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Topic: Atkinson cycle


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  Animated Engines, Atkinson
The Atkinson engine is essentially an Otto-cycle engine with a different means of linking the piston to the crankshaft.
The clever arrangement of levers allows the Atkinson to cycle the piston through all four strokes in only one revolution of the main crankshaft, and allows the strokes to be different lengths -- the intake and exhaust strokes are longer than the compression and power strokes (In this illustration...
In Atkinson's original engine, the power stroke was made longer than the intake stroke.
www.keveney.com /Atkinson.html   (312 words)

  
 The Internal Combustion Engine
The advantages of the Otto cycle are fairly good thermodynamic efficiency (conversion of the heat energy released when the fuel burns into mechanical work), an excellent power-to-weight ratio and reliability due to relatively simple operation.
Unfortunately, in the Otto cycle engine, the expansion ratio is the same as the compression ratio, that is, the ratio by which the charge is compressed before being ignited by the spark.
In an Otto cycle engine, the fuel/air "charge" is drawn into the cylinder during the downstroke and then locked in by the intake valve closing near "bottom-dead-center".
www.ecrostech.com /prius/original/Understanding/InternalCombustion.htm   (3426 words)

  
 Aftermath #3
Atkinson has sent a draft letter to Connerly, acknowledging that he mishandled the matter and should have consulted more with the regents before deciding on the delay in implementing their policy.
Atkinson explained that an unfortunate breakdown in communications led to his recent blow-up with the regents and he took the blame for a series of miscues, including a premature e-mail message sent out by his staff.
Atkinson said that he had not intended to bypass the regents when he ordered the delay in implementation of the new admissions policy.
sun3.lib.uci.edu /~dtsang/uc/cs/aft3.htm   (2792 words)

  
 Atkinson cycle - Wikipedia, the free encyclopedia
The Atkinson cycle is designed to provide efficiency at the expense of power, and is beginning to see applications in modern hybrid electric applications.
The original Atkinson cycle engine allows the intake, compression, power, and exhaust strokes of the four-stroke cycle to occur in a single turn of the crankshaft, and was designed to bypass patents covering the existing Otto cycle engines.
While Atkinson's engine design is no more than a historical curiosity, the Atkinson cycle, where the power stroke is longer than the compression stroke, is beginning to become common due to the increase in fuel economy it provides.
en.wikipedia.org /wiki/Atkinson_cycle   (758 words)

  
 atkinson cycle page - atkinson cycle engine
The Atkinson cycle may also refer to a four stroke engine in which the intake valve is held open longer than normal to allow a reverse flow of intake air into the intake manifold.
Because a smaller portion of the intake stroke is devoted to compressing the intake air, an Atkinson cycle engine does not intake as much air as would a similarly-designed and sized Otto cycle engine.
Animation of Atkinson Cycle Engine Note that this animation shows the true Atkinson engine, which uses a complex linkage that allows different stroke lengths for intake/compresssion and power/exhaust.
www.theramonitor.com /atkinson_cycle.html   (500 words)

  
 non pulsed otto cycle engine
I mean the ideal Otto cycle (which does not take into account the intake and exhaust strokes) which is essentially adiabatic compression, constant volume burning, adiabatic expansion and finally heat rejection at constant volume.
KM Even the continuous burn Brayton cycle has some pulsation at the 'output' simply because of the presence of the 'buckets' or 'teeth', or whatever it uses to derive power.
To date that is the definition of Brayton Cycle (Who knows, in the future there may be a new ICE cycle discovered that is also continuous burn), and it is the main differentiator from the timed-combustion engines, like the Otto and Diesel cycles.
www.physicsforums.com /showthread.php?t=82566   (1356 words)

  
 The Miller Cycle   (Site not responding. Last check: 2007-11-07)
This is the "fifth" cycle that the Miller cycle introduces.
Thus the Miller cycle uses the supercharger for the portion of the compression where it is best, and the piston for the portion where it is best.
Due to the reduced compression stroke of a miller cycle engine a higher over all compression ratio is possible, and therefore a miller cycle engine has a better efficiency.
members.cox.net /powellbn/miller.htm   (578 words)

  
 Full Test: 2001 Toyota Prius   (Site not responding. Last check: 2007-11-07)
The Atkinson cycle is a refinement of the normal intake, compression, combustion and exhaust four-stroke engine cycle.
Similar to the Miller cycle found on Mazda's supercharged Millenia S Sedan, the Atkinson cycle enables the duration of the compression stroke and the expansion stroke to be set independently of each other.
Because the Atkinson cycle does not generate high output, there is no practical application for this system unless it is combined with a supercharger; however, this system offers a high level of thermal efficiency.
www.edmunds.com /reviews/roadtests/roadtest/43877/page004.html   (987 words)

  
 Green Car Journal Online - Your Source for Hybrids, Hydrogen and Alternative Fuel Vehicles   (Site not responding. Last check: 2007-11-07)
The four-stroke Atkinson cycle, invented by James Atkinson in 1882, is different than the Otto cycle engine we’re used to driving in very distinct ways.
Compared to the Otto cycle, where the intake valve is closed near bottom-dead-center, the Atkinson cycle does not close the intake valve at BDC, but leaves it open as the piston rises on the compression stroke.
The Atkinson cycle allows the engine to be downsized to 76 horsepower at 4600 rpm while still being as efficient, or perhaps more so, than the Echo variant.
www.greencar.com /index.cfm?content=features32   (1461 words)

  
 cars - Internal combustion engine
Engines based on the two-stroke cycle use two strokes (one up, one down) for every power stroke, relying on the action of the bottom of the piston within the crankcase to help move the fuel-air mixture, and are used where small size and weight are important, such as lawnmowers, mopeds, outboard motors and some motorcycles.
Engines based on the four-stroke cycle or Otto cycle have one power stroke for every four strokes (up-down-up-down) and are used in cars, larger boats and many light aircraft.
Motor cycles and commonly have from one to four cylinders, with a few high performance models having six.
www.carluvers.com /cars/Internal_combustion_engine   (1794 words)

  
 Atkinson cycle Page - atkinson cycle
The Atkinson cycle allows the intake, compression, power, and exhaust strokes of the four-stroke cycle to occur in a single turn of the crankshaft.
The Atkinson cycle may also refer to a four stroke engine in which the intake valve is held open longer than normal to allow a reverse flow into the intake manifold.
This is desirable for good fuel economy because the compression ratio in a spark ignition engine is limited by the octane rating of the fuel used, while a high expansion ratio delivers a longer power stroke and reduces the heat wasted in the exhaust.
www.patpress.com /A---J/Atkinson_cycle.php   (0 words)

  
 Quasiturbine Problematic - HCCI Homogeneous Charge Compression Ignition - SCCI Stratified Combustion
The Atkinson cycle may also refer to a four stroke engine in which the intake valve is held open longer than normal to allow a reverse flow into the intake manifold.
At low load factor, the intake depressurization of the Otto cycle dissipates power from the engine since the throttle valve is almost closed and the descending piston acts as a clogged vacuum pump against the atmospheric pressure, which vacuum is subsequently partially destroyed by fuel vaporization during the compression.
Due to this effect, the engine in Otto cycle opposes to all RPM revolution increase (well known as the engine compression braking) and this intrinsic resistance to speed augmentation is compensated by a constant and important fuel consumption.
quasiturbine.promci.qc.ca /QTPhotodetonation.html   (5332 words)

  
 Atkinson cycle..... - CarSpace Automotive Forums
The Atkinson cycle is the method Mazda uses in the Millenia S but along with a super-charger to maintain a decent power output along with good fuel economy.
I believe the Mazda used the Miller cycle which is a 5 stroke system versus standard 4 stroke.
The atkinson cycle actually uses different piston stroke travel for intake/compression vs power/exhaust, whereas the Miller cycle (Mazda) uses delayed intake valve closing to virtualize the shorter intake/compression stroke.
townhall-talk.edmunds.com /direct/view/.ef21e99   (657 words)

  
 Combined cycle - Wikipedia, the free encyclopedia
In a combined cycle power plant (CCPP), or combined cycle gas turbine (CCGT) plant, a gas turbine generator generates electricity and the waste heat from the gas turbine is used to make steam to generate additional electricity via a steam turbine; this last step enhances the efficiency of electricity generation.
In the combined cycle plant the thermodynamic working cycle is operated between the high firing temperature and the ambient temperature at which low temperature waste heat can be disposed.
Although combined cycles have traditionally only been used in large power plants, BMW has a proposal to deploy such a system in automobiles by using exhaust heat to drive a steam turbine.
en.wikipedia.org /wiki/Combined_cycle   (1392 words)

  
 Gingery's Atkinson Cycle Engine
After all, Atkinson was competing in the expanding small engine market against Nicholaus Otto"s newly developed four-stroke engine.
We smile and explain that the secret lies in the unusual design of the crank linkage which, believe it or not, allows the exhaust, intake, compression and power strokes to be completed in one revolution of the crankshaft.
Building the Atkinson "Cycle" engine is well worth the time and trouble.
www.lindsaybks.com /dgjp/djgbk/atkin/index.html   (0 words)

  
 ICE - The Internal Combustion Engine in Hybrid Vehicles
The pumping losses in an Atkinson cycle engine are reduced by allowing, in the compression stroke, a small amount of the fuel/air mixture to flow back from the cylinder into the induction system, without being burned, thus reducing the effective displacement of the engine.
The Atkinson cycle — also called the "five-stroke cycle" (because of the backflow which is really not a cycle) — works like this: intake, backflow (partial expulsion to eliminate pumping losses), compression, expansion, and exhaust.
In the case of the Ford Escape Hybrid, engineers convert the Zetec I-4 engine to an Atkinson cycle by changing the intake camshaft to one with a very late valve closing and installing pistons that decrease combustion clearance volume.
www.hybrid-vehicle.org /hybrid-vehicle-ice.html   (1392 words)

  
 2005 Ford Escape Hybrid Review--World's Cleanest, Most Fuel-Efficient SUV   (Site not responding. Last check: 2007-11-07)
In the Atkinson cycle, the intake valve closes well after the piston begins moving upward to compress the air-fuel mixture, resulting in less energy loss, associated with all gasoline engines and more energy from the same amount of fuel.
The disadvantage to the Atkinson cycle is less torque availability, particularly at low engine speeds, such as when pulling away from a stop.
With the Atkinson cycle four cylinder gasoline engine and an electric motor working in concert, the Escape hybrid can run on its electric motor alone, its gasoline engine alone, or the most efficient combination of the two.
www.infotraxx.com /review.php?articleid=64   (2631 words)

  
 Toyota Prius Hybrid Car Petrol Engine Information
The main culprit is pumping loss which is the limiting of the power generated by a conventional Otto cycle engine by restricting the flow of air into the inlet manifold.
In an Otto cycle engine, the fuel/air "charge" is drawn into the cylinder during the down stroke and then locked in by the intake valve closing near "bottom-dead-centre".
By contrast, the Atkinson cycle does not close the intake valve at bottom-dead-centre but leaves it open while the piston begins to rise.
www.cleangreencar.co.nz /page/prius-petrol-engine   (2653 words)

  
 escape HEV
The Atkinson cycle engine is up to 10 percent more efficient than a conventional four-stroke Otto cycle engine.
The Atkinson cycle - also called the "five-stroke cycle" - works like this: intake, back-flow (partial expulsion to eliminate pumping losses), compression, expansion and exhaust.
Engineers convert the Zetec I-4 engine to an Atkinson cycle by changing the intake cam shaft to one with a very late valve closing and installing pistons that decrease combustion clearance volume.
home.att.net /~biker16/escape_HEV.html   (1258 words)

  
 Heat engine Summary
To be efficient, a heat engine must operate using a reversible process, that is, a process after which the thermodynamic system and its surroundings are returned to the state they were in before the process started.
Theoretically, the most efficient heat engine is the Carnot cycle, although the Carnot cycle is not used for practical applications because of engineering difficulties that cannot be overcome.
An example of a thermodynamic cycle used to design practical heat engines is the Otto cycle (isentropic compression, reversible constant volume heating, isentropic expansion, reversible constant volume cooling) of which the gas engine is the most well-known application.
www.bookrags.com /Heat_engine   (1416 words)

  
 Ford Escape HEV
The Atkinson cycle, also called the "five-stroke cycle" works like this: intake, back-flow (partial expulsion to eliminate pumping losses), compression, expansion and exhaust.
Based on this cycle, the combustion chamber volume is adapted to maintain a constant compression ratio for each load level while varying the expansion ratio to optimize efficiency.
Low-end torque losses, which are characteristic of five-stroke cycle engines, can be overcome with the assistance of an electric drive motor, making the Atkinson cycle ideal for hybridization.
filebox.vt.edu /users/jehunte3/PIP/Ford/escape_HEV.htm   (1318 words)

  
 Honda Accord Hybrid vs. Toyota Camry Hybrid - CarSpace Automotive Forums
Atkinson cycle engine can maintain 35% to 37% efficiency from 1,500 to max RPM while Otto cycle peak efficiency is about 32%.
The reason Atkinson cycle makes sense for a hybrid is because of high torque electric motor.
Atkinson cycle engine will virtually eliminate PP and PL in all cylinders in every situations.
townhall-talk.edmunds.com /direct/view/.ef26ffa/52   (3543 words)

  
 Atkinson cycle..... - CarSpace Automotive Forums
The Atkinson cycle is the method Mazda uses in the Millenia S but along with a super-charger to maintain a decent power output along with good fuel economy.
I believe the Mazda used the Miller cycle which is a 5 stroke system versus standard 4 stroke.
The atkinson cycle actually uses different piston stroke travel for intake/compression vs power/exhaust, whereas the Miller cycle (Mazda) uses delayed intake valve closing to virtualize the shorter intake/compression stroke.
townhall.edmunds.com /direct/view/.ef21e99   (0 words)

  
 Engine Compression Ratio - GreenHybrid - Hybrid Cars   (Site not responding. Last check: 2007-11-07)
In the Modified Atkinson / Miller Cycle engine, the intake valve is held open during part of the compression stroke.
On an Otto cycle engine, stroke is the distance the piston moves from TDC to BDC.
According to wikipedia, the hallmark of the Atkinson cycle is not necessarily that all four strokes occur in one rev of the crankshaft, but that the expansion ratio must be higher than the compression ratio:
www.greenhybrid.com /discuss/engine-compression-ratio.10279.html   (1244 words)

  
 Gingery's Atkinson Differential Engine Book
Even before James Atkinson developed his unorthodox "cycle" engine, he developed this totally unconventional "differential" engine in an attempt to circumvent Nicolaus Otto's patents on the four-stroke engine, and to allow Atkinson to compete with Otto headon in the new gas engine market.
Even if you are not likely to build this engine anytime soon, by studying the contruction secrets revealed here, you can journey back in time and taste the state of the IC engine art as it was in the 1880's.
If you have built, or at the very least, have studied our earlier book on the Atkinson "Cycle" engine, then you already know what an amazing engineer (in the truest sense of the word) Atkinson was.
www.lindsaybks.com /dgjp/djgbk/diff   (0 words)

  
 2005 Ford Escape Hybrid
Also, the I 4 Atkinson engine can be automatically shut down thus avoiding the fuel waste and tailpipe emissions during long idling periods.
By using the Atkinson cycle, fuel consumption is reduced 7-10 percent.
The Atkinson engine is an adaptation of the 2.3 Liter Duratec I 4 found in Ranger, Escape, and 2005 Focus.
www.gulfcoastnews.com /RT2005FordEscapeHybrid.htm   (2060 words)

  
 Directory:Atkinson-Cycle Rotary Engine:Libralato Ruggero - PESWiki
Rotary engine design by inventor, Libralato Ruggero of Italy, uses the Atkinson cycle to combine the best attributes of wankel rotaries and piston engines.
R.A.C.E. Rotary Atkinson Cycle Engine (Independent of type of fuel used).
This allows for the future development of alternative fuels like hydrogen to be used without the valve overlap and sealing problems associated with piston engines.
peswiki.com /index.php/Directory:Atkinson-Cycle_Rotary_Engine:Libralato_Ruggero   (0 words)

  
 ME3321
temperature in the cycle is 2200K, and the compression ratio is 8.
The air-standard Atkinson cycle described in the problem statement is
Otto cycle which were obtained in problem 9.1.
www.menet.umn.edu /~abra0038/homework/hw10.htm   (355 words)

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