JP2015158158A - Internal combustion engine exhaust emission control system and internal combustion engine exhaust emission control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine exhaust emission control system and an internal combustion engine exhaust emission control method capable of partially accelerating the regeneration of a particulate collector under control over a flow of exhaust gas in an exhaust emission control device depending on regeneration progress situations of a central portion and a peripheral portion of the particulate collector during a regeneration treatment on the particulate collector within the exhaust emission control device, performing the regeneration treatment efficiently without uneven regeneration, improving PM collection efficiency, and saving fuel for regeneration treatment to improve fuel economy.SOLUTION: During a regeneration treatment on a particulate collector 23, a regeneration control is exerted so that regeneration of a central portion of the particulate collector 23 is preferentially performed over that of an outer peripheral portion of the particulate collector 23 in a first state in which exhaust gas Ga flows to the entire particulate collector 23, the first state is switched to a second state in which the exhaust gas Ga easily flows to the outer peripheral portion by preventing a flow of the exhaust gas Ga to the central portion after the regeneration of the central portion, and the regeneration of the outer peripheral portion is performed after the regeneration of the central portion.

Description

  INDUSTRIAL APPLICABILITY The present invention can improve the regeneration processing capability of a particulate collection device that collects PM in exhaust gas discharged from an internal combustion engine, improve PM collection efficiency, and improve the fuel efficiency of the internal combustion engine. The present invention relates to an exhaust gas purification system for an internal combustion engine and an exhaust gas purification method thereof.

  Particulate matter called PM (Particulate Matter) is contained in the exhaust gas discharged from the internal combustion engine. The PM is collected by an exhaust gas purification device disposed in the exhaust passage and incorporated with a particulate collection device composed of various shapes and materials, and is collected by the particulate collection device and discharged into the atmosphere. Exhaust gas is purified. This particulate collection device collects PM, and as the amount of PM deposited in the particulate collection device increases, pressure loss increases and fuel consumption deteriorates, or particulate collection exceeds the PM collection limit. Because the amount of PM that passes through the device increases and the purification performance decreases, the temperature of the particulate collection device is periodically raised, and the regeneration process that recovers the PM collection ability by burning the collected PM There is a need to do.

  In the regeneration process of the particulate collection device, the amount of PM deposited in the particulate collection device is managed by, for example, the differential pressure before and after the particulate collection device. It is judged that the above has accumulated, and the regeneration process is performed. In this regeneration process, the particulate collection device is heated to a predetermined temperature or higher for a predetermined time to burn PM, and the PM collection capability of the particulate collection device is increased by repeating this collection and regeneration. Maintaining and reducing PM in exhaust gas discharged into the atmosphere. Since the regeneration process of the particulate collection device is performed under the same conditions every time, a certain amount of fuel is consumed regardless of the PM accumulation amount.

  In this connection, in order to minimize the fuel consumption required for the regeneration process, the activation rate necessary for PM combustion is calculated by calculating the combustion speed for each PM deposition amount at the time of PM combustion, and from that value There has been proposed a method of calculating the relationship between temperature and time required for PM to burn and executing regeneration under conditions that minimize fuel consumption (see, for example, Patent Document 1).

  However, in this regeneration method, the fuel consumption deterioration is optimized by optimizing the fuel consumption necessary for the regeneration process based on the PM accumulation amount in the particulate collection device. Since the regeneration processing of the central portion and the outer peripheral portion of the particle is performed in parallel, there is a difference in the progress of the regeneration processing of the central portion and the outer peripheral portion of the particulate collection device.

  Here, the difference in the progress of regeneration between the central portion and the outer peripheral portion of the particulate collection device is configured to include an oxidation catalyst device (DOC) 22X and a particulate collection device 23X shown in FIG. Explaining with reference to the provided exhaust gas purification device (DPD) 21X, in this particulate collection device 23X, PM accumulates from the center, but the relationship of the flow path area in the particulate collection device 23X. Therefore, the equivalent PM is deposited on the outer peripheral portion. However, as shown in FIG. 12, the flow rate of the exhaust gas Ga decreases as it approaches the outer periphery of the particulate collection device 23X, and the outer periphery also radiates heat to the atmosphere, resulting in a decrease in temperature. At the time of processing, reproduction near the outer peripheral part becomes difficult, and a difference in the progress of the reproduction occurs between the central part and the outer peripheral part (hereinafter, this difference in the progress of the reproduction is referred to as “unevenness of the reproduction situation”).

  In particular, since the regeneration of the central portion of the particulate collection device 23X is completed earlier than the outer peripheral portion thereof, after the regeneration of the central portion is completed, the difference between the gas flow rate at the central portion and the gas flow rate at the outer peripheral portion is further increased. The adverse effect due to the unevenness of the reproduction situation becomes larger.

  Therefore, the pressure difference between the front and rear of the particulate collection device 23X does not drop quickly, and more fuel is used than necessary to promote regeneration at the outer periphery of the particulate collection device 23X. Getting worse.

JP 2013-44256 A

  The present invention has been made in view of the above, and an object of the present invention is to provide an exhaust gas according to the progress of regeneration of the central portion and the outer peripheral portion of the particulate collection device during the regeneration processing of the particulate collection device. By controlling the state of the flow of exhaust gas that passes through the purification device, the regeneration of the particulate collection device can be partially promoted so that the regeneration processing of the particulate collection device can be performed efficiently and without unevenness of regeneration. It is possible to provide an exhaust gas purification system for an internal combustion engine and an exhaust gas purification method for an internal combustion engine that can improve PM collection efficiency and save fuel for regeneration processing and improve fuel efficiency.

  In order to achieve the above object, an exhaust gas purification system for an internal combustion engine according to the present invention is an exhaust gas purification system for an internal combustion engine comprising an exhaust gas purification device having a particulate collection device in an exhaust passage of the internal combustion engine. The flow of the exhaust gas in the exhaust gas purification device at the inlet of the gas purification device is obstructed by the first state in which the exhaust gas flows to the entire particulate collection device and the flow to the center of the particulate collection device. And a flow path changing device that switches to a second state that easily flows to the outer periphery of the particulate collection device, and controls the flow passage changing device during the regeneration process of the particulate collection device to In the state, the reproduction of the central part is performed with priority over the outer peripheral part, and the reproduction is finished when the reproduction of the central part and the outer peripheral part is completed by shifting to the second state as the reproduction proceeds. Configured with a controller for management control.

  According to this configuration, during the regeneration process of the particulate collection device, the state of the flow of the exhaust gas passing through the exhaust gas purification device is controlled according to the progress of regeneration of the central portion and the outer peripheral portion of the particulate collection device. By partially promoting the regeneration of the particulate collection device, the regeneration processing of the particulate collection device can be performed efficiently and without unevenness of regeneration, improving the PM collection efficiency, Fuel for regeneration processing can be saved and fuel consumption can be improved.

  More specifically, rapid regeneration is performed with priority on the center of the particulate collection device, and as the regeneration of the particulate collection device proceeds, the flow rate of the exhaust gas flowing through the outer periphery of the particulate collection device increases. Therefore, the heat of combustion of the fine particles due to the regeneration of the central portion that occurs in the early stage of the regeneration can be utilized in the outer peripheral portion, thereby increasing the temperature of the outer peripheral portion.

  At a later stage, by increasing the flow rate of the exhaust gas that passes through the heated outer peripheral portion, the oxygen contained in the exhaust gas can promote the combustion of the outer peripheral fine particles. The reproduction process of the apparatus can be efficiently performed, and finally, the reproduction process of the central portion and the outer peripheral portion can be performed more uniformly. As a result, the PM collection efficiency of the particulate collection device can be improved and the fuel consumption can be improved.

  Contrary to this configuration, it is conceivable that the outer peripheral portion of the particulate collection device is regenerated first and the flow rate of the exhaust gas flowing through the inner peripheral portion is increased as the regeneration proceeds. Since there is heat radiation from the outer peripheral part to the outside, only a part of the combustion heat generated at the outer peripheral part is used for regeneration of the central part, and the utilization efficiency of fuel heat is deteriorated.

  Further, in the exhaust gas purification system for an internal combustion engine described above, the regeneration is progressed by providing a period intermediate between the first state and the second state between the transition from the first state to the second state. When the transition from the first state to the second state is performed continuously or stepwise according to the above, the ratio of the exhaust gas flow rate at the central portion of the particulate collection device and the exhaust gas flow rate at the outer peripheral portion is changed more finely. This makes it possible to optimize the distribution of the exhaust gas in accordance with the progress of the regeneration at the center and the regeneration at the outer periphery.

  Further, in the exhaust gas purification system for an internal combustion engine, the exhaust gas purification device has an inlet side connection portion connected to the exhaust passage on the upstream side, and a flow passage area is increased in a tapered shape from the inlet side connection portion. A flow path expanding section, and a container having a flow path section downstream of the flow path expanding section and having a flow path section in which the particulate collection device is disposed. , Having a valve closing blade that moves in the direction of the center of the exhaust gas purifying device in a state parallel to the surface of the flow channel expanding portion, and when the valve closing blade is moved to the flow channel expanding portion side, When the first state is set and the valve closing blade is moved in the central direction so as to be set to the second state, the inner state is basically between the first state and the second state. Although there is a difference in flow rate between the peripheral part and the outer peripheral part, it is always Since all mouth exhaust gas is in a state capable of flowing, it is possible to prevent the pressure loss is greatly changed.

  In addition, in the configuration in which a partition plate that divides the flow of exhaust gas into the central part and the outer peripheral part is provided in the exhaust gas purification device, the exhaust gas in the particulate collection device can flow in when any flow path is selected Since the number of inlets of a simple cell is reduced to nearly half of the normal, the pressure loss changes greatly. In order to avoid this, if the diameter of the cell is increased or the number of cells is increased, the particulate collection device becomes thicker and larger.

  Further, an exhaust gas purification method for an internal combustion engine for achieving the above object is the exhaust gas purification method for an internal combustion engine provided with an exhaust gas purification device having a particulate collection device in an exhaust passage of the internal combustion engine. At the time of regeneration processing of the collector, in the first state where exhaust gas flows to the whole of the particulate collection device, regeneration of the central portion of the particulate collection device is given priority over the outer peripheral portion of the particulate collection device, As the regeneration progresses, the flow shifts to the second state where the exhaust gas is prevented from flowing to the central part and easily flows to the outer peripheral part, and the regeneration process is finished when the regeneration of the central part and the outer peripheral part is completed. It is the method characterized by this.

  Further, in the above exhaust gas purification method for an internal combustion engine, the progress of regeneration is provided by providing a period intermediate between the first state and the second state between the transition from the first state to the second state. To shift from the first state to the second state continuously or stepwise.

  Further, in the above exhaust gas purification method for an internal combustion engine, the exhaust gas purification device expands the flow passage area in a tapered shape from an inlet side connection part connected to the upstream side exhaust passage and the inlet side connection part. A flow path changing device is configured to include a flow path expanding section, and a container having a constant flow path area downstream of the flow path expanding section and having a flow path section in which the particulate collection device is disposed. And a valve closing vane that moves in the direction of the center of the exhaust gas purifying device in a state parallel to the surface of the flow channel expanding portion, and moves the valve closing blade toward the flow channel expanding portion side. Thus, the first state is established, and the valve closing blade is moved in the central direction to obtain the second state.

  According to these methods, the same effect as the exhaust gas purification system of the internal combustion engine can be obtained.

  According to the exhaust gas purification system for an internal combustion engine and the exhaust gas purification method thereof according to the present invention, the exhaust gas is regenerated according to the progress of regeneration of the central portion and the outer peripheral portion of the particulate collection device during the regeneration processing of the particulate collection device. By controlling the state of the flow of exhaust gas that passes through the purification device, the regeneration of the particulate collection device is partially promoted, and the regeneration processing of the particulate collection device is performed efficiently and without unevenness of regeneration. As a result, PM collection efficiency can be improved, fuel for regeneration processing can be saved, and fuel consumption can be improved.

It is a figure showing typically an example of composition of an internal-combustion engine provided with an exhaust-gas purification system of an embodiment concerning the present invention. 1 is a side sectional view schematically showing a configuration of an exhaust gas purifying apparatus according to an embodiment of the present invention. It is the figure seen from the XX direction of FIG. 2 which shows typically the mode of the blade | wing of the flow-path change apparatus arrange | positioned at the exhaust gas purification apparatus of FIG. It is a figure which shows an example of the control flow of the exhaust gas purification method of the internal combustion engine which concerns on this invention. It is a figure which shows the detail of step S400 of FIG. It is a sectional side view which shows typically the mode of the blade | wing of the flow-path change apparatus in a 1st state. It is the figure seen from the XX direction of FIG. 6 which shows typically the mode of the blade | wing of the flow-path change apparatus in a 1st state. It is a sectional side view which shows typically the mode of the blade | wing of the flow-path change apparatus in the middle of the transition from a 1st state to a 2nd state. It is the figure seen from the XX direction of FIG. 8 which shows typically the mode of the blade | wing of the flow-path change apparatus in the middle of the transition from a 1st state to a 2nd state. It is a sectional side view which shows typically the mode of the blade | wing of the flow-path change apparatus in a 2nd state. It is the figure seen from the XX direction of FIG. 10 which shows typically the mode of the blade | wing of the flow-path change apparatus in a 2nd state. It is a figure which shows typically the mode of the flow velocity of the exhaust gas which passes an exhaust-gas purification apparatus of a prior art.

  Hereinafter, an exhaust gas purification system for an internal combustion engine and an exhaust gas purification method for the internal combustion engine according to embodiments of the present invention will be described. As shown in FIG. 1, an exhaust gas purification system 2 for an internal combustion engine according to this embodiment is configured as follows.

  The engine (internal combustion engine) 10 is provided with a fuel injection device 11, an intake valve 12, and an exhaust valve 13. An intake passage 14 that communicates with the intake valve 12, an exhaust passage 15 that communicates with the exhaust valve 13, and an EGR passage 16 Is provided.

  In this intake passage 14, an air cleaner 17, a compressor 18b of a turbocharger (turbo supercharger) 18, an intercooler 19a, and an intake throttle valve 19b are provided in this order from the upstream side. The exhaust passage 15 is provided with a turbine 18a of the turbocharger 18 and an exhaust gas purification device 20 in order from the upstream side.

  The EGR passage 16 is provided by connecting an intake passage 14 downstream of the compressor 18b and an exhaust passage 15 upstream of the turbine 18a. The EGR passage 16 is provided with an EGR cooler 16a and an EGR valve 16b in this order from the upstream side. Is provided.

  Then, fresh air A introduced from the atmosphere is sent to the cylinder (cylinder) 10a via the intake valve 12 with the exhaust gas (EGR gas) Ge flowing into the intake passage 14 from the EGR passage 16 as necessary. It is done. The intake gas (A + Ge) is compressed by the piston 10b, and the fuel injected into the cylinder (cylinder) 10a burns to generate power in the engine 10.

  Exhaust gas G generated by combustion in the engine 10 flows out to the exhaust passage 15 via the exhaust valve 13, part of which flows as EGR gas Ge into the EGR passage 16, and the remaining exhaust gas Ga (= G−Ge). ) Flows into the exhaust gas purification device 20 via the turbine 18a. The exhaust gas Ga is purified by the exhaust gas purification device 20 and then released into the atmosphere as a purified exhaust gas Gc via a muffler (not shown).

  Further, as shown in FIG. 1, the exhaust gas purification device 20 constituting the exhaust gas purification system 2 has an oxidation catalyst device (DOC) 22, a particulate collection device (DPD) 23, a selective reduction in the configuration of FIG. It comprises a type catalyst device (SCR) 24, an oxidation catalyst device (DOC) 25, and the like.

  The oxidation catalyst device 22 is formed, for example, by supporting rhodium, cerium oxide, platinum, aluminum oxide, or the like on a support of a porous ceramic honeycomb structure such as a cordierite honeycomb. The oxidation catalyst device 22 oxidizes unburned fuel such as hydrocarbon (HC) or carbon monoxide (CO) in the exhaust gas Ga, and the exhaust gas Ga is raised by the heat generated by the oxidation. The downstream particulate collection device 23 is heated with this heated exhaust gas Ga.

  The particulate collection device 23 is generally formed of a monolith honeycomb wall flow type filter or the like in which the inlet and outlet of a porous ceramic honeycomb channel are alternately sealed. In many cases, an oxidation catalyst such as platinum or cerium oxide or a PM oxidation catalyst is supported. By the particulate collection device 23, PM in the exhaust gas Ga is collected by a porous ceramic wall.

  The fuel injection device 26 is a device arranged on the upstream side of the oxidation catalyst device 22 and injects unburned fuel into the exhaust passage 15. When the particulate collection device 23 is regenerated, the fuel injection device 26 is disposed in the exhaust passage 15. The unburned fuel is injected into the gas, the unburned fuel is oxidized by the downstream oxidation catalyst device 22, the exhaust gas Ga is heated by the heat generated by the oxidation, and the heated exhaust gas Ga is downstream. It has a role of raising the temperature of the side particulate collection device 23 to a temperature range in which regeneration processing is possible.

  The urea injection device 27 is a device that is disposed upstream of the selective catalytic reduction device 24 and injects urea water for NOx reduction into the exhaust passage 15. The urea water is exhausted in the exhaust passage 15. When it is injected into the gas Ga, it decomposes to produce ammonia, and has the role of detoxifying NOx into water and nitrogen by reacting ammonia with NOx in the exhaust gas Ga.

  Further, a differential pressure sensor 41 is provided to detect the differential pressure across the particulate collection device 23, and a temperature sensor 42 is provided to measure the temperature of the exhaust gas Ga flowing into the exhaust gas purification device 20. Except for FIG. 1, the selective reduction catalyst device 24, the oxidation catalyst device 25, and the differential pressure sensor 41 are not shown in the exhaust gas purification device 20 in FIG.

  Further, in the present invention, as shown in FIGS. 2 and 3, the exhaust gas purification device 20 is connected to the upstream side exhaust passage 15 and is tapered from the inlet side connection portion 21a. A container (case) 21 having a flow channel expanding portion 21b that expands the flow channel area, and a flow channel portion 21c that has a constant flow channel area downstream of the flow channel expanding portion 21b and in which the particulate collection device 23 is disposed. It comprises and comprises.

  Then, the flow of the exhaust gas Ga in the exhaust gas purification device 20 is introduced to the inlet of the exhaust gas purification device 20, the first state in which the exhaust gas Ga flows to the entire particulate collection device 23, and the particulate collection device 23. The flow path changing device 30 is configured to switch to the second state in which the flow to the central portion 23a is hindered and easily flows to the outer peripheral portion 23b of the particulate collection device 23.

  This flow path changing device 30 has a valve closing blade 32 provided on the front end side of an opening / closing shaft 31 that moves in the central direction of the exhaust gas purification device 20 in a state parallel to the surface of the flow path expanding portion 21b. Then, by moving the valve closing blade 32 toward the flow channel enlargement portion 21b, the valve closing blade 32 as shown in FIGS. 8 and 9 is centered from the first state as shown in FIGS. The state is moved to the direction, and finally the second state as shown in FIGS. This switching is performed continuously or stepwise.

  More specifically, the valve closing blade 32 has a radius from the center of the flow path expanding portion 21b of the exhaust gas purifying device 20 as viewed from the XX direction, which is the passage direction of the exhaust gas Ga, as shown in FIG. One sheet is disposed at each position that is equal in the vertical and horizontal directions (four sheets in the configuration of FIG. 3). Each of the valve closing blades 32 is shown in FIGS. 6 to 11 by moving the opening / closing shaft 31 in the axial direction by an actuator 33 such as a stepping motor operated by an output from the control device 51. The exhaust gas Gi that flows through the central portion 23a of the passage of the exhaust gas Ga is blocked.

  With this configuration, although there is a difference in flow rate between the central portion 23a and the outer peripheral portion 23b between the first state and the second state, the entire inlet of the cell of the particulate collection device 23 is always exhaust gas. Since Ga is in an inflowable state, the pressure loss can be prevented from changing greatly.

  Further, the control device 51 is configured to control the regeneration processing of the particulate collection device 23 and the flow path changing device 30. The control device 51 may be incorporated into an overall system control device (ECU) 50 that performs overall control of the engine 10 based on information from various sensors such as an accelerator opening sensor (not shown), or provided independently. May be.

  Then, the control device 51 operates the actuator 33 according to the progress of the regeneration process of the particulate collection device 23, and moves the valve closing blade 32 in a direction perpendicular to the surface of the flow path expanding portion 21b. Let Here, the position at which the valve closing blade 32 is in contact with the surface of the flow path expanding portion 21b is “full open”, and the position at which the valve closing blade 32 is closest to the center of the flow path expanded portion 21b is “fully closed”. To do.

  The amount by which the exhaust gas Ga passing through the exhaust gas purification device 20 is divided into the exhaust gas Gi flowing through the central portion 23a of the particulate collection device 23 and the exhaust gas Go flowing through the outer peripheral portion 23b depending on the moving position of the valve closing blade 32. To change. In addition, the center part 23a and the outer peripheral part 23b are comprised continuously, and the dashed-dotted line between the center part 23a and the outer peripheral part 23b shows the division for convenience, partition as a boundary, etc. However, four valve closing blades 32 are provided here, but the flow of exhaust gas Ga is not limited to this. It is only necessary to adjust the path so that the exhaust gas Ga can be divided into the exhaust gas Gi and the exhaust gas Go, and it is not necessary to limit the number.

  And in this invention, the control apparatus 51 controls the flow-path change apparatus 30 at the time of the reproduction | regeneration processing of the particulate collection apparatus 23, and gives priority to reproduction | regeneration of the center part 23a over the outer peripheral part 23b in a 1st state. In addition, the process shifts to the second state according to the progress of reproduction, and performs reproduction process control for ending the reproduction process when reproduction of the central portion 23a and the outer peripheral portion 23b is completed. The transition from the first state to the second state is performed according to the progress of regeneration, but the transition from the first state of promoting regeneration of the central portion 23a to the second state of promoting regeneration of the outer peripheral portion 23b is performed in one stage. However, a state in the middle of the transition from the first state to the second state may be interposed in a continuous or stepwise manner according to the progress of the regeneration, thereby promoting the regeneration of the central portion 23a, the central portion 23a and the outer periphery. It is good also as acceleration | stimulation of reproduction | regeneration in both parts of the part 23b, and reproduction | regeneration promotion of the outer peripheral part 23b.

  Next, an exhaust gas purification method for an internal combustion engine according to an embodiment of the present invention will be described with reference to the control flow of FIGS. The control flow of FIG. 4 is called from the high-level control flow when it is determined that regeneration of the particulate collection device 23 is necessary in the high-level control flow, and the control flow is controlled to return. Then, returning to the advanced control flow, and when it is determined that the particulate collection device 23 needs to be regenerated, it is called from the advanced control flow and is shown to be repeatedly executed during the operation of the engine 10. It is. Note that when the engine 10 stops in the middle of the control, an interrupt is generated and a return is made to return to the advanced control flow, and when the operation of the engine 10 is stopped, the operation ends with the end of the advanced control flow.

  In the advanced control flow, whether the measured value of the differential pressure across the particle collection device 23 measured by the differential pressure sensor 41 exceeds a preset differential pressure for determining regeneration start, or the amount of PM deposited It is determined whether or not the regeneration process of the particulate collection device 23 is started based on whether or not the PM accumulation amount obtained by accumulating the calculated PM accumulation amount exceeds a preset regeneration start determination PM accumulation amount. Then, the control flow of FIG. 4 is called from the advanced control flow and starts.

  When the control flow of FIG. 4 starts, when the regeneration process control of the particulate collection device 23 is started in step S100, the “regeneration process” control flow in step S200 and the “regeneration process end determination” control in step S300 are started. The flow and the control flow of “channel control” in step S400 are performed in parallel.

  The control flow of the “regeneration process” in step S200 is an exhaust gas temperature increase control for increasing the temperature of the exhaust gas Ga, and an exhaust gas temperature maintenance control for maintaining the temperature of the exhaust gas Ga after the subsequent temperature increase. .

  In this exhaust gas temperature raising control, the temperature of the exhaust gas Ga is raised by multi-injection in in-cylinder fuel injection control, and further in the exhaust gas Ga by fuel injection from the fuel injection device 26, post-injection in in-cylinder fuel injection control, etc. The unburned fuel is supplied to the catalyst, the unburned fuel is oxidized by the oxidation catalyst device 22, and the temperature of the exhaust gas Ga is burned by the oxidation heat using the oxidation heat. The temperature is increased to a starting temperature, for example, about 500 ° C. to 600 ° C.

  Further, in the exhaust gas temperature maintenance control, in the fuel injection from the fuel injection device 26 and in-cylinder fuel injection control so that the temperature of the particulate collection device 23 or the temperature of the exhaust gas Ga becomes equal to or higher than the PM combustion start temperature. Perform post-injection.

  In the exhaust gas temperature maintenance control in step S200, the end determination is made by the end determination of the regeneration process in step S300 being performed in parallel, a signal for the end determination is transmitted, and this signal is received on the step S200 side. When this signal is received, the “reproduction processing” control in step S200 is terminated.

  The control flow of step S300 is a control flow for determining the end of the regeneration process, and whether the measured value of the differential pressure across the particle collection device 23 measured by the differential pressure sensor 41 is equal to or less than the preset regeneration end determination value. Whether or not the PM accumulation amount PMc obtained by subtracting the PM removal amount ΔPMem for each control time from the PM accumulation amount PMcm at the start of regeneration is equal to or less than a preset PM determination amount PMend for end determination. Etc. When “reproduction process end determination” is performed to end the reproduction process control by any of these determinations or a combination of these determinations, this “end determination signal” is sent to the steps S200 and 400. send. Then, the control of “reproduction process end determination” in step S300 ends.

  The control flow of “flow path control” in step S400 controls the flow path changing device 30 to perform the regeneration of the central portion 23a in preference to the outer peripheral portion 23b in the first state, and the second according to the progress of the regeneration. This is the control to shift to the state. As shown in FIG. 5, the “flow path control” proceeds to step S401, and the regeneration start PM deposition amount PMcm is input from another control (for example, “regeneration processing end” control in step S300), Alternatively, it is calculated from the differential pressure before and after the particulate collection device 23.

  In the next step S402, the first determination threshold value PM1 for ending the first state and starting the transition to the second state, and the determination threshold for completing the transition to the second state, are used. A second determination threshold value PM2 is set. The first determination threshold PM1 is smaller than the regeneration start PM accumulation amount PMcm, and the second determination threshold PM2 is smaller than the first determination threshold PM1. The first determination threshold value PM1 is calculated in advance through experiments or the like, assuming, for example, the PM deposition amount PMc when the regeneration of the central portion 23a of the particulate collection device 23 is completed to some extent. As for the threshold value PM2 for 2 determination, for example, assuming the PM accumulation amount PMc when the regeneration of the central portion 23a of the particulate collection device 23 is completed to some extent, the threshold value PM2 is calculated in advance through experiments or the like, and these values are controlled. It is stored in the device 51.

  In the next step S403, the PM deposition amount PMc at the time of control is calculated by subtracting the PM removal amount ΔPMem for each control time, which is generated as the regeneration process proceeds, from the starting PM deposition amount PMcm. This PM removal amount ΔPMem is calculated by referring to map data or the like set beforehand by experiments or the like with respect to the engine operating state (engine speed and load), the temperature of the exhaust gas Ga, and the like.

  In step S404, it is determined whether or not the PM accumulation amount PMc is greater than or equal to the first determination threshold value PM1. In this determination, when the PM accumulation amount PMc is equal to or greater than the first determination threshold PM1 (YES), it is determined that the regeneration of the central portion 23a of the particulate collection device 23 has not been completed to a preset level, and the process proceeds to step S405. Then, the “center-priority channel control” is performed to fully open the valve closing blade 32 so that the flow rate of the exhaust gas Gi flowing through the center portion 23a of the particulate collection device 23 is maximized. After performing this control for a preset control time, the process goes to step S409.

  Further, when the PM accumulation amount PMc is less than the first determination threshold PM1 (NO), it is determined that the regeneration of the central portion 23a of the particulate collection device 23 has been completed to a preset level, and the process goes to step S406. .

  In this step S406, it is determined whether or not the PM accumulation amount PMc is greater than or equal to the second determination threshold value PM2. In this determination, when the PM accumulation amount PMc is equal to or greater than the second determination threshold value PM2 (YES), the center portion 23a of the particulate collection device 23 is finished to a preset level, but is sufficiently finished. If not, go to step S407 and close the valve so that the flow rate of the exhaust gas Gi flowing through the central portion 23a of the particulate collection device 23 and the flow rate of the exhaust gas Go flowing through the outer peripheral portion 23b become an appropriate ratio. “Parallel flow path control” is performed to open the blades 32 halfway. After performing this control for a preset control time, the process goes to step S409.

  In this “parallel flow path control”, as the regeneration process of the particulate collection device 23 proceeds, the flow rate of the exhaust gas Gi flowing through the central portion 23a of the particulate collection device 23 is reduced, and the particulate collection device 23 The valve closing blade 32 is changed from the fully open state to the fully closed state continuously or stepwise so as to increase the flow rate of the exhaust gas Go flowing through the outer peripheral portion 23b.

  When the opening degree of the valve closing blade 32 is changed in accordance with a preset time or a finer amount of the PM accumulation amount PMc, the ratio of the flow rate of the exhaust gas Gi and the flow rate of the exhaust gas Go is more finely defined. The distribution of the exhaust gas Ga can be optimized in accordance with the progress of the regeneration of the central portion 23a and the regeneration of the outer peripheral portion 23b.

  On the other hand, in order to simplify the control, “parallel flow path control” can be omitted. In this case, the second determination threshold value PM2 may be set to the same value as the first determination threshold value PM1.

  If it is determined in step S406 that the PM accumulation amount PMc is less than the second determination threshold value PM2 (NO), it is determined that the central portion 23a of the particulate collection device 23 has been sufficiently terminated, and the process proceeds to step S408. Then, “peripheral part priority flow path control” is performed to fully close the valve closing blade 32 so that the flow rate of the exhaust gas Go flowing through the outer peripheral part 23b of the particulate collection device 23 becomes maximum. After performing this control for a preset control time, the process goes to step S409.

  In step S409, it is determined whether the “end determination signal” from step S300 has been received. If the “end determination signal” is not received in this determination (NO), the process returns to step S403. If the “end determination signal” is received in this determination (YES), the process goes to step S410, and in the flow path control end process, the valve closing blade 32 is fully opened, End the “road control”. And it returns to the control flow of FIG.

  Then, in the control flow of FIG. 4, an “end determination signal” is transmitted from the “end of reproduction process” control in step S300, and this “end determination signal” is received. In step S200, the end of the reproduction process is performed. The process is completed and the “regeneration process” control is terminated. In step S400, the flow path control termination process is performed, and the “flow path control” control is terminated. When these three parallel controls are all finished, the process goes to return and returns to the advanced control flow. When it is determined that the particulate collection device 23 needs to be regenerated, the control flow of FIG. 4 is called from the advanced control flow and is repeatedly performed.

  In the above description, the “PM deposition amount PMc at the control point” calculated by subtracting the PM removal amount ΔPMem for each control time from the start PM deposition amount PMcm is used for the determination. “PM removal arrival amount PMem (= ΣΔPMem)” obtained by integrating the amount ΔPMem may be used for the determination. In this case, instead of setting the first determination threshold PM1 and the second determination threshold PM2, the first determination PM removal arrival amount PMe1 and the second determination PM removal arrival amount PMe2 are set. become.

  In order to simplify the control, instead of the “PM deposition amount PMc at the time of control” calculated by subtracting the PM removal amount ΔPMem for each control time from the PM deposition amount PMcm at the start time, the particulate collection device 23 The “front-rear differential pressure ΔPc” can also be used. In this case, instead of setting the first determination threshold PM1 and the second determination threshold PM2, the first determination differential pressure ΔP1 and the second determination differential pressure ΔP2 are set.

  According to the exhaust gas purification system 2 for an internal combustion engine and the exhaust gas purification method for an internal combustion engine of the present invention, the center of the particulate collection device 23 is regenerated during the regeneration process of the particulate collection device 23 disposed in the exhaust gas purification device 20. By controlling the state of the flow of the exhaust gas Ga passing through the exhaust gas purifying device 20 according to the progress of the regeneration of the part and the outer peripheral part, the regeneration of the particulate collection device 23 is partially promoted and the particulates The regeneration process of the collection device can be performed efficiently and without unevenness of regeneration, so that PM collection efficiency can be improved, fuel for regeneration process can be saved, and fuel efficiency can be improved.

  In other words, the center portion 23a of the particulate collection device 23 is preferentially regenerated and the exhaust gas Go flowing through the outer peripheral portion 23b of the particulate collection device 23 as the regeneration of the particulate collection device 23 progresses. Since the flow rate is increased, the heat of combustion of the fine particles due to the regeneration of the central portion 23a generated at the initial stage of the regeneration can be utilized in the outer peripheral portion 23b, thereby increasing the temperature of the outer peripheral portion 23b.

  At a later stage, by increasing the flow rate of the exhaust gas Go passing through the heated outer peripheral portion 23b, the combustion of the fine particles in the outer peripheral portion 23b can be promoted by the oxygen contained in the exhaust gas Go. In addition, the regeneration process of the particulate collection device 23 can be efficiently performed, and finally, the regeneration process of the central portion 23a and the outer peripheral portion 23b can be performed more uniformly. As a result, the PM collection efficiency of the particulate collection device 23 can be improved and the fuel consumption can be improved.

  In addition, a period that is intermediate between the first state and the second state is provided between the transition from the first state to the second state, and the state changes from the first state to the second state continuously or stepwise as the reproduction progresses. When shifted, the ratio of the flow rate of the exhaust gas Gi in the central portion 23a of the particulate collection device 23 and the flow rate of the exhaust gas Go in the outer peripheral portion 23b can be changed more finely. It is possible to optimize the distribution of the exhaust gas Ga in accordance with the progress of the regeneration of 23b.

  Further, when the flow path changing device 30 is configured to include the valve closing blade 32, there is basically a difference in flow rate between the central portion 23a and the outer peripheral portion 23b between the first state and the second state. However, since all the inlets of the cells of the particulate collection device 23 are always in a state in which the exhaust gas Ga can flow in, the pressure loss can be prevented from changing greatly.

  In addition, when a separate actuator is connected to each valve closing blade 32 and each valve closing blade 32 is controlled to operate independently, the central portion 23a and the outer peripheral portion 23b of the particulate collection device 23 are used. Even if the collection unevenness occurs, the regeneration can be performed more uniformly, the PM collection efficiency of the particulate collection device 23 can be improved, and the fuel efficiency can be improved.

2 Exhaust gas purification system for internal combustion engine 10 Engine (internal combustion engine)
11 Fuel injection device 14 Intake passage 15 Exhaust passage 20 Exhaust gas purification device 21 Container (case)
21a Inlet side connection part 21b Channel expansion part 21c Channel part 22 Oxidation catalyst device (DOC)
23 Fine particle collector (DPD)
24 Selective reduction catalyst system (SCR)
25 Oxidation catalyst equipment (DOC)
26 Fuel injection device 27 Urea injection device 30 Flow path changing device 31 Opening and closing shaft 32 Valve closing blade 33 Actuator 41 Differential pressure sensor 42 Temperature sensor 50 Overall system control device (ECU)
51 Control Device A Fresh Air A + Ge Intake Gas G Generated Exhaust Gas Ga Exhaust Gas (G-Ge) Flowing into Exhaust Gas Purification Device
Gc Purified exhaust gas Ge exhaust gas (EGR gas)
Gi Exhaust gas Go flowing through the central portion Exhaust gas PM1 flowing through the outer peripheral portion PM1 First determination threshold value PM2 Second determination threshold value PMc PM deposition amount PMcm Regeneration start PM deposition amount PMe1 First determination PM removal arrival amount PMe2 Second determination PM removal arrival amount PMend End determination PM deposition amount PMem PM removal arrival amount (ΣΔPMem)
ΔP1 First determination differential pressure ΔP2 Second determination differential pressure ΔPc Front-rear differential pressure ΔPMem PM removal amount

Claims (6)

In an exhaust gas purification system for an internal combustion engine comprising an exhaust gas purification device having a particulate collection device in an exhaust passage of the internal combustion engine,
The flow of the exhaust gas in the exhaust gas purification device at the inlet of the exhaust gas purification device, the first state where the exhaust gas flows to the entire particulate collection device, and the flow to the center of the particulate collection device Is provided with a flow path changing device that is switched to a second state that is prevented from flowing and easily flows to the outer peripheral portion of the particulate collection device,
During the regeneration process of the particulate collection device, the flow path changing device is controlled to regenerate the central portion in preference to the outer peripheral portion in the first state, and to the second state as the regeneration proceeds. An exhaust gas purifying system for an internal combustion engine, comprising: a control device that performs a regeneration process control that ends the regeneration process when the regeneration of the central portion and the outer peripheral portion is completed.   A period that is intermediate between the first state and the second state is provided between the transition from the first state to the second state, and the first state is continuously or stepwise from the first state according to the progress of reproduction. 2. The exhaust gas purification system for an internal combustion engine according to claim 1, wherein the system is shifted to a second state. An inlet side connecting portion for connecting the exhaust gas purifying device to the exhaust passage on the upstream side, a channel expanding portion for expanding the channel area in a tapered shape from the inlet side connecting portion, and a downstream of the channel expanding portion And having a container having a flow channel portion in which the flow channel area is constant and the particulate collection device is disposed,
The flow path changing device has a valve closing blade that moves in the central direction of the exhaust gas purification device in a state parallel to the surface of the flow channel expanding portion, and the valve closing blade is connected to the flow channel expanding portion side. 3. The exhaust of the internal combustion engine according to claim 1, wherein when the valve is moved to the first state, the first state is set, and when the valve closing blade is moved in the central direction, the second state is set. Gas purification system. In an exhaust gas purification method for an internal combustion engine comprising an exhaust gas purification device having a particulate collection device in an exhaust passage of the internal combustion engine,
During the regeneration process of the particulate collection device, the regeneration of the central portion of the particulate collection device is prioritized over the outer peripheral portion of the particulate collection device in the first state where exhaust gas flows to the entire particulate collection device. As the regeneration proceeds, the regeneration process is performed when the regeneration of the central portion and the outer peripheral portion is completed by shifting to a second state where the exhaust gas is prevented from flowing to the central portion and easily flows to the outer peripheral portion. An exhaust gas purification method for an internal combustion engine, characterized in that   A period that is intermediate between the first state and the second state is provided between the transition from the first state to the second state, and the first state is continuously or stepwise from the first state according to the progress of reproduction. 5. The exhaust gas purification method for an internal combustion engine according to claim 4, wherein the second state is shifted to a second state. The exhaust gas purifying device includes an inlet side connecting portion connected to the exhaust passage on the upstream side, a channel expanding portion that tapers the channel area from the inlet side connecting portion, and a downstream side of the channel expanding portion. The flow path area is constant, and a container having a flow path portion in which the particulate collection device is disposed is configured,
The flow path changing device is configured to have a valve closing blade that moves in the central direction of the exhaust gas purification device in a state parallel to the surface of the flow path expanding portion, and the valve closing blade is expanded to the flow path. 6. The exhaust of the internal combustion engine according to claim 4, wherein the first state is set by moving to a part side, and the second state is set by moving the valve closing blade in the central direction. Gas purification method.

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