EGR valve control device

Abstract

To early detect a catching state where a foreign matter is caught in an EGR valve to perform an opening / closing operation, and maintain a stable combustion state of an internal combustion engine.SOLUTION: An EGR valve control device 100 includes: an EGR valve 9 for adjusting an exhaust gas recirculation amount of an internal combustion engine mounted to a vehicle; an opening detection section 9a that detects an opening of the EGR valve 9; a catching determination section 11 that determines that a foreign matter is caught in the EGR valve when the opening detected by the opening detection section 9a is a predetermined opening or larger in the case where full closing of the EGR valve 9 is instructed in a combustion state of the internal combustion engine; and a valve control section 12 that controls the EGR valve 9 to perform an opening / closing operation when the catching determination section 11 determines that a foreign matter is caught in the EGR valve 9.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. A known technology related to this type of EGR valve is a device that removes foreign matter caught in the EGR valve by opening and closing the EGR valve (see, for example, Patent Document 1). In the device described in Patent Document 1, when foreign matter is caught in the EGR valve and the engine idle speed becomes unstable below a specified value, the device opens and closes the EGR valve during steady driving when fluctuations in engine speed and charging efficiency are below the specified value, or during deceleration at a speed or speed above the specified value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-287392 Summary of the Invention [Problem to be solved by the invention]

[0004] In the device described in Patent Document 1, the EGR valve is opened and closed only after the combustion state of the internal combustion engine becomes unstable. However, it is preferable to detect a state in which foreign matter is caught in the EGR valve early and perform the opening and closing operation to maintain a stable combustion state of the internal combustion engine. [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, an opening detection unit that detects the opening of the EGR valve, a jam determination unit that determines that foreign matter is jammed in the EGR valve when the opening detected by the opening detection unit is equal to or greater than a predetermined opening when a command to fully close the EGR valve is issued during combustion in the internal combustion engine, and a valve control unit that controls the EGR valve to perform opening and closing operations when the jam determination unit determines that foreign matter is jammed in the EGR valve. [Effects of the Invention]

[0006] According to the present invention, a state in which foreign matter is caught in the EGR valve can be detected early and an opening / closing operation can be performed, thereby maintaining a stable combustion state in the internal combustion engine. [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] 4 is a time chart showing an example of the operation of an EGR valve. [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] FIG. 2 is a diagram for explaining an operating region in which the opening and closing operation of the EGR valve during combustion in the engine of FIG. 1 is permitted. [Figure 6] 4 is a time chart showing an example of opening and closing operations during combustion. [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 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 also 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. The intake passage 3 is also provided with an intake amount sensor 3a that detects the flow rate (intake amount) of air supplied to the engine 1.

[0010] Exhaust gas discharged from the engine 1 into an exhaust passage 5 via an exhaust manifold 4 is purified by a catalytic converter 7 provided in the exhaust passage 5 and then released into the atmosphere. 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 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 (duty 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] FIG. 3 is a time chart showing an example of the operation of the EGR valve 9. EGR (exhaust gas recirculation) of the engine 1 is permitted, for example, when the engine water temperature has reached a predetermined water temperature. When EGR is permitted and the operating range of the engine 1, which is defined by the engine speed and load, enters a predetermined EGR range, a command is issued to open the EGR valve 9 (target lift amount > 0) (EGR ON). On the other hand, when the operating range of the engine 1 enters a predetermined non-EGR range, a command is issued to close the EGR valve 9 (target lift amount = 0) (EGR OFF). The engine load can be expressed, for example, as the amount of intake air into the engine 1.

[0018] The EGR region is defined as a high load region where the intake air volume is equal to or greater than a predetermined intake air volume, and the non-EGR region is defined as a low load region where the intake air volume is less than the predetermined intake air volume. The predetermined intake air volume is determined in advance through a combustion test of the engine 1. The predetermined intake air volume is, for example, an intake air volume corresponding to the accelerator opening (throttle opening) when the vehicle is traveling at a constant speed or when the vehicle is decelerating slowly enough that fuel cut-off during deceleration is not performed.

[0019] 3, when the accelerator pedal of the vehicle is released at times t1 and t4, the engine speed decreases, the vehicle decelerates, and the EGR is switched from on to off. When the EGR is switched from on to off and the EGR valve 9 is closed from an open state, foreign matter may become lodged in the EGR valve 9.

[0020] 2 and gets caught between the valve seat 93 and the valve element 94, the foreign matter becomes caught between the lower end of the valve seat 93 (through hole 93a) and the truncated conical surface of the valve element 94 when the valve element 94 moves upward (in the valve closing direction) in response to a valve close command. Alternatively, the foreign matter that has flowed in from the inlet side passage 91 and is passing between the valve seat 93 and the valve element 94 becomes caught between the lower end of the valve seat 93 (through hole 93a) and the truncated conical surface of the valve element 94.

[0021] In a state where foreign matter is caught in the EGR valve 9, the valve disc 94 seats on the valve seat 93 via the foreign matter, resulting in a larger lift amount compared to the lift amount (0 mm) when the valve disc 94 abuts on the valve seat 93 without any foreign matter in between. Examples of foreign matter that can become caught between the valve seat 93 and the valve disc 94 include deposits that are combustion products (oxides and carbides) contained in EGR gas and that have accumulated on the wall surfaces of gas flow paths such as the EGR passage 8, which have peeled off and become foreign matter.

[0022] When foreign matter is lodged in the EGR valve 9, it is not possible to fully close the EGR valve 9, and as a result, the EGR gas flows into the combustion chamber, making it impossible to ensure an appropriate air-fuel ratio in the non-EGR region, making it difficult to maintain a stable combustion state or restart the engine 1. By opening and closing the EGR valve 9, the foreign matter lodged in the EGR valve 9 can be dropped downward in the direction of gravity, i.e., toward the inlet-side passage 91 (Figure 2), or can be passed along with the EGR gas to the outlet-side passage 92.

[0023] The EGR valve 9 can be opened and closed during a deceleration fuel cutoff, in which the vehicle is decelerated and fuel supply to the engine 1 is cut off. Alternatively, the EGR valve 9 can be opened and closed during an idle stop, in which the engine 1 stops rotating while the vehicle ignition switch is on, or after the engine 1 has stopped operating and the ignition switch is turned off. When the EGR valve 9 is opened and closed during non-combustion periods when no fuel is supplied to the engine 1 and no combustion is occurring in the combustion chambers (opening and closing operations during non-combustion periods), exhaust gas after combustion does not flow into the combustion chambers as EGR gas and affect the combustion state of the engine 1. During the non-combustion opening and closing operations, for example, a target lift amount (0 mm → 5 mm → 0 mm) is commanded to the EGR valve 9 (solenoid 97) so that the valve element 94 (FIG. 2) reciprocates between a fully closed position and a fully open position, thereby eliminating the jammed state and ensuring restartability.

[0024] However, depending on the duration of the deceleration fuel cut (times t2 to t3 and t5 to t6 in FIG. 3), the EGR valve 9 may not be able to be opened or closed sufficiently, and the stuck state may not be resolved. Furthermore, if operation in the non-EGR range continues with foreign matter stuck in the EGR valve 9, the combustion state of the engine 1 may become unstable, and vibration or stall (stalling) may occur. Therefore, in this embodiment, the EGR valve control device is configured as follows so that the stuck state in which foreign matter is stuck in the EGR valve 9 is detected early and the opening and closing operation is performed to maintain a stable combustion state of the engine 1.

[0025] Fig. 4 is a block diagram showing an example of the configuration of a main part of an EGR valve control device (hereinafter referred to as 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, an intake air amount sensor 3a, a lift sensor 9a, and the EGR valve 9, 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, vehicle speed, and engine water temperature.

[0026] The ECU 10 is configured to include a computer having a processor such as a CPU, memories such as a ROM and a RAM, and other peripheral circuits. The ECU 10 has a jamming determination unit 11 and a valve control unit 12 as functional components, and functions as the jamming determination unit 11 and the valve control unit 12. 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, etc.

[0027] When a command to fully close the EGR valve 9 is issued, the jamming determination unit 11 determines whether or not a foreign object is jammed in the EGR valve 9 based on the lift amount detected by the lift sensor 9a. More specifically, the jamming determination unit 11 compares the lift amount with a predetermined threshold value, and determines that a foreign object is jammed in the EGR valve 9 when the lift amount is equal to or greater than the threshold value, and determines that no foreign object is jammed in the EGR valve 9 when the lift amount is less than the threshold value.

[0028] The threshold value for determining jamming is set to a different value during non-combustion when fuel is not being supplied to the engine 1 and combustion is not occurring in the combustion chamber, and during combustion when fuel is being supplied to the engine 1 and combustion is occurring in the combustion chamber. More specifically, the threshold value during combustion (combustion threshold value (e.g., 0.5 to 1.0 mm)) is set to a value greater than the threshold value during non-combustion (non-combustion threshold value (e.g., 0.1 to 0.3 mm)).

[0029] During non-combustion, it is necessary to restart combustion from a non-combustion state (restart). Restarting becomes difficult even if a small amount of exhaust gas flows into the combustion chamber. For this reason, during non-combustion, a relatively small lift amount that leads to a deterioration in restartability is used as the non-combustion threshold. On the other hand, during combustion, it is sufficient to maintain the existing combustion state, and even if more exhaust gas flows in than during restart, the engine 1 will not stall (stall) and the combustion state can be maintained. For this reason, during combustion, a relatively large lift amount that leads to a stall or an unacceptable deterioration in the combustion state is used as the combustion threshold.

[0030] When the jamming determination unit 11 determines that a foreign object is jammed in the EGR valve 9, the valve control unit 12 controls the EGR valve 9 to perform an opening and closing operation. The opening and closing operation of the EGR valve 9 includes an opening and closing operation performed during non-combustion (opening and closing operation during non-combustion) and an opening and closing operation performed during combustion (opening and closing operation during combustion). Of the opening and closing operations of the EGR valve 9, the opening and closing operation during combustion is performed on the condition that the operating range of the engine 1 is within a predetermined operating range.

[0031] FIG. 5 is a diagram for explaining an operating region in which opening and closing operations during combustion are permitted (opening and closing operation permitted region). As shown in FIG. 5, the opening and closing operation permitted region is predetermined as a low rotation region within a predetermined range of engine speed in the non-EGR region. Unlike opening and closing operations during non-EGR, opening and closing operations during combustion may cause exhaust gas after combustion to flow into the combustion chamber as EGR gas, which may affect the combustion state of the engine 1. In other words, performing opening and closing operations may cause EGR gas to flow into the combustion chamber, making it impossible to ensure an appropriate air-fuel ratio in the non-EGR region, which may make it impossible to maintain a stable combustion state of the engine 1.

[0032] In this case, the higher the engine speed, the easier it is to maintain the combustion state of the engine 1, but the opening and closing operation reduces the flow rate of EGR gas flowing into the combustion chamber. Also, the lower the engine speed, the smaller the flow rate of EGR gas flowing into the combustion chamber, but the more difficult it is to maintain the combustion state of the engine 1. The specified range of engine speeds in the opening and closing operation permitted region is determined in advance through combustion testing of the engine 1 as a range in which the combustion state can be maintained without stalling or unacceptable deterioration of the combustion state even when the opening and closing operation is performed.

[0033] Furthermore, the opening and closing operation during combustion is performed for a shorter time or with a smaller lift amount than the opening and closing operation during non-combustion in order to minimize the flow rate of EGR gas flowing into the combustion chamber due to the opening and closing operation. For example, the opening and closing operation during combustion is performed by maintaining the duty ratio of the energized time of the solenoid 97 (Fig. 2) at 100% for a predetermined time T (for example, about 25 to 30 msec) without performing feedback control of the EGR valve 9 according to the target lift amount.

[0034] By setting the duty ratio to 100%, it is possible to maximize the drive speed of the valve element 94 by the solenoid 97 (i.e., the opening speed of the EGR valve 9). In addition, by limiting the time during which the duty ratio is 100% to a predetermined time, it is possible to limit the maximum lift amount during opening and closing operations to a predetermined lift amount α (e.g., about 1 to 3 mm) that is smaller than the maximum lift amount (e.g., about 5 mm).

[0035] The predetermined lift amount for the opening / closing operation during combustion is determined in advance as the minimum value within a range that allows removal of foreign matter caught in the EGR valve 9. The predetermined time for the opening / closing operation during combustion is determined in advance as the time required for the EGR valve 9 to open to the predetermined lift amount when the duty ratio is set to 100%. This opening / closing operation during combustion can be performed more quickly than opening / closing operation during non-combustion. For example, in the opening / closing operation during non-combustion using feedback control, the valve opens to a lift amount of 5 mm in approximately 300 msec, whereas in the opening / closing operation during combustion, where the duty ratio is maintained at 100%, the valve can open to a predetermined lift amount α of approximately 1 to 3 mm in a predetermined time T of approximately 25 to 30 msec.

[0036] FIG. 6 is a time chart showing an example of opening and closing operations during combustion. In the example of FIG. 6, the solenoid 97 (FIG. 2) is turned on for a predetermined time T from time t10 to t11, the duty ratio is maintained at 100%, the valve element 94 is driven downward against the biasing force of the compression spring 96, and the EGR valve 9 is opened to a predetermined lift amount α. When the EGR valve 9 is opened to the predetermined lift amount α, foreign matter caught in the EGR valve 9 is removed. Thereafter, when the solenoid 97 is turned off, the compression spring 96 biases the valve element 94 upward, and the EGR valve 9 is closed to a lift amount of 0 mm from time t11 to t12, and then closed. By performing such opening and closing operations for a short period of time and with a limited maximum lift amount, the jammed state of the EGR valve 9 can be resolved without deteriorating the existing combustion state due to the opening and closing operations, and a stable combustion state can be maintained in the non-EGR region.

[0037] 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 a predetermined interval (for example, every few seconds). As shown in FIG. 7, first, in step S1, it is determined whether or not a command to close the EGR valve 9 (target lift amount=0) has been issued. If the result in step S1 is affirmative, the process proceeds to step S2, and if the result in step S1 is negative, the process ends. In step S2, it is determined whether or not fuel is being supplied to the engine 1 and combustion is occurring in the combustion chamber. If the result in step S2 is affirmative, the process proceeds to steps S3 to S5, and if the result in step S2 is negative, the process proceeds to steps S6 to S7.

[0038] In step S3, it is determined whether the lift amount of the EGR valve 9 detected by the lift sensor 9a is equal to or greater than the combustion threshold. If the result in step S3 is affirmative, it is determined that foreign matter is caught in the EGR valve 9, and the process proceeds to step S4. If the result in step S3 is negative, the process ends. In step S4, it is determined whether the operating range of the engine 1 is within the opening / closing operation permitted range (FIG. 5) based on the engine speed detected by the speed sensor 1a and the intake air amount detected by the intake air amount sensor 3a. If the result in step S4 is affirmative, the process proceeds to step S5, where the EGR valve 9 is controlled to perform opening and closing operations during combustion. If the result in step S4 is negative, the process ends.

[0039] In step S6, it is determined whether the lift amount of the EGR valve 9 detected by the lift sensor 9a is equal to or greater than the non-combustion threshold. If the result in step S6 is YES, it is determined that a foreign object is caught in the EGR valve 9, and the process proceeds to step S7, where the EGR valve 9 is controlled to perform the opening and closing operation during non-combustion. If the result in step S6 is NO, the process ends.

[0040] As a result, for example, if the operating range of the engine 1 shifts from the EGR range (FIG. 5) to the non-EGR range and a relatively large foreign object becomes lodged when the EGR valve 9 is closed from an open state, the lodged state of the foreign object is immediately detected (S1 to S3). By determining the lodged state based on the lift amount during combustion in the engine 1, the lodged state of the foreign object in the EGR valve 9 can be detected early.

[0041] At this time, if the operating range of the engine 1 is within the opening / closing operation permitted range, the opening / closing operation during combustion is immediately performed, and the jammed state is resolved (S4 to S5). If the operating range of the engine 1 is not within the opening / closing operation permitted range at the time the jammed state is determined, when the operating range of the engine 1 returns from the non-EGR range to the EGR range in response to the accelerator opening of the vehicle (No in S4 → No in S1), the jammed state is resolved regardless of the opening / closing operation. Alternatively, when the operating range of the engine 1 enters the opening / closing operation permitted range in response to a decrease in engine speed, the opening / closing operation during combustion is immediately performed, and the jammed state is resolved (S4 to S5). By detecting the jammed state during combustion in the engine 1 early and resolving the jammed state by the opening / closing operation during combustion, a stable combustion state of the engine 1 can be maintained.

[0042] Also, for example, if a relatively small foreign object is lodged when the engine 1 enters deceleration fuel cutoff while the operating range of the engine 1 is shifting from the EGR range to the non-EGR range, such a lodged state is detected and the non-combustion opening / closing operation is performed to eliminate the lodged state (No in S3 → S2, S6 to S7). By eliminating the lodged state by the non-combustion opening / closing operation during non-combustion in the engine 1, restartability can be ensured. The non-combustion opening / closing operation can also be performed during an idle stop of the vehicle or after the operation of the engine 1 has ended and the vehicle ignition switch has been turned off.

[0043] 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 lift amount of a valve element 94 corresponding to the opening of the EGR valve 9, a jam determination unit 11 that determines that foreign matter is trapped in the EGR valve 9 when a command to fully close the EGR valve 9 (EGR off) is issued during combustion in the engine 1 if the lift amount detected by the lift sensor 9a is equal to or greater than a combustion threshold, and a valve control unit 12 that controls the EGR valve 9 to perform an opening or closing operation when the jam determination unit 11 determines that foreign matter is trapped in the EGR valve 9 (steps S1 to S3 and S5 in FIGS. 4 and 7). By performing jam determination based on the lift amount during combustion in the engine 1 in this manner, a jammed state in which foreign matter is trapped in the EGR valve 9 can be detected early and the jammed state can be detected and the opening or closing operation can be performed, thereby maintaining a stable combustion state of the engine 1.

[0044] (2) When a command to fully close the EGR valve 9 is issued during non-combustion, i.e., when combustion is not occurring in the engine 1, the jamming determination unit 11 determines that a foreign object is jammed in the EGR valve 9 if the lift amount is equal to or greater than a non-combustion threshold (e.g., 0.1 to 0.3 mm). When a command to fully close the EGR valve 9 is issued during combustion, the jamming determination unit 11 determines that a foreign object is jammed in the EGR valve 9 if the lift amount is equal to or greater than a combustion threshold (e.g., 0.5 to 1.0 mm), which is greater than the non-combustion threshold (FIG. 7). That is, during non-combustion, when combustion needs to be restarted from a non-combustion state, a relatively small lift amount that leads to poor restartability is used as the non-combustion threshold. On the other hand, during combustion, when it is sufficient to maintain the existing combustion state, a relatively large lift amount that leads to engine stalling or unacceptable deterioration of the combustion state is used as the combustion threshold.

[0045] When the EGR valve 9 is opened or closed, the sound of the valve disc 94 seating on the valve seat 93 and the sound of the solenoid 97 operating may be generated, causing discomfort to the driver. In addition, a certain amount of power is consumed by the operation of the solenoid 97. By using a threshold value that is necessary and sufficient to determine the jammed state and 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] (3) The valve control unit 12 controls the EGR valve 9 during combustion so that the opening and closing speed of the opening and closing operation is faster or the amount of change in the lift is smaller than during non-combustion. The opening and closing operation during combustion differs from the opening and closing operation during non-combustion in that exhaust gas after combustion may flow into the combustion chamber as EGR gas, affecting the combustion state of the engine 1. By controlling the EGR valve 9 during combustion so that the opening and closing speed of the opening and closing operation is faster or the amount of change in the lift is smaller than during non-combustion, the flow rate of EGR gas flowing into the combustion chamber of the engine 1 during the opening and closing operation can be minimized.

[0047] (4) When exhaust gas recirculation is performed in the engine 1 (for example, when EGR is enabled in a warm-up state where the engine water temperature has reached a predetermined water temperature), the EGR valve 9 is commanded to open (target lift amount > 0) in the EGR region, and is commanded to close (target lift amount = 0) in the non-EGR region where the load is lower than the EGR region (FIG. 5). During combustion, the valve control unit 12 controls the EGR valve 9 to open and close, provided that the operating region of the engine 1 is the non-EGR region and the engine speed is within a predetermined range below a predetermined speed (step S4 in FIG. 7).

[0048] Unlike the opening and closing operation during non-combustion, the opening and closing operation during combustion may cause exhaust gas after combustion to flow into the combustion chamber as EGR gas, affecting the combustion state of the engine 1. In this case, the higher the engine speed, the easier it is to maintain the combustion state of the engine 1, but the flow rate of EGR gas flowing into the combustion chamber due to the opening and closing operation becomes less. By performing the opening and closing operation at or below a predetermined speed that is determined in advance as a range in which the combustion state can be maintained without causing the engine to stall or an unacceptable deterioration in the combustion state, a stable combustion state of the engine 1 can be maintained even during the opening and closing operation.

[0049] 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.

[0050] 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 opening and closing the valve. When a butterfly valve is used, the valve opening degree can be detected by an angle sensor instead of a lift sensor.

[0051] In the above embodiment, the non-combustion threshold value and the combustion threshold value for determining whether the EGR valve 9 is jammed are described as examples, but these are merely examples for the purpose of explanation, and the opening degree for determining whether the EGR valve 9 is jammed is not limited to the examples.

[0052] In the above embodiment, specific examples of the opening and closing operation during combustion are described using FIG. 6 and the like. However, the EGR valve may be controlled so that the opening and closing speed is faster during combustion than during non-combustion, or so that the amount of change in the opening degree is smaller, and the control method at this time is not limited to the example.

[0053] 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]

[0054] 1 engine, 1a rotation speed sensor, 2 intake manifold, 3 intake passage, 3a intake air amount sensor, 4 exhaust manifold, 5 exhaust passage, 6 throttle valve, 7 catalytic device, 8 EGR passage, 9 EGR valve, 9a lift sensor, 10 ECU (electronic control unit), 11 jamming determination unit, 12 valve control unit, 90 valve body, 91 inlet side passage, 92 outlet side passage, 93 valve seat, 93a through hole, 94 valve body, 95 valve stem, 95a spring receiver, 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; an opening detection unit that detects an opening of the EGR valve; a jam determination unit that determines that a foreign object is jammed in the EGR valve when the opening detected by the opening detection unit is equal to or greater than a predetermined opening when a command to fully close the EGR valve is issued during combustion in the internal combustion engine; and and a valve control unit that controls the EGR valve to perform an opening and closing operation when the jamming determination unit determines that a foreign object is jammed in the EGR valve.

2. The EGR valve control device according to claim 1, The EGR valve control device is characterized in that the jamming determination unit determines that foreign matter is jammed in the EGR valve when a command to fully close the EGR valve is issued during non-combustion when combustion is not occurring in the internal combustion engine and the opening degree is equal to or greater than a first opening degree, and when a command to fully close the EGR valve is issued during combustion and the opening degree is equal to or greater than a second opening degree that is greater than the first opening degree.

3. 3. The EGR valve control device according to claim 2, The valve control unit controls the EGR valve so that, during combustion, the opening / closing speed of the opening / closing operation is faster or the amount of change in the opening degree is smaller than during non-combustion.

4. The EGR valve control device according to claim 3, When exhaust gas recirculation is performed in the internal combustion engine, a command to open the EGR valve is issued in a first operating region, and a command to close the EGR valve is issued in a second operating region having a lower load than the first operating region, The EGR valve control device is characterized in that, during the combustion, the valve control unit controls the EGR valve to perform the opening and closing operation on the condition that the operating region of the internal combustion engine is the second operating region.

5. 5. The EGR valve control device according to claim 4, The valve control unit is further configured to control the EGR valve to perform the opening and closing operation during the combustion, on the condition that the rotation speed of the internal combustion engine is equal to or lower than a predetermined rotation speed.

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