JPS6026137A - Air-fuel ratio learning control device in electronic control fuel injection type internal-combustion engine - Google Patents

Abstract

PURPOSE:To enhance the safety of the learning control of air-fuel ratio, by providing an O2 sensor signal inverted period measuring means for measuring the inverted period of a signal from an O2 sensor and a renewal stopping means for stopping the function of a learning compensating coefficient renewal means. CONSTITUTION:A basic fuel injection amount computing means computes a basic fuel injection amount in accordance with an intake-air flow rate and an engine rotational speed, and an air-fuel ratio feed-back compensating coefficient setting means set an air-fuel ratio feed-back compensating coefficient in accordance with an air-fuel ratio from an O2 sensor. A learning compensating coefficient renewal means renews the data of learning compensating coefficient in accordance with the air-fuel ratio feed-back compensating coefficient and the learning compensating coefficient. The renewal stopping means stops the function of the learning compensating coefficient renewal means when the inverted period of the signal of the O2 sensor is out of a predetermined range. Thus, the degree of deterioration, etc. of the O2 sensor is checked, and if the deterioration, etc. occur, no compensation is made to the renewal of the learning compensating coefficient so that the safety of learning control is enhanced.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an air-fuel ratio learning control device for an electronically controlled fuel injection internal combustion engine, and in particular, to prevent air-fuel ratio learning from proceeding in the wrong direction due to deterioration of the 02 sensor, etc. Therefore, the present invention relates to a device that performs the learning side fffn while monitoring the state of the signal of the 02 sensor.

<Background Art> In an electronically controlled fuel injection type internal combustion engine, the injection amount T1 is determined by the following equation.

Tt=TpXCOEFXα+Ts Here, 1p is the basic injection amount, and Tp=×Q/N. K is a constant, Q is the intake air flow rate, and N is the engine speed. COrK F is various correction coefficients. Is α the air-fuel ratio feed bank for air-fuel ratio feedback control (λ control), which will be described later? ili is a positive coefficient. T
S is a voltage correction amount, which is used to correct changes in the injection flow rate of the fuel injection valve due to fluctuations in battery voltage.

Regarding λ control, an 02 sensor is installed in the exhaust system 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 adjusted to achieve the stoichiometric air-fuel ratio. For this reason, the air-fuel ratio feedback mentioned above? A positive coefficient α is determined and the stoichiometric air-fuel ratio is maintained by varying 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 voltage of the 02 sensor is compared with the slice level voltage, and if the voltage is higher or lower than the slice level, the air-fuel ratio is richer without suddenly enriching or reducing the air-fuel ratio. (lean), the air-fuel ratio is first lowered (raised) by P, and then gradually lowered (raised) one minute at a time to control the air-fuel ratio to become thinner (richer).

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 COE F.

By the way, if the base air-fuel ratio when α = 1 in the λ control region could be set to the stoichiometric air-fuel ratio (λ-1), fee 1-' hack control would be unnecessary. Variations in meters, fuel injection valves, pressure regulators, control units 1-), illumination, and fuel injection valve pulses
Feedhack control is performed because the base air-fuel ratio deviates from λ-1 due to factors such as non-linearity of flow characteristics and changes in operating conditions and environment.

However, if the base air-fuel ratio deviates from λ-1, it takes time to stabilize the step in the base air-fuel ratio to λ-1 by feedbank control when the operating range changes significantly. And for this we need the constant of proportionality and integration (P/
Since the I component) is increased, overshoot and undershield j, -1- occur, resulting in 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, making it unnecessary to replace the catalyst. There was the problem of losing the raft.

Therefore, in Japanese Patent Application No. 58-76221, the applicant set the base air-fuel ratio to λ-■ by learning, thereby eliminating the deviation from λ=1 caused by the step in the base air-fuel ratio during transient times, and We have proposed an essential learning control device that makes it possible to reduce Pl and improve controllability, thereby reducing the cost of catalysts.

That is, the learning Ti1i positive coefficient α corresponding to engine operating conditions such as engine speed, Pl, and load is added to RAM l.
A map of 0 is provided, and when calculating the injection amount T i, the basic injection amount Tp is corrected by α0 as shown in the following equation.

'Fi = 'l' p x COE F x a x
rx o1T3 Then, the learning of α0 proceeds in the following steps.

i) Engine operating conditions and α in a steady state
and detect.

ii) Search for α0 that has been learned and stored up to now in accordance with the engine operating conditions.

11;) From the above α and the above α0, α0 is newly set and stored by weighted average or the like.

By the way, in such an air-fuel ratio learning control device,
For example, if the 02 sensor deteriorates due to aging, there is a risk that not only will it not be learned in a compact manner, but the learning will proceed in an undesirable manner, resulting in 'C.' Improvements in this respect have been desired.

<Objective of the Invention> In view of the above-mentioned actual situation, the present invention aims to prevent air-fuel ratio learning from progressing in the wrong direction due to deterioration of the 02 sensor, etc., and improve the safety of learning control. .

<Configuration of the Invention> For this reason, the present invention, as shown in FIG. an air-fuel ratio feedback correction coefficient setting means that compares the actual air-fuel ratio detected based on a signal from the stoichiometric air-fuel ratio and sets an air-fuel ratio feedback correction coefficient by proportional-integral control; Record the engine operating conditions in the RAM accordingly.1. a learning correction coefficient search means for searching the learning correction coefficient for the same engine operating conditions; learning correction coefficient updating means for updating the learning correction coefficient; injection quantity calculation means for calculating the injection quantity by multiplying the basic injection quantity by the air-fuel ratio feedback correction coefficient and the learning correction coefficient; and a drive pulse corresponding to the calculated injection quantity. In addition to providing a drive pulse signal output means for outputting a signal to the fuel injection valve, 02
02 sensor signal reversal period δ1 measuring means for measuring the reversal period n1 of the sensor signal, and determining whether or not the measured reversal period is within a predetermined range determined by the engine rotational speed at that time, and when it is outside the range. and update stop means for stopping the function of the learning correction coefficient update means.

However, it should be noted that the lynch-lean reversal period of the 02 sensor signal is normally within a predetermined range depending on the engine speed, and when the reversal period is outside the above range, , 02 sensor deterioration, etc., and the ζ learning correction coefficient is not updated.

<Example> Examples will be described below.

Figure 2 shows the hardware configuration.

■ is CPU, 2 is P-ROM, 3 is CMO for learning control
3-RAM, and 4 an address decoder. Furthermore, RAM
For No. 3, a pull-up power supply circuit is used to retain the memory contents even after the key switch is turned off.

ζ is the analog input signal to the CPU for controlling the fuel injection amount. :! ) Intake air flow rate signal from the wire air flow meter 5, throttle opening signal from the throttle sensor 6, water temperature signal from the water temperature sensor 7, 02 sensor 8
There is U1 atmospheric oxygen concentration borrowed from U1, and battery voltage from Battery 9, which are analog input interface 1.
It is designed to be inputted via an A/D converter 11 and an A/D converter 11. 12 is an A/D conversion timing controller.

Digital input signals include ON/OFF signals from the idle switch 13, start switch 14, and neural switch 15, and these are inputted via the digital input interface I6.

In addition, for example 180" from the crank angle sensor 17
A reference signal for each position and a position signal for each l° are inputted via a one-shot one-multi circuit 18. Further, the vehicle speed signal from the vehicle speed sensor 19 is manually inputted via a waveform shaping circuit 20.

The output signal from the CPUI (driving pulse to the fuel injection valve) is sent to the fuel injection valve 22 via the current control circuit 2I.

Here, CI) U1 is a flowchart 1 (fuel injection amount δl routine) shown in FIG.
//, "z" performs input/output operations and arithmetic processing according to the program (stored in the ROM 2) to control the fuel injection amount.' Next, the flowchart 1 in FIG. 3 will be explained.

The basic injection amount Tp is calculated based on the intake air flow rate Q obtained from the signal from the air flow meter 5 and the engine rotation speed N obtained from the signal from the crank angle center 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 voltage are compared, and the air-fuel ratio feedback correction coefficient α is set by -ζζ proportional bone control.

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

In S5, engine speed N and basic injection amount (load) 'rp
The corresponding learning correction coefficient α0 is searched from.

The map of the learning correction coefficient α0 for the rotational speed N and the basic injection FitTp is stored in the rewritable RAM 3, and all αo=l when learning has not started.
It becomes.

S6 to S9 are provided to monitor the state of the signal of the 02 sensor 8. In S6, the Lynch-Lean reversal period T of the output voltage of the 02 sensor 8 (see Fig. 4) is measured, and the S
7, calculate the frequency f=1/'r. And S8
The frequency range when parking is predetermined from the engine speed N (f min = f max
). Then, in S9, the frequency f is changed to that range (f
min to fmax). Here, if it is within the range, the process proceeds to the next step 810, but if it is outside the range, it is determined that the 02 sensor 8 has deteriorated or the like, and the process proceeds to S16.

That is, the frequency f of the signal from the 02 sensor 8 changes in proportion to the engine speed N, but is determined within a certain range if the engine speed N is constant.

If the frequency of the actual 02 sensor 8 signal becomes high and goes out of range, it is considered to be due to the influence of noise, etc., and if it becomes low and goes out of range, it is considered to be due to deterioration due to aging or temperature drop. It will be done. Therefore, in these cases 3
14. The learning correction coefficient α0 is not updated in S15.

310 to 313 are provided to detect a steady state, and the SIO determines a change in vehicle speed based on the signal from the vehicle speed sensor 19, and the neutral switch 15 is activated at 311.
At 312, the change in throttle opening is determined based on the signals from the throttle sensor 1 to the throttle sensor 6. At 313, it is determined whether or not a predetermined time has elapsed. If so, return to SIO. thus,
If the change in vehicle speed is less than a predetermined value within a predetermined time, the gear is engaged, and the change in throttle opening is less than a predetermined value, it is determined that the vehicle is in a steady state, and in steps 314 and 315. The learning correction coefficient α0 is updated. Additionally, if the change in vehicle speed exceeds a predetermined value at any point within a predetermined time, if the vehicle becomes neutral, or if the change in throttle opening exceeds a predetermined value, it is considered to be a transient state. The learning correction coefficient α0 is not updated in steps 314 and 315.

When it is determined that the signal of the 0.2t sensor is positive and in a steady state, the learning correction coefficient α0 is updated as follows.

Calculation is performed according to the following formula from the learning correction coefficient α0 retrieved from the engine speed N and basic injection amount 1p in step 314 and the current air-fuel ratio feedbank correction coefficient α, and the value is used as the new learning correction coefficient αO. shall be.

αO←αO+Δα/M Note that Δα indicates the deviation amount of α from the standard value, and Δα−α−
α1, and the reference value α1 is generally 1.0. Moreover, M is a constant.

In step 315, a new learning correction coefficient α0 is written into the RAM 3 around the corresponding engine rotational speed N and basic injection ff1i'p. That is, the data in M3 is updated to R.

In step 316, the injection amount Ti is calculated according to the following equation.

Ti = TpXCOEFXαXαo'+Ts where, 0
If the signal of the 02 sensor 8 is positive and in a steady state, the updated one is used as α0, and if the signal of the 02 sensor 8 is field lightning or in a transient state, the retrieved one is used as is.

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

<Effects of the Invention> As explained above, according to the present invention, the reversal period of the 02 sensor signal Nori Sochi Lean is measured, the degree of deterioration, etc. of the 02 sensor is determined based on this, and the deterioration etc. is determined. Since the learning correction coefficient is not updated when this occurs,
Learning does not progress in the wrong direction, improving the safety of learning control.

[Brief explanation of the drawing]

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. 3 is the flowchart 1 of the same as above, and Fig. 4 is the output voltage of the 02 sensor. FIG. ■...CPU 3...CMO3-RΔM for learning control
5...Air flow meter 8...02 (!Nza 17...Crank angle sensor 22...Fuel injection valve patent applicant Japan Electronics Co., Ltd.

Claims (1)

[Claims] The basic injection amount calculating means calculates the basic injection amount from the intake air flow rate and engine speed, and the actual air-fuel ratio detected based on the signal from the 02 sensor installed in the exhaust system is compared with the theoretical air-fuel ratio. an air-fuel ratio feedback correction coefficient setting means for setting an air-fuel ratio feedbank correction coefficient by proportional-integral control; and a learning correction coefficient stored in the RAM corresponding to engine operating conditions such as engine speed and load. learning correction coefficient retrieval means; and learning correction coefficient updating means for setting a new learning correction coefficient from the air-fuel ratio feedbank correction coefficient and the learning correction coefficient to update learning correction coefficient data for the same engine operating condition in the RAM. ,
injection M calculation means for calculating the injection amount by multiplying the basic injection amount by an air-fuel ratio feedbank correction coefficient and a learning correction coefficient;
In an electronically controlled fuel injection type internal combustion engine equipped with a drive pulse signal output means for outputting a drive pulse signal corresponding to the calculated injection amount to the fuel injection valve, the inversion of the signal of the 02 sensor is performed. Measuring the cycle02
A sensor signal reversal period δ1 measuring means determines whether or not the measured reversal period is within a predetermined range determined by the engine rotational speed at that time, and stops the function of the learning correction coefficient updating means when it is outside the range. 1. An air-fuel ratio learning control device for an electronically controlled fuel injection type internal combustion engine, characterized in that an air-fuel ratio learning control device is provided with an update stop means.