JPS58143136A - Fuel injection device in internal-combustion engine - Google Patents

Abstract

PURPOSE:To make it possible to supply a stable mixture over a whole operating range, by reducing the fuel pressure applied to an injector upon operation under low engine load so that the range at which the pulse width of fuel injection by the injector is short is not used. CONSTITUTION:Fuel pressure applied to the inlet of an injector 3 to which fuel sucked up by a fuel pump 8 is fed, is adjusted by a pressure regulator 9 for maintaining the pressure difference with respect to the injection port of the injector 3. A plunger 11 is disposed in the regulator 9 so that a set force due to a solenoid 10 and a spring 12 is altered for switching a set pressure difference by two steps. The plunger 11 is moved away from the solenoid 10 for returning the spring 12 when the solenoid 10 is deenergized, and therefore, the set pressure difference is made low. Thus the set differential pressure is lowered in the range where the injection width of an output delivered to the injector 3 becomes less than a predetermined value, thereby the pulse width is made long.

Description

[Detailed description of the invention] The present invention relates to a fuel injection device for an internal combustion engine.

In a conventional fuel injection device for an internal combustion engine, the differential pressure between the fuel inlet of the injector and the injection port is always kept constant by a regulator. Ninth, when one injector is used as a fuel supply means, the injection pulse width for injection control is very short from Q, f3 m s to 5 ms.
To create an injector that satisfies this range requires extremely advanced technology. (9) When injected into the intake pipe, the effect of the assist air that further atomizes the fuel is small after the injection pulse width Q, 3 m S @, and there is a drawback that a stable air-fuel mixture cannot be created.

The purpose of the present invention is to reduce the fuel pressure applied to the injector when the load applied to the engine is small and to avoid using the short injection pulse width region of the injector, thereby stably supplying an air-fuel mixture over the entire operating range of the engine. An object of the present invention is to provide a fuel injection device for an internal combustion engine that controls the set pressure of a pressure regulator for keeping the differential pressure between the fuel inlet of the injector and the injection valve constant.
When the load is small, a means for lowering the load is provided so that the region of the injector's injection pulse width that is short is not used. As a result, when fuel is injected with a single injector downstream of the throttle valve, the effect of assist air that promotes fuel atomization improves as the injection pulse width becomes longer, and furthermore, the operating limit conditions for the injector pulse width are improved. It is made so that it can be loosened.

Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a block diagram of a system using the present invention,
1 is a vaporization pipe, 2 is an air flow sensor, 3 is an injector, 4 is a rotation sensor, 5 is a water temperature sensor, 6 is a control unit, 7 is a Tsuyuel damper, 8 is a Tsuyuel pump,
9 is a pressure regulator. To explain the operation of the main parts, engine rotation speed N1 intake air amount Qab detected by each sensor of the distributor built-in rotation sensor 4, air flow sensor 2, and water temperature sensor 5
The engine coolant temperature TW is input to the control unit 6. Based on these input data, the injection pulse width output to the injector 3 is calculated inside the control unit 60.Actual fuel injection by the fist injector 3 is performed in synchronization with the engine rotation, and the width of the injection pulse output to the injector 3 is
Fuel is injected twice. Regarding the fuel system, fuel is pumped up by a fuel pump 8 and supplied to the injector 3 through a fuel damper 7 that eliminates pulsation. At this time, the fuel pressure applied to the inlet of the injector 30 is regulated by a pressure regulator 9 that keeps the differential pressure with the injection port constant.

The pressure regulator 9 has a regulator solenoid 10 and a spring 1 so that the set differential pressure can be switched to two levels.
A plunger 11 is provided for changing the setting force of 2.

When the regulator solenoid 10 is energized, the plunger 11 is attracted and the spring 1z is pushed in, so the set differential pressure of the regulator 9 increases.0 When the energization is stopped, the plunger 11 separates from the regulator solenoid 1o, resulting in the state shown in FIG. 1. Therefore, the spring 12 is returned to its original position, and the set differential pressure becomes smaller. As a result, in a region where the injection pulse width output to the injector 3 is smaller than a predetermined value, the regulator solenoid 1° is de-energized, the set differential pressure is lowered, and the pulse width is reduced by the amount of fuel reduced with the same injection pulse width. Figure 82 is a cross-sectional view of the carburetor l, showing the flow of assist air that promotes atomization of the injected fuel. The assist air indicated by symbol A is assist air intake port 1.
After being sucked in from the air jet 3 and metered by the air jet 14, it is ejected around the injection port of the injector 3.

! Figure 3 is an explanatory diagram showing the effect of this assist near. When the width of the injection pulse applied to the injector 3 is increased while the flow rate of the assist air and the amount of fuel injected per pulse are kept constant, This indicates that the particle size of the injected fuel becomes smaller.

The reason for this is that the time that the same amount of fuel is in contact with the assist air increases with the pulse width, and in order to keep the amount of fuel injected per pulse constant, the longer the pulse width, the more fuel is injected. As a result, the difference in speed between the injected fuel and the assist air increases, which may improve the atomization effect.

Figure 4 is a characteristic diagram of the fuel pressure of the pressure regulator 9. When the regulator solenoid is energized, the differential pressure between the intake pipe and the fuel inlet of the injector is 27 ke/cm, and when the solenoid is off, it is 1.4 ke/cm. 1 has a comrade.

FIG. 5 shows the flow rate characteristics of the injector in each case. In FIG. 5, Pm1n indicates the minimum value of the injection pulse width to be used, and a shorter pulse width is not used.

FIG. 6 is a flowchart showing an example of control according to the present invention. First, the engine speed N.

Measure the intake air amount Qa and turn on the regulator solenoid.
Calculate the injection pulse width P, . Then P, is p m
It is determined whether the distance is larger than 1 m or not, and if it is larger, the regulator solenoid 10 is turned on and the injection pulse width of the injector 3 is set to P,...'t. If it is small,
Regulator solenoid Lot-OFFL, I (the pulse width must be lengthened by the amount that the fuel pressure has decreased, so the correction factor # is multiplied by P, , and 9P is obtained.
, tl, t are set as the injection pulse width of the injector 3.

Next, a system diagram showing another embodiment of the present invention is shown in FIG. 7. In FIG. 7, the difference from FIG. An intake pressure sensor 16 and an intake pipe temperature sensor 17 are provided to detect the degree a, and a pressure regulator 9 is also provided.
This is a replacement for the pressure regulator 18 with a heavy diaphragm.

FIG. 8 shows the fuel pressure characteristics of this double diaphragm pressure regulator 18. Conventional regulators keep the differential pressure between the fuel inlet of the injector and the intake pipe constant at 17 kp/cWI, but in the case of the double diaphragm pressure regulator 18, the pressure increases as the vacuum level of the intake pressure increases, that is, the load increases. The smaller the set differential pressure becomes, the smaller the set differential pressure becomes. FIG. 9 shows the intake pressure correction coefficient for lengthening the injection pulse width by the amount that the set differential pressure becomes smaller.

FIG. 10 shows the ninth control point in this embodiment. First, engine speed N1
Intake pressure v1, intake pipe internal temperature T.

, and calculate the intake air amount Q. This air amount Q,
From this, calculate the injection pulse width Pa when using a conventional pressure regulator, multiply the intake pressure v and the coefficient found from Fig. 9 by 7 degrees, and set 9 P ot + t in the injector. In low load areas, the injector is used with a longer pulse width, making it possible to supply a stable air-fuel mixture with a single injection valve.

As is clear from the above description, according to the present invention, when the load applied to the engine is small, the fuel pressure applied to the injector is lowered and the injection pulse width is lengthened by that amount. This injector has the excellent effect of supplying a stable air-fuel mixture.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a system using the present invention, Fig. 2 is a sectional view of the carburetor main body, Fig. 3 is a particle size characteristic diagram of fuel, and Fig. 4 is a fuel pressure of the pressure regulator with a regulator solenoid in the present invention. Characteristic diagram, Figure 5 is a flow rate characteristic diagram of the injector, Figure 6 is a flowchart showing a control example of the present invention, Figure 7 is a system configuration diagram showing another embodiment, and Figure 8 is a pressure injector with double diaphragm. FIG. 9 is a characteristic diagram of the fuel pressure of the regulator, FIG. 9 is a characteristic diagram of the intake pressure correction coefficient, and FIG. 10 is a flowchart showing another control example of the present invention. 1... FI converter, 2-... Air flow sensor, 3...
- Injector, 4... Rotation sensor, 5... Water temperature sensor, 6... Control unit, 7... Phenyl damper, 8... Phenyl pump, 9... Pressure regulator, 56... Intake pressure sensor, 17...
・Intake pipe temperature sensor, 18...Pressure regulator with double diaphragm ・Kaya 3 eyes E 1 arrangement ↑ 8 answers (pull 5) $4-E O/'z+'L, iJ, Suba J) 71 in class
(乍s) 1 Ishi Otsu Giant D Figure 8 $? Figure (person λ million 9 ri U [pressure i
(Sedυho 10 fig.

Claims (1)

[Claims] 1. Detects the intake air amount and engine rotation speed of the engine, and supplies nine fuels according to the detected air amount! A fuel injection device for an internal combustion engine equipped with a magnetically operated injector, characterized in that the fuel injection device for an internal combustion engine is provided with a control means that detects a load applied to the carrot and reduces the fuel pressure applied to the injector when the load is small. Injection device. 2. Claim 1, characterized in that when the injection pulse width calculated based on the intake air amount and the engine speed is smaller than a predetermined value, the load is detected as being small.
A fuel injection device for an internal combustion engine according to paragraph 1. & A patent claim characterized in that the fuel pressure is changed by detecting that the load is small based on the intake pressure of the engine, and the differential pressure between the fuel inlet of the injector and the injection port is reduced as the degree of vacuum in the intake pipe increases. A fuel injection device for an internal combustion engine according to item 1.