WO2016103417A1 - エンジンの排気浄化装置 - Google Patents
エンジンの排気浄化装置 Download PDFInfo
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- WO2016103417A1 WO2016103417A1 PCT/JP2014/084381 JP2014084381W WO2016103417A1 WO 2016103417 A1 WO2016103417 A1 WO 2016103417A1 JP 2014084381 W JP2014084381 W JP 2014084381W WO 2016103417 A1 WO2016103417 A1 WO 2016103417A1
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- reducing agent
- precursor
- channel
- outside air
- aqueous solution
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
- F01N3/2066—Selective catalytic reduction [SCR]
- F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
- F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
- F01N13/0097—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series the purifying devices are arranged in a single housing
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
- F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
- F01N3/033—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices
- F01N3/035—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices with catalytic reactors, e.g. catalysed diesel particulate filters
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
- F01N3/2066—Selective catalytic reduction [SCR]
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N9/00—Electrical control of exhaust gas treating apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
- F01N2240/02—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being a heat exchanger
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
- F01N2560/06—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being a temperature sensor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2610/00—Adding substances to exhaust gases
- F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2610/00—Adding substances to exhaust gases
- F01N2610/10—Adding substances to exhaust gases the substance being heated, e.g. by heating tank or supply line of the added substance
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2610/00—Adding substances to exhaust gases
- F01N2610/14—Arrangements for the supply of substances, e.g. conduits
- F01N2610/1473—Overflow or return means for the substances, e.g. conduits or valves for the return path
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2610/00—Adding substances to exhaust gases
- F01N2610/14—Arrangements for the supply of substances, e.g. conduits
- F01N2610/1493—Purging the reducing agent out of the conduits or nozzle
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
- F01N2900/06—Parameters used for exhaust control or diagnosing
- F01N2900/18—Parameters used for exhaust control or diagnosing said parameters being related to the system for adding a substance into the exhaust
- F01N2900/1806—Properties of reducing agent or dosing system
- F01N2900/1811—Temperature
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Definitions
- the present invention relates to an engine exhaust gas purification device that selectively reduces and purifies nitrogen oxide (NOx) in exhaust gas with a reducing agent.
- NOx nitrogen oxide
- An exhaust purification device comprising a selective catalytic reduction converter that selectively reduces and purifies NOx using ammonia as a reducing agent in an engine exhaust system, and an injection nozzle that injects an aqueous urea solution (precursor of reducing agent) upstream of the exhaust. It has been known. Since the urea aqueous solution freezes at about ⁇ 11 ° C., as described in Patent Document 1, after the engine is stopped, the freezing change of the residual urea aqueous solution in the injection nozzle and the reducing agent supply channel is monitored and the freezing change is monitored. Accordingly, a technique is known in which the residual urea aqueous solution is discharged into the exhaust pipe by temporarily opening the injection nozzle.
- the present invention provides a configuration in which at least a part of the reducing agent or its precursor supplied to the injection nozzle is heated and returned to the reducing agent tank so that the thawing time can be further shortened. Let it be an issue.
- an engine exhaust purification apparatus of the present invention in an exhaust passage of an engine, and a selective reduction catalytic converter that selectively reduces and purifies nitrogen oxides in exhaust using a reducing agent
- An injection device for injecting and supplying a liquid reducing agent or a precursor thereof upstream of the exhaust gas of the selective catalytic reduction converter, a tank for storing the liquid reducing agent to be supplied from the injection device or a precursor thereof, and the tank to the injection nozzle
- a reducing agent supply flow path for supplying a liquid reducing agent or a precursor thereof, and a branching from the middle of the reducing agent supply flow path to return a part of the liquid reducing agent or a precursor thereof to the tank; and
- a reductant circulation passage a part of which is arranged to be able to exchange heat with a heat source, a reductant recirculation valve that controls the flow of the liquid reductant or its precursor to the reductant recirculation passage, in front
- a temperature detection unit that detects a temperature of the
- the thawing time can be further shortened.
- FIG. 1 shows an example of an exhaust purification device that purifies particulate matter (PM) and NOx in exhaust gas.
- An intake pipe 120 connected to the intake manifold 110 of the diesel engine 100 includes an air cleaner 130 that filters dust and the like in the intake air along a direction of intake air flow, a compressor 142 of the turbocharger 140 that supercharges intake air, and a compressor 142.
- An intercooler 150 that cools the intake air that has passed and an intake collector 160 that smoothes the intake pulsation are arranged in this order.
- an exhaust pipe 180 connected to the exhaust manifold 170 of the diesel engine 100 includes a turbine 144 of a turbocharger 140, a continuously regenerating diesel particulate filter (Diesel Particulate Filter, hereinafter referred to as “DPF”) along the exhaust circulation direction.
- DPF diesel particulate filter
- a device 190, an injection nozzle 200 for supplying and supplying a urea aqueous solution as a reducing agent precursor, and a urea selective reduction catalytic converter system 225 are arranged in this order.
- the continuous regeneration type DPF device 190 includes a DOC (Diesel Oxidation Catalyst) converter 192 that oxidizes at least NO (nitrogen monoxide) to NO 2 (nitrogen dioxide), and a DPF 194 that collects and removes PM.
- DOC Diesel Oxidation Catalyst
- DPF 194 that collects and removes PM.
- a CSF Catalyzed Soot Filter
- a catalyst active component and additive component
- the urea selective reduction catalytic converter system 225 is a selective reduction catalytic converter 210 that selectively reduces and purifies NOx using ammonia generated from an aqueous urea solution as a reducing agent, and an oxidation catalytic converter that oxidizes ammonia that has passed through the selective reduction catalytic converter 210. 220.
- the urea aqueous solution stored in the reducing agent tank 230 is sucked by the reducing agent addition unit 240 installed in the middle of the reducing agent supply channels 250 and 251, and passes through the reducing agent supply channels 250 and 251 to the injection nozzle 200. Supplied.
- outside air air
- the end of the reducing agent circulation channel 256 is connected in a loop with the suction end of the reducing agent supply channel 250 in the reducing agent tank 230. Although the details of the reducing agent circulation channel 256 will be described later, a part thereof is disposed near the heat source.
- the urea aqueous solution can go back and forth between the reducing agent tank 230 and the flow path at the connection point between the reducing agent supply channel 250 and the reducing agent circulation channel 256 in the reducing agent tank 230 (reducing agent tank 230).
- the urea aqueous solution is sucked into the reducing agent supply flow path 250 from the water or the urea aqueous solution is returned from the reducing agent circulation flow path 256 to the reducing agent tank 230), and one or a plurality of communication holes 235 are provided. Therefore, the urea aqueous solution is sucked into the reducing agent supply channel 250 through the communication hole 235 provided in the channel and is supplied to the injection nozzle 200.
- an electric heater is disposed around the reducing agent supply flow channels 250 and 251 (not shown).
- the reducing agent addition unit 240 will be described later, not only the urea aqueous solution is supplied from the reducing agent tank 230 to the injection nozzle 200 but also the flow (flow rate, path) of the urea aqueous solution and the reducing agent circulation channel 256. Control the introduction of outside air into the.
- An exhaust pipe 180 positioned between the continuous regeneration type DPF device 190 and the injection nozzle 200 has an exhaust temperature sensor 260 for measuring the exhaust temperature (exhaust temperature) in order to grasp the active state of the selective catalytic reduction converter 210. It is attached. Further, a urea aqueous solution temperature sensor 265 for measuring the temperature of the urea aqueous solution (urea aqueous solution temperature) is attached to the reducing agent tank 230. Output signals of the exhaust temperature sensor 260, the urea aqueous solution temperature sensor 265, and the outside air temperature sensor 290 are input to a reducing agent addition control unit (DCU: Control Unit) 270 having a built-in computer.
- DCU Control Unit
- the DCU 270 electronically controls the diesel engine 100 via an in-vehicle network such as CAN (Controller Area Network) so that the rotation speed and load as an example of the engine operating state can be read at an arbitrary time.
- a unit (ECU: Engine Control Unit) 280 is communicably connected.
- the DCU 270 electronically controls the reducing agent addition unit 240 based on the exhaust temperature, the rotational speed, and the load by executing a control program stored in a nonvolatile memory such as a flash ROM (Read Only Memory). Also, the DCU 270 performs a urea aqueous solution thawing process, which will be described later, based on the outside air temperature and the urea aqueous solution temperature.
- a nonvolatile memory such as a flash ROM (Read Only Memory).
- the DCU 270 performs a urea aqueous solution thawing process, which will be described later, based on the outside air temperature and the urea aqueous solution temperature.
- a state quantity closely related to the engine torque such as a fuel injection amount, an intake air flow rate, an intake pressure, a supercharging pressure, and an accelerator opening degree can be used.
- the rotational speed and load of the diesel engine 100 may be directly detected using a known sensor instead of reading from the ECU 280.
- exhaust from the diesel engine 100 is introduced into the DOC converter 192 of the continuous regeneration type DPF device 190 through the exhaust manifold 170 and the turbine 144 of the turbocharger 140.
- the exhaust gas introduced into the DOC converter 192 flows to the DPF 194 while NO is oxidized to NO 2 .
- NO is oxidized to NO 2 .
- PM in the exhaust gas is collected, and PM is continuously oxidized (incinerated) using NO 2 generated by the DOC converter 192.
- the urea aqueous solution supplied (added) from the injection nozzle 200 according to the engine operating state is hydrolyzed using exhaust heat and water vapor in the exhaust, and converted into ammonia that functions as a reducing agent.
- This ammonia is selectively reduced and reacted with NOx in the exhaust gas in the selective catalytic reduction converter 210 to be purified into harmless H 2 O (water) and N 2 (nitrogen).
- NO is oxidized to NO 2 by the DOC converter 192, and the ratio of NO to NO 2 in the exhaust gas is improved to be suitable for the selective reduction reaction. Therefore, the NOx purification rate in the selective catalytic reduction converter 210 is increased. Can be improved.
- ammonia that has passed through the selective catalytic reduction converter 210 is oxidized by the oxidation catalytic converter 220 disposed downstream of the exhaust gas, so that it is possible to suppress the ammonia from being released into the atmosphere as it is.
- FIG. 2, FIG. 3 and FIG. 4 show an embodiment of the layout of the reducing agent circulation channel 256.
- FIG. A part of the reducing agent circulation channel 256 is disposed near the heat source so that the urea aqueous solution flowing through the channel is heated.
- a part of the reducing agent circulation flow path 256 shown in FIG. 2 constitutes an upper surface and a side surface of a housing 300 that houses a continuous regeneration type DPF device 190, a urea selective reduction catalytic converter system 225, and an exhaust pipe 180 connecting them. It is arranged to receive a heat exchange plate that As a result, the urea aqueous solution flowing through the reducing agent circulation channel 256 undergoes heat exchange with the heat exchange plate heated by the exhaust heat of the exhaust pipe 180 and is heated back to the reducing agent tank 230.
- the reducing agent circulation flow path 256 may be arranged so as to be able to exchange heat with the heat source.
- the reducing agent circulation flow path 256 may be arranged so as to cover a heat exchange plate constituting the lower surface and side surface of the housing 300.
- FIG. 3 shows a layout of another reducing agent circulation channel 256 as viewed from above the housing 300 of FIG.
- the reducing agent circulation channel 256 of FIG. 3 may also be disposed so as to cover the heat exchange plate that constitutes the lower surface and the side surface of the housing 300.
- the reducing agent circulation channel 256 may be arranged in a spiral around the exhaust pipe 180.
- the reducing agent addition unit 240 includes a pump 242 that sucks the urea aqueous solution into the reducing agent supply flow path 250, a flow rate control valve 244 for controlling the flow rate of the urea aqueous solution, and a flow path switching valve for switching the route of the urea aqueous solution. 246.
- the flow control valve 244 an existing one such as a butterfly valve or a globe valve can be used, and is controlled by the DCU 270 by an existing method such as an actuator.
- the flow path switching valve 246 will be described with reference to FIG. 5 (and FIGS. 6 and 7).
- the flow path switching valve 246 includes a first rotary valve 247 and a second rotary valve 248 disposed inside the first rotary valve 247.
- the first rotary valve 247 and the second rotary valve 248 are rotationally controlled by the DCU 270 by an existing method such as an actuator.
- the first rotary valve 247 has a “T” -shaped channel formed in the rotor, and has two rotation positions (first and second rotation positions) of 0 ° or 90 ° clockwise. Have. In the first rotation position (FIGS. 5 and 6), the outside air introduction channel 254 is closed, and the upstream reducing agent supply channel 250, the downstream reducing agent supply channel 251 and the reducing agent circulation channel 256 are closed. The three parties can communicate. Further, at the second rotation position (FIG. 7), the downstream side reducing agent supply channel 251 is closed, and the outside air introduction channel 254, the reducing agent circulation channel 256, and the upstream side reducing agent supply channel 256. Can be communicated.
- the second rotary valve 248 has a linear flow path formed at the eccentric position of the rotor arranged at the center of the rotor of the first rotary valve 247, and is clockwise, 0 °, 45 °, 90 °. There are three rotation positions (rotation positions of A, B, and C).
- the rotational position A (FIG. 5) of the second rotary valve 248 is used in combination with the first rotational position of the first rotary valve 247, closes the reducing agent circulation channel 256, and upstream reducing agent. Only the supply passage 250 and the downstream reducing agent supply passage 251 are communicated (reducing agent addition mode).
- the rotational position B (FIG. 6) of the second rotary valve 248 is used in combination with the first rotational position of the first rotary valve 247 to close the downstream side reducing agent supply passage 251 and perform upstream reduction. Only the agent supply passage 250 and the reducing agent circulation passage 256 are communicated (reducing agent circulation mode).
- the flow path switching valve 246 can switch the flow path according to the respective rotational positions of the first rotary valve 247 and the second rotary valve 248, and the reducing agent addition mode, the reducing agent circulation There are three modes: mode and purge mode.
- FIG. 8 shows an example of a control program that the ECU 280 repeatedly executes every predetermined time when the engine is started.
- the functions of the reducing agent circulation control unit and the outside air introduction control unit are realized by this control program.
- step 1 the ECU 280 determines whether or not the urea aqueous solution stored in the reducing agent tank 230 is frozen. Specifically, the ECU 280 reads the urea aqueous solution temperature from the urea aqueous solution temperature sensor 265, and determines whether the urea aqueous solution temperature is equal to or lower than the freezing temperature of the urea aqueous solution (whether the urea aqueous solution is frozen). In this example, the freezing temperature is set to about ⁇ 11 ° C. at which the urea aqueous solution is frozen.
- a temperature sensor for measuring the temperature of the urea aqueous solution is provided in the reducing agent supply channels 250 and 251, and the temperature of the urea aqueous solution is read from the temperature sensor to determine whether or not the urea aqueous solution is frozen. Good.
- ECU 280 determines that the urea aqueous solution is frozen (Yes), the process proceeds to step 2, while if it determines that the urea aqueous solution is not frozen (No), the process proceeds to step 10. .
- step 2 the ECU 280 sets the flow path switching valve 246 to the urea water circulation mode (see FIG. 6) for a predetermined time.
- the DCU 270 outputs a control signal to an actuator that controls the flow path switching valve 246, thereby setting the flow path switching valve 246 to the reducing agent circulation mode, and reducing agent supply flow path 250 and urea.
- the water circulation channel 256 is communicated. As a result, the urea aqueous solution sucked into the reducing agent supply channel 250 from the reducing agent tank 230 is guided to the urea water circulation channel 256.
- the urea water guided to the urea water circulation channel 256 is heated by exchanging heat with a heat source such as a heat exchange plate adjacent to the urea water circulation channel 256.
- the heated urea aqueous solution is returned to the reducing agent tank 230, and the urea aqueous solution in the reducing agent tank 230 is thawed by exchanging heat with the urea aqueous solution in the reducing agent tank 230.
- step 3 the ECU 280 sets the flow path switching valve 246 to the urea water addition mode for a predetermined time.
- the DCU 270 sets the flow path switching valve 246 to the reducing agent addition mode by outputting a control signal to the actuator that controls the flow path switching valve 246.
- the urea aqueous solution sucked into the reducing agent supply channel 250 from the reducing agent tank 230 is supplied to the injection nozzle 200.
- the ECU 280 determines whether or not the urea aqueous solution stored in the reducing agent tank 230 has been thawed. Specifically, the ECU 280 reads the urea aqueous solution temperature from the urea aqueous solution temperature sensor 265, and determines whether or not the urea aqueous solution temperature exceeds the freezing temperature of the urea aqueous solution (whether or not the urea aqueous solution has thawed).
- ECU 280 determines that the urea aqueous solution has been thawed (Yes), the process proceeds to step 5, while if it determines that the urea aqueous solution is not frozen (No), the process returns to step 2.
- the urea aqueous solution thawing method in this embodiment is a method for thawing a urea aqueous solution while switching between a urea water circulation mode and a urea water addition mode. Therefore, when the urea aqueous solution is frozen at the time of starting the engine, NOx in the exhaust gas is purified in parallel with thawing the urea aqueous solution.
- the predetermined time for executing the urea water circulation mode in step 2 and the urea water addition mode in step 3 will be described.
- the long time urea water circulation mode is set.
- the urea aqueous solution is thawed, and as the urea aqueous solution is thawed, the time of the urea water circulation mode is decreased, while the time of the urea water addition mode is increased.
- the thawing status of the urea aqueous solution may be determined from the urea aqueous solution temperature sensor 265 or may be determined by estimation from the application time of the urea water circulation mode.
- step 5 the ECU 280 sets the flow path switching valve 246 to the purge mode (see FIG. 7). Specifically, the DCU 270 outputs a control signal to an actuator that controls the flow path switching valve 246, thereby setting the flow path switching valve 246 to the purge mode, and the outside air supply flow path 254 and the urea water circulation flow path. 256 is communicated. In this way, the outside air supplied from the outside air supply channel 254 is guided to the urea water circulation channel 256, and the urea aqueous solution remaining in the urea water circulation channel 256 is pushed out to the reducing agent tank 230. By introducing the outside air into the urea water circulation channel 256 for a predetermined time, the urea water circulation channel 256 becomes empty. Thereafter, even if the flow path switching valve 246 is returned to the urea water addition mode, the urea water circulation flow path 256 is kept empty. After the purge mode is executed for a predetermined time in step 5, the process proceeds to step 10.
- step 10 the ECU 280 sets the flow path switching valve 246 to the urea water addition mode (see FIG. 5). Thereafter, the ECU 280 purifies NOx in the exhaust by injecting (adding) an aqueous urea solution from the injection nozzle 200 according to the engine operating state.
- the urea aqueous solution in the reducing agent tank 230 when the urea aqueous solution in the reducing agent tank 230 is frozen at the time of starting the engine, the urea aqueous solution partially flows into the reducing agent circulation passage 256 adjacent to the heat source and is heated. The urea aqueous solution is returned to the reducing agent tank 230. Thereby, the urea aqueous solution in the reducing agent tank 230 can be thawed more quickly.
- the reducing agent supply flow path 250 is connected to the reducing agent circulation flow path 256 in the reducing agent tank 230, and a communication hole 235 with the inside of the tank is provided at this connection portion.
- a communication hole 235 Through this communication hole 235, the urea aqueous solution heated in the reducing agent circulation channel 256 and the urea aqueous solution in the reducing agent tank 230 are mixed in the reducing agent tank 230, and efficiently in a wide range of the reducing agent tank 230. Heat exchange can be performed.
- the reducing agent supply channel 250 and the reducing agent circulation channel 256 are connected in a loop shape. As a result, a small-capacity substantially closed circuit is formed and heated, so that the thawing time can be greatly shortened.
- electric heaters are provided in the reducing agent supply channels 250 and 251.
- the urea aqueous solution in the reducing agent supply flow path 250, 251 is thawed by the electric heater, and the thawed urea aqueous solution is circulated.
- the urea aqueous solution in the reducing agent tank 230 can be thawed. Therefore, in order to thaw the frozen urea aqueous solution, it is not necessary to arrange an engine cooling water pipe for flowing engine cooling water, which is a kind of antifreeze, around the reducing agent tank 230 and the circulation flow paths 250 and 251.
- the piping structure of engine cooling water can be simplified.
- the flow path switching valve 246 integrates the function of introducing the urea aqueous solution into the reducing agent circulation flow path 256 and the function of introducing outside air into the reducing agent circulation flow path 256.
- these functions include a plurality of valves, for example, a reducing agent circulation valve for controlling the urea aqueous solution to the reducing agent circulation passage and an outside air introduction valve for controlling the inflow of outside air to the reducing agent circulation passage. Can also be realized.
- the liquid reducing agent or its precursor is not limited to the urea aqueous solution, and an ammonia aqueous solution, a light oil mainly composed of hydrocarbons, or the like is used depending on the function of the exhaust purification element that purifies exhaust harmful substances. You can also.
- the freezing temperature for determining whether or not the liquid reducing agent or its precursor is frozen may be appropriately selected according to the characteristics.
Abstract
Description
尿素水溶液は約-11℃で凍結するため、特許文献1に記載されるように、エンジン停止後において、噴射ノズルや還元剤供給流路の残留尿素水溶液の凍結変化を監視するとともに、その凍結変化に伴い噴射ノズルを一時的に開くことで、残留尿素水溶液を排気管内に放出する技術が知られている。
図1は、排気中の粒子状物質(PM:Particulate Matter)及びNOxを浄化する排気浄化装置の一例を示す。
尿素選択還元触媒コンバータシステム225は、尿素水溶液から生成されるアンモニアを還元剤として使用してNOxを選択還元浄化する選択還元触媒コンバータ210、選択還元触媒コンバータ210を通過したアンモニアを酸化させる酸化触媒コンバータ220と、を有する。
図3は、図2の筐体300の上方からみた、別の還元剤循環流路256のレイアウトを示す。図3の還元剤循環流路256も、筐体300の下面、側面を構成する熱交換板を這うように配置されてもよい。
また、図4に示すように、還元剤循環流路256は、排気管180周りにらせん状に配置されてもよい。
流路切換弁246については、図5(及び図6、図7)により説明する。流路切換弁246は、第1のロータリーバルブ247と、第1のロータリーバルブ247の内側に配置される第2のロータリーバルブ248と、で構成される。第1のロータリーバルブ247及び第2のロータリーバルブ248は、アクチュエータなどの既存の方法により、DCU270により回動制御される。
第1の回動位置(図5及び図6)では、外気導入流路254を閉止し、上流側還元剤供給流路250と下流側還元剤供給流路251と還元剤循環流路256との3者を連通可能とする。
また、第2の回動位置(図7)では、下流側還元剤供給流路251を閉止し、外気導入流路254と還元剤循環流路256と上流側還元剤供給通路256との3者を連通可能とする。
第2のロータリーバルブ248の回動位置B(図6)は、第1のロータリーバルブ247の第1の回動位置と組み合わせて用いられ、下流側還元剤供給通路251を閉止し、上流側還元剤供給通路250と還元剤循環通路256のみを連通させる(還元剤循環モード)。
第2のロータリーバルブ248の回動位置C(図7)は、第1のロータリーバルブ247の第2の回動位置と組み合わせて用いられ、上流側還元剤供給通路250を閉止し、外気導入通路254と還元剤循環流路256のみを連通させる(パージモード)。
ここで、ステップ2の尿素水循環モードと、ステップ3の尿素水添加モードを実行する所定時間について説明すると、本実施形態においては、尿素水溶液が完全に凍結しているときには、長時間尿素水循環モードを持続させることで、尿素水溶液の解凍を行い、尿素水溶液が解凍されるに従い、尿素水循環モードの時間を減少させ、一方、尿素水添加モードの時間を増加させる。尿素水溶液の解凍状況は、尿素水溶液温度センサ265から判定してもよいし、又は、尿素水循環モードの適用時間から推定して判定してもよい。
110 吸気マニフォールド
120 吸気管
130 エアクリーナ
140 ターボチャージャ
142 コンプレッサ
144 タービン
150 インタークーラ
160 吸気コレクタ
170 排気マニフォールド
180 排気管
190 連続再生式DPF装置
192 DOCコンバータ
194 DPF
200 噴射ノズル
210 選択還元触媒コンバータ
220 酸化触媒コンバータ
225 尿素選択還元触媒コンバータシステム
230 還元剤タンク
235 連通孔
240 還元剤添加ユニット
242 ポンプ
244 流量制御弁
246 流路切換弁
247 第1のロータリーバルブ
248 第2のロータリーバルブ
250、251 還元剤供給流路
254 外気導入流路
256 還元剤循環流路
260 排気温度センサ
265 尿素水溶液温度センサ
270 DCU
280 ECU
290 外気温度センサ
300 筐体
Claims (5)
- エンジンの排気通路に設けられ、還元剤を使用して排気中の窒素酸化物を選択還元浄化する選択還元触媒コンバータと、
前記選択還元触媒コンバータの排気上流に液体還元剤又はその前駆体を噴射供給する噴射装置と、
前記噴射装置から噴射供給する液体還元剤又はその前駆体を貯蔵するタンクと、
前記タンクから前記噴射ノズルへ液体還元剤又はその前駆体を供給する還元剤供給流路と、
前記還元剤供給流路の途中から分岐して、液体還元剤又はその前駆体の一部を前記タンクへ戻すことができ、かつ、その一部が熱源と熱交換可能に配置される還元剤循環流路と、
前記還元剤循環流路への液体還元剤又はその前駆体の流れを制御する還元剤循環弁と、
前記タンク又は前記還元剤供給流路における液体還元剤又はその前駆体の温度を検出する温度検出部と、
前記温度検出部により検出される液体還元剤又はその前駆体の温度が所定温度以下の場合に、前記還元剤循環流路に液体還元剤又はその前駆体が流入するように前記還元剤循環弁を制御する還元剤循環制御部と、を含んで構成されるエンジン排気浄化装置。 - 前記還元剤循環流路は、前記タンク内において、前記還元剤供給流路に接続され、この接続部に前記タンク内との連通部を設けたことを特徴とする、請求項1に記載のエンジン排気浄化装置。
- エンジンから排出される排気を前記熱源として用いることを特徴とする、請求項1または請求項2に記載のエンジン排気浄化装置。
- 前記還元剤循環流路に流路内の液体還元剤又はその前駆体を前記タンクにパージするように外気を導入する外気導入流路と、
外気の導入を制御する外気導入弁と、
前記還元剤循環流路への液体還元剤又はその前駆体の流入の停止後に、前記還元剤循環流路に外気を導入するように前記外気導入弁を制御する外気導入制御部と、
を更に含んで構成される、請求項1~3のいずれか1つに記載のエンジン排気浄化装置。 - 前記外気導入流路は、前記還元剤供給流路からの前記還元剤循環流路の分岐部に接続され、前記外気導入弁と前記還元剤循環弁とが前記分岐部にて一体化されて設けられることを特徴とする、請求項4に記載のエンジン排気浄化装置。
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CN201480084292.XA CN107109981B (zh) | 2014-12-25 | 2014-12-25 | 用于发动机的排气净化装置 |
EP14909024.3A EP3249185B1 (en) | 2014-12-25 | 2014-12-25 | Exhaust purification device for engine |
PCT/JP2014/084381 WO2016103417A1 (ja) | 2014-12-25 | 2014-12-25 | エンジンの排気浄化装置 |
JP2016565772A JP6501794B2 (ja) | 2014-12-25 | 2014-12-25 | エンジンの排気浄化装置 |
US15/536,724 US10513960B2 (en) | 2014-12-25 | 2014-12-25 | Exhaust purification device for engine |
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JP6729291B2 (ja) * | 2016-10-25 | 2020-07-22 | いすゞ自動車株式会社 | 尿素水供給システム及びその制御方法 |
CN108104919A (zh) * | 2018-01-22 | 2018-06-01 | 北京福田戴姆勒汽车有限公司 | 尿素罐加热系统和车辆 |
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