New Engine Technology?

[centralcoaster33]

So, some people are designing a new type of engine. It is a rotary, but is not the Wankel design. Anyway, I saw a link about it and went to their website and found plenty more information.

Here is a link to a video on their website. Take a look around there. It seems kind of neat.
http://liquidpiston.com/technology/how-it-works/

The selling points are size and subsequently weight, a variety of fuel options, fuel efficiency, scalability, quiet and low vibration...
http://liquidpiston.com/technology/engine-benefits/


First thing that comes to my mind is side sealing at the side ports. Second, the 'apex' as found on a Wankel is gone, so maybe a better perimeter sealing option there with the larger surface, but greater friction? Finally, I see the RPMs of these and the power they make and wonder if they might be lacking in useful torque, I guess a properly designed transmission could deal with that...

What do you guys think about this design?

[ArmedAviator]

Still has alot of inherent problems that stem from the Wankel. I still don't see how this is any more efficient that the Wankel at high RPM (where it needs to be to produce any power). Seems alot of blow-by will happen. Also, it will still require that oil jets be fitted to lubricate the rotor which will end up causing all sorts of emissions issues.

Gas-turbine, A/C generator, and A/C motor all the way, baby.

[MinisterofDOOM]

The idea of multiple combustion cycles per crankshaft rotation is interesting. Where traditional Wankel-cycle rotaries operate best at high RPM, this one adds more efficiency to that by effectively splitting the displacement into three evenly-spaced phases across all 360 degrees of crankshaft rotation. You'd probably be making very little brake torque, maybe even less than a Wankel engine at comparable displacement. But you can always use gear reduction to make what you need from that. I suspect these engines would work great in generators, hydraulic pumps or other purposes where they can run at a specifically-designed optimal RPM.


The core problem with rotaries is one that piston engines overcame a long time ago: lack of mechanical valves. One of the strongest areas of optimization in piston engines over its history has been valve control. Going from reed valves (basically equivalent to what's happening in a rotary) to valve-in-block to separate intake and exhaust valvetrains and even separate active timing control and now even looking at individual per-valve, per-cylinder valve control. Aspiration timing control is HUGE for power, efficiency, and emissions. You have no method of control that in a rotary. You have an RPM-bound static intake and exhaust event and that's it. You can't modulate valve lift, duration, or timing, which are very important aspects of modern engines and the reason a modern engine can idle smoothly and then rev to 7500 and never miss a beat. The intake tuning that makes sense at 750rpm is different than the same at 2000rpm, or 4000rpm, or 6000rpm. But with a rotary, you just get one setting, and in an automobile you need to be able to cover the entire rev range without getting winded or you're going to struggle. If these rotaries like things best above 6,000rpm, they still have to idle somewhere efficient or they're impractical. And without the ability to change how it breathes along the way, you're going to end up compromising and not being very good at either end.

[centralcoaster33]

That's the kind of thinking I like to see! Explosions on all sides, I like that. 3 chambers instead of 2 should also help with that balance vibration stuff. Valves and intake are static. Maybe an extra plate could be added to each side that would rotate to change the opening size of the ports, similar to variable valve lift, but that's a whole new can of worms with more moving parts and more surface sealing and such. As it currently looks in their videos, I think you've found the weakness right away.

Generators and turbines. Diesel electric trains come to mind. These might not be the powerplants for automobiles, though they did make a go-kart and show a sort of drone plane. I wonder what they will be used for.