JP2009108759A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve an exhaust property and fuel economy by control of an highly accurate EGR device, in an internal combustion engine mounted on a hybrid vehicle. <P>SOLUTION: An engine ECU 1000 sets a control target flow rate of recirculating gas in response to an operation state of an engine 120, and controls an EGR valve 502 in response to an opening command value generated based on the control target flow rate. The engine ECU 1000 learns actual opening being actual EGR valve opening for securing the control target flow rate when detecting the occurrence of flow rate reduction in the EGR valve 502 based on an operation when knocking is caused. The engine ECU 1000 also reflects the learnt actual opening on EGR control as the opening command value in an engine operating state when the knocking is caused and an opening command value in an engine operation state when the knocking is not caused when setting the engine operation state and the control target flow rate in the same. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine in a hybrid vehicle including an internal combustion engine and another drive source.

  Japanese Patent Laid-Open No. 2005-171765 (Patent Document 1) discloses an exhaust gas for controlling an exhaust gas recirculation amount by adjusting an opening degree of an exhaust gas recirculation control valve provided in an exhaust gas recirculation passage for recirculating exhaust gas from an exhaust passage to an intake passage. A control device for an internal combustion engine having a recirculation device (hereinafter also referred to as an EGR (Exhaust Gas Recirculation) device) is disclosed.

According to this control device for an internal combustion engine, the exhaust gas recirculation control valve is temporarily opened during idling engine speed feedback control in which the engine speed is feedback-controlled toward the target value, and the control parameter is changed according to the opening operation. Based on this, an opening correction value of the exhaust gas recirculation control valve is calculated. Then, by reflecting the calculated opening correction value in the setting of the ignition timing, it is possible to effectively offset and absorb the opening error and variation of the exhaust gas recirculation control valve due to deterioration over time and changes in environmental factors. Set the ignition timing accurately.
JP 2005-171765 A JP 2004-116466 A

  By the way, in recent years, as one of countermeasures for environmental problems, a hybrid vehicle further equipped with an electric motor as another driving force source of the internal combustion engine has attracted attention. In the hybrid vehicle, regardless of the accelerator operation amount of the driver, the operation by the engine and the operation by the electric motor are automatically switched to perform control so as to obtain the highest efficiency.

  In an engine mounted on this hybrid vehicle, combustion at a stoichiometric air-fuel ratio with good combustion stability is employed to improve exhaust properties. However, in the high output region, the exhaust gas temperature rises due to an increase in combustion heat, so that the exhaust gas purification catalyst of the purification device may deteriorate. For this reason, conventionally, in the high output region, by appropriately increasing the fuel injection amount, the rise in the exhaust gas temperature is suppressed by the vaporization latent heat of the fuel that does not burn, thereby suppressing the deterioration of the exhaust gas purification catalyst. .

  However, such a method of increasing the fuel injection amount to suppress the rise in the exhaust gas temperature has a problem that the fuel consumption deteriorates due to the increase in the fuel injection amount required for temperature adjustment. In addition, since fuel is performed on the richer side than the stoichiometric air-fuel ratio, there arises a problem that exhaust properties deteriorate.

  In response to this, by operating the EGR device to recirculate the exhaust gas to the combustion chamber, it is possible to slow the combustion in the fuel chamber and suppress an increase in the exhaust gas temperature. However, when the exhaust gas is recirculated into the combustion chamber, fresh air, that is, new air supplied from the outside is reduced, and the amount of combustible air is substantially reduced, so that the engine output is lowered. For this reason, in a vehicle using a conventional engine as a driving force source, the EGR device has to be stopped in order to ensure engine output in a high output region, and it has been difficult to suppress an increase in exhaust gas temperature. . In this regard, the hybrid vehicle is configured to assist the engine by driving the electric motor when the engine load is a high load of a predetermined value or higher, and thus the EGR device can be operated even in a high output region. . Thereby, since it is possible to suppress an increase in the exhaust gas temperature without increasing the fuel injection amount, combustion at the stoichiometric air-fuel ratio can be maintained.

  However, although the method of operating the EGR device in the high output region in this way is effective in improving the exhaust properties and fuel consumption, the control target value and the actual value of the exhaust gas recirculation amount due to changes in environmental factors, aging, etc. If there is a deviation between the two, the exhaust gas temperature may increase immediately. Therefore, the EGR device requires highly accurate control of the reflux control valve.

  Therefore, the present invention has been made to solve such problems, and an object of the present invention is to improve exhaust properties and fuel consumption by controlling an EGR device with high accuracy in an internal combustion engine mounted on a hybrid vehicle. It is to be.

  According to an aspect of the present invention, an internal combustion engine control apparatus is an internal combustion engine control apparatus in a vehicle including an internal combustion engine and another driving force source. The internal combustion engine is provided with an exhaust gas recirculation device for recirculating a part of the exhaust gas to the intake pipe of the internal combustion engine again through the recirculation valve. The control device sets a control target flow rate of the recirculation gas by the exhaust gas recirculation device according to the engine operation state, and a recirculation gas control means for controlling the recirculation valve according to the opening command value generated based on the control target flow rate. And detecting the occurrence of a decrease in flow rate from the control target flow rate of the recirculation gas by the exhaust gas recirculation device based on the knocking detection means for detecting the occurrence of knocking in the internal combustion engine and the engine operating state when the occurrence of knocking is detected When the reflux device abnormality detection means and the flow rate drop are detected, the actual opening degree which is the actual opening degree of the reflux valve for securing the control target flow rate is learned based on the detection signal from the knocking detection means. Actual opening degree learning means. The recirculation gas control means uses the learned actual opening, the opening command value in the engine operating state when the occurrence of knocking is detected, and the engine operation when knocking does not occur with the same engine operating state and the control target flow rate. The opening command value in the state is reflected in the control of the reflux valve.

  Preferably, the control device for the internal combustion engine includes an ignition timing control means for calculating a retard amount with respect to the basic ignition timing in accordance with the occurrence of knocking, and the engine operating state when the occurrence of knocking is detected is determined by the exhaust gas recirculation device. It further includes an operation region determination means for determining whether or not it is an operation region. The reflux device abnormality detection means is when the calculated retard amount exceeds a predetermined threshold and when the engine operating state when the occurrence of knocking is detected is the operating region of the exhaust gas reflux device, Detects a decrease in flow rate.

  Preferably, the actual opening degree learning means drives the reflux valve while gradually increasing the opening degree command value, and the opening degree instruction value when the detection signal from the knocking detection means is not input by this driving is obtained as the actual opening degree value. Get as.

  Preferably, the exhaust gas recirculation device includes a step motor for driving the recirculation valve. The actual opening learning means drives the step motor while gradually increasing the target step number, and the target step number when the detection signal from the knocking detection means is not input by this drive is the actual step corresponding to the actual opening degree. Get as a number.

  Preferably, the recirculation gas control means has in advance an opening degree command value generated based on the control target flow rate for each engine operation state, and for a plurality of engine operation states having the same control target flow rate. The actual opening learned in correspondence with the control target flow rate is reflected in the control of the recirculation valve as the opening command value.

  According to the present invention, since the EGR device can be controlled with high accuracy in an internal combustion engine mounted on a hybrid vehicle, combustion at a stoichiometric air-fuel ratio is possible regardless of the engine operating state. As a result, further improvement in environmental performance and fuel consumption performance is realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

  FIG. 1 is a block diagram illustrating a configuration of a hybrid vehicle shown as an example of a vehicle on which an internal combustion engine control apparatus according to an embodiment of the present invention is mounted. The present invention is not limited to the hybrid vehicle shown in FIG.

  The hybrid vehicle includes an internal combustion engine (hereinafter simply referred to as an engine) 120 such as a gasoline engine or a diesel engine, and a motor generator (MG) 140 as drive sources. In FIG. 1, for convenience of explanation, the motor generator 140 is expressed as a motor 140A and a generator 140B (or a motor generator 140B). However, depending on the traveling state of the hybrid vehicle, the motor 140A functions as a generator, The generator 140B functions as a motor.

  In addition to this, the hybrid vehicle transmits a power generated by the engine 120 and the motor generator 140 to the drive wheels 160, and a reduction gear 180 that transmits the drive of the drive wheels 160 to the engine 120 and the motor generator 140, and the engine 120. Power split mechanism (for example, planetary gear mechanism) 260 that distributes the generated power to two paths of drive wheel 160 and generator 140B, travel battery 220 that charges power for driving motor generator 140, and travel Inverter 240 that performs current control while converting DC of motor battery 220 and AC of motor 140 </ b> A and generator 140 </ b> B, boost converter 242 that performs voltage conversion between traveling battery 220 and inverter 240, and traveling battery 220 Management and control of charge / discharge status A battery control unit (hereinafter referred to as a battery ECU (Electronic Control Unit)) 1020, an engine ECU 1000 that controls the operating state of the engine 120, a motor generator 140, a battery ECU 1020, an inverter 240, and the like are controlled according to the state of the hybrid vehicle. The MG_ECU 1010, the battery ECU 1020, the engine ECU 1000, the MG_ECU 1010, and the like are mutually managed and controlled to control the entire hybrid system so that the hybrid vehicle can operate most efficiently.

  In FIG. 1, each ECU is configured separately, but may be configured as an ECU in which two or more ECUs are integrated (for example, MG_ECU 1010 and HV_ECU 1030 as shown by a dotted line in FIG. 1). An example is an integrated ECU).

  The power split mechanism 260 uses a planetary gear mechanism (planetary gear) in order to distribute the power of the engine 120 to both the drive wheels 160 and the motor generator 140B. By controlling the rotation speed of motor generator 140B, power split mechanism 260 also functions as a continuously variable transmission. The rotational force of the engine 120 is input to the planetary carrier (C), which is transmitted to the motor generator 140B by the sun gear (S) and to the motor and the output shaft (drive wheel 160 side) by the ring gear (R). When the rotating engine 120 is stopped, since the engine 120 is rotating, the kinetic energy of this rotation is converted into electric energy by the motor generator 140B, and the rotational speed of the engine 120 is reduced.

  In a hybrid vehicle equipped with a hybrid system as shown in FIG. 1, the hybrid vehicle travels only by the motor 140 </ b> A of the motor generator 140 when the engine 120 is inefficient, such as when starting or running at a low speed. During normal travel, for example, the power split mechanism 260 divides the power of the engine 120 into two paths, and on the other hand, the drive wheels 160 are directly driven, and on the other hand, the generator 140B is driven to generate power. At this time, the motor 140A is driven by the generated electric power to assist driving of the driving wheels 160. Further, at the time of high speed traveling, electric power from the traveling battery 220 is further supplied to the motor 140A to increase the output of the motor 140A and to add driving force to the driving wheels 160. On the other hand, at the time of deceleration, motor 140 </ b> A driven by drive wheel 160 functions as a generator to perform regenerative power generation, and the collected power is stored in traveling battery 220. When the amount of charge of traveling battery 220 decreases and charging is particularly necessary, the output of engine 120 is increased to increase the amount of power generated by generator 140B to increase the amount of charge for traveling battery 220. Of course, control is performed to increase the drive amount of the engine 120 as necessary even during low-speed traveling. For example, it is necessary to charge the traveling battery 220 as described above, to drive an auxiliary machine such as an air conditioner, or to raise the temperature of the cooling water of the engine 120 to a predetermined temperature.

  Next, engine 120 controlled by engine ECU 1000 that is the control device for the internal combustion engine according to the embodiment of the present invention will be described. FIG. 2 is a schematic configuration diagram of an engine system controlled by engine ECU 1000.

  Referring to FIG. 2, in this engine system, air through air cleaner 200 is introduced into the combustion chamber of engine 120. At that time, the intake air amount is detected by the air flow meter 202, and a signal representing the intake air amount is input to the engine ECU 1000. Further, the amount of intake air varies depending on the opening degree of the throttle valve 300. The opening degree of the throttle valve 300 is changed by a throttle motor 304 that operates based on a signal from the engine ECU 1000. The opening degree of the throttle valve 300 is detected by the throttle position sensor 302, and a signal indicating the opening degree of the throttle valve 300 is input to the engine ECU 1000.

  The fuel is stored in the fuel tank 400 and injected from the high pressure fuel injector 804 to the combustion chamber via the high pressure fuel pump 800 by the fuel pump 402. An igniter-integrated ignition coil 808, in which a control signal is input from the engine ECU 1000, is a mixture of air introduced from the intake manifold and fuel injected from the fuel tank 400 via the high-pressure fuel injector 804 into the combustion chamber. It is ignited and burns. In addition to the configuration in which the in-cylinder injector for injecting the fuel into the cylinder is provided as shown in FIG. 2, the intake passage injection for injecting the fuel into the intake port or / and the intake passage. It is good also as a structure which provides the injector for engines, or the structure which provides both the in-cylinder injector and the intake manifold injector.

  The exhaust gas after the air-fuel mixture burns passes through the exhaust manifold, passes through the three-way catalytic converter 900 and the three-way catalytic converter 902, and is discharged to the atmosphere.

  As shown in FIG. 2, this engine system has an EGR device whose flow rate is controlled by an EGR valve 502 from the downstream side of the three-way catalytic converter 900 through the EGR pipe 500. This EGR device, also called an exhaust gas recirculation device, recirculates a part of the exhaust gas discharged from the engine 120 to the intake system and mixes it with a new air-fuel mixture to lower the combustion temperature, thereby reducing nitrogen oxide ( NOx) is suppressed or pumping loss is suppressed to improve fuel efficiency.

  FIG. 3 shows an enlarged view of the EGR device portion of FIG. 2, and FIG. 4 shows an enlarged view of the EGR valve 502 portion of the EGR device.

  As shown in FIGS. 3 and 4, the exhaust gas after passing through the three-way catalytic converter 900 is introduced to the EGR valve 502 through the EGR pipe 500. The EGR valve 502 is duty controlled by the engine ECU 1000. Engine ECU 1000 controls the opening degree of EGR valve 502 based on various signals such as the engine speed and a signal from accelerator position sensor 102.

  As shown in FIG. 3, the EGR valve 502 includes a stepping motor 502A that operates according to a control signal from the engine ECU 1000, a poppet valve 502C whose valve opening degree is linearly controlled by the stepping motor 502A, and a return spring 502B. including. Since the EGR gas recirculated to the combustion chamber has a high temperature and adversely affects the performance and durability of the EGR valve 502, a cooling water passage 502D for cooling with engine cooling water is provided.

  HV_ECU 1030 receives a signal representing an engine speed detected by an engine speed sensor (not shown) and a signal from accelerator position sensor 102 via engine ECU 1000. Further, HV_ECU 1030 receives a signal representing the vehicle speed detected by a wheel speed sensor (not shown). The HV_ECU 1030 outputs an engine control signal (for example, a throttle opening signal) to the engine ECU 1000 based on these signals.

  Engine ECU 1000 outputs an electronic throttle control signal to engine 120 based on the engine control signal and other control signals. Engine ECU 1000 generates a control signal for adjusting the opening degree of EGR valve 502 based on the operating state of engine 120 by a method described later, and outputs the generated control signal to stepping motor 502A.

  In the present embodiment, the EGR valve 502 in the EGR device has been described as being driven by the stepping motor 502A, but the present invention is not limited to this. For example, instead of an electric actuator such as the stepping motor 502A, an air-controlled EGR valve constituted by a solenoid valve and an air actuator having a diaphragm may be used.

  Referring to FIG. 2 again, in addition to such an EGR device, the following system is introduced in this engine system.

  A fuel injection control system is introduced into this engine system, and the amount of intake air is detected by the air flow meter 202 and the vacuum sensor 306 to control the fuel injection amount. Engine ECU 1000 controls the fuel injection amount and fuel injection timing according to the engine speed and the engine load so as to achieve an optimal combustion state based on signals from the sensors.

  In this engine system, the fuel injection amount is determined by the engine speed and the intake air amount (detected by the vacuum sensor 306 and the air flow meter 202). Further, the air-fuel ratio after start-up is feedback controlled by signals from oxygen sensors 710 and 712. That is, in the fuel injection control, the signal of each sensor is corrected to the basic injection time calculated according to the state of the engine, and fuel injection timing control and injection amount control are executed.

  In addition, an ignition timing control system is introduced in this engine system. Engine ECU 1000 calculates an optimal ignition timing based on signals from each sensor, and outputs an ignition signal to igniter-integrated ignition coil 808. The ignition timing is determined by the initial set ignition timing or the basic advance angle and the corrected advance angle. Further, in this engine system, when the occurrence of knocking is detected based on the knock detection signal from the knock sensor 704, the ignition timing is set to the basic ignition timing (ignition timing determined according to the engine speed and load). ), A knock control system (KCS) is introduced that gradually retards when knocking does not occur.

  The engine ignition timing is calculated by the engine ECU 1000 according to the operating state based on the engine speed signal, the signal from the cam position sensor, the intake flow rate signal, the throttle valve opening signal, the engine coolant signal, etc. Then, an ignition signal is output to the igniter-integrated ignition coil 808. That is, in the ignition timing control, correction based on the signal of each sensor is added to the basic ignition timing calculated according to the state of the engine to calculate an appropriate ignition timing.

  In addition, a throttle control system is introduced in this engine system. The throttle control system is controlled so that the opening degree of the throttle valve 300 calculated according to the state of the engine is corrected by the signal of each sensor so as to obtain an appropriate opening degree. That is, the engine ECU 1000 controls the opening degree of the throttle valve 300 using the throttle motor 304 so that the opening degree of the throttle valve 300 according to the combustion state of the engine becomes an appropriate opening degree.

  In addition, an idle speed control system is introduced in this engine system. This idle speed control system controls the first idle speed corresponding to the engine coolant temperature and the idle speed after engine warm-up. In the idle speed control, the intake air amount is calculated on the basis of signals from the air flow meter 202 and the vacuum sensor 306, and the engine ECU 1000 calculates the optimum opening of the throttle valve 300 and the injector valve opening time, and determines the idle speed. Move closer to the target speed.

  Although not shown in FIG. 1, there is a control method using an idle speed control valve in addition to the idle speed control using a throttle motor. This idle speed control valve controls the idle speed by adjusting the amount of air flowing through the bypass passage of the throttle valve.

(EGR control of engine ECU)
Hereinafter, the opening degree control of EGR valve 502 (hereinafter also referred to as EGR control) executed by engine ECU 1000 according to the present embodiment will be described in detail.

  As shown in FIG. 5, engine ECU 1000 sets in advance an operating region in which the EGR device is operated in the operating state (engine speed and load) of engine 120, and reads the throttle opening, intake air amount, engine Based on each data such as the rotational speed and the cooling water temperature, it is determined whether or not the operating state of the engine 120 is in the EGR operating region. If it is determined that the operating state of engine 120 is in the EGR operating region, engine ECU 1000 opens EGR valve 502. In this way, a part of the exhaust gas is recirculated to the intake system to reduce NOx in the exhaust gas.

  Here, referring to FIG. 5, the EGR operation region is set to a medium / low load operation state (corresponding to region RGN1) and high output (high load / high rotation) operation state (corresponding to region RGN2) of engine 120, respectively. Has been. In the EGR control according to the present embodiment, the EGR device is operated even at the time of high output operation. At the time of high output operation of the engine 120, the EGR device is stopped to increase the supply amount of fresh air and ensure the engine output. This is different from conventional EGR control.

  By adopting such a configuration, the fresh air is reduced and the amount of combustible air is substantially reduced by recirculating a large amount of exhaust gas to the intake system even during high output operation. It is possible to approach the stoichiometric air-fuel ratio (that is, the excess air ratio λ = 1) in a low state. Further, since the combustion heat is absorbed by the exhaust gas in the air-fuel mixture, an increase in the fuel injection amount for adjusting the exhaust gas temperature can be suppressed. Although the output of the engine 120 is reduced by operating the EGR device, a desired vehicle driving force can be obtained by driving the motor generator 140 to assist the engine output. As a result, combustion at the stoichiometric air-fuel ratio can be performed while suppressing an increase in exhaust gas temperature, so that exhaust properties and fuel efficiency can be improved.

  On the other hand, in order to realize combustion at such a stoichiometric air-fuel ratio, it is necessary to control the opening degree of the EGR valve 502 with high accuracy. In particular, in the EGR valve 502, when a flow rate decrease that reduces the flow rate of the exhaust gas recirculated to the intake system due to deterioration over time or the like occurs, there is a deviation between the control target value of the exhaust gas recirculation amount and the actual value. May occur, leading to an increase in exhaust gas temperature.

  Therefore, as described below, the control apparatus for an internal combustion engine according to the embodiment of the present invention detects the occurrence of knocking of engine 120 based on the operating state of engine 120 at the time of occurrence of knocking. It is configured to detect the actual opening that is the actual opening of the EGR valve 502 that is necessary to secure the control target value of the exhaust gas recirculation amount when knocking occurs while detecting a decrease in the flow rate. Further, the learned actual opening is reflected in the EGR control in the operating state of the engine 120 when knocking is not generated as the opening command value of the EGR valve 502 corresponding to the control target value of the exhaust gas recirculation amount. To do.

  FIG. 6 is a flowchart for illustrating the opening degree control of EGR valve 502 executed by engine ECU 1000 according to the embodiment of the present invention.

  Referring to FIG. 6, when a series of controls is started, engine ECU 1000 detects whether knock determination flag FKNOCK is “1”, that is, occurrence of knocking in knock sensor 704 (FIG. 2). It is determined whether or not (step S01). The knock determination flag FKNOCK is set to “1” when a knock detection signal is input from the knock sensor 704 in the KCS control routine executed by the engine ECU 1000, and when the knock detection signal is not input. Cleared to "0".

  When knocking determination flag FKNOCK is “0” (NO in step S01), engine ECU 1000 further determines whether or not learning control flag FEGRRE is “1” (step S08). The learning control flag FEGRRE is set to “1” when learning control of the actual opening of the EGR valve 502 is performed in response to detection of a decrease in the flow rate of the EGR valve 502, as will be described later. When learning control is not performed, it is cleared to “0”. Therefore, when learning control flag FEGRRE is not “1” (NO in step S08), engine ECU 1000 ends the series of processes.

  On the other hand, when knock determination flag FKNOCK is “1” (YES in step S01), engine ECU 1000 is calculated according to the knock detection signal from knock sensor 704 in the KCS control routine. The retard amount θK with respect to the basic ignition timing is acquired. Then, it is determined whether or not the acquired retardation amount θK is larger than a predetermined retardation amount α (step S02).

  Here, in the KCS control, the retard amount θK with respect to the basic ignition timing is set so as to increase as the occurrence frequency / degree of knocking detected by the knock sensor 704 increases. For example, if the EGR device has an abnormality and the flow rate decreases so that the flow rate of the exhaust gas recirculated to the intake system decreases, or if the deposit accumulation amount in the combustion chamber is large, the occurrence frequency / degree is high. The retardation amount θK is set to a large value. On the other hand, when the other factors, for example, the intake air temperature and the cooling water temperature are high, the occurrence frequency / degree of knocking is low, so the retardation amount θK is set to a small value.

  Therefore, the engine ECU 1000 sets a predetermined threshold value α in advance, and when the calculated retardation amount θK exceeds the predetermined threshold value α (in the case of YES in step S02), the flow rate decrease or combustion of the EGR valve It is determined that knocking has occurred due to the deposit amount in the room, and processing for detecting a decrease in the flow rate of the EGR valve 502 shown in step S03 is executed.

  On the other hand, when retard amount θK is equal to or smaller than predetermined threshold value α (NO in step S02), engine ECU 1000 has knocked due to the running state of the vehicle, use environment conditions, and the like. The series of processing is terminated.

  Next, engine ECU 1000 determines whether or not EGR operation determination flag FEGR is “1”, that is, engine 120, when retardation amount θK is larger than predetermined threshold value α (YES in step S02). It is determined whether or not the operating state is an EGR operating region (step S03). The EGR operation determination flag FEGR is set to “1” by the engine ECU 100 when the operation state of the engine 120 is in the EGR operation region (corresponding to the region RGN1 or RGN2 in FIG. 5). If the state is not in the EGR operating range, it is reset to “0”.

  If the EGR operation determination flag FEGR is “0” in step S03 (NO in step S03), engine ECU 1000 has knocked in the EGR non-operating region, so that knocking is performed in EGR valve 502. The series of processes is terminated by assuming that the flow is not caused by a decrease in the flow rate of the fuel, but is caused by the deposit amount in the fuel chamber.

  On the other hand, when EGR operation determination flag FEGR is “1” (YES in step S03), engine ECU 1000 knocks due to a decrease in the flow rate of EGR valve 502 despite being in the EGR operation region. It is estimated that it has occurred, and it is determined that there is an abnormality in the EGR device. Then, engine ECU 1000 executes learning control of the actual opening of EGR valve 502 shown in step S04 and subsequent steps. The actual opening degree of the EGR valve 502 is an actual opening degree of the EGR valve 502 necessary for securing a control target value of the exhaust gas recirculation amount when knocking occurs.

  Specifically, in step S04, engine ECU 1000 operates engine 120 based on an engine speed signal, a signal from a cam position sensor, an intake flow rate signal, a throttle valve opening signal, an engine coolant signal, and the like. Specify the state (load and speed). Next, engine ECU 1000 calculates a control target value of the exhaust gas recirculation amount for effectively reducing the NOx generation amount in the current operating state of engine 120 based on the identified operating state of engine 120. Based on the calculated control target value of the exhaust gas recirculation amount, a target step number ESTPT for adjusting the opening degree of the EGR valve 520 is calculated (step S05). The target step number ESTPTG corresponds to the “opening command value” of the EGR valve 502 in the present invention.

  Then, engine ECU 1000 outputs the calculated target step number ESTPTG to stepping motor 502A that drives EGR valve 502. When the stepping motor 502A receives the target step number ESTPTG, the stepping motor 502A rotates by the number of steps specified by the target step number ESTPTG to drive the poppet valve 502C of the EGR valve 502, thereby adjusting the opening degree of the EGR valve 502. .

  FIG. 7 is a diagram showing the relationship between the exhaust gas recirculation amount and the number of steps of the EGR valve 502 in the EGR device.

  Referring to FIG. 7, when the EGR device is normal, the relationship between the exhaust gas recirculation amount and the number of steps of EGR valve 502 increases proportionally as the number of steps increases according to line LN2 in the figure. have. Therefore, the engine ECU 1000 preliminarily possesses the relationship shown in FIG. 7 as a map in the calculation of the target step number ESTPTG shown in step S05 of FIG. 6, and the control target value (X in the figure) of the exhaust gas recirculation amount. ) Is calculated, the number of steps (corresponding to the number of steps S1 in the figure) corresponding to the control target value is extracted with reference to the map of FIG. 7 and set to the target number of steps.

  On the other hand, when there is an abnormality in the EGR device, the actual exhaust gas recirculation amount at the step number S1 is less than the control target value X as indicated by the line LN3 in the figure. Further, from FIG. 7, the step number S2 larger than the step number S1 is an actual step number (hereinafter also referred to as an actual step number) necessary to secure the control target value X of the exhaust gas recirculation amount. I understand.

  Therefore, in the present embodiment, the EGR device is operated while increasing the target step number ESTPT by a certain step number ΔESTP, and the EGR valve 502 is actually opened based on the knock detection signal from the knock sensor 704 that changes by this operation. The actual number of steps corresponding to the degree is learned. The learned actual step number is reflected in the setting of the target step number ESTPT as the step number of the EGR valve 502 for securing the exhaust gas recirculation amount control target value X.

  Specifically, engine ECU 1000 adds a predetermined step number ΔESTP set in advance to the target step number ESTPT calculated in step S05, and sets the added step number as a new target step number ESTPTG. (Step S06). Further, engine ECU 1000 sets a learning control flag FEGRRE indicating that the actual number of steps of learning control is being executed to “1” (step S07). Thus, in the EGR device, the stepping motor 502A drives the poppet valve 502C according to the new target step number ESTPTG. As a result, the opening degree of the EGR valve 502 increases and the exhaust gas recirculation amount increases.

  Then, engine ECU 1000 returns to step S01 again to determine whether knock determination flag FKNOCK is “1” or not. When knocking determination flag FKNOCK is “1” (YES in step S01), engine ECU 1000 still has knocking eliminated because there is a deviation between the new target step number ESTPTG and the actual step number. Judge that it is not. Then, the target step number ESTPTG is further increased by a predetermined step number ΔESTP by performing the processes of steps S02 to S07 again.

  In this way, when the knock determination flag FKNOCK is “1”, engine ECU 1000 executes EGR control while increasing target step number ESTPTG by a predetermined step number ΔESTP. When knocking determination flag FKNOCK is cleared to “0” during execution of EGR control (in the case of NO in step S01), that is, when knocking is eliminated, engine ECU 1000 determines in step S08. After confirming that the learning control flag FEGRRE is “1”, it is determined that the target step number ESTPTG matches the actual step number. Then, the target step number ESTPTG is corrected to the actual step number at this time (step S09).

  FIG. 8 is a diagram for explaining the target number of steps of the EGR valve 502 corrected by the learning control of the actual number of steps.

  Referring to FIG. 8, the EGR operation region is set to a low / medium load operation state (RGN1 in the drawing) and a high output (high load high rotation) region (RGN2 in the drawing). In these EGR operating regions, a control target value of the exhaust gas recirculation amount for effectively reducing the NOx generation amount in the operating state is calculated for each operating state (load and engine speed) of the engine 120. In addition, the target step number of the EGR valve 502 corresponding to the calculated control target value of the exhaust gas recirculation amount is set based on the relationship shown in FIG. As an example, in the operation state indicated by the cell Cell1 in the figure, the step number S1 corresponding to the calculated control target value X of the exhaust gas recirculation amount is set as the target step number based on the relationship of FIG.

  Here, it is assumed that the occurrence of knocking is detected when the engine 120 is in the operation state indicated by the cell Cell1 in the drawing. At this time, if engine ECU 1000 determines that the occurrence of knocking is due to a decrease in the flow rate of EGR valve 502 in accordance with the flowchart of FIG. 6 described above, engine ECU 1000 performs learning control of the actual opening of EGR valve 502, The actual step number S2 of the EGR valve 502 for ensuring the control target value X of the exhaust gas recirculation amount is acquired as a learning value.

  And engine ECU1000 correct | amends the target step number S1 preset in the cell Cell1 in a figure to step number S2 using this acquired learning value. At this time, engine ECU 1000 further corrects target step number S1 to step number S2 for the operating state (cell Cell2 in the figure) in which the same target step number S1 is set. That is, engine ECU 1000 reflects the actual number of steps S2 acquired as the learning value in the driving state when knocking occurs as the target number of steps in the driving state when knocking does not occur.

  In this way, the actual step number learned in the operation state in which the occurrence of knocking is detected is set to the target step number in the operation state in which the operation state is the same as the target step number and the occurrence of knocking is not detected. By also reflecting this, the deviation between the control value of the exhaust gas recirculation amount and the actual value can be canceled in the entire EGR operating region. This makes it possible to perform combustion at the stoichiometric air-fuel ratio while suppressing an increase in exhaust gas temperature during high output operation. As a result, it is possible to further improve the environmental performance and fuel consumption performance that are advantageous for the hybrid vehicle.

  In the engine system configuration shown in FIG. 2, the engine 120 corresponds to the “internal combustion engine” in the present invention, and the EGR device corresponds to the “exhaust gas recirculation device” in the present invention. Further, engine ECU 1000 implements “knocking detection means”, “reflux device abnormality detection means”, “actual opening degree learning means”, and “reflux gas control means”. Each functional block constituting these means has been described as functioning as software realized by a CPU (Central Processing Unit), which is the engine ECU 1000, executing a program stored in the storage unit. It may be realized by hardware. Such a program is recorded on a recording medium and mounted on the vehicle.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied to a control device for an internal combustion engine mounted on a hybrid vehicle.

1 is a block diagram illustrating a configuration of a hybrid vehicle on which an internal combustion engine control device according to an embodiment of the present invention is mounted. FIG. 1 is a schematic configuration diagram of an engine system controlled by an engine ECU which is a control device for an internal combustion engine according to an embodiment of the present invention. It is the figure which expanded the part of the EGR apparatus of FIG. It is the figure which expanded the part of the EGR valve | bulb of an EGR apparatus. It is a figure for demonstrating the action | operation area | region of an EGR apparatus. It is a flowchart for illustrating learning control of the actual opening of EGR valve 502 that is executed by engine ECU according to the embodiment of the present invention. It is a figure which shows the relationship between the exhaust gas recirculation amount in an EGR apparatus, and the step number of an EGR valve. It is a figure for demonstrating the target step number of the EGR valve correct | amended by learning control of the actual step number.

Explanation of symbols

  102 accelerator position sensor, 120 engine, 140 motor generator, 140A motor, 140B generator, 160 driving wheel, 180 speed reducer, 200 air cleaner, 202 air flow meter, 220 battery for traveling, 240 inverter, 242 boost converter, 260 power split mechanism, 300 throttle valve, 302 throttle position sensor, 304 throttle motor, 306 vacuum sensor, 400 fuel tank, 402 fuel pump, 406 canister purge VSV, 500 EGR pipe, 502 EGR valve, 502A stepping motor, 502B return spring, 502C poppet valve 502D Cooling water passage, 600 Air flow control valve, 602 Air flow control Lub VSV, 704 knock sensor, 710, 712 oxygen sensor, 800 high pressure fuel pump, 804 high pressure fuel injector, 806 EDU, 808 igniter integrated ignition coil, 900, 902 three-way catalytic converter, 1000 engine ECU, 1010 MG_ECU, 1020 Battery ECU, 1030 HV_ECU.

Claims (5)

A control device for an internal combustion engine in a vehicle including the internal combustion engine and another driving force source,
The internal combustion engine is provided with an exhaust gas recirculation device for recirculating a part of the exhaust gas to the intake pipe of the internal combustion engine again through a recirculation valve,
The controller is
A recirculation gas control means for setting a recirculation gas control target flow rate by the exhaust gas recirculation device according to an engine operating state and controlling the recirculation valve according to an opening command value generated based on the control target flow rate;
Knocking detection means for detecting occurrence of knocking in the internal combustion engine;
Based on the engine operating state when the occurrence of knocking is detected, the reflux device abnormality detection means for detecting the occurrence of a decrease in the flow rate of the reflux gas from the control target flow rate by the exhaust gas reflux device;
An actual opening that learns an actual opening that is an actual opening of the recirculation valve for securing the control target flow rate based on a detection signal from the knocking detection means when the flow rate drop is detected Learning means,
The recirculation gas control means is configured to use the learned actual opening degree as a value of the opening degree command value in the engine operating state when the occurrence of the knocking is detected, and the non-knocking state in which the engine operating state and the control target flow rate are the same. A control apparatus for an internal combustion engine, which reflects the opening command value in the engine operating state at the time of occurrence in the control of the recirculation valve. Ignition timing control means for calculating a retard amount with respect to the basic ignition timing according to the occurrence of knocking;
An operation region determination means for determining whether or not an engine operation state when the occurrence of knocking is detected is an operation region of the exhaust gas recirculation device;
The recirculation device abnormality detection means is an operation region of the exhaust gas recirculation device when the calculated retardation amount exceeds a predetermined threshold and when the occurrence of knocking is detected. 2. The control device for an internal combustion engine according to claim 1, wherein the flow rate drop is sometimes detected.   The actual opening degree learning means drives the reflux valve while gradually increasing the opening degree instruction value, and the opening degree instruction value when the detection signal from the knocking detection means is not input by this driving is calculated as the opening degree instruction value. The control device for an internal combustion engine according to claim 1 or 2, which is acquired as an actual opening. The exhaust gas recirculation device includes a step motor for driving the recirculation valve,
The actual opening degree learning means drives the step motor while gradually increasing the target step number, and the target opening number when the detection signal from the knocking detection means is not input by this driving is calculated as the actual opening degree. The control device for an internal combustion engine according to claim 3, which is acquired as an actual step number corresponding to.   The recirculation gas control means has in advance the opening degree command value generated based on the control target flow rate for each engine operation state, and for a plurality of engine operation states having the same control target flow rate. The control apparatus for an internal combustion engine according to claim 1, wherein the actual opening degree learned in correspondence with the control target flow rate is reflected in the control of the recirculation valve as the opening degree instruction value.

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