KR840001327B1 - Method of controlling fuel of internal combustion engine - Google Patents

Abstract

A fuel injection control system consists of a carburetor for mixing the air and fuel, a sensor for detecting O2 in the exhaust gas, and a microprocrocessor. Data regarding the desired air-fuel ratio is stored in the microprocessor memory. When the signals of the sensor and the data in the memory are conpared, control signal is generated according to the variation of the engine state. The carburetor receives the control signal and changes the current air-fuel ratio.

Description

Engine Fuel Control

1 is a diagram showing a configuration of an engine peripheral device.

2 is a block diagram of a control device for controlling the engine.

3 is a flowchart showing that task priority processing is performed by an interruption signal.

4 is a position explanatory diagram of a memory content of a RAM.

5 is a flowchart of level one.

6 is a flowchart of level two.

7 shows a flat map of the air-fuel ratio.

8 is a view showing a change in output of the O ₂ sensor.

9 is a diagram showing a relationship between an air-fuel ratio and an on duty ratio in a cylinder.

10 is a flowchart showing one embodiment of the present invention.

FIG. 11 is a flowchart for explaining the embodiment shown in FIG. 10 in detail.

12 shows a flat map of an air-fuel ratio.

13 is a waveform diagram corresponding to a change in operating conditions according to the present embodiment.

The present invention relates to a method for controlling fuel in an engine, and more particularly, to a method for controlling fuel in an engine for correcting fuel using an exhaust gas sensor.

The present invention relates to a control method of an internal combustion engine, and more particularly, to an electronic control method of an internal combustion engine having a vaporizer.

In recent years, with the increase of automobiles, exhaust gas measures have become a problem as part of pollution measures in terms of environmental pollution, and at the same time, measures for fuel economy have been taken at the request of energy saving. As one method of exhaust gas countermeasure, ternary catalysts are mostly used. This three-way catalyst exhibits the best catalytic effect when the air-fuel ratio of the mixer is at the theoretical air-fuel ratio. In order to effectively operate the three-way catalyst, for example, the engine speed of a vehicle is very close to about 6,000 revolutions at around 600 revolutions. The air-fuel ratio must always be controlled in a very narrow range near the early air-fuel ratio, over a wide range, and as its speed changes rapidly. For this reason, the exhaust gas sensor which detects the state of exhaust gas came to be used.

The air-fuel ratio control method of the engine is controlled by feeding back the detection signal of the O ₂ sensor using an O ₂ sensor that detects an oxygen concentration path in the exhaust gas.

And this air-fuel ratio control system enables relatively stable control when the engine speed is running at a certain value, i.e., when the vehicle speed of the vehicle is running at substantially constant speed under certain conditions. However, as is well known, the engine has driving modes such as warm driving, idling, acceleration, deceleration, and the like, and their driving state changes rapidly depending on the surrounding conditions. Therefore, for example, when an air-fuel ratio disturbance occurs due to a sudden change in the operating state of the engine, the disturbance is detected by an O ₂ sensor provided in the exhaust pipe. However, the time between the occurrence of this disturbance and the detection of the disturbance is the delay between the engine intake and exhaust and the exhaust gas flowing through the exhaust pipe and reaching the O ₂ sensor. after the exhaust change due to the disturbance to reach the O ₂ sensor O ₂ sensor is in since the sum with the time (T) (O ₂₎ number of sensor time constant) until the result in a predetermined electromotive force, only O ₂ sensor Feedback control has a drawback that it cannot follow the rapidly changing driving method.

Thus, in order to achieve a delay in detecting the exhaust gas of the O ₂ sensor or to improve the stability of the control, attempts have been made to convert the waveform including the proportional and integral to the output waveform of the O ₂ sensor and perform the integral control. In addition, it is impossible to accurately follow the operating conditions of complex engines.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel control method for an engine that can follow the air-fuel ratio with high precision even with a sudden change in the engine.

According to the present invention, in order to correct the past fuel supply amount to the engine according to the state of the exhaust gas, and to correspond to the change in the operating state of the engine, the fuel control signal based on the past operating state and the fuel control signal at the present time. Save the car. The fuel supply amount corrected in the state of the exhaust gas is corrected again by the obtained difference.

This basic idea is to find a new fuel supply amount by correcting the previously supplied fuel supply amount by the exhaust gas sensor output if the operating conditions do not change. On the other hand, when the operating conditions change, the fuel supply amount for the past operating conditions is most appropriately corrected by the exhaust gas sensor output, and based on the result corrected based on the exhaust gas sensor output, The base is corrected by the control amount of the corresponding fuel.

Specific examples will be described below with reference to the drawings.

The configuration of the engine is shown in FIG.

In the figure, 1 is an engine, 2 is a carburetor, 4 is an intake pipe, and 5 is an exhaust pipe. By operating the accelerator pedal not shown, the opening degree of the throttle valve 18 provided in the vaporizer | carburetor 2 is controlled, and the amount of supply air supplied to each cylinder of an engine by the air cleaner 27 is controlled by this. The throttle valve 18 is provided with a throttle opening sensor 24 which outputs a signal according to the opening degree, and this signal is introduced into the control device 8.

In this way, the air flow rate controlled by the opening and closing of the throttle valve 1 is detected by the pressure sensor 9 provided in the intake pipe 4 as the suction negative pressure amount, and this suction negative pressure detection signal is transmitted to the control device 3. Is entered. The opening degree of each of the solenoid valves 7, 8, 9, and 10 provided in the vaporizer 2 is controlled by the suction negative pressure detection signal and the output signals from various sensors described later. In addition, the fuel supplied from the dye pump 29 is supplied from the main nozzle 12 to the vaporizer 2 via the main jet nozzle 11. The fuel is also supplied from the main nozzle 12 to the vaporizer 2 by bypassing the main jet nozzle 11 via the main solenoid valve 8 separately from the above supply system. Therefore, the fuel supply amount supplied from the main nozzle 12 can be controlled by the opening time of the main solenoid valve 8. In addition, the fuel is also supplied from the slow homo bypass hohol 13, but the supply amount can be controlled by controlling the opening time of the solenoid valve 7 and thereby suppressing the air inflow amount from the air inlet.

The fuel solenoid valve 9 provided in the carburetor 2 is a valve for increasing the fuel supply, and is driven when a large amount of fuel is required, for example, when starting an engine or driving a warm air. The fuel is supplied from the opening 14 by controlling the fuel solenoid valve 9.

In addition, the air solenoid valve 10 provided in the vaporizer | carburetor 2 controls the quantity of air supplied to the engine 1, The air is supplied from the opening part 15. As shown in FIG.

Each of the above-described solenoid valves 7, 8, 9, and 10 is controlled for opening time during engine control such as air-fuel ratio control and turbulence operation described later, whereby the air amount and fuel amount are minutely controlled. Controlled.

17 is also referred to as exhaust gas reflux (hereinafter referred to as EGR (valve). The EGR valve 17 is a part of the exhaust gas combusted in the cylinder of the engine discharged to the atmosphere through the exhaust pipe 5 and the three-way catalyst 6. Is a control valve for taking out from the exhaust pipe 5 and returning it to the intake pipe 4 by the EGR pipe 28 connected to the EGR valve 17. This reflux of the exhaust gas improves the exhaust gas. The reflux ratio of the exhaust gas is controlled by the EGR valve 17 and the EGR solenoid 16 that controls the EGR valve.

In addition, 25 is an ignition coil, 26 is a distributor, and these perform ignition and ignition timing control by the control signal from the control apparatus 3. As shown in FIG. This control is controlled by the detection signal which depends on the engine speed which is taken in from the crank angle sensor 23 to the control field 3. The crank angle sensor 23 includes a reference angle generator, a position signal generator, and the like.

In addition, 20 is a cooling water temperature sensor and 22 is an intake air temperature sensor. The former is used as a correction signal for increasing the concentration of fuel because the former rapidly increases the engine temperature immediately after starting the engine. It is taken in to the control apparatus 3 as a correction signal.

21 is an O ₂ sensor, which is one of the sensors important for the control of the present invention, for detecting the oxygen concentration in the exhaust gas and performing optimum air-fuel ratio control.

Data necessary for engine control is taken into the control device 3, and the engine is controlled in accordance with a control command from the control device 3. This control device 3 is shown in FIG. That is, FIG. 2 is a block diagram which shows the control apparatus 3 of the engine provided with a vaporizer. In the figure, the controller 3 includes a central processor (hereinafter referred to as cpu) 30, a read only memory (hereinafter referred to as ROM) 31, and a registration call memory device (hereinafter referred to as RAM). ), An input / output control device 33, and the like.

The cpu 30 issues a command for selectively injecting a large number of external information necessary for operation control to be described later into the cpu 30, and the ROM 31 having stored therein contents and various data in which the control mode of the system is programmed. And arithmetic processing in accordance with the above-described storage contents from the RAM 32 capable of writing and reading out various data.

The input / output control device 33 converts a plurality of pieces of information input from the outside according to a selection command from the cpu 30, and the digital switching switch 35 (e.g., a multiplexer), and the selected analog information. A / D converters 36 and 37 for converting to digital information, and these information are taken into cpu 30, calculated according to the contents stored in the ROM 31 in advance, and controlled by an external control device. And a control logic circuit 39 for outputting a signal.

The control target controlled by the operation result of the cpu 30 is the air-fuel ratio control device 40, the air-fuel ratio control device 40 is a slow solenoid valve 7 and the main solenoid valve 8 shown in FIG. Etc. The amount of air and the amount of fuel for determining the air-fuel ratio are performed by controlling the opening times of the valves 7 and 8 described above.

The control target for controlling the fuel amount of the above-described engine is comprehensively controlled by the input information described below. That is, the battery voltage detector 44 detects a change in the battery voltage.

The cooling water temperature sensor 20 becomes a main parameter especially during no-load slow operation. For example, the cooling water temperature sensor 20 controls to rotate the engine at high speed by increasing the concentration of the mixer at low temperature of the cooling water.

In addition, the cooling water temperature data is also used for the air-fuel ratio, exhaust reflux control, and the like.

The opening degree sensor 24 and the pressure sensor 19 are for controlling the reflux amount of the EGR control apparatus and the air-fuel ratio of the air-fuel ratio control apparatus.

The O ₂ sensor 21 (exhaust gas sensor) is for detecting the oxygen concentration in the exhaust gas and performing optimal air-fuel ratio control.

Next, the start switch 45 is data which comes out at the start of the engine and is used as all control condition signals after starting the engine.

In addition, the reference angle signal generator 46 and the position signal generator 47 are included in the crank angle sensor 23 of FIG. 1, which is generated at every reference angle at the time of crank rotation, for example, at every 180 degrees of electrons. This signal is generated every 1 °. Since these signals are all data relating to the engine speed, the ignition control device becomes data relating to various other better control objects. Each signal of the battery voltage detector 44, the cooling water temperature sensor 20, and the O ₂ sensor 21 is output to the multiplexer, and one selected input is input to the analog-to-digital converter 36, and the digital value thereof is bass. It is blown into cpu 30 at phosphorus 34.

The output of the pressure sensor is digitally converted by the analog-to-digital converter 37. On the other hand, the result calculated in cpu is set in the register 90. A constant period is set in the register 94. The clock from the cpu 30 is output to the counter 92 and counted. When the value is equal to or greater than the register 94, the flip-flop is set to the output of the comparator 98, and at the same time the counter 92 Cleared. For this reason, the "L" output is output from the inverter 102 to the slow solenoid 7, while the "H" solenoid is output to the main solenoid. When the output C of the counter 92 becomes larger than the output D of the register 90, the fling flop 100 is reset. For this reason, the "L" signal is input to the slow solenoid 7 via the inverter 102, while the "H" signal is input to the main solenoid 8. Therefore, the "H" duty of the main solenoid 8 is determined by the value of the register 90, and the modification rate is determined. Slow solenoids, on the other hand, are assigned an "L" duty to determine lung rate.

The input data described above must respond to the rapidly changing driving conditions of the vehicle and control the control object with high accuracy. So, the control process of the control apparatus shown in FIG. 2 is demonstrated by the flowchart shown in FIG.

First, each task is started by interrupting timer intervention (hereinafter referred to as IRQ), and task priority processing is performed.

That is, when the cpu receives an interruption request, the staff 50 determines the interruption factor analysis of whether the interruption is a timer interruption, and if the interruption is a timer interruption, the step gives priority to the step. Is selected by the task scheduler, and the selected task is executed in step 51.

If it is determined in step 52 that the execution of the selected task is finished, the process returns to step 53 again and the next task is selected by the task scheduler.

On the other hand, when the interruption is interrupted in the abnormal state, the fuel pump is turned off in step 54, the ignition system is reset, and the input / output control devices are all NO-GO in step 55.

The first table is a table showing the specific contents of the level-separated respective tasks selected in step 51 of the flowchart shown in FIG.

As apparent from the first table, each task is divided into high priority order, as shown in levels 1 to 3, and start timings according to the priority are determined. In the embodiment of the present invention, the starting timing is set to 10 ms, 20 ms, and 40 ms in order of high priority.

[Table 1]

Hereinafter, embodiments of the present invention will be described.

In Fig. 3, steps 62 to 70 determine whether the start timing of the first table has been reached. If this timing is reached, the Q marker at the level corresponding to each of FIG. 4 is set to 1 at step 66. The address ADR 200 corresponds to level 1, the ADR 201 corresponds to level 1, and the ADR 202 corresponds to level 3. The counter bits of the ADRs 200 to 202 are soft timers that are updated at each timer interrupt to determine the timing of the first table.

In step 74 to 82, it is determined at what level the program is to be executed. In step 52, the Q marker is reset and the R marker is set as it is executed. Then, the R marker is reset in step 53 by ending the task at that level.

5 is a flow of level 1, which is executed every 10 msec as shown in Table 1. FIG. In step 110, the output of the O ₂ sensor is set in the RAM address ADR 203 as the output of the analog-to-digital converter. The channel of the multiplexer is then switched to the next blown sensor.

In step 114, the digital value of the negative sensor is set to the address 204 of the RAM. In step 116, the rotational speed of the output shaft of the engine is detected and set in the address ADR 205 of the RAM.

6 is a flow of level 2, and is executed every 20m sec as shown in Table 1. The negative pressure is read out from the ADR 204 of the RAM at 118, and N is read out from the ADR 205 of the RAM at step 120.

Then, in step 124, the ROM is searched for and the value is set in the RAM 206 in step 126.

Next, the solenoid valves 7 and 8 of the carburetor for supplying fuel are driven by the pulse duty input thereto, and the control of the feed fuel is performed by the individual time control (on duty control) of each solenoid valve.

As shown in FIG. 7, the on-duty control uses the engine speed N and the suction negative pressure VC detected by the pressure sensor 19 and the position detector 23 as parameters. The on-duty value (%) of the solenoid valve is set and stored in ROM in advance so as to have an air-fuel ratio, and the mutual relationship between the set-memory on-duty value and the on-duty value calculated by the feedback signal from the O ₂ sensor is stored. Operation is performed.

The table of the on duty values shown in FIG. 7 is called a flat map of the air-fuel ratio, and the on-duty value of each solenoid valve determined on this flat map is stored in the controller. This value is then retrieved in the flow of FIG.

The O ₂ sensor has a property that the electromotive force rapidly changes as shown in FIG. 8 at an air-fuel ratio of 14.7 of the theoretical air-fuel ratio in a kind of oxygen shade battery.

Therefore, the method of controlling the air-fuel ratio by feeding back the signal of the O ₂ sensor, which is generally performed, determines the density (rich) and blur (re-in) of the air-fuel ratio, for example, in the case of rich, the duty site of the solenoid valve is reduced In the case of Rein, closed loop control is performed so that the average air-fuel ratio and the theoretical air-fuel ratio are increased to 14.7.

However, the output voltage of the O ₂ sensor is detecting voltage of the O ₂ sensor with respect to the actual in-cylinder air-fuel ratio becomes delayed by a ninth time also (b) as shown in (I). Therefore, the output voltage waveform of the O ₂ sensor shown in FIG. 9 (II) is used to adjust the proportional correction (C) and the integral slope (A) as shown in FIG. 9 (III) to correct the delay. The duty cycle is converted into an excitation waveform, the duty cycle is determined by the waveform shown in FIG. 9 (III), and the air-fuel ratio is controlled on average by this duty cycle.

The embodiment according to the present invention is a combination of the duty control by the plate after described above and the feedback control by the O ₂ sensor. The control method will be described with reference to the flowchart of FIG.

That is, a task cycle, for example every 40 milliseconds. If activation is made, a determination is made as to whether the air-fuel ratio control loop is a Peruvian loop in step 150. If it is determined in step 150 that it is not a Peruvian, it is determined in step 151 whether the temperature of the engine cooling water temperature is 40 ° C or higher, and if it is determined that the engine cooling water temperature is not 40 ° C or higher, Peru in step 154. Clear the oop mark, set the value on the air-fuel ratio flat map to the actuator (determining the duty cycle of the solenoid valve) at step 155, and then perform this operation until the engine coolant temperature reaches a specified value (40 ° C). This is repeated.

In step 151, if is determined that the coolant temperature of the engine specified value more than 40 ℃, step 152, step 153 judges whether application start immediately, and determined to start immediately at step 152, once in, O ₂ The standby counter is set to wait until the temperature of the sensor rises and becomes active (in this embodiment for about 10 seconds).

In the meantime, the air-fuel ratio control is controlled by the duty cycle by the flat mat value as described above. In addition, the value of the flat macro is read and set in the resin 70 of FIG. 1 so that the standby counter at step 153 is displayed at step 155 even during operation. In this way, control by the flat map is performed. This value is also set in the address 207 of the RAM in step 180. As described above, the control by the OFF loop and, in other words, the control by the flat macro is performed until the water temperature rises immediately after the engine start and the O ₂ sensor can function sufficiently.

If it is determined in step 156 that the counting operation of the wait counter has ended, then a dither is set in step 157.

This deserizer is intended to purify and stabilize the O ₂ sensor, forcing and periodically changing the duty output to deliberately change the O ₂ sensor output to the voltage change equivalent to rich and re-in.

In step 157, if the disser is set, it is determined in step 158 whether the output change is over a certain range. If it is determined that it is over a certain range, in step 159, a mark for starting Perupoop control is set. In step 160, the stop stop is made.

In the case where the control loop is determined as Peruvian in step 150 described above, it is determined in step 61 whether the amplitude of the O ₂ sensor is less than or equal to the prescribed value, and if it is determined that the amplitude of the O ₂ sensor is greater than the specified value, the step In 162, it is determined whether the O ₂ sensor is in close contact with one side (rich or rein) for a predetermined time or more. In other words, it is determined whether the O ₂ sensor is abnormal. If it is determined in step 162 that the O ₂ sensor is in close contact with either the rich or the reinforcement for a predetermined time or more, and the O ₂ sensor is determined to be abnormal, the process immediately switches to the open loop control, that is, the process moves to step 154.

If the O ₂ sensor is normal, the engine speed is measured at step 163 and the so-called control gains corresponding to the height of part C and the inclination of part A shown in FIG. 9 (III) are set at step 164. . In this step 164, the setting of the control gain is performed to correct the detection delay of the above-described O ₂ sensor and the stability of the control (hunting prevention), and the setting value depends on the rotation speed of the engine.

In the next step 165, the control gain determined by the engine rotational speed is explained by the change in the output signal of the O ₂ sensor shown in FIG. 9 (II). In other words, the proportional portion C shown in FIG. 9 (III). And converting it into a waveform having an integral A portion.

First, in step 165, it is determined in Fig. 9 (II) and (III) whether the O ₂ sensor output is greater than or equal to the slice level S / L, and if it is determined that the O ₂ sensor output is greater than or equal to the slice level S / L. In step 169, it is determined whether the change direction has changed from rein to rich, and only in the case where it is determined that the change direction has changed from rein to rich (arrow in section D in FIG. 9 (II)), in step 171 When the value is changed to rich, the value corresponding to the proportional part C is subtracted from the value of the address 207 of the RAM, and if the status does not change to the rich in step 169 continues, the integral A in step 170. The value corresponding to the subtraction value is subtracted from the value of the address 207 of the RAM.

If it is determined in step 165 that the O ₂ sensor output does not reach the slice level S / L or more, it is determined in step 166 whether the O ₂ sensor output has changed from the rich to the rein direction with respect to the slice level S / L. If it is determined that the O ₂ sensor output has changed from the rich to the reinward direction (the E arrow in FIG. 9 (III)), the proportional portion C is determined in step 168 in the address 167 of the RAM. In the case where the state which does not change to re-in is continued in step 166, the value corresponding to the integral A is added to the value of the address 207 of the RAM in step 167.

The output waveform of the O ₂ sensor is converted into a waveform as shown in FIG. Basically, when the duty condition of the solenoid valve according to the waveform is changed or when the operation conditions such as acceleration and deceleration in the engine change suddenly, the control delay of the air-fuel ratio control caused by the sudden change of the operation conditions in each of the following steps. Is preventing.

That is, in step 172, the change in the air-fuel ratio flat image caused by the sudden change in the engine is calculated, and in this change step 173, the change is added to the on-duty value determined by the signal from the O ₂ sensor, and the step At 174, the result is output to register 90 of FIG. 1, which is an actuator.

The air-fuel ratio control with respect to the sudden change of the operating condition of this engine is demonstrated more concretely next.

FIG. 11 shows the steps 172, 173, and 174 of FIG. 10 in more detail.

If the shift from the driving point P point on the air-fuel ratio flat map shown in FIG. 12 due to the sudden change of the driving condition is to move to the driving point Q point, the data P point on the air-fuel ratio flat map and the data in step 175 of FIG. The change ΔD with the Q point is calculated, and at step 176 the value of the address 207 of the RAM, which is the duty determined by the change ΔD and the O ₂ sensor, is added, and the addition result is obtained at step 177. As a duty output, it outputs to the register 90 of an external actuator (in this case, the solenoid valve). The Q point data is temporarily stored in the address 208 of the RAM to make the previous batch data at the time of operation by the next timer interruption.

This is clear as the relationship of FIG. In other words, the waveform R which is subjected to the duty control by the signal of the O ₂ sensor is generally controlled around the duty value P determined on the plate map. If the point S changes from P to Q at the point S, the change ΔD of the above-described P and Q is calculated, and the change ΔD is immediately added to the waveform R which is duty controlled by the O ₂ sensor. Duty control is continuously controlled around Q.

However, when the operation condition is changed from P to Q only by the feedback control by the conventional O ₂ sensor, as shown by the dotted line in FIG. 13, there is a time delay caused by the inclination of the integrator until it enters the normal air-fuel ratio control from the sudden change.

This means that the air-fuel ratio control is stopped for T time due to the sudden change of P → Q, which is controlled within the allowable range of a and b around the theoretical air-fuel ratio 14.7.

Therefore, according to the present embodiment, the duty control based on the feedback signal of the O ₂ sensor is mainly performed. However, the on-duty value (%) calculated in the above-described air-fuel ratio flat map is stored in ROM in advance, and is always In addition to monitoring the operating state of the engine at the same time, the change is calculated and added to the duty value determined by the signal from the O ₂ sensor, so that the air-fuel ratio control can be easily followed even if the operating state changes suddenly. .

In this way, according to the present embodiment, the unnecessary component in the exhaust gas does not exceed the allowable value for any sudden change in any operation state. In addition, according to the present embodiment, even if the coolant temperature has not yet reached the proper temperature immediately after the engine is started, and even after the start of the O ₂ sensor, the stable detection output cannot be obtained yet. When the engine is normally transported and the O ₂ sensor is in an abnormal state such as disconnection, the air-fuel ratio control is automatically controlled on the flap map, so that the accurate air-fuel ratio control is performed no matter what the engine is in. .

As described above, according to the present invention, it is possible to follow the air-fuel ratio with high precision even with a sudden change of the engine.

Claims (1)

Processor control for controlling the operation of the internal combustion engine with an air-fuel mixture supply device for controlling the air-fuel ratio of the air-fuel mixture to be supplied to the internal combustion engine and an exhaust sensor for detecting a predetermined characteristic of the exhaust gas emitted by the internal combustion engine. In the method of operating the apparatus, the memory stores a predetermined data value on a predetermined data map related to the air-fuel ratio of the mixer among various numerical values for the selected engine condition, and supplies the air supplied by the mixer supply device according to the output of the exhaust sensor. Generating an air-fuel ratio control signal for controlling the air-fuel ratio of the fuel mixer, and modifying the air-fuel ratio control signal according to a signal representing a difference between data values of a data map defined as a numerical value of a selected engine state before the change in engine state. The modified air-fuel ratio control signal is then air-fueled. A fuel control method for an engine comprising the steps of feeding to a mixer feeder.

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