JPH0833138B2 - Electronically controlled fuel injection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electronically controlled fuel injection device for an internal combustion engine,
In particular, the present invention relates to an electronically controlled fuel injection device in which the output timing of a drive pulse signal to a fuel injection valve provided for each cylinder can be switched according to the engine operating state.

<Prior Art> The sequential injection (sequential injection) method described in Japanese Patent Application Laid-Open No. 57-8328 can supply a mixture of fuel and air to each cylinder. There is no variation in combustion between cylinders,
It has advantages such as small torque fluctuation.

By the way, in an electronically controlled fuel injection device using a microcomputer in recent years, in the one adopting the sequential injection method, a microcomputer calculates a fuel injection amount according to an operating state of the engine, and the calculated fuel injection is performed. A drive pulse signal having a pulse width corresponding to the amount is distributed from one output terminal of a microcomputer to a fuel injection valve of each cylinder via a drive circuit and supplied, so that during high speed / high load operation Since it is necessary to continuously output the drive pulse signal of each cylinder with a short pulse width and a large pulse width to each fuel injection valve, the pulses overlap each other and the drive pulse signal corresponding to the required fuel injection amount for each cylinder is generated. It becomes impossible to distribute and supply.

Therefore, the speed is high enough to cause overlap between the pulses of the drive pulse signal output from the microcomputer. During high-load operation, as shown in FIG. 5, the drive pulse signal is simultaneously output to the fuel injection valves of all cylinders to switch to the method of injecting all cylinders at the same time. A drive pulse signal having a pulse width can be output.

<Problems to be Solved by the Invention> However, as described above, when the sequential injection system is switched to the all-cylinder simultaneous injection system, there are cylinders in which the air-fuel ratio becomes lean at the time of switching, and due to this, torque fluctuations cause switching shock. There was a problem that occurs.

That is, for example, when the injection timing of the # 2 cylinder in the sequential injection system is switched to the simultaneous injection in all cylinders as shown in FIG. The pulse width of the drive pulse signal by the cylinder simultaneous injection method is 1/2 of the required injection amount
Is set so that the injected fuel for two injections is sucked into each cylinder, so the amount of fuel supplied to the # 1 cylinder at the time of switching becomes 1/2 of the required amount (in the all-cylinder simultaneous injection system, The air-fuel mixture is formed by only one drive pulse signal), and the air-fuel ratio of the air-fuel mixture in the # 1 cylinder becomes over lean. Further, in order to satisfy the required fuel amount in the # 1 cylinder, if the first injection amount of all cylinders simultaneous injection is set to the required fuel amount in the # 1 cylinder, the air-fuel ratio of the # 2 cylinder becomes overrich and misfires occur. There is a risk of switching shock.

The present invention has been made in view of the above problems, and avoids the occurrence of cylinders in which the air-fuel ratio becomes over lean when switching from the sequential injection system to the all-cylinder simultaneous injection system, and operates when switching the injection system. The purpose is to prevent the occurrence of shock.

<Means for Solving Problems> Therefore, in the present invention, as shown in FIG. 1, the fuel injection amount is calculated according to the engine operating state, and the pulse width corresponding to the calculated fuel injection amount is provided. Electronically controlled fuel injection for an internal combustion engine configured to output a driving pulse signal to a fuel injection valve provided for each cylinder of the engine at a predetermined timing to drive the fuel injection valve and inject fuel to the engine. In the device, a sequential injection control unit that outputs the drive pulse signal in synchronization with the intake stroke of each cylinder, and an all-cylinder simultaneous injection control unit that outputs the drive pulse signal to all the fuel injection valves of all the cylinders at the same time. ,
Injection control switching means for selectively operating the sequential injection control means and the all-cylinder simultaneous injection control means based on the operating state of the engine, and the sequential injection control means for all-cylinder simultaneous injection control by the injection control switching means. At the time of switching to the means, simultaneously with respect to each fuel injection valve of one cylinder group of the cylinder groups divided into two according to the injection order by the sequential injection control means, the timing corresponding to the sequential injection control means and A drive pulse signal having a pulse width is output, and at the subsequent injection timing by the sequential injection control means, a drive pulse signal having a pulse width corresponding to the all-cylinder simultaneous injection control means is simultaneously supplied to each fuel injection valve of the other cylinder group. After outputting, the all-cylinder simultaneous injection control means is operated. Loop injection control means, and so comprises a.

<Operation> According to such a configuration, in the configuration in which the sequential injection and the all-cylinder simultaneous injection are switched based on the engine operating state, when the sequential injection is switched to the all-cylinder simultaneous injection, the group injection is performed once. The group injection is performed once for each cylinder group at the timing of sequential injection, and the cylinder group to be injected first uses the injection pulse width of sequential injection, and the cylinder group to be injected next has all cylinders. This is performed by using the injection pulse width of the simultaneous injection, and the group injection control eliminates the cylinder in which the air-fuel ratio becomes over lean and buffers the change of the injection control method.

<Example> An example of the present invention will be described below with reference to the drawings.

In FIG. 2, the 4-cylinder internal combustion engine 1 has an air cleaner.
Air is sucked through the intake duct 3, the throttle chamber 4, the intake manifold 5, and the intake valve 6.

The throttle chamber 4 is provided with a throttle valve 7 interlocking with an accelerator pedal (not shown) to control the intake air flow rate Q.

The intake manifold 5 (or intake port) is provided with a fuel injection valve 8 for each cylinder. This fuel injection valve 8
Is an electromagnetic fuel injection valve that energizes the solenoid to open the valve and deenergizes it to close the valve. The fuel regulated to a predetermined pressure by the pressure regulator is supplied to the engine 1
To be injected.

The control unit 9 receives input signals from various sensors, performs arithmetic processing as described later by a built-in microcomputer, determines a fuel injection amount (injection time) Ti and an injection timing (injection method), and follows this. And outputs a drive pulse signal to the fuel injection valve 8.

That is, in this embodiment, the control unit 9
Serves as a sequential injection control means, a group injection control means, an all-cylinder simultaneous injection control means, and an injection control switching means.

As the various sensors, a hot-wire type air flow meter 10 is provided in the intake duct 3, and the intake air flow rate Q
The signal corresponding to is output. Further, a crank angle sensor 11 is provided in a distributor (not shown) and outputs a unit signal for every 2 ° of crank angle and a reference signal for every 180 ° (in the case of 4 cylinders). Therefore, four reference signals are output at a crank angle of 720 °, one of which is
One can be distinguished from the other, and based on this, each reference signal can be specified for the stroke of each cylinder, and the number of input of the unit signal per unit time can be counted or the input cycle of the reference signal can be determined. The rotational speed N of the engine 1 is detected by measuring.

Further, a potentiometer type throttle sensor 12 is provided on the throttle valve 7 and outputs a signal according to the opening α of the throttle valve 7. Further, a water temperature sensor 13 is provided in the water jacket of the engine 1 to cool the cooling water temperature.
Output the signal according to Tw. Further, the voltage of the battery 14 is applied to the control unit 9 via the engine key switch 15 as its operating power source and for detecting the power source voltage VB.

In the present embodiment, the engine operating state for calculating the fuel injection amount Ti is the intake air flow rate Q, the engine speed N, the throttle valve opening α, the cooling water temperature Tw and the battery voltage detected by the above-mentioned sensors. VB is equivalent.

Next, fuel injection control by the microcomputer in the control unit 9 will be described with reference to the injection control routine shown in the flowchart of FIG. 3 and the time chart of FIG. The injection control routine shown in FIG. 3 is executed each time the crank angle sensor 11 outputs a reference signal.

First, in step (denoted as "S" in the drawing, the same applies hereinafter) 1, the intake air flow rate Q, the engine speed N, the throttle valve opening α, the cooling water temperature Tw, and the battery 14 detected by various sensors. Input the voltage (power supply voltage) VB.

In step 2, the basic fuel injection amount Tp (← K is calculated according to the intake air flow rate Q and the engine speed N input in step 1.
× Q / N; K is a constant) is calculated.

In step 3, various correction coefficients COEF are set by the coolant temperature Tw representing the engine temperature input in step 1 and the throttle valve opening α indicating the acceleration / deceleration operation or idle operation of the engine 1.

In step 4, the effective injection amount Te (← Tp × COEF) is calculated by the basic fuel injection amount Tp calculated in step 2 and the various correction coefficients COEF set in step 3.

In step 5, the voltage correction amount Ts is set by the voltage (power supply voltage) VB of the battery 14 input in step 1. The voltage correction amount Ts is for correcting the change in the effective valve opening time of the fuel injection valve 8 due to the change in the battery voltage VB.

In step 6, the effective injection amount Te calculated in step 4
And the correction amount Ts set in step 5 and the fuel injection amount Ti (← 2T
e + Ts).

In step 7, the fuel injection amount Ti set in step 6
That is, the injection time is converted into a crank angle based on the current engine rotation speed N input in step 1.

In step 8, the fuel injection amount Ti converted to the crank angle
And a predetermined reference angle (<180 °) are compared to determine whether the current operating state of the engine 1 is a high-speed / high-load operating state in which the injection method should be switched to the all-cylinder simultaneous injection method. To do.

Here, when it is determined that the fuel injection amount Ti converted into the crank angle is equal to or greater than the reference angle, the engine 1 is in the high-speed / high-load operating state, and the drive pulse signal of each cylinder having a large pulse width continues in a short cycle. Output (or a state where pulses overlap each other),
Since it is impossible or is becoming impossible to distribute and supply the drive pulse signal to the fuel injection valve 8 of each cylinder, the process proceeds to step 14 and the injection method is switched to perform the fuel injection control. To do so.

On the other hand, when it is determined that the fuel injection amount Ti converted into the crank angle is less than the reference angle, the drive pulse signal is distributed from one output terminal of the microcomputer to the fuel injection valve 8 of each cylinder via the drive circuit. Since the supply can be performed with a margin, the process proceeds to step 9 in order to perform the injection control by the normal sequential injection method.

In step 9, the fuel injection amount Ti (← 2Te + Ts) corresponding to the sequential injection method is set.

In step 10, based on the reference signal output from the crank angle sensor 11, the cylinder to be in the intake stroke when the next reference signal is input is determined.

Then, the fuel injection valve 8 provided in this intake stroke cylinder
On the other hand, in the next step 11, a drive pulse signal having a pulse width corresponding to the fuel injection amount Ti set in step 9 is output.

In step 12, the cylinders that have output the drive pulse signal in step 11 are sequentially updated and stored, and are used to determine the injection group at the time of starting injection control by the group injection method described later.

In step 13, when the injection control is performed by the group injection method and the all-cylinder simultaneous injection method, and then returns to the sequential injection method, various flags are reset to reset the injection control by the group injection method and the all-cylinder simultaneous injection method. Set to zero.

On the other hand, in step 8, the fuel injection amount converted into the crank angle
When it is determined that Ti is equal to or greater than the reference angle and the process proceeds to step 14, the switching flag is determined.

Since this switching flag is set to zero in the above-mentioned step 13, the zero determination is made in the first switching from the sequential injection method, and the routine proceeds to step 15 to perform the injection control by the group injection method.

In step 15, a group flag for controlling grouped injection in injection control by the group injection method is determined. Since this group flag is also set to zero in the above-mentioned step 13 like the above-mentioned switching flag, the zero determination is made at the first switching from the sequential injection system, and the routine proceeds to step 16.

In step 16, the fuel injection amount Ti (← 2Te + Ts) in the first group injection is set, and in the next step 17, the drive pulse signal having the pulse width corresponding to this fuel injection amount Ti is sequentially set as shown in FIG. The fuel is output to the fuel injection valves 8 of the first group at the injection timing. In this embodiment, the engine 1 has four cylinders, and the injection order in the sequential injection is # 1 → # 3 → # 4 → # as shown in FIG.
2, the first group refers to a cylinder group according to the sequential injection order that does not include the cylinder stored in step 12 described above. That is, as shown in FIG. 4, when the last injection of the sequential injection method is performed in the # 2 cylinder and the cylinder stored in step 12 is the # 2 cylinder, this # 2 cylinder is not included. The group consisting of the # 1 cylinder and the # 3 cylinder is the first group.

When the first group injection is performed in step 17, by setting the group flag to 1 in the next step 18,
Next time, in step 15, it is determined that the group flag is 1, and the routine proceeds to step 19, where the second group injection is performed.

In step 19, the fuel injection amount Ti (← Te + Ts) in the second group injection is set.

Then, in the next step 20, a drive pulse signal having a pulse width corresponding to this fuel injection amount Ti is output, and in the above step 17, the drive pulse signal is not output.
Group (Group # 2 and # 4 in Figure 4)
As shown in FIG. 4, it is output at the timing of sequential injection following the first group injection.

In step 21, the group flag set to 1 in step 18 is set to 0 again, and in the next step 22, the switching flag is set to 1 in order to execute the injection control by the all-cylinder simultaneous injection method from the next time.

In this way, when the fuel injection supply by the group injection system is performed to all the cylinders and the switching flag is set to 1, next step proceeds from step 14 to step 23 and the injection control by the all cylinders simultaneous injection system is performed.

In step 23, the fuel injection amount Ti (← Te + Ts) corresponding to the all cylinders simultaneous injection method is set.

In step 24, the simultaneous flag is judged. This simultaneous flag is for executing all-cylinder simultaneous injection for every one revolution of the engine 1 (every 360 ° of crank angle), and the simultaneous flag is zero in step 24 (switch to all-cylinder simultaneous injection control). At the first time, since the flag is set to zero in step 13, the simultaneous flag is zero), the process proceeds to step 25 and corresponds to the fuel injection amount Ti (← Te + Ts) set in step 23. A drive pulse signal having a pulse width is simultaneously output to the fuel injection valves 8 of all cylinders.

When the drive pulse signal is output, the simultaneous flag is set to 1 in the next step 26, so that the next time, the injection control will be performed by the all-cylinder simultaneous injection method. If the quantity Ti is equal to or greater than the reference angle), then step 24 to step 27
To proceed to. Then, in step 27, the simultaneous flag is set to zero and the drive pulse signal is not output, and the process is returned as it is, so that the crank angle is 180 °.
The drive pulse signal is simultaneously output to all the cylinders once every two times in this routine executed every time.

In this way, when the injection control is performed by the group injection method when the injection method is switched from the sequential injection method to the all-cylinder simultaneous injection method, for example, as shown in FIG. In the intake stroke of each cylinder at the beginning of the injection system, the air-fuel ratio does not become over lean (the fuel injection amount Ti becomes less than 2Te + Ts), and the air-fuel ratio becomes over lean when switching the injection system. It is possible to prevent the occurrence of driving shock due to torque fluctuation.

<Effects of the Invention> As described above, according to the present invention, when the sequential injection system is switched to the all-cylinder simultaneous injection system, it is possible to efficiently switch the injection system without generating a cylinder in which the air-fuel ratio becomes over lean. Therefore, there is an effect that the occurrence of a driving shock at the time of switching the injection method can be avoided.

[Brief description of drawings]

FIG. 1 is a block diagram of the present invention, FIG. 2 is a system diagram showing an embodiment of the present invention, FIG. 3 is a flowchart showing injection control in the same embodiment, and FIG. 4 is injection control in the same embodiment. FIG. 5 is a time chart for explaining, and FIG. 5 is a time chart for explaining problems of conventional control. 1 ... Engine, 8 ... Fuel injection valve, 9 ... Control unit, 10 ... Air flow meter, 11 ... Crank angle sensor, 12 ... Throttle sensor, 13 ... Water temperature sensor, 14
……Battery

Claims (1)

[Claims] 1. A fuel injection amount is calculated according to an engine operating state, and a drive pulse signal having a pulse width corresponding to the calculated fuel injection amount is given to a fuel injection valve provided for each cylinder of the engine. In an electronically controlled fuel injection device for an internal combustion engine configured to output the fuel at a timing to drive the fuel injection valve to inject and supply fuel to the engine, the drive pulse signal is timed to the intake stroke of each cylinder. , A simultaneous injection control means for simultaneously outputting the drive pulse signals to all the fuel injection valves of all cylinders, and a sequential injection control means and the simultaneous injection for all cylinders based on the operating state of the engine. Injection control switching means for selectively operating the injection control means, and the sequential injection control means by the injection control switching means for all cylinders When switching to the simultaneous injection control means,
A drive pulse signal having a timing and a pulse width corresponding to the sequential injection control means at the same time for each fuel injection valve of one of the cylinder groups divided into two according to the injection order by the sequential injection control means. At the injection timing by the sequential injection control means, and then simultaneously outputs a drive pulse signal having a pulse width corresponding to the all-cylinder simultaneous injection control means to each fuel injection valve of the other cylinder group, and then all the cylinders. An electronically controlled fuel injection device for an internal combustion engine, comprising: group injection control means for operating the simultaneous injection control means.