JP2008025499A - Control unit of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control unit of an internal combustion engine capable of improving controllability of a switching valve for controlling supply of exhaust gas to an HC adsorption section by performing learning in consideration of characteristics of a driver and a type of vehicle. <P>SOLUTION: The control unit of the internal combustion engine controls the internal combustion engine having the switching valve for selectively switching a passage in which exhaust gas flows to either a first passage provided with the HC adsorption section or a second passage bypassing the HC adsorption section. A switching valve control means performs control of forcibly opening the switching valve according to an operation state. A learning means sets through learning a valve closing prohibition time in which the switching valve is kept open and is prohibited from closing after the switching valve is opened by the switching valve control means. The optimum valve closing prohibition time according to the characteristics of a driver and a type of vehicle can be thus set and the controllability of the switching valve or the like can be improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine that controls an internal combustion engine that supplies exhaust gas to an HC adsorption unit by switching an exhaust passage by a switching valve.

  Conventionally, a switching valve is provided so that the exhaust gas flows through either a passage provided with an HC adsorption portion (HC adsorption cylinder) for adsorbing HC (hydrocarbon) in the exhaust gas or a passage bypassing the HC adsorption portion. There is known an apparatus that performs control using the. For example, in Patent Document 1, in an exhaust passage switching device that switches an exhaust passage using a switching valve that is driven by a negative pressure generated in an intake passage, the switching valve is driven when the opening of the throttle valve is a predetermined value or less. The technology to do is described. Patent Document 2 describes a technique for controlling the opening degree of the switching valve described above according to the balance between HC adsorption and increased pressure loss during acceleration at low temperature acceleration. In addition, Patent Document 3 describes a technique related to the present invention.

JP 2001-295633 A Japanese Patent Laid-Open No. 4-17710 JP 2000-240472 A

  By the way, in the case of a switching valve driven using negative pressure, it is basically necessary to wait until the negative pressure is secured. Thus, the time required until the negative pressure is ensured varies depending on characteristics such as the driver and the vehicle type. However, the techniques described in Patent Documents 1 to 3 do not take into account characteristics such as the driver and the vehicle type, and thus wait for an unnecessarily long time, resulting in poor controllability for the switching valve and the like. There was a case.

  The present invention has been made to solve such problems, and the object of the present invention is to provide exhaust gas to the HC adsorbing portion by performing learning in consideration of characteristics such as a driver and a vehicle type. Another object of the present invention is to provide a control device for an internal combustion engine that can improve the controllability of a switching valve that controls the supply of the engine.

  In one aspect of the present invention, a switching valve that selectively switches a passage through which exhaust gas flows to one of a first passage provided with an HC adsorption portion and a second passage that bypasses the HC adsorption portion. A control device for an internal combustion engine that controls an internal combustion engine having a switching valve, a switching valve control means that performs control to forcibly open the switching valve based on an operating state, and the switching valve Learning means for setting, by learning, a valve closing prohibition time during which the switching valve is kept open and the valve closing is prohibited after the switching valve is opened by the control means.

  The control apparatus for an internal combustion engine described above may be configured such that the exhaust gas flows in one of the first passage provided with the HC adsorption portion and the second passage that bypasses the HC adsorption portion based on the operating state. Control is performed on the internal combustion engine having a switching valve that selectively switches to. The switching valve control means performs control for forcibly opening the switching valve closed for forced purge control or the like based on the operating state. Further, the learning means learns the valve closing prohibition time during which the switching valve is kept open after the switching valve is opened by the switching valve control means to prohibit the closing of the valve based on the operating condition. Specifically, the valve closing prohibition time is set by learning based on the characteristics of the driver and the vehicle type. Thereby, the optimal valve closing prohibition time can be set according to the characteristics for each driver and vehicle type. Therefore, it is possible to absorb the variation in the number of times of operation of the switching valve or the like due to the usage method of the vehicle or the habits of individual drivers, and improve the robustness and reliability. Therefore, according to the control device for an internal combustion engine, it is possible to improve the controllability of the control for the switching valve or the like. Further, the control for closing the switching valve for forced purge or the like can be completed in a shorter time.

  In one aspect of the control apparatus for an internal combustion engine, after the switching valve is opened by the switching valve control means, at least until the valve closing prohibition time learned by the learning means elapses. And a means for prohibiting the closing of the valve.

  In this aspect, the control device for the internal combustion engine prohibits the switching valve from opening to closing at least until the valve closing prohibition time has elapsed after the switching valve is opened. In other words, the switching valve closing is delayed (delayed) until at least the time during which the switching valve can be reliably operated has elapsed. As a result, it is possible to suppress hunting of the actual valve behavior and an excessive increase in the number of operations, etc., and prevent occurrence of problems such as deterioration of device component performance, deterioration of controllability, and deterioration of drivability. It becomes possible.

  In another aspect of the control apparatus for an internal combustion engine described above, the learning means takes a time required after the condition for opening the switching valve is satisfied until the condition for opening the valve is satisfied next. Based on the above, the valve closing prohibition time is learned. In this case, for example, learning of the valve closing prohibition time is performed based on the intake air amount corresponding to the accelerator operation by the driver. Accordingly, the valve closing prohibition time can be appropriately set according to the characteristics of each driver and vehicle type. That is, it is possible to effectively absorb the variation in the number of times of operation of the switching valve or the like due to the vehicle usage method or the habits of individual drivers.

  Preferably, in the above control device for an internal combustion engine, the learning means takes a time required from when the condition for opening the switching valve is satisfied until the condition for opening the valve is satisfied next, When it is within the predetermined range, the valve closing prohibition time can be updated with the required time.

  More preferably, the switching valve control means is provided when the intake air amount becomes a predetermined value or more when the switching valve is closed to purge the HC adsorbed by the HC adsorption unit. Thus, it is possible to perform control to forcibly open the switching valve.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[overall structure]
FIG. 1 is a schematic diagram illustrating an overall configuration of a vehicle 100 to which the control device for an internal combustion engine according to the present embodiment is applied. In FIG. 1, solid arrows indicate an example of gas flow, and broken arrows indicate input / output of signals.

  The vehicle 100 mainly includes an air flow meter 1, a throttle valve 2, an intake passage 3, a surge tank 4, an engine (internal combustion engine) 5, an exhaust passage 6, a first catalyst 7, and an HC adsorption device 8. A second catalyst 9, a switching valve 10, a negative pressure supply passage 15, a check valve 16, a three-way VSV (Vacuum Switching Valve) 19, a diaphragm mechanism 20, a motor generator 21, and an ECU (Engine Control Unit). 50).

  Intake air introduced from outside passes through the intake passage 3, and the air flow meter 1 detects the flow rate of intake air (intake air amount) passing through the intake passage 3. In this case, the intake air amount detected by the air flow meter 1 is supplied to the ECU 50. The throttle valve 2 adjusts the flow rate of the intake air that passes through the intake passage 3, and the intake air that has passed through the throttle valve 2 is temporarily stored in the surge tank 4. The intake air introduced into the surge tank 4 is supplied to the engine 5.

  The engine 5 includes a plurality of cylinders, and generates power by causing an air-fuel mixture obtained by mixing the supplied intake air and fuel to explode. The engine 5 is controlled by a control signal supplied from the ECU 50 to control the fuel injection amount and the ignition timing. The engine 5 is constituted by, for example, a gasoline engine or a diesel engine.

  The exhaust gas discharged from the engine 5 flows through the exhaust passage 6. In the exhaust passage 6, a first catalyst 7, an HC adsorption device 8, and a second catalyst 9 are provided in order from the upstream side to the downstream side. The first catalyst 7 and the second catalyst 9 are constituted by a three-way catalyst or the like, and purify NOx and SOx in the exhaust gas.

  The HC adsorption device 8 is configured in a cylindrical shape, and a first passage 61 and a second passage 62 are formed. A switching valve 10 is disposed inside the HC adsorption device 8. In the first passage 61, an HC adsorbing portion 11 (hatched portion in FIG. 1) having a function of adsorbing HC (hydrocarbon) as an unburned component contained in the exhaust gas is disposed. The switching valve 10 is a valve that selectively switches the flow path of the exhaust gas so that the exhaust gas flows through either the first passage 61 or the second passage 62 that bypasses the HC adsorption unit 11. Specifically, when the switching valve 10 is closed, the exhaust gas flows only into the first passage 61, and when the switching valve 10 is open, the exhaust gas flows into the first passage 61 and the second passage 62. Flowing. The switching valve 10 is controlled to be opened and closed by a diaphragm mechanism 20 described later.

  Here, the basic concept about opening and closing of the switching valve 10 will be described. At the time of cold start or the like, both the first catalyst 7 and the second catalyst 9 cannot effectively purify the HC in the exhaust gas, so that the HC adsorbing portion 11 adsorbs the HC in the first passage 61. The switching valve 10 is set to be closed so that the exhaust gas flows. Further, the HC adsorption unit 11 has a characteristic of starting to release adsorbed HC to the outside when the temperature of the supplied exhaust gas becomes high. Therefore, when the temperature of the exhaust gas reaches a temperature at which the adsorbed HC is purged (in this case, the second catalyst 9 is generally active), the exhaust gas flows through the second passage 62. Thus, the switching valve 10 is switched from closed to open. Further, when there is a request to completely purge the HC adsorbed on the HC adsorbing unit 11 during a warm time or the like, by setting the switching valve 10 to be closed and supplying exhaust gas to the HC adsorbing unit 11, Purge (forced purge) is executed.

  Next, a mechanism for controlling the opening / closing of the switching valve 10 will be described. The switching valve 10 is controlled to be opened and closed by a diaphragm mechanism 20. Specifically, the operation of the diaphragm mechanism 20 is controlled by the pressure of the gas supplied through the negative pressure supply passage 15.

  The negative pressure supply passage 15 is a passage through which the surge tank 4 and the diaphragm mechanism 20 are electrically connected. The negative pressure supply passage 15 is provided with a check valve 16 and a three-way VSV 19 in order from the surge tank 4 side to the diaphragm mechanism 20 side. The check valve 16 is a one-way valve that allows only a gas flow from the negative pressure supply passage 15 side toward the surge tank 4 side. The three-way VSV 19 is constituted by a so-called three-way valve, and has an opening connected to the check valve 16 side, an opening connected to the diaphragm mechanism 20 side, and an opening opened to the atmosphere. The three-way VSV 19 is controlled by a control signal supplied from the ECU 50. Specifically, when the three-way VSV 19 is turned on, negative pressure is introduced into the diaphragm mechanism 20, and when the three-way VSV 19 is turned off, atmospheric pressure is introduced into the diaphragm mechanism 20 instead of negative pressure. Is done.

  The diaphragm mechanism 20 controls opening and closing of the switching valve 10 according to the pressure of the supplied gas. Specifically, the inside of the diaphragm mechanism 20 is maintained at atmospheric pressure, and operates according to the difference between the pressure of the supplied gas and the atmospheric pressure inside. Specifically, the diaphragm mechanism 20 operates so that the switching valve 10 is opened when the atmospheric pressure is introduced (when the three-way VSV 19 is turned off), and the negative pressure that is lower than the atmospheric pressure. Is introduced (when the three-way VSV 19 is turned on), the switching valve 10 is operated to be closed.

  The motor generator 21 is configured to function mainly as an electric motor that assists the output of the engine 5. The motor generator 21 is connected to the engine 5 via a planetary gear or the like (not shown).

  The ECU 50 includes a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like (not shown). The ECU 50 controls the vehicle 100 based on detection signals (for example, intake air amount acquired from the air flow meter 1) supplied from various sensors. Specifically, the ECU 50 controls the opening and closing of the switching valve 10 by controlling the pressure of the gas supplied to the diaphragm mechanism 20 mainly by controlling the on / off of the three-way VSV 19. The ECU 50 functions as a control device for the internal combustion engine in the present invention. Specifically, the ECU 50 operates as a switching valve control unit and a learning unit.

[Basic concept of control]
Next, the basic concept of control according to the present embodiment will be described. In the present embodiment, the ECU 50 performs control to open the switching valve 10 that is being closed for purging HC or the like when the intake air amount exceeds a predetermined value, and in this way. After the switching valve 10 is opened, the valve closing prohibition time that should be prohibited from being closed while the switching valve 10 is kept open is learned in accordance with the operating conditions and the like. Specifically, the valve closing prohibition time is acquired by learning based on the characteristics of the driver and determined. Then, the ECU 50 permits the switching valve 10 to be closed from being opened when the valve closing prohibition time has elapsed after the switching valve 10 is opened. It should be noted that the “valve closing time” generally corresponds to the time required until the negative pressure necessary for operating the switching valve 10 is secured.
Hereinafter, the reason why the above-described control is performed will be specifically described. As described above, the control for closing the switching valve 10 in order to forcibly purge the HC adsorbed by the HC adsorption unit 11 (that is, the control for flowing the exhaust gas through the HC adsorption unit 11) is performed. Thus, when the condition for opening the switching valve 10 (hereinafter also referred to as “forced valve opening condition”) is satisfied in the situation where the switching valve 10 is kept closed, the switching valve 10 is opened from the closed state. To control. Specifically, the forced valve opening condition is satisfied when the intake air amount becomes a predetermined value or more, and the intake air amount becomes a predetermined value or more when the vehicle 100 accelerates. Therefore, when the forced valve opening condition is satisfied, the switching valve 10 is controlled from the closed state to the open state in order to secure the drivability during acceleration and the power performance of the vehicle 100 by suppressing an increase in the back pressure. .

  In the present embodiment, after the switching valve 10 is opened as described above, the switching valve 10 is prohibited from opening to closing until at least the valve closing prohibition time has elapsed. In other words, in this embodiment, the closing of the switching valve 10 is delayed (delayed) until at least the time during which the switching valve 10 can be reliably operated has elapsed. Specifically, the switching valve 10 is closed from the open state only when the valve closing prohibition time has elapsed after the switching valve 10 is opened and the intake air amount becomes less than a predetermined value. The reason for delaying the closing of the switching valve 10 in this way is that the stroke amount (actual valve behavior) in the diaphragm mechanism 20 that substantially opens and closes the switching valve 10 is hunted as open → closed → open →. It is for suppressing that it will be. If such hunting occurs, the performance of the parts of the device will deteriorate, the time that the valve will remain in the half-open state will become longer, the controllability will deteriorate, and power fluctuations and exhaust will be caused by changes in the back pressure. A change in sound may occur and drivability may deteriorate. Therefore, in this embodiment, in order to prevent the occurrence of such a problem, after the switching valve 10 is opened, the switching valve 10 is closed from the open state until at least the valve closing prohibition time has elapsed. Is prohibited.

  Furthermore, in this embodiment, the valve closing prohibition time described above is learned based on the characteristics of the driver and the vehicle type. Specifically, learning of the valve closing prohibition time is performed based on the time required until the forced valve opening condition is satisfied after the forced valve opening condition is satisfied. Specifically, learning is performed based on the time from when the intake air amount becomes equal to or greater than a predetermined value until the next time the intake air amount becomes equal to or greater than the predetermined value. That is, the valve closing prohibition time is learned based on the accelerator operation by the driver. Thereby, the valve closing prohibition time can be set according to the characteristics of each driver and vehicle type. Therefore, it is possible to absorb variations in the number of operations of the switching valve 10 and the like due to the usage method (usage environment, travel pattern, etc.) of the vehicle 100 and the habits of individual drivers, and to improve robustness and reliability. Further, the control for closing the switching valve 10 for forced purge or the like can be completed in a shorter time.

  Here, the outline of the control according to the present embodiment will be specifically described with reference to FIGS. 2 and 3. In FIGS. 2 and 3, the situation at the time of stepwise acceleration is shown as an example.

  FIG. 2 is a diagram for explaining the control according to the comparative example. In the comparative example, since the determination using the valve closing prohibition time is not performed, the switching valve 10 is opened each time the forced valve opening condition is satisfied (every time the intake air amount exceeds a predetermined value). Control.

  2 (a) shows the vehicle speed, FIG. 2 (b) shows the rotational speed of the engine 5, FIG. 2 (c) shows the intake air amount, and FIG. 2 (d) shows the three-way VSV19. 2 (e) shows the stroke amount (hereinafter referred to as "diaphragm stroke amount") in the diaphragm mechanism 20, and FIGS. 2 (a) to 2 (e) are respectively horizontal. Time is shown on the axis.

  In this case, it is assumed that the three-way VSV 19 is set to ON (that is, the switching valve 10 is closed) and the HC is forcibly purged before time t1a. In such a situation, it is assumed that as a result of the accelerator pedal being depressed by the driver, the intake air amount is increased, and the rotational speed and the vehicle speed of the engine 5 are increased. Thus, the intake air amount becomes equal to or greater than the predetermined value G at time t1a. In this case, the three-way VSV 19 is controlled to be turned off in order to open the switching valve 10, and the diaphragm stroke amount gradually increases (the valve is gradually opened). From this, it can be seen that there is a delay in the opening and closing speed of the valve by the stroke (actual operation) of the diaphragm mechanism 20 with respect to the on / off switching of the three-way VSV 19. Specifically, after the three-way VSV 19 is turned off at time t1a, the diaphragm mechanism 20 is finally completely opened around time t1b after a certain amount of time has passed.

  Thereafter, since the intake air amount becomes less than the predetermined value G at time t1b, the three-way VSV 19 is controlled from OFF to ON. Thereby, the diaphragm stroke amount gradually decreases (the valve is gradually closed). At time t1c, the intake air amount again becomes equal to or greater than the predetermined value G, so that the three-way VSV 19 is controlled from on to off, and the diaphragm stroke amount gradually increases. Thereafter, at time t1d, the intake air amount becomes less than the predetermined value G and settles, so that the three-way VSV 19 is switched from off to on and is kept on as it is.

  When the control according to the comparative example is performed when there is a stepwise acceleration as shown in FIG. 2 (that is, when the control of the three-way VS 19 or the like is performed based only on the intake air amount), the operation of the diaphragm mechanism 20 The number of times increases, and the diaphragm stroke amount (actual valve behavior) hunts from open to closed to open to. When hunting occurs in this way, the performance of the parts of the device deteriorates, the time during which the valve in the diaphragm mechanism 20 is in a half-open state becomes longer, the controllability deteriorates, or the power is increased due to a change in back pressure. There is a possibility that drivability deteriorates due to fluctuations and exhaust sound changes.

  Next, an outline of control performed by the ECU 50 according to the present embodiment will be described with reference to FIG. 3 (a) shows the vehicle speed, FIG. 3 (b) shows the rotational speed of the engine 5, FIG. 3 (c) shows the intake air amount, and FIG. 3 (d) shows the three-way VSV 19. 3 (e) shows the amount of diaphragm stroke, and FIG. 3 (f) shows the time during which the switching valve 10 is kept open (hereinafter referred to as “valve opening time counter value”). 3), and FIGS. 3A to 3E each show time on the horizontal axis. The valve opening time counter value is counted after the forced valve opening condition is satisfied and the three-way VSV 19 is set from on to off when the switching valve 10 is closed for forced purge by the ECU 50. . Further, the ECU 50 resets the valve opening time counter value to “0” when the intake air amount is switched from a value less than the predetermined value to a value equal to or larger than the predetermined value during counting of the valve opening time counter value. And

  Also in this case, it is assumed that the three-way VSV 19 is set to ON (that is, the switching valve 10 is closed) and the HC is forcibly purged before time t2a. In such a situation, it is assumed that as a result of the accelerator pedal being depressed by the driver, the intake air amount is increased, and the rotational speed and the vehicle speed of the engine 5 are increased. Thus, the intake air amount becomes equal to or greater than the predetermined value G at time t2a. In this case, the ECU 50 controls the three-way VSV 19 to be turned off in order to open the switching valve 10. As a result, the diaphragm stroke amount gradually increases (the diaphragm mechanism 20 is gradually opened). Further, at time t2a, counting of the valve opening time counter value is started. Thereafter, the intake air amount becomes less than the predetermined value G at time t2b, but the ECU 50 keeps the three-way VSV 19 off because the valve opening time counter value is less than the valve closing prohibition time T. Therefore, the diaphragm stroke amount is kept constant (diaphragm mechanism 20 is kept open).

  Thereafter, the intake air amount becomes equal to or greater than the predetermined value G again at time t2c. At time t3 after time t2c, the valve opening time counter value becomes equal to or longer than the valve closing prohibition time T. In this case, since the intake air amount is equal to or greater than the predetermined value G, the ECU 50 keeps the three-way VSV 19 off and resets the valve opening time counter value to “0”.

  Thereafter, at time t2d, the intake air amount becomes less than the predetermined value G, but since the valve opening time counter value is less than the valve closing prohibition time T, the ECU 50 keeps the three-way VSV 19 off. At time t2e, since the intake air amount is less than the predetermined value G and the valve opening time counter value is the valve closing prohibition time T, the ECU 50 switches the three-way VSV 19 from OFF to ON. As a result, the diaphragm stroke amount gradually decreases (the diaphragm mechanism 20 is gradually closed).

  As described above, according to the control according to the present embodiment, even when there is a stepwise acceleration as shown in FIG. 3, hunting of the stroke amount (actual valve behavior) in the diaphragm mechanism 20 and the extreme number of operations are performed. An increase or the like can be suppressed. As a result, it is possible to prevent the occurrence of problems due to the hunting of the diaphragm mechanism 20 as described above.

[Learning control]
Next, a method for learning the valve closing prohibition time will be described. In this embodiment, the valve closing prohibition time is learned based on driving by the driver. Specifically, the valve closing prohibition time is learned based on the change in the intake air amount corresponding to the accelerator operation by the driver, and the valve closing prohibition time is determined. Specifically, learning of the valve closing prohibition time is performed based on the time required from when the forced valve opening condition (the intake air amount is equal to or greater than a predetermined value) to the next time when the forced valve opening condition is satisfied. . That is, learning of the valve closing prohibition time based on the time from when the first forced valve opening condition is satisfied until the second forced valve opening condition is satisfied (hereinafter also simply referred to as “delay time counter value”). I do.

  Further, in this embodiment, learning of the valve closing prohibition time is performed based on whether or not the delay time counter value is within a predetermined range. Specifically, when the acquired delay time counter value is within the range defined by the upper and lower limit guards, the valve closing prohibition time is updated using the delay time counter value. On the other hand, when the delay time counter value is not within the range defined by the upper and lower limit guards, instead of using the delay time counter value, the upper limit value or the lower limit value defining the upper and lower limit guards is used to set the valve closing prohibition time. Update.

  FIG. 4 is a flowchart showing learning control according to the present embodiment. This process is executed by the ECU 50.

  The processing from step S101 to step S105 is performed to determine whether or not the forced valve opening condition is satisfied twice, and to obtain a delay time counter value.

  First, in step S101, the ECU 50 sets the valve closing prohibition time to an initial value. For example, the valve closing prohibition time is set to “5.0 (sec)”. Then, the process proceeds to step S102.

  In step S102, the ECU 50 determines whether or not the intake air amount is equal to or greater than a predetermined value based on the intake air amount acquired from the air flow meter 1. That is, the ECU 50 determines whether or not the first forced valve opening condition is satisfied. For example, it is determined whether or not the intake air amount is “50 (g / sec)” or more. If the intake air amount is greater than or equal to the predetermined value (step S102; Yes), the process proceeds to step S103. In this case, the first forced valve opening condition is satisfied. On the other hand, when the amount of intake air is less than the predetermined value (step S102; No), the process returns to step S102. That is, the determination in step S102 is repeated until the first forced valve opening condition is satisfied.

  In step S103, the ECU 50 starts counting the delay time counter because the first forced valve opening condition is satisfied. Then, the process proceeds to step S104. In step S104, it is determined whether the intake air amount is equal to or greater than a predetermined value. That is, the ECU 50 determines whether or not the second forced valve opening condition is satisfied. If the intake air amount is greater than or equal to the predetermined value (step S104; Yes), the process proceeds to step S105. In this case, since the second forced valve opening condition is satisfied, the count of the delay time counter is stopped. In step S105, the ECU 50 stores the obtained delay time counter value, and the process proceeds to step S106. On the other hand, when the amount of intake air is less than the predetermined value (step S104; No), the process returns to step S104. That is, the determination in step S104 is repeated until the second forced valve opening condition is satisfied. In this case, the delay time counter continues to count.

  The processing after step S105 is executed to learn the valve closing prohibition time using the delay time counter value. Specifically, the valve closing prohibition time is learned by making a determination using the upper and lower limit guards on the delay time counter value.

  In step S106, the ECU 50 determines whether or not the delay time counter value stored in the process of step S105 described above is less than or equal to the lower limit value of the upper and lower limit guards. For example, “3 (sec)” is used as the lower limit value, and it is determined whether or not the delay time counter value is “3 (sec)” or less.

  When the delay time counter value is less than or equal to the lower limit value (step S106; Yes), the process proceeds to step S107, and the ECU 50 substitutes the lower limit value for the valve closing prohibition time. That is, since the delay time counter value is not within the predetermined range, learning of the valve closing prohibition time is performed using the lower limit value of the upper and lower limit guards instead of learning using the delay time counter value. That is, the valve closing prohibition time is updated with the lower limit value of the upper and lower limit guards. For example, when the lower limit value is “3 (sec)”, the valve closing prohibition time is set to “3 (sec)”. When the above process ends, the process exits the flow.

  When the delay time counter value is larger than the lower limit value (step S106; No), the process proceeds to step S108. In step S108, the ECU 50 determines whether or not the delay time counter value is greater than or equal to the upper limit value of the upper / lower limit guard. For example, “10 (sec)” is used as the upper limit value, and it is determined whether or not the delay time counter value is “10 (sec)” or more.

  If the delay time counter value is greater than or equal to the upper limit value (step S108; Yes), the process proceeds to step S109, and the ECU 50 substitutes the upper limit value for the valve closing prohibition time. That is, since the delay time counter value is not within the predetermined range, learning of the valve closing prohibition time is performed using the upper limit value of the upper / lower limit guard instead of learning using the delay time counter value. That is, the valve closing prohibition time is updated with the upper limit value of the upper and lower limit guards. For example, when the upper limit value is “10 (sec)”, the valve closing prohibition time is set to “10 (sec)”. When the above process ends, the process exits the flow.

  On the other hand, when the delay time counter value is less than the upper limit value (step S108; No), the process proceeds to step S110. In step S110, the ECU 50 substitutes the delay time counter value for the valve closing prohibition time. In this case, since the delay time counter value is within a predetermined range, learning is performed using the delay time counter value. That is, the valve closing prohibition time is updated with the delay time counter value. For example, when the lower limit value is “3 (sec)”, the upper limit value is “10 (sec)”, and the delay time counter value is “6 (sec)”, the valve closing prohibition time is set to “6”. (Sec) ". When the above process ends, the process exits the flow.

  According to the learning control according to the present embodiment, the valve closing prohibition time can be set according to the characteristics of each driver and vehicle type. Therefore, it is possible to absorb the variation in the number of times of operation of the switching valve 10 and the like due to the usage method (usage environment, running pattern, etc.) of the vehicle 100 and the habits of individual drivers, and to improve the robustness and reliability. . Further, the control for closing the switching valve 10 for forced purge or the like can be completed in a shorter time.

[Switching valve control]
Next, a method for controlling the switching valve 10 will be described. In this embodiment, when the forced valve opening condition is satisfied during the forced purge (when the intake air amount becomes a predetermined value or more), the switching valve 10 is controlled from closed to open. Further, in the present embodiment, after the switching valve 10 is opened as described above, the switching valve 10 is prohibited from being opened to closed at least until the valve closing prohibition time has elapsed. In other words, the closing of the switching valve 10 is delayed (delayed) until at least the time during which the switching valve 10 can be reliably operated has elapsed.

  FIG. 5 is a flowchart showing the switching valve control according to the present embodiment. This process is repeatedly executed by the ECU 50 at a predetermined cycle.

  First, in step S201, the ECU 50 determines whether control for forced purge is being executed. That is, it is determined whether or not the control for closing the switching valve 10 for the forced purge is being executed (valve closing control is in progress). If the valve closing control is being performed (step S201; Yes), the process proceeds to step S202. If the valve closing control is not being performed (step S201; No), the process exits the flow.

  In step S202, the ECU 50 determines whether the intake air amount is equal to or greater than a predetermined value based on the intake air amount acquired from the air flow meter 1. Here, it is determined whether or not the switching valve 50 should be switched from closed to open. That is, it is determined whether the forced valve opening condition is satisfied. For example, it is determined whether or not the intake air amount is “50 (g / sec)” or more. If the intake air amount is greater than or equal to the predetermined value (step S202; Yes), the process proceeds to step S203. If the intake air amount is less than the predetermined value (step S202; No), the process exits the flow.

  In step S203, since the forced valve opening condition is satisfied, the ECU 50 sets the three-way VSV 19 from on to off in order to open the switching valve 10 from the closed state. In this case, since the vehicle 100 is accelerating or the like, the ECU 50 opens the switching valve 10 from the closed state to protect the components in the apparatus and to suppress the back pressure increase. Further, the ECU 50 starts counting the valve opening time counter. Then, the process proceeds to step S204. The valve opening time counter is counted as time elapses.

  In step S204, the ECU 50 determines whether or not the valve opening time counter value is equal to or longer than the valve closing prohibition time. In this case, the ECU 50 performs the determination using the valve closing prohibition time determined in the above-described learning control (see FIG. 4). If the valve opening time counter value is greater than or equal to the valve closing prohibition time (step S204; Yes), the process proceeds to step S206, and if the valve opening time counter value is less than the valve closing prohibition time (step S204; No), the process is performed. Advances to step S205.

  In step S205, since the valve opening time counter value is less than the valve closing prohibition time, the ECU 50 keeps the three-way VSV 19 off in order to keep the switching valve 10 open (in order to prohibit closing). Then, the process returns to step S204 to make a determination again. That is, the processes in steps S204 and S205 are repeatedly executed until the valve opening time counter value becomes equal to or longer than the valve closing prohibition time.

  In step S206, the ECU 50 determines whether or not the intake air amount is less than a predetermined value. In other words, it is determined whether the forced valve opening condition is not satisfied. That is, here, the valve opening time counter value is equal to or longer than the valve closing prohibition time, but the ECU 50 determines whether or not the switching valve 50 may be switched from open to closed. For example, when the vehicle 100 is accelerating (in this case, the intake air amount is equal to or greater than a predetermined value), the switching valve 50 should not be switched to a closed state in order to suppress an increase in back pressure. It can be said that there is.

  If the intake air amount is less than the predetermined value (step S206; Yes), the process proceeds to step S208. In this case, since the valve opening time counter value is not less than the valve closing prohibition time and the intake air amount is not less than the predetermined value, there is no problem even if the switching valve 50 is closed from the open state. The VSV 19 is set from off to on (step S208). That is, again, control for closing the switching valve 10 for forced purge (valve closing control) is executed. Then, the process exits the flow.

  On the other hand, when the amount of intake air is greater than or equal to the predetermined value (step S206; No), the process proceeds to step S207. In step S207, the ECU 50 resets the valve opening time counter value to “0”. In this case, until the time necessary for operating the switching valve 10 or the like has elapsed, the valve opening time counter value is reset to delay the closing of the switching valve 10. Then, the process proceeds to step S205. In step S205, the ECU 50 keeps the three-way VSV 19 off to keep the switching valve 10 open. Then, the process returns to step S204 to make a determination again. That is, the processes in steps S204 to S207 are repeatedly executed until the valve opening time counter value is equal to or greater than the valve closing prohibition time and the intake air amount is equal to or greater than the predetermined value.

  According to the switching valve control according to the present embodiment, since the switching valve 10 is prohibited from being opened to closed at least until the valve closing prohibition time elapses, hunting of the actual valve behavior in the diaphragm mechanism 20 or extreme operation is performed. An increase in the number of times can be suppressed.

1 is a schematic diagram illustrating an overall configuration of a vehicle to which a control device for an internal combustion engine according to an embodiment is applied. It is a figure for demonstrating the control which concerns on a comparative example. It is a figure for demonstrating the outline | summary of the control which concerns on this embodiment. It is a flowchart which shows the learning control which concerns on this embodiment. It is a flowchart which shows the switching valve control which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air flow meter 2 Throttle valve 3 Intake passage 5 Engine 7 1st catalyst 9 2nd catalyst 10 Switching valve 11 HC adsorption | suction part 19 Three-way VSV
20 Diaphragm mechanism 50 ECU
100 vehicles

Claims (5)

Control for an internal combustion engine having a switching valve for selectively switching a passage through which exhaust gas flows to either a first passage provided with an HC adsorbing portion or a second passage bypassing the HC adsorbing portion A control device for an internal combustion engine that performs
A switching valve control means for performing control to forcibly open the switching valve in the closed state based on an operating state;
Learning means for setting, by learning, a valve closing prohibition time for keeping the switching valve open and prohibiting the valve closing after the switching valve is opened by the switching valve control means. A control device for an internal combustion engine.   And further comprising means for prohibiting the switching valve from closing until at least the valve closing prohibition time learned by the learning means has elapsed after the switching valve is opened by the switching valve control means. The control apparatus for an internal combustion engine according to claim 1, wherein the control apparatus is an internal combustion engine.   The learning means learns the valve closing prohibition time based on the time required from when the condition for opening the switching valve is satisfied until the condition for opening the next valve is satisfied. The control device for an internal combustion engine according to claim 1, wherein the control device is an internal combustion engine.   The learning means is required if the time required from when the condition for opening the switching valve is satisfied to when the condition for opening the valve is satisfied is within a predetermined range. The control apparatus for an internal combustion engine according to claim 3, wherein the valve closing prohibition time is updated according to time.   The switching valve control means sets the switching valve when the intake air amount exceeds a predetermined value when the switching valve is closed to purge the HC adsorbed by the HC adsorption unit. The control device for an internal combustion engine according to any one of claims 1 to 4, wherein control for forcibly opening the valve is performed.

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