JPH09280094A - Non-synchronous injection control method by throttle opening - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a non-synchronous injection quantity from being excessively much by deciding the changing quantity of opening as the upper limit value when the detected opening is over the set upper limit value, in an engine in which a non-synchronous injection quantity in transition period is decided based on the changing quantity of a throttle valve opening. SOLUTION: At operating an engine, an electronic control device 6 inputs output signals of an intake air pressure sensor 13, a cam position sensor 14, a water temperature sensor 17, an O2 sensor 21, and the like, a basic injection time based on the operating condition is corrected by various correcting factors so as to decide an effective injection time, and hence a fuel injection valve 5 provided on an intake air port is controlled. In this case, a map is referred, so as to obtain the upper limit value of a throttle opening corresponding to engine speed. When the detected throttle opening is over the upper limit value, a thottle opening for computation for computing the changing quantity of a throttle opening for computing a non-synchronous injection quantity in transition period is decided as the upper limit value, so as to be utilized for computating the non-synchronous injection quantity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an asynchronous injection control method mainly based on a throttle opening in a fuel injection type internal combustion engine for automobiles.

[0002]

2. Description of the Related Art Conventionally, there is known an internal combustion engine which employs a fuel injection control system called a so-called α-N system which determines a fuel injection amount on the basis of a throttle opening and an engine speed (for example, Japanese Patent Laid-Open Publication No. 2000-242242). 63-29038). That is, in this α-N system, the intake air amount is estimated from the throttle opening and the engine speed, and the fuel amount relative to the intake air amount is determined so that the air-fuel ratio becomes the stoichiometric air-fuel ratio. Also in this type of system, as in the so-called DJ system in which the fuel injection amount is determined based on the intake air flow rate or intake air pressure and the engine speed, an O ₂ sensor attached to the exhaust system is used during steady operation. Feedback control is performed based on the output voltage signal to calculate the fuel injection amount so that the air-fuel ratio becomes the stoichiometric air-fuel ratio, and during a transition, it is asynchronous with the timing of such normal fuel injection. In order to perform the injection, the fuel injection amount is calculated according to the change amount of the throttle opening.

[0003]

The intake air amount increases or decreases depending on the opening of the throttle valve. However, the intake air amount may vary depending on the engine speed even if the throttle opening is the same. That is, as shown in FIG.
When the engine speed is low, when the throttle valve is opened to some extent, that is, when a certain throttle opening is reached, even if the throttle valve is opened further, that is, the throttle opening becomes larger, the intake air amount is It shows a saturation state (saturation) that does not change at almost the same amount as at a certain throttle opening. This phenomenon occurs even when the engine speed is high, but when the engine speed is high, the saturation state does not occur up to a large throttle opening, unlike the case where the throttle opening becomes saturated, which is low.

For this reason, even when the throttle valve is opened by a predetermined amount from a certain opening, the amount of change in the throttle opening changes because the throttle opening becomes saturated when the engine speed is low and when it is high. Despite the same hand, the amount of intake air is different. Therefore, if the fuel injection amount is determined based on the change amount of the throttle opening when performing the asynchronous injection during the transition, the intake air amount, in other words, the asynchronous injection request amount is different. It may become overrich.

[0005] An object of the present invention is to solve such a problem.

[0006]

The present invention takes the following means in order to achieve such an object. That is, in the asynchronous injection control method by the throttle opening according to the present invention, since the relationship between the amount of change in the opening of the throttle valve and the intake air amount changes depending on the rotation speed of the internal combustion engine, Depending on the number, the upper limit value of the throttle valve opening is set to a value at which the amount of air passing through the throttle valve becomes substantially constant regardless of the opening, and the opening changes above the upper limit during transition. In this case, the opening change amount is determined based on the upper limit value, and the asynchronous injection amount is determined from the change amount.

With such a structure, when the opening of the throttle valve changes above the upper limit value, the amount of change in the opening of the throttle valve is determined based on the upper limit value. , The amount of change corresponding to the opening that does not actually change the amount of air passing through the throttle valve is
It will not be reflected in the asynchronous injection amount. Therefore, it is possible to prevent the asynchronous injection amount based on the determined change amount from becoming excessive with respect to the actual air amount passing through the throttle valve.
Therefore, the problem that the air-fuel ratio becomes overrich and the drivability becomes low is solved.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention calculates the fuel injection amount based on the rotational speed of the internal combustion engine and the opening degree of a throttle valve provided in the intake system during a steady state, and during a transient state, the fuel injection amount is calculated as described above. A non-synchronized injection control method based on a throttle opening, which determines an asynchronous injection amount to be injected separately from an injection of a fuel injection amount based on a change amount of an opening of a throttle valve. The opening of the throttle valve is detected, and the upper limit of the opening of the throttle valve at the detected rotational speed is set to a value at which the amount of air passing through the throttle valve becomes substantially constant regardless of the opening, and the detected opening is set. When the upper limit value is exceeded, the opening change amount is determined by the upper limit value, and the asynchronous injection amount is determined based on the determined change amount.

[0009]

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 an intake system 1 thereof is provided with a throttle valve 2 which opens and closes in response to an accelerator pedal (not shown), and a surge tank 3 is provided downstream thereof. It 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. In addition, 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 having a ROM area and a RAM area,
Input interface 9 and output interface 11
It is mainly composed of a microcomputer system including. The storage device 8 has an upper limit value T described later.
A map defining AMAX is stored in the ROM area, and the calculation throttle opening degree TAWORK is temporarily stored in the RAM area. The input interface 9 includes a rotation speed signal Ne output from a cam position sensor 14 for detecting the engine speed NE, cylinder discrimination, and a crank angle reference position, and a cylinder discrimination signal G.
1, the crank angle reference position signal G2, the vehicle speed signal c output from the vehicle speed sensor 15 for detecting the vehicle speed, and 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 100, the voltage signal h output from the O ₂ sensor 21, and the like are input. On the other hand, the output interface 11 outputs a fuel injection signal f to the fuel injection valve 5 and an ignition pulse g to the spark plug 18.

The electronic control unit 6 includes a throttle sensor 1
The basic fuel injection time TP is determined by using the throttle opening signal d output from 6 and the rotation speed signal Ne output from the cam position sensor 14 as main information.
₂ Based on the voltage signal h from the sensor 21, the basic fuel injection time TP is corrected by feedback control to determine the effective injection time TAU, and the determined effective injection time TAU
Is programmed to inject fuel in synchronism with engine rotation. In the asynchronous injection corresponding to the transient time, the engine speed NE is detected, the throttle opening TA is detected, and the upper limit value TAMAX of the throttle opening TA at the detected engine speed NE is exceeded by air passing through the throttle valve 2. The amount is set to a value that is substantially constant regardless of the throttle opening TA, and when the detected throttle opening TA exceeds the set upper limit value TAMAX, the change amount ΔTA of the throttle opening TA is set to the upper limit value T
It is programmed by AMAX, and the asynchronous injection amount is determined based on the determined change amount ΔTA.
The determination at the time of transition is made based on the engine speed NE, the vehicle speed, the change amount ΔTA of the throttle opening, and the like.
Further, as for the asynchronous injection control at the time of transition based on the determined asynchronous injection amount, what is widely known in this field can be used, and the description thereof will be omitted.

The outline of this asynchronous injection control program is as follows.
It is as shown in FIG. In addition, a map in which a typical engine speed NE, for example, an upper limit value TAMAX of the throttle opening TA for a low engine speed, a medium engine speed, and a high engine speed is set is attached to the program as data. This upper limit value TAMAX is a certain engine speed NE
In response to the throttle opening that does not increase the amount of air passing through the throttle valve 2, that is, the amount of intake air, even though the throttle valve 2 is opened, in other words, the throttle opening TA increases. It is set. Therefore, the upper limit value TMX is set to increase as the engine speed NE increases, as indicated by α, β, and γ in FIG. Also,
The upper limit value TAMAX is not limited to the above three values, and is further subdivided into, for example, the engine speed NE.
May be set in the map every 1000 rotations / minute.

Further, this program is executed every predetermined time, for example, every 10 milliseconds at the timing for carrying out the asynchronous injection, and the throttle opening T in a unit time is
In order to detect the amount of change ΔTA of A, for example, the calculation throttle opening TAW during the execution from the current execution to three times before is executed.
The ORK is stored in the storage device 8. In FIG. 2, first, in step S1, a map is searched for the engine speed NE already detected at this time, and an upper limit value T of the throttle opening TA corresponding to the engine speed NE is retrieved.
Find AMAX. In step S2, it is determined whether or not the throttle opening TA detected this time exceeds the upper limit value TAMAX. In step S3, the calculation throttle opening degree TAWORK for calculating the change amount ΔTA of the throttle opening degree TA for calculating the asynchronous injection amount is determined as the upper limit value TAMAX. In step S4, the calculation throttle opening TAW at the time of calculating the asynchronous injection amount three times before
ORK and the calculated throttle opening TAUOR obtained this time
The change amount ΔTA is calculated from the difference from K, and the change amount ΔTA
The asynchronous injection amount is calculated based on In this example,
The unit time for obtaining the change amount ΔTA is set to three times the predetermined time. In step S5, the throttle opening TA detected this time is adopted as the current calculation throttle opening TAWORK.

In such a configuration, when the throttle opening TA is relatively small and is below the upper limit value TAMAX, the control proceeds to steps S1 → S2 → S5 → S4, and the throttle opening TA at this point is set. The amount of change ΔTA is calculated by setting the calculation throttle opening degree TAWORK to calculate the asynchronous injection amount. Next, the case where the throttle valve 2 is opened widely and the throttle opening TA detected this time exceeds the upper limit TAMAX when the engine speed NE is low will be described. In this case, the control is step S1 →
S2 → S3 → S4, and the throttle opening T at this point
In place of A, the upper limit value TAMAX is set to the calculation throttle opening T
The asynchronous injection amount is calculated by calculating the change amount ΔTA in AWORK.

Specifically, for example, the upper limit value TAMAX is set to 13 °, and the previous calculation throttle opening T
It is assumed that the angle changes from 5 degrees for AWORK to 20 degrees for the throttle opening TA detected this time. Since the throttle opening TA itself has changed to 20 °, the original amount of change ΔTA is 1
Although it becomes 5 °, the throttle opening TA this time is the upper limit value TA
Since it exceeds MAX, the upper limit value TAMAX is applied to the current calculation throttle opening TAWORK. Therefore, the change amount ΔTA becomes 8 ° from 5 ° to 13 °, which is smaller than the original change amount ΔTA. This is because the throttle opening TA above the upper limit value TAMAX is substantially invalidated, and the opening range in which the intake air amount does not change is excluded from the change target of the throttle opening TA. is there. Therefore, the change amount ΔTA is only in the throttle opening range in which the intake air amount is substantially changing,
It substantially corresponds to the change amount of the intake air amount.

Thus, the throttle opening TA is substantially
Since the change amount ΔTA is calculated in the opening range where is changing and the asynchronous injection amount is calculated based on the change amount ΔTA, it is possible to calculate an appropriate required amount for the changed intake air amount. Therefore, the asynchronous injection amount does not become excessive with respect to the changed intake air amount, and it is possible to prevent the air-fuel ratio from becoming overrich.

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

[0018]

As described above, according to the present invention, it is possible to detect only the throttle opening degree at which the amount of air passing through the throttle valve changes regardless of whether the engine speed is high or low. Therefore, since the asynchronous injection amount is determined by the amount of change in the throttle opening degree according to the changed air amount, it is possible to prevent the air-fuel ratio from becoming overrich. Therefore, good drivability can be maintained even in a transient state.

[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 an operation explanatory view of the same embodiment.

FIG. 4 is an operation explanatory view of a conventional example.

[Explanation of symbols]

 2 ... Throttle valve 5 ... Fuel injection valve 6 ... Electronic control device 7 ... Central processing unit 8 ... Memory device 9 ... Input interface 11 ... Output interface 16 ... Throttle sensor

Claims (1)

[Claims] 1. A fuel injection amount is calculated on the basis of the rotational speed of an internal combustion engine and an opening degree of a throttle valve provided in an intake system during a steady state, and the fuel injection amount is injected during a transient state. Asynchronous injection control method based on the throttle opening that determines the asynchronous injection amount to be injected separately based on the amount of change in the opening of the throttle valve, which detects the rotational speed of the internal combustion engine and detects the opening of the throttle valve. The upper limit of the throttle valve opening at the detected rotational speed is set to a value at which the amount of air passing through the throttle valve becomes substantially constant regardless of the opening, and the detected opening exceeds the set upper limit. In this case, the asynchronous injection control method according to the throttle opening is characterized in that the change amount of the opening is determined by its upper limit value and the asynchronous injection amount is determined based on the determined change amount.