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Scientists Claim Major Leap in Engine Design
An anonymous reader writes "Purdue researchers say they have made a major advance in the design of the internal combustion engine, one that could seriously boost fuel efficiency and cut emissions. A key portion involves building intake and exhaust valves that are no longer driven by mechanisms connected to the pistons, a departure from the way car engines have worked since they were commercialized more than a century ago. 'The concept, known as variable valve actuation, would enable significant improvements in conventional gasoline and diesel engines used in cars and trucks and for applications such as generators, he said. The technique also enables the introduction of an advanced method called homogeneous charge compression ignition, or HCCI, which would allow the United States to drastically reduce its dependence on foreign oil and the production of harmful exhaust emissions. The homogeneous charge compression ignition technique would make it possible to improve the efficiency of gasoline engines by 15 percent to 20 percent, making them as efficient as diesel engines while nearly eliminating smog-generating nitrogen oxides, Shaver said.'"
Are they going to do anything useful, like, say, actually boost milage? Or are they going to continue what they've been doing and just increase horsepower and torque?
But they don't actually talk at all about how they WILL drive the cams. And for that matter, they still have cams! Driving valves with solenoids somehow would be more meaningful. If they're keeping the cam, then they can have variable timing easily enough, but they're still going to need a bunch of additional hardware to control lift and duration. Of course, it takes a lot of power to use solenoids to drive the valves, which is why they're not doing it now. Personally I'm far more interested in Coates rotary valves, which have been used in racing. They let you raise RPMs dramatically without having an exploding valvetrain. Combine that with direct injection and I'll be pleased as punch.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Nothing spectacular about changing the timing on the valves depending on how the engine's being driven:
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http://en.wikipedia.org/wiki/Variable_valve_timin
According to Wikipedia, VVT has existed since the 1960's. The only improvement I can see (and that's from reading between the lines) is that they've developed a means of controlling it more precisely.
All the benefits will be squandered on making bigger, heavier vehicles. At least, that's what's been happening with improvements in efficiency since the 80s. Sigh...
No matter how efficient an internal combustion engine gets, it will still emit carbon dioxide. While this technology might help an engine spew less carbon dioxide, it's still a dead end -- kind of like putting lipstick on a pig.
Put the effort into other forms of energy and we'll be a lot better off a lot more quickly.
It's not just Purdue working on this, nor is it cutting edge. The idea of variable valve actuation has been around for a while as well as HCCI, which has some problems that are yet to be overcome. One of the notable ones that I recall is simple power. As the Wikipedia article notes, in a gasoline engine, you increase the fule/air charge to increase power. In a diesel engine, you just inject more fuel. In an HCCI engine, it's tough because "many of the viable control strategies for HCCI require thermal preheating of the charge which reduces the density and hence the mass of the air/fuel charge in the combustion chamber, reducing power. These factors makes increasing the power in HCCI inherently challenging."
For more info, the Wikipedia page has some great references:
- Research, publications at Lund University
- Research at Chalmers University of Technology
- Research at Stanford University
- Research, publications at University of Wisconsin, Madison
- Research at University of California, Berkeley
So, it's got a lot of benefits but a few trade offs that need to be addressed first. Honestly, why would Ford/GM buy this out and kill it when they could just develop the technology themselves and integrate it into their vehicles like Hitachi's research? I mean, just because technology changes doesn't mean they should kill it instead of changing with it, right?My work here is dung.
None. Why would GM or Ford kill anything that would give them an advantage over Honda or Toyota?
Your Tinfoil hat is on too tight again.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
You selected the wrong entry from the Standard List of Villains. The correct comment would have been:
"What's the chance the EVIL OIL COMPANIES will buy this out and kill it?"
This is not news. BMW has been playing with this for years. So has Mercedes -- they call it EVT, for Electronic Valve Train. And next year it will ship in the 2008 C-Class sedan.
FATMOUSE + YOU = FATMOUSE
from the blurb:
...which would allow the United States to drastically reduce its dependence on foreign oil...
Editor doesn't know much 'Murkins, does he? This will be used to create higher-horsepower, heavier cars, not more efficient ones. Coming soon: The Hummer Canyonero-Magnum!
Remain calm! All is well!
Yeah, mechanical valve actuation has its problems. It makes for either non-optimal valve placement (standard wedge heads) or overly complicated mechanical actuation trains (see Chrysler original Hemi engine design). So a better method to actuate valves than driving it from a fixed, or fixed-variable, design could make for better engine performance overall. That's hardly new. As best I've seen, this has been merely an engineering problem to determine a better way to actuate valves that meets the requirements of cost, durability, cost, performance, and cost -- when it comes to consumer engines. While such an actuator method is certainly significant news in and of itself, it's not like someone has redone the whole engine.
"It's the height of ridiculousness to say for those 9 lines you get hundreds of millions."
The problems with batteries are that they have poor energy density (even the theoretical energy density of a chemical battery is less than that of gasoline) and that they take a lot of energy to produce. They also tend to be based around substantial quantities of toxic, polluting materials; the refinement of those materials is further detrimental to the environment. Fuel cells with liquid fuels produced by nuclear, solar, wind, hydro, or biofuels (or taking biofuels directly) do much better along potentially all of these lines.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
The trouble with direct valve actuation is making an actuator that's fast enough, powerful enough, small enough, heat-tolerant enough, and reliable enough to do the job. Cheaply. This is not easy. Prototypes have been built, but it's still not something that's easy to do. BMW did quite a bit of work in this direction, but backed off to their "Valvetronic" scheme, which still has a camshaft with other components to give some adjustment potential.
Most of the existing schemes for tweaking valve timing still involve camshafts, but there's an additional mechanical linkage which allows adjustment of phase angle, valve travel, or both. That's an idea which goes back to steam engine design. Most of the gear on the side of a steam locomotive is there to adjust valve timing. Steam engines are controlled by valve duty cycle, not throttling. This was the original pulse-width-modulation system. On steam engines, valve phase can be adjusted far enough to reverse the engine, which is how locomotives back up. Some newer marine diesels have that feature, too. Eliminates the need for a reverse gear.
So this isn't a new idea. It's an old idea that's hard to make work cost-effectively. Somebody may crack this thing; it's a tough mechanical engineering problem, but not an impossible one.
This article, as has been, and will be, pointed out throughout the comments is not news, very interesting, or likely to yield much of practical value.
..., reduce the number of humans by 6 billion, or so. Unless you do that, nothing else will matter. Additional terrestrial hydrocarbon fuel resources are becoming quite hard to reach and there's too much demand to get by easily on biological sources alone. Improving the efficiency by which we use the fuel helps us, regardless of the other issues.
Non-crankshaft-linked valve timing, whether through variation mechanisms that are in current street car use, or electric/pneumatic/hydraulic actuators, such as the F1 engines have used for years do not solve the problem of heat control. Burning fuel (which is why some parts of the combustion chamber are hotter than others; get a clue) generates heat. Some of that heat expands gases to push pistons (or rotors) and a lot of heat raises the temperature of the engine components. Without cooling the engine, the accumulated heat destroys the materials. This is why my air-cooled Ducati engine has a lower power output than the water-cooled Ducati engine of the same (roughly) displacement. The water-cooled engines can keep the components at a lower (and more consistent, I know) temperature, so they can use more air and fuel to generate more power (the extra valves are only usable because the additional heat can be managed).
The real solution is to use more of the chemical energy to provide power for moving the vehicle and less of it to heat the components. Trying to store the energy in rechargeable batteries will result in mostly short-range urban and novelty vehicles for a very long time, since the energy density of the storage, both in mass and volume, and recharge rate are pathetic compared to diesel, gasoline, or compressed propane/methane.
The "hydrogen solution", applied as an internal combustion fuel, has the same problems, plus the additional headaches of generating the hydrogen ("but solar is cheap" - and it will compete directly for surface area with homes, farms, and the large-scale installations needed to power your iPod's recharger since we'll be trading power between sunlit and darkened regions) and transferring it between fuel station storage and vehicle storage. Hydrogen fuel cells, still with the generating, storage, and transfer problems, are pretty good at converting between chemical and electrical energy, and electric motors are usably efficient at converting electrical energy into motion.
What we need are fuel cells that can handle ALL of the chemical energy in a hydrocarbon fuel, converting not just the stored hydrogen and oxygen from the air into water (2 H2 + O2 = 2 H2O; put energy in to break up the hydrogen and oxygen molecules then get energy back by combining the hydrogen and oxygen atoms into water), but also using the carbon atoms in the fuel molecules to make CO2 which gives a larger net energy output by mass of fuel.
As for "CO2 is a greenhouse gas": So what? We're already too far down the path. The paleohistoric record of ice-age cycles shows that we have already passed the inflection point to cooling while we're accelerating the heating. If you want to reduce the CO2 footprint of humans, along with ending overfishing of the oceans, sucking the deep aquifers dry, destruction of the rain forests for farmland, habitat destruction for either human use or by diversion of fresh water resources, pollution by agricultural runoff,
I'm a complete idiot when it comes to car repair, but in 1976 I replaced the head gasket on my Oldsmobile Rocket 350 V8 with a couple of adjustable wrenches. Super easy to work on.
I remember when the heater core went -- no sweat, pull the hose off the heater core input, plug it back into the block, done deal. Six months later when I had the money I pulled the heater core and replaced it.
Front bearings need to be repacked? Piece of cake. Just don't forget the cotter pin that holds the whole damn wheel on, and you're good to go.
Car was unbeatable in a straight line. Handled like crap otherwise, though, but who cared. Nothing like a 350 with a racing transmission and a 4 barrel off the line, baby.
Nowadays, I open the hood and it's a sea of hose assemblies and pipes, can't even see the block. If you buy the shop manual, you find out the first thing you need is a zillion-dollar set of metric torque wrenches before you even start. Screw that.
Then the solenoid went on my Honda Accord, and I found out you can't buy a solenoid any more. You have to buy the whole "alternator assembly" which includes alternator, solenoid, voltage regulator, and God knows what else -- to the tune of $400. I came THIS CLOSE to ripping the goddamn "alternator assembly" apart and fixing the solenoid myself, except I actually have to work for a living. So frustrating.
Well, no actually. A rotary such as the current Mazda 1.3 litre simply spins faster than the equivalent piston engine. The volume passed per unit of time is the relevant comparison, not the static displacement.
Since the RX8 competes with similar HP sports cars by guzzling at SUV rates, it indicates Mazda's best effort so far is still inferior in power conversion of the gasoline. (Though the smoothness is great fun.)
As for turbines, same deal really. The aircraft turbine has yet to match piston engines on efficiency for short flights. You have to run long-haul at cruise altitude before the overall fuel consumption is lower.
The idea of a completely spinning engine is very seductive, but the actual results of forty years of careful research has not delivered a spinning engine that's better than the 'tossing potatos'. This is counter intuitive, and it's entire worth your while to dig into the studies to find out why that is.
To me, modern vehicles are eminently more reparable than the old ones, but that's because I'm an electronics geek I suppose. Because the thing is mostly fly-by-wire, it's dead easy for me to go in with a laptop and dump the codes to figure out what's wrong with the system.
Take for example my friend's VW Bug... Engine was running rather roughly, and showing the "check engine light". Plugged in my laptop, dumped the codes, and one of the diagnostic codes was showing a vacuum line failure. Sure enough, we replace the appropriate vacuum line, engine runs fine after that. Sure, a seasoned mechanic would probably have figured that one out immediately, but to an office geek like me, the electronic diagnostics were a godsend.
The primary difference between modern vehicles and the ones from the days of yore is that there is a different skill set required to work on them. Now, on top of being able to turn a wrench, you need electronics and computing experience.
...si hoc legere nimium eruditionis habes...