EGR valve control device

Abstract

To ensure restart capability when an internal combustion engine stops with an ignition switch in an on position.SOLUTION: An EGR valve control device 100 comprises: an EGR valve 9 which adjusts an exhaust recirculation amount in an internal combustion engine mounted on a vehicle; a detection section 9a which detects a jamming state caused by a foreign matter in the EGR valve 9; and a control section 10 which controls the EGR valve 9. When the internal combustion engine stops rotating with an ignition switch of the vehicle in an on position, the control section 10 controls the EGR valve 9 to perform opening and closing operations a predetermined number of times, under a condition that the detection section 9a detects the jamming state.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 remove foreign matter adhering to the EGR valve when the internal combustion engine is stopped (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 reciprocates between opening and closing the EGR valve near the fully closed position when the ignition is turned on, the internal combustion engine starts operating, and then the ignition is turned 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. 2007-64166 Summary of the Invention [Problem to be solved by the invention]

[0004] When a vehicle idles or the internal combustion engine stalls, the engine may stop with the ignition switch on. If a foreign object is caught in the EGR valve at this time, the EGR valve may not be able to close completely, and EGR gas may flow into the combustion chamber when the engine is restarted, making it difficult to restart. [Means for solving the problem]

[0005] An EGR valve control device according to one aspect of the present invention includes an EGR valve that adjusts the amount of exhaust gas recirculation in an internal combustion engine mounted on a vehicle, a detection unit that detects a state in which foreign matter is caught in the EGR valve, and a control unit that controls the EGR valve. When the rotation of the internal combustion engine stops with the ignition switch of the vehicle on, the detection unit detects the state of the foreign matter. At the same time, the internal combustion engine does not start despite a start request. On the condition that the EGR valve is opened and closed a predetermined number of times, the EGR valve is controlled. Another aspect of the present invention is an EGR valve control device that includes an EGR valve that adjusts the amount of exhaust gas recirculation in an internal combustion engine mounted on a vehicle, a detection unit that detects a state in which foreign matter is trapped in the EGR valve, and a control unit that controls the EGR valve. When the internal combustion engine stops rotating with the vehicle ignition switch on, the control unit controls the EGR valve to perform opening and closing operations a predetermined number of times on the condition that the detection unit detects the trapped state, and controls the EGR valve to stop opening and closing operations and close if a start request for the internal combustion engine is made during the opening and closing operations. Another aspect of the present invention is an EGR valve control device that includes an EGR valve that adjusts the amount of exhaust gas recirculation in an internal combustion engine mounted on a vehicle, a detection unit that detects a state in which foreign matter is trapped in the EGR valve, and a control unit that controls the EGR valve. When the internal combustion engine stops rotating with the vehicle's ignition switch on, the control unit controls the EGR valve to perform opening and closing operations a predetermined number of times, provided that the detection unit detects the trapped state, and controls the EGR valve to continue opening and closing operations even if the ignition switch is turned off during the opening and closing operations. [Effects of the Invention]

[0006] According to the present invention, it is possible to ensure restartability when the internal combustion engine stops with the ignition switch on. [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 the opening and closing operation of an EGR valve. [Figure 6] 6 is a time chart showing another example of the opening and closing operation of the EGR valve. [Figure 7] 4 is a time chart showing an example of the opening and closing operation of the EGR valve when a start request is made during the opening and closing operation of the EGR valve. [Figure 8] 4 is a time chart showing an example of an opening and closing operation of an EGR valve when an ignition switch is turned off during the opening and closing operation of the EGR valve. [Figure 9] 5 is a flowchart showing an example of processing executed by the ECU of FIG. 4 when the ignition switch of the vehicle is on. [Figure 10] 10 is a flowchart showing a modification of FIG. 9; [Figure 11] 5 is a flowchart showing an example of a process executed by the ECU of FIG. 4 when a start request is made during the opening and closing operation of the EGR valve. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to Figs. 1 to 11. Fig. 1 is a diagram schematically showing an example of the configuration of the periphery of an engine 1 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). The vehicle may be mounted with only the engine 1 as a drive source, or may be a hybrid vehicle mounted with the engine 1 and a traction motor. The engine 1 is provided with a rotation speed sensor 1a 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 an 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 electronic control unit (ECU) 10 (Figure 4) mounted on the vehicle.

[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 driving 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 may become difficult. In other words, since the EGR valve 9 cannot be fully closed with foreign matter lodged therein, EGR gas flows into the combustion chamber during restart, making it impossible to maintain an appropriate air-fuel ratio and making restarting difficult.

[0021] Therefore, in this embodiment, if the engine 1 stops with the ignition switch on and foreign matter still lodged in the EGR valve 9, the EGR valve control device is configured as follows to remove the lodged foreign matter by opening and closing the EGR valve 9.

[0022] FIG. 4 is a block diagram showing an example of a main configuration 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 EGR valve 9, an engine speed sensor 1a, a lift sensor 9a, and an EGR valve 9 (solenoid 97), each 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 vehicle's operating state, such as the accelerator position 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 EGR valve 9, the throttle valve 6, the injectors, and the like.

[0023] When the vehicle's ignition switch is turned off, the ECU 10 controls the EGR valve 9 to open and close the valve a predetermined number of times (e.g., three times). 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 element 94 of the EGR valve 9 moves back and forth between the fully closed position and the fully open position a predetermined number of times. This allows the EGR valve 9 to resolve any foreign matter trapped in it, ensuring startability in the next driving cycle. The opening and closing operations are performed when the engine 1 is not rotating and EGR gas is not flowing through the EGR passage 8. This prevents EGR gas from flowing into the combustion chamber and does not affect startability in the next driving cycle.

[0024] Even if the opening and closing operation is performed only once, foreign matter can be dropped and removed before the valve element 94 reaches the fully open position. If the opening and closing operation is performed two or more times, foreign matter can be more reliably dropped and removed due to the impact when the valve element 94 seats on the valve seat 93 and the vibration when it turns back from the fully open position.

[0025] After the vehicle's ignition switch is turned on, the ECU 10 controls the EGR valve 9 to perform the same opening and closing operation as when the ignition switch is turned off, as necessary, on the condition that the EGR valve 9 is operated while the engine 1 is running. 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 opens and closes, it generates a seating sound when the valve body 94 seats on the valve seat 93 and an operating sound of the solenoid 97, which may cause discomfort to the driver. Furthermore, the operation of the solenoid 97 consumes a certain amount of power. Minimizing the opening and closing operation of the EGR valve 9 minimizes discomfort to the driver and power consumption.

[0026] When the engine 1 stops rotating with the vehicle ignition switch on, the ECU 10 controls the EGR valve 9 to open and close, provided that the lift sensor 9a detects a jammed state. While the engine 1 is operating with the engine 1 stopped, the ECU 10 always commands the EGR valve 9 to close, and a target lift amount (0 mm) corresponding to the fully closed position is commanded. While the ECU 10 is commanded to close the EGR valve 9 (target lift amount 0 mm) during the driving cycle, the ECU 10 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 engine speed detected by the engine speed sensor 1a reaches 0 rpm while the ECU 10 determines that a jammed state has occurred, the ECU 10 controls the EGR valve 9 to open and close.

[0027] Even during a driving cycle, the rotation of the engine 1 may stop during an idle stop, when a hybrid vehicle is running solely on the traction motor (EV driving), when the engine 1 stalls, etc. In such cases, there is a high probability that a restart will be necessary immediately. If a jammed state occurs when the rotation of the engine 1 stops during a driving cycle, the EGR valve 9 can be controlled to open and close to remove foreign matter and ensure restartability. Furthermore, by opening and closing the EGR valve 9 only when a jammed state is detected, the discomfort felt by the driver and power consumption can be minimized.

[0028] 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 is detected. In this case, it is possible to further reduce the discomfort felt by the driver and the power consumption.

[0029] FIG. 5 is a time chart showing an example of the opening and closing operation of the EGR valve 9. As shown in FIGS. 3 and 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 jammed. Thereafter, when it is determined that the jammed state has occurred, the engine 1 stops rotating at time t4, and the EGR valve 9 opens and closes at time t7 to remove the jammed foreign matter and set the lift amount to 0 mm. Furthermore, when the ignition switch is turned off at time t10, the EGR valve 9 opens and closes at time t11. However, if the EGR valve 9 is not operating after the opening and closing operation at time t7, the EGR valve 9 does not open or close at time t11.

[0030] When the rotation of the engine 1 stops during a driving cycle, the ECU 10 may determine whether a jammed state has occurred on the condition that the engine 1 does not start despite a subsequent restart request, and perform the opening and closing operation of the EGR valve 9 according to the determination result. That is, if the engine speed detected by the rotation speed sensor 1a during a driving cycle becomes 0 rpm and restart of the engine 1 in response to a restart request fails, the ECU 10 compares the lift amount of the EGR valve 9 detected by the lift sensor 9a with a predetermined value α. If the lift amount is equal to or greater than the predetermined value α, it is determined that a jammed state has occurred, and the ECU 10 controls the EGR valve 9 to perform the opening and closing operation. If the lift amount is less than the predetermined value α, it is determined that a jammed state has not occurred, and the ECU 10 does not perform the opening and closing operation.

[0031] The restart request includes a restart request issued by the engine system when recovering from idle stop in response to the driver's operation to release the brake in the drive range (D range) or when transitioning 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, etc.

[0032] Even if the EGR valve 9 is stuck, if the restart is successful, when the vehicle resumes driving and the opening of the EGR valve 9 increases, the foreign matter stuck in the EGR valve 9 will pass through the outlet passage 92 together with the EGR gas. If the restart fails, it is determined whether the EGR valve 9 is stuck, and the EGR valve 9 is opened or closed depending on the determination result, thereby further reducing the discomfort felt by the driver and power consumption.

[0033] FIG. 6 is a time chart showing an example of the opening and closing operation of the EGR valve 9 when determining whether a jammed state has occurred, assuming that restart will fail. As shown in FIGS. 3 and 6, the ignition switch 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 jammed. Subsequently, while it is determined that a jammed state has occurred, the engine 1 stops rotating at time t4. If restart of the engine 1 fails at time t5, the EGR valve 9 opens and closes at time t8 to remove the jammed foreign matter, and the lift amount becomes 0 mm. At time t5, the engine speed temporarily increases due to cranking in response to a restart request, but then the engine speed returns to 0 rpm without achieving complete combustion, resulting in a failed restart.

[0034] FIG. 7 is a time chart showing an example of the opening and closing operation of the EGR valve 9 when a start request is received during the opening and closing operation of the EGR valve 9. When a start request for the engine 1 is received during the opening and closing operation of the EGR valve 9, the ECU 10 controls the EGR valve 9 to stop the opening and closing operation and close the valve. More specifically, if the valve disc 94 is moving away from the valve seat 93 (i.e., during the valve opening operation) at the time of the start request, the ECU 10 prohibits further opening and seats the valve disc 94 on the valve seat 93. If the valve disc 94 is moving toward the valve seat 93 (i.e., during the valve closing operation) at the time of the start request, the ECU 10 continues the valve closing operation until the valve disc 94 seats on the valve seat 93. Once the valve disc 94 seats on the valve seat 93, the ECU 10 prohibits further opening. Note that once the valve disc 94 seats on the valve seat 93 after the start request, the ECU 10 may prohibit further opening. In this case, the EGR valve 9 is fully opened at least once, which more reliably removes foreign matter. Such start requests include a restart request during a driving cycle and a start request for the next driving cycle immediately after the ignition switch is turned off, i.e., immediately after the current driving cycle.

[0035] As shown in Figure 7, the EGR valve 9 starts opening and closing at time t20. If a start request is made immediately after the second opening and closing operation of a predetermined number of times (e.g., three times) has started, the opening and closing operation ends when the valve closes at time t21, and then cranking starts at time t22. There is a certain delay 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, it is possible to ensure that the EGR valve 9 is fully closed when cranking starts.

[0036] FIG. 8 is a time chart showing an example of the opening and closing operation of the EGR valve 9 when the ignition switch is turned off during the opening and closing operation. The ECU 10 controls the EGR valve 9 so that the opening and closing operation continues even if the ignition switch is turned off during the opening and closing operation. As shown in FIG. 8, the opening and closing operation of the EGR valve 9 starts at time t30, and even if the ignition switch is turned off at time t31 during a predetermined number of opening and closing operations (e.g., three times), the predetermined number of opening and closing operations is completed. This makes it possible to reliably remove foreign matter caught in the EGR valve 9 and ensure startability in the next driving cycle.

[0037] 9 and 10 are flowcharts showing an example of processing executed by the ECU 10 when the vehicle ignition switch is turned on. The processing shown in these flowcharts starts when the ECU 10 is activated and is repeated at predetermined time intervals. As shown in FIG. 9, first, in step S1, it is determined whether or not the EGR valve 9 has been operated in the current driving cycle. If the result of step S1 is negative, the processing is terminated. If the result of 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. If the result of step S2 is negative, the processing is terminated. If the result of step S2 is positive, the processing proceeds to step S3. In step S3, it is determined whether or not the engine speed detected by the engine speed sensor 1a has changed from a state equal to or greater than the idle speed to 0 rpm. If the result of step S3 is negative, the processing is terminated. If the result of step S3 is positive, the processing proceeds to step S4, where the opening and closing operation of the EGR valve 9 is started.

[0038] Figure 10 is a modified example of Figure 9, and shows an example of processing for determining whether a jamming state has occurred on the condition that restart will fail. Explaining the processing different from Figure 9, in the processing of Figure 10, if the result in step S2 is affirmative, the processing proceeds to step S3A, where it is determined whether restart of the engine 1 in response to the restart request has failed after the engine speed has reached 0 rpm during the driving cycle. If the result in step S3A is negative, the processing ends, and if the result in step S3A is affirmative, the processing proceeds to step S4.

[0039] 11 is a flowchart showing an example of processing executed by the ECU 10 when a start request is made during the opening and closing operation of the EGR valve 9. The processing shown in this flowchart is repeated at predetermined time intervals during the opening and closing operation of the EGR valve 9. As shown in FIG. 11, in step S5, it is determined whether a start request has been made, and if the determination is negative, the processing is terminated, whereas if the determination is positive, the processing proceeds to step S6, where the opening and closing operation of the EGR valve 9 is stopped.

[0040] According to the embodiment of the present invention, the following advantageous effects can be achieved. (1) The device 100 includes an EGR valve 9 that adjusts the amount of exhaust gas recirculation (EGR) in an engine 1 mounted on a vehicle, a lift sensor 9a that detects a stuck state in the EGR valve 9, and an ECU 10 that controls the EGR valve 9 (FIGS. 1, 2, and 4). When the engine 1 stops with the vehicle's ignition switch on, the ECU 10 controls the EGR valve 9 to perform a predetermined number of opening and closing operations on the condition that the lift sensor 9a detects the stuck state (FIGS. 5 and S2 to S4 in FIG. 9). This allows the removal of foreign matter caught in the EGR valve 9 and ensures restartability when the engine stops during a driving cycle in which there is a high probability that a restart will be required immediately after the stop. Furthermore, by opening and closing the EGR valve 9 only when a stuck state is actually detected, it is possible to minimize the discomfort felt by the driver and the power consumption.

[0041] (2) When the rotation of the engine 1 stops with the ignition switch on, the ECU 10 controls the EGR valve 9 to perform an opening and closing operation on the condition that the engine 1 does not start despite a request to start the engine 1 (S2A, S4 in Fig. 6 and Fig. 10). If the restart fails, the ECU 10 determines whether a jam has occurred and opens and closes the EGR valve 9 according to the determination result, thereby further reducing the discomfort felt by the driver and the power consumption.

[0042] (3) When the ignition switch is turned off, the ECU 10 further controls the EGR valve 9 to open and close (Fig. 5). This allows the ECU 10 to eliminate any foreign matter trapped in the EGR valve 9 at the end of the current driving cycle, ensuring good startability in the next driving cycle.

[0043] (4) If a start request for the engine 1 is received during the opening and closing operation, the ECU 10 controls the EGR valve 9 to stop the opening and closing operation and close it (FIGS. 7 and 11). By stopping the opening and closing operation in response to the start request, the EGR valve 9 can be reliably brought to a fully closed state when cranking begins.

[0044] (5) The ECU 10 controls the EGR valve 9 so that it continues opening and closing even if the ignition switch is turned off during the opening and closing operation (Figure 8). This ensures that foreign matter caught in the EGR valve 9 is removed and ensures startability in the next driving cycle.

[0045] (6) 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 (FIGS. 9 and 10). 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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 to 8, etc., but these are merely examples for the purpose of explanation, and the specifications of the EGR valve are not limited to those exemplified.

[0050] 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]

[0051] 1 engine, 1a 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), 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 EGR valve that adjusts the amount of exhaust gas recirculation in an internal combustion engine mounted on a vehicle; a detection unit that detects a state in which a foreign object is caught in the EGR valve; a control unit that controls the EGR valve, The control unit controls the EGR valve to perform opening and closing operations a predetermined number of times when the rotation of the internal combustion engine stops while the ignition switch of the vehicle is on, on the condition that the jammed state is detected by the detection unit and the internal combustion engine does not start despite a start request of the internal combustion engine.

2. An EGR valve that adjusts the amount of exhaust gas recirculation in an internal combustion engine mounted on a vehicle; a detection unit that detects a state in which a foreign object is caught in the EGR valve; a control unit that controls the EGR valve, The control unit controls the EGR valve to perform opening and closing operations a predetermined number of times when the rotation of the internal combustion engine stops while the ignition switch of the vehicle is on, on the condition that the jammed state is detected by the detection unit, and controls the EGR valve to stop the opening and closing operations and close if a start request for the internal combustion engine is made during the opening and closing operations.

3. An EGR valve that adjusts the amount of exhaust gas recirculation of an internal combustion engine mounted on a vehicle; a detection unit that detects a state in which a foreign object is caught in the EGR valve; a control unit that controls the EGR valve, When the rotation of the internal combustion engine stops with the vehicle's ignition switch on, the control unit controls the EGR valve to perform opening and closing operations a predetermined number of times, provided that the detection unit detects the jammed state, and controls the EGR valve to continue the opening and closing operations even if the ignition switch is turned off during the opening and closing operations.

4. In the EGR valve control device according to any one of claims 1 to 3, The EGR valve control device is characterized in that the control unit further controls the EGR valve to perform the opening and closing operation when the ignition switch is turned off.

5. In the EGR valve control device according to any one of claims 1 to 3, The control unit controls the EGR valve to perform the opening and closing operation on the condition that the EGR valve is activated during operation of the internal combustion engine after the ignition switch is turned on.

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