JPH0116986B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection method and device for a fuel supply system in which fuel is injected into an intake passage from an air cleaner to an engine inlet, mixed with intake air, and supplied to the engine.

Conventionally, electromagnetic injection valves have been used as means for injecting fuel into the intake passage, and the opening/closing time ratio of the injection valve, which is repeated at regular intervals, is varied depending on the engine operating condition to achieve the optimal amount required by the engine. Fuel is supplied to cover the fuel requirements over the entire operating range of the engine. However, there is a limit to the opening/closing time ratio of an injector driven by a solenoid, and if a large flow of fuel can be supplied, fuel consumption is low, such as during idling, and therefore injection is performed in a region where the valve opening time is extremely short. The valve does not respond accurately and the fuel supply becomes unstable. On the other hand, if a small flow rate of fuel is stably supplied, the amount of fuel supplied will be insufficient in areas where fuel consumption is large, such as under high load, due to insufficient capacity of the injector.

The present invention uses both an injection system that supplies an amount of fuel controlled by an injection valve and an injection system that supplies a constant amount of fuel metered by a fixed orifice, so that the injection system can be used over the entire operating range of the engine. This makes it possible to accurately and stably inject the required fuel into the intake passage.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an air cleaner, 2 is a throttle body, 3 is an intake manifold, 4 is an engine, 7 is a fuel tank, 8 is a filter 9, a fuel pump 10, and a regulator. a fuel passage having 11;
3 indicates an injection system having an injection valve 14; 16 indicates an injection system having three fixed orifices 17, 20, 23 in parallel; It branches from the passage 8 and injects pressurized fuel into the intake passage 6 on the upstream side of the throttle valve 5. The fixed orifices 17, 20, 23 each have on-off valves 18, 21, 24 on the upstream side, and the injection valve 1
Solenoid 15 that drives 4, on-off valves 18, 2
Solenoids 19 and 2 that open and close 1 and 24 separately
2, 25 and the prime mover 12 of the fuel pump 10 are operated by a drive signal current sent from an electronic control unit 26. The electronic control unit 26 inputs signal currents from detectors that detect the throttle valve opening, intake air amount, intake air temperature, engine temperature, engine speed, exhaust composition, and other operating conditions of the engine 4, and determines the optimum amount of current. A drive signal current is generated so that fuel is supplied.

The injection valve 14 is designed to respond accurately in low fuel consumption areas such as idling, and the fuel consumption of the engine 4 is less than the maximum supply amount of the injection valve 14 (Fig. 3A). In this region, a controlled amount of fuel is injected into the intake passage 6 only from the injection valve 14 . When the fuel consumption approaches the maximum supply amount of the injection valve 14, the first on-off valve 18 opens and a certain amount of fuel (FIG. 3B) metered by the first fixed orifice 17 is inhaled from the nozzle 27. The injected fuel is injected into the fuel passage 6, and the injector 14 compensates for the shortfall in fuel amount required by the engine. As the fuel consumption increases, the second and third on-off valves 21 and 24 open in sequence, and the first and second fixed orifices 17,
Fuel metered at 20 (FIG. 3C) and fuel metered at three fixed orifices 17, 20, 23 (FIG. 3D) are injected into the intake passage 6 from the nozzle 27. In these cases as well, the injector 14 compensates for the shortfall in fuel amount required by the engine.

FIG. 2 shows a different embodiment of the present invention, in which on-off valves 18, 21, 24 are provided downstream of three fixed orifices 17, 20, 23, and separate nozzles 28, 29, 30 are installed in the intake passage 6. It was opened to Also in this embodiment, FIG.
Fuel injection similar to that in FIG. 3 is performed.

Note that the fixed orifices 17, 20, and 23 may also be used as nozzles to face the intake passage 6, and the injection system that supplies a certain amount of fuel may be configured with only one fixed orifice. By arranging more than one in parallel and increasing the injection amount sequentially as fuel consumption increases, the small capacity injection valve 14 that can stably supply a small amount of fuel can be used to finely compensate for the shortage and provide accurate fuel supply. It can be performed. In this case, fixed orifice 1 is opened first.
The effective cross-sectional area of the fuel injection valve 7 is set so as to measure a slightly smaller amount of fuel than the maximum supply amount of the injection valve 14. Alternatively, two or more fixed orifices may be opened at the same time. Furthermore, the injection valve 1
4 is driven by a solenoid 15 and the fuel control is performed by changing the opening/closing time ratio that is repeated at regular intervals. Instead, it is driven by a step motor and the valve opening is changed virtually steplessly from zero to the maximum. In some cases, fuel control may also be carried out.

As described above, the present invention includes an injection system having an injection valve that injects controlled fuel into the intake passage, and an injection system having a fixed orifice that injects a certain amount of fuel into the intake passage, thereby reducing fuel consumption. When the amount is below a certain level, fuel is supplied by an injection system with an injector, so a small-capacity injector that can be accurately controlled in a small flow area is used to reduce fuel consumption during idling, etc. This allows stable fuel supply in the operating range where there is little fuel. In addition, in operating ranges where fuel consumption is high, a fixed amount of fuel is supplied from the injection system with a fixed orifice, and fuel controlled by the injection valve is also supplied at the same time, so there is a significant shortage with small-capacity injection valves. The fixed orifice can almost satisfy the amount of fuel required by the fixed orifice, and the injector can compensate for the amount of fuel required by the engine that is insufficient from the fixed orifice alone, allowing the injector to operate within a stable operating range. It is possible to accurately supply the engine's required fuel without excess or deficiency.

Furthermore, according to the present invention, since a plurality of fixed orifices are provided in parallel, the effective cross-sectional area of these orifices is set appropriately and by opening them sequentially or two or more at once, fuel can be consumed in accordance with the increase in fuel consumption. By increasing the amount of fuel in stages by a certain amount, the required amount of fuel can be stably delivered even in regions where fuel consumption is extremely high, such as in high-load, high-speed operating regions, without significantly increasing the amount of fuel injected from the injection valve.

[Brief explanation of drawings]

Figure 1 is a system diagram showing an embodiment of the present invention, Figure 2 is a system diagram showing an embodiment of the present invention;
The figures are partial system diagrams showing different embodiments, and FIG. 3 is a characteristic curve diagram. 6...Intake path, 8...Fuel passage, 10...Fuel pump, 13...Injection system, 14...Fuel pump,
16...Injection system, 17,20,23...Fixed orifice, 18,21,24...Opening/closing valve.

Claims (1)

[Claims] 1. When fuel is injected into the intake passage, mixed with intake air, and supplied to the engine, when the fuel consumption is less than a certain amount, the fuel controlled by the injection valve is injected into the intake passage, A fuel injection method characterized by injecting a fixed amount of fuel measured by a fixed orifice and fuel controlled by an injection valve into the intake passage when the fuel consumption exceeds a certain level. 2. In parallel, an injection system has an injection valve that injects fuel into the intake passage, and an injection system that has a fixed orifice that injects a certain amount of fuel into the intake passage and an on-off valve installed either before or after the orifice. A fuel injection device characterized by: 3 An injection system having an injection valve that injects fuel into the intake passage, an injection system having a fixed orifice that injects a certain amount of fuel into the intake passage, and an on-off valve provided either before or after the orifice in parallel, and further A fuel injection device characterized in that a plurality of sets of fixed orifices and on-off valves are provided in parallel.