JPH0245640A - Fuel controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the starting characteristic by driving each injector at the same time only one time in the initial stage on start. CONSTITUTION:An injector 14 is installed for each cylinder of an engine 1, and a controller 30 drives each injector 14 one time in one intake cycle of each cylinder. In the initial stage of start, all the injectors 14 are driven at the same time. Each injector 14 is not driven until the cycle counter becomes zero, and after the cycle counter counts zero, each injector 14 is driven in sequential ways in succession. Therefore, all the injectors 14 are driven at the same time only one time on start, and fuel is supplied smoothly from the start, and the starting characteristic can be improved. Afterwards, the sequential injection is started after the prescribed cycle of the engine 1, and the excessive feed of fuel is prevented, and the superior air-fuel ratio control can be carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a fuel control device for an internal combustion engine.

[Conventional technology]

In conventional fuel injection for internal combustion engines, a multi-point system in which an injector is provided for each cylinder is typical.
Further, a sequential method is used in which each injector sequentially injects fuel at a predetermined crank angle for each cylinder. this is,
This is because the range of the drive pulse width of each injector can be widened, making it easier to control the air-fuel ratio.

[Problems to be Solved by the Invention] However, in the conventional device described above, a specific cylinder is detected by a cylinder identification sensor, and the injectors of each cylinder are sequentially driven based on this cylinder as a reference. In the worst case, a four-cylinder engine would have to wait three intakes until the cylinder is detected, resulting in poor starting characteristics.

The present invention was made to solve the above problems, and an object of the present invention is to obtain a fuel control device for an internal combustion engine that can improve starting characteristics in sequential injection.

[Means to solve the problem]

The fuel control device for an internal combustion engine according to the present invention is a sequential injection device that sequentially drives each injector, and drives each injector simultaneously only once at the time of starting, and sequentially drives each injector after a predetermined stroke of the engine. It was designed to do this.

[For production]

In this invention, all injectors are driven only once at the time of starting, and injection is performed regardless of the cylinder identification signal.

Further, the sequential driving of each injector is not performed until a predetermined number of strokes have elapsed.

〔Example〕

Embodiments 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 the present invention, where 1 is a four-cylinder engine, 10 is an air cleaner, and 11 is a 4-cylinder engine.
1 is a surge tank, 12 is a throttle valve, 13 is a Karman air flow sensor (hereinafter abbreviated as AFS), 1
4 is an injector provided for each cylinder of the engine 1;
15 is an intake pipe, 16 is an exhaust pipe, 17 is a crank angle sensor, 18 is a water temperature sensor, and 19 is a start switch.

The AFS 13 outputs a pulse according to the amount of air taken into the engine 1, and the crank angle sensor 17 outputs an SGT (crank angle) pulse (for example, a pulse) according to the rotation of the engine 1 as shown in FIG. 8(b). (The crank angle is 180 degrees from one rising edge to the next rising edge.) and an SGC signal (cylinder identification signal) of rH is output during the compression stroke of a specific cylinder, for example, Nal. 20 is an AN detection means, and AF
Based on the output of Si3 and the output of crank angle sensor 17,
AFS 13 that falls between the predetermined crank angles of engine 1
Calculate the number of output pulses. 21 is an AN calculation means;
From the output of the N detection means 20 to AN+t+=+-AN+t-+++(+ to 1-)・P
++ .=(1) is calculated, and the number of pulses AN+t corresponding to the output of the AFS 13 corresponding to the amount of air considered to be taken in by the engine 1 is calculated. Here, AN+t
−++ is A corresponding to the amount of air that is thought to have been taken in by engine 1 until the SGT pulse at time t −1;
The number of pulses equivalent to the output of F S13, P, is from time t-1 to
This is the output of the AN detection means 20 which detected the .

Further, the control means 22 includes the output of the AN calculation means 21, the output of the crank angle sensor 17, the output of a water temperature sensor 18 (for example, a thermistor, etc.) that detects the cooling water temperature of the engine 1, and a start switch that detects the starting state of the engine 1. 19, the driving time of the injector 14 is controlled in accordance with the intake air amount of the engine 1, thereby controlling the amount of fuel supplied to the engine 1.

FIG. 2 shows a more specific configuration of this embodiment, and 30 is A.
FS l 3, crank angle sensor 17, water temperature sensor 18
and the output signal of the start switch 19, the engine l
This is a control device that controls four injectors 14 provided for each cylinder, and this control device 30 corresponds to the AN detection means 20 to control means 22 in FIG.
1. It is realized by a microcomputer (hereinafter abbreviated as CPU) 40 having a built-in RAM 42. Also, 31 is A
The 2 frequency divider 32 connected to the output of the FS13 uses the output of the 2 frequency divider 31 as one input, and the other input terminal is connected to the CPU 4.
It is an exclusive OR gate connected to the human power Pi of 0, and its output terminal is connected to the counter 33 and the CPU
40 input P3.

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 SGT output of the crank angle sensor 17 is input; is input. 51 is a waveform shaping circuit, and a crank angle sensor 17
The SGC output of is input, and the output is input to the port of the CPU 40. Start switch 19 is interface 4
6 to the CPU 40 boat. Also, 3B
is a timer connected to the interrupt power P5, 39 is an A/D converter that A/D converts the battery voltage V and outputs it to the CPU 40, 43 to 46 are the CPU 40 and drivers 47 to 5
0 and the outputs of the drivers 47 to 50 are connected to the injector 14, respectively.

Next, the operation of the fuel control device shown in FIG. 2 will be explained. The output of the AFS 13 is frequency-divided by a two-frequency divider 31 and input to a counter 33 via a gate 32 controlled by the CPU 40. Counter 33 measures the period between the falling edges of the output of gate 32. The CPU 40 interrupts the falling edge of the gate 32 by the human power P3, and the AFS
Interrupt processing is performed every time the output pulse period of l3 or this frequency is divided by two, and the period of the counter 33 is measured. The output of the water temperature sensor 18 is converted into a voltage by the interface 34, and converted into a digital value by the A/D converter 35 at predetermined time intervals and input to the CPU 40. The SGT output of the crank angle sensor 17 is input to the interrupt input P4 of the CPU 40 and the counter 37 via the waveform shaping circuit 36. The CPU 40 performs an interrupt process every time the SGT output of the crank angle sensor 17 rises, and detects the period between the rises of the SGT output from the output of the counter 37. Also, this S
The SGC signal of the crank angle sensor 17 is checked every time GT rises, and the compression stroke of the Nα1 cylinder is detected. C
If the output of the interface 46 is H, the PU 40 determines that the start switch 19 is on. The timer 3 generates an interrupt signal to the interrupt P5 of the CPU 40 at predetermined intervals. The A/D converter 39 converts the battery voltage into A/DI, and the CPU 40 takes in data on this battery voltage at predetermined time intervals. This output is used by drivers 47 to 50.
Each injector 14 is sequentially driven via the injector 14.

Next, the operation of the CPU 40 will be explained using flowcharts shown in FIG. 4 and FIGS. 6 and 7. First, Figure 4 shows the CPU 40
When a reset signal is input to the CPU 40, the RAM 42, human output port, etc. are initialized at step 100, and the SGC is reset at step 101.
In step 102, the CPU 40
Set the cycle counter to 5 to count the number of strokes provided. In step 103, the simultaneous injection flag is cleared. In step 104, the output of the water temperature sensor 18 is A/D converted and stored in the RAM 42 as WT. In step 105, the panteri voltage is A/D
It is converted and stored in the RAM 42 as VB. Step 1
In 06, the circumference of crank angle sensor 17! 'Jl TR Calculate 30/Ti+ and calculate the rotation speed N0.

Load data AN and rotation speed N, which will be described later in step 107,
From this, AN, N, /30 are calculated, and the output frequency F of the AFS 13 is calculated. In step 108, a basic driving time conversion coefficient is calculated from the output frequency F, which is set for F as shown in FIG. In step 109, the conversion coefficient is corrected using the water temperature data WT, and the drive time conversion coefficient is stored in the RAM 42 as: In step 110, the data table f3 stored in advance in the ROM 41 is mapped from the battery voltage data VB, and the wasted time T11 is calculated and stored in the RAM 42.

After the process in step 110, the process in step 104 is repeated again.

FIG. 6 shows the interrupt processing for the output signal of the interrupt P3, that is, the AFSL3.In step 201, the output T of the counter 33 is detected and the counter 33 is cleared. This T
, is the period between the rises of the gate 32. Step 20
2, the frequency u T F is set as the output pulse frequency o T s and R
AM42, and in step 203, the remaining pulse data PIl is added to the integrated pulse data P. Step 2
In 04, set the remaining pulse data PIl to 156,
In step 205, Pl is inverted. Step 205
After processing, interrupt processing is completed.

FIG. 7 shows the output of the CPU 40 based on the output of the crank angle sensor 17.
In step 301, the period between the rises of the crank angle sensor 17 is read from the counter 37, stored in the RAM 42 as the period TII, and the counter 37 is cleared. do. If there is an output pulse of the AFS 13 within the period T in step 302, then in step 303 the time difference Δt-tow to+ between the time tel of the immediately preceding output pulse of the AFS 13 and the current interrupt time tax of the crank angle sensor 17 is calculated. However, this is defined as the period T, and if there is no output pulse of the AFS 13 within the period T, the period T is defined as the period T.

In step 305, the time difference ΔL is converted into output pulse data ΔP of the AFS 13 by calculating 156 X T s /Ta. That is, the pulse data ΔP is calculated assuming that the previous output pulse period of the AFS 13 and the current output pulse period of the AFS 13 are the same. In step 306, if the pulse data ΔP is smaller than 156, step 3
If it is larger, ΔP is clipped to 156 in step 307. In step 308, the remaining pulse data Pa
The pulse data ΔP is frozen and calculated as new remaining pulse data ΔP. In step 309, the remaining pulse data P
If a is positive, proceed to step 313; otherwise, the calculated value of pulse data ΔP is too large than the output pulse of AFS13, so in step 310 pulse data ΔP is adjusted to pH
The remaining pulse data is set to zero in step 312. In step 313, the integrated pulse data P,
The pulse data ΔP is added to the sum of the pulse data ΔP to obtain new integrated pulse data P. This data Pe 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, a calculation corresponding to equation (1) is 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 P, K, A N + are calculated as 2·P, is calculated, and the result is set as the current new load data AN. In step 315, if the load data AN is larger than the predetermined value α, it is clipped to α in step 316 to prevent the load data AN from becoming too large than the actual value even when the engine 1 is fully opened. In step 317, the integrated pulse data P is cleared. In step 317a, the count value of the cycle counter is incremented by -1'01. In step 318, it is determined that S G C (cylinder identification signal) is H or not, and during the compression stroke of the cylinder of seed 1, S
Since GC is H, the process proceeds to step 320 to clear the cylinder counter, and in step 321 the SGC input cuff is flagged, and the process proceeds to step 322. If SGC is L, the cylinder counter is incremented by 1 in step 319.

In step 322, it is determined whether the simultaneous injection flag is set, and in step 323, it is determined whether the cycle counter is zero. If the simultaneous injection flag is set and the cycle counter is zero, or if the simultaneous injection flag is cleared. If so, proceed to step 324. If the cycle counter is not zero, the program is terminated. In step 324, it is determined whether or not the starting switch 19 is on, and if it is on, that is, at the time of starting, in step 325, drive time data, that is, pulse width Tc is determined from the water temperature data WT, and the starting switch 19 is determined.
is off, in step 326 the drive time data T,
is calculated as T + =AN-K + + Ta.

Also, in step 327, T,=TC+TD is calculated, and if the simultaneous injection flag is cleared in step 328, this T, is calculated for each injector 1 in step 329.
4, the four injectors 14 are simultaneously triggered in step 330 to simultaneously drive the four injectors 14, and a simultaneous injection flag is set in step 331. Further, in step 332, T in step 326, or in the case of simultaneous injection flag sensor 1-, T in step 327 is set in each injector 14, and the process proceeds to step 333 and subsequent steps.

That is, when the counter cylinder is O, the N114 injector 14 is driven, when the counter cylinder is 1, the Nα3 injector 14 is driven, and when the counter cylinder is 2, the Nα3 injector 14 is driven.
4, otherwise drive the injector of S1.

As mentioned above, injector 1 for each cylinder of engine 1
4, and each injector 14 is driven once for each intake of each cylinder, all the injectors 14 are driven at the same time at the beginning of startup, and then each injector 14 is not driven until the cycle counter reaches zero ( (If the injectors I4 are driven, there is a risk that the amount of fuel will be excessive.) Once the cycle counter reaches zero, each injector I4 is thereafter driven sequentially. This situation is shown in Figure 3.
(a) is the SGT output of the crank angle sensor 17, (b) is the SGC output, (C) is the output of the cylinder counter, (Φ ~
((2) shows the drive pulse of each injector 14, (5) shows the output of the key switch, and (i) shows the output of the cycle counter.

FIG. 8 shows the timing when the frequency division flag is cleared in the processing of FIG. 4 and FIGS. 17
shows the SGT output of (C) shows the remaining pulse data Po, which is set to 156 every time the frequency divider 31 rises and falls (the rise of the output pulse of the AFS 13), and every time the crank angle sensor 17 rises, for example, Pfii=P11-+
The calculation result is changed to 56xTs/TA (this corresponds to the processing in steps 305 to 312). (d) shows a change in the integrated pulse data Pa, and shows how the remaining pulse data P is integrated each time the output of the frequency divider 31 rises or falls.

(Effects of the Invention) As described above, according to the present invention, in a fuel control device that performs sequential injection, all injections are driven simultaneously only once at startup, and fuel supply is performed smoothly from the time of startup. , the starting characteristics can be improved.

Furthermore, since sequential injection is started after a predetermined stroke of the engine, excessive supply of fuel is prevented and good air-fuel ratio control can be performed.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a fuel control device according to the present invention, and FIG.
FIG. 3 is a configuration diagram showing a specific example of the fuel control device for the internal combustion engine, FIG. 3 is a time chart showing the operation of the fuel control device according to the present invention, and FIGS. FIG. 7 is a flowchart showing the operation of the fuel control device for an internal combustion engine according to an embodiment of the present invention; FIG. 5 is a diagram showing the relationship between the basic driving time conversion coefficient and the AFS output frequency of the fuel control device for the internal combustion engine; FIG. 8 is a timing chart showing the timing of the flow of FIG. 6.7. DESCRIPTION OF SYMBOLS 1... Engine, 13... Air flow sensor (Karman vortex flowmeter), 14... Injector, 15...
Intake pipe, 17... Crank angle sensor, 19... Start switch, 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 (1)

[Claims] (1) intake air amount detection means for detecting the intake air amount of the engine;
In the fuel control device for an internal combustion engine, the control means includes a control means for sequentially applying a drive signal to each injector provided for each cylinder with a pulse width corresponding to an output of an intake air amount detection means, with reference to the specific cylinder. A fuel control system for an internal combustion engine, characterized in that the means drives each injector simultaneously only once at the beginning of engine startup, and sequentially applies a drive signal to each injector after a predetermined stroke of the engine.