JPS59206627A - Method of electronically controlled fuel injection in internal-combustion engine - Google Patents

Abstract

PURPOSE:To enable a fuel supply depending on the accelerated state of an engine, by detecting the accelerated state from the rate of change in that of change in the load upon the engine and making a reference value small at the initial stage of the acceleration and large after the initial stage. CONSTITUTION:A throttle sensor 6 detects the time of opening of a throttle valve entirely closed. A reference value, which increases with the lapse of time from the detected time, is determined. A fuel increase value for the acceleration of an engine is determined from the reference value and the quantity of change in that of change in the load upon the engine. This results in enabling a fuel supply depending on the accelerated state of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronically controlled fuel injection method for an internal combustion engine, and particularly relates to an electronically controlled fuel injection method for an internal combustion engine. :Relates to an electronically controlled fuel injection method for an internal combustion engine that performs synchronous injection and asynchronous injection that injects fuel asynchronously with the crank angle during acceleration.

Conventionally, a fuel injection valve is provided for each cylinder so as to protrude into the intake manifold, and a microcomputer processes the signals sent from each stroke sensor to determine all engine operating conditions and injects fuel according to the operating condition. A fuel injection method for injecting fuel is known. In this fuel injection method,
Synchronous injection, in which fuel is injected to all cylinders simultaneously or to each specific cylinder at a predetermined period, and asynchronous injection, in which all fuel is injected during acceleration, regardless of the synchronous injection, are performed. Synchronous injection uses engine load (
The basic fuel injection pulse width is calculated according to the intake pipe pressure or the amount of intake air per engine revolution) and the engine speed, and this basic fuel injection pulse width is used to calculate the partial lean correction coefficient, feedback correction coefficient, cooling water temperature, etc. The fuel injection pulse width is determined by correcting it using another correction coefficient that remains constant depending on the crank angle, and the fuel injection valve is opened for a time corresponding to the fuel injection pulse width at a predetermined crank angle to inject fuel. . In addition, asynchronous injection during acceleration is performed to improve engine response during acceleration, etc.A linear throttle sensor that outputs a voltage that is a linear function of the throttle opening is installed, and the output voltage The system injects fuel independently of synchronous injection according to the rate of change in engine load and the rate of change in engine load. According to this asynchronous single injection, the air-fuel ratio during the transient period at the beginning of acceleration is corrected, so that drivability and exhaust gas purification rate are improved.

However, with this conventional fuel injection method, when accelerating from the load range, the intake sound pressure and intake air are reduced.

The amount increases significantly in response to a slight increase in throttle opening, and the air-fuel ratio during acceleration is adjusted appropriately depending on the acceleration state.
There was a problem that I couldn't have sex.

The present invention has been made to solve all of the above problems, and by appropriately controlling the air-fuel ratio during acceleration according to the acceleration state, the dry cleanability and 1F-scum purification rate during acceleration are improved. The overall purpose is to provide an electronically controlled fuel injection method for an internal combustion engine.

Rontono 1. In an electronically controlled fuel injection method for an internal combustion engine in which fuel is fully injected asynchronously with the crank angle when the valve is opened and the rate of change in engine load is a positive value, the reference point is when the throttle valve is opened from a fully closed state. In addition to determining the time, a reference value that increases according to the time is determined, and the rate of change of the engine load is H1.
When the rate of change of the engine load exceeds the reference value, the first fuel is injected, and the second fuel is It is designed to inject fuel. The engine load can be detected from intake sound pressure, intake air amount per engine revolution, throttle opening, fuel injection pulse 1llii1, and the like. Further, in the above configuration, the first amount is a predetermined amount, and the second amount is a predetermined amount.
It is preferable to increase the amount according to the rate of change in the engine load. It is preferable that the reference value be further increased when the engine speed is below a predetermined value.

According to the above configuration of the present invention, the acceleration state is detected based on the rate of change in the rate of change of the engine load, and the reference value at the initial stage of acceleration is increased. The number of times of asynchronous injection increases, and a unique effect 5 is obtained in that an appropriate air-fuel ratio can be obtained depending on the acceleration state.

Based on FIG. 1, an example of an internal combustion engine to which the present invention is applied will be explained in detail. On the downstream side of the air conditioner (not shown), there is an intake temperature sensor 2 which detects the temperature of the intake air and outputs the full intake temperature signal. *The throttle valve 4 is rearranged at t+, and the throttle valve 4e is interlocked with the throttle valve 4e.
On slot/L when the throttle valve is fully closed.

Throttle switch 6i that turns off when the valve opens
'i taken (t rj taken. Throttle valve 4 -F
A surge tank 8 is provided at the flow end 1j, and this -f-
-) Pressure car sensor 10 that detects the intake pipe pressure saw of the throttle switch on pink 8 and outputs an intake pressure signal
Force X is installed. The surge tank 8 is connected to the engine cDem'M through the intake manifold 12' ().
It is connected to 14. This intake manifold 1
2, a fuel injection valve 16 is attached to each cylinder. The combustion chamber 14 of the engine is connected to a catalytic converter (not shown) that is fully filled with a three-way catalyst via an exhaust manifold.
is communicated with. 1. A water temperature sensor 20 that detects the engine cooling water temperature and outputs a water temperature signal is attached to the engine block. A tip of a spark plug 22 projects into the combustion chamber 14 of the engine, and a distributor 24 is connected to the spark plug 22. The distributor 24 is provided with a cylinder discrimination sensor 26 and an engine rotation speed sensor 28, each of which includes a big amplifier fixed to the distributor housing and a signal rotor fixed to the distributor shaft.

The cylinder discrimination sensor 26 sends a cylinder discrimination signal every 720° CA to a control circuit 3 composed of a microcomputer or the like.
0, and the engine rotation speed sensor 28 is set to 30°, for example.
A crank angle signal is output to the total control circuit 30 for each CA. The distributor 24 is connected to the igniter 32. Note that 34 is an 02 sensor that detects residual acidity in exhaust gas and outputs an air-fuel ratio signal.

As shown in FIG. 2, the control circuit 30 includes a central processing unit (C
PU) 36, read-only memory (ROM) 38, random access memory (RAM) 40, backup RAM (BU-4AM) 42, input/output board (Ilo) 44,
It is composed of an analog-to-digital converter (80C) 46 and buses such as a data bus and a control bus that connect these converters. l1044 contains a cylinder discrimination signal,
A crank angle signal, an air-fuel ratio signal, and a throttle signal output from the throttle switch 6 are input, and the drive circuit controls all valves to control the fuel injection signal that controls the entire opening/closing time of the fuel injection valve 16 and the on/off time of the igniter 320. An ignition signal is output. In addition, an intake pipe pressure signal, an intake air temperature signal, and a water temperature signal are input to the ADC 46 and converted into digital signals.

The above crank angle signal is passed through a waveform shaping circuit to form a digital signal representing the engine speed. The cylinder discrimination signal is input to l1044 and converted into a digital signal in the same manner as above. This cylinder discrimination signal is used together with the crank angle signal to form an interrupt request signal, a fuel injection start signal, a cylinder discrimination signal, etc. for basic fuel injection pulse width calculation.

The on/off signal from the throttle switch 6 is l10.
4'40 is sent to a predetermined bit position and temporarily stored. In addition, a well-known fuel injection control circuit including a presettable counter, a register, etc. is provided in the Ilo 44, and an injection pulse signal having the pulse width is determined from binary data regarding the injection pulse width sent from the CPU 36. The injection pulse signals are input to all the fuel injection valves 16 sequentially or simultaneously to energize the injection valves.

As a result, falcon fuel is injected synchronously or asynchronously according to the pulse width of the injection pulse signal. The Ro'M38 contains a main processing routine program, an interrupt processing routine program for calculating fuel injection pulse width, an interrupt processing routine program for calculating coefficients such as partial lean correction coefficients, and other programs necessary for each of the above calculation processes. Various data are stored in advance. Also, ROM
3B stores in advance data regarding the first and second cylinders for asynchronous fuel injection and the map shown in FIG. This map defines a reference value for the count value C of a counter for counting the time from the point in time when the throttle valve in the fully closed state is opened, and as the count value C increases, the reference value It is determined that the increase in size increases in stages.

Next, the asynchronous injection routine of the present invention will be explained using FIGS. 4 to 7. Note that the synchronous injection routine and the like are the same as the conventional ones, so a complete explanation will be omitted. FIG. 4 shows the main routine. In step 82, it is determined whether the throttle switch 6 is off or not, that is, whether the throttle valve is open, based on the throttle signal.

If the throttle switch is on, the program proceeds to a routine after resetting 7 lags XLL'f in step S3, and if the throttle switch is off, it is determined whether the flag XLL, which is set when the throttle switch is off, has been reset. If flag XLL is set, proceed to the next routine; if 7lag XLL is reset,
That is, if the throttle switch was turned on last time, the counter is cleared in step $6, and the counter is cleared in step S8.
Set it to 7 lugs XL L'. Therefore, the counter is constantly counted and is cleared when the throttle switch changes from on to off. In other words, is the cuff time based on the time when the throttle switch changes from on to off, and therefore the time when the throttle valve changes from fully closed to open? It will be counted.

FIG. 5 shows a routine for incrementing a counter at predetermined intervals, and in this embodiment, step 3
12, the count value C of the counter is incremented every 4 m3ec. Note that in step SIO and step 814, the count value of the counter (4
5 By limiting to the maximum value MAX, the counter flow is completely prevented.

FIG. 6 shows a reference value processing routine for changing the reference value according to the engine speed NK. Step S
At 9, the engine speed iNE reaches a predetermined value (for example, 18
00r, p, m) or higher, and the engine speed is r.
Step S only when r is less than a predetermined value], set the reference value at 1 and then set a positive predetermined value A? Add the reference value L (i=increase.

This is to prevent all asynchronous injection from occurring in the low engine speed range, since the ripples in the intake pipe pressure due to engine speed fluctuations are large even in a steady running state, without being in a transient state. As a result, the reference value ■ is increased according to the time from the time when the throttle switch changes from on to off, as shown in Fig. 3, and is further increased in the low engine speed region.
is stored in a predetermined location.

FIG. 7 shows a routine for determining the acceleration state and calculating the pulse width TAU of the fuel injection signal in asynchronous injection. This routine is a routine that is interrupted when the intake pipe pressure PMOAD conversion is completed. In addition, the intake pipe pressure P
MOAD conversion is performed at 12 mft. Step S16 (Then, the current intake pipe pressure PMn
and the intake pipe pressure PMn before the previous time, that is, 24 m5ec ago.
, -2, and calculate the amount of change in intake pipe pressure during 24 msec, that is, the rate of change ΔPMn. This rate of change ΔPMn is equivalent to the first-order differential of the intake pipe pressure PM with respect to time. In step 818, the current rate of change ΔPMn and the previous rate of change Δp, that is, 12 m5ec ago, are determined.
1''IA-1, and calculate the amount of change in the rate of change during 12 m5ec, that is, the rate of change ΔΔPM in the rate of change in intake pipe pressure.
Calculate n'i. This rate of change ΔΔPMn is equivalent to a second-order differential with respect to time.

Therefore, in the following, the rate of change J, PMn, and ΔΔPMni will be defined as first-order differential values and second-order differential values, respectively.

In step S20, it is determined whether the throttle switch is on or not, and in step S22, the intake pipe pressure is 1, the step differential value ΔP is
It is determined whether Mn is negative or not, and the following steps are executed only when the throttle switch is off and the first-order differential value ΔPMn is 0 or more. Therefore, asynchronous injection is not performed when the first differential value ΔPMn is negative, that is, during deceleration. In the next step S24, it is determined whether the count value C of the counter exceeds a predetermined value (for example, 6), and if the count value C is 6 or less, the reference value is read from the RAM in step S25. Proceeding to step S26, the count value is 6.
If it exceeds the reference value, the reference value is read from the RAM in step S27, and then the process advances to step 830.

Since this reference value ■ differs depending on the count value C of the counter, the reference value when C<6 is set as the first reference value Ll,
The reference value when C-6 is set as the second reference value L2.

In step 826, the second differential value ΔΔPM of the intake pipe pressure
Fully determine whether n is greater than or equal to the first reference value L+ (positive value),
Only when it is equal to or greater than the first reference value L1, in step 828, the asynchronous +1Jj injection pulse width T AU'i is set to a predetermined value (for example, 2
m sec, ). As a result, a predetermined period of time (24 m sec) after the fully closed throttle valve is opened.
) Asynchronous injection pulse width T A during acceleration until elapsed
A first amount of fuel corresponding to U is injected asynchronously.

Further, in step 830, the second-order differential value Δ of the intake pipe pressure
It is determined whether ΔPMn is greater than or equal to the second reference value T, 2 (positive value), and only when it is greater than the second reference value L2L, in step S32 is the non-recurring +! 31 All pulses IIQTAU are determined according to the following formula.

Note that the coefficient 0.51.24 was determined through experiments, and the coefficient 1000 is a constant for converting into time in units of ntsec. As a result, after the predetermined time indicated by −F has elapsed, the second amount of fuel corresponding to the asynchronous injection pulse width proportional to the second differential value ΔΔPMn of the intake pipe pressure is l]jt
be misled.

In addition, since the reference value L2 is set to a positive value, during steady driving when ΔΔPMn is 0 (ΔPMn=0)
Asynchronous injection is not performed during slow acceleration or slow acceleration (ΔPMn=constant).

Figure 8 shows the throttle opening during acceleration and the actual intake pipe pressure P.
, the intake pipe pressure PM detected by the pressure sensor, the first differential value ΔPM of the intake pipe pressure PM, the second differential value ΔΔPM of the intake pipe pressure PM, and the driving voltage of the fuel injection valve over time. During the period when the driving voltage is at a low level, the fuel injection valve is maintained in an open state and all fuel is injected. When acceleration starts at time t1, the throttle opening increases from 0°. Accordingly, the actual intake pipe pressure P increases, and the intake pipe pressure PM as a detected value of the pressure sensor also increases. An overshoot has occurred in the intake pipe pressure P IVI.

Pulse Ib indicates injection amount synchronized injection in synchronization with the crank angle, and the base non-injection amount determined according to intake pipe pressure PM and engine speed Q is corrected by VC such as engine cooling water temperature, etc. This is the equivalent injection. The pulse Ic is an asynchronous accelerated fuel injection performed in conjunction with the execution of step 828, and the asynchronous injection occurs when ΔΔPMn becomes equal to or greater than the first reference value L1 at a time when a predetermined period of time has elapsed since the fully closed throttle valve was opened. A first amount of fuel corresponding to the pulse width (2 msec) is injected. The pulse Id is a step fuel injection, and when ΔΔPMn becomes equal to or greater than the second reference value L2 after the asynchronous injection by the pulse Ic, a second amount of fuel corresponding to the asynchronous injection pulse width determined in step S32 is injected. Since ΔΔPM has a larger rise than ΔPM at the start of acceleration, it is possible to detect the start of acceleration quickly and accurately and perform all asynchronous acceleration fuel injections.
Since the increase in M closely reflects the increase in throttle opening, asynchronous acceleration fuel injection can be fully performed depending on the acceleration state.

In addition, in the above embodiment, an engine was explained in which the basic fuel injection kt is calculated based on the intake pipe pressure and the engine rotation speed.
It is also possible to apply this method to an engine in which the basic fuel injection amount is calculated based on the engine speed and the engine speed. In this case, PMn, ΔPMn, and ΔΔP M lz in FIG. 5 are each Q
n, ΔQn, ΔΔQn. Further, the asynchronous injection timing can also be determined from the differential value of a function whose prime number is the throttle opening degree or the fuel injection pulse width, as in the present embodiment.

As explained above, in this embodiment, a contact-type throttle sensor is used instead of a linear throttle sensor, so the structure is simple and costs are reduced9, and the reference value is increased in the low engine rotation region. Therefore, it is possible to obtain the effect that asynchronous injection is not performed and drivability is improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an engine to which the present invention is applied, FIG. 2 is a block diagram showing the control circuit of FIG. 1, and FIG.
The figure is a diagram showing the entire map of reference values against count values, Figure 4 is a flowchart showing the main routine, and Figure 5 is a diagram showing the 4 m
sec routine; FIG. 6 is a flowchart showing the complete routine for changing the reference value in accordance with the engine speed;
FIG. 7 is a flowchart showing the asynchronous injection routine, and FIG. 8 is a diagram showing temporal changes in the driving voltage of the fuel injection valve during acceleration. 6...Throttle sensor, 10.°.Pressure sensor, 1
6...Fuel injection valve. Agent: Tatsuyuki Unuma (and 1 other person) Figure 3 Kara〉 Evening count 4 shift C Figure 4 Figure 85 v, 6 Figure 7

Claims (2)

[Claims] (1) In an electronically controlled fuel injection method for an internal combustion engine in which fuel is fully injected asynchronously with the crank angle when the throttle valve is opened and the rate of change in engine load is a positive value, the point at which the throttle valve is opened from a fully closed state. A second amount of fuel is injected according to the reference time, and when the time exceeds the predetermined time and the rate of change of the engine load is equal to or greater than the reference value. An electronically controlled fuel injection method for an internal combustion engine, which is characterized by full injection of fuel. (2) The electronically controlled fuel injection method for an internal combustion engine according to claim 1, wherein the second amount is increased in accordance with a rate of change in the rate of change in the engine load.