JP2010024901A - Controller for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of times of knocking, and to reduce the amount of degradation in engine output. <P>SOLUTION: An engine ECU carries out a program including a step (S102) of retarding ignition timing when it is determined that there is knocking (YES in S100), a step (S214) of carrying out control such that the ignition timing is retarded when carrying out change-over between a state of carrying out external EGR of recirculating exhaust gas discharged from a cylinder to an exhaust path to an intake path and a state of stopping the external EGR (YES in S200), and a step (S216) of continuing control of the ignition timing such that it is retarded when there is knocking. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an internal combustion engine control device, and more particularly to a technique for controlling ignition timing in an internal combustion engine.

  Conventionally, an internal combustion engine provided with an EGR (Engine Gas Recirculation) system is known. In the EGR system, the pumping loss and the unburned gas can be reduced by the external EGR that recirculates the exhaust gas discharged from the cylinder to the exhaust passage to the intake passage.

  The amount of exhaust gas recirculated from the exhaust passage to the intake passage by the EGR system is adjusted by an EGR valve provided on the EGR gas passage. When the EGR valve is opened, the exhaust gas is recirculated from the exhaust passage to the intake passage, and when the EGR valve is closed, the recirculation of the exhaust gas from the exhaust passage to the intake passage is stopped.

  When the state in which the exhaust gas is recirculated from the exhaust passage to the intake passage is switched to the state in which the exhaust gas is stopped, the amount of exhaust gas charged into the cylinder by the external EGR changes transiently. While the amount of exhaust gas charged into the cylinder by the external EGR is changing transiently, the combustion state in the cylinder becomes unstable and knocking may occur. Therefore, a technique has been proposed in which the ignition timing is retarded when switching between a state in which external EGR is performed and a state in which it is stopped.

  Japanese Patent Laying-Open No. 2007-23971 (Patent Document 1) learns a knock determination level based on the background noise of the knock sensor within the knock determination period, and also learns the knock determination level and the knock sensor within the knock determination period. Knocking determination that determines whether knocking (knocking) has occurred through comparison with the output signal of the engine, and corrects the ignition timing of the engine to the advance side or retard side according to the ignition timing correction amount set based on the determination result Due to the change of the fuel injection timing by executing or stopping the exhaust gas recirculation by the exhaust gas recirculation device that has a control unit and recirculates the exhaust gas to the intake passage, the generation timing of vibration noise due to the operation of the fuel injection valve is within the knock determination period When the knock determination level is learned when the engine operating state changes, the knock determination level Disclosed is an internal combustion engine ignition timing control device that prohibits knocking determination by the knocking determination control unit until learning is completed and corrects the ignition timing of the engine further to the retard side than the timing set by the knocking determination control unit. To do.

  According to the ignition timing control device described in this publication, when vibration noise is generated within a knock determination period due to execution or stop of exhaust gas recirculation by an exhaust gas recirculation device that recirculates exhaust gas into an intake passage. However, learning of the knock determination level is performed. As a result, the vibration noise is captured as background noise of the knock sensor. Therefore, the knock determination level is learned as a value in which the vibration noise is reflected, and the knock determination level is set large enough that the vibration noise is not erroneously determined as knocking. Therefore, even if the output signal of the knock sensor is accompanied by vibration noise accompanying the operation of the fuel injection valve, the vibration noise level does not exceed the knock determination level after completion of learning. Therefore, the same vibration noise is not erroneously determined as knocking, and the occurrence of erroneous retardation due to vibration noise associated with the operation of the fuel injection valve is suppressed, so that the knock determination period and the fuel injection timing are each set to the optimum time. Can be set.

  However, knocking determination is prohibited until vibration noise generated with the operation of the fuel injection valve is reflected in the knock determination level. As a result, it is possible to prevent an erroneous determination that the vibration noise is determined to be knocking, and thus to prevent such an erroneous retardation.

Furthermore, the ignition timing is retarded until learning of the knock determination level is completed. As a result, the occurrence of knocking can be suppressed until learning of the knock determination level is completed.
JP 2007-23971 A

  However, at the time of switching between the state in which the external EGR is performed and the state in which it is stopped, the mixed state of the fresh air newly sucked into the internal combustion engine and the recirculated exhaust gas is unknown. Therefore, it is difficult to accurately determine the retard amount of the ignition timing that can prevent the occurrence of knocking. For this reason, knocking may not be prevented even if the ignition timing is retarded immediately after the execution of external EGR or immediately after stopping. On the other hand, if the ignition timing is greatly retarded in order to prevent knocking, the output of the internal combustion engine can be reduced more than necessary.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to control an internal combustion engine capable of reducing the number of times that knocking occurs and reducing the amount of decrease in the output of the internal combustion engine. Is to provide.

  An internal combustion engine control apparatus according to a first aspect of the present invention is an internal combustion engine control apparatus provided with a recirculation system that recirculates exhaust gas discharged from a cylinder to an exhaust passage into an intake passage. The control device includes a recirculation control means for controlling the recirculation system so as to switch between a state in which the exhaust gas is recirculated from the exhaust passage to the intake passage and a state in which the exhaust gas is stopped. At the time of switching between a state where exhaust gas is recirculated and a state where it is stopped, a retarding means for controlling the ignition timing in the internal combustion engine to retard, and whether or not knocking has occurred, And a knock control means for controlling the ignition timing so as to delay when it occurs. The knock control means continues to control the ignition timing so as to be retarded when a knock occurs at the time of switching between a state where exhaust gas is recirculated from the exhaust passage to the intake passage and a state where it is stopped. Means for.

  According to this configuration, the ignition timing is retarded when the exhaust gas is recirculated from the exhaust passage to the intake passage and the state where the exhaust gas is stopped. Thus, the ignition timing is continuously controlled. As a result, the ignition timing is retarded regardless of whether or not knocking has occurred, and when knocking occurs, the ignition timing can be further retarded to reduce the number of times that knocking occurs. In addition, since the ignition timing is continuously controlled so as to be retarded when knocking occurs, the state where the exhaust gas is recirculated from the exhaust passage to the intake passage and the state where it is stopped are switched. Therefore, even if the ignition timing does not increase the retard amount more than necessary, the number of knocks can be reduced. Therefore, it is possible to provide a control device for an internal combustion engine that can reduce the number of occurrences of knocking and reduce the amount of decrease in the output of the internal combustion engine.

  In the control apparatus for an internal combustion engine according to the second invention, in addition to the configuration of the first invention, the knock control means retards when knocking occurs, and advances when the knock does not occur. Means for controlling the ignition timing. The control device further includes means for learning the ignition timing controlled so as to be retarded when knocking occurs and to advance when knocking does not occur. The retarding means is a learning value of the ignition timing in a state where the exhaust gas is recirculated from the exhaust passage to the intake passage, and a learned value of the ignition timing in a state where the recirculation of the exhaust gas from the exhaust passage to the intake passage is stopped. The means for controlling the ignition timing to be retarded more greatly is included as the difference between is increased.

  According to this configuration, the ignition timing is controlled so as to be retarded when knocking occurs and to advance when knocking does not occur. The ignition timing controlled to be retarded when knocking occurs and to advance when knocking does not occur is learned. There is a large difference between the learned value of the ignition timing when exhaust gas is recirculated from the exhaust passage to the intake passage and the learned value of ignition timing when exhaust gas is recirculated from the exhaust passage to the intake passage. Thus, the ignition timing is more retarded when switching between a state where exhaust gas is recirculated from the exhaust passage to the intake passage and a state where it is stopped. Thereby, the ignition timing can be retarded more greatly as the change in the combustion state in the cylinder of the internal combustion engine is larger. Therefore, the ignition timing can be retarded more greatly as the possibility of knocking increases. Therefore, the number of times that knocking occurs can be reduced.

  In the control apparatus for an internal combustion engine according to the third aspect of the invention, in addition to the configuration of the first aspect of the invention, the ignition timing is such that when the knocking occurs, the angle is retarded, and when no knocking occurs, the angle is advanced. Means for controlling. The control device includes means for learning the ignition timing controlled to retard when knocking occurs and advance when knocking does not occur, and exhaust from the exhaust passage to the intake passage. The learned value of the ignition timing in a state where the recirculation of the exhaust gas from the exhaust passage to the intake passage is stopped when the learned value of the ignition timing in the state where the gas is recirculated is later than the predetermined first ignition timing. Is controlled to delay the ignition timing when switching between a state in which the exhaust gas is recirculated from the exhaust passage to the intake passage and a state in which it is stopped when the ignition timing is later than the predetermined second ignition timing. Means for permitting and when the learning value of the ignition timing in a state where the exhaust gas is recirculated from the exhaust passage to the intake passage is earlier than the first ignition timing and when the exhaust gas is recirculated from the exhaust passage to the intake passage. Circulation In at least one of the cases where the learning value of the ignition timing in the stop state is earlier than the second ignition timing, there is a state in which the exhaust gas is recirculated from the exhaust passage to the intake passage and a state in which the stop is stopped And a means for prohibiting control to retard the ignition timing at the time of switching.

  According to this configuration, the ignition timing is controlled so as to be retarded when knocking occurs and to advance when knocking does not occur. The ignition timing controlled to be retarded when knocking occurs and to advance when knocking does not occur is learned. The learning value of the ignition timing in the state where the exhaust gas is recirculated from the exhaust passage to the intake passage is later than the predetermined first ignition timing, and the recirculation of the exhaust gas from the exhaust passage to the intake passage is stopped. If the learned value of the ignition timing in the state to be activated is later than the predetermined second ignition timing, the ignition timing is delayed when switching between the state in which the exhaust gas is recirculated from the exhaust passage to the intake passage and the state in which it is stopped. It is allowed to control to horn. Ignition when the learning value of the ignition timing in the state in which the exhaust gas is recirculated from the exhaust passage to the intake passage is earlier than the first ignition timing and in the state in which the recirculation of the exhaust gas from the exhaust passage to the intake passage is stopped In at least one of the cases where the learning value of the timing is earlier than the second ignition timing, the ignition timing is changed at the time of switching between the state where the exhaust gas is recirculated from the exhaust passage to the intake passage and the state where it is stopped. Control to retard is prohibited. As a result, when the ignition timing is greatly retarded, that is, when the number of knocks is high, when switching between a state where exhaust gas is recirculated from the exhaust passage to the intake passage and a state where it is stopped The ignition timing can be retarded, otherwise it can be prevented from retarding. Therefore, the number of times to retard the ignition timing can be minimized. Therefore, the output of the internal combustion engine can be prevented from decreasing more than necessary.

  In the control apparatus for an internal combustion engine according to the fourth aspect of the invention, in addition to the configuration of any one of the first to third aspects, the internal combustion engine has a change in opening / closing timing of at least one of the intake valve and the exhaust valve. A changing mechanism is provided. The control device further includes means for controlling the changing mechanism so that there is no period in which both the intake valve and the exhaust valve are open simultaneously. The recirculation control means is configured to stop the exhaust gas recirculation from the exhaust passage to the intake passage after the change mechanism is controlled so that there is no period in which both the intake valve and the exhaust valve are open simultaneously. Means for controlling the recirculation system to maintain for a predetermined time, and recirculation to maintain the state of stopping the exhaust gas recirculation from the exhaust passage to the intake passage for a predetermined time And means for controlling the recirculation system to be in a state of recirculation of exhaust gas from the exhaust passage to the intake passage after the system is controlled.

  According to this configuration, the opening / closing timing of at least one of the intake valve and the exhaust valve is changed by the changing mechanism. For example, when switching from internal EGR back to the cylinder for exhaust gas exhausted into the exhaust passage from the cylinder to the external EGR, it is changed so that both the intake valve and the exhaust valve are open simultaneously, that is, there is no overlap The mechanism is controlled. After the change mechanism is controlled so that there is no overlap between the intake valve and the exhaust valve, the state in which the recirculation of the exhaust gas from the exhaust passage to the intake passage is stopped is maintained for a predetermined time. After the recirculation system is controlled to maintain the state in which the recirculation of the exhaust gas from the exhaust passage to the intake passage is stopped for a predetermined time, the exhaust gas is recirculated from the exhaust passage to the intake passage. The recirculation system is controlled to be in the state. Thus, it is possible to provide a period during which neither the external EGR nor the internal EGR is performed during the transition from the state where the external EGR is stopped to the state where the external EGR is performed. Therefore, it is possible to reduce the turbulence of the airflow in the cylinder at the time of transition from the state where the external EGR is stopped to the state where the external EGR is performed. As a result, occurrence of knock can be suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  With reference to FIG. 1, an engine 100 for a vehicle equipped with a control device according to an embodiment of the present invention will be described. The engine 100 is provided with four cylinders. The number of cylinders is not limited to “4”, and may be “5”, “6”, “8”, “10”, “12”, and the like.

  The control device according to the present embodiment is realized by a program executed by an engine ECU (Electronic Control Unit) 200, for example. The program executed by engine ECU 200 may be recorded on a recording medium such as a CD (Compact Disc) or a DVD (Digital Versatile Disc) and distributed to the market.

  Engine 100 is an internal combustion engine that burns an air-fuel mixture of air sucked from air cleaner 102 and fuel injected from injector 104 by igniting with an ignition plug 106 in a combustion chamber.

  The ignition timing is set according to the operating state of engine 100. Hereinafter, the ignition timing set according to the operating state of engine 100 is also referred to as basic ignition timing. When knocking occurs, the ignition timing is retarded from the basic ignition timing.

  The basic ignition timing is set according to a map having the engine speed NE and the load KL as parameters. The load KL is calculated based on the intake air amount detected by an air flow meter 314, which will be described later, the engine speed NE, and the like. In addition, since the method of calculating load KL should just use a known general technique, those detailed description is not repeated here.

  When the air-fuel mixture burns, the piston 108 is pushed down by the combustion pressure, and the crankshaft 110 rotates. The combusted air-fuel mixture (exhaust gas) is purified by the three-way catalyst 112 and then discharged outside the vehicle. The amount of air taken into engine 100 is adjusted by throttle valve 114. When the intake valve 116 is opened, the air-fuel mixture is introduced into the combustion chamber. When the exhaust valve 118 is opened, the exhaust gas is discharged from the combustion chamber.

  The phase of intake valve 116, that is, the opening / closing timing is changed by a VVT (Variable Valve Timing) mechanism 120. In addition to the intake valve 116, the phase of the exhaust valve 118 may be changed.

  In the present embodiment, engine 100 is provided with an EGR system. The EGR system reduces pumping loss and unburned gas by external EGR that recirculates exhaust gas discharged from the cylinder to the exhaust passage 130 to the intake passage 132.

  The amount of exhaust gas recirculated from the exhaust passage 130 to the intake passage 132 by the EGR system is adjusted by an EGR valve 136 provided on the EGR gas passage 134. When the EGR valve 136 is opened, the exhaust gas is recirculated from the exhaust passage 130 to the intake passage 132. When the EGR valve 136 is closed, the exhaust gas recirculation from the exhaust passage 130 to the intake passage 132 is stopped.

  Engine 100 is controlled by engine ECU 200. The engine ECU 200 includes a knock sensor 300, a water temperature sensor 302, a crank position sensor 306 provided facing the timing rotor 304, a throttle opening sensor 308, a vehicle speed sensor 310, an ignition switch 312, and an air flow meter. 314 is connected.

  Knock sensor 300 is provided in a cylinder block of engine 100. Knock sensor 300 is composed of a piezoelectric element. Knock sensor 300 generates a voltage due to vibration of engine 100. The magnitude of the voltage corresponds to the magnitude of the vibration. Knock sensor 300 transmits a signal representing a voltage to engine ECU 200.

  In the present embodiment, engine ECU 200 determines whether or not knock has occurred based on a signal transmitted from knock sensor 300, and retards the ignition timing if it is determined that knock has occurred. A knock control system for advancing the ignition timing when it is determined that no knock has occurred is implemented.

  For example, when the magnitude of vibration detected by knock sensor 300 is greater than a threshold value, it is determined that knock has occurred. It should be noted that a known general technique may be used as a method for determining whether or not knocking has occurred, and therefore detailed description thereof will not be repeated here.

  Water temperature sensor 302 detects the temperature (water temperature) of the cooling water in the water jacket of engine 100 and transmits a signal representing the detection result to engine ECU 200.

  The timing rotor 304 is provided on the crankshaft 110 and rotates together with the crankshaft 110. A plurality of protrusions are provided on the outer periphery of the timing rotor 304 at predetermined intervals. The crank position sensor 306 is provided to face the protrusion of the timing rotor 304. When the timing rotor 304 rotates, the air gap between the projection of the timing rotor 304 and the crank position sensor 306 changes, so that the magnetic flux passing through the coil portion of the crank position sensor 306 increases and decreases, and an electromotive force is generated in the coil portion. . Crank position sensor 306 transmits a signal representing the electromotive force to engine ECU 200. Based on the signal transmitted from crank position sensor 306, engine ECU 200 detects the crank angle and the rotational speed of crankshaft 110 (engine rotational speed NE).

Throttle opening sensor 308 detects the throttle opening and transmits a signal representing the detection result to engine ECU 200. Vehicle speed sensor 310 detects the number of rotations of a wheel (not shown) and transmits a signal representing the detection result to engine ECU 200. Engine ECU 200 calculates the vehicle speed from the rotational speed of the wheel. Ignition switch 312 is turned on by the driver when engine 100 is started.

  Air flow meter 314 detects the amount of air taken into engine 100 and transmits a signal representing the detection result to engine ECU 200. In the present embodiment, the air flow meter 314 is a hot wire type air flow meter with a built-in intake air temperature sensor. Therefore, air flow meter 314 detects the temperature of the air taken into engine 100 (intake air temperature) and the amount of air taken into engine 100. The intake air temperature sensor may be provided separately from the air flow meter 314.

  Engine ECU 200 is operated by electric power supplied from auxiliary battery 320 as a power source. The engine ECU 200 performs arithmetic processing based on signals transmitted from the sensors and the ignition switch 312, a map and a program stored in a ROM (Read Only Memory) 202, so that the engine 100 enters a desired operating state. Control equipment.

  The function of engine ECU 200 will be described with reference to FIG. Note that the functions described below may be realized by software or hardware.

  Engine ECU 200 includes a VVT control unit 500, an EGR control unit 502, a retardation unit 504, a knock control unit 510, a learning unit 512, a permission unit 520, and a prohibition unit 522.

  VVT control unit 500 controls VVT mechanism 120. For example, VVT mechanism 120 is controlled so that the phase of intake valve 116 becomes a phase determined according to a map having engine speed NE and load KL as parameters.

  In addition, when the operating state of engine 100 (engine speed NE and load KL) is in the region indicated by hatching in the map shown in FIG. 3, the period during which both intake valve 116 and exhaust valve 118 are open simultaneously, That is, the VVT mechanism 120 is controlled so that there is no overlap between the intake valve 116 and the exhaust valve 118.

  In FIG. 3, the hatched area indicates an area where external EGR is performed by the EGR system. Therefore, when the operating state of the engine 100 is outside the region indicated by the oblique lines in FIG. Internal EGR is performed in which the exhaust gas discharged to the cylinder is sucked back into the cylinder. Note that the control method of the VVT mechanism 120 is not limited to these.

  The EGR control unit 502 controls the EGR valve 136 so as to switch between an external EGR state in which exhaust gas exhausted from the cylinder into the exhaust passage 130 is recirculated to the intake passage 132 and a stop state.

  When the operating state of the engine 100 is in a region indicated by hatching in the map shown in FIG. 3, the EGR valve 136 is controlled to open and external EGR is executed. When the operating state of the engine 100 is outside the region indicated by the oblique lines in FIG. 3, the EGR valve 136 is controlled to close and the external EGR is stopped.

  When switching from the internal EGR to the external EGR, as shown in FIG. 4, after the VVT mechanism 120 is controlled so that there is no overlap between the intake valve 116 and the exhaust valve 118 at time T1, that is, recirculation is performed by the internal EGR. The EGR valve is controlled so that the amount of exhaust gas that is recirculated (hereinafter, the amount of exhaust gas that is recirculated is also referred to as EGR amount) becomes zero, and then the amount of EGR by external EGR gradually increases. 136 is controlled.

  As shown in FIG. 5, when switching from the internal EGR to the external EGR, after the VVT mechanism 120 is controlled so that there is no overlap between the intake valve 116 and the exhaust valve 118 at time T2, a predetermined value is set. The EGR valve 136 may be controlled such that the state in which the external EGR is stopped for the time ΔT is maintained, and then the EGR amount by the external EGR gradually increases from the time T3.

  Thus, it is possible to provide a period during which neither the external EGR nor the internal EGR is performed during the transition from the state where the external EGR is stopped to the state where the external EGR is performed. Therefore, it is possible to reduce the turbulence of the airflow in the cylinder at the time of transition from the state where the external EGR is stopped to the state where the external EGR is performed. As a result, occurrence of knock can be suppressed.

  Returning to FIG. 2, the retarding portion 504 ignites the ignition timing so as to retard the ignition timing when the exhaust gas is recirculated from the exhaust passage 130 to the intake passage 132, that is, when switching between the state in which the external EGR is executed and the stop. The plug 106 is controlled. As shown in FIG. 6, after the ignition timing is retarded by a predetermined value at time T4, the retard amount is reduced at a predetermined rate of change.

  As shown in FIG. 7, after the VVT mechanism 120 is controlled so that there is no overlap between the intake valve 116 and the exhaust valve 118 at time T5, the external EGR is stopped for a predetermined time ΔT. When maintaining, the ignition timing may be retarded at time T5 when the overlap between the intake valve 116 and the exhaust valve 118 is eliminated. Further, as shown in FIG. 8, the ignition timing may be retarded at time T6 when the EGR amount by the external EGR increases after ΔT has elapsed from time T5.

  The retard portion 504 controls the spark plug 106 so as to retard the ignition timing by a retard amount corresponding to a learned value of the ignition timing described later. As the difference between the learned value of the ignition timing in the state where the external EGR is executed and the learned value of the ignition timing in the state where the external EGR is stopped is larger, the ignition timing is more retarded.

  In addition to the difference between the learned value of the ignition timing in the state where the external EGR is executed and the learned value of the ignition timing in the state where the external EGR is stopped, the learned value of the ignition timing or the external EGR in the state where the external EGR is executed is stopped. The retard amount may be determined according to the learning value itself of the ignition timing in the state to be performed. The ignition timing retarding method is not limited to these.

  Returning to FIG. 2, knock control unit 510 determines whether or not a knock has occurred based on a signal transmitted from knock sensor 300, and retards the ignition timing if it is determined that a knock has occurred. When it is determined that no knock has occurred, the spark plug 106 is controlled to advance the ignition timing.

  More specifically, the ignition timing is retarded or advanced by increasing or decreasing the retardation amount (correction amount) acs for the basic ignition timing depending on whether or not knocking has occurred. The retardation amount akcs with respect to the basic ignition timing is increased by a predetermined value every time it is determined that knocking has occurred, and is decreased by a predetermined value every time it is determined that knocking has not occurred. .

  It should be noted that a known general technique may be used as a method for calculating the retardation amount akcs with respect to the basic ignition timing in the knock control system, and therefore detailed description thereof will not be repeated here.

  In the present embodiment, when exhaust gas is recirculated from the exhaust passage 130 to the intake passage 132, that is, when switching between a state in which external EGR is executed and a state in which it is stopped, a delay is determined when it is determined that knocking has occurred. Thus, the ignition timing is continuously controlled.

  If it is determined that knock has not occurred, the control of the ignition timing so as to advance may be stopped or continued. When it is determined that knocking has not occurred, the ignition timing is controlled to advance only for a predetermined time, for example, in order to stop controlling the ignition timing to advance. That will be stopped.

  The learning unit 512 retards the ignition timing when it is determined that knocking has occurred, and the ignition timing controlled to advance the ignition timing when it is determined that knocking has not occurred. learn. That is, the ignition timing controlled by the knock control system is learned.

  For example, the ignition timing is learned by learning the retardation amount akcs with respect to the basic ignition timing. As shown in FIG. 9, when the retard amount akcs is equal to or greater than the threshold value acsc1 or less than the threshold value acsc2, the learning value akg of the retard amount acs is updated.

  When the retard amount akcs is greater than or equal to the threshold value acsc1, the learned value akg is increased by the absolute value of the threshold value acsc1, and when the retard amount acs is less than or equal to the threshold value acsc2, the learned value akg is Decrease by the absolute value of the threshold value akks2.

  For example, if the sum of the retard amount akcs and the learned value akg is positive, a value obtained by retarding the basic ignition timing by the absolute value of the sum of the retard amount akcs and the learned value akg is controlled by the knock control system. Ignition timing. When the sum of the retard amount akcs and the learned value akg is negative, the value obtained by advancing the basic ignition timing by the absolute value of the sum of the retard amount akcs and the learned value akg is controlled by the knock control system. Ignition timing.

  When the learning value akg is positive, a value obtained by delaying the basic ignition timing by the absolute value of the learning value akg is the learning value of the ignition timing controlled by the knock control system. When the learned value akg is negative, a value obtained by advancing the basic ignition timing by the absolute value of the learned value akg is the learned value of the ignition timing controlled by the knock control system.

  The ignition timing is learned in each of a state where the external EGR is executed and a state where the external EGR is stopped.

  Note that the ignition timing learning method is not limited to these. In addition, as a method of learning the ignition timing in the knock control system, a known general technique may be used, and thus detailed description thereof will not be repeated here.

  The permission unit 520 has a learning value of the ignition timing in a state where exhaust gas recirculation from the exhaust passage 130 to the intake passage 132, that is, external EGR is executed, is later than the predetermined first ignition timing, and the external EGR. When the learning value of the ignition timing in the state where the engine is stopped is later than the predetermined second ignition timing and the intake air temperature is equal to or higher than the predetermined temperature, switching between the state where the external EGR is executed and the state where the external EGR is stopped Allow control to retard the ignition timing at times. Note that the intake air temperature may not be taken into consideration.

  The prohibition unit 522 recirculates the exhaust gas from the exhaust passage 130 to the intake passage 132, that is, if the learning value of the ignition timing in a state where the external EGR is executed is earlier than the predetermined first ignition timing, A state in which external EGR is executed when the learning value of the ignition timing in the stopped state is earlier than the predetermined second ignition timing or when the intake air temperature is lower than the predetermined temperature And prohibiting the ignition timing from being retarded at the time of switching between the state and the stop state. Note that the intake air temperature may not be taken into consideration.

  With reference to FIG. 10, a control structure of a program executed by engine ECU 200 will be described.

  In step (hereinafter step is abbreviated as S) 100, engine ECU 200 determines whether or not a knock has occurred. If it is determined that knocking has occurred (YES in S100), the process proceeds to S102. If not (NO in S100), the process proceeds to S104.

  In S102, engine ECU 200 retards the ignition timing. In S104, engine ECU 200 advances the ignition timing.

  In S106, engine ECU 200 is controlled to retard the ignition timing when it is determined that knocking has occurred, and to advance the ignition timing when it is determined that knocking has not occurred. Learn ignition timing.

  In S200, engine ECU 200 determines whether to switch between a state in which external EGR is executed and a state in which it is stopped. When switching between the state of executing external EGR and the state of stopping (YES in S200), the process proceeds to S202. If not (NO in S204), the process returns to S100.

  In S202, engine ECU 200 determines whether or not to switch from internal EGR to external EGR. That is, it is determined whether to switch from the state in which the external EGR is stopped to the state in which it is executed. When switching from internal EGR to external EGR (YES in S202), the process proceeds to S204. If not (NO in S202), the process proceeds to S208.

  In S204, engine ECU 200 controls VVT mechanism 120 so that both intake valve 116 and exhaust valve 118 are open simultaneously, that is, there is no overlap between intake valve 116 and exhaust valve 118.

  In S206, engine ECU 200 executes external EGR. That is, the EGR valve 136 is controlled to open.

  In S208, engine ECU 200 stops the external EGR. That is, control is performed so that the EGR valve 136 is closed.

  In S210, engine ECU 200 has a learning value for ignition timing in a state in which external EGR is executed later than a predetermined first ignition timing, and a learning value for ignition timing in a state in which external EGR is stopped is predetermined. It is determined whether the intake temperature is later than the second ignition timing and the intake temperature is equal to or higher than a predetermined temperature.

  The learned value of the ignition timing in the state where the external EGR is executed is later than the predetermined first ignition timing, and the learned value of the ignition timing in the state where the external EGR is stopped is greater than the predetermined second ignition timing. If it is late and the intake air temperature is equal to or higher than a predetermined temperature (YES in S210), the process proceeds to S212. If not (NO in S210), the process proceeds to S218.

  In S212, engine ECU 200 permits control to retard the ignition timing when switching between a state in which external EGR is executed and a state in which it is stopped. In S214, engine ECU 200 controls to retard the ignition timing.

  In S216, engine ECU 200 continues to control the ignition timing so as to retard when knocking occurs.

  In S218, engine ECU 200 prohibits control to retard the ignition timing when switching between a state in which external EGR is executed and a state in which it is stopped.

  An operation of the control device according to the present embodiment based on the above-described structure and flowchart will be described.

  It is determined whether knock has occurred during operation of engine 100 (S100). If it is determined that knock has occurred (YES in S100), the ignition timing is retarded (S102). Thereby, the frequency | count that a knock generate | occur | produces can be reduced. If it is determined that knock has not occurred (NO in S100), the ignition timing is advanced (S104). Thereby, the output of engine 100 can be improved.

  Thereafter, when it is determined that knocking has occurred, the ignition timing is retarded, and when it is determined that knocking has not occurred, the ignition timing controlled to advance the ignition timing is learned. (S106).

  When switching between the state in which external EGR is executed and the state in which it is stopped (YES in S200), it is determined whether to switch from internal EGR to external EGR (S202).

  When switching from internal EGR to external EGR (YES in S202), the VVT mechanism is such that both intake valve 116 and exhaust valve 118 are open simultaneously, that is, there is no overlap between intake valve 116 and exhaust valve 118. 120 is controlled (S204). Thereafter, external EGR is executed (S206).

  When switching from external EGR to internal EGR (NO in S202), external EGR is stopped (S208).

  The learning value of the ignition timing in the state where the external EGR is executed is later than the predetermined first ignition timing, and the learning value of the ignition timing in the state where the external EGR is stopped is later than the predetermined second ignition timing, If the intake air temperature is equal to or higher than a predetermined temperature (YES in S210), it is permitted to control the ignition timing to be retarded when switching between the state in which the external EGR is executed and the state in which it is stopped ( S212).

  Therefore, the ignition timing is controlled to be retarded (S214). Further, when the knock occurs, the ignition timing is continuously controlled so as to be retarded (S216).

  As a result, the ignition timing is retarded regardless of whether or not knocking has occurred, and when knocking occurs, the ignition timing can be further retarded to reduce the number of times that knocking occurs. In addition, since the ignition timing is continuously controlled to be retarded when knocking occurs, the ignition timing needs to be retarded when switching between the state in which the external EGR is executed and the state in which it is stopped. Even if it is not made larger than this, the number of times that knocking occurs can be reduced. Therefore, it is possible to reduce the number of occurrences of knocking and reduce the amount of decrease in the output of the internal combustion engine.

  Further, as described above, the ignition timing is delayed more as the difference between the learned value of the ignition timing in the state in which the external EGR is executed and the learned value of the ignition timing in the state in which the external EGR is stopped is larger. Thus, the ignition timing can be retarded more greatly as the change in the combustion state in the cylinder of engine 100 is larger. Therefore, the ignition timing can be retarded more greatly as the possibility of knocking increases. As a result, the number of occurrences of knocking can be reduced.

  On the other hand, when the learning value of the ignition timing in the state where the external EGR is executed is earlier than the predetermined first ignition timing, the learning value of the ignition timing in the state where the external EGR is stopped is greater than the predetermined second ignition timing. If it is earlier or if the intake air temperature is lower than a predetermined temperature (NO in S210), the ignition timing is retarded when switching between the state in which the external EGR is executed and the state in which it is stopped. It is prohibited to perform control so as to be performed (S218).

  As a result, when the ignition timing is greatly retarded, that is, when the number of occurrences of knocking is high, the ignition timing is retarded at the time of switching between the state in which the external EGR is executed and the state in which it is stopped. If you can not retard. Therefore, the number of times to retard the ignition timing can be minimized. Therefore, the output of the internal combustion engine can be prevented from decreasing more than necessary.

  As described above, according to the control device according to the present embodiment, when switching is performed between the state in which the external EGR is executed and the state in which the external EGR is stopped, the ignition timing is controlled to be retarded and a knock occurs. In this case, the ignition timing is continuously controlled so as to be retarded. As a result, the ignition timing is retarded regardless of whether or not knocking has occurred, and when knocking occurs, the ignition timing can be further retarded to reduce the number of times that knocking occurs. In addition, since the ignition timing is continuously controlled to be retarded when knocking occurs, the ignition timing needs to be retarded when switching between the state in which the external EGR is executed and the state in which it is stopped. Even if it is not made larger than this, the number of times that knocking occurs can be reduced. Therefore, it is possible to reduce the number of occurrences of knocking and reduce the amount of decrease in the output of the internal combustion engine.

  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.

It is a schematic block diagram which shows an engine. It is a functional block diagram of engine ECU. It is a figure which shows the driving | running | working area | region where external EGR is performed. FIG. 3 is a diagram (part 1) showing an EGR amount by internal EGR and an EGR amount by external EGR. FIG. 2 is a diagram (part 2) showing an EGR amount by internal EGR and an EGR amount by external EGR. FIG. 6 is a diagram (part 1) illustrating a timing at which the ignition timing is retarded. FIG. 6 is a diagram (part 2) illustrating a timing at which the ignition timing is retarded. FIG. 6 is a diagram (part 3) illustrating timing at which the ignition timing is retarded; It is a figure which shows threshold value akcs1 and threshold value akcs2 used in order to calculate learning value akg of retard amount akcs of ignition timing. It is a figure which shows the control structure of the program which engine ECU performs.

Explanation of symbols

  100 Engine, 104 Injector, 106 Spark plug, 110 Crankshaft, 112 Three-way catalyst, 114 Throttle valve, 116 Intake valve, 118 Exhaust valve, 120 VVT mechanism, 130 Exhaust passage, 132 Intake passage, 134 EGR gas passage, 136 EGR Valve, 200 Engine ECU, 202 ROM, 300 Knock sensor, 302 Water temperature sensor, 304 Timing rotor, 306 Crank position sensor, 308 Throttle opening sensor, 310 Vehicle speed sensor, 312 Ignition switch, 314 Air flow meter, 320 Auxiliary battery, 500 VVT control unit, 502 EGR control unit, 504 retard angle unit, 510 knock control unit, 512 learning unit, 520 permission unit, 522 prohibition unit.

Claims (4)

A control device for an internal combustion engine provided with a recirculation system for recirculating exhaust gas discharged from a cylinder to an exhaust passage to an intake passage,
Recirculation control means for controlling the recirculation system to switch between a state in which exhaust gas is recirculated from the exhaust passage to the intake passage and a state in which it is stopped;
Retarding means for controlling the ignition timing in the internal combustion engine to be retarded when switching between a state in which exhaust gas is recirculated from the exhaust passage to the intake passage and a state in which it is stopped;
A knock control means for determining whether or not knocking has occurred, and for controlling the ignition timing so as to retard when knocking occurs,
The knock control means controls an ignition timing so as to delay when a knock occurs when switching between a state in which exhaust gas is recirculated from the exhaust passage to the intake passage and a state in which the exhaust gas is stopped. A control apparatus for an internal combustion engine, including means for continuing the operation. The knock control means includes means for controlling the ignition timing so as to retard when knocking occurs and advance when knocking does not occur,
Means for learning the ignition timing controlled to retard when knocking occurs and advance when knocking does not occur;
The retarding means is a learning value of the ignition timing in a state where exhaust gas is recirculated from the exhaust passage to the intake passage, and in a state where exhaust gas recirculation from the exhaust passage to the intake passage is stopped. The control apparatus for an internal combustion engine according to claim 1, further comprising means for controlling the ignition timing to be delayed more greatly as the difference between the ignition timing and the learned value is larger. The knock control means includes means for controlling the ignition timing so as to retard when knocking occurs and advance when knocking does not occur,
Means for learning ignition timing controlled to retard when knocking occurs and advance when knocking does not occur;
The learning value of the ignition timing in a state in which the exhaust gas is recirculated from the exhaust passage to the intake passage is later than a predetermined first ignition timing, and the exhaust gas from the exhaust passage to the intake passage is When the learning value of the ignition timing in the state where the recirculation is stopped is later than the predetermined second ignition timing, the state where the exhaust gas is recirculated from the exhaust passage to the intake passage and the state where it stops Means for permitting control to retard the ignition timing at the time of switching;
When the learning value of the ignition timing in the state where the exhaust gas is recirculated from the exhaust passage to the intake passage is earlier than the first ignition timing, and when the exhaust gas is recirculated from the exhaust passage to the intake passage. When the learning value of the ignition timing in the stop state is at least one of the cases where the learning value of the ignition timing is earlier than the second ignition timing, the stop is performed when the exhaust gas is recirculated from the exhaust passage to the intake passage. 2. The control device for an internal combustion engine according to claim 1, further comprising means for prohibiting control to retard the ignition timing when switching to a state. The internal combustion engine is provided with a change mechanism that changes the opening / closing timing of at least one of an intake valve and an exhaust valve,
Means for controlling the changing mechanism such that there is no period in which both the intake valve and the exhaust valve are open at the same time;
The recirculation control means includes
A state in which recirculation of exhaust gas from the exhaust passage to the intake passage is stopped after the change mechanism is controlled so that there is no period in which both the intake valve and the exhaust valve are simultaneously open is determined. Means for controlling the recirculation system to maintain for a given time;
After the recirculation system is controlled to maintain the state in which the recirculation of exhaust gas from the exhaust passage to the intake passage is stopped for the predetermined time, the exhaust from the exhaust passage to the intake passage is performed. The control device for an internal combustion engine according to any one of claims 1 to 3, further comprising means for controlling the recirculation system so as to be in a state of performing gas recirculation.

Images