JP4441135B2 - EGR control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an EGR (exhaust gas recirculation) control device for an internal combustion engine.
[0002]
[Prior art]
As an EGR control device for an internal combustion engine, for example, a technique described in Japanese Patent Publication No. 2-46787 is known, and the conventional technique is a valve opening command value (selected from a required opening map of an EGR control valve) ( When the state where the required opening is determined to be zero continues for a predetermined time, the detected opening after the predetermined time elapses is learned as a new zero reference position and added to the detected opening or the required opening. It is proposed to control the EGR control valve based on the added value.
[0003]
Further, a technique described in Japanese Patent Laid-Open No. 8-200184 is also known, and the conventional technique targets a diesel engine, calculates a basic command value for an adjustment amount of an EGR control valve based on its rotation speed and load. The basic command value correction amount is calculated based on the current value and the past value of the basic command value so as to be the reverse characteristic of the delay characteristic of the EGR system, and the basic command value is corrected by that. .
[0004]
Further, a technique described in Japanese Patent Laid-Open No. 7-293350 is also known. The conventional technique uses a linear solenoid as an actuator for driving an EGR control valve, detects the valve position of the EGR control valve, and detects the detected position. It is proposed that the target valve position corresponding to the target opening is compared and the duty ratio output to the linear solenoid is corrected according to the comparison result.
[0005]
[Problems to be solved by the invention]
Among the above-described conventional techniques, the technique described in Japanese Patent Publication No. 2-46787 only proposes zero learning, and the technique described in Japanese Patent Laid-Open No. 8-200184 also performs feedback control using a corrected basic command value. In this case, when a pulse motor in which the command value and the corresponding valve opening coincide with each other is used as an actuator, good responsiveness can be achieved, but the zero point learning of the EGR control valve opening is not performed. Therefore, there is a disadvantage that the desired accuracy cannot be obtained.
[0006]
Furthermore, the technology described in Japanese Patent Laid-Open No. 7-293350 has a disadvantage that the response and convergence are not necessarily sufficient in an operation region where disturbance due to pulsation of the exhaust system or the intake system is large. It was difficult to improve sufficiently.
[0007]
Furthermore, in EGR control, the operation amount is often determined using a PI control law or a PID control law. However, if responsiveness is emphasized, overshoot and undershoot are similarly caused and sufficient responsiveness and convergence are achieved. If the operation amount is determined so as to avoid overshoot and undershoot, it takes time to converge to the target value, and still causes problems in terms of responsiveness and convergence. It was.
[0008]
Recently, in-cylinder spark-ignition internal combustion engines have been developed in which gasoline fuel is directly injected into the cylinders in order to improve emission performance and fuel efficiency. In stratified combustion, a large amount of recirculated gas is introduced, whereas in homogeneous combustion, only a relatively small amount of recirculated gas is introduced, and the combustion is frequently switched according to the operating state. . Therefore, in such an engine, in particular, it is required that the control responsiveness is improved and the control stability is good without causing overshoot or undershoot to the target value.
[0009]
Accordingly, an object of the present invention is to solve the above-mentioned disadvantages, calculate a deviation between the effective actual opening obtained by learning the zero point of the EGR control valve opening and the required opening, and to calculate the deviation and the effective actual opening. The amount of operation of the actuator that drives the EGR control valve is corrected based on the amount of change over time, so that control responsiveness and stability are improved without causing overshoot or undershoot to the target opening. Another object of the present invention is to provide an EGR control device for an internal combustion engine.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, in claim 1, an EGR passage that communicates an exhaust system and an intake system of an internal combustion engine, an EGR control valve that opens and closes the EGR passage, and an actuator that drives the EGR control valve; More specifically, in the EGR control apparatus for an internal combustion engine, which includes a linear solenoid (or DC motor) and an operation amount calculation means for periodically calculating an operation amount to be output to the actuator, the operation amount calculation means. The required opening calculating means for calculating the required opening of the EGR control valve according to at least the required torque, the actual opening detecting means for detecting the actual opening of the EGR control valve, and the calculated required opening When it is zero for a predetermined time, the EGR control valve is regarded as being in the zero opening position, and the detected actual opening is learned and corrected, Effective actual opening calculating means for calculating an effective actual opening based on the learning corrected actual opening; deviation calculating means for calculating a deviation between the required opening and the effective actual opening; and the calculated deviation; A correction operation amount calculation means for calculating a correction amount of the operation amount based on an amount of change in the effective actual opening over time, the correction amount is added to the previous output value of the operation amount, and the current operation amount is calculated. Operation amount output value calculating means for calculating an output value and operation amount output means for outputting the output value to the actuator are provided.
[0011]
In this way, the deviation between the effective actual opening obtained by learning the zero point of the EGR control valve opening and the required opening is calculated, and the correction amount is calculated based on the deviation and the change over time of the effective actual opening. Since the current output value is calculated by adding the manipulated variable to the previous output value, the control response and stability are improved without causing overshoot or undershoot to the target opening. Can be made.
[0012]
Further, when the calculated required opening is zero over a predetermined time, the EGR control valve is assumed to be at the zero opening position, and the detected actual opening is learned and corrected, and the effective opening is effective from the learning corrected actual opening. Since the zero point learning for calculating the actual opening is performed, the control accuracy can be improved particularly in the low opening region of the EGR control valve.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
[0014]
FIG. 1 is a schematic diagram showing an internal combustion engine EGR control apparatus according to an embodiment of the present invention as a whole, taking a cylinder injection type internal combustion engine as an example.
[0015]
In the figure, reference numeral 10 denotes an OHC in-line four-cylinder internal combustion engine (hereinafter referred to as “engine”), and intake air introduced from an air cleaner 14 disposed at the front end of the intake pipe 12 passes through a surge tank 16 and a throttle valve 18. Then, the air flow is adjusted, and then flows into the first (# 1) to fourth (# 4) cylinder (cylinder) 22 through two intake valves (not shown) through the intake manifold 20. . FIG. 1 shows only one cylinder.
[0016]
A piston 24 is movably provided in each of the cylinders 22, and a recess is formed at the top thereof. A combustion chamber 28 is formed between the top of the piston 24 and the inner wall of the cylinder head 26. An injector (fuel injection valve) 30 is provided near the center of the position facing the combustion chamber 28.
[0017]
The injector 30 is connected to a fuel tank 34 through a fuel supply pipe 32, pumped up by a fuel pump 34a disposed inside the fuel tank 34, and regulated to a predetermined high pressure by a high-pressure pump and a regulator (both not shown). When the fuel (gasoline fuel) is supplied and the valve is opened, the fuel is injected into the combustion chamber 28.
[0018]
A spark plug 36 is disposed in the combustion chamber 28 of the cylinder 22. The ignition plug 36 is supplied with ignition energy from an ignition device 38 including an ignition coil, and ignites a mixture of injected fuel and intake air at a predetermined ignition timing. The ignited air-fuel mixture burns and explodes, and drives the piston 24.
[0019]
As described above, the engine 10 according to this embodiment is an in-cylinder spark ignition type internal combustion engine that directly injects gasoline fuel into the combustion chamber 28 of each cylinder 22 via the injector 30.
[0020]
Exhaust gas after combustion is discharged to an exhaust (exhaust) manifold 40 through two exhaust valves (not shown), travels through an exhaust pipe 42, and reaches a NOx component removal catalyst device 44 and a three-way catalyst device 46. Then, it is purified and discharged out of the engine 10.
[0021]
Downstream of the exhaust manifold 40, the exhaust pipe 42 is connected to the intake pipe 12 downstream of the throttle valve 18 via an EGR pipe (EGR passage) 48. The EGR pipe 48 is provided with an EGR control valve 50 to open and close the EGR pipe 48. That is, the EGR control valve 50 is opened in a predetermined operation state, and recirculates a part of the exhaust gas to the intake system while adjusting the flow rate (EGR amount).
[0022]
More specifically, the EGR control valve 50 includes a valve body 50a, and the valve body 50a is attached to a plunger of a linear solenoid (actuator) 52 disposed adjacent to the EGR control valve 50 via a stem. An opening is formed in the extension portion 48a of the EGR pipe 48. When the core 52a is excited by energizing the linear solenoid 52 and the plunger is sucked, the valve body 50a is driven (lifted) upward in FIG. The position is moved to open the opening, and a part of the exhaust gas is recirculated (introduced) to the intake system via the EGR pipe 48.
[0023]
On the other hand, when the core 52a is demagnetized by stopping energization of the linear solenoid 52, the plunger descends via the return spring 52b and closes the opening, thereby preventing the exhaust gas from recirculating (introducing) into the intake system. . The energization of the linear solenoid 52 is duty controlled (PWM control) via a duty ratio (output duty ratio DOUT) as described later, and controlled to a target opening between the fully open position and the fully closed position according to the duty ratio. Is done.
[0024]
A lift sensor 50b is disposed in the vicinity of the EGR control valve 50, and outputs a signal corresponding to the lift amount of the valve body 50a, more specifically, the actual opening degree LIFT of the EGR control valve 50.
[0025]
The space above the liquid level of the fuel tank 34 is connected to the canister 54, and the evaporated fuel is sent to the canister 54 and adsorbed by the activated carbon filled therein. The canister 54 is connected to the intake pipe 12 downstream of the throttle valve 18 via the purge pipe 56. The purge pipe 56 is provided with a canister purge control valve 58, which is opened in a predetermined operation state to purge part of the evaporated fuel into the intake system while adjusting the flow rate (purge flow rate).
[0026]
Further, the throttle valve 18 is not mechanically connected to an accelerator pedal (not shown) disposed on the vehicle driver's seat floor, and the throttle valve 18 is connected to a pulse motor 60 and driven by the output thereof to be connected to the intake pipe 12. Open and close. Thus, the throttle valve 18 is driven by the DBW method.
[0027]
The piston 24 is connected to the crankshaft 64 via a connecting rod 62, and a crank angle sensor 66 is disposed in the vicinity of the crankshaft 64. The crank angle sensor 66 includes a pulsar 66a attached to the crankshaft 64 and a magnetic pickup 66b disposed to face the pulsar 66a. The crank angle sensor 66 outputs a CYL signal for cylinder discrimination at every crank angle of 720 degrees and a BTDC predetermined crank angle of each cylinder 22. And a CRK signal at every 30 degrees of crank angle (hereinafter referred to as “STAGE”) obtained by subdividing the TDC signal interval into six.
[0028]
A throttle opening sensor 68 is connected to the pulse motor 60 and outputs a signal corresponding to the opening TH of the throttle valve 18 through the pulse motor opening.
[0029]
An absolute pressure (MAP) sensor 70 is provided in the vicinity of the arrangement position of the throttle valve 18 in the intake pipe 12, and intake pressure downstream of the throttle is introduced via a passage (not shown) to respond to the absolute pressure PBA (engine load) in the intake pipe. Output the signal. An intake air temperature sensor 72 is provided in the intake pipe 12 upstream of the position where the throttle valve 18 is disposed, and outputs a signal corresponding to the intake air temperature TA.
[0030]
A water temperature sensor 74 is provided in the vicinity of the cylinder 22 and outputs a signal corresponding to the engine water temperature TW. One air-fuel ratio sensor 76 is provided in the exhaust pipe 42 downstream of the exhaust manifold 40 and upstream of the catalyst devices 44, 46, and is a signal proportional to the exhaust air-fuel ratio, more precisely, the oxygen concentration in the exhaust gas. Is output.
[0031]
Further, the downstream side of the catalyst devices 44 and 46 is O. ₂ A sensor 80 is provided and outputs a signal that reverses whenever the exhaust air-fuel ratio changes leaner or richer than the stoichiometric air-fuel ratio.
[0032]
Further, an accelerator opening sensor 82 is provided in the vicinity of the accelerator pedal, and outputs a signal corresponding to the accelerator opening (accelerator pedal position) AP operated by the driver. An atmospheric pressure sensor 84 is provided at an appropriate position of the engine 10 and outputs a signal corresponding to the atmospheric pressure PA where the engine 10 is located.
[0033]
These sensor outputs are sent to an electronic control unit (hereinafter referred to as “ECU”) 90. The ECU 90 includes a microcomputer and includes an input circuit 90a, a CPU 90b, a memory 90c, an output circuit 90d, and a counter (not shown).
[0034]
The CRK signal output from the crank angle sensor 66 is counted by a counter, and the engine speed NE is detected and stored (stored) in the memory 90c. Other sensor outputs are subjected to A / D conversion processing and the like, and the memory 90c. (Stored). The ECU 90 calculates the fuel injection amount and the ignition timing based on the detected engine speed NE and the input sensor output value as described later, and controls the EGR (exhaust gas recirculation).
[0035]
FIG. 2 is a functional block diagram functionally showing the operation of the ECU 90 shown in FIG.
[0036]
The ECU 90 includes a required torque calculation unit 100, a combustion state determination unit 102, and an operation parameter determination unit 104 as illustrated. The required torque calculation unit 100 calculates a required torque (target engine load or driver request output) PMCMD required for the engine 10 from the detected engine speed NE and the accelerator pedal opening AP.
[0037]
More specifically, the combustion state determination unit 102 calculates the calculated required torque from the calculated required torque PMCMD, the engine speed NE, the engine water temperature TW, the effective actual opening degree LACT (described later) of the EGR control valve 50, and the like. An operation mode (combustion mode) is determined from PMCMD and the detected engine speed NE so that the fuel efficiency and emission performance are the best, and the target air-fuel ratio KCMD is set (determined).
[0038]
Specifically, when the calculated target torque PME is a high load, the combustion state determination unit 102 sets the operation mode, the target air-fuel ratio KCMD to the theoretical air-fuel ratio or the vicinity thereof, for example, 12.0: 1 to 15 Determine the theoretical air-fuel ratio operation mode to be set to 0.0: 1.
[0039]
When the calculated target torque PME is a medium load, the combustion state determination unit 102 sets the operation mode to an air-fuel ratio leaner than the stoichiometric air-fuel ratio, for example, 15.0: 1 to 22.2. The premixed lean operation mode is set to 0: 1, and when the load is low, the lean air / fuel ratio is set to a lean air / fuel ratio, for example, 22.0: 1 to 60.0: 1. The stratified charge combustion operation mode is determined.
[0040]
As described above, the engine 10 has two lean combustion operation modes including the premixed lean operation mode and the stratified combustion operation mode. The operation mode is labeled ST. EMODE0 and flag F.E. It is expressed in CMD. When CMD = 1, double injection mode; When CMD = 0, ST. When EMOD0 = 0, the stoichiometric air-fuel ratio operation mode; When CMD = 0, ST. When EMOD0 = 1, premixed lean operation mode; When CMD = 0, ST. When EMOD0 = 2, it means the stratified combustion operation mode.
[0041]
The operation parameter determination unit 104 calculates the output fuel injection amount TOUT from the detected engine speed NE and the intake pipe absolute pressure (engine load) PBA and the like, and based on the determined operation mode, the theoretical air-fuel ratio operation mode or pre- When the mixed lean operation mode is determined, fuel injection is performed through the injector 30 at a predetermined injection timing θinj (determined according to the operation state) of the intake stroke. The injected fuel is integrated with the intake air, and the operation parameter determination unit 104 ignites the ignition device 38 and the ignition plug 36 at a predetermined ignition timing θig (according to the operation state) and performs premix combustion (homogeneous combustion). ).
[0042]
When the operation parameter determination unit 104 is determined to be in the stratified charge combustion operation mode, the fuel injection is performed in the compression stroke to generate stratified charge combustion (Direct Injection Stratified Charge), and the stoichiometric air fuel ratio operation mode or the premixed lean operation is performed. When the mode is determined, fuel injection is performed in the intake stroke to cause uniform combustion.
[0043]
The operation parameter determination unit 104 performs fuel injection so that the air-fuel ratio in the vicinity of the spark plug is 12.0: 1 to 15.0: 1 regardless of the operation mode (load), and calculates the calculated ignition timing. The air-fuel mixture is ignited through the ignition device 38 and the ignition plug 36 at a crank angle corresponding to.
[0044]
Further, the operation parameter determination unit 104 determines and outputs an energization (throttle opening) command value THCMD to the pulse motor 60, a command value VTCCMD to a drive circuit of a variable valve timing mechanism (not shown), and the like. EGR control including calculation of the required opening degree LCMD of the EGR control valve 50 is performed from the detected engine speed NE and the required torque PMCMD.
[0045]
Next, the operation of the EGR control device for an internal combustion engine according to this embodiment will be described. Note that this operation is specifically the operation of the ECU 90, and more specifically, the operation of the operation parameter determination unit 104.
[0046]
FIG. 3 is a flowchart showing the operation. The illustrated program is executed at a predetermined cycle every 10 msec.
[0047]
In the following, first, in S10, it is determined whether or not the value of the required opening degree LCMD of the EGR control valve 50 is not zero. As described above, the required opening degree LCMD is a value determined (calculated) from the engine rotational speed NE or the like. More specifically, the detected engine rotational speed NE and the required engine speed are calculated in another routine (not shown). It is determined (calculated) by searching a preset characteristic (map) from the torque PMCMD.
[0048]
When the result is affirmative in S10, the process proceeds to S12, and the output duty ratio basic value previous value db1 (previous cycle calculated value. The value calculated in the previous program loop of the basic value db of the output duty ratio DOUT, that is, the previous operation amount It is determined whether or not the output value is not 0. If the result is affirmative, the process proceeds to S14, where it is determined whether or not the calculated required opening degree LCMD exceeds a predetermined value LCMDDBIS for initial value determination.
[0049]
When the result in S14 is affirmative, the routine proceeds to S16, where the output duty ratio basic value previous value db1 is replaced with the appropriately set high opening side initial value DBISH, and when the result is negative, the routine proceeds to S18, where the output duty ratio basic value The previous value db1 is replaced with the initial value DBISL on the low opening side which is set as appropriate.
[0050]
Here, the reason why the previous value of the output duty ratio basic value is replaced with a predetermined value according to the required opening is to improve the initial response. If the determination at S12 is negative, the processing from S14 to S18 is skipped.
[0051]
Next, the process proceeds to S20, and when the calculated required opening degree LCMD is zero for a predetermined time (for example, 3 sec) in another routine (not shown) according to the technique proposed in Japanese Patent Publication No. 2-46787 described above, the EGR control valve 50 Is corrected by learning the actual opening LIFT detected as being at the zero opening position. Then, an effective actual opening (hereinafter referred to as “LACT”) is calculated based on the learning-corrected actual opening, and the obtained effective actual opening LACT is used as the effective actual opening current value lact. Replace with 0.
[0052]
Next, the process proceeds to S22, and the effective actual opening current value lact. The deviation d1 is calculated by subtracting 0, and the process proceeds to S24, where the PID correction term is calculated according to the illustrated method.
[0053]
That is, first, the effective actual opening current value ract. From 0 to the previous effective actual opening value lact. The proportional correction term dbp is calculated by subtracting 1 and multiplying the difference obtained (in other words, the effective actual opening change amount) by the proportional gain KBPE1 set as appropriate. Further, the integral correction term dbi is calculated by multiplying the deviation d1 by an integral gain KBIE1 set as appropriate.
[0054]
Further, the actual actual opening current value lact. From 0, the previous effective actual opening value ract. 1 to the value obtained by doubling the effective actual opening before the actual value. The product obtained by adding 2 is subtracted, and a differential correction term dbd is calculated by multiplying the obtained difference (in other words, the effective actual opening change amount) by an appropriately set differential gain KBDE1.
[0055]
Then, as shown in the figure, the PID correction term ddb is calculated from the calculated three types of correction terms. As described above, the PID correction term ddb is calculated based on the deviation between the required opening degree LCMD and the effective actual opening degree (current value lact.0) and the effective actual opening change amount, and from the integral correction term to the proportional correction term and the derivative. It is calculated from the I-PD control law that subtracts the correction term.
[0056]
Next, in S26, the calculated PID correction term dbb is added to the output duty ratio basic value previous value db1, and the resulting sum is set as the output duty ratio basic value current value db. A limit check of the value db is performed.
[0057]
That is, first, in S28, it is determined whether the output duty ratio basic value current value db exceeds an appropriately set upper limit value DBLMTH or whether the output duty ratio basic value current value db is less than an appropriately set lower limit value DBLMTL, If the determination is affirmative, the process proceeds to S30, where it is determined again whether the output duty ratio basic value current value db exceeds the upper limit value DBLMTH. If the determination is affirmative, the process proceeds to S32, and the output duty ratio basic value current value db is set to the upper limit value. In step S34, the output duty ratio basic value current value db is replaced with the upper limit value DBLMTH in preparation for the next calculation.
[0058]
On the other hand, when proportional in S30, the process proceeds to S36, where the output duty ratio basic value current value db is replaced with the lower limit value DBLMTL, and the process proceeds to S38, and the output duty ratio basic value current value db is similarly set to the lower limit in preparation for the next calculation. Replace with the value DBLMTL. If the result in S28 is NO, the processing from S30 to S38 is skipped.
[0059]
When the result in S10 is negative, the process proceeds to S40, where the output duty ratio basic value current value db is set to 0, the process proceeds to S42, the output duty ratio basic value previous value db1 is set to 0, the process proceeds to S44, and the PID correction term dbb is set. 0.
[0060]
Next, the process proceeds to S46, and a battery voltage correction is performed by searching a table showing its characteristics in FIG. 4 from an input (detected value) VBAT from a voltage sensor (not shown in FIG. 1) for detecting the voltage of the in-vehicle battery (not shown). The term KDBVB is calculated, and the process proceeds to S48, where the output duty ratio basic value current value db is multiplied by the battery voltage correction, and the product thus obtained is set as the output duty ratio current value DOUT.
[0061]
The operation parameter determination unit 104 outputs (energizes) the output duty ratio current value DOUT calculated in this way to the linear solenoid 52 through a drive circuit (not shown) as an operation amount, and drives the EGR control valve 50 in the valve opening direction. .
[0062]
Next, in S50, the output duty ratio basic value current value db is replaced with the previous value db1 and the effective actual opening previous value lact. 1 is set to the previous value lact. 2 and its current value lact. 0 to its previous value lact. Rewrite as 1.
[0063]
5 and 6 are simulation data diagrams showing the effects of the EGR control device for an internal combustion engine according to this embodiment. FIG. 5 shows the case where the EGR control valve 50 is driven in the opening direction, and FIG. 6 is the driving direction in the closing direction.
[0064]
5 and 6, the symbol a indicates the required opening degree LCMD. The symbol b indicates the effective actual opening degree LACT calculated by the control according to this embodiment, and the symbol c indicates the effective actual opening degree LACT calculated by the prior art.
[0065]
As is apparent from FIG. 5, in the valve opening direction, the effective actual opening degree LACT calculated by the conventional technique has an overshoot with respect to the required opening degree LCMD, whereas the control according to this embodiment is performed. The calculated effective actual opening degree LACT does not cause overshoot.
[0066]
Further, as is apparent from FIG. 6, the effective actual opening degree LACT calculated by the conventional technique with respect to the required opening degree LCMD also causes an undershoot in the valve closing direction. -The effective actual opening degree LACT calculated by PD control does not cause an undershoot.
[0067]
The symbol d indicates the output duty ratio DOUT calculated by the control according to this embodiment, and the symbol e indicates the output duty ratio DOUT calculated by the conventional technique.
[0068]
As apparent from FIGS. 5 and 6, the output duty ratio DOUT calculated by the control according to this embodiment in both the valve opening direction and the valve closing direction is more responsive than that calculated by the prior art. Has improved.
[0069]
In this embodiment, as described above, the deviation d1 between the effective actual opening degree LACT (act.0) obtained by learning the zero point of the opening degree of the EGR control valve 50 and the required opening degree LCMD is calculated. Then, a PID correction term ddb (correction amount) is calculated based on the deviation and the effective change over time of the effective actual opening, and is added to the output duty ratio basic value current value db (previous output value of the manipulated variable). Since it is configured to calculate the output duty ratio current value DOUT (current output value of the manipulated variable) by correcting the battery voltage, control responsiveness can be achieved without causing overshoot or undershoot to the target opening. Stability can be improved.
[0070]
Further, the actual opening LIFT detected by assuming that the EGR control valve 50 is at the zero opening position when the calculated required opening LCMD is zero for a predetermined time (for example, 3 sec) is learned and corrected, Since the zero point learning for calculating the effective actual opening degree LACT based on the learning-corrected actual opening degree is performed, the control accuracy can be improved particularly in the low opening degree region of the EGR control valve.
[0071]
As described above, the EGR control device for an internal combustion engine according to this embodiment has an EGR passage (EGR pipe 48) that communicates an exhaust system and an intake system of the internal combustion engine (engine 10), and an EGR control that opens and closes the EGR passage. A valve 50 and an actuator for driving the EGR control valve, more specifically, a linear solenoid 52, and an operation amount to be output to the actuator (output duty ratio DOUT, more specifically, output duty ratio basic value db) ) In an EGR control device for an internal combustion engine provided with an operation amount calculation means (ECU 90, more specifically, an operation parameter determination unit 104) periodically, the operation amount calculation means includes at least a required torque PMCMD (more specifically, (Eg, the engine speed NE and the required torque PMCMD) Requested opening degree calculating means (ECU 90, operating parameter determining unit 104) for calculating the opening degree LCMD, actual opening degree detecting means (lift sensor 50b) for detecting the actual opening degree LIFT of the EGR control valve, the calculated required opening degree When the degree is zero over a predetermined time, the EGR control valve is regarded as being in the zero opening position, and the detected actual opening is learned and corrected, and the effective actual opening is performed based on the learning corrected actual opening. Effective actual opening calculating means (S20) for calculating the degree LACT (more specifically, the effective actual opening current value 1act.0), and a deviation calculating means for calculating a deviation d1 between the required opening and the effective actual opening. (S22), the calculated deviation, and the amount of change in the effective actual opening over time (more specifically, the difference between the current value and the previous value of the effective actual opening and the previous value multiplied by 2) And the value obtained two times before Based on the difference obtained by subtracting the sum), the correction operation amount calculation means (S24) for calculating the correction amount (PID correction term ddb) of the operation amount, the previous output value (output duty ratio basic value) of the operation amount Operation amount output value calculating means (S26) for calculating the current output value of the operation amount by adding the correction amount to the current value db), and operation amount output means (S28, S) for outputting the output value to the actuator S46 to S48).
[0072]
Although the embodiment of the present invention has been described by taking a cylinder injection type spark ignition type gasoline engine as an example, the present invention is very effective when applied to such an engine, but gasoline combustion is performed before the intake valve. It is also effective for ordinary engines that inject fuel.
[0073]
In addition, although a linear solenoid is illustrated as an example of an actuator that drives the EGR control valve 50, other driving means such as a DC motor may be used.
[0074]
Although the pulse motor 60 is used to drive the throttle valve 18, an actuator such as a torque motor or a DC motor may be used instead of the pulse motor 60.
[0075]
【The invention's effect】
According to the first aspect, the deviation between the effective actual opening obtained by learning the zero point of the EGR control valve opening and the required opening is calculated, and the change over time of the deviation and the effective actual opening is calculated. Since the current output value is calculated by calculating the correction amount based on this and adding it to the previous output value of the manipulated variable, control response without causing overshoot or undershoot to the target opening And stability can be improved.
[0076]
Further, when the calculated required opening is zero for a predetermined time, the EGR control valve is assumed to be at the zero opening position, and the actual opening detected is learned and corrected, and the actual opening that has been corrected by learning is corrected. Since the zero learning for calculating the effective actual opening is performed, the control accuracy can be improved particularly in the low opening region of the EGR control valve.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an overall EGR control apparatus for an internal combustion engine according to the present invention.
FIG. 2 is a functional block diagram functionally showing the operation of the ECU of the control device of FIG. 1 while displaying an operation parameter determination unit and the like.
3 is a main flow chart showing the operation of the apparatus of FIG. 1, more specifically, the operation of the operation parameter determination unit shown in FIG.
4 is an explanatory graph showing table characteristics of a battery voltage correction term KDBVB in the flowchart of FIG. 3. FIG.
FIG. 5 is a simulation data diagram showing an effective actual opening degree calculated (determined) by the apparatus of FIG. 1 in comparison with the prior art.
FIG. 6 is a simulation data diagram showing the effective actual opening and the like calculated (determined) by the apparatus of FIG. 1 in comparison with the prior art.
[Explanation of symbols]
10 Internal combustion engine
12 Intake pipe
22 cylinders
28 Combustion chamber
48 EGR pipe
50 EGR control valve
50b Lift sensor (actual opening detection means)
52 Linear solenoid (actuator)
66 Crank angle sensor
70 Absolute Pressure (MAP) Sensor
90 Electronic control unit (ECU)
100 Required torque calculator
102 Combustion state determination unit
104 Operation parameter determination unit

Claims (1)

An EGR passage that communicates an exhaust system and an intake system of an internal combustion engine, an EGR control valve that opens and closes the EGR passage, an actuator that drives the EGR control valve, and an operation amount to be output to the actuator is periodically In the EGR control device for an internal combustion engine provided with the operation amount calculation means for calculating the operation amount, the operation amount calculation means comprises:
a. Required opening degree calculating means for calculating a required opening degree of the EGR control valve according to at least the required torque;
b. An actual opening detecting means for detecting an actual opening of the EGR control valve;
c. When the calculated required opening is zero for a predetermined time, the EGR control valve is regarded as being in the zero opening position, the detected actual opening is learned and corrected, and the learned corrected actual opening is Effective actual opening calculation means for calculating the effective actual opening based on
d. Deviation calculating means for calculating a deviation between the required opening and the effective actual opening;
e. A correction operation amount calculation means for calculating a correction amount of the operation amount based on the calculated deviation and the amount of change in the effective actual opening over time;
f. An operation amount output value calculating means for calculating the current output value of the operation amount by adding the correction amount to the previous output value of the operation amount;
And g. An operation amount output means for outputting the output value to the actuator,
An EGR control device for an internal combustion engine, comprising:

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