JP2010138734A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration of operability due to torque increase caused by increase of fresh air quantity during deceleration. <P>SOLUTION: Throttle valve closing speed at a beginning is controlled to be slower than prescribed throttle valve closing speed not to increase fresh air quantity in suction air quantity with close of an EGR valve when a vehicle is decelerated under prescribed conditions, the throttle valve close velocity is controlled to the prescribed throttle valve speed after that, and a throttle valve 6 is closed to target throttle valve opening. Consequently, since fresh air quantity in the suction air quantity does not increase with close of the EGR valve 11, increase of torque due to increase of fresh air quantity during deceleration is prevented and operability is improved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine.

In Patent Document 1, when the throttle valve is closed due to a deceleration request, the EGR valve is closed to stop the exhaust gas from flowing back to the intake passage downstream of the throttle valve, and then the throttle valve is closed. Thus, there is disclosed a technique that avoids a sudden increase in the EGR rate in the cylinder after a deceleration request and a misfire.
JP 2006-194143 A

  However, if the throttle valve is closed after the EGR valve is closed when there is a deceleration request as in Patent Document 1, the throttle opening of the throttle valve is detected when the EGR valve is closed. Since the opening at the time is maintained, the amount of fresh air in the amount of intake air increases by the amount of exhaust gas recirculated to the intake passage, and torque is reduced despite demand for deceleration. There is a risk of increase.

  Therefore, according to the present invention, when the vehicle is decelerated under a predetermined condition, the initial throttle valve closing speed is controlled to a speed lower than the intended throttle valve closing speed, and the EGR valve is closed. The new air volume in the intake air volume is prevented from increasing, and the throttle valve closing speed is then controlled to the desired throttle valve closing speed to close the throttle valve to the target throttle valve opening. Yes.

  According to the present invention, since the amount of fresh air occupying the amount of intake air does not increase when the EGR valve is closed, it is possible to prevent the amount of fresh air from increasing and the torque from increasing during deceleration. Can be improved.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram schematically showing the overall configuration of an in-line four-cylinder internal combustion engine 1 to which the present invention is applied.

  As shown in FIG. 1, the internal combustion engine 1 of this embodiment is, for example, an in-line four-cylinder engine, and an intake passage 2 includes a branch passage portion 3 to which an intake port (not shown) of each cylinder is connected, And a collector portion 4 having an appropriate volume to which the branch passage portion 3 is connected. The collector unit 4 is provided with a pressure sensor 5 as pressure detecting means for detecting a collector pressure (suction negative pressure) that is a pressure in the collector unit 4.

  The intake passage 2 has an electronically controlled throttle valve 6 for controlling the intake flow rate and a throttle valve opening sensor for detecting the opening of the throttle valve 6 at a position upstream (inlet side) of the collector section 4. 7. The throttle valve 6 can operate independently of the accelerator pedal operation. Further, the intake passage 2 is provided with an air flow meter 8 that measures the flow rate of the intake air at this position on the upstream side (inlet side) of the throttle valve 6. An exhaust passage 9 is connected to an exhaust port (not shown) of each cylinder.

  An EGR passage 10 is provided between the intake passage 2 and the exhaust passage 9. One end of the EGR passage 10 is connected to the intake passage 2 on the downstream side of the throttle valve 6, and the other end is connected to the exhaust passage 9. The EGR passage 10 is provided with an EGR valve 11 for controlling the flow rate of the exhaust gas recirculated to the intake passage 2 and an EGR valve opening degree sensor 12 for detecting the valve opening degree of the EGR valve. .

  The EGR valve 11 and the throttle valve 6 are controlled by a control signal from an ECU (Engine Control Unit) 13. Note that the maximum valve closing speed of the EGR valve 11 is slower than the maximum valve closing speed of the throttle valve 6. Further, the intended closing speed of the EGR valve 11 is the maximum closing speed, and the EGR valve 11 is controlled so as to always close at the intended closing speed. On the other hand, the closing speed of the throttle valve 6 is normally controlled so as to increase as the return speed of an accelerator pedal (not shown) increases. That is, the intended valve closing speed of the throttle valve 6 is determined according to the return speed of the accelerator pedal.

  The return speed of the accelerator pedal is detected from a signal from an accelerator opening sensor 16 described later.

  The ECU 13 includes a pressure sensor 5, an air flow meter 8, a throttle valve opening sensor 7, an EGR valve opening sensor 12, a vehicle speed sensor 14 that detects the vehicle speed, an engine speed sensor 15 that detects the speed of the internal combustion engine 1, and an accelerator. A signal detected by a sensor such as an accelerator opening sensor 16 that detects a depression amount (accelerator opening APO) of a pedal (not shown) is input.

  Here, when the vehicle is decelerated, if the throttle valve 6 is closed and the EGR valve 11 is open, the EGR valve 11 is also closed. However, when the throttle valve 6 is closed, the valve opening of the throttle valve 6 is reduced. The negative pressure develops and the collector pressure increases (the suction negative pressure increases).

  As shown by a solid line in FIG. 2, when the vehicle decelerates, when the throttle valve 6 and the EGR valve 11 are simultaneously started to close at the intended closing speed, the desired closing of the throttle valve 6 is performed. Since the speed is faster than the intended closing speed of the EGR valve 11, the EGR valve 11 does not follow the increase in the collector pressure as the throttle valve opening decreases, and the EGR amount overshoots. To do.

  Further, as indicated by a broken line in FIG. 2, when the vehicle decelerates, the opening of the throttle valve 6 is maintained at the opening just before the vehicle decelerates until the EGR valve 11 is fully closed, and the EGR valve 11 If the throttle valve 6 is fully closed after the valve is fully closed, the EGR amount overshoot does not occur, but the amount of fresh air in the intake air amount is reduced by the amount of exhaust gas recirculated to the intake passage 2. As a result, the torque increases even though there is a deceleration request.

  FIG. 3 is an explanatory diagram showing the correlation between the collector pressure and the EGR amount when the throttle valve 6 and the EGR valve 11 are fully closed from the steady state. In other words, FIG. 3 is an explanatory diagram showing the correlation between the collector pressure and the EGR amount when the throttle valve 6 and the EGR valve 11 are fully closed by deceleration.

  In a steady state (characteristic line a in FIG. 3), the EGR amount is controlled to be constant regardless of the collector pressure. On the other hand, when the throttle valve 6 and the EGR valve 11 are closed from the throttle valve opening in the steady state and the EGR valve opening in the steady state to the fully closed state, respectively, the desired valve closing speed of the throttle valve 6 is the EGR valve 11. Therefore, as shown by the characteristic line b in FIG. 3, the valve closing speed of the EGR valve 11 follows the increase in the collector pressure accompanying the decrease in the throttle valve opening. Without overshooting the EGR amount.

  As shown by the characteristic line b in FIG. 3, when the vehicle decelerates, the throttle valve 6 and the EGR valve 11 are both small in the state where the collector pressure is large, so the EGR amount overshoot is also small. Although the misfire limit value is not exceeded, when the collector pressure is small, the throttle valve 6 and the EGR valve 11 are both large in opening, so the overshoot of the EGR amount increases, and the misfire limit value decreases as the collector pressure decreases. Will be greatly exceeded.

  FIG. 4 shows that when the EGR valve 11 is fully closed from the steady state, the change in the collector pressure is such that the EGR amount becomes less than the misfire limit value even if the EGR amount overshoots, that is, the misfire limit even if the EGR amount overshoots. It is explanatory drawing which showed typically the change margin of the valve opening degree of the throttle valve 6 which becomes below a value. A characteristic line c in FIG. 4 represents the collector pressure before deceleration, and a characteristic line d in FIG. 4 represents an allowable collector pressure (allowable suction negative pressure) that is a misfire limit allowable value with respect to the collector pressure before deceleration.

  The larger the collector pressure before deceleration, the smaller the overshoot of the EGR amount. Therefore, even if the amount of change in the collector pressure in the direction in which the collector pressure develops during deceleration increases, the EGR amount does not exceed this misfire limit tolerance. . That is, as shown in FIG. 4, as the collector pressure before deceleration increases, the differential pressure P between the collector pressure before deceleration and the allowable collector pressure as the misfire limit allowable value corresponding to the collector pressure before deceleration increases. . In other words, the collector pressure does not become the misfire limit allowable value even if the change amount of the valve opening in the valve closing direction of the throttle valve 6 is increased as the collector pressure before deceleration increases.

  Therefore, in the present embodiment, when the vehicle decelerates, the ECU 13 prevents an increase in torque due to an increase in the amount of fresh air in the intake air amount while preventing misfire due to an overshoot of the EGR amount. The throttle valve 6 and the EGR valve 11 are controlled.

  FIG. 5 is a flowchart showing a flow of control during deceleration of the vehicle in the first embodiment of the present invention. This control is executed by the ECU 13.

  In step (hereinafter referred to as S) 1, the vehicle speed, the rotational speed of the internal combustion engine 1 and the return speed of the accelerator pedal are read, and a deceleration determination is performed to determine whether or not the vehicle is in a predetermined deceleration state. . Specifically, when the rotational speed of the internal combustion engine 1 is equal to or higher than a predetermined speed, the vehicle speed is equal to or higher than the predetermined vehicle speed, and the return speed of the accelerator pedal is equal to or higher than a predetermined value, it is determined that the vehicle is decelerating and the process proceeds to S2. Otherwise, the current routine is terminated. In other words, in S 1, the rotational speed of the internal combustion engine 1 is equal to or higher than the predetermined rotational speed, the vehicle speed is equal to or higher than the predetermined vehicle speed, and the closing speed of the throttle valve 6 is higher than the intended closing speed of the EGR valve 11. It is determined that the vehicle is in a deceleration state when the accelerator pedal is returned at such a speed. The return speed of the accelerator pedal is calculated in the ECU 13 using a signal from the accelerator opening sensor 16.

  In S2, it is determined whether or not the opening degree of the EGR valve 11 is larger than “0”, that is, whether or not the EGR valve 11 is in the open state, and if the EGR valve 11 is open. Proceeding to S3, if the EGR valve 11 is not open, that is, if the EGR valve 11 is already fully closed, the current routine is terminated.

  In S3, the accelerator opening APO (now) when it is determined that the vehicle is decelerating and the collector pressure when it is determined that the vehicle is decelerating are read, and the process proceeds to S4.

  In S4, the accelerator opening APO (now) read in S3 is used to calculate the target collector pressure as the target suction negative pressure with reference to the characteristic map shown in FIG. 6, and the process proceeds to S5. The target collector pressure becomes larger as the accelerator opening is larger, that is, a larger negative pressure.

  In S5, the collector pressure read in S3 is used to calculate the allowable collector pressure as the allowable suction negative pressure with reference to the characteristic map shown in FIG. 7, and the process proceeds to S6. The allowable collector pressure calculated using FIG. 7 is the allowable collector pressure of FIG. 4 described above.

  In S6, it is determined whether or not the allowable collector pressure is higher than the target collector pressure. If the allowable collector pressure is higher than the target collector pressure, the process proceeds to S7, and if the allowable collector pressure is equal to or lower than the target collector pressure, S15. Proceed to In other words, in S6, it is determined whether or not the allowable collector pressure deviates by more than a predetermined value set in advance with respect to the target collector pressure. If so, the process proceeds to S15.

  In S15, the EGR valve 11 and the throttle valve 6 are simultaneously closed at the desired valve closing speed, and the current routine is terminated. That is, in S15, the throttle valve normal control at the time of deceleration is performed to close the throttle valve 6 at the desired valve closing speed.

  In S7, the intake air amount Qa, the throttle valve opening TVO (now), the EGR valve opening, and the engine speed Ne when it is determined that the vehicle is decelerating are read, and the process proceeds to S8. The intake air intake amount Qa is detected by the air flow meter 8.

  In S8, TVO (egr-less) as the second target throttle valve opening, which is the target throttle valve opening when there is no EGR, is calculated using Qa and Ne read in S7, and the process proceeds to S9.

  In S9, S (allowable) that is the opening area of the throttle valve 6 corresponding to the allowable collector pressure is calculated using the following equation (1), and the process proceeds to S10.

[Formula 1] S (allowable) = S (egr-less) * √ ((collector pressure) / allowable collector pressure)) (1)
In this equation (1), S (egr-less) is the opening area of the throttle valve 6 corresponding to TVO (egr-less) calculated in S8.

  In S10, using the S (allowance) that is the opening area of the throttle valve 6 corresponding to the allowable collector pressure calculated in S9, the throttle valve opening corresponding to the allowable collector pressure is referred to with reference to the characteristic map shown in FIG. TVO (allowance) is calculated, and the process proceeds to S11.

  In S11, the time t (egr) until the EGR valve 11 is fully closed is calculated using the following equation (2), and the process proceeds to S12. That is, in S11, the response time t (egr) that is the closing time of the EGR valve 11 required until the valve is fully closed from the opening state when it is determined that the vehicle is decelerating is calculated.

[Expression 2] t (egr) = EGR valve opening / EGR valve closing speed (2)
In this equation (2), the EGR valve closing speed is an intended valve closing speed of the EGR valve 11, that is, the maximum valve closing speed of the EGR valve 11, and is a constant value.

  In S12, t (th / c), which is a response time to the target opening of the throttle valve 6 when it is determined that the vehicle is decelerating, is calculated using the following equation (3), and the process proceeds to S13.

[Formula 3] t (th / c) = (APO (before deceleration determination) −APO (target)) / ΔAPO (3)
In this equation (3), APO (before deceleration determination) is the accelerator opening measured immediately before it is determined that the vehicle is in a deceleration state. APO (target) is the target accelerator opening in the deceleration state, that is, the final accelerator opening in the deceleration state. ΔAPO is the change rate of the accelerator opening when it is determined that the vehicle is in a decelerating state.

  The APO (target) and ΔAPO are calculated in the ECU 13 based on a signal from the accelerator opening sensor 16.

  In S13, until the response time t (th / c) to the target opening of the throttle valve 6 when it is determined that the vehicle is in the deceleration state is fully closed when the EGR valve 11 is determined to be in the deceleration state. It is determined whether or not the response time t (egr) is longer (longer), and if longer, the process proceeds to S14, and if not, the process proceeds to S15. In other words, in S13, when it is determined that the vehicle is decelerating, the EGR valve response time t (egr) until the EGR valve 11 is fully closed at the intended valve closing speed, and the throttle valve 6 is The throttle valve response time t (th / c) until the target throttle valve opening is reached at the desired valve closing speed is calculated, and the EGR valve response time t (egr) and the throttle valve response time t (th / c) If there is no deviation larger than a predetermined value set in advance, the process proceeds to S15, and if not, the process proceeds to S14.

  In the first embodiment, the right side of the judgment formula used in S13 is “0”. However, if a safety margin is taken, a positive threshold value of “0” or more is set to “0”. It is also possible to substitute for this right side. The target throttle valve opening is calculated in the ECU 13 using a signal from the accelerator opening sensor 16.

  In S14, as shown in FIG. 9, the EGR valve 11 is closed at the desired closing speed until it is fully closed, and the throttle valve 6 is further controlled to a speed slower than the intended throttle valve closing speed. As the valve 11 is closed, the amount of fresh air in the amount of intake air is prevented from increasing, and thereafter the throttle valve closing speed is controlled to the desired throttle valve closing speed to control the throttle valve 6 to the target throttle valve. Close to opening. In other words, in S14, control is performed so that the valve opening degree of the throttle valve 6 when the EGR valve 11 is in the closed state becomes the throttle valve opening degree that is the allowable suction negative pressure in the deceleration state. Then, the throttle valve cooperative control during deceleration is performed to control the subsequent throttle valve closing speed to the desired throttle valve closing speed.

  Furthermore, in S14, the throttle valve 6 and the EGR valve 11 are in the period from immediately after it is determined that the vehicle is decelerating (t = ta) until the EGR valve 11 is fully closed (t = tb). Control is performed at a constant valve closing speed such that TVO (allowable) is obtained at the timing of full closing. After the EGR valve 11 is fully closed (t> tb), the throttle valve 6 is controlled to the target throttle opening at the desired valve closing speed.

  In the first embodiment, the deceleration throttle valve cooperative control is performed in S14, and the deceleration throttle valve normal control is performed in S15. That is, the predetermined conditions at the time of deceleration when the deceleration throttle valve cooperative control is performed correspond to S2, S6, and S13 of FIG. 5 in the first embodiment described above. That is, in the first embodiment, the predetermined conditions at the time of deceleration at which the deceleration throttle cooperative control is permitted are that the EGR valve opening is larger than “0”, the allowable collector pressure is larger than the target collector pressure, The throttle valve response time t (th / c) is longer than the EGR valve response time t (egr).

  Also, the control of the EGR valve 11, the control of the throttle valve 6, the calculation of the target throttle valve opening, the calculation of the second target throttle valve opening when there is no EGR, the calculation of the allowable collector pressure, the calculation of the target collector pressure, This is implemented in the control flow shown in the flowchart described above. In other words. EGR valve control means, throttle valve control means, deceleration determination means, target throttle valve opening calculation means, second target throttle valve opening calculation means, allowable intake negative pressure calculation means, target intake negative pressure calculation means are included in the ECU 13 It is what

  In such a first embodiment, as shown in FIG. 9, when the EGR valve 11 is closed, the amount of fresh air in the amount of intake air does not increase, so the amount of fresh air increases during deceleration and torque increases. Can be prevented and drivability can be improved. In particular, when the EGR valve 11 is fully closed, the throttle valve is controlled to TVO (allowable), which is the throttle valve opening corresponding to the allowable collector pressure, so that the EGR amount does not overshoot as much as possible. The throttle valve 6 can be closed, and the collector pressure is increased to the maximum (development of negative pressure) within the range where the EGR amount does not overshoot with the closing of the EGR valve 11, and the amount of fresh air is reduced. Therefore, it is possible to realize improvement in drivability with an increase in the feeling of deceleration.

  Further, when there is no significant difference between the EGR valve response time t (egr) and the throttle valve response time t (th / c), that is, the response speed t (th / c) of the throttle valve 6 and the response speed t of the EGR valve 11. When there is no large difference in (egr), the amount of EGR gas in the intake air amount during deceleration does not increase rapidly.

  Therefore, when there is no significant difference between the EGR valve response time t (egr) and the throttle valve response time t (th / c), the closing speed of the throttle valve 6 is controlled to the initial closing speed. Thus, the time until the throttle valve opening reaches the target valve opening can be made relatively short, and the drivability can be improved.

  Furthermore, when there is no significant difference between the allowable collector pressure and the target collector pressure, the EGR gas amount in the intake air amount does not increase rapidly during deceleration.

  Therefore, when there is no large difference between the allowable collector pressure and the target collector pressure, the throttle valve opening is controlled to the target valve opening by controlling the closing speed of the throttle valve 6 to the initial closing speed. Thus, the time until the operation can be made relatively short, and drivability can be improved.

  Next, a second embodiment of the present invention will be described. In the second embodiment, a part of the conditions for executing the deceleration throttle valve cooperative control is changed with respect to the first embodiment, and the contents of the deceleration throttle valve cooperative control are partially changed. Is.

  More specifically, in the second embodiment, the collector pressure immediately before it is determined to be in the deceleration state is not one of the conditions for executing the throttle valve cooperative control during deceleration that the allowable collector pressure is larger than the target collector pressure. One of the conditions for executing the throttle valve cooperative control during deceleration is that there is a deviation larger than a predetermined value set in advance between the control valve and the target collector pressure.

  As shown in FIG. 10, in the throttle valve cooperative control in the second embodiment, the opening degree of the throttle valve 6 when the EGR valve 11 is in the closed state is the intake air in the state during the deceleration. Control is performed so that the throttle valve opening is obtained when there is no EGR gas flowing back into the passage, and the subsequent throttle valve closing speed is controlled to the desired throttle valve closing speed.

  FIG. 11 is a flowchart showing a control flow when the vehicle is decelerated in the second embodiment.

  In step 31, the vehicle speed, the rotational speed of the internal combustion engine 1 and the return speed of the accelerator pedal are read, and deceleration determination is performed to determine whether or not the vehicle is in a predetermined deceleration state. Specifically, when the rotational speed of the internal combustion engine 1 is equal to or higher than a predetermined speed, the vehicle speed is equal to or higher than the predetermined vehicle speed, and the return speed of the accelerator pedal is equal to or higher than a predetermined value, it is determined that the engine is in a deceleration state and the process proceeds to S32. Otherwise, the current routine is terminated. In other words, in S31, the rotational speed of the internal combustion engine 1 is equal to or higher than the predetermined rotational speed, the vehicle speed is equal to or higher than the predetermined vehicle speed, and the closing speed of the throttle valve 6 is higher than the intended closing speed of the EGR valve 11. It is determined that the vehicle is in a deceleration state when the accelerator pedal is returned at such a speed. The return speed of the accelerator pedal is calculated in the ECU 13 using a signal from the accelerator opening sensor 16.

  In S32, it is determined whether or not the opening degree of the EGR valve 11 is larger than “0”, that is, whether or not the EGR valve 11 is in an open state, and if the EGR valve 11 is open. Proceeding to S33, if the EGR valve 11 is not open, that is, if the EGR valve 11 is already fully closed, the current routine is terminated.

  In S33, the accelerator opening APO (now) when it is determined that the vehicle is decelerating and the collector pressure when it is determined that the vehicle is decelerating are read, and the process proceeds to S34.

  In S34, the accelerator opening APO (now) read in S33 is used to calculate the target collector pressure as the target suction negative pressure with reference to the characteristic map shown in FIG. 6, and the process proceeds to S35. The target collector pressure becomes larger as the accelerator opening is larger, that is, a larger negative pressure.

  In S35, it is determined whether or not the collector pressure is higher than the target collector pressure. If the collector pressure is higher than the target collector pressure, the process proceeds to S36, and if the collector pressure is equal to or lower than the target collector pressure, the process proceeds to S42. In other words, in S35, it is determined whether or not the collector pressure deviates by a predetermined value or more from the target collector pressure. If the collector pressure deviates by a predetermined value or more, the process proceeds to S36. The process proceeds to S42.

  In S42, the EGR valve 11 and the throttle valve 6 are simultaneously closed at the intended valve closing speed, and the current routine is terminated. That is, in S42, the throttle valve normal control at the time of deceleration is performed in which the valve closing speed of the throttle valve 6 is closed at the desired valve closing speed.

  In S36, the intake air amount Qa, the throttle valve opening TVO (now), the EGR valve opening, and the engine speed Ne when it is determined that the vehicle is decelerating are read, and the process proceeds to S37. The intake air intake amount Qa is detected by the air flow meter 8.

  In S37, using Qa and Ne read in S36, TVO (egr-less) as the second target throttle valve opening, which is the target throttle valve opening when there is no EGR, is calculated, and the process proceeds to S38.

  In S38, the time t (egr) until the EGR valve 11 is fully closed is calculated using the following equation (4), and the process proceeds to S39. That is, in S38, the response time t (egr) that is the closing time of the EGR valve 11 required until the valve is fully closed from the opening state when it is determined that the vehicle is decelerating is calculated.

[Equation 4] t (egr) = EGR valve opening / EGR valve closing speed (4)
In the equation (4), the EGR valve closing speed is an intended valve closing speed of the EGR valve 11, that is, the maximum valve closing speed of the EGR valve 11, and is a constant value.

  In S39, the response time t (th / c) to the target opening of the throttle valve 6 when it is determined that the vehicle is decelerating is calculated using the following equation (5), and the process proceeds to S40.

[Expression 5] t (th / c) = (APO (determination before deceleration) −APO (target)) / ΔAPO (5)
In this equation (5), APO (determination value before deceleration) is the accelerator opening measured immediately before it is determined that the vehicle is decelerating. APO (target) is the target accelerator opening in the deceleration state, that is, the final accelerator opening in the deceleration state. ΔAPO is the change rate of the accelerator opening when it is determined that the vehicle is in a decelerating state.

  The APO (target) and ΔAPO are calculated in the ECU 13 based on a signal from the accelerator opening sensor 16.

  In S40, until the response time t (th / c) to the target opening of the throttle valve 6 when it is determined that the vehicle is in the deceleration state is fully closed when the EGR valve 11 is determined to be in the deceleration state. It is determined whether it is longer (longer) than the response time t (egr) of the time, and if it is longer, the process proceeds to S41, and if not, the process proceeds to S42. In other words, in S40, when it is determined that the vehicle is decelerating, the EGR valve response time t (egr) until the EGR valve 11 is fully closed at the intended valve closing speed, and the throttle valve 6 is The throttle valve response time t (th / c) until the target throttle valve opening is reached at the desired valve closing speed is calculated, and the EGR valve response time t (egr) and the throttle valve response time t (th / c) If there is no deviation larger than a predetermined value set in advance, the process proceeds to S42, and if not, the process proceeds to S41.

  In the second embodiment, the right side of the determination formula used in S40 is “0”, but if a safety margin is taken, a positive threshold value that is “0” or more is set to “0”. It is also possible to substitute for this right side. The target throttle valve opening is calculated in the ECU 13 using a signal from the accelerator opening sensor 16.

  In S41, as shown in FIG. 10, the EGR valve 11 is closed at the desired closing speed until it is fully closed, and further the throttle valve 6 is controlled to a speed slower than the intended throttle valve closing speed. As the valve 11 is closed, the amount of fresh air in the amount of intake air is prevented from increasing, and thereafter the throttle valve closing speed is controlled to the desired throttle valve closing speed to control the throttle valve 6 to the target throttle valve. Close to opening. In other words, in S41, TVO (egr-less), which is the target throttle valve opening when there is no EGR calculated in S37, is the valve opening of the throttle valve 6 when the EGR valve 11 is closed. Then, the throttle valve normal speed control for controlling the throttle valve closing speed thereafter to the desired throttle valve closing speed is performed.

  Furthermore, in S41, the throttle valve 6 and the EGR valve 11 are in the period from immediately after it is determined that the vehicle is decelerating (t = ta) until the EGR valve 11 is fully closed (t = tb). Control is performed at a constant valve closing speed such that TVO (allowable) is obtained at the timing of full closing. After the EGR valve 11 is fully closed (t> tb), the throttle valve 6 is controlled to the target throttle opening at the desired valve closing speed.

  In the second embodiment, the deceleration throttle valve cooperative control is performed in S41, and the deceleration throttle valve normal control is performed in S42. That is, the predetermined condition at the time of deceleration at which the deceleration throttle valve cooperative control is performed corresponds to S32, S35, and S40 in FIG. 11 in the second embodiment described above. That is, in the second embodiment, the predetermined conditions for deceleration at which the throttle valve cooperative control is permitted to be performed are that the EGR valve opening is greater than “0”, the collector pressure is greater than the target collector pressure, and This is a case where the throttle valve response time t (th / c) is longer than the EGR valve response time t (egr).

  Also in the second embodiment, as shown in FIG. 10, when the EGR valve 11 is closed, the amount of fresh air in the intake air amount does not increase, so the amount of fresh air increases and the torque increases during deceleration. Can be prevented and drivability can be improved.

  When there is no significant difference between the EGR valve response time t (egr) and the throttle valve response time t (th / c), the closing speed of the throttle valve 6 is controlled to the initial closing speed. Thus, the time until the throttle valve opening reaches the target valve opening can be made relatively short, and the drivability can be improved.

  When there is no significant difference between the collector pressure and the target collector pressure, the throttle valve opening is set to the target valve opening by controlling the closing speed of the throttle valve 6 to the initial closing speed. Can be made relatively short, and drivability can be improved.

  The present invention is not limited to the two embodiments described above. For example, in the first embodiment described above, “the allowable collector pressure is greater than the target collector pressure” is one of the predetermined conditions during deceleration at which the execution of the throttle valve cooperative control during deceleration is permitted. Instead of this, “the collector pressure is greater than the target collector pressure” can be set as one of the predetermined conditions during deceleration. That is, S6 in FIG. 5 can be replaced with S35 in FIG. In the second embodiment described above, “the collector pressure is greater than the target collector pressure” is one of the predetermined conditions at the time of deceleration at which the execution of the deceleration throttle valve cooperative control is permitted. Instead of this, “the allowable collector pressure is greater than the target collector pressure” can be one of the predetermined conditions during deceleration. That is, S35 in FIG. 11 can be replaced with S6 in FIG.

  In the deceleration throttle valve cooperative control in the first embodiment described above, the valve opening of the throttle valve 6 when the EGR valve 11 is in the closed state becomes the allowable suction negative pressure in the deceleration state. Instead of this, the throttle valve opening of the throttle valve 6 when the EGR valve 11 is closed by the throttle valve cooperative control during deceleration is the target throttle valve when there is no EGR. You may make it become TVO (egr-less) which is an opening degree. Moreover, in the throttle valve cooperative control at the time of deceleration in the second embodiment described above, the valve opening of the throttle valve 6 when the EGR valve 11 is closed is the TVO which is the target throttle valve opening when there is no EGR. (Egr-less) However, instead of this, by the throttle valve cooperative control during deceleration, the valve opening of the throttle valve 6 when the EGR valve 11 is in the closed state is The throttle valve opening may be an allowable suction negative pressure.

  The technical ideas of the present invention that can be grasped from the above-described embodiments will be listed together with their effects.

  (1) A control device for an internal combustion engine includes a throttle valve disposed in an intake passage, an EGR passage having one end connected to the intake passage on the downstream side of the throttle valve and the other end connected to an exhaust passage, An EGR valve that controls the flow rate of EGR gas that is disposed in the EGR passage and returns to the intake passage, EGR valve control means that controls the EGR valve, throttle valve control means that controls the throttle valve, and a vehicle that decelerates Deceleration determining means for determining whether or not the throttle valve is decelerating, and target throttle valve opening degree calculating means for calculating a target throttle valve opening degree when the throttle valve is decelerating. The EGR valve control means When the vehicle is decelerating, the EGR valve is closed to stop the recirculation of the EGR gas to the intake passage, and the throttle valve control means is provided when the vehicle decelerates under a predetermined condition. Throttle valve cooperative control during deceleration is performed, and the throttle valve cooperative control during deceleration controls the initial throttle valve closing speed to a speed slower than the intended throttle valve closing speed to close the EGR valve. Accordingly, the amount of fresh air in the intake air amount is prevented from increasing, and thereafter the throttle valve closing speed is controlled to the desired throttle valve closing speed to close the throttle valve to the target throttle valve opening. As a result, the amount of fresh air in the amount of intake air does not increase when the EGR valve is closed, so it is possible to prevent the amount of fresh air from increasing and the torque from increasing during deceleration, improving operability. Can be made.

  (2) In the control device for an internal combustion engine according to (1), the throttle valve includes means for detecting a valve opening degree of the throttle valve, and means for detecting a valve opening degree of the EGR valve. When the vehicle decelerates, the control means includes an EGR valve response time until the EGR valve is fully closed at a desired valve closing speed, and the target throttle valve opens at the desired valve closing speed. The throttle valve response time until the time is reached is calculated, and when there is no greater difference than a predetermined value between the EGR valve response time and the throttle valve response time, the throttle valve is closed. The normal throttle valve control during deceleration is performed to close the valve speed at the desired closing speed. When there is no significant difference between the EGR valve response time and the throttle valve response time, that is, when there is no large difference between the response speed of the throttle valve and the response speed of the EGR valve, the EGR gas amount occupying the intake air amount during deceleration is There is no rapid increase. As a result, when there is no significant difference between the EGR valve response time and the throttle valve response time, the throttle valve opening speed is controlled to the initial valve closing speed so that the throttle valve opening degree is set as the target. The time until the valve opening is made can be relatively shortened, and drivability can be improved.

  (3) In the control apparatus for an internal combustion engine according to (1) or (2), a second target throttle valve opening calculation for calculating a target throttle valve opening when there is no amount of EGR gas recirculating to the intake passage. Specifically, the throttle valve cooperative control at the time of deceleration includes the EGR in which the valve opening of the throttle valve when the EGR valve is closed returns to the intake passage in the state of deceleration. The throttle valve opening is controlled so that there is no gas, and then the throttle valve closing speed is controlled to the desired throttle valve closing speed to close the throttle valve to the target throttle valve opening. To work.

  (4) The control apparatus for an internal combustion engine according to (1) or (2), further including an allowable intake negative pressure calculating means for calculating an allowable intake negative pressure capable of operating the internal combustion engine during deceleration, and a throttle during deceleration In the coordinated control of the valve, the valve opening of the throttle valve when the EGR valve is in the closed state is controlled so as to become the throttle valve opening that becomes the allowable suction negative pressure in the state of deceleration. The throttle valve closing speed is controlled to the desired throttle valve closing speed, and the throttle valve is operated in the valve closing direction to the target throttle valve opening. As a result, when the EGR valve is in a closed state, the throttle valve can be closed as much as possible within a range where the EGR amount does not overshoot, and within a range where the EGR amount does not overshoot as the EGR valve 11 is closed. Since the collector pressure is increased as much as possible (development of negative pressure) and the amount of fresh air is reduced, it is possible to realize improved drivability with an increase in the feeling of deceleration.

  (5) In the control device for an internal combustion engine according to any one of (1) to (4), an accelerator opening degree detecting means for detecting an amount of depression of an accelerator pedal, and an intake passage on the downstream side of the throttle valve. A pressure detecting means for detecting a suction negative pressure, a target suction negative pressure calculating means for calculating a target suction negative pressure from the depression amount of the accelerator pedal, and a permissible suction negative pressure capable of operating the internal combustion engine during deceleration A negative suction pressure calculating means, and when the allowable negative suction pressure deviates from the target negative suction pressure by a predetermined value or more during deceleration, the throttle valve cooperative control during deceleration To implement. If there is no significant difference between the allowable suction negative pressure and the target suction negative pressure, the amount of EGR gas that occupies the amount of intake air during deceleration does not increase rapidly. As a result, when there is no significant difference between the allowable suction negative pressure and the target suction negative pressure, the throttle valve opening speed is controlled by controlling the throttle valve closing speed to the initial closing speed. The time until the valve opening is made can be made relatively short, and drivability can be improved.

  (6) In the control device for an internal combustion engine according to any one of (1) to (4), an accelerator opening degree detecting unit that detects an amount of depression of an accelerator pedal, and an intake passage on a downstream side of the throttle valve A pressure detection means for detecting a suction negative pressure; and a target suction negative pressure calculation means for calculating a target suction negative pressure from a depression amount of the accelerator pedal. The suction negative pressure detected by the pressure detection means during deceleration However, when it deviates more than the predetermined value preset with respect to the target suction negative pressure, the deceleration throttle valve cooperative control is performed. If there is no significant difference between the intake negative pressure and the target intake negative pressure, the EGR gas amount in the intake air amount does not increase rapidly during deceleration. As a result, when there is no significant difference between the suction negative pressure and the target suction negative pressure, the throttle valve opening degree is controlled by controlling the throttle valve closing speed to the initial closing speed. The time until the opening is set can be made relatively short, and drivability can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed typically the whole structure of the in-line 4 cylinder internal combustion engine to which this invention was applied. The timing chart which shows the change of the various parameters in a reference example. Explanatory drawing which shows the correlation of the collector pressure and EGR amount at the time of fully closing a throttle valve and an EGR valve from a steady state. Explanatory drawing which showed typically the variation | change_quantity of the valve opening degree of a throttle valve so that it may become below a misfire limit value even if EGR amount overshoots. The flowchart which shows the flow of control at the time of the deceleration of the vehicle in 2nd Embodiment of this invention. A characteristic map used to calculate the target collector pressure. A characteristic map used to calculate the allowable collector pressure. A characteristic map used to calculate TVO (allowance). The timing chart which shows the change of the various parameters in 1st Embodiment. The timing chart which shows the change of the various parameters in 2nd Embodiment. The flowchart which shows the flow of control at the time of the deceleration of the vehicle in 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Intake passage 3 ... Branch passage part 4 ... Collector part 5 ... Pressure sensor 6 ... Throttle valve 7 ... Throttle valve opening sensor 8 ... Air flow meter 9 ... Exhaust passage 10 ... EGR passage 11 ... EGR valve 12 ... EGR valve opening sensor 13 ... ECU
14 ... Vehicle speed sensor 15 ... Engine speed sensor 16 ... Accelerator opening sensor

Claims (6)

A throttle valve arranged in the intake passage;
An EGR passage having one end connected to the intake passage on the downstream side of the throttle valve and the other end connected to an exhaust passage;
An EGR valve that controls the flow rate of EGR gas that is disposed in the EGR passage and recirculates to the intake passage;
EGR valve control means for controlling the EGR valve;
Throttle valve control means for controlling the throttle valve;
Deceleration determination means for determining whether the vehicle is decelerating;
A target throttle valve opening calculating means for calculating a target throttle valve opening at the time of deceleration of the throttle valve,
The EGR valve control means closes the EGR valve to stop the recirculation of the EGR gas to the intake passage when the vehicle decelerates,
When the vehicle is decelerating under a predetermined condition, the throttle valve control means performs a throttle valve cooperative control during deceleration,
In the deceleration throttle valve cooperative control, the initial throttle valve closing speed is controlled to a speed slower than the intended throttle valve closing speed, and the amount of fresh air occupying the intake air amount as the EGR valve is closed is reduced. A control apparatus for an internal combustion engine, wherein the control is performed so that the throttle valve closing speed is not increased and the throttle valve closing speed is controlled to a desired throttle valve closing speed to close the throttle valve to a target throttle valve opening. Means for detecting the valve opening of the throttle valve; and means for detecting the valve opening of the EGR valve;
The throttle valve control means is configured such that when the vehicle decelerates, the EGR valve response time until the EGR valve is fully closed at a desired closing speed, and the throttle valve is set at a target closing speed. When the throttle valve response time until the throttle valve opening is reached is calculated, and there is no deviation greater than a predetermined value between the EGR valve response time and the throttle valve response time, the throttle valve response time 2. The control apparatus for an internal combustion engine according to claim 1, wherein a throttle valve normal control for decelerating is performed to close the valve closing speed at an intended valve closing speed. A second target throttle valve opening calculating means for calculating a target throttle valve opening when there is no EGR gas amount recirculating to the intake passage;
The throttle valve cooperative control at the time of deceleration is that the throttle valve opening when the EGR valve is closed is the throttle valve opening when there is no EGR gas amount recirculating to the intake passage in the deceleration state. And controlling the subsequent throttle valve closing speed to a desired throttle valve closing speed to operate the throttle valve in the valve closing direction to a target throttle valve opening degree. The control apparatus for an internal combustion engine according to 1 or 2. An allowable intake negative pressure calculating means for calculating an allowable intake negative pressure capable of operating the internal combustion engine during deceleration;
The throttle valve cooperative control during deceleration is controlled so that the valve opening of the throttle valve when the EGR valve is in a closed state is the throttle valve opening that is an allowable suction negative pressure in the state during deceleration. 3. The throttle valve closing speed thereafter is controlled to an intended throttle valve closing speed, and the throttle valve is operated in the valve closing direction to the target throttle valve opening degree. Control device for internal combustion engine. An accelerator opening detecting means for detecting an accelerator pedal depression amount;
Pressure detecting means for detecting a negative suction pressure in the intake passage on the downstream side of the throttle valve;
A target suction negative pressure calculating means for calculating a target suction negative pressure from a depression amount of the accelerator pedal;
An allowable intake negative pressure calculating means for calculating an allowable intake negative pressure capable of operating the internal combustion engine during deceleration,
2. The deceleration throttle valve cooperative control is performed when the allowable suction negative pressure deviates from the target suction negative pressure by a predetermined value or more during deceleration. The control apparatus of the internal combustion engine in any one of -4. An accelerator opening detecting means for detecting an accelerator pedal depression amount;
Pressure detecting means for detecting a negative suction pressure in the intake passage on the downstream side of the throttle valve;
A target suction negative pressure calculating means for calculating a target suction negative pressure from a depression amount of the accelerator pedal,
When the negative suction pressure detected by the pressure detection means deviates more than a predetermined value with respect to the target suction negative pressure during deceleration, the throttle valve cooperative control during deceleration is performed. The control apparatus for an internal combustion engine according to any one of claims 1 to 4, wherein

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