WO2018008649A1 - Egr device - Google Patents

Egr device Download PDF

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Publication number
WO2018008649A1
WO2018008649A1 PCT/JP2017/024536 JP2017024536W WO2018008649A1 WO 2018008649 A1 WO2018008649 A1 WO 2018008649A1 JP 2017024536 W JP2017024536 W JP 2017024536W WO 2018008649 A1 WO2018008649 A1 WO 2018008649A1
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WO
WIPO (PCT)
Prior art keywords
cooling water
egr
flow path
egr cooler
connection circuit
Prior art date
Application number
PCT/JP2017/024536
Other languages
French (fr)
Japanese (ja)
Inventor
岩崎　充
Original Assignee
カルソニックカンセイ株式会社
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Publication date
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Publication of WO2018008649A1 publication Critical patent/WO2018008649A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P3/00—Liquid cooling
    • F01P3/18—Arrangements or mounting of liquid-to-air heat-exchangers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P7/00—Controlling of coolant flow
    • F01P7/14—Controlling of coolant flow the coolant being liquid
    • F01P7/16—Controlling of coolant flow the coolant being liquid by thermostatic control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/02—EGR systems specially adapted for supercharged engines
    • F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
    • F02M26/05—High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/22—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with coolers in the recirculation passage
    • F02M26/23—Layout, e.g. schematics
    • F02M26/28—Layout, e.g. schematics with liquid-cooled heat exchangers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/50—Arrangements or methods for preventing or reducing deposits, corrosion or wear caused by impurities

Definitions

  • the present invention relates to an EGR (Exhaust Gas Recirculation) device.
  • JP2010-048113A when high-temperature gas is flowing, water is injected into the EGR cooler to evaporate it, and soot adhering to the surface of the tube is washed away with water vapor to reduce heat exchange efficiency due to soot deposition.
  • An EGR device for preventing the above is disclosed.
  • the object of the present invention is to provide an EGR device capable of washing away the soot adhering to the surface of the tube and preventing a decrease in heat exchange efficiency.
  • An EGR device is an EGR device that recirculates a part of exhaust gas discharged from an engine from an exhaust passage to an intake passage, and is guided from the exhaust passage by cooling water flowing through the inside.
  • An EGR cooler that cools the exhaust gas, and the EGR cooler includes a first connection circuit connected to a first cooling water flow path through which cooling water for cooling the engine flows, and cooling that flows through the first cooling water flow path
  • a second connection circuit connected to a second cooling water flow path through which cooling water having a temperature lower than that of water circulates, and a switching valve for switching connection between the first connection circuit and the second connection circuit, The switching valve switches the connection from the first connection circuit to the second connection circuit when the temperature of the exhaust gas that has passed through the EGR cooler is equal to or higher than a predetermined temperature.
  • the exhaust gas guided to the EGR cooler can be cooled using the cooling water having a temperature lower than that of the cooling water.
  • the cooling performance of the cooler can be kept high.
  • the exhaust gas is cooled near the surface of the tube below the dew point by the cooling water having a lower temperature than the cooling water for cooling the engine, so that the condensed water is formed between the surface of the tube and the adhering soot. A water film is formed.
  • the soot attached to the surface of the tube can be washed away by the momentum of the exhaust gas flowing in the EGR cooler. Therefore, it is possible to suppress the soot that hinders the heat exchange between the cooling water and the exhaust gas from adhering to the surface of the tube, thereby preventing the heat exchange efficiency from being lowered.
  • FIG. 1 is a configuration diagram of an intake / exhaust system of an engine of a diesel vehicle including an EGR device according to an embodiment of the present invention.
  • FIG. 2 is an internal cross-sectional view of the EGR cooler.
  • FIG. 3 is a configuration diagram illustrating the cooling water flow path.
  • FIG. 4 is a diagram illustrating a connection state between the cooling water passage and the EGR cooler when the cooling water in the first cooling water passage flows through the EGR cooler.
  • FIG. 5 is a diagram illustrating a connection state between the cooling water flow path and the EGR cooler when the cooling water in the second cooling water flow path flows through the EGR cooler.
  • FIG. 6 is a flowchart showing a flow of cooling water flow path switching control.
  • FIG. 7A is a schematic diagram illustrating a state of wrinkles attached to the tube.
  • Drawing 7B is a mimetic diagram explaining the condensed water generated between a tube and a bowl.
  • FIG. 7C is a schematic diagram for explaining a state in which wrinkles are washed away from the tube.
  • FIG. 8 is a configuration diagram illustrating a cooling water passage according to a modification.
  • FIG. 9 is a diagram illustrating a connection state between the cooling water flow path and the EGR cooler when the cooling water in the first cooling water flow path of the modified example flows through the EGR cooler.
  • FIG. 10 is a diagram illustrating a connection state between the cooling water flow path and the EGR cooler when the cooling water in the second cooling water flow path of the modified example flows through the EGR cooler.
  • FIG. 1 is a configuration diagram of an intake / exhaust system of an engine 20 of a diesel vehicle including an EGR device 100 according to an embodiment of the present invention.
  • the supply / exhaust system of the engine 20 includes an intake system 10 connected upstream of the engine 20 and an exhaust system 30 connected downstream.
  • the intake system 10 includes an air cleaner 11, a compressor wheel 42 of the supercharger 40, an intake shutter valve 14, an intercooler 12, and an intake passage that connects these components so that intake air taken from outside can flow. 13.
  • the exhaust system 30 includes a turbine wheel 41 of the supercharger 40, an exhaust purification device 31, a silencer 32, and an exhaust passage 33 that connects them so that exhaust gas discharged from the engine 20 can flow. Consists of
  • the intake air is supercharged by the compressor wheel 42 of the supercharger 40 after foreign matter such as dust and dirt is removed by the air cleaner 11 when flowing through the intake flow path 13, and is introduced to the intake shutter valve 14. It is burned.
  • the supercharged intake air changes its flow rate according to the opening degree of the intake shutter valve 14, passes through the intake shutter valve 14, is cooled by the intercooler 12, and then passes through the intake manifold (not shown) to the engine 20.
  • the intercooler 12 is a water-cooled type in which cooling water circulates, and is connected to a sub-radiator 83 (see FIG. 3) to release heat taken from supercharged intake air to the outside.
  • the intake air guided to the engine 20 is supplied to the combustion chamber 22 through the intake port 21 and is combusted by being compressed together with the fuel injected in the combustion chamber 22.
  • the combustion provides the driving force necessary for the diesel vehicle to travel.
  • the exhaust gas generated by the combustion is discharged from the exhaust port 23 to the exhaust passage 33 through the exhaust manifold (not shown) of the exhaust system 30.
  • the exhaust gas passes through the turbine wheel 41 of the supercharger 40 and is purified by a diesel oxidation catalyst (not shown) or a particulate collection filter in the exhaust purification device 31 and then flows to the silencer 32.
  • the exhaust gas flowing through the silencer 32 is discharged to the outside with reduced pressure and temperature and reduced exhaust noise.
  • the diesel oxidation catalyst of the exhaust purification device 31 is a catalyst that activates and burns unburned gas in the exhaust gas
  • the particulate collection filter is a filter that collects particulates in the exhaust gas. Note that NOx in the exhaust gas is attached to the exhaust purification device 31 by attaching a NOx reduction catalyst for removing nitrogen oxides and a fuel reforming catalyst that generates a reducing agent used in the NOx reduction catalyst. May be reduced.
  • the supercharger 40 for example, a variable capacity turbocharger that controls the flow rate of exhaust gas or intake air according to the rotational speed of the engine 20 is used.
  • the turbine wheel 41 of the supercharger 40 When the turbine wheel 41 of the supercharger 40 is rotated by the pressure of the exhaust gas, the rotational force is transmitted to the compressor wheel 42 via the shaft 43 and the intake air is supercharged. A large amount of intake air can be introduced.
  • the EGR device 100 is connected between the exhaust flow path 33 and the intake flow path 13.
  • the EGR device 100 includes an EGR cooler 50, an EGR valve 51, and an EGR gas channel 52 that connects the exhaust gas recirculated from the exhaust channel 33 so that the exhaust gas can flow.
  • EGR device 100 executes EGR, NOx reduction and fuel efficiency improvement can be realized. Further, since the EGR device 100 reduces exhaust gas upstream from the turbine wheel 41 and the exhaust purification device 31, it reduces the amount of soot and the like adhering to the turbine wheel 41 and the exhaust purification device 31 and improves durability. Can do.
  • the EGR gas flow path 52 includes an EGR inlet side pipe 52a and an EGR outlet side pipe 52b.
  • the EGR inlet side pipe 52 a connects the exhaust flow path 33 and the EGR cooler 50.
  • the EGR outlet side pipe 52 b connects the EGR cooler 50 and the intake passage 13.
  • the EGR inlet side pipe 52a is formed shorter than the EGR outlet side pipe 52b.
  • the EGR valve 51 is provided in the EGR outlet side pipe 52b and adjusts the flow rate of the exhaust gas recirculated to the intake passage 13 according to the opening degree. For example, when the EGR valve 51 is closed, the exhaust gas is not recirculated to the intake flow path 13. After that, when the EGR valve 51 is opened, the flow of the exhaust gas is switched, and the opening degree of the EGR valve 51 is changed. In response to this, the air is recirculated to the intake passage 13.
  • the EGR cooler 50 cools the exhaust gas guided from the exhaust passage 33 by the cooling water flowing through the inside.
  • the EGR cooler 50 is connected so that cooling water can circulate between the cooling water channel 60 described later (see FIG. 3).
  • FIG. 2 is an internal cross-sectional view of the EGR cooler 50.
  • the EGR cooler 50 performs heat exchange between the EGR gas passage 53 through which the exhaust gas guided to the EGR gas passage 52 circulates and the exhaust gas in the EGR gas passage 53. And a plurality of tubes 54 through which the cooling water flows.
  • the EGR gas passage 53 is formed between the tube 54 and another adjacent tube 54 by alternately stacking a plurality of tubes 54 at intervals. Fins (not shown) are arranged in the EGR gas passage 53 in order to increase the efficiency of heat exchange with the exhaust gas.
  • the EGR gas passage 53 has one end connected to the EGR inlet side pipe 52a of the EGR gas flow path 52 and the other end connected to the EGR outlet side pipe 52b.
  • the exhaust gas guided to the EGR gas channel 52 flows through the EGR gas passage 53 through the EGR inlet side piping 52a as indicated by an arrow A in FIG.
  • the EGR valve 51 When the EGR valve 51 is open, the exhaust gas flowing through the EGR gas passage 53 is returned to the intake passage 13 through the EGR outlet side pipe 52b as indicated by an arrow B in FIG.
  • the EGR valve 51 when the EGR valve 51 is closed, the exhaust gas naturally convects around the EGR gas passage 53 and the EGR inlet side piping 52a.
  • the cooling water flows into the plurality of tubes 54 from the cooling water channel inlet 55 as indicated by an arrow C in FIG.
  • the cooling water exchanges heat with the exhaust gas passing through the adjacent EGR gas passage 53 via the tube 54, and then, as shown by an arrow D in FIG. 56 flows out.
  • an EGR cooler outlet gas temperature sensor 71 is attached in the vicinity of the connection portion connected to the EGR gas passage 53 of the EGR outlet side pipe 52b.
  • the EGR cooler outlet gas temperature sensor 71 detects the temperature of the exhaust gas near the outlet of the EGR cooler 50 as the EGR cooler outlet gas temperature Tg.
  • the EGR cooler outlet gas temperature sensor 71 may be installed at the outlet portion of the EGR gas passage 53.
  • an EGR outlet water temperature sensor 72 that detects the outlet temperature of the cooling water of the EGR cooler 50 may be attached to the cooling water passage outlet 56.
  • FIG. 3 is a configuration diagram illustrating the cooling water channel 60.
  • FIG. 4 is a diagram illustrating a connection state between the cooling water passage 60 and the EGR cooler 50 when the cooling water in the first cooling water passage 61 flows through the EGR cooler 50.
  • FIG. 5 is a diagram for explaining a connection state between the cooling water passage 60 and the EGR cooler 50 when the cooling water in the second cooling water passage 62 flows through the EGR cooler 50.
  • the cooling water flow path 60 includes a first cooling water flow path 61 through which cooling water for cooling the engine 20 circulates, a second cooling water flow path 62 through which cooling water for cooling the intercooler 12 circulates, Consists of
  • the first cooling water flow path 61 is configured so that cooling water can circulate in order through the engine 20, the radiator 80, and the water pump 81.
  • the water pump 81 circulates the cooling water through the first cooling water channel 61 by sending the cooling water to the engine 20.
  • the radiator 80 releases the heat of the cooling water heated by cooling the engine 20 to the outside.
  • An opening / closing valve 59 d is provided between the water pump 81 in the first cooling water passage 61 and the engine 20.
  • the second cooling water flow path 62 is configured so that the cooling water can circulate through the intercooler 12, the water pump 82, and the sub radiator 83 in order.
  • the water pump 82 circulates the cooling water through the second cooling water channel 62 by sending the cooling water to the sub-radiator 83.
  • the sub radiator 83 discharges the heat of the cooling water heated by cooling the intercooler 12 to the outside.
  • a second cooling water flow path side three-way valve 59 c is provided between the sub radiator 83 of the second cooling water flow path 62 and the intercooler 12.
  • the EGR cooler 50 includes a first connection circuit 57 connected to the first cooling water flow path 61 and a second connection circuit 58 connected to the second cooling water flow path 62.
  • the first connection circuit 57 includes an inlet-side first connection circuit 57a connected to the coolant passage inlet 55 of the EGR cooler 50, and an outlet-side first connection circuit 57b connected to the coolant passage outlet 56 of the EGR cooler 50. Is composed of.
  • An inlet-side three-way valve 59a is provided between the cooling water channel inlet 55 and the inlet-side first connection circuit 57a.
  • An outlet-side three-way valve 59b is provided between the cooling water passage outlet 56 and the outlet-side first connection circuit 57b.
  • the second connection circuit 58 includes an inlet-side second connection circuit 58a connected to the coolant passage inlet 55 of the EGR cooler 50 via the inlet-side three-way valve 59a, and cooling of the EGR cooler 50 via the outlet-side three-way valve 59b. And an outlet-side second connection circuit 58 b connected to the water flow path outlet 56.
  • the inlet side three-way valve 59a has a flow of cooling water flowing from the inlet side first connection circuit 57a into the cooling water flow path inlet 55 as shown by a thick solid line in FIG. It can switch so that it may flow in from the 2 connection circuit 58a.
  • outlet side three-way valve 59b is configured so that the flow of the cooling water flowing out from the cooling water passage outlet 56 to the outlet side first connection circuit 57b as shown by a thick solid line in FIG. It can switch so that it may flow out to the 2nd side connection circuit 58b.
  • the inlet-side three-way valve 59a and the outlet-side three-way valve 59b switch the connection between the first connection circuit 57 and the second connection circuit 58 in accordance with an output signal from the controller 70 described later.
  • the controller 70 is configured by a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and by reading a program stored in the ROM by the CPU, the controller 20 and the EGR device 100 Demonstrate various functions.
  • a CPU Central Processing Unit
  • ROM Read Only Memory
  • RAM Random Access Memory
  • the controller 70 receives a signal from the EGR cooler outlet gas temperature sensor 71 in order to cause the EGR apparatus 100 to perform various functions, for example.
  • the controller 70 may be input with signals such as an EGR outlet water temperature sensor 72, an engine rotation sensor (not shown) that detects the rotation speed of the engine 20, or an accelerator opening detection sensor (not shown) that detects the accelerator opening. .
  • the controller 70 executes control of the EGR device 100 based on the input signal. That is, the controller 70 performs opening / closing control of the intake shutter valve 14 and the EGR valve 51 as shown by broken lines in FIG. 1 according to the load of the engine 20 and the like, and as shown by broken lines in FIGS. 3 to 5.
  • the switching control of the inlet side three-way valve 59a, the outlet side three-way valve 59b, and the second cooling water flow path side three-way valve 59c and the opening / closing control of the opening / closing valve 59d are executed.
  • FIG. 6 is a flowchart showing a flow of cooling water flow path switching control.
  • FIG. 7A is a schematic diagram for explaining the state of the ridge C attached to the tube 54.
  • FIG. 7B is a schematic diagram for explaining the condensed water W generated between the tube 54 and the bowl C.
  • FIG. 7C is a schematic diagram for explaining a state in which the eyelid C is washed away from the tube 54.
  • the controller 70 executes the cooling water flow path switching control at predetermined intervals after the EGR is started and the EGR valve 51 is opened.
  • EGR exhaust gas passes through the EGR gas passage 53 vigorously.
  • the cooling water in the first cooling water passage 61 flows to the EGR cooler 50 as shown in FIG. As shown in FIG. 7A, soot C is deposited and deposited on the surface of the tube 54 of the EGR cooler 50 as the diesel vehicle travels.
  • step S101 the controller 70 determines whether or not the EGR cooler outlet gas temperature Tg is equal to or higher than a predetermined gas temperature T.
  • the processing of the controller 70 proceeds to step S102 when the EGR cooler outlet gas temperature Tg is equal to or higher than the predetermined gas temperature T, and proceeds to step S103 when it is lower than the predetermined gas temperature T.
  • the predetermined gas temperature T is a high temperature without cooling the exhaust gas as a result of the fact that soot C is deposited on the surface of the tube 54 of the EGR cooler 50 and heat exchange between the exhaust gas and the cooling water cannot be performed efficiently. For example, 180 ° C.
  • step S102 the controller 70 executes second cooling water flow path connection control.
  • the controller 70 controls the inlet side three-way valve 59a so that the cooling water flow path inlet 55 of the EGR cooler 50 is connected to the second cooling water flow path 62 as shown by a thick solid line in FIG. Switch connection.
  • the controller 70 also includes the outlet side three-way valve 59b and the second cooling water channel side so that the cooling water channel outlet 56, the outlet side second connection circuit 58b, and the second cooling water channel 62 of the EGR cooler 50 are connected in series.
  • the connection of the three-way valve 59c is switched.
  • the controller 70 opens the open / close valve 59 d of the first cooling water flow path 61.
  • the controller 70 executes the switching control of the inlet side three-way valve 59a, the outlet side three-way valve 59b, and the second cooling water flow path side three-way valve 59c and the opening / closing control of the opening / closing valve 59d.
  • the cooling water circulating through the second cooling water flow path 62 flows to the EGR cooler 50. Since the cooling water having a lower temperature than the cooling water for cooling the engine 20 flows through the EGR cooler 50, the exhaust gas passing through the EGR cooler 50 exchanges heat with the cooling water having a lower temperature. To cool.
  • the temperature of the cooling water in the second cooling water passage 62 is set to be equal to or lower than the dew point temperature at which the exhaust gas is condensed, and is set to, for example, around 50 ° C.
  • the exhaust gas passing through the EGR cooler 50 is cooled to a dew point or lower by cooling water having a low temperature, condensed water W is generated between the tube 54 and the soot C as shown in FIG. 7B.
  • Condensate water W is a condensate of water vapor contained in the exhaust gas as the exhaust gas that has entered the interior of the soot C through the fine gaps on the soot C surface is cooled near the surface of the tube 54.
  • the condensed water W is also generated when the exhaust gas preliminarily present in the soot C deposited near the surface of the tube 54 is cooled and the water vapor in the exhaust gas is condensed.
  • ⁇ C is an oily (hydrophobic) property in which hydrocarbons left unburned in the combustion process are aggregated and solidified through various chemical reactions. Therefore, the generated condensed water W forms a water film layer by spreading between the tube 54 and the ridge C without being absorbed by the hydrophobic ridge C. As a result, the bag C is forcibly separated from the surface of the tube 54 by the water film.
  • exhaust gas passes through the EGR gas passage 53 vigorously, so that the soot C separated from the surface of the tube 54 is downstream with the condensed water W by the exhaust gas as shown in FIG. 7C. Blown away.
  • the condensed water W blown off is heated by the surrounding exhaust gas and evaporated when blown off, so that it does not flow into the engine 20 as a liquid.
  • step S103 the controller 70 executes the first coolant flow path connection control.
  • the controller 70 controls the inlet side three-way valve 59a so that the cooling water flow channel inlet 55 of the EGR cooler 50 is connected to the first cooling water flow channel 61 as shown by a thick solid line in FIG. Switch connection.
  • the controller 70 also includes the outlet side three-way valve 59b and the second cooling water channel side so that the cooling water channel outlet 56, the outlet side first connection circuit 57b, and the second cooling water channel 62 of the EGR cooler 50 are connected in series.
  • the connection of the three-way valve 59c is switched.
  • the controller 70 closes the on-off valve 59d of the first cooling water channel 61.
  • the controller 70 executes the switching control of the inlet side three-way valve 59a, the outlet side three-way valve 59b, and the second cooling water flow path side three-way valve 59c, and the opening / closing control of the opening / closing valve 59d.
  • the cooling water circulating in the first cooling water flow path 61 flows to the EGR cooler 50. Therefore, when the exhaust gas is not cooled below the dew point by the cooling water that cools the engine 20, the water vapor contained in the exhaust gas passes through the EGR gas passage 53 of the EGR cooler 50 without being condensed. .
  • the EGR device 100 that recirculates a part of the exhaust gas discharged from the engine 20 from the exhaust flow path 33 to the intake flow path 13 cools the exhaust gas guided from the exhaust flow path 33 by the cooling water flowing inside.
  • a cooler 50 is provided.
  • the EGR cooler 50 circulates a first connection circuit 57 connected to a first cooling water passage 61 through which cooling water for cooling the engine 20 flows, and cooling water having a temperature lower than that of the cooling water flowing through the first cooling water passage 61.
  • the EGR cooler outlet gas temperature Tg which is the temperature of the exhaust gas that has passed through the EGR cooler 50, is equal to or higher than the predetermined gas temperature T. In this case, the connection is switched from the first connection circuit 57 to the second connection circuit 58.
  • the exhaust gas led to the EGR cooler 50 is cooled using the cooling water having a temperature lower than that of the cooling water.
  • the cooling performance of the EGR cooler 50 can be kept high.
  • the exhaust gas is cooled near the surface of the tube 54 by the cooling water having a lower temperature than that of the cooling water for cooling the engine 20 until the dew point is lowered between the surface of the tube 54 and the attached soot C.
  • a water film is formed by the condensed water W.
  • the soot C attached to the surface of the tube 54 can be washed away by the momentum of the exhaust gas flowing in the EGR cooler 50. Accordingly, it is possible to suppress the stick C, which hinders heat exchange between the cooling water and the exhaust gas, from adhering to the surface of the tube 54, thereby preventing a decrease in heat exchange efficiency.
  • the EGR cooler 50 can be used even when traveling continuously for a long time. Cooling performance can be kept high.
  • the second cooling water flow path 62 includes a sub-radiator 83 that releases heat of the cooling water to the outside, and an intercooler 12 that serves as a heat exchanger that cools other equipment different from the EGR cooler 50. Connected.
  • the EGR cooler outlet gas temperature Tg is equal to or higher than the predetermined gas temperature T
  • the second connection circuit 58 allows the intercooler 12 as a heat exchanger after the cooling water in the second cooling water passage 62 flows through the sub radiator 83. Is connected in series between the sub-radiator 83 and the intercooler 12 so as to circulate through the second connection circuit 58 before circulating.
  • the EGR cooler 50 can be cooled efficiently. Since the EGR cooler 50 is usually set to have a smaller heat capacity than the intercooler 12, the cooling water can sufficiently cool the intercooler 12 even after the EGR cooler 50 is cooled.
  • cooling water circulating through the second cooling water flow path 62 is not limited to the intercooler 12 and may cool various devices that generate heat of the diesel vehicle.
  • the intercooler 12 is installed in the intake passage 13. Therefore, since another second cooling water flow path 62 near the engine 20 can be used, the second connection circuit 58 of the EGR cooler 50 can be shortened.
  • the number of three-way valves and on-off valves may be changed from that of the above embodiment, and the cooling water channel inlet 255 and the cooling water channel outlet 256 of the EGR cooler 250 may be configured as shown in FIG.
  • the cooling water channel inlet 255 is composed of a first cooling water channel inlet 255a and a second cooling water channel inlet 255b.
  • the first coolant passage inlet 255a is connected to the inlet-side first connection circuit 57a via the on-off valve 259a
  • the second coolant passage inlet 255b is connected to the second coolant passage 62 via the three-way valve 259e.
  • the cooling water channel outlet 256 is composed of a first cooling water channel outlet 256a and a second cooling water channel outlet 256b.
  • the first cooling water channel outlet 256a is connected to the outlet side first connection circuit 57b via the on-off valve 259b, and the second cooling water channel outlet 256b is connected to the second cooling water channel 62 via the second cooling water channel side three-way valve 59c. Connected to.
  • connection state between the cooling water passage 60 and the EGR cooler 250 is as shown by a thick solid line in FIG.
  • the connection state between the cooling water flow path 60 and the EGR cooler 250 is as shown by a thick solid line in FIG.
  • the cooling water flow path switching control can also be executed in the same manner as in the above embodiment by configuring the EGR cooler 250 by replacing a part of the three-way valve in the above embodiment with an on-off valve.
  • the controller 70 is not limited to the case where the EGR cooler outlet gas temperature Tg is equal to or higher than the predetermined gas temperature T as in the above-described embodiment.
  • the soot C adhering to the surface of the tube 54 of the EGR cooler 50 can be washed away by executing the 2 cooling water flow path connection control. Therefore, when traveling with a high load or the like is scheduled, it is possible to start the traveling or the like while keeping the cooling performance of the EGR cooler 50 high in advance, so that the temperature of the exhaust gas rises excessively. Can be suppressed.
  • the EGR device 100 is not limited to the aspect of the above embodiment, and may be installed so as to connect between the compressor wheel 42 of the intake passage 13 and the downstream side of the exhaust purification device 31 of the exhaust passage 33. Good. As a result, the same effect as in the above embodiment can be obtained.
  • the present invention is not limited to diesel vehicles, and may be applied to gasoline vehicles.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust-Gas Circulating Devices (AREA)

Abstract

An EGR device (100) equipped with an EGR cooler (50), said EGR cooler being equipped with: a first connection circuit (57) connected to a first cooling water flow path (61) in which cooling water that cools an engine (20) flows; a second connection circuit (58) connected to a second cooling water flow path (62) in which cooling water at a lower temperature than the cooling water flowing in the first cooling water flow path (61) circulates; and an inlet-side three-way valve (59a), an outlet-side three-way valve (59b), a second cooling water flow-path-side three-way valve (59c), and an on-off valve (59d), which serve as switch valves for switching the connection of the first connection circuit (57) and the second connection circuit (58). When the EGR cooler outlet gas temperature Tg is equal to or greater than a prescribed gas temperature T, the inlet-side three-way valve (59a), the outlet-side three-way valve (59b), the second cooling water flow-path-side three-way valve (59c), and the on-off valve (59d) switch the connection from the first connection circuit (57) to the second connection circuit (58).

Description

ＥＧＲ装置EGR device
　本発明は、ＥＧＲ（Ｅｘｈａｕｓｔ　Ｇａｓ　Ｒｅｃｉｒｃｕｌａｔｉｏｎ：排気再循環）装置に関する。 The present invention relates to an EGR (Exhaust Gas Recirculation) device.
　ＪＰ２０１０－０４８１１３Ａには、高温のガスが流れているときにＥＧＲクーラの入口に水を噴射して蒸発させ、チューブの表面に付着した煤を水蒸気で洗い流すことによって、煤堆積による熱交換効率の低下を防止するＥＧＲ装置が開示されている。 In JP2010-048113A, when high-temperature gas is flowing, water is injected into the EGR cooler to evaporate it, and soot adhering to the surface of the tube is washed away with water vapor to reduce heat exchange efficiency due to soot deposition. An EGR device for preventing the above is disclosed.
　しかしながら、ＪＰ２０１０－０４８１１３ＡのＥＧＲ装置では、水蒸気はガスとともにＥＧＲクーラのチューブ内を流れるので、付着した煤は表面側から洗浄される。そのため、煤表面のごく一部しか洗い流すことができず、チューブに付着した煤の多くが堆積してそのまま留まり、強いては堆積した煤がチューブの内壁に固着する可能性があり、熱交換効率が低下するおそれがある。 However, in the EGR device of JP2010-048113A, water vapor flows in the tube of the EGR cooler together with the gas, so that the attached soot is washed from the surface side. As a result, only a small part of the surface of the soot can be washed away, and most of the soot that adheres to the tube accumulates and remains as it is, and the accumulated soot may stick to the inner wall of the tube, which improves the heat exchange efficiency. May decrease.
　本発明は、チューブの表面に付着した煤を洗い流すことができ、熱交換効率の低下を防止できるＥＧＲ装置を提供することを目的とする。 The object of the present invention is to provide an EGR device capable of washing away the soot adhering to the surface of the tube and preventing a decrease in heat exchange efficiency.
　本発明のある態様によるＥＧＲ装置は、エンジンから排出された排気ガスの一部を排気流路から吸気流路に還流させるＥＧＲ装置であって、内部を流通する冷却水によって前記排気流路から導かれた排気ガスを冷却するＥＧＲクーラを備え、前記ＥＧＲクーラは、前記エンジンを冷却する冷却水が流れる第１冷却水流路に接続される第１接続回路と、前記第１冷却水流路を流れる冷却水よりも温度の低い冷却水が循環する第２冷却水流路に接続される第２接続回路と、前記第１接続回路と前記第２接続回路との接続を切り替える切替弁と、を備え、前記切替弁は、前記ＥＧＲクーラを通過した排気ガスの温度が所定温度以上である場合に前記第１接続回路から前記第２接続回路に接続を切り替える。 An EGR device according to an aspect of the present invention is an EGR device that recirculates a part of exhaust gas discharged from an engine from an exhaust passage to an intake passage, and is guided from the exhaust passage by cooling water flowing through the inside. An EGR cooler that cools the exhaust gas, and the EGR cooler includes a first connection circuit connected to a first cooling water flow path through which cooling water for cooling the engine flows, and cooling that flows through the first cooling water flow path A second connection circuit connected to a second cooling water flow path through which cooling water having a temperature lower than that of water circulates, and a switching valve for switching connection between the first connection circuit and the second connection circuit, The switching valve switches the connection from the first connection circuit to the second connection circuit when the temperature of the exhaust gas that has passed through the EGR cooler is equal to or higher than a predetermined temperature.
　上記態様によれば、エンジンを冷却する冷却水の温度が高くなった場合でも、当該冷却水よりも温度の低い冷却水を用いてＥＧＲクーラに導かれた排気ガスを冷却することができ、ＥＧＲクーラの冷却性能を高く保つことができる。また、エンジンを冷却する冷却水と比較して温度の低い冷却水によって排気ガスがチューブの表面付近で露点を下回るまで冷却されることで、チューブの表面と付着した煤との間に凝縮水による水膜が形成される。その結果、水膜によってチューブと煤とが分離された状態になっているので、ＥＧＲクーラ内を流れる排気ガスの勢いによってチューブの表面に付着した煤を洗い流すことができる。したがって、冷却水と排気ガスとの間の熱交換を妨げる煤がチューブの表面で固着することも抑制でき、熱交換効率の低下を防止することができる。 According to the above aspect, even when the temperature of the cooling water for cooling the engine becomes high, the exhaust gas guided to the EGR cooler can be cooled using the cooling water having a temperature lower than that of the cooling water. The cooling performance of the cooler can be kept high. Moreover, the exhaust gas is cooled near the surface of the tube below the dew point by the cooling water having a lower temperature than the cooling water for cooling the engine, so that the condensed water is formed between the surface of the tube and the adhering soot. A water film is formed. As a result, since the tube and the soot are separated by the water film, the soot attached to the surface of the tube can be washed away by the momentum of the exhaust gas flowing in the EGR cooler. Therefore, it is possible to suppress the soot that hinders the heat exchange between the cooling water and the exhaust gas from adhering to the surface of the tube, thereby preventing the heat exchange efficiency from being lowered.
図１は、本発明の実施形態に係るＥＧＲ装置を備えるディーゼル車両のエンジンの吸排気系の構成図である。FIG. 1 is a configuration diagram of an intake / exhaust system of an engine of a diesel vehicle including an EGR device according to an embodiment of the present invention. 図２は、ＥＧＲクーラの内部断面図である。FIG. 2 is an internal cross-sectional view of the EGR cooler. 図３は、冷却水流路を説明する構成図である。FIG. 3 is a configuration diagram illustrating the cooling water flow path. 図４は、第１冷却水流路の冷却水がＥＧＲクーラに流通するときの冷却水流路とＥＧＲクーラとの接続状態を説明する図である。FIG. 4 is a diagram illustrating a connection state between the cooling water passage and the EGR cooler when the cooling water in the first cooling water passage flows through the EGR cooler. 図５は、第２冷却水流路の冷却水がＥＧＲクーラに流通するときの冷却水流路とＥＧＲクーラとの接続状態を説明する図である。FIG. 5 is a diagram illustrating a connection state between the cooling water flow path and the EGR cooler when the cooling water in the second cooling water flow path flows through the EGR cooler. 図６は、冷却水流路切替制御の流れを示すフローチャートである。FIG. 6 is a flowchart showing a flow of cooling water flow path switching control. 図７Ａは、チューブに付着した煤の状態を説明する模式図である。FIG. 7A is a schematic diagram illustrating a state of wrinkles attached to the tube. 図７Ｂは、チューブと煤との間に生成される凝縮水を説明する模式図である。Drawing 7B is a mimetic diagram explaining the condensed water generated between a tube and a bowl. 図７Ｃは、チューブから煤が洗い流される状態を説明する模式図である。FIG. 7C is a schematic diagram for explaining a state in which wrinkles are washed away from the tube. 図８は、変形例の冷却水流路を説明する構成図である。FIG. 8 is a configuration diagram illustrating a cooling water passage according to a modification. 図９は、変形例の第１冷却水流路の冷却水がＥＧＲクーラに流通するときの冷却水流路とＥＧＲクーラとの接続状態を説明する図である。FIG. 9 is a diagram illustrating a connection state between the cooling water flow path and the EGR cooler when the cooling water in the first cooling water flow path of the modified example flows through the EGR cooler. 図１０は、変形例の第２冷却水流路の冷却水がＥＧＲクーラに流通するときの冷却水流路とＥＧＲクーラとの接続状態を説明する図である。FIG. 10 is a diagram illustrating a connection state between the cooling water flow path and the EGR cooler when the cooling water in the second cooling water flow path of the modified example flows through the EGR cooler.
　以下、図面を参照して、本発明の実施形態について説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
　図１は本発明の実施形態に係るＥＧＲ装置１００を備えるディーゼル車両のエンジン２０の吸排気系の構成図である。 FIG. 1 is a configuration diagram of an intake / exhaust system of an engine 20 of a diesel vehicle including an EGR device 100 according to an embodiment of the present invention.
　エンジン２０の給排気系は、エンジン２０の上流に接続される吸気系１０と、下流に接続される排気系３０と、を備える。 The supply / exhaust system of the engine 20 includes an intake system 10 connected upstream of the engine 20 and an exhaust system 30 connected downstream.
　吸気系１０は、エアクリーナ１１と、過給機４０のコンプレッサホイール４２と、吸気シャッターバルブ１４と、インタークーラ１２と、これらを外部から吸入した吸入空気が流通可能となるように接続する吸気流路１３と、から構成される。 The intake system 10 includes an air cleaner 11, a compressor wheel 42 of the supercharger 40, an intake shutter valve 14, an intercooler 12, and an intake passage that connects these components so that intake air taken from outside can flow. 13.
　排気系３０は、過給機４０のタービンホイール４１と、排気浄化装置３１と、サイレンサ３２と、これらをエンジン２０から排出された排気ガスが流通可能となるように接続する排気流路３３と、から構成される。 The exhaust system 30 includes a turbine wheel 41 of the supercharger 40, an exhaust purification device 31, a silencer 32, and an exhaust passage 33 that connects them so that exhaust gas discharged from the engine 20 can flow. Consists of
　吸入空気は、吸気流路１３を流通する際に、エアクリーナ１１によってごみやほこり等の異物が取り除かれた後に、過給機４０のコンプレッサホイール４２によって過給されて、吸気シャッターバルブ１４へと導かれる。過給された吸入空気は、吸気シャッターバルブ１４の開度に応じて流量を変化させて吸気シャッターバルブ１４を通過して、インタークーラ１２で冷却された後に、図示しないインテークマニホールドを通ってエンジン２０へ導かれる。インタークーラ１２は、後述するように冷却水が循環する水冷式でありサブラジエータ８３（図３参照）に接続されることで、過給された吸入空気から取り込んだ熱を外部に放出する。 The intake air is supercharged by the compressor wheel 42 of the supercharger 40 after foreign matter such as dust and dirt is removed by the air cleaner 11 when flowing through the intake flow path 13, and is introduced to the intake shutter valve 14. It is burned. The supercharged intake air changes its flow rate according to the opening degree of the intake shutter valve 14, passes through the intake shutter valve 14, is cooled by the intercooler 12, and then passes through the intake manifold (not shown) to the engine 20. Led to. As will be described later, the intercooler 12 is a water-cooled type in which cooling water circulates, and is connected to a sub-radiator 83 (see FIG. 3) to release heat taken from supercharged intake air to the outside.
　エンジン２０に導かれた吸入空気は、吸入ポート２１を通って燃焼室２２に供給され、燃焼室２２内で噴射された燃料とともに圧縮されることで燃焼する。当該燃焼によって、ディーゼル車両が走行するために必要な推進力が得られる。 The intake air guided to the engine 20 is supplied to the combustion chamber 22 through the intake port 21 and is combusted by being compressed together with the fuel injected in the combustion chamber 22. The combustion provides the driving force necessary for the diesel vehicle to travel.
　燃焼により生成された排気ガスは、排気ポート２３から排気系３０の図示しないエキゾーストマニホールドを通って排気流路３３へと排出される。排気ガスは、過給機４０のタービンホイール４１を通過してから排気浄化装置３１内の図示しないディーゼル酸化触媒や微粒子捕集フィルタによって浄化された後に、サイレンサ３２へと流通する。サイレンサ３２へ流通した排気ガスは、圧力や温度が低減されるとともに排気騒音が低減されて外部に排出される。排気浄化装置３１のディーゼル酸化触媒は、排気ガス中の未燃焼ガスを活性化させ燃焼させる触媒であり、微粒子捕集フィルタは、排気ガス中の微粒子を捕集するフィルタである。なお、排気浄化装置３１に、窒素酸化物を除去するためのＮＯｘ還元触媒と、ＮＯｘ還元触媒にて使用される還元剤を生成する燃料改質触媒と、を取り付けることによって、排気ガス中のＮＯｘを還元させてもよい。 The exhaust gas generated by the combustion is discharged from the exhaust port 23 to the exhaust passage 33 through the exhaust manifold (not shown) of the exhaust system 30. The exhaust gas passes through the turbine wheel 41 of the supercharger 40 and is purified by a diesel oxidation catalyst (not shown) or a particulate collection filter in the exhaust purification device 31 and then flows to the silencer 32. The exhaust gas flowing through the silencer 32 is discharged to the outside with reduced pressure and temperature and reduced exhaust noise. The diesel oxidation catalyst of the exhaust purification device 31 is a catalyst that activates and burns unburned gas in the exhaust gas, and the particulate collection filter is a filter that collects particulates in the exhaust gas. Note that NOx in the exhaust gas is attached to the exhaust purification device 31 by attaching a NOx reduction catalyst for removing nitrogen oxides and a fuel reforming catalyst that generates a reducing agent used in the NOx reduction catalyst. May be reduced.
　過給機４０には、例えば、エンジン２０の回転数に応じて排気ガスや吸入空気の流速を制御する可変容量型のターボチャージャが用いられる。排気ガスの圧力により過給機４０のタービンホイール４１が回転すると、シャフト４３を介してコンプレッサホイール４２にその回転力が伝達されて吸入空気を過給するので、自然吸気の場合と比べてエンジン２０に大量の吸入空気を導入することができる。 For the supercharger 40, for example, a variable capacity turbocharger that controls the flow rate of exhaust gas or intake air according to the rotational speed of the engine 20 is used. When the turbine wheel 41 of the supercharger 40 is rotated by the pressure of the exhaust gas, the rotational force is transmitted to the compressor wheel 42 via the shaft 43 and the intake air is supercharged. A large amount of intake air can be introduced.
　排気流路３３と吸気流路１３との間には、ＥＧＲ装置１００が接続される。 The EGR device 100 is connected between the exhaust flow path 33 and the intake flow path 13.
　ＥＧＲ装置１００は、ＥＧＲクーラ５０と、ＥＧＲバルブ５１と、これらを排気流路３３から還流させた排気ガスが流通可能となるように接続するＥＧＲガス流路５２と、から構成される。ＥＧＲ装置１００がＥＧＲを実行することによって、ＮＯｘの低減や燃費向上を実現することができる。また、ＥＧＲ装置１００は、タービンホイール４１や排気浄化装置３１より上流で排気ガスを還元させるので、タービンホイール４１や排気浄化装置３１に付着する煤等の量を低減させ、耐久性を向上させることができる。 The EGR device 100 includes an EGR cooler 50, an EGR valve 51, and an EGR gas channel 52 that connects the exhaust gas recirculated from the exhaust channel 33 so that the exhaust gas can flow. When the EGR device 100 executes EGR, NOx reduction and fuel efficiency improvement can be realized. Further, since the EGR device 100 reduces exhaust gas upstream from the turbine wheel 41 and the exhaust purification device 31, it reduces the amount of soot and the like adhering to the turbine wheel 41 and the exhaust purification device 31 and improves durability. Can do.
　ＥＧＲガス流路５２は、ＥＧＲ入口側配管５２ａと、ＥＧＲ出口側配管５２ｂと、から構成される。ＥＧＲ入口側配管５２ａは、排気流路３３とＥＧＲクーラ５０とを接続する。ＥＧＲ出口側配管５２ｂは、ＥＧＲクーラ５０と吸気流路１３とを接続する。ＥＧＲ入口側配管５２ａは、ＥＧＲ出口側配管５２ｂよりも短く形成される。 The EGR gas flow path 52 includes an EGR inlet side pipe 52a and an EGR outlet side pipe 52b. The EGR inlet side pipe 52 a connects the exhaust flow path 33 and the EGR cooler 50. The EGR outlet side pipe 52 b connects the EGR cooler 50 and the intake passage 13. The EGR inlet side pipe 52a is formed shorter than the EGR outlet side pipe 52b.
　ＥＧＲバルブ５１は、ＥＧＲ出口側配管５２ｂに設けられ、吸気流路１３に還流される排気ガスの流量を開度に応じて調節する。例えば、ＥＧＲバルブ５１が閉じられた場合には吸気流路１３に排気ガスが還流されなくなり、その後、ＥＧＲバルブ５１が開かれた場合には排気ガスの流れが切り換わり、ＥＧＲバルブ５１の開度に応じて吸気流路１３に還流される。 The EGR valve 51 is provided in the EGR outlet side pipe 52b and adjusts the flow rate of the exhaust gas recirculated to the intake passage 13 according to the opening degree. For example, when the EGR valve 51 is closed, the exhaust gas is not recirculated to the intake flow path 13. After that, when the EGR valve 51 is opened, the flow of the exhaust gas is switched, and the opening degree of the EGR valve 51 is changed. In response to this, the air is recirculated to the intake passage 13.
　ＥＧＲクーラ５０は、内部を流通する冷却水によって排気流路３３から導かれた排気ガスを冷却する。ＥＧＲクーラ５０は、後述する冷却水流路６０との間で冷却水が循環できるように接続されている（図３参照）。 The EGR cooler 50 cools the exhaust gas guided from the exhaust passage 33 by the cooling water flowing through the inside. The EGR cooler 50 is connected so that cooling water can circulate between the cooling water channel 60 described later (see FIG. 3).
　ここで、図２を参照してＥＧＲクーラ５０について説明する。図２は、ＥＧＲクーラ５０の内部断面図である。 Here, the EGR cooler 50 will be described with reference to FIG. FIG. 2 is an internal cross-sectional view of the EGR cooler 50.
　ＥＧＲクーラ５０は、図２に示すように、ＥＧＲガス流路５２に導かれた排気ガスが流通するＥＧＲガス通路５３と、ＥＧＲガス通路５３内の排気ガスとの間で熱交換を行うように冷却水が内部を流通する複数のチューブ５４と、を有する。 As shown in FIG. 2, the EGR cooler 50 performs heat exchange between the EGR gas passage 53 through which the exhaust gas guided to the EGR gas passage 52 circulates and the exhaust gas in the EGR gas passage 53. And a plurality of tubes 54 through which the cooling water flows.
　ＥＧＲガス通路５３は、複数のチューブ５４が間隔を空けて交互に積層されることによって、チューブ５４と隣接する他のチューブ５４との間にそれぞれ形成される。ＥＧＲガス通路５３中には、排気ガスとの熱交換効率を高めるために図示しないフィンが配置される。 The EGR gas passage 53 is formed between the tube 54 and another adjacent tube 54 by alternately stacking a plurality of tubes 54 at intervals. Fins (not shown) are arranged in the EGR gas passage 53 in order to increase the efficiency of heat exchange with the exhaust gas.
　ＥＧＲガス通路５３は、一端がＥＧＲガス流路５２のＥＧＲ入口側配管５２ａに接続され、他端がＥＧＲ出口側配管５２ｂに接続される。 The EGR gas passage 53 has one end connected to the EGR inlet side pipe 52a of the EGR gas flow path 52 and the other end connected to the EGR outlet side pipe 52b.
　ＥＧＲガス流路５２に導かれた排気ガスは、図２に矢印Ａで示すように、ＥＧＲ入口側配管５２ａを通ってＥＧＲガス通路５３を流通する。ＥＧＲガス通路５３を流通した排気ガスは、ＥＧＲバルブ５１が開いている場合には、図２に矢印Ｂで示すようにＥＧＲ出口側配管５２ｂを通って吸気流路１３へ還流される。他方で、排気ガスは、ＥＧＲバルブ５１が閉じている場合には、ＥＧＲガス通路５３やＥＧＲ入口側配管５２ａ周囲で自然対流する。 The exhaust gas guided to the EGR gas channel 52 flows through the EGR gas passage 53 through the EGR inlet side piping 52a as indicated by an arrow A in FIG. When the EGR valve 51 is open, the exhaust gas flowing through the EGR gas passage 53 is returned to the intake passage 13 through the EGR outlet side pipe 52b as indicated by an arrow B in FIG. On the other hand, when the EGR valve 51 is closed, the exhaust gas naturally convects around the EGR gas passage 53 and the EGR inlet side piping 52a.
　複数のチューブ５４には、図２に矢印Ｃで示すように冷却水流路入口５５から冷却水が流入する。冷却水は、チューブ５４内を流通する際に、チューブ５４を介して隣接するＥＧＲガス通路５３を通過する排気ガスと熱交換を行った後、図２に矢印Ｄで示すように冷却水流路出口５６から流出する。 The cooling water flows into the plurality of tubes 54 from the cooling water channel inlet 55 as indicated by an arrow C in FIG. When the cooling water circulates in the tube 54, the cooling water exchanges heat with the exhaust gas passing through the adjacent EGR gas passage 53 via the tube 54, and then, as shown by an arrow D in FIG. 56 flows out.
　図２に示すように、ＥＧＲ出口側配管５２ｂのＥＧＲガス通路５３に接続される接続部付近には、ＥＧＲクーラ出口ガス温度センサ７１が取り付けられる。ＥＧＲクーラ出口ガス温度センサ７１は、ＥＧＲクーラ５０の出口付近の排気ガスの温度をＥＧＲクーラ出口ガス温度Ｔｇとして検出する。なお、ＥＧＲクーラ出口ガス温度センサ７１をＥＧＲガス通路５３の出口部分に設置してもよい。また、冷却水流路出口５６に、ＥＧＲクーラ５０の冷却水の出口温度を検出するＥＧＲ出口水温センサ７２を取り付けてもよい。 As shown in FIG. 2, an EGR cooler outlet gas temperature sensor 71 is attached in the vicinity of the connection portion connected to the EGR gas passage 53 of the EGR outlet side pipe 52b. The EGR cooler outlet gas temperature sensor 71 detects the temperature of the exhaust gas near the outlet of the EGR cooler 50 as the EGR cooler outlet gas temperature Tg. Note that the EGR cooler outlet gas temperature sensor 71 may be installed at the outlet portion of the EGR gas passage 53. Further, an EGR outlet water temperature sensor 72 that detects the outlet temperature of the cooling water of the EGR cooler 50 may be attached to the cooling water passage outlet 56.
　次に図３から図５を参照して、ＥＧＲクーラ５０を冷却する冷却水の冷却水流路６０について説明する。図３は、冷却水流路６０を説明する構成図である。図４は、第１冷却水流路６１の冷却水がＥＧＲクーラ５０に流通するときの冷却水流路６０とＥＧＲクーラ５０との接続状態を説明する図である。図５は、第２冷却水流路６２の冷却水がＥＧＲクーラ５０に流通するときの冷却水流路６０とＥＧＲクーラ５０との接続状態を説明する図である。 Next, with reference to FIG. 3 to FIG. 5, a cooling water flow path 60 for cooling water for cooling the EGR cooler 50 will be described. FIG. 3 is a configuration diagram illustrating the cooling water channel 60. FIG. 4 is a diagram illustrating a connection state between the cooling water passage 60 and the EGR cooler 50 when the cooling water in the first cooling water passage 61 flows through the EGR cooler 50. FIG. 5 is a diagram for explaining a connection state between the cooling water passage 60 and the EGR cooler 50 when the cooling water in the second cooling water passage 62 flows through the EGR cooler 50.
　冷却水流路６０は、図３に示すように、エンジン２０を冷却する冷却水が循環する第１冷却水流路６１と、インタークーラ１２を冷却する冷却水が循環する第２冷却水流路６２と、から構成される。 As shown in FIG. 3, the cooling water flow path 60 includes a first cooling water flow path 61 through which cooling water for cooling the engine 20 circulates, a second cooling water flow path 62 through which cooling water for cooling the intercooler 12 circulates, Consists of
　第１冷却水流路６１は、エンジン２０とラジエータ８０とウォータポンプ８１とを順番に冷却水が循環できるように構成される。ウォータポンプ８１は、冷却水をエンジン２０へと送り出すことで、第１冷却水流路６１に冷却水を循環させる。ラジエータ８０は、エンジン２０を冷却することで加熱された冷却水の熱を外部に放出する。第１冷却水流路６１のウォータポンプ８１とエンジン２０との間には、開閉弁５９ｄが設けられる。 The first cooling water flow path 61 is configured so that cooling water can circulate in order through the engine 20, the radiator 80, and the water pump 81. The water pump 81 circulates the cooling water through the first cooling water channel 61 by sending the cooling water to the engine 20. The radiator 80 releases the heat of the cooling water heated by cooling the engine 20 to the outside. An opening / closing valve 59 d is provided between the water pump 81 in the first cooling water passage 61 and the engine 20.
　第２冷却水流路６２は、インタークーラ１２とウォータポンプ８２とサブラジエータ８３とを順番に冷却水が循環できるように構成される。ウォータポンプ８２は、冷却水をサブラジエータ８３へと送り出すことで、第２冷却水流路６２に冷却水を循環させる。サブラジエータ８３は、インタークーラ１２を冷却することで加熱された冷却水の熱を外部に放出する。第２冷却水流路６２のサブラジエータ８３とインタークーラ１２との間には、第２冷却水流路側三方弁５９ｃが設けられる。ここで、エンジン２０の暖機が完了した後の通常の走行状態において、エンジン２０の熱の影響を受けることのない第２冷却水流路６２には、第１冷却水流路６１を流れる冷却水よりも温度の低い冷却水が循環する。 The second cooling water flow path 62 is configured so that the cooling water can circulate through the intercooler 12, the water pump 82, and the sub radiator 83 in order. The water pump 82 circulates the cooling water through the second cooling water channel 62 by sending the cooling water to the sub-radiator 83. The sub radiator 83 discharges the heat of the cooling water heated by cooling the intercooler 12 to the outside. A second cooling water flow path side three-way valve 59 c is provided between the sub radiator 83 of the second cooling water flow path 62 and the intercooler 12. Here, in the normal running state after the warm-up of the engine 20 is completed, the second cooling water flow path 62 that is not affected by the heat of the engine 20 is supplied from the cooling water flowing through the first cooling water flow path 61. Cooling water with low temperature circulates.
　ＥＧＲクーラ５０は、第１冷却水流路６１に接続される第１接続回路５７と、第２冷却水流路６２に接続される第２接続回路５８と、を備える。 The EGR cooler 50 includes a first connection circuit 57 connected to the first cooling water flow path 61 and a second connection circuit 58 connected to the second cooling water flow path 62.
　第１接続回路５７は、ＥＧＲクーラ５０の冷却水流路入口５５に接続される入口側第１接続回路５７ａと、ＥＧＲクーラ５０の冷却水流路出口５６に接続される出口側第１接続回路５７ｂと、から構成される。冷却水流路入口５５と入口側第１接続回路５７ａとの間には、入口側三方弁５９ａが設けられる。冷却水流路出口５６と出口側第１接続回路５７ｂとの間には、出口側三方弁５９ｂが設けられる。 The first connection circuit 57 includes an inlet-side first connection circuit 57a connected to the coolant passage inlet 55 of the EGR cooler 50, and an outlet-side first connection circuit 57b connected to the coolant passage outlet 56 of the EGR cooler 50. Is composed of. An inlet-side three-way valve 59a is provided between the cooling water channel inlet 55 and the inlet-side first connection circuit 57a. An outlet-side three-way valve 59b is provided between the cooling water passage outlet 56 and the outlet-side first connection circuit 57b.
　第２接続回路５８は、入口側三方弁５９ａを介してＥＧＲクーラ５０の冷却水流路入口５５に接続される入口側第２接続回路５８ａと、出口側三方弁５９ｂを介してＥＧＲクーラ５０の冷却水流路出口５６に接続される出口側第２接続回路５８ｂと、から構成される。 The second connection circuit 58 includes an inlet-side second connection circuit 58a connected to the coolant passage inlet 55 of the EGR cooler 50 via the inlet-side three-way valve 59a, and cooling of the EGR cooler 50 via the outlet-side three-way valve 59b. And an outlet-side second connection circuit 58 b connected to the water flow path outlet 56.
　入口側三方弁５９ａは、図４に太実線で示すように冷却水流路入口５５に入口側第１接続回路５７ａから流入する冷却水の流れを、図５に太実線で示すように入口側第２接続回路５８ａから流入するように切り替えることができる。 The inlet side three-way valve 59a has a flow of cooling water flowing from the inlet side first connection circuit 57a into the cooling water flow path inlet 55 as shown by a thick solid line in FIG. It can switch so that it may flow in from the 2 connection circuit 58a.
　また、出口側三方弁５９ｂは、図４に太実線で示すように冷却水流路出口５６から出口側第１接続回路５７ｂに流出する冷却水の流れを、図５に太実線で示すように出口側第２接続回路５８ｂに流出するように切り替えることができる。 Further, the outlet side three-way valve 59b is configured so that the flow of the cooling water flowing out from the cooling water passage outlet 56 to the outlet side first connection circuit 57b as shown by a thick solid line in FIG. It can switch so that it may flow out to the 2nd side connection circuit 58b.
　このように、入口側三方弁５９ａ及び出口側三方弁５９ｂは、後述するコントローラ７０からの出力信号に応じて、第１接続回路５７と第２接続回路５８との接続を切り替える。 Thus, the inlet-side three-way valve 59a and the outlet-side three-way valve 59b switch the connection between the first connection circuit 57 and the second connection circuit 58 in accordance with an output signal from the controller 70 described later.
　コントローラ７０は、ＣＰＵ（Ｃｅｎｔｒａｌ　Ｐｒｏｃｅｓｓｉｎｇ　Ｕｎｉｔ）、ＲＯＭ（Ｒｅａｄ　Ｏｎｌｙ　Ｍｅｍｏｒｙ）、ＲＡＭ（Ｒａｎｄｏｍ　Ａｃｃｅｓｓ　Ｍｅｍｏｒｙ）等によって構成され、ＲＯＭに記憶されたプログラムをＣＰＵによって読み出すことで、エンジン２０、及びＥＧＲ装置１００に各種機能を発揮させる。 The controller 70 is configured by a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and by reading a program stored in the ROM by the CPU, the controller 20 and the EGR device 100 Demonstrate various functions.
　コントローラ７０には、例えばＥＧＲ装置１００に各種機能を発揮させるために、ＥＧＲクーラ出口ガス温度センサ７１からの信号が入力される。なお、コントローラ７０には、ＥＧＲ出口水温センサ７２、エンジン２０の回転速度を検出する図示しないエンジン回転センサ、又はアクセル開度を検出する図示しないアクセル開度検出センサ等の信号が入力されてもよい。 The controller 70 receives a signal from the EGR cooler outlet gas temperature sensor 71 in order to cause the EGR apparatus 100 to perform various functions, for example. The controller 70 may be input with signals such as an EGR outlet water temperature sensor 72, an engine rotation sensor (not shown) that detects the rotation speed of the engine 20, or an accelerator opening detection sensor (not shown) that detects the accelerator opening. .
　コントローラ７０は、入力された信号に基づいて、ＥＧＲ装置１００の制御を実行する。すなわち、コントローラ７０は、エンジン２０の負荷等に応じて、図１に破線で示すように吸気シャッターバルブ１４とＥＧＲバルブ５１の開閉制御を実行するとともに、図３から図５に破線で示すように入口側三方弁５９ａ、出口側三方弁５９ｂ及び第２冷却水流路側三方弁５９ｃの切替制御と、開閉弁５９ｄの開閉制御と、を実行する。 The controller 70 executes control of the EGR device 100 based on the input signal. That is, the controller 70 performs opening / closing control of the intake shutter valve 14 and the EGR valve 51 as shown by broken lines in FIG. 1 according to the load of the engine 20 and the like, and as shown by broken lines in FIGS. 3 to 5. The switching control of the inlet side three-way valve 59a, the outlet side three-way valve 59b, and the second cooling water flow path side three-way valve 59c and the opening / closing control of the opening / closing valve 59d are executed.
　次に、図６から図７Ｃを参照して、コントローラ７０が実行する冷却水流路切替制御について説明する。図６は、冷却水流路切替制御の流れを示すフローチャートである。図７Ａは、チューブ５４に付着した煤Ｃの状態を説明する模式図である。図７Ｂは、チューブ５４と煤Ｃとの間に生成される凝縮水Ｗを説明する模式図である。図７Ｃは、チューブ５４から煤Ｃが洗い流される状態を説明する模式図である。 Next, the cooling water flow path switching control executed by the controller 70 will be described with reference to FIGS. 6 to 7C. FIG. 6 is a flowchart showing a flow of cooling water flow path switching control. FIG. 7A is a schematic diagram for explaining the state of the ridge C attached to the tube 54. FIG. 7B is a schematic diagram for explaining the condensed water W generated between the tube 54 and the bowl C. FIG. 7C is a schematic diagram for explaining a state in which the eyelid C is washed away from the tube 54.
　コントローラ７０は、ＥＧＲが開始されてＥＧＲバルブ５１が開かれた後、所定周期毎に冷却水流路切替制御を実行する。ＥＧＲが開始されると、排気ガスがＥＧＲガス通路５３内を勢いよく通過する。また、ＥＧＲが開始されると、図４で示すように第１冷却水流路６１の冷却水がＥＧＲクーラ５０に流通する。なお、ディーゼル車両の走行に応じてＥＧＲクーラ５０のチューブ５４の表面には、図７Ａに示すように、煤Ｃが付着して堆積している。 The controller 70 executes the cooling water flow path switching control at predetermined intervals after the EGR is started and the EGR valve 51 is opened. When EGR is started, exhaust gas passes through the EGR gas passage 53 vigorously. Further, when the EGR is started, the cooling water in the first cooling water passage 61 flows to the EGR cooler 50 as shown in FIG. As shown in FIG. 7A, soot C is deposited and deposited on the surface of the tube 54 of the EGR cooler 50 as the diesel vehicle travels.
　ステップＳ１０１では、コントローラ７０は、ＥＧＲクーラ出口ガス温度Ｔｇが所定ガス温度Ｔ以上であるか否かを判定する。コントローラ７０の処理は、ＥＧＲクーラ出口ガス温度Ｔｇが所定ガス温度Ｔ以上である場合にはステップＳ１０２に進み、所定ガス温度Ｔ未満である場合にはステップＳ１０３に進む。所定ガス温度Ｔは、ＥＧＲクーラ５０のチューブ５４の表面に煤Ｃが堆積することによって排気ガスと冷却水との間で熱交換を効率よく行えなくなった結果、排気ガスが冷却されずに高温となったときの温度であり、例えば１８０℃である。 In step S101, the controller 70 determines whether or not the EGR cooler outlet gas temperature Tg is equal to or higher than a predetermined gas temperature T. The processing of the controller 70 proceeds to step S102 when the EGR cooler outlet gas temperature Tg is equal to or higher than the predetermined gas temperature T, and proceeds to step S103 when it is lower than the predetermined gas temperature T. The predetermined gas temperature T is a high temperature without cooling the exhaust gas as a result of the fact that soot C is deposited on the surface of the tube 54 of the EGR cooler 50 and heat exchange between the exhaust gas and the cooling water cannot be performed efficiently. For example, 180 ° C.
　ステップＳ１０２では、コントローラ７０は、第２冷却水流路接続制御を実行する。第２冷却水流路接続制御では、コントローラ７０は、図５に太実線で示すようにＥＧＲクーラ５０の冷却水流路入口５５が第２冷却水流路６２と接続されるように入口側三方弁５９ａの接続を切り替える。また、コントローラ７０は、ＥＧＲクーラ５０の冷却水流路出口５６と出口側第２接続回路５８ｂと第２冷却水流路６２とが直列に接続されるように出口側三方弁５９ｂ及び第２冷却水流路側三方弁５９ｃの接続を切り替える。同時に、コントローラ７０は、第１冷却水流路６１の開閉弁５９ｄを開く。 In step S102, the controller 70 executes second cooling water flow path connection control. In the second cooling water flow path connection control, the controller 70 controls the inlet side three-way valve 59a so that the cooling water flow path inlet 55 of the EGR cooler 50 is connected to the second cooling water flow path 62 as shown by a thick solid line in FIG. Switch connection. The controller 70 also includes the outlet side three-way valve 59b and the second cooling water channel side so that the cooling water channel outlet 56, the outlet side second connection circuit 58b, and the second cooling water channel 62 of the EGR cooler 50 are connected in series. The connection of the three-way valve 59c is switched. At the same time, the controller 70 opens the open / close valve 59 d of the first cooling water flow path 61.
　このように、入口側三方弁５９ａ、出口側三方弁５９ｂ及び第２冷却水流路側三方弁５９ｃの切替制御と、開閉弁５９ｄの開閉制御と、がコントローラ７０に実行されることによって、図５に太実線で示すように第２冷却水流路６２を循環する冷却水がＥＧＲクーラ５０へと流通することになる。エンジン２０を冷却する冷却水と比較して温度の低い冷却水がＥＧＲクーラ５０に流通することになるので、ＥＧＲクーラ５０内を通過する排気ガスは、温度の低い冷却水との間で熱交換を行い冷却される。 As described above, the controller 70 executes the switching control of the inlet side three-way valve 59a, the outlet side three-way valve 59b, and the second cooling water flow path side three-way valve 59c and the opening / closing control of the opening / closing valve 59d. As shown by the thick solid line, the cooling water circulating through the second cooling water flow path 62 flows to the EGR cooler 50. Since the cooling water having a lower temperature than the cooling water for cooling the engine 20 flows through the EGR cooler 50, the exhaust gas passing through the EGR cooler 50 exchanges heat with the cooling water having a lower temperature. To cool.
　ここで、第２冷却水流路６２の冷却水の温度は、排気ガスが結露する露点温度以下となるように設定されており、例えば５０℃前後となるように設定される。ＥＧＲクーラ５０を通過する排気ガスが温度の低い冷却水によって露点以下まで冷却されると、図７Ｂに示すように、チューブ５４と煤Ｃとの間に凝縮水Ｗが生成される。 Here, the temperature of the cooling water in the second cooling water passage 62 is set to be equal to or lower than the dew point temperature at which the exhaust gas is condensed, and is set to, for example, around 50 ° C. When the exhaust gas passing through the EGR cooler 50 is cooled to a dew point or lower by cooling water having a low temperature, condensed water W is generated between the tube 54 and the soot C as shown in FIG. 7B.
　凝縮水Ｗは、煤Ｃ表面の細かい隙間から煤Ｃの内部に侵入した排気ガスがチューブ５４の表面付近で冷却されることによって、排気ガス中に含まれる水蒸気が結露したものである。また、凝縮水Ｗは、チューブ５４の表面付近に堆積した煤Ｃ内に予め存在している排気ガスが冷却され、排気ガス中の水蒸気が結露することによっても生成される。 Condensate water W is a condensate of water vapor contained in the exhaust gas as the exhaust gas that has entered the interior of the soot C through the fine gaps on the soot C surface is cooled near the surface of the tube 54. The condensed water W is also generated when the exhaust gas preliminarily present in the soot C deposited near the surface of the tube 54 is cooled and the water vapor in the exhaust gas is condensed.
　煤Ｃは、燃焼過程で燃え残った炭化水素が様々な化学反応を経て凝集し固体化されたものであり、油性（疎水性）の性質となっている。そのため、生成された凝縮水Ｗは、疎水性の煤Ｃに吸収されることなくチューブ５４と煤Ｃとの間を広がることによって水膜の層を形成する。その結果、煤Ｃは、水膜によってチューブ５４の表面から強制的に分離された状態となる。 煤 C is an oily (hydrophobic) property in which hydrocarbons left unburned in the combustion process are aggregated and solidified through various chemical reactions. Therefore, the generated condensed water W forms a water film layer by spreading between the tube 54 and the ridge C without being absorbed by the hydrophobic ridge C. As a result, the bag C is forcibly separated from the surface of the tube 54 by the water film.
　ＥＧＲの実行中は、排気ガスがＥＧＲガス通路５３内を勢いよく通過しているので、チューブ５４の表面から分離された煤Ｃが、図７Ｃに示すように、排気ガスによって凝縮水Ｗとともに下流へ吹き飛ばされる。なお、吹き飛ばされた凝縮水Ｗは、吹き飛ばされた際に周囲の排気ガスに熱せられて蒸発するので、液体のままエンジン２０に流れることがない。 During execution of EGR, exhaust gas passes through the EGR gas passage 53 vigorously, so that the soot C separated from the surface of the tube 54 is downstream with the condensed water W by the exhaust gas as shown in FIG. 7C. Blown away. The condensed water W blown off is heated by the surrounding exhaust gas and evaporated when blown off, so that it does not flow into the engine 20 as a liquid.
　他方で、ステップＳ１０３では、コントローラ７０は、第１冷却水流路接続制御を実行する。第１冷却水流路接続制御では、コントローラ７０は、図４に太実線で示すようにＥＧＲクーラ５０の冷却水流路入口５５が第１冷却水流路６１と接続されるように入口側三方弁５９ａの接続を切り替える。また、コントローラ７０は、ＥＧＲクーラ５０の冷却水流路出口５６と出口側第１接続回路５７ｂと第２冷却水流路６２とが直列に接続されるように出口側三方弁５９ｂ及び第２冷却水流路側三方弁５９ｃの接続を切り替える。同時に、コントローラ７０は、第１冷却水流路６１の開閉弁５９ｄを閉じる。 On the other hand, in step S103, the controller 70 executes the first coolant flow path connection control. In the first cooling water flow channel connection control, the controller 70 controls the inlet side three-way valve 59a so that the cooling water flow channel inlet 55 of the EGR cooler 50 is connected to the first cooling water flow channel 61 as shown by a thick solid line in FIG. Switch connection. The controller 70 also includes the outlet side three-way valve 59b and the second cooling water channel side so that the cooling water channel outlet 56, the outlet side first connection circuit 57b, and the second cooling water channel 62 of the EGR cooler 50 are connected in series. The connection of the three-way valve 59c is switched. At the same time, the controller 70 closes the on-off valve 59d of the first cooling water channel 61.
　このように、入口側三方弁５９ａ、出口側三方弁５９ｂ及び第２冷却水流路側三方弁５９ｃの切替制御と、開閉弁５９ｄの開閉制御と、がコントローラ７０に実行されることによって、図４に太実線で示すように第１冷却水流路６１を循環する冷却水がＥＧＲクーラ５０へと流通することになる。そのため、エンジン２０を冷却する冷却水によって排気ガスが露点以下まで冷却されない場合には、排気ガス中に含まれる水蒸気は、凝縮することなく気体のままＥＧＲクーラ５０のＥＧＲガス通路５３内を通過する。 Thus, the controller 70 executes the switching control of the inlet side three-way valve 59a, the outlet side three-way valve 59b, and the second cooling water flow path side three-way valve 59c, and the opening / closing control of the opening / closing valve 59d. As shown by the thick solid line, the cooling water circulating in the first cooling water flow path 61 flows to the EGR cooler 50. Therefore, when the exhaust gas is not cooled below the dew point by the cooling water that cools the engine 20, the water vapor contained in the exhaust gas passes through the EGR gas passage 53 of the EGR cooler 50 without being condensed. .
　以上の実施形態によれば、以下に示す効果を奏する。 According to the above embodiment, the following effects are obtained.
　エンジン２０から排出された排気ガスの一部を排気流路３３から吸気流路１３に還流させるＥＧＲ装置１００は、内部を流通する冷却水によって排気流路３３から導かれた排気ガスを冷却するＥＧＲクーラ５０を備える。ＥＧＲクーラ５０は、エンジン２０を冷却する冷却水が流れる第１冷却水流路６１に接続される第１接続回路５７と、第１冷却水流路６１を流れる冷却水よりも温度の低い冷却水が循環する第２冷却水流路６２に接続される第２接続回路５８と、第１接続回路５７と第２接続回路５８との接続を切り替える切替弁としての入口側三方弁５９ａ、出口側三方弁５９ｂ、第２冷却水流路側三方弁５９ｃ及び開閉弁５９ｄと、を備える。入口側三方弁５９ａ、出口側三方弁５９ｂ、第２冷却水流路側三方弁５９ｃ及び開閉弁５９ｄは、ＥＧＲクーラ５０を通過した排気ガスの温度であるＥＧＲクーラ出口ガス温度Ｔｇが所定ガス温度Ｔ以上である場合に、第１接続回路５７から前記第２接続回路５８に接続を切り替える。 The EGR device 100 that recirculates a part of the exhaust gas discharged from the engine 20 from the exhaust flow path 33 to the intake flow path 13 cools the exhaust gas guided from the exhaust flow path 33 by the cooling water flowing inside. A cooler 50 is provided. The EGR cooler 50 circulates a first connection circuit 57 connected to a first cooling water passage 61 through which cooling water for cooling the engine 20 flows, and cooling water having a temperature lower than that of the cooling water flowing through the first cooling water passage 61. An inlet-side three-way valve 59a, an outlet-side three-way valve 59b as a switching valve for switching the connection between the second connection circuit 58 connected to the second cooling water flow path 62 and the first connection circuit 57 and the second connection circuit 58, A second cooling water flow path side three-way valve 59c and an opening / closing valve 59d. In the inlet-side three-way valve 59a, the outlet-side three-way valve 59b, the second cooling water channel side three-way valve 59c, and the on-off valve 59d, the EGR cooler outlet gas temperature Tg, which is the temperature of the exhaust gas that has passed through the EGR cooler 50, is equal to or higher than the predetermined gas temperature T. In this case, the connection is switched from the first connection circuit 57 to the second connection circuit 58.
　このようなＥＧＲ装置１００によれば、エンジン２０を冷却する冷却水の温度が高くなった場合でも、当該冷却水よりも温度の低い冷却水を用いてＥＧＲクーラ５０に導かれた排気ガスを冷却することができ、ＥＧＲクーラ５０の冷却性能を高く保つことができる。また、エンジン２０を冷却する冷却水と比較して温度の低い冷却水によって排気ガスがチューブ５４の表面付近で露点を下回るまで冷却されることで、チューブ５４の表面と付着した煤Ｃとの間に凝縮水Ｗによる水膜が形成される。その結果、水膜によってチューブ５４と煤Ｃとが分離された状態になっているので、ＥＧＲクーラ５０内を流れる排気ガスの勢いによってチューブ５４の表面に付着した煤Ｃを洗い流すことができる。したがって、冷却水と排気ガスとの間の熱交換を妨げる煤Ｃがチューブ５４の表面で固着することも抑制でき、熱交換効率の低下を防止することができる。 According to such an EGR device 100, even when the temperature of the cooling water for cooling the engine 20 becomes high, the exhaust gas led to the EGR cooler 50 is cooled using the cooling water having a temperature lower than that of the cooling water. The cooling performance of the EGR cooler 50 can be kept high. Further, the exhaust gas is cooled near the surface of the tube 54 by the cooling water having a lower temperature than that of the cooling water for cooling the engine 20 until the dew point is lowered between the surface of the tube 54 and the attached soot C. A water film is formed by the condensed water W. As a result, since the tube 54 and the soot C are separated by the water film, the soot C attached to the surface of the tube 54 can be washed away by the momentum of the exhaust gas flowing in the EGR cooler 50. Accordingly, it is possible to suppress the stick C, which hinders heat exchange between the cooling water and the exhaust gas, from adhering to the surface of the tube 54, thereby preventing a decrease in heat exchange efficiency.
　また、ＥＧＲクーラ５０のチューブ５４の表面に付着した煤Ｃを都度洗い流すことができ熱交換効率の低下を防止することができるので、長時間にわたり連続して走行する場合等においてもＥＧＲクーラ５０の冷却性能を高く保つことができる。 Further, since the soot C adhering to the surface of the tube 54 of the EGR cooler 50 can be washed away each time and a decrease in heat exchange efficiency can be prevented, the EGR cooler 50 can be used even when traveling continuously for a long time. Cooling performance can be kept high.
　ＥＧＲ装置１００では、第２冷却水流路６２は、冷却水の熱を外部に放出するサブラジエータ８３と、ＥＧＲクーラ５０とは異なる他の機器を冷却する熱交換器としてのインタークーラ１２と、に接続される。第２接続回路５８は、ＥＧＲクーラ出口ガス温度Ｔｇが所定ガス温度Ｔ以上である場合に、第２冷却水流路６２の冷却水がサブラジエータ８３を流通した後、熱交換器としてのインタークーラ１２を流通する前に第２接続回路５８を流通するように、サブラジエータ８３とインタークーラ１２との間に直列に接続される。 In the EGR device 100, the second cooling water flow path 62 includes a sub-radiator 83 that releases heat of the cooling water to the outside, and an intercooler 12 that serves as a heat exchanger that cools other equipment different from the EGR cooler 50. Connected. When the EGR cooler outlet gas temperature Tg is equal to or higher than the predetermined gas temperature T, the second connection circuit 58 allows the intercooler 12 as a heat exchanger after the cooling water in the second cooling water passage 62 flows through the sub radiator 83. Is connected in series between the sub-radiator 83 and the intercooler 12 so as to circulate through the second connection circuit 58 before circulating.
　したがって、サブラジエータ８３によって外部に熱を放出して冷却された冷却水が、ＥＧＲクーラ５０を冷却する前に暖められることがないので、ＥＧＲクーラ５０を効率よく冷却することができる。なお、ＥＧＲクーラ５０は、インタークーラ１２と比較して熱容量が通常小さく設定されるので、冷却水は、ＥＧＲクーラ５０を冷却した後においてもインタークーラ１２を十分に冷却することができる。 Therefore, since the cooling water cooled by releasing heat to the outside by the sub radiator 83 is not heated before cooling the EGR cooler 50, the EGR cooler 50 can be cooled efficiently. Since the EGR cooler 50 is usually set to have a smaller heat capacity than the intercooler 12, the cooling water can sufficiently cool the intercooler 12 even after the EGR cooler 50 is cooled.
　なお、第２冷却水流路６２を循環する冷却水は、インタークーラ１２に限らず、ディーゼル車両の熱を発生する各種装置を冷却することとしてもよい。 Note that the cooling water circulating through the second cooling water flow path 62 is not limited to the intercooler 12 and may cool various devices that generate heat of the diesel vehicle.
　ＥＧＲ装置１００では、インタークーラ１２は、吸気流路１３に設置される。そのため、エンジン２０付近にある別の第２冷却水流路６２を用いることができるので、ＥＧＲクーラ５０の第２接続回路５８を短くすることができる。 In the EGR device 100, the intercooler 12 is installed in the intake passage 13. Therefore, since another second cooling water flow path 62 near the engine 20 can be used, the second connection circuit 58 of the EGR cooler 50 can be shortened.
　以上、本発明の実施形態について説明したが、上記実施形態は本発明の適用例の一部を示したに過ぎず、本発明の技術的範囲を上記実施形態の具体的構成に限定する趣旨ではない。 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.
　例えば、上記実施形態とは三方弁や開閉弁の数を変えて、図８に示すようにＥＧＲクーラ２５０の冷却水流路入口２５５や冷却水流路出口２５６を構成してもよい。 For example, the number of three-way valves and on-off valves may be changed from that of the above embodiment, and the cooling water channel inlet 255 and the cooling water channel outlet 256 of the EGR cooler 250 may be configured as shown in FIG.
　冷却水流路入口２５５は、第１冷却水流路入口２５５ａと第２冷却水流路入口２５５ｂとから構成される。第１冷却水流路入口２５５ａは開閉弁２５９ａを介して入口側第１接続回路５７ａに接続され、第２冷却水流路入口２５５ｂは三方弁２５９ｅを介して第２冷却水流路６２に接続される。 The cooling water channel inlet 255 is composed of a first cooling water channel inlet 255a and a second cooling water channel inlet 255b. The first coolant passage inlet 255a is connected to the inlet-side first connection circuit 57a via the on-off valve 259a, and the second coolant passage inlet 255b is connected to the second coolant passage 62 via the three-way valve 259e.
　冷却水流路出口２５６は、第１冷却水流路出口２５６ａと第２冷却水流路出口２５６ｂとから構成される。第１冷却水流路出口２５６ａは開閉弁２５９ｂを介して出口側第１接続回路５７ｂに接続され、第２冷却水流路出口２５６ｂは第２冷却水流路側三方弁５９ｃを介して第２冷却水流路６２に接続される。 The cooling water channel outlet 256 is composed of a first cooling water channel outlet 256a and a second cooling water channel outlet 256b. The first cooling water channel outlet 256a is connected to the outlet side first connection circuit 57b via the on-off valve 259b, and the second cooling water channel outlet 256b is connected to the second cooling water channel 62 via the second cooling water channel side three-way valve 59c. Connected to.
　第１冷却水流路６１の冷却水がＥＧＲクーラ２５０に流通するときには、冷却水流路６０とＥＧＲクーラ２５０との接続状態は、図９の太実線のようになる。また、第２冷却水流路６２の冷却水がＥＧＲクーラ２５０に流通するときには、冷却水流路６０とＥＧＲクーラ２５０との接続状態は、図１０の太実線のようになる。 When the cooling water in the first cooling water passage 61 flows through the EGR cooler 250, the connection state between the cooling water passage 60 and the EGR cooler 250 is as shown by a thick solid line in FIG. Further, when the cooling water in the second cooling water flow path 62 flows through the EGR cooler 250, the connection state between the cooling water flow path 60 and the EGR cooler 250 is as shown by a thick solid line in FIG.
　このように、上記実施形態の三方弁の一部を開閉弁に代えてＥＧＲクーラ２５０を構成することによっても上記実施形態と同様に冷却水流路切替制御を実行することができる。 As described above, the cooling water flow path switching control can also be executed in the same manner as in the above embodiment by configuring the EGR cooler 250 by replacing a part of the three-way valve in the above embodiment with an on-off valve.
　また、上記実施形態のようにＥＧＲクーラ出口ガス温度Ｔｇが所定ガス温度Ｔ以上である場合に限らず、コントローラ７０は、定期的に、又は所望のタイミングで運転手の要求等に応じて、第２冷却水流路接続制御を実行してＥＧＲクーラ５０のチューブ５４の表面に付着した煤Ｃを洗い流すことができる。したがって、負荷の高い走行等を予定している場合に、ＥＧＲクーラ５０の冷却性能を予め高く保った上で当該走行等を開始することができるので、排気ガスの温度が過度に上昇することを抑制できる。 Further, the controller 70 is not limited to the case where the EGR cooler outlet gas temperature Tg is equal to or higher than the predetermined gas temperature T as in the above-described embodiment. The soot C adhering to the surface of the tube 54 of the EGR cooler 50 can be washed away by executing the 2 cooling water flow path connection control. Therefore, when traveling with a high load or the like is scheduled, it is possible to start the traveling or the like while keeping the cooling performance of the EGR cooler 50 high in advance, so that the temperature of the exhaust gas rises excessively. Can be suppressed.
　さらに、ＥＧＲ装置１００は、上記実施形態の態様に限らず、吸気流路１３のコンプレッサホイール４２と排気流路３３の排気浄化装置３１の下流側との間を接続するように設置することとしてもよい。これによって、上記実施形態と同様の効果を得ることができる。 Furthermore, the EGR device 100 is not limited to the aspect of the above embodiment, and may be installed so as to connect between the compressor wheel 42 of the intake passage 13 and the downstream side of the exhaust purification device 31 of the exhaust passage 33. Good. As a result, the same effect as in the above embodiment can be obtained.
　また、ディーゼル車両に限らず、ガソリン車両に適用してもよい。 Further, the present invention is not limited to diesel vehicles, and may be applied to gasoline vehicles.
　本願は、２０１６年７月６日に日本国特許庁に出願された特願２０１６－１３４３５２に基づく優先権を主張し、この出願の全ての内容は参照により本明細書に組み込まれる。 This application claims priority based on Japanese Patent Application No. 2016-134352 filed with the Japan Patent Office on July 6, 2016, the entire contents of which are incorporated herein by reference.

Claims (3)

  1. 　エンジンから排出された排気ガスの一部を排気流路から吸気流路に還流させるＥＧＲ装置であって、
    　内部を流通する冷却水によって前記排気流路から導かれた排気ガスを冷却するＥＧＲクーラを備え、
    　前記ＥＧＲクーラは、
    　前記エンジンを冷却する冷却水が流れる第１冷却水流路に接続される第１接続回路と、
    　前記第１冷却水流路を流れる冷却水よりも温度の低い冷却水が循環する第２冷却水流路に接続される第２接続回路と、
    　前記第１接続回路と前記第２接続回路との接続を切り替える切替弁と、
    を備え、
    　前記切替弁は、前記ＥＧＲクーラを通過した排気ガスの温度が所定温度以上である場合に、前記第１接続回路から前記第２接続回路に接続を切り替える、
    ＥＧＲ装置。     An EGR device that recirculates a part of exhaust gas discharged from an engine from an exhaust passage to an intake passage,
    An EGR cooler for cooling the exhaust gas guided from the exhaust flow path by the cooling water flowing through the inside;
    The EGR cooler is
    A first connection circuit connected to a first cooling water flow path through which cooling water for cooling the engine flows;
    A second connection circuit connected to a second cooling water flow path through which cooling water having a temperature lower than that of the cooling water flowing through the first cooling water flow path circulates;
    A switching valve for switching the connection between the first connection circuit and the second connection circuit;
    With
    The switching valve switches the connection from the first connection circuit to the second connection circuit when the temperature of the exhaust gas that has passed through the EGR cooler is equal to or higher than a predetermined temperature.
    EGR device.
  2. 　請求項１に記載のＥＧＲ装置であって、
    　前記第２冷却水流路は、冷却水の熱を外部に放出するラジエータと、前記エンジンとは異なる他の機器を冷却する熱交換器と、に接続され、
    　前記第２接続回路は、前記ＥＧＲクーラを通過した排気ガスの温度が前記所定温度以上である場合に、前記第２冷却水流路の冷却水が前記ラジエータを流通した後、前記熱交換器を流通する前に前記第２接続回路を流通するように、前記ラジエータと前記熱交換器との間に直列に接続される、
    ＥＧＲ装置。     The EGR device according to claim 1,
    The second cooling water flow path is connected to a radiator that releases heat of the cooling water to the outside and a heat exchanger that cools other equipment different from the engine,
    When the temperature of the exhaust gas that has passed through the EGR cooler is equal to or higher than the predetermined temperature, the second connection circuit circulates the heat exchanger after the cooling water in the second cooling water passage has circulated through the radiator. Connected in series between the radiator and the heat exchanger so as to circulate through the second connection circuit before
    EGR device.
  3. 　請求項２に記載のＥＧＲ装置であって、
    　前記熱交換器は、前記吸気流路に設置される水冷式のインタークーラである、
    ＥＧＲ装置。     The EGR device according to claim 2,
    The heat exchanger is a water-cooled intercooler installed in the intake passage.
    EGR device.
PCT/JP2017/024536 2016-07-06 2017-07-04 Egr device WO2018008649A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2914694A1 (en) * 2007-04-05 2008-10-10 Renault Sas Heat exchange controlling system for engine of motor vehicle, has cooling loop coupled with parallel circuit through four way valves, where valves define distinct functioning modes corresponding to pathways of coolant in parallel circuit
JP2011132852A (en) * 2009-12-24 2011-07-07 Hino Motors Ltd Exhaust emission control device for engine
JP2014163335A (en) * 2013-02-27 2014-09-08 Calsonic Kansei Corp Cooling device of exhaust gas recirculation device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2914694A1 (en) * 2007-04-05 2008-10-10 Renault Sas Heat exchange controlling system for engine of motor vehicle, has cooling loop coupled with parallel circuit through four way valves, where valves define distinct functioning modes corresponding to pathways of coolant in parallel circuit
JP2011132852A (en) * 2009-12-24 2011-07-07 Hino Motors Ltd Exhaust emission control device for engine
JP2014163335A (en) * 2013-02-27 2014-09-08 Calsonic Kansei Corp Cooling device of exhaust gas recirculation device

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