JP2018173048A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exfoliate ash from a filter.SOLUTION: A control device 200 of an internal combustion engine 100 comprises an adhesion force estimation part for estimating an adhesion force of ash on the basis of a parameter which is in a correlation relationship with the adhesion force of the ash which adheres to a filter 71, and a pressure wave creation control part for creating a pressure wave propagating in an exhaust passage 42 toward an upstream side of an exhaust flow direction from a shut valve 44 by temporarily blocking the exhaust passage 42 by the shut valve 44. When temporarily blocking the exhaust passage 42 by the shut valve 44, the pressure wave creation control part controls a flow rate of exhaust emission which is discharged from an engine main body 1, or controls an operation speed of the shut valve 44.SELECTED DRAWING: Figure 1

Description

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

  In Patent Document 1, as a control device for a conventional internal combustion engine, an ash deposited and adhered to a particulate filter is provided in an exhaust passage downstream of the particulate filter in the exhaust flow direction in order to peel off the ash from the particulate filter. Further, there is disclosed a configuration that opens and closes a shut valve.

JP 2014-051896 A

  However, since the thing of patent document 1 mentioned above did not consider the adhesion force of the ash adhering to a particulate filter, even if it opens and closes a shut valve, there exists a possibility that an ash cannot fully be peeled from a particulate filter. there were.

  The present invention has been made paying attention to such a problem, and an object thereof is to peel off ash from a particulate filter.

  In order to solve the above problems, according to an aspect of the present invention, an engine main body, a filter provided in an exhaust passage of the engine main body for collecting particulate matter in the exhaust, and an exhaust flow direction downstream from the filter An internal combustion engine control device for controlling an internal combustion engine provided with a shut valve provided in the exhaust passage on the side for closing the exhaust passage is based on a parameter correlated with the adhesion force of the ash attached to the filter Then, an adhesion force estimation unit that estimates the adhesion force of ash and a shut valve temporarily closes the exhaust passage to generate a pressure wave that propagates the exhaust passage from the shut valve toward the upstream side in the exhaust flow direction. A pressure wave generation control unit. When the pressure wave generation control unit temporarily closes the exhaust passage by the shut valve, it controls the flow rate of the exhaust discharged from the engine body based on the adhesion force of the ash, or the operating speed of the shut valve Configured to control.

  According to this aspect of the present invention, the ash can be peeled off from the particulate filter.

FIG. 1 is a schematic configuration diagram of an internal combustion engine and an electronic control unit that controls the internal combustion engine according to the first embodiment of the present invention. FIG. 2A is a front view of the particulate filter. FIG. 2B is a side cross-sectional view of the particulate filter. FIG. 3 is a flowchart for explaining control of the pressure fluctuation amount according to the first embodiment of the present invention. FIG. 4 is a table for estimating the ash adhesion force based on the total execution time of the filter regeneration control. FIG. 5A is a flowchart for explaining the content of the pressure wave generation process when the shut valve 44 that can make the shortest opening / closing time Tmin to be equal to or less than the pulsation interval Tpul is used. FIG. 5B is a flowchart for explaining the content of the pressure wave generation process when the shut valve 44 that cannot make the shortest opening / closing time Tmin less than or equal to the pulsation interval Tpul is used. FIG. 6 is a table for setting the target exhaust flow velocity tV1 before the exhaust passage is temporarily closed by the shut valve based on the ash adhesion force. FIG. 7 is a table for setting the operating speed of the shut valve 44 when the exhaust passage is temporarily closed by the shut valve based on the ash adhesion force. FIG. 8 is a flowchart for explaining control of the pressure fluctuation amount according to the second embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals are assigned to similar components.

(First embodiment)
FIG. 1 is a schematic configuration diagram of an internal combustion engine 100 and an electronic control unit 200 that controls the internal combustion engine 100 according to a first embodiment of the present invention.

  The internal combustion engine 100 includes an engine body 1, a fuel injection device 2, an intake device 3, and an exhaust device 4.

  The engine body 1 compresses and ignites fuel in a combustion chamber formed in each cylinder 10 to generate power for driving a vehicle, for example.

  The fuel injection device 2 includes an electronically controlled fuel injection valve 20, a common rail 21, a supply pump 22, and a fuel tank 23. The fuel injection amount (injection time) and the injection pressure of fuel injected from the fuel injection valve 20 are as follows. And it is comprised so that injection timing can be changed.

  One fuel injection valve 20 is provided in each cylinder 10 so as to face the combustion chamber of each cylinder 10. The valve opening time (injection time) and the valve opening timing (injection timing) of the fuel injection valve 20 are changed by a control signal from the electronic control unit 200, and when the fuel injection valve 20 is opened, the fuel injection valve 20 opens to the combustion chamber. Fuel is injected into the tank. Each fuel injection valve 20 is connected to the common rail 21 via an injection pipe 24.

  The common rail 21 is connected to the fuel tank 23 via a pressure feed pipe 25. A supply pump 22 for pressurizing the fuel stored in the fuel tank 23 and supplying it to the common rail 21 is provided in the middle of the pressure feeding pipe 25. The common rail 21 temporarily stores the high-pressure fuel pumped from the supply pump 22. When the fuel injection valve 20 is opened, the high-pressure fuel stored in the common rail 21 is injected from the fuel injection valve 20 into the combustion chamber via the injection pipe 24. The common rail 21 has a rail pressure sensor 211 for detecting the fuel pressure in the common rail 21 (hereinafter referred to as “rail pressure”), that is, the pressure (injection pressure) of fuel injected from the fuel injection valve 20 into the combustion chamber. Provided.

  The supply pump 22 is configured to be able to change the discharge amount, and the discharge amount of the supply pump 22 is changed by a control signal from the electronic control unit 200. By controlling the discharge amount of the supply pump 22, the fuel pressure (rail pressure) in the common rail 21, that is, the injection pressure of the fuel injection valve 20 is controlled.

  The intake device 3 is a device for guiding intake air into a cylinder, and includes an intake passage 30, an intake manifold 31, and an EGR (Exhaust Gas Recirculation) passage 32.

  One end of the intake passage 30 is connected to the air cleaner 34, and the other end is connected to the intake collector 31 a of the intake manifold 31. In the intake passage 30, an air flow meter 212, a compressor 51 of the variable displacement type exhaust turbocharger 5, an intercooler 35, and an intake throttle valve 36 are provided in order from the upstream.

  The air flow meter 212 detects the flow rate of intake air (hereinafter referred to as “intake amount”) taken into the intake passage 30 via the air cleaner 34.

  The compressor 51 includes a compressor housing 51a and a compressor wheel 51b disposed in the compressor housing 51a. The compressor wheel 51b is rotationally driven by the turbine wheel 52b of the exhaust turbocharger 5 mounted on the same axis, and compresses and discharges the intake air flowing into the compressor housing 51a. The turbine 52 of the exhaust turbocharger 5 is provided with a variable nozzle 52c for controlling the rotational speed of the turbine wheel 52b. By controlling the rotational speed of the turbine wheel 52b by the variable nozzle 52c, the compressor housing 51a. The pressure (supercharging pressure) of the intake air discharged from the inside is controlled.

  The intercooler 35 is a heat exchanger that cools the intake air that has been compressed by the compressor 51 to a high temperature, for example, with traveling wind or cooling water.

  The throttle valve 36 adjusts the amount of intake air introduced into the intake manifold 31 by changing the cross-sectional area of the intake passage 30. The intake throttle valve 36 is driven to open and close by a throttle actuator 36a, and its opening (intake throttle valve opening) is detected by a throttle sensor 213.

  The intake manifold 31 is connected to the engine body 1 and distributes the intake air flowing in from the intake passage 30 to each cylinder 10 evenly. An intake collector 31a of the intake manifold 31 detects an intake pressure sensor 214 for detecting the pressure of intake air (intake pressure) sucked into the cylinder and a temperature of intake air (intake air temperature) sucked into the cylinder. An intake air temperature sensor 215 is provided.

  The EGR passage 32 communicates the exhaust manifold 41 and the intake collector 31a of the intake manifold 31, and is a passage for returning a part of the exhaust discharged from each cylinder 10 to the intake collector 31a by a pressure difference. Hereinafter, the exhaust gas flowing into the EGR passage 32 is referred to as “EGR gas”. By recirculating the EGR gas to the intake collector 31a and thus to each cylinder 10, the combustion temperature can be reduced and the emission of nitrogen oxides (NOx) can be suppressed. The EGR passage 32 is provided with an EGR cooler 37 and an EGR valve 38 in order from the upstream.

  The EGR cooler 37 is a heat exchanger for cooling the EGR gas with, for example, traveling wind or cooling water.

  The EGR valve 38 is an electromagnetic valve whose opening degree can be adjusted continuously or stepwise, and the opening degree is controlled by the electronic control unit 200. By controlling the opening degree of the EGR valve 38 and adjusting the flow rate of the EGR gas that is recirculated to the intake collector 31a, the EGR rate (the ratio of EGR gas in the intake air) is controlled.

  The exhaust device 4 is a device for discharging the exhaust in the cylinder to the outside, and includes an exhaust manifold 41 and an exhaust passage 42.

  The exhaust manifold 41 is connected to the engine body 1 and collectively introduces exhaust discharged from each cylinder 10 into the exhaust passage 42.

  The exhaust passage 42 is provided with a turbine 52 of the exhaust turbocharger 5, an exhaust aftertreatment device 43, and a shut valve 44 in order from the upstream.

  The turbine 52 includes a turbine housing 52a and a turbine wheel 52b disposed in the turbine housing 52a. The turbine wheel 52b is rotationally driven by the energy of the exhaust gas flowing into the turbine housing 52a, and drives the compressor wheel 51b attached on the same axis.

  The variable nozzle 52c described above is provided outside the turbine wheel 52b. The variable nozzle 52 c functions as a throttle valve, and the nozzle opening (valve opening) of the variable nozzle 52 c is controlled by the electronic control unit 200. By changing the nozzle opening degree of the variable nozzle 52c, the flow rate of the exhaust gas that drives the turbine wheel 52b can be changed in the turbine housing 52a. That is, by changing the nozzle opening degree of the variable nozzle 52c, the intake wheel pressure (supercharging pressure) can be changed by changing the rotational speed of the turbine wheel 52b. Specifically, when the nozzle opening of the variable nozzle 52c is reduced (the variable nozzle 52c is throttled), the exhaust flow rate increases, the rotational speed of the turbine wheel 52b increases, and the intake pressure increases.

  The exhaust aftertreatment device 43 is a device for removing the harmful substances in the exhaust discharged from the engine body 1 and discharging the exhaust to the outside air. The exhaust aftertreatment device 43 is a catalyst device 61 and a wall flow type particulate filter 71. And comprising.

  The catalyst device 61 has an exhaust purification catalyst supported on a carrier. The exhaust purification catalyst is, for example, an oxidation catalyst (two-way catalyst) or a three-way catalyst, and is not limited to these, and an appropriate catalyst can be used depending on the type and application of the internal combustion engine 100. In this embodiment, an oxidation catalyst is used as the exhaust purification catalyst. When an oxidation catalyst is used as the exhaust purification catalyst, hydrocarbon (HC) and carbon monoxide (CO), which are harmful substances in the exhaust, are oxidized and removed by the oxidation catalyst.

  The particulate filter 71 collects particulates (particulate matter) in the exhaust gas introduced therein.

  2A and 2B are diagrams for explaining the structure of the wall flow type particulate filter 71. FIG. 2A is a front view of the particulate filter 71, and FIG. 2B is a side sectional view of the particulate filter 71.

  2A and 2B, the particulate filter 71 has a honeycomb structure, and a plurality of exhaust flow passages 711 and 712 extending in parallel with each other, and a partition wall 713 that separates the exhaust flow passages 711 and 712 from each other, Is provided.

  In this embodiment, the exhaust flow passages 711 and 712 include an exhaust inflow passage 711 having an upstream end opened and a downstream end closed by a plug 715, and an exhaust having an upstream end closed by a plug 714 and an open downstream end. And an outflow passage 712. In addition, the hatched part in FIG. Therefore, the exhaust inflow passages 711 and the exhaust outflow passages 712 are alternately arranged via the thin partition walls 713. In other words, the exhaust inflow passage 711 and the exhaust outflow passage 712 are arranged such that each exhaust inflow passage 711 is surrounded by four exhaust outflow passages 712 and each exhaust outflow passage 712 is surrounded by four exhaust inflow passages 711.

  The partition wall 713 is formed of a porous material, for example, a ceramic such as cordierite, silicon carbide, silicon nitride, zirconia, titania, alumina, silica, mullite, lithium aluminum silicate, and zirconium phosphate. Therefore, as indicated by an arrow in FIG. 2B, the exhaust gas first flows into the exhaust inflow passage 711 and then flows into the adjacent exhaust outflow passage 712 through the surrounding partition wall 713. Thus, the partition wall 713 constitutes the inner peripheral surface of the exhaust inflow passage 711.

  A catalyst having an oxidation function (particulate oxidation immediate sale) is supported on both side surfaces of the partition wall 713 and the inner surface of the pores. The catalyst having an oxidation function is composed of a noble metal such as platinum Pt, rhodium Rh, or palladium Pd. The catalyst having an oxidation function is not limited to this, and may be composed of a complex oxide containing a base metal such as cerium Ce, praseodymium Pr, neodymium Nd, or lanthanum La, or a combination of a noble metal and a complex oxide. May be.

  Returning to FIG. 1, the exhaust after-treatment device 43 includes a filter temperature sensor 216 for detecting the temperature of the particulate filter 71 (hereinafter referred to as “filter temperature”), and a differential pressure across the particulate filter 71 (hereinafter referred to as “filter temperature”). And a differential pressure sensor 217 for detecting “differential pressure before and after the filter”).

  The shut valve 44 is provided in the exhaust passage 42 downstream of the exhaust aftertreatment device 43 in the exhaust flow direction. The shut valve 44 is an electromagnetic valve that can open and close the exhaust passage 42 and adjust its opening and closing speed. The opening / closing speed of the shut valve 44 is controlled by the electronic control unit 200. The reason why such a shut valve 44 is provided in the exhaust passage 42 on the downstream side in the exhaust flow direction from the exhaust aftertreatment device 43 will be described later.

  The electronic control unit 200 is composed of a digital computer and is connected to each other by a bi-directional bus 201. A ROM (read only memory) 202, a RAM (random access memory) 203, a CPU (microprocessor) 204, an input port 205, and an output port 206.

  Output signals from the rail pressure sensor 211, the air flow meter 212, the throttle sensor 213, the intake pressure sensor 214, the intake air temperature sensor 215, the filter temperature sensor 216, the differential pressure sensor 217, and the like described above are input to the input port 205. Input via the converter 207. Further, the output voltage of the load sensor 218 that generates an output voltage proportional to the depression amount of the accelerator pedal 221 (hereinafter referred to as “accelerator depression amount”) L is input to the input port 205 via the corresponding AD converter 207. Entered. Furthermore, an output signal of a crank angle sensor 219 that generates an output pulse every time the crankshaft of the engine body 1 rotates, for example, 15 ° is input to the input port 205 as a signal for calculating the engine rotational speed N and the like. . As described above, output signals of various sensors necessary for controlling the internal combustion engine 100 are input to the input port 205.

  Control components such as the fuel injection valve 20, the supply pump 22, the throttle actuator 36a, the EGR valve 38, and the variable nozzle 52c are electrically connected to the output port 206 through corresponding drive circuits 208.

  The electronic control unit 200 outputs a control signal for controlling each control component from the output port 206 based on output signals of various sensors input to the input port 205.

  The wall flow type particulate filter 71 will eventually become clogged if it continues to collect particulates. Therefore, in this embodiment, before the particulate filter 71 is clogged, the collected particulate is forcibly burned and removed to regenerate the particulate filter 71. Specifically, filter regeneration control for increasing the exhaust temperature to a predetermined regeneration target temperature (for example, 650 ° C.) when the differential pressure across the particulate filter 71 becomes equal to or higher than a predetermined allowable upper limit value set in advance. The electronic control unit 200 is configured so as to be implemented.

  However, the particulates contain sulfur oxides mainly generated from the sulfur component contained in the engine oil called ash, and the ash in the particulates may be subjected to the above-described filter regeneration control. It cannot be burned off. For this reason, even if the filter regeneration control is periodically performed, ash gradually accumulates on the particulate filter 71.

  If a large amount of this ash accumulates and adheres to the upstream end side of the exhaust inflow passage 711 of the particulate filter 71, the back pressure may increase and the engine output may decrease. In addition, if the ash is entirely deposited and adhered from the upstream end side to the downstream end side of the exhaust inflow passage 711, the particulate oxidation catalyst is deposited on the exhaust inflow passage 711. As a result of the ash, the contact between the particulates and the particulate oxidation catalyst is hindered, which may reduce the particulate oxidation rate during filter regeneration control.

  Therefore, conventionally, a shut valve 44 is provided in the exhaust passage 42 downstream of the particulate filter 71 in the exhaust flow direction, and the exhaust passage 42 is temporarily closed by the shut valve 44, so that the shut valve 44 is placed in the exhaust passage 42. Pressure wave propagating from the exhaust flow direction to the upstream side of the exhaust flow direction is generated, and the ash deposited and adhering to the particulate filter 71 due to the impact of the pressure wave is peeled off from the particulate filter 71, and downstream of the exhaust inflow passage 711. It was pushed into the end side.

  However, as a result of diligent research by the inventors, when filter regeneration control is repeatedly performed with ash deposited on the particulate filter 71, the adhesion between the particulate filter 71 and the ash (hereinafter referred to as “ash adhesion”). .) Gradually increased. Therefore, even if a pressure wave is generated in the exhaust passage 42, if the impact force applied to the particulate filter 71 by the pressure wave is small with respect to the ash adhesion force, the ash is sufficiently separated from the particulate filter 71. I found it impossible.

  The impact force applied to the particulate filter 71 by this pressure wave increases as the amplitude of the pressure wave generated in the exhaust passage 42 increases. In other words, the pressure fluctuation amount generated in the exhaust passage 42 increases as the pressure fluctuation amount increases. Therefore, in order to peel the ash from the particulate filter 71, it is necessary to control the amount of pressure fluctuation when the exhaust passage 42 is temporarily closed by the shut valve 44 in accordance with the ash adhesion force.

  Here, when the exhaust passage 42 is temporarily closed by the shut valve 44, the parameter that affects the amount of pressure fluctuation generated in the exhaust passage 42 is to open and close the shut valve 44 by maximizing the operating speed of the shut valve 44. It changes according to the relationship between the time (hereinafter referred to as the “shortest switching time”) Tmin [ms] and the pulsation interval Tpul [ms]. The pulsation interval Tpul is a time represented by 2X / C, where X is the distance from the particulate filter 71 to the shut valve 44, and C is the propagation velocity of the pressure wave in the air. That is, it is a constant value determined according to the distance X. In other words, the pulsation interval Tpul is, in other words, a pressure wave that is generated when the shut valve 44 is closed and propagates upstream is propagated from the shut valve 44 to the particulate filter 71 and then reflected by the particulate filter 71 filter. It is the time until the valve returns to the shut valve 44.

  When the shortest opening / closing time Tmin can be made equal to or shorter than the pulsation interval Tpul, a parameter that affects the amount of pressure fluctuation generated in the exhaust passage 42 when the exhaust passage 42 is temporarily closed by the shut valve 44 is to close the shut valve 44. A difference ΔV between the previous exhaust flow velocity V1 and the exhaust flow velocity V2 after closing the shut valve 44 (hereinafter referred to as “flow rate change amount”). As the flow rate change amount ΔV increases, the pressure fluctuation amount increases.

  On the other hand, when the shortest opening / closing time Tmin cannot be made shorter than the pulsation interval Tpul and the shortest opening / closing time Tmin becomes longer than the pulsation interval Tpul, the exhaust passage 42 is temporarily closed when the exhaust passage 42 is temporarily closed by the shut valve 44. A parameter that affects the amount of pressure fluctuation that occurs in the valve is the opening / closing time of the shut valve 44, that is, the operating speed of the shut valve 44. As the operating speed of the shut valve 44 is increased and the opening / closing time of the shut valve 44 is shortened, the amount of pressure fluctuation increases.

  As described above, the parameter that affects the pressure fluctuation amount varies depending on the performance of the shut valve 44 to be used. Therefore, in the present embodiment, if the shut valve 44 that can make the shortest opening / closing time Tmin less than or equal to the pulsation interval Tpul is used, the exhaust flow velocity V1 before closing the shut valve 44 is controlled according to the ash adhesion force. Control the amount of pressure fluctuation. On the other hand, if a shut valve 44 that cannot make the shortest opening and closing time Tmin less than or equal to the pulsation interval Tpul is used, the amount of pressure fluctuation is controlled by controlling the operating speed of the shut valve 44 according to the ash adhesion force. .

  Hereinafter, the control of the pressure fluctuation amount according to this embodiment will be described with reference to FIG.

  FIG. 3 is a flowchart illustrating the control of the pressure fluctuation amount according to the present embodiment. The electronic control unit 200 repeatedly executes this routine at a predetermined calculation cycle.

  In step S <b> 1, the electronic control unit 200 determines whether or not the number of executions of the filter regeneration control after the pressure wave generation process described later is performed and the ash is separated from the particulate filter 71 is equal to or greater than a predetermined number of times set in advance. Determine. Since the electronic control unit 200 can estimate that a certain amount or more of ash has accumulated and adhered to the particulate filter 71 if the number of times the filter regeneration control is performed is a predetermined number or more, the ash is removed from the particulate filter 71. In order to make it peel, it progresses to the process of step S2. On the other hand, the electronic control unit 200 ends the current process if the number of times the filter regeneration control is performed is less than the predetermined number.

  In step S2, the electronic control unit 200 estimates the ash adhesion force based on a parameter correlated with the ash adhesion force. The ash adhesion force basically tends to increase as the amount of heat applied to the ash increases. Accordingly, as a parameter correlated with the ash adhesion force, for example, the total execution time of the filter regeneration control after the pressure wave generation processing described later is performed and the ash is separated from the particulate filter 71, or the filter regeneration control is performed. For example, the total value of the time integral values of the filter temperature. The ash adhesion force increases as the total execution time of the filter regeneration control after the ash is peeled from the particulate filter 71 becomes longer. Further, the ash adhesion force increases as the total value of the time integral values of the filter temperature during the filter regeneration control after the ash is peeled off from the particulate filter 71 increases. In the present embodiment, the electronic control unit 200 refers to the table of FIG. 4 created in advance by experiment or the like, and estimates the ash adhesion force based on the total execution time of the filter regeneration control after the ash is peeled from the filter. ing.

  In step S3, the electronic control unit 200 performs a pressure wave generation process. For details of the pressure wave generation process, referring to FIGS. 5A and 5B, when the shut valve 44 that can make the shortest opening / closing time Tmin less than or equal to the pulsation interval Tpul is used, and the shortest opening / closing time Tmin less than or equal to the pulsation interval Tpul The case where the shut valve 44 that cannot be used is used will be described separately.

  FIG. 5A is a flowchart for explaining the content of the pressure wave generation process when the shut valve 44 that can make the shortest opening / closing time Tmin to be equal to or less than the pulsation interval Tpul is used.

  In step S311, the electronic control unit 200 sets the target exhaust flow velocity tV1 before temporarily closing the exhaust passage 42 by the shut valve 44 based on the ash adhesion force with reference to the table of FIG. As shown in the table of FIG. 6, the target exhaust flow velocity tV1 becomes faster as the ash adhesion force becomes larger.

  In step S312, the electronic control unit 200 controls the flow rate of the exhaust gas by adjusting, for example, the throttle opening degree based on the target exhaust gas flow rate tV1 so that the exhaust gas flow rate becomes the target exhaust gas flow rate tV1.

  In step S313, the electronic control unit 200 temporarily closes the exhaust passage 42 from the fully open state to the fully closed state so that the opening / closing time of the shut valve 44 is at least the pulsation interval Tpul, and then shuts the shut valve 44. The valve 44 is returned to the fully open state.

  FIG. 5B is a flowchart for explaining the content of the pressure wave generation process when the shut valve 44 that cannot make the shortest opening / closing time Tmin less than or equal to the pulsation interval Tpul is used.

  In step S321, the electronic control unit 200 refers to the table of FIG. 7 and sets a target operating speed of the shut valve 44 when the exhaust passage 42 is temporarily closed by the shut valve 44 based on the ash adhesion force. . As shown in the table of FIG. 7, the target operating speed of the shut valve 44 increases as the ash adhesion force increases.

  In step S322, the electronic control unit 200 temporarily closes the exhaust passage 42 from the fully open state to the fully closed state at the target operating speed set in step S3, and then returns the shut valve 44 to the fully open state.

  According to the present embodiment described above, the engine main body 1, the particulate filter 71 (filter) provided in the exhaust passage 42 of the engine main body 1 for collecting particulate matter in the exhaust, and the particulate filter 71. Also attached to the particulate filter 71 is an electronic control unit 200 (control device) that controls the internal combustion engine 100 provided with a shut valve 44 that is provided in the exhaust passage 42 downstream of the exhaust flow direction and closes the exhaust passage 42. The exhaust passage 42 is shut by the shut valve 44 by temporarily closing the exhaust passage 42 by the adhesion force estimating unit for estimating the ash adhesion force and the shut valve 44 based on a parameter correlated with the ash adhesion force. And a pressure wave generation control unit that generates a pressure wave propagating toward the upstream side in the exhaust flow direction. When the exhaust passage 42 is temporarily closed by the shut valve 44, the pressure wave generation control unit controls the flow rate of the exhaust discharged from the engine body 1 based on the ash adhesion force, or the shut valve 44 is configured to control the operating speed.

  As a result, a pressure fluctuation corresponding to the ash adhesion force is generated in the exhaust passage 42, and the ash can be peeled off from the particulate filter 71. Therefore, the ash peeled off from the particulate filter 71 is pushed into the downstream end side of the exhaust inflow passage 711 or moved from the upstream end side of the exhaust inflow passage 711 to the side opposite to the exhaust flow direction from the exhaust inflow passage 711. Or can be removed.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. This embodiment is different from the first embodiment in that the pressure wave generation process is repeatedly performed when it can be determined that the ash has not been sufficiently peeled even if the pressure wave generation process is performed once. Hereinafter, the difference will be mainly described.

  FIG. 8 is a flowchart for explaining the control of the pressure fluctuation amount according to the present embodiment. The electronic control unit 200 repeatedly executes this routine at a predetermined calculation cycle.

  In FIG. 8, from step S1 to step S3, the same processing as that in the first embodiment is performed, and thus the description thereof is omitted here.

  In step S <b> 21, the electronic control unit 200 detects the differential pressure before and after the filter immediately after the pressure wave generation processing is performed by the differential pressure sensor 217.

  In step S22, the electronic control unit 200 performs filter regeneration control.

  In step S <b> 23, the electronic control unit 200 detects the differential pressure before and after the filter immediately after the filter regeneration control is performed following the pressure wave generation process by the differential pressure sensor 217.

  In step S24, the electronic control unit 200 has a difference between the filter front-rear differential pressure detected in step S41 and the filter front-rear differential pressure detected in step S43 (hereinafter referred to as “front-rear differential pressure change amount”) equal to or greater than a predetermined value. It is determined whether or not.

  If the front-rear differential pressure change amount is equal to or greater than a predetermined value, the ash that has been obstructed by the contact between the particulate and the particulate oxidation catalyst due to the pressure wave generation process is peeled off from the particulate filter 71, and the filter is regenerated. It can be determined that the particulate oxidation rate during control is normal.

  On the other hand, if the front-rear differential pressure change amount is less than the predetermined value, the ash is not sufficiently separated from the particulate filter 71, the ash is attached to the particulate filter 71, and the particulates, the particulate oxidation catalyst, It can be judged that the contact of this is inhibited. As a result, it can be determined that the particulate oxidation rate during the filter regeneration control has decreased, and the amount of change in differential pressure across the front and rear has decreased.

  Therefore, the electronic control unit 200 ends the current process if the front-rear differential pressure change amount is equal to or greater than a predetermined value. On the other hand, if the front-rear differential pressure change amount is less than the predetermined value, the electronic control unit 200 returns to the process of step S3 and performs the pressure wave generation process again.

  According to the present embodiment described above, the same effects as those of the first embodiment can be obtained, and the ash can be more reliably separated from the particulate filter 71.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

  For example, in each of the above-described embodiments, when the NOx storage reduction catalyst is provided in the exhaust passage 42 upstream of the particulate filter 71 in the exhaust flow direction, before the pressure wave generation process is performed, the NOx storage reduction catalyst You may make it implement sulfur poisoning recovery | restoration control. The sulfur poisoning recovery control is a control for releasing the sulfur component from the NOx occlusion reduction catalyst while making the air-fuel ratio of the exhaust gas leaner than stoichiometric and setting the temperature of the NOx occlusion reduction catalyst to a high temperature of, for example, 600 ° C. or higher. . As a result, the sulfur component is supplied to the ash, and the ash adhesion is thereby reduced. Therefore, the ash can be more reliably separated from the particulate filter 71 by the pressure wave generation process.

  Further, in each of the above embodiments, the pressure wave generation processing is performed when the number of times the filter regeneration control is performed is equal to or greater than a predetermined number of times set in advance. The pressure wave generation process may be performed when the above is reached or when the fuel consumption amount exceeds a predetermined amount.

  Further, in each of the above embodiments, the engine body 1 is configured so that the fuel is subjected to compression self-ignition combustion, but may be configured to perform spark ignition combustion.

1 Engine body 42 Exhaust passage 44 Shut valve 71 Particulate filter (filter)
100 Internal combustion engine 200 Electronic control unit (control device)

Claims (1)

The engine body,
A filter provided in the exhaust passage of the engine body for collecting particulate matter in the exhaust;
A shut valve that is provided in the exhaust passage downstream of the filter in the exhaust flow direction and closes the exhaust passage;
An internal combustion engine control apparatus for controlling an internal combustion engine comprising:
An adhesion force estimation unit for estimating the adhesion force of the ash based on a parameter correlated with the adhesion force of the ash adhered to the filter;
A pressure wave generation control unit that generates a pressure wave propagating from the shut valve toward the upstream side in the exhaust flow direction by temporarily closing the exhaust passage by the shut valve;
With
The pressure wave generation control unit
When the exhaust passage is temporarily closed by the shut valve, the flow rate of exhaust gas discharged from the engine body is controlled based on the adhesion force of the ash, or the operating speed of the shut valve is controlled. ,
Control device for internal combustion engine.

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