JPS63195347A - Electrically controlled fuel injection device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent the occurance of shock shortly after acceleration is completed by controlling basic fuel injection quantity to be less than the upper limit for acceleration during the period of acceleration and within the period of a predetermined time after acceleration is completed, and to be less than the upper limit smaller than that for acceleration for normal operations under other operating conditions. CONSTITUTION:A basic fuel injection setting means operates basic fuel injection quantity based on intake air quantity from a hot wire flowmeter and engine speed. An acceleration upper limit setting means judges that the time for acceleration is applicable when throttle valve opening increases at a rate greater than a predetermined value, thereby setting the upper limit for acceleration during the period of acceleration and within the period of a predetermined time after acceleration is completed. A normal operation upper limit setting means sets the upper limit smaller than that for acceleration for normal operations under other operating conditions. A basic fuel injection quantity upper limit control means selects either one, which is smaller than the other, of basic fuel injection quantity and the upper limit, thereby outputting thereof to a fuel injection quantity setting means.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an electronically controlled fuel injection device for an internal combustion engine, and in particular to an upper limit value of the basic fuel injection amount that is set based on the intake air flow rate and rotational speed of the engine. Concerning improved control.

<Prior Art> Examples of conventional electronically controlled fuel injection devices for internal combustion engines include the following (see Japanese Patent Laid-Open No. 59-49334, etc.).

That is, the intake air flow rate Q and rotational speed N of the engine are detected,
Based on these, the basic fuel injection amount Tp (-KXQ/N
; is a constant). Various correction coefficients C are set according to engine operating conditions, mainly engine cooling water temperature.
0EF and a correction numerator s for correcting the change in the effective valve opening time of the electromagnetic fuel injection valve due to the battery voltage, the basic fuel injection amount is corrected and the final fuel injection amount 'l' i ( -T p X COE F + T
'! 1) Set.

Here, a drive pulse signal having a pulse width corresponding to the fuel injection amount Ti is output to the electromagnetic fuel injection valve in synchronization with the rotation of the engine based on a reference signal obtained from the crank angle sensor. The injection valve was opened to inject fuel into the engine.

By the way, in an internal combustion engine, when an intake valve is closed under a high engine load condition in which a throttle valve installed in an intake passage has a large opening, a backflow or blowback of intake air generally occurs. When the intake air flow rate is detected using a hot-wire flowmeter, the blowback of the intake air is detected as the intake air flow rate, so the detection point of this blowback is more important than the intake air flow rate that is actually drawn into the cylinder. However, based on this incorrect intake air flow rate detection result, more fuel is injected than necessary, resulting in an over-rich air-fuel ratio and worsening exhaust properties and fuel consumption. .

A hot wire flow meter controls the current value to the hot wire resistor installed in the intake passage in order to keep the resistance value constant against changes in the intake air flow rate, and detects the intake air flow rate corresponding to this current value. Since the intake air flow rate is detected based on the change in resistance value due to the hot wire resistance being cooled by the intake flow, the direction of the intake air flow relative to the hot wire resistance is irrelevant to the detected value. , even if it blows back, it will be detected without distinguishing it from the forward flow.

For this reason, in the past, an upper limit value T pv-□ was set for the basic fuel injection amount 'rp set based on the intake air flow rate, and the basic fuel injection amount 'rp was set based on the detected values of the intake air flow rate Q and the engine rotational speed N. The injection amount 'rp is this upper limit value Tp 11X
When exceeding the upper limit Tp-ax, set the upper limit Tp-ax as the basic fuel injection amount Tp.
The basic fuel injection amount Tp is not set to exceed the value Tp, thereby preventing the air-fuel ratio from becoming excessively enriched due to blowback detection.

The above upper limit value Tp. is set based on the amount of air taken in when the throttle valve is fully open in a steady engine operating state, and this upper limit value Tp is set so that the basic fuel injection amount 'rp will not exceed it unless blowback is detected. Set it to a value.

In addition, in a fuel injection device of a so-called single point injection (S, P, I) system in which a fuel injection valve is installed upstream of a throttle valve installed in the engine intake passage, fuel is injected upstream of the throttle valve. Since fuel is injected and supplied, it is necessary to inject fuel into the air filling the intake manifold downstream of the throttle valve when the engine accelerates, but the intake air flow rate when filling the intake manifold is constant. Since the flow rate will be higher than the maximum intake air flow rate during operation, if the basic fuel injection amount Tp is limited using the upper limit values Tp and y at this time, the injection amount will be insufficient and the air-fuel ratio will be diluted. Upper jll ([T
Upper limit T for acceleration greater than p, * +g pt□
, 8, and when the engine is accelerating, this acceleration upper limit 'rp□7. He is trying to limit the basic fuel injection amount Tp based on. (See Japanese Patent Application No. 61-090045).

(Problems to be Solved by the Invention) According to such conventional upper limit value control of the basic fuel injection amount Tp, an operation in which the basic fuel injection amount 'rp is limited based on the upper limit value T pt□, , l for acceleration. The state is limited to the engine acceleration state, and when the acceleration is deemed to have ended, the upper limit value T P a is set corresponding to the steady operating state. The upper limit of the basic fuel injection amount 'rp is set based on .

However, as shown in Fig. 4, in reality, the intake air flow rate is higher than the maximum intake air flow rate in the steady state of operation, not only during acceleration but also immediately after the end of acceleration. If the basic fuel injection amount Tp is limited using the upper limit values Tp, , Shocks could occur due to the dilution of the fuel, impairing drivability.

The present invention has been made in view of the above problems, and it is an object of the present invention to avoid the dilution of the air-fuel ratio due to the upper limit restriction on the basic fuel injection amount and to prevent the occurrence of shock.

Therefore, in the present invention, as shown in FIG. A basic fuel injection amount setting means that sets the basic fuel injection amount based on the intake air flow rate and rotational speed detected by the system, and various correction coefficients that determine the basic fuel injection amount set thereby according to the engine operating state. An internal combustion engine comprising: a fuel injection amount setting means for correcting the fuel injection amount based on the fuel injection amount; and a fuel injection valve drive control means for driving and controlling the fuel injection valve according to the fuel injection amount set by the fuel injection amount setting means. In an electronically controlled fuel injection system for an engine, the engine acceleration state detection means detects the acceleration state of the engine, and the basic fuel injection amount is detected by the engine acceleration state detection means during engine acceleration and within a predetermined time after the end of acceleration. an acceleration upper limit value setting means for setting the upper limit value to a predetermined acceleration upper limit value; and an acceleration upper limit value setting means that is smaller than the acceleration upper limit value by a predetermined amount in a state other than the upper limit setting operation state. A steady state upper limit value setting means sets a certain steady state upper limit value as the upper limit value of the basic fuel injection amount, and the basic fuel injection amount set by the basic fuel injection amount setting means is set as the upper limit value for acceleration or a constant Basic fuel injection amount upper limit limiting means is provided for causing the fuel injection amount setting means to set the fuel injection amount based on these upper limit values in an operating state in which the constant upper limit values are exceeded.

According to this configuration, when the basic fuel injection amount set based on the intake air flow rate and rotational speed exceeds the predetermined upper limit value for acceleration during engine acceleration and within a predetermined time after the end of acceleration, the engine is accelerated. The fuel injection amount is set using the upper limit value for the basic fuel injection amount. That is, during acceleration of the engine and within a predetermined time after the end of acceleration, the basic fuel injection amount is limited to within the upper limit value for acceleration. In addition, in operating states other than those in which the acceleration upper limit is set, the basic fuel injection amount is limited to a steady state upper limit that is smaller than the acceleration upper limit.

Therefore, even during steady operation immediately after acceleration, the basic fuel injection amount is limited by the upper limit value for acceleration.
Similar to during acceleration, the required injection amount can be ensured immediately after the end of acceleration when the air flow rate is greater than the maximum intake air flow rate in the steady operating state.

<Example) An embodiment of the present invention will be described below based on the drawings.

In FIG. 2, a control device 1 including a microcomputer includes a rotation speed signal N1 output from a rotation speed sensor 2 as an engine rotation speed detection means, a hot wire air flow meter 3 as an intake air flow rate detection means, and a rotation speed signal N1 outputted from a rotation speed sensor 2 as an engine rotation speed detection means. Output intake air flow rate signal Q1 Throttle valve opening sensor 4
The throttle valve opening signal α output from the controller 5 and the cooling water temperature signal Tw output from the water temperature sensor 5 are input. The control device 1 sets the fuel injection amount TI according to the routine shown in the flowchart of FIG. It is output to the drive circuit 7 of the electromagnetic fuel injection valve 6 provided in the passage.

Here, the control device 1 is a basic fuel injection amount setting means.

Fuel injection amount setting means and upper limit value setting means for acceleration.

The control device 1 and the drive circuit 7 constitute a fuel injection valve drive control means, and the control device 1 and the throttle valve opening sensor also serve as a steady state upper limit value setting means and a basic fuel injection amount upper limit limiter. 4 constitutes an engine acceleration state detection means.

Next, the setting control of the fuel injection amount Tt will be explained according to the routine shown in the flowchart of FIG.

In step (rSJ in the figure, the same applies hereinafter) 1, the engine rotational speed N, intake air flow rate Q, cooling water temperature Tw, and throttle valve opening degree α detected by each sensor 2 to 5 are input.

In step 2, the engine rotation speed N input in step 1 is
and the basic fuel injection amount Tp (
=KXQ/N; is a constant).

In step 3, it is determined whether the engine is in an accelerating state based on the throttle valve opening degree α input in step 1.

That is, when the throttle valve opening α is increasing at a rate greater than a predetermined rate, it is assumed that the engine is in an accelerating state, and step 4 is performed.
Otherwise, proceed to step 9. In addition, the engine acceleration state is detected based on changes in the basic fuel injection amount Tp'P, intake air flow rate Q, etc. in addition to the throttle valve opening α. Also good.

When it is determined in step 3 that the engine is in an accelerating state and the process proceeds to step 4, the flag is set to 1 and the process proceeds to the next step 5.

In step 5, the upper limit Tpya□ for regulating the maximum value of the basic fuel injection amount Tp is set to a preset upper limit Tp□1 for acceleration. ．． Set to l. This upper limit value T pTRmag during acceleration is set corresponding to the maximum intake air flow rate Q including intake manifold filling bone during acceleration.

Then, in step 6, the upper limit value Tpa□ (upper limit value for acceleration Tpr□□) set in step 5 is compared with the basic fuel injection amount Tp calculated in step 2, and 'rp
>'rp□x(Tpt□,), which is the basic fuel injection amount set based on the intake air flow IQ and the engine rotational speed N'
When it is determined that rp exceeds the upper limit value 'rp, . Upper limit TpT engineering 1. , to avoid setting the fuel injection amount Ti based on the basic fuel injection 11Tp exceeding the upper limit Tp, □.

On the other hand, in step 6, T p 5 T P maX
(Tp, engineering □), and when it is determined that the basic fuel injection amount Tp calculated in step 2 is less than the upper limit value Tpmax and there is no detection of intake blowback, the basic fuel injection amount Tp calculated in step 2 The process directly proceeds to step 8 to calculate the fuel injection amount Ti using the injection amount Tp.

In step 8, the fuel injection amount Ti is calculated based on the basic fuel injection amount Tp or the upper limit value Tp-x calculated in step 2.

That is, the calculation in step 2 is performed using various correction coefficients C0EF that are mainly set based on the cooling water temperature Tw input in step 1, and a correction numerator s for correcting changes in the effective valve opening time of the fuel injection valve 6 due to battery voltage. The basic fuel injection amount Tp, which is the result or the upper limit for acceleration (1'rpy*wax), is corrected using these and the fuel injection amount Ti (
-Tp The upper limit value T pT'Reh*x.

On the other hand, if it is determined in step 3 that the engine is not in an accelerating state, the process proceeds to step 9 and the flag is determined.

In the engine acceleration state, the flag is set to l (step 4), so immediately after acceleration, it is determined that the flag is 1 in step 9, and here the flag =
If it is determined to be 1, the counter value a is incremented by 1 in step 10, and then in step 11, the counter value a that has been incremented by 1 is compared with a predetermined value a1. Here, when it is determined that the counter value a is less than or equal to the predetermined value a1, that is,
If it is immediately after the end of acceleration, the process proceeds to step 5, and similarly to when it is determined in step 3 that the engine is in an accelerating state, the upper limit value for acceleration 'rp□s is set as the upper limit value Tp-x of the basic fuel injection amount Tp. x (see Figure 4), and the basic fuel injection ff calculated in step 2 in the same way as above.
1Tp and the upper limit value Tpsmx are compared and the upper limit value T p
Upper limit control of the basic fuel injection amount 'rp is performed based on , , .

On the other hand, if it is determined in step 11 that the counter value a exceeds the predetermined value a1, the flag is set to 0 in step 12, and then the process proceeds to step 13, where the upper limit value Tp, □, is set as the upper limit value for acceleration. A normal-time upper limit value Tpstmax is set to be smaller than the values Tp□, □ by a predetermined amount. This steady state upper limit value Tpst--true is set corresponding to the maximum intake air flow rate Q in the steady state of operation, and is calculated in step 2 when intake air blowback is detected by the hot wire air flow meter 3. The amount Tp exceeds this upper limit value TpSteam for steady state.

In step 13, if the steady state upper limit value T p st + amx is set as the upper limit value 'rp+s@X, then in step 6
Proceeding to step 2, the basic fuel injection amount Tp calculated in step 2 is compared with the upper limit value TI)wax, and as described above, the fuel injection amount based on the basic fuel injection amount Tp exceeding the upper limit value Tp,...l is determined. Avoid Ti settings. -Also, step 9
When it is determined that the flag is 0 in step 13, that is, in a steady operating state where the engine is not in an acceleration state and the counter value a is less than or equal to the predetermined value a, and is not immediately after the end of acceleration, the process proceeds to step 13 and the upper limit is set. The above-mentioned upper limit value Tp 5taax for steady state is set as the value Tp,...l.

In this way, in the engine acceleration state, the basic fuel injection amount Tp
The upper limit value T for acceleration is set as the upper limit value Tpsag of
As shown in Fig. 4, pt□, be. Therefore, even if the intake air flow rate Q exceeds the maximum intake air flow rate Q in the steady operating state immediately after acceleration ends, the required injection amount will not be reduced due to the upper limit value TI) saw restriction, and the air-fuel ratio dilution can be prevented. Therefore, it is possible to avoid the occurrence of stagnation due to the dilution of the air-fuel ratio immediately after the end of acceleration, and it is possible to improve engine operability.

In this embodiment, the upper limit value for acceleration Tpt□,8 is used as the upper limit value TpIIIX from the end of acceleration until the counter value a exceeds the predetermined value a.
Even within such a predetermined time, when a deceleration operating state of the engine is detected, the steady state upper limit value Tpsrs□ may be set immediately.

(Effects of the Invention) As explained above, according to the present invention, the value that limits the upper limit of the basic fuel injection amount when the engine is in an accelerating state is also applied within a predetermined time after the end of acceleration. This has the effect that it is possible to avoid the inability to secure the required injection amount due to the upper limit regulation in an operating state where the intake air flow rate is large immediately after the end of engine acceleration, and it is possible to prevent the occurrence of stagnation.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of the present invention, Fig. 2 is a system schematic diagram showing an embodiment of the present invention, Fig. 3 is a flowchart showing fuel injection amount control in the above embodiment, and Fig. 4 is a flowchart showing the fuel injection amount control in the above embodiment. It is a time chart showing the problems of control and conventional control.

Claims (1)

[Claims] means for respectively detecting the intake air flow rate and rotational speed of the engine; and basic fuel injection amount setting means for setting the basic fuel injection amount based on the detected intake air flow rate and rotational speed;
a fuel injection amount setting means for setting the fuel injection amount by correcting the set basic fuel injection amount based on various correction coefficients determined according to the engine operating state; In an electronically controlled fuel injection device for an internal combustion engine, the electronically controlled fuel injection device for an internal combustion engine includes: a fuel injection valve drive control means for driving and controlling a valve; and an engine acceleration state detection means for detecting an acceleration state of the engine; Acceleration upper limit value setting means for setting the upper limit value of the basic fuel injection amount to a predetermined acceleration upper limit value during engine acceleration and within a predetermined time from the end of acceleration; and an upper limit value set by the acceleration upper limit value setting means. A steady state upper limit value setting means for setting a steady state upper limit value that is smaller than the acceleration upper limit value by a predetermined amount as the upper limit value of the basic fuel injection amount in a state other than the set operating state;
In an operating state in which the basic fuel injection amount set by the basic fuel injection amount setting means exceeds an acceleration upper limit value or a steady state upper limit value, the fuel injection amount setting means sets the fuel injection amount based on these upper limit values. An electronically controlled fuel injection device for an internal combustion engine, comprising means for limiting an upper limit of basic fuel injection amount.