JPS603477A - Fuel injector for internal-combustion engine - Google Patents

Abstract

PURPOSE:To reduce fuel consumption and improve stability of an engine in low load by providing a sub-fuel injection valve driven in the low load in an auxiliary intake path. CONSTITUTION:Fuel is supplied mainly from a main fuel injection valve 12 and a sub-fuel injection valve 17 is driven in low load including idling time. Air passes through a slight gap between a throttle valve 13 and the inner wall of an intake path 15 with speed near acoustic velocity in the idling time. Thus, fuel supplied to an auxiliary intake path 16 from the sub-fuel injection valve 17 is sucked out of the opening end 16b of said path 16 and atomized very satisfactorily by the high speed air flow. Also, in the low load where the throttle valve 13 is slightly opened, a comparatively large intake negative pressure acts on the opening end 16b of the auxiliary air path 16 to provide similarly satisfactory atomization.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a fuel injection device for an internal combustion engine that performs fuel injection during 4Q at a position upstream of a throttle valve.

Internal combustion engine with multiple cylinders 1) 1 fuel injection device 1'L
For example, as shown in FIG. 1, one or two fuel injection valves 3 facing the throttle valve 2 at an angle of 49 degrees are disposed upstream of the throttle valve 2 in the intake passage. There is a system in which B2I injection is performed intensively and the air-fuel mixture formed here is distributed to each cylinder downstream of the throttle valve 1 (Japanese Patent Laid-Open Publication No. 57-73858 Y1λ, etc.).

According to this, the 479 configuration is simple and low cost compared to a fuel injection system in which one injector is provided in the intake boat of each cylinder, and on the other hand, the 479 configuration is simple and low cost. If the air-fuel ratio is 1ir1. l 1 no! 1.1
It has the advantage of being slightly intensified on the 1q degree surface.

However, when fuel injection is performed intensively in this way, the above-mentioned 971. '1 As the fuel injection valve 3,
It is necessary to use a relatively large-capacity fuel injector to sufficiently cover the fuel required at high speeds and high loads, and therefore atomization is poor when the amount of fuel injected is small, such as during idling or low load. There is a problem in that the fuel tends to reach the throttle valve 2 etc. in the form of droplets, resulting in deterioration of fuel efficiency and engine stability due to this iL.

This invention was made in view of the conventional problems such as those mentioned above, and it enables sufficient fuel atomization even under low load conditions when the amount of fuel supplied is small. The aim is to improve fuel efficiency and engine stability at low loads, which had been a problem.

Specifically, the fuel injection device for an internal combustion engine according to the present invention has the following features:
A main fuel injection valve is installed at a position upstream of the throttle valve in the intake passage and is oriented toward the throttle valve, with one end opening upstream of the throttle valve and the other end opening in the throttle valve fully closed position or downstream of the throttle valve. The auxiliary intake passage is provided with an auxiliary intake passage that opens at a position, and an auxiliary fuel injection valve that is provided in the auxiliary intake passage and that is operated at least when the load is low. Very good atomization can be achieved by sucking out the supplied fuel at the fully closed position of the throttle valve or downstream of the throttle valve.

Hereinafter, a specific embodiment of the present invention will be described in detail based on all the drawings.

Fig. 2 shows the fuel injection amount [¥, the injection volume l/l tested by the main fuel injection valve P7.2 according to the present invention]. The upper half //a has a throttle valve /3f5 and the lower half 7'j1 has a throttle valve /3f5 (
//b, and both are integrated via a heat insulating gas cant/hiro, and the intake air is drawn in the vertical direction.
i3, the lower end of which is also a wedge-shaped gasket)/
*The whole body is connected to the intake manifold nK, and the upper end is connected to an air cleaner (not shown). The main fuel injection valve located upstream of the throttle valve /3 is supported from any direction so as to protrude into the intake passage 15;
The lower end nozzle /, 2a is directed towards the above-mentioned diaphragm -fPt3. Note that this main fuel injection valve 12 has a relatively large discharge capacity, usually 111I! ! ] Or about two are provided.

On the other hand, one end /4a of the lower half of the intake engine body l//b opens upstream of the throttle valve 13 of the intake passage 13,
In addition, an auxiliary intake passage /6 is formed whose other end /6b opens at the throttle valve 13d] position, and this auxiliary intake passage /6 is formed.
A relatively small auxiliary fuel injection valve/7 with a capacity of 1 is temporarily installed in B. In addition, Ig and /q are the main fuel injection valves 12
fuel supply passage and fuel return passage, no. and 2/ are a fuel supply passage and a fuel return passage of the auxiliary fuel injection valve /7.

In the above configuration, %j:Ig+E fuel supply is mainly performed by the main fuel injection valve/2 upstream of the throttle valve/3, and
:it: auxiliary fuel injector/7 is the above main fuel injector/2
In other words, at idle, the gap between the throttle valve 13 and the inner wall of the intake passage 15 is close to the air velocity. Since it passes at a speed, upper tfl-: secondary combustion 84-
The fuel 1 supplied into the auxiliary intake passage 16 by the injection valve /7 is sucked out from the opening y;

-1: At low load when the throttle valve "/3" is slightly open, a relatively large suction negative pressure acts on the opening end of the auxiliary intake passage 16 (/61), ensuring good atomization as well. can.

At this time, the main fuel injector 2 may be subjected to TLI control so as to completely stop its fuel injection, since the problem of so-called disconnection is likely to occur when starting fuel injection under a constant load. A portion of the fuel may always be supplied through the main fuel injection valve/2°. In other words, either the main fuel injector (1) and the auxiliary fuel injector (7) can be switched at a constant load and controlled so that they move 1, or both can be moved at the same time in a partial or full load range. Various types of control are possible, such as changing the proportion of each fuel injection depending on the load.In addition, each fuel injection is the sum of the
Period 7) It goes without saying that tlilJ is determined depending on the air-fuel ratio.

As described above, by improving fuel atomization when the rear equipment is loaded, engine stability, fuel efficiency, and lean limit can be improved. Figure 3 shows the relationship between fuel consumption and suction negative pressure during idling. Number and )j, i fire timing course - 5Jyu()' idle rotation speed:
700 rpm, ignition timing: 12° BTDC) while changing the idle air-fuel ratio (i.e., corresponding to the 17% charge).
t+1 and plotted (○...conventional, △...this example), C, and F at the same time, and the stability 67 value at that time is written in each plot symbol 1. Furthermore, this stability is 1 to 7.
The higher the number, the more stable the item is from 1 to 5, and the higher the value, the more stable it is.
It is Jtl. As is clear from this Figure 3, the point is 7.
Compared to the conventional method shown by the solid line, this example enables a significant reduction in the amount of tX:〉1 charge consumption.
Moreover, it is possible to expand the area of degree ``4'' or higher at low cost. Boxed collection 4
The figure also shows (equivalent amount δ: ; sintered state k
, T Og% degree (in the exhaust gas which is an index indicating 1) and empty space'::! , the relationship with Mobi was completely sold. This fourth
As is clear from the figure, the present embodiment shown by the dotted line can significantly reduce the total He concentration near the stoichiometric air-fuel ratio compared to the conventional one shown by the solid line, and can also Even during subsidence, no sudden drop in He intensity is observed, which means that combustion stability can be maintained well even under lean air-fuel ratios.

Next, in the embodiment shown in FIG.
All i/Abs are installed downstream of the throttle valve/3.

This makes full use of the suction negative pressure developed downstream of the throttle valve 13 during idle or low load to suck fuel from the auxiliary fuel 1 (injection valve/7), and also to suck fuel from the opening y; g/xb. The atomization of the fuel is entirely performed by air that expands and diffuses rapidly due to negative pressure, and this configuration can also achieve the same effects as the above-mentioned embodiment.

As is clear from the above description, in the fuel injection device for an internal combustion engine according to the present invention, by supplying fuel to a low position through an auxiliary fuel injection valve, the fuel injection device according to 9. It is possible to improve the fuel efficiency of the L and US classes, and it completely improves fuel efficiency and engine stability at low loads compared to the conventional fuel gun f'2. be able to.

[Brief explanation of the drawing]

Figure 1 shows an example of a conventional fuel injection system.
Figure +f+i and Figure 2 are cross-sectional views showing one embodiment of the present invention.
Figures j and 3 are the idle Jv Nezumi and j'b
't l': Characteristic diagram showing the need for I-female return, DI'44 diagram is a characteristic diagram showing the relationship between HO distribution IW and air-fuel ratio at idle,
FIG. 5 is a sectional view showing a different embodiment of the invention. //...injection body, /mouth...earth fuel injection valve%/3...throttle valve, /J...intake passage, /6...
- Auxiliary intake passage, 17...auxiliary fuel injection valve. 1

Claims (1)

[Claims] (1) Throttle tf'l of the intake passage The main fuel injection valve is provided in its original position facing the throttle valve, one end is open upstream of the throttle valve, and the other end Δ1j is the throttle valve fully closed position or the throttle valve. 1. A fuel injection device for an internal combustion engine, comprising an auxiliary intake passage that opens at a downstream position, and an auxiliary fuel injection valve that is provided in the auxiliary intake passage and is flexed once at least when the load is low.