JPH0519030B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an interrupt injection control device for an electronically controlled fuel injection type internal combustion engine.

<Prior Art> Conventionally, electronically controlled fuel injection type internal combustion engines include the following, for example.

That is, the basic fuel injection amount Tp is determined from the intake air flow rate Q detected by an air flow meter etc. and the engine rotation speed N detected by a crank angle sensor etc.
(=K×Q/N; K is a constant), and
After calculating various correction coefficients COEF according to engine operating conditions such as cooling water temperature Tw and correction amount Ts due to battery voltage, fuel injection amount Ti (= Tp × COEF +
Ts). Then, a drive pulse signal with a pulse width corresponding to the fuel injection amount Ti is output at a predetermined timing to the electromagnetic fuel injection valve provided for each cylinder, so that a predetermined amount of fuel is injected and supplied to the engine. ing.

By the way, in order to compensate for the delay in fuel supply during acceleration, so-called interrupt injection is performed in which fuel is injected in advance of normal fuel injection to improve responsiveness during acceleration (Japanese Patent Laid-Open No. 1983-1999). (See No. 081187, etc.)

Specifically, the opening degree α of the throttle valve installed in the intake passage of the engine is detected, and when the throttle valve is opened at a predetermined rate or more from an idle state (throttle valve fully closed state), the engine is accelerated. (ON at idle position of throttle valve)
This acceleration detection may be performed by turning the idle switch ON → OFF), and the interrupt injection amount T _ioj is set based on the rate of change Δα of the throttle valve opening α detected at the time of this acceleration determination. Interrupt injection amount
An interrupt drive pulse signal having a pulse width corresponding to the interrupt injection amount T _ioj (some models have this interrupt injection amount T _ioj as a constant value) is output at the same time as the acceleration is detected.

Here, there is a method in which the interrupt drive pulse signal is output to all fuel injection valves provided for each cylinder at the same time as acceleration is detected, and a method in which the interrupt drive pulse signal is outputted to all the fuel injection valves provided for each cylinder, and a method in which the interrupt drive pulse signal is output only to the fuel injection valves of the cylinder that is in the intake stroke at the time of acceleration detection. Interrupt injection is performed by two methods: the method of outputting the interrupt drive pulse signal and the method of outputting the interrupt drive pulse signal.

<Problems to be Solved by the Invention> By the way, according to the above-mentioned method of simultaneously performing interrupt injection for all cylinders, when the throttle valve is slightly opened by slightly operating the accelerator when the engine is fully warmed up, However, even when the throttle valve is opened from fully closed to fully open by greatly operating the accelerator, interrupt injection will be performed on all cylinders, so for example, pressing the accelerator pedal slightly will immediately return the throttle valve. When you perform an operation like this,
As shown in FIG. 5, the air-fuel ratio became overrich, causing afterburn and overrich misfires.

On the other hand, with a method in which interrupt injection is performed only in cylinders that are in the intake process when acceleration is detected, the above problems are unlikely to occur because interrupt injection is only performed in specific cylinders, but there may be a delay in fuel supply when the engine is cold. When this is large, as shown in FIG. 6, the air-fuel ratio becomes over-lean in the cylinder that undergoes the intake stroke after the cylinder in which the interrupt injection is performed, causing a problem in that a shock occurs at the beginning of acceleration.

The present invention has been made in view of the above problems, and it is an object of the present invention to enable optimal interrupt injection to be performed without being affected by engine temperature.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. a fuel injection amount setting means for setting the amount;
An electronically controlled fuel injection type internal combustion engine comprising: drive pulse signal output means for outputting a drive pulse signal corresponding to the set fuel injection amount to an electromagnetic fuel injection valve provided for each cylinder. , an engine acceleration state detection means for detecting the acceleration state of the engine, an engine temperature detection means for detecting the engine temperature, and an interrupt drive corresponding to a predetermined interrupt injection amount for all fuel injection valves at the same time as acceleration detection. a first interrupt drive pulse signal output means for outputting a pulse signal; and an interrupt drive pulse signal corresponding to a predetermined interrupt injection amount only to the fuel injection valve corresponding to the cylinder that is in the intake stroke at the same time as acceleration is detected; When the engine temperature detected by the second interrupt drive pulse signal output means and the engine temperature detection means is below a predetermined temperature, the first interrupt drive pulse signal output means is operated to exceed the predetermined temperature. An interrupt output switching means for operating the second interrupt drive pulse signal output means when necessary, constitutes an interrupt injection control device.

<Operation> According to this interrupt injection control device, when the engine temperature is below a predetermined temperature, the first interrupt drive pulse signal output means is operated, and interrupt injection is performed to all cylinders simultaneously with acceleration detection. On the other hand, when the engine temperature exceeds the predetermined temperature, the second interrupt drive pulse signal output means is operated, and interrupt injection is performed only in the cylinder that is in the intake stroke at the time of acceleration detection.

That is, the interrupt injection for all cylinders and the interrupt injection for cylinders in the intake stroke are switched depending on the engine temperature.

<Example> An example of the present invention will be described below based on the drawings.

In FIG. 2, an engine rotational speed signal N is the output of the rotational speed sensor 1, an engine intake air flow rate signal Q is the output of the airflow meter 2, and a water temperature sensor 3.
The engine cooling water temperature signal Tw, which is the output of the engine, and the throttle valve installed in the engine intake passage (not shown)
The throttle valve opening signal α, which is the output of the throttle valve opening sensor 7 attached to the throttle valve opening sensor 7, is input to the control unit 4 having a built-in microcomputer, and the control unit 4 is set as described below based on these signals. A drive pulse signal and an interrupt drive pulse signal are output to the drive circuit 6 of the electromagnetic fuel injection valve 5.

That is, as shown in the flowcharts of FIGS. 3 and 4, the control unit 4 includes fuel injection amount setting means, drive pulse signal output means, first and second interrupt drive pulse signal output means, and interrupt output. It also serves as a switching means, and together with the throttle valve opening sensor 7, constitutes an engine acceleration state detecting means. Further, the engine operating state detection means in this embodiment corresponds to the rotational speed sensor 1, the air flow meter 2, and the water temperature sensor 3, and the water temperature sensor 3 also corresponds to the engine temperature detection means.

Next, normal fuel injection control will be explained according to the fuel injection control routine shown in the flowchart of FIG.

In step 1 (indicated as "S" in the figure, the same applies hereinafter), the engine rotation speed N, intake air flow rate Q, and cooling water temperature detected by each sensor are
Enter Tw.

Then, in the next step 2, a basic fuel injection amount Tp (=K×Q/N; K is a constant) is calculated based on the engine rotational speed N and intake air flow rate Q input in step 1.

In step 3, various correction coefficients COEF are set mainly based on the cooling water temperature Tw input in step 1.

Furthermore, in step 4, a correction amount Ts is set for correcting a change in the effective valve opening time of the fuel injection valve 5 due to battery voltage.

Then, in step 5, the above steps 2 to 4 are performed.
The final fuel injection amount Ti (=
Tp×COEF+Ts) is calculated, and in step 6, a drive pulse signal with a pulse width corresponding to this fuel injection amount Ti is outputted to each fuel injection valve 5 in time with the intake stroke of each cylinder.

Next, the interrupt injection control will be explained according to the interrupt injection control routine shown in the flowchart of FIG.

In step 11, the throttle valve opening α detected by the throttle valve opening sensor 7 and the cooling water temperature Tw detected by the water temperature sensor 3 are input.

In step 12, the throttle valve opening change rate Δα per execution cycle of this routine is calculated from the throttle valve opening α input this time in step 11 and the previous input value.

In step 13, the opening change rate Δα calculated in step 12 is compared with a predetermined value Δα ₁ , and if the calculation result Δα in step 12 is greater than or equal to the predetermined value Δα ₁ , it is determined that the engine is in an accelerating state. Proceeding to step 14, if the calculation result Δα in step 12 is less than the predetermined value _Δα1 , it is determined that the engine is not in an accelerating state, and the process returns directly. That is, when the throttle valve is opened at a rate greater than a predetermined rate, it is determined that the engine is in an accelerated state.

When it is determined in step 13 that the engine is in an accelerating state and the process proceeds to step 14, it is determined whether or not this acceleration determination is the first time. Note that this initial acceleration judgment is performed when the throttle valve is fully closed (idle position).
This can also be done using an idle switch that turns ON.

Then, only when it is determined that the acceleration determination is the first time, the process proceeds to step 15 and the interrupt injection amount T _ioj is set.

In step 15, the throttle valve opening change rate Δα
(This rate of change Δα indicates the speed of acceleration) The interrupt injection amount T _ioj is set in advance based on the calculation result in step 12.

In step 16, the coolant temperature Tw input in step 11 is compared with the predetermined temperature _Tw1 , and if the current coolant temperature Tw is less than the predetermined temperature _Tw1 , which is a so-called cold engine, the process advances to step 19 and the temperature is changed for each cylinder. An interrupt drive pulse signal having a pulse width corresponding to the interrupt injection amount T _ioj is output to all the fuel injection valves 5 provided in the interrupt injection valve 5 .

On the other hand, if it is determined in step 16 that the cooling water temperature Tw is equal to or higher than the predetermined temperature Tw ₁ and the engine is not in a cold state, the process proceeds to step 17 to determine which cylinder is currently in the intake stroke, and in step 18 this determination is performed. An interrupt drive pulse signal having a pulse width corresponding to the interrupt injection amount T _ioj is output to the fuel injection valve 5 provided in the cylinder in the intake stroke. That is, in step 18, interruption injection is performed only in the cylinder in the intake stroke, and interruption injection is not performed in other cylinders.

In this way, by performing interrupt injection for all cylinders when the engine is cold, it is possible to prevent the air-fuel ratio from becoming over lean in all cylinders in such an operating state where there is a large delay in fuel supply.
In addition, since interrupt injection is performed only for cylinders that are in the intake process when the engine is not cold, there is no need for more interrupt injection than is necessary, such as when the throttle valve is opened by slightly operating the accelerator. , it is possible to avoid enrichment of the air-fuel ratio.

In other words, when the engine is cold and there is a large fuel supply delay, interrupt injection may be performed only in the cylinder that is in the intake process.
Since there is a risk that the air-fuel ratio may become over-lean due to fuel shortage in the cylinders that will undergo the intake stroke after that, interrupt injection is performed for all cylinders, except during cold engine conditions when fuel supply is relatively smooth. In order to avoid excessive fuel supply due to interruption, interruption injection is performed only to cylinders in the intake stroke.

Therefore, according to this embodiment, it is possible to prevent the occurrence of an acceleration shock due to an over lean air-fuel ratio when the engine is cold, and even if the throttle valve is slightly opened in a fully warmed state, the injection amount can be maintained by interrupt injection. This prevents the occurrence of afterburn from becoming excessive.

<Effects of the Invention> As explained above, according to the present invention, the interrupt injection for all cylinders and the interrupt injection for the cylinders in the intake stroke are switched depending on the engine temperature. This makes it possible to control the air-fuel ratio to a desired value by avoiding excess or deficiency in the amount of interrupt injection, thereby improving the operability of the engine.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of the present invention, Fig. 2 is a system block diagram showing an embodiment of the present invention, Fig. 3 is a flowchart showing fuel injection control in the above embodiment, and Fig. 4 is a system block diagram showing an embodiment of the invention. Flowchart showing interrupt injection control, Figure 5 is a time chart to explain the problems in the all-cylinder simultaneous interrupt method, and Figure 6 is a time chart to explain the problems in the intake stroke cylinder interrupt method. It is. 1...Rotation speed sensor, 2...Air flow meter,
3...Water temperature sensor, 4...Control unit, 5
...Fuel injection valve, 6... Drive circuit, 7... Throttle valve opening sensor.

Claims (1)

[Claims] 1 Engine operating state detection means for detecting the operating state of the engine, fuel injection amount setting means for setting the fuel injection amount based on the detected engine operating state, and a drive pulse corresponding to the set fuel injection amount. Drive pulse signal output means for outputting a signal to an electromagnetic fuel injection valve provided for each cylinder; and engine acceleration state detection means for detecting an acceleration state of the engine in an electronically controlled fuel injection type internal combustion engine. , an engine temperature detection means for detecting engine temperature, and a first interrupt drive pulse signal output means for outputting an interrupt drive pulse signal corresponding to a predetermined interrupt injection amount to all fuel injection valves simultaneously with acceleration detection. a second interrupt drive pulse signal output means for outputting an interrupt drive pulse signal corresponding to a predetermined interrupt injection amount only to the fuel injection valve corresponding to the cylinder in the intake stroke at the same time as the acceleration is detected; interrupt output switching means that operates the first interrupt drive pulse signal output means when the engine temperature is below a predetermined temperature and operates the second interrupt drive pulse signal output means when the engine temperature exceeds the predetermined temperature; An interrupt injection control device for an electronically controlled fuel injection type internal combustion engine, comprising: