EGR control device for internal combustion engine

Abstract

To suppress occurrence of knocking in a situation where a recirculation gas amount cannot be secured.SOLUTION: In an EGR control device for an internal combustion engine, a control section 73 performs control so as to increase an opening of an EGR valve 52 by predetermined amount when a request for recirculation gas is made and a knocking determination section 71 determines knocking and so as not to request the recirculation gas when the knocking determination section 71 determines knocking after a predetermined time elapses after the opening of the EGR valve 52 is increased. Due to this configuration, in a situation where the recirculation gas amount cannot be secured, occurrence of knocking can be suppressed.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an EGR control device for an internal combustion engine. [Background technology]

[0002] Conventionally, an exhaust gas recirculation (EGR) device is known that can suppress the generation of nitrogen oxides and improve fuel efficiency by recirculating a part of exhaust gas to an intake passage and combusting it in a combustion chamber. In general, in an internal combustion engine of a vehicle having an EGR device, a correction control is performed to advance the ignition timing according to an estimated amount of recirculated gas.

[0003] Deposits can build up in the EGR passage through which the recirculated gas flows. If the amount of recirculated gas decreases due to deposits in the EGR passage, the amount of recirculated gas estimated based on the control device's required value will diverge from the actual amount of recirculated gas, causing the engine to fail to ignite at the appropriate time, resulting in knocking.

[0004] Patent Document 1 discloses a knocking control device having a knocking detection means for detecting knocking in an internal combustion engine, an exhaust gas recirculation passage for recirculating a portion of exhaust gas to the fuel supply side, and a recirculation amount adjustment means for adjusting the amount of recirculation of exhaust gas flowing through the exhaust gas recirculation passage in response to the detection result of the knocking detection means. The recirculation amount adjustment means of the knocking control device of Patent Document 1 is configured to suppress knocking by increasing the amount of recirculated exhaust gas when the knocking detection means detects knocking. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-158927 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the knocking control device in Patent Document 1 does not take into consideration the case where the amount of deposits accumulated is so large that it blocks the EGR passage. In other words, when deposits are accumulated in the EGR passage, even if the EGR valve is opened to increase the amount of recirculated gas, the amount of recirculated gas cannot be secured, and the occurrence of knocking cannot be suppressed.

[0007] The present invention has been made in consideration of the above-mentioned problems, and has an object to suppress the occurrence of knocking in a situation in which the amount of recirculated gas cannot be secured. [Means for solving the problem]

[0008] The present invention is an EGR control device for an internal combustion engine comprising an EGR passage for recirculating a portion of exhaust gas to an intake passage, an EGR valve provided in the EGR passage, and a control unit for controlling the amount of recirculated gas recirculated to the intake passage by opening the EGR valve based on a request for recirculated gas, and further comprising a knocking determination unit for determining the occurrence of knocking in the internal combustion engine, wherein the control unit increases the opening of the EGR valve by a predetermined amount when there is a request for recirculated gas and knocking has been determined by the knocking determination unit, and controls so as not to request recirculated gas if knocking has been determined by the knocking determination unit after a predetermined time has elapsed since the opening of the EGR valve was increased. Effect of the Invention

[0009] According to the present invention, it is possible to suppress the occurrence of knocking in a situation in which the amount of recirculated gas cannot be secured. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a vehicle. [Diagram 2] FIG. 2 is a diagram illustrating an example of a functional configuration of a control device. [Diagram 3]5 is a flowchart showing an example of a process performed by a control device. [Figure 4] 4 is a timing chart showing a process performed by the control device. [Diagram 5] 4 is a timing chart showing a process performed by the control device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The EGR control device according to the embodiment of the present invention includes an EGR passage 51 for recirculating a portion of exhaust gas to the intake passage 21, an EGR valve 52 provided in the EGR passage 51, a control unit 73 for controlling the amount of recirculated gas recirculated to the intake passage 21 by opening the EGR valve 52 based on a request for recirculated gas, and a knocking determination unit 71 for determining the occurrence of knocking in the engine 10. When there is a request for recirculated gas and the knocking determination unit 71 has determined that knocking has occurred, the control unit 73 increases the opening degree of the EGR valve 52 by a predetermined amount, and when the knocking determination unit 71 has determined that knocking has occurred after a predetermined time has elapsed since the opening degree of the EGR valve 52 has been increased, the control unit 73 controls so as not to request recirculated gas, thereby making it possible to suppress the occurrence of knocking in a situation in which the amount of recirculated gas cannot be secured. The EGR control device according to the embodiment of the present invention includes an EGR passage 51 that recirculates a portion of exhaust gas to the intake passage 21, an EGR valve 52 provided in the EGR passage 51, a control unit 73 that controls the amount of recirculated gas recirculated to the intake passage 21 by opening the EGR valve 52 based on a request for recirculated gas, and an EGR valve opening sensor 64 that detects the opening of the EGR valve 52. When the opening of the EGR valve 52 based on the request for recirculated gas is smaller than a predetermined opening, the control unit 73 controls the EGR valve 52 so as not to request recirculated gas, thereby making it possible to suppress the occurrence of knocking in a situation in which the amount of recirculated gas cannot be secured. EXAMPLES

[0012] An EGR control device for an internal combustion engine according to the present invention will now be described with reference to the drawings. Fig. 1 is a diagram showing a schematic configuration of a vehicle 1 as an EGR control device for an internal combustion engine. Note that Fig. 1 is simplified for the sake of convenience in explaining the present embodiment, and components that are normally provided in a vehicle are assumed to be provided even if they are not shown in the figure. The vehicle 1 in the embodiment is equipped with an engine 10 as an internal combustion engine, an intake system 20 that takes in intake air for combustion in the engine 10, an exhaust system 30 that discharges exhaust gas from the engine 10 to the outside, an exhaust gas recirculation device (EGR device) 50, a sensor unit 60, a control device 70, etc.

[0013] Engine 10 performs a series of four strokes consisting of an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke. Engine 10 has a combustion chamber 12 in which a piston 11 is housed so as to be capable of reciprocating, a crank chamber 14 in which a crankshaft 13 is housed so as to be rotatable, an intake port 15 which is an inlet for air to be used for combustion, and an exhaust port 16 which is an outlet for exhaust gas. Engine 10 also has an ignition plug 17 arranged so that its tip is located within combustion chamber 12, an intake valve 18 located between combustion chamber 12 and intake port 15, and an exhaust valve 19 located between combustion chamber 12 and exhaust port 16.

[0014] During the intake stroke, the piston 11 descends from the top dead center to the bottom dead center, the intake valve 18 opens, and the exhaust valve 19 closes. As the piston 11 descends, the mixture of intake air and fuel flows from the intake system 20 into the combustion chamber 12. In the compression stroke, the piston 11 moves upward from the bottom dead center to the top dead center, and the intake valve 18 and the exhaust valve 19 are closed. As the piston 11 moves upward, the air-fuel mixture is compressed. During the combustion stroke, the compressed air-fuel mixture is ignited by the spark plug 17 and combusted, pushing the piston 11 down, causing it to move from the top dead center to the bottom dead center. During the exhaust stroke, the piston 11 rises from the bottom dead center to the top dead center, the intake valve 18 closes, and the exhaust valve 19 opens. As the piston 11 rises, exhaust gas generated during the combustion stroke is discharged into the exhaust system 30.

[0015] As the engine 10 repeats a series of processes, driving force is transmitted from the engine 10 to the drive wheels via the crankshaft 13, causing the vehicle to run. Note that the configuration of the engine 10 is not particularly limited, and various known engines can be applied. Furthermore, the engine 10 may be either a gasoline engine or a diesel engine.

[0016] The intake system 20 includes an intake passage 21, an air cleaner 23, and a throttle valve 24. The intake passage 21 is a passage that guides intake air taken in from outside the vehicle 1 to the combustion chamber 12 via the intake port 15. The intake passage 21 is mainly composed of an intake pipe 22. The air cleaner 23 is disposed in the intake passage 21, and purifies the intake air by removing foreign matter such as dust and dirt contained in the intake air. The throttle valve 24 is disposed in the intake passage 21, and adjusts the flow rate of the intake air by opening and closing. The throttle valve 24 adjusts the flow rate of the intake air based on the control of the control device 70.

[0017] The exhaust system 30 includes an exhaust passage 31 and a catalyst (catalytic converter) 33. The exhaust passage 31 is a passage that exhausts exhaust gas burned in the combustion chamber 12 to the outside of the vehicle 1 via the exhaust port 16. The exhaust passage 31 is mainly composed of an exhaust pipe 32. The catalyst 33 purifies harmful substances contained in the exhaust gas. For example, various known three-way catalysts and the like can be used for the catalyst 33.

[0018] Fuel system 40 supplies fuel to engine 10. Fuel system 40 includes a fuel tank, a fuel pump, and a fuel injector 41. The fuel pump supplies fuel stored in the fuel tank to fuel injector 41. Fuel injector 41 injects the fuel supplied from the fuel tank into intake passage 21. Fuel injector 41 adjusts the amount of fuel injected based on the control of control device 70. Furthermore, fuel injector 41 is not limited to injecting fuel into intake passage 21, and may be configured to inject fuel into combustion chamber 12 or intake port 15.

[0019] The exhaust gas recirculation device 50 recirculates a part of the exhaust gas combusted in the combustion chamber 12 to the intake passage 21 as recirculated gas, and combusts the exhaust gas again in the combustion chamber 12. The exhaust gas recirculation device 50 has an EGR passage 51 and an EGR valve 52. The EGR passage 51 communicates between the intake passage 21 and the exhaust passage 31, and recirculates a portion of the exhaust gas to the intake passage 21. Here, the exhaust gas flowing through the EGR passage 51 is recirculated gas. One end of the EGR passage 51 is connected to the exhaust pipe 32 downstream of the catalyst 33, and the other end is connected to the intake pipe 22 at a position between the throttle valve 24 and the engine 10.

[0020] The EGR valve 52 is disposed in the EGR passage 51, and opens and closes to adjust the amount of recirculated gas that flows back from the exhaust passage 31 to the intake passage 21. The EGR valve 52 adjusts the amount of recirculated gas based on the control of the control device 70. The exhaust gas recirculation device 50 may be provided with an EGR cooler in the EGR passage 51 for cooling the recirculated gas.

[0021] The sensor unit 60 detects the state of the vehicle 1 and transmits the detection result to the control device 70 (see also FIG. 2). The sensor unit 60 has a knock sensor 61, a crank angle sensor 62, an engine speed sensor 63, an EGR valve opening sensor 64, a coolant temperature sensor 65, an air flow sensor 66, a throttle valve opening sensor 67, etc. The sensor unit 60 also has sensors that the vehicle 1 normally has, such as an accelerator opening sensor and an intake pressure sensor.

[0022] The knock sensor 61 detects the frequency of vibrations of the engine 10 and transmits information on the detected frequency to the control device 70. When abnormal combustion such as knocking occurs during the compression stroke or combustion stroke of the engine 10, a frequency different from the frequency during normal combustion is detected. Based on the signal transmitted from the knock sensor 61, the control device 70 determines whether or not abnormal combustion such as knocking is occurring in the engine 10.

[0023] The crank angle sensor 62 detects the crank angle (the rotation angle of the crankshaft 13) and transmits information about the detected crank angle to the control device 70. The control device 70 controls the ignition timing of the spark plug 17 based on the information about the crank angle detected by the crank angle sensor 62.

[0024] The engine speed sensor 63 detects the engine speed and transmits information on the detected engine speed to the control device 70. The control device 70 calculates the required amount of recirculated gas and the like based on the information transmitted from the engine speed sensor 63.

[0025] The EGR valve opening sensor 64 detects the EGR valve opening of the EGR valve 52, and transmits information on the detected EGR valve opening to the control device 70. The control device 70 controls the EGR valve opening of the EGR valve 52 based on the information transmitted from the EGR valve opening sensor 64.

[0026] The cooling water temperature sensor 65 detects the temperature of the cooling water and transmits information on the detected temperature to the control device 70. The control device 70 executes exhaust gas recirculation (EGR) by the exhaust gas recirculation device 50 based on the information transmitted from the cooling water temperature sensor 65.

[0027] The airflow sensor 66 detects the amount of intake air, and transmits information about the detected amount of intake air to the control device 70. The control device 70 controls the exhaust gas recirculation device 50 based on the information transmitted from the airflow sensor 66.

[0028] The control device 70 controls the entire vehicle 1. For example, an ECU (Electronic Control Unit) can be used as the control device 70. The control device 70 has a CPU, a ROM, a RAM, etc. as a hardware configuration. The ROM stores programs and predetermined information for controlling the vehicle 1, the engine 10, etc. The RAM is a work memory, and temporarily stores programs and data. The CPU reads out the programs stored in the ROM, expands them in the RAM, and executes them to control the vehicle 1, the engine 10, the exhaust gas recirculation device 50, etc.

[0029] FIG. 2 is a diagram showing an example of a functional configuration of the control device 70. As shown in FIG. The control device 70 has a knocking determination unit 71, an EGR request unit 72, and a control unit 73. The knocking determination unit 71 detects abnormal combustion based on a signal from the knock sensor 61. Specifically, the knocking determination unit 71 determines that knocking is occurring when the frequency detected by the knock sensor 61 is greater than a threshold value.

[0030] The EGR request unit 72 requests exhaust gas recirculation (EGR) from the control unit 73 when the state of the engine 10 satisfies a predetermined condition. Specifically, the EGR request unit 72 requests EGR from the control unit 73 when the cooling water temperature is equal to or higher than a predetermined temperature. The EGR request unit 72 continues to request EGR from the control unit 73 while the predetermined condition is satisfied.

[0031] The control unit 73 controls the entire vehicle 1. The control unit 73 controls the fuel injector 41 to inject fuel at a fuel injection amount obtained by correcting a reference fuel injection amount calculated according to the engine speed detected by the engine speed sensor 63 and the intake amount detected by the air flow sensor 66 based on information from various sensors.

[0032] When EGR is requested by the EGR request unit 72, the control unit 73 performs EGR by controlling the exhaust gas recirculation device 50. Specifically, the control unit 73 recirculates the recirculated gas to the intake passage 21 by opening the EGR valve 52 based on the requested recirculated gas amount. At this time, the control unit 73 advances the ignition timing of the spark plug 17. Furthermore, the control unit 73 of this embodiment performs control so as to suppress the occurrence of knocking when EGR is performed, even in a situation in which the amount of recirculated gas cannot be secured.

[0033] Next, an example of processing by the control device 70 will be described with reference to the flowchart of Fig. 3. The flowchart of Fig. 3 is realized, for example, by the ECU, which is the control device 70, executing a program. The flowchart of Fig. 3 is started when the engine 10 is started.

[0034] In S1, the control unit 73 determines whether or not EGR is required. Specifically, the EGR request unit 72 determines whether or not the temperature detected by the cooling water temperature sensor 65 is equal to or higher than a predetermined temperature, and if it is equal to or higher than the predetermined temperature, requests EGR from the control unit 73. If EGR is required, the process proceeds to S2, and if EGR is not required, the process waits in S1 until EGR is required.

[0035] In S2, the control unit 73 executes EGR. Specifically, the control unit 73 calculates a required recirculation gas amount based on the engine speed detected by the engine speed sensor 63 and the engine load calculated by the intake air amount detected by the air flow sensor 66 and the throttle valve opening detected by the throttle valve opening sensor 67. The control unit 73 opens the EGR valve 52 so that the target opening degree corresponds to the calculated required recirculation gas amount. Note that the control device 70 stores in advance information on a map in which the engine speed, the engine load, and the required recirculation gas amount are associated with each other. The control unit 73 calculates the required recirculation gas amount by referring to the map, and opens the EGR valve 52 so that the target opening degree corresponds to the calculated required recirculation gas amount. Note that the map may associate the engine speed, the engine load, and the target opening degree of the EGR valve 52. Furthermore, the control unit 73 controls the ignition timing of the spark plug 17 to be advanced based on information about the crank angle detected by the crank angle sensor 62 .

[0036] In S3, the control unit 73 determines whether the valve opening of the EGR valve 52 is opened to a predetermined opening degree or more. Specifically, the control unit 73 determines whether the valve opening degree detected by the EGR valve opening sensor 64 is equal to or greater than the predetermined opening degree. Note that information on the predetermined opening degree is stored in advance in the control device 70. Normally, the EGR valve 52 opens, and therefore the valve opening degree is equal to or greater than the predetermined opening degree. On the other hand, in cases where the EGR valve 52 is stuck due to deposits adhering to it, the valve opening degree may be less than the predetermined opening degree. If the valve opening is equal to or larger than the predetermined opening, the process proceeds to S4, and if it is less than the predetermined opening, the process proceeds to S7.

[0037] In S4, the knocking determination unit 71 determines whether knocking occurs in the engine 10. Specifically, the knocking determination unit 71 determines that knocking occurs when the frequency detected by the knock sensor 61 is equal to or higher than a threshold value. By opening the EGR valve 52 in S3, a part of the exhaust gas mixes with the intake air as recirculated gas and flows into the combustion chamber 12, thereby lowering the combustion temperature in the combustion stroke. Therefore, knocking can be prevented under normal circumstances. On the other hand, in cases where deposits are attached to the EGR passage 51 and the amount of recirculated gas cannot be secured, knocking may not be prevented due to the insufficient amount of recirculated gas. If it is determined that knocking is occurring, the process proceeds to S5, and if it is determined that knocking is not occurring, the process returns to S1.

[0038] In S5, the control unit 73 opens the EGR valve 52 so as to increase the valve opening of the EGR valve 52 by a predetermined amount. When proceeding from S4 to S5, since there is a possibility that the amount of recirculated gas is insufficient, the valve opening of the EGR valve 52 is increased to ensure the amount of recirculated gas.

[0039] In S6, the knocking determination unit 71 determines whether or not the knocking has improved after a predetermined time has elapsed. Specifically, the knocking determination unit 71 determines whether or not the vibration frequency detected by the knock sensor 61 is equal to or greater than a threshold value after a predetermined time has elapsed since the valve opening of the EGR valve 52 was increased in S5. Here, the predetermined time may be, for example, the time from when the valve opening of the EGR valve 52 is increased until the increased amount of recirculated gas reaches the combustion chamber 12. If it is determined that the knocking has not been improved (knocking is occurring), the process proceeds to S7, and if it is determined that knocking is not occurring, the process returns to S1.

[0040] In S7, the control unit 73 does not request recirculation gas and sets the requested recirculation gas amount to 0. That is, the control unit 73 closes the EGR valve 52 in response to the requested recirculation gas amount being 0. Furthermore, the control unit 73 controls the ignition timing of the spark plug 17, which has been advanced, to be returned to its original state based on information about the crank angle detected by the crank angle sensor 62. Note that in S7, there are cases where the process branches from S6 to NO and proceeds to S7, and cases where the process branches from S3 to NO and proceeds to S7.

[0041] The process proceeds from S6 to S7 when the knocking has not improved even though the EGR valve 52 has been opened to increase the valve opening of the EGR valve 52 by a predetermined amount. In this case, it can be assumed that the amount of recirculated gas cannot be secured due to deposits adhering to the EGR passage 51, and therefore it is unlikely that the knocking can be eliminated even if EGR is continued. Therefore, by stopping EGR in S7 and returning the ignition timing of the spark plug 17, which was advanced, to its original timing, the occurrence of knocking can be suppressed because ignition is performed at the appropriate timing.

[0042] FIG. 4 is a timing chart assuming that S1, S2, and S3 in the flowchart of FIG. 3 are branched to YES and the process proceeds to S4, S5, S6, and S7. Note that the larger the numerical value of the recirculated gas amount, the larger the recirculated gas amount. The dashed line indicates the required recirculated gas amount, and the solid line indicates the actual recirculated gas amount. Also, the larger the numerical value of the EGR valve opening degree, the larger the opening degree. As shown in FIG. 4, at time T0, an EGR request is made, and the EGR valve opening degree changes from 0 to 2, and the ignition timing advances. Here, although the requested recirculation gas amount is 2, the actual recirculation gas amount is only 1 because of deposits in the EGR passage 51, and knocking occurs. Therefore, at time T1, the EGR valve opening degree is increased from 2 to 3 to ensure recirculation gas. Since the knocking has not been improved even at time T2, which is a predetermined time after time T1, EGR is not requested at time T2, and the requested recirculation gas amount is set to 0, the EGR valve opening degree becomes 0, and the ignition timing returns to the original state. As a result, the occurrence of knocking can be suppressed.

[0043] On the other hand, the process proceeds from S3 to S7 when the EGR valve 52 is not opened beyond a predetermined opening degree despite an attempt to open it. In this case, it can be assumed that the EGR valve 52 is stuck due to deposits adhering thereto, and the opening and closing of the EGR valve 52 cannot be controlled, and therefore there is no prospect of controlling the EGR. Therefore, by stopping the EGR and returning the ignition timing of the spark plug 17, which was advanced in S7, to its original state, the spark is ignited at the appropriate timing, and the occurrence of knocking can be suppressed.

[0044] Figure 5 is a timing chart assuming that S1, S2, and S3 in the flow chart of Figure 3 are branched to NO and the flow proceeds to S7. Note that the larger the numerical value of the EGR valve opening degree, the larger the opening degree. The dashed line indicates the opening degree based on the required recirculation gas amount, and the solid line indicates the actual opening degree. As shown in Fig. 5, when an EGR request is made at time T3, the EGR valve opening changes from 0 to 1 and the ignition timing advances. Here, although the EGR valve opening based on the requested recirculation gas amount is 2, the actual EGR valve opening is only 1, which is smaller than the predetermined opening, because the EGR valve 52 is stuck due to deposits, and knocking occurs. Therefore, by not requesting EGR at time T4 and setting the requested recirculation gas amount to 0, the EGR valve opening becomes 0 and the ignition timing returns to the original state. As a result, the occurrence of knocking can be suppressed.

[0045] When the process of S7 ends, the flowchart of Fig. 3 ends. When the process proceeds to S7, the control device 70 may notify an occupant or a vehicle mechanic, etc., of the fact that there is a problem with performing EGR via a notification unit such as a display, a warning light, or a speaker. When the process proceeds to S7, the control device 70 may turn on an EGR failure flag and not perform the process of the flowchart of Fig. 3 and EGR until an operator such as a mechanic maintains the exhaust gas recirculation device 50 and turns off the EGR failure flag.

[0046] Thus, according to this embodiment, when there is a request for recirculated gas and knocking determination unit 71 has determined that knocking has occurred, control unit 73 increases the opening of EGR valve 52 by a predetermined amount to increase the opening of EGR valve 52. If knocking determination unit 71 has determined that knocking continues to occur after a predetermined time has elapsed, control unit 73 performs control so as not to request recirculated gas. Therefore, the ignition timing of spark plug 17, which had been advanced, is returned to its original state, thereby making it possible to suppress the occurrence of knocking. According to this embodiment, the control unit 73 controls the EGR valve 52 so as not to request recirculation gas when the opening of the EGR valve 52 based on the request for recirculation gas is smaller than a predetermined opening. Therefore, the ignition timing of the spark plug 17 that was advanced is returned to the original timing, thereby making it possible to suppress the occurrence of knocking in a situation where the amount of recirculation gas cannot be secured.

[0047] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and modifications and the like are possible within the scope of the present invention. [Explanation of symbols]

[0048] 1: Vehicle 10: Engine 11: Piston 12: Combustion chamber 13: Crankshaft 17: Spark plug 18: Intake valve 19: Exhaust valve 20: Intake system 30: Exhaust system 40: Fuel system 50: Exhaust gas recirculation (EGR) device 51: EGR passage 52: EGR valve 61: Knock sensor 64: EGR valve opening sensor 70: Control device 71: Knocking determination unit 72: EGR request unit 73: Control unit

Claims

1. an EGR passage for recirculating a portion of the exhaust gas to the intake passage; an EGR valve provided in the EGR passage; a control unit that controls an amount of recirculated gas recirculated to the intake passage by opening the EGR valve based on a request for recirculated gas, A knocking determination unit that determines the occurrence of knocking in the internal combustion engine, The control unit is When there is a request for recirculation gas and knocking is determined by the knocking determination unit, the opening degree of the EGR valve is increased by a predetermined amount, 1. An EGR control device comprising: an EGR valve that is opened at a predetermined time and, if knocking is determined to occur by the knocking determination unit, performs control so as not to request recirculated gas.

2. an EGR passage for recirculating a portion of the exhaust gas to the intake passage; an EGR valve provided in the EGR passage; a control unit that controls an amount of recirculated gas recirculated to the intake passage by opening the EGR valve based on a request for recirculated gas, An opening sensor that detects the opening of the EGR valve is further provided, The control unit is 1. An EGR control device comprising: an EGR valve that controls an EGR valve so as not to request recirculation gas when the opening of the EGR valve based on a request for recirculation gas is smaller than a predetermined opening.

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