JPH08505Y2 - Electronically controlled fuel injection system for multi-cylinder 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 a multi-cylinder internal combustion engine that includes a fuel injection valve for each cylinder.

<Prior Art> The following is a conventional example of an electronically controlled fuel injection device for a multi-cylinder internal combustion engine.

That is, the basic injection amount T _P (= K) is calculated from the intake air flow rate Q detected by the air flow meter and the engine rotation speed N.
・ Q / N: K is a constant) and after calculating various correction coefficients COEF mainly according to the water temperature, the air-fuel ratio feedback correction coefficient α, and the correction coefficient T _S based on the battery voltage, the fuel injection amount T _i ( = T _P × COEF × α + T _S ) is calculated.

Then, in synchronization with a reference signal or the like from the crank angle sensor, a control device including a microcomputer or the like outputs an injection pulse signal having a pulse width corresponding to the fuel injection amount T _i to each fuel injection valve to output fuel to the engine. Supply.

Specifically, as shown in FIG. 7, the control device includes a crank angle sensor, the number of which is the same as the number of cylinders and is set at a predetermined crank angle (for example, in a four-cylinder internal combustion engine, the crank angle is 180 degrees).
Every °). Here, for example, the pulse width of the reference signal corresponding to the # 1 cylinder (hereinafter referred to as the cylinder discrimination reference signal) is formed longer than the pulse width of the reference signal corresponding to the other cylinders.

When the cylinder discrimination signal is input,
It is determined to be one cylinder, and thereafter, for each input of each reference signal, the cylinder to be injected is determined according to a preset injection order (similar to the ignition order).

Then, as shown in FIG. 7, for each input of each reference signal,
The injection start timing is set based on the fuel injection amount T _i so that the injection end timing is always at a substantially constant crank angle position in synchronization with the intake stroke. A position signal (for example, a crank angle of 2 ° from the time of inputting each reference signal)
Every time) or based on the count value of the timer, each fuel injection valve is operated at the timing of the set injection start timing (a ₁ , b _1, etc. in FIG. 7).

<Problems to be Solved by the Invention> However, in such a conventional electronically controlled fuel injection device, the injection start timing is set when the reference signal corresponding to each cylinder is input. There was a problem.

That is, for example, when the fuel injection amount of the # 3 cylinder becomes extremely large, the injection start timing becomes earlier than the injection start timing of the previous injection cylinder (here, the # 2 cylinder), as indicated by C ₁ in FIG. 7. . However, when the reference signal corresponding to the # 3 cylinder is input, the cylinder is discriminated and the fuel injection valve of the # 3 cylinder is operated, so the actual injection start timing is C _{2 in} FIG. The actual amount of fuel injected to the engine is greatly insufficient (hatched portion in FIG. 7), which may cause misfire.
For example, in an exhaust manifold of each bank of a V-type engine equipped with an oxygen concentration sensor that detects the actual air-fuel ratio from the oxygen concentration in the exhaust gas, the actual air-fuel ratio of each bank may differ greatly. It was easy to occur because of it.

The present invention has been made in view of the above circumstances, and provides an electronically controlled fuel injection device capable of operating a fuel injection valve at the injection start timing of each cylinder even if the fuel injection amount of each cylinder greatly differs. To aim.

<Means for Solving Problems> For this reason, the present invention is provided with the fuel injection valves A _{1 to} A _n for each cylinder of the engine as shown in FIG. _1, while the predetermined reference signal is synchronized with the engine rotation. In which the same predetermined reference signal is input according to the set fuel injection amount and the fuel injection amount setting unit C that sets the fuel injection amount according to the engine operating state. To the injection start timing for each cylinder, the injection start timing setting means D, the time measuring means E for measuring the time, the time measured from the time when the predetermined reference signal is input, and the set injection start timing. Means F for selecting a cylinder to be injection-controlled based on
And drive control means G for driving and controlling the fuel injection valves A _{1 to} A _n of the selected cylinders.

<Operation> Then, while setting the injection start timing of each cylinder with the same predetermined reference signal as a reference, select the cylinder to be injection-controlled based on the set injection start timing and the measured time,
The fuel injection valve of the cylinder is drive-controlled.

<Embodiment> An embodiment of the present invention will be described below with reference to FIGS. In this embodiment, a V-type 4-cylinder internal combustion engine will be described as an example.

In FIG. 2, electromagnetic fuel injection valves 2a to 2d are attached to intake ports of each cylinder of the engine 1.
The driving of 2a to 2d is controlled by a control signal from a control device 3 including a microcomputer or the like.

A first oxygen concentration sensor 5 that detects the actual air-fuel ratio by detecting the oxygen concentration in the exhaust gas is provided at the collecting portion of the first exhaust manifold 4 that is connected to the exhaust port of one bank. ing. A second oxygen concentration sensor 7 having the same function as that of the first oxygen concentration sensor 5 is provided at the collecting portion of the second exhaust manifold 6 which is connected to the exhaust port of the other bank. The detection signals of the first and second oxygen concentration sensors 4 and 6 are input to the control device 3. In addition, the control device 3 includes an engine rotation speed signal detected by a rotation speed sensor (not shown), an intake air flow rate signal detected by an air flow meter (not shown), and a water temperature sensor (not shown). The detected cooling water temperature signal and are input. Further, a reference signal is input to the control device 3 from the crank angle sensor 8 as a reference signal output means at every crank angle of 180 °, and the pulse width of the reference signal corresponding to the # 1 cylinder among the reference signals is different. The reference signal for cylinder discrimination is set longer than that of the cylinder.

The control device 3 operates according to the flow charts of FIGS. 3 to 5, and drives and controls each of the fuel injection valves 2a to 2d at a predetermined timing described later. Further, the control device 3 is provided with a timer (not shown) as a time counting means that is reset when the cylinder discrimination reference signal is input and starts time counting in association with the number of cylinders.

Here, the control device 3 constitutes a fuel injection amount setting means, an injection start timing setting means, and a drive control means.

 Incidentally, 9 and 10 are catalyst devices for purifying exhaust gas.

Next, the operation will be described with reference to the flowcharts of FIGS.

First, the flowchart of FIG. 3 will be described. It should be noted that this routine is started when a cylinder discrimination reference signal (corresponding to the # 1 cylinder, every 720 ° in crank angle) is input.

In S1, the detection signals from the first and second oxygen concentration sensors 5, 7, etc. are read.

In S2, the fuel injection amount T _i is calculated for each cylinder.

Specifically, based on the intake air flow rate Q detected by the air flow meter and the engine rotation speed N, the basic injection amount T _P (= K
・ Q / N; K is a constant) and various correction factors COEF and the first and second oxygen concentration sensors 5, which mainly correspond to the water temperature,
After calculating the air-fuel ratio feedback correction coefficient α based on the detected air-fuel ratio of 7 and the correction coefficient T _S based on the battery voltage, the fuel injection amount T _i (= T _P × COEF × α + T _S ) is calculated.

In S3, the injection start timing from the input of the cylinder discrimination reference signal is set for each cylinder based on the fuel injection amount T _i calculated for each cylinder in S2.

Specifically, the crank angle from the input of the cylinder discrimination reference signal to the start of the intake stroke (corresponding to the end of injection) of each cylinder can be set in advance as shown in A to D in FIG. As a result, the crank angle (A to D in FIG. 6) from when the reference signal for cylinder discrimination is input to immediately before the intake stroke of each cylinder.
By subtracting the fuel injection amount T _i (which can be displayed by the crank angle) calculated for each cylinder from, the injection start timing of each cylinder from the input of the cylinder discrimination reference signal is indicated by A ₁ -D in FIG. _It can be displayed in crank angle as shown in ₁ .

In S4, the fuel injection amount T _i and the injection start timing are stored for each cylinder.

Next, the flowchart of FIG. 4 will be described. This routine is executed every 10 msec.

In S11, the detection signals from the first and second oxygen concentration sensors 5, 7, etc. are read.

In S12, the fuel injection amount T _i is calculated for each cylinder in the same manner as in S2.

In S13, the fuel injection amount T _i calculated for each cylinder in S12
Based on the above, the injection start timing from the input of the cylinder discrimination reference signal is set for each cylinder in the same manner as in S3.

In S14, it is determined for each cylinder whether or not the injection start timing set for each cylinder in S13 has passed the count value T _C of the timer corresponding to that cylinder, and if YES, the process proceeds to S15.
If NO, proceed to S16.

In S15, the injection start timing and the fuel injection amount (the value for each 720 ° set in S4 or the value set immediately before 10 msec) stored in the previous routine are selected.

In S16, the current injection start timing and fuel injection amount set in S13 are selected.

With this configuration, when the injection control can be performed in timing with the injection start timing set in this routine, the latest injection start timing set in this routine is selected, so that the optimum fuel injection according to the operating state is performed. If it is possible, otherwise, the injection start timing set in the previous routine is selected.

In S17, the injection start timing and the fuel injection amount selected in S15 or S16 are stored.

Then, the control device 3 controls the count value of the timer of each cylinder.
When T _C reaches the injection start timing of that cylinder, an injection timing signal corresponding to that cylinder is issued, and the routine shown in the flowchart of FIG. 5 is executed.

This routine is adapted to be executed independently for each cylinder. Therefore, since this routine is executed corresponding to the cylinders, the fuel injection valves 2a to 2d of the predetermined cylinders can be drive-controlled without specially determining the cylinders to be injected. A selection means for selecting is configured.

That is, when the injection timing signal is input, S21
The fuel injection valves 2a to 2d of the cylinder are driven and controlled to supply the fuel to the cylinder.

As described above, the injection start timing for each cylinder is set on the basis of the cylinder discrimination reference signal, and the fuel injection valves 2a to 2d of the cylinders to be injection-controlled at the injection start timing are driven and controlled. It has the following effects.

That is, the regular injection order is, for example, # 1- # 2- # 3.
In the case of the # 4 cylinder, for example, as shown in FIG. 6, even if the fuel injection amount of the # 4 cylinder becomes extremely large and the injection start timing thereof is earlier than the injection start timing of the # 3 cylinder, the cylinder discrimination reference signal Since the cylinder is selected on the basis of the input time, the fuel injection is started from the # 4 cylinder first, and the fuel injection of the # 3 cylinder is started after that. Therefore, it is possible to supply the optimal fuel amount to the # 4 cylinder in accordance with the engine operating state, prevent misfires in the # 4 cylinder, and increase the degree of freedom in selecting the injection order. In particular, in the V-type engine, the actual air-fuel ratio of each bank may be greatly different, and the fuel injection amount of each cylinder may be significantly different, which is effective.

Also, when fuel injection is possible at the injection start timing set every 10 msec, injection control is performed at this injection start timing, so fuel can be supplied to the engine based on the latest data, and engine control is optimal. Becomes

The timer may be provided not for each cylinder but for each cylinder group. Further, the fuel injection valves 2a to 2d of each cylinder are driven and controlled only by the injection start timing set when the cylinder discrimination reference signal is input.

<Effect of the Invention> As described above, the present invention sets the period from the same predetermined reference signal time to the injection start timing of each cylinder to each cylinder, and based on this period, the fuel injection valve of each cylinder is set. Since the drive control is performed, the fuel injection valve of each cylinder can be controlled at the set injection start timing even if the injection order is different from the normal one.
The fuel injection control of the engine can be optimally performed.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention, FIG. 2 is a configuration diagram showing an embodiment of the present invention, FIGS. 3 to 5 are flowcharts of the same, and FIG. 6 is a diagram for explaining the operation of the same. Figure, 7th
The figure is a figure for demonstrating the conventional fault. 1 ... Engine, 2a-2d ... Fuel injection valve, 3 ... Control device,
5 ... First oxygen concentration sensor, 7 ... Second oxygen concentration sensor, 8 ... Crank angle sensor

Claims (1)

[Scope of utility model registration request] 1. A multi-cylinder internal combustion engine having a fuel injection valve for each cylinder of the engine and a reference signal output means for outputting a predetermined reference signal in synchronization with engine rotation. Fuel injection amount setting means for setting the amount, injection start timing setting means for setting the period from the time when the same predetermined reference signal is input to the injection start timing for each cylinder according to the set fuel injection amount, and the time A time measuring means for measuring, a selecting means for selecting a cylinder to be injection-controlled based on the time measured from the time when the predetermined reference signal is input and the set injection start timing, and a fuel injection valve for the selected cylinder. An electronically controlled fuel injection device for a multi-cylinder internal combustion engine, comprising: drive control means for controlling the drive.