JPH02173334A - Adaptable control method for engine - Google Patents

Abstract

PURPOSE:To heighten a control quality when a fuel supply quantity is controlled on the basis of the attachment rate of fuel to an air intake pipe wall surface and the evaporation rate of an attached fuel, by surmizing the attachment rate and the evaporation rate from an air fuel ratio or a fuel injection quantity or the like, and correcting the attachment rate and the evaporation rate calculated as above on the basis of a surmize result. CONSTITUTION:A parameter calculating means 13 which calculates the rate (an attachment rate) of an injected fuel being attached to an air intake pipe wall surface from the various detection amounts of an engine operation condition, and the rate (an evaporation rate) of an attached fuel evaporating at a unit time, is equipped, and on the basis of its output, the control of a fuel quantity supplied to each cylinder is conducted by means of a fuel injection controlling means 12. At such a controller as this, a parameter surmizing means 14 which surmizes the attachment rate and the evaporation rate from such time system data as an exhaust gas air fuel ratio, a fuel injection quantity, a measured air quantity or the like, is provided. And on the basis of its surmize result, the opposing relation of various detection quantities, the attachment rate and the evaporation rate is arranged to be made to be corrected by means of a parameter characteristic correcting means 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection control device for an automatic +1E engine, and particularly to an adaptive engine control method suitable for automatically setting control parameters thereof.

[Conventional technology]

The conventional device is disclosed in Japanese Patent Application Laid-Open No. 58-8238, 60-20.
1.042, 60-126: (As described in Publication No. 37, the adhesion rate is the rate at which the injected fuel adheres to the intake pipe wall, and the rate at which the fuel attached to the intake pipe wall evaporates in about m time. The correspondence between the evaporation rate or the removal rate, which is the rate at which adhering fuel is carried away to the cylinder per unit time, and various detected quantities of the engine such as intake air amount and intake pipe internal pressure is determined in advance, and this correspondence is used. In other words, the control parameters adhesion rate and evaporation rate (or removal rate) are calculated from various detected amounts of the engine using the correspondence relationship determined in advance. The fuel injection amount is then determined based on the calculation results.

[Problem to be solved by the invention]

The above-mentioned conventional technology has a problem in that it is necessary to calculate parameters such as deposition rate and evaporation rate in advance in various operating ranges through engine tests, which requires a lot of man-hours to develop the control system.

Furthermore, due to individual differences in engine characteristics, it is necessary to match calculated parameters for each engine, which also requires a lot of man-hours.

Further, there is a problem in that no consideration is given to changes in the engine over time, and as time passes, the set parameters deviate from optimal values, resulting in deterioration of controllability.

Furthermore, in the conventional method, consideration is not given to the effects of delays in measuring the amount of air and transportation delays. These delays cause deterioration in controllability during transients. It is thought that it is possible to obtain the desired controllability in a certain area by consolidating this delay into parameters such as deposition rate and evaporation rate, that is, by performing parameter matching. However, there is a problem in that desired controllability cannot be obtained in various areas. In other words, the characteristics of air flow measurement delay are completely different during acceleration and deceleration, so even if parameter matching is performed to obtain the desired controllability during acceleration, controllability may deteriorate during deceleration, or Even if parameter matching is performed, there is a problem in that controllability deteriorates during acceleration.

A first object of the present invention is to provide an adaptive control method for an engine that automatically sets and corrects the above-mentioned parameters in response to individual differences in engine characteristics over time.

A second object of the present invention is to provide an adaptive control method for an engine that compensates for the effect of air flow delay (tQ) and obtains desired controllability in various operating ranges.

[Means to solve the problem]

The first purpose is to determine the adhesion rate, which is the rate at which the injected fuel adheres to the intake pipe wall surface, and the evaporation rate, which is the rate at which the fuel adhering to the intake pipe wall evaporates per unit time, based on various detected amounts of the engine.
Alternatively, in an engine control device that calculates a carry-off rate (the rate at which the adhering fuel is carried away to the cylinder per unit time) and controls the amount of fuel supplied to the cylinder based on the calculated value, a wide-range air-fuel ratio sensor is installed in the exhaust pipe. A parameter estimating means for estimating the deposition rate, evaporation rate, or carry-off rate from the air-fuel ratio measured by the sensor and the air amount measured by the fuel injection amount, and various detections of the engine based on the estimation results. This is achieved by providing a parameter characteristic modification means for modifying the correspondence between the amount and the deposition rate, evaporation rate, or removal rate.

The first and second purposes are to install a wide-range air-fuel ratio sensor in the exhaust pipe, and measure the adhesion rate and evaporation rate from the measured air-fuel ratio, fuel injection amount, and air amount measured by the sensor. By providing a parameter estimating means for estimating the removal rate, and controlling the amount of fuel supplied to the cylinder based on the estimation results of the estimation means in place of the adhesion rate, evaporation rate, and removal rate calculated from various detected amounts. achieved.

The second objective is to determine various detected amounts and adhesion rates.

This is achieved by providing multiple types of correspondence between the evaporation rate and the removal rate depending on the operating situation.

[Effect]

In the means shown in FIG. 1, the parameter estimating means calculates the adhesion rate, which is a model parameter, by, for example, the successive least squares method based on a model representing the fuel flow characteristics in the intake pipe;
The evaporation rate or removal rate is estimated, and this is paired with the measured value of the engine operating state at the time of estimation and sent to the parameter characteristic correction means. The parameter characteristic correction means corrects the correspondence between various detection amounts of the engine, adhesion rate, evaporation rate, and removal rate, which are appropriately determined in advance based on the obtained data, and adjusts the relationship between the engine's various detected amounts and the adhesion rate, evaporation rate, and removal rate. Define the optimal relationship in As described above, even if the initial settings are appropriate, as the number of engine operations increases, parameters such as deposition rate and evaporation rate will be automatically optimized, reducing system development man-hours and reducing individual differences in engine characteristics over time. It becomes possible to adapt to

In the second means, the deposition rate, evaporation rate, and take-off rate are always kept at optimum values under certain operating conditions by the parameter estimating means, so that a similar effect can be achieved.

In the third means, different parameters can be set depending on driving conditions such as during acceleration and deceleration, so desired controllability can be obtained in various driving ranges.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 6.

FIG. 1 is an overall configuration diagram of a first means of the present invention. The conventional device is the parameter calculation means.

In contrast to the previous configuration, which consisted only of fuel injection control means, the new configuration includes parameter estimating means and parameter characteristic modifying means.

The operation of each means will be explained below.

The parameter calculation means calculates the adhesion rate, which is the rate at which the injected fuel adheres to the intake pipe wall surface, and the evaporation rate, which is the rate at which the fuel adhering to the intake pipe evaporates per unit time, from measured values of engine operating conditions such as intake air amount and water temperature. is calculated based on a predetermined correspondence relationship and sent to the fuel injection control means. The fuel injection control means controls the amount of fuel supplied to the cylinder based on the calculated deposition rate and evaporation rate.

The parameter estimation means calculates the adhesion rate, which is a control parameter, from time-series data such as the exhaust gas air-fuel ratio measured by a wide-range air-fuel ratio sensor installed in the exhaust pipe, and the air amount measured by the fuel injection amount.
Estimate the evaporation rate (or removal rate). Parameter estimation can be performed, for example, by applying the successive least squares method to a discrete equation of the following mathematical model expressing the fuel flow characteristics in the intake pipe.

Gze=(IX)・Gi+−・Mi
...11)t Here, Gf: Fuel injection amount (g/s) (conversion value of injected fuel amount to mass flow rate per unit time) Gfe Niji cylinder inflow fuel Jkt (g/s) Mi: Fuel attached to intake pipe wall surface amount(
g) X: deposition rate: evaporation rate (1/s) (or removal rate)
When the relational expression between ie and Gi is derived, the following expression is obtained. Note that central difference is used for continuous difference.

2・Δt 2・Δt Here, Δt: time step k: Time (1 time corresponds to Δt) In equation (3), the error equation is the parameter X.

Since it is linear with respect to -, it is possible to calculate optimal parameters in the sense that the weighted sum of squares of equation errors is minimum.

That is, even if the evaluation index is set as Equation (4), it is possible to calculate X, - for which J is the minimum, and the recursive algorithm is Equations (5) and (6).

φ(k+1) Δ...(6) 2・Δt 2・Δ, but O〈ε〈1 In addition, as a recursive parameter estimation method, (5) (6) In addition to holes, the theory and practice of adaptive control systems (ohm company) P
, 78-P, 86 are also applicable.

(5) According to equation (6), in the current operating state.

In order to estimate and calculate X,-, G i(k ), G
Data of i a(k) is required.

The fuel injection amount Gz(k) is calculated from a command value from the microcomputer to the fuel injection valve. Cylinder inflow fuel amount afeDc)
Since there is no sensor that directly measures this, it is calculated from the measured values of other driving conditions using the following formula.

N・Δt N: Engine rotation speed Here, Qa is the value obtained by applying various processing to eliminate noise and pulsation to the measured value of the air amount upstream of the throttle detected by the air amount sensor in the L-dietronics system. do. In other words, the air amount is used as the basis for determining the fuel injection amount. In the D-dietronics system, the amount of air flowing into the cylinder is calculated based on the intake pipe internal pressure detected by the pressure sensor. This is also the air amount that is the basis for determining the fuel injection amount.

A/F is the exhaust gas air-fuel ratio detected by an air-fuel ratio sensor installed in the exhaust pipe.

ko is the average time from the time when the air-fuel mixture is taken into the cylinder until the combustion gas is exhausted.

Here, 11 steps are assumed to correspond to three steps of piston movement.
) formula.

Note that in order to calculate the amount of fuel flowing into the cylinder using equation (10), the air amount Qa should originally be the amount of air flowing into the cylinder. However, in the L-dietronics system,
The total amount of air passing through the throttle is 8 (the value is used. Also,
Even in the D-dietronics system, the measured value cannot match the true amount of air flowing into the cylinder due to the delay in response of the sensor. (1
In equation 0), the reason why Qa is not the true cylinder intake air amount, but the air amount which is the basis for determining the fuel injection amount in each system is used is as follows. In the conventional method, the desired controllability is obtained by compensating only for the fuel delay, but in reality, there is also a delay in air transportation and measurement, which causes deterioration in controllability during sudden acceleration and deceleration. wake up

The reason for using the air amount as the basis for fuel determination is to solve this problem by consolidating the air delay to a certain extent to X, - to obtain the desired controllability.

Note that in the above method, the measured value of the air-fuel ratio sensor is used as it is to calculate the amount of fuel flowing into the cylinder, but if the response delay of the sensor is large, the optimal X, - cannot be estimated.

In this case, take into account the response delay of the sensor.

It is necessary to estimate this, but this can be done using the following method.

First, the sensor response delay model is assumed to be a fuel-air ratio transfer function model. For example, assuming a first-order delay, the delay model is as follows.

A/Fin: Measured exhaust gas air-fuel ratio The constant ρ in equation (12) measures the response of the sensor output when a predetermined input is applied to the sensor, and calculates the equation error of equation (12) based on input/output time series data. is determined to be the minimum. Expression (13) obtained as above can be expressed as (3)
By combining the formula and the formula in which A/F in formula (10) is set as A/Fout, the fuel injection amount Gi and the measured exhaust gas air-fuel ratio A
/F in A relational expression is obtained. The error equation for this relation is the parameter X.

Since it is linear with respect to 1, the same τ as mentioned above The method allows estimation of,X,−,.

τ This concludes the explanation of the operation of the parameter estimating means. Next, the operation of the parameter characteristic modifying means will be explained. The parameter characteristic correction means uses the estimated parameter Δ where A / F out : X in the true exhaust gas air-fuel ratio means - various detected amounts of the engine that are the basis for calculation Xz (k), Xx (k),...・Based on various predetermined detection amounts XI, X of the parameter calculation means
4 Correct the correspondence between ,... and X, -.

As a correction method for τ, for example, Xt=81°Δ at time. At this time, the state in the parameter calculation means is X1=S
1, X2. = S 21 New X for...
, - are X, - calculated by the following τ equation.

τ X(xx, )un ・=, k)=m−Xo(xx,
xx, ・=r k)Δ+(1−m) ・X(xz, xxt −t k)Here, X1=S1. X2=Sz- 0<m<1 Δτ The reason for not changing is to prevent deterioration of controllability in case estimation is not successful. By repeating parameter correction using the above method, the parameters will gradually converge to the optimal values.

Note that here, the estimated parameters for each operating state are stored for a predetermined period of time or a predetermined number of times,
When a predetermined time has elapsed or a predetermined number has been reached, the average value of the estimated parameters is replaced with the parameter value originally calculated by the parameter calculation means, thereby establishing the correspondence between various detected amounts and control parameters (adhesion rate, evaporation rate). may be modified.

This concludes the explanation of the operation of the control system of the present invention.

Next, the overall configuration of the control system and the operation of the control program when the above configuration is realized by a digital control unit will be explained.

Figure 2 shows the overall configuration of the control system. Here L Jie +
-Applicable to Ronics system.

The control unit includes CUP, ROM, RAM, Ilo, L
It is equipped with an SI, a timer, and a bus that electrically connects them. ■/○, Signals from an air amount sensor, a water temperature sensor, a crank angle sensor, an air-fuel ratio sensor, and a throttle angle sensor are input to the LSI. Also, ■/
○, The LSI outputs a signal to the fuel injection valve. In addition, Ilo, LSI has A on the input side.
/D converter and a D/A converter on the output side.

The timer issues an interrupt request to the CPU at regular intervals, and in response to this request, the CPU executes a control program stored in the ROM.

Next, we will explain the operation of a control program that estimates parameters, which are a feature of the present invention, with reference to FIG. 3, and corrects the correspondence between various detected amounts of the engine and .

First, in step 301, the number of revolutions N(k
), kO is calculated using equation (10).

Next, in step 302, the measured air ff1Q, (k) at the time stored in the RAM and the measured air-fuel ratio A/F'' (k + k o) at the time +ko are read out.

Next, in step 303, G, according to equation (10),
. (k) and store it in RAM.

Next, in step 304, G i (1) HG is stored in the RAM. (j, ) (i =
k −2, kΔ Store in RAM.

Next, in step 305, various detected amounts of the engine, x1. (kL xz(k), xa(k).

Next, in step 306, Δ is stored in the RAM. Read out (k).

Next, in step 307, the data is stored at the address specified by equation (3).

Next, in step 308, the value of k is increased by one.

The process ends with "-" and waits until the next interrupt request is received.

In order to execute the above program, the intake air amount Qa
+Rotational speed N, measured value of air-fuel ratio A/F, fuel injection amount Gz, cylinder inflow fuel amount G ie, and X.

Measured values of variables XI and X2 that serve as the basis for one calculation.

It is necessary to manage the storage, deletion, etc. of data of xa, . . . , but this is executed by a separate program.

] Note that in the above method, the estimated time of the parameter
Since there is a concern about estimation accuracy, a configuration in which the estimated value as shown in FIG. 4 is directly used to control the fuel is not used.

Here, the problem with estimation time is that by the time the parameter X, - is estimated, the delay in estimation is large, the parameter has already deviated from the optimal value for the operating state at that time, so sufficient controllability is not achieved. The problem with estimation accuracy is that if a value that deviates significantly from the optimum value is estimated, controllability will be significantly degraded. If there are no above problems, if the configuration shown in Figure 4 is adopted, the RA
M capacity can be significantly reduced, and there is a possibility of system control.

Next, an embodiment of the third means of the present invention will be described with reference to FIGS. 5 and 6.

FIG. 5 shows the transient characteristics of various air amounts during acceleration and deceleration when the L-dietronics system is targeted. During acceleration, the measured air amount, which is the basis for determining the fuel injection amount, is greater than the cylinder inflow air amount, and the opposite is true during deceleration. The control system to which the present invention is directed attempts to obtain desired controllability by compensating only for the fuel delay, and does not give any consideration to the amount of air. Therefore, in order to obtain the desired controllability, the amount of air on which the fuel injection amount is determined must be the amount of air flowing into the cylinder. However, in reality, a measured air amount different from the cylinder inflow air amount is used. When determining the fuel injection amount based on the measured air amount, it is possible to obtain the desired controllability in a limited area by matching parameters such as deposition rate and evaporation rate, but it is not possible in various areas. Have difficulty. This is caused by the difference in the characteristics of the air amount during acceleration and deceleration as shown in Figure 5, and parameter matching is necessary to obtain the desired controllability (setting the air-fuel ratio to the target value) during acceleration. For example, if the measured air amount is larger than the cylinder inflow air amount and control based on the measured air amount causes the fuel supply amount to be larger than the required value, if the parameters are matched so that the fuel is slightly less, the control will be controlled during deceleration. The air-fuel ratio, which is a quantity, exceeds the target value.

This is because during deceleration, the amount of air flowing into the cylinder is larger than the measured air amount, and with control based on the measured air amount, the fuel amount is smaller than the required value, so the parameters should have been set so that the amount of fuel is slightly larger. This is because it is set to be a small number. In other words, in conventional control systems, during acceleration.

It was difficult to obtain desired controllability in both operating modes during deceleration. The above problems also apply to the D-dietronics system.

To solve this problem, in the present invention, for example, as in the configuration of the control system shown in FIG. 6, one of the acceleration parameter calculation means, the deceleration parameter calculation means, and the output of each means is selected as the parameter calculation means. , and signal selection means for sending the signal to the fuel injection control means.

The acceleration parameter calculation means is a means for calculating control parameters to obtain desired controllability during deceleration, and the deceleration parameter calculation means is means for calculating control parameters to obtain desired controllability during deceleration. be. The correspondence relationships between the above-mentioned means, various detected amounts of the engine operating state, and control parameters are determined in advance so as to obtain desired controllability.

In addition, the signal selection means determines whether the throttle opening is in an acceleration state or a deceleration state based on the deviation between the latest measured value and the value several hours ago, and if it is in an acceleration state, calculates acceleration parameters. If the means is in a deceleration state, the output of the deceleration parameter calculation means is sent to the fuel injection control means.

With the above configuration, separate parameter settings can be made during acceleration and deceleration, making it possible to obtain the ultimate in controllability in various operating regions.

In the above embodiment, only two types of correspondence were provided, but a plurality of types may be provided depending on the magnitude of acceleration/deceleration.

〔Effect of the invention〕

As described above, according to the present invention, as the number of operations increases, the values of the control parameters such as deposition rate and evaporation rate are automatically optimized, thereby reducing the number of man-hours for initial setting of parameters, and improving engine characteristics over time. This has the effect of making it possible to adapt to changes and individual differences.

Further, by providing a plurality of types of relational expressions between control parameters and various detected amounts, there is an effect that desired controllability can be obtained in various operating regions.

[Brief explanation of the drawing]

Fig. 1 is an elliptical diagram of the control system of the present invention, Fig. 2 is an overall configuration diagram of the control system when the present invention is realized by a digital control unit, and Fig. 3 is a diagram of the control program that is a feature of the present invention. Flowchart, FIG. 4 is a block diagram of a control system in another embodiment of the present invention, FIG. 5 is a diagram showing transient characteristics of various air amounts, and FIG. 6 is a control system in still another embodiment of the present invention. FIG.

Claims (1)

[Claims] 1. A wide-range air-fuel ratio sensor is installed in the exhaust pipe, and the rate at which the injected fuel adheres to the intake pipe wall is calculated based on the amount detected by the sensor, including the measured air-fuel ratio, fuel injection amount, and measured intake air amount. A certain adhesion rate and either an evaporation rate, which is the rate at which the fuel adhering to the intake pipe wall evaporates per unit time, or a removal rate, which is the rate at which the adhering fuel is carried away to the cylinder per unit time, are determined in advance. A method for adaptively controlling an engine, characterized in that the correspondence between the detected amount and the deposition rate, the evaporation rate, or the removal rate is corrected based on the estimation result. 2. A wide range air-fuel ratio sensor is installed in the exhaust pipe, and the adhesion rate of the injected fuel to the intake pipe wall surface and the evaporation rate of the adhering fuel are determined from the detected amounts including the measured air-fuel ratio, fuel injection amount, and measured intake air amount by the sensor. , or the rate of adhering fuel being carried away to the cylinder, and controlling the amount of fuel supplied to the cylinder based on the estimation result in place of the adhesion rate, evaporation rate, and removal rate calculated from the detected amount. An adaptive engine control method characterized by: 3. In the adaptive control method according to claim 1, a plurality of types of correspondence relationships between the detected amount and the deposition rate, evaporation rate, and removal rate are provided depending on the operating situation. 4. In the adaptive control method according to claim 1, the estimating process includes a process of compensating for a response delay of the air-fuel ratio sensor. 5. In the adaptive control method according to claim 1 or 2, the measured intake air amount is determined by the L-dietronics system;
and the air amount after performing predetermined processing that is the basis for determining the fuel injection amount in the D-dietronics system. 6. In the adaptive control method according to claim 1, the modifying process includes a process of modifying the correspondence relationship between the detected amount and the parameter so that the estimated parameter gradually converges to a predetermined parameter. Become. 7. In the adaptive control method according to claim 1, the correction process is performed by storing parameters estimated for each driving state for a predetermined period of time or by a predetermined number of parameters, and when the predetermined period of time elapses, or When the predetermined number is reached, the average value of the estimated parameters is replaced with the parameter value estimated for the same driving state, thereby correcting the correspondence relationship between the detected amount and the parameter.