WO2011146111A1 - Construction egr pour moteur à pistons opposés - Google Patents

Construction egr pour moteur à pistons opposés Download PDF

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Publication number
WO2011146111A1
WO2011146111A1 PCT/US2011/000864 US2011000864W WO2011146111A1 WO 2011146111 A1 WO2011146111 A1 WO 2011146111A1 US 2011000864 W US2011000864 W US 2011000864W WO 2011146111 A1 WO2011146111 A1 WO 2011146111A1
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WO
WIPO (PCT)
Prior art keywords
charge air
output
input
opposed
exhaust gas
Prior art date
Application number
PCT/US2011/000864
Other languages
English (en)
Inventor
Eric P. Dion
Iain J. L. Read
Fabien G. Redon
Gerhard Regner
Michael H. Wahl
Original Assignee
Achates Power, Inc.
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 Achates Power, Inc. filed Critical Achates Power, Inc.
Priority to JP2013511146A priority Critical patent/JP6117695B2/ja
Priority to US13/068,679 priority patent/US8549854B2/en
Priority to EP11721839.6A priority patent/EP2572089B1/fr
Priority to PCT/US2011/000864 priority patent/WO2011146111A1/fr
Priority to CN201180024717.4A priority patent/CN103026024B/zh
Publication of WO2011146111A1 publication Critical patent/WO2011146111A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B25/00—Engines characterised by using fresh charge for scavenging cylinders
    • F02B25/02—Engines characterised by using fresh charge for scavenging cylinders using unidirectional scavenging
    • F02B25/08—Engines with oppositely-moving reciprocating working pistons
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00—Other engines
    • F02B75/28—Engines with two or more pistons reciprocating within same cylinder or within essentially coaxial cylinders
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F1/00—Cylinders; Cylinder heads 
    • F02F1/18—Other cylinders
    • F02F1/186—Other cylinders for use in engines with two or more pistons reciprocating within same cylinder
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00—Other engines
    • F02B75/02—Engines characterised by their cycles, e.g. six-stroke
    • F02B2075/022—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle
    • F02B2075/025—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle two
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B2275/00—Other engines, components or details, not provided for in other groups of this subclass
    • F02B2275/14—Direct injection into combustion chamber

Definitions

  • the field is internal combustion engines.
  • the field relates to ported, uniflow-scavenged, opposed-piston engines with exhaust gas recirculation.
  • the field includes two-stroke, opposed-piston engines with one or more ported cylinders and uniflow scavenging in which an exhaust gas recirculation (EGR) construction provides a portion of the exhaust gasses produced by the engine for mixture with charge air to control the production of NOx during combustion.
  • EGR exhaust gas recirculation
  • an internal combustion engine is illustrated by way of an opposed-piston engine that includes at least one cylinder 10 with a bore 12 and longitudinally-displaced exhaust and intake ports 14 and 16 machined or formed therein.
  • Fuel injector nozzles 17 are located in or adjacent injector ports that open through the side of the cylinder, at or near the longitudinal center of the cylinder.
  • Two pistons 20, 22 are disposed in the bore 12 with their end surfaces 20e, 22e in opposition to each other.
  • the piston 20 is referred as the "exhaust” piston because of its proximity to the exhaust port 14; and, the end of the cylinder wherein the exhaust port is formed is referred to as the "exhaust end”.
  • the piston 22 is referred as the "intake” piston because of its proximity to the intake port 16, and the corresponding end of the cylinder is the "intake end”.
  • a phase offset is introduced into the piston movements.
  • the exhaust piston leads the intake piston and the phase offset causes the pistons to move around their BDC positions in a sequence in which the exhaust port 14 opens as the exhaust piston 20 moves through BDC while the intake port 16 is still closed so that combustion gasses start to flow out of the exhaust port 14.
  • the intake port 16 opens while the exhaust port 14 is still open and a charge of pressurized air ("charge air") is forced into the cylinder 10, driving exhaust gasses out of the exhaust port 14.
  • charge air pressurized air
  • the displacement of exhaust gas from the cylinder through the exhaust port while admitting charge air through the intake port is referred to as "scavenging”. Because the charge air entering the cylinder flows in the same direction as the outflow of exhaust gas (toward the exhaust port), the scavenging process is referred to as "uniflow scavenging”.
  • the exhaust port 14 is closed by the exhaust piston 20 and scavenging ceases.
  • the intake port 16 remains open while the intake piston 22 continues to move away from BDC.
  • TDC TDC
  • the intake port 16 is closed and the charge air in the cylinder is compressed between the end surfaces 20e and 22e.
  • the charge air is swirled as it passes through the intake port 16 to promote good scavenging while the ports are open and, after the ports close, to mix the air with the injected fuel.
  • the fuel is diesel which is injected into the cylinder by high pressure injectors.
  • the swirling air (or simply, "swirl") 30 has a generally helical motion that forms a vortex in the bore which circulates around the longitudinal axis of the cylinder.
  • fuel 40 is injected through the nozzles 17 directly into the swirling charge air 30 in the bore 12, between the end surfaces 20e, 22e of the pistons.
  • the swirling mixture of charge air and fuel is compressed in a combustion chamber 32 defined between the end surfaces 20e and 22e when the pistons 20 and 22 are near their respective TDC locations.
  • the fuel ignites in the combustion chamber, driving the pistons apart toward their respective BDC locations.
  • a solution to the problem is to reduce the NOx emissions of a two-stroke opposed-piston engine with uniflow scavenging by exhaust gas recirculation through one or more ported cylinders of the engine.
  • the engine includes at least one cylinder with piston-controlled exhaust and intake ports and a charge air channel to provide charge air to at least one intake port of the engine.
  • EGR is provided by an EGR loop having an input coupled to an exhaust port of the cylinder and a loop output coupled to the charge air channel.
  • a pressure differential provided between the exhaust gas and the charge air channel causes the exhaust gas to flow through the EGR loop to the charge air channel where exhaust gas and air are mixed and provided to the at least one intake port.
  • EGR is provided by retention of residual exhaust gasses in the ported cylinder when scavenging ceases.
  • FIG. 1 is a side sectional partially schematic drawing of a cylinder of a prior art opposed-piston engine with opposed pistons near respective bottom dead center locations, and is appropriately labeled "Prior Art”.
  • FIG. 2 is a side sectional partially schematic drawing of the cylinder of FIG. 1 with the opposed pistons near respective top dead center locations where end surfaces of the pistons define a combustion chamber, and is appropriately labeled "Prior Art”.
  • FIG. 3 is a conceptual schematic diagram of an internal combustion engine of the opposed-piston type in which aspects of an air management system with EGR are illustrated.
  • FIG. 4 is a conceptual schematic drawing illustrating preferred constructions for EGR in the ported, uniflow scavenging, internal combustion engine of FIG. 3.
  • FIG. 5 is a schematic drawing of a preferred EGR construction for the ported, uniflow scavenging, internal combustion engine of FIG. 3.
  • FIG. 6 is a schematic drawing of an alternate EGR construction for a ported, uniflow scavenging, opposed-piston engine without a turbocharger.
  • EGR constructions described in this specification are presented in an explanatory context that includes a ported, uniflow-scavenging internal combustion engine having at least one cylinder in which a pair of pistons is disposed with their end surfaces in opposition.
  • a "ported" cylinder includes one or more of intake and exhaust ports formed or machined in a sidewall thereof.
  • an internal combustion engine 49 is embodied by an opposed- piston engine having at least one ported cylinder 50.
  • the engine may have one ported cylinder, two ported cylinders, three ported cylinders, or four or more ported cylinders.
  • the engine is an engine of the opposed-piston type that is presumed to have a plurality of ported cylinders.
  • each cylinder 50 has a bore 52 and exhaust and intake ports 54 and 56 formed or machined in respective ends thereof.
  • the exhaust and intake ports 54 and 56 each include one or more circumferential arrays of openings in which adjacent openings are separated by a solid bridge.
  • each opening is referred to as a "port”; however, the construction of a circumferential array of such "ports” is no different than the port constructions shown in FIG. 3.
  • Exhaust and intake pistons 60 and 62 are slidably disposed in the bore 52 with their end surfaces 61 and 63 opposing one another.
  • the exhaust pistons 60 are coupled to a crankshaft 71
  • the intake pistons are coupled to the crankshaft 72.
  • a combustion chamber is defined in the bore 52 between the end surfaces 61 and 63 of the pistons. Fuel is injected directly into the combustion chamber through at least one fuel injector nozzle 100 positioned in an opening through the sidewall of a cylinder 50.
  • the engine 49 includes an air management system 51 that manages the transport of charge air provided to, and exhaust gas produced by, the engine 49.
  • a representative air management system construction includes a charge air subsystem and an exhaust subsystem.
  • the charge air subsystem includes a charge air source that receives intake air and processes it into charge air, a charge air channel coupled to the charge air source through which charge air is transported to the at least one intake port of the engine, and at least one air cooler in the charge air channel that is coupled to receive and cool the charge air (or a mixture of gasses including charge air) before delivery to the intake port or ports of the engine.
  • a cooler can comprise an air-to-liquid and/or an air-to-air device, or another cooling device.
  • the charge air subsystem also includes a supercharger that pumps charge air in the charge air channel to intake ports of the engine.
  • the exhaust subsystem includes an exhaust channel that transports exhaust products from exhaust ports of the engine to an exhaust pipe.
  • the preferred charge air subsystem includes a supercharger 1 10, which can be driven by an electrical motor, or by a gear, chain, or belt apparatus coupled to a crankshaft.
  • the supercharger 1 10 is coupled by a belt linkage to the crankshaft 72 to be driven thereby.
  • the supercharger 1 10 can be a single-speed or multiple-speed device, or a fully variable-speed device.
  • the air management system 51 includes a turbo-charger 120 with a turbine 121 and a compressor that rotate on a common shaft 123.
  • the turbine 121 is coupled to the exhaust subsystem and the compressor 122 is coupled to the charge air subsystem.
  • the turbine 121 can be a fixed-geometry or a variable-geometry device.
  • the turbo- charger 120 extracts energy from exhaust gas that exits the exhaust ports 54 and flows into the exhaust channel 124 directly from the exhaust ports 54, or from an exhaust manifold 125.
  • the turbine 121 is rotated by exhaust gas passing through it. This rotates the compressor 122, causing it to generate charge air by compressing intake air.
  • the charge air output by the compressor 122 flows through a conduit 126 to a charge air cooler 127, whence it is pumped by the supercharger 10 to the intake ports.
  • Air compressed by the supercharger 1 10 is output from the supercharger through a charge air cooler 129 to an intake manifold 130.
  • the intake ports 56 receive charge air pumped by the supercharger 1 10, through the intake manifold 130.
  • the intake manifold 130 is constituted of an intake plenum that communicates with the intake ports 56 of all cylinders 50.
  • Exhaust Gas Management It is desirable to modify or adapt an air management construction for an internal combustion engine of the ported-cylinder type in order to reduce NOx emissions produced by combustion. It is particularly desirable to control such emissions by recirculating exhaust gas through the ported cylinders of an opposed-piston engine. The recirculated exhaust gas is mixed with charge air to lower peak combustion temperatures, which lowers NOx emissions. This process is referred to as exhaust gas recirculation ("EGR").
  • EGR exhaust gas recirculation
  • An EGR construction can utilize exhaust gasses transported in an EGR channel external to the cylinder into the incoming stream of fresh intake air as per the valve-controlled recirculation channel 131 in FIG. 3.
  • an EGR process can utilize residual exhaust gasses that are retained in the cylinders 50 when scavenging ceases.
  • the exhaust gas is pumped into the inflowing stream of air.
  • a source of pressure in communication with the EGR channel creates a pressure differential that causes exhaust gas to flow through the EGR channel into the charge air subsystem.
  • a virtual pump exists when the exhaust gas to be recirculated is obtained from a source guaranteed to be at a higher pressure than the point where it is fed into the intake stream of charge air.
  • an active pump such as the supercharger 1 10 is used to pump the exhaust gas to be recirculated into the charge air that the supercharger is pumping to the intake ports.
  • use of a supercharger provides an additional variable for controlling EGR operations in an opposed-piston engine.
  • recirculated exhaust gas is cooled by way of one or more EGR coolers, which can comprise air-to-liquid and/or air-to-air devices.
  • recirculated exhaust gas is cooled by one or more charge air coolers alone or in combination with one or more EGR coolers.
  • First EGR loop construction In some aspects, the internal combustion engine seen in FIG. 3 includes a first EGR loop construction.
  • a first EGR loop construction for a uniflow scavenging, ported, opposed-piston application circulates exhaust gas from any source of exhaust gas exiting from one or more cylinders.
  • the first EGR loop construction includes an EGR port 55 positioned inboard of exhaust port 54; that is to say, the EGR port 55 is positioned between the exhaust port 54 and the longitudinal midpoint of the cylinder 50.
  • the EGR port construction includes one or more port openings as needed by any particular design.
  • the exhaust piston 60 moves past the EGR port 55, opening the EGR port to a cylinder bore pressure that is guaranteed to be higher than the pressure in the intake manifold 130.
  • This pressure differential pumps a portion of exhaust gas from the EGR port 55 through a plenum or manifold (not shown) into a conduit 133 controlled by a one-way check valve 134, and then into the intake manifold 130 where it is mixed with the charge air and recirculated therewith into the cylinder bore.
  • the exhaust gas enters the charge air output by the supercharger 1 10 prior to the inlet of the charge air cooler 129.
  • the ratio of the cylinder pressure when the EGR port opens (“EGR open”) to the intake manifold pressure not exceed a threshold value beyond which choked flow conditions may occur in the one-way check valve 134.
  • This pressure ratio is affected by the size of the EGR port and its location with respect to the longitudinal center of the cylinder (the closer to the center, the higher the pressure) as well as the state of the air charge system (boost, turbine back pressure, etc.).
  • the exhaust gas flowing in the conduit 133 is mixed with charge air output by the supercharger 110 through a mixer 135 that can be constituted, for example, as a venturi.
  • the exhaust gas is input to the mixer 135 through a valve 136; pressurized charge air output by the supercharger 1 10 is provided to a mixing input of the mixer 135.
  • the mixture of pressurized charge air and exhaust gas produced by the mixer 135 is provided to the input of the charge air cooler 29 (or, alternately, to the input of the charge air cooler 127).
  • the valve 136 is operated by a signal output by an engine control unit (ECU) 149.
  • ECU engine control unit
  • an accumulator 145 is provided in the first loop in series between the EGR port 55 and the input to the valve 136.
  • an EGR cooler 146 is provided in the first loop in series between the check valve 134 and the input to the valve 136.
  • the loop construction can be 134, 136, 146.
  • Second EGR loop construction In some aspects, the internal combustion engine 49 seen in FIG. 3 can include another EGR loop construction.
  • a second EGR loop construction includes the conduit 131 and a valve 138 to shunt a portion of the exhaust gas from the exhaust manifold 54 to the input of a charge air cooler so that the portion is cooled.
  • the exhaust gas portion is shunted to the input of the charge air cooler 127.
  • This loop subjects the exhaust gas to the cooling effects of two charge air coolers (127 and 129).
  • the valve 138 can be constituted as a three-way valve (as best seen in FIG. 4), and the exhaust gas portion can be shunted around the cooler 127 to the input of the supercharger 1 10.
  • This alternative subjects the exhaust gas portion to cooling by only the charge air cooler 129.
  • a dedicated EGR cooler that cools only exhaust gas can be incorporated into the second loop, if needed.
  • an EGR cooler can be placed in the conduit 131 , in series with the valve 138, or in series with the output port of the valve 138 and the input to the supercharger 1 10.
  • the valve 138 is constituted as a single three-way device.
  • valve 138 is constituted as a pair of valves, each in a respective branch of a Y-connection from the conduit 131 , in which one valve controls the provision of exhaust gas to the input of the cooler 127 and the other controls the provision of exhaust gas to the input of the supercharger 1 10.
  • EGR using retained exhaust gas In a uniflow or loop-scavenged internal combustion engine, it is sometimes desirable to trap or retain a residual amount of exhaust gas in a cylinder after scavenging ceases.
  • the residual exhaust gas can be used to adjust the initial conditions for combustion to a point advantageous for reducing NOx emissions.
  • uniflow-scavenged engines may exhibit incomplete scavenging. Since the residual exhaust gas inside the cylinder is hot, the resulting temperature of the new charge of air may be substantially elevated, therefore this method is best suited for reducing NOx under partial engine load conditions.
  • the amount of charge air that is fed into a cylinder each cycle can be used to alter the amount of residual exhaust gas left in the cylinder.
  • adjusting the amount of charge air that is fed into the cylinder in any given cycle of operation can be used to "tune" the amount of exhaust gas retained in the cylinder for the next combustion occurrence.
  • a bypass conduit loop 148 including a valve 139 is placed in parallel with the supercharger 1 10. The valve 139 is operated to control the amount of charge air pumped into the engine by the supercharger 1 10.
  • backpressure An increase in the pressure felt by exhaust gas flowing to the turbine
  • backpressure can also be used to alter the amount of residual exhaust gas left in the cylinder.
  • adjusting the amount of backpressure in any given cycle of operation can be used to "tune" the amount of residual exhaust gas for the next combustion occurrence. Therefore, in another aspect of retained exhaust gas EGR, seen in FIG. 4, a variable valve 140 is placed in series with exhaust gas output. The setting of the valve 140 directly influences the backpressure felt upstream of the valve and, consequently, the amount of exhaust gas retained in any cylinder after scavenging. In FIG. 4, the valve 140 is placed in series with the output of the turbine 121.
  • an equivalent valve 140a can be placed in series between the input to the turbine 121 and an exhaust manifold that collects the exhaust output of one or more cylinders.
  • the equivalent valve 140a can be placed in series with an exhaust manifold or exhaust port of each of a plurality of cylinders.
  • Turbine bypass construction Referring again to FIG. 4, a bypass conduit loop 143 including a valve 144 is placed in parallel with the turbine 121. The valve 144 is operated to control the amount of exhaust gas flowing from the engine into the turbine 121. Setting the valve 144 to bypass the turbine 121 allows exhaust energy to be dumped into the exhaust pipe 128 without operating the turbine 121 and compressor 122. This keeps the exhaust gas at a higher temperature level and increases after-treatment conversion efficiencies (for particulate filters and catalytic devices, for example) at engine warm-up during partial engine load conditions such as from a cold start.
  • after-treatment conversion efficiencies for particulate filters and catalytic devices, for example
  • VGT variable geometry turbine
  • a VGT has only a limited mass flow range where it works at acceptable efficiencies. Outside this range, a turbine bypass valve can be used to control the mass flow and intake pressure of the engine 49.
  • Preferred EGR Embodiment A preferred EGR construction for a ported opposed-piston engine with uniflow scavenging is shown in FIG. 5.
  • exhaust gas flows from the exhaust port or ports 54 of the engine, through the conduit 124 to the turbine 121 , whence it passes through after-treatment conversion (not shown) and flows out the exhaust pipe 128.
  • After-treatment conversion not shown
  • a portion of the exhaust gas is shunted from the conduit 124 via 131 and from there through the valve 138' to the input of the charge air cooler 127 where it mixes with the incoming stream of fresh air.
  • the exhaust gas and air are mixed and cooled in the charge air cooler 127, and the cooled gas/air mixture is input to the supercharger 1 10.
  • the supercharger 110 compresses the gas/air mixture, and the compressed mixture is input to the charge air cooler 129.
  • the cooled, compressed mixture then enters the cylinder 50 via the intake port 56.
  • the intake throttle valve 141 and the turbine bypass valve 144 are included for high precision control of the ratio of recirculated exhaust gas to fresh air.
  • Exhaust configuration and control The EGR and turbine bypass constructions illustrated in FIGS. 4 and 5 can be implemented in a ported engine of the uniflow scavenging type singly, or in any combination of two or more constructions, or portions thereof, as required for a specific design.
  • One example is an EGR configuration in which uncooled exhaust gas retained in a cylinder following scavenging is combined or mixed with recirculated exhaust gas that is cooled and mixed with charge air provided to the cylinder.
  • the relative amounts of retained and recirculated exhaust gas can be varied in order to precisely control the EGR rate and temperature.
  • An intake throttle valve 141 can be placed in the stream of fresh air flowing into the compressor 122 in order to more precisely control the ratio of recirculated exhaust gas to fresh air. If implemented on a per-cylinder basis, a high- speed individual EGR and charge air/fuel trim is provided to correct cylinder-to- cylinder variations caused by flow dynamics and/or manufacturing tolerances.
  • An EGR control process for an EGR system that utilizes one or more of the constructions illustrated in FIGS. 4 and 5, or any combination thereof, is executed by the ECU 149 in response to specified engine operating conditions by automatically operating any one or more of the valves 136, 138, 139, 140, 140a, and 144, the intake throttle valve 141 , and the supercharger 110, if a multi-speed or variable speed device is used, and the turbo-charger 120, if a variable-geometry device is used.
  • operation of valves, throttles, and associated elements used for EGR can include any one or more of electrical, pneumatic, mechanical, and hydraulic actuating operations.
  • valves be high-speed, computer-controlled devices with continuously- variable settings.
  • Each valve has a first state in which it is open (to some setting controlled by the ECU 149) to allow gas to flow through it, and a second state in which it is closed to block gas from flowing through it.
  • an EGR control process automatically operates an EGR system incorporating one or more constructions described and illustrated herein based upon one or more parameters relating to recirculated exhaust gas and to a mixture of recirculated exhaust gas and charge air.
  • Parameter values are determined by a combination of one or more of sensors, calculations, and table lookup so as to manage the values of individual parameters and one or more ratios of EGR and mixture parameters in one or more cylinders.
  • Alternate EGR Embodiment An alternate EGR construction is shown in FIG. 6 in a two-stroke opposed-piston engine with ported cylinders and uniflow scavenging in which only a supercharger provides scavenging pressure.
  • emission control devices that include a diesel oxidation catalyst (DOC) to reduce CO and hydrocarbons, a diesel particulate filter (DPF) to reduce soot emissions and a selective catalytic reduction device to reduce NOx emissions. All of these devices require addition of heat for operation, and the absence of a turbocharger reduces the competition for heat derived from exhaust gas, while also lowering the power density of the engine.
  • DOC diesel oxidation catalyst
  • DPF diesel particulate filter
  • a selective catalytic reduction device to reduce NOx emissions. All of these devices require addition of heat for operation, and the absence of a turbocharger reduces the competition for heat derived from exhaust gas, while also lowering the power density of the engine.
  • the DPF and DOC now can be closely coupled at an exhaust manifold, where a turbocharger typically is mounted. Furthermore, elimination of a turbocharger and its required ducting reduces the size of the opposed-piston engine and also reduces the loss of exhaust heat by convection from the turbocharger housing and ducting.
  • exhaust gas for recirculation is extracted from the outlet of the DPF where it is free of particulates and can be cooled and plumbed to the inlet of the supercharger. Although the exhaust gas is cooler after the DPF, it can be cooled further with an EGR cooler.
  • the alternate EGR embodiment for a two-stroke, ported, uniflow- scavenging, opposed-piston engine is illustrated in FIG. 6.
  • the engine does not include a turbocharger.
  • Exhaust gas flows from the exhaust manifold 125, through the conduit 124, through the DOC 150 and the DPF 151 , then through the valve 140 and out the exhaust pipe 128.
  • a portion of the exhaust gas is diverted by a pressure change determined by the setting of the valve 140 into the input of an EGR cooler 142. Cooled exhaust gas output by the EGR cooler 142 is metered through a valve 147 into the air stream entering the supercharger 1 10.
  • the intake throttle valve 141 can be placed in the airstream flowing to the supercharger, upstream of the output of the valve 147, in order to more precisely control the ratio of recirculated exhaust gas to air by creating a slight vacuum. Since the alternate EGR loop is being drawn through the supercharger 1 10, the time needed to empty the exhaust gas from the charge air cooler 129 is much reduced, thereby improving the transient response. If the supercharger 1 10 is driven directly from the engine, it will achieve high flow and high speed together with the engine. The supercharger capacity enables the needed exhaust gas to be pumped as required at high engine speed and load as required to meet stringent emission requirements.
  • the supercharger bypass valve 139 permits the pressure produced by the supercharger to be continuously varied.
  • EGR constructions have been described with reference to a ported opposed engine construction with two crankshafts, it should be understood that various aspects of these constructions can be applied to opposed-piston engines with one or more crankshafts. Moreover, various aspects of these EGR constructions can be applied to opposed-piston engines with ported cylinders disposed in opposition, and/or on either side of one or more crankshafts. Accordingly, the protection afforded to these constructions is limited only by the following claims.

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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)
  • Supercharger (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)

Abstract

L'invention concerne un moteur à pistons opposés à deux temps (49) doté d'au moins un cylindre porté (c) et d'une récupération uniflow qui comporte une construction de recirculation de gaz d'échappement (EGR) (131) qui amène une partie des gaz d'échappement produits par le moteur (49) pour un mélange avec de l'air de charge de façon à contrôler la production de NOx durant la combustion.
PCT/US2011/000864 2010-05-18 2011-05-16 Construction egr pour moteur à pistons opposés WO2011146111A1 (fr)

Priority Applications (5)

Application Number Priority Date Filing Date Title
JP2013511146A JP6117695B2 (ja) 2010-05-18 2011-05-16 対向ピストンエンジンのためのｅｇｒ構造
US13/068,679 US8549854B2 (en) 2010-05-18 2011-05-16 EGR constructions for opposed-piston engines
EP11721839.6A EP2572089B1 (fr) 2010-05-18 2011-05-16 Construction egr pour moteur à pistons opposés
PCT/US2011/000864 WO2011146111A1 (fr) 2010-05-18 2011-05-16 Construction egr pour moteur à pistons opposés
CN201180024717.4A CN103026024B (zh) 2010-05-18 2011-05-16 用于对置式活塞发动机的egr结构

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
US39584510P 2010-05-18 2010-05-18
US61/395,845 2010-05-18
US40159810P 2010-08-16 2010-08-16
US61/401,598 2010-08-16
PCT/US2011/000864 WO2011146111A1 (fr) 2010-05-18 2011-05-16 Construction egr pour moteur à pistons opposés

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EP (1) EP2572089B1 (fr)
JP (1) JP6117695B2 (fr)
CN (1) CN103026024B (fr)
WO (1) WO2011146111A1 (fr)

Cited By (14)

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US9284884B2 (en) 2013-06-25 2016-03-15 Achates Power, Inc. Trapped burned gas fraction control for opposed-piston engines with uniflow scavenging
US9206751B2 (en) 2013-06-25 2015-12-08 Achates Power, Inc. Air handling control for opposed-piston engines with uniflow scavenging
WO2014209642A1 (fr) * 2013-06-25 2014-12-31 Achates Power, Inc. Commande de gestion d'air pour moteurs à pistons opposés à balayage à écoulement unique
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US9512790B2 (en) 2013-06-25 2016-12-06 Achates Power, Inc. System and method for air handling control in opposed-piston engines with uniflow scavenging
EP3486448A1 (fr) 2013-08-23 2019-05-22 Achates Power, Inc. Système et procédé de commande de manipulation d'air dans des moteurs à pistons opposés avec récupération de type uniflow
WO2015026628A1 (fr) * 2013-08-23 2015-02-26 Achates Power, Inc. Système et procédé de commande de traitement de l'air dans des moteurs à pistons opposés à balayage longitudinal
CN105612327A (zh) * 2013-08-23 2016-05-25 阿凯提兹动力公司 在具有直流扫气的对置活塞发动机中进行空气处理控制的系统和方法
EP3483389A1 (fr) * 2013-08-23 2019-05-15 Achates Power, Inc. Commande de fraction de gaz brûlé et piégé pour moteurs à pistons opposés à récupération de type uniflow
WO2015116570A1 (fr) * 2014-01-31 2015-08-06 Achates Power, Inc. Système de régulation d'air pour un moteur à pistons opposés, dans lequel un compresseur de suralimentation fournit une pression de suralimentation pendant le démarrage d'un moteur et entraîne une recirculation de gaz d'échappement pendant le fonctionnement normal du moteur
US9206752B2 (en) 2014-01-31 2015-12-08 Achates Power, Inc. Air handling system for an opposed-piston engine in which a supercharger provides boost during engine startup and drives EGR during normal engine operation
US20170122199A1 (en) * 2014-06-16 2017-05-04 Volvo Truck Corporation Two-stroke opposed piston internal combustion engine
WO2015192859A1 (fr) * 2014-06-16 2015-12-23 Volvo Truck Corporation Moteur deux temps à combustion interne à pistons opposés libres
US10690051B2 (en) 2014-06-16 2020-06-23 Volvo Truck Corporation Two-stroke opposed piston internal combustion engine
US9982617B2 (en) 2014-12-04 2018-05-29 Achates Power, Inc. On-board diagnostics for an opposed-piston engine equipped with a supercharger
US10450985B2 (en) 2014-12-04 2019-10-22 Achates Power, Inc. On-board diagnostics for an opposed-piston engine equipped with a supercharger
US11396841B2 (en) 2015-12-07 2022-07-26 Achates Power, Inc. Air handling in a heavy-duty opposed-piston engine
US10598104B2 (en) 2017-02-03 2020-03-24 Achates Power, Inc. Mass airflow sensor monitoring using supercharger airflow characteristics in an opposed-piston engine

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JP2013529275A (ja) 2013-07-18
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CN103026024B (zh) 2016-01-27
JP6117695B2 (ja) 2017-04-19

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