JPH051373B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a learning control device for an electronically controlled fuel injection type internal combustion engine, and particularly to a learning control device for starting (cold start).

<Background Art> In an electronically controlled fuel injection type internal combustion engine, the injection amount (pulse width of the drive pulse signal to the fuel injection valve) Ti during normal operation is determined by the following equation.

Ti=Tp×COEF×α+Ts Here, Tp is the basic injection amount, Tp=K×Q/N
It is. K is a constant, Q is the intake air flow rate, and N is the engine speed. COEF 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 amount, which is used to correct changes in the injection amount of the fuel injector due to changes in battery voltage.

Regarding λ control, an O ₂ 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 fuel is injected to achieve the stoichiometric air-fuel ratio. For this purpose, the above-mentioned air-fuel ratio feedback correction coefficient α is determined, and by varying this α, the stoichiometric air-fuel ratio is maintained.

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

In other words, the output voltage of the O ₂ sensor is compared with the slice level voltage, and if it is higher or lower than the slice level, the air-fuel ratio is rich (lean) without suddenly enriching or thinning the air-fuel ratio. ), the air-fuel ratio is first lowered (raised) by P, and then gradually lowered (raised) minute by minute to make the air-fuel ratio leaner (richer).

However, in the region where λ control is not performed, α=
1 and set various correction coefficients COEF to obtain a predetermined air-fuel ratio.

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 (λB = 1), feedback control would not be necessary. The base air-fuel ratio λ = 1 due to factors such as variations in valves, pressure regulators, control units) and changes over time, non-linearity of the pulse width-flow rate characteristics of the fuel injector, and changes in operating conditions and environment. Feedback control is used to prevent this from occurring.

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 through feedback control when the operating range changes significantly. For this purpose, the proportionality and integral constants (P/I) are increased, which causes overshoot and undershoot, 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 is operated at a point where its conversion efficiency is poor, and not only does the cost increase due to the 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.

Therefore, in Japanese Patent Application No. 58-76221, the present applicant set the base air-fuel ratio to λ = 1 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 a base air-fuel ratio learning control device that makes it possible to reduce the P/I ratio, improve controllability, and thereby reduce the cost of catalysts.

In other words, a map of the learning correction coefficient αL corresponding to the operating range determined by the engine speed and load is provided in the RAM, which can be rewritten and the memory contents are retained even after the engine key switch is turned off, and the injection amount Ti is calculated. When doing so, the basic injection amount Tp is calculated as shown in the following formula.
is corrected by αL.

Ti=Tp×COEF×α×αL+Ts Then, the learning of αL proceeds in the following steps.

In a steady state, the operating region and α at that time are detected.

αL that has been learned and stored up to now in correspondence with the driving range is searched.

αL is newly set and stored according to the deviation value of α from α and αL.

On the other hand, the injection amount (pulse width) T _cs at the time of starting is determined by the following equation.

T _cs =T×Kn×Kt Here, T is the basic injection amount at startup, which is retrieved from the water temperature as shown in FIG. 1A. Kn is a correction coefficient, which depends on the engine speed as shown in FIG. 1B. Kt is a correction coefficient that depends on the elapsed time after starting cranking, as shown in FIG. 1C, to prevent fogging.

As a result, the injection amount T _cs at startup is based on the basic injection amount T at startup, which is determined by the water temperature, and is therefore affected by environmental conditions such as aging of the engine, atmospheric pressure, and intake air temperature.

For this reason, depending on the matching, starting may become difficult due to aging of the engine or the influence of environmental conditions.

<Object of the Invention> In view of the above-mentioned circumstances, an object of the present invention is to enable stable starting at all times without being affected by aging of the engine or environmental conditions.

<Configuration of the Invention> For this reason, the present invention provides a learning correction coefficient learned for each operating region determined by engine speed and load, including engine aging and environmental conditions, for air-fuel ratio control during normal operation. This is used to correct the water temperature-dependent injection amount at startup.

Specifically, as shown in Figure 2, basic injection amount calculation means calculates the basic injection amount from the intake air flow rate and engine speed, and detection is based on a signal from the O ₂ set installed in the exhaust system. an air-fuel ratio feedback correction coefficient setting means for setting an air-fuel ratio feedback correction coefficient by comparing the actual air-fuel ratio and the theoretical air-fuel ratio; A learning correction coefficient search means that searches for a learning correction coefficient stored in a RAM that is possible and whose memory contents are retained even after the engine key switch is turned off, and a new learning correction coefficient is determined from the air-fuel ratio feedback correction coefficient and the learning correction coefficient. learning correction coefficient updating means for setting and updating learning correction coefficient data for the same operating region in RAM; and injection for calculating the injection amount by correcting the basic injection amount using the air-fuel ratio feedback correction coefficient and the learning correction coefficient. In addition to comprising an amount calculating means and a driving pulse signal outputting means for outputting a driving pulse signal corresponding to the calculated injection amount to the fuel injection valve, a starting means for detecting the starting state of the engine based on a signal from a start switch is provided. a state detecting means; a starting basic injection amount setting means for setting a starting basic injection amount based on the cooling water temperature when the engine is started; The driving pulse signal output means calculates the injection amount at startup by correcting it using a learning correction coefficient in the same operating region as the operating region determined by the load, and outputs the driving pulse signal in place of the injection amount calculated by the injection amount calculating means. and starting injection amount calculation means for sending the fuel to the engine.

<Example> Examples will be described below.

Figure 3 shows the hardware configuration.

1 is CPU, 2 is P-POM, 3 is for learning control
COMS-RAM, 4 is an address decoder.
Note that a backup power supply circuit is used for the RAM 3 in order to retain the memory contents even after the key switch is turned off.

The hot wire air flow meter 5 is used as an analog input signal to the CPU 1 for controlling the fuel injection amount.
intake air flow rate signal from the throttle sensor 6, throttle opening signal from the throttle sensor 6, water temperature signal from the water temperature sensor 7, exhaust oxygen concentration signal from the _O2 sensor 8,
There is a battery voltage from the battery 9, which is adapted to be input via an analog input interface 10 and an A/D converter 11. 1
2 is an A/D conversion timing controller.

Digital input signals include ON/OFF signals from the idle switch 13, start switch 14, neutral switch 14, and neutral switch 15, and these are now input via the digital input interface 16. There is.

In addition, for example, from the crank angle sensor 17
A reference signal every 180 degrees and a position signal every 1 degree are inputted via a one-shot multi-circuit 18. In addition, the vehicle speed sensor 19
A vehicle speed signal is inputted via the waveform shaping circuit 20.

An output signal from the CPU 1 (a drive pulse signal to the fuel injection valve) is sent to the fuel injection valve 22 via a current control circuit 21.

Here, the CPU 1 performs input/output operations, arithmetic processing, etc. according to a program (stored in the ROM 2) based on the flowchart (fuel injection amount calculation routine) shown in FIG. 4, and controls the fuel injection amount.

Next, the flowchart shown in FIG. 4 will be explained.

The intake air flow rate Q obtained from the signal from the air flow meter 5 and the crank angle sensor 17 at S1
The basic injection amount Tp (=K×Q/N) is calculated from the engine speed N obtained from the signal from the engine.

In S2, various correction coefficients COEF are set.

In S3, the output voltage of the O ₂ sensor 8 and the slice level voltage are compared and the air-fuel ratio feedback correction coefficient α is set by proportional-integral control. Note that under the air-fuel ratio feedback control stop condition, the air-fuel ratio feedback correction coefficient α is clamped.

In S4, a voltage correction amount Ts is set based on the battery voltage from the battery 9.

Engine speed N and basic injection amount (load) at S5
Search for the corresponding learning correction coefficient αL from Tp.
Note that the map of the learning correction coefficient αL for the engine speed N and the basic injection amount Tp is stored in the rewritable RAM 3.
, and all αL=1 at the time when learning has not started.

S6 to S9 are provided to detect a steady state as a learning condition, and in S6 the vehicle speed sensor 19
The change in vehicle speed is determined based on the signal from S7.
The gear position is determined based on the signal from the neutral switch 15, and the throttle sensor 6 is determined at S8.
The change in the throttle opening degree is determined based on the signal from , and it is determined in S9 whether or not a predetermined time has elapsed. If it is within the predetermined time, the process returns to S6. In this way, if the change in vehicle speed is less than or equal to a predetermined value within a predetermined time, the gear is engaged, and the change in throttle opening is less than or equal to a predetermined value, it is determined to be in a steady state,
The learning correction coefficient αL is updated in S10 and S11. In addition, if the change in vehicle speed exceeds a predetermined value at any point within a predetermined time, if the vehicle speed becomes neutral, or if the change in throttle opening exceeds a predetermined value, it is determined that the state is in a transient state, S
10. Do not update the learning correction coefficient αL in S11. Note that since the learning is performed on the assumption that air-fuel ratio feedback control is being performed, it goes without saying that updating is not performed even under the air-fuel ratio feedback control stop condition.

Learning correction coefficient αL when the steady state is determined
The update is performed as follows.

Calculation is performed according to the following formula from the learning correction coefficient αL retrieved from the engine speed N and basic injection amount Tp in S10 and the current air-fuel ratio feedback correction coefficient α, and the value is set as the new learning correction coefficient αL. do.

αL←αL+Δα/M Note that Δα indicates the amount of deviation of α from the reference value (α ₁ ), Δα=α−α ₁ , and the reference value α ₁ is generally 1.0.
becomes. Moreover, M is a constant.

In S11, a new learning correction coefficient αL is written into the RAM 3 at the corresponding engine speed N and basic injection amount Tp. That is, the data in RAM3 is updated.

In S12, the injection amount Ti is calculated according to the following equation.

Ti=Tp×COEF×α×αL+Ts In S13, it is determined based on the signal from the start switch 14 whether or not the engine is in a starting state (during cranking).

Here, in the case of NO, that is, in the case of normal operation, the injection amount Ti calculated as described above is output.

In the case of YES, that is, at the time of starting, the starting injection amount Tcs is calculated as follows.

Based on the signal from the water temperature sensor 7 in S14
The starting basic injection T stored in the map in the ROM 2 according to the water temperature is searched (see FIG. 1A).

In S15, a correction coefficient kn is searched from the engine speed N, and a correction coefficient Kt is searched from the elapsed time after the start of cranking (see FIGS. 1B and C). Of course, these maps are also stored in ROM2.

In S16, a correction coefficient Kn,
In addition to Kt, the learning correction coefficient αL in the operating region (N, Tp) that has already been searched is multiplied to calculate the starting injection amount Tcs as shown in the following equation.

Tcs]=T×Kn×Kt×αL In this way, when calculating the starting injection amount Tcs, correction is performed using the learning correction coefficient αL, so it is not affected by aging of the engine or environmental conditions.

The starting injection amount Tcs is calculated above, but Tcs
Outputs the larger of Ti and Ti. That is,
Compare Tcs and Ti in S17, and if NO (Tcs≦Ti), output Ti as is and YES (Tcs>Ti)
In this case, Tcs is output as Ti in S18.

When Ti is output, a drive pulse signal corresponding to this 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 injection amount at startup is corrected using the learning correction coefficient learned during normal operation, including the aging of the engine and environmental conditions. The effect is that stable starting can always be performed without being affected by the impact.

[Brief explanation of drawings]

Figure 1 A, B, and C are characteristic diagrams of the basic injection amount and various correction coefficients for calculating the injection amount at startup;
FIG. 2 is a block diagram showing the configuration of the present invention, FIG. 3 is a hardware configuration diagram showing an embodiment of the present invention,
FIG. 4 is a flow chart similar to the above. 1...CPU, 2...ROM, 3...For learning control
CMOS-RAM, 5... Air flow meter, 7...
...Water temperature sensor, 8...O ₂ sensor, 14...Start switch, 17...Crank angle sensor, 22
...Fuel injection valve.

Claims (1)

[Scope of Claims] 1. Basic injection amount calculation means that 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 O ₂ sensor installed in the exhaust system. an air-fuel ratio feedback correction coefficient setting means for setting an air-fuel ratio feedback correction coefficient by comparing the air-fuel ratio with a stoichiometric air-fuel ratio; A learning correction coefficient retrieval means searches for a learning correction coefficient stored in RAM whose memory contents are retained even after OFF, and a new learning correction coefficient is set from the air-fuel ratio feedback correction coefficient and learning correction coefficient. learning correction coefficient updating means for updating learning correction coefficient data for the same operating region; injection quantity calculation means for calculating the injection quantity by correcting the basic injection quantity using the air-fuel ratio feedback correction coefficient and the learning correction coefficient; In a learning control device for an electronically controlled fuel injection internal combustion engine, the learning control device includes a drive pulse signal output means for outputting a drive pulse signal corresponding to a calculated injection amount to a fuel injector, and starts the engine based on a signal from a start switch. a starting state detection means for detecting a state; a starting basic injection amount setting means for setting a starting basic injection amount based on the cooling water temperature when the engine is started; The injection amount at startup is calculated by correcting it using a learning correction coefficient in the same operating area as the operating area determined by the engine speed and load, and the injection amount calculated by the injection amount calculation means is replaced by the injection amount calculated by the injection amount calculation means. What is claimed is: 1. A learning control device for starting an electronically controlled fuel injection type internal combustion engine, comprising: starting injection amount calculating means for sending a signal to a drive path signal outputting means.