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Discussion in 'Auto News' started by GTPNewsWire, Mar 3, 2020.
Good. Finally Freevalve is making its production (ish) debut.
I disagree that large engines make more sense. The weight is a major issue, and regenerative braking is not 100% efficient, and a larger engine needs a larger body and that creates more drag. There will be a sweet spot between the electric network (external charging) efficiency, the thermal motor efficiency and the regen package efficiency.
A small-ish engine is definitely in that sweet spot. Not least because fewer cylinders are more efficient, and there is a practical upper unit capacity limit for a variable speed engine.
Oh, and here come the "rolling cylinder deactivation" schemes:
Tiny Friendly Giant:
It sort of appears as though each cylinder is plumbed to two separate 3-into-1 collectors, which is nuts.
Edit: It also appears to have a "valve pump", which is also nuts. Perhaps it's just lubricant.
Subsequent edit: Could also be coolant, but I keep going back to valve fluid. That would be a peculiar place to introduce (or retrieve) engine lubricant or coolant in the head.
I'm no engineer, but my instinct would be to use fluid under pressure to overcome valvesprings, and use solenoids to actuate valves whose purpose is to hold back said fluid. But then I don't know that this even has valvesprings.
This is worth a watch for anyone not familiar with Freevalve (from 2016):
I don't think they're using the poppet valves to control turbine bypass behaviour, as the turbines clearly have internal wastegates in the pictures. So the twin setup might instead be for response and / or "staged" boost (+2 bar peak?).
The actuation is (electro-)pneumatic, so it will indeed need a pump!
Just watched the Top Gear and Shmee's videos on the car. Loads of interesting tid bits not covered in the press release.
- Apparently the engine can also run on a 2 stroke cycle in some situations
- The hot & cold cupholders run on Peltier cycle, whatever that is
- Front headlights inspired by the very first prototype Koenigsegg CC
- Space for 4 suitcases (3 in back, 1 in frunk), one for each passenger
- The door hinge now also moves the door upwards (instead of just out and rotating) so you can park close to a kerb and still clear it
- Fixed roof means this car has highest torsional rigidity out of any 4 seater car
I'm still a bit perplexed by the choice to have a mid engine front wheel drive layout though. Surely having a traditional MR layout and then moving the 2 electric motors to the front will still leave enough space for a frunk, and the car will be even lighter without the driveshaft and extra set of diffs at the front? Then again, I don't have CvK's brain so I'm sure they went thru that iteration already and have a good reason why they went the current route.
Interesting, thanks for the easy to understand explanation. It is definitely counterintuitive for someone without an engineering background.
With GT Sport though, it's not as straightforward as "lower fuel map = more time loss than refuelling". In the FIA races last year we have very short races and very high multipliers where it's actually more beneficial to save the fuel on track than spending ages refuelling. With the OP slipstream you don't lose as much time in draft even with a low fuel map. Whereas if you go all out in addition to the refuelling you have to battle your way back thru the pack which costs you even more time. This year they have made the races 2x longer so yes, saving fuel on track costs too much time and you're better off going all out and refuelling.
Now see, that's just fascinating. The concept of internal throttling hadn't occurred to me either, but it's obvious in hindsight with so much control over valve lift.
Hypercars aren't my thing, but I like him.
Also found this computer animation detailing how the system functions:
Peltier device is a device that's basically a heat pump, but in solid-state (like a brick or plate). If your Fridge is a Cassette Tape a peltier device is a USB stick, but with tiny capacity.
You send power (+100) to the brick, and one side absorbs a little temp (-25W) and the other side tries to emit a lot of temp (+125W).
They're not very efficient, but they're small and have less parts than a refrigerant + compressor + radiator + evaporator cooling loop, and no chemical reliability/loss problems.
I could have sworn they changed the doors to go up a bit on one of the latter CCX / Agera models?
I can vaguely remember FWD being quoted as being '1MPG' better than RWD for passenger cars, but I can't figure out why. Only thing I can think of is that the loss of a longer driveshaft is offset by the links at the front being at their most efficient angle (straight ahead) during fuel testing cycles?
It could be that they wanted a weaker engine powering the fronts, and the powerful electric motors on the rear where most of the grip and load is, but had to just accept the packaging being a little weird. That way under hard acceleration they're getting something like a ~30:70 power split F:R which is ideal.
But then you've got the best generators on the rear axle which isn't ideal for regeneration under braking (rear-biased for regen = unstable, front-biased for performance = less regen).
In motorsport there's also hard break points, since pitting takes time (slowing for pit entry, traveling down the lane, stopping for fuel) and the fact that you can only pit once per lap (integer, not a fraction of a lap).
I think this might be a mis-quote in some way, it's more likely to be rolling cylinder deactivation. If not, this is pretty awesome - but it means the peak power figure for the thermo engine might be dubious if it's only in "some situations".
I already linked to a nice summary of research into an "8-stroke" three cylinder engine previously, as an extension / improvement to "standard" cylinder deactivation.
I had personally had the thought some time ago that you could switch to two stroke mode with such "free" valve operation, but a positive displacement "blower" is more reliable for this (think Detroit Diesel). Unless they allow the engine to "pop out" of two-stroke mode of its own accord when conditions are not viable - but that doesn't sound ideal to me.
2T: |o o o|o o o|o o o|o o o| 120°
4T: |o - o|- o -|o - o|- o -| 240°
8T: |o - -|- o -|- - o|- - -| 480°
I personally can't wait for a Freevalve (or similar) crossplane four with such "multi-stroke" capability...
This is perfectly believable once you start adding up all the friction from sliding contact in the drivetrain.
The mid-FWD concept feels a little like a retread of the NISMO LM project, just without the crippling restrictions on electric drive, regeneration and storage.
2T: |o o o|o o o|o o o|o o o| 120°
4T: |o - o|- o -|o - o|- o -| 240°
8T: |o - -|- o -|- - o|- - -| 480°
Just when I thought Koenigsegg couldn't get any dumber, they go and do a thing like this....
AND TOTALLY REDEEM THEMSELVES!
Seriously...this thing is bananas, in the best possible ways. CVK is a savant. Just imagine what kind of weird and beautiful creations could emerge if him, Musk, and Pagani worked together on something....anything.
I'm convinced Koenigsegg has staff meetings and just discusses the craziest ideas they can think of.
Like, "Alright folks. What innovative complex piece can we conjure up this time?" "...... How about a 1,700 HP 4 seater? ... With 4 individual engines?!" "STAMP IT! AND LET'S GET IT IN PRODUCTION"
Lmaoo all jokes aside, this car is actually pretty damn sexy to me. and has the insane engineering to support its look. Gotta love Koenigsegg's approach to making their cars.
According to the website (https://www.koenigsegg.com/gemera/engine-and-drivetrain/), the ICE+crankshaft e-motor's output to the front wheels is 1100 HP and the 2 rear motors provide 500 HP each (1000 HP combined). So actually there's slightly more power going to the front.
Someone pointed out also what happens when the batteries run out of juice? You'll end up with a 600 HP FWD with no torque vectoring to help The Nismo GT-R LM comparisons are starting to make sense
From the man himself, watch from around 7:30
The rest of your post is way over my feeble mind though. Thanks for the effort to explain regardless, I'm sure smarter people here will find it more meaningful
Imagine a round table meeting to make the perfect hypercar:
CvK in charge of powertrain
Pagani in charge of design
Rimac/Musk in charge of electrification
Gordon Murray in charge of packaging/materials/weight
Adrian Newey in charge of aerodynamics
The final hurrah for internal combustion before we all become mindless passengers in autonomous electric pods
Even with no e-juice, you can still use the e-motors as e-brakes
Can't wait to see how this two stroke lark works in practice, it's pretty crazy stuff.
Has the look of the Supra's body outline in the front 3 quarter view.
Ah so there is a regen system hooked up to the fronts (the crankshaft motor). In fact, that makes it even stranger that they've got the least capable electric system hooked up to the front. Presumably most of the recharging is going to be kinetic>electric (regen braking) not passive ICE>electric (generate from the rears or crankshaft motor while the fronts are ICE-powering the car).* So again you've got a max of 375kW (~500hp) charging from that front motor, and what, 225kW (~300hp) from the back 2 combined for a reasonable brake bias of 62% front, to drive 1125kW of motors?
If the hard braking from a straight into a corner takes 2s, you only generate ~1s of full boost, assuming everything is 100% efficient.
People, you're all free to check my physics on this one, I think I've got it right, but just in case I haven't...
*That could be done...I think the 919 had something similar where the top gear would try and regen while under full ICE power.
I suppose when the boost does run out, you should in theory be going fast enough that you're not traction-limited on power-down, so FDW wouldn't matter that much?
100% agree there's a lot of New Supra in there, along with a fair old chunk of Mercedes AMG-One.
Definitely not the work of art that the CCX was, where every line surface and fold was perfectly clean and crisp. Details are always the first thing to look outdated, and this probably won't age well.
Okay, so...Koenigsegg takes care of the engineering, including electric because he seems to have a handle on that. Pagani does the design work, but keep him away from the key. That leaves Musk, who...
...fosters a cult-like fanbase?
I thought the SEC banned him from doing that?
That sure is one expensive way to scare your whole family
I think the rear electric/front petrol arrangement was for handling and traction. A smallish engine geared for 200+mph is gonna be laggy as hell, so below like 70mph most of the available thrust comes from the electric motors. Surely at normal speeds a RWD bias is preferable.
As for a mid/rear engine, setup in a 4-seater? packaging.
It's a bummer they couldn't make it pretty. The last time they designed a car was in the 90s, since then it's been a parade of aero kits.
It promises full spool from 1700 rpm and peak torque from 2000 rpm.
This is very much not your average smallish engine.
Life must be a struggle when you're blind
Will the Freevalve system ever see use in regular cars? Or will it always be reserved for ultra-expensive hypercars?
In addition to the engine mapping flexbility Freevalve provides, don't forget also it has a whole 400hp e-motor sitting on the crankshaft helping it at low rpm, plus the KDD torque converter.
From what I can understand with my non-engineering background, normal variable valve systems are still pretty good in 99% of situations. That last 1% flexibility that Freevalve provides are cool, but it's marginal gains and doesn't make sense to put in normal cars at its current price point.
There's a fella from Greece who has lots of awesome designs and prototypes of various variable valve timing mechanisms conceived over several years. If you read a few of the descriptions, it adds up to a good discussion about how current variable valve technology is insufficient for the sustainability of the ICE.
In short, camshaft phasing alone compromises efficiency for emissions and variable lift technologies are not flexible enough to offer both peak performance and peak efficiency in the same package.
Freevalve basically makes all his mechanically variable prototypes obsolete and then some, except in high revving applications (for now).
And yes, there is Chinese interest in making Freevalve a mass market technology - this "LFG" engine should be considered an extended R&D platform (unless you're a potential customer, of course).
The electric future is not guaranteed globally, or especially any time soon anywhere, so I can see Freevalve (or equivalents) gaining traction quickly once proven.