JPS6155335A - Fuel injection quantity controlling method of internal-combustion engine - Google Patents

Abstract

PURPOSE:To make optimum asynchronous injection corresponding to a driving state performable, by setting a fuel quantity of the asynchronous injection according to a fuel cut release condition when it comes to fruition during fuel cut performance. CONSTITUTION:In case of a fuel injection controller which installs a solenoid- operated fuel injection valve in a suction pipe and controls the fuel supply, when a fuel cut release condition comes to fruition (P5) during fuel cut performance (P4), a fuel quantity of asynchronous injection is determined on the basis of a driving state of an internal-combustion engine (P7). Therefore, during the fuel cut performance, when a throttle valve is full-close whereby an engine speed drops and the fuel cut is released, if the asynchronous fuel injection quantity is set on the basis of a warm-up state, the fuel quantity is at once increased to the quantity required and restored, thus responsiveness is securable without entailing an unexpected drop in output.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuel injection control method for an internal combustion engine, and more specifically, it is performed when a fuel cut is canceled and normal fuel injection control is resumed. The present invention relates to a fuel injection control method for an internal combustion engine that appropriately controls an asynchronous fuel amount of 0.

[Prior Art] In recent years, electronic control 61 of internal combustion engines has been implemented in floor cabinets, one of which is to supply fuel to the internal combustion engine between electromagnetic fuel injection valves installed in the intake pipe. Fuel injection $II iII device and its control 2+'+ that controls fuel injection by closing the valve
There is a way. In such fuel injection control, the fuel injection m is controlled according to the operating conditions such as the load of the internal combustion engine, but under conditions where the required fuel port of the internal combustion engine is extremely small, the fuel amount (g) valve operates. Due to the above characteristics, such as variations in response time, it may be difficult to accurately measure the fuel gauge. For this reason, the air-fuel ratio of the mixture involved in combustion in the internal combustion engine fluctuates, and the unburned fuel becomes 11
This can cause a combustion reaction near the catalytic converter installed in the exhaust system, heating the catalyst and damaging it by 1Ω, causing packfire, and worsening fuel efficiency. Ta.

Therefore, in conventional fuel injection control, when the load on the internal combustion engine is below a predetermined value, for example, when the throttle valve is fully open and the internal combustion engine speed is above a predetermined value, the fuel amount (g) is temporarily stopped. The government has carried out so-called fuel cuts in an effort to help improve the 11 issues listed above.

However, the following problems existed in implementing such fuel cuts. When normal fuel injection is performed, some of the injected fuel adheres to the intake pipe wall, intake valve, etc., but once the fuel injection ends, the adhered fuel remains vaporized until the start of the next fuel injection. Since it evaporates, it can be said that this adhesion and evaporation are roughly balanced. However, since fuel injection is of course not performed during the fuel cut, only the fuel that has already adhered to the engine is evaporated. Therefore, when the fuel cut is canceled and asynchronous fuel injection is performed depending on the operating condition of the internal combustion engine, the injected fuel initially adheres to the inside of the intake pipe, so the amount of fuel that enters the combustion chamber as an air-fuel mixture becomes insufficient, and in some cases It was thought that this could lead to a situation such as an engine stall.

Conventionally, in order to deal with this problem, when the operating state of the internal combustion engine reaches a predetermined state during a fuel cut, for example when the throttle valve is no longer fully open, the fuel cut is canceled and the asynchronous fuel Measures have been taken to ensure sufficient fuel is injected to the internal combustion engine. In addition, to solve the problem that the adhesion of fuel to intake pipe walls, intake valves, etc. depends on the temperature, Japanese Patent Laid-Open No. 55-49
537 and Special Publication No. 56-42739.

[Problems to be Solved by the Present Invention] Against the background of the prior art, the present invention is to solve the following problems. In the conventional internal combustion engine J5, in addition to the control described in the prior art section, the 'f1■ of the flywheel etc. is relatively large, so even if a fuel cut is performed, the rotational speed of the internal combustion engine decreases slowly. Therefore, after the internal combustion engine's rotation speed falls below the specified rotation speed and the fuel cut is canceled,
It was easy to set the rotational speed for canceling the fuel cut so that the output of the internal combustion engine would be restored before the engine failure occurred.

However, in recent years, in order to improve the responsiveness of internal combustion engines, the mass of the flywheel has been reduced, and in addition,
As the fuel cut is applied to lower engine speeds to improve fuel efficiency, when the throttle valve is fully open and the engine speed decreases, even if the fuel cut is canceled and asynchronous injection is performed, the internal combustion engine speed will decrease. A problem arose in that the engine speed dropped quickly and the engine stalled.

To deal with this problem, simply increasing the amount of fuel for asynchronous injection, which is not performed when canceling the fuel cut, would result in the throttle valve being fully open and the rotational speed decreasing, resulting in the proper amount of fuel being injected when canceling the fuel cut. Even if the amount of fuel injection is obtained, when the throttle valve is no longer fully open, that is, when the accelerator is pressed and the fuel cut is canceled, the main fuel injection amount has also increased, so fuel is supplied by asynchronous injection. becomes excessive, resulting in deterioration of fuel efficiency and ignition near the spark plug.
There were problems such as yellowing or deterioration of jJF gas.

[Object of the Invention] An object of the present invention is to solve the above problem and appropriately control the asynchronous fuel amount q1 that is performed when the fuel cut is canceled and the normal fuel injection side 911 is returned to. An object of the present invention is to provide a fuel injection control method for an internal combustion engine.

[Configuration of the Invention] As shown in FIG. 1, the configuration of the present invention, which has been made to achieve the above object, is to inject fuel in synchronization with the crank angle of the internal combustion engine using an amount of fuel corresponding to the load of the internal combustion engine. Step P1)
When the load of the internal combustion engine is below a predetermined value and the rotational speed of the internal combustion engine is above a predetermined rotational speed (step P2), the fuel injection is temporarily stopped and fuel cut is performed.Step P3
), when the operating state of the internal combustion engine becomes a predetermined state during the fuel cut (step Pa, step P5), asynchronous injection is performed with the predetermined fuel () and the fuel cut is canceled (step Ps) of the internal combustion engine. In the fuel injection control method for an internal combustion engine, the amount of fuel supplied to the internal combustion engine by the asynchronous injection is determined based on the operating state of the internal combustion engine at the time of canceling the fuel cut (step P7). The main point is how to control fuel injection.

[Operation of the Invention] Regarding the fuel injection control method for an internal combustion engine of the present invention having the above-mentioned configuration, the control procedure and its operation will be explained using the flowchart of FIG. According to the fuel injection control method for an internal combustion engine of the present invention, first, it is determined whether or not a fuel cut is being performed, for example, by determining the value of a flag (
Step Pa), if fuel cut is not implemented,
Paying attention to the operating state of the internal combustion engine, particularly its load, it is determined whether the load of the internal combustion engine is below a predetermined value and the rotational speed is above a predetermined rotational speed, so that a fuel cut can be carried out (step P2). ). Here, it is determined whether or not fuel cut can be implemented, for example, if the throttle valve is fully open and the number of revolutions of the internal combustion engine is higher than a predetermined number of revolutions, or based on the intake air ff1Q of the internal combustion engine and the number of revolutions N. This can be done under the condition that the required intake air mQ/N per revolution of the internal combustion engine is regarded as the load of the internal combustion engine, and that this value is less than a predetermined value. If the judgment in step P2 is rNOJ and the conditions for implementing fuel cut are not satisfied, the fuel injection control of the internal combustion engine is normal fuel injection control, that is, the fuel injection control determined based on the magnitude of the load on the internal combustion engine. Execute control to perform fuel injection at (step PI>).

On the other hand, in the judgment at step P2, it is decided whether or not to implement a fuel cut! 1 is established, a fuel cut is implemented to temporarily stop fuel injection to the internal combustion engine (step Ps
). In this way, when Burning One Cut came to be carried out,
In step P4, [Is fuel cut in progress?] ” judgment is r
YESJ, and then it is determined whether the operating state of the internal combustion engine is in a predetermined state (step Ps).

Here, the predetermined state means, for example, that the rotational speed of the internal combustion engine is below a predetermined number of rotations, that the vehicle speed is below a predetermined speed, or that the throttle valve is controlled from fully open to open and the internal combustion engine outputs This refers to an operating state in which a request for an increase has occurred, or in any case, the fuel cut cannot be continued any longer, and a determination is made as to whether or not such an operating state exists. Judgment at step P5 is "NO"
That is, unless the condition is such that the fuel cut cannot be continued, the fuel injection is stopped and the subsequent fuel cut is carried out as is (step Pa).

On the other hand, in step Ps, if it is determined that the operating state of the internal combustion engine is such that fuel cut cannot be continued, the fuel injection scheduler of the next asynchronous fuel injection is determined based on the operating state of the internal combustion engine at that time. (Step P7
), asynchronous fuel injection is performed using this fuel amount, and the fuel cut is canceled (step P6).

Therefore, according to the fuel injection control method for an internal combustion engine, when the vehicle is decelerating or is being operated at high speed without load, a fuel cut is performed to temporarily stop fuel injection, When the operating state of the internal combustion engine reaches a predetermined state, such as when the number of revolutions of the internal combustion engine falls below a predetermined number of revolutions due to implementation of a fuel cut, asynchronous fuel injection is performed using fuel determined based on the operating state of the internal combustion engine. , control is performed to cancel the fuel cut. As a result,
Depending on the operating state of the internal combustion engine when the fuel cut is canceled, the optimal fuel i can be inhaled as a mixture by asynchronous fuel injection immediately after combustion.

Here, the amount of fuel for non-double injection determined based on the operating state of the internal combustion engine is determined when the fuel cut is canceled when the throttle of the internal combustion engine is fully open and its rotational speed falls below a predetermined rotational speed. and when the fuel cut is canceled due to other conditions such as depressing the accelerator.
Preferably, it is determined separately. This is because the main fuel injection IJffi to be restarted is different under the two conditions (e) above. Furthermore, when the fuel cut is canceled under the former condition, determining the amount of fuel to be injected asynchronously based on the warm-up state of the internal combustion engine is sufficient to solve the problem of fuel adhesion near the intake pipe wall. You can deal with it by 1 degree.

On the other hand, among the conditions of the operating state of the internal combustion engine that would cancel the fuel cut, in the case of the latter condition, that is, a request for an increase in the output of the internal combustion engine has occurred, the normal Since the number of fuel injection pipes is also increased, if non-JIIi 1st stage fuel injection is performed based on the internal combustion engine's warm-water conditions, especially in low humidity, it may cause deterioration of exhaust gas or excessive changes in the internal combustion engine output torque. Sometimes I end up going crazy.

For this reason, even if the amount of fuel for asynchronous fuel injection that is performed when canceling the fuel cut due to the condition that a request for increased output of the internal combustion engine has arisen is determined based on the warm-up state of the internal combustion engine, the throttle valve is fully opened. Compared to the case where the fuel cut is canceled under the condition that the rotational speed of the internal combustion engine is equal to or lower than a predetermined rotational speed, the asynchronous fuel amount CFl ffl is determined based on a different correlation, and the asynchronous fuel t31@cut is performed.

[Example] Embodiments of the present invention will be described in detail below based on the drawings.

First, FIG. 2 is a schematic configuration diagram showing an internal combustion engine and its peripheral devices to which an embodiment of the present invention is applied together with a block diagram of an electronic control circuit.

1 is the internal combustion detector body, 2 is the piston, 3 is the spark plug, 4
is an exhaust manifold; 5 is an oxygen sensor provided in the exhaust manifold 4 to detect the residual oxygen concentration in the exhaust gas;
6 is a fuel injection valve that injects fuel into the intake air of the internal combustion engine main body 1; 7 is an intake manifold; 8 is an intake temperature sensor that detects the temperature of the intake air sent to the internal combustion engine main body 1; 9 is an internal combustion engine Water temperature sensor that detects cooling water temperature THW, 1
0 is a throttle valve, 11 is a throttle valve with a built-in idle switch and detects the opening of the throttle valve, 14 is a surge tank that absorbs the pulsation of intake air, 15
1 and 2 respectively represent an air flow meter that detects the amount of intake air.

16 is an Eve knife that outputs the high voltage necessary for ignition; 17 is a distributor that is distributed to the crankshaft (not shown) and distributes the high voltage generated by the Eve knife 16 to the spark plugs 3 of each cylinder; and 18 is a installed within the distributor 17;
19 is a rotation angle sensor that outputs 24 pulse signals for one revolution of the distributor 17, that is, two rotations of the crankshaft; 19 is a cylinder discrimination sensor that outputs one pulse signal for each revolution of the distributor 17; 20 is a cylinder discrimination sensor An electronic control circuit as a control means, 21 a key switch, 22 a key switch 2
1 represents a battery that supplies power to the electronic control circuit 20, 24 represents an on-vehicle gear stage, and 26 represents a vehicle speed sensor that detects the vehicle speed from the rotational speed of the output shaft of the transmission 24.

Furthermore, the internal configuration of the electronic control circuit 20 will be explained as follows.
In the figure, 3o inputs and executes the data output from each sensor according to the control program, and the central block is a single unit (CPU) that performs processing to control the operation of various devices, and 31 is a control Il program and Read-only memory (ROM) where initial data is stored
, 32 are the data input to the electronic control circuit 20 and the performance! χ
Random access memory (RAM) in which data necessary for &lI tin is temporarily read and written, 33 is CPU 3
A timer 36 which can read the real time on control at any time by 0 and has a register (hereinafter referred to as conveyor A) which generates an interrupt routine to the CPU 30 inside.
38 is an input boat that inputs signals from each sensor, 38 is an output boat that drives the evening knife 16' and the fuel injection valve 6 provided in each cylinder, and 39 is a common bus that interconnects each of the above elements. . The input boat 36 has an oxygen sensor length of 5. Intake temperature sensor 8. Water temperature sensor 9. an analog input section (not shown) that A/D converts and inputs the analog signal from the throttle sensor 111° air 70 meter 15;
An idle switch (not shown) in the throttle sensor 11 and a rotation angle sensor 18. It consists of a pulse input section (not shown) into which a pulse signal from the cylinder discrimination sensor 19 is input. In addition, when the output ports 1 to 38 receive a command to start fuel injection from the CPU 30, they output a control signal to open the fuel injection valve G.
It continues to be output from timer 3 until it receives a signal commanding the end of fuel injection (14).
This occurs when the fuel injection end time set by the CPU 30 on the conveyor A inside the conveyor 3 coincides with the actual time when the timer 33 continues to run. It is configured.

Next, regarding the fuel injection method of this embodiment, we will first explain the basic control routine of the internal combustion engine using the flowchart of FIG. 3, and then control the start of normal fuel injection. About C△ interrupt routine Figure 4 (A)
Following the flowchart, FIG. 4 (
According to the flowchart in B), and furthermore, according to the flowchart in FIG. 5 regarding the main routine for performing fuel cut and asynchronous fuel injection Lulili 1, the asynchronous fuel injection time is finally determined based on the cooling water temperature of the internal combustion engine 1. The asynchronous fuel injection control routine will be sequentially explained with reference to the flowchart of FIG.

As shown in FIG. 3, the basic control routine of the internal combustion engine 1 is started when the key switch 21 is turned on.
First, initialization such as clearing the internal register of the CPU 30 is performed (step 100), and then the initial value of data used to control the internal combustion engine 1 is set, for example, the flag FCUT indicating that the fuel cut is in progress is set to 0. , a flag FMT indicating the difference in equipment between a manual transmission and an automatic transmission used in the second embodiment described later is set to 1 (
Step 1o5). Next, the operating state of the internal combustion engine 1, for example, the air flow meter 151, the rotation angle sensor 18, and the water temperature pin 1.
Performs processing to read signals from No. 9 etc. (Step 1)
10) From the various data read in this way, the internal combustion engine 1
A process is performed to calculate various quantities that are essential for controlling the internal combustion engine 1, such as the intake air LmQ, the rotational speed N, or the load Q/N (step 120). Hereinafter, based on the various quantities obtained in step 120, well-known ignition timing control (step 13
0) and fuel injection control (step 140) are performed. After completing step 140, the process proceeds to step 110.
Return to and repeat the above process.

Note that the control of the fuel injection amount here is usually performed by feedback control of the air-fuel ratio, and the load Q of the internal combustion engine 1 is
/N, the fuel injection amount is corrected by J: based on various correction terms such as the air-fuel ratio feedback correction coefficient, and synchronous injection is performed twice per revolution of the internal combustion engine 1. However, in place of air-fuel ratio feedback control, oven-controlled DO or other well-known methods such as IJ that increase fuel enrichment in response to various operating demands of the internal combustion engine 1 are used.
Sometimes 1ull is performed. including ignition timing control,
The basic control of these internal combustion engines is well known, so a description thereof will be omitted.

Next, the 30' CΔ interrupt routine for controlling the start of fuel injection will be described using the flowchart of FIG. 4(A). This control routine uses a crank angle of 30' CA.
A pulse inputted from the rotation angle sensor 18 at fH causes a starting force as a routine including Vl, and first step 150 is performed.
The time when a pulse is input from the cylinder discrimination sensor 19 is set to 0, and each time a pulse is input from the rotation angle sensor 18, the pulse is input from the rotation angle sensor 18.
While the count is repeatedly counted up from 24 to 24, the value of a counter (not shown) is known and the current crank angle is determined. In the following step 160, step 15
Based on the crank angle determined at 0, it is determined whether the intake stroke of the first cylinder or the sixth cylinder is about to start. This is twice per revolution of internal combustion (1 lf of fuel)
Since the current stroke of the internal combustion engine is a stroke in which fuel injection is performed in synchronization with the rotation of the internal combustion engine, that is, the first stroke.
Alternatively, it is determined whether the crank angle is at the start of the intake stroke of the sixth cylinder. Step 16
If the judgment at 0 is l-N OJ, change the fuel injection to 2r.
As there is no need to interrupt i-J', the process returns 122 digits to RTN and ends this interrupt routine. If the determination at step 160 is rYEsJ, the process proceeds to step 170, where it is determined whether the flag FCUT=O. Flag FCUT indicates whether or not to implement fuel cut1
° flag, whose first value is 1'J] The I shift is O, and is set according to the operating state of the internal combustion engine 1 in the main routine that will be described later with reference to FIG. now,
If the value of flag FCUT is 1, then the fuel level is 1~
Assuming that it is being executed, the process returns to RTN1); t4:l and ends the tree v1 inclusion routine.

On the other hand, if the flag FCUT=O, the process proceeds from step 170 to restep 180, outputs a command signal to the output port 38 to start fuel injection, and burns [injector 6
Open the valve. In the following step 19o, the fuel injection amount (fuel injection time τ) determined in step 140 in FIG.
is added to the real time Tr read from the timer 33,
That is, a process is performed in which the fuel injection end time [1] is set in conveyor 8 in the timer 33. After step 190 is completed, the process can be handled as RTN, and this interrupt routine ends.

In the conveyor A in the timer 33, the set fuel injection end time t1 and the actual control time 1i! ]Tr is continued to be compared, and when the control real time r reaches the fuel injection rJJ end time t1, an interrupt request is issued to the CPU 30, and a coincidence interrupt routine is activated for the conveyor. This is the routine shown in the flowchart of FIG. 4(B). In step 195, a signal to end fuel injection is output to the output port 38, the fuel injection valve 6 is closed, and the fuel injection valve 6 is closed. end the shooting. Immediately after the processing in step 195 is completed, RTNI is entered, and the match interrupt routine for this conveyor is ended.

The 11λ essential points regarding the control of the fuel 1 injection rule have been explained above.Next, the main routine for controlling fuel cut and asynchronous fuel injection will be explained based on the flowchart of FIG. This routine is based on the fuel injection control υ11 shown in Figure 3.
(Step 140) is repeatedly executed, and first, the control is divided into three types depending on each decision condition in Steps 200 to 240. Steps 200 to 240 in area D1 of FIG.
To explain each determination, each step is step 200: flag FCLJ indicating execution of fuel cut 1~.
Determining whether T (initial value '98) is 1, step 210: The rotational speed N of the internal combustion engine 1 is 1500+.
1) Judgment whether n1 is 1 or 1, step 220
: Determining whether the rotational speed N of the internal combustion engine 1 is 17QQrpm or less, Step 230 : Whether or not the idle switch in the throttle sensor 11 is turned off, that is, the throttle valve 10 is closed or not. Step 240: Similarly, it is determined whether the idle switch is on, that is, whether the throttle valve 1Q is fully open.

In addition, the three branches are as follows: (a) In step 250, a signal to start fuel injection is output to the output port 38 to open the fuel injection valve, and in step 26
0 is the end time of asynchronous fuel injection (determine 0 and set it to conveyor A in the timer 33, set flag FCUT to 0 to cancel the fuel cut in step 270, and move 1 to NEXT. To end the main routine: (l) Go to NEXT without performing any processing; To end the main routine, (C) Processing in step 280, that is, setting the flag "CUT to 1." This is the case when the main routine is terminated by proceeding to NEXT after performing .In the case of (a),
The fuel injection is terminated by the above-mentioned conveyor A coincidence interrupt routine (
(shown in the flowchart of FIG. 4(B)).

Further, the details of the process of step 260 will be described in detail.

Therefore, to summarize the control of the main routine, the flag F CU T b < 1 (, the rotational speed N of the internal combustion engine 1
is below 170 rpm, or when the rotational speed N of the internal combustion engine 1 exceeds 1700 rpm but the idle switch is off, the load on the internal combustion engine 1 is assumed to be sufficiently high, and the main routine is terminated without performing any fuel cut or other operations. Step 200-Step 220-NEXT or Step 200-Step 220-Step 240-NEXT
>. On the other hand, if the flag FCUT is 1 (and its rotational speed N
If the engine speed exceeds 1700 rpIIl and the idle switch is on, the throttle valve 10 is fully open and the rotational speed is sufficiently high, so the fuel consumption is low.
It is determined that ~ should be the actual size, the flag FCUT is set to 1, and the main routine is ended (step 200 - step 220 - step 240 - step 280 - NEX
T). In this case, the normal fuel injection synchronized with the rotation of the internal combustion engine 1 will not be performed and the fuel cut will be performed due to the judgment in step 170 in the 30° CA interrupt routine already explained using the flowchart in FIG. 4 (A>). It will be implemented.

Next, after the flag FCUT becomes 1, if the rotational speed N of the internal combustion engine 1 is 150 rpm or higher and the idle switch remains on, it is assumed that the conditions for implementing the fuel cut continue, and no action is taken and the main operation is continued. End the routine (step 200-step 210-step 230-NEX
T) , when the rotational speed N of the internal combustion engine 1301 gradually decreases to less than 1500 rpm, or 1500 rpm.
When the idle switch is no longer on even if the engine speed is above rpm, that is, when a request for an increase in the output of the internal combustion engine 1 occurs, the condition for implementing a fuel cut is no longer present, and asynchronous fuel injection is performed in step 250. Flag FCU to perform 260 processing and cancel fuel 11 cut.
The process of step 270 is performed to set T to O, and the main routine is terminated (steps 200 to 21).
0-Step 250 to Step 270-NEXT,
or step 200-step 210-step 23
0-Step 250 Step 270-NEXT)
.

Therefore, by executing this main routine, fuel injection is normally performed in synchronization with the crank angle of the internal combustion engine 1 with an amount of fuel corresponding to the load on the internal combustion engine 1, and the load on the internal combustion engine 1 is lower than or equal to a predetermined value. When this happens, here, when the rotational speed of the internal combustion stage 1 exceeds 1700 rpm and the idle switch is on (throttle valve 10 fully open), fuel injection is temporarily stopped and fuel is cut. When the operating state of the internal combustion engine 1 becomes a predetermined state during the cut, here, when the rotation speed of the internal combustion engine 1 becomes less than 150 Orpm or the idle switch is turned off, the asynchronous operation is performed with a predetermined fuel amount. Control is performed to cancel the fuel cut while performing the injection.

Next, a routine for determining the asynchronous fuel injection ffi in step 260 in FIG. 5 by setting the fuel injection end time [0] according to flow 11-1- in FIG. 6 will be described.

This control routine first determines whether or not the idle switch in the throttle sensor 11 is on in step 300, and then determines the temperature of the cooling water detected by the water temperature sensor 9, which indicates the warm-up state of the internal combustion engine 1. The range of TI-IW is determined. When the determination in step 300 is "N○", that is, when it is determined that the idle switch is not on and the throttle valve 10 is no longer fully closed, and the throttle valve is fully closed (the idle switch is on), When the internal combustion engine 1 has been sufficiently warmed up and the cooling water temperature T)-IW is 706C or higher, the process moves to step 320, and a process is performed to set the asynchronous fuel injection time T- to 3m5eC. It will be done. On the other hand, when the idle switch is on and the water temperature TI-IW is greater than or equal to O0C and less than 70'C, the process proceeds to step 330, and the asynchronous fuel injection time T' is set to T=
=8-THW/14 is calculated and set. Similarly, when the idle switch is on and the water temperature T1-IW is 00C)1, the process moves to step 340, and the asynchronous fuel injection time T- is set to 8 m5e.
Processing to set the value to c is performed.

Step 320 above. Step 330 or Step 3
40, the process proceeds to step 350.
The timer 33 sets the current time T as the real time for control purposes.
A process of reading r is performed. In the following step 360, the asynchronous fuel injection time T- set in any step from step 320 to step 3/lo is added to the current time 7'r read in step 350, and a process for determining the fuel injection end time (O) is performed. is carried out, and in the next step 370, processing is performed to set the fuel injection end times t and o in the conveyor Δ in the timer 33, and the water control routine is completed by setting NEXT to 1.

Therefore, in this embodiment configured as above,
When the operating state of the internal combustion engine 1 becomes such that it is no longer possible to continue the fuel cut while the fuel cut is being carried out, the fuel cut is canceled and the following non-identical 11rI fuel injection is carried out.

<A) The throttle valve 10 of the internal combustion engine 1 is still fully closed and its rotational speed is at a predetermined rotational speed (here, 1500 rpm).
pm) and the fuel cut is canceled, asynchronous fuel injection is performed using a fuel amount determined based on the cooling water water gTHW indicating the warm-up state of the internal combustion engine. The asynchronous m-material injection time in this case is shown in the actual rAs in FIG.

(B) When the throttle valve 10 of the internal combustion engine 1 is no longer fully open, that is, when a request for an increase in the output of the internal combustion engine 1 occurs and the fuel cut is canceled, the internal combustion engine 1 remains warm at a predetermined level regardless of the state. Here, the fuel injection time is 3 m.
Asynchronous fuel injection is performed for the amount of fuel (corresponding to 5ec). The asynchronous fuel injection time in this case is shown by the broken line R in FIG.

Therefore, according to this embodiment, when the internal combustion engine 1311!111 performs a fuel cut depending on its load condition,
When there is no request for an increase in the output of the internal combustion engine 1 and the rotational speed simply falls below a predetermined rotational speed, asynchronous fuel injection is carried out according to the warm-up state of the internal combustion engine 1 and the fuel cut is canceled, so that the engine is not involved in combustion. This solves the problem that the amount of fuel contained in the air-fuel mixture immediately increases and recovers, leading to an unexpected decrease in the output of the internal combustion engine 1. On the other hand, when a request for an increase in output occurs, a predetermined asynchronous fuel injection is performed. As a result, it is possible to fully bring out the effects of improving fuel efficiency and reducing catalyst temperature decay due to fuel cut.

Further, when the throttle valve 10 is no longer fully closed during the implementation of the fuel cut, that is, when the combustion cutoff 1~ is canceled due to a request for an increase in the output of the internal combustion engine 1, the asynchronous fuel injection amount is set to a constant amount. Therefore, in this case, the problems of deterioration of exhaust gas conditions and deterioration of drive feeling due to excessive changes in output torque, which have conventionally been observed at low temperatures, have been sufficiently solved.

Next, a second embodiment of the present invention will be described.

FIG. 8 is a flowchart, not showing the main routine of the second embodiment, and corresponds to the flowchart of the main routine shown in FIG. 5 of the first embodiment. Other controls in the second embodiment (1) The basic control of the internal combustion engine, the 30° CΔ interrupt routine, etc. are all the same as the control in the first embodiment.

This main routine is executed as part of the fuel injection control routine, and first, as shown in FIG.
The process starts with a determination as to whether the flag FMT is 1 or not. The flags F to I are determined by the transmission 24 mounted on the vehicle and its state, and are set to an initial value of 1 in step 105 of the flowchart of FIG. The determination at step 400 is of course rYEsJ (FMT
-1), the process proceeds to step 405 and the transmission 2
The state of the neutral switch NSW No. 4 is read to determine whether it is off or not.

Neutral switch NSW is not particularly shown, but is provided in the white shift gearbox, and switch 1 becomes active when switch 24 is in the parking range or neutral range. Note that when a manual transmission is installed, there is no neutral switch, and the input corresponding to the neural switch NSW is always in the on state. Further, 408 is a step for setting the flag FMT to O. Therefore, if the main routine of this embodiment is used in a vehicle with a separate manual transmission,
Processing always proceeds in the order of steps 400-405-410. On the other hand, in the case of a vehicle with an automatic transmission, steps 400 to 405 are performed until the internal combustion engine 1 has started and the transmission 24 is changed from the parking range or the neutral range to the driving range, etc.
Immediately after the change in the shift position of the transmission 24 is performed, the process proceeds to step 410.
- Step 405 - Step 408 - Step 410 are proceeded to set the flag FMT to zero, and thereafter the process proceeds to Step 400 - Step 410.

Judgment is made within the area Dz enclosed by the dashed line in Figure 87.
Steps 410 to 470 are steps 200 to 24 shown in FIG. 5 of the first embodiment.
This almost corresponds to the judgment made in step 0 (region D1 in the same figure), with the addition of judgments based on the state of the transmission, etc. (steps 450 and 46o). Note that steps 480 and 490 in FIG. Step 500. Steps 510 each correspond to steps 250.. of FIG. Step 260. Step 270. Since this corresponds to step 280, detailed explanation will be omitted.

Each step in the area D2 is set to step 410: a flag F indicating that fuel cut is in progress.
A step of determining whether CUT (initial value zero) is 1, step 420: The rotation speed N of the internal combustion engine 1 is 150 Orp.
Step 430: determining whether or not the rotation speed of the internal combustion engine 1 is less than 170 O
A step of determining whether or not the rpm is below, Step 440: Internal combustion 1jIr! A1f7) Load, that is, intake air ff1Q/N per rotation is 0.15 ft/R
Step 450: Determine whether the same < Q/N is less than 0.1 t/R. Step 460: The vehicle once After driving in a mode other than the barking range or the neutral range, the value of the flag FMT determines whether the on-board transmission 24 is an automatic transmission (FMT-0) or a manual transmission (FMT-1). Step of making a judgment, Step 470: A step of making a judgment as to whether the vehicle speed detected by the vehicle speed hinge 26 is 5 Km/l-1 or less.

Therefore, to summarize the control of this main routine, (I>Flag FCUT is not 1 and the rotation speed N of the internal combustion engine 1 is below 1700 rpm JX, or when the internal combustion engine 1
Although the rotation speed N of the internal combustion engine 1 exceeds 170 Orpm,
The intake air ff1Q/N per revolution is 0.1 ft/R
In the above case, the load on internal combustion (function 1) is considered to be sufficiently high, and the main routine is terminated without performing a fuel cut or the like.
Step 410-Stella 7430-N EXT mata l;
TS? 7410-Stella 1430-Step 450
- NEX Ding).

(n) On the other hand, when the flag FCUT is not 1 and the respective rotation speed N exceeds 1700 rpm, and the load Q/N of the internal combustion engine 1 is less than 0.11/R, the internal combustion engine Since the load on the engine is sufficiently small and the rotational speed is sufficiently high, it is determined that a fuel cut should be carried out, and the flag FCUT is set to 1.
(step 510) and ends the main routine (step 410 - step 430 - step 450 -
Step 510-NEXT>. In this case, the normal fuel injection synchronized with the rotation of the internal combustion engine 1 is not performed due to the determination in step 170 in the 30°C A interrupt routine explained using the flowchart in FIG. 4 (A> in the first embodiment). , fuel cuts will be implemented.

(I[[)Next, after the flag FCUT becomes 1, if the rotation speed of the internal combustion engine 1 is 1500 rpm or more and its load Q/N is less than 0.15 t/R, fuel cut is still continued. Assuming that the necessary conditions are met, nothing is done (the flag FCUT remains zero), and the main routine ends (step 410 - sub 420 - Stella 7).
440-N[EXT>.

(IV) On the other hand, even after the flag FCUT becomes 1 and the rotation speed N of the internal combustion engine 1 is less than 150 rpm, the vehicle speed is 5 km/h with the flag FMT = 1 (equipped with a manual transmission). exceeds.

Sometimes the conditions for continuing fuel 7J are no longer present,
Since there is no need to perform asynchronous fuel injection, the lil'j of the flag FCUT is simply set to 0 in step 500, and the main routine ends (step 410-step 4).
20-Swipe 460-Step 470-Step 5
00-NEXT). This means that even if the rotational speed of the internal combustion engine 1 is less than the predetermined rotational speed (1500 rpm in this case), the vehicle is equipped with a manual transmission and the vehicle speed is 5K.
This control is based on the fact that when the internal combustion engine 1 exceeds m/l-1, there is a small possibility that the internal combustion engine 1 will misfire and lead to entrances 1 to 1. In this case, it is better to simply cancel the fuel 1 cut without performing asynchronous fuel injection, and gradually increase the output through normal fuel injection, without the excessive change in output 1~r3. This is because the drive feeling becomes better.

(V) Flag FCUT=1 and the above (Iff)
In addition, under conditions other than those described in NV), the process is performed in step 4.
Go below 80 and start asynchronous fuel injection Step 4
80), asynchronous fuel injection control routine (step 490 in FIG.
), and in step 500 the flag FCUT is
After setting 0 to O, the main routine ends.

Next, control of the asynchronous fuel injection motherboard in this embodiment will be explained. The main routine of determining the asynchronous fuel injection end time to and setting it on the conveyor A in the timer 33 performed in step 490 of FIG. 8 already explained in the second embodiment is as shown in FIG. 6 in the first embodiment. The asynchronous fuel injection routine is the same as the asynchronous fuel injection routine described using the flowchart in FIG. In the second embodiment, in step 300 of the first embodiment, is the idle switch on? ” instead of determining “The load Q/N of internal combustion engine 1 is 0.
．． Is it less than 15 tate/R? ” judgment is made. This is because in the first embodiment, the request for an increase in the output of the internal combustion engine 1 was determined based on the state of the idle switch.
In the second embodiment, the determination is made based on the value Q/N representing the Q load of the internal combustion engine 1. Note that the asynchronous fuel injection control routine is the same as the first embodiment except for this point.

Therefore, by executing the main routine described above, the same control as in the first embodiment is performed. As a result, according to this embodiment, in addition to the effects of the first embodiment, without changing the control program, if the vehicle speed is 5 km/h or more when the vehicle-mounted transmission 24 is in manual gear shift mode, Control will be executed to prevent asynchronous fuel injection when the fuel cut is canceled, further improving the drive feeling.

In addition, 1st. In the second embodiment, the amount of fuel for asynchronous fuel injection performed when there is a request to increase the output of the internal combustion engine 1 during fuel cut is 1 fl of the cooling water of the internal combustion engine 1.
Although it is assumed that the THW is constant regardless of THW (dashed line R in Figure 7), even in this case, if the warm-up of the internal combustion engine 1 is insufficient, it is better to slightly increase the asynchronous fuel injection time. It has been confirmed that the output rises better, as shown by the dashed line Q in Figure 7, when the humidity is low (here below 10°C).
Slightly increasing the asynchronous fuel injection tJJffi at
This is suitable for application of the present invention.

Although several embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and can be implemented in various forms without departing from the gist of the present invention. Of course.

[Advantageous Effects of the Invention 1] As detailed above, according to the fuel injection control method for an internal combustion engine of the present invention, a fuel cut is performed when the load of the internal combustion engine is below a predetermined value and above a predetermined rotation speed. When you are,
If the operating state of the internal combustion engine reaches a predetermined state where the fuel cut can no longer be continued, the amount of fuel determined individually depending on the operating state of the internal combustion engine when canceling the fuel cut is determined. Control is performed to perform non-domain fuel injection (0) and to cancel the fuel cut.

Therefore, when a condition for canceling the fuel cut is established while the fuel cut is in progress, the amount of fuel for asynchronous injection 04 is determined based on the condition, so that the optimal asynchronous fuel injection for the operating condition of the internal combustion engine is executed. Qin can have excellent effects. When the throttle valve of the internal combustion engine is fully opened and the rotational speed decreases during a fuel cut to cancel the fuel cut, for example, if the internal combustion engine is cooled [1
If the amount of asynchronous fuel injection is determined based on the warm-up condition such as water temperature, the amount of fuel contained in the air-fuel mixture involved in combustion will immediately increase and recover to the required level by asynchronous fuel injection, which will improve the internal combustion engine's performance. There is no need to worry about an unexpected drop in output, and there is no need to sacrifice the responsiveness of the internal combustion engine. On the other hand, there is a demand for an increase in the internal combustion engine
If the asynchronous fuel injection (2) is kept low when the 1~ is released, problems such as poor fuel efficiency, smoldering, and deterioration of exhaust gas will not occur.

As a result, the fuel can be cut sufficiently, and the effects of reducing the temperature of the catalyst and improving fuel efficiency due to the fuel cut 1 can be fully utilized.

[Brief explanation of drawings]

Fig. 1 is a basic diagram of the present invention, and Fig. 2 is an electronic control 21 for an internal combustion engine and its peripheral devices to which an embodiment of the present invention is applied.
Figure 3 is a flowchart showing the basic control routine of the internal combustion engine used in the first and second embodiments;
A) is 30” OA which also controls the start of fuel injection DI+
FIG. 4(B) is a flowchart showing the interrupt routine, and FIG. 4(B) is a flowchart showing the conveyor A coincidence interrupt routine for controlling the end of fuel injection ([1]. FIG. 5 is a flowchart showing the main routine of the first embodiment. FIG. 6 is a flowchart showing the asynchronous fuel injection control routine,
FIG. 7 is a map showing the relationship between the cooling water temperature THW of the internal combustion engine and the non-identical fuel injection product (time) T', and FIG. 8 is a flowchart showing the main routine of the second embodiment. be. 1...Internal combustion engine 6...Fuel injection valve 9...Water temperature sensor 11...Throttle sensor 15...Air flow meter 18...Rotation angle range 20...Electronic control circuit 24...Speed change Machine 26...Vehicle speed indicator 30...CPU Figure 1 Figure 3 Figure 4 (A)' (B) Figure 6 Figure 7

Claims (1)

[Claims] 1. Fuel injection is performed in synchronization with the crank angle of the internal combustion engine with an amount of fuel corresponding to the load of the internal combustion engine, and when the load of the internal combustion engine is below a predetermined value and the rotational speed of the internal combustion engine is When the rotation speed exceeds a predetermined number of revolutions, the fuel injection is temporarily stopped to perform a fuel cut, and when the operating state of the internal combustion engine reaches a predetermined state during the fuel cut, asynchronous injection is performed with a predetermined amount of fuel. In the fuel injection control method for an internal combustion engine, the amount of fuel supplied to the internal combustion engine by the asynchronous injection is determined based on the operating state of the internal combustion engine when the fuel cut is canceled. A fuel injection control method for an internal combustion engine featuring features. 2 The amount of fuel injected to the internal combustion engine by the asynchronous injection is determined differently depending on whether the fuel cut is canceled due to the rotational speed of the internal combustion engine falling below a predetermined rotational speed or due to other operating conditions. A fuel injection control method for an internal combustion engine as defined in claim 1. 3. The amount of fuel supplied to the internal combustion engine by the asynchronous injection is determined based on the warm-up state of the internal combustion engine when the rotational speed of the internal combustion engine falls below a predetermined rotational speed and the fuel cut is canceled. A fuel injection control method for an internal combustion engine according to claim 1.