JPS6318766Y2 - - 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, during transient operations such as acceleration and deceleration, the air-fuel ratio and amount of the mixture supplied to the combustion chamber. , relates to a control device for an internal combustion engine that uses a microcomputer to adjust ignition timing to an optimal state.

Due to the rising price of petroleum resources and environmental pollution, automobile engines are now required to achieve high levels of fuel efficiency, exhaust emissions, and power performance. In contrast, with the introduction of a microprocessor as seen in SAE Paper 800056, the intake air amount signal and rotation speed signal under each operating condition can be used to
The required fuel amount, ignition timing, and exhaust gas recirculation amount are determined from a pre-stored table 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 even during transient operation. However, most of the practical driving conditions are a series of transient conditions, and it is desired to establish a control method that obtains the optimal fuel amount, ignition timing, and exhaust gas recirculation amount in the transient conditions.

An object of the present invention is to provide a control device for an internal combustion engine that can supply an optimal amount of fuel at least during transient operation.

The configuration of the present invention will be explained with reference to FIG. The suction negative pressure is detected by the suction negative pressure sensor. The output of the sensor is sampled at a predetermined timing by a sampling means. The sampled values are stored in a storage device (random access memory).

The predicted suction negative pressure P e predicted by the suction negative pressure calculation means based on the suction negative pressure signal data P _o and the previously stored signal data P _o-1 is calculated as _{P e =} P _o + Y
(P _o −P _o-1 ), (Y: constant).

An injection amount calculation means calculates a fuel injection signal from the suction negative pressure signal obtained by the calculation.

The fuel injection signal is applied to the fuel injection valve by a driving means.

In the conventional method, the injection amount was determined from previous data, which meant that the fuel injection amount would not match the actual operating conditions. However, with a device like that of this invention, the operating conditions at the time of actual fuel injection are predicted from previous data, making it possible to supply just the right amount of fuel.

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 with 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 the pressure sensor 4 from the intake pipe 8 via the conduit 3. Furthermore, 13 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 supplied from the fuel injection valve 5 through the fuel tank 17, fuel pump 18, fuel damper 19, filter 20, fuel pressure regulator 21, and fuel pipe 23. The amount of fuel to be supplied is calculated by the computer 16 from signals from the pressure sensor 4, oxygen sensor 13, and cooling water temperature sensor 12. Ignition is performed by an ignition coil 15 and a spark plug 10 in response to a signal from a computer 16. Note that 14 is a crank angle sensor for determining ignition timing.

FIG. 2 is a detailed diagram of the computer 16 of FIG. As an input signal, crank angle sensor 1
4, intake pressure sensor 4, engine cooling water temperature sensor 1
2. There are signals such as the throttle valve opening switch 7. These analog inputs are input to a multiplexer 30, and the output of each sensor is selected in a time-sharing manner.
It is sent to the AD converter 31 and becomes a digital signal. Furthermore, information input as an ON-OFF signal, for example, an engine key switch, a starter switch, etc. (not shown);
Treated as a bit digital signal. Furthermore, like the crank angle sensor 14, a pulse train signal 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 32 is a storage element for storing control programs and fixed data.
4 is a readable and writable storage element. The I/O circuit 35 sends signals from the AD converter 31 and each sensor to the CPU 33.
The signal from the CPU 33 is sent to the injection valve 5 and the ignition coil 1.
It has a function to send to 5.

FIG. 3 is another system diagram of FIG. 1. In FIG. 1, there was one fuel injection valve 5, but three
The figure shows an example of a system in which one fuel injection valve for each cylinder, that is, the same number of fuel injection valves as the number of cylinders, are provided very close to the intake valve. Note that 4 is a pressure sensor that measures the intake pressure, and 41 is a valve for controlling the exhaust recirculation flow rate.

Figure 4 shows a 4-stroke, 4-cylinder engine with 1 intake and 1 intake.
This figure shows the difference between the ideal ignition timing characteristics (shown by the solid line) when a microcomputer is used to control the ignition timing during accelerated operation in an injection system and the ignition timing control characteristics using the conventional method. It is something. Here, the fuel supply system corresponds to a so-called multi-point fuel injection system having a fuel injection valve at each intake port, or a so-called single-point fuel injection system having a single fuel injection valve at an intake manifold assembly.
As shown in Figure 4, when the throttle valve opening θ _TH is suddenly opened in the middle of the intake stroke of the No. 1 cylinder (hereinafter abbreviated as Cyl), the suction negative pressure P _B exhibits a pulsating waveform and the negative pressure increases. Changes in the direction of becoming smaller. Here, assuming that the fuel supply amount is ideally given in response to the suddenly changed engine operating state, the engine speed N changes as shown in FIG. 4. As is well known, the required ignition timing of an engine is a value determined by the intake negative pressure or intake air amount and the engine speed. (The exhaust gas recirculation amount will be omitted from the explanation here.) Therefore, the ideal ignition timing needs to be determined based on the true suction negative pressure during the suction stroke and the engine speed near the explosion stroke. The ideal ignition timing A _dv determined by this method is shown by a solid line in FIG.

However, in the conventional ignition timing control method using a microcomputer, taking into account the calculation processing time of the microcomputer, the intake negative pressure or intake air amount, and the engine speed signal are set to a specific crank angle based on the engine top dead center signal. The information is input into a microcomputer at the time of each injection, and the above processing is performed to determine the opening time of the fuel injection valve, that is, the amount of fuel to be injected, and the necessary ignition timing. Therefore, for example, as shown in Figure 4, even if the throttle valve suddenly opens during the intake stroke of No. 1Cyl and the suction negative pressure P _B changes from P ₂ ' to P ₁ , the microcomputer For the reasons mentioned above, the P _B value before No.1Cyl, that is,
P ₄ ′ is incorporated. At the same time, the engine speed N is
N ₃ ′ values have been captured. Therefore, No.1Cyl
The ideal value for the ignition timing is a _steady value (~
A ₃ ′, ~A ₂ ′), whereas it remains at the steady value before acceleration, as shown by the dashed line value. Similarly, the next intake stroke, No.
Even in 3Cyl, the ignition timing is determined by the P ₂ ′ and N ₄ ′ values, so ideally, the ignition timing of A ₃ determined from P ₃ and N ₃ is desired, but if the ignition timing was previously steady. The value remains the same. Furthermore, in the next intake stroke, No. 4Cyl, the ignition timing is determined by P ₁ and N ₂ '. Here, since N ₂ ′=N ₁ ,
It is the same value as A ₁ determined by P ₁ and N ₁ .
However, ideally the value A ₄ determined by P ₄ and N ₄ is desirable. Furthermore, the next intake stroke, No.2Cyl
is determined by P ₃ and N ₁ , and P ₁ > P ₃ ,
Since N ₂ ′=N ₁ , the ignition timing changes further compared to No.4Cyl. However, ideally A ₂ determined by P ₂ and N ₂ is desirable. In this way, sequentially,
The ignition timing controlled with respect to the ideal ignition timing has a characteristic with a delay, but as P _B and N become saturated, the two come to match.

As detailed above, it has been impossible to obtain characteristics that meet the requirements of the engine during accelerated operation using conventional ignition timing control methods. The same can be said for other types of institutions as well.

Figure 5 shows a 4-cycle 6-cylinder engine with 1 revolution per rotation.
This is the case with injection.

The data that determines the engine operating state is acquired every revolution as D ₁ , D ₂ , D ₃ to _{D o} . With respect to acceleration changes, the ideal ignition timing becomes A ₁ from P ₁ and N ₁ , and A ₅ from P ₅ and N ₅ using the same determination method as in the case of FIG. On the other hand, in the conventional method, the result as shown by the broken line in FIG. 5 is obtained by the same method as in FIG. 4. Therefore, a large deviation between the two temporarily occurs, which is undesirable.

As mentioned above with reference to FIGS. 4 and 5, the ignition timing during acceleration is controlled to a value that is significantly different from the required value in the conventional system. Therefore, in the present invention, the following method is used to control the ignition timing to match the required value.

Here, for ease of explanation, a detailed explanation will be given using a part of FIG. 4.

Ideal ignition timing in No.1Cyl's explosion stroke C1
A1 is the intake negative pressure P ₁ in the latter half of the intake stroke S1 and the explosion stroke
As mentioned above, it is desirable to determine the engine speed _N1 near the start of C1. Here P ₁
If the data is input into the microcomputer at a crank angle slightly past bottom dead center, there will be enough time to determine the ignition timing, even considering the calculation processing time. On the other hand, it is desirable for _N1 to be a value immediately before or near the ignition, and even if this value is imported into a microcomputer, considering the calculation processing time, it is impossible to use it as data for determining the ignition timing of the C1 explosion stroke. be. Therefore, if we take in N ₂ ′ at the same crank angle as in the case of P ₁ , then
It can be used as C1 data. However, there is a difference in crank angle of 180° between N ₂ ′ and N ₁ , and the change in absolute value between N ₂ ′ and N ₁ cannot be compensated for. Therefore, in the present invention, the following method has been adopted in order to achieve even finer ignition timing control. In other words, a constant crank angle ΔθC between crank angles θC ₁ and θC ₁ ′, which are slightly past top dead center and bottom dead center, and crank angles θC ₂ and θC ₂ ′, which are further past an arbitrary angle, passes through the crank angle sensor. The time required to do this is input into the microcomputer as data each time, and T ₁ is determined by extrapolating from T ₄ ' and T ₂ ' in FIG. In other words, T ₂ ′ is the time taken this time T _o , T ₄ ′ is the time taken last time T _o-1 , T _o , _the predicted time T _e
Then, T _e = T _o + X (T _o − _{T o-1} ) …(1). Here, X is a constant with a certain weight.

Therefore, the engine speed N ₁ can be determined as N ₁ =K/T _e (K: constant) (2).

As described above, the true suction negative pressure during the intake stroke
P ₁ and the engine speed N ₁ near the beginning of the explosion stroke obtained by extrapolation, it is possible to output the ignition timing that almost matches the required value to the ignition timing control device.

The next intake process is No.3Cyl, No.4, No.2
can also be performed sequentially using the same method, so the explanation will be omitted here.

A specific example for detecting the above-mentioned ΔθC is shown in FIGS. 6a and 6b. The crank gear 50 is installed at a location equivalent to the movement of the crankshaft, such as by being directly connected to the crankshaft or installed inside a distributor. The crank gear 50 is provided with a top dead center mark 51a and a bottom dead center mark 51b for indicating top dead center or bottom dead center. This mark is at the true top, slightly behind the bottom dead center position,
That is, the position may be in the opposite direction to the rotation direction. Moreover, phase point marks 52a and 52b are arranged at positions further delayed from the bottom dead center mark. Although both marks are detected by the crank angle sensor 53, it is desirable that these two mark signals can be detected separately. Suction negative pressure, engine speed,
This is because when inputting individual data such as ignition timing into a microcomputer, it is most suitable to use the crank angle top and bottom dead center signals as references. Therefore, in the present invention, to account for the difference between the two marks, the installation position of the gear in the thickness direction is changed (FIG. 6a), and two crank angle sensors are installed for each. However, data acquisition is better,
Of course, there is no need to do this if the bottom dead center or any other location is acceptable. As shown in FIG. 6b, the signal thus detected has a waveform in which the top and bottom dead centers are signal a, and the phase point is signal b.
Therefore, both signals are processed to obtain a signal c, a clock pulse is generated during the pulse open time width of the signal c, and the accurate time in between is counted by counting the number of clock pulses. In other words, the required time T between ΔθC described above can be counted.

Although the method for highly accurate control of the ignition timing during acceleration operation has been described above, it is desirable to perform fine compensation control in the same way for controlling the fuel injection amount.

FIG. 7 shows the deviation characteristics between the required fuel injection amount during acceleration operation and the controlled injection amount when the fuel injection amount of a 4-stroke, 4-cylinder engine is calculated based on suction negative pressure.

When acceleration starts in the middle of the intake stroke of No. 1Cyl, the amount of air taken in is determined by P ₁ and the cylinder volume. Since the cylinder volume at position P ₁ is always constant, if P ₁ is detected accurately, the true amount of air taken in can be known. For the true amount of air determined in this way,
The amount of fuel required to obtain a flat air-fuel ratio characteristic is 7th.
The result will be as shown by the solid line in the figure. On the other hand, in conventional microcomputer control, data (in this case, suction negative pressure) is taken into the microcomputer at a crank angle of 180 degrees or more before fuel injection, taking calculation processing time into consideration. That is, for the injection amount in the intake stroke of S1, the amount of air is calculated from the intake negative pressure value at or before _P4 , and the amount of fuel is determined. Therefore, the injection amount differs from the true required injection amount by P ₄ −P ₁ . The same holds true for the next intake stroke, No. 3, as well as No. 4 and No. 2, and the controlled fuel injection amount becomes as shown by the broken line in FIG. Therefore, unless the deviation between the solid line and the broken line is eliminated, optimal control during accelerated operation is impossible.

The present invention attempts to eliminate this deviation in the following manner. i.e. the true value in the intake stroke of S ₁
P ₁ is obtained by extrapolating from P ₃ and P ₄ ' in FIG. In other words, the suction negative pressure that takes in P ₃ ′ this time
P _o , P ₄ ′ is the previously taken suction negative pressure with respect to p ₃ ′
_{P e ​ ​}
Then, P _e = P _o + Y (P _o − _{P o-1} ) …(3). Here, Y is a weighting coefficient and a value of 0.5 to 2.0 is calculated. By repeating this process sequentially, it is possible to obtain P _B close to the true value.

FIG. 8 shows the deviation characteristics between the required fuel injection amount and the control amount during acceleration in a 4-stroke, 6-cylinder engine with two injections per revolution. As in the case of Figure 7, it is clear that there is a large deviation value among the profiteers. Even in this case, the control amount close to the required value can be obtained by the arithmetic processing of the present invention described above.

FIG. 9 shows the flowchart.

As described above, the ignition timing and fuel injection amount during acceleration operation can be controlled with characteristics that substantially match the requirements of the engine.

[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 shows details of the computer of FIG. FIG. 3 is a block diagram of another internal combustion engine to which the present invention is applied. FIGS. 4 and 5 are explanatory diagrams of the conventional ignition timing calculation method and required characteristics. Chapter 6a,
Figure b is a diagram showing a specific crank angle interval detection means which is one of the embodiments of the present invention. Figures 7 and 8
The figure is an explanatory diagram of a conventional fuel amount calculation method and required characteristics. Figure 9 is a flowchart of the present invention, Figure 10
The figure is a configuration diagram of the present invention. 4...Pressure sensor, 5...Fuel injection valve, 14...
...Crank angle sensor, 15...Ignition coil, 16
...Microcomputer.

Claims (1)

[Claims for Utility Model Registration] Sensor means for monitoring the operating state of the engine, including an intake negative pressure sensor; a fuel injection valve for supplying fuel to the internal combustion engine; A control device for an internal combustion engine, comprising: a data processing unit that generates a signal for controlling an injection valve; and sampling means that samples a signal representing an output signal of the suction negative pressure sensor at a predetermined timing; a storage means for storing data; one signal data P _o read out in relation to the suction negative pressure and the previously stored signal data P _o-1;
a suction negative pressure calculation means for calculating a predicted suction negative pressure signal P _e predicted based on the formula P _e = P _o + Y (P _o − _{P o-1} ) Y: constant; and the calculated suction negative pressure. A control device for an internal combustion engine, comprising an injection amount calculation means for determining a fuel injection amount signal based on a signal, and a drive means for applying the calculated fuel injection amount signal to the fuel injection valve. .