JPH0476242A - Fuel injection quantity controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To secure proper startability and operatability by compensating a basic injection quantity by means of an air-fuel ratio learning value at the starting time, and after starting an engine and controlling the engine with an injection quantity obtained through varying the basic injection quantity stepwise at the starting time in the case when the learning value is not stored. CONSTITUTION:Deviation of an air-fuel ratio from a theoretical air-fuel ratio is detected by an air-fuel ratio deviation detection means A, and a learning value which corrects the deviation of the air-fuel ratio is calculated and stored by an air-fuel ratio learning means B. There are provided a learning value confirmation means C which discriminates whether the learning value is stored or not, and a starting finish detection means D which detects the end of starting an engine. The basic injection quantity is varied stepwise by a variation means E at the starting time when the learning value is not stored, and the stepwise variation of the basic injection quantity is stopped by a stopping means F at the time of finishing starting. On the other hand, at the starting time when the learning compensation value is stored, the basic fuel injection quantity is compensated by the learning compensation value so that the air-fuel ratio becomes the air-fuel ratio by a learning compensation means G at the previous time of stopping the engine so as to control the fuel injection quantity by a control means H.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fuel injection control device that controls injection of fuel into an internal combustion engine, and in particular controls the amount of fuel injection at the time of starting to an injection amount that enables a suitable start. The present invention relates to a fuel injection amount control device for an internal combustion engine.

[Prior Art] Conventionally, when starting an engine, fuel is supplied to the engine according to a pre-programmed basic fuel injection amount at starting, and whether or not this basic fuel injection amount at starting is a fuel injection amount that allows the engine to be started is determined. If it is determined that starting is not possible, the basic injection amount at startup is increased at regular intervals (
For example, Japanese Patent Application Laid-Open No. 58-133437).

[Problem to be solved by the invention]

However, when the above is used in an internal combustion engine compatible with F, F, V, (flexible fuel vehicles), the stoichiometric air-fuel ratio of alcohol is about half that of gasoline, so when using gasoline, the fuel is It is necessary to inject approximately twice as much.

Therefore, when starting the engine, the basic fuel injection amount must be increased and corrected at regular intervals, resulting in poor startability.

An object of the present invention is to improve the startability of an FFV compatible internal combustion engine.

[Means to solve the problem]

As a means for solving the above problems, the present invention includes a state detection means for detecting the state of the engine as shown in FIG. 1, a calculation means for calculating a basic injection amount based on the state detection means, and an air-fuel mixture supplied to the engine. an air-fuel ratio detecting means for detecting an air-fuel ratio of the air-fuel ratio; an air-fuel ratio deviation detecting means for detecting a deviation between the air-fuel ratio and the stoichiometric air-fuel ratio; and a learning value for correcting the air-fuel ratio deviation detected by the air-fuel ratio deviation detecting means. air-fuel ratio learning means for determining and storing the learned value; learned value checking means for determining whether the learned value is stored; starting completion detecting means for detecting completion of starting of the engine; basic injection amount changing means for changing the basic injection amount in stages when starting is not completed; stopping means for stopping the stepwise change in the basic injection amount when starting is completed; and according to the change when starting is completed; post-start injection amount calculating means for calculating an injection amount after starting by correcting the basic injection amount; learning correction means for correcting the fuel ratio using the learning correction value, the basic injection amount changing means, the injection amount calculation means after startup, and the learning correction means according to an output from the fuel ratio. A fuel injection amount control device for an internal combustion engine is proposed, which is characterized by comprising a control means for controlling the injection amount.

[Effect]

As a result, the basic injection amount determined by the engine condition is corrected using the air-fuel ratio learning value so that the air-fuel ratio becomes the air-fuel ratio at the time of the previous engine stop during and after starting.

Further, if the air-fuel ratio learning value is not stored, the basic injection amount is changed in stages at the time of starting until the starting is completed. When the start is completed, the basic injection amount is corrected according to the amount of change in the basic injection amount until the start is completed. Fuel injection is controlled based on the basic injection amount corrected as described above.

〔Effect of the invention〕

According to the present invention, F, F, V compatible internal combustion engines can be started even if alcohol is used as fuel.

After starting, by correcting the basic injection amount using the air-fuel ratio learning value, the engine can be controlled with the optimum injection amount, resulting in good startability and drivability. In addition, even if the learned value is not memorized due to panteri clearing, etc., the injection amount obtained by changing the basic injection amount in stages will be used at the time of starting, and after starting, the amount will be adjusted according to the amount of change in the basic injection amount at the completion of starting. The engine is controlled by the injection amount obtained by correcting the basic injection amount, which has the excellent effect of providing good startability and drivability.

(Example) An example of the present invention will be described based on the drawings. Fig. 2 is a schematic diagram showing the overall configuration of an engine and a control circuit in which the present invention is implemented.

1 is the engine, and the combustion air is passed through the air filter 2゜intake'
W3. Inhale via throttle valve 6.

Reference numeral 4 denotes an air flow meter that detects the amount of air taken into the engine 1. Reference numeral 5 denotes an intake air temperature sensor that detects the temperature of intake air. 7 is an electromagnetic fuel injection valve that supplies fuel to engine 1.
is supplied to. Exhaust gas after combustion is passed through the exhaust pipe 8. It passes through a three-way catalyst 9 and is released into the atmosphere. 10 is an air-fuel ratio sensor that detects the air-fuel ratio from exhaust gas. The engine 1 is equipped with a thermistor type water temperature sensor 11 that detects the coolant temperature and outputs an analog voltage according to the coolant temperature.The rotational speed sensor 12 detects the rotational speed of the crankshaft of the engine 1, and Outputs a frequency pulse signal corresponding to the 13 is a control circuit and an air flow meter 4. The fuel injection lid is calculated based on the detection signals of the intake air temperature sensor 51, the rotational speed sensor 12, the cooling water temperature sensor 11, and the air-fuel ratio sensor 10, and an injection signal corresponding to this calculation is output to the fuel injection valve 7. Adjust the injection amount. 14 is a battery connected to the control circuit 13 via the ignition switch 15;
supplies power to.

The control circuit 13 also includes a backup RAM 13a to which power is supplied from the battery 14 regardless of whether the ignition switch 15 is on or off. This R.A.
M13a stores learning correction coefficients to be described later.

FIG. 3 is a flowchart showing the operation of the control circuit 13, and this routine is executed every revolution of the engine.

When the ignition switch 15 is turned on, in step 101, a mirror check is performed to determine whether or not a learning correction coefficient KG, which will be described later, is abnormal. If it is determined that the learning correction coefficient KG is abnormal, the process proceeds to step 102, where the learning correction coefficient is initialized to 1.

This learning correction coefficient KG is calculated from the battery 14 to the RAM 13.
If the power supply to a is cut off, it will be initialized. Next, in step 103, the battery clear flag BCI'', which becomes 0 when the power supply from the battery 14 to the RAM 13a is cut off, is set to O.Then, the process proceeds to step 1.04, where it is determined whether or not the engine 1 is in the starting state. Also, if it is determined in step 101 that the learning correction coefficient KG is normal, the process proceeds to step 104 and it is determined whether or not the engine is in the starting state.

If it is determined that it is in the starting state, the process proceeds to step 105 and the BCF
It is determined whether or not is O. When BCF=0, that is, when starting after the power supply to the battery 14 has been cut off and the learning correction coefficient KG has been initialized, or when starting when the learning correction coefficient KG is abnormal, the process proceeds to step 106, and the fuel Spray lid T A 1. J is calculated using the following formula.

TAU=TAUSTAxFTHAx (1+Kxt) Here, T A and US T A are the basic injection amounts at startup, FTHA is the intake temperature correction coefficient, K is a constant, and L is the elapsed time from the start of startup.

Calculate the fuel injection amount T A IJ by multiplying the basic injection amount TAUSTA at startup by the intake air temperature correction value, and then multiplying it stepwise according to t (1+ -t) during the reddening period from the start of startup. There is. As a result, TAU increases stepwise until the engine is completely started. Next, in step 107, the fuel injection amount correction coefficient FBC after the start is completed when the battery is cleared (when the learning value is initialized) is calculated using the following formula.

FBC= (1 + KXt) Fourth
5 shows the relationship between the coefficients A and B that determine the constant KT, the elapsed time after startup, and the cooling water temperature at startup.

The coefficient A gradually becomes smaller as the starting elapsed time increases, and the coefficient B takes a larger value as the amount of cooling water at the time of starting is higher. The coefficients A and B and the constant KT have the following relationship.

KT=1 +A+B As described above, the post-start fuel injection amount correction coefficient FBC is calculated by multiplying (1+Kxl) by KT determined by the elapsed time after start and the coolant temperature at start.

When the BCF is not 0 in step 105, that is, when the learning correction coefficient KG has not been initialized, the process proceeds to step 108 and calculates the fuel injection amount TAU using the following formula.

TAU=T, AUSTAxFTHAxKGTAUSTA
is the basic injection amount at startup, FTHA is the intake temperature correction coefficient, KG
is the learning correction coefficient. In other words, if the correct learning correction coefficient has not been initialized, the injection amount is calculated by reflecting the learning correction coefficient.

The above are the steps for calculating the fuel injection amount TAU at the time of starting.

Steps 109 to 117 are steps for calculating the fuel injection amount after completion of starting.

If it is determined in step 104 that the starting has been completed, that is, if it is determined that the engine speed is equal to or higher than the predetermined rotation speed, the process proceeds to step 109, where it is determined whether or not the feedback of the fuel injection amount by the 0□ sensor 10 can be corrected. Discern. 0□
If it is determined that feedback correction by the sensor 10 is impossible, that is, the temperature of the 02 sensor is too low to accurately detect the stoichiometric air-fuel ratio, the process proceeds to step 110, where it is determined whether the battery clear flag BCF is O or not. When the learning correction coefficient KG is 0, that is, when the learning correction coefficient KG has been initialized, the fuel injection amount TAU is calculated from the following formula in step 111.

TAU= TP
FALL is a correction coefficient determined by the injection amount at the completion of starting calculated, the elapsed time until the start of starting, and the cooling water temperature, and FALL is a correction coefficient related to the engine temperature (cooling water temperature) and transient state.

As mentioned above, the basic fuel injection amount after starting is FTHA, FB.
The fuel injection amount TAU is calculated by correcting it using C and FALL.

If BCF=O is not established in step 110, that is, if the learning correction coefficient remains uninitialized, the fuel injection amount TAU is calculated in step 112 using the following formula.

TAU=TPXFTHAXKGXFALLTP is the basic fuel injection amount after completion of starting, FTI (A is the intake air temperature correction value, F
ALL is a correction coefficient related to engine temperature, and KG is a learning correction coefficient.

As described above, the fuel injection amount TAU is calculated using the correction coefficient, FTHA,
The fuel injection amount is calculated by correcting KG, FA, and LL.

0 in step 109. If it is determined that air-fuel ratio feedback correction using the sensor is possible, a feedback correction coefficient FAF is calculated in step 113. This step 1
The calculation of the correction coefficient FAF in step 13 will be explained in more detail based on the flowchart shown in FIG.

First, in step 201, the 02 sensor signal is input. Next, the 0□ sensor signal is subjected to delay processing using the steering knob 202 to reduce noise. Then, in step 203, it is determined whether the delay-processed value is rich or lean. If it is determined to be lean, the process proceeds to step 204, where it is determined whether or not the value subjected to the previous delay processing is rich. If it is determined to be lean, that is, if it is determined to be lean both this time and the previous time, a predetermined value KI is added to the previous correction coefficient FAF, and the result is set as the current feedback correction coefficient. When the previous delay processing value is determined to be rich in step 204, that is, when the delay processing value has switched from rich to lean, the skip value R3 is added to the previous correction coefficient FAF, and the result is used as the current feedback correction coefficient. shall be. By the way, the relationship Kl<R3 holds true between the predetermined value Kl and the skip value R3.

If the current delay processing value is determined to be rich in step 203, the process proceeds to step 207, where it is determined whether the current delay processing value is lean. When judged as rich,
That is, when it is determined that the previous time and the present time are the same, in step 208, a predetermined number of ■ is subtracted from the previous correction value FAF, and the result is set as the current feedback correction value. In addition, when lean is determined in step 207, that is, when the delay processing value has switched from lean to rich, the value obtained by subtracting the skip value R3 from the previous correction coefficient FAF is used as the current feedback in step 209. It is used as a correction factor.

The air-fuel ratio feedback correction value FAF is calculated based on the signal from the 02 sensor 10 in the following manner.

Next, returning to FIG. 3, the process proceeds to step 114, where it is determined whether a predetermined number of feedback correction coefficients FAF have been input. If not, steps 115 and 116 are skipped. When it is determined that a predetermined number of feedback correction coefficients FAF have been input, a learning correction coefficient KG is calculated and stored in step 115. Now, based on Figure 7, step 1
The operation when calculating the learning correction coefficient KG of No. 15 will be explained in more detail.

First, in step 301, an average value F A F A V of a predetermined number of feedback correction coefficients FAF is calculated.

Next, the average value FAF calculated in step 3021
AV is stored as a learning correction coefficient KG. The learning correction coefficient is calculated and stored as described above.

After calculating and storing the learning correction coefficient, the process returns to FIG. 3 and in step 116, the BCF is set to 1 and the process proceeds to step 117. Also, when it is determined in step 114 that there is no input of a predetermined number of feedback correction coefficients FAF, step 11
Proceed to step 7.

In step 117, the fuel injection amount TAU is calculated using the following formula.

TAU=TPXFTHAXFAFXFALL where, T
P is the basic fuel injection amount, FTHA is the intake temperature correction coefficient, FA
F is an air-fuel ratio feedback correction coefficient, and FALL is a correction coefficient related to engine temperature. As shown in -1 above, the basic fuel injection amount is corrected using the correction coefficients FTHA, FAF, and FALL to calculate the fuel injection @TAU.

The operation of fuel injection 1TAU and rotational speed at the time of starting when the control device described above is actually used will be explained based on FIGS. 8 and 9. Figure 8 shows what happens when the learning correction coefficient KG is initialized, and Figure 9 shows how the basic fuel injection amount is corrected using the learning correction coefficient KG, both of which use alcohol as the fuel. . The stoichiometric air-fuel ratio of alcohol is about 7, which is about half of the stoichiometric air-fuel ratio of gasoline, so it is necessary to inject about twice as much fuel as when using gasoline.

In Fig. 8, at the time of starting, the basic injection amount TAUST at starting when using gasoline is determined according to the elapsed time from the start of starting.
From A, the rotational speed increases stepwise until it exceeds the starting completion determination level Neo. Then, when the rotation speed exceeds the level Neo, the injection amount TAU is changed to the gasoline injection amount TAU to correct the basic injection amount TP after starting when using gasoline based on the amount of change in the injection amount Ts at the time of completion of starting from the basic injection amount TAUSTA at the time of starting. It will be about twice as much. Then, after a predetermined period of time, 02
Air-fuel ratio control is started by the sensor, and the injection amount TAU is controlled to reach the stoichiometric air-fuel ratio.

When the learning correction coefficient KG is stored as shown in Fig. 9, the basic injection amount TALI at starting when using gasoline is used.
STA is corrected by a learning correction coefficient KG that makes the air-fuel ratio at the time of the previous engine stop, and an injection amount TAtJ approximately twice that of TAUSTA is injected. When the rotational speed exceeds the starting completion determination level Neo, the basic injection amount TP after starting is corrected by the learning correction coefficient KG, and an injection amount approximately twice the TP is injected.

Then, after a predetermined period of time has elapsed, the air-fuel ratio feed-hack control is started by the 02 sensor, and the injection amount T A tJ is controlled to become the stoichiometric air-fuel ratio.

Another embodiment will be described based on FIG. 10. The difference from the embodiment shown in FIG. 3 is the processing section at the time of startup and after startup when the battery clear flag BCF is 00, that is, when the learning correction coefficient KG is initialized.

In the embodiment shown in FIG. 10, at the time of starting when the learning correction coefficient KG is in the initialized state, in step 406, the product of the starting start elapsed time t and a constant is added to the learning correction coefficient KG, and the result is used as a new learning correction coefficient. The learning correction coefficient is changed in stages according to the elapsed time after starting the engine. Then, in step 407, the learning correction coefficient KG is stored, and in step 4
In step 08, the learning correction coefficient KGO after the completion of starting is calculated by multiplying the learning correction KG by the correction coefficient KT determined by the elapsed time after starting and the cooling water temperature at the time of starting.

Then, in step 409, the basic injection amount at startup is corrected using a learning correction coefficient KG that changes in steps according to the elapsed time after the start of startup, thereby changing the injection amount TAU in steps.

When starting is completed at BCF-0, steps 412, 413,
Proceeding to step 414, the injection amount TAU is calculated in which the post-start learning correction coefficient KGO calculated in step 408 is reflected.

Furthermore, in the flowchart shown in FIG. 3, BCF=1 was set after the correction by the 0□ sensor started, but this time, BCF=1 is set in step 413 after starting has started.

The operations in other steps are the same as in the flowchart shown in FIG.

As described above, in steps 406 and 407, by storing the learning correction coefficient KG that changes step by step depending on the elapsed time after starting, the starting fails and the injection amount at restart is changed from the final injection amount at the previous start. will be started.

In the embodiments described above, when starting with the learning correction coefficient KG initialized, the injection amount was changed according to the elapsed time after starting the engine, but it may be changed according to the number of injections.

FIG. 3 is a flowchart showing the operation of the control circuit according to the embodiment of the present invention, FIG. 4 is a relationship diagram showing the relationship between the elapsed time after startup and the correction coefficient, and FIG. 5 is a relationship diagram showing the relationship between the cooling water temperature at startup and the correction coefficient. Figure 6 is a flowchart showing the operation of feedback processing by the 02 sensor, Figure 7 is a flowchart showing the operation of the learning correction coefficient creation process, and Figure 8 is the initialization of the learning correction coefficient. FIG. 9 is a diagram showing the relationship between the rotation speed and injection amount at the time of learning correction, and FIG. 10 is a diagram showing the relationship between the rotation speed and the injection amount at the time of learning correction. 5 is a flowchart showing the operation of the control circuit.

■...Engine, 4...Air flow meter, 5...
Intake temperature sensor, 7...injector, 10...02
sensor.

II...Water temperature sensor, 12...Rotation speed sensor, 1
3...Control circuit.

Claims (1)

[Scope of Claims] Condition detection means for detecting the condition of the engine, calculation means for calculating the basic injection amount based on the condition detection means, and air-fuel ratio for detecting the air-fuel ratio of the air-fuel mixture supplied to the engine. a detection means, an air-fuel ratio deviation detection means for detecting a deviation between the air-fuel ratio and the stoichiometric air-fuel ratio, and an air-fuel ratio learning means for obtaining and storing a learning value for correcting the air-fuel ratio deviation detected by the air-fuel ratio deviation detection means. a learned value confirmation means for determining whether or not the learned value is stored; a start completion detection means for detecting completion of starting of the engine; basic injection amount changing means for changing the amount in steps; stopping means for stopping the stepwise change in the basic injection amount when starting is completed; and correcting the basic injection amount in accordance with the change at the completion of starting. a post-start injection amount calculation means for calculating an injection amount after startup; and the learning correction so that the air-fuel ratio changes from the basic injection amount to the air-fuel ratio at the time of the previous stop of the engine at the time of startup in which the learning correction value is stored. a learning correction means for correcting the fuel injection amount based on the value; a control means for controlling the fuel injection amount according to an output from any one of the basic injection amount changing means, the post-start injection amount calculation means, and the learning correction means; A fuel injection amount control device for an internal combustion engine, comprising: