JPH06137200A - Control device for engine - Google Patents

Abstract

PURPOSE:To surely correct a delay element and wasteful time by correcting at least one of the delay element and the wasteful time in a preset model type when a detection value of an engine parameter of engine load, engine speed, etc., with a large coefficient of variation in a predetermined time, CONSTITUTION:A device is provided with the first detecting means P1 for detecting the first parameter of intake air temperature, engine water temperature, etc., with a small coefficient of variation, second detecting means P2 for detecting the second parameter of an engine load, engine speed, etc., with a large coefficient of variation and a means P4 of modeling an engine operation condition for controlling an engine control amount to further store a preset model type. The device is provided with a means P3 for calculating the engine control amount based on a detection value of each detecting means P1, P2 and the model type stored by the memory means P4. Further, the device is provided with a means P6 for correcting at least one of a delay element and a waste time in the model type when the detection value of the second engine parameter is smaller than a preset value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modern control theory (modern control) of, for example, the fuel injection amount during lean burn and the ISC valve operation amount during idle speed control (ISC) that converges the actual rotation speed to an idle target rotation speed. control t
heory) related to the control device of the engine that controls based on.

[0002]

2. Description of the Related Art Conventionally, as an engine control apparatus of the above-mentioned example, there is an apparatus described in Japanese Patent Laid-Open No. 3-31549. That is, a model expression of modern control is previously stored in the storage means for the purpose of controlling the fuel of the engine, and when the operation amount of the fuel adjusting member is largely changed in order to cope with the variation and the secular change of the fuel adjusting member, A fuel injection control device configured to correct the fuel injection control at all times by correcting the modern control model formula (updating the differential gain) according to the difference between the calculation result of the reference model and the operation amount of the fuel adjusting member. Is.

This conventional device has an advantage that the fuel injection control can always be accurately performed by modifying the model expression of modern control, but the above-mentioned modification of the model expression irrespective of the calculation load of the CPU. Instead, it is executed when the operation amount of the fuel adjustment member changes significantly, so
The model formula is corrected even when the detection amount of the engine parameter, which has a large fluctuation rate within a predetermined time such as the engine load and the engine speed, is large.
When the CPU calculation load is large and the model formula is corrected, there is a problem that the model formula cannot be surely corrected because of the calculation capacity of the CPU.

[0004]

SUMMARY OF THE INVENTION According to the first aspect of the present invention, when the detection amount of an engine parameter, which has a large fluctuation rate in a predetermined time such as engine load and engine speed, is small, in other words, the CPU Delay factor (order lag elem
It is an object of the present invention to provide a control device for an engine capable of surely correcting the above-mentioned delay element and dead time by correcting at least one of ent) and dead time.

The invention according to claim 2 of the present invention, together with the object of the invention according to claim 1, has a delay element in the above model formula when the engine speed is low and the CPU has a sufficient calculation capacity. Another object of the present invention is to provide an engine control device capable of reliably correcting dead time.

[0006]

According to a first aspect of the present invention, a first engine parameter for detecting a first engine parameter having a small variation rate within a predetermined time, such as an intake air temperature and an engine water temperature, is detected.
Detecting means, second detecting means for detecting a second engine parameter having a large fluctuation rate within a predetermined time such as engine load, engine speed, and the like, and a model of the operating state of the engine for controlling the engine control amount. And storage means for storing a preset model expression, and calculation means for calculating an engine control amount based on the detection values of the detection means and the model expression stored by the storage means. In the engine control device, a determination unit that determines that the detected value of the second engine parameter is smaller than a set value, and the second unit based on the determination result of the determination unit
When the detected value of the engine parameter is low, the engine control device is provided with a correction means for correcting at least one of the delay element and the dead time in the model formula.

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the invention, an engine in which a condition that the detected value of the second engine parameter is small is set when the engine speed is low It is a control device of.

[0008]

According to the invention described in claim 1 of the present invention, as shown in the claim correspondence diagram of FIG. 5, the above-mentioned first detecting means P1 changes the intake air temperature, the engine water temperature, etc. within a predetermined time. The first engine parameter having a small rate is detected, and the second detecting means P2 described above detects the second engine parameter having a large variation rate in a predetermined time such as the engine load and the engine speed. The calculating means P3 calculates the engine control amount by using the detection values from the detecting means P1 and P2 described above as variables (parameters) based on the model formula stored in advance in the storage means P4. Based on the output of the detecting means P2, the judging means P5 judges that the detected value of the second engine parameter is smaller than the set value C.
When the PU calculation load is light, the correction means P6 described above corrects at least one of the delay element and the dead time in the model formula.

Therefore, it is possible to update the model formula corresponding to the variation of parts and aging so as to always perform proper engine control, and of course, when the calculation load of the CPU (calculation means described above) is light. Since at least one of the delay element and the dead time in the equation is corrected, there is an effect that the delay element and the dead time described above can be surely corrected.

According to the second aspect of the present invention,
In addition to the effect of the invention according to claim 1, the condition that the detected value of the second engine parameter is small is set when the engine speed is low, so the engine speed is low,
When the CPU has a sufficient calculation capacity, it is possible to reliably correct at least one of the delay element and the dead time in the model formula.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. The drawing shows a control device for an engine. In FIG. 1, an air flow sensor is connected to the rear of an air cleaner for purifying intake air, and the air flow sensor is configured to detect the intake air amount. A throttle body 1 is connected to the rear position, and a throttle chamber 3 in the throttle body 1 is provided with a throttle valve 3 for controlling the intake air amount. A surge tank 4 as an expansion chamber having a predetermined volume is connected to the intake passage downstream of the throttle valve 3, an intake manifold 6 communicating with an intake port 5 is connected downstream of the surge tank 4, and the intake manifold 6 is connected to the intake manifold 6. An injector 7 is arranged on the manifold 6.

On the other hand, an intake valve 12 and an exhaust valve 13 which are opened / closed by a valve mechanism including an intake cam 10 and an exhaust cam 11 are connected to the intake port 5 and the exhaust port 9 which communicate with the combustion chamber of the engine 8 as appropriate. And a spark plug (not shown) having a spark gap facing the combustion chamber.

Exhaust passage 1 communicating with the above-mentioned exhaust port 9
4, a linear O2 sensor 15 as an air-fuel ratio sensor is arranged, and a catalytic converter 16 for making harmful gas harmless, a so-called catalyst, is connected to the rear of the exhaust passage 14.

Further, a bypass passage 17 for bypassing the above-mentioned throttle valve 3 is provided, and an ISC valve 18 as an ISC (idle speed control) mechanism is provided in this bypass passage 17.

An optimal regulator for modern control (optimal re
CPU 20 corresponding to a gulator) includes a brake switch 21, a neutral switch 22, and an idle switch 2
3, feedback of the calculated fuel injection amount based on various necessary signal inputs from the tachograph 24, the linear O2 sensor 15 (corresponding to the output from the engine to be controlled) and others according to the program stored in advance in the ROM 25. The injector 7 is driven based on the correction coefficient CFB, and the RAM 26 stores the modern control model formula (first-order delay model with dead time) shown in the following equation 1.

[0016]

[Equation 1]

Where x is a controlled object
Output from the engine as ()
), The air-fuel ratio A /
F K is the number of samples a is a delay element (corresponding to the delay of the control system) L is dead time (corresponding to the detection delay of the linear O 2 sensor 15) u is an input to the engine as a control target (control inpu)
t)), when applied to the lean burn control, the above-mentioned feedback correction coefficient CFB is used. Here, the above-mentioned CPU 20 has a large fluctuation rate of the engine load CE, the engine speed Ne, etc. within a predetermined time.
Detecting means for detecting the engine parameter of the first engine (see the first step S1 in the flowchart of FIG. 2) and the first detecting means for detecting the first engine parameter having a small fluctuation rate of the intake air temperature, the engine water temperature, etc. within a predetermined time. Detection means (specifically, intake air temperature sensor, water temperature sensor, etc.) and the second
Calculation means for calculating the engine control amount based on each detection value of the detection means and the model formula (CPU 20 itself), and determination means for determining that the detection value of the second engine parameter is smaller than the set value (Fig. When the detected value of the second engine parameter is small based on the determination result of the determination means (specifically, the engine speed is low and stable). ) Also serves as a correcting means (see steps S4 and S5 in the flowchart of FIG. 2) for correcting the delay element a and the dead time L in the model expression of the modern control.

The model control process of modern control in the engine control device thus constructed will be described in detail below with reference to the flow chart shown in FIG. First step S
1, the CPU 20 turns on the brake switch 21, the neutral switch 22, and the idle switch 23 based on the inputs from the brake switch 21, the neutral switch 22 (or the inhibitor switch), the idle switch 23, and the tachograph 24. It is detected whether or not all the conditions of the mileage of 500 km are satisfied and within a predetermined time after the engine 8 is restarted. That is, it is detected whether or not the condition that the engine speed is low and stable in the idle state and the fuel injection interval is long is satisfied, and when all the conditions are satisfied, the process proceeds to the next second step S2. However, when the conditions are not satisfied, it waits until all the above conditions are satisfied.

In the above-described second step S2, the CPU 20 determines that the detected value of the second engine parameter, such as the engine load CE and the engine speed Ne, which has a large fluctuation within a predetermined time, is smaller than the set value. CPU20
It is determined that the calculation load of is a light load, and the test mode is entered.

Next, in a third step S3, the CPU 20 changes the fuel injection pulse stepwise, the pulse width at that time and the response of the linear O2 sensor 15, that is, the above-mentioned [Equation 1].
The values corresponding to the input u and the output x indicated by are stored.

Next, in a fourth step S4, the CPU 20 corrects the parameters of the model formula, that is, the delay element a and the dead time L based on the above data. This modification is performed as follows. First, AF (exhaust air-fuel ratio) is assigned to x in [Equation 1] and CFB (feedback or correction coefficient) is assigned to u.
Is substituted and then converted into a concrete model formula shown in [Equation 2].

[0022]

[Equation 2]

With respect to the above-mentioned [Equation 2], the evaluation criterion I shown in [Equation 3] is set next, and the parameters a and L that minimize this are optimized by the optimal design method (least square method, steepest descent method, etc.). Ask by.

[0024]

[Equation 3]

In the above [Formula 3], x = AF and u =
Since it is CFB, this equation of [Equation 3] becomes the following equation of [Equation 4].

[0026]

[Figure 4]

When the parameters (delay element a, dead time L) that minimize the evaluation criterion I are obtained in the above-mentioned fourth step S4, the CPU 20 completes the modification of the model formula in the following fifth step S5. , In the next sixth step S6, the CP
U20 releases the test mode.

As described above, when the calculation load of the CPU 20 is light, the delay element a and the dead time L in the model formula of the modern control are corrected, so that the delay element a and the waste time are not affected to other calculations of the CPU 20. There is an effect that the time L can be corrected with certainty. In addition, under the condition that the detected value of the second engine parameter is smaller than the set value,
Since it is set when the engine speed Ne is low, when the engine speed Ne is low and the calculation capacity of the CPU 20 has a margin, the delay element a and the dead time L in the model formula of the modern control can be reliably corrected. Therefore, it is possible to update the model formula corresponding to the variation of parts and the secular change and always perform appropriate engine control.

In the above embodiment, the process of correcting the lean burn control model formula has been described with the output from the controlled object as the air-fuel ratio A / F and the input to the controlled object as the feedback correction coefficient CFB. Next, referring to FIG. 3 and FIG. 4, the output from the control target is set to the engine speed N.
An apparatus and process for correcting the model formula for idle speed control in which the input to the control target is the ISC valve operation amount (duty value) will be described.

In this embodiment, as shown in FIG.
The engine speed Ne from an engine speed sensor provided at one end of the intake camshaft is input to the CPU 20 corresponding to the optimum regulator for modern control, and CP
U20 outputs the ISC valve operation amount (duty value) Du to the above-mentioned ISC valve 18. RAM2
6 then stores the modern control model formula (second-order lag model) shown in [Equation 5].

[0031]

[Equation 5]

Where x is the output from the engine as the control target, and when applied to the idle speed control, the engine speed Neu is the input to the engine as the control target and when applied to the idle speed control. Is an ISC valve operation amount (duty value) a, b, c are delay elements (corresponding to signal delay) Here, the CPU 20 changes the engine load CE, the engine speed Ne, etc. within a predetermined time. Second with a high rate
Second detection means for detecting the engine parameter (see first step S11 in the flowchart of FIG. 4),
First detection means (specifically, an intake temperature sensor, a water temperature sensor, etc.) for detecting a first engine parameter, such as an intake air temperature, an engine water temperature, which has a small fluctuation rate within a predetermined time, and each of the second detection means. Calculation means for calculating the engine control amount based on the value and the model formula (CPU 20 itself)
And a determination unit that determines that the detected value of the second engine parameter is smaller than a set value (see second step S12 in the flowchart of FIG. 4), and the second engine based on the determination result of the determination unit. When the detected value of the parameter is small (specifically, the engine speed is low,
And stable), the correction means for correcting the delay element and the dead time (see αβγ and η in [Equation 6]) in the model expression of the above modern control (see steps S14 and S15 in the flowchart of FIG. 4). Also serves as.

Since the other structure is the same as that of the previous embodiment, the same parts as those in FIG. 1 are designated by the same reference numerals and symbols in FIG.

The model control processing of the modern control in the engine control device thus configured will be described in detail below with reference to the flow chart shown in FIG. First step S
At 11, the CPU 20 turns on the brake switch 21, the neutral switch 22, and the idle switch 23 based on the inputs from the brake switch 21, the neutral switch 22 (or an inhibitor switch), the idle switch 23, and the tachograph 24. It is detected whether or not all the conditions of the mileage of 500 km are satisfied and within a predetermined time after the engine 8 is restarted. That is, it is detected whether or not the engine speed is low and stable in the idle state, and when all the conditions are satisfied, the process proceeds to the next second step S12, and when the conditions are not satisfied, waits until all the conditions are satisfied. .

In the above-mentioned second step S12, the CPU 20
Determines that the detected value of the second engine parameter, such as the engine load CE and the engine speed Ne, which has a large fluctuation rate within a predetermined time is smaller than the set value, in other words, the CPU 2
It is determined that the calculation load of 0 is a light load, and the test mode is entered.

Next, in the third step S13, the CPU 20 changes the operation amount (duty value) Du of the ISC valve 18 stepwise, and the response of the duty value Du and the engine speed Ne at that time, that is, the above-mentioned [Equation 5]. The values corresponding to the input u and the output x indicated by are stored.

Next, in a fourth step S14, the CPU 20 corrects the parameters of the model formula, that is, the delay element αβγ and the dead time η based on the above data. This modification is performed as follows. First, the above-mentioned second-order differential equation of [Equation 5] is replaced with the discrete differential equation shown in [Equation 6].

[0038]

[Equation 6]

Where αβγ is a second-order lag element (corresponding to signal delay, corresponding to a, b, and c in Equation 5) η is dead time (corresponding to response delay of engine speed) K is the number of samples Next, with respect to the above-mentioned [Equation 6], the evaluation criterion I shown in [Equation 7] is set, and the parameter that minimizes this is obtained by the optimal programming method.

[0040]

[Equation 7]

In the above [Formula 7], x = Ne, u =
Since it is Du, the equation of [Equation 7] is the following equation of [Equation 8].

[0042]

[Equation 8]

That is, in the above-mentioned fourth step S14, the parameter that minimizes the evaluation criterion I in the above [Equation 8] is obtained.

In the above-mentioned fourth step S14, the evaluation criterion I
When the parameters (second-order lag element αβγ, dead time η) that minimizes C are obtained, in the next fifth step S15, C
The PU 20 completes the modification of the model formula, and in the next sixth step S16, the CPU 20 releases the test mode.

As described above, when the calculation load of the CPU 20 is light, the second-order lag element αβγ in the model formula of the modern control,
Since the dead time η is corrected, there is an effect that the second-order lag element αβγ and the dead time η can be surely corrected without hindering other calculations of the CPU 20. In addition, since the condition where the detected value of the second engine parameter is smaller than the set value is set when the engine speed Ne is low, when the engine speed Ne is low and the calculation capacity of the CPU 20 has a margin, The second-order lag element αβγ and the dead time η in the control model formula can be reliably corrected. Therefore, it is possible to update the model formula corresponding to the variation of parts and the secular change and always perform appropriate engine control.

In the correspondence between the configuration of the present invention and the above-described embodiment, the first detecting means of the present invention corresponds to the intake air temperature sensor, the water temperature sensor, etc. (neither is shown) of the embodiment,
Similarly, the second detecting means corresponds to the first steps S1 and S11 controlled by the CPU 20, and the calculating means is the CPU.
20, the storage means corresponds to the RAM 26, and the determination means corresponds to the second step S2, S1 under the control of the CPU 20.
2, the correction means corresponds to steps S4, S5, S14, and 15 under the control of the CPU 20, but the present invention is not limited to the configuration of the above-described embodiment.

[Brief description of drawings]

FIG. 1 is a system diagram showing an engine control device of the present invention.

FIG. 2 is a flowchart showing a model correction of lean burn control.

FIG. 3 is a system diagram showing another embodiment of the engine control device of the present invention.

FIG. 4 is a flowchart showing correction of a model formula of idle speed control.

FIG. 5 is a complaint correspondence diagram.

[Explanation of symbols]

 20 ... CPU (calculation means) 26 ... RAM (storage means) S1, S11 ... First step (second detection means) S2, S12 ... Second step (determination means) S4, S5 ... Correction means S14, S15 ... Correction means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location F02M 69/32 F02D 41/14 330 A 8011-3G 41/16 A 8011-3G

Claims (2)

[Claims] 1. A first detecting means for detecting a first engine parameter, such as an intake air temperature and an engine water temperature, which has a small fluctuation rate within a predetermined time, and a fluctuation rate of an engine load, an engine speed, etc. within a predetermined time. Second detection means for detecting a large second engine parameter, storage means for modeling the operating state of the engine for controlling the engine control amount, and storing a preset model expression, and the above-mentioned detection means. An engine control device is provided with a calculating means for calculating an engine control amount based on a detected value of the means and a model formula stored by the storing means, wherein the detected value of the second engine parameter is a set value. When the detection value of the second engine parameter is small based on the determination means for determining that it is smaller and the determination result of the determination means, the delay in the model formula is delayed. The engine control system and a correction means for correcting at least one element and dead time. 2. The engine control device according to claim 1, wherein the condition that the detected value of the second engine parameter is small is set when the engine speed is low.