendicularly to the central intake passage, and one side intake passage along which the central intake passage runs is provided with a passage opening/closing valve that closes the passage when the engine is at low speed and low load.

In addition to the above-mentioned 4i111&, a fuel injection valve is installed in the central intake passage so as to be oriented toward the spark plug.

As a result, when the engine is running at low speed and under low load, the passage opening/closing valve closes and intake air flows from the central intake passage and one side intake passage, thereby strengthening the Turnbull flow and attenuating the swirl flow caused by the central intake passage. It is possible to prevent fuel from adhering to the peripheral wall of the combustion chamber.

Furthermore, by directing the injection direction of the fuel injection valve toward the ignition direction, combustion can be performed approximately in the center of the combustion chamber, and this combustion can be spread to the surrounding area, thereby achieving better combustion.

Example of U invention Embodiments of the present invention will be described below based on the drawings.

In FIGS. 1 and 2 showing a first embodiment of the present invention, a combustion chamber 4 is formed by a cylinder block 1, a lower surface of a cylinder head 2, and a top surface of a piston that reciprocates up and down within the cylinder. ing.

The cylinder head 2 is formed with three intake valve holes 5, 6.7 and two exhaust valve holes 8.9 that open into the combustion chamber 4, and a spark plug 11 facing approximately the center of the combustion chamber 4.
A plug hole 10 is formed for attaching the plug.

The intake valve holes 5 and 6 on both sides communicate with site intake boats 12 and 13 as side intake passages in a substantially closed manner, and the center intake valve hole 7 has a central intake passage branching from one of the site intake boats 12. It communicates with the center intake boat 14 as well.

The center intake boat 14 is formed near the intake valve hole 7 or horizontally to easily generate a swirl flow as shown in the second figure. The fuel injection valve 15 is oriented in the direction
Or installed.

Both site intake boats 12.13 are Turnbull style (
The included angle between each other is small so that it is easy to generate vertical swirl flow).
As shown in the second figure, it is formed to be oriented horizontally from the center intake boat 14.

Furthermore, the site intake boat 12 includes a sensor intake boat 1.
A shutter valve 16 as a passage opening/closing valve is installed downstream of the branch point No. 4, and the shutter l*16 is controlled to close at low speeds and low loads, as shown in FIG. It has become.

In Figure 2, 17 is an intake valve, 18 is an exhaust valve, and 19 is an exhaust boat. In addition, the one-car site intake boats 12 and 13 are installed on the downstream side of the throttle side (not shown).

The intake device configured as described above operates as follows.

When the engine is at low speed and load, the shatter valve 16 is controlled to close and the site intake boat 12 is shut off. In this state, intake air is supplied into the combustion chamber 4 from the center intake boat 14 and the other site intake boat 13, respectively.

In this case, the swirl flow generation effect by the center intake boat 14 is large, resulting in good combustion performance at low engine speeds and low loads. In addition, since the fuel injection valve 15 injects fuel toward the spark plug 11 in the combustion chamber 4, combustion gradually spreads from the center of the combustion chamber 4 to the periphery, resulting in lean burn combustion. , combustibility can be further improved.

At high speed, since the shatter valve 16 is opened, intake air is supplied to the combustion chamber via all the intake boats 12, 13, and 14. In this condition, both site intake boats 12.1
3 is strengthened and inhibits the swirl flow caused by the center intake boat 14, the combustion chamber 4
This prevents fuel from adhering to the peripheral wall of the engine, improves combustion performance at high engine speeds, and reduces HC and improves fuel efficiency.

Furthermore, since the center intake boat 14 is branched from the site intake boat 12 and offset, space for installing the fuel injection valve 15 etc. can be easily secured.
It is possible to make effective use of space and create a compact intake system.

Next, a second embodiment is shown in FIGS. 4 to 6. Note that the same parts as in the first embodiment are given the same reference numerals, and the explanation thereof will be omitted.

In the figure, in this embodiment, two symmetrical center intake boats 21 and 22 curved in opposite directions are communicated with the center intake valve hole 7. Both center intake boats 21 and 22 are formed along the site intake boats 23 and 24 as shown in FIG. 5, and branch off upstream of the confluence of the site intake boats 2324.

In addition, one center intake boat 21 and the second intake boat 24 located on the opposite side of the harmful center intake port 21 have
A shutter valve 25, 26 having the characteristics shown in FIG. 3 similar to that of the first embodiment is interposed. Double shutter valve 2
5.26 are interlocked with each other and the valves are controlled to close when the engine speed is low and the load is low.

This configuration operates as follows.

At low engine speeds and low loads, both shutter valves 25.26
The valve is closed, and intake air is supplied from the intake boat 23 to the center intake boat 22 and the cylinder 1 into the combustion chamber 4. In this case, the swirl flow generation effect of the center intake boat 22 strengthens the turbulence of the air-fuel mixture, compensates for the decrease in the intake flow velocity, and improves the combustion performance at low engine speeds and low loads. When the engine is at high speed, both shutter valves 25, 26 are opened, and intake air is supplied to the combustion chamber from all ports 21, 22, 23, 24. In this case, the center intake boats 21 and 22 are in conflict with each other.
In addition, the generation of swirl flow is canceled out, and the turnbull flow generation effect by the intake boats 23 and 24 on both sites is strengthened, which prevents fuel from adhering to the combustion chamber wall when the engine is running at high speed, thereby reducing HC. This reduces fuel consumption and improves fuel efficiency.

Furthermore, in the second embodiment, by controlling the shatter valve narrowly according to the engine operating conditions, complex control of the mixture formation in the combustion chamber 4 is possible, which further improves combustibility. It becomes possible.

[Effects of the Invention] As described above, according to the present invention, the swirl flow can be strengthened at low speeds and low loads, and at the same time, the swirl flow can be reduced by the Turnzle flow generated at high speeds. As a result, it is possible to prevent fuel from adhering to the wall surface of the combustion chamber, improving combustibility not only at low speeds and low loads but also at high speeds, thereby reducing HC and improving fuel efficiency.

Furthermore, by mounting the fuel injection valve so as to point it toward the spark plug, lean burn combustion can be performed, thereby further improving combustibility.

[Brief explanation of drawings]

FIG. 81 is a simplified plan sectional view showing the first embodiment of the present invention, FIG. 2 is a simplified side sectional view of the first embodiment, FIG. 3 is a control characteristic diagram of the shatter valve, and FIG. 5 is a simplified plan sectional view of the 82nd embodiment, FIG. 5 is a sectional view taken along the line v--2 in FIG. 4, and FIG. 6 is a simplified side sectional view of the second embodiment. l...Cylinder block 2...Cylinder head 4...Combustion chamber 5.6.7--Intake valve hole 11...Spark plug 12, 13゜23゜24...Site intake port 14゜21.22...Center intake port 15...Fuel injection valve 16゜25゜26...Shutter valve

Claims (2)

[Claims] (1) In an engine with three intake valve holes in the combustion chamber,
A central intake passage communicating with the central intake valve hole is formed along at least one of the side intake passages communicating with the intake valve holes on both sides, and a swirl flow is generated in the vicinity of the intake valve hole of the central intake passage. On the other hand, each side intake passage near the intake valve hole is formed so as to be oriented perpendicularly to the central intake passage in order to generate a Turnbull flow, and one side along which the central intake passage runs An intake system for an engine, characterized in that a side intake passage is provided with a passage opening/closing valve that closes the passage when the engine is at low speed and low load. (2) An intake system for an engine according to claim (1), characterized in that a fuel injection valve is installed in the central intake passage and is oriented toward a spark plug facing into the combustion chamber.