JP6540239B2 - Engine control device - Google Patents

Description

  The present invention relates to a control device of an engine provided with an exhaust gas recirculation device.

  An engine mounted on a vehicle or the like is often equipped with an exhaust gas recirculation device. The exhaust gas recirculation device recirculates a part of the exhaust gas exhausted from the combustion chamber of the engine to the atmosphere through the exhaust passage to the intake passage through the exhaust gas recirculation passage connecting the exhaust side and the intake side. The combustion temperature is lowered to suppress the emission of nitrogen oxides (NOx) and the like contained in the exhaust gas.

  Exhaust gas introduced from the exhaust side to the intake side (hereinafter referred to as return gas) is sent to the combustion chamber by opening / closing the valve device provided in the exhaust gas recirculation passage or the intake throttle valve provided in the intake passage. The actual oxygen concentration is feedback-controlled to control the introduction amount of the reflux gas so that the actual oxygen concentration of the intake air of the intake manifold section leads to the target value.

  In addition, in the exhaust gas recirculation system, the temperature of the reflux gas may be lowered by suppressing the rise of the combustion temperature by passing the reflux gas to be recirculated to the intake side via a cooling device called a reflux gas cooler (for example, for example) , Patent Document 1).

JP, 2013-160061, A

  When a reflux gas cooler is provided in the exhaust gas recirculation passage, hydrocarbons, smoke and the like contained in the exhaust gas may adhere to the inside of the reflux gas cooler, and these deposits may gradually accumulate in the reflux gas cooler. If the amount of the deposit inside the reflux gas cooler is increased, not only the original cooling performance can not be exhibited, but also the amount of the reflux gas supplied to the intake passage becomes smaller than the originally set required amount. If the supply amount of the reflux gas is smaller than the required amount, the exhaust gas may not be maintained properly.

  In this respect, in the technique of Patent Document 1, the blockage of the exhaust gas recirculation passage is determined by comparing the air-fuel ratio at the time of introducing the reflux gas with the air-fuel ratio at the time of not introducing the gas. However, if the blockage of the exhaust gas recirculation passage is determined only by comparing the actual air-fuel ratio, there is a limit to the improvement in accuracy. Therefore, in order to accurately determine the degree of the blockage, a more detailed method is desired.

  In addition, if the deposits in the exhaust passage or exhaust recirculation passage increase, it may lead to the sticking of various movable parts such as the valve device, so there is also a demand to accurately grasp the presence or absence of these sticking.

  Therefore, an object of the present invention is to more accurately determine the blockage of the exhaust gas recirculation passage and the fixation of various movable parts such as the valve device in the exhaust gas passage and the exhaust gas recirculation passage.

  In order to solve the above problems, the present invention uses a part of exhaust gas as a return gas through an intake air passage and an exhaust air passage connected to a combustion chamber of a cylinder, and an exhaust gas recirculation passage connecting the exhaust passage and the intake air passage. An exhaust gas recirculation device introduced into the intake air, a reflux gas cooler provided in the middle of the exhaust gas reflux passage for cooling the reflux gas, an upstream side and a downstream side of the reflux gas cooler or an upstream side of the reflux gas cooler and the intake passage Flow control means for adjusting the flow rate of the reflux gas passing through the cooling device passage passing through the reflux gas cooler and the flow rate of the reflux gas passing through the bypass passage, and the intake air introduced into the combustion chamber Intake oxygen concentration detection means for detecting the actual oxygen concentration, and in a state where the reflux gas is passing through the cooling device passage, it is detected by the intake oxygen concentration detection means When the absolute value of the concentration difference of the target oxygen concentration in the intake passage according to the operating condition with respect to the oxygen concentration is larger than a predetermined value and the concentration difference is a positive value, the exhaust passage or the exhaust gas recirculation passage An engine control apparatus comprising: an abnormality determining unit that determines an abnormal state in which adhesion of a member due to a deposit or blockage of a passage occurs in any part.

  Here, when the abnormality determination means determines that the state is an abnormal state, reflux gas increase control is performed on the exhaust gas recirculation device to increase the introduction amount of the reflux gas into the intake air, and the flow rate adjustment means It is possible to employ a configuration provided with a flow rate adjustment control means for performing a bypass shift command to decrease the flow rate of the reflux gas passing through the cooling device passage and increase the flow rate of the reflux gas passing through the bypass passage.

  The absolute value of the difference between the target oxygen concentration in the intake passage and the actual oxygen concentration detected by the intake oxygen concentration detecting means after the reflux gas increase control and the bypass shift command are issued. In the case where the value of 採用 is a predetermined value or less, the abnormality determining unit may adopt a configuration in which it is determined that the abnormal state is due to the blockage of the flow passage in the reflux gas cooler.

  The exhaust gas recirculation device is provided upstream of a junction between a reflux gas control valve provided upstream of a branch between the cooling device passage and the bypass passage and the exhaust pipe flow passage of the intake passage. Intake flow control valve, and the flow rate adjustment means is formed of a bypass adjustment valve provided in the bypass passage, and after performing the bypass shift command, the actual oxygen concentration detected by the intake oxygen concentration detection means When the absolute value of the concentration difference of the target oxygen concentration in the intake passage according to the operating condition for the engine is larger than a predetermined value, the abnormality determination unit determines that the abnormal condition is the reflux gas adjusting valve or the intake throttle valve. It is possible to adopt a configuration in which it is determined to be in the stuck state.

  At this time, when the concentration difference after the bypass transfer command is issued is a positive value, the abnormality determination unit determines that the abnormal state indicates that the reflux gas adjustment valve is in the closed side fixed state or the intake throttle valve. A configuration may be employed in which it is determined that the open-side fixed state, and when the concentration difference after the bypass transfer command is issued is a negative value, the reflux gas adjustment valve is determined to be in the open-side fixed state. .

  In each of these configurations, the recirculation gas increase control can adopt a configuration in which the recirculation gas control valve is fully opened and the intake throttle valve is fully closed.

  According to the present invention, the reflux gas introduced from the exhaust side to the intake side through the exhaust gas recirculation passage can be selectively supplied by the cooling device passage passing through the reflux gas cooler and the bypass passage not passing through the reflux gas cooler. The flow rate of the passage can be adjusted, and the absolute value of the concentration difference between the reference oxygen concentration in the intake passage and the actual oxygen concentration of the intake air introduced into the combustion chamber, and the value of the concentration difference Since it has become possible to determine whether or not there is sticking of a member or blockage of a passage due to deposits in any part of the exhaust passage or the exhaust gas recirculation passage, the blockage or sticking of these members can be more accurately determined. Can.

It is a schematic diagram of the engine which shows one Embodiment of this invention. It is a flowchart which shows control of the engine of this invention.

  An embodiment of the present invention will be described based on the drawings. FIG. 1 is a schematic view of an engine 1 of the present invention.

  The engine 1 of this embodiment is a diesel engine for automobiles. A piston is accommodated in a cylinder of the engine 1, and a combustion chamber 2 is formed by an inner wall surface of the cylinder, an upper surface of the piston, and the like.

  The engine 1 is provided with an intake passage 4 for feeding intake air into the combustion chamber 2 of each cylinder, an exhaust passage 5 drawn from the combustion chamber 2, and a fuel injection device 6 for injecting fuel into the combustion chamber 2.

  In the drawings, members and means directly related to the present invention are mainly shown, and other members and the like are not shown. Further, the number of cylinders of the engine is arbitrary, and may be a single cylinder, two cylinders, three cylinders, four cylinders, or multiple cylinders of more than that.

  An intake valve hole, which is an opening to the combustion chamber 2 of the intake passage 4 of each cylinder, is opened and closed by the intake valve. Further, an exhaust valve hole, which is an opening to the combustion chamber 2 of the exhaust passage 5 drawn from the combustion chamber 2, is opened and closed by the exhaust valve.

  In the intake passage 4, an intake air cooling device (intercooler) 21 for cooling intake air flowing through the intake passage 4 from the intake port leading to the combustion chamber 2 toward the upstream side, a compressor of a turbocharger that constitutes the supercharger 9, An intake throttle valve 3 for adjusting the flow passage area of the intake passage 4, an air cleaner and the like are provided. The intake throttle valve 3 adjusts the introduction amount of air (fresh air) to the intake passage 4 by increasing or decreasing the cross-sectional area of the flow passage of the intake passage 4 by the operation of the valve body of butterfly valve type.

  An exhaust gas purification device 8 provided in the exhaust passage 5 with a turbine of a turbocharger constituting the supercharger 9, a catalyst for removing harmful substances in exhaust gas, and the like from the exhaust port drawn out from the combustion chamber toward the downstream side , Mufflers, etc. are provided. In this embodiment, since the engine 1 is a diesel engine, an oxidation catalyst, a diesel particulate filter, or the like is used as the exhaust gas purification device 8. When a gasoline engine is employed as the engine 1, a three-way catalyst or the like is used as the exhaust gas purification device 8.

  In addition, the engine 1 is provided with a rotation sensor 7 that detects the number of rotations of the engine by detecting the rotational angular velocity and rotational angular acceleration of the crankshaft. In this embodiment, a crank angle sensor for reading the rotation of the timing rotor attached to the end of the crankshaft is adopted as the rotation sensor 7. However, it is driven by the rotation of the engine and the rotation of the engine. You may use the well-known rotation sensor provided in the auxiliary machine etc. which are carried out, or another place.

  These intake and exhaust valves, the fuel injection device 6, the intake throttle valve 3, the exhaust gas purification device 8 and other devices necessary for the operation of the engine are provided in an electronic control unit 30 through cables. It is controlled by the control means. Further, the electronic control unit 30 acquires necessary information from the engine and sensors provided around the engine. The electronic control unit 30 can obtain information on the number of rotations of the engine 1 and the engine load based on the information from these sensors.

  Further, the exhaust passage 5 and the intake passage 4 communicate with each other by the exhaust gas recirculation passage 11 that constitutes the exhaust gas recirculation device C. The exhaust gas recirculation device C has a function of returning a part of the exhaust gas discharged from the engine to the intake passage 4 as a return gas. The exhaust gas recirculation device C of this embodiment is a high-pressure exhaust gas recirculation device, and the exhaust gas recirculation passage 11 is extracted from the exhaust passage 5 on the upstream side of the turbocharger 9 provided in the exhaust passage 5 to The passage 4 is connected to the downstream side of the turbocharger 9. However, as the exhaust gas recirculation device C, the exhaust gas recirculation passage 11 is pulled out from the exhaust passage 5 on the downstream side of the turbocharger 9 and the low pressure exhaust gas re-connected to the intake passage 4 on the upstream side of the turbocharger 9 A circulator may be employed.

  The exhaust gas recirculation passage 11 is provided with a reflux gas cooler 16 for reducing the temperature of the reflux gas. The reflux gas cooler 16 is provided with an air-cooled core having a space through which the reflux gas can pass, and a water-cooled core.

  The exhaust gas recirculation passage 11 on the upstream side of the reflux gas cooler 16 and the exhaust gas recirculation passage 11 on the downstream side, or the upstream side of the reflux gas cooler 16 and the intake passage 4 are connected by a bypass passage 15 not via the reflux gas cooler 16. Hereinafter, on the downstream side of the branched portion B of the bypass passage 15 in the exhaust gas recirculation passage 11, a route passing the reflux gas cooler 16 will be referred to as a cooling device passage 14 and a route not passing the reflux gas cooler 16 will be referred to as a bypass passage 15.

  Further, the exhaust gas recirculation device C is provided with a flow rate adjusting means A for adjusting the flow rate of the reflux gas passing through the cooling device passage 14 and the flow rate of the reflux gas passing through the bypass passage 15.

  In this embodiment, as the flow rate adjusting means A, a bypass adjusting valve 13 is provided in the middle of the bypass passage 15. Further, the exhaust gas recirculation passage 11 is provided, upstream of the branch portion B of the bypass passage 15 in the exhaust gas recirculation passage 11, with a reflux gas control valve 12 capable of adjusting the amount of passing gas by opening and closing the passage. The reflux gas regulating valve 12 and the bypass regulating valve 13 as the flow rate regulating means A have the function of regulating the flow rate of the reflux gas passing through the respective passages.

  The flow rate adjustment control means 31 included in the electronic control unit 30 controls the operation of the flow rate adjustment means A and the reflux gas adjustment valve 12. If the reflux gas adjustment valve 12 is closed, the introduction of the reflux gas from the exhaust side to the intake side is stopped, and if the reflux gas adjustment valve 12 is opened, the introduction of the reflux gas from the exhaust side to the intake side is started. . Further, when the bypass control valve 13 is closed, all the reflux gas passes through the cooling device passage 14, and when the bypass control valve 13 is opened, the flow rate on the bypass passage 15 increases. At this time, a large amount of reflux gas passes through the bypass passage 15 side where the resistance of the flow passage is relatively small.

Further, an intake oxygen concentration detection means 20 for detecting the actual oxygen concentration of intake air introduced into the combustion chamber 2 is provided in the intake passage 4. For example, a linear air fuel sensor (Linear Air-Fuel ratio sensor) or the like can be adopted as the intake oxygen concentration detection means 20, and the actual oxygen concentration of intake air is detected at a position immediately before being introduced into the combustion chamber 2. can do. The intake oxygen concentration detecting means 20 has a function capable of numerically detecting a continuous change in air-fuel ratio (oxygen concentration) instead of a device that detects only lean or rich, such as an O ₂ sensor, for example. Is preferred.

  In the supercharger 9, a turbine provided in the exhaust passage 5 is rotated by the exhaust gas discharged through the exhaust passage 5, and rotation of a turbine is transmitted to a compressor provided in the intake passage 4. The rotation of the compressor compresses the air taken in from the air cleaner and supplies the air in a supercharged state to the combustion chamber 2 of the engine 1 through the intake passage 4.

  Further, in the state where the return gas is passing through the cooling device passage 14, the electronic control unit 30 detects the actual oxygen concentration of the intake air detected by the intake oxygen concentration detecting means 20 and the inside of the intake passage 4 according to the operating condition. When the absolute value of the concentration difference from the reference oxygen concentration is larger than a predetermined value, and the concentration difference is a positive value, a member of any part of the exhaust passage 5 or the exhaust gas recirculation passage 11 may be attached An abnormality determination unit 32 is provided that determines that there is a sticking or blockage in the passage.

  Here, when the abnormality determination means 32 determines that the state is abnormal, the flow rate adjustment control means 31 causes the flow rate adjustment means A to decrease the flow rate of the reflux gas passing through the cooling device passage 14 and passes the bypass passage 15. And a bypass shift command to increase the flow rate of the reflux gas.

  Also, after performing the bypass shift command, the absolute value of the difference in concentration of the reference oxygen concentration in the intake passage 4 according to the operating condition with respect to the actual oxygen concentration of the intake detected by the intake oxygen concentration detection means 20 is less than a predetermined value In this case, the abnormality determination unit 32 determines that the abnormal state is due to the blockage of the flow passage in the reflux gas cooler 16.

  In addition, after performing the bypass shift command, the absolute value of the difference in concentration of the reference oxygen concentration in the intake passage 4 according to the operating condition with respect to the actual oxygen concentration of the intake detected by the intake oxygen concentration detecting means 20 In the case where the value is also large, the abnormality determining means 32 is configured such that the abnormal state determines that the reflux gas adjusting valve 12 or the intake throttle valve 3 is in the stuck state.

  At this time, when the above-mentioned concentration difference after performing the bypass shift command is a positive value, the abnormality determination unit 32 determines that the abnormal state indicates that the reflux gas adjustment valve 12 is in the closed side or the intake throttle valve. 3 is determined as the open side fixed state. In addition, when the above-mentioned concentration difference after the bypass shift command is issued is a negative value, it is determined that the reflux gas adjustment valve 12 is in the open side stuck state.

  Hereinafter, the control method of the engine and the flow thereof will be described based on the flowchart of FIG.

  First, it is assumed that the exhaust gas recirculation device C performs close loop control (feedback control) (see step S1). The feedback control reflects the signal of the output to the input to the next input, and while controlling the input and output repeatedly, controls the output to be an appropriate target value or reference value. Here, the opening degree of the reflux gas control valve 12 and the intake throttle valve 3 is feedback controlled so that the actual oxygen concentration of the intake air becomes a target value.

  In step S1, the exhaust gas recirculation device C starts the introduction of the reflux gas from the exhaust side to the intake side. In step S2, information on the actual oxygen concentration of the intake air introduced into the combustion chamber 2 is acquired from the intake oxygen concentration detection means 20. Next, in step S3, it is determined whether the reflux gas has passed through the cooling device passage 14 via the reflux gas cooler 16. This determination can be made based on whether or not the bypass control valve 13 is closed. If the bypass control valve 13 is closed, it is determined that the reflux gas passes through the cooling device passage 14.

  When the reflux gas passes through the cooling device passage 14, the difference between the actual oxygen concentration of the intake air detected by the intake oxygen concentration detection means 20 and the concentration difference of the reference oxygen concentration of the intake air in the intake passage 4 according to the operation situation. It is determined whether the absolute value is larger than a predetermined value (see step S4).

  If the absolute value of the concentration difference between the detected actual oxygen concentration of the intake air and the reference oxygen concentration is larger than a predetermined value, the process proceeds to step S6 through step S5. If the absolute value of the concentration difference between the actual oxygen concentration and the reference oxygen concentration is equal to or less than the predetermined value, there is no danger of sticking or clogging, so the process proceeds to step S14, and the control of the blockade / sticking determination is ended. It is determined that the absolute value of the concentration difference between the detected actual oxygen concentration of the intake air and the reference oxygen concentration is larger than a predetermined value determined in advance in this way. This is because it is considered that the introduction amount of the reflux gas does not reach the required amount or the introduction amount of the reflux gas exceeds the required amount due to the blockage and the fixation of the members in other places.

  Here, in step S5, how long does the state in which the absolute value of the concentration difference between the detected reference oxygen concentration and the actual oxygen concentration of the intake is larger than a predetermined value last before shifting to step S6? To judge. Since the control method of the exhaust gas recirculation device C is feedback control, the time required for the numerical value to converge on the target value is taken into consideration. The process proceeds to step S6 only when the duration exceeds a predetermined time which is predetermined as a time sufficient for the convergence of the numerical value, and since the numerical value is a transient value in the middle of control when it is less than the predetermined time. , And moves to step S14, and ends the control of the blockage / sticking determination.

  In step S6, it is determined whether the difference between the reference oxygen concentration of the intake air in the intake passage 4 and the actual oxygen concentration of the intake detected by the intake oxygen concentration detecting means 20 is a positive value. Be done. When the concentration difference is a positive value (for example, when the actual oxygen concentration is 18% with respect to the target oxygen concentration 16%), blockage of the exhaust gas recirculation passage 11 due to deposits in any part of the exhaust gas recirculation passage 11; Alternatively, it is determined that the abnormal state in which the members are stuck to any part of the exhaust gas recirculation passage 11 or the exhaust passage 5 is determined, and the process proceeds to steps S7 and S8.

  Therefore, in step S7, the flow rate of fresh air introduced into the intake passage 4 is suppressed by setting the intake throttle valve 3 in the fully closed state and the return gas adjustment valve 12 in the fully open state. It is introduced into the intake passage 4 and controlled so that the reflux gas introduced into the intake passage 4 is increased if there is no sticking of the reflux gas control valve 12 and the intake throttle valve 3. Then, in S8, by opening the bypass control valve 13 and switching the introduction of the reflux gas to the bypass passage 15, whether the cause of the abnormal state is the blockage of the exhaust gas recirculation passage 11 on the side of the cooling device passage 14 Make sure.

In step S6, if the concentration difference is a negative value (for example, the actual oxygen concentration is 14% with respect to the target oxygen concentration of 16%), the reflux gas adjustment valve 12 is in the open-side fixed state . It is determined that there is (see step S17). For this reason, it is not preferable to continue the driving as it is, so the control of the blockade / sticking determination is ended after the driver is warned by voice or display (step S18).

  In steps S7 and S8, after closing the intake throttle valve 3 based on the determination of the abnormal state and opening the reflux gas regulating valve 12 and the bypass regulating valve 13, that is, the reflux gas to be recirculated to the intake passage 4 with respect to the flow regulating means A. After performing a bypass transfer command to increase the flow rate of the reflux gas flowing through the bypass passage 15 and to decrease the flow rate of the reflux gas passing through the cooling device passage 14 Whether the absolute value of the concentration difference between the actual oxygen concentration of the intake air detected by the intake oxygen concentration detection means 20 and the reference oxygen concentration of the intake air in the intake passage 4 according to the operating situation is larger than a predetermined value (See step S9).

  In step S9, if the absolute value of the concentration difference is equal to or less than the predetermined value, it is determined that the value of the actual oxygen concentration of the intake approaches the normal by switching the exhaust gas recirculation passage 11 to the bypass passage 15 side. It is determined that the passage blockage is in the cooling device passage 14 of the exhaust gas recirculation passage 11, and the process proceeds to step S11. Further, in step S9, even if the absolute value of the concentration difference is a value larger than the predetermined value, in step S10, if the continuation time of the state exceeding the predetermined value is equal to or less than the predetermined time, It is determined that the blockade is in the cooling device passage 14 of the exhaust gas recirculation passage 11, and the process proceeds to step S11. In these cases, the abnormality is often the blockage of the flow passage in the reflux gas cooler 16. Since the detected actual oxygen concentration of the intake air is larger than the reference oxygen concentration in the state before the bypass shift command, sufficient return gas is not supplied to the intake side due to the blockage of the exhaust gas recirculation passage 11, and the relative It is thought that the proportion of fresh air is increasing. Also, in the state after the bypass shift command, since the oxygen concentration approaches the appropriate numerical value, it is considered that the reflux gas adjusting valve 12 and the intake throttle valve 3 are normal, and the above cause is in the cooling device passage 14 Be

  If it is determined in step S11 that the cooling device passage 14 of the exhaust gas recirculation passage 11 is clogged, the driver is not warned by voice or display (step S12) and the recirculation gas cooler 16 is not used or the exhaust gas recirculation device The operation is shifted to an operating state in which the introduction of the reflux gas by C is not performed (step S13). Thus, the control of the blockage / sticking determination is ended.

  Here, in step S10, how long does the state where the absolute value of the concentration difference between the reference oxygen concentration and the detected actual oxygen concentration is larger than a predetermined value last time before shifting to step S11? To judge. Since the control method of the exhaust gas recirculation device C is feedback control, the time required for the numerical value to converge on the target value is taken into consideration. The process proceeds to step S11 only when the duration is equal to or less than a predetermined time predetermined as the time sufficient for the convergence of the numerical value, and another cause may be considered when the predetermined time exceeds the time, so the process proceeds to step S15.

  In steps S9 and S10, when the absolute value of the concentration difference between the actual oxygen concentration of the intake air detected by the intake oxygen concentration detection means 20 and the reference oxygen concentration in the intake passage 4 according to the operating condition is larger than a predetermined value. If the duration time exceeds the predetermined time, it is determined that the abnormal state is the reflux gas control valve 12 or the intake throttle valve 3, and the process proceeds to step S15.

  In step S15, when the concentration difference after performing the bypass shift command is a positive value (in the case of the lean side), the abnormal state is that the reflux gas adjusting valve 12 is in the closed side fixed state or the intake throttle valve It is determined that the intake oxygen concentration is increased by the state 3 being in the open-side fixed state. For this reason, it is not preferable to continue the driving as it is, so the control of the blockade / sticking determination is ended after the driver is warned by voice or display (step S18) (step S19).

  Further, in step S15, when the concentration difference after the bypass shift command is given is a negative value (in the case of the rich side), regardless of the opening degree of the intake throttle valve 3, the reflux gas regulating valve 12 It is determined that the intake oxygen concentration is low due to the open-side fixed state. For this reason, it is not preferable to continue the driving as it is, so the control of the blockade / sticking determination is ended after the driver is warned by voice or display (step S18) (step S19).

  In step S3, when the reflux gas does not pass through the cooling device passage 14, that is, when the bypass adjustment valve 13 is opened, the reflux gas hardly passes through the cooling device passage 14, so After shifting to S8, the same control is performed.

  In the above control, it is used when evaluating the absolute value of the concentration difference of the reference oxygen concentration of the intake air in the intake passage 4 according to the operating condition with respect to the actual oxygen concentration of the intake detected by the intake oxygen concentration detecting means 20 Regarding the predetermined value, the setting of the predetermined value can be determined using a map or the like based on, for example, the two factors of the engine speed and the engine load. The predetermined value tends to increase as the engine speed increases, and tends to increase as the engine load increases. The same applies to the predetermined time.

  Also, with regard to the reference oxygen concentration of intake air in the intake passage 4 according to the operating situation, the setting of the reference oxygen concentration is determined using a map or the like based on two factors, for example, the engine speed and the engine load. can do. The reference oxygen concentration tends to increase as the engine speed increases, and tends to increase as the engine load increases.

  In the above embodiment, the flow rate adjusting means A includes the reflux gas adjusting valve 12 provided on the upstream side of the branch portion B of the cooling device passage 14 and the bypass passage 15, and the bypass adjusting valve 13 provided in the bypass passage 15. However, the configuration of the flow control means A is not limited to this embodiment, and for example, a flow control valve may be provided in both the cooling device passage 14 and the bypass passage 15.

  Further, in the above embodiment, the configuration of the present invention has been described by taking a diesel engine for a car as an example, but the present invention can be applied to a gasoline engine for a car and various other engines.

Reference Signs List 1 engine 2 combustion chamber 3 intake throttle valve 4 intake passage 5 exhaust passage 6 fuel injection device 11 exhaust recirculation passage 12 recirculation gas adjustment valve 13 bypass adjustment valve 16 recirculation gas cooler 20 intake oxygen concentration detection means 30 electronic control unit (Electronic Control Unit)
31 Flow rate adjustment control means 32 Abnormality determination means A Flow rate adjustment means C Exhaust gas recirculation device

Claims (6)

An intake passage and an exhaust passage connected to a combustion chamber of the cylinder;
An exhaust gas recirculation device for introducing a part of the exhaust gas into the intake air as a reflux gas through an exhaust gas recirculation passage connecting the exhaust passage and the intake passage;
A reflux gas cooler provided in the middle of the exhaust gas recirculation passage for cooling the reflux gas;
A bypass passage connecting an upstream side and a downstream side of the reflux gas cooler or an upstream side of the reflux gas cooler and the intake passage;
Flow rate adjustment means for adjusting the flow rate of the reflux gas passing through the cooling device passage passing through the reflux gas cooler and the flow rate of the reflux gas passing through the bypass passage;
Intake oxygen concentration detection means for detecting the actual oxygen concentration of intake air introduced into the combustion chamber;
In a state where the reflux gas passes through the cooling device passage, the absolute value of the concentration difference of the target oxygen concentration in the intake passage according to the operating condition with respect to the actual oxygen concentration detected by the intake oxygen concentration detecting means is predetermined when large and the density difference than the value is a positive value, the abnormality determination means for determining an abnormal state in which there is a fixed or blockage of the passage of the member by deposits on the exhaust gas recirculation passage,
A control device of an engine comprising: The exhaust gas recirculation device performs recirculation gas increase control to increase the introduction amount of the reflux gas to the intake air when the abnormality determination unit determines that the flow is the abnormal state, and the cooling of the flow rate adjustment unit is performed. The engine control device according to claim 1, further comprising a flow control control means for performing a bypass shift command to decrease the flow rate of the reflux gas passing through the device passage and increase the flow rate of the reflux gas passing through the bypass passage. After performing the reflux gas increase control and the bypass shift command, the absolute value of the difference between the target oxygen concentration in the intake passage and the actual oxygen concentration detected by the intake oxygen concentration detecting means is a predetermined value. The engine control device according to claim 2, wherein the abnormality determination unit determines that the abnormal state is due to a blockage of a flow passage in the reflux gas cooler when the following condition is satisfied. The exhaust gas recirculation device is provided upstream of a junction between a reflux gas control valve provided upstream of a branch portion between the cooling device passage and the bypass passage and the exhaust gas recirculation passage of the intake passage. It consists of an intake throttle valve and
The flow rate adjusting means is constituted by a bypass adjusting valve provided in the bypass passage,
When the absolute value of the concentration difference of the target oxygen concentration in the intake passage according to the operating condition relative to the actual oxygen concentration detected by the intake oxygen concentration detecting means after the bypass transfer command is issued is larger than a predetermined value The engine control device according to claim 3, wherein the abnormality determining unit determines that the abnormal condition is in the adhering state of the reflux gas adjusting valve or the intake throttle valve. When the concentration difference after the bypass transfer command is issued is a positive value, the abnormality determination means determines that the abnormal condition is the closed side of the reflux gas adjusting valve or the open side of the intake throttle valve. The engine control device according to claim 4, wherein when it is determined that the state is the difference in concentration after the bypass transfer command is issued is a negative value, the control valve for the reflux gas is determined to be in the open side fixed state. . The control device for an engine according to claim 4 or 5 , wherein the reflux gas increase control causes the reflux gas adjustment valve to be fully open and the intake throttle valve to be fully closed.

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