JP3882055B2 - Air-fuel ratio control method for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for controlling an internal combustion engine, and more particularly to an improvement in an air-fuel ratio control method for an internal combustion engine using air-fuel ratio means.
[0002]
[Prior art]
Conventionally, in order to control the air-fuel ratio of the internal combustion engine, an air-fuel ratio detection means that reacts to whether the air-fuel ratio is higher or lower than the stoichiometric air-fuel ratio has been provided in the exhaust pipe or the like of the internal combustion engine. The fuel injection amount is controlled based on the above.
Specifically, means for detecting the engine speed and throttle opening of the engine are provided, the basic fuel injection amount is determined using a map or the like based on the detection results of these means, and the engine temperature and intake air are determined. Means for detecting environmental changes with respect to engine operating conditions such as temperature are provided, a fuel injection correction value or a correction coefficient is calculated based on the detection results of these means, and the fuel injection correction value is set as the basic fuel injection amount. While fuel is injected from the fuel injection device as a fuel injection amount corrected by adding or multiplying by a correction coefficient, air-fuel ratio detection means is provided in an exhaust pipe or the like, and mixing with fuel supplied based on the corrected fuel injection amount Whether the air-fuel ratio is rich or lean is detected, and a feedback correction value is determined from the detection result.For example, when the detected air-fuel ratio is rich, the fuel injection amount is determined. If the detected air-fuel ratio is lean, the fuel injection amount is increased to control the air-fuel ratio to the stoichiometric air-fuel ratio (see FIG. 16, this figure shows the normal air-fuel ratio) It is a graph showing the change over time of the fuel injection amount controlled by the control method and the detection result of the air-fuel ratio detection means.)
In the conventional control method described above, the operation of the means for detecting the environmental change with respect to the engine operating condition such as the engine temperature is monitored, and when the failure of the means is detected, the fuel injection correction value is set to a predetermined value. (Refer to FIG. 17, this figure is a graph corresponding to FIG. 16 including a state in which the fail-safe for failure of the environmental change detecting means functions), and air-fuel ratio detection. A limit width has been set for the feedback correction value determined based on the detection result of the air-fuel ratio detection means as fail-safe when the means fails.
[0003]
[Problems to be solved by the invention]
According to the conventional control method described above, the final fuel injection amount is corrected in accordance with the detection result of the air-fuel ratio means, that is, the actual air-fuel ratio, so that extremely accurate air-fuel ratio control can be performed, and the engine The means for detecting an annular change with respect to the operating conditions of the engine is monitored, and when a failure of these environmental change detection means is detected, the fuel injection correction value or the correction coefficient is fixed to a predetermined value or a correction coefficient value. The fuel injection amount does not increase or decrease due to a failure of the detection means, and the limit value is set for the feedback correction value as a fail-safe of the air-fuel ratio detection means, so the air-fuel ratio detection means The fuel injection amount does not increase or decrease even when the engine breaks down. When the detection means fails and the fuel injection correction value or the correction coefficient is fixed to a predetermined value, the limit range of the feedback correction value based on the air-fuel ratio detection means is determined. As shown in FIG. 17, even if the feedback correction value is increased to the limit, the final fuel injection amount does not reach the target fuel injection amount, and therefore the air-fuel ratio may be maintained in a lean state. Such problems remain.
The above problem can be solved by eliminating the limit range of the feedback correction value. However, if the limit range of the feedback correction value is eliminated, the air-fuel ratio detection unit fails and, for example, the detection result is fixed to the lean side. In such a case, the feedback correction value is not preferable because the fuel injection amount is increased without limit in order to make the air-fuel ratio rich.
The present invention solves the above-mentioned conventional problems, has a fail-safe function for both failure of the environmental change detection means and the air-fuel ratio detection means, and even when the environmental change detection means fails, the air-fuel ratio detection means It is an object of the present invention to provide an air-fuel ratio control method for an internal combustion engine that can obtain a target air-fuel ratio by feedback control using the engine.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the present invention fixes a fuel injection amount correction value determined based on the detection result of the environmental change detection means to a constant value when the environmental change detection means fails, In the air-fuel ratio control method for an internal combustion engine having two fail-safe functions of providing a limit range for the feedback correction value determined based on the detection result, the limit of the feedback correction value when the environmental change detecting means fails Increase width Then, the final fuel injection amount is increased or decreased to a level at which the air-fuel ratio detection means can react in response to the change in the feedback correction value.
As a result, it is possible to control the air-fuel ratio of the internal combustion engine that can obtain the optimum air-fuel ratio even after the failure of the operating state detecting means.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
An air-fuel ratio control method for an internal combustion engine according to the present invention includes a fuel injection amount of a fuel injection device, a basic fuel injection amount determined based on a detection result of a means for detecting an engine operating state, and an environment for engine operating conditions. If the air-fuel ratio is lean based on the fuel injection amount correction value determined based on the detection result of the means for detecting change and the detection result from the means for detecting the actual air-fuel ratio after fuel injection, the fuel injection amount And when it is rich, it is determined based on a feedback correction value calculated so as to decrease the fuel injection amount, while the operation of the environmental change detection means is monitored and a failure of the means is detected. The fuel injection amount correction value is fixed to a predetermined value as fail-safe, and the air-fuel ratio feedback correction value is limited as fail-safe when the air-fuel ratio detection means fails. In the air-fuel ratio control method for an internal combustion engine, the air-fuel ratio feedback correction value to a level at which the air-fuel ratio detection means can react in response to a change in the air-fuel ratio feedback correction value when a failure of the environment change detection means is detected. This is characterized in that the limit width of the is expanded.
[0006]
The limit width may be enlarged on both the rich side and the lean side, and at this time, the enlargement ratio on the rich side and the lean side may be changed. Further, the limit width may be enlarged only on the rich side.
Preferably, the enlargement ratio can be determined according to the type of the environmental change detection sensor that has failed.
[0009]
【Example】
Hereinafter, an embodiment of an air-fuel ratio control method for an internal combustion engine according to the present invention will be described with reference to the accompanying drawings.
FIG. 1 is an external view of a ship equipped with a two-board outboard motor to which the present invention is applied. As shown in the drawing, this two-board outboard motor is a type in which two outboard motors 3-1 and 3-2 each equipped with a six-cylinder two-cycle engine for ships are mounted on the stern of the hull 1. Each of the outboard motors is provided with a drive control device 100 to be described later so that the engine can be operated independently even when one of the engines fails.
The two outboard motors 3-1 and 3-2 have the same structure, and the processing method of the drive control device 100 that controls the engine of each outboard motor has the same structure. In the description, only one outboard motor 3-1 will be described.
[0010]
FIG. 2 is a schematic configuration diagram showing the relationship between the engine of the outboard motor 3-1 and the drive control device 100, and FIG. 3 shows detection means and fuel injection for detecting the operating state of the engine of the outboard motor 3-1. It is a block diagram which shows the means which drives an ignition, the drive control apparatus 100, and the relationship of a drive object.
As shown in the drawings, the engine is provided with various sensors as means for detecting environmental changes with respect to the engine operating condition and engine operating conditions. The drive control device 100 calculates the fuel injection amount that can obtain the optimum air-fuel ratio at that time, the injection timing or the ignition timing, etc. according to a control program determined in advance based on detection information from these detection sensors, and performs ignition. In addition to the plug and the fuel injection device, it controls a fuel pump, an oil pump, and the like.
The control program includes a main routine in which a detection information reading routine and a plurality of calculation routines for calculating each control amount based on the read detection information are arranged according to a predetermined sequence, and the calculation processing is performed according to the main routine. Do.
[0011]
Hereinafter, each detection unit shown in FIG. 3 will be described in order from the top.
The operating state detecting means is a detecting means for detecting the operating state of the engine at that time. In this embodiment, the operating state detecting means includes cylinder detecting means # 1 to # 6, crank angle detecting means, and throttle opening degree detecting means.
Six cylinder detecting means # 1 to # 6 are arranged around the crankshaft. These cylinder detecting means # 1 to # 6 are configured to emit a signal at the moment when the piston of each cylinder is located at a top dead center or a predetermined angle before it, and in this embodiment, during one revolution of the crankshaft. One cylinder detection signal (TDC signal) is sent to the clearing processing apparatus 101 in order from each cylinder # 1 to # 6 every 60 degrees. The engine speed is calculated based on the detection results of the cylinder detecting means # 1 to # 6. The previous period TDC signal becomes a trigger signal for executing an event interrupt (TDC interrupt) for each cylinder. The event interrupt is executed by the previous period TDC signal, and each of the main routines obtained during the event interrupt flow is obtained. The ignition timing and fuel injection amount set based on the control calculation result for the cylinder is executed.
The crank angle detection means generates an angle pulse that is a base for ignition timing control, and generates a pulse signal corresponding to the number of teeth of a ring gear (not shown) engaged with the crankshaft. For example, when it is configured to generate 448 pulses during one rotation corresponding to 112 gear teeth, the crankshaft rotates 0.8 degrees for each pulse. The ignition timing control is performed by counting the crank angle signal after setting in the TDC interruption.
The throttle opening detection means generates an analog voltage signal according to the opening of a throttle valve (not shown) provided in the intake manifold. The arithmetic processing unit uses this analog signal for arithmetic processing such as A / D conversion and reading and map reading.
The environment change detection means is a means for detecting a change in the state of the surrounding environment with respect to the operating state of the engine (for example, in this embodiment, a change in temperature of each engine, a change in trim angle, etc.). It comprises a trim angle detection means, an E / G temperature detection means, an atmospheric pressure detection means, and an intake air temperature detection means. Since these changes in the surrounding environment directly affect the air-fuel ratio, the detection result obtained from the environment change detection means is the fuel injection amount calculated based on the result of the operation state detection means described above. It is used as a reference control amount correction parameter for correcting a reference control amount such as ignition timing.
The trim angle detection means is provided on a bracket for mounting the outboard motor to the hull 1 and detects the mounting angle of the outboard motor. The E / G temperature detection means is provided in a cylinder block of each cylinder (or a specific reference cylinder) and detects the temperature of the cylinder. The atmospheric pressure detection means is provided at an appropriate position in the cowling, and the intake air temperature detection means is provided at an appropriate position in the intake passage.
The air-fuel ratio detection means is O ₂ It consists of sensors, reacts at the stoichiometric air-fuel ratio, detects whether the actual air-fuel ratio is rich or lean, and is used as a parameter for performing feedback control such as the fuel injection amount.
The knock detection means is used to detect abnormal combustion in each cylinder. When knocking occurs, the knocking is eliminated by shifting the ignition timing to the retard side or setting the fuel to the rich side. And prevent damage to the engine.
The oil level detection means is provided with level sensors in both the sub tank in the cowling and the main tank in the ship.
The thermo switch is composed of a highly responsive sensor such as a bimetal type temperature sensor, and performs misfire control for detecting an engine temperature rise or the like due to a cooling system abnormality or the like to prevent seizure.
The shift cut switch detects the load applied to the shift operation system during the shift operation of the outboard motor (forward clutch or reverse clutch detachment operation), that is, the high surface pressure of the dog clutch. Based on this signal, when the surface pressure of the clutch applied to the clutch disengagement is high, the engine output, that is, the torque is reduced to facilitate the clutch disengagement.
The DES detecting means is a signal for informing the other engine that one engine is in a misfire operation state due to an abnormality in the case of two-machine operation in which two engines 3-1 and 3-2 are driven simultaneously. A certain DES is detected. That is, in the case of a ship of a type equipped with two outboard motors arranged side by side at the stern, the detection means, when the engine of one outboard motor is performing misfire control due to oil shortage or temperature rise, This is for detecting the DES output from the DES output means of the engine to detect the misfire operation state of the engine. Like the other engine, misfire operation is performed, and the operating state of both engines is made the same to maintain the balance of the run.
The battery voltage detection means detects the battery voltage and outputs it to the arithmetic processing unit 103. The arithmetic processing unit 101, based on the detection result, changes the speed of the valve opening / closing operation that changes according to the change in the drive power supply voltage of the injector. The fuel injection amount is corrected accordingly.
The starter switch detection means is for detecting whether or not the engine is in a starting operation, and the arithmetic processing unit 101 performs, for example, fuel enrichment based on the detection result in the starting state. Control for starting operation.
The E / G stop switch detection means includes an engine stop operation switch and a water fall detection switch. Of these, the water fall detection switch detects an emergency state such as a water fall accident, and controls to stop the engine immediately in an emergency. .
[0012]
Signals from the respective detection means described above are input to the arithmetic processing unit 101. The arithmetic processing unit 101 outputs fuel injection means # 1 to # 6 on the output side, ignition means # 1 to # 6, based on these input signals. Drive and control the fuel pump and oil pump. The fuel injection means and the ignition means are each composed of an injector and a spark plug, which are controlled in turn independently for each cylinder.
[0013]
Hereinafter, a basic configuration for executing the ignition timing control and the fuel injection control in the arithmetic processing unit 101 will be described with reference to FIGS. 4 and 5. FIG. 4 is a block diagram showing a basic configuration for executing ignition timing control and fuel injection control. In this block diagram, a portion for performing basic control amount calculation of ignition timing and fuel injection amount, a portion for performing basic control amount correction according to environmental changes with respect to the engine operating state, and detection from the air-fuel ratio detection means Only the part that executes feedback control based on the result and the part that executes fail-safe at the time of failure of the environmental change detection means are specifically shown, and the anti-seize control by the thermo switch and the detection result of the shift cut switch are shown. A specific configuration is omitted with respect to a part for executing control of the engine speed based on the above and other control for misfire of the spark plug. FIG. 5 is a graph showing the change over time of the actual fuel injection amount and the detection result of the air-fuel ratio detection means corresponding to the processing of the drive control device 101.
[0014]
The cylinder discriminating means 201 discriminates the corresponding cylinder number based on the inputs from the cylinder detecting means # 1 to # 6 (see FIG. 3). The cycle measuring means 203 inputs the detection signals of the cylinder detecting means # 1 to # 6 via the cylinder discriminating means 201, and measures the input signal time interval from each cylinder based on these detection signals. Is multiplied by 6 to calculate the time (cycle) of one rotation. The engine speed calculation means 205 calculates the rotation speed by calculating the reciprocal of this cycle. The throttle opening degree reading means 207 receives an analog voltage signal obtained from the throttle opening degree detecting means and converts it into a digital signal.
[0015]
The throttle opening degree signal A / D converted by the throttle opening degree reading means 207 and the engine speed signal calculated by the E / G speed calculation means 205 are the basic ignition timing calculation means 209 and the basic fuel injection amount calculation means 211. In each of the means 209 and 211, the ignition timing and fuel injection amount of the reference cylinder, here cylinder # 1, are calculated from the three-dimensional map. The three-dimensional map is a map obtained in advance by experiments or the like, and is stored in a non-volatile memory (see FIG. 3) although not shown. The engine speed signal and the throttle opening signal described above are further sent to the cylinder specific ignition timing correction value calculation means 213 and the cylinder specific fuel injection amount correction value calculation means 215, where the remaining cylinder # Correction values for the basic ignition timing and the basic fuel injection amount for 2 to # 6 are obtained by map calculation for each cylinder.
[0016]
On the other hand, the trim angle reading means 217, the engine temperature reading means 219, and the atmospheric pressure reading means 221 read detection signals from the corresponding detection means in the environment change detection means, and use these information as ignition timing correction value calculation means 223 and fuel. It sends to the injection quantity correction value calculation means 225, and the correction value according to each driving | running state is calculated by these means 223 and 225. In this case, the ignition timing correction value is obtained from a map stored in advance for each type of read data by reading the number of correction advance angles (or retard angles) to be added to the basic ignition advance value. Further, the fuel injection amount correction value is obtained by multiplying the basic injection amount by a predetermined proportional count.
[0017]
Although the ignition timing correction and the fuel injection amount correction are not shown, correction based on the intake air temperature may be performed by inputting intake air temperature detection data to each of the calculation means 212 and 213.
[0018]
The correction values calculated by the ignition timing correction value calculation means 223 and the fuel injection amount correction value calculation means 225 are respectively input to the ignition timing correction means 227 and the fuel injection amount correction means 229, where the basic ignition timing and the basic fuel are calculated. The ignition timing of the reference cylinder # 1 and the control amount of fuel injection (that is, the corrected ignition timing and the corrected fuel injection amount) are calculated by adding to the calculated value of the injection amount.
[0019]
The control amount of the ignition timing and fuel injection amount of the reference cylinder # 1 is input to the cylinder specific ignition timing correction means 231 and the cylinder specific fuel injection amount correction means 233, where the corrected basic ignition for the reference cylinder # 1 is performed. By adding control correction values by the cylinder specific ignition timing correction value calculation means 213 and cylinder specific fuel injection amount correction value calculation means 215 for the cylinders # 2 to # 6 to the timing and the fuel injection amount, the cylinders # 2 to # 6 are added. Control amounts of the ignition timing and fuel injection amount of the cylinders up to # 6 are calculated.
[0020]
Based on the ignition timing and the fuel injection amount control amount for each cylinder # 1 to # 6 calculated as described above, the ignition output means 235 calculates the ignition advance angle value for each cylinder. The control amount thus set is set based on the cylinder detection means # 1 to # 6 and counted by an input signal from the crank angle reading means 239. The fuel output means 237 determines the valve opening time of the fuel injection device as cylinder detection means # 1. Set the timer based on ~ # 6.
[0021]
The arithmetic processing unit 101 further includes feedback control means 241 and failsafe control means 243.
The feedback control unit 241 determines a feedback correction value based on the actual air-fuel ratio information input from the air-fuel ratio reading unit 245 and outputs the feedback correction value to the fuel injection amount correction unit 229. Specifically, as shown in FIG. 5, the feedback control means 241 receives either a rich signal or a lean signal from the air-fuel ratio reading means 245. For example, when the air-fuel ratio is lean, the air-fuel ratio is reduced. The fuel injection amount is increased by a predetermined amount until it becomes rich, and if the air-fuel ratio at which the air-fuel ratio is detected is rich, the fuel injection amount is decreased by a predetermined amount until the air-fuel ratio becomes lean, and the air-fuel ratio detection means The fuel injection amount correction means 229 determines a feedback correction value for correcting the correction fuel injection amount so that the fuel injection amount and the rich signal are alternately output, and the fuel injection amount correction means 229 obtains the basic fuel injection amount and the fuel injection obtained from the basic fuel injection amount calculation means 211. The feedback correction value is further added to the corrected fuel injection amount calculated from the fuel injection amount correction value obtained from the amount correction value calculation means 225, and the final fuel injection amount is obtained. Determining a control value (see Fig. 5).
The feedback control means 241 sets a predetermined limit width R (see FIG. 5) for the calculated feedback correction value in consideration of the failure of the air-fuel ratio detection means. When a failure occurs and the detection result is fixed to the lean side, the final fuel injection amount is prevented from increasing without limit by the feedback correction value.
[0022]
Further, the fail safe control means 243 inputs the information of the environmental change detection means comprising the trim angle reading means 217, the engine temperature reading means 219, and the atmospheric pressure reading means 221, and these information is missing or abnormal. A failure determination is made on the environmental change detection means to determine whether or not the state is present, and the determination result is output to the ignition timing correction value calculation means 223, the fuel injection amount correction value calculation means 225, and the feedback correction value determination means 242.
In the fuel injection amount correction value calculation means 225, when information indicating that the annular change detection means is failed is input from the fail safe control means 243, the fuel injection correction value is fixed to a predetermined value (see FIG. 5). ). The fuel injection amount correction value calculation means 225 may determine a fixed value according to the type of the environmental change detection means that is a failure, or may determine a predetermined fixed value regardless of the type. Also good. On the other hand, when the feedback control means 241 obtains information from the fail-safe control means 243 that the environmental change means is out of order, the feedback control means 241 expands the limit width R of the feedback correction value by a preset width α. This makes it possible to set a large feedback correction value even if the fuel injection amount correction value is fixed at a low fixed value in the event of a failure of the environmental change detection means, so that the final fuel injection amount is detected by the air-fuel ratio. The level at which the means reacts, that is, the target fuel injection amount can be increased. When the final fuel injection amount has reached the target fuel injection amount, thereafter, as usual, the air-fuel ratio detection means changes the feedback correction value so that the lean signal and the rich signal are output alternately, thereby changing the fuel injection amount. Control (see FIG. 5).
[0023]
6 and 7 are flowcharts of the overall control of the engine including the basic configuration of the ignition timing control and the fuel injection amount control described in FIG. This flowchart is a main routine flow showing a sequence program of the entire control process incorporated in the CPU of the arithmetic processing unit 101.
[0024]
When the main switch is turned on and the power is turned on to start the engine operation, each processing circuit in the control processing device is first initialized after a predetermined reset time (step 11).
[0025]
Next, in step 12, the following engine operating state is determined and the result is stored in the volatile memory 102.
a. Whether the engine is in the starting state based on the ON / OFF information of the main switch, the ON / OFF information of the starter switch read using the starter switch detection means, and the engine speed information calculated from the crank angle pulse train read from the crank angle detection means Start determination to determine whether or not.
b. Throttle opening information read from the throttle opening detection means, engine speed information, DES information read from the DES detection means, which is the operating state information of the other outboard motor, or abnormal state information such as overheating and oil shortage described below Alternatively, cylinder deactivation determination for determining whether or not a specific cylinder should be deactivated based on rapid acceleration / deceleration information calculated from a time change in throttle opening information.
c. Judgment whether to perform feedback control of oxygen concentration mainly based on throttle opening information and engine speed information.
d. Judgment whether control data is to be learned and stored under specific control conditions mainly based on throttle opening information and engine speed information.
e. Over-revo judgment of whether or not the engine is in excessive rotation based on engine speed information.
f. Overheat determination for determining whether or not the engine is in an overheat state based on throttle opening information, engine speed information, and temperature information from engine temperature detection means or a thermo switch.
g. Oil empty judgment for judging whether or not the residual oil amount is small based on the throttle opening information, the engine speed information, and the residual oil amount information by the oil level detecting means.
h. Based on throttle opening information, crank angle information, oxygen concentration information or pulsar information from a pulsar coil which is a kind of crank angle detection means, a fail judgment is made as to whether or not these pieces of information are missing or abnormal. Based on the detection information from the environmental change detection means, a fail determination is made as to whether or not these pieces of information are missing or abnormal.
i. Judgment whether or not it is in a two-engine operation state where other outboard motors are also operated by a two-engine operation signal,
Determining whether the other outboard motor is in a cylinder deactivation operation state based on a cylinder deactivation state signal; and
A two-engine operating state determination consisting of three determinations of whether or not the other outboard motor is in an abnormal misfire control state by DES (signal for notifying the misfire control state corresponding to an abnormality).
j. Rapid acceleration / deceleration judgment as to whether or not the vehicle is in a sudden acceleration / deceleration state from the time change of the throttle opening information.
k. Determination of whether or not the ignition of the specific cylinder is stopped and the fuel injection amount is reduced based on the signal of the shift cut switch.
The various determinations described above are made based on various information such as detection information and calculation results from each detection means read in the previous routine.
[0026]
Next, in step 13, it is determined whether or not the routine work of the loop 1 is performed.
The arithmetic processing unit sets the processing flag 1 of the loop 1 to “1” at intervals of 4 ms in terms of hardware or software, and sets the processing flag 2 of the loop 2 to “1” at intervals of 8 ms.
FIG. 8 is a flowchart of a timer interrupt for executing such loop 1 and loop 2. Such setting of the timer is performed in step 11, the flag is set while the routines of the loops 1 and 2 are being executed, and the timer for the next routine is set.
Returning to FIG. 6, in step 13, the flag 1 is checked, and if it is “1”, the processing of loop 1 including steps 14 and 15 is executed. At the same time as the process proceeds to step 14, the flag 1 is cleared to "0". If it is confirmed in step 13 that the flag 1 is “0”, the process proceeds to step 16 to check whether the flag 2 is “1”. If the flag 2 is “1”, the process proceeds to step 17 and at the same time the flag 2 is cleared and becomes “0”. If the flag 2 is “0” in step 16, the process returns to step 12.
[0027]
If the process proceeds to step 14 due to the determination in step 13, the switch information is read in step 14. Here, information from the E / G stop switch detecting means, the main switch, the starter switch detecting means and the thermo switch is read. Subsequently, in step 15, information from the knock detecting means and the throttle opening degree detecting means is read. After the reading of information by the loop 1 is completed, the process proceeds to step 16 to determine whether or not to perform the routine work of the loop 2.
[0028]
If the process proceeds to step 17 by the determination in step 16, in step 17, the oil level is detected, the output of the shift cut switch, the engine two-engine running signal, the cylinder deactivation signal, and the DES signal are read. Proceeding to step 18, environmental change information (atmospheric pressure information, intake air temperature information, trim angle information, engine temperature information), battery voltage information, and knocking information are read from each detection means.
[0029]
Next, in step 19, misfire control is performed. This is because, in the determinations e to g in step 12, when an over-rotation state, an overheat state, or a small amount of residual oil is confirmed, or in the determination i in step 12, it is determined that another engine is in an abnormal state. Alternatively, when the output of the shift cut switch is detected at decision k, the ignition output means is controlled so as to misfire the specific cylinder. Further, in the cylinder-by-cylinder correction to be described later in step 24, misfire fuel control that outputs to the volatile memory 102 that the misfire control state is in effect is performed in order to halve the fuel injection amount of the cylinder to be misfired from other cylinders. .
As described below, when the injection pulse is set by interrupting the volatile memory 102 and the injection start data and the injection end data for each cylinder in step 65 of the TDC interruption in FIG. 11, it is also checked whether or not the misfire control state is set. When the engine is in the state, the injection end data of the misfired cylinder is corrected and set to the injection pulse, and the injection is completed in about half the time from the ignition applicable cylinder.
[0030]
Subsequent to the processing in step 19, the fuel pump and the oil pump are controlled based on the determination in step 20 whether the engine is rotating and information from the level sensor of the oil tank. This drive control controls the fuel pump to drive the fuel pump when the engine is rotating, and to stop the fuel pump when the engine is stopped. When the amount is small, the oil pump is driven to replenish the oil from the oil tank in the hull, or the engine speed is decreased to control the oil consumption to be decreased.
[0031]
Next, in step 21, the cylinder deactivation determination result is determined. This is a determination step for selecting a map for calculation processing when it is determined in the above-described determination b in the operation state determination step 12 that the idle cylinder operation is performed in a predetermined low load low rotation state. If it is determined in step 12 that the cylinder deactivation operation is not performed, the process proceeds to step 22, and the basic calculation of the ignition timing and the injection time and the correction calculation for each cylinder are performed using the normal operation map by the normal all cylinder operation. I do. It is also determined whether or not the misfire control state is set. If the misfire control state is set, the fuel is supplied to the misfire cylinder so as to supply fuel equal to the fuel injection amount to the other ignition cylinders or reduced by a predetermined ratio. The injection time is set. As a result, even when the misfire control is performed from the time when the throttle opening and the engine speed are equal to or higher than the predetermined values, the piston of the misfire cylinder can be cooled by the heat of vaporization of the supplied fuel. Damage can be prevented.
If it is determined in step 12 that the idle cylinder operation state is to be performed, the process proceeds to step 24 where the ignition timing and fuel injection timing are calculated using the cylinder idle map for cylinder idle operation in which a specific cylinder is deactivated. Correction calculation for each cylinder is performed.
[0032]
Next, after calculating the invalid injection time correction value and the like in step 23 of FIG. 7, the process proceeds to a fuel injection amount correction value calculation process based on the environmental change information in step 25.
FIG. 9 shows a flowchart of the fuel injection amount correction value calculation process. As shown in the drawing, first, in step 40, it is determined whether or not the environmental change detecting means is in a fail state based on the determination h in step 12 described above. When the injection amount correction value is set to a fixed value and the fuel injection amount correction value is not in the fail state, the fuel injection amount correction value is calculated in step 42 based on the detection result from the environment change detection means read in step 18. Proceeding to step 26, fail-safe processing relating to the feedback control means is performed.
[0033]
FIG. 10 shows a flowchart of the feedback correction value limit width changing process performed in step 26. As shown in the drawing, first, in step 45, it is determined whether or not the environmental change detecting means is in a fail state based on the determination h in step 12, and if it is in the fail state, feedback is made in step 46. The limit width R of the correction value is expanded to the limit width R + α (see FIG. 5). If not in the failure state, the process is terminated without performing the process of step 46, and the process proceeds to step 27 to detect the air-fuel ratio. A feedback correction value calculation process based on the detection result of the means is performed.
[0034]
In step 27, based on the detection result of the air-fuel ratio detection means read in step 18, for example, if the air-fuel ratio is lean, the fuel injection amount is increased until it becomes rich, and if it is rich, until it becomes lean. The feedback correction value is determined so as to decrease the fuel injection amount, and after that, the knock control correction coefficient is calculated in step 28, and then the routine proceeds to step 29.
[0035]
In step 29, an optimal ignition timing, injection time, injection timing, and fuel injection amount are calculated by adding various correction values to the basic control amount of the ignition timing and fuel injection.
After this process, in step 30, the calculation for the engine pre-stop control is performed. This is a control routine for stopping fuel injection and continuing fuel injection for a predetermined time in consideration of restart when the main switch or the engine stop switch is turned off in step 12 and it is determined that the engine is stopped. It is. Thus, the loop 2 routine is completed, and the operation returns to the original operation state determination step 12.
[0036]
FIG. 11 shows the flow of the TDC interrupt routine. A marker is attached to the crankshaft so as to output a signal from each cylinder detecting means informing that the piston is at the top dead center in each cylinder when passing in the vicinity of each cylinder detecting means. The TDC interruption is a routine interrupted at any time in the main routine based on the input of the TDC signal of each cylinder from the cylinder detection means # 1 to # 6.
First, in step 50, the cylinder number of the input TDC signal is determined, and then in step 51, the cylinder number is compared with the cylinder number related to the previous TDC signal, so that the engine of the rotational direction to be operated is determined. Determine forward and reverse rotation. If it is determined in step 51 that the engine is reverse, the process proceeds to step 66 and the engine is immediately stopped. If it is determined in step 51 that the engine is rotating forward, the process proceeds to step 52 where the time interval between, for example, the cylinders of # 1 and # 2 is counted and the engine speed is increased by 6 times. Is calculated. Subsequently, at step 53, the rotational speed is calculated by calculating the reciprocal of this cycle. At step 54, it is compared whether or not the engine speed is lower than the predetermined rotational speed. Proceed to, and stop the engine immediately.
[0037]
If it is determined in step 54 that the engine is not stopped, the process proceeds to step 55, where it is determined whether or not the input TDC interrupt signal is from a specific reference cylinder # 1. If the interrupt signal is a signal from the reference cylinder # 1, it is determined in step 56 whether or not the cylinder is in the idle cylinder operation state. If the change is made, the process proceeds to step 59 to switch the rest cylinder pattern, or the process proceeds to the next step 60 without changing and the ignition rest cylinder information is set. Also, if it is determined in step 56 that the cylinder is not in the idle cylinder operation, the cylinder idle information is cleared as it is or in step 57 and the process proceeds to step 60. In step 55, the interrupt signal is not from cylinder # 1. Also when it judges, it progresses to step 60 as it is and sets ignition stop cylinder information.
[0038]
Next, in step 61, it is determined whether or not the ignition system correction information of the shift cut process is output to the memory in step 23 of the main flow. If the ignition system correction information is output, the process proceeds to step 62. After setting the ignition system correction information related to the shift cut process, based on the ignition deactivation information set in step 60 and the ignition system correction information related to the shift cut process set in step 62, in step 63, the corresponding cylinder Set the ignition pulse. If it is determined in step 61 that the ignition system correction information regarding the shift and cut is not output to the memory (including the case where the ignition system correction information is cleared by the ignition system correction cancellation information), the process of step 62 is performed. Instead, in step 63, the ignition pulse of the corresponding cylinder is set based on the ignition deactivation information.
[0039]
After the above-described processing, the cylinder that reduces the fuel injection amount in the fuel injection control is set as the cylinder deactivation information by the fuel injection control for the cylinder that is misfired in the ignition control in Step 64, and the cylinder that is misfired in the ignition control in Step 65 Corresponds to the injection time corresponding to the fuel injection amount reduced from the fuel injection control amount calculated for the cylinder and the injection time corresponding to the fuel injection control amount calculated for the other cylinders for each cylinder. Set the injection pulse.
[0040]
The above is the configuration of the outboard motor engine to which the air-fuel ratio control method for an internal combustion engine according to the present invention is applied, the system configuration of the entire control system, and the flow thereof. According to the drive control apparatus 100 described above, the operation of the environment change detection unit is monitored, and the limit range of the feedback correction value is expanded when the failure of the detection unit is detected. Therefore, when the environment change detection unit fails, A fail-safe function that fixes the fuel injection amount correction value that is calculated based on the detection result of the environmental change detection means, and a fail that sets a marginal range for the feedback correction value determined based on the detection result of the air-fuel ratio detection means Even if both safety functions are provided, when the environmental change detection means actually fails, the two fail-safe functions do not prevent proper fuel injection and are optimal even when the environmental change detection means fails. It is possible to perform an effective air-fuel ratio control.
[0042]
FIG. 12 shows another processing method of the method for compensating for the decrease in the fuel injection amount due to the fixed fuel injection amount correction value when the environmental change detection means is faulty. Reference example FIG. 13 shows a graph showing the change over time of the air-fuel ratio detecting means and the fuel injection amount corresponding to the processing of FIG.
This process is a process executed in step 26 in FIG. 10 after the fuel injection amount correction value calculation process in step 25 in FIG. 10, and all other processes are performed. The above according to the present invention The same as the embodiment.
First, in step 70, it is determined whether or not the environmental change detecting means is in a fail state based on the determination h in step 12 (see FIG. 6). If not, the processing in steps 71 to 74 is performed. The process is terminated without performing the process. If it is determined in step 70 that the environmental change detection means is in a fail state, the process proceeds to step 71, where it is determined whether the output result of the air-fuel ratio detection means is in a rich state. Advances to step 72 to decrease the fixed value of the fuel injection amount correction value fixed at the predetermined value in step 25 (see FIG. 7).
If it is determined in step 71 that the output result of the air-fuel ratio detection means is not in the rich state, the process proceeds to step 73 without performing the processing of step 72, where it is determined whether or not the detection result is in the lean state. When the determination is made and it is determined that the engine is in the lean state, the fixed value of the fuel injection amount correction value fixed at a predetermined value is increased in step 24 (see FIG. 6).
As described above, when the environment change detection means is in the fail state, the value of the fuel injection amount correction value fixed to the predetermined value is increased or decreased, so that as shown in FIG. The feedback control based on the air-fuel ratio detecting means can be continued without changing the limit width.
[0043]
FIG. 14 shows another processing method of a method for compensating for the decrease in the fuel injection amount due to the fixed fuel injection amount correction value when the environmental change detection means is faulty. Reference example FIG. 15 shows a graph showing the change over time of the air-fuel ratio detecting means and the fuel injection amount corresponding to the processing of FIG.
This process is a process executed in step 26 in FIG. 7 after the fuel injection amount correction value calculation process is performed in step 25 in FIG. 7, and all other processes are performed. The above according to the present invention The same as the embodiment.
First, in step 75, it is determined whether or not the environmental change detection means is in a fail state based on the determination h in step 12 (see FIG. 6). If not, the processing in steps 76 to 78 is performed. The process is terminated without performing the process. If it is determined in step 75 that the environmental change detection means is in a fail state, the process proceeds to step 76, where it is determined whether the output result of the air-fuel ratio detection means is in a rich state. Advances to step 77 to decrease the basic fuel injection amount calculated in step 22 or step 24 (see FIG. 6).
If it is determined in step 76 that the output result of the air-fuel ratio detection means is not in the rich state, the process proceeds to step 78 without performing the processing in step 77, where it is determined whether or not the detection result is in the lean state. When the determination is made and it is determined that the engine is in the lean state, the fixed value of the fuel injection amount correction value fixed at a predetermined value is increased in step 24 (see FIG. 6).
As described above, when the environmental change detection means is in a failure state, the basic fuel injection amount itself fixed to a predetermined value is increased or decreased to reduce the limit range of the feedback correction value as shown in FIG. The feedback control based on the air-fuel ratio detecting means can be continued without changing the value.
[0044]
Book In the embodiment, the control method of the internal combustion engine according to the present invention is described by taking a 6-cylinder 2-cycle engine as an example. However, the engine suitable for the present invention is not limited to this embodiment, and is a 4-cycle engine. Needless to say, the number of cylinders is not limited.
The fuel injection amount is set to the basic fuel injection amount, and the fuel injection correction coefficient determined based on the detection result of the means for detecting the environmental change with respect to the engine operation and the air-fuel ratio are detected to approach the stoichiometric air-fuel ratio. You may obtain | require by multiplying the calculated feedback correction coefficient. In this case, the relationship between the fuel injection correction coefficient a, the basic fuel injection amount Q0, and the fuel injection correction amount q1 is a = (Q0 + q1) / Q0.
The relationship between the feedback correction coefficient b, Q0, q1, and the feedback correction value q2 is b = 1 + {q2 / (Q0 + q1)}. That is, in the claims, each result is referred to as a correction value, but it is controlled using a correction coefficient used by multiplication. Also Substantially the same as the present invention.
[0045]
【The invention's effect】
According to the air-fuel ratio control method of the internal combustion engine according to the present invention described above, the fuel injection amount correction value determined based on the detection result of the means when the environmental change detection means fails is fixed to a constant value, In the air-fuel ratio control method for an internal combustion engine having two fail-safe functions of providing a limit range for the feedback correction value determined based on the detection result of the air-fuel ratio detection means, when the environmental change detection means fails, the feedback correction value The final fuel injection amount is increased or decreased to a level at which the air-fuel ratio detecting means can react in response to a change in the feedback correction value by expanding the limit range of the air-fuel ratio. Even when the environmental change detection means fails, the optimum feedback control using the air-fuel ratio detection means can be performed, and as a result, the optimum air-fuel ratio can be obtained. Achieve the results.
[Brief description of the drawings]
FIG. 1 is an external view of a ship equipped with a two-board outboard motor to which the present invention is applied.
FIG. 2 is a schematic configuration diagram showing a relationship between an engine of an outboard motor and the drive control device.
FIG. 3 is a block diagram showing a relationship between a detection means for detecting the operating state of the engine of the outboard motor, a means for driving fuel injection and ignition, a drive control device, and a drive target.
FIG. 4 is a block diagram showing a basic configuration for executing ignition timing control and fuel injection control.
FIG. 5 is a graph showing changes over time in the actual fuel injection amount and the detection result of the air-fuel ratio detection means corresponding to the processing of the drive control device 101;
FIG. 6 is a flowchart of overall control related to the engine in the drive control device;
FIG. 7 is a flowchart of overall control related to the engine in the drive control device;
8 is a flowchart of a timer interrupt related to the flowcharts shown in FIGS. 6 and 7. FIG.
9 is a flowchart of a fuel injection amount correction value calculation process related to the flowcharts shown in FIGS. 6 and 7. FIG.
10 is a flowchart of a feedback correction value limit width changing process related to the flowcharts shown in FIGS. 6 and 7. FIG.
11 is a flowchart of a TDC interrupt routine related to the flowcharts shown in FIGS. 6 and 7. FIG.
FIG. 12 shows another processing method of a method for compensating for a decrease in the fuel injection amount due to the fixed fuel injection amount correction value when the environmental change detection means fails. Reference example It is a flowchart which shows.
FIGS. 13A and 13B show graphs showing the change with time of the air-fuel ratio detection means and the fuel injection amount corresponding to the processing of FIG.
FIG. 14 shows still another processing method of the method for compensating for the decrease in the fuel injection amount due to the fixed fuel injection amount correction value when the environmental change detection means has failed. Reference example It is a flowchart which shows.
FIGS. 15A and 15B show graphs showing the change with time of the air-fuel ratio detection means and the fuel injection amount corresponding to the processing of FIG.
FIG. 16 is a graph showing changes over time in the fuel injection amount controlled by the normal air-fuel ratio control method and the detection result of the air-fuel ratio detection means.
FIG. 17 is a graph corresponding to FIG. 16 including a state in which the fail-safe for failure of the environmental change detection unit functions.
[Explanation of symbols]
1 hull
3-1 Outboard motor
3-2 Outboard motor
100 Drive control device
101 arithmetic processing unit
102 volatile memory
103 Nonvolatile memory
201 cylinder discrimination means
203 period measuring means
205 Engine speed calculation means
207 Throttle opening reading means
209 Basic ignition timing calculation means
211 Basic fuel injection amount calculation means
213 Ignition timing correction value calculation means for each cylinder
215 Fuel injection amount correction value calculation means for each cylinder
217 Trim angle reading means
219 Engine temperature reading means
221 Atmospheric pressure reading means
223 Ignition timing correction value calculation means
225 Fuel injection amount correction value calculation means
227 Ignition timing correction means
229 Fuel injection amount correction means
231 Ignition timing correction means for each cylinder
233 Fuel injection amount correction means for each cylinder
235 Ignition output means
237 Fuel output means
239 Crank angle reading means
241 Feedback control means
243 Fail-safe control means
245 Air-fuel ratio detection means

Claims (5)

The fuel injection amount of the fuel injection device,
A basic fuel injection amount determined based on the detection result of the means for detecting the operating state of the engine;
A fuel injection amount correction value determined based on a detection result of a means for detecting an environmental change with respect to an engine operating condition;
Feedback calculated to increase the fuel injection amount if the air-fuel ratio is lean and to decrease the fuel injection amount if the air-fuel ratio is rich, based on the detection result from the means for detecting the actual air-fuel ratio after fuel injection While making a decision based on the correction value and
When the operation of the environmental change detection means is monitored and a failure of the means is detected, the fuel injection amount correction value is fixed to a predetermined value as fail safe, and the failure at the time of failure of the air-fuel ratio detection means is detected. In an air-fuel ratio control method for an internal combustion engine in which a limit range is defined for the air-fuel ratio feedback correction value as a safe,
An internal combustion engine characterized by expanding the limit range of the air-fuel ratio feedback correction value to a level at which the air-fuel ratio detection means can react in response to a change in the air-fuel ratio feedback correction value when a failure of the environmental change detection means is detected. Engine air-fuel ratio control method.   2. The air-fuel ratio control method for an internal combustion engine according to claim 1, wherein the limit range is expanded on both the rich side and the lean side.   3. The method for controlling an internal combustion engine according to claim 2, wherein an expansion ratio between the rich side and the lean side of the limit width is changed.   2. The air-fuel ratio control method according to claim 1, wherein the limit width is expanded only on the rich side.   The air-fuel ratio control method for an internal combustion engine according to any one of claims 1 to 4, wherein an expansion rate of the limit width is determined according to the type of the environmental change detection means that has failed.

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