Beta
×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

Toyota Describes Combustion Engine That Generates Electricity Directly

Soulskill posted about 5 months ago | from the you-got-your-electric-in-my-dinosaur-burner dept.

Transportation 234

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."

Sorry! There are no comments related to the filter you selected.

Efficiency? (4, Interesting)

Dan East (318230) | about 5 months ago | (#46884715)

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.

Re:Efficiency? (4, Insightful)

Todd Palin (1402501) | about 5 months ago | (#46884765)

I was thinking the same thing. Efficiency is the real question. I assume the article would have mentioned this if the efficiency was available to the authors. The fact that efficiency figures weren't available means they were not very impressive at this stage. The devil is in the details.

10 kw (2)

fyngyrz (762201) | about 5 months ago | (#46884899)

10 kw is an interesting number for another reason, too -- 10 kwh is about the size of the average US home electrical draw. [eia.gov] 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.

Re:10 kw (4, Funny)

fyngyrz (762201) | about 5 months ago | (#46884913)

eh, goddamit.

10k kiowatt hours.

WTF is my coffee?? Good grief.

Re:10 kw (1)

oodaloop (1229816) | about 5 months ago | (#46885219)

10k kiowatt hours

I expected much better spelling from someone named 'fyngyrz'!

Re:10 kw (3, Interesting)

ShanghaiBill (739463) | about 6 months ago | (#46885783)

10 kw is an interesting number for another reason, too -- 10 kwh is about the size of the average US home electrical draw. [eia.gov]

For stationary residential use, you could run the thing on cheap natural gas (rather than expensive gasoline) and use the waste heat to warm your house. It would be personalized cogeneration [wikipedia.org] .

Disclaimer: Yes, I realize that outside North America, natural gas isn't cheap.

Re:Efficiency? (5, Informative)

Dahamma (304068) | about 5 months ago | (#46885207)

Efficiency information was there, I guess the dumbed-down article linked from the post didn't feel like including it. This link (that was in TFA) has much more interesting details:

http://www.greencarcongress.co... [greencarcongress.com]

Summary is, not only does it have 42% efficiency (for reference, efficient DI gas engines are about 35%, and diesel about 40%), it allows for a lighter, simpler engine with reduced cooling and lubrication requirements. Higher efficiency, lower weight, fewer moving parts all just generally contribute to a lower TCO, which would be a great thing, as series hybrids are still not particularly cheap (at least without their current subsidies)...

Re:Efficiency? (1)

DigiShaman (671371) | about 6 months ago | (#46885633)

Well that, and Toyota is behind this. But I'm rather surprised that it's that efficient. I would think there would be a substantial inductive loss in the form of wasted EM radiation along with heat. At least with mechanical energy, it goes directly from the combustion chamber to where the rubber meets the road; effectively.

Re:Efficiency? (3, Interesting)

Crayz9000 (2783019) | about 6 months ago | (#46885957)

Effectively?
Mechanical losses are a major issue with cars, particularly when dealing with power losses through differentials. Friction will quickly make you its bitch, which is why everything must be kept well-lubricated, and even then you have to keep the viscosity to an absolute minimum to avoid fluid load.
A completely electric drivetrain, if done right, can eliminate almost all of the moving parts that contribute to power loss. Electricity, wires, and motors. It doesn't get much simpler than that.

Re:Efficiency? (0)

Bing Tsher E (943915) | about 6 months ago | (#46886143)

Copper loss. Eddy currents.

Really, just a whole new set of conditions.

That's all. Different, not necessarily simpler.

Re:Efficiency? (1)

cheater512 (783349) | about 6 months ago | (#46885873)

Does that include using it to drive the wheels?
I assume the petrol/diesel stats do.

Re:Efficiency? (1)

swillden (191260) | about 6 months ago | (#46885949)

Does that include using it to drive the wheels? I assume the petrol/diesel stats do.

Doesn't make much difference because electric motors are very efficient, nearing 100%.

Re:Efficiency? (5, Informative)

calidoscope (312571) | about 6 months ago | (#46886099)

The transmissions on current GE and EMD diesel electric locomotives are about 94% efficient from the output of the prime mover to the driving wheels. I would expect electric car motors to be on the order of 90 to 95% efficient, so this should compare favorably with a mechanical tranny.

Speaking of locomotives, the free piston gasifier was being heavily researched in the 1950's as a more efficient realization of a gas turbine and something that could compete with diesel engines as prime movers.

Re:Efficiency? (2)

FatdogHaiku (978357) | about 5 months ago | (#46885375)

The devil is in the details.

Crap, I've spent years hunting him in the boardroom!

Re:Efficiency? (1)

Mr D from 63 (3395377) | about 5 months ago | (#46884777)

Efficiency and size/HP. A small one as a backup genny in an EV might be interesting, or larger ones in a hybrid.

If they are efficient, how about using them as portable generators as well? That nobody has used them in this manner before sparks my critical side.

Re:Efficiency? (3, Interesting)

Blaskowicz (634489) | about 6 months ago | (#46885611)

Nobody has used them because they need some high tech. From what I've read free-piston engines need to be computer-controlled at a very high rate, else the technology is unworkable. Something like an Intel 8051 wouldn't keep up, so for that reason alone it was not invented 30 years ago.
Writing the firmware must be hard, as hinted by the wikipedia article's end. Maybe that requires a lot of computer simulations, which is easier to do in the 2000s and 2010s to say the least.

I do agree a portable generator would nice, or a lightweight vehicle that doubles as a power plant. 10 kilowatts would be pretty good for audio gear, lighting and an ice machine to keep the beer cool.

Re:Efficiency? (1)

cheater512 (783349) | about 6 months ago | (#46885887)

So...it needs what a low end smart phone or a Raspberry Pi can provide without breaking a sweat?

Doesn't quite explain the last 10 years. We've had plenty of computing power for ages.

Re:Efficiency? (1)

Blaskowicz (634489) | about 6 months ago | (#46885637)

As for efficency I read a claim they can do 60%, which is crazy high and pretty much the max for anything. But my source is weak (finding about free-piston engines serendipitously and maybe doing some google searches)

Re:Efficiency? (2)

ShanghaiBill (739463) | about 6 months ago | (#46885809)

As for efficency I read a claim they can do 60%, which is crazy high

No way ... unless you are using liquid nitrogen for your heat sink. Even a perfect Carnot cycle isn't going to give you efficiencies that high. Maybe they mean "60% of perfect CC" rather than "60% = (electrical energy out)/(fuel energy in)".

Re:Efficiency? (1)

Blaskowicz (634489) | about 6 months ago | (#46886011)

That must be theoretical efficiency (I thought of that after hitting "submit").
That makes me think of audio amplifiers. Class D amps have a theoretical efficiency of 100% :), real world results are about 88% to 92%.

Re:Efficiency? (2)

grmoc (57943) | about 5 months ago | (#46884781)

.. and how efficient is at as compared to a turbine?

Re:Efficiency? (1)

rubycodez (864176) | about 5 months ago | (#46884965)

or a free piston engine driving a turbine? I love how I keep seeing the same shit different decade

Re:Efficiency? (2, Insightful)

Anonymous Coward | about 5 months ago | (#46885111)

Turbines are really not efficient at all. Even if you made a perfect turbine, the Brayton cycle is inherently less efficient than the Otto/Atkinson cycle used in internal combustion engines.

They are used in airplanes because nothing beats their power/weight ratio, and in power plants because of their longer MTBF and ability to burn lower quality fuels.

Re:Efficiency? (3, Informative)

slinches (1540051) | about 6 months ago | (#46885987)

That's not true in practice. The efficiency of the Brayton cycle may be lower for the same compression ratio, but higher compression ratios are achievable. This is the same reason Diesel engines are more efficient. Also, turbines tend to have lower thermal and mechanical losses.

Re:Efficiency? (2)

drinkypoo (153816) | about 6 months ago | (#46885691)

Well, according to the only reference I found before I got bored [nal.res.in] you need recirculation to even reach 30% with a small turbine in the power range we're discussing. That's not really competitive with modern ICEs, let alone this engine.

Re:Efficiency? (1)

Zeussy (868062) | about 5 months ago | (#46884783)

The other thing the article doesn't state, is that the cylinder and head design is similar to 2 stroke diesels. With exhaust ports at the top, and intake ports at the bottom, blocked off as the piston moves up. They generally use a supercharger or a turbocharger to force the exhaust gases out and the fresh intake charge in, so I assume this design is using some sort of electric supercharger in it's place.

Heat (0)

Anonymous Coward | about 5 months ago | (#46884923)

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.

Re:Heat (1)

amorsen (7485) | about 5 months ago | (#46885013)

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.

No. It would not increase efficiency greatly. The meagre temperature differences available as waste from a car engine will not provide much output from a heat engine.

Re: Heat (0)

Anonymous Coward | about 6 months ago | (#46885739)

Eliminate the cooling system and replace it with a heat pump that exchanges with outside air and you will see that heat engine yield another 20% efficiency in captured electrical power. The question is whether or not that could be developed affordable, and whether the complex heat pump would just be another system to break.

Re:Heat (0)

Anonymous Coward | about 5 months ago | (#46885317)

We're getting really damn close to your "most" being factually incorrect. Merc's current engines from F1 are over 40% efficient. It's rumoured that Honda's design is 40% efficient even without the turbo charger, which implies it may get close to 50% efficiency when they add the turbo.

It's probably the same on the same load however... (0)

Anonymous Coward | about 5 months ago | (#46884973)

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.

Re:Efficiency? (1, Interesting)

kimvette (919543) | about 5 months ago | (#46885069)

The real question is actually, will the car be safe? with 13hp*2, 0-60 will likely be in the high 20s. Not very good for merging, or crossing traffic, or going uphill, or even hauling groceries. Think sub-VW Beetle performance, considering that a Beetle weighed in at less than half the weight of today's nannystate-mandated safety features.

Re:Efficiency? (2)

cryptizard (2629853) | about 5 months ago | (#46885139)

They will not be powering the acceleration directly though, they will be charging batteries which power an electric drivetrain. That means you get some extra charge while you are sitting at a red light and you use more when accelerating to highway speed.

Re:Efficiency? (4, Informative)

im_thatoneguy (819432) | about 5 months ago | (#46885183)

The real question is actually, will the car be safe? with 13hp*2, 0-60 will likely be in the high 20s. Not very good for merging, or crossing traffic, or going uphill, or even hauling groceries.

Of course. The great thing about electric cars is that you have tons of torque instantly available. This is just for charging batteries. As long as you aren't accelerating indefinitely they can make up the high power drain from the acceleration while cruising.

Re:Efficiency? (2)

beelsebob (529313) | about 5 months ago | (#46885331)

Acceleration should be just fine. This thing just needs to run constantly producing power to charge the battery. The electric motors will have far more torque and power than this, and be able to (temporarily) discharge the battery, until you lift.

Re:Efficiency? (0)

Anonymous Coward | about 5 months ago | (#46885401)

It would be pretty silly to have this be the direct source of power, doncha think? It's for keeping the battery charged.

Alternate sig suggestion: Every time we say that Slashdotters can't be that stupid, they set out to prove us wrong.

Re:Efficiency? (1, Interesting)

kimvette (919543) | about 6 months ago | (#46885557)

Okay anonymous coward, tell me this: what happens when you have a very long incline for miles, such as found on I-84, I-76, I-80, I-70, etc. and your batteries run down? Granted most of it isn't steep, but very long distances. Also, what happens when the cells have worn out? The generator has got to provide enough power to drive the electric motors directly in order for the car to be streetworthy. Also, is 75mph the top speed? Speed limits are now 70 or even 80 or 85 on more and more American highways, and the minimum is usually 10mph under the posted limit. Again, on long inclines, when the batteries have drained, will the generator provide enough current to keep the car moving at legal highway speeds?

Now, it's time to turn your snark around against yourself.

Re:Efficiency? (1)

Bing Tsher E (943915) | about 6 months ago | (#46886163)

Pontiac is out of business. So low-priced overpowered ego-peen vehicles are slowly dwindling away. There are still Mustangs and Camaros to produce hazardous conditions when combined with such a low powered vehicle, but they'll likely fade away as well.

Re:Efficiency? (0)

Anonymous Coward | about 5 months ago | (#46885303)

75mph on 26hp... pretty efficient given that most cars need triple that. By removing most of the mechanics you're eliminating an awful lot of friction, noise, momentum (eg of cams) etc.

Most? Hardly (5, Interesting)

the_humeister (922869) | about 6 months ago | (#46885621)

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.

Re:Efficiency? (2)

willy_me (212994) | about 5 months ago | (#46885463)

The real question is how efficient is it?

It does not have to be any more efficient if they manage to reduct weight and increase reliability. Efficiency has a big part to play but even a less efficient engine would be desirable if they improve greatly on other aspects.

Remember that this is being targeted for vehicles that will run mostly on electric power. An ICE is a dead weight when not being used. If someone drives using 90% pure electric then the efficiency gains of carrying less weight could easily outweigh the losses of an ICE that was 5% less efficient but only operates for 10% of the time.

Just like a bunch of Slashfags (-1)

Anonymous Coward | about 5 months ago | (#46884717)

You like the idea of a "piston" moving up and down in your "single chamber."
 
Fucking faggots are taking over.

Re:Just like a bunch of Slashfags (0)

Anonymous Coward | about 5 months ago | (#46885019)

The whole thing is generally black from soot, too. And you know what that means... It means we need some rope.

Okay. (2)

sexconker (1179573) | about 5 months ago | (#46884737)

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 locomo (0)

Anonymous Coward | about 5 months ago | (#46884779)

so how is it different from diesel electric locomotive ?

Re:so how is it different from diesel electric loc (3, Informative)

viperidaenz (2515578) | about 5 months ago | (#46884943)

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.

Re:so how is it different from diesel electric loc (1)

Anonymous Coward | about 5 months ago | (#46885469)

A 2-stroke carefully tuned to a smallish rpm band can be very efficient.
Simple, light, powerful - not terribly environmentally friendly

Re:so how is it different from diesel electric loc (1)

matfud (464184) | about 6 months ago | (#46885681)

They have. In the prototype they use hydrolic valves.

Stirling engine? (1)

Gablar (971731) | about 5 months ago | (#46884791)

To me this design wants to be combined with a sterling engine.

Re:Stirling engine? (1)

mspohr (589790) | about 5 months ago | (#46885307)

It sounds like it is close to a Stirling engine as it is now.

Re:Stirling engine? (1)

Anonymous Coward | about 6 months ago | (#46885503)

The linear portion, yes....but this is still internal combustion, and while a simple change in the spring constant/air mixture should allow it to use a wide variety of fuels, a Stirling engine is even more fuel-agnostic, as it's external combustion...just need a source of heat. Problem with them is that they are low power for a given size relative to internal combustion, though they are uber-efficient.

In mpg ... (0)

Anonymous Coward | about 5 months ago | (#46884803)

75mph at 10kw, assuming 35% thermal efficiency, gives us 44 mpg. Not incredible but not bad.

Re:In mpg ... (1)

kenh (9056) | about 5 months ago | (#46884851)

About the same as an $18K Chevrolet Cruz Eco [chevrolet.com] , which claims 46 MPG in the diesel variant...

Re:In mpg ... (2)

pushing-robot (1037830) | about 5 months ago | (#46884881)

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.

Re: In mpg ... (0)

Anonymous Coward | about 5 months ago | (#46884935)

I don't understand how you calculated that since there are so many missing variables. However the research paper stated 42% efficiency.

Bill Gates has allready patented this. (1)

Anonymous Coward | about 5 months ago | (#46884805)

Embrace.
Extend.
Extinguish!
http://jalopnik.com/5210372/bi... [jalopnik.com]

The vibration must suck (1, Interesting)

drinkypoo (153816) | about 5 months ago | (#46884823)

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.

Re:The vibration must suck (1)

Zeussy (868062) | about 5 months ago | (#46884903)

They can be horizontal opposed in motion in the parallel twin design. This will give some second order imbalance though. Piston rings don't fail all the time, or you would see new cars blowing blue smoke all the time. They gradually wear out.

Re:The vibration must suck (1)

Whatsisname (891214) | about 5 months ago | (#46884911)

Right, because I'm sure the engineers at Toyota haven't thought about this kind of stuff.

Re:The vibration must suck (1)

drinkypoo (153816) | about 5 months ago | (#46885065)

Right, because I'm sure the engineers at Toyota haven't thought about this kind of stuff.

They build stuff they have no intention of producing all the time, they can still afford shit like that because people still want their cars.

Re:The vibration must suck (1)

mjwx (966435) | about 6 months ago | (#46885777)

Right, because I'm sure the engineers at Toyota haven't thought about this kind of stuff.

They build stuff they have no intention of producing all the time, they can still afford shit like that because people still want their cars.

It's called Research and Development.

Things like VTEC didn't pop into your Honda overnight, the technology was developed over decades until it became good and cheap enough to be put into everyday use.

Re:The vibration must suck (1)

sexconker (1179573) | about 5 months ago | (#46885165)

Right, because I'm sure the engineers at Toyota haven't thought about this kind of stuff.

Oh I'm sure they thought of it. Probably decades ago. And decided it was an inferior design. This is only being trotted out in an effort to distract from all-electrics from Tesla, Nissan, Ford, etc. There is no indication that Toyota plans to use this design in any product.

Re:The vibration must suck (5, Informative)

Anonymous Coward | about 6 months ago | (#46885485)

Free piston engines have a distinct difference with respect to vibration. They can potentially couple a lot less vibration to the chassis than traditional designs because the vibration is only in one plane and there is no need to couple the engine to the chassis to provide torsional reaction force for the drive train.

The vibration of any individual component doesn't matter, only the vibration that is coupled to the chassis of the vehicle. With a free piston design, there is no need to couple the engine directly to anything because you have no output shafts to couple to the drive train, and no mechanical reaction forces to contain. That means that the body of the engine can be decoupled from the chassis of the vehicle in the axis of vibration, and *allowed* to vibrate back and forth as much as it needs to. That provides the reaction force to the piston, and the forces coupled to the chassis are only the frictional loss in your mounting system.

Re:The vibration must suck (2)

Required Snark (1702878) | about 6 months ago | (#46886105)

Why was this modded down? If I had mod points I would mod it up.

All I can assume is that some anti-green ideological idiot wants to shoot down any thing that makes good sense and saves energy.

I assume that they are political conservatives, since it fits their typical behavior. I wonder if the Koch (pronounced COCK) brothers are somehow involved.

Not an engineer'car guy, but... (1)

kenh (9056) | about 5 months ago | (#46884825)

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 [howstuffworks.com] and be done with it?

Re:Not an engineer'car guy, but... (1)

jonwil (467024) | about 5 months ago | (#46884987)

Isn't the Chevy Volt PHEV exactly like that? Its got a gasoline engine that powers a generator that powers an electric motor that powers the wheels. It also has batteries you can plug in and charge up though.

Re:Not an engineer'car guy, but... (2)

gman003 (1693318) | about 5 months ago | (#46885011)

Rather than the cylinder driving a crankshaft, they're driving a linear alternator directly (basically an inverse solenoid - turning linear back-and-forth motion into electric current). That ought to lead to less losses from inertia and friction, as well as being more compact.

Re:Not an engineer'car guy, but... (0)

Anonymous Coward | about 5 months ago | (#46885037)

How is this not just a one cylinder engine? Based on the description, that's what it sounds like.

No crankshaft and it generates electricity directly instead of turning a generator - making it more compact and lighter weight. Although, it will have the same problem as all internal combustion engines - lot's of wasted heat. If only that heat can be captured and turn into electricity.

Re:Not an engineer'car guy, but... (1)

amorsen (7485) | about 5 months ago | (#46885041)

Diesel electric locomotives are horribly inefficient and heavy.

Re:Not an engineer'car guy, but... (0)

Anonymous Coward | about 6 months ago | (#46885813)

Diesel electric locomotives are horribly inefficient and heavy.

Citation needed on the efficiency. Heavy is merely an attribute of the scale of the equipment it must move. A light locomotive would have reduced friction between the steel wheels and the rails, which would reduce the towing weight regardless of how much power it produced.

Re:Not an engineer'car guy, but... (1)

amorsen (7485) | about 6 months ago | (#46885985)

They are just regular crappy diesel engines plus an inefficient electrical power train. Efficiency is not particularly a concern for freight trains; fuel is a small part of the operating expenses.

why not develop the solar magnet star cars? (0)

Anonymous Coward | about 5 months ago | (#46884847)

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?

Good Lord, man... (1)

Chris Mattern (191822) | about 5 months ago | (#46884853)

...you've invented the alternator!

Some things that make you go "Hmmm" (1)

grmoc (57943) | about 5 months ago | (#46884855)

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.

Re:Some things that make you go "Hmmm" (1)

Jmc23 (2353706) | about 5 months ago | (#46885211)

So what you're saying is it'll sell like hotcakes in the type of small cars women drive?

Re:Some things that make you go "Hmmm" (1)

Blaskowicz (634489) | about 6 months ago | (#46885689)

The synchronization would have to be between the electronic control units. So it can be implemented by running e.g. an ethernet cable between the two engines.

Re:Some things that make you go "Hmmm" (1)

Bing Tsher E (943915) | about 6 months ago | (#46886183)

Any piece of wire will do. Sure, use an ethernet cable.

Why not generate in both directions? (0)

Anonymous Coward | about 5 months ago | (#46884865)

Why not generate in both directions, and get AC current?

Re:Why not generate in both directions? (1)

Paradise Pete (33184) | about 5 months ago | (#46885435)

Why not generate in both directions, and get AC current?

And add one more after that, giving you 3D current, an essential ingredient in building the flying car.

Transduction mechanism? (1)

oldhack (1037484) | about 5 months ago | (#46884887)

How's the back-and-forth motion converted to electric power?

Re:Transduction mechanism? (1)

Carnivore (103106) | about 5 months ago | (#46885015)

The "mover" (same function as a rotor, but is linear instead of rotational) is pushed past the stator by the explosions. This also compresses a gas spring which returns the cylinder to the starting point when it rebounds.

Re:Transduction mechanism? (0)

Anonymous Coward | about 5 months ago | (#46885195)

You don't need rotational movement to drive an alternator. A magnet can move back and forth inside a coil and generate AC.

Re:Transduction mechanism? (5, Funny)

VortexCortex (1117377) | about 5 months ago | (#46885267)

You don't need rotational movement to drive an alternator. A magnet can move back and forth inside a coil and generate AC.

Wait, what? That's all it takes to create the AC? The last time I checked the accepted theory involved a stork.
What's motivating all those cowards to turn the car wheels? I feel like I'm missing something...
Perhaps a Unix analogy?

Re:Transduction mechanism? (0)

Anonymous Coward | about 5 months ago | (#46885359)

It's called a "linear alternator" [wikipedia.org] .

Basically it's like one of those "shake flashlights" [wikipedia.org] .

Fuck a Mare (-1)

Anonymous Coward | about 5 months ago | (#46884895)

and the bootom Don't walk around Fact: *BSD is dying That the project Shower Don't just I read the latest Lite is straining then disappeared

"Directly" (1)

kruach aum (1934852) | about 5 months ago | (#46884929)

So chemical energy generates mechanical energy which then generates electricity. This is not what the word "directly" means.

Re:"Directly" (1)

im_thatoneguy (819432) | about 5 months ago | (#46885231)

Yeah this definitely isn't a direct electrical generator. But it could be far more easily distributed throughout a vehicle. Instead of every piston needing to be mechanically linked you could have them spread throughout the car and arranged somewhat arbitrarily (except for vibration considerations). So from that perspective they are kind of direct in that electricity comes directly out of a self contained unit instead of needing an engine connected to an alternator. Each piston is creating electricity. Technically even some sort of fusion plant isn't "directly" creating electricity unless the electrons just decided to leave the gasoline of their own free will. Even a solid state device like a peltier generator isn't "directly" extracting electricity, it's converting thermal to electricity. This isn't "directly" extracting electricity but it is just about as directly as is physically possible extracting electricity from the mechanical energy of combustion.

Why use the gas chamber? (3, Interesting)

140Mandak262Jamuna (970587) | about 5 months ago | (#46885163)

The description talks about using a gas chamber as a spring to push the piston back to starting position. Why? There is no crank shaft on the other side? We could imagine a dual acting piston with a combustion chamber on both sides. In a regular IC engine there is a flywheel to do the intake, compression and exhaust strokes soaking up the energy from the power stroke. Even with a dual acting piston, there is an issue there.

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.

Make a vehicle with a single one? (1)

Blaskowicz (634489) | about 5 months ago | (#46885249)

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)

Rotational Energy Conserved (0)

Anonymous Coward | about 5 months ago | (#46885291)

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.

I saw "Directly" and thought MHD. (1)

jeffb (2.718) (1189693) | about 5 months ago | (#46885305)

At least, a magnetohydrodynamic generator [wikipedia.org] 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...)

engineering heaven (2)

PopeRatzo (965947) | about 5 months ago | (#46885313)

Felix Wankel is somewhere laughing his ass off.

Re:engineering heaven (0)

Anonymous Coward | about 6 months ago | (#46885663)

Haha, really tho. I had to search all comments to see that someone mentioned it(Was my first thought).

https://en.wikipedia.org/wiki/Wankel_engine

Would still seem to be superior. I would how the two would compare fuel per energy out.

Re:engineering heaven (1)

rahvin112 (446269) | about 6 months ago | (#46885865)

The last (AFAIK only) Wankel engine every built commercially got 8MPG. It also proved to be a son of a bitch to maintain because the seals would go bad and it would require a total engine rebuild.

A paragon of efficiency and simplicity the Wankel engine is not.

Re:engineering heaven (1)

PopeRatzo (965947) | about 6 months ago | (#46885995)

Actually, it looks like they build quite a few different versions of the Wankel, from little econobox models to screaming twin-turbos.

And according to most sources I've seen, they only get about 1 to 3 mpg worse mileage than a similarly powered piston engine. But hey, (and this is one of those rare times when the phrase really applies), your mileage may vary.

Re:engineering heaven (1)

ArhcAngel (247594) | about 6 months ago | (#46886025)

The Mazda RX8 [wikipedia.org] got up to 23 MPG.

Re:engineering heaven (1)

DigiShaman (671371) | about 6 months ago | (#46885697)

Elegant design, and lots of HP per liters of displacement. The problem is that you often run into carbon fouling and the apex seals break. They also need oil metered in with the fuel as there isn't an oil sump. Now combine the need to burn oil with the fact a combustion cycle doesn't have enough time to stay in the chamber and you have pollution. It's why the entire length of the exhaust system is one giant catalytic converter.

Now if they can make a diesel Wankel with strong enough apex seals, now you're talking!

Re:engineering heaven (1)

PopeRatzo (965947) | about 6 months ago | (#46885969)

I don't know nothin' about no apex seals, but I drove a '93 RX-7 a few times and that thing would push you down against your seat back when you hit the gas. It was a twin turbo and the owner told me it was getting close to 400 bhp, but I can't say one way or the other, but man, I liked that car.

Old concept, but might work. (1)

joe_frisch (1366229) | about 5 months ago | (#46885379)

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.

Re:Old concept, but might work. (1)

Blaskowicz (634489) | about 6 months ago | (#46886121)

I read about free piston engine about one year ago, and it described a single piston going back and forth.
Very interesting that the concept was devised in the 50s, it makes me think that the flying car was invented in the 50s as well. Only it was uncontrollable and not worth for anything except hovering over the ground for 30 seconds or such.

Load More Comments
Slashdot Login

Need an Account?

Forgot your password?