JPH036857Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a fuel injection device for an engine that injects fuel overlapping the opening timing of an intake port.

(Prior art) Engine intake structures have been known that achieve high output by opening two intake ports in the combustion chamber of the engine to significantly increase charging efficiency (for example, (See Publication No. 56-44419).

On the other hand, the fuel injection timing of the fuel injector is set to overlap with the timing when the intake port is opened by the intake valve, and the fuel is introduced into the combustion chamber along with the intake air flow to atomize and vaporize the fuel. In a fuel-injected engine designed to promote the flow of fuel (see Japanese Patent Laid-Open No. 148636/1983), when the opening timings of the intake valve and exhaust valve partially overlap, so-called intake/exhaust overlap, a portion of the injected fuel is If the fuel is discharged from the exhaust port along with the exhaust gas, there is a problem of fuel leakage.

(Purpose of the invention) An object of the invention is to provide a fuel injection device for an engine having a configuration in which fuel is not directly discharged from an exhaust port when fuel is supplied to two intake ports from a common fuel injection valve. It is.

(Structure of the invention) In order to achieve the above object, the invention differs in the timing of opening and closing of the intake valves that respectively open and close the two intake ports connected to the two branched intake passages formed by branching in the middle. , the exhaust port is installed close to the intake port that is opened and closed by the intake valve, which has a longer overlap in opening timing with the exhaust valve, while the fuel injection valve is installed closer to the other intake port. Even if the fuel injection timing of the injector is set to partially overlap the intake/exhaust overlap timing, the injected fuel will not be directed toward the exhaust port.

(Effects of the invention) According to the invention, even if the fuel injection timings are overlapped at the time of intake/exhaust overlap, it is possible to reliably prevent fuel from blowing through from the exhaust port.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

As shown in FIG. 1, in the combustion chamber 2 of the cylinder 1 of the engine E, first and second intake ports 3 and 4 having approximately equal areas are opened symmetrically with respect to the center line l in the width direction of the combustion chamber 2. Intake passages 7 branched from a common intake passage 6 of the intake manifold 5 to each cylinder 1
is branched into two intake passages 10 and 11 within the cylinder head 8 by a partition wall 9 extending along the width direction center line l, and these two intake passages 10 and 11 are divided into a first intake passage and a first intake passage 11. 2 intake ports 3, 4
are connected to each other.

Of these first and second intake ports 3 and 4, the first
An exhaust port 12 is opened into the combustion chamber 2 so as to face the intake port 3.

The opening and closing characteristics of the intake valves (not shown) that open and close the first and second intake ports 3 and 4 are shown in FIGS.
As shown in FIG. ), the overlap with the opening timing of the exhaust valve is lengthened, and the intake valve of the second intake port 4 and the exhaust port 12 are
Set the overlap with the exhaust valve to be short.

The opening/closing timing of the intake/exhaust valves is set by
This can be done using a conventionally known valve mechanism,
Based on this setting, the fuel injection valve 13 is installed offset to the second intake port 4 side with respect to the width direction center line l, as shown by the dotted line in FIG.
The configuration is such that most of the fuel injected from the fuel injection valve 13 is directed toward the second intake port 4.

With such a configuration, even if the fuel injection timing of the fuel injection valve 13 is set to coincide with the intake/exhaust overlap, as shown by D in FIG. Since the exhaust port 12 is not directed toward the exhaust port 12, direct blow-by of fuel from the exhaust port 12 is reliably prevented. Most of the injected fuel flows through the second intake port 4, which is opened later.
is introduced into the combustion chamber 2, where it is atomized and
After being vaporized, in the compression stroke, the second intake port 4
The ignition is ignited by the ignition plug 14, which is placed opposite to the ignition plug 14, and ignition combustion occurs.

As described above, if the positional relationship and timing relationship of the first and second intake ports 3, 4, exhaust port 12, and fuel injection valve 13 are determined, even if the fuel injection timing is set at the time of intake/exhaust overlap, the fuel Blow-through from the exhaust port can be prevented.

[Brief explanation of the drawing]

FIG. 1 is an explanatory horizontal cross-sectional view of the main parts of an engine showing an embodiment of the present invention, and FIG. 2 is a graph showing the opening/closing characteristics of intake and exhaust valves and the fuel injection timing of a fuel injection valve. 2... Combustion chamber, 3, 4... First and second intake ports, 12... Exhaust port, 13... Fuel injection valve.

Claims (1)

[Claim for Utility Model Registration] Two intake ports connected to branch intake passages formed by branching from the middle of the intake passage leading to each cylinder, and opened and closed by intake valves, and In an engine equipped with one exhaust port that opens and closes at the same time, and a fuel injection valve that supplies fuel from upstream of the branch point of the intake passage, the opening and closing timings of the intake valves are set to be different from each other, and at least The opening timing of one intake valve and the opening timing of the exhaust valve are partially overlapped, and the fuel injection timing of the fuel injector is set to include the overlap timing, so that the opening timing of the exhaust valve is overlapped. The exhaust port is installed close to the intake port, which is opened and closed by a long intake valve, and the fuel injection valve is installed offset to the intake port, which is opened and closed by the other intake valve with a short overlap. Features the engine's fuel injection system.