JPH0121333B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a fuel-injected internal combustion engine (hereinafter referred to as EFI).
The present invention relates to a fuel control device for an engine (referred to as an engine), and particularly to a device for correcting the amount of fuel injected during acceleration. As is well known, in EFI, engine parameters such as engine speed (hereinafter abbreviated as Ne), throttle valve opening (hereinafter abbreviated as θth), and suction negative pressure (hereinafter abbreviated as PB) The fuel amount is controlled by opening the nozzle for a period of time determined based on this and injecting fuel from the nozzle at a constant pressure. In such an EFI engine, when accelerating, a relatively rich air-fuel ratio is required compared to when cruising. For this reason, if only normal fuel quantity control is used, the air-fuel ratio required during acceleration becomes too lean, making it impossible to obtain the output (horsepower) required for acceleration, which tends to cause a temporary decrease in output and misfires. It has the disadvantage of being. In order to improve the above-mentioned drawbacks, if the increase rate of θth exceeds the planned value, temporary addition of fuel is performed independently of the normal basic fuel injection, or if the increase rate exceeds the planned value. It has been proposed that the addition should be continued while the
(Refer to Publication No. 9740 and Japanese Patent Application Laid-open No. 112828/1983). Hereinafter, such a conventional example will be explained with reference to FIG. Matrix memory 1 contains Ne and one of the other engine parameters (θth, PB, etc.) (in the illustrated example
A required basic fuel amount, that is, a basic fuel (injection time) signal Ti, is stored in advance with PB) as a parameter. The basic fuel signal Ti read out from the memory 1 in accordance with the input Ne and PB is input to the register 5 and presets the preset down counter 6. Preset down counter 6 is controlled by sequence timer 7. Sequence timer 7
is controlled by the Ne signal, controls the preset operation and counting operation of the preset/down counter 6, and sets the flip-flop 9 at a timing determined in advance with respect to the Ne signal. Further, although not shown, the sequence timer 7 supplies necessary timing signals and clock signals to all device blocks to be described later. The output of flip-flop 9 is outputted through OR gate 10, which energizes a fuel injection solenoid (not shown) to open a nozzle (not shown) and inject fuel at a constant pressure. When the count of the preset down counter 6 advances and reaches 0, the 0 detector 8 generates an output to reset the flip-flop 9 and stop fuel injection. As described above, fuel injection is performed for a time corresponding to the basic fuel signal Ti. On the other hand, the value of θth is stored in the first register 14 at every scheduled sampling time interval Δt by the sampling signal from the sequence timer 7,
The contents of the first register 14 are transferred to the second register 15 at the next sampling. That is, θth(i) at the current sampling time is stored in the first register 14 as
Further, θth(i-1) at the time of sampling immediately before that is stored in the second register 15, respectively. First,
A shift register can be used as the second register. The contents of both registers 14 and 15 are stored in a subtracter 16.
The difference Δθth is divided by Δt in the divider 13 to calculate the rate of increase. Increase rate △
θth/Δt is applied to comparator 17. As can be seen from the above explanation, the first and second registers 14, 15
Also, a differentiator can be used in place of the subtracter 16 and divider 13. As shown in FIG. 2A, the comparator 17 is set with three reference values, namely an acceleration increase reference value B, a cruise upper limit value +C1, and a deceleration reference value -C2, and the input △θth/△t According to the value of , the area is divided into areas as shown in the figure and Table 1, and three types of corresponding signal outputs are generated.

[Table] When △θth/△t exceeds the acceleration increase reference value B,
When the K1 signal is output, flip-flop 18 is set. As mentioned above, the basic fuel signal read out from matrix memory 1 according to Ne and PB
Ti is compared with a limit value Tlim set by a limit value setter 21 in a comparator 22 . When Ti>Tlim, the gate 19 is closed; otherwise, the gate 19 is opened. Therefore, when Ti>Tlim, the temporary (or one shot) fuel increase correction described below is prohibited. When the gate 19 is open, that is, when Ti<Tlim,
When flip-flop 18 is set, its output passes through gate 19 to trigger monomulti 20. The output pulse of monomulti 20 starts preset down counter 21 and sets flip-flop 24. At this time, the preset down counter 21 is set with a temporary fuel increase correction output generated from the function generator 22 in accordance with Δθth/Δt. In this case, the function generator 22 may be omitted and the temporary correction output may be set to a fixed value. The counter 21 is clocked by the preset amount.
Counting down causes zero detector 23 to produce an output, so flip-flop 24 is reset. As a result, the flip-flop 24 produces an output for a time Ts corresponding to the output of the function generator 22, which is superimposed on the basic fuel signal Ti via the OR gate 10. Therefore, a temporary increased correction supply of fuel is performed for the above-mentioned period of time. In other words, as shown in the timing diagram of Fig. 3, when the value of △θth/△t exceeds the reference value B (a in the figure), the signal is activated at a timing independent of the original basic fuel signal Ti (b in the figure). A correction increase signal Ts (FIG. 3(c)) is generated. This increases the amount of fuel supplied and the engine output, so smooth and sufficient acceleration can be achieved. The reason why temporary addition correction is prohibited when the basic fuel signal Ti exceeds the limit value is when Ti is larger than a certain level - that is, when accelerating under a condition where the load exceeds a certain level, temporary addition is necessary based on experience. This is because they do not. Further, the amount of the temporary addition correction, that is, the output of the function generator 22 is predetermined within a range in which the amount of addition fuel is too large, causing the plug to fog, causing a misfire, and causing a decrease in output. Moreover, although the above example shows that the temporary addition correction is performed only once, this increase can also be performed in two or more times. To do this, for example, the preset counter 21 may be started a predetermined number of times, and the flip-flop 24 may be set using an output obtained by delaying the output of the monomulti 20 by an appropriate time (for example, the basic fuel injection cycle at that time). Of course, at this time the function generator 22
The output of should be kept small accordingly. The value of △θth/△t decreases, and the cruise upper limit value +
When reaching the cruise region below C1 or the deceleration region below deceleration reference value - C2, the comparator 17 outputs a signal.
CR and DL are output. These signals are applied to flip-flop 18 through OR gate 28, thereby resetting flip-flop 18. Incidentally, in reality, the value of Δθth/Δt often fluctuates around the reference value B, and if a temporary addition is performed every time B is exceeded, fuel will be in excess, causing a misfire. However, in the fuel correction device shown here, if △θth/△t is before and after B,
Even if it fluctuates, the state of the flip-flop 18 does not change unless the voltage drops below +C1. Therefore, the monomulti 20 does not generate any output, no temporary addition of fuel is performed, and a misfire caused by the plug being covered is completely prevented. By temporarily adding fuel as described above, it is possible to quickly and reliably accelerate the engine, but if the timing of temporary addition and the timing of basic injection partially or completely overlap, the addition There is a risk that the effectiveness of the product may decrease or disappear altogether. For this purpose, in this fuel correction device, the clock Cl is supplied to the preset/down counter 6 via the AND gate 25, and the gate 25 is controlled by the temporary addition signal, that is, the inverted output of the flip-flop 24. I have to. According to such a configuration, the clock supply to the preset/down counter 6 is stopped while the fuel temporary addition signal is being output, so if no counting is performed and the two signals overlap, The basic injection timing will be delayed by that amount. Therefore, the temporary addition is always performed reliably. However, in the fuel correction device illustrated and explained above, the value of △θth/△t is in the acceleration region (B or more).
After dropping from to the cruise region (below +C1),
When the vehicle rises again to the acceleration region, fuel is temporarily added each time. Therefore, for example, if the driver repeatedly opens and closes the throttle valve rapidly while hesitating whether to accelerate or not, or by revving the engine when starting the engine, etc. △θth／△
When the value of t moves back and forth between B or more and +C1 or less,
Since a temporary addition is made each time the value B is exceeded, the amount of fuel supplied becomes excessive, which tends to cause fogging of the plug and misfire, which has the drawback of deteriorating acceleration performance. Also, as is clear, such a tendency becomes even more remarkable when the acceleration rate is continuously increased while the acceleration rate exceeds the predetermined value. The object of the invention is to provide an EFI without the drawbacks mentioned above.
An object of the present invention is to provide a fuel correction device for an engine. For this reason, in the present invention, from the time the engine enters the cruise state until the scheduled time has elapsed, in other words, when the cruise state has not continued beyond the scheduled time, even if the engine is not in the acceleration state. A means for prohibiting temporary addition is added to the fuel correction device described above. Furthermore, simply prohibiting temporary addition as described above tends to reduce the re-acceleration performance in acceleration-deceleration-re-acceleration situations, so in order to prevent this, the present invention provides It is also possible to further add means for canceling the temporary fuel addition prohibition when a deceleration state is detected after acceleration. FIG. 4 is a block diagram of essential parts of an embodiment of the present invention, and the same reference numerals as in FIG. 1 represent the same or equivalent parts. When the engine is in the cruise state, comparator 17 outputs a CR signal, so flip-flop 18 is reset. Since there is no reset signal which is the inverted input of the CR signal from the inverter 42, the preset counter 41 counts the engine pulses Ne and sends a set signal to the flip-flop 43 if the cruise state continues for more than the scheduled time. supply This opens the AND gate 44. On the other hand, since the DL signal of the comparator 17 is not output when the engine is in the cruise state, the inverted signal from the inverter 46 triggers the one-shot multi 45, puts the flip-flop 47 in the set state, and also opens the AND gate 48. . When the engine is accelerated and Δθth/Δt exceeds +C1, the CR signal disappears, so the preset counter 41 is reset. However, at this time flip-flop 43 does not reverse its state.
When .DELTA..theta.th/.DELTA.t exceeds B and the state is accelerated and the K1 output is generated from the comparator 17, the K1 signal is applied to the set input terminal of the flip-flop 18 via the AND gates 44 and 48 and the OR gate 49. This sets flip-flop 18 and performs fuel summing as described above with respect to FIG. Flip-flops 43 and 47 are monomulti 2
Since it is reset by the output of 0, it is reset simultaneously with the start of the above-mentioned temporary addition operation, and AND gates 44 and 48 are closed. Next, when the engine changes from the acceleration state to the cruise state, the comparator 17 produces a CR output, so the flip-flop 18 is reset, while the preset counter 41 starts counting Ne pulses. Until the count value of the preset counter 41 reaches the set value, that is, after the engine transitions from the acceleration state to the cruise state, until the scheduled time elapses, the engine will return to the acceleration state without reaching the deceleration state. Then, comparator 17 is K1
Output a signal. However, at this time, the preset counter 41 does not generate an output, so the flip-flop 43 is in the reset state, the AND gate 44 is in the closed state, and one AND gate 48 is also closed, so the K1 signal is output from the flip-flop. 18 cannot be set, and temporary addition of fuel during acceleration is prohibited. On the other hand, if the engine is temporarily decelerated before the preset counter 41 reaches the set value, the flip-flop 18 is reset by the DL signal from the comparator 17. Next, when the engine shifts to the cruise state, the
Since the DL signal disappears, the one shot multi 4
5 is triggered and flip-flop 47 is set. Therefore, AND gate 48 is opened. Therefore, the engine then accelerates,
When the K1 signal is output from the comparator 17,
K1 signal is AND gate 48 and OR gate 4
9 to the set input terminal of flip-flop 18. As a result, the fuel acceleration temporary correction similar to that described above is executed. As described above, according to the present invention, △θth/△t
Even if engine acceleration is detected from the value of Alternatively, even if the engine is revved up when starting the engine, fogging of the plug and misfires caused by this are prevented, and acceleration performance is improved.
Furthermore, even within the scheduled time, once the engine is in a deceleration state, the temporary addition prohibition is canceled, so in such a case, sufficient acceleration performance can be achieved. Note that the above-mentioned temporary addition prohibition cancellation is not necessarily necessary, and can be omitted in some cases. In this case, flip-flop 4 in FIG.
7. The inverter 46, AND gate 48, and OR gate 49 can be omitted. The present invention illustrated and described above can also be implemented using a computer such as a microcomputer. A flowchart in this case is shown in FIG. 5, and the calculation contents in each step S1 to S12 will be explained below. S1...Read the necessary data such as Ne, θth, dθth/
Calculate dt. S2...Whether dθth/dt is smaller than the reference value + C1,
That is, it is determined whether the engine is in the cruise range. If Yes, proceed to step S3; if No, proceed to step S5. S3...Determine whether dθth/dt is smaller than -C2. If No, the engine is in the cruise range, so the process proceeds to step S4; if Yes, it is determined that the engine is in the deceleration area, and the process proceeds to step S12. S4, S4a...Add 1 to the contents of the counter. S5...It is determined whether the K2 flag is 1, that is, whether the deceleration state has been reached before that. Initially, since the deceleration state is not passed, the answer is No, and the process proceeds to step S6. If yes, step
Jumps to S7 S6... Checks whether the contents of the counter are greater than or equal to n, that is, whether the cruise state has continued for n sampling periods. At first
Since the answer is No, return to step S1. When the cruise state is maintained for n sampling periods and the contents of the counter reach n, the process proceeds to step S7. S7... It is determined whether the basic fuel signal Ti read out according to the normal EFI control method is larger than a predetermined control value Tlim. If it is large, no temporary increase correction will be made, so
Return to the original. If it is small, proceed to step S8. S8... It is determined whether dθth/dt is larger than reference value B. If No, the temporary increase correction will not be performed and the original state will be restored. If Yes, proceed to step S9. S9... It is determined whether the K1 flag is set to 1, that is, whether the temporary increase correction has already been performed. Initially, since no temporary increase correction is performed, the determination result is No, and the process proceeds to steps S10 and S11. S10...Calculate a temporary correction amount according to the value of dθth/dt at that time, or read it from a table prepared in advance. Note that this value may be kept constant. S11...Outputs the increase correction signal calculated or read in the previous step S10, energizes the solenoid for that period of time, and performs fuel injection. At the same time, set the K1 flag to 1, set the K2 flag to 0, clear the counter, and return to the original state. S12... Sets the K2 flag to 1, indicating that the engine has passed the deceleration state, and returns to normal. Therefore, if the value of dθth/dt is less than or equal to B and more than -C2 for a period longer than the scheduled time after the last acceleration was performed, that is, if the engine cruise state continues, the computer calculation will proceed to step S1. →S2→S3→
S4→S1, or step S1→S2→S4a→…S8→
The loop of S1 is circulated, and the count value of the counter is greater than or equal to n. Furthermore, the K2 flag is 0 since the vehicle has not passed through the deceleration state. Next, depending on the acceleration state, dθth/dt becomes the reference value B
When it becomes larger, steps S2 to S4a→S5...
Temporary fuel addition is performed on the route S8→S9→S10→S11. Furthermore, if the value of dθth/dt becomes B or more before the count value of the counter reaches n or more, i.e., the acceleration state is reached, the flow of computer calculations goes from step S1 to step S2.
→S4a→S5 and reaches step S6, but since the determination result here is No, the process returns to step S1 again and the temporary addition of fuel is not performed. If the engine is decelerated and then accelerated before the count value of the counter reaches n or more,
During deceleration, in the flow of steps S1 → S2 → S3 → S12,
Set the K2 flag to 1 to indicate that the deceleration state has passed. Next, when the acceleration state is reached, the flow of calculation proceeds from step S1 → S2 → S4a → S5, and since the judgment at step S5 becomes Yes, the process jumps to step S7, and if other necessary conditions are satisfied, For example, temporary addition of fuel is performed in the same way as in the case described above. If the temporary increase correction is to be performed twice or more, for example, the engine rotation period may be calculated in step S11, and the fuel injection signal may be output a plurality of times at that time interval. As described above, the same effects as those described above with reference to FIG. 4 can be achieved by arithmetic control using a computer.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an EFI engine fuel correction device as a prior art of the present invention, and FIGS.
The figure is a time chart for explaining its operation, part 4.
The figure is a block diagram of a main part of an embodiment of the present invention, and FIG. 5 is a flowchart of an embodiment in which the present invention is implemented by computer control. 1... Matrix memory, 6, 21, 41...
...Preset down counter, 7...Sequence timer, 8, 23...0 detector, 9, 18, 2
4,43,47...flipflop, 13...
Divider, 14, 15...Register, 16...Subtractor, 17...Comparator, 20...Monomulti, 22
...Function generator.

Claims (1)

[Scope of Claims] 1. A device that determines a basic fuel injection time based on at least two engine parameters such as engine speed, throttle valve opening, and suction negative pressure, and a device that opens a nozzle during the basic fuel injection time. , a device that injects fuel at a constant pressure, a device that obtains the rate of increase in throttle valve opening, and a device that temporarily opens a nozzle for a predetermined time when the rate of increase exceeds an acceleration increase reference value. A fuel correction device for a fuel-injected internal combustion engine having a device for additionally injecting fuel, wherein the state in which the increase rate is below an acceleration increase reference value and above a smaller deceleration reference value continues for more than a scheduled time. A fuel correction device for a fuel injection type internal combustion engine, further comprising a device for prohibiting the fuel addition injection when the fuel addition injection is not performed. 2. A device that determines a basic fuel injection time based on at least two engine parameters such as engine speed, throttle valve opening, and suction negative pressure, and a device that opens a nozzle during the basic fuel injection time and injects fuel at a constant pressure. A device for injecting fuel, a device for obtaining an increase rate of throttle valve opening, and a device for additionally injecting fuel by temporarily opening a nozzle for a predetermined time when the increase rate exceeds an acceleration increase reference value. a fuel correction device for a fuel-injected internal combustion engine, which has the following: when the state in which the increase rate is less than or equal to an acceleration increase reference value and greater than or equal to a smaller deceleration reference value continues for more than a scheduled time; A fuel injection system comprising: a device for prohibiting additional fuel injection; and a device for canceling the prohibition when the increase rate decreases below the deceleration reference value after the additional fuel injection has been performed. Fuel correction device for internal combustion engines.