JPH0713490B2 - Electronic control fuel injection type internal combustion engine deceleration reduction control device - Google Patents

Description

The present invention relates to a deceleration / reduction control device for an electronically controlled fuel injection internal combustion engine.

<Prior Art> As an electronically controlled fuel injection internal combustion engine, there are the following conventional ones.

That is, the basic fuel injection amount Tp (= K × Q / N; 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, the ignition coil, etc.).
(K is a constant), and further various correction factors COEF according to engine operating conditions such as engine temperature and correction amount by battery voltage
After calculating Ts, the basic fuel injection amount Tp is corrected and calculated to set the final fuel injection amount Ti (= Tp × COEF + Ts).

Then, by outputting an injection pulse signal having a pulse width corresponding to the set fuel injection amount Ti to the electromagnetic fuel injection valve, a predetermined amount of fuel is injected and supplied to the engine (JP-A-59-59). (See No. 203828, etc.).

Further, particularly in an electronically controlled fuel injection internal combustion engine having a fuel injection valve in the upstream portion of the intake passage (for example, upstream of the throttle valve), fuel (wall flow) adhering to the inner wall of the intake passage during engine deceleration Since the throttle valve is fully closed (idle position) and then supplied to the cylinder with a delay, there is a risk of over-riching the air-fuel ratio. Then, by setting the fuel injection amount Ti, it is possible to prevent the air-fuel ratio from becoming overrich as described above.

Specifically, a throttle valve opening sensor for detecting the opening of a throttle valve provided in the intake passage is provided, and the opening change rate Δθ (valve closing speed) per unit time obtained from the detection value of this sensor is provided. ) And a predetermined value Δθ ₁ (for example, −2.2 ° /
10 ms) and determines that the engine is in deceleration operation when the valve closing speed is equal to or higher than a predetermined value. Then, when the deceleration operation is determined, the engine speed N, the basic fuel injection amount
The rotation speed dependent deceleration reduction coefficient NKDC, the basic injection amount dependent deceleration reduction coefficient TpKDC, and the water temperature dependent deceleration reduction coefficient TwKDC stored respectively corresponding to Tp and the engine cooling water temperature Tw are set based on the respective detected values. Deceleration weight loss coefficient KDC (= NKDC × TpKDC × TwKDC) obtained by multiplying by
It is included in the various correction factors COEF used to set the fuel injection amount Ti, and the reduction correction is performed according to the deceleration state of the engine to avoid over-riching of the air-fuel ratio due to wall flow in the engine deceleration operation state. Was there.

The above-mentioned various correction coefficients COEF are determined, for example, by the constituent elements shown in the following equations.

COEF = 1 + water temperature correction coefficient K _TW + start correction coefficient Kas + post-idle increase correction coefficient Kai + air-fuel ratio correction coefficient Kmr-deceleration reduction coefficient KDC <Problems to be solved by the invention> By the way, the deceleration operation of the engine is as described above. This is performed by comparing the opening change rate Δθ of the throttle valve with a predetermined value Δθ ₁ , but the predetermined value Δθ ₁ that serves as a reference for this deceleration determination is closed by a spring or the like as shown in FIG. When the throttle valve urged in the valve direction is closed by the valve closing urging force from the fully open state to the fully closed state (when the engine is decelerated from a high load state and the required amount of deceleration reduction correction is the largest) When the engine is in the deceleration operation state and the valve closing speed is slow such that the accelerator is operated to stop the valve closing from the fully open state at the intermediate opening degree, the deceleration determination is not made.

That is, when the throttle valve is closed from the fully open state to the intermediate opening degree, the change in the intake air flow rate is smaller than in the case where the throttle valve is closed to the fully closed state, but the closing valve to the intermediate opening degree is decelerated. When the determination is made, the deceleration correction is performed in the same manner as when decelerating to the fully closed state, so the air-fuel ratio becomes over lean and a deceleration shock occurs. Therefore, the predetermined value Δθ _{1 is} set so as to avoid the deceleration reduction correction during deceleration up to the intermediate opening degree.
Is set.

However, when the predetermined value Δθ ₁ as the deceleration determination reference is set in this way, as shown in FIG. 5, the throttle valve is closed from the low opening state to the fully closed state during engine deceleration. (When the valve closing speed is slower than during deceleration from fully open to fully closed), deceleration determination is not made and weight reduction correction is not executed.
There is a problem that the air-fuel ratio becomes rich due to the influence of the wall flow and the hydrocarbons HC and CO which are harmful components of the exhaust gas increase (see FIG. 6). It should be noted that the predetermined value Δ in order to carry out deceleration reduction when decelerating from such a low opening state.
When θ ₁ is set, deceleration reduction is performed during deceleration from the above-described full opening to the intermediate opening, and the air-fuel ratio becomes lean.

The present invention has been made in view of the above problems, and it is an object of the present invention to optimize deceleration reduction control by improving deceleration determination so that a desired air-fuel ratio can be obtained during engine deceleration.

<Means for Solving Problems> Therefore, in the present invention, as shown in FIG. 1, the fuel injection amount setting means for setting the fuel injection amount in the steady operation based on the operating state of the engine is set. In an electronically controlled fuel injection type internal combustion engine, comprising: a fuel injection valve drive control means for drivingly controlling a fuel injection valve based on a fuel injection amount, an opening of a throttle valve interposed in an intake passage of the engine per unit time. Throttle opening degree change rate detecting means for detecting the degree of change in engine speed, deceleration operation determining means for comparing the detected degree of opening change with the reference rate of change to determine deceleration operation of the engine, and engine load. Engine load detection means for detecting, reference change rate setting means for variably setting the reference change rate according to the detected engine load, and the fuel injection when the deceleration operation of the engine is determined by the deceleration operation determination means. The deceleration / reduction control device is configured to include a reduction correction setting unit that corrects and sets the fuel injection amount set by the amount setting unit according to the engine operating state.

<Operation> According to the deceleration / reduction control device, whether or not the engine is in the deceleration operation state is determined by comparing the reference rate of change set according to the engine load with the detected rate of change of the throttle valve opening. When it is determined whether or not deceleration operation is determined, the fuel injection amount is reduced and corrected according to the engine operating state at that time.

That is, for example, during deceleration in which the throttle valve is closed from the fully open state to fully closed, and during deceleration in which the throttle valve is closed from the low opening state to fully closed, the opening change rate (closed valve Even if there is a difference in speed), the standard of deceleration judgment is variably set according to the engine load so that the deceleration operation that requires deceleration reduction can be accurately judged, and the difference in valve closing speed can be dealt with. Is.

<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 for detecting an opening θ of a throttle valve 3 provided in an intake passage 2 of an internal combustion engine 1, a rotation speed sensor 5 such as a crank angle sensor for detecting an engine rotation speed N, and an engine 1 Air flow meter 8 for detecting the intake air flow rate Q of the engine and a water temperature sensor 9 for detecting the engine cooling water temperature Tw
And the respective detection signals from these are input to the control unit 6 incorporating a microcomputer.

The control unit 6 sets the fuel injection amount Ti in the steady operation based on these detection signals, and performs the predetermined deceleration reduction correction during the engine deceleration operation to perform the fuel injection amount Ti.
Is set, and an injection pulse signal having a pulse width corresponding to the fuel injection amount Ti is output to the electromagnetic fuel injection valve 7 provided on the upstream side of the throttle valve 3.

That is, in this embodiment, the control unit 6 is
The fuel injection amount setting means, the fuel injection valve drive control means, the deceleration operation determination means, the reference change rate setting means, and the reduction correction setting means also serve as the throttle valve opening degree change rate detecting means with the throttle valve opening degree sensor 4. Further, the engine speed detecting means is constituted by the rotation speed sensor 5 and the air flow meter 8. Further, the engine operating state in this embodiment is the intake air flow rate Q, the engine rotation speed N, the cooling water temperature Tw, and the throttle valve opening degree θ detected by the above sensors.

Here, the setting control of the fuel injection amount Ti by the control unit 6 will be described based on the routine shown in the flowchart of FIG.

In step (denoted as "S" in the figure, the same applies hereinafter) 1, the throttle valve opening degree θ, the engine rotation speed N, the cooling water temperature Tw, and the intake air flow rate Q detected by each sensor are input.

In step 2, the throttle valve opening change rate Δθ per execution cycle of this routine (for example, 10 ms) is calculated by subtracting the previous input value from the throttle valve opening θ input in step 1 this time. The throttle valve opening change rate Δθ calculated in step 2 indicates that the throttle valve 3 is closed when the value is negative, and the throttle valve 3 is opened when the value is positive. The absolute value indicates the opening / closing speed of the throttle valve 3.

In step 3, the intake air flow rate Q input in step 1
And the engine speed N, the basic fuel injection amount Tp (← K ×
Q / N; K is a constant).

In step 4, the reference change rate Δθ ₁ that is the reference for the deceleration determination is set based on the basic fuel injection amount Tp indicating the engine load calculated in step 3. This reference rate of change Δθ ₁ is, as shown in the graph in the flowchart, the basic fuel injection amount.
The larger the Tp (engine load), the smaller the value (negative absolute value).

Therefore, during deceleration operation from high load in which the throttle valve 3 is closed from full open, the reference change rate Δθ _{1 with} a large absolute value is
Is set, it is possible to avoid the deceleration determination being made during deceleration from full opening to the intermediate opening (the closing speed of the throttle valve 3 is slow) that does not require deceleration reduction,
It is possible to prevent over leaning of the air-fuel ratio due to deceleration reduction correction.

Further, during deceleration operation from a low load in which the throttle valve 3 is closed from a low opening state, the reference change rate Δ with a small absolute value is obtained.
Since θ ₁ is set, the deceleration determination can be performed and the deceleration reduction can be performed at the time of such deceleration in which the valve closing speed becomes smaller than when the throttle valve 3 is closed from fully open to fully closed. It is possible to avoid enrichment and prevent the increase of carbon monoxide CO and hydrocarbon HC which are harmful components of the exhaust gas (see Fig. 6).

In the present embodiment, the basic fuel injection amount Tp is used as a representative of the engine load for setting the reference change rate Δθ ₁ as described above, but in addition to the basic fuel injection amount Tp,
The reference change rate Δθ ₁ may be set based on the intake air flow rate Q, the throttle valve opening θ, the intake negative pressure, the engine torque, the intake passage opening area / the engine rotation speed, and the like.

In step 5, the throttle valve opening change rate Δθ calculated in step 2 and the reference change rate Δθ set in step 4
₁ is compared, and when Δθ <Δθ ₁ , the throttle valve 3
Is closed at a rate (speed) equal to or higher than the reference change rate Δθ _1, it is determined that the engine 1 is in a predetermined deceleration operation state, and the routine proceeds to step 6. On the other hand, in step 5, Δθ ≧ Δ
When it is determined that θ ₁ and the engine 1 is not in the predetermined deceleration operation state but in the steady operation state, the acceleration operation state, or the predetermined slow deceleration operation state, the routine proceeds to step 12.

When it is determined in step 5 that the engine 1 is in a predetermined deceleration operation state (deceleration operation state in which the closing speed of the throttle valve 3 is a predetermined speed or more), the process proceeds to step 6, and whether or not the deceleration determination is the first time To determine.

Here, when it is determined that the deceleration determination is the first time,
Proceeding to step 7, the basic fuel injection amount Tp calculated in step 3 this time is set as the basic fuel injection amount Tp ₁ for setting the basic injection amount dependent deceleration reduction coefficient TpKDC which is an element of the deceleration reduction coefficient KDC, and step 8 is set. Go to. That is, the basic injection amount-dependent deceleration reduction coefficient TpKDC is set based on the basic fuel injection amount Tp set in step 3 at the initial stage of deceleration.

On the other hand, if it is determined in step 6 that the deceleration determination is not the first time, the setting of the basic fuel injection amount Tp ₁ in step 7 is skipped and the process proceeds to step 8.

In step 8, the engine speed N input in step 1,
Cooling water temperature Tw and basic fuel injection amount set in step 7
Based on Tp ₁ , rotation speed dependent deceleration reduction coefficient NKDC, water temperature dependent deceleration reduction coefficient TwKDC, basic injection amount dependent deceleration reduction coefficient TpKD
Decrease deceleration weight coefficient KDC (← NKDC × TwKD
C × TpKDC) is calculated.

The three elements NKDC, TwKDC, TpKD that determine the deceleration reduction coefficient KDC
Each C is set as shown in the graph in the flowchart, and a large deceleration reduction coefficient KDC is set at the time of deceleration from a high load and high rotation state and at the time of cold engine with a large wall flow.

When the deceleration reduction coefficient KDC is set in step 8, various correction coefficients COEF including this deceleration reduction coefficient KDC are set in step 9.
(For example, COEF = 1 + water temperature correction coefficient K _T w + start correction coefficient Kas
+ Post-idle increase correction coefficient Kai + air-fuel ratio correction coefficient Kmr-deceleration reduction coefficient KDC).

In step 10, a correction amount Ts for correcting the change in the effective valve opening time of the fuel injection valve 7 due to the battery voltage is set.

Then, in step 11, the basic fuel injection amount Tp calculated in step 2 and the various correction coefficients set in step 9
The final fuel injection amount Ti (← Tp × COEF + Ts) is set by COEF and the correction amount Ts set in step 10.

On the other hand, if it is determined in step 5 that Δθ ≧ Δθ ₁ and the engine 1 is not in the predetermined decelerating operation state,
The procedure proceeds to step 12, and it is determined whether the previously set deceleration reduction coefficient KDC is less than or equal to zero.

Here, when it is determined that the deceleration reduction coefficient KDC is a numerical value exceeding zero, the routine proceeds to step 13, where the previous value is multiplied by a predetermined value a (numerical value less than 1) and set as the current value.
Then, the deceleration reduction coefficient KDC set in step 13
The various correction factors COEF are set in step 9 using. When it is determined in step 12 that the previously set deceleration reduction coefficient KDC is less than or equal to zero, the current deceleration reduction coefficient KDC is set to zero in step 14, and the process proceeds to step 9.

That is, in the predetermined deceleration operation state based on the determination in step 5, various correction coefficients COEF are set based on the deceleration reduction coefficient KDC calculated in step 8. However, the deceleration reduction coefficient KDC based on such deceleration determination is set. After setting, when it is determined in step 5 that the engine 1 is not in the predetermined deceleration operation state, the deceleration reduction coefficient KDC is executed every execution cycle of this routine.
The deceleration reduction coefficient KDC set in the deceleration state is gradually made to approach zero by setting the reduction at a predetermined ratio (determined by the predetermined value a).

In the present embodiment, the element of the deceleration reduction coefficient KDC includes the basic injection amount-dependent deceleration reduction coefficient TpKDC corresponding to the basic fuel injection amount Tp set at the initial stage of deceleration. Since it is for performing deceleration reduction according to the state, the reference change rate Δθ ₁
Similar to the case of setting, the basic fuel injection amount Tp, the intake air flow rate Q, the throttle valve opening θ, the intake negative pressure, the engine torque, the intake passage opening area / the engine rotation speed, etc. are set. May be.

<Effects of the Invention> As described above, according to the present invention, the determination of the engine deceleration operation based on the opening change rate of the throttle valve is optimized, and the deceleration is performed even in the deceleration operation state in which the opening change rate (valve closing speed) is different. Since it is possible to perform the reduction control by determining the operating state that requires the reduction control, the air-fuel ratio control in the engine deceleration operating state becomes good, and it is possible to prevent the occurrence of deceleration shock and the increase of harmful exhaust components. The effect is that you can do it.

[Brief description of drawings]

FIG. 1 is a block diagram of the present invention, FIG. 2 is a schematic diagram of a system showing an embodiment of the present invention, FIG. 3 is a flowchart showing injection amount control in the same embodiment, and FIGS. 4 and 5 are conventional. FIG. 6 is a time chart for explaining control problems, and FIG. 6 is a graph showing the relationship between the air-fuel ratio and the conversion rate of the catalyst. 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, 9… Water temperature sensor

Claims (1)

[Claims] 1. A fuel injection amount setting means for setting a fuel injection amount during steady operation based on an operating condition of an engine, and a fuel injection valve drive control for driving and controlling a fuel injection valve based on the set fuel injection amount. And a throttle valve opening change rate detecting means for detecting an opening change rate per unit time of a throttle valve interposed in an intake passage of the engine. A deceleration operation determination means for determining the deceleration operation of the engine by comparing the opening change rate and the reference change rate; an engine load detection means for detecting the engine load;
Reference change rate setting means for variably setting the reference change rate according to the detected engine load, and fuel set by the fuel injection amount setting means when the deceleration operation determination means determines the deceleration operation of the engine. A deceleration / reduction control device for an electronically controlled fuel injection type internal combustion engine, comprising: a reduction correction setting means for reducing and setting an injection amount according to an engine operating state.