JPS6093150A - Learnig control device for air-fuel ratio in electronically controlled fuel injection type internal- combustion engine - Google Patents

Abstract

PURPOSE:To decrease the PI constant to aim at greately enhancing the controllability of the air-fuel ratio of an engine in a learning control device for the air-fuel ratio of the engine, by utilizing a learning compensating coefficient for the feed-back control of the air-fuel ratio to control the base air-fuel ratio so that the latter is made approach the stocichometic air-fuel ratio. CONSTITUTION:A learning control device for the air-fuel ratio of an engine comprises a basic fuel injection amount computing means for computing a basic fuel injection amount in accordance with a constant, the amount of intake-air and an engine rotational speed, an air-fuel ratio feed-back compensating coefficient setting means for comparing an actual air-fuel ratio detected in accordance with a signal from an O2 sensor with the stoichometric air-fuel ratio so that an air-fuel ratio feed back compensating coefficient is set by means of PI control, and a learning compensating coefficient searching means for searching learning compenesating coefficients stored in a map on an RAM, corresponding to the engine running condition. Further, there are provided a learning compensating coefficient renewal means, a fuel injection amount computing means, a drive pulse signal delivering means, a learning log discriminating means and a leaning inclination discriminating means, and thus the learning control device is constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an air-fuel ratio learning control device in an electronically controlled fuel injection internal combustion engine.

<Background Art> In an electronically controlled fuel injection type internal combustion engine, the injection amount Ti is determined by the following equation.

T i = T p x C0EF x α'rs where Tp is the basic injection amount and TP=K x Q/N. K is a constant, Q is the intake air flow rate, and N is the engine speed. C0BF is various correction coefficients.

α is an air-fuel ratio feedback correction coefficient for air-fuel ratio feedback control (λ control) to be described later.

Ts is a voltage correction valve, which is used to correct changes in injection amount of the electromagnetic injection valve due to fluctuations in voltage.

For air-fuel ratio feedback control, 02
A sensor is installed to detect the actual air-fuel ratio, and the slice level determines whether the air-fuel ratio is richer or leaner than the stoichiometric air-fuel ratio, and the fuel injection amount is controlled according to the stoichiometric air-fuel ratio. The above-mentioned air-fuel ratio feedback correction coefficient α is determined and the stoichiometric air-fuel ratio is maintained by changing this α.

Here, the value of the air-fuel ratio feedback correction coefficient α is changed by proportional-integral (PI) control to achieve stable control.

In other words, the output of the 02 sensor is compared with the slice level, and if the air-fuel ratio is higher or lower than the slice level, the air-fuel ratio is rich (lean) without suddenly enriching or reducing the air-fuel ratio. To do this, the air-fuel ratio is controlled to become lean ((rich) by first lowering (raising) it by P, then gradually lowering (raising) it one minute at a time.

However, in a region where λ control is not performed, α is clamped to 1, and a desired air-fuel ratio is obtained by setting various correction coefficients COEF. By the way, if the base air-fuel ratio at α-1 in the λ control region could be set to the stoichiometric air-fuel ratio (λ=1), feedback control would not be necessary.
Actually components (e.g. air flow meter, fuel injection valve, pressure regulator, control unit)
This is because deviations from the base air-fuel ratio λ = 1 may occur due to factors such as variations and changes over time, non-linearity of the fuel injection valve pulse i]-flow characteristics, and changes in operating conditions.

Feedback control is performed.

However, if the base air-fuel ratio deviates from λ-1, it takes time to settle the step in the base air-fuel ratio to λ=1 by feedback control when the operating range changes significantly. For this reason, the KPI constants are made thicker, resulting in overshoot or undershoot and poor controllability.

In other words, if the base air-fuel ratio deviates from λ=1, the air-fuel ratio will be controlled within a range that deviates considerably from the stoichiometric air-fuel ratio.

As a result, the three-way catalyst has to be operated at a point where its conversion efficiency is poor, and not only does the cost increase due to an increase in the amount of precious metal in the catalyst, but the conversion efficiency further deteriorates as the catalyst deteriorates, forcing the catalyst to be replaced. There was a problem that

Therefore, by setting the base air-fuel ratio to λ = 1 through learning, it is possible to eliminate deviations from λ-1 caused by steps in the base air-fuel ratio during transients, and to reduce the PI constant, improving controllability. A learning control device for the base air-fuel ratio was devised to reduce the cost of the catalyst.

That is, a learning correction coefficient α■ corresponding to engine operating conditions such as engine speed and load is stored in the RAM.

When calculating the injection amount Ti, the basic injection amount TP is corrected by α7 as shown in the following equation.

T i = Tp X COE F Xα×αL −1
−'I' 3° Then, the learning of αL proceeds in the next 1,122 steps.

1) Engine operating conditions and α in steady state
and detect.

++) Search for αL that has been learned and stored up to now in accordance with the engine operating conditions.

111) Create a new α from α and αL at a predetermined update rate.
Set and store L.

Furthermore, in Japanese Patent Application No. 58-132894, the present applicant utilized the above-mentioned learning control device, and even in the region where λ control is not performed, the flow rate change due to wear and clogging of the fuel injector, ambient source temperature, pressure noise, etc. We proposed a system that can effectively correct the air-fuel ratio in response to changes in the type (composition) of gasoline.

In other words, in the learning control device described above, if all the learning results deviate in the same direction (rich side or lean side) in the map of learning correction coefficients whose parameter is the engine operating condition in RAM, the minimum deviation Constant for basic injection amount calculation in the direction of modifying the value (so-called constant)
has been modified so that it can respond to changes in the air density of the fuel injector even in areas where λ control is not performed by kneading.

However, in reality, in the learning correction coefficient map, the operating range in which the learning correction coefficient is stored is divided into fine sections in order to improve learning accuracy. Since it is rare for a station to remain in a steady state even if it only passes through it temporarily during driving, it often remains unlearned for a long period of time.

Therefore, it takes a long time for all the learning correction coefficients to deviate from their initial values, and there is little chance that all of them deviate in the same direction, so it is not always possible to correct the constant K well.

<Purpose of the invention> The present invention was made in view of the above circumstances.

The learning results of the learning control device can be used more effectively, and changes in the air-fuel ratio based on various factors in the region where λ control is not performed can be better compensated for, further improving air-fuel ratio control performance. The purpose is to

<Structure of the Invention> Therefore, 1. the present invention includes a basic injection amount calculation means for calculating the basic injection amount from a constant, an intake air flow rate, and an engine rotational speed, as shown in FIG. an air-fuel ratio feedback correction coefficient setting means for setting an air-fuel ratio feedback correction coefficient by proportional-integral control by comparing the actual air-fuel ratio detected based on the signal of the air-fuel ratio; A learning correction coefficient search means for searching a learning correction coefficient stored in a map on the RAM corresponding to the above, an air-fuel ratio feedback correction coefficient setting means for setting an air-fuel ratio feedback correction coefficient, and an engine control unit for determining the engine speed, engine load, etc. A learning correction coefficient search means for searching a learning correction coefficient stored in a map on a RAM corresponding to the operating conditions; and a learning correction coefficient searching means for setting a new learning correction coefficient from the air-fuel ratio feedback correction coefficient and the learning correction coefficient; learning injection amount calculation means for updating data of the same engine operating condition in the RAM with a learning correction coefficient; drive pulse signal output means for outputting a drive pulse signal corresponding to the calculated injection amount to the fuel injection valve;
learning history determining means for determining whether or not a predetermined percentage or more of all learning correction coefficients in a map on the RAM has been updated a predetermined number of times (including once) or more through learning, and when the predetermined percentage or more has been updated; learning tendency determining means for determining whether a predetermined percentage or more of these learning correction coefficients deviate in the same direction from the initial value; The configuration includes constant correction means for correcting the constant accordingly.

Example of implementation Examples will be described below.

Figure 2 shows the hardware configuration. 1, Q1 1 is CPU, 2 is P-ROM, 3 is C for learning control.
MO8-RA, M, 4 is an address decoder. still,
For RAM, 3, key switch OFI? A backup power supply circuit is used to retain the memory contents even after '.

Analog input signals to the CPU 1 for controlling the fuel injection amount include an intake air flow rate signal from the hot wire air flow meter 5, a throttle opening signal from the throttle sensor 6, a water humidity signal from the water temperature sensor 7, and the 02 sensor. There is an exhaust oxygen concentration signal from 8, a battery voltage from battery 9, and a battery voltage from analog input interface 10 and A.
The signal is input via a /D converter 11.

12 is an A/D conversion timing controller.

As digital input signals, there are signals 0N-01i''F from the idle switch 13, the start switch 14, and the neutral switch 15, and these are inputted via the digital input interface 16.

In addition, for example, IRQ (
10) Reference signals for each angle and position signals for each 1° are inputted via the one-shot multi-circuit 18. Further, a vehicle speed signal from a vehicle speed sensor 19 is inputted via a waveform shaping circuit 20.

The output signal (driving pulse signal to the fuel injection valve) from the CPU 1 is sent to the fuel injection valve 22 via the current waveform control circuit 21.
It is now sent to

Here, the CPU 1 executes a program (RO
(stored in M2), performs input/output operations, arithmetic processing, etc., and controls the fuel injection amount.

Next, the flowchart shown in FIG. 3 will be explained.

The basic injection amount TP is determined from the intake air flow rate Q obtained from the signal from the air flow meter 5 at Sl and the engine rotation speed N obtained from the signal from the crank angle sensor 17.
(=KxQ/N) is calculated.

In S2, various correction coefficients C0EF are set.

In S3, the output voltage of the 02 sensor 8 and the slice level (11) lumi pressure are compared, and the air-fuel ratio feedback correction coefficient α is set by proportional-integral control. 1, and in the region where λ control is not performed, it is clamped to α=1.

In S4, a voltage correction numerator s is set based on the pressure of the batch IJ from the battery 9.

In S5, the operating region based on parameters indicating the engine operating state, such as engine speed N and basic injection l (load) Tp, is divided into a plurality of areas, and a map ( RAM3
The area in which the current (N + Tp) exists is searched from (stored in ) and data indicating the area is set in a predetermined location A of the address decoder 40.

In S6, the current (N.

The data in the area where Tp) exists is also searched previously set in address decoder address 40 LA (N
, TP) to determine whether they are the same. If YES, that is, if it is determined that the operating conditions are substantially the same (12), the process advances to S7.

In S7, the output voltage of 02 sensor 8 (see Figure 4) is 8.
After the determination in step 6 becomes YES, it is determined whether or not it has been reversed n times, and in the case of YES, the process advances to S8.

That is, 86.87 is provided to determine whether or not the operating state is in a steady state. If both determinations in S7 are YES, it is determined that the state is in a steady state. Such a steady state determination method is simple and can be performed with high bulk accuracy, but other methods may also be adopted, such as determining whether a predetermined time has elapsed with the vehicle speed constant, the gear position not neutral, and the throttle opening constant. You may. And S6
Alternatively, if any of the determinations in S7 is NO, it is determined that the state is unsteady, and in this case, the process proceeds to S11 without performing the learning from 88 to 810, which will be described later.

In S8, the average value a of the current and past values of the air-fuel ratio feedback correction coefficient α during steady operation is calculated. You can calculate the average value each time the flow is performed, but for example, you can calculate the average value from when the increase/decrease in the air-fuel ratio feedback coefficient α is reversed to when the flow is reversed (13), or when the flow is reversed. The average value of only the value of the air-fuel ratio feedback correction coefficient α may be calculated, and in this way, the control center of α in the steady state can be set more accurately.

In S9, the learning correction corresponding to (N, 'l''p) stored in the area where the above (N, T, ,) of R, AM3 exists from the engine speed N and basic injection t'I'p. The coefficient αL is searched.The values of αL stored in the map are all αL=1 at the time when learning has not started.

In S10, calculation is performed according to the following formula from the learning correction coefficient αL retrieved in S9 and the average value d of the air-fuel ratio feedback correction coefficient α calculated in 88, and the value is set as a new learning correction coefficient αL, Update the value in the corresponding area of the αL map.

αL←αL+Δα/M In addition, Δα represents the deviation amount between a and the reference value Δα=d−αλ
-1, and the reference value αλ=1 is generally (14) 10. Further, M is a constant.

The value of M, which determines the rate at which the learning deviation amount Δα of the learning correction coefficient αL is added, may be constant, but if it is set to a value proportional to the engine speed, the PI control coefficient of α can be adjusted according to the increase in the injection cycle. Since the injection amount can be decreased, more accurate injection amount control can be performed.

Alternatively, the learning correction coefficient may be updated by directly calculating the deviation amount between α and the reference value without averaging the air-fuel ratio feedback coefficient α, and adding the deviation amount by a predetermined percentage.

At 811, the data of the previous area (N, TP) set at address LA indicated by the address decoder 4 is transferred by transferring the data of the current area (N, Tp) set at address A. Update.

Search for αL map from RA and M3 at 812, and search for αL map at 81
In step 3, it is determined whether or not a predetermined percentage or more of all the learning correction coefficients αL stored in the αL map have a history of updating by learning. If the determination at 8130 is YES, the process proceeds to 814, and if the determination (15) at 813 is No, the process proceeds to 820.

In Si4, the learning correction coefficient α updated by learning
It is determined whether the learning correction coefficient αL of L deviates from the initial value to the + (increase) side by a predetermined percentage or more. 81
If the determination in step 4 is YES, the process proceeds to step 816, where the constant is corrected to 0111 by a predetermined percentage or more, and then all learning correction coefficients αL are reversely corrected to the decreasing side by the percentage by which the constant is increased. That is, correction is made so that K×αL=constant.

On the other hand, if the determination in S14 is NO, the process proceeds to 817, and it is determined whether or not a predetermined percentage or more of the learning correction coefficients αL, which have been updated by learning, are deviated from the initial value to the − (decrease) side. Determine whether If the determination in 8170 is YES, the process goes to 818 where the constant is corrected to decrease by a predetermined percentage on the road side only, and then all the learning correction coefficients αL are reversely corrected to increase by the percentage by which the constant is decreased (KXαL). - constant).

If the determination in 813 or 817 is NO, that is, the learning correction coefficient αL that has been updated.

- The percentage of deviation in one direction is on the predetermined side (16
), the process proceeds to 820.

At 820, the injection amount Ti is calculated according to the following equation.

'I' i = Tp X C0EF Xα×αL+T
S Here, in the case of steady state, the learning correction coefficient αL is 8
10 is used, and in the case of a transient state, 8 is used.
10 is used.

The injection amount Ti is calculated as described above, and a drive pulse signal corresponding to the injection amount Ti is given to the fuel injection valve 22 at a predetermined timing via the current waveform control circuit 21.

On the other hand, in the region where λ control is not performed, the air-fuel ratio feedback correction coefficient α is clamped to 1 as described above, and steps 85 to 819 are omitted, so that αr,=] is substantially obtained.

Therefore, the injection amount is given by the following equation.

T i = T'p xcOEF +Ts However, TP
=KXQ/N The constant for calculating the basic injection amount TP is updated when the learning correction coefficient αL of a predetermined rate or more has been updated by learning (17), that is, the value of the learning constant αL is When the reliability is high and more than a predetermined percentage of the learning update t or αL is shifted in one direction, the correction is made, so from the next routine after the correction is made. A constant is used to compensate for changes in the flow rate of the fuel injector 22 and ambient temperature.

Deviations in the base air-fuel ratio due to changes in atmospheric pressure, etc. can be effectively corrected even in a region where λ control is not performed. Especially single point injection (8PI
In the case of the ) system, there is only one fuel injection valve 22, which has a large influence on clogging, etc., so a fuel-safe effect can also be expected.

Here, in the case of the present invention, as described above, the history of update through learning and the learning tendency are determined, and the correction is performed when it is determined that the constant should be substantially sufficiently corrected. Therefore, as shown in the above-mentioned Japanese Patent Application No. 58-132894, there is an opportunity to perform correction more effectively than when constant correction is performed only when all learning correction coefficients αL are shifted in the same direction. increases and is highly practical.

(18) In this embodiment, the learning history is determined by determining whether the learning correction coefficient αL that has been updated by learning at least once is greater than or equal to a predetermined percentage. It may be determined whether the learning correction coefficient αL that has been updated by learning is equal to or greater than a predetermined ratio, and the learning correction coefficient αL
The constants are corrected under conditions with higher reliability.

In addition, in this embodiment, the take of the learning correction coefficient αL is increased or decreased at the stage of correcting the K constant, so there is no need to affect the λ control at all. Even if no proper correction is performed, the value of the learning correction coefficient αL will not be automatically corrected due to learning.

<Effects of the Invention> As explained above, according to the present invention, the learning correction coefficient αL is used for the λ control, and the base air-fuel ratio is adjusted to λ by learning.
Eliminate the deviation from λ = 1 caused by transient differences in the base air-fuel ratio by controlling it so that it approaches -1,
In addition, since the PI constant can be reduced, controllability can be greatly improved (19), and as a result, the catalyst can be used in a location with high conversion efficiency, which not only reduces costs by reducing the amount of precious metals but also eliminates the need for catalyst conversion. Become.

In addition, since the basic injection basin 1 constant is corrected by determining the learning history and learning tendency of the 6 learning correction coefficients, the constant can be corrected with sufficient reliability and extremely effectively. Therefore, it is possible to bring the base air-fuel ratio close to λ-1 even in the region where λ control is not performed, and it is possible to effectively deal with wear and clogging of the fuel injector, as well as changes in air density, etc. . More specifically, this feature eliminates the need for an altitude sensor, etc., and provides excellent effects such as reducing the cost of the control system.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a hardware configuration diagram showing an embodiment of the present invention, FIG. FIG. 2 is a diagram showing the output characteristics of the 02 sensor. 1...CPU 3...CMO8-11 for learning control,
AM (20) 5...Air flow meter 8...02 sensor 17.
...Crank angle sensor 22...Fuel injection valve patent applicant Japan Electronics Co., Ltd. Representative Patent attorney Fujio Sasashima (21)

Claims (1)

[Claims] A basic injection amount calculation means for calculating the basic injection amount from a constant, an intake air flow rate, and an engine rotational speed, and an 02 provided in the exhaust system.
an air-fuel ratio feedback correction coefficient setting means for setting an air-fuel ratio feedback correction coefficient by integral control by comparing the actual air-fuel ratio detected based on the signal from the sensor and the stoichiometric air-fuel ratio; learning correction coefficient retrieval means for searching a learning correction coefficient stored in a map on a RAM corresponding to the engine operating condition;
A new learning correction coefficient is set from the air-fuel ratio feedback correction coefficient and the learning correction coefficient, and the RA is adjusted using the learning correction coefficient.
learning correction coefficient updating means for updating data for the same engine operating conditions in M; injection sound calculation means for calculating the injection amount by multiplying the basic injection amount by the air-fuel ratio feedback correction coefficient and the learning correction coefficient; drive pulse signal output means for outputting a drive pulse signal corresponding to the injection amount to the fuel injection valve, and whether or not a predetermined percentage or more of all learning correction coefficients in a map on the RAM has been updated by learning a predetermined number of times or more. learning history determining means for determining the learning history determination means; and learning tendency determining means for determining whether or not a predetermined percentage or more of these learning correction coefficients deviate in the same direction with respect to the initial value when the predetermined percentage or more has been updated. , constant correction means for correcting the constant according to the amount of deviation when the predetermined ratio or more deviates in the same direction. .