JPS62248842A - Fuel control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent the shortage of fuel even at the time of acceleration by detecting increase in intake air quantity and increasing the quantity of feeding fuel. CONSTITUTION:An intake air quantity sensor 13 outputs a pulse in accordance with air quantity taken into an internal combustion engine 1 and crank angle sensor 17 output a pulse in accordance with the rotation of the internal combustion engine 1. An intake air quantity detecting means 20 calculates the number of output pulses of the intake air quantity sensor 13 which enter in between defined crank angles of the internal combustion engine 1, from the output of the intake air quantity sensor 13 and the output of the crank angle sensor 17. An intake air quantity operating means 21 calculates the number of pulses corresponding to the output of the intake air quantity sensor13 corresponding to an air quantity which is considered to be taken in to the internal combustion engine 1, from the output of the intake air quantity detecting means 20. A control means 22 controls the driving time of an injector 14 in accordance with the air quantity which is taken into the internal combustion engine 1 based on the output of the intake air quantity operating means 21 and the output of a water temp. Sensor 18 for detecting the cooling water temp. Of the internal combustion engine 1, thereby, controlling the quantity of fuel which is fed into the internal combustion engine.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is directed to a fuel IIJ for an internal combustion engine, which detects the intake air amount of the internal combustion engine by an intake air amount sensor and controls the fuel supply amount of the internal combustion engine based on the detected output. This is related to the control device.

[Conventional technology]

When performing fuel control of an internal combustion engine, an intake air flow sensor (hereinafter abbreviated as AFS) is placed upstream of the throttle valve,
Based on this information and the engine speed, the amount of intake air per intake is determined, and the amount of fuel to be supplied is controlled.

By the way, when trying to detect the intake air amount of an internal combustion engine by placing AFS upstream of the throttle valve in the air intake passage, when the throttle suddenly opens, the intake air between the throttle valve and the engine Since the amount of air filled into the passage is also measured, the amount of air that is filled into the passage is measured more than the amount of air that is actually taken into the internal combustion engine, and if the amount of fuel is controlled as it is, a problem arises in that it becomes overrich. For this reason, conventionally, the output of AFS, that is, the detected intake air amount at a predetermined crank angle is AN, t, n-1 of a predetermined crank angle.
AN is the amount of air that the internal combustion engine takes in at the times and n times, respectively.
,. -1, and AN, , , when the filter constant is K, AN =K xAN +K xANlnl
1 (n-112(tl) There is a system that calculates AN, ., using the formula of tl, and uses this AN, . to perform fuel control. It was designed to perform efficient fuel control.

[Problem that the invention seeks to solve]

However, in the conventional device described above, since the intake air amount is corrected, there is a calculation delay of one intake air or more, and when accelerating, there is also a delay in the detection output of the intake air amount detection means due to the presence of air in the intake pipe. There was a problem that there was a shortage of.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a fuel control device for an internal combustion engine that does not run out of fuel even during acceleration.

[Means for solving problems]

The fuel control device for an internal combustion engine according to the present invention is provided with an intake air amount increase detection means for detecting an increase in the intake air amount, so that when the intake air amount increases, the supplied fuel amount also increases.

[For production]

When the internal combustion engine is accelerated, the amount of intake air increases, and it is necessary to increase the amount of fuel supplied accordingly, but the amount of fuel is insufficient due to delays in the calculation of the amount of intake air and the control system. Therefore, in the present invention, an increase in the intake air amount is detected and the supplied fuel amount is increased.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Figure 3 shows a model of the intake system of an internal combustion engine, where 1 is an internal combustion engine and V per stroke. has a volume of , and the Kalman style t
Air is inhaled through the AFS 13, throttle valve 12, surge tank 11 and intake pipe 15,
Fuel is supplied by an injector 14. Also, here, the volume from the throttle valve 12 to the internal combustion engine 1 is v
8. 16 is an exhaust pipe.

FIG. 4 shows the relationship between the amount of intake air and a predetermined crank angle in the internal combustion engine 1, and (a) shows the predetermined crank angle (hereinafter referred to as SGT) of the internal combustion engine 1. (bl is the air amount Q passing through the AFS 13, (c) is the air amount ζ taken in by the internal combustion engine 1, and (d) is the output pulse f of the AFS 13. Also, SG T f) n-2 to n - The period of the first rise is t. -1, the period from n-1 to n-th rise is t. and period t. −1 and t. to AFS13
The amount of intake air passing through Qsln-11 and Q, respectively.
,. 1, periods tn-1 and t. Let the amounts of air taken into the internal combustion engine 1 be Q, In-11, and Qslnl, respectively. Furthermore, the period t. Let the average pressure and average intake air temperature in the surge tank 11 at -8 and tn be P, P and T, respectively. For example, QaI
n-11 corresponds to the number of output pulses of the AFS 13 during "n-1. Also, since the rate of change in the intake air temperature is small, it is set as T, and assuming that the charging efficiency of the combustion engine 1 is constant, Pa 1n-41"c = Qa In-11・R-
T... , ......(1)P-1,l''-
"Q-1゜l 'R' T-(.l "' ”
'''. However, R is a constant. Then, if the amount of air accumulated in the surge tank 11 and the intake pipe 15 during the period trl is ΔQ, then Δ qll,n, = q・, , -Q ,,n,=v,−,
τT.

x (p,,.1-Pm1゜-8,)...
(3), and equations (1) to (3) are obtained. Therefore, the internal combustion engine 1 is operated for a period t. The amount of air inhaled Q. , the amount of air passing through AFS 13 q
It can be calculated using equation (4) based on , , .

Now, vc=o, 5z, v,=2. sI tort,
Qa(nl=”83×Qsin-11+” ” ”
Qa ln+ (5j). Fig. 5 shows the situation when the throttle valve 12 is opened. In Fig. 5, (a) shows that the throttle valve 12
(b) is the intake air amount Q passing through AFS13 in m,
and overshoots.

(c) is the amount of air Q taken into the internal combustion engine 1 corrected using equation (4), and (d) is the pressure P of the surge tank 11.

(el indicates the amount of change ΔQ in Q, and (f) indicates the fuel supply amount f. Here, fl is based on Q,
f2 is corrected based on ΔQ0.

FIG. 1 shows the configuration of a fuel control device for an internal combustion engine according to the present invention. 10 is an air cleaner disposed upstream of AFSlB, and AFSlB is configured as shown in FIG. d), and the crank angle sensor 17 outputs a pulse as shown in FIG. ) is output. Reference numeral 20 denotes AN detection means, which calculates the number of output pulses of AFSlB that fall within a predetermined crank angle of the internal combustion engine 1 based on the output of AFSlB and the output of the crank angle sensor 17. 21 is an AN calculation means, which is the AN detection means 2.
Perform calculations similar to equation (5) from the output of 0, and calculate the internal combustion engine 1
AFS 13 corresponding to the amount of air expected to be inhaled by
Calculate the number of pulses equivalent to the output of Further, the control means 22 drives the injector 14 in accordance with the amount of air taken into the internal combustion engine 1 based on the output of the AN calculation means 21 and the output of a water temperature sensor 18 (for example, a thermistor) that detects the cooling water temperature of the internal combustion engine 1. The time is controlled, and thereby the amount of fuel supplied to the internal combustion engine 1 is controlled.

FIG. 2 shows a more specific configuration of this embodiment, and 30 is A.
FS 13, water temperature sensor 18 and crank angle sensor 1
This is a control device that receives an output signal of 7 as an input and controls four injectors 14 provided for each cylinder of an internal combustion engine 1, and this control device 30 corresponds to the AN detection means 20 to control means 22 in FIG. , ROM41. This is realized by a microcomputer (hereinafter abbreviated as CPU) 40 having a RAM 42. Further, 31 is a 2-frequency divider connected to the output of AFSlB, 32 is an exclusive OR gate whose one input terminal is the output of the 2-frequency divider 31, and the other input terminal is connected to the input P1 of the CPU 40. The output terminal is connected to the counter 33 and the input P3 of the CPU 40. 34 is an interface connected between the water temperature sensor 18 and the A/D converter 35, 36 is a waveform shaping circuit to which the output of the crank angle sensor 17 is input, and the output is input to the interrupt input P4 of the CPU 40 and the counter 371. be done. Further, 38 is a timer connected to the interrupt input P5, and 39 is an A/D converter that converts the voltage of a battery (not shown) and outputs it to the CPU 40.
The /D converter 43 is a timer provided between the CPU 40 and the driver 44, and the output of the driver 44 is connected to each injector 14.

Next, the operation of the above configuration will be explained. The output of AFSlg is frequency-divided by a two-way division @31 and input to a counter 33 via an exclusive OR gate 32 controlled by the CPU 40. Counter 33 measures the period between the falling edges of the output of gate 32. CPU40 is gate 32
The falling edge of is input to the interrupt input P3, and interrupt processing is performed every time the output pulse period of AFSlB or this is divided by two, and the period of the counter 33 is measured. The output of the water temperature sensor 18 is converted to voltage by the interface 34, and the output is converted to voltage by the A/D
It is converted into a digital value by the converter 35 at predetermined time intervals and is taken into the CPU 40. Crank angle sensor 17
The output is input to the interrupt input P4 of the CPU 40 and the counter 37 via the waveform shaping circuit 368. The CPU 40 performs an interrupt process every time the crank angle sensor 17 rises, and detects the period between the rises of the crank angle sensor 17 from the output of the counter 37. The timer 38 activates the CPU 4 at predetermined intervals.
0 generates an interrupt signal to the interrupt P5. The A/D converter 39 A/D converts the battery voltage (not shown), and converts the battery voltage (not shown) into
The PO 40 takes in this battery voltage data at predetermined time intervals. The timer 43 is preset in the CPU 40 and
It is triggered from the output port P2 of U40 to output a predetermined pulse width, and this output drives the injector 14 via the driver 44.

Next, the operation of the CPU 40 will be explained in FIGS. 6 and 8-9.
Explained by Chiard. First, Figure 6 shows the CPU 40
When a reset signal is input to the CPU 40, the RAM 42, input/output boat, etc. are initialized in step 100, and the output of the water temperature sensor 18 is A/D converted and stored in the RAM 42 as WT in step 101. . In step 102, the battery voltage is A/D converted and stored in the RAM 42 as VB. Step 10
3, 30/TF from the cycle T8 of the crank angle sensor 17
I is calculated, and the rotational speed N is calculated. Step 10
From load data AN and rotation speed N, which will be described later in 4, AN・N
, /30 to calculate the output frequency of AFS 13. In step 105, f is set for the output frequency as shown in FIG.

Basic driving time conversion coefficient K. Calculate. Step 1
In 06a, the conversion coefficient - is corrected by water temperature data WT,
It is stored in the RAM 42 as a driving time conversion coefficient. In step 106b, the basic drive time conversion coefficient K at the time of acceleration increase
PA is corrected using the water temperature data WT and stored in the RAM 42 as a drive time conversion coefficient of 1A. That is, when the water temperature is low, more fuel adheres to the inside of the intake pipe 15, and a correspondingly larger amount of fuel is required, whereas when the water temperature is high, the amount of adhering fuel is small and the amount of fuel to be supplied may also be small. In step 107, the data is stored in the ROM 41 in advance from the battery voltage data VB.
The data table f3 stored in the data table f3 is mapped, the wasted time is calculated, and the result is stored in the RAM 42. Step 107
After the process, the process of step 101 is repeated again.

FIG. 8 shows the interrupt processing for the output signal of interrupt input P3, ie, AFS 1 g. In step 201, counter 3
3 is detected and the counter 33 is cleared. This T1 is the period between the rises of the gate 32. If the branch flag in the RAM 42 is set in step 202, l is divided into two in step 203 and stored in the RAM 42 as the output pulse period T of AFS 1 g. Next, in step 204, the remaining pulse data P is added to the accumulated pulse data 8.
. , and add the new integrated pulse data P.
8. This integrated pulse data a is obtained by integrating the number of pulses of AFS 1 g output during the rise of the crank angle sensor 17, and is treated as 156 times one pulse of AFSI 3 for convenience of processing.

If the branch flag is reset in step 202, the lever
In step 205, RA
M42, and in step 206, the remaining pulse data 8 is added to the accumulated pulse data 8. In step 207, the remaining pulse data P is set to 156. Step 2
If the branch flag is reset in 08, T, >
2 m5ec, T if set, > 4
If it is yasee, the process advances to step 210; otherwise, the process advances to step 209. In step 209, a branch flag is set, in step 210, the branch flag is cleared, and in step 211, Pl is inverted. Therefore, in the case of the process of step 209, a signal is input to the interrupt manual P3 at the timing when the output pulse of AFSlg is divided by 2,
AFS 13 when the process of step 210 is performed.
A signal is input to the interrupt input P3 for each output pulse. After processing steps 209 and 211, the interrupt processing is completed.

FIG. 9 shows the CPU 40 using the output of the crank angle sensor 17.
The interrupt processing when an interrupt signal is generated at the interrupt input P4 is shown. In step 301, the period between the rises of the crank angle sensor 17 is read from the counter 37, and the period - is set as R.
It is stored in AM42 and the counter 37 is cleared. If in step 302 there is an output pulse of AFS 13 within the period -, then in step 303 the time difference Δt between the time t0□ of the immediately preceding output pulse of AFS 1g and the current interrupt time tOQ of the crank angle sensor 17 is determined = t02 -tOf is calculated, and this is set as the period -, and if there is no output pulse of AFSlg within the period -, the period - is set as the period -. Step 30
5, the time difference Δt is converted into output pulse data ΔP of the AFS 13 by calculating 1 s 6 x T, /' TA.

That is, the output pulse period of the previous AFS 13 and the current A
Pulse data ΔP is calculated assuming that the output pulse period of FS 1 g is the same. In step 306, if the pulse data ΔP is smaller than 156, the process proceeds to step 308; if it is larger, ΔP is clipped to 156 in step 307.

In step 308, pulse data ΔP is subtracted from remaining pulse data 9 to obtain new remaining pulse data ΔP.

In step 309, if the remaining pulse data is positive, proceed to step 313a; otherwise, the calculated value of pulse data ΔP is too larger than the output pulse of AFSI (), so in step 310, pulse data ΔP is made equal to P; In step 312, the remaining pulse data 8 is set to zero.In step 313, the pulse data Δ is added to the integrated pulse data P8.
P is added to create new integrated pulse data. This data 8 is A during the rise of the crank angle sensor 17 this time.
This corresponds to the number of pulses that are thought to have been output by FS 1 g. In step 314, calculations corresponding to equation (5) are performed. That is, from the load data AN calculated up to the previous rise of the crank angle sensor 17 and the integrated pulse data P8,
K, AN+ (K2) P, is calculated, and the result is set as the current new load data AN. In step 315, if this load data AN is larger than the predetermined value a, step 3
16, the load data AN is thicker than the actual value even when the internal combustion engine 1 is fully open (so that it does not become too large). In step 317, the accumulated pulse data is cleared. In step 318a, the load data AN is 3 for AN and drive time conversion coefficient, drive time data T from waste time T0,
= AN −K, +T.

Perform the calculation. Further, in step 318b, the difference ΔAN between the new load data AN and the previous load data AN is determined, and in step 318c, it is determined whether ΔAN is greater than β1, and if it is smaller, the process proceeds to step 318g.

In addition, if ΔAN>β, in step 318d, ΔAN
It is determined whether or not the second is larger than β2, and if it is smaller, the process proceeds to step 318f, and if it is larger, the process proceeds to step 318e.
ΔAN is clipped to β2, and the process proceeds to step 318f. In step 318f, drive time data T is obtained from T1, ΔAN, and KIA, and in step 318g, AN o
It is stored in the RAM 42 as L,==AN. next,
In step 319, driving time data T is set in the timer 43, and in step 320, the timer 43 is triggered, so that four injectors 14 are simultaneously driven in accordance with T, and the interrupt processing is completed.

FIG. 10 shows the timing when the branch flag is cleared in the processing of FIGS.
The output of 7 is shown. (e) shows the remaining pulse data P0, which is set to 156 each time the frequency division N31 rises and falls (the rising edge of the output pulse of AFSlg), and is set to 156 every time the crank angle sensor 17 rises, for example, Po, = P0-156
The calculation result is changed to T,/TA (this corresponds to the processing in steps 305 to 312). (d) shows the change in the integrated pulse data PFI, and the remaining pulse data P is changed every time the output of the frequency divider N31 rises or falls. It shows how is accumulated.

In the above embodiment, the output pulse of AFSlg during the rising edge of the crank angle sensor 17 was counted, but this may also be during the falling edge, or the number of AFSlg output pulses during several cycles of the crank angle sensor 17. may be counted.

Further, although the output pulses of AFSlg are counted, the number of output pulses may be multiplied by a constant corresponding to the output frequency of AFSlg. Furthermore, the same effect can be obtained by using the ignition signal of the internal combustion engine 1 instead of the crank angle sensor 17 to detect the crank angle.

〔Effect of the invention〕

As described above, according to the present invention, when the internal combustion engine accelerates, an increase in the intake air amount is detected by the intake air amount increase detection means, and the supplied fuel amount is increased accordingly. It is possible to correct a shortage of fuel amount due to a delay in the control system, and also to increase or decrease the fuel amount depending on the cooling water temperature, so that appropriate air-fuel ratio control can be performed.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a fuel control device according to the present invention, FIG. 2 is a block diagram showing a specific example of the fuel control device for the same internal combustion engine, and FIG. 3 is a block diagram showing the intake air of the internal combustion engine according to the present invention. Fig. 4 is a diagram showing the relationship between the intake air amount and the crank angle; Fig. 5 is a waveform diagram showing changes in the intake air amount during transient periods of the internal combustion engine; Fig. 6; 8 and 9 are diagrams showing the operation of a fuel control device for an internal combustion engine according to an embodiment of the present invention, and FIG. Diagram showing the relationship between time conversion coefficients, 10th rI! J
9 is a timing chart showing the timing of the flows in FIGS. 8 and 9. FIG. 1... Internal combustion engine, 12... Throttle valve, 13
... Airf four-sensor (Karman S flowmeter), 14.
... Injector, 15... Intake pipe, 17-, Crank angle sensor, 18... Water temperature sensor, 20... AN detection means, 21... AN calculation means, 22... Control means. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A to detect the amount of intake air per intake of an internal combustion engine
In a fuel control device for an internal combustion engine that controls the amount of fuel supplied to the internal combustion engine based on the output of the N detection means, the intake air amount increase detection means detects an increase in the intake air amount, and the cooling water temperature of the internal combustion engine is detected. 1. A fuel control device for an internal combustion engine, characterized in that a water temperature detection means is provided to increase the amount of supplied fuel during acceleration, and also increase or decrease the amount of supplied fuel depending on the cooling water temperature. (2) The fuel control device for an internal combustion engine according to claim 1, wherein a limit is set on an increase in the amount of supplied fuel.