tiger1964

Perhaps better used on non-interference engines?

SpudRacer

Not true. High RPM gives you higher horsepower as long as the torque curve either doesn't drop off drastically or peaks high in the power band. So, more power in a smaller package a la the F20C / F22C. But, friction increases in a non-linear fashion with speed. So friction becomes a big concern as far as fuel efficiency is concerned. But then there are things you can do to combat friction as Honda did in the F20C / F22C.

You are right though that every moving part internal to the engine needs to be strengthened to accommodate higher piston speeds and the associated higher inertia levels. Pistons, connecting rods, crankshaft, bearings, flywheel, valves. Even accessory (A/C, power steering) pulleys, bearings, and belts need to be considered. Of course all of that could be detached and driven electrically.

A cool thing about this Free Valve technology for me is the elimination of between one and four heavy chunks of rotating mass(camshafts). It would seem that not having to accelerate and decelerate all that metal would make for a much more responsive engine with much lower inertial forces to worry about. I wonder what the parasitic drag of driving the camshafts takes away from say a quad cam V8 or a twin cam I4. I wonder if it helps or hurts balance?

All in all, this sounds like a real engineering breakthrough that's worth exploring. The freedom it gives designers to tune the engine seems like a huge potential step forward.

Teeks

High revving gets you a couple of things if your stuff flows right:

You can get efficiency at lower rpm while still getting power by revving the piss out of it.
Power is a function of torque and RPM.

I'd say cam design is a decent limitation of RPM in that you have to have a stronger spring to be able to have valves not float at higher rpm. F1 uses air modulated valves to make it precise and not have to worry about a stiff spring taking away from efficiency or a weak spring that will allow floating.

This is good tech for sure, and I hope it makes it to more production cars.
[/quote]

Not just valves, but hydraulic valve lifters can frequently be the limiting factor for max RPM. My Z4's engine hits peak power at literally redline. It's limited by the hydraulic valve lifters. The Z4M has mechanical valve lifters to address the issue. The problem is that mechanical valve lifters require adjustment and are more expensive because of it.

But yeah, infinitely adjustable valve timing and instant valve actuation will help efficiency through the entire RPM band. What's really interesting is if you couple this technology with a small motor/battery powered by regenerative braking, you have a formula for a high revving oversquare engine that still has awesome low end torque thanks to the motor. 10-11K redlines should be very doable when you don't have to worry about low end torque and can drop the stroke down to lower mean piston speed.

Koenigsegg is developing a similar tech. I'll find the video when I get home.
[/quote]

Cargine is a corporate partner with Koenigsegg, so it is probably the same tech.

tarheel91

High revving gets you a couple of things if your stuff flows right:

You can get efficiency at lower rpm while still getting power by revving the piss out of it.
Power is a function of torque and RPM.

I'd say cam design is a decent limitation of RPM in that you have to have a stronger spring to be able to have valves not float at higher rpm. F1 uses air modulated valves to make it precise and not have to worry about a stiff spring taking away from efficiency or a weak spring that will allow floating.

This is good tech for sure, and I hope it makes it to more production cars.
[/quote]

Not just valves, but hydraulic valve lifters can frequently be the limiting factor for max RPM. My Z4's engine hits peak power at literally redline. It's limited by the hydraulic valve lifters. The Z4M has mechanical valve lifters to address the issue. The problem is that mechanical valve lifters require adjustment and are more expensive because of it.

But yeah, infinitely adjustable valve timing and instant valve actuation will help efficiency through the entire RPM band. What's really interesting is if you couple this technology with a small motor/battery powered by regenerative braking, you have a formula for a high revving oversquare engine that still has awesome low end torque thanks to the motor. 10-11K redlines should be very doable when you don't have to worry about low end torque and can drop the stroke down to lower mean piston speed.

Koenigsegg is developing a similar tech. I'll find the video when I get home.
[/quote]

Cargine is a corporate partner with Koenigsegg, so it is probably the same tech.
[/quote]

Couldn't see the video at work, haha.

@slithr: Durability of the solenoids WAS the limiting factor twenty years ago when my boss worked on this stuff. However, 20 years is a long time and I'm sure improvements have been made.

@Spud: Increase bore, reduce stroke. Slower mean piston speed and a more optimized cylinder design for high RPM efficiency (oversquare engine has a horizontal surface area which means valves can be bigger).

fm_sd

I know Purdue has been working on this technology for awhile.

https://news.uns.purdue.edu/x/2007a/...erEngines.html

On the last picture is their camless variable valve test unit for a Cummins diesel engine.

https://engineering.purdue.edu/ME/Re...20Research.pdf

tarheel91

HCCI engines have been around for a long time. It's basically compressing the combustion mixture right up to the point of compression ignition (knock), similar to a diesel cycle, but still using the otto cycle. There are a lot of challenges beyond valve control, but that would certainly help. One of the biggest issues is just how quickly the sensors can get data. 1Mhz frequently isn't fast enough in these sorts of situations if you want to keep the cylinder from knocking.

Sound's like Purdue's PR group is going beyond what the engineers have actually found. It's probably more like, "Our VVA system could help with HCCI" instead of, "We can do HCCI!"

g0g3tt4

The idea of moving further down the line in the usage of this engine and using it as an air pump and stored energy instead of batteries was a nice way to turn usage and storage on its ear.
Encouraging vid to say the least.

RedCelica

http://www.youtube.com/watch?feature...&v=Bch5B23_pu0

20,000rpm?!?!?

I can only imagine how awesomely efficient having a "flat head camshaft" profile will be...man this is awesome. No more worrying about timing chains/belts breaking...oh wow...

PureFunction

free valve technology

tx2K

Somebody with deep pockets needs to do this to an S2000 just because