JPS6193229A - Suction device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To thin a quench layer due to fuel inside a combustion chamber, by installing a fuel injection valve in a high load suction passage too, besides a low load suction passage, in case of an engine provided with the high load suction passage that opens when high load is imposed on one cylinder. CONSTITUTION:A low load suction port 11B and a high load suction port 11A are installed in each cylinder 20, while a low load suction passage 12B and a high load suction passage 12A are interconnected to each of these ports. High load suction passages 12A of adjacent cylinders are unified at the upstream in one whereby these passages are opened by an on-off valve 13 only in time of high load. A fuel injection valve 19 is set up in this unified high load suction passage, and fuel is sprayed in time of opening the on-off valve 13. Therefore, even if a swirl in a combustion chamber in time of high load comes little, much fuel is fed out of a fuel injection valve 15 alone installed the low load suction passage, and the fuel is in no case stuck to a wall surface of the combustion chamber, thus a quench layer can be spread over the whole lot of a cylinder wall surface so thinly.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a technology for improving the intake system of an internal combustion engine having two intake valves for each cylinder.

<Prior Art> An example of an intake system for this type of internal combustion engine is the one shown in Fig. 4 (Japanese Patent Application No. 58-225356).
.

That is, one of the two intake ports 2A and 2B, for example, the intake port 2A, is provided with a butterfly-type on-off valve 3, and the on-off valve 3 is operated at low engine speeds. By closing the other intake port (2B), the intake air flowing along the 4th peripheral wall of the combustion chamber is used to generate a large swirl in the combustion chamber to improve combustibility at low speeds. By opening the valve 3 and opening the two intake ports 2A and 2B, intake resistance is reduced, intake air filling efficiency is increased, and output is improved.

Further, since the on-off valve 3 is opened less frequently in the normal operating range, the fuel injector 5 is provided on the intake port LA side, which is always open, in order to obtain stable air-fuel ratio control responsiveness.

Also, exhaust valves 6A, 6B and exhaust ports? Two each of A and 7B are provided, and the ignition plug 8 is provided near the center of the combustion chamber 4.

(Problems to be Solved by the Invention) By the way, in such an intake system, the on-off valve 3 is closed at high speeds.
When opened, two almost symmetrically formed intake ports 2 open.
Approximately the same amount of air flows in parallel from A and 2B and is introduced into the combustion chamber 4. In this case, after the fuel injected from the fuel injector 5 enters the combustion chamber 4, most of it mixes with the air introduced from the intake port 2A where the fuel injector 5 is not installed due to highly developed turbulence, but the combustion The quench layer formed by adhering to the wall surface of the chamber 4 (cylinder head surface and piston surface) tends to be concentrated near the intake valve IB interposed in the intake bow 1-2B on the side where the fuel injector 5 is installed, resulting in a thick quench layer. There was a problem in that the amount of HC (hydrocarbons) discharged unburnt due to the layer increased. In particular, in the case of an internal combustion engine with an exhaust turbo supercharger, the air-fuel ratio must be enriched to lower the exhaust temperature due to the heat resistance of the turbine rotor, which increases the quench layer and causes a significant increase in HC emissions. Become.

The present invention was made in view of the above-mentioned circumstances, and an object of the present invention is to provide an intake system for an internal combustion engine that can reduce as much as possible the amount of unburned HC discharged in the operating range where the on-off valve is opened. do.

Means for Solving the Problems> For this reason, the present invention provides an operation mode in which the on-off valve is opened separately from the first fuel supply means that supplies fuel to the intake port on the side where the on-off valve is not installed in all operating ranges. A second fuel supply means is provided in the area to supply fuel to the intake port on the side where the on-off valve is installed.

With this configuration, when the on-off valve is open, fuel is distributed and supplied from the first fuel supply means and the second fuel supply means through the two intake ports, so that a thick quench layer is formed. The uneven distribution of unburned HC can be prevented, and the amount of unburned HC discharged can be reduced.

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

In FIG. 1 showing one embodiment, a first . The second intake valve 11A, IIB and the first intake valve 11A, IIB with these intake valves interposed therebetween. A second intake port 12A and 12B are provided, an on-off valve 13 is provided to the first intake port 12A, and fuel is injected and supplied to the second intake port 12B in the entire operating range according to the output from the control unit 14. A first fuel injector 15 is attached to each. The injection timing of the first fuel injector 15 is set in synchronization with the completion of the intake stroke for each type of fuel.

16A and 16B are the first. Second exhaust valve, 17A, 1
7B is the first. The second exhaust port, 18, is a spark plug;
1st. The second intake valve 11A, IIB and the first intake valve 11A. The operating characteristics of the second exhaust valves 16A, 16B are as shown in FIG.

Further, the opening/closing valve 13 has its support shaft connected to an actuator (not shown), and is configured to switch from closed to open in a high speed range where the engine rotational speed is a predetermined value or higher.

In addition to this configuration, between a plurality of cylinders, for example, in the case of the four-cylinder engine in this embodiment, the ignition timing is set between the first pair of adjacent cylinders #1 and #4, and the pair of cylinders #2 and #3. The upstream portions of the intake ports 12A and 12A are merged into a single line, and a second fuel injector 19 as a second fuel supply means is attached to this merged portion 12A'. In the figure, only the #2 cylinder and #3 cylinder are shown.

This second fuel injector 19 is configured to inject and supply fuel only in the operating range where the on-off valve 13 is opened by the output from the control unit 14.
The injection timing is the same as the first intake port 12A #
It is set to be injected once per 360° crank angle in synchronization with the completion of the intake stroke of the 2nd cylinder and the #3 cylinder. Fuel injector 19 for #1 cylinder and #4 cylinder
The same applies to

The fuel injected from each fuel injector 19 is then injected into the first intake bow) 12 of the two branched cylinders.
The amount of fuel supplied per cylinder is approximately equal to the amount of fuel supplied from the first fuel injector 15 attached to the second intake port 12B. The settings are as follows. In addition, these 1st. Calculation of the injection amount from the second fuel injector 15, 19, etc. is performed by a microcomputer M in the control unit 14, which inputs the engine rotational speed signal and the intake flow rate signal.

Next, the action will be explained.

In the low speed range of the engine, the on-off valve 13 closes and intake is performed only through the second intake valve 11 with a small delay in closing timing.
Combustibility can be improved by creating a swirl and substantially increasing the compression ratio, and in the high-speed range, the on-off valve 13 opens and the first intake valve 11A, which has a large delay in closing 11.7, is used in conjunction with the intake valve 11A. By doing this, you can effectively utilize the inertia effect of intake air,
In addition, this invention is similar to the previous application in that it reduces intake resistance, increases intake air filling efficiency, and improves output.

Further, as an effect of the present invention, the fuel injected from the second fuel injector 19 to the confluence section 12A° in the high speed range when the on-off valve 13 is opened is transferred to the first branch of each cylinder.
The fuel injector 15 is distributed to the intake port) 12A, 12A, and the first fuel injector 15 is distributed to the second intake port) 12B.
The fuel flows into the combustion chamber 20 of each cylinder together with the fuel that is injected into the combustion chamber 20 of each cylinder.

In this way, the first. Second intake port 12A, 12B
In the high-speed areas where both are open, the first. Since the second fuel injectors 15, 19 evenly distribute fuel to the first and second intake ports 12A and 12B, respectively, the quench layer is formed in the first and second intake ports 12A and 12B. It is dispersed and spread thinly around the second intake valves 11A and IIB, making it possible to significantly reduce the amount of unburned HC discharged.

Further, since the upstream portions of the first intake holes 2A and 12A of the two cylinders are merged into a single cylinder, it is sufficient to provide only half the number of second fuel injectors 19 as the number of cylinders.

Incidentally, the upstream portions of the first intake ports of all cylinders may be merged into one, and in this case, the injection from one fuel injector installed at the merged portion is at a crank angle of 1
It is sufficient to do this once every 80 degrees.

Further, an on-off valve may be provided at the confluence portion of the first intake port, and the number of attached valves can be reduced, and sealing performance can be improved by reducing the number of on-off valves. In this case, it goes without saying that a second fuel injector is provided upstream of the on-off valve.

Furthermore, the upstream portions of the second intake ports of each cylinder may be similarly merged, and a fuel injector may be provided in the merged portion.

FIG. 3 shows a second embodiment of the invention. This thing is
In an engine having an intake passage structure similar to the previous application in which the intake port on the side where the on-off valve is installed is provided independently for each cylinder, the on-off valve is installed downstream of the on-off valve 13 at the intake port 12A on the side where the on-off valve 13 is installed. A second fuel injector 19 is provided which injects and supplies fuel to the intake port 12A only when the intake port 13 is open.

However, the same reference numerals are given to the same components as in the first embodiment.

When the on-off valve 13 is opened, the first. The amounts of fuel injected from the second fuel injectors 15 and 19 are set to be equal. In this embodiment, the number of second fuel injectors 19 installed is doubled compared to the first embodiment, but the amount of fuel supplied to each cylinder can be accurately distributed evenly, and the second fuel injectors 19 19 can be brought closer to the combustion chamber 20, transient operation (acceleration)
The time response is improved.

In addition, the above-mentioned No. 1. In the second embodiment, the on-off valve 1
3 during the transition period between fully closed and fully open, the 1st.
Gradually changing the ratio of the fuel supply amount from the second fuel injector 15°19 to the total fuel supply amount,
It is preferable to set it so that 1=1 when fully opened.

This is because such a transient region is a speed region in which a large amount of HC is likely to be discharged, so that the HC reduction effect by equalizing the mixture concentration at each intake port is large.

Furthermore, if a very small amount of fuel is supplied from the second fuel injector 19 when the on-off valve 13 is closed, carbon, etc. in the exhaust gas that adheres to the injection hole of the fuel injector 19 can be washed away by this fuel. and its operation can be maintained in good condition.

<Effects of the Invention> As explained above, according to the present invention, since the second fuel supply means is provided to mainly supply fuel to the intake port on the side where the on-off valve is installed when the on-off valve is opened, the fuel can be It can be distributed and supplied from the two intake ports of each cylinder, thereby achieving the effect that the quench layer in the combustion chamber can be spread thinly and the amount of unburned HC discharged can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional configuration diagram of essential parts showing a first embodiment of the present invention, FIG. 2 is a diagram showing the operating characteristics of the intake/exhaust valve of the same embodiment, and FIG. 3 is a diagram showing a second embodiment of the present invention. A sectional view of main parts showing an example of
FIG. 4 is a sectional view of a main part of an intake system for an internal combustion engine according to a prior application filed by the present applicant.

Claims (1)

[Claims] Each cylinder is provided with two intake valves and two intake ports with these intake valves interposed therein, and one of the two intake ports is provided with an on-off valve that opens and closes depending on engine operating conditions,
and a second fuel supply means for supplying fuel to the one intake port in an operating range in which the on-off valve is opened, in an intake system for an internal combustion engine, which is provided with means for supplying fuel to the other intake port in all operating ranges. An intake system for an internal combustion engine, characterized in that it is provided with.