JPH06137185A - Fuel injection amount learning control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce a mislearning by variably generating a deposit learning speed based on a transient correction amount, in a fuel injection amount learning control device for an internal combustion engine. CONSTITUTION:In a deposit learning means M1, a deposit learning value is adjusted in accordance with air-fuel ratio at transient time of an internal combustion engine M2. In a correcting means M3, the deposit learning value is integration reflected to a transient correction amount of fuel injection to correct a fuel amount injected to the internal combustion engine M2 by an injection means M4. In a learning speed control means M5, based on the transient correction amount, an adjusting speed of the deposit learning value is variably set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection amount control device equipped with a correction means for correcting the amount of fuel adhering to the wall surface of an intake passage of an internal combustion engine and the amount of evaporation of the fuel, immediately after starting the engine and during transition The present invention relates to an injection amount learning control device.

[0002]

2. Description of the Related Art Conventionally, as described in Japanese Patent Application Laid-Open No. 64-29653, the influence of deposit is learned from the air-fuel ratio at the transition when the deviation of the intake pipe pressure exceeds a predetermined value, and the acceleration increase coefficient and deceleration are calculated. There is a fuel injection amount learning control device for an internal combustion engine that reflects the reduction coefficient.

[0003]

Since the conventional apparatus learns the influence of the deposit on the condition that the deviation of the intake pipe pressure exceeds a predetermined value, among the various coefficients for obtaining the actual fuel injection amount, There is a problem that erroneous learning may occur when the degree of reflection of each of the above-described acceleration increase coefficient or deceleration decrease coefficient with respect to other various coefficients is large or small.

The present invention has been made in view of the above points,
An object of the present invention is to provide a fuel injection amount learning control device for an internal combustion engine, which reduces erroneous learning by varying a deposit learning speed based on a transient correction amount.

[0005]

FIG. 1 shows the principle of the present invention.

In the figure, the deposit learning means M1 increases or decreases the deposit learning value according to the air-fuel ratio of the internal combustion engine M2 at the time of transition. The correction unit M3 corrects the fuel injection amount injected by the injection unit M4 into the internal combustion engine M2 by integrating and reflecting the deposit learning value on the transient correction amount of fuel injection.

The learning speed control means M5 varies the increase / decrease speed of the deposit learning value based on the transient correction amount.

[0008]

In the present invention, the rate of increase / decrease of the deposit learning value is changed based on the transient correction amount, and when the transient correction amount in which the deposit learning value is integrated and reflected is large, that is, when the deposit learning value changes, the air-fuel ratio is changed. When the amount of change in the deposit learning value increases significantly, the increase / decrease rate of the deposit learning value is increased to actively learn, and when the transient correction amount is small, the increase / decrease rate of the deposit learning value is decreased to learn negatively, so false learning is reduced. It

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. First, FIG. 2 shows the arrangement of the entire gasoline engine, in which 1 is a gasoline engine body, 2 is a piston, 3 is a spark plug, 4 is an exhaust pipe, 5 is an intake pipe,
6 is a surge tank that absorbs the pulsation of intake air, 7 is a throttle valve that adjusts the amount of intake air, and 8 is a negative pressure sensor that measures the intake pipe pressure. The exhaust pipe 4 is provided with an oxygen sensor 9 for detecting the residual oxygen concentration in the exhaust gas, and the intake pipe 5 is provided with a fuel injection valve 10 for injecting fuel into the intake air of the gasoline engine body 1 and a temperature of the intake air. An intake air temperature sensor 11 for detecting and a throttle sensor 12 for detecting the opening of the throttle valve are provided. Further, a knock sensor 13 for detecting knocking is attached to a cylinder block inside the engine body, and a water temperature sensor 15 for measuring a cooling water temperature is attached to a water jacket.

Further, the igniter 16 generates a high voltage necessary for ignition, and the distributor 17 distributes and supplies the high voltage to the ignition plug of each cylinder in conjunction with the rotation of a crankshaft (not shown). The rotation angle sensor 18 outputs a rotation pulse signal NE of 24 pulses for one rotation of the distributor 17, that is, two rotations of the crankshaft, and the cylinder discrimination sensor 19 outputs a rotation detection signal G of one pulse for one rotation of the distributor 17. Reference numeral 20 denotes an electronic control circuit that inputs signals from each sensor and outputs a control signal to the fuel injection valve 10 and the like, 21 is a key switch, and 22 is a starter motor.

As shown in FIG. 3, the electronic control circuit 20 includes a central processing unit (CPU) 30, a read only memory (ROM) 31 storing a processing program, and a random access memory (RAM) used as a work area. 32
And a backup RAM that retains data even after power is stopped
33 and A / D converter 34 having a multiplexer function
And an I / O interface 35 having a buffer function, and these are interconnected by a bus line 37.

The A / D converter 34 has an air flow rate signal from the negative pressure sensor 8, an oxygen concentration signal from the oxygen sensor 9, an intake air temperature signal from the intake air temperature sensor 11, and a throttle opening degree from the throttle sensor 12. Signal and knock sensor 13
The knocking signal from the water temperature sensor and the water temperature signal from the water temperature sensor 15 are supplied to digitize each signal, and these digital signals are read by the CPU 30.
Further, the I / O interface 35 has a rotation angle sensor 1
Signals from the 8, cylinder discrimination sensor 19, and key switch 21 are input, and the signals are read by the CPU 30.

The CPU 30 calculates the ignition timing and the fuel injection amount based on the sensor detection data, and the obtained ignition signal and fuel injection signal are supplied to the igniter 16 and the fuel injection valve 10 through the I / O interface 35. It

Next, the control program of one embodiment of the device of the present invention will be described with reference to FIGS. 4, 5, 6, 7, 8, and 9.
This will be described with reference to the flowchart shown in FIG.
FIG. 4 is an expected intake air amount calculation routine, FIG. 5 is a wall surface adhesion correction amount calculation routine, FIG. 6 is a deposit learning calculation routine, FIG. 7 is an increase value initial value setting routine at the time of start, and FIG. FIG. 9 shows the value FASE2 calculation routine, FIG. 9 shows the first and third post-start increase amounts FASE1, FASE3 calculation routine, and FIG. 10 shows the post-start increase amount calculation routine.

First, a predicted intake pipe pressure PMF used to calculate the basic injection amount TP and the fuel adhesion correction amount FMW (described later).
The WD operation routine will be described with reference to FIG. This routine is executed every predetermined time (for example, 8 msec).
In step 200, the engine speed NE, the A / D conversion value TA of the throttle opening, and the current intake pipe pressure PM ₀ detected by the negative pressure sensor 8 are fetched. In step 202, the intake pipe pressure PMTA in a steady state corresponding to the engine speed NE and the throttle opening TA is calculated from the map shown in FIG.
Is calculated. In the next step 204, the coefficient n relating to weighting is calculated from the map shown in FIG. In the next step 206 and step 208, the previously calculated weighted average value PMSM _i-1 stored in the register PMSM1 is read out and the weighted average value PMSM _{i of} this time is read based on the equation 1.
And the weighted average value PM is calculated in step 210.
The SM _i is stored in the register PMSM1.

[0016]

[Equation 1]

In the next step 212, the number of calculations T / Δt is calculated by dividing the time Tmsec from the current time point to the intake pipe pressure prediction time point by the calculation cycle Δt (= 8 msec) of the routine of FIG. This predicted time Tmsec is shown in FIG.
As shown in, the time from the present time to the establishment of the intake air amount, that is, the time from the current time to the closing of the intake valve can be adopted, and when fuel is not injected into each cylinder independently, It is determined by taking into consideration the fuel flight time up to, but even if the crank angle from the current time point to the prediction destination is the same, this prediction time Tmsec becomes shorter as the engine speed increases, so the engine speed, etc. It is preferable to change it depending on the operating conditions (for example, shorten as the engine speed increases). In the next step 214, the value stored in the register PMSM1 is set to the weighted average value PMSM _i−1, and then in step 216, the calculation of the above formula 1 is repeatedly executed T / Δt times,
In step 218, the calculated value is stored in the register PM.
Store in SM2. By repeatedly executing the weighted average value in this manner, the latest weighted average value approaches the intake pipe pressure value in the steady operation state. Therefore, by setting the number of times of calculation of the weighted average value as described above, Tmsec It is possible to calculate a value close to the previous intake pipe pressure (the intake pipe pressure in a state closer to the steady state from the present time).

In the next step 220, the register PMSM
2 is subtracted from the value stored in the register PMSM1 (the intake pipe pressure PMSM1 at the present time calculated) from the value stored in 2 (the intake pipe pressure PMSM2 at the predicted time obtained by the calculation) to obtain the difference ΔP, and the next step The difference Δ with the current intake pipe pressure (current measurement value) PM ₀ measured in 222
A value obtained by adding P and P is set as a predicted value PMFWD.

Next, since the amount of fuel adhering to the wall surface near the intake manifold changes depending on the operating conditions, it is necessary to transiently supply the difference in the saturated adhering amount under each operating condition to the wall surface near the port.

Fuel adhesion correction amount FM executed for this purpose
W will be described based on the flowchart of FIG.
First, at step 301, it is judged whether or not the engine is starting. If the engine is starting, the fuel adhesion correction amount FM
W and the attenuation rate QTRN (details will be described later) are initialized to 0 (step 302). Conversely, if the above conditions are not satisfied, the process proceeds to step 303. Predicted value PMFWD calculated in FIG.
Based on Table 1, the adhered fuel amount QMW is calculated (the adhering fuel amount increases as the intake pipe negative pressure increases), and the adhering fuel amount QMW _i-1 obtained from the previous routine and the present routine From the difference between the calculated adhered fuel amount QMW _i , the adhered fuel change amount D
LQMW is calculated. Here, in Table 1, the saturated adhering fuel amount during steady operation is stored with the intake pipe pressure in that state as a parameter.

[0021]

[Table 1]

Next, at step 304, the correction coefficient KTHW based on the water temperature and the correction coefficient KNE based on the rotational speed are read from Tables 2 and 3.

[0023]

[Table 2]

[0024]

[Table 3]

Further, KFMW is calculated from the correction coefficients KTHW and KNE and the deposit learning value KDPC calculated from the flowchart shown in FIG.

KFMW = 1 + (KTHW + KDPC) * KNE Next, the fuel adhesion correction amount FMW is calculated from the following formula (step 305). Here, when the intake air amount changes from small to large, a predetermined amount of the fuel injection amount adheres to the wall surface so as to shift to the equilibrium state. The adhesion amount until equilibrium can be calculated from the difference between the fuel adhesion amount QMW _i-1 in the fuel adhesion amount QMW _i and the previous processing cycle in the current processing cycle. However, the fuel adhesion correction amount (QM
W _i -QMW _{i -1} ) is not attached all at once and gradually shifts to the equilibrium state. Therefore, the fuel correction amount (QMW _i −QMW _{i− 1} ) * KMW1 that is attached in the current processing cycle is calculated using the ratio KMW1 of the fuel correction portion that is attached in the current processing cycle (KMW1 is calculated from Table 4). I asked for it, and I asked for the amount that I have not attached yet
TRN _i * KMW2 (KMW2 is calculated from Table 5) is calculated, and the above two fuel correction amounts are added together to determine the fuel correction amount in the current processing cycle. Further, the fuel adhesion correction amount FMW is calculated by multiplying the fuel correction amount by the water temperature calculated in step 304 and the correction coefficient KFMW based on the rotation speed.

FMW = {(QMW _i −QMW _i−1 ) * K
MW1 + QTRN _i * KMW2} * KFMW In step 306, the damping term QTRN _i used in the above equation is calculated and the calculation result is used as the damping term QTR of the fuel adhesion correction amount in the next processing cycle.
It is used as N _i . Where QTRN
_i-1 is the attenuation term in the previous processing cycle.

QTRN _i = QTRN _i-1 * (1-KMW
2) + (QMW _i -QMW _i-1 ) * (1-KMW1)

[0029]

[Table 4]

[0030]

[Table 5]

Next, the deposit learning value KD used above
The calculation method of the PC will be described based on the flowchart of FIG.

First, in steps 401 to 405, it is determined whether or not deposit learning is performed. The condition for executing this deposit learning is that when the water temperature in the F / B is 80 ° C or more and 100 ° C or less, the amount after the start and the warm-up amount are not executed and the number of revolutions is less than the predetermined number of revolutions, the amount of wall adhesion QW
When is equal to or greater than the predetermined value A, all the conditions are met, and the process proceeds to step 406. The adhered amount on the wall QW is calculated by the following equation QW = D
It is calculated by LQMW * KMW1 + QTRN _i-1 * KMW2. That is, the wall surface adhesion amount QW is the same as the part in parentheses of the arithmetic expression of step 305 of FIG. 5 for calculating the fuel adhesion correction amount FMW. If any of the above conditions is not satisfied, counter values CDP1 = 0 and CDP2 =
0, flag XDPC = 0 is initialized, and deposit learning is not performed.

Next, in step 406, it is determined whether or not the value of the flag XDPC indicating whether or not the deposit learning is in progress. During deposit learning (XDPC = 1),
Skip steps 407 and 408, and vice versa, counter XD
If PC = 0 and no deposit learning is in progress, step 4
Proceed to 07. This step 407 is a deposit learning start condition for determining whether or not to start deposit learning, which is the wall surface adhesion amount QW (= DLQMW * KMW1 + QTRN _i-1).
* KMW2) is compared with the predetermined value B, and the wall adhesion amount Q
When W is less than the predetermined value B, the counter values CDP1 = 0, CDP2 = 0, and XDPC = 0 are initialized as described above. However, when the wall surface adhesion amount QW is equal to or greater than the predetermined value B, the deposit learning is started, and X is determined in step 408.
Set DPC to 1. Here, A <B.

Next, at step 409, if the deposit learning is in progress, the counter CDPC1 indicating the time from the start of the deposit learning is incremented.

In step 410, the time counter CDP
When C1 is 1, acceleration is just started and the following routine is executed so as not to execute the determination of the deposit amount by determining that the burned gas which is accelerating has not reached the oxygen sensor in the exhaust pipe. Bypass. When CDPC1 is 2 or more, the routine proceeds to step 411, where it is judged by the oxygen sensor whether it is rich or lean. When it is determined that the vehicle is rich in step 411, the process proceeds to step 412,
The rich / lean determination value counter CDPC2 is decremented. On the contrary, when it is judged to be lean in step 411, the routine proceeds to step 413, where the rich / lean judgment value counter CDPC2 is incremented.

Next, at step 414, when the above routine is looped 10 times (time counter CDPC1
When the counter becomes 10 counters), the process proceeds to step 415 only when the loop is repeated 10 times. This step 41
In No. 5, when the total number of decrements and increments for nine loops, CDPC2, is 4 or more, it is determined that the air-fuel ratio state during acceleration of the internal combustion engine is lean and the deposit amount is large. This is because when the deposit amount is large, the surface area of the intake manifold is large, and the amount of adhered fuel is large and the fuel amount is lean. If it is determined to be lean, the deposit learning value KDPC is incremented by a predetermined amount.
On the contrary, when CDPC2 is less than 4, the process proceeds to step 417, and it is determined whether CDPC2 is -4 or less (it is determined whether rich). When CDPC2 is -4 or less, it is determined that the air-fuel ratio state during acceleration of the internal combustion engine is rich and the deposit amount is small, and in step 418, the deposit learning value KDPC is decremented by a predetermined amount. Also,
When CDPC2 is -4 or more and 4 or less, the deposit learning value KDPC is continuously maintained. In this way, the deposit learning value KDPC is updated according to the lean or rich degree of the air-fuel ratio during acceleration. Here, the deposit learning value KDPC is stored in the backup RAM and is not erased even after the engine is stopped.

Finally, after the deposit learning value is updated, in step 419, CDPC1, CDPC2, XD
PC is initialized to 0.

Next, the routine for calculating the initial value of fuel increase, which is executed only when the engine is started, will be described with reference to FIG.

When the ignition switch is turned on,
As shown in FIG. 7, the water temperature is detected in step 501. The warm-up increase FWL, the first post-start increase FASE1, obtained from Table 6, Table 7, and Table 8 based on the detected water temperature and the like.
An initial value of the second post-start increase FASE2 is calculated (step 503).

[0040]

[Table 6]

[0041]

[Table 7]

[0042]

[Table 8]

Next, at step 505, the initial value of the third post-start increase amount FASE3 is calculated from the following equation. Here, FASE3B can be obtained from FIG. 14, which is a two-dimensional map of water temperature, and KDPC can be obtained from a deposit learning value calculation routine.

FASE3 = FASE3B * KDPC Further, instead of the two-dimensional map of the water temperature, the post-start increase amount FASE3 may be obtained from the three-dimensional map (FIG. 15) from the water temperature and the deposit learning value KDPC.

Next, a damping routine for attenuating the initial value of the second post-start increase amount FASE2 set at the time of starting after the completion of starting will be described with reference to FIG.

First of all, this routine is executed 2
It is determined whether or not more than a second has passed (step 60).
1). If it is less than 2 seconds after the start is completed, this routine is ended, but if it is 2 seconds or more after the start is completed, the routine proceeds to step 602, and the second post-start increase amount FASE2 is subtracted by a predetermined amount.
Since this routine rotates every 32 ms for a predetermined period of time, the second post-start amount increase value FAS is started 2 seconds after the start is completed.
E2 is gradually attenuated, and when the second post-start increase amount FASE2 becomes 0, the second post-start increase amount FASE2 remains 0.

Similarly, the first and third post-start increase amount values FASE
A damping routine for damping the initial value set at the time of starting in 1 and FASE 3 will be described with reference to FIG.
However, this first and third post-start increase amount values FASE1, FA
In SE3, a routine is started every rotation.

Step 701 in FIG. 9 determines whether or not the engine is starting. This routine is ended at the time of starting, but when it is not starting, the routine proceeds to step 702, where it is judged whether a predetermined time M has elapsed after the starting. If it is less than the predetermined time M after the start, skip the rotation damping step 703 of the third post-start increase amount FASE3 in step 703.
After the start, the increased value FASE3 is held (FIG. 16). However, if it is more than the predetermined time M after the start, the routine proceeds to step 703, where the third post-start increase amount FASE3 is decreased by the predetermined amount. The first post-start increase amount FASE1 is decreased by a predetermined amount each time the routine goes around immediately after the start (step 7).
04). Here, the value of the predetermined time M after the start is changed according to the water temperature as shown in FIG. Next, step 7
In 05 to 708, the first and third post-start increase amount values FASE
1, FASE3 is set to 0 or less.

Next, FIG. 10 showing a routine for calculating the fuel injection amount is shown as a routine different from FIG. First,
In step 801, it is determined whether or not the engine is starting. If it is at the time of starting, the following fuel injection amount TAU at the time of starting is calculated and this routine is ended. Where T
AUST is calculated from the water temperature, and KNEST is calculated from the rotation speed.

TAU = TAUST * KNEST On the contrary, if it is after the start, it is judged whether or not it is in the idle state (step 803). If it is not idle, in step 804, the third post-start amount increase FASE
If 3 is set to 0 and the engine is idling, the fuel injection amount is calculated by adding the FASE3 value calculated in FIG. 9 above.

In step 805, as shown by the following equation, first, the basic fuel injection amount TP is changed to the predicted intake air amount P.
Calculated from MFWD and rotational speed NE, and as correction coefficients for TP, as shown in the following formula, correction amounts for the first, second and third post-start increase amounts FASE1, FASE2, FASE3 and warm-up amount FWL, etc. Is the value added. here,
φ is another correction coefficient. Further, the fuel adhesion correction amount FMW is added to the basic fuel injection amount TP corrected by the correction coefficient.

TAU = TP * (FASE1 + FASE2
+ FASE3 + FWL + φ) + FMW As described above, in steps 405 and 407 in FIG. 6, the start of the deposit learning is determined by comparing the wall surface adhesion amount QW with the predetermined values A and B, respectively. The wall surface adhesion amount QW is the same as the portion in parentheses of the calculation formula of the fuel adhesion correction amount FMW which is the transient correction amount, and the correction coefficient KF used in this calculation formula.
The MW is substantially the same as the value obtained by adding 1 to the deposit learning value KDPC when the cooling water temperature is sufficiently high and the rotation speed is 2400 rpm or more. That is, the wall surface adhesion amount QW represents the degree of reflection of the deposit learning value with respect to the transient correction amount. Therefore, when the wall surface adhesion amount QW, which is the degree of this reflection, is large, that is, when the air-fuel ratio changes significantly with respect to the change in the deposit learning value, the deposit learning value KDPC is learned and the learning speed is increased to increase the learning speed. If the degree of reflection is small, that is, if the change in the air-fuel ratio is small with respect to the change in the deposit learning value, the deposit learning value KD
The learning is passively performed by stopping the learning of the PC and reducing the learning speed, which reduces erroneous learning.

[0053]

As described above, according to the fuel injection amount learning control system for an internal combustion engine of the present invention, the false learning can be reduced by changing the deposit learning speed based on the transient correction amount. It is useful.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a layout view of an engine body according to an embodiment of the present invention.

FIG. 3 is a detailed diagram of a control circuit.

FIG. 4 is a flow chart diagram for calculating an expected intake air amount.

FIG. 5 is a flowchart for calculating a fuel adhesion correction amount.

FIG. 6 is a flow chart of deposit learning value calculation.

FIG. 7 is a flow chart for calculating a fuel increase initial value at the time of starting.

FIG. 8 is a flowchart of a second increase amount calculation after starting.

FIG. 9 is a flowchart of first and second post-start amount increase calculation.

FIG. 10 is a flowchart of fuel injection amount calculation.

FIG. 11 is a three-dimensional map for calculating the intake pipe pressure from NE and TA.

FIG. 12 is a three-dimensional map for calculating weighting from NE and intake pipe pressure.

FIG. 13 is a diagram showing a relationship between an intake air amount predicted value and a measured value.

FIG. 14 is a two-dimensional map of FASE3B and water temperature in the third post-start increase.

FIG. 15 is a three-dimensional map for calculating a third post-start increase amount from the deposit learning value and the water temperature.

FIG. 16 is a third attenuation diagram of the increased amount after starting.

FIG. 17 is a diagram showing a relationship between M and water temperature, which are kept constant for a predetermined time after starting.

[Explanation of symbols]

 1 Gasoline engine main body 4 Exhaust pipe 5 Intake pipe 7 Throttle valve 8 Negative pressure sensor 9 Oxygen sensor 10 Fuel injection valve 11 Intake temperature sensor 12 Throttle sensor 13 Knock sensor 15 Water temperature sensor 16 Igniter 17 Distributor 18 Rotation angle sensor 19 Cylinder discrimination sensor 20 Electronic control circuit 21 Key switch 30 Central processing unit 31 ROM 32 RAM 33 Backup RAM

Claims (1)

[Claims] 1. A fuel injection amount learning control device for an internal combustion engine, wherein a deposit learning value is increased / decreased in accordance with an air-fuel ratio of a transient state of the internal combustion engine, and the deposit learning value is integrated and reflected in a transient correction amount of fuel injection. A fuel injection amount learning control device for an internal combustion engine, comprising: learning speed control means for varying an increase / decrease speed of the deposit learning value based on a transient correction amount.