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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.
eh, goddamit.
10k kiowatt hours.
WTF is my coffee?? Good grief.
I've fallen off your lawn, and I can't get up.
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.
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
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?
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.
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.
10 kw is an interesting number for another reason, too -- 10 kwh is about the size of the average US home electrical draw.
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.
Disclaimer: Yes, I realize that outside North America, natural gas isn't cheap.
And it won't be cheap for long in the US. The natty gas industry is lobbying for it to become a "foreign policy tool." They want to ship it across the sea, somehow making it cheaper on the European market than Russian gas. I wonder who'll end up subsidizing that? The struggling US economy, or the almost bankrupt European economies, or Germany?
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.