For over a hundred years , engines got bigger , faster , and meaner , with morehorsepower and torque . Exhaust bubble from the tailpipes like a dragon awoken from its slumber to boom at likely thieves of its hoarded wealth . At least , that ’s what the guy rope with the all-embracing tyre and the airbrush flame business wants you to call back .
Then came the twentieth century , when we realized thatfire - breathing engine were slaying more than red - light retarding force racing antagonist . turn out , all that burp was interchange the climate and produce smutty smog . Too manydragonswere making the planet more like Mordor than the Shire .
Who can save us from these exhaust system - burp dragons ? Who can tame their gas pedal - guzzling ways with his sword of science and engineering ? Who carries the one dead on target ring offuel efficiency ? One human race : James Atkinson of Hampstead , Middlesex , England . Also of 1887 .
That ’s right – the latest in green engine technology come from the morning of the automotive eld . The Atkinson cycles/second engine was patented in the United States in 1887 ( Atkinson filed for U.K. and European patents a couple years in the beginning ) . But the uneven strokes of the plunger in hisgasoline - power combustion engine fit our modern cross system pretty neatly .
The Atkinson cycle locomotive engine used in so many hybrids these days works on the same rule as the original – with the obvious advantage of a century of technological advances . But in decree to infer where we ’re at today , we first have to know where we ’ve been . Set your time auto for 1887 !
The Original Atkinson Cycle Engine
Atkinson ’s U.S. patent ( number 367,496 , for us patent of invention - adoring nerds ) is pretty aboveboard : about a thousand countersign of text and a few helpful diagrams . Or you could just study this account , which is far wittier than any patent .
The most common combustion locomotive engine these day is afour - stroke Otto cycle engine , where a piston sound up and down inside a piston chamber and a spark ignites a smorgasbord of gas and air . Same become for an Atkinson cycle engine , so here ’s a quick refresher course of the appendage :
Intake stroke : absorb air and fuel into the piston chamber
Compression stroke : splash the mixture so when the spark go off , it will blow up – bragging meter
king or expanding upon stroke : Uses the forcefulness create by the explosion to move the plunger down the cylinder
Exhaust stroke : Pushes the nasty leftover of the burning process out of the piston chamber
In an Otto cycle engine , this is done in two rotations of the crankshaft : intake / lighting , then ability / exhaust fumes . In the original Atkinson engine , the inventor added a couple of linkages so that all four CVA could be completed with a single rotation of the crankshaft .
That in itself would improve efficiency , but Atkinson had another realization : if the compression in the cylinder were lowered and the world power cerebrovascular accident was long than the intake stroke , the engine would put to work more efficiently . It would take less fuel to turn the engine , which turns the wheels and make the car go .
Imagine , if you will , the cylinder and piston . On the intake shot , the piston does n’t move all the way down the cylinder . The intake valve , where the tune and fuel infix the cylinder , does n’t appropriate as much of the miscellanea into the piston chamber . Less mixture requires less compression . The piston moves back up for the concretion stroke , and at the top the mixture is erupt . Boom ! The forcefulness sends the Walter Piston back down the quill of the cylinder in the big businessman stroke , this time all the way down to take advantage of every last mo of strength generated by the combustion . Then the piston move back up to get the junk out for the exhaust fumes slash . Ta da ! Four strokes , less fuel !
Of naturally , clever lecturer that you are , you plausibly realized that less fuel and less compression have in mind less power . You are right . Even though the Walter Piston is allowed to travel further down on the power stroke than it does on the intake accident , it ’s not run to generate as much power as it does in an engine with higher compression and a richer gas mixture .
The other challenge with this engine is that it requires pile of additional parts , which makes it tricky to assemble , not to remark expensive . pitiful Atkinson had to achieve all this efficiency with spring and vibrate links and a carmine - red-hot ignition tubing , which sounds like an excellent name for a band . forward-looking engineers have a much easier time of it .
The Modern Atkinson Cycle Engine
Purists will pooh - pooh the Atkinson cycle engine of today , with nary a vibrating radio link in visual modality . As a affair of fact , if you put a forward-looking Atkinson cycle engine next to a modernOtto oscillation railway locomotive , you would n’t be able to see any difference . " There ’s nothing in [ the Prius ] locomotive engine that ’s not in the regular locomotive engine , " according to David Lee at the University of Toyota . ( It ’s not a university you’re able to attend unless you ’re a Toyota employee needing to know about the latest and greatest roll out to the dealerships . Sorry . )
What Atkinson had to achieve with crankshaft placement we now can do withvariable valve timing , a far chinchy and easier solution . recall that in Atkinson ’s master , the intake valves would close betimes to keep out some of the melodic line - fuel mixture . now , the intake valve is withstand open a little too long , so that when the Walter Piston go up for the condensation stroke , a lilliputian of the gas - tune mixture can hightail it . Each method has the same end : the compression ratio is low-pitched . In engineer - speak , the modern method acting is known as " livic " – previous intake valve closure . Then thespark plugdoes its thing – touch off – and the plunger takes vantage of the combustion with a full big businessman stroke down the cylinder . And then the exhaust stroke does its clean - up task .
More than that has alter in 120 - plus year . In the pursuance for increased efficiency , newfangled materials have been develop . Lighter - weight Walter Piston , rings , and valves springs , for instance , reduce friction and the overall weighting of the car . haul less free weight around take less energy . Using adual - overhead River Cam locomotive , as Ford does in its Fusion and other hybrids , make it even easier to control the summons .
And again , ingenious lector , you in all probability noticed that the modern version of this engine bring forth less power , just like its predecessor . Too reliable . As Lee noted , " This locomotive would struggle in a regular railway car . "
But you know where it does n’t fight ? In ahybrid drivetrain .
The Atkinson Cycle and Hybrid Cars
So , you ’ve get anenginethat ’s really efficient , but it lacks in power , specially of the torque variety , the kind of major power that the attack - breathing pull car has in spades . But , if you ’re ahybrid powertrainengineer , you also have anelectric motorthat has all torsion all the time , from 0 rev . The problem with the galvanizing motor is that it does n’t sustain a high speed very well , not as well as a petrol locomotive does , with its higherhorsepower . What to do , intercrossed powertrain railroad engineer ?
Well , if you ’re Gilbert Portalatin , who happens to be a hybrid powertrain railroad engineer with Ford , or any other engine driver at almost any other gondola company building full hybrids , you take these two systems together likechocolateand peanut butter . At low speeds , the electric motors sound off in with their torsion and move the car ahead . Unless you ’re one of those super carefulhypermilerswho exhort the throttle valve as gently as if a kitten were hide underneath it , thegasolineengine will come online pretty quickly , though the electrical motor is doing quite a bit of workplace . At about 40 miles per hour or so , the Atkinson cycle railway locomotive will take over almost completely , with a bit of assist from the electrical motor .
As long as you ’ve got this kind of jazz band , you may direct the Atkinson bicycle locomotive to mesh exactly with the electric motor for optimum efficiency . If you insist on pick out on the fire - snorkel in the next lane , you wo n’t be leave totally in the junk . " Smash the pedal , and you ’ll get what you ’re asking for – all of both powerplants , " say Lee at Toyota .
This load leveling is why a full crossbreed like the Toyota Prius or Ford Escape get well gasoline mileage around Ithiel Town than they do on the highway – exactly the opposite of , like , every other vehicle on the road . The non - fire - breathing place among us drive pretty slowly around town . We begin and stop a luck , and we do n’t get up to 75 miles per hour , so the electric motor takes a lot of the encumbrance . On the highway , though , the gasolene locomotive engine is pretty much working alone .
Hardly anyone in 1887 could have predicted the happy peanut vine butter - and - burnt umber union between Atkinson ’s engine and electrical motors – auto did n’t even have permanent roofs then .
Atkinson Cycle Engine FAQ
Lots More Information
To be absolutely reliable , I love writing these super - technological article . I get it on calling technologist and making them excuse things to me that I have never canvass . I have a hard clip even figure what they ’re talking about , so I make them repeat themselves six ways to Sunday to check that I have it right before I compose anything down .
This time , I mother an superfluous - geeky bonus : nerd coloring Good Book ! Okay , it was n’t really a color script , but if you depend up Atkinson ’s patent of invention using Google ’s patent of invention hunt ( phone number 367,496 , remember ) it includes Atkinson ’s original diagrams . I used all eight of my highlighters and several colored Sharpies to keep raceway of which valves did what , and where the atmosphere was coming in and the fumes was going out . Then I color - coded the patent text – which I had also print out – so that when I was reading , I could match up vibrating link H in the description with its piazza in the engine .
I can not recommend the coloring rule book method acting of technological acquisition enough . I contrive on using it as often as potential . My inner eight - year - old is very glad .
