WO2003046347A1 - Moteur a deux temps a recuperation - Google Patents

Moteur a deux temps a recuperation Download PDF

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Publication number
WO2003046347A1
WO2003046347A1 PCT/US2001/046898 US0146898W WO03046347A1 WO 2003046347 A1 WO2003046347 A1 WO 2003046347A1 US 0146898 W US0146898 W US 0146898W WO 03046347 A1 WO03046347 A1 WO 03046347A1
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Prior art keywords
recuperator
cylinder
engine
combustion chamber
compressor
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PCT/US2001/046898
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English (en)
Inventor
Richard Berkeley Britton
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Richard Berkeley Britton
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Priority to AU2002245077A priority Critical patent/AU2002245077A1/en
Priority to PCT/US2001/046898 priority patent/WO2003046347A1/fr
Publication of WO2003046347A1 publication Critical patent/WO2003046347A1/fr

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B33/00—Engines characterised by provision of pumps for charging or scavenging
    • F02B33/02—Engines with reciprocating-piston pumps; Engines with crankcase pumps
    • F02B33/06—Engines with reciprocating-piston pumps; Engines with crankcase pumps with reciprocating-piston pumps other than simple crankcase pumps
    • F02B33/22—Engines with reciprocating-piston pumps; Engines with crankcase pumps with reciprocating-piston pumps other than simple crankcase pumps with pumping cylinder situated at side of working cylinder, e.g. the cylinders being parallel
    • 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
    • F02B41/00—Engines characterised by special means for improving conversion of heat or pressure energy into mechanical power
    • F02B41/02—Engines with prolonged expansion
    • F02B41/06—Engines with prolonged expansion in compound cylinders
    • 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
    • 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 piston-type internal combustion engines having an expander cylinder, a compressor cylinder, and an exhaust recuperator which superheats the compressed air charge and passes it into a combustion chamber in the expander cylinder for combustion.
  • the invention relates further to an engine having a recuperator and a protective valve to protect the recuperator from the combustion process.
  • the first recuperative internal combustion engine of the prior art appears to be US Patent 155,087 issued on September 15, 1874 to Joseph Hirsch.
  • the described engine has two cylinders interconnected by a regenerator made of refractory elements. Because the heat exchanger is located in a duct external to the cylinder head and also made of refractory material, the heat exchanger continuously radiates away thermal energy. Hot exhaust gas from the "hot-air” cylinder, after passage through the heat exchanger, passes into the "cold-air” cylinder. When heated exhaust gas is in the cold-air cylinder, water is injected to cool and reduce the volume of the gas in the cold-air cylinder. Additional make-up air is then added under pressure and the gas volume is finally transferred to the hot-air cylinder via the heat exchanger.
  • Utilization of the thermal energy in the exhaust is far from optimum as a consequence of lowering the temperature of the charge before transfer to the hot-air cylinder by way of the heat exchanger. Taking the radiation and convection heat losses from the heat exchanger into account, it is difficult to see how the device can effect an appreciable increase in the Carnot efficiency.
  • the location of the recuperator and the combustor in an external un-insulated duct extending between the two cylinder heads of a Vee-engine presents a large surface for thermal convection and radiation losses to degrade the high temperature thermal energy available from the exhaust, while the occurrence of combustion adjacent the exposed recuperator would lead to deterioration of the element.
  • US Patent 4,630,447 issued to William T. Webber describes, as was also done by Thomson and by Frith, an engine having two cylinders coupled by a recuperator without separation from either cylinder by valving. Air inducted into the cold cylinder is compressed, passed through the recuperator into the hot side, mixed with fuel, combusted, expanded, and passed through the recuperator for further expansion in the cold cylinder, and then exhausted to atmosphere without passing through the recuperator.
  • Webber's engine suffers from potential degradation of the recuperator due to its direct exposure to combustion, as well as loss of thermal energy with the exhaust.
  • US Patent 5,228,415 issued to Thomas E. Williams employs a shell and tube heat exchanger to extract heat from the exhaust and transfer it to the compressed air charge while the air is in transit from a compression cylinder to a combustion cylinder.
  • the shell and tube heat exchanger acts as a recuperator but is less efficient and unless provided with heavy insulation, is not as efficient as a recuperator of the type having a hot end and a cold end and countercurrent flow of the gas streams.
  • recuperative engines have generally had adequate recovery of exhaust heat but their transfer of this heat to the working charge has been inefficient. This is because the high temperature and what is termed "high grade" thermal energy available in and recovered from the exhaust has been allowed to dissipate by escaping to the environment, thus leaving only a fraction of the available energy for transfer to the working charge.
  • Early inventors of heat engines sought effective use of recuperators, but often compromised thermal efficiency by reducing temperatures either to protect working materials and surfaces or to avoid problems with detonation or pre-ignition in the heated combustion gases.
  • recuperation another solution to the exhaust waste problem of the Otto engine and in some cases the Diesel has been the turbo-expansive conversion of exhaust energy to rotative energy.
  • the rotative output is typically used to drive a turbo-compressor for boosting input air pressure to the engine.
  • Turbines are not well suited, however, to the pulsating exhaust flow from a single cylinder nor can they tolerate the aforementioned high temperature gas released at the exhaust valve of an Otto engine. For this reason, exhaust is generally collected and merged from several cylinders to moderate the pulsations and passed through exposed pipes which cool the gas to 1,400° F or lower before it enters the turbine. Such cooling wastes the bulk of the potential energy to the atmosphere, and particularly the high grade, high temperature energy contained in the initial exhaust. For this reason, exhaust turbines have not been particularly effective for raising the efficiency of Otto engines.
  • recuperator The problem with most of these cited internal combustion engines employing a heat exchanger or recuperator of one type or another is the large radiative and convective heat loss caused by the exposed location and the large surface area of the heat exchanging element. As pointed out in the discussion of individual patents, heat losses from the recuperator lower the Carnot efficiency. In the very few instances in the prior art where the recuperator is not subject to radiation and convection losses, the recuperator is located in the working cylinder or located in an internal duct that is directly connected with and open to the working cylinder. This means that the recuperator or equivalent is directly exposed to the flame front of the ignited charge, which can be as hot as 5,000° F, with a consequent shortening of its useful life.
  • the present recuperative engine invention has a significantly reduced percentage of waste energy in its exhaust and consequently has improved efficiency while retaining the low pressure operation and light weight of contemporary Otto engines. This is achieved by incorporating a recuperator, gas ducts, and gas valves entirely within the cylinder head of the engine.
  • the recuperator recovers heat from the exhaust gas at the instant the exhaust leaves the combustion chamber. This heat superheats compressed air for delivery to an early part of the next cycle.
  • the Hx recuperative engine has a compressor cylinder and an expander cylinder, with a respective compressor and expander piston which reciprocate therein between top center and bottom center positions, within 90 degrees of each other in phase.
  • the pistons operate on a two-stroke cycle and typically are connected by a common crankshaft. Since the volume of air passed through the engine is determined by the compressor, the displacement of the Hx engine is defined as the swept volume of the compressor piston.
  • the Hx engine also includes the following elements: means defining a cylinder head enclosing a working end of the aforesaid cylinders, which means provides a minimum clearance volume over the compressor piston of less than 7 percent of the displacement, and provides a combustion chamber over the expander piston; a recuperator built into the cylinder head means, the recuperator being coupled to the combustion chamber and having either a common duct for both exhaust and compressed air flow, or in a preferred embodiment, a first duct for compressed air flow and a second duct for exhaust flow, and an internal volume for compressed air flow that is substantially less than the displacement; means for the selective control of ambient air flow into the compressor cylinder and for the selective control of the then compressed air as it passes through to the recuperator duct and into the combustion chamber as the expander piston is near top center; means for admixing fuel with the compressed air so as to form a combustible charge; means for igniting the charge within the combustion chamber, thereby forming combustion products that urge the expander piston toward bottom center; and
  • recuperator concentric with the recuperator valve, the exhaust valve, and the transfer valve elements as used in the several described configurations. It is also preferred that the recuperator and its associated parts be enclosed in refractory thermal insulation to reduce the loss of heat to the cylinder head structure and the engine coolant.
  • the recuperator may have an elongated shape, such as conical, with the hotter end adjacent the combustion chamber being larger in diameter than the exhaust end, thus minimizing viscous losses in the very hot gas flows in relation to the recuperator's overall volume.
  • the exhaust from the recuperative engine may still contain 20% to 30% of the input fuel energy to the engine, yet it is at a sufficiently low temperature to directly drive a turbine.
  • the exhaust from larger displacement engines above about 200 cubic inches displacement is thus preferably passed through a turbo-expander to convert residual exhaust energy into mechanical power.
  • This power may then be used to directly drive a high RPM alternator for efficient generation of high frequency 1,000 to 4,000 Hz AC electrical power.
  • This AC may of course be used directly, or rectified to DC for conventional vehicular use for powering auxiliaries.
  • FIGURE 1 is a sectional view of a recuperative engine operable on a two-stroke cycle and having dual pistons, a common duct recuperator, and a turbo-expander for final recovery of residual exhaust energy.
  • FIGURE 2 is a sectional view of a preferred embodiment of a recuperative engine operable on a two-stroke cycle and having dual pistons, a separated duct recuperator, and a combustion chamber defined primarily by the cylinder head.
  • FIGURE 3 is a sectional view of another embodiment of the recuperative engine operable on a two-stroke cycle and having dual pistons, a separated duct recuperator, and a combustion chamber located in and defined primarily by the head of the expander piston.
  • FIGURE 4 is a graph comparing the Hx cycle with the Otto and Diesel cycles on linear pressure versus volume scales.
  • FIGURE 5 is a comparison between the Hx cycle and the Otto and Diesel cycles illustrated on a graph having logarithmic pressure versus volume scales.
  • the high efficiency of the Diesel is due to its high expansion ratio, a result of the high compression ratio needed to create high air temperature (generally greater than 550° F) sufficient to auto-ignite the injected fuel.
  • the high compression ratio and attendant high gas and bearing pressures require greatly increased strength and with it, increased weight and cost.
  • a Diesel is, in fact, two to three times the weight and cost of a comparable power Otto engine.
  • the Diesel's high efficiency, now up to 54% in stationary engines, is reflected in its low exhaust temperature which is generally around 1,100° F when it leaves the port of an engine under full load.
  • recuperation is most effective, however, when the recovered heat is used to superheat the charge after the charge is fully compressed within the engine's working chambers. This is achieved in the recuperative engine embodiments described herein.
  • Ignition delay creates another potential energy loss in the recuperative engine.
  • This delay is the total period measured either in degrees rotation of the crankshaft or in milliseconds of time between when an ignition spark occurs and when combustion pressure goes through a peak.
  • optimum spark advance is around 30 crankshaft degrees before top center. If peak pressure occurs at 10 degrees past top center, then ignition delay is 40 crank degrees or 2.2 milliseconds.
  • recuperative engine Since the recuperative engine performs extra functions just prior to ignition which functions do not occur in the Otto, it is important that the recuperative engine have less ignition delay than an Otto engine.
  • extra functions in the recuperative engine are: a) the transfer of compressed air from the compressor through the recuperator to the combustion chamber, b) the closing of the recuperator valve to seal the compressed air into the combustion chamber, and c) the injection of fuel into the compressed air.
  • Ignition delay can be reduced in several ways. These include increasing the temperature of the compressed air charge, increasing turbulence and thoroughness of mixing during fuel injection, increasing the pressure of the air charge, increasing the wall temperature, and modifying the fuel by reducing the octane rating (low octanes ignite faster) and other characteristics. Fuels such as hydrogen and acetylene with lightweight molecules exhibit higher flame speed and therefore have less ignition delay. Gasoline, by comparison, has a slow flame speed, while higher octane gasolines have an even slower flame speed and also a reduced propensity to pre-ignite and to detonate.
  • the recuperative engine invention herein benefits from reduced ignition delay (equivalent to increased flame speed) .
  • I provide the combination of a new and novel recuperative cylinder head with a two cylinder engine, which two cylinders comprise a compressor and an expander.
  • the cylinder head contains a compact internal recuperator having a volume in the range of 2 to 10 per cent of the volume of the inducted air charge, this volume being preferably made as small as possible.
  • the recuperator is adjacent to the combustion chamber and efficiently coupled at its hot end to the chamber for gas flow communication by a recuperator protective valve.
  • an exhaust valve is located at the opposite or cool end of the recuperator for releasing exhaust to the atmosphere.
  • a charge of air is first inducted, then it is compressed and thereby adiabatically heated in a compression cylinder, then passed through the recuperator for second stage superheating from recovered exhaust heat. It is in fact relatively easy to realize over 600 Fahrenheit degrees of heating in an engine running at 1,000 RPM.
  • the doubly heated air is then passed directly into the combustion chamber where fuel is injected and the mixture ignited, while a recuperator protective valve closes behind it to isolate the recuperator from the combustion chamber to avoid the life shortening of the recuperator through exposure to the flaming fuel-air mixture.
  • the combustion gases are then expanded against the expander piston to produce work to a volume which for highest efficiency and dependent upon the design of the engine, may be in the range of 50 to 150 % larger than the ambient volume of the inducted air charge.
  • the expander may have a volume approximately equal to the displacement of the compressor.
  • the topology of the recuperator of the instant invention is such that refractory thermal insulation may be easily provided to enclose and align the high temperature valves and the recuperator and catalytic elements.
  • This arrangement of combustion chamber, recuperator, protective valve, and insulation greatly reduces heat losses caused by radiation and convection and obtains improved Carnot efficiency in a simple, cost effective, practical manner.
  • a compressor piston 14 operates in compressor cylinder 12 and an expander piston 22 operates in adjacent expander cylinder 20.
  • Cylinder head 16 is attached at joint 18 to cylinders 12 and 20 and encloses their open ends.
  • Cylinder head 16 defines inlet port 36 which port contains inlet valve 38 to selectively admit ambient air into compressor cylinder 12.
  • Cylinder head 16 also defines transfer duct 60 containing a transfer valve 56 for selectively releasing compressed air from compressor cylinder 12 to flow to a recuperator 26 contained in a first cavity of cylinder head 16 and insulated by recuperator liner 40.
  • a recuperator valve 58 fitted between recuperator 26 and chamber 34 selectively controls flows of compressed air from recuperator 26 into a second cavity in cylinder head 16 defining a combustion chamber 34.
  • Fuel injector 64 can inject fuel 65 directly into combustion chamber 34.
  • Fuel can also be injected by fuel injector 64' into compressed air as the air flows through recuperator 26 into chamber 34, such injection being preferably at a location where recuperator 26 has a temperature high enough to prevent buildup of carbon or tar.
  • Ignition of the fuel-air mixture within combustion chamber 34 is provided by spark plug 66, particularly during startup. Once warmed up, ignition may occur spontaneously as fuel is injected into the compressed, superheated charge as in a Diesel and the engine may run without spark-ignition.
  • recuperator valve 58 and exhaust valve 70 both open to release exhaust from cylinder 20 whereby these gases can flow through recuperator 26 and give up heat thereto. The gases then flow in a cooled state past exhaust valve 70 and then pass through exhaust port 72. On a subsequent cycle of engine 8, compressed air passing through recuperator 26 receives heat from recuperator 26 by which it becomes superheated as it passes into combustion chamber 34.
  • turbo-expander 74 may be connected with port 72 to receive partially cooled gases 73 from recuperator 26, expand them to further recover energy from them, and release them to atmosphere at 76.
  • Mechanical power produced by turbo-expander 74 may be used to drive electrical alternator 78 to produce electrical power available at output wires 80, or alternatively to provide compressed air for the inlet of the engine
  • recuperator 26 may be described as a common-duct recuperator since both the exhaust gas and the compressed air charge flow through the same duct. However the exhaust flow and the compressed air flow occur alternately and flow in opposite direction through the recuperator, thereby effecting counter-current flow which is the most efficient arrangement.
  • Recuperator 26 is preferably divided by radial divisions into multiple heat transfer elements to thermally isolate elements at the cold end 28 adjacent the compressed air entrance and the exhaust exit from elements at the hot end 30 adjacent to the combustion chamber.
  • recuperator For construction of the recuperator, refractory mate ⁇ als are preferably chosen having a thermal conductivity of at least 30 Btu-ft/hr-ft 2 , which value is about one -eighth that of copper.
  • the recuperator elements must also have high temperature tolerance, materials being presently available with temperature tolerances up to 2,200°F.
  • the supply of air and fuel to the engine may require limiting, either by basic design of induction passages and valving, or by high speed electronic controls which limit air and/or fuel during operation
  • Special consideration must be given to the heat transfer elements at the hot end 30 of the recuperator which will assume a temperature midway between the peak temperature of the exhaust as it leaves the combustion chamber, and the peak temperature of the compressed air as it enters the combustion chamber.
  • Initial exhaust flow gases may be as hot as 3,200°F while the air charge compressed by a ratio of 6 1 may be around 350°F whereby the segment at the hot end 30 may operate around 1,800°F or more.
  • These temperatures must be determined expenmentally for each engine design. Their optimum value is affected by many vanables including engine cylinder volume, RPM, volumetric efficiency of the compressor, combustion chamber shape, turbulence of the pre -combustion gas, type of fuel and so forth
  • Heat transfer elements at the cool end 28 of recuperator 26 adjacent to the exhaust valve operate substantially cooler at about 800°F. Du ⁇ ng operation, recuperator temperatures are higher when the engine is at full load and high RPM, and lower when the engine is at minimum load and at low RPM
  • exhaust gas temperature will nse when the fuel input is reduced to make the fuel-air mixture lean and above stoichiometric.
  • Lean mixtures burn at reduced speed whereby burning may continue throughout an extended portion of the expansion stroke and sometimes into the exhaust stroke.
  • Exhaust from a lean mixture will also contain free oxygen. Overly lean operation may thus be detnmental to the recuperator as well as to engine efficiency due to the combination of these factors.
  • FIGURES 2 and 3 Additional embodiments of the recuperative engine are illustrated in FIGURES 2 and 3. Their primary difference is that the recuperator has a common duct in FIGURE 1 versus a separated duct in the embodiment of FIGURES 2 and 3.
  • the common-duct recuperator 26 in FIGURE 1 is expected to have have higher heat transfer efficiency and lower temperature drop between exhaust flow and compressed air flow than the separated-duct recuperator in FIGURES 2 and 3. This will occur because of the difference in distance which the heat must travel from its area of absorption into the recuperator to its area of release into the compressed air flow. Heat recovered by the surface of an element in the common-duct can transfer directly back from the surface to the compressed air flow in the next phase of the cycle. In the separated-duct recuperator, the heat must transfer from the exhaust port through the body of an element and dividing wall between the exhaust and the air duct, and then transfer into the compressed air.
  • the common-duct embodiment requires four valves for a basic engine unit, while the separated-duct embodiments require only three valves.
  • Each duct in the separated-flow recuperator may be optimized for the characteristics of its gas flow.
  • the compressed air charge has a density of 8 to 10 times that of the exhaust and can be handled with a much smaller duct than is required for the exhaust. This is because the compressed charge is both cool and under a compression of about 6:1 while the exhaust is extremely hot and rapidly expanding to atmospheric /ambient pressure as it passes through the recuperator.
  • FIGURE 1 does not show standard components of an internal combustion engine except for those which are essential for an understanding of my invention.
  • FIGURES 2 and 3 there are second and third embodiments of my invention with a recuperator structure that differs from the embodiment of FIGURE 1.
  • FIGURE 2 is the preferred embodiment of this invention.
  • the engines of FIGURE 2 and FIGURE 3 have no loss of compressed air in transfer duct 60. Due to the minimal volume of duct 60, compressed air from cylinder 12 has a negligible loss of compression as it travels from cylinder 12 through duct 60 into recuperator 26'.
  • Exhaust gas duct 84 and compressed air duct 86 of recuperator 26' can each be optimized for gas flow and gas viscosity by appropriate sizing and tapering.
  • FIGURES 2 and 3 are substantially unchanged from FIGURE 1 as indicated by the indicia affixed thereto. The differences are in the elimination of duct transfer valve 56 of FIGURE 1, and its replacement by recuperator transfer valve 59 and 59' in FIGURES 2 and 3 respectively.
  • Recuperator 26' is now combined with recuperator valve 58 to become a single unit, recuperative exhaust valve 58'.
  • Transfer valve 59 is mounted coaxially with recuperative exhaust valve 58'.
  • Valve 58' and 59 of FIGURE 2 or valves 58' and 59' in FIGURE 3 thus combine the functions of recuperator 26, recuperator valve 58, and exhaust valve 70 in FIGURE 1.
  • the shape of cylinder head 16' is modified to accommodate the altered gas flows, and only one fuel injector is illustrated.
  • a compressor piston 14 and an expander piston 22 operate in adjacent compressor cylinder 12 and expander cylinder 20.
  • a recuperative cylinder head 16' is attached to and encloses the open ends of the cylinders 12 and 20 at joint 18.
  • Cylinder head 16' also defines a transfer duct 60 to pass compressed air from compressor cylinder 12 into recuperator 26', and a combination recuperative exhaust valve 58' to allow the compressed air to pass through compressed air duct 83 from recuperator 26' into combustion chamber 34.
  • Recuperator 26' has separated ducts, a construction wherein the exhaust gas and the air charge passage is through the recuperator in opposite directions, and in adjacent but separate ducts.
  • FIGURE 2 Also illustrated in FIGURE 2 is a fuel injector 64 to inject and admix fuel with the superheated, compressed air charge within chamber 34.
  • recuperative exhaust valve 58' opens to release exhaust from cylinder 20 to flow through separate exhaust duct 81 of recuperator 26' and through exhaust port 72 to the atmosphere. Ignition of the fuel-air mixture within combustion chamber 34 is provided by spark plug 66.
  • FIGURE 3 is a third embodiment of the invention wherein the head of valve 59' is basically flush with the top of expander cylinder 20 and combustion chamber 34' is defined by the upper end of expander cylinder 20 and the head of expander piston 22', and the surface of cylinder head 16".
  • Recuperative exhaust valve 58' and recuperator transfer valve 59' are arranged approximately coaxial with expander cylinder 20.
  • Fuel 65 is fed in through a hollow stem of recuperator transfer valve 59' and injected through fuel atomization means 64" under the head of valve 59', whereby atomized fuel is admixed with the compressed air as the air enters combustion chamber 34'.
  • FIGURE 4 a graph illustrates on a linear scale, the relative cylinder volume versus cylinder gas pressures in the Otto and the recuperative engines.
  • a Diesel cycle is shown on the same graph.
  • the recuperative cycle deviates from the Otto cycle at point c where recovered exhaust heat is applied to the compressed air charge to superheat it to point d Hx on the curve. Combustion then provides a pressure increase from point d H to d c .
  • recuperative cycle over the curve, b - c - d H *-d c - e - f contains considerably more area and thus generates greater work output than the Otto cycle over its curve, b - c - d' - e' - f .
  • FIGURE 5 illustrates the same cycle pressures and volumes using logarithmic graph scales.
  • the two-cylinder engines in FIGURES 1, 2, and 3 represents the basic unit of this invention, one cylinder being employed for induction and compression of ambient air and the other cylinder being used to receive compressed air and fuel, combust and expand the mixture, and then exhaust it.
  • This basic unit is a two-stroke wherein it fires once for each revolution of its crankshaft, but without suffering any of the drawbacks of the common two-stroke Otto having a single piston.
  • recuperative dual piston two-stroke is thus quite suitable for low power utility applications such as garden tractors, lawn mowers, all terrain vehicles, outboard motors, chain saws and the like.
  • low power utility applications such as garden tractors, lawn mowers, all terrain vehicles, outboard motors, chain saws and the like.
  • From two to six or even more such units may be ganged together in a common engine block to produce the equivalent of a modern day four to twelve cylinder four-stroke Otto engine.
  • One method has been developed for ganging four units of the recuperative engine for automotive use much like a conventional 90° V-8 Otto automotive engine configuration.
  • Each four-cylinder bank of the V-4 recuperative engine will preferably have compressor pistons in cylinders one and four, and expander pistons of larger size in cylinders two and three.
  • Each expander cylinder will fire once per revolution, giving four uniformly spaced power impulses per crankshaft revolution as in a conventional V-8 Otto engine. Modifications to a single conventional style crankshaft will provide the correct firing order for the expander pistons and a phase lead to the compressor pistons appropriate to the design RPM of the engine.
  • FIGURE 1 A Ford 4 cylinder Pinto 2.0 liter engine block assembly was used as the basic test engine. Cylinders 1 and 4 were blanked off and used only for mechanical balance while cylinders 2 and 3 were used for the compressor and the expander. The phasing of the compressor and expander was left as is; that is, the compressor and the expander pistons moved in synchronism. By putting a twist in the crankshaft, of course, one can build into an engine any desired phase difference between the compressor and expander pistons.
  • a phase lead of the compressor of about 15 degrees over the expander may be advantageous for an engine designed to run in a low 500 to 2,000 RPM range while for higher RPM, a larger phase advance would be optimal.
  • the compressor and the expander cylinders were left at their basic displacement of 30 cubic inches, each.
  • a recuperator duct having an internal gas volume of one -fifteenth of the cylinder displacement (approximately 2 cubic inches) was built into the recuperative cylinder head between the cylinders, and metal sheet helices were fixed in place in this duct to serve as the recuperator element.
  • An inlet port was built into the cylinder head to admit an air charge into the compressor cylinder, while a conventional poppet inlet valve built into the inlet port controlled charge flow through the duct into the compressor cylinder.
  • a small poppet valve about 0.5" diameter served as a transfer valve and was built into the head over the compressor cylinder to release charge from the compressor cylinder into a small duct which connected with the "cool end" of the aforementioned heat exchanger duct.
  • an exhaust valve was placed to release cooled exhaust gases to the atmosphere.
  • recuperator duct adjoined a combustion chamber which was also built into the recuperative head.
  • the hot end was fitted with a poppet recuperator valve that controlled the release of superheated charge from the recuperator into the combustion chamber and into the expander cylinder. Later in the cycle, the recuperator valve releases hot exhaust gases from the expander cylinder allowing them to pass through the combustion chamber, the recuperator valve, the recuperator, and out through the exhaust valve to atmosphere.
  • the recuperator 26 Upon startup of the engine in a four-stroke cycle, the recuperator 26, which is initially at ambient or room temperature, very quickly warms up and after several dozen engine cycles at full throttle, approaches a temperature up to as high as 2,000°F. Initial operation of the engine is thus much like that of an engine operating on an Otto cycle, but as the recuperator reaches maximum temperature, the engine cycle becomes strongly recuperative. Satisfactory operation of the engine was obtained over a range of about 400 RPM up to 980 RPM.
  • recuperative mode operation was measured exiting the engine cylinder head up to 600°F cooler than it exitted when the engine is operated in the Otto mode with the recuperator element removed.
  • this reduction in exhaust temperature implies an improvement in gas cycle efficiency for the recuperative cycle of approximately 30% over the Otto.
  • fuel-to-air ratio can be leaned significantly more than when operated as an Otto, to an estimated 25:1.
  • the lean burn capability is undoubtedly due to the superheat of the fuel-air charge in comparison with the charge temperature in an Otto engine.

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Abstract

L'invention concerne un moteur à combustion interne à récupération, à deux temps, possédant un cylindre d'extension (20) avec une chambre de combustion ouverte (34) située dans son extrémité de travail et un cylindre de compression séparé (12) destiné à injecter une charge d'air comprimé surchauffé dans la chambre. Ce moteur permet d'obtenir un rendement de Carnot amélioré par confinement des constituants de travail dans une tête de cylindre. Le récupérateur (26) récupère l'énergie thermique, habituellement rejetée dans l'échappement du moteur, et la ramène au cycle de travail. Ce résultat, longtemps recherché par d'autres, a été obtenu en incorporant de façon compact dans la tête un récupérateur de chaleur d'échappement interne (26) étroitement couplé à une chambre de combustion. Une soupape de protection du récupérateur (58) isole le récupérateur (26) des gaz de combustion chauds jusqu'à ce que ces derniers aient été refroidis par extension complète du piston. Un prototype a permis de démontrer que la récupération peut faire baisser la température d'échappement de 600 degrés Fahrenheit en dessous de la température pouvant être atteinte dans un moteur Otto équivalent, ce qui permet que le rendement soit supérieur d'un tiers à celui d'un moteur Otto.
PCT/US2001/046898 2001-11-26 2001-11-26 Moteur a deux temps a recuperation WO2003046347A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU2002245077A AU2002245077A1 (en) 2001-11-26 2001-11-26 Two-stroke recuperative engine
PCT/US2001/046898 WO2003046347A1 (fr) 2001-11-26 2001-11-26 Moteur a deux temps a recuperation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US2001/046898 WO2003046347A1 (fr) 2001-11-26 2001-11-26 Moteur a deux temps a recuperation

Publications (1)

Publication Number Publication Date
WO2003046347A1 true WO2003046347A1 (fr) 2003-06-05

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AU (1) AU2002245077A1 (fr)
WO (1) WO2003046347A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1639247A2 (fr) * 2003-06-20 2006-03-29 Scuderi Group LLC Moteur a quatre temps split-cycle (a cycle scinde)
DE102010047112A1 (de) * 2010-02-26 2011-09-01 GETAS GESELLSCHAFT FüR THERMODYNAMISCHE ANTRIEBSSYSTEME MBH Verbrennungsmotor und Verfahren zum Betrieb eines Verbrennungsmotors
DE102010020325A1 (de) 2010-05-12 2011-11-17 Christian Daublebsky von Eichhain Thermokompressionsmotor
WO2012050902A3 (fr) * 2010-09-29 2014-02-20 Scuderi Group, Inc. Dimensionnement de passage d'intercommunication pour moteur à cycle divisé
US8833315B2 (en) 2010-09-29 2014-09-16 Scuderi Group, Inc. Crossover passage sizing for split-cycle engine
US20220154652A1 (en) * 2020-11-17 2022-05-19 Volvo Truck Corporation Internal combustion engine system

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Cited By (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7810459B2 (en) 2003-06-20 2010-10-12 Scuderi Group, Llc Split-cycle four-stroke engine
CN101368507B (zh) * 2003-06-20 2012-08-29 史古德利集团有限责任公司 分开式循环四冲程发动机
EP1639247A2 (fr) * 2003-06-20 2006-03-29 Scuderi Group LLC Moteur a quatre temps split-cycle (a cycle scinde)
CN100445528C (zh) * 2003-06-20 2008-12-24 史古德利集团有限责任公司 分开式循环四冲程发动机
EP1990516A3 (fr) * 2003-06-20 2009-08-12 Scuderi Group LLC Moteur a quatre temps split-cycle
EP2096279A1 (fr) * 2003-06-20 2009-09-02 The Scuderi Group, LLC Moteur a quatre temps split-cycle
AU2009200503B2 (en) * 2003-06-20 2009-09-03 Scuderi Group, Llc Split-cycle four stroke engine
EP2112350A1 (fr) * 2003-06-20 2009-10-28 Scuderi Group LLC Moteur a quatre temps split-cycle
AU2004250137B2 (en) * 2003-06-20 2010-01-21 Scuderi Group, Llc Split-cycle four stroke engine
AU2004250137B9 (en) * 2003-06-20 2010-03-04 Scuderi Group, Llc Split-cycle four stroke engine
AU2008207684B2 (en) * 2003-06-20 2010-03-04 Scuderi Group, Llc Split-cycle four stroke engine
EP2146073A3 (fr) * 2003-06-20 2010-04-21 Scuderi Group LLC Moteur a quatre temps Split-Cycle
EP1925795A3 (fr) * 2003-06-20 2008-08-13 Scuderi Group LLC Moteur à quatre temps split-cycle
US8006656B2 (en) 2003-06-20 2011-08-30 Scuderi Group, Llc Split-cycle four-stroke engine
EP1639247A4 (fr) * 2003-06-20 2006-11-22 Scuderi Group Llc Moteur a quatre temps split-cycle (a cycle scinde)
AU2009227866B2 (en) * 2003-06-20 2011-10-27 Scuderi Group, Llc Split-cycle four stroke engine
AU2009202979B2 (en) * 2003-06-20 2011-11-03 Scuderi Group, Llc Split-cycle four stroke engine
DE102010047112A1 (de) * 2010-02-26 2011-09-01 GETAS GESELLSCHAFT FüR THERMODYNAMISCHE ANTRIEBSSYSTEME MBH Verbrennungsmotor und Verfahren zum Betrieb eines Verbrennungsmotors
DE102010020325A1 (de) 2010-05-12 2011-11-17 Christian Daublebsky von Eichhain Thermokompressionsmotor
WO2011141508A1 (fr) 2010-05-12 2011-11-17 Christian Daublebsky Von Eichhain Moteur thermique à compression
DE102010020325B4 (de) * 2010-05-12 2012-09-06 Christian Daublebsky von Eichhain Wärmekraftmaschine
US8683984B2 (en) 2010-05-12 2014-04-01 Christian Daublebsky von Eichhain Thermocompression motor
WO2012050902A3 (fr) * 2010-09-29 2014-02-20 Scuderi Group, Inc. Dimensionnement de passage d'intercommunication pour moteur à cycle divisé
US8833315B2 (en) 2010-09-29 2014-09-16 Scuderi Group, Inc. Crossover passage sizing for split-cycle engine
EP2622189A4 (fr) * 2010-09-29 2015-12-23 Scuderi Group Inc Dimensionnement de passage d'intercommunication pour moteur à cycle divisé
US20220154652A1 (en) * 2020-11-17 2022-05-19 Volvo Truck Corporation Internal combustion engine system
US11598248B2 (en) * 2020-11-17 2023-03-07 Volvo Truck Corporation Internal combustion engine system

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