JP2742445B2 - Engine learning control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a learning control device for an engine that corrects a setting error of a learning value for compensating for deterioration of various sensors or variation for each product.

[Prior Art and Problems to be Solved by the Invention] Conventionally, a learning control device of this kind has been disclosed in, for example,
No. 150 and Japanese Patent Application Laid-Open No. 61-25949. In this prior art, a fuel injection amount (fuel injection pulse width) Ti is calculated by Ti = Tp × COEF × α × KBLRC, and a drive pulse corresponding to the fuel injection amount Ti is given to an injector at a predetermined timing to perform fuel injection. Have done it.

Here, Tp is a basic fuel injection amount (basic fuel injection pulse width), COEF is a correction coefficient for various increments, α is an air-fuel ratio feedback correction coefficient set by proportionally integrating control of the O2 sensor output voltage, and KBLRC is a learning correction coefficient. The learning value KLR stored in the corresponding address of the learning value table is searched by using the operating state variable at that time as a parameter, and the value is obtained by interpolation calculation.

The learning value KLR is a backup RAM of a control unit constituted by a microcomputer or the like.
Are stored in a learning value table having a plurality of addresses provided in the air-fuel ratio feedback correction coefficient α.
The learning value KLR of the corresponding address corresponding to the operating condition at that time in the learning value table is updated so that the base air-fuel ratio when = 1.0 is set to the target air-fuel ratio (for example, the stoichiometric air-fuel ratio λ = 1.0). I have. This learning value KLR is retrieved from the corresponding address in the learning value table corresponding to the operating state at that time, and a learning correction coefficient KBLRC is set by interpolation calculation and used for the fuel injection amount calculation as in the above equation, so that the components (Intake air amount sensor, injector, pressure regulator, control unit, etc.) over time and variation among products, or injector pulse width-
The controllability is improved by eliminating the deviation of the base air-fuel ratio from, for example, the stoichiometric air-fuel ratio λ = 1.0 due to the non-linearity of the flow characteristic, and reducing the proportional constant P and the integral constant I of the air-fuel ratio feedback correction coefficient α. To improve fuel economy and exhaust emissions.

If the learning correction coefficient KBLRC is to compensate for the deterioration of the intake air amount measurement system such as the intake air amount sensor constituting the operating state parameter detection means, as shown in FIG. Since the deviation of the air-fuel ratio due to the deterioration of the air-fuel ratio increases with the increase of the intake air amount Q, the learning value KLR in the learning value table increases as shown in FIG. 10 in order to compensate for the deviation of the air-fuel ratio. The value is set to a large value as the value increases.

Generally, in a region where the traveling frequency is high such as a steady operation region, the learning value KLR is relatively frequently updated, and the line connecting the point coordinates of the learning value KLR draws a gentle curve. In the passing area when shifting from the medium-speed operation area to the high-speed operation area, the learning value KLR is not accurately set because the learning frequency is low, and the passing area has a concave or convex shape as shown by the point coordinates indicated by the arrow in FIG. When a fuel injection amount Tp is corrected by a learning correction coefficient KBLRC which is set based on a learning value KLR having the setting error due to a setting error, the air-fuel ratio is shifted. This leads to deterioration in controllability.

[Object of the Invention] The present invention has been made in view of the above circumstances, and even in an operation region where learning is less frequent, a setting error of a learning value is appropriately corrected, thereby significantly improving air-fuel ratio controllability. It is an object of the present invention to provide an engine learning control device that can perform the learning.

[Means for Solving the Problems] In order to achieve the above object, the present invention specifies an address of a learning value table from operating state parameters, and sets a learning correction coefficient based on a learning value stored in the address. In the learning control device for an engine that corrects the basic fuel injection amount with the learning correction coefficient, the learning values stored for each address in the learning value table are averaged in order from the larger parameter to the smaller parameter. A learning value correcting means for correcting a setting error of each learning value.

[Operation] In the above configuration, the learning value stored for each address of the learning value table is averaged in order from the higher parameter side to the lower parameter side by the learning value correction means, so that the learning value of the entire operation region is obtained. Becomes smooth, and the setting error of the learning value is corrected.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 to 8 show an embodiment of the present invention, FIG. 1 is a functional block diagram of a control device, FIG. 2 is an overall schematic diagram of an engine control system, and FIG. 3 is an air-fuel ratio feedback control determination map. FIG. 4 (a) is an explanatory diagram of a matrix for determining a steady state, FIG. 4 (b) is an explanatory diagram of a learning value table, and FIG. 4 (c) is a relationship between operating state parameters and learning values. FIG. 5 is an explanatory diagram of an O2 sensor output and an air-fuel ratio feedback correction coefficient. FIG. 6 is a flowchart showing a procedure for updating a learning value. FIG. 7 is a flowchart showing a means for correcting a learning value. FIG. 5 is a flowchart showing the air-fuel ratio control procedure.

(Configuration) In the drawing, reference numeral 1 denotes an engine body, and in the drawing, a horizontally opposed four-cylinder engine. An intake manifold 3 communicates with a suction port 2a formed in a cylinder head 2 of the engine body 1, and a throttle chamber 5 communicates with an upstream side of the intake manifold 3 via an air chamber 4, and the throttle chamber 5 Is connected to an air cleaner 7 via a suction pipe 6.

An intake air amount sensor (hot wire type air flow meter in the figure) 8 is provided immediately downstream of the air cleaner 7 of the intake pipe 6, and a throttle valve 5 a provided in the throttle chamber 5 is provided with a throttle valve. An idle switch 10 for detecting the fully closed state of the position sensor 9 and the throttle valve 5a is provided in series.

An injector 11 is disposed immediately upstream of each intake port 2a of each cylinder of the intake manifold 3.

Further, the crankshaft 1b of the engine body 1
A crank rotor 12 having a projection or a slit at a predetermined crank angle on the outer periphery thereof is fixedly mounted. A crank angle sensor 13 such as an electromagnetic pickup for detecting a crank angle is provided on the outer periphery of the crank rotor 12.
Are opposed to each other.

Further, a cooling water temperature sensor is provided in a cooling water passage (not shown) forming a riser formed in the intake manifold 3.
14 is coming.

Also, an exhaust port formed in the cylinder head 2
An O2 sensor 16 faces an exhaust pipe 15 communicating with 2b.
Reference numeral 17 denotes a catalytic converter.

The power of the engine control system is supplied by a battery 18, and the voltage of the battery 18 is made stable by a constant voltage circuit 20a to operate the sensors and the control device 20.

(Circuit Configuration of Control Device) The control device 20 includes a CPU (central processing unit) 21, a ROM,
22, RAM23, backup RAM (non-volatile RAM) 24 and I / O
Interfaces 25 are connected to each other via a bus line 26. The input ports of the I / O interface 25 are connected to the intake air amount sensor 8, the throttle position sensor 9, the idle switch 10 , Crank angle sensor 13, cooling water temperature sensor
14 and the O2 sensor 16, and a voltage detection circuit 20b for monitoring the voltage of the battery 18 is connected. The injector 11 is connected to an output port of the I / O interface 25 via a drive circuit 27.

The ROM 22 stores a control program and fixed data, and the RAM 23 stores data obtained by processing output signals of the respective sensors and data processed by the CPU 21. In the backup RAM 24,
A learning value table TLR, which will be described later, is stored, and the stored data is retained even when the engine key switch is OFF by, for example, battery backup.

Further, the CPU 21 follows the control program stored in the ROM 22 and executes the RAM 23 and the backup RAM 24 according to the control program.
The fuel injection amount Ti is calculated on the basis of the various data stored in the controller 11 and a drive pulse signal corresponding to the fuel injection amount Ti is output to the injector 11 via the drive circuit 27 at a predetermined timing.

(Functional Configuration of Control Device) As shown in FIG. 1, the control device 20 includes an intake air amount calculation means 11, an engine speed calculation means 32, various increase correction coefficient setting means 33, a voltage correction coefficient setting means 34, Basic fuel injection amount setting means 35, air-fuel ratio feedback control determination means 36,
Air-fuel ratio feedback correction coefficient setting means 37, learning condition determining means 38, learning value updating means 39, learning value table TLR, learning value correcting means 40, learning correction coefficient setting means 41, fuel injection amount setting means 42, injector driving means 43 Consists of

The intake air amount calculating means 31 reads an output signal from the intake air amount sensor 8 and calculates an intake air amount Q.

The engine speed calculating means 32 calculates the engine speed N based on the output signal from the crank angle sensor 13.

The above-mentioned various increase correction coefficient setting means 33 reads output signals from the throttle position sensor 9, the idle switch 10, and the cooling water temperature sensor 14, and performs water temperature correction, post-idle increase correction, throttle full-open increase correction, acceleration correction, and the like. The various increase correction coefficients COEF are set.

The voltage correction coefficient setting means 34 reads the invalid injection time (pulse width) of the injector 11 from a table (not shown) according to the terminal voltage of the battery 18, and sets a voltage correction coefficient Ts for interpolating the invalid injection time.

The basic fuel injection amount setting means 35 includes an intake air amount Q calculated by the intake air amount calculation means 31 and an engine speed N calculated by the engine speed calculation means 32.
The basic fuel injection amount Tp is calculated by Tp = K × Q / N (1) (K: constant), or is set by table lookup using the intake air amount Q and the engine speed N as parameters.

The air-fuel ratio feedback control determining means 36 reads the output signal of the O2 sensor 16 and outputs an air-fuel ratio feedback control stop signal to the air-fuel ratio feedback correction coefficient setting means 37 when the O2 sensor 16 is in an inactive state. At the same time, it determines whether the air-fuel ratio feedback control condition is satisfied even if the O2 sensor 16 is in the active region, and instructs the air-fuel ratio feedback correction coefficient setting means 37 whether to perform the air-fuel ratio feedback control.

The activation state of the O2 sensor 16 is determined, for example, when the difference between the O2 sensor output voltage maximum value EMAX and the output voltage minimum value EMIN per predetermined time is less than a set value, the O2 sensor 16 is determined to be inactive. If the value is equal to or more than the set value, it is determined that the O2 sensor 16 is in the active state.

Whether the air-fuel ratio feedback control condition is satisfied even when the O2 sensor 16 is in the active state is determined by using the engine speed N and, for example, the engine load data L based on the basic fuel injection amount Tp as a third parameter. From the air-fuel ratio feedback control determination map shown in FIG.
Is equal to or higher than the set rotation speed Ns (for example, 4500 rpm) (N ≧ Ns),
Alternatively, the load data L is equal to or greater than the set load Ls (L ≧ L
s) (substantially fully open region of the throttle), the air-fuel ratio feedback control stop signal is output to the air-fuel ratio feedback correction coefficient setting means 37, and L <Ls, N <Ns, and
Only when the O2 sensor 16 is in the active state, the air-fuel ratio feedback control condition is instructed to the air-fuel ratio feedback correction coefficient setting means 37 to instruct the air-fuel ratio feedback control.

In the air-fuel ratio feedback correction coefficient setting means 37,
When the air-fuel ratio feedback control determining means 36 determines that the air-fuel ratio feedback control condition is satisfied, the output voltage (output signal) of the O2 sensor 16 is compared with the slice level voltage, and the air-fuel ratio feedback correction coefficient is determined by the comparative integration control. Set α.

The air-fuel ratio feedback correction coefficient setting means 37
When the air-fuel ratio feedback control determining means 36 determines that the O2 sensor 16 is in an inactive state or is in a substantially fully open region of the throttle and instructs to stop the air-fuel ratio feedback control, the air-fuel ratio feedback correction coefficient α is set to α = 1.0
To stop the air-fuel ratio feedback control.

The learning condition determining means 38 reads the output voltage of the O2 sensor 16 and reads the O2 sensor output voltage maximum value EMA per predetermined time.
When the difference between X and the predetermined output voltage value EMIN is equal to or greater than the set voltage value E0 (for example, 300 mV) (EMAX-EMIN ≧ E0), the cooling water temperature TW signal of the cooling water temperature sensor 14 is read, and the cooling water temperature TW is set to the set value TW0. (TW ≧ TW0,
Further, in a matrix (see FIG. 4 (a)) in which the load data L (basic fuel injection amount Tp) and the engine speed N are used as parameters, the basic fuel set by the basic fuel injection amount setting means 35 is set. The section in the matrix is determined from the load data L based on the injection amount Tp and the engine speed N calculated by the engine speed calculating means 32,
When this section is the same as the section selected last time, and the output voltage of the O2 sensor 16 rotates n times in the area of this section, the engine is in the steady operation state, and it is determined that the learning condition is satisfied at this time. .

The learning value table TLR is formed in the backup RAM 24, and has addresses a0 corresponding to the ranges P0 , P1 , P2 ,..., PN-1 , PN using the intake air amount Q as a parameter P as shown in FIG. , a1, a2,..., aN−1, aN, and the learning value KLR is stored in each address. The learning value KLR in each address is KLR = 1.0 as an initial value.
Is stored.

When the learning condition determining unit 38 determines that the learning condition is satisfied, the learning value updating unit 39 obtains a deviation amount between an average value of the air-fuel ratio feedback correction coefficient α and a reference value in a predetermined section, and obtains the learning value. The learning amount KLR stored in the corresponding address using the intake air amount Q in the table TLR as a parameter is calculated by adding the above-mentioned deviation amount to +,-of the sign of the deviation from the reference value.
Is added or subtracted by a predetermined ratio to obtain the learning value KLR.
To update.

The learning value correcting means 40 averages the learning values KLR stored at the respective addresses of the learning value table TLR in order from the larger side of the parameter P (intake air amount Q) to the smaller side to obtain the learned value KLR of each address. Fix it. The procedure for correcting the learning value KLR will be described later.

The learning correction coefficient setting means 41 calculates the intake air amount Q at that time.
The learning value KLR stored at the corresponding address of the learning value table TLR is read using the parameter as a parameter, and a learning correction coefficient KBLRC is set by interpolation calculation.

The fuel injection amount setting means 42 converts the basic TP set by the basic fuel injection amount setting means 35 into the various increase correction coefficient setting means 33, voltage correction coefficient setting means 34, and air-fuel ratio feedback correction coefficient setting means 37. , Learning correction coefficient setting means 41
, The air-fuel ratio feed correction coefficient α, the learning correction coefficient KB
The fuel injection amount Ti is corrected by the LRC, and the fuel injection amount Ti is set by the following equation: Ti = TP × KBLRC × COEF × α + Ts (2), and a drive pulse signal corresponding to the fuel injection amount Ti is given at predetermined timing via the injector driving means 43. Output to the injector 11.

(Operation) Next, a control procedure of the control device 20 having the above configuration will be described with reference to the flowcharts of FIGS.

(Learning value update procedure) As shown in FIG. 6, first, in step S101, the O2 sensor
The output (voltage signal) of the O2 sensor 16 is read in step S102, and the difference between the output voltage maximum value EMAX and the output voltage minimum value EMIN of the O2 sensor 16 per predetermined time and the set value E0 (for example, 300 m
V) and comparing the, EMAX-EMIN <Exit routine in the case of Eo, it reads the cooling water temperature T _W signal from the coolant temperature sensor 14 in EMAX-EMIN ≧ Eo step step S103, the cooling water temperature Tw at step S104 And the set value TWO (for example, 60
° C), and if Tw <Two, the routine ends. If Tw ≧ Two, the routine proceeds to step S105.

That is, in steps S102 and S104, the O2 sensor 1
The active state determination of step 6 is performed. When EMAX-EMIN ≧ Eo and Tw ≧ Two, the O2 sensor 16 is determined to be in the active state, and the process proceeds to step S105.

In step S105, the output signal of the crank angle sensor 13 is read to calculate the engine speed N, and the output signal of the intake air amount sensor 8 is read to calculate the intake air amount Q.

Next, in step S106, the basic fuel injection amount TP is set based on the above equation (1), and is set as the load data L.

Next, proceeding to step S107, it is determined whether or not the engine speed N calculated in step S105 and the load data L set in step S106 are within the steady state determination region, that is, as shown in FIG. It is determined whether it is within the indicated matrix range ( No ≦ N ≦ Nn , Lo ≦ L ≦ Ln ).

When it is determined that the engine speed N and the load data L are within the matrix range and are within the learning value update control target range, the partition position in the matrix is determined by the engine speed N and the load data L, for example, It is specified in the matrix like the section D1 in FIG. 4A, and the process proceeds to step S108.

On the other hand, if the engine speed N or the load data L is outside the matrix range and outside the learning value update control target range, the routine ends.

In step S108, the section position OLD in the matrix specified in the previous routine is compared with the section position NEW specified this time to determine whether or not the engine is in a steady operation state. That is, when the section position OLD specified in the previous routine and the section position NEW specified this time are not the same, the operation proceeds to step S109 without determining the unsteady operation state and updating the learning value, and is performed in the current routine. The partition position in the matrix is stored in the RAM 23 as the previous partition position data (OLD ← NEW), the process proceeds to step S110, the counter is cleared (COUNT ← φ), and the routine ends.

In the first routine, since there is no previous section position data, the process jumps from step S107 to step S109, and ends the routine via step S110.

On the other hand, if it is determined in step S108 that the partition position in the matrix specified in the current routine is the same as the previous partition position (NEW = OLD), the process proceeds to step S111, where the output voltage of the O2 sensor 16 is read. In rare cases, it is determined whether the output voltage is alternately inverted between the rich side and the lean side.

If there is no inversion of the output voltage of the O2 sensor 16, the routine ends.
Proceeding to S112, the count value of the counter is counted up (COUNT ← COUNT + 1).

Next, in step S113, if the count value of the counter is smaller than n (for example, 3), the routine ends, while if the count value is equal to or larger than n, step S114.
Proceed to.

That is, a steady state determination is performed in steps S108, S111, and S113, and the operation state based on the load data L and the engine speed N is substantially constant.
Only when the output voltage of 16 is inverted n times or more, it is determined that the engine is in the steady operation state, and the learning value KLR is updated.

When it is determined in the above steps that the engine operation is in the steady state and the process proceeds to step S114, the counter is cleared, the output voltage of the O2 sensor 16 is compared with the reference voltage, and the air-fuel ratio feedback correction coefficient α is set by proportional integral control. An average value of the air-fuel ratio feedback correction coefficient α is calculated, and a deviation amount Δα between the average value and the reference value α is calculated.

That is, for the air-fuel ratio feedback correction coefficient α, for example, as shown in FIG. 5, an average value during three steps is obtained, and a reference value α0 (= 1.0) of this average value is obtained.
Then, the process proceeds to step S116.

In step S116, the learning value KLR is searched from the corresponding address of the learning value table TLR using the intake air amount Q at that time as a parameter, and the process proceeds to step S117.
From the learning value KLR retrieved in step 16 and the deviation amount Δα calculated in step S115, a new learning value KLR is set by the following equation: KLR → KLR + Δα / M, and the learning value table TLR
The learning value KLR of the corresponding address in is updated, and the routine ends.

The coefficient M in the above equation is a constant (weight of the weighted average) that determines the ratio of adding the deviation amount Δα based on the deterioration characteristic of the intake air amount measurement system at the time of updating the learning value. It is stored in the ROM 22.

As described above, at the addresses ao to aN (see FIG. 4 (b)) where the intake air amount Q in the learning value table TLR is specified as the parameter P, the intake air amount measurement system such as the intake air amount sensor 8 is provided. The latest learning value KLR that compensates for the aging degradation of
Is stored. The relationship between the learning value KLR and the parameter P (intake air amount Q) is as shown by the mark in FIG. 4 (c).

(Learning Value Correction Procedure) As is clear from the flowchart of FIG. 6, the frequency of updating the learning value KLR differs for each operation region (for each address of the learning value table TLR).

That is, in a region that is merely a passing point, such as a passing region from a low speed to a medium speed and a passing region from a medium speed to a high speed, since the learning frequency is low, as shown by a coordinate point indicated by an arrow in FIG. Is deviated from the line connecting the learning values KLR in a concave or convex manner.

The in-learning correcting means 40 corrects the concave and convex of the learning value KLR caused by the learning frequency. The correcting procedure will be described with reference to the flowchart of FIG.

This program is executed every predetermined calculation cycle.

First, in step S201, the size of the learning value table TLR, that is, the number N of addresses in the learning value table TLR is substituted into a specific work area of the RAM 23 to be n.

Next, in step S202, the learning value table TLR corresponding to the work area n substituted in step S201.
Of the learning value KLRn stored at the address an of the learning value table TLR and the learning value KLRn-2 stored at the address an-2 of the learning value table TLR are averaged. Is updated (KLRn-1 ← KLRn + KLRn-2) / 2).

After that, in step S203, “1” is subtracted from n substituted in step S201, and n substituted in the specific work area of the RAM 23 is rewritten (n ← n−1).

Then, the process proceeds to step S204, where n is assigned to the work area of the RAM 23 rewritten in step S203.
Is determined whether or not n = 0, and if n ≠ 0, the process returns to step S202 and n rewritten in step S203.
The learning value K stored in the address an-1 of the learning value table TLR is calculated based on the average value of the learning values KLRn and KLRn-2 stored in the addresses an and an-2 of the learning value table TLR based on
Update LRn-1.

On the other hand, when it is determined in step S204 that n = 0,
That is, the learning value K stored in the address of the smaller parameter P sequentially from the address aN-1 of the larger parameter P (intake air amount Q) of the learning value table TLR.
When the correction of the LR is performed and the correction of the learning value KLR1 stored at the address a1 is completed, the program ends.

As described above, since the correction of the learning value KLR by the averaging process is performed in order from the side having the larger parameter to the side having the smaller parameter, the learning value KLR is corrected by performing the averaging process from the side having the smaller parameter to the larger side. Compared to the case, as shown by the crosses in FIG. 4 (c), the learning value KLR in the learning value table TLR can be corrected appropriately without being substantially affected by a concave or convex setting error. .

The learning value KLR stored in the address aN corresponding to the largest parameter in the learning table TLR and the address ao corresponding to the smallest parameter in the learning table TLR are not corrected, but the address aN is the parameter P in the learning value table TLR. Is the extreme end on the larger side, is a high-speed operation area, not a pass area, and has a high learning frequency. Therefore, the learning value KLR stored at this address aN has a concave or convex shape compared to the surrounding learning value KLR. No setting error occurs and the address
There is no need to modify the learning value KLR stored in aN.

Further, as shown in FIG. 9, the deviation of the air-fuel ratio due to the deterioration of the intake air amount measuring system such as the intake air amount sensor 8 is hardly present on the side where the intake air amount Q is small, and is therefore stored in the address ao. It is not necessary to correct the learned value KLR.

(Air-fuel ratio control procedure) Next, the air-fuel ratio control procedure by the control device 20 will be described with reference to the flowchart shown in FIG.

First, in step S301, an output signal from the intake air amount sensor 8 and the crank angle 13 is read, and an intake air amount Q and an engine speed N are calculated.

Next, the process proceeds to step S302, and the basic fuel injection amount Tp is calculated from the intake air amount Q and the engine speed N calculated in step S301 by the above equation (1) Tp = K × Q / N (K: constant). To step S303.

In step S303, the cooling water temperature from the cooling water temperature sensor 14
The Tw signal, the operation signal from the idle switch 10, and the throttle opening θ signal from the throttle position sensor 9 are read, and in step S304, various increases related to water temperature correction, post-idle increase correction, throttle full-open increase correction, acceleration correction, etc. Set the correction coefficient COEF for use.

Next, in step S305, the terminal voltage of the battery 18 is read, a voltage correction coefficient Ts for interpolating the invalid injection time of the injector 11 is set, and the process proceeds to step S306.

In step S306, the output (voltage) signal of the O2 sensor 16 is read, and the difference between the output voltage maximum value EMAX and the output voltage minimum value EMIN for a predetermined time is obtained. Is determined to be active, and the process proceeds to step S307. On the other hand, the maximum value E of the output of the O2 sensor 16 per predetermined time E
If the difference between MAX and the minimum output voltage value EMIN is less than the set value,
The O2 sensor 16 determines that it is inactive and proceeds to step S309, fixes the air-fuel ratio feedback correction coefficient α to 1.0, suspends the air-fuel ratio feedback control, and proceeds to step S310.
Proceed to.

In step S307, whether the air-fuel ratio feedback control condition is satisfied using the engine speed N calculated in step S301 and the engine load data L based on the basic fuel injection amount Tp set in step S302 as parameters. Determine whether or not.

When the engine speed N is equal to the set speed Ns (for example, 4500 rp)
m) (N <Ns) and when the load data L is less than the set load Ls (L <Ls), the process proceeds to step S308 as satisfying the air-fuel ratio feedback control condition.

On the other hand, when the engine speed N is equal to or more than the set number Ns (N ≧ Ns),
Alternatively, the load data L is equal to or greater than the set load Ls (L ≧ L
In the case of s), that is, in the substantially fully open region of the throttle, it is determined that the operation region is in the air-fuel ratio feedback control suspension region, the process proceeds to step S309, and the air-fuel ratio feedback correction coefficient α is fixed to α = 1.0, and the air-fuel ratio The feedback control is stopped, and the process proceeds to step S310.

Note that the activity of the O2 sensor 16 in step S306,
The determination of inactivity is made by reading the cooling water temperature Tw signal from the cooling water temperature sensor 14, and when the cooling water temperature Tw is equal to or lower than a set value (when the engine is in a cold state), the O2 sensor 16 is determined to be in an inactive state. Further, the determination of the satisfaction of the air-fuel ratio feedback control condition in step S307 may be made based on the throttle opening θ as the throttle fully open area determination.

In step S308, the output voltage of the O2 sensor 16 is compared with the slice level, and the air-fuel ratio feedback correction coefficient α is set by proportional integration control, and the flow proceeds to step S310.

In step S310, the learning value KLR is searched from the corresponding address of the learning value table TLR based on the parameter P (intake air amount Q) at the time of the current operation, and the learning correction coefficient KBLRC is set by interpolation calculation.

For example, when the parameter P (intake air amount Q) at the time of the current operation is in the learning value table area, that is, the intermediate point of each parameter in the ao, aN of the both end addresses of the learning value table TIR is defined as Po, PN. In the case of Po ≦ P ≦ PN, it is determined which parameter value Pn−1,, Pn of the address has the parameter P in the present operation (Pn ≦ P <P, where n = 1,2). , 3, ..., N−1, N.The learning value table TIR
, AN at the respective addresses ao, a1,..., AN are set as parameter values Po, P1,. ), Parameter P at present operation
From the corresponding parameter values Pn-1 and Pn and the learning values KLRn-1 and KLRn stored at the addresses an-1 and an indicated by the corresponding parameter values, a learning correction coefficient KBLRC is calculated. And the parameter P during the current operation is P <P
If the learning value is outside the range of the learning value table TLR of o, the learning value KLRo stored at the lowest end address ao indicated by the parameter value Po is set as the learning correction coefficient KBLRC as it is,
Further, when the parameter P at the time of the current operation is outside the range of the learning value table TLR where P> PN, the learning value KLRN stored at the maximum end address aN indicated by the parameter PN is set as the learning correction coefficient KBLRC as it is.

Then, in step S311, the basic fuel injection amount TP set in step S302 is replaced with the values in steps S304, S305, S
308 or S309, and the various increase correction coefficients COEF, voltage correction coefficient Ts, air-fuel ratio feedback correction coefficient α, and learning value correction coefficient KBL set in step S310.
The fuel injection amount Ti is corrected by the RC, and the fuel injection amount Ti is set by the above equation (2) Ti = TP × KBLRC × COEF × α + Ts, and the process proceeds to step S312.

In step SS312, a drive pulse signal corresponding to the fuel injection amount Ti
Is output to

Accordingly, the fuel injection amount is determined using the learning correction coefficient KBLRC set based on the learning value KLR corrected as described above.
Since the Ti is calculated, the air-fuel ratio is prevented from being deviated, and the engine load data L is used as the basic fuel injection amount TP. Alternatively, for example, the fuel injection amount Ti may be used as the load data.

In this embodiment, the initial value of the learning value TLR stored in each address of the learning value table TLR is set to 1.0.
However, it is not always necessary to set the initial value to 1.0. For example, the initial value of the learning value KLR is
0.0 may be set, and in this case, the equation (2) becomes Ti = TP × (1 + KBLRC) × COEF × α + Ts.

Furthermore, in the present embodiment, the operating state parameter P is the intake air amount Q, but the basic fuel injection amount Tp or the fuel injection amount Ti may be used as this parameter.

[Effects of the Invention] As described above, according to the present invention, the address of the learning value table is specified from the operating state parameter, and the learning correction coefficient is set based on the learning value stored in the address. In a learning control device for an engine that corrects a basic fuel injection amount by a correction coefficient, a learning value stored for each address in the learning value table is averaged in order from a parameter having a larger value to a parameter having a smaller value. Since the learning value correcting means for correcting the learning value setting error is provided, the learning value setting error is appropriately set even in the operation region where the learning frequency is low, and the air-fuel ratio control characteristic is greatly improved. Excellent effects such as can be achieved.

[Brief description of the drawings]

1 to 8 show an embodiment of the present invention, FIG. 1 is a block diagram of a control device, FIG. 2 is a schematic diagram of an entire engine control system, and FIG. 3 is a map of an air-fuel ratio feedback control determination map. FIG. 4A is an explanatory diagram of a matrix for steady state determination, FIG. 4B is an explanatory diagram of a learning value table, FIG.
FIG. 5C is an explanatory diagram showing the relationship between the operating state parameter and the learning value, FIG. 5 is an explanatory diagram of the O2 sensor output and the air-fuel ratio feedback correction coefficient, FIG. 6 is a flowchart showing a procedure for updating the learning value, FIG. 7 is a flowchart showing a procedure for correcting a learning value, FIG. 8 is a flowchart showing a procedure for controlling an air-fuel ratio, FIG. 9 and subsequent figures show a conventional example, and FIG. 9 shows the deterioration characteristics of an intake air meter system. FIG. 10 is an explanatory diagram showing the relationship between the intake air amount and the learning value. 28: operating state parameter detecting means, 40: learning value correcting means, P: operating state parameter, TLR: learning value table,
KLR: learning value, KBLRC: learning correction coefficient, TP: basic fuel injection amount.

Claims (1)

(57) [Claims] An engine for identifying an address of a learning value table from operating state parameters, setting a learning correction coefficient based on a learning value stored at the address, and correcting a basic fuel injection amount with the learning correction coefficient. Learning value correction means for averaging a learning value stored for each address of the learning value table in order from a larger parameter to a smaller parameter, and correcting a setting error of each learning value. A learning control device for an engine, comprising: