JP2590941B2 - Fuel injection amount learning control device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel injection amount learning control device for an internal combustion engine,
In particular, the present invention relates to a fuel injection amount learning control device for an internal combustion engine that learns and controls a fuel injection amount during acceleration / deceleration by correcting (learning) acceleration increase and deceleration decrease.

[Conventional technology]

Conventionally, engine load (intake air volume or intake pipe pressure)
The air-fuel ratio feedback correction factor FAF obtained from the O ₂ sensor output that detects the basic fuel injection time TP determined according to the engine speed and the residual oxygen concentration in the exhaust gas and outputs a signal inverted at the logical air-fuel ratio There is known a fuel injection amount control device that performs feedback control of the fuel injection amount so that the combustion air-fuel ratio becomes a logical air-fuel ratio using the above formula. In such a fuel injection amount control device, it is determined whether the vehicle is accelerating or decelerating. When it is determined that the vehicle is accelerating, the fuel injection amount is increased by an acceleration increasing coefficient, and when it is determined that the vehicle is decelerating, the fuel injection amount is determined by a deceleration decreasing coefficient. It has been done to reduce the weight.

However, as the traveling distance of the vehicle increases, deposits adhere to the intake valves and the intake port walls due to changes over time,
Due to the effect of the deposit, the air-fuel ratio shows a lean tendency during acceleration, and the air-fuel ratio shows a rich tendency during deceleration. That is, during acceleration, the throttle opening increases, so the intake pipe pressure is high and the amount of fuel evaporation is small, so that the injected fuel is absorbed by the deposit, and as a result, the fuel supplied to the combustion chamber becomes insufficient and the air-fuel ratio Shows a lean tendency. On the other hand, during deceleration, the fuel absorbed in the deposit evaporates due to the low intake pipe pressure due to the small throttle opening, and the evaporated fuel is supplied to the combustion chamber, so that much fuel is supplied to the combustion chamber. , Indicating an air-fuel ratio rich tendency. FIG. 2 shows the difference between the air-fuel ratio feedback coefficient and the combustion air-fuel ratio of the internal combustion engine (new internal combustion engine) in the initial state and the internal combustion engine with the deposit during acceleration. As can be understood from the figure, in the internal combustion engine in the initial state, the deposit is not attached, so that the air-fuel ratio feedback correction coefficient changes in a constant cycle, and the combustion air-fuel ratio is also controlled to a value near the approximate logical air-fuel ratio. . On the other hand, in an internal combustion engine having a deposit, the air-fuel ratio becomes lean during acceleration, and as a result, the air-fuel ratio feedback correction coefficient changes greatly. In addition, FIG.
The relationship between the deviation ΔPM of the intake pipe pressure for each A and the change frequency of the combustion air-fuel ratio is shown. In the figure, the solid line NEW indicates the change frequency of the air-fuel ratio in the internal combustion engine in the initial state, and the broken line OLD
Indicates the change frequency of the air-fuel ratio of the internal combustion engine to which the deposit has adhered. As can be understood from the figure, in an internal combustion engine with a deposit, the air-fuel ratio becomes more frequent during acceleration (when ΔPM is positive), and during deceleration (when ΔPM is negative). The frequency at which the air-fuel ratio becomes rich is increasing.

For this reason, conventionally, as shown in JP-A-59-203829, when the air-fuel ratio A / F at the time of acceleration is richer than the target air-fuel ratio, the acceleration increase coefficient K _ACC is reduced and the air-fuel ratio A / F is reduced. Is leaner than the target air-fuel ratio, the acceleration increase coefficient K _ACC
Was large and the deceleration reduction coefficient K _DCL when the air-fuel ratio A / F is lean than the target air-fuel ratio with the air-fuel ratio A / F at the time of deceleration when the Ritsuchi than the target air-fuel ratio to increase the deceleration reduction coefficient K _DCL Learning control is performed by reducing the size.

As a technique related to the present invention, Japanese Patent Application Laid-Open No. 59-2038
There is a technique described in Japanese Patent Application Laid-Open No. 29-204, and Japanese Patent Application Laid-Open No. 60-204937.

[Problems to be solved by the invention]

However, in the conventional learning control, the acceleration increase coefficient and the deceleration decrease coefficient are immediately learned when the air-fuel ratio becomes not equal to the target air-fuel ratio at the acceleration / deceleration. There is a problem that erroneous learning occurs because the learning may be performed due to the change, and exhaust emission and drivability deteriorate. That is, in the conventional learning control, since learning is performed without considering the deviation of the air-fuel ratio, there is a problem that learning cannot be performed according to the deviation of the air-fuel ratio due to a change over time. For this reason, the present applicant has already proposed a learning control device that performs learning control according to the deviation of the air-fuel ratio due to a change over time (Japanese Patent Application No. 62-89212).

However, when the engine temperature is high, the intake pipe wall temperature is high and the vaporization state is good, so that the amount of fuel adhering to the intake pipe wall is small, and the effect of the deposit is greatly reflected on the air-fuel ratio, so the learning value (required correction amount) is large. Become. On the other hand, when the engine temperature is low, the amount of fuel adhering to the intake pipe wall surface is large because the intake pipe wall surface temperature is low and the vaporization state is poor, and the learning value is small because the air-fuel ratio is not significantly affected by the deposit. Therefore, if a large learning value learned at a high engine temperature is used as it is at a low engine temperature, overcorrection may occur. Further, when the engine temperature is low, the O ₂ sensor element is in an inactive state and the output becomes unstable, so that erroneous learning may occur.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to judge a deviation tendency of an air-fuel ratio at the time of acceleration / deceleration to correct an air-fuel ratio deviation due to a change with time, and to correct an air-fuel ratio overcorrection or error. An object of the present invention is to provide a combustion injection amount learning control device for an internal combustion engine in which learning does not occur.

[Means for solving the problem]

In order to achieve the above object, the present invention provides acceleration / deceleration state determination means for determining an acceleration / deceleration state, an oxygen concentration sensor for detecting a residual oxygen concentration in exhaust gas, Deviation calculating means for calculating a deviation between the time when the oxygen concentration sensor output is leaner than the target air-fuel ratio, the temperature when the oxygen concentration sensor output is leaner than the target air-fuel ratio, the temperature detecting means for detecting the engine temperature, and the engine temperature. Learns an acceleration increasing coefficient so that the deviation becomes a value within the first predetermined range when the deviation becomes a value outside the first predetermined range during acceleration exceeding a first predetermined temperature. While the engine temperature is decelerating beyond the first predetermined temperature, the deviation may be reduced to a second value.
Learning means for learning a deceleration reduction coefficient such that the deviation becomes a value within the second predetermined range when the engine temperature becomes a value outside the predetermined range. 2. During acceleration exceeding the second predetermined temperature, an amount of fuel determined according to the acceleration increasing coefficient is increased and injected, and during deceleration when the engine temperature exceeds the second predetermined temperature, the amount of fuel determined according to the deceleration decreasing coefficient is increased. Fuel injection means for reducing the amount of fuel injected,
Is included.

[Action]

According to the present invention, the acceleration / deceleration state determination means determines whether the operation state is accelerating or decelerating. The deviation calculating means is:
The difference between the time when the output of the oxygen concentration sensor for detecting the residual oxygen concentration in the exhaust gas indicates a rich state from the target air-fuel ratio and the time when the output of the oxygen concentration sensor indicates a lean state from the target air-fuel ratio is calculated. Calculate. Here, if the time when the oxygen concentration sensor output indicates the rich state from the target air-fuel ratio is longer than the time when the oxygen concentration sensor output indicates the lean state from the target air-fuel ratio, the air-fuel ratio rich state Has continued for longer than the air-fuel ratio lean state, and the air-fuel ratio has shifted toward the rich side. That is, the air-fuel ratio shows a tendency to rich. Therefore, it is possible to determine whether the air-fuel ratio shows a rich tendency or a lean tendency within a certain period from the above deviation. The learning means determines that the deviation has a value outside the first predetermined range during the acceleration in which the period temperature exceeds the first predetermined temperature, that is, when the air-fuel ratio shows a rich tendency and a lean tendency. , The acceleration increase coefficient is corrected so that the deviation becomes a value within the first predetermined range. As described above, when the air-fuel ratio indicates the rich tendency and the lean tendency, the acceleration increasing coefficient is learned so that the deviation becomes a value within the first predetermined range, so that the rich tendency and the lean tendency of the air-fuel ratio are corrected. The fuel injection amount can be controlled so that the air-fuel ratio is controlled near the target air-fuel ratio. Further, the learning means, when the deviation becomes a value outside the second predetermined range during the deceleration during which the period temperature exceeds the first predetermined temperature, that is, when the air-fuel ratio shows a rich tendency and a lean tendency, The deceleration reduction coefficient is learned so that the deviation falls within a second predetermined range, and the rich and lean tendencies of the air-fuel ratio are corrected, so that the air-fuel ratio is controlled near the target air-fuel ratio. The fuel injection means is
In an area where the engine temperature exceeds a second predetermined temperature lower than the first predetermined temperature by a predetermined temperature, an amount of fuel determined by the acceleration increase coefficient learned as described above when it is determined that the vehicle is accelerating is increased. When it is determined that the vehicle is decelerating, the amount of fuel determined according to the deceleration reduction coefficient learned as described above is reduced and injected. In this way, erroneous learning is prevented by learning the acceleration increase coefficient and the deceleration decrease coefficient in a region where the engine temperature exceeds the first predetermined temperature, such as after warm-up,
By learning-controlling the fuel injection amount using the learning value learned in the region where the engine temperature exceeds the second predetermined temperature, the time-dependent change in the air-fuel ratio due to deposits or the like is corrected without being overcorrected.

〔The invention's effect〕

As described above, according to the present invention, the air-fuel ratio deviates toward the rich side from the difference between the time when the oxygen concentration sensor output indicates the air-fuel ratio rich state and the time when the oxygen-concentration sensor output indicates the air-fuel ratio lean state. It is determined whether the air-fuel ratio is lean or lean, and after warm-up, the acceleration increase coefficient and deceleration decrease coefficient are learned so that the learning values are not used as they are at low temperatures. The effect is obtained that the deviation of the air-fuel ratio due to the change over time can be corrected without correction, thereby preventing deterioration of exhaust emission and drivability.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, description will be made using numerical values that do not hinder the present invention, but the present invention is not limited to these numerical values. FIG. 4 shows a four-cylinder four-cycle spark ignition engine (engine) equipped with a fuel injection amount learning control device according to an embodiment of the present invention.
1 shows an outline.

This engine is controlled by a microcomputer 44 as a control circuit.
A throttle valve 8 is disposed downstream of the throttle valve, and a surge tank 12 is provided downstream of the throttle valve 8. An intake air temperature sensor 4 for detecting the intake air temperature is attached near the air cleaner 2, and an idle switch 10 is attached to the throttle valve 8 to turn on the throttle valve when the throttle valve is fully closed. The surge tank 12 is provided with a semiconductor type pressure sensor 6. The output signal from the pressure sensor 6 has a small time constant for removing a pulsating component of the intake pipe pressure (for example, 3 to 5 msec) and a filter 7 composed of a CR filter or the like having a good response (FIG. 5). See). A bypass 14 is provided so as to bypass the throttle valve 8 and communicate between the upstream side of the throttle valve and the downstream side of the throttle valve. An ISC (idle speed control) valve 16 whose degree of opening is adjusted by a solenoid is attached to the bypass passage 14, and the amount of air flowing through the bypass passage 14 is controlled by controlling the current flowing through the solenoid at a duty ratio. The rotation speed during idling is controlled to a target value. Surge tank 12
Is connected to a combustion chamber of the engine 20 via an intake manifold 18 and an intake port 22. A fuel injection valve 24 is attached to each cylinder so as to protrude into the intake manifold 18.

The fuel chamber of the engine 20 is filled with a three-way catalyst through a suction port 26 and an exhaust manifold 28.
It is connected to 27. This exhaust manifold 28
The, O ₂ sensor 30 outputs a signal obtained by inverting the boundary of logical air-fuel ratio by detecting the oxygen concentration in the exhaust gas is attached.
A cooling water temperature sensor 34 is attached to the engine block 32 so as to penetrate the engine block 32 and protrude into the water jacket. This cooling water temperature sensor 34
The engine cooling water temperature is detected, a water temperature signal is output, and the water temperature signal represents the engine temperature. The engine oil temperature may be detected to represent the engine temperature.

An ignition plug 38 is attached to each cylinder so as to penetrate the cylinder head of the engine 20 and protrude into the combustion chamber. The ignition plug 38 is connected to a microcomputer 44 via an igniter having a distributor 40 and an ignition coil. This Distributor 40
A rotation angle sensor 48 composed of a signal rotor fixed to the distributor shaft and a pipe fixed to the distributor housing is mounted therein. The rotation angle sensor 48 outputs an engine rotation speed signal every 30 ° CA, for example.

As shown in FIG. 5, the microcomputer 44 includes a micro processing unit (MPU) 60, a read only memory (ROM) 62, and a random access memory (RA).
M) 64, back-up plum (BU-RAM) 66, I / O ports
68, an input port 70, output ports 72, 74, and 76, and a bus 75 such as a data bus or a control bus for connecting them. The BU-RAM 66 stores an acceleration increase coefficient and a deceleration decrease coefficient described below. An A / D converter 78 and a multiplexer 80 are sequentially connected to the input / output port 68. The multiplexer 80 is connected to the pressure sensor 6 via a filter 7 composed of a resistor R and a capacitor C and a buffer 82, and is connected to the cooling water temperature sensor 34 via a buffer 84, and absorbs via a buffer 85. The temperature sensor 4 is connected. The MPU 60 controls the multiplexer 80 and the A / D converter 78 to sequentially convert the output of the pressure sensor 6, the output of the cooling water temperature sensor 34 and the output of the intake air temperature sensor 4 input via the filter 7 into digital signals.
Store in RAM64. Therefore, the multiplexer 80, the A / D converter 78, the MPU 60, and the like function as sampling means for sampling the output of the pressure sensor and the like at predetermined time intervals.
The input port 70, the rotation angle sensor 48 is connected via a waveform shaping circuit 90 together with the O ₂ sensor 30 is connected via a comparator 88 and a buffer 86. The input switch 70 is connected to the idle switch 10 via a buffer (not shown). Output port 72 is connected to igniter 42 via drive circuit 92, output port 74 is connected to fuel injector 24 via drive circuit 94 with a down counter, and output port 76 is provided via drive circuit 96. It is connected to the solenoid of the ISC valve 16. Note that 98 is a clock, and 99 is a counter. In the ROM 62, a control routine program and the like described below are stored in advance.

Next, a control routine of a first embodiment in which the present invention is applied to the engine will be described.

FIG. 7 shows a routine for calculating an air-fuel ratio feedback correction coefficient FAF for feedback-controlling the air-fuel ratio. In step 180, it is determined whether or not the air-fuel ratio feedback condition is satisfied. Whether the air-fuel ratio feedback condition is satisfied or not is determined according to the operation state. For example, the engine cooling water temperature is not less than a predetermined value (for example, 40 ° C.), not the engine start state, and the fuel cut is not performed. It is determined that the air-fuel ratio feedback condition has been satisfied when the fuel is not being increased and the air-fuel ratio lean control is not being performed. When it is determined in step 180 that any one of the above conditions is not satisfied, that is, when it is determined that the feedback condition is not satisfied, in step 182, the air-fuel ratio feedback correction factor FAF is set to 1.0, and the air-fuel ratio feedback correction factor FAF is stored in RAM. In a predetermined area.

On the other hand, if it is determined in step 180 that all of the above conditions are satisfied and the air-fuel ratio feedback condition is satisfied, the output of the O ₃ sensor is taken in step 183 and then the output of the O ₂ sensor becomes the air-fuel ratio rich in step 184. Is determined. When the O ₂ sensor output is determined to indicate an air-fuel ratio Ritsuchi the flag CAFR in step 188 after the reset flag CAFL at step 186 it is determined whether or not it is reset. When the flag CAFR is reset, at step 191 after the O ₂ sensor output is obtained by subtracting the proportional constant R _s from the air-fuel ratio fed back correction coefficient FAF in step 190 for a time when inverted from lean air-fuel ratio in Ritsuchi flag CAFR
Set. When the flag CAFR is judged to be excisional in step 188, i.e. after the O ₂ sensor output is inverted from lean air-fuel ratio in Ritsuchi the step 189
Calculates the integration constant K _i from the air-fuel ratio fed back correction coefficient FAF in.

In step 184 when the O ₂ sensor output is determined to indicate a lean air-fuel ratio, the flag CAFL in step 194 after the reset flag CAFR at step 192 it is determined whether or not it is reset. When the flag CAFL is reset, the flag in O ₂ step 197 after adding the proportional constant R _s to the air-fuel ratio fed back correction coefficient FAF in step 196 the sensor output is when inverted from the air-fuel ratio Ritsuchi lean CAFL Set. Meanwhile, when the flag CAFL is determined to be excisional at step 194, i.e., adding the integral constant K _i in the air-fuel ratio fed back correction coefficient FAF in step 195 after the O ₂ sensor output is inverted from the air-fuel ratio Ritsuchi lean I do.

FIG. 1 shows a routine executed every 360 ° CA. In step 100, it is determined whether or not the engine coolant temperature THW exceeds a first predetermined temperature (for example, 70 ° C.). It is determined whether it is after. The first predetermined temperature is a value higher than the value of the cooling water temperature under the air-fuel ratio feedback control condition. If it is determined that the motor has been warmed up, go to Step 101
In step 102, it is determined whether other learning conditions (for example, air-fuel ratio feedback control conditions) are satisfied, and if these conditions are satisfied, in step 102, the intake pipe 360 ° CA before the current intake pipe pressure PM _{NEW is obtained.} The pressure PM _OLD is subtracted to calculate a deviation DLPM of the intake pipe pressure. In the next step 103, the deviation DLPM of the intake pipe pressure is a positive predetermined value (for example, 2 mmHg).
It is determined whether or not the vehicle is accelerating by determining whether or not the vehicle speed exceeds the vehicle speed. When the deviation DLPM of the intake pipe pressure exceeds the positive predetermined value and it is determined that the vehicle is accelerating, the routine proceeds to step 104 where O
₂ sensor output OX and a reference level (e.g., 0.45 V) and the O ₂ sensor output OX by comparing the determines whether shows Ritsuchi state from the logical air-fuel ratio. When it is determined that the O ₂ sensor output OX indicates the air-fuel ratio rich state,
Increments the count value CAC at step 106, O ₂ sensor output OX becomes a reference level or less to the determined as indicating an air-fuel ratio lean state Deikurimento the count value CAC at step 108.

In the next steps 110 and 114, it is determined whether or not the count value CA has become a value outside the first predetermined range (50 to -50), so that the air-fuel ratio shows a richer tendency than the logical air-fuel ratio. , To determine whether it shows a lean tendency.
That is, when it is determined in step 110 that the count value CAC exceeds the upper limit value (50) of the first predetermined range, that is, when it is determined that the air-fuel ratio indicates a tendency to rich, the BU− is determined in step 112. After decreasing the acceleration increase coefficient KAC stored in the RAM by a predetermined value (for example, 0.1), the count value CAC is set to 0 in step 118. The initial value of the acceleration increase coefficient KAC is set to 1.0 and the BU-RA
It is stored in M. In step 114, it is determined whether or not the count value CAC is less than the lower limit value (-50) of the first predetermined range. If it is determined that the count value CAC is less than the lower limit value of the first predetermined range, the air-fuel ratio is determined. Is determined to be leaner than the logical air-fuel ratio, indicating that the air-fuel ratio is lean, and in step 116, the acceleration increase coefficient KAC stored in the BU-RAM is increased by a predetermined value (for example, 0.1). In a subsequent step 118, the count value CAC is set to 0. When the count value CAC is within the first predetermined range, the routine proceeds to the routine of FIG. 8 without correcting the acceleration increase coefficient KAC.

When it is determined in step 103 that the intake pipe pressure deviation DLPM is equal to or less than the positive predetermined value, in step 120, the intake pipe pressure deviation DLPM is set to a negative predetermined value (for example, −2 mmH).
g) It is determined whether or not the vehicle is decelerating by determining whether or not the speed is lower. When it is determined that the intake pipe pressure deviation DLPM is equal to or greater than the negative predetermined value, it is determined that the engine is in a steady operation state, and the routine proceeds to the routine of FIG. 8, and when it is determined that the intake pipe pressure deviation DLPM is less than the negative predetermined value, it is decelerated. The state is determined to be advancing to step 122. In step 122, either by comparing the determined level as described in O ₂ sensor output OX and the O ₂ sensor output indicates a Ritsuchi state from logical air-fuel ratio, it is determined whether shows a lean state. O ₂ increments the count value CDC at step 124 when the sensor output is determined to indicate an air-fuel ratio Ritsuchi state, in step 126 when the O ₂ sensor output OX is determined to indicate an air-fuel ratio lean state The count value CDC is decremented.

In the next steps 128 and 132, the count value CD
By judging whether or not C is outside a second predetermined range (for example, 50 to -50), the air-fuel ratio deviates toward the rich side from the logical air-fuel ratio to indicate an air-fuel ratio rich tendency, or It is determined whether the air-fuel ratio is leaner than the logical air-fuel ratio and the air-fuel ratio shows a lean tendency. That is, at step 128, it is determined whether the count value CAC exceeds the upper limit value (50) of the second predetermined range to determine whether or not the air-fuel ratio shows a tendency to rich. Step 13 when it is judged that there is a tendency
At 0, the deceleration reduction coefficient KDC stored in the BU-RAM is increased by a predetermined value (for example, 0.1), and then at step 136, the count value CDC is set to 0. The initial value of the deceleration reduction coefficient KDC is set to 1.0 and stored in the BU-RAM. In step 132, it is determined whether or not the air-fuel ratio shows a lean tendency by determining whether or not the count value CDC is less than the lower limit value (-50) of the second predetermined range. Step 13
In step 4, the deceleration reduction coefficient KDC stored in the BU-RAM is reduced by a predetermined value (for example, 0.1), and then the count value CDC is set to 0 in step 136. On the other hand, when it is determined in steps 128 and 132 that the count value CDC is within the second predetermined range, the deceleration reduction coefficient KDC
Proceeds to the routine of FIG. 8 without correcting.

FIG. 6 shows the change in the output of the O ₂ sensor, the change in the count value CAC, the change in the CDC, the change in the acceleration increase coefficient KAC, and the change in the deceleration decrease coefficient KDC together with the change in the vehicle speed and the intake pipe pressure PM when controlled as described above. Show.

FIG. 8 shows a routine for calculating the fuel injection time TAU. In step 200, the engine speed NE, the intake pipe pressure PM and the engine coolant temperature THW are taken, and in step 202, the engine speed NE and the intake pipe pressure PM are obtained. The basic fuel injection time TP is calculated based on Next step
At 204, Fig. 9 and 10 increase or decrease the amount of time corresponding to the engine rotational speed NE from a map shown in FIG f ₁ and the engine coolant temperature TH
Calculates a decrease amount time f ₂ in accordance with W, the following by adding the increment or decrement time f _1, f ₂ at step 206 (1)
As shown in the equation, engine speed NE and engine coolant temperature
An increase / decrease amount time f (NE, THW) corresponding to THW is calculated.

f (NE, THW) = f 1 + f 2 ... (1) using the following step 208 in FIG. 1 in step 102 the calculated intake pipe pressure deviation DLPM the increment or decrement time f (NE, THW) The transient basic fuel injection time TPAEW is calculated according to the following equation (2).

TPAEW = DLPM · f (NE, THW) (2) Here, the transient basic fuel injection time TPAEW becomes positive when accelerating because DLPM> 0 and the transient basic fuel injection time when DLPM <0 when decelerating. Time TPAEW becomes negative.

In step 210, it is determined whether the engine cooling water temperature THW is equal to or lower than a second predetermined temperature (for example, 10 ° C.) to determine whether the engine is at a low temperature. When it is determined that the engine is at a low temperature, the value of K is set to 1 at step 214 in order to prevent the correction by the acceleration increase coefficient and the deceleration decrease coefficient learned as described above. On the other hand, when the engine cooling water temperature THW exceeds the second predetermined temperature, step 212
In step 216, it is determined whether the deviation DLPM of the intake pipe pressure is positive or not to determine whether the vehicle is accelerating or decelerating.If it is determined that the vehicle is accelerating, the acceleration increase coefficient KAC stored in the BU-RAM is determined in step 216. After reading and setting K, the process proceeds to step 220. On the other hand, when it is determined in step 212 that the vehicle is decelerating, in step 218, the deceleration reduction coefficient KDC stored in the BU-RAM is read and set to K, and the process proceeds to step 220.

In step 220, the basic fuel injection time TP, the K value set as described above, the transient basic fuel injection time TPAEW,
Using the air-fuel ratio feedback correction coefficient FAF calculated in the routine of FIG. 7 and the correction coefficient F determined by the intake air temperature, engine cooling water temperature, etc., the fuel injection time TAU
Is calculated.

TAU = (TP + K · TPAEW) · FAF · F (3) Then, it is determined in a routine (not shown) whether or not the fuel injection timing is reached, and when it is determined that the fuel injection timing, the time corresponding to the fuel injection time TAU is driven. The synchronous fuel injection synchronized with the crank angle is executed by setting the down counter of the circuit 94 and opening the fuel injection valve until the value of the down counter becomes O. Where the cooling water temperature TH
During acceleration in the region where W exceeds the second predetermined temperature, the transient basic fuel injection time TPAEW takes a positive value, so that K · TPAEW
Of fuel is increased with respect to the basic fuel injection time TP, and during the same deceleration, the transient basic injection fuel time TPAEW takes a negative value. Weight loss. During normal operation, the value of K is set to O, the basic fuel injection time TP, the air-fuel ratio feedback correction coefficient
The fuel injection amount is controlled according to the FAF and the correction coefficient F.

Transient basic fuel injection time when controlled as described above
TPAEW, acceleration increase value KAC / TPAEW, deceleration decrease value KDC / TPAE
W, basic fuel injection time TP, fuel injection time TAU, and fuel injection time after learning are shown in FIGS. 11 (2) and (3). The eleventh
FIG. 1A shows a change in the intake pipe pressure.

Next, a second embodiment of the present invention will be described. This embodiment is obtained so as to determine the acceleration state and deceleration state on the basis of the transient basic fuel injection time TPAEW _i. Therefore, portions corresponding to those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

In step 230, the transient basic fuel injection time TPAEW _i is a positive predetermined amount (e.g., 100 .mu.sec) determines whether beyond. When it is determined that the transient basic fuel injection time TPAEW _i exceeds the positive predetermined value, it is determined that the vehicle is accelerating, and the routine proceeds to step 104, where it is determined that the transient basic fuel injection time TPAEW _i is less than the positive predetermined value. transient basic fuel injection time TPAEW _i is a predetermined negative value (e.g., -100msc) determines whether during deceleration by determining whether less at step 236 when the. When the transient basic fuel injection time TPAEW _i is determined to be less than the negative predetermined value, it is determined that the vehicle is decelerating, and the routine proceeds to step 122. When the transient basic fuel injection time TPAEW _i is determined to be equal to or longer than the negative predetermined value, steady operation is performed. The state is determined and the routine proceeds to the routine of FIG. Step 232 and Step 2
34 is for processing the same as in steps 110 and 114 in FIG. 1. In step 232, it is determined whether or not the absolute value of the count value CAC is equal to or more than a predetermined value (for example, 50). It is determined whether or not the air-fuel ratio deviates from the logical air-fuel ratio, and when it is determined that the air-fuel ratio deviates from the logical air-fuel ratio, it is determined in step 234 whether the count value CAC is positive. It is determined whether the air-fuel ratio deviates toward the rich side or lean side from the logical air-fuel ratio. When it is determined that the air-fuel ratio is deviated to the lean side, the acceleration increase coefficient KAC is corrected in step 116, and when it is determined that the air-fuel ratio is deviated to the rich side, the acceleration increase coefficient is determined in step 112. Correct KAC. Also, steps 238 and 240 are the same as steps 128 and 130 in FIG.

Note that the count value CAC,
Acceleration increase coefficient KAC, transient basic fuel injection time TPAEW, the change of the O ₂ sensor output OX with changes in the intake pipe pressure PM and the vehicle speed shown in Figure 13.

FIG. 14 shows a routine for calculating the fuel injection time TAU of this embodiment.
At step 252, the basic fuel injection time TP _NEW at the present time is calculated. At the following step 254, 360 ° C from the current basic fuel injection time TP _NEW
A deviation ΔTP of the basic fuel injection time is calculated by subtracting the basic fuel injection time TP _OLD before A. And step
At 256, deviation ΔTP and previous transient basic fuel injection time T
Using the value obtained by attenuating PAEW _i-1 with the damping coefficient C (0 <C <1), the transient basic fuel injection time TPAE according to the following equation:
To calculate the W _i.

TPAEW _i ← ΔTP + TPAEW _i−1 · C (4) In step 258, it is determined whether the engine cooling water temperature THW is equal to or lower than a second predetermined temperature (for example, 10 ° C.) to determine whether the engine is at a low temperature. . When it is determined that the engine is at a low temperature, the value of K is set to 1 at step 260 in order to prevent the correction based on the acceleration increase coefficient and the deceleration decrease coefficient learned as described above. On the other hand, the engine cooling water temperature T
HW is at beyond the constant temperature second place, it is determined whether or not the acceleration by transient basic fuel injection time TPAEW _i determines whether positive or not in step 262, the acceleration in step 264 when during acceleration After setting the value of the increase coefficient KAC to K, the process proceeds to step 268. If it is determined in step 262 that the vehicle is decelerating, the value of the deceleration reduction coefficient KDC is set to K in step 266.
Set to. In step 268, the basic fuel injection time is calculated according to the following equation.

TAU ← (TP _NEW + K · TPAEW _i ) · FAF · F (5) Then, in a fuel injection amount control routine (not shown), it is determined whether or not the injection timing is reached. The fuel injection is executed by opening the fuel injection valve for a corresponding time.

FIG. 15 shows changes in the basic fuel injection time TPAEW, changes in the basic fuel injection time TP, and changes in the fuel injection time TAU when the fuel injection amount is controlled as described above, together with changes in the intake pipe pressure.

The fuel injection time calculation routine shown in FIG. 8 can be used in the second embodiment, and the fuel injection time calculation routine shown in FIG. 14 can be used in the first embodiment.

Next, a third embodiment of the present invention will be described. A comparison between the required correction amount (learning value) at the time of transition between the new internal combustion engine and the internal combustion engine on which the deposit has adhered is as shown in FIG. 18 (1), and the difference increases as the engine temperature increases. Also,
The required correction amount (learning value) of the deposit-attached internal combustion engine when the required correction amount of the new internal combustion engine is 1.0 is shown in FIG. 18 (2).
And increases as the temperature increases. For this reason, in this embodiment, the fuel injection amount is controlled by correcting the acceleration increase coefficient KAC and the deceleration decrease coefficient KDC according to the engine temperature.

FIG. 16 shows a fuel injection time calculation routine of this embodiment. In FIG. 16, portions corresponding to those in FIG. 8 are denoted by the same reference numerals, and description thereof is omitted. Step 300
Then, a correction coefficient KTHW corresponding to the current cooling water temperature THW is calculated from the map shown in FIGS. 17 (1) and (2). The map shown in FIG. 17 (1) is set so that the correction coefficient KTHW changes continuously according to the water temperature THW. The map shown in FIG. 17 (2) has the correction coefficient KTHW changed stepwise. It is determined and any map may be used. Step 30
In step 2, whether acceleration or deceleration is determined on the basis of the deviation DLPM of the intake pipe pressure, the fuel injection time TAU is determined based on the following equation (6) during acceleration and based on the following equation (7) during deceleration.
Is calculated.

TAU = {TP + [1.0+ (KAC-1.0) ・ KTHW] ・ TPAEW} ・ F
AF ・ K… (6) TAU = {TP + [1.0+ (KDC−1.0) ・ KTHW] ・ TPAEW} ・ F
AF ・ K… (7) In the above map, the correction coefficient KTHW is set to 1.0 when the water temperature THW is 70 ° C or higher, so the acceleration increase coefficient KAC and the deceleration decrease coefficient KDC are directly used for the fuel injection time when the cooling water temperature is 70 ° C or higher. Reflected in the calculation. In this embodiment, learning is performed as in the first embodiment or the second embodiment.

According to the present embodiment, KAC, KD according to the engine cooling water temperature THW.
Since the amount of reflection of C on the fuel injection time is determined, fuel more suitable for the engine can be injected.

In the above description, an example in which the present invention is applied to an engine that calculates the basic fuel injection time based on the intake pipe pressure and the engine rotation speed has been described. However, an airflow meter that detects the amount of intake air is provided, and the intake air per engine revolution is provided. The present invention can also be applied to an engine that calculates the basic fuel injection time from the amount. Further, the count value at the time was described O ₂ sensor output Ritsuchi For an example of calculating the time of the deviation by Deikurimento the count value counted value when incremented vital O ₂ sensor output lean when the O ₂ sensor output Ritsuchi in the above count value when Deikurimento vital O ₂ sensor output lean may be determined increment to deviation. The count value and the O ₂ sensor output is lean when the O ₂ sensor output is incremented another count value and when showing the lean and when showing the Ritsuchi O ₂ sensor output indicates a Ritsuchi The deviation from the count value at the time shown may be calculated to calculate the above-mentioned time deviation, or the ratio of these times may be used as the deviation. Further, in the above, an example has been described in which the deviation is obtained by counting every predetermined crank angle (360 ° CA). However, the deviation may be obtained by counting every predetermined time. In the above description, the engine temperature is represented by the engine cooling water temperature, but may be represented by the engine oil temperature or the like.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a routine for updating an acceleration increasing coefficient and a deceleration decreasing coefficient in the first embodiment of the present invention;
FIG. 2 is a diagram showing a change between a conventional feedback correction coefficient and an air-fuel ratio, FIG. 3 is a diagram showing a conventional change frequency of an air-fuel ratio, and FIG. 4 is a fuel injection amount learning method to which the present invention can be applied. FIG. 5 is a block diagram showing details of the microcomputer shown in FIG. 4, and FIG. 6 is a diagram showing changes in the acceleration increasing coefficient and the deceleration decreasing coefficient in the first embodiment. FIG. 7 is a flowchart showing a routine for calculating the air-fuel ratio feedback correction coefficient, and FIG.
FIG. 9 is a flowchart showing a routine for calculating the fuel injection time. FIGS. 9 and 10 are diagrams showing an increase / decrease amount time according to the engine rotation speed and an increase / decrease amount time according to the engine cooling water temperature, respectively. Is a diagram showing changes in the basic fuel injection time during transient and the fuel injection time in the first embodiment,
FIG. 12 is a flowchart showing a routine for correcting the acceleration increasing coefficient and the deceleration decreasing coefficient in the second embodiment of the present invention.
FIG. 13 is a diagram showing changes in the acceleration increase coefficient and the basic fuel injection time in the second embodiment, FIG. 14 is a flowchart showing a routine for calculating the fuel injection time in the second embodiment, and FIG. FIG. 16 is a diagram showing changes in the transient basic fuel injection time and the fuel injection time in the second embodiment, FIG. 16 is a flowchart showing a fuel injection time calculation routine according to the third embodiment of the present invention, and FIG. (1) and (2) are diagrams showing the map of the correction coefficient KTHW, and FIGS. 18 (1) and (2) are diagrams showing the required correction amounts of the deposit-attached internal combustion engine and the new internal combustion engine in comparison. is there. 6 ...... pressure sensor, 8 ...... Surotsutoru valve, 24 ...... fuel injection valve, 30 ...... O ₂ sensor, 44 ...... microcomputer.

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-59-203829 (JP, A) JP-A-58-13131 (JP, A) JP-A-60-204937 (JP, A) JP-A 61-203 294149 (JP, A) JP-A-64-29653 (JP, A) JP 7-92011 (JP, B2)

Claims (1)

(57) [Claims] An acceleration / deceleration state determination means for determining an acceleration / deceleration state; an oxygen concentration sensor for detecting a residual oxygen velocity in exhaust gas; and an oxygen concentration sensor when the output of the oxygen concentration sensor indicates a state richer than a target air-fuel ratio. Deviation calculating means for calculating a difference between the time and the time when the output of the oxygen concentration sensor indicates a lean state from the target air-fuel ratio; temperature detecting means for detecting an engine temperature; When the deviation becomes a value outside the first treatment range during acceleration exceeding the range, the acceleration increase coefficient is learned so that the deviation becomes a value within the first predetermined range, and the engine temperature is reduced to the first range. Learning means for learning a deceleration reduction coefficient such that the deviation falls within the second predetermined range when the deviation becomes a value outside the second predetermined range during deceleration exceeding a predetermined temperature; and Predetermined from first predetermined temperature During acceleration exceeding the second predetermined temperature, which is lower than the second predetermined temperature, an amount of fuel determined according to the acceleration increase coefficient is increased and injected, and at the same time, during deceleration when the engine temperature exceeds the second predetermined temperature, it is determined according to the deceleration reduction coefficient. A fuel injection amount learning control device for an internal combustion engine, comprising: fuel injection means for injecting a reduced amount of fuel.