JPH01116261A - Fuel injection control device - Google Patents

Abstract

PURPOSE:To prevent a delay of injection end, based on calculating the optimum fuel injection residual time, by comparing the fuel injection time, accumulated from a fuel injection start, with the optimum fuel injection time and performing fuel injection till both the accumulated fuel injection time and the optimum fuel injection time agree. CONSTITUTION:A CPU13 calculates a fuel injection start and the optimum fuel injection time being based on an intake pressure, intake air temperature, engine speed and a crank angle, resetting a counter 10 while setting the optimum fuel injection time to a latch 11 when injection is started. A comparator 12 compares the optimum fuel injection time, set to the latch 11, with the fuel injection time accumulating a clock from an oscillator 14 input through an AND gate 14a during the fuel injection, and the fuel injection is performed till both the optimum fuel injection time and the accumulated fuel injection time agree.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fuel injection control device used in automobile engines and the like.

Conventional Technology Generally, in this type of fuel injection control device, a microcomputer calculates the optimum fuel injection time based on data such as the pressure in the intake pipe and the engine rotation speed, and calculates the optimum fuel injection time from this optimum fuel injection time and the previous ignition timing. The remaining fuel injection time is calculated based on the cumulative injection time, and the opening time of the fuel injection valve is controlled according to this remaining fuel injection time.

Conventionally, this type of fuel injection control device has a CPU (central processing unit) 52 for calculating the optimum fuel injection time, a down counter 51 for calculating the remaining fuel injection time, and a CPU 52, as shown in FIG. is down counter 51
It is roughly composed of a tri-state buffer 53 for reading out the value (output of the Q terminal).

FIG. 7 is a flowchart for explaining the algorithm of the fuel injection interrupt processing routine of the CPU 52 of FIG.

In FIG. 7, when this fuel injection interrupt processing routine is started, the optimum fuel injection time is calculated in step 61, and in the following step 62, this fuel injection interrupt processing routine is started to perform the first fuel injection action after engine ignition. If it is the first fuel injection action after engine ignition, the process branches to step 63, sets the calculated optimal fuel injection time in the down counter 51, and ends this routine. .

On the other hand, in the case of a fuel injection time correction action, the process proceeds from step 62 to step 64, where the current remaining fuel injection time is read from the down counter 51, and in the subsequent step 65, the fuel injection time calculated in the previous fuel injection interrupt processing routine is read. The cumulative fuel injection time is calculated by subtracting the current remaining fuel injection time from the time.

In step 66, the optimum remaining fuel injection time is calculated by subtracting the cumulative fuel injection time from the optimum fuel injection time, and in the subsequent step 67, this optimum remaining fuel injection time is set in the down counter 51, and the routine ends.

By repeating this routine multiple times, the injector injects the optimal amount of fuel for one ignition.

Note that if the fuel injection time calculated in the current routine is smaller than the fuel injection time calculated in the previous routine, C=
is set in the down counter 51 as rOJ, which is the optimum fuel injection remaining time, and the fuel injection pulse is stopped.

Problems to be Solved by the Invention However, the conventional fuel injection control device described above has the following problems.

In FIG. 8, tl is the time when step 64 is performed, t2 is the time when step 67 is performed, and IG
If t is the optimal remaining fuel injection time calculated in step 66, originally the optimal remaining fuel injection time IG is calculated from time t1.
Although fuel injection should have ended at time T1 after time t has elapsed, fuel injection ends at time T2 when optimal fuel injection remaining time IGt has elapsed from time t2. Therefore, the processing time from step 64 to step 66 However, there is a problem in that an error occurs in the fuel injection time.

In order to solve the above problem, as shown in FIG. 9, the remaining fuel injection time is obtained by subtracting the processing time from step 64 to step 66 in step 68, and in the subsequent step 69, the value is entered in the down counter 51. There are known fuel injection control devices that set

However, in such a fuel injection control device, the first
0 As shown in Figure 11, there is no problem if the optimal remaining fuel injection time IGt is sufficiently large, but as shown in Figure 11, the optimal remaining fuel injection time IGt is shorter than the processing time from step 64 to step 66. In some cases, there is a problem that the fuel injection end time is delayed from the original time.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a fuel injection control device that can prevent a delay in the fuel injection end time caused by the process of calculating the optimal remaining fuel injection time from the optimal fuel injection time.

Means for Solving the Problems In order to solve the above problems, the present invention calculates the cumulative fuel injection time from the fuel injection start time, compares the optimal fuel injection time and the cumulative fuel injection time, and determines the optimal fuel injection time. The fuel injection pulse is output during the fuel injection time and the cumulative fuel injection time does not exceed the optimum fuel injection time.

Effect of the Invention With the above-mentioned configuration, the present invention is capable of correcting the fuel injection amount without calculating the remaining fuel injection time as in the conventional example. A delay in the injection end time can be prevented.

Example Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of main parts showing one embodiment of a fuel injection control device according to the present invention, FIG. 2 is a schematic block diagram showing the fuel injection control device of FIG. 1, and FIG. Figure and second
FIG. 4 is a schematic configuration diagram showing an engine system using the fuel injection control device shown in FIG.
The figure is a timing chart of main signals of the output section of the fuel injection control device of FIGS. 1 and 2.

FIG. 1 shows an output section 19 of the fuel injection control device, which includes a counter 10 for measuring cumulative fuel injection time data D3 by counting a clock S5, and an optimum fuel injection time calculated by the CPU 13. A latte 11 for storing the fuel injection time data D1 and outputting it as fuel injection time data D2 compares the cumulative fuel injection time data D3 from the counter lO with the fuel injection time data D2 from the latch 11, and calculates the cumulative fuel Injection time data D3
a comparator 12 that outputs a fuel injection pulse S1 during a time period when the fuel injection pulse S1 is small; an oscillator 14 that outputs a clock S4 that serves as a reference for counting by the counter 10; AND gate 14 outputs to counter 10 as S5
It has a.

Note that S2 is a reset signal that the CPU 13 outputs to the reset (RESET) terminals of the counter 11 and latch 11, respectively, and S3 is a reset signal that the CPU 13 outputs to the reset (RESET) terminals of the counter 11 and latch 11.
This is an injection amount write signal output to the ROAD) terminal.

In FIG. 2, 15 is a fuel injection control device, and this fuel injection control device 15 is an A/D converter that converts various analog signals S6 necessary for controlling the engine such as fuel injection time into digital signals. 16, an input port 17 into which various digital signals S7 necessary for controlling the engine are input, and a CPU (central processing unit) 13 for controlling fuel injection time and the like as described later.

The fuel injection control device 15 also includes a ROM (read only memory) 18 in which execution programs for the CPU 13 and data for the CPU 13 to perform various calculations are stored, and an output section 19 that outputs the injection pulse S1 as described above. , and a timer 20 that outputs a signal S8 to the CPU 13.

21 is a signal S9 synchronized with the rotation, such as a top dead center signal, by a mechanism 22 such as a crankshaft that rotates in synchronization with the rotation of the engine, and indicates whether the engine is in the intake, compression, explosion, or exhaust process. 2-pit signal Slo, 8 indicating
This is a pulse sensor that outputs 11 to the CPU 13.

As shown in FIG. 3, the signals S6 and S7 input to the A/D converter 16 and the input port 17 are data such as the intake pressure and intake air temperature in the intake pipe 24 of the engine 23. The injection pulse S1 output from the engine 23 is output to the injector 25 of each cylinder of the engine 23 and is used to control the opening time of the valve.

Next, the operation of the embodiment according to the above configuration will be explained with reference to FIGS. 4 and 5.

FIG. 4(a) shows the signal S10 from the pulse sensor 21,
The CPU is activated by S11 at the top position of the fuel injection possible range of the engine 23 (the start time of the previous explosion process).
13 interrupt processing routine (reset routine),
In step 31, the counter 10 and latch f11 in FIG. 1 are reset by the reset signal S2 (time tl in FIG. 5), and the interrupt processing is terminated.

At this time, since the cumulative fuel injection time data D3 and the optimal fuel injection time data D1 are both 10'', the comparator 12 does not output the fuel injection pulse S1.

Figure 4 (b) shows the signal S9 from the pulse sensor 21.
This is an interrupt processing routine (fuel injection control routine) started by Step 32, in which it is determined whether or not to start fuel injection and correct the fuel injection time based on information on the engine speed and crank position of signal S9, If neither is done, this routine ends.

When starting fuel injection and correcting fuel injection time,
Proceeding from step 32 to step 33, the input signal S6,
The optimal fuel injection time data D1 is calculated from S7 and the data in the ROM 18, and in the subsequent step 34, the optimal fuel injection time data D1 is written into the latte 11 by the write signal S3, and this routine ends.

In FIG. 5, the latch 11 outputs fuel injection time data D2 corresponding to the optimal fuel injection time data Dl written by the CPU 13 from time t2, and at this time t2, the cumulative injection time data output by the counter 10 is output. Since D3 is "0", the fuel injection pulse S1 output by the comparator 12 becomes high level.

While this fuel injection pulse 81 is being output, the masking of the clock S4 from the oscillator 14 is canceled by the AND gate 14a, so the counter 10 starts counting the tally clock S5 from the AND gate 14a.
It is output to the comparator 12 as cumulative injection time data D3.

In addition, FIG. 5 shows that the CPtJ13 corrects the optimum fuel injection time data Dl to decrease at times t3, t4, and t5, and the latch 11 adjusts the fuel injection time according to the corrected optimum fuel injection time data Dl. A case where data D2 is output is shown. In this case as well, the comparator 12 continues to output the fuel injection pulse Sl, and the counter 10 continues to count.

When the counter 10 continues counting and the cumulative injection time data D3 increases and the cumulative injection time data D3 exceeds the fuel injection time data D2, the comparator 12 stops outputting the fuel injection pulse Sl (time ts).

In addition, as shown at time t6, the CPU 13 corrects the optimum fuel injection time data D1 so that it becomes larger, the comparator 12 restarts outputting the fuel injection pulse 81, and the counter 10 restarts counting to increase the cumulative injection time. When the data D3 increases and exceeds the fuel injection time data D2, the comparator 12 stops outputting the fuel injection pulse Sl (time t7).

Incidentally, the intake valve 26 (Fig. 3) of the engine 23 is closed at time 15.
~Opens near t7 (start of the inhalation process), time t7
Close after (start of the compression process).

Therefore, according to the above embodiment, the counter 10 counts the cumulative injection time D3, and the comparator 12 uses the cumulative injection time D3 and the latch 11 to calculate the fuel injection time D2.
In order to output the fuel injection pulse Sl while the cumulative injection time D3 does not exceed the fuel injection time D2, the remaining time of the previous fuel injection is read from the down counter 51 as shown in FIG. There is no delay in the completion of fuel injection due to the processing time required to set the optimum remaining fuel injection time.

Furthermore, in the above embodiment, since control is performed using the actual optimum fuel injection time D1, there is no delay in the end of fuel injection due to processing time as shown in FIG.

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention counts the cumulative fuel injection time from the fuel injection start time, compares the optimal fuel injection time with the cumulative fuel injection time, and determines whether the cumulative fuel injection time is between the optimal fuel injection times or not. Since the fuel injection pulse is output while the cumulative fuel injection time does not exceed the optimum fuel injection time, the fuel injection amount can be corrected without calculating the remaining fuel injection time as in the conventional example. , it is possible to prevent a delay in the fuel injection end time caused by the process of calculating the optimal remaining fuel injection time from the optimal fuel injection time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of main parts showing one embodiment of a fuel injection control device according to the present invention, FIG. 2 is a schematic block diagram showing the fuel injection control device of FIG. 1, and FIG. Figure and second
FIG. 4 is a schematic configuration diagram showing an engine system using the fuel injection control device shown in FIG.
The figure is a timing chart of the main signals of the output section of the fuel injection control device shown in FIGS. 1 and 2, FIG. 6 is a block diagram of main parts showing a conventional fuel injection control device, and FIG. 6
FIG. 8 is a flowchart for explaining the algorithm of the fuel injection control device shown in FIG. Flowcharts for explanation, FIGS. 10 and 11 are explanatory views of the operation of the fuel injection control device of FIG. 9, respectively. 10... Counter, 11... Latch, 12... Comparator, 13... CPU (central processing unit), 14
... Oscillator, 15 - Fuel injection control device, 19...
・Output section. Name of agent: Patent attorney Toshio Nakao Haka 1 person No. 3
Figure 4 (a)
(TJ) ; Figure 7 Figure 8 T1 1 Figure 9 Figure 10 Itd' = Iert - (tz-it) Figure 1I

Claims (1)

[Claims] means for calculating an optimum fuel injection time; means for calculating a differential fuel injection time from a fuel injection start time; and means for comparing the optimum fuel injection time and the cumulative fuel injection time; A fuel injection control device, characterized in that fuel is injected into the engine during an injection period during which the cumulative fuel injection period does not exceed the optimum fuel injection period.