JP4051180B2 - Lean combustion engine control apparatus and method, and engine system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic engine control system for a lean combustion engine, and more particularly to an engine control device that can search and control optimum control parameters according to engine conditions even when the dynamic range of a control air-fuel ratio is wide.
[0002]
[Prior art]
In conventional engine control devices, when determining control parameters such as target air-fuel ratio, target throttle opening, and ignition timing, the engine speed Ne is generally set as one axis as described in JP-A-2-85843. , Ne and the basic injection amount Tp obtained from the actually measured intake air amount Qa is used as another axis of the map to obtain the control parameter. As a special example, as described in Japanese Patent Laid-Open No. 6-129276, there is one in which the engine speed is set as one axis and the target torque obtained from the accelerator opening is set as another axis. .
[0003]
The lean combustion system improves the fuel efficiency by increasing the combustion efficiency and effectively using the energy of the fuel. As the air-fuel ratio is made leaner, the fuel efficiency is improved, but the combustion becomes unstable, so various ideas have been made for drivability and exhaust gas reduction.
[0004]
In lean combustion, if the air-fuel ratio exceeds a certain value, combustion becomes unstable, torque fluctuation increases rapidly, and smooth operation becomes impossible. For this reason, it has been proposed to perform precise air-fuel ratio control in a lean air-fuel ratio region in order to suppress torque fluctuation to an allowable value.
[0005]
[Problems to be solved by the invention]
By the way, in the lean combustion engine having a wide dynamic range of the control air-fuel ratio represented by the cylinder injection engine, the above two known examples will be verified with respect to the control parameter setting method.
[0006]
In the method for obtaining control parameters described in Japanese Patent Laid-Open No. 2-85843, assuming that the air-fuel ratio is controlled to be constant in all operating regions, the intake air amount Qa increases as the load increases, so the basic injection amount Tp also increases monotonously. Since the basic injection amount Tp corresponds to 1: 1 with respect to the torque, each control parameter can be set to an optimum value for any torque if the basic injection amount Tp is used for the control shaft.
[0007]
However, when the air-fuel ratio on the low load side is set to a leaner air-fuel ratio than on the high load side, the intake air amount Qa decreases as the load increases, and there is a region where the basic injection amount Tp decreases even when the load increases. And the basic injection amount Tp does not correspond to 1: 1. Therefore, when the basic injection amount Tp is used for the control shaft, the optimum value of each control parameter cannot be set for an arbitrary torque. Further, it is desirable that the basic injection amount Tp representing the load increases as the load increases. However, even if the load increases, the value of the basic injection amount Tp becomes the same, or even if the load increases, the basic injection amount Tp. As a result, a reverse phenomenon occurs where the control becomes smaller, and the control becomes extremely unstable. This phenomenon becomes more prominent as the difference in the set air-fuel ratio becomes larger. Therefore, control is not established in a lean combustion engine having a wide dynamic range of the control air-fuel ratio represented by a direct injection engine.
[0008]
Further, as described in Japanese Patent Laid-Open No. 6-129276, a map search for control parameters with the engine speed as one axis and the target torque obtained from the accelerator opening as another axis is performed. It cannot be verified whether the torque matches the actual torque. Therefore, the optimal control parameter is not available because the actual torque cannot be compensated for in an actual vehicle where the actual torque cannot be obtained even if the optimum value of each control parameter is set for each torque in a bench test with a dynamometer. Unable to search the map.
[0009]
Therefore, an object of the present invention is to set the optimum value of each control parameter to 1: 1 for any torque even in a lean combustion engine with a wide dynamic range of the control air-fuel ratio, and in practice It is an object of the present invention to provide an engine control device that realizes stable lean combustion by accurately obtaining the optimum value of each control parameter for an arbitrary torque even in a vehicle-mounted state.
[0010]
[Means for Solving the Problems]
In the present invention, a reference Tp as a function of the accelerator opening is obtained. This reference Tp is a value of the basic fuel injection amount Tp when the engine is operated at a theoretical air-fuel ratio (A / F = 14.7) in order to produce a certain torque, and corresponds to the torque and 1: 1.
[0011]
Basic fuel injection amount Tp = K × Qa / Ne (Equation 1)
Reference Tp = f (Ne, Acc) (Equation 2)
K: coefficient
Ne: Engine speed
Qa: amount of intake air
Acc: accelerator opening
The reference Tp learns the actual basic fuel injection amount Tp with the two variables of the accelerator opening and the engine speed as axes at the stoichiometric air-fuel ratio, and updates the value.
[0012]
By the way, in the lean combustion, the measured basic fuel injection amount Tp (hereinafter, actual Tp) increases as the air-fuel ratio decreases even if the same torque is output, and does not correspond to 1: 1 with the torque.
[0013]
Therefore, at the time of lean combustion, the engine operating point is determined by a map of the reference Tp and the engine rotational speed Ne, and the engine operating point can be uniquely determined regardless of the air-fuel ratio by searching each control parameter.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an engine control apparatus according to the present invention will be described in detail with reference to the illustrated embodiments.
[0015]
FIG. 1 shows an overall control block diagram of the present invention. The reference Tp map 101 is a map for obtaining the reference Tp from two variables of the accelerator opening Acc and the engine speed Ne, and the value in the map can be updated by the actual Tp at the theoretical air-fuel ratio (hereinafter referred to as “stoichi”). It is like that. In order to perform combustion at the optimum value of each control parameter in accordance with the engine load and rotation speed, a map of A / F, ignition timing, fuel injection timing, and EGR rate is searched by two variables of engine rotation speed Ne and reference Tp. . The air-fuel ratio is a stoichiometric A / F map 103 and a lean A / F map 102 at a lean air-fuel ratio (hereinafter referred to as “lean”), the ignition timing is a stoichiometric ignition map 105 and a lean ignition map 104, and the fuel injection timing is a stoichiometric injection timing map. 107, the lean injection timing map 106, and the EGR rate are divided into a stoichiometric EGR map 109 and a lean EGR map 108. Whether to use a stoichiometric map or a lean map for each map is determined by the map switching logic 110.
[0016]
In the map switching logic 110, when the target A / F> 14.7 and the engine coolant temperature ≧ T (for example, 10 ° C.), it is permitted to use the lean side map among the control parameter maps. Here, calculation of the target A / F referred to for map switching will be described in detail. If the current A / F map is the stoichiometric A / F map 103 and the target A / F ≦ 14.7 of the map value of the operation region determined by the reference Tp and the engine speed Ne, a map of other control parameters such as an ignition map is also available. Use for stoiki. Next, when the operating point moves and changes to the target A / F = 20 area in the stoichiometric A / F map 103, the map on the lean side is selected by the map switching logic 110, so the target in the lean A / F map 102 is displayed. At the same time as searching for A / F, other parameters are also switched to the lean map. Further, when the load or the engine speed increases during lean operation and enters the area of A / F = 14.7 in the lean A / F map 102, the other parameters are changed simultaneously with switching to the stoichiometric A / F map 103. Switch to the stoichiometric map.
[0017]
The intake air amount Qa of the engine detected by the sensor is noise-removed by the filter processing unit 111, and the actual Tp is calculated in block 112 (Equation 1). The actual Tp is used to update the reference Tp map 101 and is also used as an axis of the stoichiometric learning map 113. Further, the target Tp is obtained from the reference Tp as shown in the following equation (Equation 3), and the feedback control of the air amount control unit is performed with the deviation compared with the actual TP.
[0018]
Target Tp = Reference Tp × (Target A / F) / (14.7) (Equation 3)
In (Equation 3), the reference Tp is equivalent to the Tp at the time of stoichiometry. Therefore, when the target A / F is 14.7 of the stoichiometry, the target Tp = the reference Tp = the actual Tp at the time of stoichiometry. On the other hand, when the target A / F is lean and is, for example, 40, the air amount actuator (for example, electronically controlled throttle) is controlled so that the target Tp is obtained by multiplying the reference Tp by 40 / 14.7.
[0019]
When the throttle PD (proportional / derivative) control is performed based on the deviation obtained by subtracting the actual Tp from the target Tp, the proportional gain Kp is applied in block 116, and the signal obtained by the differentiator in block 114 is differentiated into the differential gain in block 115. Apply the Kd to the throttle target opening, and input it to the TCM (Throttle Control Module) of the air amount actuator.
[0020]
On the other hand, for the fuel, the fuel injection amount Ti is obtained by adding the injector valve opening delay time Ts to the reference Tp.
[0021]
Next, FIG. 2 shows an example of an engine system to which the present invention is applied. In the figure, the air taken in by the engine is taken from the inlet 2 of the air cleaner 1, passes through the air flow meter 3, passes through the throttle body in which the throttle valve 5 for controlling the intake flow rate is accommodated, and enters the collector 6.
[0022]
Here, the intake air is distributed to each intake pipe connected to each cylinder of the engine 7 and guided into the cylinder.
[0023]
On the other hand, fuel such as gasoline is sucked and pressurized from a fuel tank 9 by a fuel pump 10, and then a fuel damper 11, a fuel filter 12, a fuel injection valve (injector) 13, and a fuel pressure regulator 14 are connected. Supplied to the fuel system.
The fuel is regulated to a constant pressure by the fuel pressure regulator 14 and is injected into the intake pipe 8 from an injector 13 provided in the intake pipe 8 of each cylinder.
[0024]
The air flow meter 3 outputs a signal indicating the intake flow rate and is input to the control unit 15.
[0025]
Further, a throttle sensor 18 for detecting the opening degree of the throttle valve 5 is attached to the throttle body, and its output is also input to the control unit 15.
[0026]
Next, 16 is a dist (distributor), and this dist has a built-in crank angle sensor. A reference angle signal REF indicating the rotation position of the crankshaft and an angle signal POS for detecting a rotation signal (rotation number) are provided. These signals are also input to the control unit 15.
[0027]
Reference numeral 20 denotes an A / F sensor provided in the exhaust pipe, and this output signal is also input to the control unit 15. Here, the A / F sensor is for detecting the actual operating air-fuel ratio, and may be a type that outputs a linear output with respect to the detected air-fuel ratio, It may be a type that detects whether the state is thin. In the middle of the exhaust pipe, there is a catalyst 25 for purifying CO, HC, NOx in the exhaust gas.
[0028]
As shown in FIG. 3, the main part of the control unit 15 takes in signals from the MPU, ROM and A / D converter, various sensors for detecting the operating state of the engine, etc. as input, and executes predetermined arithmetic processing. Then, various control signals calculated as the calculation results are output, predetermined control signals are supplied to the injector 13 and the ignition coil 17 described above, and fuel supply amount control and ignition timing control are executed.
[0029]
FIG. 4 is an example of a map in which the target A / F in the lean combustion engine is assigned with the engine speed Ne and torque as axes, and is a pattern in which the leaner the load is, the lower the load is. FIG. 5 shows a longitudinal cut at a certain engine speed (2000 rpm). In FIG. 5, the horizontal axis represents torque, but FIG. 6 shows this relationship with the horizontal axis indicating the basic fuel injection pulse width Tp (actual Tp) of a parameter that can be actually detected in the engine control apparatus. is there. In this case, a plurality of target A / Fs correspond to one value of the actual Tp, and the torque does not correspond to 1: 1 with respect to the actual Tp. It is impossible to search for F or make the operating point correspond to 1: 1.
[0030]
FIG. 7 applies the relationship shown in FIG. 5 to the control system of FIG. 1, which is a feature of the present invention, and arranges the reference Tp as a horizontal axis. In this way, it can be seen that both the torque and the target A / F correspond to 1: 1 with respect to the reference Tp and are established as a map. Further, the target Tp before addition of the signal input to the block 116 in FIG. 1 also corresponds to one value if the reference Tp is determined.
[0031]
FIGS. 4 to 7 examine the control axis based on an example of air-fuel ratio setting. FIG. 8 is a quantitative verification of the establishment of the control axis in order to obtain this general solution.
[0032]
FIG. 8 shows the relationship of actual Tp when the target A / F is assigned to each of the three torque points and the operation is actually performed lean. In addition, the numerical value in [] is an example. First, it is assumed that there are three torque differences T1 [8 kgfm], T2 [10 kgfm], and T3 [12 kgfm] at the same engine speed. If Tp at the time of the above-mentioned stoichiometry, that is, the reference Tp is Tp1, Tp2, Tp3, the relationship of Tp1 <Tp2 <Tp3 is always established. The ratio of Tp (Tp2 / Tp1) at this time is a.
[0033]
Next, A / F1, A / F2, A / F3 and the target A / F are set so that the gradient of A / F decreases between T1 to T2 and T2 to T3 as shown in A / F setting pattern 2 in FIG. Set. Here, the ratio of A / F (A / F2) / (A / F1) is b. At this time, the actual Tp is LTp1 <LTp2 <LTp3, and the actual Tp monotonously increases with respect to the torque. Therefore, the torque and the actual Tp have a 1: 1 relationship, and the air-fuel ratio can be set even if the actual Tp is used as the control shaft. It is. Here, the product a × b of a and b is a numerical value of 1 or more between T1 and T2 and between T2 and T3.
[0034]
However, A / F1, A / F2, A / F3 and the target A / F are set so that the gradient of A / F increases between T1 to T2 and T2 to T3 as in A / F setting pattern 1 in FIG. Set. At this time, the A / F ratio b is smaller than the A / F setting pattern 2. In addition, the actual Tp at this time is LTp1 <LTp2> LTp3, and the actual Tp is decreased although the torque is increased between T2 and T3. Therefore, the torque and the actual Tp do not have a 1: 1 relationship, and if the actual Tp is used for the control shaft, the air-fuel ratio cannot be set. Here, paying attention to the product a × b value of a and b, it is 1 or less between T2 and T3.
[0035]
When the results obtained from the above examination are quantitatively arranged, the target A / F is set to 1: 1 on the actual Tp axis in a setting with a small A / F gradient with respect to the torque such that the a × b value is 1 or more. Although it is possible to correspond, the target A / F cannot be made to correspond to 1: 1 on the actual Tp axis in a setting with a large A / F gradient with respect to torque such that the a × b value is 1 or less. It is.
[0036]
Therefore, as described in claim 2, any two operating points having the same engine speed Ne and a different torque (T1 <T2) are selected from the engine operating points so that a × b <1. When setting A / F, in order to select control parameters such as accelerator opening, ignition timing, air-fuel ratio, fuel injection timing, EGR rate, etc., the engine speed is set as one axis in each control parameter map, and the other If the axis is provided with either the accelerator opening or the reference Tp that is a function of the accelerator opening, and a map search means is provided, the A / F setting is eliminated and the dynamic range of the used air-fuel ratio can be widened. is there.
[0037]
Next, FIG. 9 corresponds to the content of the reference Tp map 101 of FIG. 1, and is stored in the ROM as a map searched by the two axes of the accelerator opening and the engine speed Ne.
[0038]
FIG. 10 is a block diagram of the reference Tp map portion of FIG. 9, where the accelerator opening Acc and the engine speed Ne are input, and the reference Tp is output. The value in the reference Tp map can be corrected by the actual Tp at the time of stoichiometry.
[0039]
The correction of the reference Tp map is processed as shown in the flowchart of FIG. The series of processes shown in FIG. 13 is executed by a scheduled interrupt. First, in block 131, the current accelerator opening Acc (k), engine speed Ne (k), and target A / F are read. In the determination 132, it is determined whether or not the target A / F is 14.7. If the current target A / F is 14.7, that is, stoichiometric, the routine proceeds to decision 133. Whether or not the engine is in a steady state is determined based on two determinations 133 and 134. First, in the determination 133, it is determined whether or not the current accelerator opening Acc (k) is within a certain value ± α from the previous accelerator opening Acc (k-1). In determination 134, it is determined whether or not the current engine speed Ne (k) is within a certain value ± β from the previous engine speed Ne (k-1). If it is determined in the above determination that it is in a steady state, the actual Tp is read in block 135. Further, at block 136, the value of the reference Tp in the region determined by the accelerator opening and the engine speed is updated to the actual Tp value. Next, in block 137, the values of the accelerator opening Acc (k-1) and the engine speed Ne (k-1) are made current values in preparation for the next processing. The actual Tp map is updated by the above processing.
[0040]
FIG. 11 is a table of the reference Tp, in which the engine speed factor is removed from the map of FIG.
[0041]
FIG. 12 is a block diagram of the reference Tp table portion of FIG. 11, where the accelerator opening Acc is input and the reference Tp is output. Similarly to the reference Tp map, the values in the reference Tp table can be corrected by the actual Tp when stoichiometric in the flowchart of FIG.
[0042]
The block diagram of FIG. 14 is for performing air amount control based on the target Tp. The target Tp is calculated by multiplying the reference Tp by the target A / F as shown in Equation 3 and dividing by the stoichiometric A / F = 14.7. The air amount actuator 141 operates so as to increase the intake air amount Qa if the reference Tp> actual Tp based on the deviation between the target Tp and the actual Tp calculated as shown in Equation 1, and if the reference Tp <actual Tp. It operates so as to reduce the intake air amount Qa. The air amount actuator 141 is, for example, a motor-driven electronically controlled throttle.
[0043]
FIG. 15 is a diagram showing an input / output relationship of signals between the throttle control device TCM (Throttle Control Module) 151 and the control unit 15 as an example of the air amount actuator 141 of FIG. The Tp calculation unit of the control unit 15 inputs the intake air amount Qa measured by the intake air amount meter 3 and the engine speed Ne, and outputs an actual Tp. As shown in FIG. 14, the actual Tp is compared with the target Tp, and the deviation is input to the opening calculation unit 152. The opening calculation unit 152 calculates a target opening of the electronically controlled throttle based on a Tp deviation that is a deviation between the target Tp and the actual Tp. In the TCM, the target opening degree transmitted from the control unit 15 is compared with the actual opening degree detected by the throttle sensor 18, and the opening degree deviation is input to the current converter 154. The current converter 154 calculates a current to be supplied to the motor 155 from the opening degree deviation, and controls the current to the motor 155. Torque from the shaft of the motor 155 is transmitted to the throttle valve 5 via a gear, and feedback control is performed so that the target opening and target Tp are obtained.
[0044]
FIG. 16 is a diagram showing an input / output relationship of signals between the TCM (Throttle Control Module) 151 and the control unit 15 of the example of the air amount actuator 141 shown in FIG. 14, and is an example of a form different from FIG. The difference from FIG. 15 is that the Tp calculation unit 153 and the opening conversion unit 152 are taken into the TCM 151. Therefore, the target Tp is transmitted from the control unit 15 to the TCM 151. In TCM151, the Tp calculation unit 153 outputs an actual Tp in response to the input of the intake air amount Qa measured by the intake air amount meter 3 and the engine speed Ne. The actual Tp is compared with the target Tp, and the deviation is input to the opening calculation unit 152. The opening calculation unit 152 calculates the target opening of the electronically controlled throttle based on the Tp deviation. Next, the target opening and the actual opening detected by the throttle sensor 18 are compared, and the opening deviation is input to the current converter 154. The current conversion unit 154 calculates a current to be supplied to the motor 155 from the opening degree deviation, and controls the current to the motor 155. Torque from the shaft of the motor 155 is transmitted to the throttle valve 5 via a gear, and feedback control is performed so that the target opening and target Tp are obtained.
[0045]
FIG. 17 is a diagram showing an input / output relationship of signals between the TCM (Throttle Control Module) 151 and the control unit 15 as an example of the air amount actuator 141, which is an example of a form different from FIGS. 15 and 16. The difference from FIGS. 15 and 16 is that the signal transmitted from the control unit 15 to the TCM 151 is the target intake air amount Qa. By taking this communication mode, the TCM 151 compares the target intake air amount Qa with the actual intake air amount Qa and performs feedback control. The deviation between the target intake air amount Qa and the actual intake air amount Qa is input to the opening calculation unit 152. The opening calculation unit 152 calculates a target opening of the electronically controlled throttle based on the Qa deviation. Next, the target opening and the actual opening detected by the throttle sensor 18 are compared, and the opening deviation is input to the current converter 154. The current converter 154 calculates a current to be supplied to the motor 155 from the opening degree deviation, and controls the current to the motor 155. Torque from the shaft of the motor 155 is transmitted to the throttle valve 5 through a gear, and feedback control is performed so that the target opening and target Qa are obtained.
[0046]
The present invention is effective for an engine system that performs lean combustion, but is particularly effective for a lean combustion engine having a wide dynamic range of air-fuel ratio. FIG. 18 shows a specific configuration of an in-cylinder injection engine system that directly injects fuel into a combustion chamber as an example of a lean combustion engine having a wide air-fuel ratio dynamic range.
[0047]
Hereinafter, differences from the port injection engine system of FIG. 2 will be described.
[0048]
Fuel, such as gasoline, is primarily pressurized from the fuel tank 9 by the fuel pump 10 and then secondarily pressurized by the fuel pump 30 and supplied to the fuel system to which the injector 13 is piped. The primary pressurized fuel is kept at a constant pressure (for example, 3 kg / cm) by the fuel pressure regulator 31. ² ), And the secondary pressure pressurized to a higher pressure is maintained at a constant pressure (for example, 30 kg / m) by the fuel pressure regulator 32. ² ) And is injected into the cylinders from the high pressure injectors 33 provided in the respective cylinders.
[0049]
Next, reference numeral 16 denotes a crank angle sensor attached to the camshaft shaft, which outputs a reference angle signal REF indicating the rotation position of the crankshaft and an angle signal POS for detecting a rotation signal (number of rotations). It is input to the control unit 15. Here, the crank angle sensor may be of a type that directly detects the rotation of the crankshaft as in 34.
[0050]
Reference numeral 20 denotes an A / F sensor provided in the exhaust pipe, and this output signal is also input to the control unit 15.
[0051]
In the present invention, since the throttle opening is controlled by calculating the reference Tp using the accelerator opening signal as an input, ensuring the accuracy of the accelerator opening and the throttle opening is an important issue in performing air-fuel ratio control and torque control. In particular, it is necessary to ensure the accuracy of the accelerator opening and the throttle opening near the fully closed position where the increase rate of the intake air amount with respect to the opening becomes large.
[0052]
Accordingly, FIGS. 19 and 20 show a configuration in which the accelerator opening and the throttle opening are input to the control unit 15 with high accuracy.
[0053]
The TCM 151 in FIG. 19 includes an amplifier 193 that amplifies the voltage from the accelerator or throttle opening sensor 191 N times and an amplifier 192 that has a gain of 1. The outputs of the amplifiers 192 and 193 are converted to digital by the A / D converter 194 and input to the CPU 195. The CPU 195 selects either the 1 × signal or the N × signal, but the N × signal from the amplifier 193 is used to accurately follow the actual opening to the target opening when the opening is low. Here, the outputs of the amplifiers 192 and 193 are branched and input to the A / D converter 196 in the control unit 15, and digitally converted and input to the CPU 197. In this way, the control unit 15 can also obtain an N-fold signal, so that the calculation of the reference Tp and the throttle control at the time of low opening can be performed with high accuracy.
[0054]
FIG. 20 shows an example in which the configuration is different for the same purpose as in FIG. Here, the TCM 151 includes an amplifier 193 for amplifying the voltage from the accelerator or throttle opening sensor 191 N times and an amplifier 192 for gain 1. The outputs of the amplifiers 192 and 193 are converted to digital by the A / D converter 194 and input to the CPU 195. The CPU 195 selects either the 1 × signal or the N × signal, but the N × signal from the amplifier 193 is used to accurately follow the actual opening to the target opening when the opening is low. Here, the CPU 195 of the TCM communicates with the CPU 197 of the control unit 15 and transmits the digital data of the 1 × actual opening signal and the N times signal to the CPU 197. In this way, the control unit 15 can also obtain an N-fold signal, and the reference Tp calculation and throttle control at the time of low opening can be performed with high accuracy.
[0055]
In the prior art, since the actual Tp was used as the load side shaft, the actual Tp is not uniquely determined with respect to the torque when the lean combustion is performed, and the phenomenon that the actual Tp is reversed when the load becomes large. there were.
[0056]
However, according to the present invention, since the present invention is based on the reference Tp, the torque, the reference Tp, and the target A / F are uniquely determined, and the target A / F setting range is set in the lean combustion region. It can be enlarged and can be operated at an optimum A / F according to the load. Similarly, it is possible to operate at an optimal ignition timing, fuel injection timing, and EGR rate according to the load.
[0057]
【The invention's effect】
In the present invention, when setting the engine operating point, the control parameter is searched and obtained with the engine speed Ne and the reference Tp as axes, so that the target A / F for torque, the target Tp and each control parameter are determined. It will be possible to create a uniquely defined relationship. According to this, since a large degree of freedom is derived in setting the target A / F, the optimum air-fuel ratio and control parameters can be set according to the load in the lean combustion region, and stable lean Combustion can be realized.
[Brief description of the drawings]
FIG. 1 is a control block diagram showing the overall configuration of the present invention.
FIG. 2 shows an example of an engine system to which the present invention is applied.
FIG. 3 is a configuration diagram of a control unit to which the present invention is applied.
FIG. 4 shows an example of setting a target air-fuel ratio.
FIG. 5 shows an example of setting a target air-fuel ratio with respect to torque.
FIG. 6 shows an example of target A / F setting in the prior art.
FIG. 7 shows an example of target A / F setting in the present invention.
FIG. 8 shows an example of target A / F setting for a plurality of points with different torques.
FIG. 9 is a diagram showing a reference Tp map used in the present invention.
FIG. 10 is a block diagram of a reference Tp map used in the present invention.
FIG. 11 is a diagram showing a reference Tp table used in the present invention.
FIG. 12 is a block diagram of a reference Tp table used in the present invention.
FIG. 13 is a flowchart of an embodiment of the present invention.
FIG. 14 is a block diagram showing a configuration of an air amount control unit according to the present invention.
FIG. 15 shows an example of the input / output relationship of the control unit to which the present invention is applied.
FIG. 16 shows an example of an input / output relationship of a control unit to which the present invention is applied.
FIG. 17 shows an example of the input / output relationship of the control unit to which the present invention is applied.
FIG. 18 shows an example of an engine system to which the present invention is applied.
FIG. 19 shows an example of the input / output relationship of the control unit to which the present invention is applied.
FIG. 20 shows an example of the input / output relationship of the control unit to which the present invention is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 3 ... Air flow meter, 5 ... Throttle valve, 7 ... Engine, 13 ... Injector, 15 ... Control unit, 18 ... Throttle sensor, 23 ... Spark plug, 33 ... High pressure injector, 101 ... Standard Tp map, 102 ... Lean A / F map, 117 ... TCM (Throttole Control Module).

Claims (5)

Means for detecting the amount of intake air Qa entering the cylinder of the engine;
Means for detecting the engine speed Ne;
Means for calculating the basic fuel injection pulse width Tp per cylinder by dividing the intake air amount Qa by the engine speed Ne and multiplying by a coefficient such that the air-fuel ratio becomes the stoichiometric air-fuel ratio (A / F = 14.7); ,
A map of each control parameter for selecting a control parameter including at least one of the air-fuel ratio, ignition timing, fuel injection timing, throttle opening, and EGR rate according to the engine operating state is referred to as “engine speed axis” and “ An engine control device having means for searching by "axis representing engine load",
Means for retrieving each control parameter using the basic fuel injection pulse width Tp as an axis representing the engine load at the stoichiometric air-fuel ratio;
The control parameter is retrieved using a reference Tp which is obtained based on the accelerator opening and the engine speed as the above-mentioned “axis representing engine load” at the lean air-fuel ratio, and which has the same unit as the basic fuel injection pulse width Tp. Means,
And having
A learning means is provided for updating the map of the reference Tp so that the reference Tp of the operation region determined by the engine speed and the accelerator opening coincides with the basic fuel injection pulse width Tp at the theoretical air-fuel ratio. Engine control device. Among the engine operating points, select any two operating points with the same engine speed Ne and different torque ( T1 <T2 ) , set the torque at the first operating point to T1, and the basic fuel injection amount at the stoichiometric air-fuel ratio. Tp1, target A / F is A / F1,
The torque at the second operating point is T2, the basic fuel injection amount at the theoretical air-fuel ratio is Tp2, the target A / F is A / F2,
When the change ratio from Tp1 to Tp2 is a (= Tp2 / Tp1) and the change ratio from A / F1 to A / F2 is b (= [A / F2] / [A / F1]), a × b When setting A / F to be <1,
To select control parameters including at least accelerator opening, ignition timing, air-fuel ratio, fuel injection timing, and EGR rate, the engine speed is set as one axis in the map of each control parameter, and the other axis is opened. In addition to providing a means for searching the map with a reference Tp determined based on the engine speed and the engine speed,
A learning means is provided for updating the map of the reference Tp so that the reference Tp of the operation region determined by the engine speed and the accelerator opening coincides with the basic fuel injection pulse width Tp at the theoretical air-fuel ratio. Engine control device. 3. The engine control apparatus according to claim 1, wherein the learning condition is a state in which feedback control is performed with the air-fuel ratio being the stoichiometric air-fuel ratio. Means for detecting the amount of intake air Qa entering the cylinder of the engine;
Means for detecting the engine speed Ne;
Means for calculating the basic fuel injection pulse width Tp per cylinder by dividing the intake air amount Qa by the engine speed Ne and multiplying by a coefficient such that the air-fuel ratio becomes the stoichiometric air-fuel ratio (A / F = 14.7); ,
A map of each control parameter for selecting a control parameter including at least one of the air-fuel ratio, ignition timing, fuel injection timing, throttle opening, and EGR rate according to the engine operating state is referred to as “engine speed axis” and “ An engine control device having means for searching by "axis representing engine load",
Means for retrieving each control parameter using a basic fuel injection pulse width Tp, which is a variable retrieved from a table of an accelerator opening axis, as an axis representing an engine load at the theoretical air-fuel ratio;
The control parameter is retrieved using a reference Tp which is obtained based on the accelerator opening and the engine speed as the above-mentioned “axis representing engine load” at the lean air-fuel ratio, and which has the same unit as the basic fuel injection pulse width Tp. Means,
And having
An engine control apparatus comprising means for updating a table of reference Tp so that a reference Tp determined by an accelerator opening coincides with a basic fuel injection pulse width Tp at the theoretical air-fuel ratio. Among the engine operating points, select any two operating points with the same engine speed Ne and different torque ( T1 <T2 ) , set the torque at the first operating point to T1, and the basic fuel injection amount at the stoichiometric air-fuel ratio. Tp1, target A / F is A / F1,
The torque at the second operating point is T2, the basic fuel injection amount at the theoretical air-fuel ratio is Tp2, the target A / F is A / F2,
The reference Tp is a variable to be searched in the accelerator opening axis table,
When the change ratio from Tp1 to Tp2 is a (= Tp2 / Tp1) and the change ratio from A / F1 to A / F2 is b (= [A / F2] / [A / F1]), a × b When setting A / F to be <1,
To select control parameters including at least accelerator opening, ignition timing, air-fuel ratio, fuel injection timing, and EGR rate, the engine speed is set as one axis in the map of each control parameter, and the other axis is opened. In addition to providing a means for searching the map with a reference Tp determined based on the engine speed and the engine speed,
An engine control apparatus comprising means for updating a table of reference Tp so that a reference Tp determined by an accelerator opening coincides with a basic fuel injection pulse width Tp at the theoretical air-fuel ratio.

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