JP2007186998A - Control method and control device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method for an engine preventing malfunction of a gas flow control valve due to adhesion and pile of deposit. <P>SOLUTION: In the control method for the engine provided with an EGR device 26 and the gas flow control valve, including a process procedure controlling the EGR device 26 to introduce EGR gas of predetermined EGR rate in an EGR region, and a process procedure operating the gas flow control valve to a close condition when serge is made worse during introduction of EGR gas, an intake valve close timing variable mechanism 29 is provided, and a control means 31 includes a process procedure judging whether the engine is under an operation condition where EGR gas and adhesive component easily adhere or deposit on the gas flow control valve due to blowing back of air fuel mixture containing EGR gas in a combustion chamber to neighborhood of the gas flow control valve, and a process procedure advancing intake valve closing timing to a position where blowing back is weakened by using the intake valve close timing variable mechanism 29 when it is judged that the engine is under the operation condition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an engine (internal combustion engine) control method and control device, particularly an EGR device that introduces a part of exhaust gas as EGR gas downstream of an intake throttle valve, and an operating state in the combustion chamber in the vicinity of the intake valve. It is related with what is provided with the gas flow control valve which produces a gas flow.

An engine control device that includes an EGR device and a gas flow control valve and that closes the gas flow control valve when a surge worsens during the introduction of EGR gas, and detects the closed operation state of the gas flow control valve A detection means is provided, and it is determined that a failure has occurred in which the gas flow control valve cannot be closed when there is a difference between the set closed operation state of the gas flow control valve and the actual closed operation state detected by the detection means. Thus, there is one that reduces the EGR rate and suppresses the deterioration of the surge caused by the failure of the gas flow control valve (see Patent Document 1).
JP-A-6-173780

  By the way, when the gas flow control valve is positioned in the vicinity of the intake valve, the air-fuel mixture containing EGR gas in the combustion chamber is brought into contact with the intake valve and the port wall that are opened as the piston rises. It blows back to the vicinity of the gas flow control valve through the gap, and adhesion components such as fuel and blow-by gas existing in the EGR gas and the intake port are heated by the blown EGR gas, and are deposited and deposited as deposits on the gas flow control valve. Then, due to the deposit / deposition of the deposit, the gas flow control valve is stuck in an open state or a closed state, and a failure may occur in which the gas flow control valve malfunctions. Here, the adhesive component is unburned HC, that is, gasoline particles remaining in the intake port without burning.

  In this case, if the malfunction of the gas flow control valve is detected by applying the technique disclosed in Patent Document 1, a detection means (switch or sensor) for detecting the malfunction is necessary, which is expensive.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an engine control method and a control apparatus that prevent a gas flow control valve from malfunctioning due to adhesion / deposition of an adhesive component as a deposit.

  The present invention includes an EGR device that introduces part of the exhaust gas as EGR gas downstream of the intake throttle valve, and a gas flow control valve that is in the vicinity of the intake valve and that generates a gas flow in the combustion chamber in an operating state. When entering the EGR region, the EGR device is controlled so that EGR gas of a predetermined EGR rate is introduced, and when the surge worsens during the introduction of EGR gas, the gas flow control valve is closed. An intake valve closing timing variable mechanism capable of variably controlling the closing timing of the intake valve is provided, and the EGR gas and the adhesive component are converted into the gas flow control valve by blowing back an air-fuel mixture containing EGR gas in the vicinity of the gas flow control valve. It is determined whether or not the operating conditions are likely to deposit and accumulate on the gas flow control valve as deposits, and when it is determined that the operating conditions are satisfied, the intake valve closing timing variable mechanism is used to Teeth configured to advancing the intake valve closing timing to weaken position.

  The present invention also includes an EGR device that introduces part of the exhaust gas as EGR gas downstream of the intake throttle valve, and a gas flow control valve that is in the vicinity of the intake valve and generates a gas flow in the combustion chamber in an operating state. In the EGR region, the EGR device is controlled so that an EGR gas having a predetermined EGR rate is introduced, and the gas flow control valve is closed when a surge worsens during the introduction of the EGR gas. On the other hand, when the EGR gas and the adhesive component adhere and accumulate on the gas flow control valve as deposits due to the backflow of the air-fuel mixture containing EGR gas in the combustion chamber to the vicinity of the gas flow control valve, The atmosphere temperature of the gas flow control valve is increased until the fixing torque becomes less than the driving torque of the gas flow control valve actuator.

  According to the present invention, there is provided an EGR device that introduces a part of exhaust gas as EGR gas downstream of the intake throttle valve, and a gas flow control valve that is in the vicinity of the intake valve and generates a gas flow in the combustion chamber in an operating state. In the EGR region, the EGR device is controlled so that an EGR gas having a predetermined EGR rate is introduced, and the gas flow control valve is closed when a surge worsens during the introduction of the EGR gas. On the other hand, an intake valve closing timing variable mechanism capable of variably controlling the closing timing of the intake valve is provided, and an EGR gas and an adhesive component are obtained by blowing back an air-fuel mixture containing EGR gas in the combustion chamber to the vicinity of the gas flow control valve. Is determined as to whether or not it is an operating condition that is likely to adhere and deposit as a deposit on the gas flow control valve. Blowback advancing the intake valve closing timing to weaken position. Thereby, since the blowback of the air-fuel mixture containing the EGR gas can be suppressed, it is possible to prevent malfunctions such as adhesion of the gas flow control valve due to deposit adhesion / deposition. If malfunction of the gas flow control valve due to deposit adhesion / deposition can be prevented in advance, EGR with a predetermined EGR rate can be obtained without having a detection means for detecting whether or not the gas flow control valve has malfunctioned. The EGR rate control that allows the gas to be introduced can be continuously executed. Further, the diagnosis system and detection means for the gas flow control valve itself are not required, and the cost can be reduced.

  Further, according to the present invention, an EGR device that introduces a part of the exhaust gas as EGR gas downstream of the intake throttle valve, and a gas flow control valve that is in the vicinity of the intake valve and generates a gas flow in the combustion chamber in an operating state. When the EGR region is reached, the EGR device is controlled so that an EGR gas having a predetermined EGR rate is introduced, and the gas flow control valve is closed when a surge worsens during the introduction of the EGR gas. On the other hand, when the gas mixture containing EGR gas in the combustion chamber is blown back to the vicinity of the gas flow control valve, the EGR gas and the adhesive component are deposited and deposited on the gas flow control valve as deposits. Since the atmosphere temperature of the gas flow control valve is raised until the adhesion torque of the deposit becomes less than the driving torque of the actuator for the gas flow control valve, the deposit adhesion Even if malfunction such as stuck open or closed sticking occurs in the gas flow control valve by the product, it is possible to operate the gas flow control valve.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of an engine control apparatus used directly in the engine control method. Here, the engine is an L-Jetronic gasoline injection engine.

  The air metered by the intake throttle valve 23 is stored in the intake collector 2 and then introduced into the combustion chamber 5 of each cylinder via the intake manifold 3. The engine speed is calculated based on the intake air flow rate detected by the air flow meter 32 and the signal from the crank angle sensor (33, 34) from the fuel injection valve 21 arranged in the intake port 4 of each cylinder. Accordingly, the injection is intermittently supplied into the intake port at a predetermined timing.

  The fuel injected toward the intake valve 15 is mixed with the intake air to form an air-fuel mixture. The air-fuel mixture is confined in the combustion chamber 5 by closing the intake valve 15, compressed by the rise of the piston 6, and ignited. It is ignited by the plug 14 and burns. The gas pressure due to the combustion works to push down the piston 6, and the reciprocating motion of the piston 6 is converted into the rotational motion of the crankshaft 7. The combusted gas (exhaust gas) is discharged into the exhaust passage 8 when the exhaust valve 16 is opened.

A three-way catalyst 9 is provided in the exhaust passage 8. The three-way catalyst 9 can efficiently remove HC, CO and NOx contained in the exhaust gas simultaneously when the air-fuel ratio of the exhaust gas is in a narrow range centered on the stoichiometric air-fuel ratio. For this reason, the engine controller 31 determines the basic fuel injection pulse width Tp from the fuel injection valve 21 according to the operating conditions (determined from the intake air amount and the rotational speed Ne), and O ₂ provided upstream of the three-way catalyst 9. This basic fuel injection pulse width Tp is feedback-controlled based on a signal from a sensor (not shown).

  The intake throttle valve 23 is driven by a throttle motor 24. Since the torque required by the driver appears in the amount of depression of the accelerator pedal 41 (accelerator opening), the engine controller 31 determines a target torque based on a signal from the accelerator sensor 42, and a target air for realizing this target torque. The amount is determined, and the opening degree of the intake throttle valve 23 is controlled via the throttle motor 24 so that this target air amount is obtained.

  EGR device is provided mainly to improve fuel economy. The EGR device adjusts the amount (or rate) of an EGR passage 25 that communicates the exhaust passage 8 and the intake manifold 3 and a part of exhaust (that is, EGR gas) that flows to the intake manifold 3 through the EGR passage 25. When the EGR gas is introduced into the intake manifold 3, the pumping loss is reduced and the fuel efficiency is improved. The method for driving the EGR valve 26 is not limited to this. For example, it may be driven by a motor other than the step motor, or may be driven by a hydraulic actuator.

  Here, the EGR rate is a value obtained by multiplying the value obtained by dividing the amount of EGR gas introduced into the combustion chamber 5 per cycle by the amount of fresh air introduced into the combustion chamber 5 per cycle (%). ). The basic value Regr0 [%] of the EGR rate is divided into four regions R1 to R4 in the operation region in which the engine speed Ne and the engine load (for example, the basic fuel injection pulse width Tp) are parameters as shown in FIG. Is the largest in the region R1 on the lowest load / low rotational speed side, the largest in the region R2 / R3 on the high load / high rotational speed side, and zero in the region R4 on the highest load / high rotational speed side. The value is [%].

  As described above, the basic value of the EGR rate is increased toward the low load low rotation speed side because the intake throttle valve 23 is closed and the pumping loss increases as the low load low rotation speed side increases. This is because the EGR rate is increased and a large amount of EGR gas is introduced downstream of the intake throttle valve 23 to reduce the pumping loss.

  The engine controller 31 (control means) obtains the optimum EGR rate basic value Regr0 shown in FIG. 2 from the operating conditions determined by the engine load and the rotational speed, and multiplies this by the intake air flow rate detected by the air flow meter 32. The EGR gas flow rate is calculated, the EGR valve opening area through which the EGR gas flow rate flows is calculated, the number of steps from which the EGR valve opening area is obtained is calculated, and the number of steps is output to the step motor 27. The larger the EGR rate basic value Regr0, the larger the number of steps. The larger the number of steps, the larger the EGR valve 26 is opened, and a larger amount of EGR gas is introduced into the intake manifold 3.

  When the ERG rate basic value Regr0 is increased on the low load and low rotation speed side, the pumping loss is reduced, but on the other hand, the introduction of a large amount of EGR gas makes the combustion in the combustion chamber 5 unstable and causes fluctuations in combustion. Go to the direction of worsening the surge. In order to suppress this deterioration of surge, the combustion state is improved by giving a gas flow to the air-fuel mixture containing EGR gas in the combustion chamber 5. Therefore, a swirl control valve 18 is provided in the intake manifold 3 near the intake valve 15. For example, as shown in FIG. 3, a so-called independent dual port is formed which branches into two independent ports 4a and 4b in the vicinity of the combustion chamber 5 and opens into the combustion chamber 5, and an intake valve 15a is formed in each of the two openings. , 15b. One of the independent ports 4a is provided with a swirl control valve 18 for opening and closing the independent port 4a, and the swirl control valve 18 is driven to open and close by a step motor 19 (actuator for gas flow control valve). The method for driving the swirl control valve 18 is not limited to this. For example, it may be driven by a motor other than the step motor, or may be driven by a hydraulic actuator.

  For example, as shown in FIG. 4, a surge deterioration region (an operation region in which the surge is easily deteriorated) is determined in advance (see the vertical hatched portion). The motor 19 is driven and the swirl control valve 18 is closed. At this time, almost no air-fuel mixture containing EGR gas is introduced from the independent port 4a on the side where the swirl control valve 18 is present, whereas almost all air-fuel mixture containing EGR gas is supplied from the independent port 4b on the other side. As a result, a gas flow (that is, a swirl) flows around the cylinder axis in the combustion chamber 5. When the swirl is generated, the combustion speed is probably increased, thereby improving the combustion state in the EGR gas introduction state and suppressing the deterioration of the surge.

  In an operating region other than the surge deterioration region, the engine controller 31 drives the step motor 19 to open the swirl control valve 18. At this time, the air-fuel mixture containing EGR gas is evenly introduced from the two independent ports 4a and 4b and the flow of each other cancels out in the combustion chamber 5, so that the swirl in the combustion chamber 5 is weakened.

  In this embodiment, the case where the gas flow control valve is the swirl control valve 18 will be described. However, the gas flow control valve may be a tumble control valve.

  An intake valve cam 17 is provided above the intake valve 15, and the intake valve 15 is opened and closed by the intake valve cam 17. The intake valve cam 17 is provided integrally with an intake valve camshaft 28 driven by the crankshaft 7, and is interposed between the intake valve camshaft 28 and a cam sprocket (not shown). An intake valve timing control mechanism (hereinafter referred to as “VTC mechanism”) 29 capable of continuously controlling the phase of the intake valve cam 18 with a constant operating angle is provided.

  In this VTC mechanism 29 (intake valve closing timing variable mechanism), when no signal is given to the VTC mechanism actuator (not shown), the intake valve camshaft 28 is in the most retarded position, and the control is given to the VTC mechanism actuator. As the amount increases, the intake valve camshaft 28 rotates toward the advance side with respect to the cam sprocket. In other words, when no signal is given to the VTC mechanism actuator, the timing at which the intake valve 15 closes (that is, the intake valve closing timing IVC) is at the latest position (the most retarded position), and the control amount given to the VTC mechanism actuator is As the number increases, the closing timing of the intake valve 15 becomes earlier (the intake valve closing timing IVC advances toward the advance side).

  The VTC mechanism 29 is used in a deposit generation area as will be described later.

  Now, in the gasoline engine with an EGR device having the swirl control valve 18 in the vicinity of the intake valve 15, a part of the air-fuel mixture containing EGR gas once flowing into the combustion chamber 5 due to the relationship with the intake valve closing timing. In some cases, it may blow back to the independent ports 4a and 4b. At this time, the EGR gas and the adhesive component adhere or deposit as deposits on the control swirl valve 18 so that the swirl control valve 18 is closed or fixed. The swirl control valve 18 may malfunction. Here, the adhesive component is unburned HC, that is, fuel (gasoline) and blow-by gas particles remaining in the intake port 4 without burning.

  In the present embodiment, the following <Countermeasure 1>, <Countermeasure 2>, <Countermeasure 3> 3 so that the swirl control valve 18 does not malfunction due to deposits / deposition on the swirl control valve 18. By implementing one measure, the diagnostic system for the swirl control valve 18 itself is not required.

  <Countermeasure 1> By operating the VTC mechanism 29 under the operating conditions in which the EGR gas and the adhesive component easily adhere and deposit as deposits on the swirl control valve 18 by blowing back the air-fuel mixture containing EGR gas in the combustion chamber 5. The valve closing timing IVC is advanced to a position where the blowback is weakened, and the blowback amount of the air-fuel mixture containing the adhesive component from the combustion chamber 5 is reduced.

  For example, as shown in FIG. 4, an operation condition in which deposits easily deposit and deposit on the swirl control valve 18 (hereinafter referred to as “deposit”) is assumed. "Generation area") is determined in advance. 4A shows a case where the deposit generation area is included in the surge deterioration area, and FIG. 4B shows a case where the deposit generation area partially overlaps the surge deterioration area. Needless to say, the deposit generation area is in the EGR area.

  The reason why the blowback weakens when the intake valve closing timing IVC is advanced will be described with reference to FIG. That is, since the air-fuel mixture flowing into the combustion chamber 5 has inertia, to increase the charging efficiency of the intake air, the intake valve 15 is closed after the intake bottom dead center BDC as shown by the solid line in FIG. However, since the piston 6 rises from the intake bottom dead center BDC, one of the gases (air mixture containing EGR gas) introduced into the combustion chamber 5 as a result of the piston 6 rising. The portion is pushed back (returned back) to the independent ports 4a and 4b through the gap between the open intake valve 15 and the port wall, so that the gas in the combustion chamber 5 is received by the piston 6 rising. Before the part is pushed back to the independent ports 4a and 4b, that is, as shown by the broken line in FIG. 5, the intake valve 15 should be closed at a position before the intake bottom dead center BDC (before the piston 6 starts to rise). In this case, the Weakening the blowback (reducing the blowback amount) it is because it is.

  <Countermeasure 2> If the ambient temperature of the intake port 4 in the vicinity of the swirl control valve 18 is raised, the deposit adhering to and accumulating on the swirl control valve 18 is dissolved, and the fixing torque of the deposit can be reduced. If the atmospheric temperature of the intake port 4 in the vicinity of the swirl control valve 18 is increased so that the motor torque of 19 overcomes the adhesion torque of the deposit, the swirl control valve 18 can be operated even if deposits are deposited and accumulated. Thus, the operation of the swirl control valve 18 can be guaranteed. Therefore, when the EGR region is reached, the EGR rate control is not performed so that the EGR gas at the target EGR rate (predetermined EGR rate) is immediately introduced, but the swirl control valve 18 is closed as a preparation stage. Even if it does not, the operation at the upper limit value of the EGR rate that does not deteriorate the surge is performed for a certain period of time, the ambient temperature in the vicinity of the swirl control valve 18 is raised, and the deposit adhered / deposited on the swirl control valve 18 is changed from solid to liquid. And the deposit fixing torque is reduced to less than the motor torque of the step motor 19.

  <Countermeasure 3> In the unlikely event that the <Measure 1> and <Countermeasure 1> are not performed, the EGR gas having the target EGR rate is introduced in a malfunctioning state in which the swirl control valve 18 is stuck open and closed. Even when the control shifts to the EGR rate control, the engine rotational speed is detected based on the engine speed sensors (33, 34), and the swirl control valve 18 is fixed to the swirl control valve 18 based on the rotational speed. It is determined whether or not there is an operation failure such as sticking, and when it is determined that there is an operation failure, the target EGR rate is reduced to minimize the deterioration in drivability.

  This control executed by the engine controller 31 (control means) will be described in detail with reference to the following flowchart.

  FIG. 6 is for executing the above <Countermeasure 1>, that is, for performing the advance processing of the intake valve closing timing IVC using the VTC mechanism 29, and is executed at regular intervals (for example, every 10 msec).

  In steps 1 to 3, it is checked whether or not the operating conditions determined from the engine load and the rotational speed are in the deposit generation area this time, and whether or not the previous time was in the deposit generation area.

  The deposit generation area is included in the surge deterioration area as shown in FIG. 4 (see (a)), or partially overlaps with the surge deterioration area (see (b)), or the same as the surge deterioration area Or This is because the deposit is likely to be generated in the vicinity of the swirl control valve 18 because it is in the operating region where the exhaust gas temperature at which the EGR gas and the adhesive component are cooled is low, that is, the operating region on the low load, low rotation side. In addition, the inertia force of the air-fuel mixture flowing into the combustion chamber 5 is small in the low rotation speed range, so that it easily blows back to the intake port 4.

  When it is in the deposit generation area this time and was not in the deposit generation area last time, that is, when it becomes the deposit generation area for the first time this time, it proceeds to step 4 from steps 1 and 2, and the intake valve is closed so that the blowback to the intake port 4 is weakened. A signal for advancing the timing IVC by a predetermined crank angle from the most retarded position is output to the VTC mechanism 29.

  If the current time is in the deposit generation area and the previous time was in the deposit generation area, that is, if it is continuously in the deposit generation area, the current processing is terminated. However, even at this time, the operation of outputting a signal for advancing the intake valve closing timing IVC by a predetermined crank angle to the VTC mechanism 29 is continued.

  When the current time is not in the deposit generation area and the previous time was in the deposit generation area, that is, when switching from the deposit generation area to a non-deposit generation area for the first time this time, the process proceeds from step 1 to step 5 to output to the VTC mechanism 29. The intake valve closing timing IVC is returned to the original most retarded position.

  If it is not in the deposit generation area this time and was not in the deposit generation area last time, that is, if it is not in the deposit generation area, the current process is terminated. At this time, it is not output to the VTC mechanism 29, and the intake valve closing timing IVC is at the most retarded position.

  In this way, according to the flow of FIG. 6, as long as the deposit is generated, the intake valve closing timing IVC is advanced by a predetermined crank angle by using the VTC mechanism 29, so that the blowback to the intake port 4 is weakened and swirl control is performed. The deposit / deposition of the deposit on the valve 18 is avoided in advance.

  FIGS. 7A and 7B are for setting the target EGR rate and controlling the opening and closing of the swirl control valve 18, and are executed at regular intervals (for example, every 10 msec) independently of FIG.

  Of these, FIG. 7A executes the above-mentioned <Countermeasure 2>, that is, a portion where the ambient temperature of the deposit adhering and depositing in the vicinity of the swirl control valve 18 is raised, steps 24-28 in FIG. 7B. , 30 to 33 are parts for executing the above <Countermeasure 3>, that is, for reducing the target EGR rate when there is rotational fluctuation in the EGR region.

  To explain in sequence, in FIG. 7A, in step 11, the operation guarantee flag (initially set to zero at the start) is seen. Here, assuming that the operation guarantee flag = 0, at this time, the process proceeds to step 12 to check whether or not it is in the EGR region. The EGR region is the three regions R1, R2, and R3 shown in FIG. If the operating point determined from the engine load and the rotational speed is included in any of the regions R1, R2, and R3, if the operating point is in the EGR region, the operating point determined from the engine load and the rotational speed is the region R1, If it is not included in any of R2 and R3 (that is, if it is in region R4), it is determined that it is not in the EGR region. If it is not in the EGR area, the current process is terminated.

  When it is in the EGR region, the process proceeds from step 12 to step 13 and the preparation start flag (initially set to zero at the start) is checked. Here, assuming that the preparation start flag = 0, at this time, the routine proceeds to step 14 where a predetermined EGR rate upper limit value is set as the target EGR rate. Here, the predetermined EGR upper limit value is set in advance as an upper limit value of the EGR rate that does not require the swirl control valve 18 to be closed for surge suppression.

  Even if the swirl control valve 18 is closed or fixed due to deposit, a predetermined upper limit value of the EGR rate is set as the target EGR rate, and a considerable amount of high-temperature EGR gas is taken into the intake port near the swirl control valve 18. 4, the solid deposit is heated by the high heat of the EGR gas, and the temperature rises and dissolves. As the deposit dissolves, the fixing torque of the deposit decreases.

  In step 15, a timer is started. This timer is for measuring the time after a predetermined EGR rate upper limit value is set as the target EGR rate. As the timer, for example, a timer provided in the engine controller 31 can be used.

  In step 16, the preparation start flag = 1 is set, and the predetermined EGR rate upper limit value is set as the target EGR rate, that is, the preparation before the operation of the swirl control valve 18 is started.

  When it is in the EGR area from the next time onward, the preparation start flag = 1, so that the process proceeds from step 13 to step 17 from the next time. In step 17, the timer value is compared with a predetermined value.

  By setting a predetermined EGR rate upper limit value as the target EGR rate, as described above, if the solid-state deposit is melted by the high heat of the EGR gas and the fixing torque of the deposit becomes less than the motor torque, the deposit is reduced. The operation of the swirl control valve 18 can be assured even if it adheres and accumulates. In this case, since the time from when the predetermined EGR rate upper limit value is set as the target EGR rate until the fixing torque of the deposit becomes less than the motor torque can be known in advance by experiment, the time obtained by adding the margin to the time is obtained. What is necessary is just to set as a predetermined value. That is, the predetermined value is a time obtained by adding an allowance to the time from when the predetermined EGR rate upper limit value is set as the target EGR rate until the fixing torque of the deposit becomes less than the motor torque.

  When the timer value is less than the predetermined value, the current process is terminated. At this time, the target EGR rate is set to a predetermined EGR rate upper limit value.

  When the timer value becomes equal to or greater than the predetermined value, the swirl control valve 18 is operated, that is, the preparation before the shift to the EGR rate control in which the EGR gas having the target EGR rate is introduced is completed. Is determined to be guaranteed, and the process proceeds to step 18 to set the operation guarantee flag = 1. In step 19, the preparation start flag = 0 is set in preparation for the case where the EGR area is entered again after leaving the EGR area.

  Since the operation guarantee flag = 1, the process proceeds to FIG.

  In FIG. 7B, it is checked in step 20 whether or not it is in the EGR area. This operation is the same as step 12 in FIG. If it is in the EGR region, the process proceeds to step 21 to search the map having the contents shown in FIG. 2 from the engine load and the rotational speed Ne, thereby calculating the EGR rate basic value Megr0. For example, if the operating point determined from the engine load and the rotational speed belongs to the region R1 shown in FIG. 2, the EGR rate basic value of the region R1 is shown as the operating point determined from the engine load and the rotational speed. If it belongs to the region R2, the EGR rate basic value of the region R2, and if the operating point determined from the engine load and the rotational speed belongs to the region R3 shown in FIG. 2, the EGR rate basic value of the region R3. For each.

  Each region R1, R2, R3 contains large values in this order. As described above, the larger the value is on the low load low rotation speed side, the smaller the opening degree of the intake throttle valve 23 is on the low load low rotation speed side, and the larger the pumping loss is. This is because the valve 26 is greatly opened to increase the amount of EGR gas introduced downstream of the intake throttle valve 23 to reduce the pumping loss.

  In step 22, it is determined whether or not the surge is worse. Since the surge deterioration area is known in advance as shown in FIG. 4, for example, if it is in the surge deterioration area, the process proceeds to step 23, and an instruction is issued to the step motor 19 to bring the swirl control valve 18 into the closed operation state. As a result, a swirl is generated in the combustion chamber 5 to improve the combustion state, and the surge is suppressed so as not to cause combustion fluctuations.

  In step 24, the fluctuation amount per predetermined time is calculated as the rotation fluctuation amount ΔN from the engine rotation speed Ne, and in step 25, the calculated rotation fluctuation amount ΔN is compared with a predetermined value. If the rotational fluctuation amount ΔN is less than the predetermined value, it is determined that there is no rotational fluctuation, that is, the swirl control valve is not stuck open, and the routine proceeds to step 26 where the EGR rate basic value Megr0 obtained in step 21 is used as the target EGR rate. Set.

  If the rotational fluctuation amount ΔN is greater than or equal to a predetermined value in step 25, it is determined that there is rotational fluctuation. In step 23, it is instructed to close the swirl control valve 18, and if the swirl control valve 18 is actually in the closed operation state in response to this, the above-described combustion fluctuation, and therefore the rotation fluctuation, It does not occur. In other words, if the command to set the swirl control valve 18 in the closed operation state is instructed in step 23, but the swirl control valve 18 is not actually fixed in the closed operation state, the above-described operation will be performed. Combustion fluctuations and therefore rotation fluctuations will occur. That is, it is determined whether or not the swirl control valve 18 is stuck open based on the rotational fluctuation.

  When there is a rotational fluctuation, the routine proceeds to step 27, where the EGR rate reduction correction amount Rgen is updated by setting the value obtained by adding the predetermined value ΔR to the previous value of the EGR rate reduction correction amount as the current value of the EGR rate reduction correction amount. The initial value of the EGR rate reduction correction amount Rgen is zero. Accordingly, when it is determined for the first time that the rotational fluctuation has occurred, the reduction amount correction amount Rgen becomes the predetermined value ΔR.

  In step 28, a value obtained by subtracting the EGR rate decrease correction amount Rgen from the EGR rate basic value Megr0 obtained in step 21 is set as the target EGR rate.

  Since it is determined whether or not there is a rotation fluctuation at regular time intervals, the reduction correction amount Rgen is ΔR × 2 when it is determined again that the rotation fluctuation has occurred next time. In this way, the decrease correction amount Rgen increases, and the target EGR rate is corrected for decrease by this increasing decrease correction amount Rgen. This target EGR rate reduction correction continues until the rotational fluctuations, and thus the combustion fluctuations, disappear.

  In this way, by correcting the target EGR rate so that the fluctuation of combustion does not occur, the surge can be suppressed even when the swirl control valve 18 has a malfunction such as open fixation.

  When it is not in the surge deterioration region in step 22, the process proceeds to step 29, and an instruction is issued to the step motor 19 so that the swirl control valve 18 is opened.

  Step 30 and subsequent steps are the same as step 24 and subsequent steps. In step 30, the fluctuation amount per predetermined time is calculated as the rotation fluctuation amount ΔN from the engine speed Ne, and in step 31, the calculated rotation fluctuation amount ΔN is compared with a predetermined value. If the rotational fluctuation amount ΔN is less than the predetermined value, it is determined that there is no rotational fluctuation, that is, the swirl control valve is not closed and stuck, and the routine proceeds to step 26 where the EGR rate basic value Megr0 obtained in step 21 is used as the target EGR rate. Set.

  If the rotation fluctuation amount ΔN is greater than or equal to a predetermined value in step 31, it is determined that there is a rotation fluctuation. In step 29, it is instructed to open the swirl control valve 18, and if the swirl control valve 18 is actually in the open operation state in response to this, combustion fluctuations and therefore rotation fluctuations will occur. There is no. In other words, if the swirl control valve 18 is instructed to be in the open operation state in step 29, but the swirl control valve 18 is not actually closed and not in the open operation state, the surge deteriorates. A swirl that does not need to be applied because it is in the operating region other than the region is generated, and on the contrary, combustion becomes unstable and rotational fluctuation occurs. That is, it is determined whether or not the swirl control valve 18 is closed and stuck due to the rotational fluctuation.

  When there is a rotational fluctuation, the routine proceeds to step 32, where the EGR rate reduction correction amount Rgen is updated by setting the value obtained by adding the predetermined value ΔR to the previous value of the EGR rate reduction correction amount as the current value of the EGR rate reduction correction amount. The initial value of the EGR rate reduction correction amount Rgen is zero. Accordingly, when it is determined for the first time that the rotational fluctuation has occurred, the reduction amount correction amount Rgen becomes the predetermined value ΔR.

  In step 33, a value obtained by subtracting the EGR rate decrease correction amount Rgen from the EGR rate basic value Megr0 obtained in step 21 is set as the target EGR rate.

  Since it is determined whether or not there is a rotation fluctuation at regular time intervals, the reduction correction amount Rgen is ΔR × 2 when it is determined again that the rotation fluctuation has occurred next time. In this way, the decrease correction amount Rgen increases, and the target EGR rate is corrected for decrease by this increasing decrease correction amount Rgen. This target EGR rate reduction correction continues until the rotational fluctuations, and thus the combustion fluctuations, disappear.

  In this way, by correcting the target EGR rate so that the rotation fluctuation does not occur, the rotation fluctuation can be suppressed even when the swirl control valve 18 has a malfunction such as closed adhering.

  On the other hand, it is determined that the operation condition has changed after the operation guarantee flag = 1 in Step 20 in Step 20, so that it is determined that the operation condition is no longer in the EGR region. In this case, the process proceeds to Steps 34 and 35 and the swirl control valve 18 is opened. An instruction is issued to the step motor 19 to set the state, and the target EGR rate = 0.

  In step 36, the operation guarantee flag is set to 0 to prepare for the next EGR area.

  When the EGR area is reached again after leaving the EGR area, the process proceeds from Steps 11 and 12 in FIG. 7A to Step 13, and the above operation is repeated.

 In this way, when the EGR region is reached, the shift to the EGR rate control in which the EGR gas having the target EGR rate is immediately introduced is not performed, but the deposit fixing torque is less than the motor torque of the step motor 19. Until the atmosphere of the deposit adhering / depositing on the swirl control valve is raised, and then the EGR rate control is performed so that the EGR gas of the target EGR rate is introduced.

  The target EGR rate set according to FIGS. 7A and 7B is converted into a step number in a flow (not shown), and this step number is output to the step motor 19.

  Note that once the engine is warmed, as long as the engine is running, the EGR gas and adhesive component as deposits become liquid, and the swirl control valve 18 will not stick when the EGR gas and adhesive component are liquid. After the engine is started, once the operation guarantee flag is set to 1, when the EGR area is re-entered and then re-entered into the EGR area, the swirl control valve 18 is immediately prepared without preparation before the operation. The control motor 18 can be closed to control the step motor 27 so that the target EGR rate is obtained.

  Here, the effect of this embodiment is demonstrated.

  According to the present embodiment (the inventions described in claims 1 and 7), the EGR valve 26 (EGR device) and the swirl control valve 18 (gas flow control valve) are provided. The EGR valve 26 is controlled so that EGR gas having an EGR rate) is introduced (see steps 20, 21, and 26 in FIG. 7B), and a swirl control valve is used when a surge worsens during the introduction of the EGR gas. 18 is in a closed operation state (see steps 22 and 23 in FIG. 7B), while a VTC mechanism 29 (intake valve closing timing variable mechanism) is provided, and an air-fuel mixture containing EGR gas in the combustion chamber 5 is Whether or not the operation condition is such that the EGR gas and the adhesive component are easily deposited and deposited as deposits on the swirl control valve 18 by blowing back to the vicinity of the swirl control valve 18. When it is determined (see step 1 in FIG. 6) and it is determined that the operation condition is satisfied, the intake valve closing timing is advanced to a position where the blowback is weakened using the VTC mechanism 29 (step 1 in FIG. 6). 2, 4).

  Thereby, since the blowback of the air-fuel mixture containing the EGR gas (including the fuel serving as the adhesive component) can be suppressed, it is possible to prevent malfunction such as adhesion of the swirl control valve 18 due to deposit adhesion / deposition. If the malfunction of the swirl control valve 18 due to deposit adhesion / deposition can be prevented, the EGR of the target EGR rate can be achieved without having a detection means for detecting whether or not the swirl control valve 18 has malfunctioned. The EGR rate control that allows the gas to be introduced can be continuously executed. Further, the diagnostic system and detection means for the swirl control valve 18 itself are not necessary, and the cost can be reduced.

  According to the present embodiment (the invention described in claims 3 and 9), the EGR valve 26 (EGR device) and the swirl control valve 18 (gas flow control valve) are provided, and when the EGR region is reached, the target EGR rate ( The EGR valve 26 is controlled so that EGR gas having a predetermined EGR rate is introduced (see steps 20, 21, and 26 in FIG. 7B), and swirl control is performed when a surge worsens during the introduction of EGR gas. While the valve 18 is closed (see steps 22 and 23 in FIG. 7B), the EGR gas and the adhesive component are generated by blowing back the air-fuel mixture containing the EGR gas in the combustion chamber to the vicinity of the swirl control valve 18. Is deposited and deposited on the swirl control valve 18 as a deposit, the fixing torque of this deposit is the motor torque of the step motor 19. Since the atmospheric temperature of the swirl control valve 18 is raised until it becomes less than (the driving torque of the gas flow control valve actuator) (see steps 11, 12, 13, and 14 in FIG. 7A), the deposit adheres and accumulates. Thus, the swirl control valve 18 can be operated even if the swirl control valve 18 has a malfunction such as open fixation or closed fixation.

  According to the present embodiment (the inventions described in claims 6 and 12), the engine rotation fluctuation is detected, and the target EGR rate is reduced when there is a rotation fluctuation during the introduction of EGR gas (FIG. 7B ), Steps 24 to 28 and 30 to 33), the EGR gas having the target EGR rate (predetermined EGR rate) is introduced while the swirl control valve 18 is not properly operated due to adhesion or accumulation of deposits. Even if the EGR rate control is performed to cause a combustion failure, the deterioration of operability can be minimized.

  The EGR rate control processing procedure of claim 1 is performed by steps 20, 21, and 26 in FIG. 7B, the closing operation processing procedure is performed by steps 22 and 23 of FIG. 7B, and the operating condition determination processing procedure is performed by FIG. By step 1, the advance processing procedure is performed by steps 1, 2, and 4 in FIG.

  The EGR rate control processing procedure of claim 3 is performed by steps 20, 21, and 26 in FIG. 7B, the closing operation processing procedure is performed by steps 22 and 23 of FIG. 7B, and the ambient temperature increase processing procedure is (FIG. 7). This is accomplished by steps 11, 12, 13, and 14 of (A).

  [7] The function of the EGR rate control means is according to steps 20, 21, and 26 of FIG. 7B, the function of the closing operation means is according to steps 22 and 23 of FIG. 7B, and the function of the operating condition determination means is FIG. In step 1, the advance angle function is performed by steps 1, 2, and 4 in FIG.

  The function of the EGR rate control means of claim 9 is the function of steps 20, 21 and 26 in FIG. 7B, the function of the closing operation means is the steps 22 and 23 of FIG. (Performed by steps 11, 12, 13, and 14 in FIG. 7A, respectively.

The schematic block diagram of the control apparatus of the engine of 1st Embodiment of this invention. The characteristic view of an EGR rate basic value. Swirl control valve layout. The area | region figure which shows a surge deterioration area and a deposit production | generation area. The characteristic view of the intake valve lift for explaining the function of the VTC mechanism. The flowchart for demonstrating the advance processing of an intake valve closing timing. The flowchart for demonstrating the setting of a target EGR rate, and the opening / closing control of a swirl control valve. The flowchart for demonstrating the setting of a target EGR rate, and the opening / closing control of a swirl control valve.

Explanation of symbols

3 Intake manifold 4 Intake port 8 Exhaust passage 11 Engine controller (control means)
15 Intake valve 18 Swirl control valve (gas flow control valve)
19 Step motor (Gas flow control valve actuator)
26 EGR valve (EGR device)
29 VTC mechanism (intake valve closing timing variable mechanism)

Claims (12)

An EGR device that introduces part of the exhaust gas as EGR gas downstream of the intake throttle valve;
A gas flow control valve that is in the vicinity of the intake valve and generates a gas flow in the combustion chamber in an operating state;
When the EGR region is reached, an EGR rate control processing procedure for controlling the EGR device so that EGR gas having a predetermined EGR rate is introduced;
A closing operation processing procedure for closing the gas flow control valve when a surge worsens during the introduction of EGR gas,
An intake valve closing timing variable mechanism capable of variably controlling the closing timing of the intake valve;
Judgment is made on whether or not the operating condition is such that EGR gas and adhesive components are likely to adhere and accumulate as deposits on the gas flow control valve by blowing back the air-fuel mixture containing EGR gas in the combustion chamber to the vicinity of the gas flow control valve. Operating condition determination processing procedure to
An advance angle processing procedure for advancing the intake valve closing timing to a position where the blowback weakens using the intake valve closing timing variable mechanism when it is determined that the operating condition is satisfied. Control method.   The engine control method according to claim 1, wherein the position where the blowback is weakened is a position before the piston starts to rise. An EGR device that introduces part of the exhaust gas as EGR gas downstream of the intake throttle valve;
A gas flow control valve that is in the vicinity of the intake valve and generates a gas flow in the combustion chamber in an operating state,
When the EGR region is reached, an EGR rate control processing procedure for controlling the EGR device so that EGR gas having a predetermined EGR rate is introduced;
A closing operation processing procedure for closing the gas flow control valve when a surge worsens during the introduction of EGR gas,
When the gas mixture containing EGR gas in the combustion chamber blows back to the vicinity of the gas flow control valve, and the EGR gas and the adhesive component adhere to and accumulate on the gas flow control valve as deposits, this deposit fixing torque A method for controlling an engine, comprising: an atmospheric temperature increase processing procedure for increasing an atmospheric temperature of the gas flow control valve until the gas flow control valve actuator becomes less than a driving torque of the gas flow control valve actuator.   The said atmospheric temperature rise process sequence is a process sequence which performs the operation | movement by the upper limit of the EGR rate which does not deteriorate a surge even if it does not operate a gas flow control valve for a fixed time. How to control the engine.   The engine control method according to claim 3 or 4, wherein the ambient temperature of the gas flow control valve is raised before the gas flow control valve is operated. Rotation fluctuation detection processing procedure for detecting engine rotation fluctuation,
The engine control method according to claim 1, further comprising: a processing procedure for reducing an EGR rate when there is a rotational fluctuation during the introduction of the EGR gas. An EGR device that introduces part of the exhaust gas as EGR gas downstream of the intake throttle valve;
A gas flow control valve that is in the vicinity of the intake valve and generates a gas flow in the combustion chamber in an operating state,
EGR rate control means for controlling the EGR device so that an EGR gas having a predetermined EGR rate is introduced when the EGR region is reached;
A closing operation means for closing the gas flow control valve when a surge worsens during the introduction of EGR gas,
An intake valve closing timing variable mechanism capable of variably controlling the closing timing of the intake valve;
Judgment is made on whether or not the operating condition is such that EGR gas and adhesive components are likely to adhere and accumulate as deposits on the gas flow control valve by blowing back the air-fuel mixture containing EGR gas in the combustion chamber to the vicinity of the gas flow control valve. Operating condition determining means for
And advancing means for advancing the intake valve closing timing to a position where the blowback is weakened using the intake valve closing timing variable mechanism when it is determined that the operating condition is satisfied. apparatus.   The engine control device according to claim 7, wherein the position where the blowback is weakened is a position before the piston starts to rise. An EGR device that introduces part of the exhaust gas as EGR gas downstream of the intake throttle valve;
A gas flow control valve that is in the vicinity of the intake valve and generates a gas flow in the combustion chamber in an operating state,
EGR rate control means for controlling the EGR device so that an EGR gas having a predetermined EGR rate is introduced when the EGR region is reached;
A closing operation means for closing the gas flow control valve when a surge worsens during the introduction of EGR gas,
When the gas mixture containing EGR gas in the combustion chamber blows back to the vicinity of the gas flow control valve, and the EGR gas and the adhesive component adhere to and accumulate on the gas flow control valve as deposits, this deposit fixing torque An engine temperature control means for increasing the ambient temperature of the gas flow control valve until the gas flow control valve actuator becomes less than the driving torque of the gas flow control valve actuator.   10. The engine according to claim 9, wherein the ambient temperature increasing unit is a unit that executes an operation at an upper limit value of an EGR rate that does not deteriorate a surge without operating a gas flow control valve for a certain period of time. Control device.   The engine control device according to claim 9 or 10, wherein the temperature of the atmosphere of the gas flow control valve is raised before the gas flow control valve is operated. Rotation fluctuation detecting means for detecting engine rotation fluctuation;
10. The engine control device according to claim 7, further comprising: means for reducing an EGR rate when there is a rotational fluctuation during the introduction of the EGR gas.

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