EGR valve control device

Abstract

To ensure restart capability of an internal combustion engine after a deceleration fuel cut.SOLUTION: An EGR valve control device 100 comprises: an internal combustion engine mounted on a vehicle, which includes a fuel injection section 1a and an EGR valve 9 that adjusts an exhaust recirculation amount; and a control section 10 that determines whether a fuel cut condition is met during deceleration, and controls the fuel injection section 1a and the EGR valve 9 so as to stop fuel supply from the fuel injection section 1a and cause the EGR valve 9 to perform a first predetermined number of opening and closing operations when the fuel cut condition is met. The control section 10 also controls the EGR valve 9 to perform a second predetermined number of opening and closing operations when an ignition switch of the vehicle is turned off. The first predetermined number of times is smaller than the second predetermined number of times.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an exhaust gas recirculation (EGR) valve control device that controls an EGR (Exhaust Gas Recirculation) valve of an internal combustion engine mounted on a vehicle. [Background technology]

[0002] In recent years, research and development has been conducted on vehicles equipped with EGR valves with the aim of contributing to the development of sustainable transportation systems by ensuring the integrity of the EGR valve and improving vehicle and traffic safety. Conventional EGR valve technologies include devices that open and close the EGR valve to remove foreign matter adhering to or trapped in the EGR valve (see, for example, Patent Documents 1 and 2). The device described in Patent Document 1 closes the EGR valve when the ignition switch is turned off and the internal combustion engine stops, and then fully opens it. The device described in Patent Document 2 controls the EGR valve so that the valve body repeatedly opens and closes between fully closed and a small opening when the internal combustion engine is decelerated and fuel is cut off. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-303307 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-249774 Summary of the Invention [Problem to be solved by the invention]

[0004] Immediately after a deceleration fuel cut of an internal combustion engine, the vehicle may go through an idle stop, etc., and the engine may need to be restarted, in which fuel supply to the internal combustion engine is resumed from a fuel-cut state in which fuel supply was stopped, and combustion is resumed. In such a case, if the EGR valve is opened and closed excessively, the amount of EGR gas flowing into the intake passage during the opening and closing operation may increase, deteriorating the combustion state when combustion resumes, and making the restart difficult. [Means for solving the problem]

[0005] An EGR valve control device according to one aspect of the present invention includes an internal combustion engine mounted on a vehicle and having a fuel injection unit and an EGR valve that adjusts the amount of exhaust gas recirculation, and a control unit that determines whether a fuel cut condition is met when the vehicle is decelerating, and, if it is determined that the fuel cut condition is met, stops fuel supply from the fuel injection unit and controls the fuel injection unit and the EGR valve so that the EGR valve performs opening and closing operations a first predetermined number of times. The control unit further controls the EGR valve so that the EGR valve performs opening and closing operations a second predetermined number of times when the vehicle's ignition switch is turned off. The first predetermined number of times is less than the second predetermined number of times. [Effects of the Invention]

[0006] According to the present invention, it is possible to ensure restartability of an internal combustion engine after deceleration fuel cut. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating an example of a configuration of an engine and its surroundings to which an EGR valve control device according to an embodiment of the present invention is applied; [Figure 2] FIG. 2 is a diagram schematically illustrating an example of the internal configuration of the EGR valve of FIG. 1. [Figure 3] 2 is a time chart showing an example of the operation of the EGR valve of FIG. 1 in one driving cycle from when the ignition switch of the vehicle is turned on to when it is turned off. [Figure 4] 1 is a block diagram that schematically shows an example of the configuration of a main part of an EGR valve control device according to an embodiment of the present invention. [Figure 5] 4 is a time chart showing an example of a first opening / closing operation of an EGR valve. [Figure 6] 5 is a time chart showing an example of a second opening / closing operation of the EGR valve. [Figure 7] 5 is a flowchart showing an example of processing executed by the ECU of FIG. 4; DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 7. FIG. 1 is a diagram schematically illustrating an example of the configuration of an engine 1 and its surroundings to which an EGR valve control device according to an embodiment of the present invention is applied. The engine 1 is an internal combustion engine such as a gasoline engine or a diesel engine mounted on a vehicle (not shown), and includes an injector 1a that injects fuel into the combustion chamber or intake port of each cylinder. The fuel injection timing and fuel injection duration of the injector 1a are controlled by an electronic control unit (ECU (Electronic Control Unit)) 10 (FIG. 4) mounted on the vehicle, thereby adjusting the amount of fuel supplied to the engine 1 (fuel injection amount). The fuel injection timing and fuel injection duration of the injector 1a are determined by predetermined characteristics depending on the operating state of the engine 1, etc. The vehicle may be mounted with only the engine 1 as a drive source, or may be a hybrid vehicle equipped with the engine 1 and a traction motor. The engine 1 is also provided with a rotation speed sensor 1b that detects the engine rotation speed.

[0009] As shown in Fig. 1, an intake passage 3 is connected to an engine 1 via an intake manifold 2, and an exhaust passage 5 is connected via an exhaust manifold 4. The air taken into the intake passage 3 via an air cleaner (not shown) has its flow rate adjusted by a throttle valve 6 provided in the intake passage 3, and is supplied to the engine 1 via the intake manifold 2. Exhaust gas discharged from the engine 1 into the exhaust passage 5 via the exhaust manifold 4 is purified by a catalytic device 7 provided in the exhaust passage 5 and then released into the atmosphere.

[0010] A portion of the exhaust gas discharged into the exhaust passage 5 is recirculated to the intake passage 3 via the EGR passage 8. The flow rate of the exhaust gas (EGR gas) recirculated from the exhaust passage 5 to the intake passage 3 via the EGR passage 8, i.e., the exhaust gas recirculation amount of the engine 1, is adjusted by an EGR valve 9 provided in the EGR passage 8. The EGR valve 9 is provided with a lift sensor 9a that detects the lift amount of a valve body (Figure 2) corresponding to the opening degree of the EGR valve 9. The EGR valve 9 is controlled by an ECU 10 (Figure 4).

[0011] FIG. 2 is a diagram schematically illustrating an example of the internal configuration of the EGR valve 9, showing the EGR valve 9 in a closed (fully closed) state. The EGR valve 9 is configured as, for example, an electric poppet valve. As shown in FIG. 2, the EGR valve 9 has a valve body 90 that forms part of the EGR passage 8. The valve body 90 is formed with an inlet-side passage 91 connected to the EGR passage 8 on the exhaust passage 5 side, and an outlet-side passage 92 connected to the EGR passage 8 on the intake passage 3 side. A substantially annular valve seat 93 centered on a vertical axis CL is provided in the valve body 90 between the inlet-side passage 91 and the outlet-side passage 92.

[0012] The EGR valve 9 further includes a valve element 94 that is capable of seating on the valve seat 93, a valve stem 95 that is integral with the valve element 94, a compression spring 96 that urges the valve element 94 and the valve stem 95 upward, and a solenoid 97 that drives the valve element 94 and the valve stem 95 downward. Note that the valve element 94 and the valve stem 95 may be driven by a motor such as a stepping motor instead of the solenoid. The compression spring 96 and the solenoid 97 are housed in a housing 98 that is provided above the valve body 90.

[0013] The through-hole 93a of the valve seat 93 has a truncated conical surface centered on the vertical axis CL and expands in diameter upward. The valve element 94 is formed in a generally truncated conical shape centered on the vertical axis CL and expands in diameter downward. The valve shaft 95 is provided so as to extend upward along the vertical axis CL from the upper end of the valve element 94 and is supported by a bearing 98a provided in the housing 98 so as to be slidable along the vertical axis CL. The valve shaft 95 is formed with a spring bearing 95a that protrudes horizontally in the outer diameter direction centered on the vertical axis CL.

[0014] The lower end of the compression spring 96 abuts against the upper end surface of the bearing 98a, and the upper end of the compression spring 96 abuts against the lower end surface of the spring receiver 95a, and the compression spring 96 urges the valve element 94 and the valve shaft 95 upward via the spring receiver 95a. The solenoid 97 is connected to the spring receiver 95a and drives the valve element 94 and the valve shaft 95 downward via the spring receiver 95a.

[0015] 2, when the solenoid 97 is off, the valve element 94 and the valve stem 95 are urged upward by the compression spring 96, and the truncated conical surface of the valve element 94 abuts against the lower end of the valve seat 93 (through-hole 93a), causing the valve element 94 to seat on the valve seat 93, thereby closing the EGR valve 9. When the solenoid 97 is turned on, the valve stem 95 and the valve element 94 are driven downward against the urging force of the compression spring 96, causing the valve element 94 to move away from the valve seat 93, thereby opening the EGR valve 9.

[0016] The lift amount of the valve element 94, which corresponds to the opening of the EGR valve 9, i.e., the distance of the valve element 94 from the valve seat 93, is detected by a lift sensor 9a provided at the upper end of the valve stem 95. The lift amount when the EGR valve 9 is fully closed is 0 mm, and the lift amount when fully open is, for example, approximately 5 mm. The amount of electricity supplied to the solenoid 97 is controlled by the ECU 10 (FIG. 4), which adjusts the lift amount (0 to 5 mm) of the EGR valve 9 and regulates the flow rate of EGR gas. The target lift amount of the EGR valve 9 is determined by predetermined characteristics depending on the operating state of the engine 1, and the EGR valve 9 (solenoid 97) is feedback-controlled so that the lift amount detected by the lift sensor 9a becomes the target lift amount.

[0017] 3 is a time chart showing an example of the operation of the EGR valve 9 during one driving cycle from when the vehicle's ignition switch is turned on to when it is turned off, illustrating the operation of the EGR valve 9 during a cold start. As shown in FIG. 3, even when the vehicle's ignition switch is turned on at time t1, the engine 1 starts operating, and the vehicle begins traveling, the EGR valve 9 is prohibited from opening and maintained in a closed state until the engine water temperature reaches a predetermined water temperature at which the EGR valve 9 can be operated. When the predetermined water temperature is reached at time t2, the EGR valve 9 is permitted to open, and the EGR valve 9 is feedback-controlled to achieve a target lift amount determined based on the operating state of the engine 1, etc. Thereafter, the vehicle decelerates at time t3, entering a deceleration fuel cutoff state in which fuel supply to the engine 1 is cut off. When the vehicle stops at time t4, a command to close the EGR valve 9 is issued until the vehicle begins traveling again at time t5.

[0018] In the example of FIG. 3 , even though a command to close the EGR valve 9 is issued from time t3 to time t5, a lift amount equal to or greater than a predetermined value α (e.g., approximately 0.5 to 1.0 mm) is detected. This indicates that a foreign object is trapped in the EGR valve 9. For example, a foreign object that flows in from the inlet-side passage 91 in FIG. 2 and becomes trapped between the valve seat 93 and the valve disc 94 from time t2 to time t3 becomes trapped between the lower end of the valve seat 93 (through-hole 93 a) and the truncated conical surface of the valve disc 94 when the valve disc 94 moves upward (in the valve closing direction) in response to the valve closing command at time t3. Alternatively, a foreign object that flows in from the inlet-side passage 91 and passes between the valve seat 93 and the valve disc 94 becomes trapped between the lower end of the valve seat 93 (through-hole 93 a) and the truncated conical surface of the valve disc 94 at time t3. In this case, when the valve body 94 is seated on the valve seat 93 via a foreign object, the lift amount becomes larger than the lift amount (0 mm) when the valve body 94 abuts on the valve seat 93 without a foreign object, and becomes greater than a predetermined value α (for example, approximately 0.5 to 1.0 mm).

[0019] The foreign matter that may become caught between the valve seat 93 and the valve body 94 in this way includes, for example, deposits that are combustion products (oxides and carbides) contained in EGR gas that have accumulated on the wall surfaces of gas flow paths such as the EGR passage 8 and that have peeled off and become foreign matter. When EGR gas is flowing through the EGR passage 8, such foreign matter passes between the valve seat 93 and the valve body 94 without becoming caught if the EGR valve 9 is nearly fully open. When EGR gas is not flowing through the EGR passage 8, the EGR valve 9 can be fully opened to allow the foreign matter to fall downward in the direction of gravity, i.e., toward the inlet-side passage 91.

[0020] When the vehicle resumes running and the opening of the EGR valve 9 increases, the foreign matter lodged in the EGR valve 9 passes through the outlet passage 92 together with the EGR gas. However, if foreign matter is lodged in the EGR valve 9 during an idle stop of the vehicle or when the engine 1 is stalled, restarting the engine itself, which is when fuel supply to the combustion chamber is stopped and fuel supply is resumed to restart combustion, may become difficult if foreign matter is lodged in the EGR valve 9. In other words, since the EGR valve 9 cannot be fully closed with foreign matter lodged in it, EGR gas flows into the combustion chamber during restart, making it impossible to maintain an appropriate air-fuel ratio and making restarting difficult.

[0021] The restart request includes a restart request issued by the engine system when the vehicle returns from idle stop in response to the driver's operation to release the brake in the drive range (D range) or when the vehicle transitions from EV driving to driving using the engine 1. It also includes a restart request issued in response to the driver's operation to turn on the starter via the ignition switch in the parking range (P range) when the engine 1 stalls, for example.

[0022] Between a state in which the EGR valve 9 is operating and a state in which the vehicle is idling and the engine 1 is stalled, in which foreign matter may get caught in the EGR valve 9 and cause restart problems, there is a deceleration fuel cut-off state in which the vehicle is decelerating and the fuel supply to the engine 1 is cut off. During the deceleration fuel cut-off state, the engine 1 rotates according to the vehicle speed, and fresh air from the intake passage 3 (Figure 1) blows through the combustion chamber of the engine 1. At this time, by fully opening the EGR valve 9, the foreign matter caught in the EGR valve 9 can be dislodged and passed through the combustion chamber to the outlet passage 92 (Figure 2) together with the EGR gas that is blown through the combustion chamber and recirculated to the intake passage 3 from the exhaust passage 5 via the EGR passage 8.

[0023] However, if the EGR valve 9 is opened and closed excessively, restarting the engine may become difficult even if the jammed state is resolved. That is, the amount of EGR gas flowing into the intake passage 3, which is under negative pressure during the opening and closing operation of the EGR valve 9, and flowing into the combustion chamber at restart increases, making it impossible to ensure an appropriate air-fuel ratio when combustion resumes. In this case, the combustion state in the combustion chamber at the time of combustion resumes deteriorates, making it difficult for the engine 1 to operate normally and restarting the engine. Therefore, in this embodiment, the EGR valve control device is configured as follows to ensure the restartability of the engine 1 after deceleration fuel cutoff by performing appropriate opening and closing operation of the EGR valve 9 during deceleration fuel cutoff.

[0024] FIG. 4 is a block diagram showing an example of a configuration of a main part of an EGR valve control device (hereinafter, referred to as the device) 100 according to an embodiment of the present invention. As shown in FIG. 4, the device 100 mainly includes an ECU 10 that controls an injector 1a and an EGR valve 9, an engine speed sensor 1b, a lift sensor 9a, a vehicle speed sensor 20, the injector 1a, and the EGR valve 9, all of which are connected to the ECU 10. Although not shown, the ECU 10 is also connected to various sensors and other ECUs mounted on the vehicle, and receives detected values ​​and command values ​​of various parameters indicating the operating state of the vehicle, such as the accelerator opening and engine water temperature. The ECU 10 includes a processor 11 such as a CPU, a memory 12 such as a ROM and a RAM, and a computer having other peripheral circuits. The ECU 10 is configured as an engine control ECU that controls the entire engine 1, including the injector 1a, the EGR valve 9, the throttle valve 6, and the like.

[0025] <First opening / closing operation> The ECU 10 determines whether a predetermined fuel cut condition is met when the vehicle is decelerating, based on the vehicle speed detected by the vehicle speed sensor 20, etc. If it is determined that the fuel cut condition is met, the ECU 10 controls the injector 1a to stop fuel supply from the injector 1a and controls the EGR valve 9 to perform a first predetermined number of opening and closing operations (first opening and closing operations). The first predetermined number of operations is set to the minimum number of times necessary to remove foreign matter caught in the EGR valve 9, for example, one time. More specifically, the ECU 10 commands the EGR valve 9 (solenoid 97) to set a target lift amount (0 mm → 5 mm → 0 mm) so that the valve element 94 of the EGR valve 9 reciprocates between the fully closed position and the fully open position the first predetermined number of times. Even if the opening and closing operation is performed only once, foreign matter can be released, passed through, and removed before the valve element 94 reaches the fully open position.

[0026] The ECU 10 controls the EGR valve 9 to perform a first opening / closing operation on the condition that the EGR valve 9 is operated while the engine 1 is running after the vehicle ignition switch is turned on. That is, if the EGR valve 9 is operating during the current driving cycle, a jammed state may occur. However, even if the engine 1 is operating during the driving cycle, if the EGR valve 9 is not operating, the jammed state will not occur. When the EGR valve 9 is opened or closed, a seating sound is generated when the valve body 94 seats on the valve seat 93, and an operating sound is generated from the solenoid 97, which may cause discomfort to the driver. Furthermore, a certain amount of power is consumed by the operation of the solenoid 97. Minimizing the opening and closing operation of the EGR valve 9 minimizes discomfort to the driver and power consumption.

[0027] The ECU 10 further controls the EGR valve 9 to perform a first opening / closing operation on the condition that the lift sensor 9a detects a jammed state. In the deceleration fuel cutoff state, the ECU 10 always commands the EGR valve 9 to close, and commands a target lift amount (0 mm) corresponding to the fully closed position. While the ECU 10 is commanded to close the EGR valve 9 (target lift amount 0 mm) during the driving cycle, the ECU 10 constantly compares the lift amount of the EGR valve 9 detected by the lift sensor 9a with a predetermined value α (e.g., approximately 0.5 to 1.0 mm) at predetermined intervals (e.g., every few seconds). If the lift amount of the EGR valve 9 is equal to or greater than the predetermined value α, the ECU 10 determines that a jammed state has occurred. If the lift amount of the EGR valve 9 is less than the predetermined value α, the ECU 10 determines that a jammed state has not occurred. When the ECU 10 enters the deceleration fuel cutoff state while the jammed state has been determined to have occurred, the ECU 10 controls the EGR valve 9 to perform an opening / closing operation.

[0028] If a jammed state occurs during deceleration fuel cut of the engine 1, which is likely to require restarting immediately thereafter, controlling the EGR valve 9 to perform the first opening and closing operation can remove foreign matter and ensure restartability. Also, by minimizing the number of first opening and closing operations, the amount of EGR gas that flows into the intake passage 3 during the opening and closing operation can be reduced, ensuring restartability. Also, by performing the opening and closing operation of the EGR valve 9 only when a jammed state is detected, it is possible to minimize the discomfort felt by the driver and the power consumption.

[0029] Fig. 5 is a time chart showing an example of the first opening / closing operation of the EGR valve 9. As shown in Fig. 3 and Fig. 5, the ignition switch of the vehicle is turned on at time t1, the EGR valve 9 operates from time t2 to t3, and it is determined at time t3 that the EGR valve 9 is stuck. After that, when the deceleration fuel cut state is entered at time t6 while it is determined that the stuck state has occurred, the first opening / closing operation of the EGR valve 9 is performed at time t7, the stuck foreign matter is removed, and the lift amount becomes 0 mm.

[0030] During deceleration fuel cutoff, the vehicle's self-diagnosis function (OBD (On-board diagnostics)) may perform a fault diagnosis of the EGR system (fault diagnosis to determine whether or not there is a decrease in EGR flow rate). In this case, when the deceleration fuel cutoff state is entered, the fault diagnosis is performed first, and then the first opening / closing operation is initiated. Because the fault diagnosis takes a certain amount of time (e.g., approximately 1 to 3 seconds), depending on the length of the deceleration fuel cutoff period, the first opening / closing operation may be completed between the end of the deceleration fuel cutoff and just before restart. Even in such cases, by minimizing the number of first opening / closing operations, the amount of EGR gas flowing into the intake passage 3 during the opening / closing operation can be reduced, ensuring restartability.

[0031] <Second opening / closing operation> When the vehicle ignition switch is turned off, the ECU 10 controls the EGR valve 9 to perform a second predetermined number of opening and closing operations (second opening and closing operations). The second predetermined number of times is set to a plurality of times, for example, three times, so that foreign matter caught in the EGR valve 9 can be reliably removed even when EGR gas is not flowing through the EGR passage 8. More specifically, the ECU 10 commands the EGR valve 9 (solenoid 97) to set a target lift amount (0 mm → 5 mm → 0 mm → 5 mm → 0 mm → 5 mm → 0 mm) so that the valve body 94 of the EGR valve 9 reciprocates between the fully closed position and the fully open position the second predetermined number of times.

[0032] As a result, even if the ignition switch is turned off with foreign matter lodged in the EGR valve 9, the lodged state can be resolved, ensuring startability in the next driving cycle. The second opening and closing operation is performed when the engine 1 is not rotating and EGR gas is not flowing through the EGR passage 8, so the opening and closing operation does not cause EGR gas to flow into the combustion chamber and does not affect startability in the next driving cycle. By repeating the opening and closing operation two or more times, the impact when the valve body 94 seats on the valve seat 93 and the vibration when it returns from the fully open position can more reliably cause foreign matter to fall off and be removed.

[0033] The opening and closing operation of the EGR valve 9 when the ignition switch is turned off is also performed on the condition that the EGR valve 9 was operated in the driving cycle immediately before the vehicle's ignition switch was turned on and off. The opening and closing operation of the EGR valve 9 when the ignition switch is turned off may also be performed on the condition that a jammed state has been detected. In this case, it is possible to further reduce the discomfort felt by the driver and the power consumption.

[0034] Fig. 6 is a time chart showing an example of the second opening / closing operation of the EGR valve 9. As shown in Fig. 3 and Fig. 6, the ignition switch is turned on at time t1, the EGR valve 9 operates from time t2 to t3, and then the ignition switch is turned off at time t10, causing the second opening / closing operation of the EGR valve 9 to be performed at time t11. However, if the EGR valve 9 has not operated after the first opening / closing operation is performed at time t7 in Fig. 5, the second opening / closing operation at time t11 is not performed.

[0035] If a start request for the engine 1 is received during the second opening / closing operation of the EGR valve 9, the ECU 10 controls the EGR valve 9 to stop the second opening / closing operation and close the valve. More specifically, if the valve element 94 is moving away from the valve seat 93 (i.e., during a valve opening operation) at the time of the start request, the ECU 10 prohibits further valve opening and seats the valve element 94 on the valve seat 93. If the valve element 94 is moving toward seating on the valve seat 93 (i.e., during a valve closing operation) at the time of the start request, the ECU 10 continues the valve closing operation until the valve element 94 seats on the valve seat 93, and prohibits further valve opening once the valve element 94 seats on the valve seat 93. Note that, once the valve element 94 seats on the valve seat 93 after the start request, further valve opening may be prohibited. In this case, the EGR valve 9 is fully opened at least once, which more reliably removes foreign matter. There is a certain delay time between the issuance of a start request and the start of cranking. Therefore, by stopping the opening and closing operation in response to a start request, the EGR valve 9 can be reliably brought to a fully closed state when cranking starts.

[0036] 7 is a flowchart showing an example of processing executed by the ECU 10. The processing shown in this flowchart starts when the ECU 10 is started and is repeated at predetermined time intervals. As shown in FIG. 7, first, in step S1, it is determined whether or not there is a history of the EGR valve 9 being operated in the current driving cycle. If the result in step S1 is negative, the processing ends, and if the result in step S1 is positive, the processing proceeds to step S2. In step S2, it is determined whether or not the lift amount of the EGR valve 9 detected by the lift sensor 9a when the EGR valve 9 is commanded to close is equal to or greater than a predetermined value α.

[0037] If the result in step S2 is negative, the process ends, and if the result is positive, the process proceeds to step S3. In step S3, it is determined whether or not a predetermined fuel cut condition is met when the vehicle is decelerating, based on the vehicle speed detected by the vehicle speed sensor 20. If the result in step S3 is positive, the fuel supply from the injector 1a is stopped, and the process proceeds to step S4, where the EGR valve 9 is controlled to perform the first opening / closing operation.

[0038] If the result in step S3 is negative, the process proceeds to step S5, where it is determined whether the ignition switch is turned off. If the result in step S5 is negative, the process ends, but if the result in step S5 is positive, the process proceeds to step S6, where the EGR valve 9 is controlled to perform the second opening / closing operation.

[0039] According to the embodiment of the present invention, the following advantageous effects can be achieved. (1) The device 100 is mounted on a vehicle and includes an engine 1 having an injector 1a and an EGR valve 9 that adjusts the amount of exhaust gas recirculation (EGR). The ECU 10 determines whether a fuel cut condition is met when the vehicle is decelerating, and, if it is determined that the fuel cut condition is met, stops fuel supply from the injector 1a and controls the injector 1a and the EGR valve 9 so that the EGR valve 9 performs a first predetermined number of opening and closing operations (first opening and closing operations) (steps S2 and S4 in FIGS. 1, 2, 4, 5, and 7). The ECU 10 further controls the EGR valve 9 so that the EGR valve 9 performs a second predetermined number of opening and closing operations (second opening and closing operations) when the vehicle's ignition switch is turned off (steps S5 and S6 in FIGS. 6 and 7). The first predetermined number is less than the second predetermined number (FIGS. 5 and 6). In this way, during deceleration fuel cut of the engine 1, which is likely to require restarting immediately thereafter, reducing the number of times the EGR valve 9 is opened and closed reduces the amount of EGR gas that flows into the intake passage during the opening and closing operations while removing foreign matter, thereby ensuring restartability. Also, reducing the number of times the EGR valve 9 is opened and closed reduces the discomfort felt by the driver and power consumption.

[0040] (2) The device 100 further includes a lift sensor 9a that detects a jammed state in which a foreign object is jammed in the EGR valve 9 (FIGS. 1, 2, and 4). When fuel supply to the engine 1 is stopped while the vehicle is decelerating, the ECU 10 controls the EGR valve 9 to perform the first opening / closing operation on the condition that the lift sensor 9a detects the jammed state (step S3 in FIGS. 5 and 7). In this way, by performing the opening / closing operation of the EGR valve 9 only when a jammed state is actually detected, it is possible to minimize the discomfort felt by the driver and the power consumption.

[0041] (3) After the ignition switch is turned on, the ECU 10 controls the EGR valve 9 to perform an opening and closing operation on the condition that the EGR valve 9 is operated while the engine 1 is running (step S1 in FIG. 7). In other words, if the EGR valve 9 is not operating in the current driving cycle, a jammed state will not occur, and therefore the EGR valve 9 will not perform an opening or closing operation. By minimizing the opening and closing operation of the EGR valve 9, it is possible to minimize the discomfort felt by the driver and the power consumption.

[0042] The above embodiment can be modified in various ways. Modifications will be described below. In the above embodiment, an example in which exhaust gas after passing through the catalytic device 7 is recirculated as EGR gas has been described with reference to FIG. 1 and other figures. However, the internal combustion engine may be any engine having an EGR valve that adjusts the amount of exhaust gas recirculation, and the arrangement of the various parts of the internal combustion engine is not limited to that illustrated. For example, exhaust gas before passing through the catalytic device 7 may be recirculated as EGR gas. The EGR passage 8 may be directly connected to the exhaust manifold 4 instead of the exhaust passage 5, or directly connected to the intake manifold 2 instead of the intake passage 3, or may be connected to the intake manifold 2 via an appropriate chamber or the like for mixing the EGR gas and fresh air.

[0043] 1, 2, 4, etc., an example has been described in which the lift sensor 9a is used to detect the jammed state of the EGR valve 9, but the detection unit for detecting the jammed state of the EGR valve due to foreign matter being jammed is not limited to this. For example, an appropriate concentration sensor may be provided in the EGR passage 8 downstream of the EGR valve 9 to detect the concentration of gas components contained in the exhaust, and the inflow of EGR gas and the jammed state of the EGR valve 9 may be detected based on the detected concentration.

[0044] In the above embodiment, the specific internal configuration of the EGR valve 9 is illustrated in FIG. 2 and other figures, but the EGR valve is not limited to the illustrated configuration. For example, a valve other than a poppet valve, such as a butterfly valve, may be used. That is, a butterfly valve may also become clogged with foreign matter, just like a poppet valve, and the foreign matter can be removed by fully opening the valve. When a butterfly valve is used, the valve opening degree can be detected by an angle sensor instead of a lift sensor.

[0045] In the above embodiment, the lift amount (5 mm) when the valve is fully open and the predetermined value α (0.5 to 1.0 mm) for detecting and determining the jamming state are exemplified in Figures 3, 5, 6, etc., but these are merely examples for the purpose of explanation, and the specifications of the EGR valve are not limited to those exemplified.

[0046] The above description is merely an example, and the present invention is not limited to the above-described embodiment and modifications, as long as the features of the present invention are not impaired. One or more of the above-described embodiment and modifications can be arbitrarily combined, and modifications can also be combined with each other. [Explanation of symbols]

[0047] 1 engine, 1a injector, 1b rotation speed sensor, 2 intake manifold, 3 intake passage, 4 exhaust manifold, 5 exhaust passage, 6 throttle valve, 7 catalytic converter, 8 EGR passage, 9 EGR valve, 9a lift sensor, 10 ECU (electronic control unit), 20 vehicle speed sensor, 90 valve body, 91 inlet passage, 92 outlet passage, 93 valve seat, 93a through hole, 94 valve body, 95 valve stem, 95a spring seat, 96 compression spring, 97 solenoid, 98 housing, 98a bearing, 100 EGR valve control device (device)

Claims

1. an internal combustion engine mounted on a vehicle and having a fuel injection unit and an EGR valve that adjusts the amount of exhaust gas recirculation; a control unit that determines whether a fuel cut condition is met when the vehicle is decelerating, and when it is determined that the fuel cut condition is met, stops fuel supply from the fuel injection unit and controls the fuel injection unit and the EGR valve so that the EGR valve performs an opening and closing operation a first predetermined number of times, The control unit further controls the EGR valve to perform an opening and closing operation a second predetermined number of times when an ignition switch of the vehicle is turned off, The EGR valve control device is characterized in that the first predetermined number of times is smaller than the second predetermined number of times.

2. The EGR valve control device according to claim 1, A detection unit is further provided to detect a state in which a foreign object is caught in the EGR valve, The control unit controls the EGR valve to perform the first predetermined number of opening and closing operations when fuel supply to the internal combustion engine is stopped during deceleration of the vehicle, and further, on the condition that the detection unit detects the jammed state.

3. The EGR valve control device according to claim 1 or 2, the control unit controls the EGR valve to perform the first predetermined number of opening and closing operations and / or the second predetermined number of opening and closing operations on the condition that the EGR valve is actuated during operation of the internal combustion engine after the ignition switch is turned on.

Images