Electronic valve control project

[rsafier]

There have been a number of attempts with rotary valves on 4-cycle engines, they always had sealing issues. There are a few companies out there that. This one has some web presence http://www.coatesengine.com/technology.html
Interesting stuff.

[AbeFM]

http://www.a-car.com/valves/rotary.html

Interesting conversation here, some folks who want to work together...

I remember seeing a harley that used some.

Also, here's a page I am surprised is still around:
http://www.dself.dsl.pipex.com/MUSEUM/P ... alveIC.htm

Many of these you could envision doing with a phasing modifier to turn on and off..


Neat! From Wiki:
Azzariti, a short lived Italian manufacturer from 1933 to 1934, produced 173 cc and 348 cc twin cylinder engines, some of which had desmodromic valve gear, with the valve being closed by a separate camshaft.

I like that, since you could phase shift the two shafts independently, to create a motor with greater overlap at high RPM, without the sudden change in profile inherent in the VTEC system.

Lastly, just interesting reading:
http://en.wikipedia.org/wiki/Sleeve_valve
Another, much more drastic, form of rotary valves, non-reciprocating.

For switching from 4 to 6 cycle, this might be diffifcult. I could envision some complicated things with flaps or alternate pairs of rings in different patterns, but I'd think it would be hard to realize in simple terms, mechanically....

[Wiglaf]

I'm not familiar with any 8-cycle concepts, but you could sure give it a shot

I'm been trying to figure out how i could retro-fit the current head for the valves but it's not looking too good.. I would rather have a new head machined if it meant that i could make the valve solenoid itself a little more generic/modular.. When people start hopping aboard there will be an issue of having hardware to play with. Either we all buy E30's (not a bad option) or some alternate heads get made. A one size fits all approach to the valves could make that a lot easier.

no worries, it will be a long long time before we are there. I'm still trying to gather up power supplies and tools to do my own bench testing.

for the crank sensor I've been considering an optical encoder wheel. I would like it to be absolute, at least to start just to avoid trouble. That would also let me try a "soft-start" idea of starting the engine without using a starter motor.
8 bit would identify 256 positions, about 1.4º accuracy. I don't think we need any more than that, MS controls the spark on mine just fine with a 36-tooth wheel. On that note 4 or 6 bit might be sufficient.

[ababkin]

...since you could phase shift the two shafts independently, to create a motor with greater overlap at high RPM ...

at least on bmw vanos engines, the higher overlap is only engaged from about 2krpm up to 5krpm and only past a certain load threshold. Past 5krpm, overlap goes back to minimal (as it is at idle). I hear retarding the intake cam at high rpm gives better cylinder fill. But i guess it's how you tune the whole system.

Wiglaf, why not make a 1/2cyl non-interference engine'd go-kart for the first prototype?

btw, i am sure one can fit m20 into even newer bimmers (since it's easy enough to put a newer bmw engine into an e30)

[GartnerProspect]

On the 8-cycle - I was conceptualizing the fact that based on the Crower 6-cycle design, it may be possible to have enough heat in the cylinder after the first water cycle to light off another water cycle.

With electronic control you have the option of adapting to this on the fly. Start on Fuel only, change to 6-cycle once operating temp has been reached. And if the operating temp increases switch to 8 cycle. I picture intelligent control and per-cylinder thermal assessment. If the engine design was clean slate design, I suppose it might be possible to eliminate the cooling system all together and rely soley on an oil cooler and the water cycles to regulate engine temp. Maybe a small exchanger for cabin heaters.

Of course, my worries are thermal fatigue. In Crowers original design I reckon he was spraying water directly onto the piston. In my napkin-cad design the nozzle actually put water stream more on the cylinder/head. I figured this would reduce the piston shrinkage/growth cycle. Also insert creative use of ceramic coatings to control heat. With a cylinder with thicker walls to retain heat and a head without as significant water passages, I'd assume warpage would be less of a concern. But it may change the way you have to think about head gaskets as there may be problems with sealing.

I was pondering the addition of a turbo charger to this arrangement. However, instead of using it to compress intake air, use it to capture electrically the last bit of the steam energy that I don't think can be fully utilized by a piston design.

I also haven't decided if there is going to be an overall net energy conservation by elminating the cam-shaft. Electricity isn't free, but I wonder if in a push-pull arrangement if you may simply gain efficiency just by eliminating the need to overcome a few hundred pounds of spring pressure per-valve.

Of course this is all coming from a shade tree wanna-be engineer. And I kind of went off on a pointless rant! I guess you could say this technology excites me, and I'm actually very happy to see I'm not the only guy out there thinking about it.

[AbeFM]

My guess is if you need to squirt water twice, you're doing something wrong (using the wrong fluid or the wrong amount).. But I think when you get the rest of it working, conciderations like that will be minor in comparison.

[GartnerProspect]

My guess is if you need to squirt water twice, you're doing something wrong (using the wrong fluid or the wrong amount).. But I think when you get the rest of it working, conciderations like that will be minor in comparison.

Well, you're pretty much bound to a few things with the water. While it's expansion ratio is really high, my thoughts are that it's expansion rate is relatively slow and increasing water volume only slows the phase change process. Atomizing the water as much as possible will help but I really have no concept of how much.

Because in most automotive engines the stroke is relatively short I have a feeling that a smaller volume injection of water over multiple cycles will do more to extract power from the phase change.

So you can drench the combustion chamber but most of that steam power is going out the exhaust valve.


On a different note I was also pondering the advantages of a mid-combustion injection of water as well. This may have a negligable impact on power or efficiency, but should have a positive impact on emissions vs. economy. When gasoline burns very lean, you can pick up efficiency at cruise, but your NOx emissions go way up. With water to keep combusion temps in check I think it might negate the NOx production of lean burn. Having electronic valve control also allows for dynamic exhaust valve control which can help pull exhaust gases back into the combusion chamber which also help emissions in certain circumstances.

[Wiglaf]

My guess is if you need to squirt water twice, you're doing something wrong (using the wrong fluid or the wrong amount).. But I think when you get the rest of it working, conciderations like that will be minor in comparison.

Well, you're pretty much bound to a few things with the water. While it's expansion ratio is really high, my thoughts are that it's expansion rate is relatively slow and increasing water volume only slows the phase change process. Atomizing the water as much as possible will help but I really have no concept of how much.

Because in most automotive engines the stroke is relatively short I have a feeling that a smaller volume injection of water over multiple cycles will do more to extract power from the phase change.

So you can drench the combustion chamber but most of that steam power is going out the exhaust valve.


On a different note I was also pondering the advantages of a mid-combustion injection of water as well. This may have a negligable impact on power or efficiency, but should have a positive impact on emissions vs. economy. When gasoline burns very lean, you can pick up efficiency at cruise, but your NOx emissions go way up. With water to keep combusion temps in check I think it might negate the NOx production of lean burn. Having electronic valve control also allows for dynamic exhaust valve control which can help pull exhaust gases back into the combusion chamber which also help emissions in certain circumstances.

I've had similar thoughts too. Both would require a direct-injection setup for the water. Since I doubt that two direct-injection setups would actually fit, the gas can get injected the regular old way through the intake. Either way the head will have a provision for direct injection.

I'd be happy to discuss this 6-cycle water injection thing more, but for this thread it's becoming a side-track. I brought it up simply as a possibility that opens with the valve control.

[GartnerProspect]

Sorry

Didn't mean to take over your thread.

[Wiglaf]

no worries, i'd just like to keep focused on the valve control itself here.