JPS61272448A - Fuel injection controller for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent the generation of engine disorder due to the erroneous signal by installing a means for judging the propriety of the cylinder discriminating signal, means for stopping the reset operation and the second reset means which operates wen the counter value is equal to a prescribed value. CONSTITUTION:When it is judged from a crank angle sensor 4 that the cylinder discriminating signal (720 deg.) is input in the regular timing immediately after start, the injection starting time according to the cylinder discriminating signal is not varied by a reset stop means afterwards, and the fuel injection timing is controlled only by the input of the REF signal as the crank standard angle signal. In other words, when the count value of the REF signal is 6, clearing is performed by the second reset means, and injection is not carried out. While, when he count value is 1 or 4, each fuel injection start signal (e) is outputted, and a fuel injection valve 2 in A or B group is allowed to carry out injection by alternately changing the injection switching signal. Therefore, even in case of the erroneous operation of the cylinder discriminating signal due to noise, etc., normal injection is permitted.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a fuel injection control device for an internal combustion engine equipped with an electronically controlled fuel injection device.

<Prior Art> Examples of conventional fuel injection control devices include those shown in FIGS. 5 and 6, for example.

FIG. 5 is an overall configuration diagram, in which 1 is an engine (6 cylinders in this example), 2 is a fuel injection valve provided for each cylinder (
3 is an air flow meter, 4 is a crank angle sensor, and 5 is a control unit.

The air flow meter 3 measures the intake air flow rate and outputs a corresponding voltage signal using a potentiometer.

The crank angle sensor 4 is, for example, a distributor 40
The signal disk plate 42 is built into the distributor shaft 41 and rotates together with the distributor shaft 41, and a photoelectric detection section 43 is provided. Signal disc plate 42
A slit 44 for a 10 signal and a slit 45 for a 1200 signal are formed in the slit 4 for a 120' signal.
One of the slits 5 has a wide slit width and also serves as a 720° signal slit 45a. The photoelectric detection unit 43 detects these slits 44 and 45, and generates a pulse signal every 10 at the rotation angle of the engine crankshaft (hereinafter referred to as a PoS signal).
A pulse signal every 1200 seconds (hereinafter referred to as REF signal),
A pulse signal every 720° (hereinafter referred to as a 720° signal) is output.゛The control unit 5 reads the intake air flow rate Q based on the voltage signal from the air flow meter 3, and also counts the PO3 signal from the crank angle sensor 4 for a certain period of time to measure the rotation speed N, and calculates the basic injection pulse from both. Calculate the width 'rp = K - Q/N (K is a constant),
This is corrected with various correction coefficients C0EF and voltage correction numerator s to calculate the injection pulse width of Ti = Tp - COEF + Ts, which is 7200 obtained from the crank angle sensor 4.
The fuel injection start timing is set based on the signal and the REF signal, and the timing is set at °T every engine revolution.

Fuel injection valve 2 divided into two groups with a pulse width of
are driven alternately to perform fuel injection.

Next, the internal operation of the control unit 5 will be explained with reference to the block diagram of FIG. 6 and the timing chart of FIG. 7.

In FIG. 6, 11 is an A/D converter that A/D converts the output voltage of the air flow meter 3 to obtain a digital signal of the intake air flow rate Q, and 12 is an A/D converter that counts the PoS signal of the crank angle sensor 4 to detect the engine. The rotational speed measurement counter 13 that measures the rotational speed N calculates the basic injection pulse width Tp corresponding to the amount of fuel required for one rotation of the engine from Q and N, and corrects this as appropriate to obtain the injection pulse width Ti. , and A based on the REF signal of the crank angle sensor 4 and the 7200 signal.

8. Interchange the fuel injectors 2 divided into 2 groups.

This is a microcomputer (CPU) that outputs injection switching signals to drive each other.

Counter 14. Register 15. The comparator 16 is a circuit for setting the fuel injection start timing based on the REF signal and the 720° signal of the crank angle sensor 4. Counter 14 counts the number of REF signals and is reset by the 720° signal. The register 15 is set to 1 every time 7200 signals are input from the CPU 13, and to 4 when the REF signal is input three times thereafter. And counter 14
When the current value becomes equal to the set value of the register 15, the comparator 16 generates an output signal (fuel injection start signal) e.

This fuel injection start signal e causes the flip-flop 17 to
is set to make its output H level, and the fuel injection valve 2 is driven via the fuel injection valve driving power transistor Trs+Trh to start fuel injection.

In addition, counter 18. Clock 19. The register 20° comparator 21 is a circuit for continuing fuel injection for a period of time calculated by the CPU 13.

The counter 18 receives the fuel injection start signal e from the comparator 16.
It is reset by the clock 19 and counts pulses from the clock 19 at fixed time intervals. Ti from the CPU 13 is set in the register 20. When the count value of the counter 18 becomes equal to the set value of the register 20, the comparator 21 generates an output signal (fuel injection end signal) f.

This fuel injection end signal r causes the flip-flop 17 to
is reset to bring its output to L level, power transistors Try and Tr6 are turned off, and fuel injection by the fuel injection valve 2 is terminated.

On the other hand, the CPU 13 selects the transistor Trt based on the REF signal and the 7200 signal from the crank angle sensor 4.

Outputs an injection switching signal to the base of Trz. This injection switching signal indicates that the counter 14 and register 15 have a set value of 1.
H level when it matches with set value 4, L level when it matches with set value 4
level. In this way, when the injection switching signal is at H level, transistor Trlt-OFF, )transistor T
rz is turned ON, thereby turning the 5-transistor Tr3 to O.
Nl Turns off the transistor Tra, thereby turning off the transistor Trs at the output of the flip-flop 17.
The FF and transistor Tr are turned on to drive only the fuel injectors 2 of group B. When the injection switching signal is at the L level, only the fuel injection valves 2 of the A group are driven.

The above is known from Japanese Unexamined Patent Publication No. 57-28834.

<Problems to be Solved by the Invention> However, in such a conventional fuel injection control device, two fuel injection start timings are determined at a predetermined position state of a specific cylinder every cycle, as in the 7200 signal. As shown in FIG. 8, the cylinder discrimination signal (720' signal) is
There is a problem in that if a malfunction occurs due to external noise or the like and occurs in a position other than a predetermined cylinder, the injection timing will be shifted and the engine will malfunction.

Therefore, an object of the present invention is to eliminate the use of cylinder discrimination signals except immediately after starting, thereby preventing engine malfunctions caused by erroneous cylinder discrimination signals.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a crank reference angle detection means that outputs a crank reference angle signal at every predetermined crank angle, as shown in FIG. a cylinder discriminating means that outputs a cylinder discriminating signal in a predetermined position state of a specific cylinder every cycle; a counting means that counts a crank reference angle signal; and a resetting means that resets the count value of the counting means using the cylinder discriminating signal; A fuel injection control device comprising: a fuel injection start timing setting means for outputting a fuel injection start signal to start fuel injection from a fuel injection valve when the count value of the counting means is a predetermined value; determining means for determining whether the generation of the cylinder discrimination signal is correct or not for each occurrence of the cylinder discrimination signal; reset stopping means for stopping the operation of the resetting means upon normality determination by the determining means; A second reset means for resetting the count value is also provided.

In other words, the input of the cylinder discrimination signal is checked immediately after starting, and if the cylinder discrimination signal is input at the regular timing for every predetermined number of crank reference angle signals, the determination means determines that the cylinder discrimination signal is normal, and from then on The counting means is set by the cylinder discrimination signal by the reset stop means, so the injection start timing is not changed, and the second reset means resets the counted value only when the counted value of the counting means reaches a predetermined value; The fuel injection start timing is set only by the crank angle detection means without relying on the cylinder discrimination means.

<Example> An example of the present invention will be described below with reference to FIGS. 2 to 4.

FIG. 2 is a hardware configuration diagram, and the same elements as in FIG. 6 are given the same reference numerals. The difference from FIG. 6 is that the counter 14. Register 15. The comparator 16 is deleted. That is, this part is achieved by the software configuration within the CPU 13, and the setting of the flip-flop 17 and the reset of the counter 18 are performed using the output signal (fuel injection start signal) e from the CPU 14.

Explaining according to the flowchart in Figure 3, 11.
A REF signal counter memory is provided in the CPU 13 instead of the counter 14, and in step 1 (Sl in the figure), the CPU 13 waits for input of the REF signal, which is a crank reference angle signal, and performs a count amplification upon input. This part corresponds to the counting means. Next, in step 2, it is determined whether or not flag F, which will be described later, is 1. Immediately after starting, F=O, so proceed to step 3, and check whether a 720° signal, which is a cylinder discrimination signal, has been input. judge.

Immediately after starting and before the 720° signal is input, the process directly proceeds to step 14 and subsequent steps. After step 14, when the count value of the REF signal is 6, it is cleared and (step 14.1
5) When the count value of the REF signal is 1, the fuel injection start signal e is outputted, and the injection switching signal is set to H level to cause the fuel injection valves 2 of group B to inject (step 16.
17) When the count value of the REF signal is 4, the fuel injection start signal e is outputted, and the injection switching signal is set to the L level to cause the fuel injection valves 2 of the A group to inject (step 1).
8.19).

When a 720° signal is input when the REF signal is input,
Proceeding from step 3 to step 4, the 720° signal counter is counted up. Here, if the 7200 signal count value is not 2 or more, the REF signal count value is reset (set to 0) and the memory is set to 0 (steps 5 to 7). This part corresponds to the reset means. .

Next, in step 8, the count value of the REF signal is compared with the value in the memory, and if they match, the normal input counter is counted up (step 9). Next, in step 10, it is determined whether the normal input counter is 5 or more, and if it is less than 5, the process proceeds to step 14 and subsequent steps. If they do not match in step 8, clear the normal input counter in step 11,
Store the REF signal count value in memory and proceed to step 1.
Proceed to step 4 onwards.

If the normal input counter is 5 or more in step 10, flag F is set to 1 and the REF signal counter is set to 0 in order to ignore the 720° signal from now on (step 13). Incidentally, the portion from step 8 to step 10 corresponds to the determining means, and the portion to step 13 corresponds to the reset stop means.

In this way, at the same timing (72 times in 6 REF signals)
R when the 0° signal (1 time) occurs multiple times (5 times in this example) in a row.
Clear the EF signal and use REF when inputting the 7200 signal from now on.
(Clear only when the REF signal count reaches 6 without clearing No. 1.

That is, from the REF' signal count in step 1, the process proceeds to step 14 and subsequent steps via step 2, and when the count value of the REF signal is 6, it is cleared and the process proceeds to step 14.15.
), when the count value of the REF signal is 1, outputs the fuel injection start signal e and sets the injection switching signal to H level.B
Inject fuel injector 2 of the group (step 16.1
7) When the count value of the REF signal is 4, the fuel injection start signal e is output, and the injection switching signal is set to the L level to cause the fuel injection valves 2 of the A group to inject (step 18).
．． 19). Here, steps 14 and 15 correspond to the second reset means, and steps 16 to 19 correspond to the fuel injection start timing setting means.

<Effects of the Invention> As explained above, according to the present invention, when the cylinder discrimination signal is input normally, the injection timing is not changed based on the subsequent cylinder discrimination signal, but is based only on the crack reference angle signal. Since the injection timing is controlled, it is possible to achieve the effect that injection can be performed normally even if the cylinder discrimination signal malfunctions due to noise or the like.

[Brief explanation of the drawing]

Fig. 1 is a functional block diagram showing the configuration of the present invention, Fig. 2 is a hardware configuration diagram showing an embodiment of the invention, Fig. 3 is a flow chart, Fig. 4 is a time chart, and Fig. 5 is a system diagram. , FIG. 6 is a hardware configuration diagram showing a conventional example,
FIG. 7 is a time chart of the conventional example under normal conditions, and FIG. 8 is a time chart of the conventional example under abnormal conditions.

Claims (1)

[Claims] Crank reference angle detection means that outputs a crank reference angle signal at every predetermined crank angle; cylinder discrimination means that outputs a cylinder discrimination signal at a predetermined position state of a specific cylinder every cycle; and a cylinder discrimination means that counts the crank reference angle signal. a counting means; a reset means for resetting a count value of the counting means in response to a cylinder discrimination signal; and a fuel injection system for outputting a fuel injection start signal to start fuel injection from a fuel injection valve when the count value of the counting means is a predetermined value. A fuel injection control device for an internal combustion engine, comprising: a start timing setting means;
It is characterized by providing a reset stop means for stopping the operation of the reset means upon normality determination by the determination means, and a second reset means for resetting the count value of the counting means when the count value is a predetermined value. A fuel injection control device for internal combustion engines.