JP2014034921A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine capable of preventing a wasteful valve opening and closing motion by optimizing a time to execute a fastening preventing motion after stop of an engine to elongate a service life of a valve and to save power.SOLUTION: A control device of an internal combustion engine includes: circulation passages 21, 41 for circulating the exhaust from an exhaust passage to an intake passage of the internal combustion engine 10; valves 23a, 43a for adjusting a flow rate of the exhaust circulated in the circulation passages; a circulation state acquiring portion for acquiring a circulation state of the exhaust in the circulation passages when a predetermined estimation timing comes; a determining portion 60 for comparing the acquired circulation state with a reference state of the circulation state memorized in advance to determine whether a fastening preventing motion to solve or prevent fastening of a valve, is necessary or not; and an instruction information outputting portion 60 for outputting instruction information including an instruction to execute the fastening preventing motion, when the internal combustion engine transits from a rotating state to a stop state, in a case when the determining portion determines necessity of execution of the fastening preventing motion.

Description

  The present invention relates to a control device for an internal combustion engine.

  For example, in an automobile engine, a part of the exhaust gas flowing in the exhaust pipe is introduced into the intake pipe as exhaust recirculation gas (EGR gas), and this EGR gas is mixed into the intake air to lower the maximum in-cylinder combustion temperature. And an exhaust gas recirculation device that reduces harmful substances (for example, nitrogen oxides) contained in the exhaust gas.

  This exhaust gas recirculation device includes an EGR pipe that connects an exhaust system and an intake system of an engine, and an EGR valve (also simply referred to as a “valve”) that is provided in the EGR pipe and is adjustable in opening. There is). That is, the recirculation amount of the EGR gas is adjusted by adjusting the opening degree of the EGR valve.

  In this type of exhaust gas recirculation device, combustion products (oxides) contained in EGR gas are provided in an exhaust gas recirculation path formed in an EGR pipe, for example, a circular tube-shaped nozzle fitted in a valve housing. (Or carbide) deposits may be deposited. This deposit is caused by hydrocarbons (HC), carbon (C), oil, etc. in the exhaust gas, and has a high viscosity. Therefore, the deposit is included in the outer periphery of the EGR valve, the drive shaft of the EGR valve, and the exhaust gas recirculation path. Adhere to the wall surface. When this deposit (deposit) adheres between the outer periphery of the EGR valve and the inner wall surface of the return path, or between the drive shaft and the inner wall surface of the return path, the EGR valve opens and closes. As a result, the opening degree of the EGR valve cannot be adjusted satisfactorily, and EGR gas cannot be supplied into the intake pipe, and an appropriate recirculation amount of EGR gas cannot be obtained. In particular, when the driving torque for opening and closing the EGR valve is small, or when the opening degree of the EGR valve is to be controlled within a minute angle range, this problem appears remarkably.

  Therefore, the EGR valve is opened and closed by a predetermined opening degree near the fully closed position of the valve, and the deposited deposit is scraped off by the EGR valve to eliminate or prevent the EGR valve from sticking (hereinafter, this operation is referred to as “sticking avoidance”). Called operation). In order to efficiently perform this “sticking avoidance operation”, a valve control device for an internal combustion engine has been devised in which the start condition of the “sticking avoidance operation” is set only at the time of the ignition off operation that the engine has been operating until just before. (See Patent Document 1).

  Further, when reciprocating to avoid sticking of the valve, if the valve movement amount does not reach the predetermined amount even after the predetermined movement control time has elapsed, an operation of moving the valve in the other direction is started. There has been devised a valve control device for an internal combustion engine that can complete a “sticking avoidance operation” in a relatively short time without the operation of moving the valve in one direction or the other direction taking a long time (patent) Reference 2).

  In addition, the amount of deposit generated is calculated according to the operating state of the internal combustion engine, and is integrated to estimate the amount of deposit deposited in the gas passage provided with the butterfly valve element. Based on the estimated amount of deposited deposit, A control device for an internal combustion engine that removes deposits by rotating a valve body has been devised (see Patent Document 3).

  Also, an exhaust gas recirculation device has been devised that can cool the high-temperature exhaust gas and recirculate it to the engine intake side, and can remove deposits adhering to the exhaust gas recirculation path and valves with the high-temperature exhaust gas. (See Patent Document 4).

  Also, when the engine is stopped, the deposit temperature when the engine is stopped is estimated based on the usage environment of the exhaust gas recirculation device during the engine operation continuation period, and the deposit temperature and the external environment of the exhaust gas recirculation device Devised a control device for an internal combustion engine that estimates the deposit solidification period from the time when operation of the engine is stopped to the time when the deposit hardens to some extent, and performs this `` sticking avoidance operation '' when this deposit solidification period has elapsed (See Patent Document 5).

  Further, when it is requested to stop the internal combustion engine, the internal combustion engine is closed after the intake throttle valve provided in the intake passage of the internal combustion engine is closed to a predetermined opening until the internal combustion engine is completely stopped. An intake control device for an internal combustion engine has been devised that detects the magnitude of the rotation fluctuation of the engine and removes the deposit attached around the intake throttle valve when the magnitude of the rotation fluctuation exceeds a predetermined value. (See Patent Document 6).

Japanese Patent Laid-Open No. 2007-064166 JP 2007-032356 A JP 2008-038636 A JP 2006-070852 A Japanese Patent Application Laid-Open No. 2008-075517 JP 2010-174651 A

  In Patent Documents 1, 2, 5, and 6, “sticking avoidance operation” is performed when the engine is stopped. For this reason, in a so-called idling stop system that has been adopted as a fuel efficiency measure in recent years, the engine is automatically stopped when a predetermined stop condition is satisfied, and then the engine is restarted when a predetermined restart condition is satisfied. The number of engine stops, that is, the number of “sticking avoidance operations” increases. Along with this, there is a problem that the wear amount of the sliding portion of the EGR valve also increases, and the life of the EGR valve and the actuator that rotates the EGR valve is reduced.

  In Patent Document 3, “sticking avoidance operation” is performed at the time of engine rotation, but the rotation of the EGR valve for deposit removal is performed when the target opening of the EGR valve is less than a predetermined opening near the fully closed position. Therefore, there is a problem that the “sticking avoidance operation” cannot be performed in an operation state in which this condition is not satisfied.

  In Patent Document 4, “adhesion avoidance operation” is performed during engine rotation, but it is necessary to provide a bypass passage and a bypass valve for flowing hot exhaust gas to the EGR valve, which complicates the configuration of the apparatus. There's a problem.

  Against the background of the above problems, the object of the present invention is to optimize the timing for performing the “sticking avoidance operation” after the engine is stopped, thereby preventing unnecessary valve opening / closing operations, extending the life of the valve and saving it. An object of the present invention is to provide a control device for an internal combustion engine capable of achieving electric power.

Means for Solving the Problems and Effects of the Invention

  An internal combustion engine control apparatus for solving the above problems includes an intake passage (15) through which intake air of the internal combustion engine (10) flows, an exhaust passage (51) through which exhaust from the internal combustion engine flows, and intake air from the exhaust passage. Recirculation passages (21, 41) that recirculate exhaust gas to the passages, valves (23a, 43a) that are provided in the recirculation passages and adjust the flow rate of exhaust gas that recirculates the recirculation passages, and a predetermined estimated timing has arrived Sometimes, the recirculation state acquisition unit (23b, 43b, 24, 44) for acquiring the recirculation state of the exhaust gas in the recirculation passage is compared with the acquired recirculation state and the reference state of the recirculation state stored in advance. Based on the comparison result, the determination unit (60) for determining whether or not the sticking avoidance operation for eliminating or preventing the sticking of the valve needs to be performed, and the determination unit determines that the sticking avoidance operation needs to be performed. Place , When the internal combustion engine is shifted from the rotating state to the stop state, characterized in that it comprises instruction information output unit for outputting the instruction information including the instructing execution of solid deposition avoidance operation (60), the.

  With the above configuration, it is possible to optimize the timing for performing the “sticking avoidance operation” after the engine is stopped, to prevent useless valve opening / closing operations, and to extend the life of the valve and save power. In addition, the configuration of the conventional internal combustion engine is not changed. For example, the configuration of the present invention can be realized only by changing the software for controlling the internal combustion engine, and the manufacturing cost can be reduced.

The figure which shows the structure of the control apparatus of the internal combustion engine of this invention. The flowchart explaining sticking avoidance control processing. The timing chart which shows the flow of sticking avoidance control of FIG. The flowchart explaining another example of sticking avoidance control processing. The figure which shows the example of the map data for calculating the reference value of EGR flow volume in FIG. The figure which shows the concept of the sticking avoidance control of FIG. The timing chart which shows the flow of the sticking avoidance control of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an outline of a control device 1 (hereinafter, device 1) for an internal combustion engine according to the present invention. The device 1 is configured for an internal combustion engine (engine) of an automobile vehicle, for example. In addition, although the diesel engine is illustrated in FIG. 1, since the structure is well-known, only an outline will be described.

  The apparatus 1 includes an engine 10 (a general term for a cylinder 11, a supply pump 12, a common rail unit 13, and an injector 14), an intake pipe 15, an exhaust pipe 51, a high pressure EGR system 20, a low pressure EGR system 40, and an electronic control unit 60 (ECU: Electronic). Control Unit).

  For example, air taken in from the intake manifold 31 integrated with the surge tank is supplied to the engine 10 through the intake pipe 15. Exhaust gas from the engine 10 is discharged outside the vehicle through the exhaust pipe 51. The intake pipe 15 includes, in addition to the intake throttle 16, the air flow meter 32, and the intercooler 35, a temperature sensor that detects the temperature in the intake manifold 31 and a pressure sensor that detects the pressure in the intake manifold 31 (all not shown). Is provided. The intake air amount is adjusted by adjusting the opening of the intake throttle 16. The air flow meter 32 detects the intake air amount. The intake air is cooled by the intercooler 35, and more air can be sent from the intake pipe 15 to the engine 10.

  The exhaust pipe 51 is provided with an exhaust pressure sensor 58. The pressure in the exhaust pipe 51 is detected by the exhaust pressure sensor 58, and the exhaust pressure adjustment valve 59 is opened and closed based on the detected value. The supercharger 33 includes a turbine 33b in the exhaust pipe 51 and a compressor 33a in the intake pipe 4, and the compressor 33a to which driving force is transmitted from the turbine 33b driven by the exhaust compresses the intake air so that more air is supplied. Is sent to the engine 10.

  The DOC 52 is a diesel oxidation catalyst and oxidizes unburned gas (HC, CO) discharged from the engine 10.

  The DPF 53 is a filter that collects PM discharged from the engine 10. For example, the DPF 53 has a structure in which the inlet side and the outlet side are alternately clogged in a so-called honeycomb structure. PM contained in the exhaust discharged during operation of the engine 10 is collected inside or on the surface of the DPF wall when passing through the DPF 53. The DPF 53 may be a DPF with an oxidation catalyst on which an oxidation catalyst is supported.

  When it is determined that the estimated value of the PM amount accumulated in the DPF 53 has exceeded a predetermined amount, for example, the DPF 53 is heated by post injection after the main injection in the engine cylinder, and the accumulated PM is burned to burn the DPF 53 Play. At this time, as an estimation method of the PM accumulation amount in the DPF 53, for example, the pressure difference (front-rear differential pressure) on the inlet side and the outlet side of the DPF 53 is measured using the differential pressure sensor 56, and the measured value is obtained in advance. The PM deposition amount is estimated from the map showing the relationship between the placed differential pressure and the PM deposition amount.

  On the upstream side of the DOC 52, the downstream side of the DOC 52 (that is, the upstream side of the DPF 53), and the downstream side of the DPF 53, exhaust temperature sensors 54, 55, 57 for protecting the DOC 52 and the DPF 53 from high-temperature exhaust gas, respectively. Is provided.

  The high pressure EGR system 20 and the low pressure EGR system 40 are pipes for exhaust gas recirculation (EGR) from the exhaust pipe 51 to the intake pipe 15. The high-pressure EGR system 20 includes an EGR pipe 21, an EGR cooler 22, a valve unit 23, a differential pressure sensor 24 that measures a pressure difference (differential pressure) between the upstream side and the downstream side of the valve 23a, and a flow rate sensor 25. The exhaust gas is recirculated from the upstream side of 33b to the downstream side of the compressor 33a (further downstream of the intake throttle 16). The valve unit 23 also includes an opening degree sensor 23b that detects the opening degree of the valve 23a in addition to the valve 23a.

  Further, the low pressure EGR system 40 includes an EGR pipe 41, an EGR cooler 42, a valve unit 43, a differential pressure sensor 44 for measuring a pressure difference (differential pressure) between exhaust gas upstream and downstream of the valve 43a, and a flow rate sensor 45. The exhaust gas is recirculated from the downstream side of the turbine 33b of the supercharger 33 (further downstream of the DPF 53) to the upstream side of the compressor 33a. In addition to the valve 43a, the valve unit 43 includes an opening degree sensor 43b that detects the opening degree of the valve 43a.

  In the high-pressure EGR system 20 and the low-pressure EGR system 40, the amount of exhaust gas recirculated is adjusted by the opening degree of valves 23a and 43a driven by motors, respectively. For example, in the high pressure EGR system 20, the ECU 60 outputs a drive signal to the motor that drives the valve 23a so that the flow rate of the exhaust gas in the EGR pipe 21 detected by the flow sensor 25 becomes a predetermined value. Alternatively, a drive signal is output from the ECU 60 to the motor that drives the valve 23a so that the valve 23a has a predetermined opening based on the detection value of the opening sensor 23b. The low pressure EGR system 40 operates in the same manner.

  In addition, the exhaust gas that recirculates is cooled by the EGR coolers 22 and 42, thereby enabling more exhaust gas recirculation. By the exhaust gas recirculation by these EGR systems, the combustion temperature in the engine is lowered, and the NOx emission from the engine can be reduced.

  When the engine 10 is in a high load state, it is impossible to secure an EGR amount that can be recirculated from the exhaust passage only by the high-pressure EGR system 20 by securing the necessary intake pressure by the supercharger 33 (securing the exhaust flow rate to the turbine 33b side). There is. Therefore, EGR is executed by the low pressure EGR system 40 communicating with the upstream side of the intake passage relative to the compressor 33a so as not to be affected by the intake pressure increase due to supercharging of the supercharger 33. As a result, a sufficient EGR amount can be ensured even under conditions where intake air is supercharged in a high load range. Of course, the low pressure EGR system 40 may not be provided.

  The EGR pipe 21 corresponds to the first recirculation passage (21) that recirculates the exhaust gas from the upstream side of the turbine (33b) equipped in the exhaust passage to the downstream side of the compressor (33a) equipped in the intake passage. . The EGR pipe 41 corresponds to a second recirculation passage (41) that recirculates exhaust gas from the downstream side of the turbine equipped in the exhaust passage to the upstream side of the compressor equipped in the intake passage.

  The ECU 60 is configured as a normal computer including a CPU 60a, a nonvolatile memory 60b and a RAM (not shown), a signal input / output circuit, an A / D conversion circuit, and the like (not shown). Control. In FIG. 1, transfer of representative information between the ECU 60 and each part of the apparatus 1 is shown by dotted lines. For example, the ECU 60 controls the fuel injection in the injector 14 of the engine 10, the opening degree of the intake throttle 16, the opening degree of the valves 23a and 43a, and the like.

  Further, the ECU 60 acquires measured values of the air flow meter 32, the differential pressure sensors (24, 44), the flow rate sensors (25, 45), the differential pressure sensor 56, the exhaust temperature sensors 54, 55, 57, the exhaust pressure sensor 58, and the like. To do. Further, the ECU 60 also acquires the state of the engine rotation sensor 17 that detects the rotation speed of the engine 10 and the ignition switch 61 for starting / stopping the engine 10.

  The sticking avoidance control process included in the program stored in the memory 60b of the ECU 60 and executed by the CPU 60a will be described with reference to FIG. First, it is determined whether or not the engine has been started. That is, the state of the ignition switch 61 is acquired, and it is determined whether or not the ignition switch 61 is on.

  When the engine is started with the ignition switch 61 turned on (S11: Yes), the state of the engine speed sensor 17 is acquired, and the engine speed of the engine 10 is included in a predetermined idle speed region. It is determined whether or not. This configuration corresponds to the case where the estimated timing has arrived when the rotational state of the internal combustion engine transitions to the idle state. In the idle state, since the fluctuation of the rotation speed of the engine 10 is smaller than that in the traveling state, the valve opening degree, the EGR flow rate, or the value of the differential pressure sensor is less changed, and it is necessary to execute the sticking avoidance operation more accurately. It can be determined whether or not there is.

When the engine 10 is in the idle state (S12: Yes), the state of the valves 23a and 43a (hereinafter referred to as “valve state”) is acquired. (S13) The valve state uses at least one of the following.
Opening degree of valve (23a, 43a) (command value calculated by CPU 60a and output to each valve unit (23, 43) or voltage value of opening degree sensor (23b, 43b)).
The output value of the differential pressure sensor (24, 44). Since the differential pressure sensor outputs a voltage corresponding to the pressure value, the voltage value is acquired and A / D conversion or the like is performed to calculate the differential pressure.

  When the engine 10 is in an idle state (S12: No), this process may be terminated.

  Next, it is checked whether or not the above-described valve state reference value has been stored. This reference value is normally stored in the memory 60b at the inspection stage when the vehicle is shipped from the factory (so-called initial value). Further, it can be stored after the engine operating state is initialized (the memory 60b is cleared) at the dealer or the maintenance shop.

  When the reference value of the valve state is not stored (S14: No), the acquired valve state is stored in the memory 60b as a reference value (S15). Thereafter, this process is terminated.

On the other hand, when the reference value of the valve state has been stored (S14: Yes), it is determined whether this idle state is an idle state after traveling using one or more of the following conditions.
The idle state when a predetermined time has elapsed after the ignition switch 61 is turned on is the idle state after traveling.
A state where the rotational speed of the engine 10 exceeds the idle rotational speed region (sometimes referred to as “running state”) after the ignition switch 61 is turned on or the engine 10 is in an idle state is a predetermined time. Let the idle state after continuing be an idle state after a run.

  When it is not in the idle state after traveling (S22: No), this process is terminated. On the other hand, when the vehicle is in the idle state after traveling (S22: Yes), the previously acquired valve state is compared with the reference value (S16). Then, it is determined whether or not the difference between the two is a predetermined value or more. The determination unit corresponds to a configuration for determining whether or not the sticking avoidance operation needs to be performed when the state of the engine transitions from the traveling state to the idle state. As a result, since the deposit adhesion amount is greater in the running state, the determination can be made only when necessary, and the processing load on the ECU 60 can be reduced.

  When the difference between the two is equal to or greater than the predetermined value (S17: Yes), the sticking avoidance operation flag on the memory 60b is set (S18). On the other hand, when the difference between them is not greater than or equal to the predetermined value (S17: No), nothing is done.

  Then, when the ignition switch 61 is turned off or the engine 10 is in the idle stop state and the engine 10 is stopped (S19: Yes), it is determined whether or not the sticking avoidance operation flag is set. When the sticking avoidance operation flag is not set (S20: No), this process ends.

  On the other hand, when the sticking avoidance operation flag is set (S20: Yes), as described above, the valves (23a, 43a) are opened and closed by a predetermined opening degree near the fully closed position, and the deposited deposit is made by the valve. The sticking avoidance operation for scraping off is executed (S21). At this time, the sticking avoidance operation flag on the memory 60b is cleared.

  Moreover, it is good also as a structure which does not determine whether it is the idle state after driving | running | working of FIG. 2, and does not perform step S22. This is because it is considered that the sticking avoidance operation flag is not set and the sticking avoidance operation is not executed because the valve state in the idle state before traveling is considered to be substantially equal to the reference value.

  In addition, the structure which uses the opening degree of valve | bulb (23a, 43a) as a valve state, a recirculation | reflux state acquisition part contains the valve opening degree detection part (23b, 43b) which detects the opening degree of a valve, and a determination part is a valve | bulb. This corresponds to determining whether or not it is necessary to perform the sticking avoidance operation based on a comparison between the detected value of the opening and the reference value of the opening. Further, the configuration using the differential pressure as the valve state is such that the recirculation state acquisition unit has a differential pressure detection unit (24, 44) that detects a differential pressure that is a pressure difference between the exhaust on the upstream side and the exhaust on the downstream side of the valve. In addition, the determination unit corresponds to determining whether or not the sticking avoidance operation needs to be performed based on a comparison between the detected value of the differential pressure and the reference value of the differential pressure.

  Further, in the comparison between the valve state of the processing of FIG. 2 and the reference value, the difference between the valve opening detection value and the reference value of the opening exceeds a predetermined value, and the differential pressure and the reference value of the differential pressure When the difference between the values exceeds a predetermined value, it may be determined that the sticking avoidance operation needs to be performed. In this way, it is possible to determine whether or not deposits have accumulated on the valve and its vicinity more accurately, and it is possible to perform the sticking avoidance operation only when it is really necessary.

  FIG. 3 shows the state (IG) of the ignition switch 61, the rotational speed (NE) of the engine 10, the EGR flow rate (that is, the flow rate sensor value), the EGR differential pressure (that is, the differential pressure sensor value), and the valve in FIG. The relationship of the opening (it may be the value of the valve opening sensor) is shown. This relationship applies to the high pressure EGR system 20 and the low pressure EGR system 40.

  When the IG transitions from the OFF state to the ON state and the engine 10 enters the idle state (IDL), the EGR flow rate, EGR differential pressure, and valve opening are predetermined values (IDL flow, IDL differential pressure, IDL opening), respectively. (State of A1).

  When the rotational speed of the engine 10 becomes higher than the idling state, the valve opening becomes zero when the engine rotational speed is equal to or higher than the predetermined rotational speed of the engine 10, and accordingly, the EGR flow rate becomes zero. In addition, since the EGR differential pressure depends on the exhaust pressure, the acceleration during fuel injection (for example, when the engine speed increases) exceeds the IDL differential pressure and the engine is not decelerated (for example, the engine speed). At the time of descent), it falls below the IDL differential pressure. In FIG. 3, when the engine is running at a constant speed when the engine speed is higher than the idling state, it varies depending on the state of fuel injection. (States of B1 and B2).

  When the engine 10 transitions from the running state to the idle state, the EGR flow rate, the EGR differential pressure, and the valve opening become predetermined values (IDL flow rate, IDL differential pressure, IDL opening) (state A2).

  When the engine 10 transitions to the idle stop state (in this case, IG is in the ON state), the EGR flow rate, the valve opening degree, and the EGR differential pressure become zero. (State C). When transitioning from the idling stop state to the idling state, the EGR flow rate, the EGR differential pressure, and the valve opening are respectively set to predetermined values (IDL flow rate, IDL differential pressure, IDL opening) (state A3).

  When the deposit is deposited on the valve (23a, 43a) and the vicinity thereof, the flow rate detected by the flow sensor (25, 45) is smaller than the IDL flow rate. The opening is made larger than the normal IDL opening. In the state of A4, the actual valve opening is shown by the solid line of the EGR valve opening, and the IDL opening (original opening, reference value) is shown by the dotted line.

  When the difference between the actual valve opening and the IDL opening is greater than or equal to a predetermined value, the sticking is avoided when the engine is stopped (that is, the ignition switch 61 is turned off or idle stopped). The operation is executed (state D).

  Further, when the deposit is deposited on the valve (23a, 43a) and its vicinity, the EGR differential pressure (indicated by a solid line) detected by the differential pressure sensor (24, 44) is the IDL differential pressure (ie, reference value: broken line). Smaller than). When the difference between the actual EGR differential pressure and the IDL differential pressure is equal to or greater than a predetermined value, the sticking avoidance operation is executed next when the engine is stopped (state D).

  Another example of the sticking avoidance control process will be described with reference to FIG. First, it is determined whether or not the engine has been started. That is, the state of the ignition switch 61 is acquired, and it is determined whether or not the ignition switch 61 is on.

  When the engine is started with the ignition switch 61 turned on (S31: Yes), the state of the engine speed sensor 17 is acquired and the engine speed of the engine 10 is included in a predetermined idle speed region. It is determined whether or not.

When the engine 10 is in the idle state (S32: Yes), the flow rate state of the exhaust gas in the EGR pipe (21, 41), that is, the value of the flow rate sensor (25, 45) is acquired (S33). Subsequently, the state of the valves 23a and 43a (ie, “valve state”) is acquired (S34). The valve state uses at least one of the following (details are the same as in FIG. 2).
-Opening degree of the valve (23a, 43a).
The output value of the differential pressure sensor (24, 44).

  Next, based on the valve state, a reference value of the exhaust gas flow rate (that is, the exhaust gas flow rate value when no deposit is accumulated in the EGR pipe) is calculated (S35). As shown in FIG. 5, the reference value of the flow rate is stored in advance in the memory 60b as a map value based on the relationship between the opening degree of the valve (23a, 43a) and the differential pressure. This corresponds to a configuration in which the reference value of the exhaust gas flow rate is stored in advance as a map value based on the relationship between the opening degree of the valve and the differential pressure. As a result, the time required to calculate the reference value of the exhaust gas flow rate and to compare it with the actual measurement value can be shortened.

  Next, as shown in FIG. 6, the previously obtained flow rate state (actual measurement value) is compared with the reference value of the flow rate based on the valve state (S36). Then, it is determined whether or not the difference between the two is a predetermined value or more.

  Returning to FIG. 4, when the difference between the two is equal to or greater than the predetermined value (S37: Yes), the sticking avoidance operation flag on the memory 60b is set (S38). On the other hand, when the difference between the two is not greater than or equal to the predetermined value (S37: No), nothing is done.

  Then, when the ignition switch 61 is turned off or the engine 10 is in the idle stop state and the engine 10 is stopped (S39: Yes), it is determined whether or not the sticking avoidance operation flag is set. When the sticking avoidance operation flag is not set (S40: No), this process ends.

  On the other hand, when the sticking avoidance operation flag is set (S40: Yes), as described above, the valves (23a, 43a) are opened and closed by a predetermined opening degree near the fully closed position, and the deposited deposit is made by the valve. The sticking avoidance operation for scraping off is executed (S41). At this time, the sticking avoidance operation flag on the memory 60b is cleared.

  In the configuration of FIG. 4, the recirculation state acquisition unit includes an exhaust flow rate measurement unit (25, 45) that measures the flow rate of the exhaust gas flowing through the recirculation passage, and the determination unit includes the detected value of the exhaust flow rate, This corresponds to determining whether or not the sticking avoidance operation needs to be performed based on the comparison with the reference value of the flow rate.

  FIG. 7 shows the state (IG) of the ignition switch 61, the rotational speed (NE) of the engine 10, the EGR flow rate (ie, the flow rate sensor value), the EGR differential pressure (ie, the differential pressure sensor value), and the valve in FIG. The relationship of the opening (it may be the value of the valve opening sensor) is shown. This relationship applies to the high pressure EGR system 20 and the low pressure EGR system 40. In addition, about the state similar to FIG. 3, the same code | symbol is provided and detailed description here is omitted.

  If the deposit is deposited on the valve (23a, 43a) and the vicinity thereof, the EGR flow rate detected by the flow rate sensor (25, 45) is lowered than usual, or the differential pressure sensor value is lowered than usual. Under the control of the ECU 60, the valve opening is increased in order to maintain the flow rate. However, the map data value of the EGR flow rate based on the valve opening or the differential pressure sensor value (the solid line portion in the E state) is larger than the actual measurement value (the broken line portion in the E state). That is, the EGR flow rate is small relative to the valve opening degree instructed by the ECU 60.

  Therefore, when the difference between the actual measured value of the EGR flow rate and the map data value (that is, the reference value) is equal to or greater than a predetermined value, the engine is then stopped (that is, the ignition switch 61 is in the off state or the idle stop state). The sticking avoidance operation is executed (state D).

  Although the embodiments of the present invention have been described above, these are merely examples, and the present invention is not limited to these embodiments, and the knowledge of those skilled in the art can be used without departing from the spirit of the claims. Various modifications based on this are possible.

1 Internal combustion engine control device
10 Engine (Internal combustion engine)
15 Intake pipe (intake passage)
21 High pressure EGR pipe (first reflux passage)
23a Valve 23b Opening sensor (recirculation state acquisition unit, valve opening detection unit)
24 Differential pressure sensor (recirculation state acquisition unit, differential pressure detection unit)
25 Flow sensor (recirculation state acquisition unit, exhaust flow measurement unit)
33a Compressor 33b Turbine 41 Low pressure EGR pipe (second return passage)
43a Valve 43b Opening sensor (recirculation state acquisition unit, valve opening detection unit)
44 Differential pressure sensor (recirculation state acquisition unit, differential pressure detection unit)
45 Flow sensor (recirculation state acquisition unit, exhaust flow measurement unit)
51 Exhaust pipe (exhaust passage)
60 Electronic control unit (determination unit, instruction information output unit)

Claims (7)

An intake passage (15) through which intake air of the internal combustion engine (10) flows;
An exhaust passage (51) through which exhaust from the internal combustion engine flows;
A reflux passage (21, 41) for recirculating exhaust gas from the exhaust passage to the intake passage;
Valves (23a, 43a) that are provided in the reflux passage and adjust the flow rate of the exhaust gas that is refluxed through the reflux passage;
A recirculation state acquisition unit that acquires a recirculation state of the exhaust gas in the recirculation passage when a predetermined estimation timing arrives;
Whether the obtained reflux state and the reference state of the reflux state stored in advance are compared, and whether or not the sticking avoidance operation for eliminating or preventing sticking of the valve needs to be performed based on the comparison result. A determination unit (60) for determining
When the determination unit determines that it is necessary to perform the sticking avoidance operation, it outputs instruction information including an instruction to execute the sticking avoidance operation when the internal combustion engine transitions from the rotation state to the stop state. An instruction information output unit (60);
A control device for an internal combustion engine, comprising:   The control apparatus for an internal combustion engine according to claim 1, wherein the estimated timing has arrived when the rotational state of the internal combustion engine transitions to an idle state. The reflux state acquisition unit includes a valve opening degree detection unit (23b, 43b) for detecting the opening degree of the valve,
The determination unit determines whether or not the sticking avoidance operation needs to be performed based on a comparison between a detected value of the opening of the valve and a reference value of the opening. The control apparatus of the internal combustion engine described in 1. The recirculation state acquisition unit includes a differential pressure detection unit (24, 44) that detects a differential pressure that is a pressure difference between the exhaust on the upstream side and the exhaust on the downstream side of the valve,
4. The method according to claim 1, wherein the determination unit determines whether the sticking avoidance operation needs to be performed based on a comparison between the detected value of the differential pressure and a reference value of the differential pressure. A control device for an internal combustion engine according to claim 1. The recirculation state acquisition unit includes an exhaust flow rate measurement unit (25, 45) for measuring a flow rate of exhaust gas flowing through the recirculation passage,
5. The determination unit according to claim 1, wherein the determination unit determines whether the sticking avoidance operation needs to be performed based on a comparison between a detected value of the flow rate of the exhaust gas and a reference value of the flow rate. A control device for an internal combustion engine according to claim 1.   The recirculation passage is a first recirculation passage (21) for recirculating exhaust gas from an upstream side of a turbine (33b) equipped in the exhaust passage to a downstream side of a compressor (33a) equipped in the intake passage. The control device for an internal combustion engine according to any one of claims 1 to 5.   The recirculation passage is a second recirculation passage (41) for recirculating exhaust gas from a downstream side of a turbine provided in the exhaust passage to an upstream side of a compressor provided in the intake passage. The control device for an internal combustion engine according to any one of the above.

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