JPH06185396A - Basic fuel injection method - Google Patents

Abstract

PURPOSE:To enhance air-fuel ratio controllability at an initial stage in transition by calculating an intake pipe pressure, where a charge delay and a stroke delay of which are corrected, on the basis of a throttle opening degree and an engine speed detected at each predetermined timing so as to determine a basic fuel injection time. CONSTITUTION:An electronic controller 6 controls at least a fuel injection valve 5 in an engine 100 on the basis of at least a throttle opening degree signal detected by a throttle sensor 16 and an engine speed signal detected by a cam position sensor 14. The electronic controller 6 predicts an intake pipe pressure to be changed after a lapse of a predetermined time on the basis of the throttle opening degree and the engine speed, calculates a delay time of a stroke based on a calculated timing of a fuel injection quantity and an opening timing of an intake value, and further, and calculates a predictive pressure on the basis of the predicted intake pipe pressure and the calculated stroke delay time. Consequently, the electronic controller 6 determines a basic fuel injection time at each given timing based on the calculated predictive pressure and the engine speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a basic fuel injection method in a fuel injection type engine for automobiles.

[0002]

2. Description of the Related Art Conventionally, as a basic fuel injection method of this type, for example, as in the electronically controlled fuel injection device for an internal combustion engine disclosed in Japanese Patent Laid-Open No. 63-29038, the opening of a throttle valve, The intake air amount detected and the intake air temperature are respectively detected, and the intake air amount corresponding to each operating region in which the throttle valve opening and the rotation speed are used as parameters are searched in advance, and the searched intake air amount and the detected intake air amount are detected. It is known that a correction coefficient for the intake air amount is set according to the temperature, and the basic fuel injection amount is calculated by correcting the intake air amount with the set correction coefficient.

[0003]

By the way, during a transition, the actual intake air amount is detected, the correction coefficient is set as described above, and then the intake air amount is corrected by the correction coefficient to obtain the basic fuel. When calculating the injection amount, the appropriate fuel injection amount may be due to the delay of the signal in the filter that processes the signal from the sensor, or the delay of the stroke from the calculation of the fuel injection amount to the actual operation of the intake valve. Was sometimes not calculated. Therefore, since the fuel injection amount is not appropriate, the air-fuel ratio controllability in the initial stage of the transient state tends to deteriorate.

An object of the present invention is to eliminate such a problem.

[0005]

The present invention takes the following means in order to achieve such an object. That is, the basic fuel injection method according to the present invention detects the throttle opening and engine speed, predicts the intake pipe pressure changing after a predetermined time based on the detected throttle opening and engine speed, and The stroke delay time is calculated from the amount calculation timing and the intake valve closing timing, and the predicted pressure is calculated based on the predicted intake pipe pressure and the delay time,
It is characterized in that the basic injection time is calculated for each predetermined period based on the obtained predicted pressure and the engine speed at that time.

[0006]

With such a structure, the intake pipe pressure that has changed after a predetermined time is predicted based on the throttle opening and the engine speed for each predetermined time, and the stroke delay time is calculated. The predicted pressure is obtained based on the predicted intake pipe pressure and its delay time, and the basic injection time is calculated based on the predicted pressure and the engine speed obtained. In other words, the basic injection time is an intake pipe that corrects the delay between the start of the change in the intake air amount and the start of the change in the intake pipe pressure, which also depends on the capacity of the surge tank tank, and also the stroke delay. Since it is calculated from the pressure and the engine speed, the air-fuel ratio controllability at the initial stage of the transition is improved without correcting the delay in the filter or the like that processes the signal from the sensor.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

An engine 100 schematically shown in FIG. 1 is for an automobile, and its intake system 1 is provided with a throttle valve 2 which opens and closes in response to an accelerator pedal (not shown), and a surge is provided downstream thereof. A tank 3 is provided.
Intake manifold 4 of intake system 1 communicating with surge tank 3
A fuel injection valve 5 is further provided near one end of the fuel injection valve 5, and the fuel injection valve 5 is controlled by the electronic control unit 6. Further, an O ₂ sensor 21 for measuring the oxygen concentration in the exhaust gas is attached to the exhaust system 20 at a position upstream of a three-way catalyst 22 arranged in a pipe line leading to a muffler (not shown). There is. This O ₂ sensor 21
Outputs a voltage signal h corresponding to the oxygen concentration.

The electronic control unit 6 includes a central processing unit 7
And a storage device 8, an input interface 9, and an output interface 11 are mainly configured, and the input interface 9 includes an engine speed NE, a compression top dead center (cylinder). (Discrimination) and a rotation speed signal Ne output from a cam position sensor 14 for detecting a crank angle reference position, a cylinder determination signal G1, a crank angle reference position signal G2, and a vehicle speed sensor 15 for detecting a vehicle speed. The vehicle speed signal c, the throttle opening signal d output from the throttle sensor 16 for detecting the opening of the throttle valve 2, the water temperature signal e output from the water temperature sensor 17 for detecting the cooling water temperature of the engine, O mentioned above
_The voltage signal h or the like output from the ₂ sensor 21 is input. On the other hand, from the output interface 11, the fuel injection signal f is sent to the fuel injection valve 5, and the spark plug 1
Ignition pulse g is output to eight.

The electronic control unit 6 includes a throttle sensor 1
The throttle opening signal d output from 6 and the rotation speed signal Ne output from the cam position sensor 14 are used as main information, and the basic injection time TP is corrected by various correction coefficients determined according to the engine condition. To determine the injection valve opening time, that is, the injector final energization time T, control the fuel injection valve 5 according to the determined energization time, and inject fuel according to the engine load from the fuel injection valve 5 to the intake system 1. The program is built in. Moreover, in this program, in order to improve the air-fuel ratio controllability at the initial stage of the transition, the throttle opening TA and the engine speed NE are set.
Is detected, the intake pipe pressure and the pressure increase amount thereof are calculated at predetermined time intervals based on the detected throttle opening TA and engine speed NE, and the stroke delay time is calculated from the injection amount calculation timing and the intake valve closing timing. Is calculated, and the predicted pressure PMTP is calculated based on the obtained intake pipe pressure, the pressure increase amount, and the delay time, and the basic injection time TP is calculated based on the obtained predicted pressure PMTP and the engine speed NE at that time. It is programmed so as to calculate every predetermined period.

The outline of this basic injection amount control program is as follows.
This is as shown in FIGS. 2 and 3.

First, at step 51, the throttle opening TA is read from the throttle opening signal d output from the throttle sensor 16, and the rotation speed NE is read from the rotation speed signal b output from the rotation speed sensor 14. Step 52
Then, the (QNP, SP) map is searched from the obtained throttle opening TA and rotational speed NE to obtain the intake air amount QN.
Determine P _n and intake pipe pressure SP _n . Here, the intake air amount QNP _n is defined as a steady intake air amount at a unit rotation speed, and the intake pipe pressure SP _n is defined as a steady intake pipe absolute pressure determined by the throttle opening TA and the rotation speed NE. To be done. The (QNP, SP) map defines the intake air amount QNP _n and the intake pipe pressure SP _n as a pair using the engine speed NE and the throttle opening TA as parameters, and the configuration thereof is as shown in FIG. Is. In step 53, the charge delay coefficient KCHD is read. This charge delay coefficient KCHD is actually the intake system 1
Is a coefficient that is set based on the delay of the start time between the change in the intake air amount sucked into the intake manifold and the change in the intake pipe pressure in the intake manifold 4 detected by the surge tank 3. That is, the charge delay coefficient KCHD is determined from the change in the amount of air taken into the intake system 1 via the throttle valve 2 from the previous state to the present state until the intake pipe pressure in the surge tank 3 changes. It is set by the time.

In step 54, a predetermined time, for example, 5 mSEC
The increase amount ΔPM _n of the intake pipe pressure changed during
The calculated pressure PM _n is calculated by the following equation from the increase amount ΔPM _n obtained every predetermined time.

[0014]

[Equation 1] PM _n = PM _n−1 + ΔPM _n (2) Next, in the flowchart shown in FIG. 3, a program executed at the timing (N timing) defined by the cylinder determination signal G1 to calculate the basic injection amount will be described. First, in step 61, the latest calculated pressure PM _n and increase amount ΔPM _n at this time point and the detected engine speed NE are read. In step 62,
The time difference (stroke delay time) KTDLY between the timing of calculating the fuel injection amount and the timing of closing the intake valve is calculated by the following equation.

[0015]

[Equation 2] That is, the stroke delay time KTDLY measures the required rotation time T180 of 180 ° in terms of crank angle, and also the stroke delay crank angle between the fuel injection amount calculation timing and the intake valve closing timing. Then, this crank angle is converted into time and obtained.

In step 63, the read calculated pressure P
M _n and increase amount ΔPM _n , and obtained stroke delay time K
Predicted pressure PM considering stroke delay based on TDLY
Calculate TP. PMTP = PMC + ΔPM × KTDLY (4) In step 64, the predicted pressure M calculated in step 63
A normal TP map based on the PTP and the read engine speed NE (a map in which the basic injection time TP is set using the engine speed NE and the intake pipe pressure as parameters)
Then, the basic injection time TP is calculated. In step 65,
Other correction amounts at this time, such as A / F feedback correction amount and transient air-fuel ratio correction amount, and wet correction amount are calculated. In step 66, the effective injection time TAU is calculated based on the basic injection time TP and each correction coefficient.

In the above structure, a predetermined time of 5 mS
Steps 51 to 54 are executed for each EC, and the throttle opening TA and engine speed N detected at that time
E is used to calculate the increase amount ΔPM of the intake pipe pressure within a predetermined time in consideration of the charge delay coefficient KCHD,
The calculated pressure PM that is the intake pipe pressure for determining the basic injection amount TP is calculated, and the latest value is stored. That is,
A charge delay coefficient KCHD as a correction coefficient for the delay related to the intake pressure at the time when the operating state of the engine is detected
Since the increase amount ΔPM _n of the intake pipe pressure is calculated using
The calculated pressure PM is obtained by correcting the delay from the time when the intake air changes to the time when the intake pipe pressure actually changes, and corresponds to the intake air amount that has no delay time from the start of the change. In this case, by setting the predetermined time to be short, it is possible to reliably calculate the calculated pressure PM in which the charge delay is corrected even when a relatively rapid change occurs at the initial stage of transient or during rapid acceleration. Then,
Steps 61 to 66 are executed every N timings,
The predicted pressure PNTP is calculated by correcting the latest calculated pressure PM with the stroke delay element, and the basic injection time TP is calculated from the obtained predicted pressure PNTP and the engine speed at that time. The basic injection time TP is calculated from the intake pipe pressure. Therefore, the basic injection time is prevented from deviating from the actually required time due to the delay of the signal in the filter in the electronic circuit, the injection fuel amount becomes appropriate, and the air-fuel ratio controllability is improved.

The present invention is not limited to the embodiments described above.

In addition, the configuration of each part is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0020]

As described above in detail, the present invention calculates the intake pipe pressure with the charge delay and the stroke delay corrected based on the throttle opening and the engine speed detected every predetermined time. Since the basic injection time is determined by the intake pipe pressure, an appropriate basic injection time can be calculated even when there is a sudden change in the initial stage of a transition,
The air-fuel ratio controllability can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration explanatory view showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a control procedure of the embodiment.

FIG. 3 is a flowchart showing a control procedure of the embodiment.

FIG. 4 is a map configuration explanatory view showing a configuration of a map for setting an intake air amount QNP and an intake pipe pressure SP in the embodiment.

[Explanation of symbols]

 2 ... Throttle valve 4 ... Intake manifold 5 ... Fuel injection valve 6 ... Electronic control device 7 ... Central processing unit 8 ... Storage device 9 ... Input interface 11 ... Output interface

Claims (1)

[Claims] 1. A throttle opening and an engine speed are detected, and an intake pipe pressure which is changing after a predetermined time is predicted based on the detected throttle opening and the engine speed, and an injection amount calculation timing and an intake valve closing. The stroke delay time is calculated from the valve timing, the predicted pressure is calculated based on the predicted intake pipe pressure and the delay time, and the basic injection time is set based on the obtained predicted pressure and the engine speed at that time. A basic fuel injection method characterized in that it is calculated for each period.