JPH0710048Y2 - Fuel supply control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a fuel supply control device for an internal combustion engine having an electronically controlled fuel supply device.

<Prior Art> Conventionally, in an electronically controlled fuel supply device for an internal combustion engine, an intake air flow rate Q is detected as a state quantity of intake air, and from this and an engine speed N, a basic fuel injection amount Tp = K · Q. / N (K is a constant) is calculated, or the intake air pressure (intake negative pressure) PB is detected as the state quantity of the intake air, and based on this, the basic fuel injection amount Tp = K · η _V · PB · K Calculate _TA (K is a constant, η _V is volume efficiency, and K _TA is an intake air temperature correction coefficient). The method based on the intake air flow rate Q is called L-JETRO, and the intake pressure PB
This method is called D JETRO. Then, the air-fuel ratio feedback correction coefficient α, various correction coefficients COEF based on the water temperature, etc.
Then, the final fuel injection amount Ti = Tp · α · COEF + Ts is calculated by correcting the voltage correction amount Ts based on the battery voltage.

Then, at a predetermined timing synchronized with the engine rotation, a drive pulse signal having a pulse width corresponding to the fuel injection amount Ti is output to the electromagnetic fuel injection valve, thereby injecting and supplying the fuel to the engine. Vol. 10, Electrical Equipment, Body Equipment, Engine Parts "Page 260-Page 262 Sankaido Co., Ltd.
See October 15, 1980).

<Problems to be solved by the invention> However, in the D-JETRO system,
Since the intake pressure PB just before flowing into the combustion chamber of the engine is detected as the state quantity of the intake air, it is affected by the intake pulsation of the engine and, for example, time-synchronous sampling is performed to measure the intake pressure.
When PB is measured, as a result of randomly sampling the bottom value and the top value of the intake pulsation, the fluctuation of Tp becomes large, the fluctuation of the air-fuel ratio becomes large, and the fluctuation of the ignition timing also becomes large. Further, since the intake pressure PB changes due to the change in atmospheric pressure, the basic fuel injection amount Tp changes as a result, and the air-fuel ratio becomes rich or lean, which causes deterioration of exhaust performance, which is not preferable.

On the other hand, in the L-JETRO type, an air flow meter or the like for detecting the intake air flow rate Q is provided upstream of the engine with respect to the intake pipe, which may cause a response delay in the detection result. This is more remarkable in the internal combustion engine with a supercharger, and since the air flow meter is provided upstream of the supercharger, the response delay becomes larger and the engine is in a transient state. However, due to the response delay (turbo lag) of the supercharger itself, the response delay between the detection result of the air flow meter and the intake air flow rate Q actually sucked into the engine becomes larger.

Further, in the case of an internal combustion engine with a supercharger, a pressure change occurs between the compressor of the supercharger and the throttle chamber during supercharging, but the responsiveness to changes in the intake air flow rate due to the pressure change is The D-JETRO, which detects the intake pressure PB immediately before flowing into the fuel chamber, obtains the flow rate of the air flowing into the combustion chamber of the engine from the detection result of the air flow meter provided at a location distant from the combustion chamber. Good compared to L-JETRO.

The present invention has been made in view of such a conventional situation, and takes advantage of the advantages of both the L-JETRO system and the D-JETRO system to provide optimum control of the fuel of the internal combustion engine according to the transient / steady state of the engine. An object is to provide a supply control device.

<Means for Solving the Problems> Therefore, the present invention, as shown in FIG. 1, is an engine operating state detecting means for detecting an engine operating state including an engine speed, an intake pressure, and an intake air flow rate; First basic fuel supply amount setting means for setting a basic fuel supply amount based on the intake pressure thus determined, and second basic fuel supply amount setting means for setting a basic fuel supply amount based on the detected engine speed and intake air flow rate. Fuel supply amount setting means, engine state determination means for determining the transient / steady state of the engine, and when the steady state is determined by the engine state determination means, it is set by the second basic fuel supply amount setting means. A final fuel supply amount is calculated based on the basic fuel supply amount, and a correction amount for correcting the first basic fuel supply amount to be equal to the second basic fuel supply amount is set, and a transient state is determined. When And a configuration and a correcting means for computing a final fuel supply amount based on the correction amount and the basic fuel supply quantity set by said first basic fuel supply quantity setting means.

<Operation> In the above configuration, when it is determined that the engine is in the steady state, the final fuel is supplied based on the basic fuel supply amount based on the intake air flow rate set by the second basic fuel supply amount setting means. The supply amount is calculated. Further, a correction amount for correcting the first basic fuel supply amount to be equal to the second basic fuel supply amount is set.

On the other hand, if it is determined that the engine is in a transient state, the first
The final fuel supply amount is calculated based on the basic fuel supply amount based on the intake pressure set by the basic fuel supply amount setting means and the correction amount described above.

Therefore, in the steady state, it is not affected by the intake pulsation, etc., and in the transient state, the response is good, and by adding a predetermined correction amount, the fuel supply amount at the transition from the transient state to the steady state is Differences are corrected.

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

In FIG. 2 showing an embodiment of the present invention, exhaust gas discharged from the internal combustion engine 1 rotates a turbine 4 of a supercharger 3 through an exhaust passage 2. A compressor 5 is provided coaxially with the turbine 4, and the compressor 5 rotates in synchronization with the turbine 4 to supercharge the air in the intake passage 6. The air sucked from the air cleaner 7 is supercharged by the supercharger 3, and sequentially passes through the intake passage 6 through the throttle valve 9, collector 10 and intake manifold 11 of the throttle chamber 8 and immediately before the combustion chamber 12 of the internal combustion engine body 1. , Is mixed with fuel injected from a fuel injection valve 13 provided for each cylinder, and is supplied to the combustion chamber 12. The fuel injection valve 13 is an electromagnetic fuel injection valve that is opened by energizing a solenoid, and is closed by stopping energization.The fuel injection valve 13 is energized and opened by a drive pulse signal from a control unit 20 described later, and is not shown. Fuel that is pressure-fed by the fuel pump and adjusted to a predetermined pressure by the pressure regulator is injected.

The combustion chamber 12 of the engine 1 is provided with a spark plug 14, which causes spark ignition to ignite and burn the air-fuel mixture.

Control unit 20 consists of CPU, ROM, RAM, A / D converter,
A microcomputer including an input / output interface is provided, and arithmetic processing is performed based on input signals from various sensors to control the operation of the fuel injection valve 13 and the spark plug 14. However, only the control of the fuel injection amount by the fuel injection valve 13 will be described below.

As the various sensors, an intake pressure sensor 31 is provided in the intake manifold 11, and an intake pressure (intake negative pressure) PB
To detect.

Further, an intake air temperature sensor 32 is provided to detect the intake air temperature Ta.

An air flow meter 33 is provided in the intake passage 6 to detect the intake air flow rate Q.

In addition, a crank angle sensor 34 is provided, for example, 4
In the case of a cylinder, the reference signal REF for each crank angle of 180 ° and the unit signal POS for each crank angle of 1 to 2 ° are output. The engine speed N can be calculated from these signals.

Further, the throttle valve 9 is provided with a potentiometer-type throttle sensor 35 to detect the throttle valve opening TVO.

Further, an O ₂ sensor 36 is provided in the exhaust passage 2 of the engine 1 to detect rich / lean of the air-fuel ratio via the oxygen concentration in the exhaust.

A water temperature sensor 37 is provided so as to face the water jacket of the engine 1 and detects the cooling water temperature Tw.

Here, the microcomputer (CPU) built in the control unit 20 performs arithmetic processing according to the program on the ROM shown as a flowchart in FIG. 3 to control the fuel injection amount.

Next, with reference to the flow charts of FIGS. 3 to 5, the state of the arithmetic processing of the microcomputer in the control unit 20 will be described.

FIG. 3 is an intake pressure detection routine that is executed every predetermined period (for example, 4 ms), and is shown as a step (denoted by S in the figure).
The same applies hereinafter) 1, the output power V _PB from the intake pressure sensor 31 is input, and the intake pressure PB (mmHg) is obtained by searching from the one-dimensional map stored in the ROM in advance according to the output voltage V _PB .

FIG. 4 is also an intake air flow rate detection routine that is executed every predetermined period (for example, 4 ms). In step 3, the detected value Q of the intake air flow rate from the air flow meter 33 is read.

FIG. 5 shows a fuel supply control routine executed every predetermined period (for example, 10 ms). In step 11, the intake pressure PB, the intake air flow rate Q, and the intake temperature sensor 32 are calculated as described above. Then, the detection signals from various sensors such as the crank angle sensor 34, the O ₂ sensor 36, and the water temperature sensor 37 are input. That is, the intake pressure detection routine, the intake air flow rate detection routine, and the function of step 11 constitute the engine operating state detection means.

In step 12, based on the detected intake pressure PB, the basic fuel injection amount Tp1 = K ₁ · η _V · PB · K _TA (K ₁ is a constant, η _V is volume efficiency, K _TA is the intake temperature correction coefficient) Is calculated. That is, step 12 has the function of the first basic fuel supply amount setting means.

In step 13, the basic fuel supply amount Tp2 = K ₂ · Q / N (K ₂ is a constant) is calculated based on the detected intake air flow rate Q. That is, step 13 has the function of the second basic fuel supply amount setting means.

Next, in step 14, the detection signal TVO of the throttle sensor 35 is input.

In step 15, the detection signal TVO of the throttle sensor 35
And the difference between the previous detected value TVO _OLD and ΔTVO (= TVO-TVO _OLD )
Is greater than or equal to a predetermined value C1, it is determined whether the operating state of the engine 1 is a transient state or a steady state. That is, the difference ΔTVO is ΔTVO ≧
In the case of C1, there is a sudden operation of the throttle valve 9, and it is possible to determine that it is a transitional state in which, for example, the intake air flow rate Q, the intake pressure PB, etc., change rapidly. On the other hand, when ΔTVO <C1, it can be determined that the operation of the throttle valve 9 is so-called a steady state. That is, step 14 and step 15 have a function of engine state determination means.

If ΔTVO <C1 in step 15, the process proceeds to step 16, in which the rate of change ΔTVO of the opening of the throttle valve 9 is a predetermined value C2 (C1 >>) which is smaller than the predetermined value C1 used in step 15.
By comparing with C2), it is judged whether the operating state is a complete steady state that hardly changes. And ΔTV
If O <C2, it is regarded as a complete steady state and step 17
Proceed to.

In step 17, the operating state is the first basic fuel supply amount Tp1.
The correction amount HSTp1 for correcting the first basic fuel supply amount Tp1 in the steady state to be equal to the second basic fuel supply amount Tp2 in the steady state is a weighted average. It is obtained by performing the weighted average processing according to the following equation using the processing coefficient W.

HSTp1 ← W (Tp2-Tp1) + (1-W) HSTp1 _{OLD In the} next step 18, the weighted average correction amount HSTp1 obtained in step 17 is stored as the previous data HSTp1 _OLD used in the next weighted average processing. .

Incidentally, if ΔTVO <C2 is not satisfied in step 16, it is determined that the operating state is not the completely steady state, and the process jumps to step 19.

In step 19, the basic fuel supply amount Tp2 calculated in step 13 is set again as the basic fuel injection amount Tp for calculating the final fuel injection amount Ti described later.

On the other hand, if ΔTVO ≧ C1 in step 15, the process proceeds to step 30, and the basic fuel injection amount Tp1 calculated in step 12 and the basic fuel injection amount Tp1 calculated in step 12 are used as the basic fuel injection amount Tp when calculating the final fuel injection amount Ti described later. Based on the correction amount HSTp1 obtained in 17, set by the formula Tp ← Tp1 + HSTp1. That is, steps 15 to 19 and steps
30 functions correspond to the correction means.

Then, after that, the process proceeds to step 20, in which the cooling water temperature Tw detected by the water temperature sensor 37 and various correction coefficients COEF according to the operating conditions are set, and the effective opening time of the fuel injection valve 13 is changed by the change of the battery voltage. Set the correction amount Ts for correcting T.

In step 21, the air-fuel ratio feedback correction coefficient LAMBDA that is set so that the air-fuel ratio of the engine intake air-fuel mixture obtained based on the oxygen concentration in the exhaust gas detected by the oxygen sensor 36 approaches the target air-fuel ratio is read.

Then, in step 22, step 19 or step 30
Using the basic fuel injection amount Tp set in step 1, the final fuel injection amount Ti is calculated by the following equation.

Ti = Tp × LAMBDA × COEF + Ts In the next step 23, an injection pulse signal having a pulse width corresponding to the fuel injection amount Ti calculated in this way is output to the fuel injection valve 13 at a predetermined timing synchronized with the engine rotation. Thus, the fuel is injected and supplied to the engine 1.

In the present embodiment, the change in the detection signal TVO of the throttle sensor 35 that detects the opening degree of the throttle valve 9 is used to determine whether the operating state of the engine 1 is a transient state or a steady state. As a determination, in addition to ΔTVO, intake pressure P
It may be performed by the change ΔPB (ΔQ) of B and the change ΔTp of the basic fuel injection amount.

Further, if the correction amount HSTp1 is calculated for each region partitioned by the intake pressure PB representing the load and the engine speed N and used for the correction calculation, it is possible to perform more precise control.

Further, regarding the correction amount HSTp1, the correction method by addition is shown, but step 17 and step 30 are respectively referred to as step 17 ′ and step 30 ′ which will be described later, and step 18 is excluded, and the same correction can be performed by multiplication. It goes without saying that the effect can be obtained.

S17 ′; HSTp1 ← W (Tp2 / Tp1) + (1-W) HSTp1 S30 ′; Tp ← Tp1 × HSTp1 As described above, according to the present embodiment, FIG. In a transient state in which the influence of a response delay such as turbo lag becomes noticeable due to a rapid change of the throttle valve 9 as shown in Fig. 5, the final intake pressure PB immediately before flowing into the combustion chamber 12 of the engine 1 is determined. Fuel injection amount
Since Ti is calculated, responsiveness to changes in the injection amount is good, and in the steady state, the final fuel injection amount Ti is calculated based on the detected intake air flow rate Q,
There is no influence of the intake pulsation of the engine 1, the fuel injection amount Ti does not fluctuate, and the fluctuation of the air-fuel ratio does not increase.

Further, since it is not affected by the change in atmospheric pressure, the air-fuel ratio does not become rich or lean, and the exhaust performance becomes good.

Further, the first basic fuel supply amount Tp in the steady state is set to be equal to the second basic fuel supply amount Tp2 in the steady state.
Since the correction amount HSTp1 that corrects 1 is obtained by performing a weighted average process, there is almost no fluctuation in the basic fuel supply amount Tp when transitioning from the transient state to the steady state, and when the transition from the transient state to the steady state occurs. The difference in the fuel supply amount is corrected, the final fuel injection amount Ti does not change, and the fluctuation of the air-fuel ratio does not increase.

In addition, although the present embodiment has described the internal combustion engine with a supercharger,
Of course, the same effect can be obtained also in a general internal combustion engine without a supercharger.

<Effect of Device> As described above, according to the present invention, the final fuel supply amount is calculated based on the intake pressure when the engine is in the transient state, and the final fuel supply amount is calculated based on the intake air flow rate when the engine is in the steady state. Since the supply amount is calculated, the advantages of both the L-JETRO system and the D-JETRO system can be utilized to perform optimum control according to the operating state of the engine.
Fluctuations in Ti and the air-fuel ratio can be suppressed, and exhaust performance can be improved.

Further, since the correction amount for correcting the steady state first basic fuel supply amount to be equal to the steady state second basic fuel supply amount is set, the fuel injection amount when transitioning from the transient state to the steady state is performed. It is possible to reduce the blurring.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a configuration diagram showing the configuration of an embodiment of the present invention, and FIGS. 3 to 5 are flow charts showing various control routines of the same embodiment. FIG. 6 is a time chart explaining the operation of the above embodiment. 1 ... Internal combustion engine, 3 ... Supercharger, 6 ... Intake passage, 9 ... Throttle valve, 13 ... Fuel injection valve, 20 ... Control unit,
31 ... Intake pressure sensor, 33 ... Air flow meter, 34 ... Crank angle sensor

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. An engine operating state detecting means for detecting an engine operating state including an engine speed, an intake pressure and an intake air flow rate, and a first basic system for setting a basic fuel supply amount based on the detected intake pressure. Fuel supply amount setting means, second basic fuel supply amount setting means for setting a basic fuel supply amount based on the detected engine speed and intake air flow rate, and an engine state for determining a transient / steady state of the engine When the determination means and the engine state determination means determine the steady state, the final fuel supply amount is calculated based on the basic fuel supply amount set by the second basic fuel supply amount setting means, and the first fuel supply amount is calculated. Of the basic fuel supply amount is set to be equal to the second basic fuel supply amount, and when the transient state is determined, the basic amount set by the first basic fuel supply amount setting means is set. Burn A fuel supply control device for an internal combustion engine, comprising: a correction unit that calculates a final fuel supply amount based on the fuel supply amount and the correction amount.