JPH0364697B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides a method for controlling the supply of air flow near the nozzle hole of a fuel injection valve in order to promote atomization of fuel injected from the fuel injection valve. The present invention relates to a preferred engine fuel supply system.

(Prior Art) In an engine equipped with a fuel injection valve, an air flow is supplied near the injection hole of the fuel injection valve in order to promote atomization of the fuel injected into the intake passage from the injection hole. There is something like this. For example, in the device disclosed in Japanese Patent Application Laid-Open No. 57-153935,
It has a configuration in which intake air is directly introduced from an intake passage portion on the upstream side of the throttle valve into the injection hole of the fuel injection valve disposed on the intake downstream side with respect to the throttle valve,
The atomization of the injected fuel is promoted by utilizing the air flow formed by the differential pressure of the intake air generated between the upstream and downstream sides of the throttle valve.

On the other hand, engines that use fuel injection valves to supply fuel have two fuel injection valves for each cylinder, and one at low load when the amount of intake air is small.
There is a fuel supply system that uses only one injector and uses both injectors to inject fuel at high loads when the amount of intake air is large. Also in such a device, it is preferable to supply the above-mentioned air flow for promoting fuel atomization to each injection valve.

(Problem to be Solved by the Invention) However, as described above, the method of introducing airflow using the intake air pressure difference between upstream and downstream of the throttle valve does not allow the throttle valve to operate at high loads with a large amount of intake air. Since the valve is fully open, the differential pressure of the intake air decreases, making it impossible to introduce sufficient airflow into the nozzle hole of the injection valve. Therefore, promotion of atomization of the injected fuel cannot be expected. In addition, simply forming an air passage from the intake upstream side for each injection valve will introduce unnecessary air flow to the side of the injection valve that is not being driven, and it will be supplied into the intake passage. I end up.
As a result, the amount of air supplied increases when the vehicle is idling, and control under such operating conditions is not performed properly.

Therefore, it is conceivable to perform control such that the supply of airflow to the fuel injection valve is cut off when the fuel injection valve is not being driven, and the supply of airflow is started when the fuel injection valve starts to be driven. However, with this control, when the drive of the fuel injection valve is started, there is a delay in the supply of airflow, and there is a risk that the atomization of the fuel will be insufficient.

The present invention has been made in view of the problems of the prior art, and provides an air flow to both fuel injection valves to promote atomization of the fuel injected therefrom. The purpose of this invention is to provide a fuel supply system for a fuel-efficient engine.

(Means for Solving the Problems) The configuration of the present invention will be described with reference to FIG.
The fuel supply control device for an engine according to the present invention includes a first fuel injection valve 1 and a second fuel injection valve 3, and in a first operating region where the amount of intake air is equal to or less than a predetermined value, the first fuel injection valve 1, and in a second operating region other than the first operating region, both the first and second fuel injection valves 1, 3 are driven to perform fuel injection, the injected fuel a first air flow forming means 7 that forms an air flow for promoting atomization using the differential pressure between upstream and downstream air across the throttle valve in the intake passage 5; and an air pump that forms the air flow. Second air flow forming means 9
and a first detection means 11 for detecting that the operating state of the engine is in a low intake air amount region including idling in the first operating region, and a first detecting means 11 that detects that the operating state of the engine is in the low intake air amount region including idling in the first operating region; Based on the detection outputs of the second detection means 13 and the first and second detection means, which detect that the region is in the high intake air amount region including the high load region, the operating state is determined to be at least the above-mentioned state. When in the low intake air amount region, the air flow formed by the first air flow forming means is supplied only to the first fuel injection valve, and when the operating state is at least in the high intake air amount region, The air flow formed by the second air flow forming means is supplied to the first and second fuel injection valves, and the operating state of at least the second fuel injection valve is within the first operation region and outside the low intake air amount region. The present invention is characterized in that it includes a supply control means 15 for supplying an air flow from either the first or second air flow forming means to the second device injection valve when the air flow is in a region adjacent to the operating region.

(Function) In the device of the present invention configured as described above,
The supply of the air flow for atomizing the injected fuel to the first fuel injection valve 1, which is constantly driven, is controlled as follows. First, the low intake air volume area including the idle area,
In areas other than the high intake air amount area, the airflow formed by the first airflow forming means 7 using the intake air pressure difference is supplied to the vicinity of the nozzle hole of the first fuel injection valve 1. The opening degree of the throttle valve increases, the intake air differential pressure decreases, and the operating state shifts to an operating region where fuel atomization cannot be expected by introducing the air flow by the air flow forming means 7, that is, a high intake air amount region. After that, the introduction of the air flow is forcibly carried out by the second air flow forming means 9 instead of the first air flow forming means 7. The optimal timing for this switching is determined individually for each engine.

On the other hand, the air flow for atomizing the injected fuel is supplied to the second fuel injection valve 3 as follows. First, in the low intake air amount region, no air flow is supplied to this second fuel injection valve. However, at least in a high intake air amount region including times of high load, the second air flow forming means 9 forcibly supplies the air flow, and this air flow promotes atomization of the injected fuel. Furthermore, when the operating state is within the first operating region and in a region adjacent to at least the second operating region outside the low intake air amount region, the second fuel injector is provided with either the first or second air flow forming means. Since the air flow is supplied from above, the air flow is supplied to the second fuel injection valve without delaying the fuel injection.

(Effects of the Invention) As explained above, the fuel injection device for an engine of the present invention has a configuration capable of supplying an air flow for promoting atomization of injected fuel to each fuel injection valve, and also In operating regions where the intake air flow is small, airflow is forcibly supplied regardless of this intake differential pressure, and in operating regions where the intake air amount is small, such as during idling, the intake differential pressure is used to supply airflow to the drive-side injector. Air flow is supplied, and unnecessary air flow is not supplied to injection valves on the unused side. Therefore, according to the present invention, it is possible to promote atomization of the injected fuel even in an operating region where the intake air differential pressure is small, and at the same time, during idling, the amount of intake air increases due to the supply of unnecessary airflow. You can also avoid the negative effects of doing so. Further, according to the present invention, even when the operating state shifts from an operating range in which the second fuel injector is not driven to an operating range in which the second fuel injector is driven, the fuel atomization is applied to the second fuel injector. airflow can be supplied without delay. As a result, the problem of insufficient fuel atomization is solved.

(Example) Examples of the present invention will be described below with reference to the drawings.

FIG. 2 shows the overall configuration of an embodiment of the present invention. In the figure, an intake passage 25 that introduces intake air into the combustion chamber 23 in the engine body 21 includes:
An air cleaner 27, an air flow meter 29, and a throttle valve 31 are arranged in this order from the upstream side. In the passage between the throttle valve 31 and the intake valve 33 in the intake passage 25, a first fuel injection valve 35 is arranged on the intake valve side, and a second fuel injection valve 37 is arranged on the throttle valve 31 side. It is located. Fuel is supplied to these fuel injection valves via a fuel supply passage comprised of a fuel tank 39, a fuel pump 41, a fuel filter 43, a pressure regulator 45, and the like.

The injection valves 35 and 37 are provided with means for supplying an air flow for promoting atomization of the injected fuel downstream of the injection holes 35a and 37a. Specifically, a passage 47 communicates with the injection hole 35a of the first fuel injection valve 35, and this passage communicates with the outlet port 4 of the electromagnetic control valve 49.
It is connected to 9a. This control valve 4
The first inlet port 49b of 9 communicates with the outlet port of the air pump 53 via the passage 51. The second inlet port 49c of the control valve 49 communicates with an air passage near the upstream side of the throttle valve 31 via a passage 55. Here, when the control valve 49 is off, the second inlet port 49c and the outlet port 49a communicate with each other, and when it is on, the first inlet port 49b communicates with the second inlet port 49c.
and the outlet port 49a are in communication with each other. On the other hand, a passage 57 communicates with the injection hole 37a of the second fuel injection valve 37, and this passage 57 is connected to the outlet port 59a of the electromagnetic second control valve 59.
is connected to. The inlet port 59b of this control valve 59 communicates with the above-mentioned passage 47 via a passage 61. Here, this control valve 59 is designed to open when it is turned on. Note that an air control valve 63 for adjusting the air pressure discharged from the air pump is disposed in the passage 51 communicating with the air pump 53 described above.

Next, 65 is a control unit composed of a 1-chip microcomputer, and its output port 65a outputs drive signals for the above-mentioned injection valves, control valves, etc., and its input port 65b is connected to the engine. Detection signals such as engine rotational speed N, intake pipe internal pressure P, throttle valve opening Θ, and intake air amount Q, which is the output of an air flow meter, indicating the operating state are supplied. A control program shown in FIG. 4, which will be described later, is stored in the ROM of the control unit 65, and both control valves 49 and 59 are controlled according to the detected engine operating state according to this program.

Here, before explaining the operation of this embodiment, the third
The air flow supply control mode achieved by this embodiment will be described with reference to the graph shown in the figure. In the figure, a solid line A indicates the drive start timing of the second fuel injection valve 37, and in the region of high load and high rotation, fuel injection is performed from both injection valves 35 and 37.
In other areas, fuel injection is performed only by the first fuel injection valve 35. On the other hand, a broken line B indicates the timing at which the supply of air flow to the first fuel injection valve 35 is switched to forced supply by the air pump 53 as described later. Therefore, in areas where the load is higher and the rotational speed is higher than this, airflow is forcibly supplied, and in other areas, airflow is supplied using the intake pressure differential. Further, a dashed-dotted line C indicates the timing at which the forced supply of airflow to the second fuel injection valve 37 is started. Airflow is forcibly supplied in the region on the high-load, high-speed side of this line, and no airflow is supplied in other regions. Furthermore, dashed line B
In the area surrounded by and dashed line C, the second
An air flow is supplied to the fuel injection valve 37 by the intake air pressure differential. In addition, in this example, fuel acceleration increase control is also performed, and during this control, air flow is always forcibly supplied to the first fuel injection valve 35 by the air pump 53.

Next, air flow supply control in this example will be explained according to the flowchart of FIG. First, step
In ST1, parameters indicating the operating state of the engine, such as engine speed N, intake pipe pressure P, throttle valve opening Θ, and intake air amount Q, are read. In step ST2, the acceleration state is detected from the rate of change in the throttle valve opening Θ, and when the acceleration state shifts to an acceleration state in which fuel acceleration increase control is performed, an acceleration switch (not shown) is turned on. set to state.

Next, the routine from step ST3 to step ST7 is a control routine for determining whether or not to forcibly supply airflow to the first fuel injection valve 35. That is, in step ST3, the state of the acceleration switch is determined, and if it is on, the process moves to step ST6 following the flow of "YES", and the first control valve 49 is turned on. When the acceleration switch is off, the engine advances along the flow of "NO", and in step ST4 it is determined whether the engine load (intake pipe pressure) P is greater than or equal to the value P1, and in step ST5, the engine speed N is set to the value N1. It is determined whether or not the value is greater than or equal to the value. Step only if both steps are positive
Proceed to ST6. In other words, the operating state in this case corresponds to the area shown in FIG. In other cases (in the area shown in FIG. 3), the process proceeds to step ST7, and the control valve 49 is turned off. Here,
When the control valve 49 is turned on, the inlet port 49b and the first outlet port 49a of the control valve 49 are turned on.
The air flow discharged from the air pump 53 is supplied to the nozzle hole of the first fuel injection valve 35.
On the other hand, when the control valve 49 is turned off,
The inlet port 49b and the second outlet port 49c communicate with each other, and an air flow is supplied to the nozzle hole of the first fuel injection valve 35 due to the intake pressure difference generated between the upstream and downstream sides of the throttle valve 31. Become.

Next, the routine from step ST8 to step ST11 is a control routine for determining whether or not to supply air flow to the second fuel injection valve 37.
That is, in step ST8, it is determined whether the engine speed N is greater than or equal to the value N1, and step ST8 is performed.
In ST9, it is determined whether the operating state determined by the engine speed N and the throttle valve opening Θ is in a region on the high-load, high-speed side of the deceleration line (see FIG. 3). Only in the case of positive judgments in both steps (area in Figure 3), step ST
10, the second control valve 59 is turned on. As a result, the injection hole of the second fuel injection valve 37 is filled with air due to the intake pressure difference or the air pump 5.
Air flow is provided by 3. That is, when the valve 49 is on (the area surrounded by the broken line B and the dashed line C in FIG. 3), the air flow is directly supplied from the upstream side of the throttle valve due to the intake air pressure difference, and the valve 49 is turned on. When is on (area shown in Figure 3)
is supplied with air flow from an air pump 53.
If a negative determination is made in step ST8 or ST9 (area in FIG. 3), step ST1
1, and the second control valve 59 is turned off. As a result, the supply of airflow to the injection hole of the second fuel injection valve 37 is stopped.

Although not shown in the flowchart, the control unit 65 also controls the injection drive of both the injection valves 35 and 37 in addition to the above-mentioned air flow supply control, and in the operating state falling within the region shown in FIG.
Fuel is injected from both injection valves, and in an operating state that falls within the range, only the first fuel injection valve 35 injects fuel.

As mentioned above, in this example, the first fuel injector 35 is operated in the operating region where a sufficient airflow can be supplied by the intake air pressure differential, as shown in the region in FIG. An air flow for promoting atomization is supplied using the intake pressure difference, and in the operating region after this air flow is no longer sufficiently supplied,
Since the air flow is forcibly supplied by the air pump 53, it can be expected that the atomization of the injected fuel will always be promoted. Further, the supply of air flow to the second fuel injection valve 37 is started after the second fuel injection valve 37 enters the operating state (region) before shifting to the region in which it is driven. Therefore, an air flow for promoting atomization can be supplied without the amount of intake air increasing unnecessarily during idling, and without causing a delay in the start of fuel injection from this injector. Furthermore, in this example, since the air flow is supplied by the air pump even during acceleration increase control, atomization of the injected fuel can be promoted during such increase control.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of the present invention.
Fig. 2 is an overall configuration diagram showing an embodiment of the present invention, Fig. 3 is a characteristic diagram showing a mode of supply control by the device in Fig. 2, and Fig. 4 is a flowchart showing the control operation of the device in Fig. 2. It's a chat. DESCRIPTION OF SYMBOLS 1...First fuel injection valve, 3...Second fuel injection valve, 5...First air supply passage, 7...Second air supply passage, 9...Intake passage, 11...Air flow formation mechanism, 13... Air pump, 15... First detection means, 17... Second detection means, 19... Supply control means.

Claims (1)

[Claims] 1. A fuel injection valve comprising a first fuel injection valve and a second fuel injection valve,
In a first operating region where the amount of intake air is equal to or less than a predetermined value, only the first fuel injection valve is driven to perform fuel injection, and in a second operating region other than the first operating region, the first and second fuels are injected. In an engine fuel injection system that injects fuel by driving both injection valves, an air flow that promotes atomization of the injected fuel is created by using the differential pressure between the upstream and downstream windings across the throttle valve in the intake passage. a first air flow forming means for forming the air flow using an air pump; and a second air flow forming means for forming the air flow using an air pump; The first step is to detect that it is in the amount region.
a detection means, a second detection means for detecting that the operating state of the engine is in a high intake air amount region including a high load region within the second operation region, and the first and second detection means; Based on the detection output of the means, when the operating state is at least in the low intake air amount region, the air flow formed by the first air flow forming means is supplied only to the first fuel injection valve; When the state is at least in the high intake air amount region, the air flow formed by the second air flow forming means is supplied to the first and second fuel injection valves, and the operating state is in the first operation region. supply control for supplying airflow from either of the first and second airflow forming means to the second device injection valve when the airflow is in a region outside the low intake air amount region and adjacent to at least the second operation region; 1. A fuel supply device for an engine, comprising: means.