JPH04272473A - Fuel injection device - Google Patents

Abstract

PURPOSE:To provide a fuel injection device of an internal combustion engine having three or more suction ports per cylinder, with which fuel-through to the exhaust side can be suppressed in the valve overlapping period. CONSTITUTION:From a fuel injection valve 22 disposed at each cylinder of an internal combustion engine upstream of intake ports 10 to 12 of the cylinder, fuel in supplied only to the intake port 11 except the other ports 10, 12 having openings 10a, 12a positioned close to the openings 13a, 14a of exhaust ports 13,14. As a result, the fuel is prevented from going through from the intake ports 10, 12 to the exhaust ports 13, 14 without making any contribution to combustion at the time of valve overlapping.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection system, and more particularly to a fuel injection system for an internal combustion engine having three or more intake ports for each cylinder.

0002

[Prior Art] In recent years, as part of efforts to improve the performance and output of internal combustion engines, it has been required to improve the intake efficiency of the engine, and for this purpose, the number of internal combustion engines equipped with three intake ports (intake valves) has increased. ing. When installing a fuel injection device to such an internal combustion engine, the installation of the fuel injector is carried out according to, for example, Japanese Utility Model Application Publication No. 186765/1986 and Japanese Utility Model Application No.
As shown in Japanese Patent No. 40977, etc., sprayed fuel from a fuel injection valve is distributed and supplied to three intake ports in some way.

0003

[Problem to be Solved by the Invention] However, among the three intake ports, in the intake port near the exhaust port,
During a so-called valve overlap period in which the intake valve and exhaust valve open simultaneously, fuel entering the combustion chamber escapes to the exhaust port, causing a problem of worsening emissions in the exhaust gas.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel injection device that can suppress the leakage of fuel to the exhaust side during the valve overlap period.

[0005]

[Means for Solving the Problems] The present invention provides three or more intake ports provided in one cylinder and opening into a combustion chamber;
The internal combustion engine is provided with an intake valve that opens and closes an opening of the intake port, an exhaust port that opens into the combustion chamber, and an exhaust valve that opens and closes the opening of the exhaust port. From the fuel injection valve disposed in each cylinder upstream of the intake port of the engine, out of three or more intake ports in one cylinder, the intake port other than the intake port having an opening close to the opening of the exhaust port The gist of this is a fuel injection device that supplies fuel to an intake port.

[0006]

[Operation] Among three or more intake ports in one cylinder,
Fuel is supplied from the fuel injection valve to an intake port other than the intake port having an opening close to the opening of the exhaust port. As a result, during the so-called valve overlap period in which the intake valve and exhaust valve open simultaneously, fuel is not supplied to the intake port whose opening is close to the exhaust port opening, so fuel is not supplied from this intake port to the combustion chamber. This prevents the sprayed fuel from escaping to the exhaust side without contributing to combustion.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the present invention will be described below with reference to the drawings. 1 and 2 show one cylinder of a multi-cylinder internal combustion engine. A cylinder head 2 is fixed on the cylinder block 1, and an intake pipe 3 is connected to the cylinder head 2. A circular cylinder 4 is formed in the cylinder block 1, and a piston 5 is slidably supported within the cylinder 4. A combustion chamber 6 is located above the piston 5 within the cylinder 4.

An intake port 7 is formed in the cylinder head 2 and communicates with an intake passage in an intake pipe 3.The intake port 7 is branched by partition walls 8 and 9 into intake ports 10, 11, and 1.
2, which opens into the combustion chamber 6. The cylinder head 2 also has two exhaust ports 13 and 14 that open into the combustion chamber 6.
are formed, and the exhaust ports 13 and 14 communicate with an exhaust passage 15. Openings 10 of intake ports 10, 11, 12
a, 11a, 12a and the openings 13a, 14a of the exhaust ports 13, 14 are circular with the same area, and are arranged at equal distances and equal angles (72 degrees) with respect to the center of the cylinder 4. Moreover, the openings 10a of the intake ports 10, 11, 12
, 11a, 12a are arranged on the right side in FIG. 1, and the openings 13a, 14a of the exhaust ports 13, 14 are arranged on the left side in FIG. This cylinder 4 has intake valves 16, 17, 18 for each intake port 10, 11, 12.
are provided, and openings 10a to 12 of each port 10 to 12 are provided.
Open and close a. In addition, an exhaust valve 1 is provided for each exhaust port 13 and 14.
9, 20 are provided, and the opening 13 of each port 13, 14 is provided.
a, 14a are opened and closed.

Furthermore, a spark plug 21 is arranged in the combustion chamber 6. Further, a fuel injection valve 22 is attached to the intake pipe 3, and the tip of the fuel injection valve 22 is exposed to the intake passage within the intake pipe 3. This fuel injection valve 22 is fixed so as to face the opening 11a of the central intake port 11 among the three intake ports 10, 11, and 12. FIG. 3 is an enlarged view of the tip portion of the fuel injection valve 22. As shown in FIG. A seat surface 24 is formed within the valve body 23, and the diameter of the seat surface 24 decreases toward the tip, and a nozzle hole 25 is formed at the tip of the seat surface 24. Further, a needle valve 26 is disposed within the valve body 23, and a tip portion 27 of the needle valve 26 passes through the nozzle hole 25 and projects to the outside of the valve body 23, forming a conical portion 28 having a widening angle α. The needle valve 26 is movable in the left and right directions in FIG.
I am seated at number 4. Then, due to the excitation of the coil, the needle valve 26 moves to the right in FIG.
The fuel separates from the fuel and is injected in the form of a mist. At this time, the spread angle β (see FIG. 1) of the sprayed fuel is determined in accordance with the spread angle α of the conical portion 28 of the needle valve 26.

The sprayed fuel from the fuel injection valve 22 spreads in a conical shape, and the spreading angle β is about 10 to 20 degrees. All of this sprayed fuel is set to be sent only to the intake port 11. In general, the wider the spray angle (β), the better the atomization of the fuel, so the spray angle should not be made narrower than necessary. Also, if the spray spreads too much,
Since the amount of fuel adhering to the wall increases and transient characteristics deteriorate, it is better for the spray to directly hit the intake valve 17.

In FIG. 4, fuel is supplied to three intake ports 10,
11 and 12 evenly (Comparative example ■), a case where it was evenly supplied only to the intake ports 10 and 12 on both sides (Comparative example ■), and a case where it was supplied only to the center intake port 11 of this example. 2 shows the measurement results of the HC concentration in the exhaust gas at idle (600 rpm) in the case of FIG. From this figure 4,
It can be seen that the smaller the amount of fuel supplied to the intake ports 10, 12 which are closer to the exhaust port, the lower the HC concentration at idle can be.

The reason why the HC concentration can be reduced by supplying fuel only to the central intake port 11 will be explained below. FIG. 5 shows a cross section taken along the line AA in FIG. In an internal combustion engine equipped with five intake and exhaust valves 16 to 20 per cylinder, the valves 16 to 20 are arranged close to each other in order to maximize the efficiency of gas exchange, and the intake and exhaust valves 16 to 20 shown in FIG. When the intake ports 10 and 1 open at the same time (valve overlap),
A part of the fuel entering the combustion chamber 6 from the combustion chamber 6 escapes to the exhaust ports 13 and 14 without contributing to combustion. This phenomenon occurs more noticeably in high-output engines (especially motorcycle engines) with long valve overlap periods, and is particularly noticeable in engines that use fuel injection valves to supply fuel toward the intake port. In the port fuel injection method, fuel tends to accumulate in liquid form before the intake valve opens, so some of the accumulated fuel tends to travel along the walls of the combustion chamber and escape into the exhaust gas.

However, in this embodiment, since fuel is supplied only to the central intake port 11, the fuel that enters the combustion chamber 6 from the intake ports 10 and 12 during valve overlap flows to the exhaust side without contributing to combustion. It never falls out. As a result, the HC concentration in the exhaust gas can be reduced. In this way, in this embodiment, the intake port 10 of the internal combustion engine,
From the fuel injection valve 22 arranged in each cylinder upstream of 11, 12, the intake port 10, 11, 1 in one cylinder
2, the openings 13a and 14 of the exhaust ports 13 and 14
The fuel is supplied only to the intake ports 11 other than the intake ports 10 and 12 having the openings 10a and 12a that approach from a. In other words, by collecting the fuel supplied from the fuel injection valve 22 into the central intake port 11, as shown in FIG.
As shown in FIG. 2, it is possible to prevent part of the fuel from leaking from the intake ports 10, 12 to the exhaust ports 13, 14 without contributing to combustion. As a result, the unburnt gas concentration (HC concentration) in the exhaust gas can be significantly reduced.

In addition, in the conventional device in which the fuel injection valve is formed with a nozzle hole that points toward each intake port, the center line L1 (see FIG. 1) of the fuel injection valve is High precision positioning was required to regulate rotation. However, in this embodiment, it is sufficient to inject fuel only to the center line L1 of the fuel injection valve 22, so that the performance required of the fuel injection valve 22 is such that it is sufficient to simply spray in a conical shape. The influence of manufacturing variations on the performance can be reduced, and furthermore, even if the fuel injection valve 22 rotates about its center line L, there is no influence at all, so the structure can be simplified.

It should be noted that the present invention is not limited to the above-described embodiment; for example, in the above-mentioned embodiment, an internal combustion engine having three intake ports/intake valves per cylinder has been described, but an internal combustion engine having four intake ports/intake valves per cylinder has been described. The present invention may be applied to an internal combustion engine equipped with the above intake ports and intake valves.

[0016]

[Effects of the Invention] As detailed above, according to the present invention,
It has the excellent effect of suppressing fuel leakage to the exhaust side during the valve overlap period.

[Brief explanation of the drawing]

FIG. 1 is a plan cross-sectional view of an internal combustion engine according to an embodiment.

FIG. 2 is a side sectional view of the internal combustion engine of the embodiment.

FIG. 3 is an enlarged view of the tip of the fuel injection valve.

FIG. 4 is a diagram showing HC concentrations in exhaust gas in Examples and Comparative Examples.

FIG. 5 is a sectional view taken along line AA in FIG. 1;

FIG. 6 is a diagram for explaining valve lift.

[Explanation of symbols]

6 Combustion chamber 10 Intake port 11 Intake port 12 Intake port 13 Exhaust port 14 Exhaust port 16 Intake valve 17 Intake valve 18 Intake valve 19 Exhaust valve 20 Exhaust valve 22 Fuel injection valve

Claims (1)

[Claims] [Claim 1] Three or more intake ports are provided in one cylinder, and include an intake port that opens into a combustion chamber, an intake valve that opens and closes an opening of the intake port, an exhaust port that opens into the combustion chamber, and the exhaust port. The fuel injection valve is provided in an internal combustion engine equipped with an exhaust valve that opens and closes an opening of A fuel injection device characterized in that, among the above intake ports, fuel is supplied to an intake port other than the intake port having an opening close to the opening of the exhaust port.