JPS62142841A - Electronic control type fuel injection device for internal combustion engine - Google Patents

Abstract

PURPOSE:To enable the dissolution of the difference between a required fuel injection quantity and an actual injection quantity by comparing the actual fuel injection quantity with the required fuel injection quantity operated based on engine operating conditions thereby correcting the fuel injection quantity depending on deviation thereof. CONSTITUTION:A basic fuel injection quantity is operated by an operating means A based on engine operating conditions for making a setting means B set a feedback correction coefficient correcting the basic fuel injection quantity in such a way that a specified amount is increased or decrease so as to bring an actual air fuel ratio to a target one. Then the fuel injection quantity is operated by an operating means C based on the basic fuel injection quantity and the feedback correction coefficient. And the fuel injection quantity is compared by a setting means E with an actual fuel injection quantity detected by a detecting means D for setting a fuel injection correction value to correct the fuel injection quantity in such a way that actual fuel injection quantity will be a required fuel injection quantity, so as to be outputted thereof by the operating means C.

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.

<Prior Art> A fuel injection valve used in an electronically controlled fuel injection system is opened by a drive pulse signal given in synchronization with engine rotation, and the fuel injection valve injects fuel at a predetermined pressure into the engine. ing. Therefore, the fuel injection amount is controlled by the pulse width of the drive pulse signal, and if this pulse width is set as Ti and the control signal corresponds to the fuel injection amount, in order to obtain the stoichiometric air-fuel ratio which is the target air-fuel ratio, Ti is determined by the formula.

T i =Tp ・C0EF・α+Ts However, Tp is the basic pulse width corresponding to the basic fuel injection amount and is called the basic fuel injection amount for convenience. 'rp = K・Q/N, where K is a constant and Q
is the engine intake air flow rate, and N is the engine speed. C0EF
are various correction coefficients such as water temperature correction. α is a feedback correction coefficient for feed puncture control (λ control) of the air-fuel ratio, which will be described later. Ts is a voltage correction element, which is used to correct changes in the injection flow rate of the fuel injector due to fluctuations in battery voltage.

Regarding λ control, an oxygen sensor is installed in the exhaust system to detect the actual air-fuel ratio, and the slice level controls whether the air-fuel ratio is richer or leaner than the stoichiometric air-fuel ratio.
For this reason, the above-described feedback correction coefficient α is determined, and by changing this α, the stoichiometric air-fuel ratio is maintained.

Here, the value of the feedback correction coefficient α is the proportional integral (P
I) It is changed by control and stable control is achieved.

That is, the output voltage of the oxygen sensor is compared with the slice level voltage, and if it is higher or lower than the slice level,
If the air-fuel ratio is rich (lean) without suddenly making it rich or lean, first lower (raise) it by P, then gradually lower (raise it) one minute at a time. ), and controls the air-fuel ratio to be lean (rich).

However, under conditions where λ control is not performed, such as in high rotation and high load regions, α is clamped and the desired air-fuel ratio is obtained by setting various correction coefficients COEF.

<Problem to be solved by the invention> However, as mentioned above, in the past, α is clamped under conditions where λ control is not performed, such as in high rotation and high load areas, Under these conditions, if there is a difference between the requested fuel injection amount and the actual fuel injection amount, there is a problem in that it is not possible to correct this difference.

The present invention has been made in view of these conventional problems, and it is an object of the present invention to eliminate the error between the requested fuel injection amount and the actual fuel injection amount over the entire fuel flow rate range.

Means for Solving the Problems> Therefore, as shown in FIG. Feedback correction coefficient setting means for increasing or decreasing a feed bank correction coefficient by a predetermined amount for correcting the basic fuel injection amount so as to approach the target air-fuel ratio; and a basic fuel injection amount calculated by the basic fuel injection amount calculation means. and fuel injection amount calculation means for calculating the fuel injection amount based on the feed bank correction coefficient set by the feedback correction coefficient setting means, actual fuel injection amount detection means for detecting the actual fuel injection amount, and the calculated fuel Fuel injection amount calculation means for comparing the injection amount with the actual fuel injection amount detected by the actual fuel injection amount detection means and correcting the fuel injection amount so that the actual fuel injection amount becomes the required fuel injection amount. and fuel injection amount difference correction setting means for setting the fuel injection amount difference correction amount.

Since the fuel injection amount is corrected for the difference in fuel injection amount, for example, when the feedback correction coefficient is clamped during operation in a high rotation, high load region, etc., the requested fuel injection amount and the actual fuel injection amount are If a difference occurs, this can be corrected.

<Example> Hereinafter, an example of the present invention will be described based on FIGS. 2 to 4.

In FIG. 2, the engine 1 includes an air cleaner 2°, an intake duct 3. Throttle chamber 4 and intake manifold 5
Air is inhaled through.

The intake duct 3 is provided with an air flow meter 6 as means for detecting the intake air flow rate Q, and outputs a voltage signal corresponding to the intake air flow rate Q signal.

The throttle chamber 4 includes a primary throttle valve 7 and a secondary throttle valve 8 that operate in conjunction with an accelerator pedal (not shown).
is provided to control the intake airflow iQ. or,
An auxiliary air passage 9 is provided which bypasses these throttle valves 7.8, and an idle control valve 10 is interposed in this auxiliary air passage 9. The intake manifold 5 or the intake port of the engine 1 is provided with a fuel injection valve 11 as a fuel injection means. The fuel injection valve 11 is an electromagnetic fuel injection valve that opens when the solenoid is energized and closes when the energization is stopped.The fuel injection valve 11 opens when the solenoid is energized by a drive pulse signal, and is fed under pressure from a fuel pump (not shown). The engine 1 is injected with fuel controlled to a predetermined pressure by the pressure regulator 26.

From engine 1, exhaust manifold 12. Exhaust duct 13
．． Exhaust gas is discharged via the three-way catalyst 14 and the muffler 15.

An oxygen sensor 16 is provided in the exhaust manifold 12. This oxygen sensor 16 detects the oxygen concentration in the atmosphere (constant).
outputs a voltage signal according to the ratio of the oxygen concentration in the exhaust gas and
This is a known sensor whose electromotive force suddenly changes when the air-fuel mixture is combusted at the stoichiometric air-fuel ratio. Therefore, the oxygen sensor 16 is a means for detecting the air-fuel ratio (rich/lean) of the air-fuel mixture.

In addition, a crank angle sensor 17 is provided.

The crank angle sensor 17 includes a signal disc plate 19 provided on the crank boot 1J18.
For example, a reference signal every 120 degrees and a position signal every 1 degree are outputted by the teeth provided on the outer circumference of the sensor. Here, the engine speed N can be calculated by measuring the period of the reference signal.

Therefore, the crank angle sensor 17 is a means for detecting not only the crank angle but also the engine speed N.

Output signals from the air flow meter 6, crank angle sensor 17, and oxygen sensor 16 are all input to a control unit 30. Furthermore, control unit 3
The voltage of a battery 20 is directly applied to the engine 0 via an engine key switch 21 as its operating power source and for detecting the electric voltage.

Furthermore, the control unit 30 is provided with a water temperature sensor 22 for detecting the engine cooling water temperature as required. - Throttle sensor 23 including an idle switch that detects the throttle opening of the next throttle valve 7. Vehicle speed sensor 24 that detects vehicle speed. A signal from a neutral switch 25 or the like that detects the neutral position of the transmission is input. The control unit 30 performs arithmetic processing on the basis of various input signals and outputs an optimal driving pulse signal to the fuel injection valve 11 to obtain the fuel injection amount for obtaining the optimal air-fuel ratio.

The functions of the basic fuel injection amount calculation means, the feedback correction coefficient setting means, the fuel injection amount calculation means, and the fuel injection amount difference correction setting means are achieved by a program of the CPU in the control unit 30.

Next, the operation will be explained with reference to the flowcharts of FIGS. 3 and 4.

In the fuel injection amount calculation routine shown in FIG.
(SL in the figure) shows the intake airflow IQ obtained from the signal from the airflow meter 6 and the crank angle sensor 17.
The basic fuel injection amount Tp (=-Q/N) is calculated from the engine speed N obtained from the signal from the engine. This part corresponds to the basic fuel injection amount calculation means.

In step 2, various correction coefficients C0FF are set as necessary.

In step 3, a voltage correction numerator s is set based on the voltage value of the battery 20. In step 4, it is determined whether the λ control condition is met.

Here, in cases where the λ control condition is not met, for example, in a high rotation, high load region, etc., the feedback correction coefficient α is clamped to the previous value (or reference value 1), and from step 4 onward, the fuel injection amount shown in FIG. The process advances to step 9 for setting the fuel injection amount difference using the difference calculation routine.

In the case of the λ control condition, in steps 5 to 7, the output voltage Vo2 of the oxygen sensor 16 and the slice level voltage Vref corresponding to the stoichiometric air-fuel ratio are compared to determine whether the air-fuel ratio is rich or lean, and the control is performed using integral control or proportional-integral control. Set the feedback correction coefficient α.

This part corresponds to feedback correction coefficient setting means. Specifically, in the case of integral control, when the comparison in step 5 determines that the air-fuel ratio = rich (■o2>Vref), the feedback correction coefficient α is decreased by a predetermined integral (1) from the previous value in step 6. Conversely, when it is determined that the air-fuel ratio is lean (Vo2<Vref), in step 7 the feed bank correction coefficient α is calculated by a predetermined integral (
I) increase by minutes. In the case of proportional-integral control, in addition to this, a predetermined proportional bone (P
).

In the next step 8, the fuel injection amount Ti is calculated according to the following equation. This part corresponds to the fuel injection amount calculation means.

Ti = Tp - COEF .alpha.+Ts+T (.DELTA.q) However, as T (.DELTA.q), the value obtained in the fuel injection amount difference calculation routine shown in FIG. 4 is used.

Next, a calculation routine for this fuel injection amount difference will be explained.

In FIG. 4, in step 10, the fuel injection amount q is calculated from the calculated injection pulse Ti. In step 11, the actual fuel injection amount q is detected by the electromagnetic flow meter 27 interposed between the fuel injection valve 11 and the pressure regulator 26 in FIG. 2, and in step 12, the fuel injection itq and the actual fuel The pulse width T (Δq) is calculated from the difference Δq from the injection amount q゛.

According to this configuration, since the fuel injection amount is corrected by the fuel injection amount difference numerator (Δq), for example, when the feedback correction coefficient α is clamped during operation in a high rotation, high load region, etc.
Requested fuel injection 1q and actual fuel injection ff1q'
If a difference occurs, this can be corrected, and it becomes possible to eliminate the error between the requested fuel injection amount and the actual fuel injection amount over the entire fuel flow rate range.

<Effects of the Invention> As explained above, according to the present invention, the fuel injection amount is corrected so that the actual fuel injection amount becomes the required fuel injection amount. When the air-fuel ratio feedback correction coefficient is clamped during operation, the error in the injection amount can be corrected, and when used in conjunction with the setting of the air-fuel ratio feedback correction coefficient, the required fuel injection amount and the required fuel injection amount can be corrected for the entire fuel flow range. It becomes possible to eliminate errors in the actual fuel injection amount.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIG. 2 is a configuration diagram showing an embodiment of the present invention, and FIGS. 3 and 4 are flow charts showing control contents. ■... Engine 6... Air flow meter 11...
・Fuel injection valve 16...Oxygen sensor 17...
Crank angle sensor 30... Control unit patent applicant Agent of Japan Electronics Co., Ltd.
Patent Attorney Fujio Sasashima Figure 3

Claims (1)

[Claims] a basic fuel injection amount calculating means for calculating a basic fuel injection amount based on engine operating conditions; and a feedback correction coefficient for correcting the basic fuel injection amount by a predetermined amount so that the actual air-fuel ratio approaches the target air-fuel ratio. A feedback correction coefficient setting means that increases or decreases the fuel injection amount, and a fuel injection amount calculation that calculates the fuel injection amount based on the basic fuel injection amount calculated by the basic fuel injection amount calculation means and the feedback correction coefficient set by the feedback correction coefficient setting means. means, an actual fuel injection amount detecting means for detecting an actual fuel injection amount, and comparing the calculated fuel injection amount and the actual fuel injection amount detected by the actual fuel injection amount detecting means to determine the actual fuel injection amount. An electronic device for an internal combustion engine, comprising: fuel injection amount difference correction setting means for setting a fuel injection amount difference correction amount for correcting the fuel injection amount so that the injection amount becomes the required fuel injection amount. Control fuel injector.