WO2014103824A1 - Exhaust-heat-recovery device and exhaust-heat-recovery method - Google Patents

Exhaust-heat-recovery device and exhaust-heat-recovery method Download PDF

Info

Publication number
WO2014103824A1
WO2014103824A1 PCT/JP2013/083866 JP2013083866W WO2014103824A1 WO 2014103824 A1 WO2014103824 A1 WO 2014103824A1 JP 2013083866 W JP2013083866 W JP 2013083866W WO 2014103824 A1 WO2014103824 A1 WO 2014103824A1
Authority
WO
WIPO (PCT)
Prior art keywords
exhaust
heat recovery
recirculation
engine
exhaust heat
Prior art date
Application number
PCT/JP2013/083866
Other languages
French (fr)
Japanese (ja)
Inventor
永井　宏幸
真一朗 溝口
Original Assignee
日産自動車株式会社
ルノー エス．ア．エス．
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 日産自動車株式会社, ルノー エス．ア．エス． filed Critical 日産自動車株式会社
Publication of WO2014103824A1 publication Critical patent/WO2014103824A1/en

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
    • F02G5/00—Profiting from waste heat of combustion engines, not otherwise provided for
    • F02G5/02—Profiting from waste heat of exhaust gases
    • F02G5/04—Profiting from waste heat of exhaust gases in combination with other waste heat from combustion engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K15/00—Adaptations of plants for special use
    • F01K15/02—Adaptations of plants for special use for driving vehicles, e.g. locomotives
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K23/00—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids
    • F01K23/02—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled
    • F01K23/06—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle
    • F01K23/065—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle the combustion taking place in an internal combustion piston engine, e.g. a diesel engine
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K9/00—Plants characterised by condensers arranged or modified to co-operate with the engines
    • F01K9/003—Plants characterised by condensers arranged or modified to co-operate with the engines condenser cooling circuits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D13/00—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing
    • F02D13/02—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation
    • F02D13/0261—Controlling the valve overlap
    • F02D13/0265—Negative valve overlap for temporarily storing residual gas in the cylinder
    • 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
    • F02M26/01—Internal exhaust gas recirculation, i.e. wherein the residual exhaust gases are trapped in the cylinder or pushed back from the intake or the exhaust manifold into the combustion chamber without the use of additional passages
    • 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
    • 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
    • F02M26/24—Layout, e.g. schematics with two or more coolers
    • 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
    • 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
    • F01N5/00—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy
    • F01N5/02—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy the devices using heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
    • F02G2260/00—Recuperating heat from exhaust gases of combustion engines and heat from cooling circuits
    • 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

  • This invention relates to an exhaust heat recovery device that recovers exhaust heat of an engine and regenerates it as kinetic energy.
  • An exhaust heat recovery device (Rankine cycle system) that recovers exhaust heat of the engine through cooling water or refrigerant and regenerates it as kinetic energy by rotating the expander by this heat has been put into practical use.
  • JP 2010-78216A proposes a method of recovering the heat of the exhaust gas passing through the pipe by providing a heat exchanger in the pipe of the exhaust gas recirculation apparatus (EGR).
  • EGR exhaust gas recirculation apparatus
  • EGR exhaust gas recirculation gas by EGR
  • the external EGR is provided with a valve in a pipe communicating from the exhaust pipe to the intake pipe, and the exhaust gas recirculation amount is adjusted by the valve.
  • the internal EGR adjusts the amount of recirculation of exhaust gas in the cylinder by overlapping the intake valve and the exhaust valve of the engine.
  • the internal EGR can return unburned hydrocarbons (HC) to the cylinders again before passing through the catalyst to reduce the HC emission amount, and the recirculation amount can be adjusted with good response only by controlling the intake and exhaust valves.
  • HC hydrocarbons
  • the external EGR has an advantage that the recirculation gas can be cooled, the recirculation amount can be increased, and knocking can be improved.
  • the present invention has been made in view of such problems, and in an exhaust heat recovery device that recovers heat of an exhaust gas recirculation device in an engine and regenerates it as an energy, an exhaust heat recovery device that can improve fuel efficiency is provided.
  • the purpose is to provide.
  • an exhaust heat recovery device that recovers exhaust heat of a vehicle engine and regenerates it as energy, and recirculates a part of the exhaust of the engine to the intake side;
  • a recirculation valve that controls the amount of exhaust gas that is recirculated, an exhaust heat recovery device that recovers exhaust heat from the exhaust recirculation passage, an expander that can be driven to rotate by the heat recovered by the exhaust heat recovery device, and an engine
  • a control device that controls the operation of the recirculation valve and the expander.
  • the control device controls the timing of the intake valve and the exhaust valve of the engine to recirculate the exhaust gas at the first recirculation amount, and controls the recirculation valve to control the exhaust gas to the second recirculation amount.
  • external EGR control for recirculation.
  • the ratio of the second recirculation amount is increased more than the first recirculation amount.
  • FIG. 1 is an explanatory diagram showing a configuration of a Rankine cycle system centering on an engine according to a first embodiment of the present invention.
  • FIG. 2A is an explanatory diagram illustrating an operation region of the Rankine cycle according to the first embodiment of this invention.
  • FIG. 2B is an explanatory diagram illustrating an operation region of the Rankine cycle according to the first embodiment of this invention.
  • FIG. 3 is an explanatory diagram showing the relationship between the ratio between the external EGR and the internal EGR and the vehicle speed when the Rankine cycle according to the first embodiment of the present invention is operated.
  • FIG. 4A is an explanatory diagram of heat exchange and its efficiency in the Rankine cycle of the first embodiment of the present invention.
  • FIG. 4A is an explanatory diagram of heat exchange and its efficiency in the Rankine cycle of the first embodiment of the present invention.
  • FIG. 4B is an explanatory diagram of heat exchange and its efficiency in the Rankine cycle of the first embodiment of the present invention.
  • FIG. 4C is an explanatory diagram of heat exchange and its efficiency in the Rankine cycle of the first embodiment of the present invention.
  • FIG. 5 is an explanatory diagram showing the relationship between the cooling water temperature and the fuel efficiency effect in the Rankine cycle of the first embodiment of the present invention.
  • FIG. 6 is a flowchart showing control of Rankine cycle operation executed by the controller according to the first embodiment of the present invention.
  • FIG. 7 is an explanatory diagram showing the configuration of a Rankine cycle system centering on the engine of the second embodiment of the present invention.
  • FIG. 8 is an explanatory diagram showing the configuration of a Rankine cycle system centering on the engine of the third embodiment of the present invention.
  • FIG. 1 is an explanatory diagram showing a configuration of a Rankine cycle system 1 centering on an engine 2 according to a first embodiment of the present invention.
  • FIG. 1 shows a cooling water circuit 10 of an engine 2 mounted on a vehicle and a Rankine cycle system 1 that recovers exhaust heat of the engine 2 to generate driving force.
  • the engine 2 includes an exhaust passage 3 and an intake passage 6.
  • the exhaust passage 3 includes an exhaust manifold 4, an exhaust passage 3 connected to a collecting portion of the exhaust manifold 4, a catalyst 5 provided in the exhaust passage 3, and a silencer 16.
  • the intake passage 6 includes an intake manifold 7, a collector portion 8 connected to the intake manifold 7, and an upstream air filter 9.
  • the EGR 20 includes an EGR passage 21, an EGR valve 22, and a heat exchanger 23.
  • the cooling water circuit 10 of the engine 2 is provided with a cooling water pump 11, a radiator 12, and a thermostat 13.
  • the cooling water circuit 10 circulates the cooling water to the engine 2 or the like by the cooling water pump 11, and cools the cooling water by exchanging heat between the cooling water and the atmosphere by the radiator 12.
  • the thermostat 13 opens and closes the passage to the radiator 12 according to the cooling water temperature, and prevents the cooling water temperature from being lowered.
  • Part of the cooling water that has passed through the engine 2 flows to the heat exchanger 23 of the EGR 20.
  • the heat exchanger 23 performs heat exchange between the exhaust gas passing through the EGR passage 21 and the cooling water, and raises the cooling water temperature.
  • the cooling water that has passed through the heat exchanger 23 is circulated again by the cooling water pump 11 via a heater 41 and an evaporator 42 described later.
  • a part of the cooling water that has passed through the engine 2 is circulated again by the cooling water pump 11 via the evaporator 42.
  • the Rankine cycle circuit 40 includes a heater 41, an evaporator 42, an expander 43, a condenser 44, and a refrigerant pump 46.
  • the refrigerant pump 46 is connected to the crank pulley 45 of the engine 2 via a belt 47, is driven to rotate as the crank pulley 45 rotates, and circulates the refrigerant to the Rankine cycle circuit 40.
  • the refrigerant pump 46 is coaxially connected to the expander 43 and rotates together with the expander 43.
  • the refrigerant discharged from the refrigerant pump 46 exchanges heat with the cooling water circulating in the engine 2 in the evaporator 42, and further exchanges heat with the cooling water heated in the heat exchanger 23 in the heater 41. From phase to gas phase.
  • the gas-phase refrigerant that has been subjected to heat exchange and has become high temperature and high pressure is expanded in the expander 43, and energy is given to the expander 43 by the volume change.
  • the expander 43 converts energy into rotational energy, rotationally drives the coaxial refrigerant pump 46, and rotationally drives the crank pulley 45 via the belt 47. This assists driving of the engine. That is, the energy generated by the recovered heat can be used as the regenerative power of the engine 2.
  • the gas-phase refrigerant that has exited the expander 43 is cooled and converted from the gas phase to the liquid phase by exchanging heat with the atmosphere in the condenser 44, and is circulated through the Rankine cycle circuit 40 again by the refrigerant pump 46.
  • the condenser 44 is provided with a fan 48 to promote cooling of the refrigerant.
  • the controller 30 controls a transmission gear ratio (not shown) and a driving force of the engine 2 based on signals such as an accelerator pedal opening (APO), a brake pedal depression amount (BRK), a vehicle speed (VSP), and the like. And drive the vehicle.
  • APO accelerator pedal opening
  • BRK brake pedal depression amount
  • VSP vehicle speed
  • controller 30 controls whether to rotate the expander 43 of the Rankine cycle system 1 based on these signals, thereby regenerating exhaust heat energy and assisting the driving force of the engine 2. Control.
  • the controller 30 also controls the amount of exhaust gas recirculated to the intake side of the engine 2 by controlling the opening degree of the EGR valve 22.
  • the controller 30 controls the variable valve timing mechanism 31 to control the opening / closing timing of the intake valve 2a and the exhaust valve 2b of the engine 2.
  • the Rankine cycle system 1 is configured as described above, and recovers exhaust heat of the engine 2 and generates regenerative power by the recovered heat to assist the engine driving force and improve the fuel efficiency of the engine. it can.
  • the controller 30 determines whether to assist the power of the engine 2 by operating the Rankine cycle system 1 based on the coolant temperature, the outside air temperature, the engine rotational speed Ne, the vehicle speed VSP, and the like. In the embodiment of the present invention, recovering exhaust heat and operating the Rankine cycle system 1 to assist the power of the engine 2 will be referred to as “operating the Rankine cycle” hereinafter.
  • FIG. 2A and FIG. 2B are explanatory diagrams showing an operation region of the Rankine cycle according to the first embodiment of the present invention.
  • FIG. 2A shows the Rankine cycle operating region where the horizontal axis is the outside air temperature and the vertical axis is the engine water temperature (cooling water temperature).
  • FIG. 2B shows the Rankine cycle operating region when the horizontal axis is the engine rotation speed and the vertical axis is the engine torque (engine load).
  • the Rankine cycle is operated when the operating region satisfies both of these conditions, that is, the driving force of the engine 2 is driven by rotating the expander 43 with the refrigerant that has recovered the heat. Assist.
  • Rankine cycle Stop operation As shown in FIG. 2A, in the low water temperature side region where the cooling water temperature is low (for example, 80 ° C.) and priority is given to warming up the engine 2, and in the high outside temperature side region where the load of the air conditioner or the like increases, Rankine cycle Stop operation. This is because in such a region, operating the Rankine cycle increases the load, which in turn reduces the fuel efficiency of the engine 2.
  • the Rankine cycle operation is stopped in the region where the engine rotational speed is low and the capacity of the exhaust heat is small and the region on the high rotational speed side where the friction of the expander 43 increases. Since the expander 43 is connected to the crankshaft of the engine 2, the rotation speed of the expander 43 depends on the engine rotation speed. It is difficult for the expander 43 to have a highly efficient structure with little friction even when the rotational speed is high. Therefore, the expander 43 is designed so that the friction is small and the efficiency is high in the engine rotation speed region where the Rankine cycle is frequently operated. The Rankine cycle is efficiently operated in such a rotational speed range.
  • the exhaust gas is recirculated to the intake side. Circulation takes place.
  • the external EGR is provided with an EGR valve 22 in an EGR passage 21 communicating from the exhaust passage 3 to the intake passage 6, and the exhaust gas recirculation amount is adjusted by the opening degree of the EGR valve 22.
  • the internal EGR overlaps the timing at which the intake valve 2a of the engine 2 is opened and the timing at which the exhaust valve 2b is closed, thereby adjusting the exhaust gas recirculation amount.
  • unburned hydrocarbons can be returned to the cylinders again before passing through the catalyst to reduce HC emissions, and the amount of recirculation can be adjusted only by controlling the valve opening.
  • the amount can be controlled with good response.
  • it is necessary to finely control the recirculation amount, and it is preferable to actively use the internal EGR.
  • the external EGR can cool the recirculated exhaust gas by the heat exchanger 23 and does not raise the intake air temperature, so that the fuel efficiency can be improved. Further, there is an advantage that the amount of exhaust gas recirculation can be increased. In particular, when traveling in a constant speed range at a high vehicle speed, such as on an expressway, the response is not emphasized. Therefore, the fuel efficiency is improved by increasing the recirculation amount by the external EGR.
  • the internal EGR and the external EGR have respective merits. Which method is used to recirculate the exhaust gas or to combine these to recirculate the exhaust gas depends on the fuel efficiency of the engine 2. A big influence.
  • the controller 30 appropriately change the exhaust gas recirculation amount and the ratio of the recirculation amount between the external EGR and the internal EGR in accordance with the running state of the vehicle and the operating state of the engine. As described above, the fuel efficiency of the engine 2 can be improved by the operation of the Rankine cycle and the control of the external EGR and the internal EGR.
  • FIG. 3 is an explanatory diagram showing the relationship between the overlap amount (O / L) between the intake valve 2a and the exhaust valve 2b when operating the Rankine cycle of the first embodiment of the present invention.
  • the upper part of FIG. 3 shows the relationship between the EGR rate and the overlap amount (O / L) between the intake valve 2a and the exhaust valve 2b.
  • the lower part shows the relationship between the heat release amount (heat amount radiated from the exhaust to the medium) in the heat exchanger 23 and the overlap amount (O / L) between the intake valve 2a and the exhaust valve 2b.
  • the upper limit amount of exhaust gas recirculated during operation of the engine 2 is determined.
  • the ratio between the external EGR and the internal EGR is determined based on the vehicle speed with respect to the upper limit amount. That is, the higher the vehicle speed is, the smaller the overlap amount (O / L) between the intake valve 2a and the exhaust valve 2b is controlled to increase the external EGR ratio.
  • the heat radiation efficiency in the condenser 44 is increased by the traveling wind. This is because the thermal efficiency of the Rankine cycle is increased, and the amount of heat radiated from the exhaust gas to the medium in the heat exchanger 23 is increased.
  • the upper limit amount of the exhaust gas recirculated in the cylinder is kept constant, and the overlap amount (O / L) between the intake valve 2a and the exhaust valve 2b is increased as the vehicle speed is increased to increase the ratio of the external EGR. As a result, it is possible to recover heat by operating the Rankine cycle and improve fuel efficiency of the engine 2 by lowering the exhaust temperature.
  • the ratio of the internal EGR is increased. This is because, as described above, the internal EGR can adjust the recirculation amount only by controlling the valve opening, and therefore has an advantage that the recirculation amount can be controlled with good response. Thus, the exhaust gas recirculation amount can be appropriately controlled even in the transient operation of the engine 2.
  • 4A to 4C are explanatory diagrams of the relationship between the vehicle speed and the heat exchange in the Rankine cycle of the first embodiment of the present invention.
  • FIG. 4A shows the relationship between the heat capacity received by the medium in the heat exchanger 23 and the fuel efficiency when the Rankine cycle is operated, with respect to the vehicle speed. As shown in FIG. 4A, it is shown that as the vehicle speed increases, the ratio between the heat receiving capacity in the heat exchanger 23 and the fuel efficiency effect due to Rankine cycle operation increases, and the fuel efficiency effect improves.
  • 4B and 4C show the relationship between the vehicle speed and the ratio of the external EGR to the internal EGR, and the relationship between the heat dissipation capability (capacity of cooling the medium) in the condenser 44. If the vehicle speed is high, the traveling wind becomes large, and the heat dissipation capability in the condenser 44 is also improved. Accordingly, the cooling effect of the exhaust gas in the EGR 20 is also improved by the operation of the Rankine cycle. Therefore, as described above with reference to FIG. 3, the fuel efficiency can be improved by increasing the ratio of the external EGR to the internal EGR as the vehicle speed increases.
  • FIG. 5 is an explanatory diagram showing the relationship between the cooling water temperature and the fuel consumption effect in the Rankine cycle of the first embodiment of the present invention.
  • the fuel efficiency of the engine 2 is slightly improved by cooling the exhaust gas in the heat exchanger 23 of the EGR 20.
  • the Rankine cycle When the coolant temperature reaches the Rankine cycle operating range (80 to 100 ° C.), the Rankine cycle is operated and the driving force of the engine 2 is assisted by the rotation of the expander 43, so the fuel efficiency is greatly improved. To do. If the cooling water temperature exceeds the Rankine cycle operating range, the fuel efficiency will decrease. Further, when the coolant temperature becomes higher (from 110 ° C.), the exhaust of the EGR 20 cannot be sufficiently cooled, and the fuel efficiency is lowered.
  • the Rankine cycle operating range 80 to 100 ° C.
  • FIG. 6 is a flowchart showing the Rankine cycle operation control executed by the controller 30 according to the first embodiment of the present invention.
  • the controller 30 always acquires the vehicle speed VSP and the coolant temperature (step S10).
  • the controller 30 determines whether or not the operation region of the Rankine cycle system is based on the water temperature and the cooling water temperature with reference to the maps shown in FIGS. 2A and 2B (step S20).
  • the operation region of the Rankine cycle system is determined by the cooling efficiency with which the medium is cooled by the condenser 44. That is, the fuel efficiency increases when the Rankine cycle system is operated due to the difference between the heat recovered by the medium in the heat exchanger 23 and the heat generated when the medium is cooled by the condenser 44 (assuming the driving force of the engine 2). If possible, this is the operating area of the Rankine cycle system. Since the cooling efficiency of the condenser 44 increases even when the vehicle speed is high, the operation region of the Rankine cycle system is set. Even when the cooling water temperature is high, the amount of heat received by the medium increases, so the temperature difference increases, and the operation region of the Rankine cycle system is set.
  • step S30 the controller 30 increases the exhaust gas recirculation amount (second recirculation amount) by the external EGR, and the exhaust gas by the internal EGR.
  • the recirculation amount (first recirculation amount) is decreased. Thereby, the ratio of the external EGR to the internal EGR is increased.
  • the controller 30 increases the amount of exhaust gas that passes through the EGR passage 21 by controlling the opening degree of the EGR valve 22 in the external EGR.
  • the controller 30 controls the variable valve timing mechanism 31 to reduce the overlap period between the opening timing of the intake valve 2a and the closing timing of the exhaust valve 2b, and the recirculation amount of the exhaust gas in the cylinder. Decrease. More specifically, the controller 30 decreases the exhaust gas recirculation amount by bringing the timing at which the intake valve 2a is opened and the timing at which the exhaust valve 2b are closed closer to top dead center. The ratio of the exhaust gas recirculated can be changed by such control.
  • the ratio of the exhaust gas recirculation amount by the external EGR is made larger than the exhaust gas recirculation amount by the internal EGR within a range not exceeding the upper limit value of the exhaust gas recirculated in the cylinder.
  • step S40 the controller 30 decreases the exhaust gas recirculation amount (second recirculation amount) by the external EGR, and recirculates the exhaust gas by the internal EGR.
  • the circulation amount (first recirculation amount) is increased. Thereby, the ratio of the external EGR to the internal EGR is lowered.
  • the controller 30 controls the opening degree of the EGR valve 22 to reduce the amount of exhaust gas passing through the EGR passage 21.
  • the controller 30 controls the variable valve timing mechanism 31 in the internal EGR to expand the overlap period between the timing of opening the intake valve 2a and the timing of closing the exhaust valve 2b, thereby re-exhaust gas in the cylinder. Increase circulation. More specifically, the controller 30 increases the exhaust gas recirculation amount by advancing the timing of opening the intake valve 2a and delaying the timing of closing the exhaust valve 2b. The ratio of the exhaust gas recirculated can be changed by such control.
  • step S10 After the process of step S30 or step S40, the process after step S10 is repeated.
  • the heat recovered by the cooling water in the heat exchanger 23 is transmitted to the medium by the evaporator 42 and the heater 41.
  • the expander 43 is rotationally driven by the heat of the medium to assist the driving force of the engine 2.
  • the controller 30 sets the ratio of the second recirculation amount by the external EGR to the first recirculation amount by the internal EGR. Control to increase.
  • the exhaust gas recirculated to the intake side by the external EGR can be increased to recover the heat of the exhaust gas and to reduce the temperature of the recirculated exhaust gas.
  • the fuel efficiency can be improved by collecting the exhaust heat of the engine 2 and the fuel efficiency can be improved by lowering the temperature of the recirculated exhaust gas.
  • step S30 when the ratio of the exhaust gas recirculation amount by the external EGR is made larger than the internal EGR, the total exhaust gas recirculation amount (the internal EGR and the external EGR) than the upper limit value of the exhaust gas recirculated in the cylinder. And the total).
  • the combustion stability can be improved, and the fuel consumption can be improved while suppressing the vibration of the vehicle.
  • FIG. 7 is an explanatory diagram showing the configuration of the Rankine cycle system 1 centering on the engine 2 according to the second embodiment of the present invention.
  • the embodiment of the second embodiment is a modification of the first embodiment, in which Rankine cycle refrigerant is directly introduced into the heat exchanger 23 of the EGR 20 and heat exchange is performed between the exhaust of the EGR 20 and the refrigerant.
  • Other configurations and the operation of the controller 30 are the same as those in the first embodiment.
  • the amount of heat received by the refrigerant in the Rankine cycle increases, so that the temperature difference in the Rankine cycle can be increased.
  • the Rankine cycle can be operated with higher efficiency, and the fuel efficiency of the engine can be improved. Since the exhaust gas of the EGR 20 reaches several hundred degrees, it is necessary to select an appropriate refrigerant that is not affected by heat.
  • FIG. 8 is an explanatory diagram showing the configuration of the Rankine cycle system 1 centering on the engine 2 according to the third embodiment of the present invention.
  • the third embodiment is a modification of the first embodiment.
  • a cooling circuit 50 and a heat exchanger 51 are provided separately, and the Rankine cycle refrigerant is cooled by the cooling circuit 50. Configured to do.
  • Other configurations and the operation of the controller 30 are the same as those in the first embodiment.
  • the cooling circuit 50 includes a pump 52 for circulating the refrigerant, a heat exchanger 51 for exchanging heat with the Rankine cycle refrigerant, and a sub-radiator 53 for cooling the refrigerant by exchanging heat with the atmosphere.
  • the cooling circuit 50 is configured to be able to cool electronic devices (motor MOT, inverter INV, intercooler CAC, etc.) mounted on the vehicle.
  • the cooling circuit 50 is further provided, and the Rankine cycle is cooled by the refrigerant that has less fluctuation than the series cooling in the air in the heat exchanger 51, so that the difference between the high temperature and the low temperature particularly in the Rankine cycle when the vehicle speed fluctuates. Can be bigger. As a result, the Rankine cycle can be operated with higher efficiency, and the fuel efficiency of the engine can be improved.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
  • Exhaust-Gas Circulating Devices (AREA)
  • Engine Equipment That Uses Special Cycles (AREA)

Abstract

This exhaust-heat-recovery device is equipped with an expander capable of rotating and driving as a result of heat recovered by an exhaust-heat recovery apparatus for recovering exhaust heat in an exhaust recirculation channel for recirculating, on the air-intake side, a portion of the exhaust from an engine. The exhaust-heat-recovery device executes: an internal EGR control for controlling the timing of an engine air-intake valve and exhaust-discharge valve, and recirculating a first recirculation amount of the exhaust; and an external EGR control for controlling a recirculation valve, and recirculating a second recirculation amount of exhaust. When the expander is rotated and driven as a result of the heat recovered by the exhaust-heat recovery apparatus, the proportion of the second recirculation amount is increased more than the first recirculation amount.

Description

排熱回収装置及び排熱回収方法Waste heat recovery device and waste heat recovery method
　この発明は、エンジンの排熱を回収してこれを運動エネルギとして回生する排熱回収装置に関する。 This invention relates to an exhaust heat recovery device that recovers exhaust heat of an engine and regenerates it as kinetic energy.
　エンジンの排熱を冷却水や冷媒を介して回収し、この熱により膨張機を回転させて運動エネルギとして回生する排熱回収装置（ランキンサイクルシステム）が実用化されている。 An exhaust heat recovery device (Rankine cycle system) that recovers exhaust heat of the engine through cooling water or refrigerant and regenerates it as kinetic energy by rotating the expander by this heat has been put into practical use.
　このような排熱回収装置として、ＪＰ２０１０－７８２１６Ａには、排気再循環装置（ＥＧＲ）の配管に熱交換機を設け、配管を通過する排気の熱を回収する方法が提案されている。ＥＧＲ通路に熱交換機を設けることにより、排熱を回収できると共に、ＥＧＲにより再循環される排気の温度を冷却できるという利点がある。 As such an exhaust heat recovery apparatus, JP 2010-78216A proposes a method of recovering the heat of the exhaust gas passing through the pipe by providing a heat exchanger in the pipe of the exhaust gas recirculation apparatus (EGR). By providing a heat exchanger in the EGR passage, there is an advantage that exhaust heat can be recovered and the temperature of the exhaust gas recirculated by the EGR can be cooled.
　ＥＧＲによる排気の再循環には、内部ＥＧＲと外部ＥＧＲとの２種類方法が知られている。外部ＥＧＲは、排気管から吸気管へと連通する配管にバルブを設け、バルブにより排気の再循環量を調整する。内部ＥＧＲは、エンジンの吸気バルブと排気バルブをオーバーラップさせて気筒内で排気の再循環量を調整する。 There are two known methods for recirculation of exhaust gas by EGR: internal EGR and external EGR. The external EGR is provided with a valve in a pipe communicating from the exhaust pipe to the intake pipe, and the exhaust gas recirculation amount is adjusted by the valve. The internal EGR adjusts the amount of recirculation of exhaust gas in the cylinder by overlapping the intake valve and the exhaust valve of the engine.
　内部ＥＧＲは未燃焼の炭化水素（ＨＣ）を触媒通過前に再び気筒内に戻してＨＣの排出量を低減できるほか、吸気バルブ及び排気バルブの制御のみで再循環量の調節をレスポンス良く行えるというメリットがある。外部ＥＧＲは、再循環ガスが冷却可能であり、再循環量を大きくすることができるうえ、ノック改善も可能というメリットがある。 The internal EGR can return unburned hydrocarbons (HC) to the cylinders again before passing through the catalyst to reduce the HC emission amount, and the recirculation amount can be adjusted with good response only by controlling the intake and exhaust valves. There are benefits. The external EGR has an advantage that the recirculation gas can be cooled, the recirculation amount can be increased, and knocking can be improved.
　そこで、これら内部ＥＧＲと外部ＥＧＲとを組み合わせ、車両の走行状態やエンジンの操作状態に応じて、適宜外部ＥＧＲと内部ＥＧＲとの排気の再循環量や再循環量の割合を変更することが望ましい。 Therefore, it is desirable to combine the internal EGR and the external EGR, and appropriately change the exhaust gas recirculation amount and the ratio of the recirculation amount between the external EGR and the internal EGR in accordance with the traveling state of the vehicle and the operating state of the engine. .
　一方で、外部ＥＧＲの配管に熱交換機を設けて排熱を回収する場合は、これら内部ＥＧＲと外部ＥＧＲとの排気の再循環量や再循環量の割合に応じて、排熱の回収を適切に制御する必要がある。制御が適切でない場合は、排熱によるエネルギの回生を行ったとしても燃費効率がかえって悪化するという問題が発生する。 On the other hand, when exhaust heat is recovered by installing a heat exchanger in the piping of the external EGR, it is appropriate to recover the exhaust heat according to the exhaust gas recirculation amount and the ratio of the recirculation amount between the internal EGR and the external EGR. Need to control. When the control is not appropriate, there is a problem that the fuel efficiency is deteriorated even if the energy is regenerated by exhaust heat.
　本発明は、このような問題点に鑑みてなされたものであり、エンジンにおける排気再循環装置の熱を回収してエネルギとして回生する排熱回収装置において、燃費効率を向上できる排熱回収装置を提供することを目的とする。 The present invention has been made in view of such problems, and in an exhaust heat recovery device that recovers heat of an exhaust gas recirculation device in an engine and regenerates it as an energy, an exhaust heat recovery device that can improve fuel efficiency is provided. The purpose is to provide.
　本発明の一実施態様によると、車両のエンジンの排熱を回収してエネルギとして回生する排熱回収装置であって、エンジンの排気の一部を吸気側に再循環する排気再循環通路と、再循環される排気の量を制御する再循環弁と、排気再循環通路の排熱を回収する排熱回収機と、排熱回収機により回収された熱により回転駆動可能な膨張機と、エンジン、前記再循環弁及び前記膨張機の動作を制御する制御装置と、を備える排熱回収装置に適用される。制御装置は、エンジンの吸気バルブと排気バルブとのタイミングを制御して排気を第１の再循環量で再循環させる内部ＥＧＲ制御と、再循環弁を制御して排気を第２の再循環量で再循環させる外部ＥＧＲ制御と、を実行する。排熱回収機により回収された熱により膨張機を回転駆動させる場合は、第１の再循環量よりも第２の再循環量の比率を増加させることを特徴とする。 According to one embodiment of the present invention, an exhaust heat recovery device that recovers exhaust heat of a vehicle engine and regenerates it as energy, and recirculates a part of the exhaust of the engine to the intake side; A recirculation valve that controls the amount of exhaust gas that is recirculated, an exhaust heat recovery device that recovers exhaust heat from the exhaust recirculation passage, an expander that can be driven to rotate by the heat recovered by the exhaust heat recovery device, and an engine And a control device that controls the operation of the recirculation valve and the expander. The control device controls the timing of the intake valve and the exhaust valve of the engine to recirculate the exhaust gas at the first recirculation amount, and controls the recirculation valve to control the exhaust gas to the second recirculation amount. And external EGR control for recirculation. In the case where the expander is rotationally driven by the heat recovered by the exhaust heat recovery machine, the ratio of the second recirculation amount is increased more than the first recirculation amount.
図１は、本発明の第１実施形態のエンジンを中心としたランキンサイクルシステムの構成を示す説明図である。FIG. 1 is an explanatory diagram showing a configuration of a Rankine cycle system centering on an engine according to a first embodiment of the present invention. 図２Ａは、本発明の第１の実施形態のランキンサイクルの運転領域を示す説明図である。FIG. 2A is an explanatory diagram illustrating an operation region of the Rankine cycle according to the first embodiment of this invention. 図２Ｂは、本発明の第１の実施形態のランキンサイクルの運転領域を示す説明図である。FIG. 2B is an explanatory diagram illustrating an operation region of the Rankine cycle according to the first embodiment of this invention. 図３は、本発明の第１の実施形態のランキンサイクルを運転する場合の外部ＥＧＲと内部ＥＧＲとの比率と車速との関係を示す説明図である。FIG. 3 is an explanatory diagram showing the relationship between the ratio between the external EGR and the internal EGR and the vehicle speed when the Rankine cycle according to the first embodiment of the present invention is operated. 図４Ａは、本発明の第１の実施形態のランキンサイクルにおける熱交換とその効率の説明図である。FIG. 4A is an explanatory diagram of heat exchange and its efficiency in the Rankine cycle of the first embodiment of the present invention. 図４Ｂは、本発明の第１の実施形態のランキンサイクルにおける熱交換とその効率の説明図である。FIG. 4B is an explanatory diagram of heat exchange and its efficiency in the Rankine cycle of the first embodiment of the present invention. 図４Ｃは、本発明の第１の実施形態のランキンサイクルにおける熱交換とその効率の説明図である。FIG. 4C is an explanatory diagram of heat exchange and its efficiency in the Rankine cycle of the first embodiment of the present invention. 図５は、本発明の第１の実施形態のランキンサイクルにおける冷却水温と燃費効果との関係を示す説明図である。FIG. 5 is an explanatory diagram showing the relationship between the cooling water temperature and the fuel efficiency effect in the Rankine cycle of the first embodiment of the present invention. 図６は、本発明の第１の実施形態のコントローラが実行するランキンサイクル運転の制御を示すフローチャートである。FIG. 6 is a flowchart showing control of Rankine cycle operation executed by the controller according to the first embodiment of the present invention. 図７は、本発明の第２実施形態のエンジンを中心としたランキンサイクルシステムの構成を示す説明図である。FIG. 7 is an explanatory diagram showing the configuration of a Rankine cycle system centering on the engine of the second embodiment of the present invention. 図８は、本発明の第３実施形態のエンジンを中心としたランキンサイクルシステムの構成を示す説明図である。FIG. 8 is an explanatory diagram showing the configuration of a Rankine cycle system centering on the engine of the third embodiment of the present invention.
　以下、添付図面を参照しながら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 accompanying drawings.
　＜第１実施形態＞
　図１は、本発明の第１実施形態のエンジン２を中心としたランキンサイクルシステム１の構成を示す説明図である。 <First Embodiment>
FIG. 1 is an explanatory diagram showing a configuration of a Rankine cycle system 1 centering on an engine 2 according to a first embodiment of the present invention.
　図１には、車両に搭載されるエンジン２の冷却水回路１０と、エンジン２の排熱を回収して駆動力を発生するランキンサイクルシステム１とが示されている。 FIG. 1 shows a cooling water circuit 10 of an engine 2 mounted on a vehicle and a Rankine cycle system 1 that recovers exhaust heat of the engine 2 to generate driving force.
　エンジン２は、排気通路３と吸気通路６とを備える。排気通路３は、排気マニホールド４と、排気マニホールド４の集合部に接続される排気通路３と、排気通路３に備えられる触媒５と、消音機１６とから構成される。吸気通路６は、吸気マニホールド７と、吸気マニホールド７に接続されるコレクタ部８と、上流側のエアフィルタ９とから構成される。 The engine 2 includes an exhaust passage 3 and an intake passage 6. The exhaust passage 3 includes an exhaust manifold 4, an exhaust passage 3 connected to a collecting portion of the exhaust manifold 4, a catalyst 5 provided in the exhaust passage 3, and a silencer 16. The intake passage 6 includes an intake manifold 7, a collector portion 8 connected to the intake manifold 7, and an upstream air filter 9.
　排気通路３と吸気通路６との間には、排気の一部を吸気に再循環する排気再循環装置（ＥＧＲ）２０が備えられる。ＥＧＲ２０は、ＥＧＲ通路２１と、ＥＧＲバルブ２２と、熱交換機２３とを備える。 Between the exhaust passage 3 and the intake passage 6, an exhaust gas recirculation device (EGR) 20 that recirculates part of the exhaust gas to the intake air is provided. The EGR 20 includes an EGR passage 21, an EGR valve 22, and a heat exchanger 23.
　エンジン２の冷却水回路１０には、冷却水ポンプ１１と、ラジエタ１２と、サーモスタット１３とが備えられている。冷却水回路１０は、冷却水ポンプ１１によって冷却水をエンジン２等に循環し、ラジエタ１２により冷却水と大気とで熱交換を行うことで冷却水を冷却する。サーモスタット１３は、冷却水水温によってラジエタ１２への通路を開閉し、冷却水水温が低下することを防止する。 The cooling water circuit 10 of the engine 2 is provided with a cooling water pump 11, a radiator 12, and a thermostat 13. The cooling water circuit 10 circulates the cooling water to the engine 2 or the like by the cooling water pump 11, and cools the cooling water by exchanging heat between the cooling water and the atmosphere by the radiator 12. The thermostat 13 opens and closes the passage to the radiator 12 according to the cooling water temperature, and prevents the cooling water temperature from being lowered.
　エンジン２を通過した冷却水の一部は、ＥＧＲ２０の熱交換機２３へと流れる。熱交換機２３は、ＥＧＲ通路２１を通過する排気と冷却水とで熱交換を行い、冷却水温度を上昇させる。熱交換機２３を通過した冷却水は、後述する加熱機４１及び蒸発機４２を経由して、冷却水ポンプ１１により再び循環される。 Part of the cooling water that has passed through the engine 2 flows to the heat exchanger 23 of the EGR 20. The heat exchanger 23 performs heat exchange between the exhaust gas passing through the EGR passage 21 and the cooling water, and raises the cooling water temperature. The cooling water that has passed through the heat exchanger 23 is circulated again by the cooling water pump 11 via a heater 41 and an evaporator 42 described later.
　エンジン２を通過した冷却水の一部は、蒸発機４２を経由して、冷却水ポンプ１１により再び循環される。 A part of the cooling water that has passed through the engine 2 is circulated again by the cooling water pump 11 via the evaporator 42.
　ランキンサイクルシステム１において、ランキンサイクル回路４０には、加熱機４１、蒸発機４２、膨張機４３、凝縮機４４、冷媒ポンプ４６が備えられている。 In the Rankine cycle system 1, the Rankine cycle circuit 40 includes a heater 41, an evaporator 42, an expander 43, a condenser 44, and a refrigerant pump 46.
　冷媒ポンプ４６は、エンジン２のクランクプーリ４５とベルト４７を介して連結され、クランクプーリ４５の回転に伴い回転駆動され、冷媒をランキンサイクル回路４０に循環する。冷媒ポンプ４６は、膨張機４３と同軸に連結されて膨張機４３と共に回転する。 The refrigerant pump 46 is connected to the crank pulley 45 of the engine 2 via a belt 47, is driven to rotate as the crank pulley 45 rotates, and circulates the refrigerant to the Rankine cycle circuit 40. The refrigerant pump 46 is coaxially connected to the expander 43 and rotates together with the expander 43.
　冷媒ポンプ４６を出た冷媒は、蒸発機４２において、エンジン２を循環する冷却水とで熱交換を行ない、加熱機４１において、熱交換機２３において加熱された冷却水とでさらに熱交換を行い液相から気相となる。熱交換が行われて高温高圧となった気相冷媒は、膨張機４３において膨張され、その体積変化により膨張機４３にエネルギを与える。膨張機４３は、エネルギを回転エネルギに変換し、同軸の冷媒ポンプ４６を回転駆動させると共に、ベルト４７を介してクランクプーリ４５を回転駆動する。これによりエンジンの駆動がアシストされる。すなわち、回収した熱により発生したエネルギをエンジン２の回生動力とすることができる。 The refrigerant discharged from the refrigerant pump 46 exchanges heat with the cooling water circulating in the engine 2 in the evaporator 42, and further exchanges heat with the cooling water heated in the heat exchanger 23 in the heater 41. From phase to gas phase. The gas-phase refrigerant that has been subjected to heat exchange and has become high temperature and high pressure is expanded in the expander 43, and energy is given to the expander 43 by the volume change. The expander 43 converts energy into rotational energy, rotationally drives the coaxial refrigerant pump 46, and rotationally drives the crank pulley 45 via the belt 47. This assists driving of the engine. That is, the energy generated by the recovered heat can be used as the regenerative power of the engine 2.
　膨張機４３を出た気相の冷媒は、凝縮機４４において大気と熱交換を行うことにより、冷却されて気相から液相となり、再び冷媒ポンプ４６によりランキンサイクル回路４０を循環する。凝縮機４４にはファン４８が備えられており、冷媒の冷却を促進する。 The gas-phase refrigerant that has exited the expander 43 is cooled and converted from the gas phase to the liquid phase by exchanging heat with the atmosphere in the condenser 44, and is circulated through the Rankine cycle circuit 40 again by the refrigerant pump 46. The condenser 44 is provided with a fan 48 to promote cooling of the refrigerant.
　これらエンジン２をはじめとする各構成は、コントローラ３０により制御される。 These components including the engine 2 are controlled by the controller 30.
　コントローラ３０は、例えば、アクセルペダル開度（ＡＰＯ）、ブレーキペダル踏み込み量（ＢＲＫ）、車速（ＶＳＰ）等の信号に基づいて、図示しない変速機の変速比とエンジン２の駆動力とを制御して、車両を運転する。 For example, the controller 30 controls a transmission gear ratio (not shown) and a driving force of the engine 2 based on signals such as an accelerator pedal opening (APO), a brake pedal depression amount (BRK), a vehicle speed (VSP), and the like. And drive the vehicle.
　また、コントローラ３０は、これら各信号に基づいて、ランキンサイクルシステム１の膨張機４３の回転駆動を制御することにより、排熱のエネルギを回生してエンジン２の駆動力をアシストするか否かを制御する。また、コントローラ３０は、ＥＧＲバルブ２２の開度を制御して、エンジン２の吸気側に再循環する排気の量を制御する。また、コントローラ３０は、可変バルブタイミング機構３１を制御して、エンジン２の吸気バルブ２ａ及び排気バルブ２ｂの開閉タイミングを制御する。 Further, the controller 30 controls whether to rotate the expander 43 of the Rankine cycle system 1 based on these signals, thereby regenerating exhaust heat energy and assisting the driving force of the engine 2. Control. The controller 30 also controls the amount of exhaust gas recirculated to the intake side of the engine 2 by controlling the opening degree of the EGR valve 22. The controller 30 controls the variable valve timing mechanism 31 to control the opening / closing timing of the intake valve 2a and the exhaust valve 2b of the engine 2.
　ランキンサイクルシステム１はこのように構成され、エンジン２の排熱を回収して回収された熱により回生動力を発生することでエンジンの駆動力をアシストして、エンジンの燃費効率を向上することができる。 The Rankine cycle system 1 is configured as described above, and recovers exhaust heat of the engine 2 and generates regenerative power by the recovered heat to assist the engine driving force and improve the fuel efficiency of the engine. it can.
　次に、本発明の実施形態のランキンサイクルシステム１による排熱の回収を説明する。 Next, recovery of exhaust heat by the Rankine cycle system 1 according to the embodiment of the present invention will be described.
　コントローラ３０は、冷却水温度、外気温、エンジン回転速度Ｎｅ、車速ＶＳＰ等により、ランキンサイクルシステム１を運転させてエンジン２の動力をアシストするか否かを決定する。本発明の実施形態では、排熱を回収してランキンサイクルシステム１を運転させてエンジン２の動力をアシストすることを、以降は「ランキンサイクルを運転する」と表記する。 The controller 30 determines whether to assist the power of the engine 2 by operating the Rankine cycle system 1 based on the coolant temperature, the outside air temperature, the engine rotational speed Ne, the vehicle speed VSP, and the like. In the embodiment of the present invention, recovering exhaust heat and operating the Rankine cycle system 1 to assist the power of the engine 2 will be referred to as “operating the Rankine cycle” hereinafter.
　図２Ａ及び図２Ｂは、本発明の第１実施形態のランキンサイクルの運転領域を示す説明図である。図２Ａは横軸を外気温、縦軸をエンジン水温（冷却水温度）としたときのランキンサイクルの運転領域を示す。図２Ｂは、横軸をエンジン回転速度、縦軸をエンジントルク（エンジン負荷）としたときのランキンサイクルの運転領域を示す。 FIG. 2A and FIG. 2B are explanatory diagrams showing an operation region of the Rankine cycle according to the first embodiment of the present invention. FIG. 2A shows the Rankine cycle operating region where the horizontal axis is the outside air temperature and the vertical axis is the engine water temperature (cooling water temperature). FIG. 2B shows the Rankine cycle operating region when the horizontal axis is the engine rotation speed and the vertical axis is the engine torque (engine load).
　図２Ａ、図２Ｂに示すように、運転領域がこれら両方の条件が満たされた場合にランキンサイクルを運転、すなわち、熱を回収した冷媒によって膨張機４３を回転駆動させて、エンジン２の駆動力をアシストする。 As shown in FIGS. 2A and 2B, the Rankine cycle is operated when the operating region satisfies both of these conditions, that is, the driving force of the engine 2 is driven by rotating the expander 43 with the refrigerant that has recovered the heat. Assist.
　図２Ａに示すように、冷却水水温が低く（例えば８０℃）エンジン２の暖機を優先する低水温側の領域と、エアコン等の負荷が増大する高外気温側の領域では、ランキンサイクルの運転を停止する。このような領域では、ランキンサイクルを運転することにより負荷が増大し、かえってエンジン２の燃費効率が低下するためである。 As shown in FIG. 2A, in the low water temperature side region where the cooling water temperature is low (for example, 80 ° C.) and priority is given to warming up the engine 2, and in the high outside temperature side region where the load of the air conditioner or the like increases, Rankine cycle Stop operation. This is because in such a region, operating the Rankine cycle increases the load, which in turn reduces the fuel efficiency of the engine 2.
　図２Ｂに示すように、エンジン回転速度が低く排熱の容量が小さい領域と、膨張機４３のフリクションが増大する高回転速度側の領域では、ランキンサイクルの運転を停止する。膨張機４３はエンジン２のクランクシャフトに連結されているため、膨張器４３の回転速度はエンジン回転速度に依存する。膨張機４３は、回転速度が高い場合にもフリクションが少なく高効率な構造とすることは難しい。そこで、膨張機４３は、ランキンサイクルを運転する頻度が高いエンジン回転速度域においてフリクションが小さく高効率となるように設計されている。このような回転速度域でランキンサイクルが効率よく運転される。 As shown in FIG. 2B, the Rankine cycle operation is stopped in the region where the engine rotational speed is low and the capacity of the exhaust heat is small and the region on the high rotational speed side where the friction of the expander 43 increases. Since the expander 43 is connected to the crankshaft of the engine 2, the rotation speed of the expander 43 depends on the engine rotation speed. It is difficult for the expander 43 to have a highly efficient structure with little friction even when the rotational speed is high. Therefore, the expander 43 is designed so that the friction is small and the efficiency is high in the engine rotation speed region where the Rankine cycle is frequently operated. The Rankine cycle is efficiently operated in such a rotational speed range.
　次に、エンジン２の排気再循環について説明する。 Next, the exhaust gas recirculation of the engine 2 will be described.
　エンジン２のポンピングロスの低減による燃費効率の向上を目的として、また、排気中の炭化水素（ＨＣ）、窒素酸化物（ＮＯｘ）等の削減を目的として、排気を吸気側に再循環させる排気再循環が行われる。 For the purpose of improving fuel efficiency by reducing the pumping loss of the engine 2 and for the purpose of reducing hydrocarbons (HC), nitrogen oxides (NOx), etc. in the exhaust, the exhaust gas is recirculated to the intake side. Circulation takes place.
　排気再循環の方法として、内部ＥＧＲと外部ＥＧＲとの２種類方法が知られている。外部ＥＧＲは、排気通路３から吸気通路６へと連通するＥＧＲ通路２１にＥＧＲバルブ２２を設け、ＥＧＲバルブ２２の開度により排気の再循環量を調整する。内部ＥＧＲは、エンジン２の吸気バルブ２ａを開くタイミングと排気バルブ２ｂを閉じるタイミングとをオーバーラップさせ、気筒内で排気の再循環量を調整する。 There are two known methods for exhaust gas recirculation, internal EGR and external EGR. The external EGR is provided with an EGR valve 22 in an EGR passage 21 communicating from the exhaust passage 3 to the intake passage 6, and the exhaust gas recirculation amount is adjusted by the opening degree of the EGR valve 22. The internal EGR overlaps the timing at which the intake valve 2a of the engine 2 is opened and the timing at which the exhaust valve 2b is closed, thereby adjusting the exhaust gas recirculation amount.
　内部ＥＧＲでは、未燃焼の炭化水素（ＨＣ）を触媒通過前に再び気筒内に戻してＨＣの排出量を低減できるほか、バルブ開度の制御のみで再循環量の調節を行えるので、再循環量の制御をレスポンスよく行えるというメリットがある。特に、市街地などストップアンドゴーが多い場合には、再循環量を細かく制御する必要があり、内部ＥＧＲを積極的に用いることが好適である。 In internal EGR, unburned hydrocarbons (HC) can be returned to the cylinders again before passing through the catalyst to reduce HC emissions, and the amount of recirculation can be adjusted only by controlling the valve opening. There is an advantage that the amount can be controlled with good response. In particular, when there are many stop-and-go operations such as in urban areas, it is necessary to finely control the recirculation amount, and it is preferable to actively use the internal EGR.
　一方、外部ＥＧＲは、再循環される排気を熱交換機２３により冷却でき吸気温度を上昇させることがないため、燃費効率を向上できる。また、排気の再循環量を大きくすることができるというメリットがある。特に、高速道路など高車速で一定速度域により走行する場合などには、レスポンスが重視されないので外部ＥＧＲによる再循環量を多くすることにより燃費効率が向上する。 On the other hand, the external EGR can cool the recirculated exhaust gas by the heat exchanger 23 and does not raise the intake air temperature, so that the fuel efficiency can be improved. Further, there is an advantage that the amount of exhaust gas recirculation can be increased. In particular, when traveling in a constant speed range at a high vehicle speed, such as on an expressway, the response is not emphasized. Therefore, the fuel efficiency is improved by increasing the recirculation amount by the external EGR.
　このように、内部ＥＧＲと外部ＥＧＲとにはそれぞれメリットがあり、いずれの方式を用いて排気を再循環させるか、又は、これらを組み合わせて排気を再循環させるかは、エンジン２の燃費効率に大きく影響する。 As described above, the internal EGR and the external EGR have respective merits. Which method is used to recirculate the exhaust gas or to combine these to recirculate the exhaust gas depends on the fuel efficiency of the engine 2. A big influence.
　そこで、コントローラ３０は、車両の走行状態やエンジンの動作状態に応じて、適宜、外部ＥＧＲと内部ＥＧＲとの排気の再循環量や再循環量の割合を変更することが望ましい。そして、前述のようにランキンサイクルの運転と、外部ＥＧＲと内部ＥＧＲとの制御とにより、エンジン２の燃費効率を向上させることができる。 Therefore, it is desirable that the controller 30 appropriately change the exhaust gas recirculation amount and the ratio of the recirculation amount between the external EGR and the internal EGR in accordance with the running state of the vehicle and the operating state of the engine. As described above, the fuel efficiency of the engine 2 can be improved by the operation of the Rankine cycle and the control of the external EGR and the internal EGR.
　図３は、本発明の第１実施形態のランキンサイクルを運転する場合の吸気バルブ２ａと排気バルブ２ｂとのオーバーラップ量（Ｏ／Ｌ）と関係を示す説明図である。図３の上段は、ＥＧＲ率と吸気バルブ２ａと排気バルブ２ｂとのオーバーラップ量（Ｏ／Ｌ）との関係とを示す。下段は、熱交換機２３における放熱量（排気から媒体へと放熱される熱の量）と吸気バルブ２ａと排気バルブ２ｂとのオーバーラップ量（Ｏ／Ｌ）との関係を示す。 FIG. 3 is an explanatory diagram showing the relationship between the overlap amount (O / L) between the intake valve 2a and the exhaust valve 2b when operating the Rankine cycle of the first embodiment of the present invention. The upper part of FIG. 3 shows the relationship between the EGR rate and the overlap amount (O / L) between the intake valve 2a and the exhaust valve 2b. The lower part shows the relationship between the heat release amount (heat amount radiated from the exhaust to the medium) in the heat exchanger 23 and the overlap amount (O / L) between the intake valve 2a and the exhaust valve 2b.
　図３において、エンジン２の運転中に再循環される排気の上限量が決まっている。この上限量に対して、外部ＥＧＲと内部ＥＧＲとの比率が車速に基づいて決定される。すなわち、車速が高いほど、吸気バルブ２ａと排気バルブ２ｂとのオーバーラップ量（Ｏ／Ｌ）を小さくして、外部ＥＧＲの比率が大きくなるように制御する。 In FIG. 3, the upper limit amount of exhaust gas recirculated during operation of the engine 2 is determined. The ratio between the external EGR and the internal EGR is determined based on the vehicle speed with respect to the upper limit amount. That is, the higher the vehicle speed is, the smaller the overlap amount (O / L) between the intake valve 2a and the exhaust valve 2b is controlled to increase the external EGR ratio.
　車速が高い場合は、走行風により凝縮機４４における放熱効率が高くなる。これにより、ランキンサイクルの熱効率が大きくなるので、熱交換機２３において排気から媒体へと放熱される熱の量が増えるためである。 When the vehicle speed is high, the heat radiation efficiency in the condenser 44 is increased by the traveling wind. This is because the thermal efficiency of the Rankine cycle is increased, and the amount of heat radiated from the exhaust gas to the medium in the heat exchanger 23 is increased.
　気筒内に再循環される排気の上限量は一定のまま、車速が大きいほど吸気バルブ２ａと排気バルブ２ｂとのオーバーラップ量（Ｏ／Ｌ）を大きくして、外部ＥＧＲの比率を大きくする。これにより、ランキンサイクルを運転することによる熱の回収と、排気温度を下げることによるエンジン２の燃費効率の向上とを行うことができるようになる。 The upper limit amount of the exhaust gas recirculated in the cylinder is kept constant, and the overlap amount (O / L) between the intake valve 2a and the exhaust valve 2b is increased as the vehicle speed is increased to increase the ratio of the external EGR. As a result, it is possible to recover heat by operating the Rankine cycle and improve fuel efficiency of the engine 2 by lowering the exhaust temperature.
　ランキンサイクルの運転を行わない場合、すなわち、図２Ａ及び図２Ｂに示す運転領域を外れている場合は、内部ＥＧＲの比率を大きくする。これは、前述のように、内部ＥＧＲはバルブ開度の制御のみで再循環量の調節を行えるので、再循環量の制御をレスポンスよく行えるというメリットがあるためである。これにより、エンジン２の過渡的な運転においても、適切に排気の再循環量を制御できる。 When the Rankine cycle operation is not performed, that is, when the operation range shown in FIGS. 2A and 2B is not satisfied, the ratio of the internal EGR is increased. This is because, as described above, the internal EGR can adjust the recirculation amount only by controlling the valve opening, and therefore has an advantage that the recirculation amount can be controlled with good response. Thus, the exhaust gas recirculation amount can be appropriately controlled even in the transient operation of the engine 2.
　図４Ａ－図４Ｃは、本発明の第１実施形態のランキンサイクルにおける車速と熱交換と関係の説明図である。 4A to 4C are explanatory diagrams of the relationship between the vehicle speed and the heat exchange in the Rankine cycle of the first embodiment of the present invention.
　図４Ａは、熱交換機２３において媒体が受熱する熱容量とランキンサイクルを運転したときの燃費効果との比を車速に対する関係を示す。図４Ａに示すように、車速が大きいほど、熱交換機２３における受熱容量とランキンサイクルの運転による燃費効果との比が大きくなり、燃費効果が向上することが示されている。 FIG. 4A shows the relationship between the heat capacity received by the medium in the heat exchanger 23 and the fuel efficiency when the Rankine cycle is operated, with respect to the vehicle speed. As shown in FIG. 4A, it is shown that as the vehicle speed increases, the ratio between the heat receiving capacity in the heat exchanger 23 and the fuel efficiency effect due to Rankine cycle operation increases, and the fuel efficiency effect improves.
　図４Ｂ及び図４Ｃは、車速に対する、内部ＥＧＲに対する外部ＥＧＲの比率の関係と、凝縮機４４における放熱能力（媒体を冷却する能力）の関係を示す。車速が高ければ走行風が大きくなり、凝縮機４４における放熱能力も向上する。これに伴って、ランキンサイクルの運転によりＥＧＲ２０における排気の冷却効果も向上する。そこで、図３で前述したように、車速が大きいほど内部ＥＧＲに対する外部ＥＧＲの比率を大きくすることにより、燃費効率を向上することができる。 4B and 4C show the relationship between the vehicle speed and the ratio of the external EGR to the internal EGR, and the relationship between the heat dissipation capability (capacity of cooling the medium) in the condenser 44. If the vehicle speed is high, the traveling wind becomes large, and the heat dissipation capability in the condenser 44 is also improved. Accordingly, the cooling effect of the exhaust gas in the EGR 20 is also improved by the operation of the Rankine cycle. Therefore, as described above with reference to FIG. 3, the fuel efficiency can be improved by increasing the ratio of the external EGR to the internal EGR as the vehicle speed increases.
　図５は、本発明の第１実施形態のランキンサイクルにおける冷却水温と燃費効果との関係を示す説明図である。 FIG. 5 is an explanatory diagram showing the relationship between the cooling water temperature and the fuel consumption effect in the Rankine cycle of the first embodiment of the present invention.
　冷却水水温が低い場合はエンジン２の暖機のために燃費効率は高くない。暖機が終わり、冷却水水温が上昇すると（７０～８０℃）、ＥＧＲ２０の熱交換機２３における排気の冷却によるによりエンジン２の燃費効率がやや向上する。 When the coolant temperature is low, the fuel efficiency is not high because the engine 2 is warmed up. When the warm-up is finished and the coolant temperature rises (70 to 80 ° C.), the fuel efficiency of the engine 2 is slightly improved by cooling the exhaust gas in the heat exchanger 23 of the EGR 20.
　そして、冷却水水温がランキンサイクルの運転域（８０～１００℃）となった場合は、ランキンサイクルが運転され、膨張機４３の回転によりエンジン２の駆動力をアシストするので、燃費効率は大きく向上する。冷却水水温がランキンサイクルの運転域を超えた場合は燃費効果が低下する。また、冷却水水温がさらに高くなった場合（１１０℃～）は、ＥＧＲ２０の排気が十分に冷却できなくなり、燃費効率は低下する。 When the coolant temperature reaches the Rankine cycle operating range (80 to 100 ° C.), the Rankine cycle is operated and the driving force of the engine 2 is assisted by the rotation of the expander 43, so the fuel efficiency is greatly improved. To do. If the cooling water temperature exceeds the Rankine cycle operating range, the fuel efficiency will decrease. Further, when the coolant temperature becomes higher (from 110 ° C.), the exhaust of the EGR 20 cannot be sufficiently cooled, and the fuel efficiency is lowered.
　図６は、本発明の第１実施形態のコントローラ３０が実行するランキンサイクル運転の制御を示すフローチャートである。 FIG. 6 is a flowchart showing the Rankine cycle operation control executed by the controller 30 according to the first embodiment of the present invention.
　コントローラ３０は、車速ＶＳＰ、冷却水水温を常に取得している（ステップＳ１０）。 The controller 30 always acquires the vehicle speed VSP and the coolant temperature (step S10).
　コントローラ３０は、これら水温、冷却水温度に基づいて、図２Ａ及び図２Ｂに示すマップを参照してランキンサイクルシステムの運転領域か否かを判定する（ステップＳ２０）。 The controller 30 determines whether or not the operation region of the Rankine cycle system is based on the water temperature and the cooling water temperature with reference to the maps shown in FIGS. 2A and 2B (step S20).
　ランキンサイクルシステムの運転領域は、言い換えると、凝縮機４４により媒体が冷却される冷却効率により決定される。すなわち、熱交換機２３で媒体が回収する熱と、凝縮機４４により媒体が冷却するときの熱との差により、ランキンサイクルシステムを運転したとき、燃費効率が大きくなる（エンジン２の駆動力をアシストできる）場合を、ランキンサイクルシステムの運転領域とする。車速が高い場合にも凝縮機４４の冷却効率が大きくなるので、ランキンサイクルシステムの運転領域とする。冷却水水温が高い場合にも、媒体の受熱量が大きくなるため、温度差が大きくなり、ランキンサイクルシステムの運転領域とする。 In other words, the operation region of the Rankine cycle system is determined by the cooling efficiency with which the medium is cooled by the condenser 44. That is, the fuel efficiency increases when the Rankine cycle system is operated due to the difference between the heat recovered by the medium in the heat exchanger 23 and the heat generated when the medium is cooled by the condenser 44 (assuming the driving force of the engine 2). If possible, this is the operating area of the Rankine cycle system. Since the cooling efficiency of the condenser 44 increases even when the vehicle speed is high, the operation region of the Rankine cycle system is set. Even when the cooling water temperature is high, the amount of heat received by the medium increases, so the temperature difference increases, and the operation region of the Rankine cycle system is set.
　ランキンサイクルシステムの運転領域であると判定した場合は、ステップＳ３０に移行して、コントローラ３０は、外部ＥＧＲによる排気の再循環量（第２の再循環量）を増加させ、内部ＥＧＲによる排気の再循環量（第１の再循環量）を減少させる。これにより、内部ＥＧＲに対する外部ＥＧＲの比率を高くする。 When it is determined that the operation region is in the Rankine cycle system, the process proceeds to step S30, where the controller 30 increases the exhaust gas recirculation amount (second recirculation amount) by the external EGR, and the exhaust gas by the internal EGR. The recirculation amount (first recirculation amount) is decreased. Thereby, the ratio of the external EGR to the internal EGR is increased.
　より具体的には、コントローラ３０は、外部ＥＧＲにおいては、ＥＧＲバルブ２２の開度を制御して、ＥＧＲ通路２１を通過する排気の量を増大させる。コントローラ３０は、内部ＥＧＲにおいて、可変バルブタイミング機構３１を制御して、吸気バルブ２ａを開くタイミングと排気バルブ２ｂを閉じるタイミングとのオーバーラップ期間を縮小させて、気筒内での排気の再循環量を減少させる。より具体的には、コントローラ３０は、吸気バルブ２ａを開くタイミングと排気バルブ２ｂを閉じるタイミングとを、共に上死点に近づけることにより排気の再循環量を減少させる。このような制御によって再循環される排気の比率を変更することができる。 More specifically, the controller 30 increases the amount of exhaust gas that passes through the EGR passage 21 by controlling the opening degree of the EGR valve 22 in the external EGR. In the internal EGR, the controller 30 controls the variable valve timing mechanism 31 to reduce the overlap period between the opening timing of the intake valve 2a and the closing timing of the exhaust valve 2b, and the recirculation amount of the exhaust gas in the cylinder. Decrease. More specifically, the controller 30 decreases the exhaust gas recirculation amount by bringing the timing at which the intake valve 2a is opened and the timing at which the exhaust valve 2b are closed closer to top dead center. The ratio of the exhaust gas recirculated can be changed by such control.
　このような制御により、気筒内に再循環する排気の上限値を超えない範囲において、内部ＥＧＲによる排気の再循環量よりも外部ＥＧＲによる排気の再循環量の比率を大きくする。 By such control, the ratio of the exhaust gas recirculation amount by the external EGR is made larger than the exhaust gas recirculation amount by the internal EGR within a range not exceeding the upper limit value of the exhaust gas recirculated in the cylinder.
　ランキンサイクルシステムの運転領域でないと判定した場合は、ステップＳ４０に移行して、コントローラ３０は、外部ＥＧＲによる排気の再循環量（第２の再循環量）を減少させ、内部ＥＧＲによる排気の再循環量（第１の再循環量）を増加させる。これにより、内部ＥＧＲに対する外部ＥＧＲの比率を低くする。 If it is determined that it is not in the operating region of the Rankine cycle system, the process proceeds to step S40, where the controller 30 decreases the exhaust gas recirculation amount (second recirculation amount) by the external EGR, and recirculates the exhaust gas by the internal EGR. The circulation amount (first recirculation amount) is increased. Thereby, the ratio of the external EGR to the internal EGR is lowered.
　より具体的には、コントローラ３０は、外部ＥＧＲにおいては、ＥＧＲバルブ２２の開度を制御して、ＥＧＲ通路２１を通過する排気の量を減少させる。また、コントローラ３０は、内部ＥＧＲにおいて、可変バルブタイミング機構３１を制御して、吸気バルブ２ａを開くタイミングと排気バルブ２ｂを閉じるタイミングとのオーバーラップ期間を拡大させて、気筒内での排気の再循環量を増加させる。より具体的には、コントローラ３０は、吸気バルブ２ａを開くタイミングを進角させ、排気バルブ２ｂを閉じるタイミング遅角させることで、排気の再循環量を増加させる。このような制御によって再循環される排気の比率を変更することができる。 More specifically, in the external EGR, the controller 30 controls the opening degree of the EGR valve 22 to reduce the amount of exhaust gas passing through the EGR passage 21. In addition, the controller 30 controls the variable valve timing mechanism 31 in the internal EGR to expand the overlap period between the timing of opening the intake valve 2a and the timing of closing the exhaust valve 2b, thereby re-exhaust gas in the cylinder. Increase circulation. More specifically, the controller 30 increases the exhaust gas recirculation amount by advancing the timing of opening the intake valve 2a and delaying the timing of closing the exhaust valve 2b. The ratio of the exhaust gas recirculated can be changed by such control.
　これらステップＳ３０またはステップＳ４０の処理の後、ステップＳ１０以降の処理を繰り返す。 After the process of step S30 or step S40, the process after step S10 is repeated.
　以上のように本発明の第１の実施形態のランキンサイクルシステム１は、熱交換機２３（排熱回収機）で冷却水により回収された熱を蒸発機４２及び加熱機４１で媒体に伝える。媒体の熱により膨張機４３を回転駆動させてエンジン２の駆動力をアシストするように構成されている。 As described above, in the Rankine cycle system 1 according to the first embodiment of the present invention, the heat recovered by the cooling water in the heat exchanger 23 (exhaust heat recovery device) is transmitted to the medium by the evaporator 42 and the heater 41. The expander 43 is rotationally driven by the heat of the medium to assist the driving force of the engine 2.
　そして、熱により膨張機４３を回転駆動させてエンジン２の駆動力をアシストする場合は、コントローラ３０は、内部ＥＧＲによる第１の再循環量よりも外部ＥＧＲによる第２の再循環量の比率を増加させるように制御を行う。 And when rotating the expander 43 by heat and assisting the driving force of the engine 2, the controller 30 sets the ratio of the second recirculation amount by the external EGR to the first recirculation amount by the internal EGR. Control to increase.
　このような制御によって、外部ＥＧＲにより吸気側に再循環される排気を増加させて、排気の熱を回収すると共に、再循環される排気の温度を下げることができる。これにより、エンジン２の排熱を回収することによる燃費効率の向上と、再循環される排気の温度を下げることによる燃費効率の向上とが行えるようになる。 By such control, the exhaust gas recirculated to the intake side by the external EGR can be increased to recover the heat of the exhaust gas and to reduce the temperature of the recirculated exhaust gas. As a result, the fuel efficiency can be improved by collecting the exhaust heat of the engine 2 and the fuel efficiency can be improved by lowering the temperature of the recirculated exhaust gas.
　前述のステップＳ３０において、内部ＥＧＲよりも外部ＥＧＲによる排気の再循環量の比率を大きくする場合に、気筒内に再循環する排気の上限値よりも排気の再循環の総量（内部ＥＧＲと外部ＥＧＲとの合計）を少なくしてもよい。これにより燃焼安定度を向上させて、車両の振動を抑制しつつ、燃費を向上することができる。 In the aforementioned step S30, when the ratio of the exhaust gas recirculation amount by the external EGR is made larger than the internal EGR, the total exhaust gas recirculation amount (the internal EGR and the external EGR) than the upper limit value of the exhaust gas recirculated in the cylinder. And the total). Thereby, the combustion stability can be improved, and the fuel consumption can be improved while suppressing the vibration of the vehicle.
　＜第２実施形態＞
　図７は、本発明の第２実施形態のエンジン２を中心としたランキンサイクルシステム１の構成を示す説明図である。 Second Embodiment
FIG. 7 is an explanatory diagram showing the configuration of the Rankine cycle system 1 centering on the engine 2 according to the second embodiment of the present invention.
　第２実施形態の実施形態は第１の実施形態の変形例であり、ランキンサイクル冷媒を、ＥＧＲ２０の熱交換機２３に直接導入して、ＥＧＲ２０の排気と冷媒とで熱交換を行うように構成した。その他の構成及びコントローラ３０の動作は第１の実施形態と同様である。 The embodiment of the second embodiment is a modification of the first embodiment, in which Rankine cycle refrigerant is directly introduced into the heat exchanger 23 of the EGR 20 and heat exchange is performed between the exhaust of the EGR 20 and the refrigerant. . Other configurations and the operation of the controller 30 are the same as those in the first embodiment.
　図７のように構成することによって、ランキンサイクルにおける冷媒の受熱量が高まるので、ランキンサイクルにおける温度差を大きくできる。この結果、ランキンサイクルをより高効率に運転することができ、エンジンの燃費効率を向上することができる。ＥＧＲ２０の排気は数百度に達するため、熱に影響を受けない適切な冷媒を選定する必要がある。 7, the amount of heat received by the refrigerant in the Rankine cycle increases, so that the temperature difference in the Rankine cycle can be increased. As a result, the Rankine cycle can be operated with higher efficiency, and the fuel efficiency of the engine can be improved. Since the exhaust gas of the EGR 20 reaches several hundred degrees, it is necessary to select an appropriate refrigerant that is not affected by heat.
　＜第３実施形態＞
　図８は、本発明の第３実施形態のエンジン２を中心としたランキンサイクルシステム１の構成を示す説明図である。 <Third Embodiment>
FIG. 8 is an explanatory diagram showing the configuration of the Rankine cycle system 1 centering on the engine 2 according to the third embodiment of the present invention.
　第３の実施形態は第１の実施形態の変形例であり、ランキンサイクルシステム１の凝縮機４４の代わりに、別に冷却回路５０と熱交換機５１とを設け、冷却回路５０によってランキンサイクル冷媒を冷却するように構成した。その他の構成及びコントローラ３０の動作は第１の実施形態と同様である。 The third embodiment is a modification of the first embodiment. Instead of the condenser 44 of the Rankine cycle system 1, a cooling circuit 50 and a heat exchanger 51 are provided separately, and the Rankine cycle refrigerant is cooled by the cooling circuit 50. Configured to do. Other configurations and the operation of the controller 30 are the same as those in the first embodiment.
　冷却回路５０は、冷却回路配管５５に、冷媒を循環させるポンプ５２、ランキンサイクル冷媒と熱交換を行う熱交換機５１、大気と熱交換を行うことで冷媒を冷却するサブラジエタ５３が備えられている。冷却回路５０には、車両に搭載される電子機器など（モータＭＯＴ、インバータＩＮＶ、インタークーラーＣＡＣ等）の冷却を行うことができるように構成されている。 The cooling circuit 50 includes a pump 52 for circulating the refrigerant, a heat exchanger 51 for exchanging heat with the Rankine cycle refrigerant, and a sub-radiator 53 for cooling the refrigerant by exchanging heat with the atmosphere. The cooling circuit 50 is configured to be able to cool electronic devices (motor MOT, inverter INV, intercooler CAC, etc.) mounted on the vehicle.
　このように、冷却回路５０をさらに設け、熱交換機５１において大気で直列冷却させるよりも変動の少ない冷媒によってランキンサイクルを冷却することにより、特に車速変動時のランキンサイクルにおける高温と低温との差を大きくでき。この結果、ランキンサイクルをより高効率に運転することができ、エンジンの燃費効率を向上することができる。 In this way, the cooling circuit 50 is further provided, and the Rankine cycle is cooled by the refrigerant that has less fluctuation than the series cooling in the air in the heat exchanger 51, so that the difference between the high temperature and the low temperature particularly in the Rankine cycle when the vehicle speed fluctuates. Can be bigger. As a result, the Rankine cycle can be operated with higher efficiency, and the fuel efficiency of the engine can be improved.
　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主旨ではない。 As mentioned above, although embodiment of this invention was described, the said embodiment showed only a part of application example of this invention, and it is the main point which limits the technical scope of this invention to the specific structure of the said embodiment. Absent.
　本願は、２０１２年１２月２７日に日本国特許庁に出願された特願２０１２－２８５８４９に基づく優先権を主張する。この出願のすべての内容は参照により本明細書に組み込まれる。
  The present application claims priority based on Japanese Patent Application No. 2012-285849 filed with the Japan Patent Office on December 27, 2012. The entire contents of this application are incorporated herein by reference.

Claims (8)

  1. 　車両のエンジンの排熱を回収してエネルギとして回生する排熱回収装置であって、
    　前記エンジンの排気の一部を吸気側に再循環する排気再循環通路と、
    　前記再循環される排気の量を制御する再循環弁と、
    　前記排気再循環通路の排熱を回収する排熱回収機と、
    　前記排熱回収機により回収された熱により回転駆動可能な膨張機と、
    　前記エンジン、前記再循環弁及び前記膨張機の動作を制御する制御装置と、
    を備え、
    　前記制御装置は、
    　前記エンジンの吸気バルブと排気バルブとのタイミングを制御して排気を第１の再循環量で再循環させる内部ＥＧＲ制御と、前記再循環弁を制御して排気を第２の再循環量で再循環させる外部ＥＧＲ制御と、を実行し、
    　前記排熱回収機により回収された熱により前記膨張機を回転駆動させる場合は、前記第１の再循環量よりも、前記第２の再循環量の比率を増加させる排熱回収装置。     An exhaust heat recovery device that recovers exhaust heat from a vehicle engine and regenerates it as energy,
    An exhaust gas recirculation passage for recirculating a part of the exhaust of the engine to the intake side;
    A recirculation valve for controlling the amount of exhaust gas recirculated;
    An exhaust heat recovery machine for recovering exhaust heat from the exhaust gas recirculation passage;
    An expander that can be rotationally driven by the heat recovered by the exhaust heat recovery machine;
    A control device for controlling the operation of the engine, the recirculation valve and the expander;
    With
    The control device includes:
    Internal EGR control for controlling the timing of the intake valve and the exhaust valve of the engine to recirculate the exhaust gas with a first recirculation amount; and controlling the recirculation valve to recirculate the exhaust gas with a second recirculation amount. Execute external EGR control to circulate,
    When the expander is rotationally driven by the heat recovered by the exhaust heat recovery machine, the exhaust heat recovery apparatus increases the ratio of the second recirculation amount to the first recirculation amount.
  2. 　請求項１に記載の排熱回収装置であって、
    　熱を媒介する媒体を冷却する凝縮機を備え、
    　前記膨張機は、熱を回収した前記媒体により回転駆動され、
    　前記制御装置は、前記媒体により回収された熱により前記膨張機を回転駆動させる場合は、前記凝縮機における前記媒体の冷却効率が所定効率よりも大きいときに、前記第２の再循環量の比率を増加させる排熱回収装置。     The exhaust heat recovery apparatus according to claim 1,
    With a condenser that cools the medium that carries heat,
    The expander is rotationally driven by the medium that has recovered heat,
    When the controller rotates the expander with the heat recovered by the medium, the ratio of the second recirculation amount when the cooling efficiency of the medium in the condenser is larger than a predetermined efficiency. Increases exhaust heat recovery device.
  3. 　請求項１又は２に記載の排熱回収装置であって、
    　前記制御装置は、前記排熱回収機により回収された熱により前記膨張機を回転駆動させる場合は、車両の車速が所定車速よりも高いときに、前記第２の再循環量の比率を増加させる排熱回収装置。     The exhaust heat recovery apparatus according to claim 1 or 2,
    When the expansion device is rotationally driven by the heat recovered by the exhaust heat recovery device, the control device increases the ratio of the second recirculation amount when the vehicle speed of the vehicle is higher than a predetermined vehicle speed. Waste heat recovery device.
  4. 　請求項１から３のいずれか一つの記載の排熱回収装置であって、
    　前記排熱回収機は前記エンジンの冷却水により熱を回収し、
    　前記膨張機は前記冷却水により回収された熱を用いて回転駆動され、
    　前記制御装置は、前記エンジンの水温温度が所定水温よりも高い場合に、前記回収された熱により前記膨張機を回転駆動させる排熱回収装置。     The exhaust heat recovery apparatus according to any one of claims 1 to 3,
    The exhaust heat recovery machine recovers heat by the engine cooling water,
    The expander is rotationally driven using heat recovered by the cooling water,
    The control device is an exhaust heat recovery device that rotationally drives the expander with the recovered heat when the water temperature of the engine is higher than a predetermined water temperature.
  5. 　請求項１から４のいずれか一つに記載の排熱回収装置であって、
    　前記制御装置は、
    　前記排熱回収機により回収された熱により前記膨張機を回転駆動させる場合は、
    　前記外部ＥＧＲ制御において、前記再循環弁の弁開度を拡大して第２の再循環量を増大させると共に、
    　前記内部ＥＧＲ制御において、前記エンジンの吸気バルブと排気バルブとのオーバーラップ期間を縮小して第１の再循環量を減少させて、
    　前記第１の再循環量よりも前記第２の再循環量の比率を増加させる排熱回収装置。     The exhaust heat recovery device according to any one of claims 1 to 4,
    The control device includes:
    When rotating the expander by heat recovered by the exhaust heat recovery machine,
    In the external EGR control, the valve opening of the recirculation valve is increased to increase the second recirculation amount,
    In the internal EGR control, the overlap period between the intake valve and the exhaust valve of the engine is reduced to reduce the first recirculation amount,
    An exhaust heat recovery apparatus that increases a ratio of the second recirculation amount to the first recirculation amount.
  6. 　請求項１から４のいずれか一つに記載の排熱回収装置であって、
    　前記制御装置は、
    　前記排熱回収機により回収された熱により前記膨張機を回転駆動させる場合は、
    　前記外部ＥＧＲ制御において、前記再循環弁の弁開度を拡大して第２の再循環量を増大させると共に、
    　前記内部ＥＧＲ制御において、前記エンジンの吸気バルブを開くタイミングと、前記エンジンの排気バルブを閉じるタイミングとを、共に上死点に近づけることにより第１の再循環量を減少させて、
    　前記第１の再循環量よりも前記第２の再循環量の比率を増加させる排熱回収装置。     The exhaust heat recovery device according to any one of claims 1 to 4,
    The control device includes:
    When rotating the expander by heat recovered by the exhaust heat recovery machine,
    In the external EGR control, the valve opening of the recirculation valve is increased to increase the second recirculation amount,
    In the internal EGR control, the first recirculation amount is reduced by bringing the timing of opening the intake valve of the engine and the timing of closing the exhaust valve of the engine close to top dead center,
    An exhaust heat recovery apparatus that increases a ratio of the second recirculation amount to the first recirculation amount.
  7. 　請求項１から６のいずれか一つに記載の排熱回収装置であって、
    　前記制御装置は、
    　前記排熱回収機により回収された熱により前記膨張機を回転駆動させる場合は、前記膨張機を回転駆動させない場合と比較して、前記第１の再循環量と前記第２の再循環量との合計を同じか又は小さくする排熱回収装置。     The exhaust heat recovery apparatus according to any one of claims 1 to 6,
    The control device includes:
    When the expander is rotationally driven by the heat recovered by the exhaust heat recovery machine, the first recirculation amount and the second recirculation amount are compared with the case where the expander is not rotationally driven. Waste heat recovery device that makes the total of the same or smaller.
  8. 　車両のエンジンの排気の一部を吸気側に再循環する排気再循環通路と、前記再循環される排気の量を制御する再循環弁と、前記排気再循環通路の排熱を回収する排熱回収機と、前記排熱回収機により回収された熱により回転駆動可能な膨張機と、前記エンジン、前記再循環弁及び前記膨張機の動作を制御する制御装置と、を備え、エンジンの排熱を回収してエネルギとして回生する排熱回収装置の排熱回収方法であって、
    　前記エンジンの吸気バルブと排気バルブとのタイミングを制御して排気を第１の再循環量で再循環させる内部ＥＧＲ制御と、前記再循環弁を制御して排気を第２の再循環量で再循環させる外部ＥＧＲ制御と、を実行すると共に、
    　前記排熱回収機により回収された熱により前記膨張機を回転駆動させる場合は、前記第１の再循環量よりも、前記第２の再循環量の比率を増加させる排熱回収方法。
          An exhaust gas recirculation passage that recirculates part of the exhaust of a vehicle engine to the intake side, a recirculation valve that controls the amount of exhaust gas that is recirculated, and exhaust heat that recovers exhaust heat from the exhaust gas recirculation passage A recovery device, an expander that can be rotationally driven by the heat recovered by the exhaust heat recovery device, and a control device that controls the operation of the engine, the recirculation valve, and the expander, the exhaust heat of the engine Is an exhaust heat recovery method of an exhaust heat recovery device that recovers and regenerates as energy,
    Internal EGR control for controlling the timing of the intake valve and the exhaust valve of the engine to recirculate the exhaust gas with a first recirculation amount; and controlling the recirculation valve to recirculate the exhaust gas with a second recirculation amount. And executing external EGR control to circulate,
    An exhaust heat recovery method for increasing a ratio of the second recirculation amount to the first recirculation amount when the expander is rotationally driven by the heat recovered by the exhaust heat recovery device.
PCT/JP2013/083866 2012-12-27 2013-12-18 Exhaust-heat-recovery device and exhaust-heat-recovery method WO2014103824A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2012-285849 2012-12-27
JP2012285849A JP2015232274A (en) 2012-12-27 2012-12-27 Exhaust heat recovery system

Publications (1)

Publication Number Publication Date
WO2014103824A1 true WO2014103824A1 (en) 2014-07-03

Family

ID=51020911

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2013/083866 WO2014103824A1 (en) 2012-12-27 2013-12-18 Exhaust-heat-recovery device and exhaust-heat-recovery method

Country Status (2)

Country Link
JP (1) JP2015232274A (en)
WO (1) WO2014103824A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3057299A1 (en) * 2016-10-11 2018-04-13 Peugeot Citroen Automobiles Sa MOTORIZATION ASSEMBLY WITH RANKINE LOOP

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010242582A (en) * 2009-04-03 2010-10-28 Denso Corp Engine waste heat control apparatus
JP2012087687A (en) * 2010-10-20 2012-05-10 Mitsubishi Heavy Ind Ltd Torque fluctuation inhibiting control device and method for diesel engine
JP2012102619A (en) * 2010-11-08 2012-05-31 Hino Motors Ltd Waste heat recovery system

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010242582A (en) * 2009-04-03 2010-10-28 Denso Corp Engine waste heat control apparatus
JP2012087687A (en) * 2010-10-20 2012-05-10 Mitsubishi Heavy Ind Ltd Torque fluctuation inhibiting control device and method for diesel engine
JP2012102619A (en) * 2010-11-08 2012-05-31 Hino Motors Ltd Waste heat recovery system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3057299A1 (en) * 2016-10-11 2018-04-13 Peugeot Citroen Automobiles Sa MOTORIZATION ASSEMBLY WITH RANKINE LOOP
WO2018069587A1 (en) * 2016-10-11 2018-04-19 Psa Automobiles Sa Drive unit with rankine loop

Also Published As

Publication number Publication date
JP2015232274A (en) 2015-12-24

Similar Documents

Publication Publication Date Title
US10100690B2 (en) Method and system for exhaust emissions control
JP5481737B2 (en) Waste heat utilization device for internal combustion engine
JP4492672B2 (en) Control device for hybrid system
JP5293235B2 (en) Engine intake control method and apparatus
US20160003127A1 (en) Intake-air cooling device for engine and method for cooling engine
WO2013031287A1 (en) Waste heat utilization device
US20160230643A1 (en) Engine cooling system
KR20130081664A (en) Cooler arrangement for a vehicle powered by a supercharged combustion engine
JP2013181394A (en) Waste heat recovery device of engine
KR102648821B1 (en) Apparatus for controlling thermal energy for hybrid vehicle and method for controlling thermal energy thereof and hybrid vehicle including the same
CN109830783B (en) Whole vehicle heat management system based on college student electric formula car and control method thereof
JP2002161748A (en) Automobile electric water pumping device
RU2518764C1 (en) Device and method for heating of heat carrier circulating in cooling system
JP2019137279A (en) Hybrid vehicle
JP2019156108A (en) Temperature control device of vehicle
CN201074559Y (en) Heat-recovering mechanism for automobile internal combustion engine
WO2014132755A1 (en) Cooling device and cooling method for exhaust recirculation device
WO2014103824A1 (en) Exhaust-heat-recovery device and exhaust-heat-recovery method
CN101059108A (en) Vehicular internal combustion engine residual heat recovery and utilization mechanism and method
CN202672204U (en) Cooling system of hybrid power bulldozer
JP2012144205A (en) Hybrid vehicle and control device for internal combustion engine
JP2014234801A (en) Engine waste heat utilization device
JP2016014339A (en) Exhaust heat regeneration system
JP3329123B2 (en) Diesel engine intake temperature control system
CN107605580B (en) Automobile waste heat recovery and air conditioner refrigeration composite circulation system and control method thereof

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 13867365

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 13867365

Country of ref document: EP

Kind code of ref document: A1