JPH0612082B2 - Electronically controlled fuel injection device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled fuel injection device for an internal combustion engine, and more particularly to improvement of correction control of a fuel supply amount in an engine transient operation state.

<Prior Art> An electronically controlled fuel injection device for an internal combustion engine has heretofore been as follows (see Japanese Patent Laid-Open No. 59-203828).

That is, the basic fuel injection amount Tp (= K × Q / N; K is a constant) is calculated from the intake air flow rate Q detected by the air flow meter and the engine rotation speed N detected by the crank angle sensor or the like. , Various correction coefficients COEF according to the engine operating condition mainly on the machine seat temperature, an air-fuel ratio feedback correction coefficient LAMBDA for making the actual air-fuel ratio close to the target air-fuel ratio, and a correction amount Ts corresponding to the battery voltage. The final fuel injection amount Ti (= Tp ×) is calculated by correcting the basic fuel injection amount Tp.
COEF × LAMBDA + Ts) is set.

Then, a predetermined amount of fuel is injected and supplied to the engine by outputting an injection pulse signal having a pulse width corresponding to the set fuel injection amount Ti to the electromagnetic fuel injection valve.

By the way, in the transient operation state of the engine, the response delay of the fuel injection control, the detection response delay of the intake air flow rate Q, and
The air-fuel ratio cannot be controlled to a desired value due to a delay in the supply of liquid fuel (hereinafter referred to as wall flow) that flows along the wall surface of the intake passage, and the air-fuel ratio becomes over lean during acceleration and over-rich during deceleration. Therefore, the normal fuel injection amount is increased / decreased during transient operation, and the injection pulse signal for increasing fuel is output during the normal injection pulse signal especially during acceleration. The fuel ratio was controlled to a desired value.

Here, the amount of fuel increase / decrease required by the engine during transient operation is
Since it changes according to the engine load state, the throttle valve opening change rate, the engine temperature, the engine speed, etc. in the steady operation state before the transient operation, the correction amount (correction coefficient) preset according to these parameters can be set. It was set according to each detected value, and was used to correct the increase / decrease of fuel during transient operation (Japanese Patent Application Nos. 61-182011 and 61-2).
58486, etc.).

<Problems to be Solved by the Invention> Here, the correction amount setting of the fuel injection amount based on the engine load is set so as to correspond to the engine load change during transient operation, and It is desirable to set it based on the engine load in a steady operation state, and it decreases in accordance with an increase in the basic fuel injection amount Tp that represents the engine load in advance, as in Japanese Patent Application No. 62-148036 previously filed by the applicant of the present application. The set correction coefficient (correction amount) is set based on the basic fuel injection amount Tp immediately before the transient operation is detected, and the fuel supply amount corresponding to the steady operation is corrected based on this correction coefficient (correction amount). There is something like this.

By the way, to detect the engine transient operating state, the control unit reads the detected value of the throttle valve opening TVO every minute time (for example, 10 ms), and the throttle valve opening change rate ΔTVO and the predetermined value at the minute time are read. Since it is performed by comparing, for example, as shown in FIG.
When the throttle valve opening change rate ΔTVO is smaller than the predetermined value and is shifted to an acceleration state where the throttle valve opening change rate ΔTVO is detected, the steady state before the transient operation is originally assumed. Engine fuel injection amount T
Although it is desired to set the acceleration increase correction amount based on p ₀ (engine load), the correction amount is set with the basic fuel injection amount TP ₁ in the slow acceleration state as the engine load state before the acceleration operation.

Therefore, the load condition larger than the engine load condition at the time of true steady operation is set as the correction amount setting condition, the increase correction amount becomes smaller than the engine required amount, the air-fuel ratio becomes lean during acceleration, and the acceleration response and Exhaust properties sometimes deteriorated. That is, when the air-fuel ratio becomes lean, misfiring occurs, the indicated mean effective pressure falls, and an acceleration shock occurs, and as shown in FIG. 6, the nitrogen oxide NO _x concentration increases as the air-fuel ratio becomes lean. In addition, as shown in FIG. 7, the conversion rate of NO _x by the three-way catalyst decreases and a large amount of NO _x is generated.
Will be discharged.

If the throttle valve is slowly closed at the beginning of deceleration as in the above acceleration, the engine load state in the steady operation state before deceleration cannot be specified, and the reduction correction amount based on the smaller engine load state in the actual steady operation. Is set,
The correction amount becomes smaller than the deceleration reduction correction amount required by the engine, and the air-fuel ratio becomes rich.

The present invention has been made in view of the above problems, and it is possible to more accurately identify the engine load state in the steady operation state before the transient operation, and to correct the fuel supply amount during the transient operation that meets the engine request. The purpose is to be able to do it.

<Means for Solving Problems> Therefore, in the present invention, as shown in FIG. 1, when the engine operating state detecting means for detecting the operating state of the engine and the detected engine operating state is set to the steady operating state, Fuel supply amount setting means for setting the fuel supply amount required by the engine, throttle valve opening degree detecting means for detecting the opening degree of the throttle valve provided in the engine intake passage, and detection by the throttle valve opening degree detecting means. The engine transient operating state detecting means for detecting the transient operating state of the engine based on the rate of change of the throttle valve opening per predetermined minute time, the engine load detecting means for detecting the load of the engine at every predetermined minute time, An engine load storage means for storing a value of the engine load detected a predetermined number of times before by the engine load detection means, and an engine transient operation state detection by the engine transient operation state detection means. Fuel supply correction amount setting means for setting a correction amount of the fuel supply amount according to the engine load of a plurality of times stored in the means, and the fuel supply amount and the fuel supply correction amount setting set by the fuel injection amount setting means. Fuel supply control means for driving and controlling the fuel supply means based on the correction amount set by the means.

<Operation> According to the electronically controlled fuel injection device having such a configuration, the rate of change of the throttle valve opening detected by the throttle valve opening detection means is detected in a predetermined minute time, and based on this rate of change of the throttle valve opening. Detects transient engine operating conditions. Then, in the first detection of the engine transient operation state, the correction amount of the fuel supply amount is set based on the stored value of the engine load storage means that stores the engine loads detected a plurality of times before by the engine load detection means.

That is, the correction amount of the fuel supply amount during the engine transient operation is not set based on the engine load state immediately before the detection of the transient operation, but is set based on the engine load detected a plurality of times before. Even if there is a slow transient operation state before detecting the transient operation based on the opening change rate, the engine load state during transient operation that is not detected based on the throttle valve opening change rate is a condition for setting the correction amount during transient operation. Is set so that the correction amount can be set substantially corresponding to the engine load state in the steady operation state before the engine transient operation.

<Example> An example of the present invention will be described below with reference to the drawings.

FIG. 2 shows an outline of the system of this embodiment.

A throttle valve opening sensor 4 as a throttle valve opening detecting means for detecting an opening TVO of a throttle valve 2 provided in an intake passage 2 of the internal combustion engine 1, a crank angle sensor for detecting an engine rotation speed N, and the like. Rotational speed sensor 5 and engine 1
An air flow meter 8 for detecting the intake air flow rate Q and a water temperature sensor 9 for detecting the engine cooling water temperature Tw are provided, and respective detection signals from these are input to a control unit 6 incorporating a microcomputer. The control unit 6 sets the fuel injection amount Ti by increasing / decreasing during transient operation of the engine 1 based on these detection signals, and sets an injection pulse signal having a pulse width corresponding to this fuel injection amount Ti as fuel supply means. Output to the electromagnetic fuel injection valve 7.

Here, in the present embodiment, since the basic fuel injection amount Tp set based on the engine rotation speed N and the intake air flow rate Q is used as a representative of the engine load, the rotation speed sensor 5 and the air flow meter 8 are used. And correspond to the engine load detecting means, and the rotation speed sensor 5, the air flow meter 8 and the water temperature sensor 9 correspond to the engine operating state detecting means. Further, in the present embodiment, the control unit 6 also serves as fuel supply amount setting means, engine transient operation state detecting means, engine load storing means, fuel supply correction amount setting means, and fuel supply control means.

Next, the setting control of the fuel injection amount Ti by the control unit 6 will be described based on the flowcharts of FIGS. 3 and 4.

The fuel injection amount setting routine shown in the flowchart of FIG. 3 is executed every predetermined minute time (for example, 10 ms), and in step (S in the figure, the same applies hereinafter) 1, each sensor The detected opening degree TVO of the throttle valve 3, the intake air flow rate Q, the engine rotation speed N, and the cooling water temperature Tw are input.

In step 2, the intake air flow rate Q input in step 1
And the basic engine fuel injection amount Tp (=
K × Q / N; K is a constant) is calculated. The basic fuel injection amount Tp is used to indicate the engine load state as described above.

In step 3, by subtracting the previous input value from the throttle valve opening TVO input in step 1 this time,
The opening change rate ΔTVO of the throttle valve 3 in the routine execution cycle is calculated, and this opening change rate ΔTVO is compared with a predetermined value. If the opening change rate ΔTVO is a predetermined value or more and the throttle valve 3 is a predetermined value or more. If it indicates that the engine is open at a certain rate, it is determined that the engine is in the accelerated operation state, and the routine proceeds to step 4. On the other hand, the opening change rate ΔT of the throttle valve 3
When VO is smaller than the predetermined value and it is determined that the engine 1 is not in the acceleration operation state, the process proceeds to step 12.

When it is determined in step 3 that the engine 1 is in the acceleration operation state and the process proceeds to step 4, it is determined whether or not this acceleration determination is the first time, and when it is determined that the first time, the process proceeds to step 5.

In step 5, the settings are stored in step 17 described later.
The basic fuel injection amount 30Tp set in step 2 in 30 ms (three times before) is set as the basic fuel injection amount MTp for setting the engine load-dependent correction coefficient this time.

That is, in the engine acceleration state, it is desired to set the increase correction amount according to the engine load state in the steady operation state before the acceleration operation, but in the acceleration detection based on the throttle valve opening change rate ΔTVO performed in step 3, the steady state is detected. A slow acceleration state (a state in which the opening change rate ΔTVO is slight) in which the throttle valve 3 is gradually opened so as not to erroneously detect the operation as the acceleration operation is not determined to be the acceleration state. For this reason,
If there is a slow acceleration state in which acceleration is not determined before the acceleration state in step 3 and the basic fuel injection amount Tp (engine load) immediately before acceleration detection is set as the setting reference MTp for acceleration increase correction. The acceleration increase correction is performed based on the engine load state after the start of acceleration, not the engine load state in the steady operation state before acceleration.
Therefore, in this embodiment, the basic fuel injection amount Tp set in step 2 is set three times before the initial acceleration is detected (30 ms before).
Even if there is a slow acceleration state where acceleration is not detected before acceleration is detected, it is closer to the steady operation state rather than the engine load state at the end of the slow acceleration state. Alternatively, the acceleration increase correction is performed based on the engine load state in the true steady operation state.

In step 5, as the basic fuel injection amount MTp for setting the engine load-dependent correction coefficient, the basic fuel injection amount Tp set 30 ms before (three times before) is set, and in the next step 6, the acceleration increase correction is performed. The throttle valve opening TVO _de , which is the timing for gradually decreasing the amount, is obtained by referring to a map that is set in advance according to the engine rotation speed N. The throttle valve opening TVO _de it comes to be opened throttle valve 3 exceeds the opening TVO _de, the increase correction amount is gradually reduced acceleration increase correction amount which is set according to the engine operating condition To return to zero, the opening TVO
Even if the vehicle is accelerated from the opening TVO exceeding _de , the acceleration increase correction is not performed.

In step 7, the acceleration increase / decrease transition opening TVO _de obtained in step 6 is compared with the current throttle valve opening TVO input in step 1, and the current throttle valve opening T
When VO has not reached the opening TVO _de , the routine proceeds to step 8, where the acceleration increase correction coefficient KFUEL2 is set based on each parameter indicating the engine operating state.

The parameters are the cooling water temperature Tw, the engine rotation speed N, the throttle valve opening TVO, the basic fuel injection amount MTp three times before set in step 5, and the throttle valve opening change rate ΔTVO. The correction coefficient corresponding to the parameter is stored in the map in advance (see the graph in FIG. 3), and the acceleration increase correction coefficient KF is calculated by referring to the corresponding correction coefficient from the map based on each detected value and multiplying each other.
Set UEL2.

Here, the engine load before acceleration detection (basic fuel injection amount MT
In the case of the present embodiment, the correction coefficient set according to p) is
It does not correspond to the engine load immediately before the first acceleration detection, but is set based on the engine load state a predetermined time (30 ms before) the first acceleration detection. However, it is possible to set a value that roughly corresponds to the engine load state in the steady operation state before the acceleration operation that goes back further, and increase correction according to the engine load in the steady operation state before the desired engine acceleration operation. The amount can be set and the lean air-fuel ratio can be prevented. Therefore, the generation of acceleration shock can be avoided, and the exhaust property can be kept good.

In the next step 9, the acceleration increase correction coefficient KFUEL2 set based on the engine operating state in step 8 is compared with the acceleration increase correction coefficient KFUEL1 set in the routine (step 21) shown in the flowchart of FIG. .

Since the initial value of the acceleration increase correction coefficient KFUEL1 is zero, KFUEL1 ≦ KF in step 9 in the initial acceleration detection.
If it is determined to be UEL2, the process proceeds to step 10 and step 8
The acceleration increase correction coefficient KFUEL2 set in step 2 is set as the final correction coefficient KFUEL. Then, according to the routine shown in the flowchart of FIG. 4, the acceleration increase correction coefficient KFUEL set at the initial stage of acceleration is corrected in a predetermined ratio in synchronization with the signal Ref output from the rotation speed sensor 5 at every predetermined crank angle. Then, the acceleration increase correction coefficient KFUEL1 is set, and thereafter, every time the rotation speed sensor 5 outputs the signal Ref, the previous final correction coefficient KFUEL is decreased and corrected at a constant rate (β%), and the acceleration increase correction coefficient KFUEL1. Is set.

That is, step 9 is, as described above, the acceleration increase correction coefficient KFUEL2 set according to the engine operating state at that time, and the acceleration increase set by correcting the previous correction coefficient KFUEL to decrease in synchronization with the engine rotation. The larger one of the correction coefficient KFUEL1 is set as the final acceleration increase correction coefficient KFUEL, and the correction coefficient KFUEL1 _or KFUEL2 determined to be the larger one in step 9 is set in step 10 or step 11. It is set as the final acceleration increase correction coefficient KFUEL.

On the other hand, if it is determined in step 3 that the engine 1 is not in the acceleration operation state and the process proceeds to step 12, it is determined whether the engine 1 is in the deceleration operation state based on the throttle valve opening change rate ΔTVO as in the acceleration operation determination. judge.

Here, when it is determined that the engine 1 is not in the decelerating operation state, it indicates that the engine 1 is in the steady operation state, the process proceeds to step 13, the acceleration increase correction coefficient KFUEL2 is set to zero, and the process proceeds to step 9. Here, the acceleration increase correction coefficient set by correcting the previous correction coefficient KFUEL to decrease in synchronization with the engine rotation
If KFUEL1 is not zero yet, step 9
It is determined that KFUEL1> KFUEL2 in
KFUEL1 is set as the final acceleration increase correction coefficient KFUEL. That is, when the acceleration operation state is changed to the steady operation state, the correction coefficient KFUEL set at the end of the acceleration operation state is gradually decreased and corrected in synchronization with the engine rotation. When the throttle valve opening TVO exceeds the acceleration increase / decrease transition opening TVO _de , the acceleration increase correction amount is immediately decreased even during acceleration. When the steady operation is continuously performed, the correction coefficients KFUEL1 and KFUEL2 become zero, and the final acceleration increase correction coefficient KFUEL becomes zero.

When it is determined in step 12 that the engine 1 is in the deceleration operation state, in step 14, the final correction coefficient
By setting KFUEL to zero, the value of the correction coefficient KFUEL1 is immediately set to zero and the acceleration increase correction is stopped.

When the acceleration increase correction coefficient KFUEL is set in this way, various correction coefficients COEF including this KFUEL are set in step 15 according to the following equations.

COEF = KFUEL + where _{KDC + K MR + K AS +} K TW, KDC is decelerating decrease correction, although not described in detail in this embodiment, the acceleration enrichment coefficient engine load condition in the steady operation state before deceleration operation as with KFUEL ( In the case of setting based on the basic fuel injection amount Tp), the basic fuel injection amount Tp set several times before is also used to represent the engine load state in a steady state before deceleration, and is set to a desired value. Allows deceleration and weight reduction.

Further, K _MR is an air-fuel ratio correction coefficient, and the engine speed N
It is stored for each operating state divided by the basic fuel injection amount Tp and the basic fuel injection amount Tp. T _AS
Is a startup and post-starting increase correction coefficient, which increases and corrects the fuel for the purpose of improving engine startability and stable operation after start, and is set according to the cooling water temperature Tw. K
_TW is a water temperature increase correction coefficient, which is used to increase the amount of fuel to be corrected at a low temperature when the fuel atomization property deteriorates.

In step 16, the various correction factors C set in step 15
Using OEF, the fuel injection amount Ti is set according to the following equation.

Ti = Tp × LAMBDA × KLRN × (1 + COEF) + Ts where LAMBDA is an air-fuel ratio feedback correction coefficient, which is based on the oxygen concentration in the exhaust gas detected by the O ₂ sensor provided in the exhaust passage. The air-fuel ratio is detected and the actual air-fuel ratio is set to approach the target air-fuel ratio, and is clamped during transient operation or starting.

KLRN is an air-fuel ratio learning correction coefficient, and learns a deviation from the reference value of the air-fuel ratio feedback correction coefficient LAMBDA to approximate the base air-fuel ratio to the target air-fuel ratio. Ts is for correcting the change in the effective valve opening time of the fuel injection valve 7 due to the change in the battery voltage.

In the next step 17, the basic fuel injection amount Tp set in step 2 this time is set to the previous basic fuel injection amount 10 Tp (10 ms before).
And the basic fuel injection amount of 10 Tp set in the previous step 2 is set as the basic fuel injection amount of 20 Tp two times before (20 ms before), and further set in the step 2 before the previous step 17 in the previous step 17. The value set as the basic fuel injection amount of 20 Tp two times before (20 ms before) is set as the basic fuel injection amount of 30 Tp three times before (30 ms before). Therefore, the value set as the basic fuel injection amount Tp three times before in step 5 is
This is the value set as the basic fuel injection amount of 30 Tp in the previous step 17.

In this way, each time this routine is executed, the basic fuel injection amount Tp set three times before, which is used for setting the acceleration increase correction coefficient KFUEL, is updated and stored.

In this embodiment, the normal fuel injection amount Ti is corrected to be increased / decreased during the transient operation. However, when the fuel is injected during the normal injection timing according to the acceleration state to increase the fuel injection amount, It is obvious that the present invention can be applied to the case where the injection pulse signal is extendedly controlled by the acceleration detection during the pulse signal output to increase the acceleration amount.

<Effects of the Invention> As described above, according to the present invention, in the transient operation state of the engine, the correction control of the fuel supply amount according to the engine load state during the steady operation before the transient operation can be performed. There is an effect that a fuel supply amount commensurate with the above can be secured, and the transient operability can be improved by controlling the air-fuel ratio in the engine transient operation state to a desired value.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a system schematic diagram showing an embodiment of the present invention, FIGS. 3 and 4 are flow charts showing fuel injection control in the same embodiment, and FIG. The figure is a time chart for explaining the problems of the conventional control, FIG. 6 is a graph showing the relationship between the air-fuel ratio and various exhaust gas component concentrations, and FIG. 7 is the NO _x conversion rate by the three-way catalyst and the air-fuel ratio. It is a graph which shows the relationship of. 1 ... Engine, 2 ... Intake passage, 3 ... Throttle valve, 4
...... Throttle valve opening sensor, 5 ...... Rotation speed sensor,
6 ... Control unit 7 ... Fuel injection valve, 8 ... Air flow meter

Claims (1)

[Claims] 1. An engine operating state detecting means for detecting an operating state of the engine, a fuel supply amount setting means for setting an engine requested fuel supply amount when the detected engine operating state is a steady operating state, and an engine. Throttle valve opening detection means for detecting the opening degree of the throttle valve interposed in the intake passage, and an engine based on the rate of change of the throttle valve opening detected by the throttle valve opening detection means per predetermined minute time period. Engine transient operating state detecting means for detecting a transient operating state, engine load detecting means for detecting a load of the engine at every predetermined minute time, and a value for a predetermined number of times before the engine load detected by the engine load detecting means is stored. The engine load storage means for detecting the engine transient operating state by the engine transient operating state detecting means, and the correction amount of the fuel supply amount according to the engine load stored a plurality of times in the engine load storing means for the first time. And the fuel supply correction amount setting means for constant,
Electronic control of an internal combustion engine, comprising: a fuel supply control unit that drives and controls the fuel supply unit based on the fuel supply amount set by the fuel injection amount setting unit and the correction amount set by the fuel supply correction amount setting unit. Fuel injection device.