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Toyota Describes Combustion Engine That Generates Electricity Directly
cartechboy writes: "While electric cars are now more available than ever, combustion engines will remain for decades to come. Now auto engineers are working to refine combustion power as part of cars that are increasingly electrified, including plug-in hybrids. Toyota's new 'Free Piston Engine Linear Generator' (or FPEG) shows us one potential way. Linear engines eliminate the rotating crankshaft of conventional engines in favor of a single chamber, in which a piston moves forward and backward. A linear engine has no crankshaft, nor connecting rods. In their place is a gas-filled chamber, the compression of which functions like a spring — returning the piston after the expansion / combustion phases of a typical combustion cycle. This back-and-forth motion can be turned into energy, when you haven't got a crankshaft and the mechanically-useful rotation it produces. While linear engines are far from new, and Toyota's test units are only 10 kW (13 horsepower), a pair of them can still produce enough electricity for a Yaris- or Corolla-sized vehicle to cruise on the highway at 75 mph."
The real question is how efficient is it? The article doesn't say. It might be simpler mechanically than using a crankshaft to generate rotational energy, but that doesn't mean it is more efficient than an alternator / generator method of producing electricity.
Better known as 318230.
Okay. Is there some sort of plan to use these in future vehicles? How do they compare to traditional engines in terms of efficiency, power, maintenance requirements, etc.? How do they compare to electric vehicles in the same regard? Devoid of any such meaningful substance, this story seems like fluff meant to distract from Tesla, Nissan, Ford, etc. who are aggressively pursuing all-electric vehicles.
so how is it different from diesel electric locomotive ?
To me this design wants to be combined with a sterling engine.
It's all about finding better ways
75mph at 10kw, assuming 35% thermal efficiency, gives us 44 mpg. Not incredible but not bad.
Embrace.
Extend.
Extinguish!
http://jalopnik.com/5210372/bi...
So you're gonna need at least two cylinders. But they'll have to be opposed and they'll have to fire in time, because otherwise they're not going to help you. I don't have any trouble believing they can synchronize them, but this makes the engine a lot longer, and you might as well just build a boxer. If the gas seal on the chamber on the other side of the piston fails, your engine will fail spectacularly. Seals fail all the time. Meh.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
How is this not just a one cylinder engine? Based on the description, that's what it sounds like.
Why don't they just scale down (massively) from diesel electric locomotives and be done with it?
Ken
millions of miles per 'charge'. no subscription model yet? free the innocent stem cells no bomb us more mom us.. some still calling this 'weather'? http://www.youtube.com/results?search_query=weather+manipulation+wmd+cabals oh what a feeling?
...you've invented the alternator!
There were 2 of these 10Kw units required to cruise at 75Mph, so the efficiency, assuming 35% thermal efficiency, is 22mpg.
Given that they're small and easy to maintain, perhaps that doesn't matter if they're only backups, or if this is just a first-iteration technology that may get substantially better.
The big concern imho, is vibration. Unlike a crankshaft-based engine/motor, there is no physical coupling of the pistons if you deploy two of these in a horizontal configuration (as TFA suggests would counter vibration).
The lack of coupling means that the pistons are not mechanically synchronized, which means they don't create forces which act against each other.
I'd have to imagine that one could approximate the physical coupling by varying the timing and mixture, but.. I have no idea how actually effective that'd be.
Anyway.. vibration. Big deal.
Why not generate in both directions, and get AC current?
How's the back-and-forth motion converted to electric power?
Fuck systemd. Fuck Redhat. Fuck Soylent, too. Wait, scratch the last one.
10 kw is an interesting number for another reason, too -- 10 kwh is about the size of the average US home electrical draw. An hour of run time, some storage... assuming 10 kw is the output of these things, and various efficiencies, etc. Still, it's an interesting number. Sure seems like you could make an interesting power source from them.
I've fallen off your lawn, and I can't get up.
It looks as though it would have the same problem as other internal combustion engines: most of the energy from the fuel is wasted as heat.
Maybe they should be working on thermocouple technology (or something else) and generate electricity from the cooling system and charge batteries or power wheels. Now that would increase efficiency greatly.
So chemical energy generates mechanical energy which then generates electricity. This is not what the word "directly" means.
RTFS.
A diesel locomotive as a traditional diesel engine with a crankshaft that turns a generator. The rotational energy is converted in to electricity by moving coils past alternating magnetic fields.
If move a single magnet back and forth through a coil it will also produce electricity.
If you attach the magnet to the piston and the coil around the cylinder walls you don't need a crankshaft anymore. I guess in theory, less friction = less loss = more efficient. Without a crankshaft there isn't any side load put on the cylinder either, so that experiences less friction too.
You still need mechanical movement to run values though, or you've just an inefficient 2-stroke cycle.
Perhaps they need to develop decent electronic valves before they go telling everyone how efficient it is.
It's probably the same on the same load however...
If you think about constant speed, you have less metal, less weight, and cheaper costs to make. Less mechanical issues.
You could even plug a turbo on it.
The whole thing is generally black from soot, too. And you know what that means... It means we need some rope.
The linear generator is also a motor. We should be able to use the magnetic fields to move the piston back and forth. Mechanical complexity of cams, crankshafts and flywheels and clutches replaced by the electrical complexity. Easier to handle and more reliable too. But still don't see any reason to believe it is going to be more efficient.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
10 kilowatts ought to be enough, it's like the output of 50 human beings (unless they're working really hard at pedaling), I also don't feel the need to go over 50 mph.
In fact it is a good match for the european category of heavy motorised quadricycle : up to 15 kilowatts, up to 1 ton payload (when transporting goods ; max vehicle weight at 550 kg in this case) and top speed not very high.
If the engine can be scaled down in power as well as size and weight you open up the lightweight category which is max 4 kilowatts, max 200 kg payload and slow but can be driven without driver license (45kph max)
Have just enough battery range for driving out of parkings, driveways etc. and very short trips.. That drives cost, weight and charging time down and is a nice solution for when you just wanted to pick up stuff at a nearby store or in a rural area, go to the village back and forth.
For the engines themselves, free-piston and electrics, that seems elegant. The thermal engine runs at fixed rpm and is ideally suited for a vehicle where there would be no transmission, chain, crank whatever ; the electric ones give full torque. For full size vehicles it is maybe not so much a revolution (with the exception of being able to burn any fuel, including synthetic ones and ammonia)
2quick notes;
Rotational Energy in a mechanical system is conserved.
Heat is biggest waste in any internal combustion engine, so far.
Rotational energy in an operating internal combustion engine is conserved not unlike a flywheel retains energy until friction or other force causes it to slow.This is perhaps the most efficient thing about most gas/diesel engines.
The worst thing about internal combustion engines is the waste heat! However there are numerous methods available, to recapture this waste heat.Heat exchangers can be employed, even a small steam engine can be run from the manifold heat. Perhaps the most surprising method of recovery of heat from a gasoline engine was (to Me) when a small solar cell was placed beneath a hot engine and the heat caused a full release of 18 volts from the solar cell, about all one could expect from the same solar cell in direct sunlight.. This brings to mind the potential of a hybrid composite gas-electric engine having incorporated wiring for magnetic fields and ceramic/silicon outer layer for thermoelectric direct conversion to electricity.
At least, a magnetohydrodynamic generator is the only thing I can think of off the top of my head that "directly" converts energy from combustion to electricity. Still doesn't look like it's anywhere close to the efficiency of a good fuel cell, though, and those superconducting magnets would make for an awfully heavy vehicle. (Now, if you used liquid hydrogen for both fuel and cryo-coolant...)
Felix Wankel is somewhere laughing his ass off.
You are welcome on my lawn.
Free piston engines have been around since a least the 50s. Described in detail in Taylor's "The Internal Combustion Engine in Theory and Practice"1977, rev 1985, An excellent set of book on how internal combustion engines work.
The classic version used a turbine for output and was not very efficient. Using direct electromagnetic output for a hybrid is an interesting idea. One of the great weaknesses of the free piston engine is poor low power performance, and that isn't needed in a hybrid. Not clear though that it can do better than the (almost) Atkinson cycle engine in a Prius - (a cycle also described in detail in the Taylor book).
The Toyota design is unusual, most free piston engines use opposing pistons to fix vibration. Not clear why toyota uses a single piston.(or two separate pistons).
As with most engine designs, the devil is in the details - cooling, lubrication, etc. Sometimes a design that is good in concept just can't compete with the enormous amount of development that has been done on conventional designs.
A 2-stroke carefully tuned to a smallish rpm band can be very efficient.
Simple, light, powerful - not terribly environmentally friendly
I bought a ScanGauge II back in 2008 and use it to this day. Plug it into the OBD II port to read data. One of the data points is engine torque, which can be converted to power. My previous car, a 2008 VW Jetta with the 2.5 L engine needed 35 hp to maintain 75 mph on a flat road. 26 hp is about right for my wife's 2011 Prius at 75 mph.
They have. In the prototype they use hydrolic valves.
A fuel cell is pretty good at converting chemical energy into electrity directly.
Of course they work best on Hydrogen, but we need to stop burning carbon anyway.
I also don't feel the need to go over 50 mph.
So it YOU! If you're that guy, please, please get out of the fast lane! It's dangerous to have everybody switching to the slow lane to pass you. ;)
They demonstrated and mentioned several concept cars on Top Gear (england) where it was a full electric car that had a diesel generator in it. It wasn't as good as realtime but it'd give you some miles in a pinch. It was relatively quiet and they said it was over 100MPG effective in most models.
How environmentally unfriendly? I remember reading about an environmental contest, and one entrant was disqualified for submitting a 2-stroke. It would have won, beating all the 4-strokes for economy/emissions, but they changed the rules to exclude 2-stroke after the entry was accepted.
Learn to love Alaska
Each pistol could act as it's own, independant cell, greatly reducing the chance of catastrophic engine failure.
Nobody cracks the obvious joke? Slashdot really is dead.
Fuck systemd. Fuck Redhat. Fuck Soylent, too. Wait, scratch the last one.
I've seen some amazing prototype demos of magnetic fluids as a sealant. The concept is sound and I don't know why somebody isn't doing anything with them. It can hold quite a lot-- magnets keep the liquid in the gaps and there is minimal friction; much less than any solids. somebody just needs to engineer a synthetic oil that is magnetic... but even if they don't, just the magnetic fluid should be enough...
not sure of the speeds... but the demo I saw was for an air compressor that used less energy (due to the seals being essentially a fluid that was between water and gas in viscosity... and boy did it stain anything it touched...)
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I would guess that with a linear action, you don't have to deal with the crank shaft grinding at all the joints, flexing a belt to run an alternator, etc. The result, less friction, which yields more efficiency.
it's an old idea, but worth trying now because electric power conversion works very well now. This thing generates AC at some variable frequency and voltage depending on fuel flow and load. The waveform that comes out is awful. (See the article). Two successive cycles can be quite different. There's no flywheel or rotating mass to smooth out the motion.
Today, converting that irregular electrical output into something more consistent is straightforward. The output is going to be fed into some kind of switching power supply, probably with an ultracapacitor to smooth things out. This beats trying to stablize the thing mechanically.
Koenigsegg has some pneumatic valve technology that is rather promising.
In Soviet Russia, dot slashes YOU!
They just need to change their name so people know how to pronounce it. I don't care how fast their cars are.
You can do four stroke engines without valves, a duke engine is a good example.
https://www.youtube.com/watch?v=c19kn3drdFU
One of the problem with boxer-style engines (older VWs, 911s, Subarus) was that the horizontal orientation of the piston bores meant the bores, rings, and pistons wore more rapidly at the bottom due to self-weight when compared to vee or vertical engines. The slide showed roller bearings to support the rotor / piston, so maybe that's less of an issue.
Example: Mazda RX8 (full on 2 seater sports car). 26MPG is reported by real owners. Seals stopped being a problem in the late 70s. I have 2 RX7 from the early 80s, they do better than 26MPG and rebuilds are not something I'm doing all the time.
But you are correct, the Wankel is an evolutionary dead end. The reason is simple: The combustion chamber moves around the engine (look up a picture of it, really cool) and so the hot gasses loose heat to the walls. As a result the efficiency is less.
Even that didn't kill the Wankel (for Mazda). What did was it's rather bad emissions performance... due to lack of engineering experience perhaps, but I also think because the geometry that makes it less efficient also means incomplete combustion.
Electric cars work. This charges the batteries as you go. You can have smaller batteries. Where is the problem?
2-stroke engines are "unfriendly" because they use positive pressure from the piston to pump the charge into the cylinder. That means you have charge in your crank case, which in turn means you need oil mixed in with your charge, and that oil gets exhausted as unburned soot. Add a blower to pump the charge into the cylinder, independent of the motion of the piston, and your emissions issues vanish.
Why not link to the original fucking page
http://www.tytlabs.com/tech/fpeg/fpeg02.html
you know - the one with the fucking "copyright toyota" marks all over it and with the original info, pictures, etc..
Or the actual documents
http://papers.sae.org/2014-01-1203/ "Development of Free Piston Engine Linear Generator System Part 1 - Investigation of Fundamental Characteristics"
http://papers.sae.org/2014-01-1193/ "Development of Free Piston Engine Linear Generator System Part 2 - Investigation of Control System for Generator"
Comments about mechanical simplicity are missing the key advantage. There is no risk of pre-ignition bending a piston rod if if fuel is introduced too early in the cycle. Direct injection also solves this - there is not fuel in the cylinder until it's safe. This is the solution for diesel engines and allows for higher compression. But a crankshaft makes it hard to change an engine's compression ratio, which can be useful, especially in a multi-fuel setup. A crankshaft dictates how far the piston can rise towards the cylinder head and determines a fixed volume at top-dead-center, the highest point in the piston's travel. In a free piston engine the piston is free to top out closer or farther from the cylinder head.
Who thought it was a good idea for Washington to dictate a national speed limit in the first place? Are traffic conditions in the Mojave desert the same as an urban freeway?
There are parts of Texas and Nevada where you can drive for an hour, in a straight line, without seeing another car. Is that anything like the northeast ? Why should the speed limits be the same?
That's a problem with common implementations, not with 2-stroke itself. That's why the guys in the contest (colorado I think) got kicked out. I was hoping someone would call me an idiot for not citing it and link to it. Put valves on the 2-stroke and it fixes all the problems you mention. 2-stroke will be more efficient than a 4-stroke because the heat lost in the 3 non-power strokes reduces efficiency compared to the 1 non-power in a 2-stroke. And if this crankless engine takes off, I see someone coming out with a 2-sided piston for a double-2-stroke, making power on every stroke. They'll make the engine half the size or twice the power. And you could turn off half when not needed. So you make one big enough for single-side operation cruise, and the other side kicks in only for low-battery conditions.
Learn to love Alaska
"Without a crankshaft there isn't any side load put on the cylinder either, so that experiences less friction too."
There are alternatives to cranks which don't produce sideloads on the piston/cylinder. The best also extract more 30% energy from the stroke as they're not subject to cosine rules.
Downside: hideous mechanical complexity. They've been tested and work, but they require the bottom end be a lot more complex than it is now.
http://www.shelleys.demon.co.u...
http://www.wisemanengine.com/a...
http://www.scalzoautomotiveres...
The simplest is simply a straight rod connected to the piston which attaches to the crank rod via a silder - these are commonly used in ships and large stationary engines, but they increase the height of the engine by _at least_ the length of the piston stroke and they don't give any mechanical advantage over a standard crankshaft setup.
There's also the scotch yoke, but it's not wonderful under high loads.
http://en.wikipedia.org/wiki/S...
There are plenty of non-charged-crankshaft 2 stroke designs around. If you use an external supercharger (or turbo driven off exhaust pressure) you don't need to use crankcase pressure.
Writing off 2 strokes because _one_ design is polluting is a bad idea.
You can get the equivalent to variable compression ratio by altering valve timing; delaying the closing of the intake valve lowers compression ratio.
There are also .... unique ways to vary the stroke length given a fixed crankshaft, but that adds complexity, not reduces it.
=Smidge=
On April 2, 1987, Surface Transportation and Uniform Relocation Assistance Act SET the speed limit at 65 MPH.
You are probably thinking of the 1995 National Highway System Designation Act, which gave states much more freedom.
Still, in 2001 Houston was negotiating with the feds over speed limits, which were hen being indirectly set by the EPA.
All of those engines look great, for producing small amounts of power.
http://www.scalzoautomotiveres... is the best though, If you look at the 3D models you can see they've kept the large surface area bearing on the crankshaft, but the other two, which need to handle at least as much force are tiny.
The first and second ones are basically the same, all the force of the fuel exploding is transferred through a single tooth of a planetary gear.
I expected 2 cylinders at opposite ends with 1 piston in the middle for back-and-forth motion.
I agree with the assessment about power and stress ponts, but bear in mind that we _are_ talking about small amounts of power.
One of the largest advantages of the toyota design is that you can use power modules and only fire up as many as are needed, which gets around the issue of piston engines only being most efficient around full load. That alone will improve the overall efficiency of the setup from the typical 5-15% to the 25-30% range.
There's another design I ran across a few years ago which has been tested in real world situations and works well, developing a lot of torque, but at cost of utterly hideous mechanical complexity (the crank is replaced with 2 counterrotating butterfly wheels and the connecting rod rides on top of them, rigidly attached to the piston)
All reciprocating stuff all has disadvantages though - primarily vibration. Fuel cells are more efficient and quiet but they require levels of fuel purity currently unavailable in portable applications.
At the other extreme from car engines, this is a good example of a slider crank: http://qualityjunkyard.com/200...
Wave disks (essentially an inverted whittle turbine) look interesting, but proabbly aren't practical and almost certainly won't achieve the claimed improvements. http://wattsupwiththat.com/201...
One of the largest advantages of the toyota design is that you can use power modules and only fire up as many as are needed, which gets around the issue of piston engines only being most efficient around full load. That alone will improve the overall efficiency of the setup from the typical 5-15% to the 25-30% range.
AKA, variable displacement engines.
http://en.wikipedia.org/wiki/V...
It's been done since the 80's. It's been done properly for 10 years too.
Yes, it's a form of variable displacement - much better than the types previously seen in auto engines (cylinder deactivation)
Cylinder deactivation on anything rigidly attached to a crankshaft is an imperfect way of doing variable displacement as there are still significant frictional losses (Try turning a crankshaft by hand with the head off and cams disconnected - you'll feel it)
If you don't have a crankshaft then the pistons can be stopped entirely, resulting in greater efficiency.
This idea has a lot of merit and is extremely compact, but I do wonder how they'll kill the vibration issue.
Apparently the pumping losses - moving air through the intake/throttle/valves/exhaust incurs more loss than the friction.
Also, turning the crankshaft when there is no oil pressure is going to be harder than when there is. The bearings that connect the conrods to the crankshaft and the ones that support the crankshaft are designed to be fed with oil so there is no metal-to-metal contact.
Most of the friction will be coming from the piston rings