JPH0568632B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a learned value control method for an internal combustion engine that performs idle rotation speed control and air-fuel ratio control.

[Prior art (1)] In idle speed control, the flow rate of intake air supplied to the engine via a bypass that bypasses the throttle valve is controlled by a flow control valve installed in the bypass, thereby controlling the actual engine speed. The actual rotation speed is made to match the target rotation speed determined according to the operating state of the engine, and in particular, after the engine has warmed up completely, feedback control is used to bring the actual rotation speed closer to the target rotation speed. . By the way, the learning value that is updated under this feedback control so as to converge to the actual opening of the flow rate control valve is stored in a memory means that is constantly supplied with power, and is stored in the memory means when the engine is started. There is an internal combustion engine that controls the opening degree of a flow control valve in accordance with a learned value, thereby quickly controlling the engine speed to an appropriate idle speed.

[Problem to be solved by the invention (1)] In such an internal combustion engine, if the power supply to the storage means for storing learned values is interrupted, the learned values will be erased, and after the engine starts, the Since the opening degree of the flow rate control valve is determined according to the newly initialized learned value, the time required for the engine speed to reach the desired idle speed is determined by the already fully learned learned value. This becomes longer than when the opening degree of the control valve is determined.

[Prior art (2)] On the other hand, as an example of air-fuel ratio control, the basic fuel injection time TP determined from the engine load and engine speed,
The fuel injection time τ is determined by the feedback correction coefficient FAF, which is determined according to the oxygen concentration in the exhaust gas, and the learning value TAUG, which is updated so that the average value of the correction coefficient FAF falls within a predetermined range. , τ=TP×FAF×(1+TAUG) There is an internal combustion engine that controls the air-fuel ratio to the stoichiometric air-fuel ratio. Here, FAF during open loop control such as when starting the engine or when it is cold is 1.0.
In addition, the learned value TAUG is used to control the base air-fuel ratio indicated by the average value of the correction coefficient FAF to λ = 1 in order to compensate for changes in the engine over time and variations in individual parts. in,
It is stored in a storage device that is constantly supplied with power, so that values learned over a long period of time can be stored at all times.
This is reflected in the fuel injection, so that the above compensation can be reliably performed, especially in operating conditions where no feedback is provided.

[Problem (2) to be solved by the invention] Such an internal combustion engine also has the same problem as the idle speed control described above. In other words, if the learned value in the storage means is erased for the same reason, during open loop control while the learned value is restored to the value before being erased, the air-fuel ratio will deviate to the rich side or lean side, causing the engine There is a risk that starting performance and engine performance will be adversely affected.

[Means and actions for solving problems]

The present invention has been made to solve such problems, and after the learned value is destroyed due to interruption of power supply to the storage means in which the learned value is stored, the learned value is not updated. This invention proposes a learned value control method for an internal combustion engine in which the learned value is quickly restored to the value before it was destroyed.

Embodiment 1 - Idle speed control - FIG. 2 shows an example of an electronically controlled fuel injection type internal combustion engine to which the present invention is applied, in which reference numeral 10 denotes an engine body, 1
Reference numeral 2 indicates an intake passage, 14 a combustion chamber, and 16 an exhaust passage. 11 is a flow control valve connected to the control circuit 22 via a signal line l11;
It is installed in the bypass 13 that bypasses the throttle valve 18 to control the air flow rate of the bypass 13. The flow rate control valve 11 is driven by, for example, a pulse motor, and its opening degree is controlled according to the number of steps supplied to the pulse motor.

An intake pressure sensor 20 provided in a surge tank 24 downstream of the throttle valve 18 is connected to a signal line l.
1 to the control circuit 22, and generates a voltage according to the intake pressure. The intake temperature sensor 21 is provided in the intake passage 12 upstream of the throttle valve 18,
It is connected to the control circuit 22 via a signal line l2 and generates a voltage according to the intake air temperature.

Intake air whose flow rate is controlled by a throttle valve 18 that is linked to an accelerator pedal (not shown) is guided to the combustion chamber 14 of each cylinder via a surge tank 24 and an intake valve 25.

A fuel injection valve 26 is provided for each cylinder,
The opening/closing is controlled in response to an electrical drive pulse signal S8 supplied from the control circuit 22 via the signal line l3, and pressurized fuel sent from a fuel supply system (not shown) is fed into the intake passage 12 near the intake valve 25, i.e. Injects intermittently into the intake port. The exhaust gas after being burned in the combustion chamber 14 is passed through the exhaust gas 28 and the exhaust passage 16.
and is discharged into the atmosphere via the three-way catalytic converter 30.

Crank angle sensors 34 and 36 are attached to the distributor 32 of the engine, and these sensors 34 and 36 are connected to the control circuit 22 via signal lines 14 and 15. These sensors 34 and 36 output pulse signals each time the crankshaft rotates 30 degrees and 360 degrees, respectively, and these pulse signals are supplied to the control circuit 22 via signal lines l4 and l5, respectively.

The distributor 32 is connected to an igniter 38, and the igniter 38 is connected to the control circuit 22 via a signal line l6.

Reference numeral 40 indicates an idle switch (LL switch) which is linked to the throttle valve 18 and is closed when the throttle valve 18 is fully closed.
It is connected to the control circuit 22 via.

The exhaust passage 16 outputs a signal responsive to the oxygen concentration in the exhaust gas, that is, an output voltage that changes rapidly depending on whether the air-fuel ratio is on the lean side or rich side with respect to the stoichiometric air-fuel ratio. An O ₂ sensor 42 that generates the
It is connected to the control circuit 22 via. The three-way catalytic converter 30 is provided downstream of the O ₂ sensor 42 and simultaneously purifies three harmful components, HC, CO, and NOx, in the exhaust gas.

Further, reference numeral 44 detects the engine cooling water temperature,
This is a water temperature sensor that generates a voltage according to the temperature, and is attached to the cylinder block 46 and connected to the control circuit 22 via a signal line 19.

Reference numeral 48 denotes an air conditioner switch that activates or deactivates the air conditioner, and is connected to the control circuit 22 via a signal line l10. The battery 50 is connected to the control circuit 22 either directly or via a key switch 52.

As shown in FIG. 3, the control circuit 22 includes a central processing unit CPU 22a that controls various devices, a read-only memory ROM 22b in which various numerical values and programs to be described later are written in advance, and a read-only memory ROM 22b in which numerical values and flags of the calculation process are stored in a predetermined manner. A random access memory RAM 22c written in the area, an A/D converter ADC 22d having an analog multiplexer function and converting an analog input signal into a digital signal,
Input/output interface (I/O) 22e to which various digital signals are input, input/output interface (I/O) to which various digital signals are output
22f, a backup memory (BU-RAM) 22g which is supplied with power from the battery 50 when the engine is stopped and stores learning values to be described later, and a path line 22h to which each of these devices is connected. The CPU 22a can detect that the battery has been removed from the vehicle and power supply to the backup plum 22g has been cut off, and can store this as a standby flag "0".

Then, an intake pressure sensor 20, an intake temperature sensor 2
1. O ₂ sensor 42 and water temperature sensor 44 are A/D
It is connected to the converter 22d, and the voltage signals S1, S2, S3, S4 from each sensor are sent to the CPU 22a.
The signal is sequentially converted into a binary signal according to instructions from the computer.

A pulse signal S5 every 30 degrees of crank angle from the crank angle sensor 34, a pulse signal S6 every 360 degrees of crank angle from the crank angle sensor 36, an idle signal S7 from the idle switch 40, and an air conditioner signal S10 from the air conditioner switch 48. , are respectively taken into the control circuit 22 via the I/O 22e. A binary signal representing the engine speed is formed on the basis of the pulse signal S5;
and S6 cooperate to form a request signal for fuel injection pulse width calculation, an interrupt signal for starting fuel injection, a cylinder discrimination signal, and the like. Furthermore, it is determined based on the idle signal S7 whether the throttle valve 19 is substantially fully closed, and the operating state of the air conditioner is determined based on the air conditioner signal S10.

From the I/O 22f, a fuel injection signal S8 and an ignition signal S9 formed by various calculations are output to the fuel injection valves 26a to 26d and the igniter 38, respectively, and are also sent to the flow rate control valve 11 to determine the valve opening. A valve opening signal S11 that controls the valve opening is output.

FIG. 4 shows an example of a procedure for idle speed control in the main routine. The main routine is started when the key switch is turned on, and in step P1,
It is determined whether the standby flag F1 is zero.
If the battery 50 has been removed at some point, an affirmative determination is made, and in step P2 the flag F2 is set to "1" to speed up the learning speed, and in step P3 the standby flag F1 is set to "1". Learning value at P4
Set the initial value IV as PG. If a negative determination is made in step P1, these steps P2 to P4 are skipped.
Steps P1 to P4 are a routine that is passed only once immediately after the power is turned on by the key switch.

In step P5, the engine cooling water temperature THW is 70°C based on the water temperature signal S4 from the water temperature sensor 44.
In other words, it is determined whether the engine is completely warmed up. In step P6, based on the idle signal SG from the idle switch 40, it is determined whether the throttle valve 18 is fully closed or not.
In other words, it is determined whether the idle state is present or not. If steps P5 and P6 are respectively affirmed, the steps
Proceeding to P7, it is determined whether the flag F2 is "1", in other words, whether the learned value is being updated quickly. If an affirmative determination is made, the process proceeds to step P8, where it is determined whether or not the actual engine rotation speed NE is within the range of (target rotation speed NT±α). If an affirmative determination is made, the flag F2 is set to "0" in step P9.
With this flag F2 "0", the update speed returns to normal. If a negative determination is made, step P9 is skipped and the process proceeds to the next step P10, where the learning control routine shown in FIG. 1 is executed.

Referring to Fig. 1, in step P11 it is determined whether Tmsec has elapsed, in other words, whether it is learning timing or not.If the determination is negative, all learning control steps are skipped and this routine ends. do.
If an affirmative determination is made, it is determined in step P12 whether or not the flag F2 is "1", in other words, whether or not the learning value is to be updated quickly. If the judgment is positive, the procedure
In step P13-1, L1 is set in the A register as the learning amount, and if the determination is negative, L2 is set in the A register as the learning amount in step P13-2. here,
L1 is a larger value than L2.

Next, in step P14, the magnitude relationship between the actual engine rotation speed NE and the target rotation speed NT is determined.

The engine's actual rotation speed NE obtained by the rotation speed sensor is the target rotation speed determined based on the engine cooling water temperature.
If it is smaller than NT, in step P15-1,
A value indicating the actual opening degree of the flow control valve 11, for example, the number of pulses PMT of the pulse motor, is compared with the learned value PG. If PMT > PG, in step P16, the learning value is set in register A where the predetermined learning amount is stored.
The values of are added and the result is set as the new learning amount PG. In this case, the learning value PG becomes large. on the other hand,
In step P14, if it is determined that NE>NT, the step
Proceeding to P15-2, the pulse number PMT is compared with the learned value PG, and if PMT<PG, the process proceeds to step P17. In step P17, the contents of register A are set to a negative value, and the process proceeds to step P16, where the learned value PG is updated.
In this case, the learning value PG becomes small. Also, the steps
In P14, if it is determined that NE=NT, the procedure
Proceed to P15-3, determine PMT>PG, and if it is affirmative, proceed to step P16 to set the learning value PG to L1 or L2.
Make it bigger. If a negative judgment is made, proceed to step P15-4.
Proceed to step PMT<PG, and if the determination is positive, proceed to step P17 and step P16 to set the learned value PG to L1.
Or reduce by L2. Step P15-1 or
If P15-2 is negative, if steps P15-3 and 15-4 are negative, the learned value PG
will not be updated.

In this way, in the embodiment shown in FIG.
When the learning value PG stored in RAM22g has been deleted, the large learning value L1 is used to
Since I am trying to update the PG, Figure 11B
As shown by the broken line in , the learning value PG is quickly updated, and therefore the engine speed changes as shown in Figure 11A.
NE is quickly controlled to the desired value. In FIGS. 11A and 11B, solid lines indicate the conventional example.

Furthermore, in this embodiment, when the target rotation speed NT is larger than the actual rotation speed NE during learning, even if the learning value PG is larger than the actual pulse number PMT, the learning value is not used.
In order not to reduce PG, or conversely, NT<NE
In the case of , the learning value PG is not increased even if PMT>PG. Therefore, as in the case where the technical problem of the present invention is solved by another embodiment as shown in FIG. 5, the actual rotation speed NE and the target rotation speed
Update the learned value PG regardless of the size of NT,
In other words, more accurate control is possible than in the case of learning. Note that the embodiment shown in FIG.
Since the procedure is the same as that of the embodiment shown in the figure, the explanation thereof will be omitted. In addition, the flow rate control valve 11
A linear solenoid type can also be used.

Embodiment 2 - Air-fuel ratio control - This embodiment can also be implemented with the internal combustion engine shown in FIG. 2, so it will be described below with reference to FIG. 2 and FIGS. 6 to 10, which will be described later.

In the engine shown in FIG. 2, fuel can be injected according to the main flowchart shown in FIG. Referring to Figure 6, steps P1~
P3 is the same as in FIG. 4, and its explanation will be omitted.
In step P61, the engine speed NE is read based on the engine speed signal S5, which is a reference position signal, and the intake pipe pressure PM is read based on the intake pipe pressure signal S4. In step P62, the basic injection time TP is determined from the map in Fig. 7 based on the rotational speed NE and intake pipe pressure PM, and in step P63,
The corrected injection time τ is determined by executing correction calculation processing according to the operating conditions of the engine. Then step P64
The final injection time Fτ is determined by performing a correction calculation process according to the battery voltage. The injection timing is determined in step P65, and if the determination is affirmative, injection is executed in step P66.

The fuel injection time τ (injection amount) is obtained, for example, as follows.

τ=(TP+TAUG)×(1+KG)×FAF×K Where, τ=Final fuel injection time TP=Basic fuel injection time FAF=Feedback correction coefficient TAUG=Learning correction amount KG=Learning correction coefficient K=Water temperature, intake temperature, etc. The feedback correction coefficient FAF is a value that increases the injection amount if it is determined that the air-fuel ratio is lean based on the air-fuel ratio signal S3 from the O ₂ sensor 42 under feedback control conditions, for example.
1.05, and if the air-fuel ratio is determined to be rich based on the air-fuel ratio signal S3, it will be a value that reduces the injection amount, for example 0.95, and if it is not under the feedback control condition, the correction coefficient FAF will be 1.0.

An example of the procedure for calculating the feedback correction coefficient FAF2 is shown in FIG.

In step P81, it is determined whether the feedback condition is satisfied. For example, the engine coolant temperature THW is
The conditions for feedback control are met when the temperature is 50°C or higher and the power is not being increased. If the conditions for feedback control are not met, proceed to step P82.
Then, set the feedback correction coefficient FAF to 1.0 to prevent feedback control from being executed, and end this procedure. Steps if the conditions are met
Proceed to P83. In step P83, the air-fuel ratio signal S3 is read. In step P4, an air-fuel ratio lean rich flag is formed according to the voltage value represented by the air-fuel ratio signal S3 so that it becomes "1" when rich and "0" when lean, and in step P85, the flag is set to "1". In this case, it is determined that the air-fuel ratio is too rich, and steps are taken to make the air-fuel ratio lean.

That is, in step P86, the flag CAFL is set to zero, and the process proceeds to step P87, where it is determined whether the flag CAFR is zero. When it first shifts to the over-concentrated side, a flag is displayed.
Since CAFR is zero, proceed to step P89 and set RAM2
Subtract a predetermined value α1 from the correction coefficient FAF stored in 2C, and use the result as a new correction coefficient FAF.
shall be. In step P90, flag CAFR is set to 1.
shall be. Therefore, if excessive concentration is determined twice or more in succession in step P85, a negative determination will always be made in step P7 passed from the second time onwards, and in step P88, a predetermined value β1 is subtracted from the correction coefficient FAF, and the The FAF calculation is ended using the result as a new correction coefficient FAF.

On the other hand, if the lean rich flag based on the voltage value represented by the signal _S3 is "0" in step P85, it is determined that the air-fuel ratio is lean, and the procedure is executed to make the air-fuel ratio rich. That is, in step P91, the flag CAFR is set to zero, and the process proceeds to step P92, where it is determined whether the flag CAFL is zero. When shifting to the thinning side for the first time, the flag CAFL is zero, so the process proceeds to step P93, where a predetermined value α2 is added to the correction coefficient FAF, and the result is set as a new correction coefficient FAF. In step P94, the flag CAFL is set to 1. Therefore, if it is determined that the dilution is diluted twice or more consecutively in step P85, a negative determination will always be made in step P92 that passes from the second time onwards, and in step P95, the correction coefficient
A predetermined value β2 is added to FAF, and the result is used as a new correction coefficient FAF to complete the FAF calculation.

In addition, α1 in steps P88, P89, P93, P95,
α2, β1 and β2 are predetermined values.

The feedback correction coefficient FAF determined by this calculation means is shown in FIG. 9 together with the lean rich flag of the air-fuel ratio A/F which changes in accordance with the voltage value represented by the air-fuel ratio signal S3. Referring to this figure, when the air/heat ratio switches from lean to rich or from rich to lean, the correction factor FAF
is skipped by α1 or α2, and if it remains rich, a predetermined number β1 is successively subtracted, and if it remains lean, a predetermined number β2 is successively added.

Next, an example of the calculation procedure for the learning control amount TAUG and the learning control correction coefficient KG is shown in FIG.

Referring to FIG. 10, in step P101, it is determined whether Tmsec has elapsed, in other words, whether or not it is learning timing. If the determination is negative, all learning control steps are skipped and this routine ends. If a positive judgment is made, the flag F is set in step P102.
In other words, it is determined whether or not the learned value is to be updated quickly. If the judgment is positive, the procedure
P103-1 sets L1 as the learning amount to A register M
Set 1 to the B register, and if the result is negative,
In step P103-2, L2 is set to the A register and M2 is set to the B register as learning amounts. Here L1>
L2, M1>M2.

Next, in step P104, it is determined whether the throttle valve 18 is fully closed or not based on whether the idle signal S7 output from the idle switch 40 is on. If the throttle valve 18 is fully closed and a positive determination is made, in step P105-1,
For example, if the engine speed NE is 1000 rpm or less,
Also, it is determined whether the intake pipe pressure PM is 200 mmHg or more. If a positive judgment is made, take steps to perform learning control.
Proceed to P106.

On the other hand, if the throttle valve 18 is not fully closed and a negative determination is made in step P104, step P105-
2, for example, if the intake pipe pressure PM is 200mmHg
Determine whether it is above 500mmHg or not. If an affirmative determination is made, the process proceeds to step P106 to perform learning control.

If a negative determination is made in step P105-1 or P150-2, no learning control is performed.

Next, in step P106, it is determined whether the learning conditions are satisfied. For example, air-fuel ratio feedback control is in progress and the engine coolant temperature THW is
Learning occurs when the temperature is 80°C or higher and the intake air temperature THA is between 40°C and 90°C. If it is determined that the learning conditions are satisfied, the feedback correction coefficient is set in step P107.
It is determined whether the FAF has skipped or not, and if the skip is affirmatively determined, the process proceeds to step P108. procedure
P107 has the aforementioned flag CAFL, CAFR “1” →
This is determined by the change to "0". procedure
In P108, the value of the correction coefficient FAF immediately before skipping is read, and in step P109, the correction coefficient FAFn read this time and the correction coefficient FAFn −
The arithmetic mean value FAFAV with 1 is calculated and stored in a predetermined area. Next, in step P110, the magnitude of the arithmetic average value FAFAV is determined.

If the arithmetic average value FAFAV is smaller than 0.95, it is determined in step P120 whether or not the throttle valve 18 is fully closed. If it is fully closed, the process proceeds to step P121 and the value of the A register is calculated from the learning control amount TAG. Subtract and use the result as a new learning control amount TAG.
If it is not fully closed, proceed to step P122, subtract the value of the B register from the learning control correction coefficient KG, and use the result as a new learning control correction coefficient KG.

If the arithmetic average value FAFAV is greater than 1.1, it is determined in step P130 whether the throttle valve 18 is fully closed or not. If it is fully closed, the process proceeds to step P131 and the value of the A register is set to the learning control amount TAG. The result is set as a new learning control amount TAG.
If it is not fully closed, proceed to step P132, add the value of the B register to the learning control correction coefficient KG, and use the result as a new learning control correction coefficient KG.

In this way, in this embodiment, the air-fuel ratio when the throttle 18 is fully closed is learned using the learning control amount TAG, and the air-fuel ratio when the throttle valve 18 is fully closed is learned using the learning control correction coefficient KG.
8 is open, but if the learned values KG and TAUG have been cleared, the learning speed will be increased by increasing the update amount that increases or decreases according to the engine operating status. I made it.

[Modified example]

In Figures 1 and 10, step P11,
The learning speed can also be increased by reducing the Tmsec determined in P101. In this case, there is no need to change the size of the update amount for learning, but if you change the size, the learning speed can be increased. You can do it faster.

〔Effect of the invention〕

In the present invention, when the learning value of the storage means that is constantly receiving power from the battery regardless of whether or not the engine is being driven is erased due to interruption of power supply from the battery, the learning speed is increased. The influence on the engine, which is made to operate appropriately based on the learned value, is eliminated in a short time.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing a learning control routine according to a first embodiment of the present invention, FIG. 2 is a configuration diagram showing an example of an internal combustion engine to which the present invention is applied, and FIG.
The figure is a detailed block diagram showing an example of the control circuit.
FIG. 4 is a flowchart showing an example of the main routine of the first embodiment, FIG. 5 is a flowchart showing a modification thereof, and FIG. 6 is a flowchart showing an example of the main routine of the second embodiment. Figure 7 is
A diagram showing an example of a map for calculating TP, Figure 8 is FAF
Flowchart showing an example of arithmetic routine, No. 9
The figure is a time chart showing the lean rich flag and FAF, Fig. 10 is a flow chart showing the learning control routine of the second embodiment, Fig. 11A is a time chart of engine speed, and Fig. 11B is a learning value.
This is PG's time chart. 10... Internal combustion engine, 11... Flow rate control valve, 13
...Bypass, 22...Control circuit, 22g...Backup RAM, 26...Injection valve, 40...Idle switch, 50...Battery.

Claims (1)

[Claims] 1 A learning value that is updated according to the deviation between a predetermined basic operating state of the engine and the current operating state of the engine, and is stored in a storage means that is constantly supplied with power from the on-board battery. A learned value control method for an internal combustion engine, characterized in that when it is determined that the power supply from the battery has been interrupted, the learned value update speed is increased for a predetermined period after the engine is started.