JPS6065250A - Electronically controlled fuel injector for internal- combustion engine - Google Patents

Abstract

PURPOSE:To improve the transient responce by providing means for calculating the basic injection, means for calculating the injection and means for controlling the injection pulse for starting/ending fuel injection. CONSTITUTION:Basic injection calculating means will calculate the basic injection from the period between referential input signals and suction air flow. Injection calculating means will calculate the injection by correcting the basic injection. Injection pulse control means will start fuel injection with delayed timing against the referential input signal. Fuel injection is terminated simultaneously with termination of calculation of injection. Consequently, the transient responce of system is improved while the control range is widened.

Description

[Detailed description of the invention] Technical fields> The present invention relates to an electronically controlled fuel injection device for an internal combustion engine.

<Background technology> In an electronically controlled fuel injection device for an internal combustion engine, the injection amount Ti
is calculated according to the following equation. Note that Ti is the duration of the injection pulse to the fuel bullet, and is also the injection time.

Ti=TpXCOEF+Ts: Tp=KXQ/N
Here, 'rp is the basic injection amount, which is intertwined with the intake air flow rate Q and the rotational speed N (K is a constant).

C0EF is various correction coefficients. Ts is a voltage correction amount.

By the way, in the past, calculations of the injection amount Ti, etc. were performed at the timing shown in FIG.

That is, in synchronization with a reference input signal generated in synchronization with engine rotation, for example, an ignition signal (generated every % rotation in the case of a 4-cylinder engine), the cycle (time) between the immediately preceding ignition signals Tig
The rotational speed is determined by measuring n, and at the same time, the integral value of the intake air flow rate between the ignition signals is calculated to determine the intake air flow rate. I put it on. Then, based on these values, the basic injection amount Tp
is calculated, and then the injection amount Ti is calculated. On the other hand, in the case of a multi-point injection system, fuel injection is performed in synchronization with the ignition signal every revolution, so the fuel injection valve injects fuel in synchronization with the next ignition signal after calculating the injection amount Ti. An injection pulse in a pulse corresponding to the quantity Ti is output.

However, in this method, due to the time it takes to calculate Ti, from the point of fuel injection, data on the rotational speed and intake air flow rate are from two revolutions ago, and Ti calculated using old data is output. Was. For this reason, there was a problem with responsiveness in a transient state.

Therefore, as disclosed in Japanese Unexamined Patent Publication No. 57-13239, calculation of the injection amount Ti is started in synchronization with the reference input signal, and at the same time, transmission of an injection pulse to the fuel injection valve is started to inject fuel. The injection time is measured during this injection, and when the calculation result matches the measured injection time after the calculation is completed, the injection pulse is stopped and the fuel injection is ended. I thought about that.

However, in this method, the condition is that all Ti calculations be completed between the start and the end of Ti injection, and the injection pulse must be within a pulse longer than the minimum time required for the calculation. , it would become uncontrollable, so it was difficult to realize in practice.

<Object of the Invention> In view of the above-mentioned actual situation, the present invention aims to improve transient response by performing fuel injection based on calculation results using the latest data as much as possible, and to improve injection pulses among relatively small pulses. An object of the present invention is to provide an electronically controlled fuel injection device that can expand the control range by making it possible to output as much as possible.

<Configuration of the Invention> Therefore, in the present invention, calculation of the injection amount is performed separately into calculation of the basic injection amount and subsequent correction calculation, and fuel injection is started during the correction calculation.

That is, as shown in Fig. 2, the basic injection amount is activated by a reference input signal generated in synchronization with the engine rotation, and the basic injection amount is calculated from the period between the immediately preceding reference input signals and the intake air flow rate. a calculation means; an injection amount calculation means that is activated at a timing with a predetermined delay with respect to the reference input signal and calculates the injection amount by correcting the calculated basic injection amount; Fuel injection is started with the injection pulse in the on state, while timing is started at the same time as the start of fuel injection, and when the injection time reaches the injection time, which is calculated at the same time as the calculation of the injection amount is completed, the injection pulse is sent to the fuel injection valve. and an injection pulse control means for turning off the fuel injection valve and terminating the fuel injection.

<Example> 3 to 5 show a first embodiment.

First, the hardware configuration will be explained with reference to FIG.

1 is a CPU, 2 is a P-ROM, 3 is an A/D converter, and 4 is an address decoder.

Analog input signals for controlling the injection amount include an intake air flow rate signal from the hot wire airflow meter 5, a water temperature signal from the water temperature sensor 6, an exhaust oxygen concentration signal from the O2 sensor 7, and a battery voltage from the battery 8. etc., and these are input to the A/D converter 3 via the analog input interface 9.

Digital input signals include ON-OFF signals from the idle switch 10, star 1-switch 11, etc., and these are input to the C through the digital input interface 12.
Input to PUI.

In addition, the ignition signal from the ignition coil 13 is input to the CPUI via the waveform shaping circuit 14.

Output signal from CPUI (injection pulse to fuel injection valve)
is sent to the fuel injection valve 16 via the current control circuit 15.

Next, explanation will be given with reference to the timing chart of FIG. 4 and the flow chart of FIG. 5.

Calculation of the basic injection amount 'rp is started in synchronization with the ignition signal. This is performed by an interrupt routine using an ignition signal as shown in FIG. 5fAl.

That is, in Sl, a predetermined time (for example, 1 m s
) reserves the later interrupt routine. In S2, the period Tign between the previous ignition signals is measured.

In S3, the intake air flow rate Q between the ignition signals is calculated. In addition, when calculating the intake air flow rate Q, the output of the air flow meter was A/D converted every predetermined time (for example, 1.28 m S') between the ignition signals, the values were added, and the ignition signal was input. In each stage, the addition value ΣQ is set to the number of data n
The average value of the intake air flow rate can be calculated by dividing by . It is also possible to do it with hardware. Then, in S4, the basic injection amount Tp is calculated from the cycle Tign and the intake air flow rate Q according to the following equation.

Tp=KXQXTign Note that when performing feedbank control of the air-fuel ratio, the basic injection amount 'rp is calculated according to the following equation.

Tp-KXQXTign xα α is the air-fuel ratio feedback correction coefficient (reference value 1), 0
The actual air-fuel ratio detected by the two sensors is compared with the stoichiometric air-fuel ratio and determined by proportional-integral control.

Then, 1 ms after the ignition signal, calculation of the injection amount Ti is started and fuel injection is started. This is Figure 5 fBl
This is done by the interrupt routine shown in .

That is, at Sll, transmission of an injection pulse to the fuel injection valve is started. At 312, counting of clock pulses begins. In step 313, the injection amount Ti is calculated by correcting the already calculated basic injection amount Tp as shown in the following equation.

Ti=TpXCOEF+Ts.

After the calculation is completed, the count value C is read in S14, and 3
The comparison between the count value C and the calculated Ti in Step 15 is repeated, and when the two match, the process proceeds to S16 and the transmission of the injection pulse to the fuel injection valve is stopped.

6 to 8 show a second embodiment.

Note that this embodiment is an example in which ignition control is performed by the same unit, and is an example of a single point injection system.

The difference in the hardware configuration shown in FIG. 6 is that reference signals every 180 degrees and position signals every 1 degree from the crank angle sensor 17 are input as standard input signals via the waveform shaping circuit 18. For ignition control, an output signal is issued from the CPU via the ignition coil driver 19 to the power transistor 20 of the ignition coil.

Next, explanation will be given with reference to the timing chart of FIG. 7 and the flow chart of FIG. 8.

Calculation of the basic injection amount 'rp is started in synchronization with the reference signal from the crank angle sensor that is generated every 180 degrees at 80'' before top dead center.This is performed by the interrupt routine using the reference signal shown in Fig. 8fAl. be exposed.

That is, in S21, the period Tref between the immediately preceding reference signals is measured. In S22, the intake air flow rate Q between the reference signals is calculated.

In addition, when calculating the intake air flow rate Q, the output of the air flow meter is A/D converted every predetermined time (for example, 940 μs) between the reference signals, and the resulting values are added, and when the reference signal is input, the added value is The average value of the intake air flow rate is calculated by dividing ΣQ by the number of data items n. Then, in S23, the basic injection amount 'rp is calculated from the period Tref and the intake air flow rate Q according to the following equation.

Tp=KxQXTref When performing air-fuel ratio feedback control, the basic injection amount 'rp is calculated according to the following equation.

Tp=KxQXTref The counter value is decremented by one each time the counter value reaches O, and when the counter value reaches O, an ignition pulse is output to the power transistor of the ignition coil via the ignition coil driver.

Here, calculation of the injection amount Ti is started in synchronization with the ignition pulse, and fuel injection is also started. This is done by the interrupt routine shown in FIG. 8(B).

That is, in S31, transmission of an injection pulse to the fuel injection valve is started. In S32, counting of clock pulses is started. In S33, the injection amount Ti is calculated by correcting the already calculated basic injection amount Tp as shown in the following equation.

T i = T p
The comparison between the count value C and the calculated Ti is repeated, and when the two match, the process proceeds to S36 and the transmission of the injection pulse to the fuel injection valve is stopped.

<Effects of the Invention> As explained above, according to the present invention, the injection amount can be controlled by always performing calculations using the latest rotational speed and intake air amount data, and the sampling timing of the data coincides. It is possible to configure a system with excellent transient response, and since the calculation is performed in two steps, it is also possible to output injection pulses in small pulses.

[Brief explanation of drawings]

FIG. 1 is a timing chart showing a conventional example, FIG. 2 is a block diagram showing the configuration of the present invention, FIG. 3 is a hardware configuration diagram of the first embodiment, FIG. 4 is a timing chart of the same as above, and FIG. FIG. 1...CPU 5...Air flow meter 13...
・Ignition coil 16... Fuel injection valve] 7... Crank angle sensor 19... Ignition coil driver Patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fujio Sasashima Figure 5 (B)

Claims (1)

[Claims] a basic injection amount calculating means that is activated by a reference input signal generated in synchronization with engine rotation and calculates a basic injection amount from the period between the immediately preceding reference input signals and the intake air flow rate; an injection amount calculation means that is activated at a timing with a predetermined delay and calculates the injection amount by correcting the calculated basic injection amount; and an injection amount calculation means that is activated at a timing with a predetermined delay and calculates the injection amount by correcting the calculated basic injection amount; starts, and at the same time starts timing at the same time as the start of fuel injection,
electronically controlled fuel injection for an internal combustion engine, comprising an injection pulse control means that turns off an injection pulse to a fuel injection valve to end fuel injection when an injection time that is set at the same time as the calculation of the injection amount is completed; Device.