JPH0419377B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an internal combustion engine operating state control device, and more particularly to an internal combustion engine operating state control device that detects internal combustion engine operating parameters and controls the internal combustion engine operating state based on the detected output. This relates to a control device.

One method of controlling the operating state of an internal combustion engine in an automobile or the like is to control the amount of fuel injected into the engine. In this case, the throttle (throttle valve)
The absolute pressure P _BA in the downstream intake manifold is detected by a pressure sensor, and the engine speed is detected by a rotation sensor, and the system responds accordingly using this detection output or a combination of the detection output and other engine operating parameters. This controls the fuel injection time Ti.

Therefore, this manifold absolute pressure P _BA needs to be a value that directly represents the manifold pressure during the engine's intake stroke, but when P _BA changes slowly from cycle to cycle,
Sufficient accuracy can be obtained even if the fuel injection time Ti corresponding to the P _BA value is injected during or before the intake stroke.

However, if the P _BA value changes suddenly, for example when the throttle is suddenly opened, the P _BA value at the measured timing and the P _{BA value} at the actual injection timing will be different.
The difference in value cannot be ignored. Therefore, in the above-mentioned conventional method of determining the injection amount using the measured P _BA value,
When the throttle is suddenly opened, the amount of air during injection is greater than the amount of air at the timing of measuring the P _BA value, so the air-fuel ratio becomes leaner, and when the throttle is suddenly closed, the air-fuel ratio becomes richer. In order to remedy this problem, there is a method of correcting the problem using a throttle opening signal, but it is difficult to obtain sufficient performance and this also poses a problem in exhaust gas purification.

The present invention has been made to solve these conventional drawbacks, and its purpose is to ensure stable engine operating conditions and good operating performance in cases where the absolute pressure inside the intake manifold changes suddenly. The present invention also provides an engine operating state control device that is also useful for purifying exhaust gas.

The operating state control device for an internal combustion engine according to the present invention includes a detection means for detecting the pressure in the intake pipe downstream of the throttle valve of the internal combustion engine, a sampling means for sampling the detection output of the detection means to obtain a current sampling value, and a current sampling value. and a calculation means for calculating a correction value by a predictive calculation of multiplying the difference between the current sampling value and the sampling value before the current sampling by a constant, and adding the current sampling value to the multiplication result value, and determining a control value based on the correction value. and a control means for controlling the operating state of the engine, wherein the calculation means includes a first determining means for determining whether the magnitude of the difference is greater than or equal to a predetermined value; determining means for stopping the predictive calculation and directly using the current sampled value as the correction value when the magnitude of the difference is smaller than a predetermined value; and determining whether or not another operating condition is satisfied when the magnitude of the difference is greater than or equal to the predetermined value. The present invention is characterized in that it includes a second discriminating means for discriminating whether the second discriminating means is the same, and a setting means for setting a constant to a different value other than 0 in accordance with the discriminating result of the second discriminating means.

Embodiments of the present invention will be described below with reference to the drawings.

In the operating state control device shown in FIG. 1, which is an embodiment of the present invention, intake air is supplied from an atmospheric air intake port 1 to an engine 4 via an air cleaner 2 and an intake path (including the inside of the intake manifold) 3. It's becoming like that. A throttle valve 5 is provided in the intake passage 3 so that the amount of air taken into the engine 4 changes depending on the opening degree of the throttle valve 5. In addition, a secondary air passage 6 is connected so as to bypass the throttle valve 5 and communicate from the air cleaner 2 downstream of the throttle valve 5, that is, to the intake manifold.
The secondary air passage 6 is provided with a solenoid valve 7 for idle speed control.

On the other hand, the reference numeral 10 is a throttle opening sensor which is composed of, for example, a potentiometer and which generates an output voltage at a level corresponding to the opening degree of the throttle valve 5. The reference numeral 11 is a throttle opening sensor which is provided downstream of the throttle valve 5 and which generates an output voltage at a level corresponding to the magnitude of the pressure. an absolute pressure sensor that generates an output voltage of
12 is a cooling water temperature sensor that generates an output voltage at a level corresponding to the cooling water temperature of the engine 4; 13 is a crank angle sensor that generates a pulse signal when the crankshaft (not shown) of the engine 4 is at a predetermined rotation angle; 14; is an oxygen concentration sensor that is provided in the exhaust passage 8 and generates an output voltage at a level corresponding to the oxygen concentration in the exhaust gas of the engine 4. 15 is an injector provided in the intake passage 3 near the intake valve (not shown) of the engine 4. Throttle opening sensor 10, absolute pressure sensor 11, cooling water temperature sensor 12,
Each output terminal of the crank angle sensor 13 and the oxygen concentration sensor 14 and each input terminal of the solenoid valve 7 and the injector 15 are connected to a control circuit 16. Also,
An ignition switch 17 and a starter switch 18 are connected to the control circuit 16. The ignition switch 17 supplies power supply voltage to the control circuit 16 when turned on, and the starter switch 18 supplies voltage to a starting motor (not shown) when turned on. ) is supplied to the control circuit 16. Note that a three-way catalyst 9 is provided downstream of the location of the oxygen concentration sensor 14 in the exhaust path 8 of the engine 4.

The control circuit 16 includes a capacitor as shown in FIG.
Oxygen concentration sensor 14 consists of C ₁ , C ₂ and resistor R
a smoothing circuit 19 for smoothing the output voltage of the buffer amplifier 20 connected to the output of the smoothing circuit 19;
A level correction circuit 21 corrects the level of each output of the water temperature sensor 12, throttle opening sensor 10, absolute pressure sensor 11, and amplifier 20, and selectively outputs one of the sensor outputs that have passed through the level correction circuit 21. An input signal switching circuit 22, an A/D converter 23 that converts the analog signal output from the input signal switching circuit 22 into a digital signal, a waveform shaping circuit 24 that shapes the waveform of the output of the crank angle sensor 13, and A counter 25 that measures the time between pulses output from the waveform shaping circuit 24, a level correction circuit 26 that corrects the level of each output of the ignition switch 17 and the starter switch 18, and a level correction circuit 26 that adjusts the output of the level correction circuit 26. A digital input module 27 as an input, and a drive circuit 2 that drives the injector 15 and the solenoid valve 7, respectively.
8, 29, a CPU 30, a ROM 31 and a RAM 32 in which various processing programs are stored, an input signal switching circuit 22, an A/D converter 23, a counter 25, and a digital input module 2.
7. Drive circuit 28, 29, CPU 30, ROM 31
and RAM 32 are connected by a bus line 33. Further, a TDC (top depth center) signal is supplied from the waveform shaping circuit 24 to the CPU 30.

In this configuration, information on the throttle valve opening, intake pressure, cooling water temperature, and oxygen concentration is alternatively sent from the A/D converter 23, information on the engine speed is sent from the counter 25, and information on the ignition speed is sent from the digital input module 27. Information on whether to turn on or off the switch 17 and the starter switch 18 is supplied to the CPU 30 via a bus line 33, respectively. CPU
30 reads each of the above information according to the calculation program stored in advance in the ROM 31, and based on the information, calculates the fuel injection time corresponding to the fuel supply amount from a predetermined calculation formula in synchronization with the TDC signal. . Then, the drive circuit 28 drives the injector 15 for the calculated fuel injection time to
It supplies fuel to the Also, during idling, the idle control amount is calculated from the engine speed and the set idle speed, and the drive circuit 29 intermittently drives the solenoid valve 7 according to the idle control amount, so that the engine speed is adjusted to the set idle speed. The duty of the secondary air amount is controlled so that the amount of air increases.

Figures 3 and 4 show the control circuit 1 shown in Figure 2.
6 is a flowchart showing the operations in step 6. FIG.

Referring to FIG. 3, in the control circuit, first, the intake absolute pressure P _BA is sampled from the A/D converter 23 in synchronization with the TDC signal and read into the CPU 30 as the latest current sampling value P _Bo (step 101). The sampling value P _Bo this time is
It is stored in the RAM 32 for calculation at the time of the TDC signal (step 102), and also stored in the RAM 32 for calculation at the time of the next TDC signal (step 103). After this, the previous sampling value P _B n
-1 and RAM32 are read out (step
104), the difference between the current sampling value P _Bo and the previous sampling value P _B n-1 is calculated, and it is determined whether the absolute value of this difference is greater than a predetermined value ΔP _BG (step 105). . Here, ΔP _BG has a value that is a predetermined multiple of the minimum resolution of absolute pressure P _BA , including 1, and designates a guard value. ｜P _B n−P _B n−1｜
Only in the case of ≧ΔP _BG , the difference between the current sampling value P _B n and the previous sampling value P _B n-1 is multiplied by a constant ψ, and the multiplication result value is set as the current sampling value.
By adding P _B n, the current sampling value
A correction value P _BA of P _B n is calculated (step 106).
Here, the constant ψ is set to an optimal value depending on the operating state of the engine. On the other hand, |P _B n−P _B n−1|<
In the case of ΔP _BG, the current sampling value P _B n is used as it is as the correction value P _BA (step 107).
The correction value P _BA calculated or determined in this way
The fuel injection time of the injector 15 is determined based on the data map etc. stored in the ROM 31 in advance.
Ti is determined (step 108).

The above procedure is sequentially repeated to control the engine operating state. By doing this, if the amount of change in the absolute pressure P _BA inside the manifold during the sampling period is large, |P _B n−P _B n−1|
Since ≧ΔP _BG , the value ψ (P _B n−P _B n−1) corresponding to this amount of change (including polarity and magnitude) is added to the latest current sampling value P _B n to determine the P _BA value. be done. Therefore, when P _BA is changing in the increasing direction, the P _BA value is corrected to increase in advance according to the amount of change, and when P _BA is changing in the decreasing direction, the P _BA value is also corrected to decrease. I will do it. That is, the correction value P _BA is predictively calculated as a predicted value at the time of actual fuel supply according to the sampling value. As a result, the sensor 11 and the calculation control circuit 1
It becomes possible to correct the delay in the operation of the control system of the engine 4, etc., and the delay in the operation of the controlled system of the engine 4, thereby preventing the dilution and enrichment of the air-fuel ratio, which were problems in the past, and purifying the exhaust gas.

The multiplication constant ψ at the time of the above correction is determined by taking into account the operation delays of these control systems and controlled systems, and also taking into account the operating conditions since the operation delays change depending on the operating conditions of the engine.

Next, a case in which the constant ψ is determined depending on the operating state of the engine will be specifically explained.

Referring to FIG. 4, only the differences from FIG. 3 will be described. After the current sampling value P _B n is stored in steps 102 and 103, the previous sampling value P B n-1 is stored together with the previous sampling value P _B n-1. _B n-2 is read from the RAM 32 (step 109), and |P _B n-P _B n-2 | ≧ΔP _BG
It is determined whether or not it is (step 110). ｜P _B
n-P _B n-2｜≧ΔP _BG , engine speed
It is determined whether Ne is less than or equal to the upper limit idle rotation speed N _IDL (step 111). If Ne<N _IDL ,
It is determined whether the throttle valve opening θth is less than the predetermined opening θ _IDL (step 112), and if θth < θ _IDL , the engine operating state is determined to be idle, and the constant φ is set to the predetermined value ψ ₁ . is set (step 113).
If Ne≧N _IDL or θth≧θ _IDL , it is determined that the operating state of the engine is not an idle state, and the constant ψ is set to a predetermined value ψ ₀ that is smaller than the predetermined value ψ ₁ (step 114). Next, using the set constant ψ, in step 106 P _B n + ψ (P _B n - P _B n - 1)
is calculated, and the calculation result becomes the correction value P _BA . On the other hand, if |P _B n-P _B n-2 |<ΔP _BG , the process moves to step 107. Note that the execution of step 110 by the CPU 30 corresponds to the first determination means, and the execution of at least one of steps 111 and 112 corresponds to the second determination means.

In this example, the constant ψ is set large to stabilize the engine speed when the engine is idling, when the driver is likely to feel engine speed hunting, and the constant ψ is set small when the engine is running in a state other than idling. This setting compensates for operational delays in the control system and the controlled system.

The effects of the present invention will be explained below using FIGS. 5 to 12. First, FIG. 5 shows the follow-up characteristics of the absolute pressure P _BA in the manifold when a load is applied in steps during engine idling, where curve 50 shows the change in engine speed over time, and curve 51 shows the change in engine speed over time. ~53 is
The figure shows the change in P _BA over time for manifold internal volumes of 0.25 liters, 1.0 liters, and 4.0 liters, respectively. In addition, Figure 6 shows the state in which the absolute pressure P _BA follows a sinusoidal change in the engine speed (curve 60) when the engine is idling, and curves 61 to 63 indicate the manifold internal volume.
The changes are shown for each case of 0.25, 1.0 and 4.0 liters.

Furthermore, Fig. 7 shows the P _BA follow-up characteristics when the throttle is suddenly closed, where curve 70 shows the change in throttle opening, and curves 71 to 73 show the internal volume 0.25,
This is the tracking characteristic for each case of 1.0 and 4.0 liters.

As can be seen from these figures 5 to 7, the manifold absolute pressure P _BA follows changes in engine speed and throttle opening with a time delay.
The delay increases as the manifold internal volume increases. This delay time is corrected according to the present invention, and the corrected state is shown in FIG.

The figure shows the effect of the present invention when the throttle is suddenly closed, and curves 81 to 84 are the change characteristics of the absolute pressure P _BA when the present invention is not applied.
These are cases where the internal volume is 0.25, 1.0, 2.0, and 4.0 liters. The dashed line curves 85 to 88 represent the present invention.
This is the P _BA tracking characteristic for each case of ψ = 2, 4, 6, and 8 when applied to a 4.0 liter manifold. That is, even with a 4.0 liter manifold, by selecting ψ, particularly from 4 to 6, the corrected P _BA becomes equivalent to that of a 2.0 liter manifold, and is significantly improved.

Figure 9 is another characteristic example showing the effect of the present invention, showing the effect of the reduction in engine speed and constant ψ at clutch off, when decelerating from 2nd speed gear 3000 rpm cruise and clutching off at 1300 rpm. The correction operation of the present invention is disclosed. Note that above 1130 rpm, the fuel is cut off. The solid line shows the change in the engine speed when ψ=6, and the dotted line shows the change in the engine speed when ψ=0, that is, when the present invention is not applied. According to the present invention, hunting in the engine speed is suppressed and the engine speed converges to a substantially constant idling speed. Note that this hunting in the rotational speed is caused by the operation of the AC generator for battery charging.

Figure 10 shows the relationship between the constant ψ and the maximum hunting variation width ΔNe (rpm) in a certain operating state during idling (a state where hunting is likely to occur), and shows the relationship between the manifold internal volume of 1.7, 2.2, 3.2 and
Each case of 4.7 liters is shown. As is clear from the figure, hunting can be suppressed by selecting the value of ψ. It has been confirmed that effective suppression can be achieved even when ψ is approximately 20.

Figure 11 shows the relationship between the intake manifold internal volume and the maximum engine speed change ΔNe,
The values of the constant ψ are shown for each case of 0, 1, 3, 6, 10, and 16. Note that the conditions are the same as in the case of FIG. Again, depending on the value of ψ, hunting is suppressed regardless of the internal volume of the manifold.

Figure 12 shows the optimum constant ψ for the internal volume of the intake manifold and ΔNe at this optimum ψ.
(tpm), and it can be seen that it is sufficient to increase the value of ψ as the volume increases. This is because as the volume of the manifold increases, the delay in the operation of the controlled system increases, so if the multiplication constant ψ for correction is made large, the amount of correction becomes large.

As described above, according to the present invention, stable engine operating characteristics are limited, which also contributes to exhaust gas purification.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of an embodiment of the present invention, FIG. 2 is a specific block diagram of a control circuit in the device shown in FIG. 1, and FIGS. 3 and 4 show engine operating parameters in the device shown in FIG. Flowcharts showing each mode of correction and FIGS. 5 to 12 are experimental data showing characteristics for explaining the effects of the present invention. Explanation of symbols of main parts, 2... Air cleaner,
3...Intake path, 5...Throttle valve, 6...Secondary air passage, 7...Solenoid valve, 8...Exhaust path, 9...
Three-way catalyst, 10...Throttle opening sensor, 11
... Absolute pressure sensor, 12 ... Water temperature sensor, 13 ...
...Crank angle sensor, 15...Injector.

Claims (1)

[Scope of Claims] 1. Detection means for detecting the pressure in the intake pipe downstream of the throttle valve of the internal combustion engine; sampling means for sampling the detection output of the detection means to obtain the current sampling value; and detecting the current sampling value and the current sampling. a calculation means for calculating a correction value by a predictive calculation of multiplying a difference from a previous sampling value by a constant and adding the current sampling value to the multiplication result value; and determining a control value based on the correction value. An operating state control device comprising: a control means for controlling an operating state of an engine; determining means for stopping the prediction calculation and using the current sampled value as the correction value when the magnitude of the difference is smaller than the predetermined value; and determining another operating condition when the magnitude of the difference is greater than or equal to the predetermined value. and a setting means for setting the constant to a different value other than 0 according to the determination result of the second determining means. Device. 2. The operating state control device according to claim 1, wherein the other operating condition is an idle state. 3. The operating state control device according to claim 1, wherein the control value is a fuel injection amount to be injected and supplied to the engine.