JPH01211631A - Fuel amount control device for internal combustion engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a fuel supply system for an internal combustion engine in which, for example, the intake air amount of an internal combustion engine is detected by an air flow sensor, and the timing of the fuel supply amount to the internal combustion engine is controlled based on the detected output. This relates to a control device.

[Conventional technology]

When performing fuel control of an internal combustion engine, an air flow sensor is placed upstream of the throttle valve, and this information and the internal combustion engine's crank angle detection signal are used to determine the amount of intake air at a predetermined crank angle and control the amount of fuel supplied. is being carried out.

By the way, when trying to detect the intake air amount of an internal combustion engine by placing an air flow sensor upstream of the throttle valve in the air intake passage, if the throttle valve and internal combustion engine Since the amount of air filled into the intake passage between the internal combustion engine and the internal combustion engine is also measured, the amount of air that is filled into the intake passage between the internal combustion engine and the internal combustion engine is measured, which results in the problem of over-richness if the amount of fuel is controlled as it is. For this reason, in the past, the output of the airflow sensor, that is, the detected intake air amount at a predetermined crank angle, was set to AN(t>
, the amount of air taken into the internal combustion engine at the n-1st and nth times of a given crank angle is AN(11-11 and AN(
, l), and when the filter constant is K, AN(y,)
- to +XAN+n-+1+KzXAN+t+...
(1) holds true. By this formula (1), AN+-+
There is a system that calculates A N (n) and performs fuel control using this value. This smoothes the amount of intake air for each predetermined crank angle and performs appropriate fuel control.

However, the conventional device described above has a problem in that there is a delay in detecting the amount of intake air by the air flow sensor, resulting in a shortage of fuel during acceleration.

In order to solve this problem, the applicant of the present invention previously proposed Japanese Patent Application No. 61-93871, in which when the internal combustion engine is accelerated, the amount of intake air increases, and the amount of supplied fuel is corrected and increased accordingly. Therefore, an increase in the amount of intake air is detected and the amount of fuel supplied is increased.

[Problem to be solved by the invention]

Conventional fuel control devices for internal combustion engines are configured as described above, so the injectors are controlled in synchronization with the crank angle, but when the rotation speed is high and the load is high, the time of the pulse applied to the injectors is controlled in synchronization with the crank angle. As the width becomes longer, the cycle of the crank angle signal becomes shorter, so the end point of the pulse applied to the injector becomes longer than the end point of the intake stroke of the cylinder in question, and the intake valve of the cylinder in question closes during the fuel supply period.
No matter how much the amount of fuel supplied during acceleration of the internal combustion engine is increased, the increased fuel does not enter the intake period until the intake valve closes, so there is a problem that the air-fuel ratio cannot be properly controlled during the transient period of the internal combustion engine. .

Therefore, when the time width of the pulse applied to the injector is long, fuel is supplied before the intake valve opens, but in this case, fuel is supplied before the internal combustion engine actually takes in the fuel. Since the calculation is performed beforehand, there is a large calculation delay, and there are problems such as the inability to properly control the air-fuel ratio during transient periods of the internal combustion engine.

This invention was made in order to solve the above-mentioned problems, and provides a fuel control device for an internal combustion engine that increases the fuel correction amount during transient periods and always controls the optimal air-fuel ratio when supplying fuel early. The purpose is to obtain.

[Means to solve the problem]

A fuel control device for an internal combustion engine according to the present invention supplies fuel using a correction device that corrects and calculates a basic fuel amount based on a change in the output of an intake air amount detection device that detects an intake air amount of an internal combustion engine. When the starting crank angle is changed, the correction amount of the fuel amount to be corrected is changed.

[For production]

The fuel control device for an internal combustion engine according to the present invention injects fuel early by changing the crank angle at which fuel supply is started during transient periods such as acceleration of the internal combustion engine. Since the amount is increased, an appropriate air-fuel ratio is achieved.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows the configuration of a fuel control device for an internal combustion engine according to an embodiment of the present invention, and 1 indicates the first to fourth cylinders (#1 to #4).
10 is an intake pipe of the internal combustion engine 1, 11 is an exhaust pipe of the internal combustion engine 1, and an air cleaner 12 is connected from the upstream side of the intake pipe 1o. Karman air flow sensor (hereinafter referred to as AFS) 13, throttle valve 1
4 are arranged in order. 15 is the throttle valve 14
A surge tank 16 is provided in a portion of the intake pipe 10 on the more downstream side;
- fourth injectors 16A to 16D. Reference numeral 17 is a crank angle sensor, which changes the angle as shown in FIG.
), the rank angle pulse below C is called an SGT signal)
It falls at DC5°. ) and, for example, during the #1 compression stroke, a cylinder identification signal (hereinafter referred to as the SCC signal) of the level "rH" is output. 18 is a water temperature sensor that detects the temperature of the cooling water of the internal combustion engine 1. 2° is the AN detection means, AFS13
The number of output pulses of the AFS 13 that fall between a predetermined crank angle of the internal combustion engine 1 is calculated based on the output of the AFS 13 and the output of the crank angle sensor 17. Reference numeral 21 denotes an AN calculating means, which performs calculations similar to equation (2) described later from the output of the AN detecting means 20 to calculate the number of pulses equivalent to the output of the AFS 13 corresponding to the amount of air considered to be taken in by the internal combustion engine 1. . Further, the control means 22 controls the drive of the injector 16 according to the amount of air taken into the internal combustion engine 1 and the operating condition (for example, the rotation speed) based on the output of the AN calculation means 21, the output of the crank angle sensor 17, and the output of the water temperature sensor 18. The time and drive timing are controlled, thereby controlling the amount of fuel supplied to the internal combustion engine 1.

FIG. 2 shows a more specific configuration of this embodiment, and 30 is A.
FS 13, crank angle sensor 17 and water temperature sensor 1
This control device receives the output signal of 8 and controls the four first to fourth injectors 16A to 16D provided for each cylinder of the engine 1, and this control device 30 is similar to the AN detection means 20 in FIG. ~ Corresponds to the control means 22, and the CPU
32, a microcomputer (hereinafter referred to as a microcomputer) with a built-in ROM 33, RAM 34, etc. that stores the flows shown in Figures 3, 5, and 6 as a program and stores data for calculations and judgments. This is realized by 31. Further, 35 is a counter whose one input is the output of the AFS 13 and whose other output terminal is connected to the input terminal P1 of the microcomputer 31, and measures the period of the output pulse of the AFS 13. The output of the AFS 13 is also configured to be input to the interrupt input terminal P2 of the microcomputer 31. 36 is an interface connected between the water temperature sensor 18 and the A/D converter 37; 38 is a waveform shaping circuit to which the SGT output of the crank angle sensor 17 is input; It is input to the counter 39. 40 is a waveform shaping circuit to which the SGC output of the crank angle sensor 17 is input, and its output is input to a port of the microcomputer 31. 41 is a timer connected to the interrupt input terminal P4; 42 is an A/D converter that A/D converts the battery voltage VB and outputs it to the microcomputer 31; 43 to 46 are the microcomputer 31 and the first to fourth drivers 47 to 50, the output terminals of the first to fourth drivers 47 to 5o are connected to the first to fourth injectors 16A to 16D, respectively. .

Next, the operation of the fuel control device shown in FIG. 2 will be explained. The output of the AFS 13 is input to a counter 35, which measures the period between the rising edges of the input pulse. The microcomputer 31 receives the rising edge of the pulse from the AFS 13 at an interrupt input terminal P2, performs interrupt processing every output pulse period of the AFS 13, and reads the period from the counter 35. The output of the water temperature sensor 18 is converted into a voltage by the interface 36, and converted into a digital value by the A/D converter 37 at predetermined time intervals, and then sent to the microcomputer 3.
1 is input. The SGT output of the crank angle sensor 17 is input to the interrupt input terminal P3 of the microcomputer 31 and the counter 39 via the waveform shaping circuit 38. The microcomputer 31 performs an interrupt process every time the SGT output of the crank angle sensor 17 rises, and calculates the period between the rises of the SGT output using the counter 3.
It is detected from the output of 9. Also, every time this SGT signal rises, the SGC signal of the crank angle sensor 17 is checked, and #
Detects the compression stroke of one cylinder. The timer 41 generates an interrupt signal to the interrupt input terminal P4 of the microcomputer 31 at predetermined intervals. The A/D converter 42 converts the battery voltage into an A/D converter.
D conversion is performed, and the microcomputer 31 takes in data of this battery voltage at predetermined time intervals. The first to fourth timers 43 to 46 are preset in the microcomputer 31 and are triggered by the output ports P and + to P8 of the microcomputer 31, respectively, to output predetermined pulse widths, and these outputs are sent to the first to fourth drivers 47. ~50
The first to fourth injectors 16A to 16D are driven through the respective injectors 16A to 16D.

Next, the operation of the CPU 32 in the microcomputer 31 will be explained with reference to flowcharts shown in FIGS. 3, 5, and 6.

First, FIG. 3 shows the main program of the CPU 32,
When the reset signal is input to the CPU 32, step 1
00 to initialize the RAM 34, input/output ports, etc., and in step 101 the output of the water temperature sensor 18 is A/D converted and stored in the RAM 34 as WT. Step 102
The battery voltage is A/D converted and stored in the RAM 34 as VB. In step 103, the crank angle sensor 17
30/TR is calculated from the period TR, and the rotation speed N8 is calculated. At step 104, load data AN and rotation speed N, which will be described later. Calculate AN, N, /30 from AFS
Calculate the output frequency F8 of 13. In step 105, f is set to F from the output frequency F3 as shown in FIG.

From the basic drive time conversion coefficient, calculate. Step 1
In 06, the conversion coefficient KF is corrected by the water temperature data WT,
It is stored in the RAM 34 as a driving time conversion coefficient.

In step 107, the number of revolutions is N.

It is determined whether or not the rotation speed is less than a predetermined rotation speed α, and if it is less than the predetermined rotation speed α, the correction value KNA is set to a predetermined value C1 in step 108, and if it is not less than but greater than or equal to the predetermined value C1, the correction value KNA is set to a predetermined value C2 (however, , CI < C2). Next, in step 110, the water temperature correction acceleration increase coefficient f, (W
T ) and the correction value KNA set as above, K I A = K P A X f 3 (W T )
The calculation of XKNA is performed to calculate 1A as a drive time conversion coefficient for transient correction, and the result is stored in the RAM 34. Step 111
Now, map the data table f4 stored in the ROM 33 in advance from the battery voltage data VB, and calculate the waste time T.
, is calculated and stored in the RAM 34. After the process in step 111, the process returns to step 101 and repeats the above process.

FIG. 5 shows the interrupt processing for the interrupt P2, that is, the output signal of the AFS 13. In step 201, the output T of the counter 35 is detected and the counter 35 is cleared. This T
A is the period between the rising edge of the output pulse of AFS 13,
The output pulse period TA of this AFS 13 is stored in the RAM 34. At step 202, the remaining pulse data P is added to the accumulated pulse data PR. In step 203, the remaining pulse data P is set to 156. Step 20
After the processing in step 3, the interrupt processing in FIG. 5 is completed.

Figure 6 shows the microcomputer 3 using the output of the crank angle sensor 17.
CP when an interrupt signal is generated at interrupt input terminal P3 of 1
The interrupt processing of U32 is shown. In step 301, the cycle between the rises of the crank angle sensor 17 is read from the counter 39, stored in the RAM 34 as the cycle TR, and the counter 39
Clear.

If there is an output pulse of the AFS13 within the period TR in step 302, the immediately preceding AFS13
Also the time of the output pulse. , and the current interrupt time of the crank angle sensor 17. 2 time difference Δt = toz f−oI
is calculated, and this is set as period T, and AFS1 is calculated within period TR.
If there is no output pulse No. 3, the period TR is set to the period T in step 304.

In step 305, for example, the time difference ΔL in step 303 is calculated by calculating 156
is converted into output pulse data ΔP. In step 306, if the pulse data ΔP is 156 or less, step 308
If it is larger, 8P is clipped to 156 in step 307. In step 308, the pulse data ΔP is subtracted from the remaining pulse data PD, and the new remaining pulse data Δ
Let it be P.

In step 309, if the remaining pulse data Pn is 0 or more, the process goes to step 313; otherwise, the pulse data ΔP
Since the calculated value of is too larger than the output pulse of the AFS 13, the pulse data ΔP is set to be the same as P in step 310, and the remaining pulse data P is set to 0 in step 312.

In step 313, the pulse data ΔP is added to the integrated pulse data P, and the result is set as new integrated pulse data PR.

This data PR corresponds to the number of pulses that the AFS 13 is thought to have output during the current rise of the crank angle sensor 17. In step 314, calculations corresponding to equation (1) above are performed. That is, from the load data AN calculated up to the previous rise of the SGT signal of the crank angle sensor 17, the integrated pulse data P, and the filter constant +, kz, kl・
A N + k 2 · P + t is calculated, and the result is set as the current new load data AN. In step 315, if this load data AN exceeds the predetermined value β, step 316
is clipped to β to prevent the load data AN from becoming too large than the actual value even when the internal combustion engine 1 is fully opened, and if it is less than β, the process proceeds to step 317. Step 31
7, the integrated pulse data P is cleared.

In step 318, 1 is calculated for the load data AN and the driving time conversion coefficient, and +T is calculated for the driving time data T1=AN, based on the dead time TD. Step 3197i! Now, the new current load data AN and the previous load data ANo, D
The difference ΔAN is calculated and compared with a predetermined value T in step 320. In step 320, if it is less than or equal to γ, step 32
2, and if it exceeds T, then in step 321 the drive time data T1 and the load data difference ΔAN are stored in the RAM 34 first.
The drive time data T1 is corrected by calculating T1-T and 1ΔA N X K IA using the drive time conversion coefficient KIA for transient correction stored in . The driving time data T1 calculated in step 322 is transmitted to the first to fourth timers 43.
Preset to ~46. Next, in step 323, the current load data AN is stored in the RAM 34 as the previous load data ANOLD. In step 324, the level of the SGC signal output from the crank angle sensor 17 is determined.
If it is "L", the cylinder counter is incremented by +1 in step 326 and the cylinder count (directly C6 is changed to c, =
Update at C, +1. Next, in step 327, it is determined whether the rotational speed N8 is less than a predetermined rotational speed α, and if it is less than the predetermined rotational speed α, the process proceeds to step 328, otherwise, step 335
Proceed to. In step 328, it is determined whether the cylinder counter is 0 or not, and if it is 0, in step 329, the fourth timer 4 is
6 to drive #4 injector 16D, and 0
If not, the cylinder counter is set to 1 in step 330.
If it is 1, the second timer 44 is activated in step 331 to drive the #2 injector 16B, and if it is not 1, the process proceeds to step 332. Step 33
In Step 2, it is determined whether the cylinder counter is 2 or not. If it is 2, the first timer 43 is triggered in Step 333 to drive the #1 injector 16A. If it is not 2, it is 3, so in Step 334 Trigger the third timer 45 and #3
The injector 16C is driven.

Also, in step 335, it is determined whether the cylinder counter is O or not, and if it is 0, the second timer 44 is triggered in step 336 to drive the #2 injector 16B, and if it is not 0, the cylinder counter is is 1, and if it is 1, the first timer 3 is set in step 338.
Trigger #1 to drive #1 injector 16A,
Otherwise, the process proceeds to step 339. In step 339, it is determined whether the cylinder counter is 2 or not, and if it is 2, the third timer 45 is triggered in step 340 to drive the #3 injector 16C, and if it is not 2, step 341
Trigger the fourth timer 46 at #4 injector 1
Drive 6D.

Injectors 16A to 1 of #1 to #4 as described above.
6D is driven to complete the series of processing and return.

FIG. 7 shows the situation when the throttle valve 14 is opened. The amount of air that the internal combustion engine 1 takes in for the n-1st and nth times is Q e(n+ + Qe(n-11), and AFS
The amount of air passing through 13 for the nth time Qa (assuming n+) is
Corresponding to equation 1), equation (2) below holds true.

Qe+n) - to + X QlICll-1) + K
zx Qatn+ =12) In Figure 7, (a
) is the opening degree of the throttle valve 14, (b) is the AFS13
This is the intake air amount Q3 that passes through, and it overshoots. (C) is corrected using formula (2)! ! This is the amount of air Q that the A engine 1 takes in, and (d) is the pressure P inside the surge tank 15. Also, (e) shows the amount of change △Q of Q8, and (
f) indicates the supplied fuel amount fu.

ful is based on Qe, and fu2 is corrected based on ΔQ.

FIG. 8 is a timing diagram of various signals in each process of the internal combustion engine 1. In particular, the signal waveform shown by the solid line is at high rotation. In FIG. 8, (a) is the SGT signal, (b) is the SGC signal, (C) is the value C6 of the cylinder counter, (d) is the driving pulse of the first injector 14A of #1, and (e) is the #3 (f) is the drive pulse of the fourth injector 1 to D of #4, (g) is the drive pulse of the second injector 16B of #2, (5) is the drive pulse of the second injector 16B of #2, and (5) is the drive pulse of the fourth injector 1 to D of #4. Indicates the process: fanning is the explosion process, exhaust is the exhaust process, suction is the intake process, and pressure is the compression process. When the internal combustion engine 1 is running at high speeds, it becomes as shown by the solid line, but when the internal combustion engine 1 is running at low speeds, it becomes as shown in FIG. It is understood that fuel injection is performed with a delay of the l5 GT signal period.In other words, the l5
Fuel injection is performed earlier in GT (for example, -step), and the time width is corrected to be longer during acceleration transition.

In Fig. 8, the rise of the injector drive pulse in Fig. 8(d) to Fig. 8 (cloudy) is actually at SG in Fig. 8(a).
There is a very short delay of processing time from the rising edge of the T signal.

In the above embodiment, steps 107 to 110 of the main routine in FIG. 3 are deleted, step 106 is followed by step 111, and step 107 is
The process from step 110 to step 3 in FIG. 6(a)
It may be inserted between the affirmative determination of step 20 and step 321.

Further, in the above embodiment, the output pulses of the AFS 13 during the rising edge of the crank angle sensor 17 are counted, but this may also be during the falling edge, or the number of output pulses of the AFS 13 during several cycles of the crank angle sensor 17 may be counted Also good. Also, A
Although the output pulses of the FS 13 are counted, the number of output pulses multiplied by a constant corresponding to the output frequency of the AFS 13 may be counted. 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.

(Effects of the Invention) As described above, according to the present invention, when the crank angle at which fuel supply is started is changed, the fuel amount is corrected by correcting the basic fuel amount according to the change in the intake air amount of the internal combustion engine. Since the structure is configured to change the bone, there is an effect that it is possible to correct a shortage of fuel amount due to a delay in calculation of intake air amount, etc., and to perform appropriate air-fuel ratio control.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the entire fuel control device for an internal combustion engine according to an embodiment of the present invention, FIG. 2 is a more specific block diagram of the device shown in FIG. 1, and FIG. 3 is a main block diagram of the CPU in the device. FIG. 4 is a flowchart showing the routine; FIG. 4 is a diagram showing the relationship between the basic driving time conversion coefficient and the AFS output frequency of the above device; and FIG.
Figures 6(a) and 6(c) show the C in the above device.
FIG. 7 is a flow diagram showing the interrupt processing routine of the PU; FIG.
The figure is a timing diagram of various signals in each process of an internal combustion engine. In the figure, 1... internal combustion engine, 10... intake pipe, 13...
・AFS, 14... Throttle valve, 16... Injector, 17... Crank angle sensor, 18...
Water temperature sensor, 20...AN detection means, 21...AN
Arithmetic means, 22...control means. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] a crank angle sensor for detecting the crank angle of the internal combustion engine; an intake air amount detection means for detecting the intake air amount of the internal combustion engine; a calculation means for calculating a basic fuel amount based on the output of the intake air amount detection means; and the intake air amount detection means. a correction means for correcting and calculating a basic fuel amount to be supplied to the internal combustion engine based on a change in the output of the means; In the fuel control device for an internal combustion engine, the correction means includes a supply means for supplying the internal combustion engine and a changing means for changing a crank angle at which the fuel supply is started according to an operating state of the internal combustion engine. A fuel control device for an internal combustion engine, characterized in that when the crank angle at which fuel supply is started is changed, the amount of correction of the amount of fuel to be corrected is changed.