JPH0137584B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a fuel injection device for an engine.

(Prior art) Two intake passages are provided for each cylinder of the engine, and a fuel injection valve is arranged in each intake passage.
The intake air amount is controlled by opening and closing throttle valves installed in each intake passage according to the engine load and other operating conditions, and the amount of fuel injected from each fuel injection valve is controlled. Fuel is injected in the entire operating range, including the low intake air volume range, and fuel is injected from the second injection valve in the high intake air volume range, providing highly accurate fuel supply control from low load ranges to high load ranges. For example, the fuel injection device that made it possible to realize
No. 51-12025.

In the above-mentioned fuel injection device, if a large amount of fuel is injected under high load using a single fuel injection valve, the accuracy will decrease when injecting a small amount of fuel under low load, whereas low flow rate While injecting fuel in the low load range with the first injector, which has good supply accuracy in the low load range,
In a high flow rate region that cannot be supplied by the first injection valve, fuel is also injected from the second injection valve. Therefore, as in the preceding example, the start timing of fuel injection from the second injector corresponds to the magnitude of the fuel injection amount (fuel injection pulse width) calculated according to the operating state of the engine, and this calculated injection In the case where fuel is also injected from the second injection valve when the amount exceeds a set value, the second injection is performed before the second intake passage for the high flow rate range is opened by the second throttle valve. This has the problem that fuel is injected from the valve.

In other words, for example, when the engine is cold, in order to increase the fuel injection amount relative to the intake air volume and obtain good warm-up performance, a cold-time correction is performed to increase the calculated injection amount, and at the same time, the engine speed is increased when the engine is cold. In order to do this, the amount of air intake is increased. and,
In the above correction, although the actual operating state of the engine is the amount of fuel injected only by the first injector, if the calculated injection amount based on the detection of engine temperature and intake air amount exceeds the set value, fuel is injected also from the second injector. It may be an area where

Therefore, in this case, fuel is injected from the second injection valve even though the second throttle valve is not opened, and this fuel does not flow into the combustion chamber but accumulates in the intake passage. There is a risk that a predetermined amount of fuel may not be supplied to the combustion chamber, resulting in a misfire, and there are also problems that result in atomization of the fuel and worsening of mixing.

(Object of the Invention) In view of the above circumstances, the present invention provides that even if the calculated injection amount increases due to cold correction etc., the second intake passage
When the throttle valve is not opened, the second injection valve does not inject fuel, and only the first injection valve injects fuel into the first intake passage, regardless of the magnitude of the calculated injection amount. It is an object of the present invention to provide a fuel injection device for an engine as described above.

(Structure of the Invention) The fuel injection device for an engine of the present invention includes a first intake passage that supplies intake air to each cylinder in all operating ranges including a low intake air amount range, and a first intake passage that supplies intake air in a high intake air amount range to each cylinder. 2 intake passages are connected, the first intake passage is provided with a first injection valve and a first throttle valve, and the second intake passage is provided with a second injection valve and a second throttle valve, and the intake air amount is detected. The fuel injection amount calculating means calculates the fuel injection amount according to the intake air amount detected by the means, and the injection valve operating means drives the first injection valve when the injection amount calculated by the fuel injection amount calculating means is less than a set value; When this calculated injection amount exceeds a set value, the first and second injection valves are driven, and in a region where the second throttle valve is closed with respect to this injection valve actuating means, the calculated injection amount exceeds the set value. The present invention is characterized by comprising a second injection valve stopping means for stopping the operation of the second injection valve even if the second injection valve is exceeded.

The above-mentioned second injection valve stopping means may be one that increases the setting value for starting fuel injection from the second injection valve when the second injection valve is cold, or one that detects the opening degree of the second injection valve and starts the second injection when the valve is closed. A type with a non-operating valve is adopted.

(Effects of the Invention) According to the present invention, the first injector performs fuel injection with high precision in the low intake air amount range, and at the appropriate time in the high intake air amount area where the calculated injection amount exceeds the set value. While fuel atomization is promoted by injecting fuel from the second injection valve as well, if the calculated injection amount exceeds a predetermined value due to cold correction etc. Even if the size is large enough to inject fuel, fuel injection from the second injector is not performed in the area where the second throttle valve of the second intake passage where the second injector is installed is closed. Furthermore, it is possible to prevent fuel injection into an intake passage where there is no intake air, perform accurate fuel injection corresponding to the operating condition, and ensure good ignitability and combustibility.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Example 1 This example is shown in FIGS.
The figure is an overall configuration diagram, in which two first and second intake ports 3 and 4 are open to the combustion chamber 2 of each cylinder of the engine 1, and two first and second exhaust ports 5 and 6 are open, respectively. It's open.

An intake passage 7 for supplying intake air is connected to the intake ports 3 and 4. This intake passage 7 has an air cleaner 8 at the upstream end, and an intake air amount detection means 9 (air flow meter) for detecting the intake air amount is installed downstream of this air cleaner 8, and downstream from this intake air amount detection means 9. The side intake passage 7 is branched into a first intake passage 7a and a second intake passage 7b. The first intake passage 7a is connected to the first intake port 3 of each combustion chamber 2 via an expansion chamber 7c, while the second intake passage 7b is connected to the second intake port of each combustion chamber 2 via an expansion chamber 7d. 4 are connected to each other.

A first throttle valve 10 for controlling the amount of intake air flowing through the first intake passage 7a is provided at the entrance of the first intake passage 7a, and a first throttle valve 10 is provided at the entrance of the second intake passage 7b. A second throttle valve 11 is provided to control the amount of intake air flowing through the second intake passage 7b, and both throttle valves 10 and 11 are opened and closed in conjunction with throttle operation. The first throttle valve 10 opens when the load is low and becomes fully open as the load increases,
The second throttle valve 11 begins to open when the first throttle valve 10 reaches a set opening or more, and becomes fully open as the load increases.

The first intake passage 7a is provided with a first injection valve 12 for each cylinder, which injects fuel in all operating ranges including the low intake air amount range, and the second intake passage 7b is provided with a high intake air amount. A second injection valve 13 that injects fuel in a quantity range is provided for each cylinder. These first and second injection valves 12, 13
A fuel injection pulse is output as a fuel control signal from the control unit 14 (microcomputer), and a predetermined amount of fuel is injected according to the width of the injection pulse.

Further, the intake passage 7 is provided with a bypass passage 15 that bypasses the first throttle valve 10, and a bypass control valve 16 for controlling the amount of bypass air is interposed in the middle of this bypass passage 15. Reference numeral 16 is a linear solenoid 16a whose opening degree is adjusted by the operation of a linear solenoid 16a based on a control signal from the control unit 14, and controls such that the amount of bypass air increases as the engine temperature (cooling water temperature) decreases. .

The control unit 14 receives an intake air amount signal from the intake air amount detection means 9, an engine rotation speed signal from the rotation speed sensor 17, and an engine cooling water temperature signal from the water temperature sensor 18.

This control unit 14 calculates the fuel injection amount and timing (injection number) corresponding to the operating state including cold time correction according to the outputs of the intake air amount detection means 9, the rotation speed sensor 17, and the water temperature sensor 18. Based on the fuel injection amount calculating means 19 and the calculated injection amount (injection pulse width) by this fuel injection amount calculating means 19, when this calculated injection amount is less than a set value, an injection pulse is output to the first injection valve 12 to drive it. and an injection valve operating means 20 that outputs an injection pulse to the first and second injection valves 12 and 13 to drive them when the set value is exceeded, and the water temperature sensor 1.
8, when the engine is cold, the set value of the injection valve operating means 20 is increased in accordance with the cold increase, the injection start timing of the second injection valve 13 is delayed, and at least the second throttle valve 11 is closed. The second injection valve stop means 21 stops the injection operation from the second injection valve 13 in the area where the engine temperature is lower based on the output of the water temperature sensor 18,
The linear solenoid 1 sends a control signal to open the bypass control valve 16 of No. 5 to increase the amount of bypass air.
6a.

The fuel injection control by the control unit 14 is performed as shown in FIG.
In the relationship between the intake air amount Qa and the intake air amount Qa, when the temperature is warm, the area below the setting curve A is the first injector 12.
and the area is the first and second injection area.
This is the injection area by the injection valves 12 and 13. This setting curve A approximately corresponds to the valve opening curve of the second throttle valve 11, and in the low intake air amount region, the first injection valve 12
When the intake air amount Qa, that is, the fuel injection amount reaches a set value (set value of injection pulse width), fuel injection by the second injector 13 is started, and when it is cold, the dashed line As shown in , this setting curve B is set to a high value, and even if the fuel injection amount increases, the start of injection by the second injector 13 is delayed, so that the amount of fuel increases during cold conditions and the amount of bypass air increases. The second throttle valve 11 before opening operation
This prevents the fuel injection valve 13 from injecting fuel.

FIG. 3 is a flowchart for explaining the operation of the control unit 14. After starting, the water temperature signal from the water temperature sensor 18 is input in step S1, and the fuel injection amount corresponding to the operating condition is calculated in step S2. The fuel injection pulse width τ (injection time) is determined from the intake air amount Qa detected by the intake air amount detection means 9, the engine rotation speed N detected by the rotation speed sensor 17, the constant K, the correction coefficient α, etc.
seek. Note that the correction coefficient α is for correcting and increasing the amount during cold periods, etc., and the additional correction value τo is for correcting the amount of fuel actually injected even if the fuel injection pulse is output to the first or second injection valve 12, 13. This is to correct the rise time since it takes a certain amount of time for the start of the rise. Further, τa is the basic injection time taking into account cold correction, etc., and τb is the acceleration increase time.

Subsequently, the bypass control valve 16 is activated depending on the cooling water temperature t.
The control amount is read (S3), and the linear solenoid 16a of the bypass control valve 16 is driven in accordance with this control amount (S4). Further, the set pulse width τv for starting the injection of the second injection valve 13 is read out (S5), and it is determined whether the injection pulse width τa + τb as the calculated injection amount in step S2 is greater than or equal to the set pulse width τv (S6); When this judgment is NO (low injection amount region), it is judged whether the asynchronous acceleration switch is on (S7), and when the asynchronous acceleration switch is on (YES) and the engine is in a large acceleration state, step S8 is performed.
On the other hand, when this asynchronous acceleration switch is off (NO), the injection pulse τp for the first injection valve 12 and the injection pulse τs for the second injection valve 13 are calculated without performing the asynchronous injection. (S9). In the above-mentioned low injection amount region, the injection pulse τs for the second injection valve 13 is set to zero;
without injecting fuel from the injection valve 13.
The first injector 1 is controlled by the control signal of the injection pulse width τp determined in step S2 only by the injector 12.
2 to perform fuel injection (S13).

On the other hand, if the determination in step S6 is YES and the injection amount is in the high injection amount region, it is similarly determined whether the asynchronous acceleration switch is on (S10), and if the asynchronous acceleration switch is on (YES) and the injection is in a large acceleration state, While performing asynchronous injection in step S11, when the asynchronous acceleration switch is off (NO), the injection pulse τp for the first injection valve 12 and the injection pulse τs for the second injection valve 13 are calculated without performing the asynchronous injection. (S12), and the first and second injection valves 12, 13 are driven by this control signal to perform fuel injection (S13). In this example, the first injection valve 12 and the second injection valve 13 are set to inject the same amount (half each) of fuel.

At this time, the value of the set value τv read out in step S5 is set to have the characteristics as shown in FIG. That is, when the cooling water temperature t detected by the water temperature sensor 18 is lower than the warm-up completion temperature to, a large set value τv is read out, and when it exceeds it, a small set value τv is read out.

In the above fuel injection, the output of injection pulses τp and τs when performing asynchronous injection in the high injection amount region is
The result will be as shown in the figure.

Embodiment 2 In this embodiment, the overall configuration is shown in FIG. 6, and the flowchart is shown in FIG. 7. In this example, instead of detecting the cooling water temperature, the opening degree of the second throttle valve 11 is directly detected by the throttle sensor 23, and this detection signal is output to the second injection valve stopping means 21 of the control unit 14. Even when the fuel injection amount calculated by the fuel injection amount calculation means 19 according to the operating state of the engine exceeds the set value in the injection valve actuation means 20, the signal indicating that the second throttle valve 11 is closed indicates that the second injection is performed. When the valve stop means 21 is outputting, it outputs a control signal to stop the operation of the second injection valve 13 and cause the first injection valve 12 to inject the entire calculated injection amount. The rest is provided in the same manner as in the previous example, and the same structures as those in FIG.

FIG. 7 is a flowchart showing the operation of the control unit 14 of this example to obtain the above characteristics. After the start, in step S1, the fuel injection amount corresponding to the operating condition is calculated, and the intake air amount is calculated. Intake air amount Qa detected by detection means 9, engine rotation speed N detected by rotation speed sensor 17, constant K,
The fuel injection pulse width τ is determined from the correction coefficient α and the like. Next, the set pulse width τv for starting fuel injection from the second injection valve 13 is read out (S2), and the step
It is determined whether the injection pulse width τa + τb calculated in S1 is greater than or equal to the set pulse width τv (S3), and when this determination is NO (low injection amount region), it is determined whether the asynchronous acceleration switch is on (S4), When the asynchronous acceleration switch is turned on (YES) and there is a large acceleration state, asynchronous injection is performed in step S5, while this asynchronous acceleration switch is turned off (NO).
In this case, the injection pulse τp for the first injection valve 12 and the injection pulse τs for the second injection valve 13 are calculated without performing asynchronous injection (S6). In the low injection amount region, the injection pulse τs for the second injection valve 13 is set to zero, and the step S1 is performed only by the first injection valve 12 without injecting fuel from the second injection valve 13. The first injection valve 12 is driven to perform fuel injection using the control signal having the injection pulse width τp determined in (S11).

On the other hand, in the high injection amount region, the judgment in step S3 above is
If YES, it is determined in step S7 whether or not the second throttle valve 11 is open based on the signal from the throttle sensor 23, and if it is closed (NO), the process advances from step S4 to S6 and the second injector valve 13 is opened.
will not operate. The judgment in step S7 above is
When the second throttle valve 11 is open with YES,
Determine whether the asynchronous acceleration switch is on (S8), and if the asynchronous acceleration switch is on (YES) and is in a large acceleration state, step S9
On the other hand, when the asynchronous acceleration switch is off (NO), the asynchronous injection is not performed and the injection pulse τp for the first injection valve 12 and the injection pulse τs for the second injection valve 13 are This injection pulse is used to control the first and second injection valves 1.
2 and 13 to perform fuel injection (S11). In this example, the acceleration increase correction τb is such that the entire amount is injected by the first injection valve 12.

As explained above, even when the calculated injection amount (injection pulse width τa + τb) exceeds the set value τv,
When the second throttle valve 11 is closed, fuel injection by the second injection valve 13 is not performed.

In the above embodiment, as shown in FIG. 1, the first injector 12 is disposed in the downstream portion of the first intake passage 7a relatively close to the combustion chamber 2, and the first injector 12 injects air. The fuel is quickly supplied to the combustion chamber 2 to improve the responsiveness of the fuel to increases and decreases in the amount of intake air, and on the other hand,
The second injection valve 13 is disposed in the second intake passage 7b on the upstream side of the first injection valve 12 to improve mixing and atomization of the injected fuel and intake air, thereby promoting atomization. It is.

In addition, the first throttle valve 10 that controls the amount of intake air flowing through the first intake passage 7a is provided at the entrance of the first intake passage 7a as shown in FIG.
A similar control effect can be obtained even if the intake passage 7 is provided in the intake passage 7 on the more upstream side.

Furthermore, in the above embodiment, two intake ports connected to the intake passages are opened independently in the combustion chamber of each cylinder, and each is opened and closed by an intake valve, but a single intake port is opened, The intake passage connected to this may be divided into a plurality of intake passages.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an engine fuel injection device according to a first embodiment of the present invention, and FIG. 2 is a control of the injection region of an injector in relation to the engine speed and intake air amount in the first embodiment. FIG. 3 is a flowchart of the control unit in the first embodiment. FIG. 4 is an explanatory diagram showing an example of the fuel injection pulse output to the injection valve according to FIG. 3. Fig. 5 is an explanatory diagram showing the characteristics of the set value with respect to the cooling water temperature in Fig. 3, Fig. 6 is a schematic configuration diagram of the engine fuel injection device in the second embodiment, and Fig. 7 is a control diagram in the second embodiment. FIG. 3 is a flowchart of the unit. DESCRIPTION OF SYMBOLS 1... Engine, 2... Combustion chamber, 3, 4... Intake port, 7... Intake passage, 7a... First intake passage, 7b... Second intake passage, 9... Intake air amount detection means, 10...First throttle valve, 11...Second throttle valve, 12...First injection valve, 13...Second injection valve,
14...Control unit, 18...Water temperature sensor, 19...Fuel injection amount calculation means, 20...
Injection valve operating means, 21... second injection valve stopping means,
23...Throttle sensor.

Claims (1)

[Claims] 1 A first intake passage that supplies intake air to each cylinder in all operating ranges including a low intake air volume range, a second intake passage that supplies intake air in a high intake air volume range, and a first intake passage provided in the first intake passage. an injection valve, a second injection valve provided in the second intake passage, a first throttle valve that controls the amount of intake air in the first intake passage, a second throttle valve that controls the amount of intake air in the second intake passage; intake air amount detection means for detecting the intake air amount; a fuel injection amount calculation means for calculating the fuel injection amount according to the output of the intake air amount detection means; and when the injection amount calculated by the fuel injection amount calculation means is less than a set value. an injection valve operating means that drives the first injection valve and drives the first and second injection valves when the calculated injection amount exceeds a set value; 2. A fuel injection device for an engine, comprising: second injection valve stopping means for stopping operation of the second injection valve in a region where the calculated injection amount exceeds a set value.