JPS638296B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an internal combustion engine that uses a microcomputer, and in particular controls the air-fuel ratio of the mixture supplied to the combustion chamber during transient operations such as acceleration and deceleration, the amount of the mixture, and the ignition. The present invention relates to a control device for an internal combustion engine that uses a microcomputer to adjust timing to an optimal state.

Due to the rising price of petroleum resources and environmental pollution, it has become necessary for automobile engines to achieve high levels of fuel efficiency, exhaust emissions, and power performance. In contrast, with the introduction of a microprocessor as described in Japanese Patent Application Laid-Open No. 54-58116, the intake air amount signal and rotation speed signal under each operating condition can be used to
Required fuel amount from a pre-stored table,
The ignition timing and exhaust recirculation amount are determined through interpolation calculations and correction calculations based on cooling water temperature and intake air temperature. Therefore, during steady operation, it is possible to obtain almost ideal fuel amount, ignition timing, and exhaust recirculation amount. However, during transient operations such as acceleration and deceleration, it takes time to take in the intake air amount and rotational speed signals and calculate the fuel amount and ignition timing, so by the time the calculation is finished, the engine operating conditions have already changed. Currently, it is difficult to obtain the optimal fuel amount, ignition timing, and exhaust recirculation amount. However, most of the practical driving conditions are a series of transient conditions, and the optimal fuel amount, ignition timing, and
It is desired to establish a control method to obtain the exhaust recirculation amount.

SUMMARY OF THE INVENTION An object of the present invention is to provide a control device for an internal combustion engine that maintains at least the optimal fuel amount and ignition timing even during transient operation, thereby simultaneously reducing fuel consumption and exhaust gas.

As mentioned in the prior art section, computer calculations require a finite amount of time, and even after the calculations are completed, the fuel must be injected after waiting until the fuel injection timing. Operating conditions are changing at the time of fuel injection. In order to avoid this, the operating conditions during actual fuel injection are predicted from conventional data, that is, the amount of air sucked into the combustion chamber during fuel injection and the engine speed are predicted, and the amount of fuel and ignition timing are calculated. The fuel amount and ignition timing are always optimized even during transient operation.

FIG. 1 shows a configuration diagram of an internal combustion engine control device applied to the present invention. In the figure, intake air is supplied to an air cleaner 1, a throttle body 2, a throttle valve 6 having a throttle valve opening switch 7, an intake pipe 8, and an intake valve 9.
through which it enters the combustion chamber 24. The intake air flow rate is measured by a hot wire type air flow meter 4 provided in the bypass passage 3 of the throttle body 2. 1 more
3 is an oxygen sensor provided in the exhaust pipe and measures the oxygen concentration in exhaust gas, 12 is an engine cooling water temperature sensor, and 11 is a piston. Fuel is in fuel tank 1
7. Fuel is supplied from the fuel injection valve 5 through the fuel pump 18, fuel damper 19, filter 20, fuel pressure regulator 21, and fuel pipe 23. The amount of fuel to be supplied is determined by the air flow meter 4,
It is determined based on the signals from the oxygen sensor 13 and the cooling water temperature sensor 12. Ignition timing is determined by an ignition coil 15 based on a signal from a computer 16, and ignition is performed by a spark plug 10. Note that 14 is a crank angle sensor for determining ignition timing.

FIG. 2 is a detailed diagram of the computer 16 of FIG. Input signals include an intake air amount meter 4, an engine cooling water temperature sensor 12, a throttle valve opening switch 7, and the like. These analog inputs are input to the multiplexer 30, and the outputs of each sensor are selected in a time-division manner and sent to the AD converter 31, where they become digital signals. Further, information inputted as an ON-OFF signal, for example, an engine key switch, a starter switch, etc. (not shown), is handled as a 1-bit digital signal. Further, a signal such as a pulse train from the crank angle sensor 14 is also input. The CPU 33 is a processing central unit that performs digital arithmetic processing, the ROM 32 is a storage element for storing control programs and fixed data, and the RAM 34
is a readable and writable storage element. The I/O circuit 35 has a function of sending signals from 31 and each sensor to the CPU 33, and sending signals from the CPU 33 to the injection valve 5 and the ignition coil 15.

FIG. 3 shows an internal combustion engine control device different from that in FIG. 1, and whereas FIG. 1 had one fuel injection valve 5, in FIG. This is an example in which as many fuel injection valves as the number of fuel injection valves are provided in close proximity to the intake valve. Note that an air flow meter 41 40 that measures the amount of air taken in by the engine is a valve for controlling the flow rate of exhaust gas recirculation. In the above configuration, a conventional method of calculating the amount of injected fuel from the intake air amount signal will be explained with reference to FIG. Considering the case of 4 cylinders and 4 cycles, for example, the first cylinder is provided with a representative value of the air flow meter signal during the intake stroke (e.g., an integrated value of the air flow meter signal during the intake stroke, or
The air flow meter signal at a specific crank angle is
At the end of the cylinder's intake stroke, the fuel flow rate is taken into the CPU 33 and determined from a pre-stored table. This calculation is performed during the compression stroke of the first cylinder. Here, the firing order is 1-3-4
-2 cylinders in this order, fuel injection is performed at the beginning of the explosion stroke of the first cylinder, that is, at the beginning of the suction stroke of the fourth cylinder, and the fuel injected here is sucked into the fourth cylinder. However, during transient operation, the amount of air taken into the fourth cylinder is already different from that during the intake stroke of the first cylinder, and the air-fuel ratio of the mixture taken into the fourth cylinder is the desired one. It comes out differently. In FIG. 4, the air amount signal used to calculate the amount of fuel during fuel injection is shown by a broken line A, and the amount of air actually taken into each cylinder at that time is shown by a solid line B, thereby showing the temporal relationship between the two. Due to the calculation time and injection waiting time, there is no problem during steady operation, but during transient operation, the air-fuel mixture that actually enters the cylinder is fundamentally different from the expected one. Next, the correction method will be explained.

In FIG. 5, as explained in FIG. ₄ , at time t3, the representative signal Q _a3 of the air amount signal is taken in, the fuel amount is calculated, and fuel injection is started from time _t4 . However, the actual amount of intake air at that time is
Q _a5 . Therefore, it is necessary to estimate Q _a5 at time _t3 . One method is to use the air amount representative signal Q _a2 at t ₂ and the Q _a3 signal at t ₃ , and let the estimated value of Q _a5 be Q _a5 ′.Q _a5 ′=Q _a3 +X ₁ (Q _a3 − Q _a2 )...(1) Here, X ₁ is a weighting coefficient, and uses a value of 0.5 to 2.0, for example. Repeat this step by step. The same applies to deceleration. That is, the air amount signal when the air amount signal is taken in and the previous signal are used to extrapolate the air amount signal when fuel is actually injected.
The flowchart is shown in FIG. 6 and will be explained below.

In step 50, the current representative air amount signal is
Q _ao is read, and in the next step 60, the previous representative air amount signal Q _ao-1 stored in the RAM is read. Next, in step 70, an estimated air amount signal Q _ao+2 during injection is determined using Q _ao and Q _ao-1 . This estimated air amount signal Q _ao+2 is obtained by an extrapolation formula determined by Q _ao+2 = Q _ao + X (Q _ao - Q _ao-1 ) where X: coefficient.

Then, in step 80, the amount of fuel to be injected is calculated using the estimated air amount signal Q _ao+2 .

FIG. 8 is a correspondence diagram functionally representing the above-mentioned operation, in which the signal of the air flow meter 4 is sent to the extrapolation means 110, and the previously captured air amount signal Q _ao- stored in the storage means 120 is shown. ₁ and the air amount signal Q _ao taken in this time, calculate the estimated air amount Q _ao+2 . When the estimated air amount Q _ao+2 is determined, the injected fuel determining means 130
Then, the injection pulse T _P is determined using the rotational speed signal N from the crank angle sensor 14.

Furthermore, in Fig. 5, if the acceleration/deceleration of the engine is detected based on the increase/decrease in the air amount representative signal and it is determined that the engine is in an acceleration or deceleration situation, then the representative value of the air amount signal during the intake stroke is detected. Alternatively, the fuel amount may be calculated using the air amount signal at the end of the intake stroke.
The flowchart is shown in FIG. 7, and the same numbers as in FIG. 6 indicate the same functions. Then, in step 90, if it is determined that the difference between Q _ao and Q _ao-1 is larger than the predetermined value ε, it indicates acceleration or deceleration, so in that case, the process moves to step 100, where the air amount signal at the end of the intake stroke is Load Q _a . If the difference between Q _ao and Q _ao-1 is smaller than the predetermined value ε, the process moves to step 70;
The same operation as in FIG. 6 is performed.

The same thing as described above also occurs when setting the ignition timing. In Fig. 5, at time _t3 , if the ignition timing is calculated from the air amount signal _Qa3 and the engine speed _N3 and is set to 20°BTDC, for example, the actual ignition time.
At t ₄ , the engine speed is changing, so
Proper ignition timing is not achieved. Therefore, at time _t3 , it is necessary to estimate the rotation speed at time _t4 . Similarly to equation (1), the estimated value N ₄ ′ is N ₄ ′=N ₃ +X ₂ (N ₃ −N ₂ ) (2) where X ₂ is a weighting coefficient. This estimate
The ignition timing is calculated from N ₄ ′ and the representative air amount signal Q _a3 at time t ₃ .

The above-described correction allows the air-fuel ratio of the air-fuel mixture supplied to the fuel chamber, the amount of air-fuel mixture, and the ignition timing to be accurately maintained at optimal values even when the engine is accelerated or decelerated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an internal combustion engine to which the present invention is applied. FIG. 2 is a diagram showing details of the computer of FIG. 1. FIG. 3 is a configuration diagram of another internal combustion engine to which the present invention is applied. FIG. 4 is an explanatory diagram of the conventional fuel amount calculation method. FIG. 5 is an explanatory diagram of the fuel amount calculation method of the present invention. Figures 6 and 7 are
The flowchart of the present invention, FIG. 8, is a functional diagram corresponding to FIG. 6. 4...Air flow meter, 5...Fuel injection valve, 14...Crank angle sensor, 15...Ignition coil, 16...Computer.

Claims (1)

[Scope of Claims] 1. A control device for an internal combustion engine comprising a control device that generates a control signal for controlling a fuel control device based on signals from at least an intake air amount detection device and an engine rotation speed detection device, The device calculates the estimated air amount signal at the time of fuel injection from the air amount signal Q _ao taken in this time and the air amount signal Q _ao-1 taken in last time.
A control device for an internal combustion engine, comprising extrapolation means for calculating Q _{a from an equation consisting of Q a =} Q _ao +X (Q _ao −Q _ao-1 ), where X is a coefficient.