JP4655002B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine that includes a butterfly valve body in a gas passage and adjusts a gas flow rate by opening and closing the butterfly valve body.

  In an internal combustion engine, the flow rate of gas flowing through a gas passage is adjusted, and a butterfly valve element is used for the adjustment. For example, an exhaust gas recirculation device that recirculates a part of exhaust gas to an intake system in order to improve exhaust gas characteristics is known, and in this exhaust gas recirculation device, the amount of exhaust gas recirculation is adjusted. The exhaust gas recirculation device has a communication passage that communicates an intake passage and an exhaust passage of an internal combustion engine, and a metering valve that can be opened and closed, and controls the opening of the metering valve to control the flow of the communication passage. The road area changes to adjust the exhaust gas recirculation amount. In recent years, butterfly-type metering valves have been adopted instead of poppet-type metering valves in order to improve controllability in a low flow rate region in controlling the exhaust gas recirculation amount.

  However, the exhaust gas recirculating through the communication passage contains PM (particulate matter), unburned gas, lubricating oil, etc., and if these deposit and deposit as deposits on the wall surface of the communication passage, they cool down after the internal combustion engine stops. Solidify. In particular, when this phenomenon occurs in the rotation range of the butterfly valve body, the rotation of the butterfly valve body is hindered by the solidified deposit, or the butterfly valve body is fixed to the wall surface of the communication path and cannot be rotated. As a result, there arises a problem that the recirculation amount of the exhaust gas cannot be adjusted.

  To solve this problem, Patent Document 1 proposes a method of scraping the deposit by rotating the butterfly valve body to predetermined positive and negative opening positions with the fully closed position of the butterfly valve body as a reference after the internal combustion engine is stopped. Has been.

  However, since the temperature in the communication path is high immediately after the internal combustion engine is stopped, the deposit containing PM or lubricating oil as a component is in a viscous liquefied state. Therefore, even if the butterfly valve body is rotated, the deposit in the viscous liquefied state may move only on the communication passage wall surface and may not be scraped off. Therefore, in the method of Patent Document 1 in which the butterfly valve body is rotated after the internal combustion engine is stopped, it is difficult to effectively remove the deposit.

The problem caused by deposit accumulation as described above occurs not only in the metering valve in the exhaust gas recirculation device, but also in the entire butterfly valve body provided in the flow passage of the gas containing the fuel component. Therefore, including such a butterfly valve body, it is desired to improve the response to the deposit.
JP 2003-314377 A

  The present invention has been made in view of the above problems, and a main object of the present invention is to provide a control device for an internal combustion engine that suppresses a malfunction of a butterfly valve body caused by deposits, and thus enables favorable gas flow rate adjustment. Is.

  Hereinafter, means and the like effective for solving the above-described problems will be described while showing functions and effects as necessary.

The invention according to claim 1 is applied to an internal combustion engine having a butterfly valve body provided in a gas passage of the internal combustion engine and an actuator for rotating the butterfly valve body, and the butterfly is operated by operating the actuator. In a control device for an internal combustion engine that controls opening and closing of a valve body, the amount of deposit generated is calculated according to the operating state of the internal combustion engine each time, and the accumulated amount is accumulated to estimate the amount of deposit accumulated in the gas passage Deposit amount estimating means, and deposit removing means for rotating the butterfly valve body based on the deposit accumulation amount estimated by the deposit amount estimating means in order to remove the deposit during operation of the internal combustion engine , The deposit removing means has the butterfly valve body at a rotation speed set in accordance with the rotation speed of the internal combustion engine. It is characterized by performing the rotation.

  According to this, since the deposited deposit is removed during the operation of the internal combustion engine, the deposit can be effectively removed. That is, during the operation of the internal combustion engine, a gas flow is generated in the gas passage. In this state, the butterfly valve body is rotated so that the deposit scraped by the butterfly valve body is placed on the gas flow. Can be skipped. Thereby, the deposit can be effectively removed. Further, since the deposit can be effectively removed during the operation of the internal combustion engine, the depositing excessively changes the fully closed position of the butterfly valve body or increases the sliding resistance of the butterfly valve body. This can be suppressed. As a result, good gas flow rate adjustment is possible, and the controllability of the internal combustion engine can be improved. The butterfly valve body for removing the deposit is rotated within a relatively small opening range in the vicinity of the fully closed position of the butterfly valve body.

  In addition, it is possible to estimate the deposit amount accurately by sequentially accumulating the deposit generation amount calculated according to each operation state and estimating the deposit accumulation amount in the gas passage, and suitable deposit removal according to the operation state It can be performed.

Also, the more and this for performing rotation of the butterfly valve body at a set rotation speed in accordance with the rotational speed of the internal combustion engine, in relation to the sound generated in accordance with the rotational speed of the internal combustion engine, the butterfly valve The driving sound of the body can be made inconspicuous.
According to a second and a fourth aspect of the present invention, there is provided a rotation speed detecting means for detecting a rotation speed of the butterfly valve body, and the deposit amount estimating means is configured to detect the rotation speed detecting means when the internal combustion engine is started. The deposit amount at the start is estimated based on the rotation speed of the butterfly valve body detected by the above, and the deposit accumulation amount is calculated by sequentially adding the deposit generation amount to the deposit amount at the start. There is a correlation between the deposit accumulation amount in the gas passage and the rotation speed of the butterfly valve element. In the present invention, the deposit accumulation amount at the start is estimated based on the rotational speed of the butterfly valve element. The accumulation amount at the start is the remaining accumulation amount at the end of the previous operation of the internal combustion engine. Then, the deposit accumulation amount is obtained by adding the deposit generation amount to the accumulation amount at the start in consideration of the remaining accumulation amount at the end of the previous operation, thereby increasing the deposit accumulation amount estimation accuracy.
According to a third aspect of the present invention, there is provided means for storing a deposit accumulation amount at the time of the operation stop of the internal combustion engine in a backup memory, and the deposit amount estimation means is configured to stop the previous operation when the internal combustion engine is started. The deposit accumulation amount at the time is defined as a deposit amount at start-up, and the deposit accumulation amount is calculated by sequentially adding the deposit generation amount to the start-up deposit amount. By estimating the deposit amount at the time of starting using the deposit amount at the time of the previous operation stop, it becomes possible to quickly estimate the deposit amount at the time of starting. Further, the deposit accumulation amount is obtained by adding the deposit generation amount to the remaining accumulation amount at the end of the previous operation every time, so that the estimation accuracy of the deposit accumulation amount can be improved.
The deposit amount at the time of starting can also be estimated from both the deposit amount estimated value based on the rotational speed of the butterfly valve body and the deposit amount estimated value at the previous operation stop stored in the backup memory. For example, the two deposit amount estimated values may be compared, and the larger value may be estimated as the final deposit amount. As a result, the amount of deposit at the time of start-up is estimated to be small, and it is possible to prevent the deposit from being excessively deposited without being removed even though the amount of deposit is actually required to be removed. It becomes possible.

According to a fifth aspect of the present invention, the deposit removing means performs the rotation of the butterfly valve body a number of times set based on the deposit accumulation amount estimated by the deposit amount estimating means. Thereby, the number of rotations required to remove the deposit can be appropriately set according to the deposit accumulation amount.

According to a sixth aspect of the present invention, the gas passage is an EGR passage that recirculates exhaust gas from the exhaust system to the intake system, and the butterfly valve body is provided in the EGR passage and adjusts the recirculation amount of the exhaust gas. And an EGR valve control means for controlling the recirculation amount of the exhaust gas by adjusting the opening degree of the EGR valve, and the deposit removing means has a target opening degree of the EGR valve by the EGR valve control means. The EGR valve is rotated in order to remove the deposit when the opening is equal to or less than a predetermined opening near the closed position.

  The rotation of the EGR valve for deposit removal is performed when the target opening of the EGR valve is equal to or less than a predetermined opening near the fully closed position. Thereby, the influence which acts on EGR control by rotation of the EGR valve for deposit removal can be suppressed. That is, the rotation of the EGR valve for deposit removal is performed within a relatively small valve opening range near the fully closed position of the EGR valve. Therefore, if the EGR valve is rotated to remove deposits when the EGR valve is controlled to be fully open or close to it, the EGR amount changes greatly before and after the rotation, which greatly affects EGR control. Become. In this regard, when the target valve opening is equal to or smaller than the predetermined opening, the fluctuation of the EGR amount is small before and after the EGR valve is rotated for removing the deposit, and the EGR control is performed by rotating the EGR valve for removing the deposit. Can reduce the impact.

In a seventh aspect of the invention, the deposit removing means rotates the EGR valve to remove the deposit when a fuel supply device that injects and supplies fuel to the internal combustion engine is non-injecting. It is a feature. As a result, the influence on the operating state of the internal combustion engine can be suppressed by the rotation of the EGR valve for deposit removal. That is, when fuel injection is performed and the internal combustion engine is to be rotated, the exhaust gas is recirculated by rotating the EGR valve, which causes deterioration of exhaust gas and deterioration of drivability such as rotational fluctuation. In this regard, when trying to decelerate the rotation of the internal combustion engine in the state of no fuel injection, even if the exhaust gas recirculates, the influence on the operating state of the internal combustion engine is small.

According to an eighth aspect of the present invention, the temperature of in-cylinder inflow gas formed by mixing fresh air sucked through the intake passage of the internal combustion engine and EGR gas recirculated through the EGR passage is acquired by estimation or detection. And the deposit amount estimating means calculates the deposit generation amount based on the temperature of the in-cylinder inflow gas. The amount of deposit generated depends on the temperature of in-cylinder inflow gas. Therefore, by calculating the deposit generation amount using the temperature of the cylinder inflow gas, it is possible to accurately calculate the deposit accumulation amount.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In the present embodiment, an engine control system is constructed for a diesel engine as a vehicle engine. In this control system, an intake air amount control, a fuel supply control, etc. are performed with an electronic control unit (hereinafter referred to as an ECU) as a center. We are going to carry out. First, an overall schematic configuration diagram of the engine control system will be described with reference to FIG.

  In the engine 10 shown in FIG. 1, an air cleaner 12 is provided at the most upstream portion of the intake pipe 11. An air flow meter 13 is provided on the downstream side of the air cleaner 12, and the amount of air sucked through the air cleaner 12 (new air amount) is detected. A throttle valve 14 is provided on the downstream side of the air flow meter 13. The throttle valve 14 is adjusted in opening degree by a throttle actuator 15 including a DC motor and a gear unit. An intake air temperature sensor 16 for detecting the intake air temperature and an intake pipe pressure sensor 17 for detecting the intake pipe pressure are provided on the downstream side of the throttle valve 14. The intake pipe 11 is connected to the intake port of each cylinder of the engine 10 on the downstream side of the intake temperature sensor 16 and the intake pipe pressure sensor 17.

  Fuel is injected and supplied to the engine 10 from a fuel injection device 18. The fuel supplied by injection is used for combustion together with the intake air sucked through the intake pipe 11, and the exhaust gas after combustion is discharged from the exhaust pipe 19.

  The exhaust pipe 19 is provided with an exhaust A / F sensor 20 for detecting the oxygen concentration in the exhaust gas.

  The engine 10 is provided with an exhaust gas recirculation (EGR) device for recirculating a part of the exhaust gas as EGR gas to the intake system. In other words, the EGR pipe 21 is provided between the downstream portion of the throttle valve 14 of the intake pipe 11 and the exhaust pipe 19. The EGR pipe 21 is provided with an EGR valve 22 composed of a butterfly valve body, and the opening degree of the EGR valve 22 is adjusted by an EGR valve actuator 23 composed of a DC motor, a gear unit, and the like. The opening degree of the EGR valve 22 is detected by an EGR valve opening degree sensor 23 a built in the EGR valve actuator 23.

  Here, the EGR valve 22 is a normally closed valve in which a spring is incorporated in its rotating shaft and stops at the fully closed position when the EGR valve actuator 23 is not driven. Further, the EGR valve 22 is configured to pass through the fully closed position and rotate in both forward and reverse directions.

  The engine control system includes an engine rotation speed sensor 24 that detects the rotation speed of the engine 10, an accelerator opening sensor 25 that detects the amount of accelerator operation by the driver (accelerator opening), and engine start / An ignition switch (hereinafter referred to as an IG switch) 26 that detects a stop request, a vehicle speed sensor 27 that detects the traveling speed of the vehicle, and the like are provided.

  The ECU 30 is mainly composed of a microcomputer composed of a CPU, ROM, RAM, EEPROM, etc., and by executing various control programs stored in the ROM, it acquires detection signals from the various sensors and detects them. Various controls such as intake air amount control and fuel supply control are performed based on signals and the like. Further, exhaust gas recirculation control (hereinafter referred to as EGR control) and deposit scraping control are performed.

  In the EGR control, the opening degree of the EGR valve 22 is adjusted by the EGR valve actuator 23 to adjust the amount of EGR gas recirculated to the intake system through the EGR pipe 21 (hereinafter referred to as EGR amount). Specifically, the EGR amount is determined according to the engine speed, the load of the engine 10 and the like based on a map obtained in advance, and the target opening degree of the EGR valve 22 is determined according to the EGR amount. Then, the EGR valve actuator 23 is operated so that the EGR valve 22 reaches the target opening, and the EGR amount is adjusted.

  In deposit scraping control, the deposit is removed by rotating the EGR valve 22. The EGR gas flowing through the EGR pipe 21 contains PM (particulate matter), unburned gas, engine oil, and the like. If these adhere to and accumulate on the EGR pipe 21 or the EGR valve 22, the fully closed position of the EGR valve 22 changes, or the sliding resistance of the EGR valve 22 increases and the controllability deteriorates. Therefore, when the deposit is accumulated more than a predetermined amount, the deposit is scraped off on condition that a predetermined operation condition is satisfied. In the scraping drive of the deposit, the deposit is removed by rotating the EGR valve 22 in both the forward and reverse directions through the fully closed position.

  FIG. 2 is a flowchart showing a procedure of main processing for deposit amount calculation and scraping control. FIG. 3 is a flowchart showing a processing procedure (subroutine of step S102 in FIG. 2) for calculating the deposit amount at the start. FIG. 4 is a flowchart showing a processing procedure for calculating the deposit amount during operation (subroutine of step S103 in FIG. 2). The routine shown in FIG. 2 is executed by the ECU 30 every predetermined period T after the IG switch 26 is turned on.

  In FIG. 2, in step S <b> 101, it is determined whether or not the flag FLAG is 1 by referring to a flag FLAG indicating whether or not the deposit amount has been calculated when the engine 10 is started. The flag FLAG is set to be cleared when the IG switch 26 is turned off. Therefore, after the IG switch 26 is turned on, the flag FLAG is set to 0 if the start-time deposit amount has not yet been calculated. If the decision result in the step S101 is NO, that is, if the start-time deposit amount has not yet been calculated, the process proceeds to a step S102.

  In step S102, the amount of deposit at start-up is calculated. This process will be further described with reference to the flowchart of FIG. First, in step S201, it is determined whether or not engine start is completed. Whether or not the engine start has been completed is determined by whether or not a complete explosion has been detected after cranking, for example. If the EGR valve 22 is rotationally driven at the time of cranking, startability is deteriorated, which is not appropriate. Therefore, if it is determined that the engine has not been completely started, the present subroutine is terminated without calculating the starting deposit amount.

  If it is determined in step S201 that the engine 10 has been started, the process proceeds to step S202, and parameters calculated based on various sensor information are read. Specifically, the engine rotation speed, the accelerator opening, and the like are read according to detection signals from various sensors. In step S203, various operating conditions are read. Specifically, the fuel injection amount injected from the fuel injection device 18, the target opening degree of the EGR valve 22, and the like are read. Various operating conditions are calculated by various operating condition calculation routines (not shown).

  In step S204, it is determined whether an engine operating condition for calculating the starting deposit amount is satisfied. As this operating condition, it is determined whether the target opening degree of the EGR valve 22 and the fuel injection amount are zero. If the engine operating condition for calculating the starting deposit amount is satisfied, the process proceeds to step S205. If not, the present subroutine is terminated without calculating the starting deposit amount.

  In step S205, the EGR valve 22 is scraped off once. In the present embodiment, the scraping drive is performed once by reciprocating the EGR valve 22 in the opening range of +15 degrees and −15 degrees with the fully closed position of the EGR valve 22 as a reference. In step S206, the driving speed of the EGR valve 22 at the time of scraping driving is acquired. The drive speed of the EGR valve 22 is a rotation speed when the EGR valve 22 passes through the fully closed position, and is calculated from a rate of change over time of the EGR valve opening detected by the EGR valve opening sensor 23a. Is done.

  In step S207, the deposit amount Gs at the start based on the drive speed of the EGR valve 22 acquired in step S206 is calculated. Here, the drive speed of the EGR valve 22 and the deposit amount are in a relationship as shown in FIG. 5, and this relationship is stored in advance in a map inside the ECU 30. This map is used when calculating the deposit amount Gs at the start in step S207.

  In step S208, the deposit amount Gf at the time of engine stop in the previous trip is read. In the engine control system of the present embodiment, when the IG switch 26 is turned off and the engine 10 is stopped, the main relay process is executed, and the deposit amount Gf stored in the RAM is written in the EEPROM. In this step, the deposit amount Gf at the time of engine stop in the previous trip, that is, the remaining amount of deposit in the previous trip is read.

  In step S209, the starting deposit amount Gs calculated in step S207 is compared with the deposit amount Gf at the time of engine stop in the previous trip read in step S208. The larger value is used as the final starting deposit amount Gf. In step S210, the flag FLAG is set to 1 on the assumption that the start-time deposit amount has been calculated.

  If the determination result in step S101 is YES, that is, if the calculation process of the deposit amount at start has already been performed after the IG switch is turned on, the process proceeds to step S103 to calculate the deposit amount during operation. This process will be further described with reference to the flowchart of FIG.

  First, in step S301, parameters calculated based on various sensor information are read. Specifically, the intake air amount, intake air temperature, intake air pressure, exhaust gas oxygen concentration, engine rotation speed, accelerator opening, vehicle speed, etc. are read according to detection signals from various sensors. In step S302, various operating conditions are read. Specifically, the fuel injection amount injected from the fuel injection device 18, the target opening degree of the EGR valve 22, and the like are read. Various operating conditions are calculated by various operating condition calculation routines (not shown).

  In step S303, an estimated value of the in-cylinder inflow gas temperature obtained by mixing the intake air and the EGR gas is calculated. The estimated value of the in-cylinder inflow gas temperature is calculated from the intake air amount, the EGR amount, and the like by a preset calculation formula. Note that the intake air temperature and the EGR temperature may be added as parameters when calculating the estimated temperature value of the cylinder inflow gas. In addition, as another method of estimating the in-cylinder inflow gas temperature, it is also possible to estimate the inflow gas temperature into the cylinder based on the intake air amount and the exhaust gas oxygen concentration using an engine model created using exhaust gas oxygen concentration as a parameter. Is possible. Further, the inflow gas temperature can be detected by providing a sensor.

  In step S304, deposits newly generated during the execution period T of the main routine from the operating conditions such as in-cylinder inflow gas temperature, engine speed, fuel injection amount, target opening of the EGR valve 22 (target EGR amount), and the like. A generation amount G1 is calculated. It is known that the amount of deposit generated is highly dependent on the in-cylinder inflow gas temperature, and the amount of deposit generated in a predetermined engine speed, fuel injection amount, and EGR amount operating state, and in-cylinder inflow gas temperature Are in the relationship shown in FIG. That is, the amount of deposit generated becomes large at a low temperature with a large amount of unburned gas and PM emission. Such a relationship between the in-cylinder inflow gas temperature and the deposit generation amount is stored as a map in the ECU 30 for each parameter of the engine rotation speed, the fuel injection amount, and the EGR amount. This map is used when calculating the deposit generation amount G1 in step S304.

  In step S305, a value obtained by adding the deposit generation amount G1 to the deposit amount Gf stored in the RAM at the end of the previous main routine is calculated as a new deposit amount Gf. This step is a step of adding the newly generated deposit amount from the time when the previous deposit amount is calculated to the present time.

  After calculating the deposit amount Gf in step S102 or step S103, the process proceeds to step S104. In step S104, it is determined whether or not the deposit amount Gf is larger than the scraping execution threshold value α. If the determination result in step S104 is NO, the process proceeds to step S110, the calculated deposit amount Gf is stored in the RAM, and this routine is terminated. On the other hand, if the determination result in step S104 is YES, the process proceeds to step S105. Note that, as a result of the determination conditions in step S201 and step S204 of the subroutine shown in FIG. 3, if the starting deposit amount Gf has not been calculated, the processing of the main routine is terminated without determining at this step.

  In step S105, it is determined whether the scraping operation condition is satisfied. As the scraping operation condition, it is determined whether or not the target opening degree and the fuel injection amount of the EGR valve 22 are zero. If the determination result in step S105 is NO, the process proceeds to step S110, where the deposit amount Gf calculated without executing scraping drive is stored in the RAM, and this routine is terminated. On the other hand, if the determination result in step S105 is YES, the process proceeds to step S106.

  In step S106, the number of scrapes (the number of rotations of the EGR valve 22) is determined based on the deposit amount Gf. The number of scrapes is determined in advance in relation to the deposit amount, and this relation is stored in advance in a map inside the ECU 30. This map is used when determining the number of overwriting in step S106.

  In step S107, the driving speed of the EGR valve 22 at the time of scraping driving is calculated. The driving speed of the EGR valve 22 is set to a driving speed at which the driving sound of the EGR valve 22 is not noticeable according to the volume of sound generated due to the engine rotation speed, the vehicle speed, or the like. That is, when the engine rotation speed and the vehicle speed are high, the drive speed of the EGR valve 22 is set high, and when the engine rotation speed and the vehicle speed are low, the drive speed of the EGR valve 22 is set low. The driving speed of the EGR valve 22 is determined in advance in relation to the engine rotational speed, the vehicle speed, and the like, and this relation is stored in advance in a map inside the ECU 30. This map is used when determining the drive speed of the EGR valve 22 in step S107.

  In step S108, the EGR valve 22 is scraped off. That is, the EGR valve 22 is rotated by the number of scraping times determined in step S106 at the driving speed calculated in step S107. As a result, the deposit accumulated in the vicinity of the EGR valve 22 of the EGR pipe 21 is scraped off. Note that one scraping drive in this step is also performed by reciprocatingly rotating the EGR valve 22 in the opening ranges of +15 degrees and −15 degrees with the fully closed position of the EGR valve 22 as a reference.

  In step S109, a value obtained by subtracting the deposit scraping amount G2 due to scraping from the deposit amount Gf before scraping driving is calculated as a new deposit amount Gf. The scraping amount G2 of the deposit due to scraping drive depends on the number of scraping and the driving speed, and the scraping amount G2 at the predetermined scraping number and driving speed is stored in advance in a map inside the ECU 30. In step S109, a new deposit amount Gf is calculated using the deposit scraping amount G2 calculated using this map. In step S110, the deposit amount Gf is stored in the RAM, and this routine is terminated.

  Next, an outline of this scraping control will be described based on the time chart of FIG.

  FIG. 7A is a time chart showing the deposit amount in the vicinity of the EGR valve 22. FIGS. 7B and 7C are time charts showing respective states of the EGR control and the fuel injection amount. In FIGS. 7B and 7C, the case where the target EGR valve opening and the fuel injection amount are 0 is expressed as EGR control OFF and the fuel injection OFF, respectively, and the other cases are expressed as ON. Yes.

  After turning on the IG switch 26 at the timing t0, the starting deposit amount Gf is calculated at the timing t1. After timing t1, the deposit amount Gf increases with time when EGR gas flows into the EGR pipe 21 (when EGR control is ON). At timing t2, the scraping execution threshold value α is reached. At timing t2, EGR control and fuel injection are in an OFF state. Therefore, at timing t2, the scraping operation condition of step S105 is established, and scraping driving is started. From timing t2 to timing t3, scraping driving is executed a predetermined number of times at a predetermined valve driving speed, and as a result, the deposit amount Gf decreases.

  After timing t3, when the EGR control is ON, the deposit amount Gf again increases with time. The deposit amount Gf reaches the scraping execution threshold value α at timing t4. However, at timing t4, EGR control and fuel injection are in an ON state, and the scraping operation condition in step S105 is not satisfied. Therefore, the scraping drive is not started at the timing t4.

  Thereafter, when the scraping operation condition is satisfied at timing t5, scraping driving is started. From timing t5 to timing t6, scraping driving is executed a predetermined number of times at a predetermined valve driving speed, and as a result, the deposit amount Gf decreases.

  After timing t6, when the EGR control is ON, the deposit amount Gf increases with time again. Then, at timing t7, the IG switch 26 is turned off and the engine 10 is stopped. As described above, when the IG switch 26 is turned off and the engine 10 is stopped, the main relay process is executed, and the deposit amount Gf stored in the RAM is written in the EEPROM.

  FIG. 8 shows the deposit state before and after scraping drive (for example, t2 and t3 in FIG. 7). In FIG. 8A, the deposit before the scraping drive is performed is shown as X. On the other hand, when the EGR valve 22 is rotated a predetermined number of times at a predetermined valve driving speed, the deposit is indicated as Y as shown in FIG. That is, the deposit in the rotation area of the EGR valve 22 is scraped off by executing the scraping drive.

  According to the embodiment described above in detail, the following excellent effects can be obtained.

  By performing the scraping drive while the engine 10 is in operation, the deposit can be effectively removed. That is, during the operation of the engine 10, an EGR gas flow is generated from the exhaust pipe 19 to the intake pipe 11 in the EGR pipe 21. Then, by performing scraping driving while the EGR gas flow is generated in the EGR pipe 21, the deposit scraped out by the EGR valve 22 can be carried on the EGR gas flow and effectively deposited. Can be removed. Since the deposit can be removed effectively, the deposit is excessively accumulated during the operation of the engine 10, thereby changing the fully closed position of the EGR valve 22 or increasing the sliding resistance of the EGR valve 22. This can be suppressed. As a result, good gas flow rate adjustment is possible, and the controllability of the engine 10 can be improved.

  During the operation of the engine 10, it is possible to prevent the deposit from being excessively accumulated by executing the scraping drive every time the deposit amount Gf exceeds the predetermined scraping execution threshold value α. Thereby, even if the scraping drive is not executed when the engine 10 is stopped, it is possible to suppress a situation where the deposit is solidified after the engine 10 is stopped and the EGR valve 22 is fixed to the wall surface of the EGR pipe 21 and cannot be rotated. . Further, by not performing the scraping drive after the engine 10 is stopped, it is possible to avoid the problem that the driving sound of the EGR valve 22 is noticeable after the engine 10 is stopped. Furthermore, since the EGR valve 22 is not driven after the engine 10 is stopped, the power of the in-vehicle battery is not consumed after the engine 10 is stopped, and the influence on the next engine startability can be suppressed.

  Since the number of times of scraping at the time of scraping driving is determined based on the deposit amount Gf, an appropriate number of scrapes required for removing the deposit can be set according to the deposit amount. Further, since the driving speed of the EGR valve 22 is set according to the loudness generated due to the engine rotation speed, the vehicle speed, etc., the driving sound of the EGR valve 22 at the time of scraping driving is set to the engine sound or the like. Inconspicuous.

  Since the scraping drive is performed when the target valve opening degree of the EGR valve 22 is 0, it is possible to suppress the EGR control from being affected by the scraping drive. That is, the scraping drive is performed within a relatively small valve opening range of +15 degrees and −15 degrees with respect to the fully closed position of the EGR valve 22. Therefore, if scraping drive is performed when the EGR valve 22 is controlled to be fully opened or close to it, the EGR amount greatly changes before and after the scraping drive, and the influence on the EGR control is increased. In this respect, when the target valve opening is 0, the influence of the rotation of the EGR valve 22 is small before and after the scraping drive, and the influence on the EGR control by the scraping drive can be reduced.

  The scraping drive is performed when the fuel injection amount is zero. Thereby, the influence which it gives to the driving | running state of the engine 10 by scraping drive can be suppressed. That is, when fuel injection is performed and the engine is to be rotated, the EGR valve 22 is rotated to recirculate the EGR gas, which causes deterioration of exhaust gas and drivability deterioration such as rotational fluctuation. In this regard, when the fuel injection amount is set to 0 and the engine rotation is to be decelerated, even if the EGR gas recirculates and the rotational fluctuation occurs, the influence on the operating state of the engine 10 is small.

  Since the deposit generation amount G1 calculated according to each engine operating state is sequentially accumulated and the deposit amount Gf accumulated on the EGR pipe 21 is calculated, the deposit amount Gf can be calculated with high accuracy and suitable for the operating state. Scraping control is possible. Further, the deposit generation amount G1 is calculated from the EGR gas temperature and various operating states, and the deposit amount Gf is calculated using the deposit generation amount G1. The deposit generation amount G1 largely depends on the in-cylinder inflow gas temperature. Therefore, by calculating the deposit generation amount G1 using the cylinder inflow gas temperature and calculating the deposit amount Gf using the deposit generation amount G1, the calculation accuracy of the deposit amount Gf can be improved.

  The starting deposit amount Gs based on the driving speed of the EGR valve 22 at the time of starting is compared with the deposit amount Gf (the remaining amount of deposit) when the engine is stopped in the previous trip, and the larger value is the final starting deposit. The amount is Gf. As a result, the deposit amount at start-up is estimated to be small, and it is possible to prevent the deposit from being excessively deposited without being scraped off even though the deposit amount actually needs to be scraped off. It becomes.

  In addition, this invention is not limited to the content of description of the said embodiment, For example, you may implement as follows.

  In the above embodiment, the final starting deposit amount Gf of the engine 10 is calculated from the starting deposit amount Gs based on the driving speed of the EGR valve 22 and the deposit amount Gf when the engine is stopped in the previous trip. However, it may be calculated from only one of them. Thereby, the deposit amount at the time of starting of the engine 10 can be easily calculated. Further, when the deposit amount Gf at the time of engine stop in the previous trip is used as the deposit amount at the time of starting, the deposit amount at the time of starting can be determined promptly after the IG switch 26 is turned on.

  In the above embodiment, the scraping drive is performed when the target valve opening of the EGR valve 22 is 0. However, the scraping drive may be performed when the target valve opening is equal to or less than a predetermined valve opening. When the target valve opening is small, the fluctuation of the EGR amount is small before and after the scraping drive. Therefore, even when the target valve opening is small, the influence on the EGR control by the scraping drive can be reduced.

  In step S201, it is determined whether or not the engine 10 has been completely started. If it has not been completed, the subroutine shown in FIG. 3 is terminated without calculating the starting deposit. However, even before the engine start is completed, the start-time deposit may be calculated after turning on the IG switch 26 and before starting cranking.

  In step S207, the deposit amount Gs at the start is calculated using the map storing the relationship shown in FIG. However, instead of this method, the deposit amount Gs at the time of starting is calculated from a difference between the driving speed of the EGR valve 22 when there is no deposit and the driving speed of the EGR valve 22 acquired in step S206 by a predetermined calculation formula. You may make it calculate.

  In the above embodiment, the scraping control is performed on the EGR valve 22 provided in the EGR pipe 21, but the scraping control may be performed on the throttle valve 14. There is a risk that deposits may adhere to the throttle valve 14 due to air flowing through the intake pipe 11 or blowback of combustion gas from the combustion chamber of the engine 10. Further, in the engine 10 that performs EGR control, deposits due to EGR gas may adhere. In this regard, by performing scraping control on the throttle valve 14, it is possible to prevent the throttle valve 14 from being hindered from being prevented and to control a good intake air amount.

The whole block diagram which shows the outline of an engine control system. The flowchart which shows the main process of calculation of deposit amount, and scraping-off control. The flowchart which shows the calculation process of the deposit amount at the time of starting. The flowchart which shows the calculation process of the deposit amount at the time of driving | running | working. The figure which shows the relationship between the amount of deposits, and the drive speed of an EGR valve. The figure which shows the relationship between cylinder inflow gas temperature and the amount of deposit production. A time chart showing an outline of scraping control. (A) is a figure which shows the accumulation condition of the deposit before implementation of scraping drive, (b) is after implementation of scraping drive.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Engine, 11 ... Intake pipe, 14 ... Throttle valve, 15 ... Throttle valve actuator, 18 ... Fuel injection device, 19 ... Exhaust pipe, 21 ... EGR piping, 22 ... EGR valve, 23 ... EGR valve actuator, 23a ... EGR Valve opening sensor, 24 ... engine rotation speed sensor, 26 ... IG switch, 27 ... vehicle speed sensor, 30 ... ECU.

Claims (8)

An internal combustion engine that is applied to an internal combustion engine having a butterfly valve body provided in a gas passage of the internal combustion engine and an actuator that rotates the butterfly valve body, and controls the opening and closing of the butterfly valve body by operating the actuator. In the engine control device,
A deposit amount estimating means for calculating a deposit generation amount according to the operation state of the internal combustion engine each time, and accumulating the deposit generation amount to estimate a deposit accumulation amount accumulated in the gas passage;
Deposit removing means for rotating the butterfly valve body based on the deposit accumulation amount estimated by the deposit amount estimating means to remove the deposit during operation of the internal combustion engine ;
The control apparatus for an internal combustion engine, wherein the deposit removing means rotates the butterfly valve body at a rotation speed set according to the rotation speed of the internal combustion engine. A rotation speed detecting means for detecting the rotation speed of the butterfly valve body;
The deposit amount estimating means estimates a starting accumulation amount based on a rotation speed of the butterfly valve body detected by the rotation speed detecting means at the time of starting the internal combustion engine, and the deposit amount is calculated to the deposit amount at the start. 2. The control apparatus for an internal combustion engine according to claim 1 , wherein the deposit accumulation amount is calculated by sequentially integrating the generation amount. Means for storing a deposit amount when the internal combustion engine is stopped in a backup memory;
The deposit amount estimating means sets the deposit accumulation amount at the time of the previous operation stop at the start of the internal combustion engine as a start accumulation amount, and sequentially accumulates the deposit generation amount to the deposit amount at the start. The control apparatus for an internal combustion engine according to claim 1 , wherein:   An internal combustion engine that is applied to an internal combustion engine having a butterfly valve body provided in a gas passage of the internal combustion engine and an actuator that rotates the butterfly valve body, and controls the opening and closing of the butterfly valve body by operating the actuator. In the engine control device,
  A deposit amount estimating means for calculating a deposit generation amount according to the operation state of the internal combustion engine each time, and accumulating the deposit generation amount to estimate a deposit accumulation amount accumulated in the gas passage;
  Deposit removing means for rotating the butterfly valve body based on the deposit accumulation amount estimated by the deposit amount estimating means to remove the deposit during operation of the internal combustion engine;
  Rotation speed detecting means for detecting the rotation speed of the butterfly valve body,
  The deposit amount estimating means estimates a starting accumulation amount based on a rotation speed of the butterfly valve body detected by the rotation speed detecting means at the time of starting the internal combustion engine, and the deposit amount is calculated to the deposit amount at the start. A control apparatus for an internal combustion engine, wherein the amount of deposit accumulation is calculated by sequentially accumulating generation amounts. The deposit removal means performs the rotation of the butterfly valve body a number of times set based on the deposit accumulation amount estimated by the deposit amount estimation means . The control apparatus of the internal combustion engine described in 1. The gas passage is an EGR passage that recirculates exhaust gas from the exhaust system to the intake system,
The butterfly valve body is an EGR valve that is provided in the EGR passage and adjusts the recirculation amount of the exhaust gas,
EGR valve control means for controlling the recirculation amount of the exhaust gas by adjusting the opening of the EGR valve,
The deposit removing means rotates the EGR valve to remove the deposit when the target opening degree of the EGR valve by the EGR valve control means is equal to or less than a predetermined opening degree near the fully closed position. control apparatus for an internal combustion engine according to any one of claims 1 to claim 5, characterized. Said deposit removal means, when injecting fuel supplying fuel supply apparatus of the non-injection to the internal combustion engine, according to claim 6, characterized in that the rotation of the EGR valve in order to remove the deposits Control device for internal combustion engine. Means for estimating or detecting a temperature of in-cylinder inflow gas formed by mixing fresh air sucked through the intake passage of the internal combustion engine and EGR gas recirculated through the EGR passage;
The control apparatus for an internal combustion engine according to claim 6 or 7 , wherein the deposit amount estimating means calculates the deposit generation amount based on a temperature of the in-cylinder inflow gas.

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