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Fully digital valves open up engine possibilities

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Re: Fully digital valves open up engine possibilities

#11

Post by ak217 »

mkstowegnv wrote: post #7
rmason wrote: post #2

It seems in tech just when the incumbents seem like they will lose to the upstart they achieve a breakthrough and the inevitable is delayed for a few more years. Combine this breakthrough with what Michigan State is doing in gas powered engines and battery powered cars dominance is delayed for at least another decade. http://www.wkar.org/post/reworking-michigan-msu-develops-lig...

The inherently self destructive nature of ICE's make it likely that ICE vehicles will always be more complex, less reliable/ higher maintenance than comparable all electric vehicles. The simplicity advantage of electric will soon take a quantum leap when driveshaft-free 4 motor all wheel drive vehicles hit the market [1]. On the other hand as long as batteries are heavy, ICE's will have a place in aircraft, and I wou…

> The simplicity advantage of electric will soon take a quantum leap when driveshaft-free 4 motor all wheel drive vehicles hit the market

You can't just eliminate the driveshaft because the wheel must be on a suspension. Remove the driveshaft and you have to put the motor on the wheel, increasing unsprung weight, exposing the motor and making high voltage parts subject to damage.

4 motors is more complex than 2 and doesn't buy you much except in niche packaging applications (like buses). As far as torque vectoring, you can achieve the same effect with differential braking (the duty cycle of torque vectoring is very short, so you don't lose any efficiency). A 2-motor Tesla is probably already the optimal passenger car configuration.

Agreed on everything else though.

Re: Fully digital valves open up engine possibilities

#13

Post by jondumbau »

jondumbau wrote: post #12

The temporary 2 stroke idea doesn't sound very well cooked. Fine control over the valves is great, but the exhaust and other aspects of the engine need to be tuned for that use case.

Also the "2 strokes are the future" remark seems a bit off too. The future of enduro bikes and chainsaws maybe.

Re: Fully digital valves open up engine possibilities

#14

Post by jondumbau »

Nitpicky, but compression release for easy (easier..) starting is already a thing. It talks about completely opening the valves so the starter only overcomes friction. Presumably they're talking about having the cylinders that aren't yet fired spinning over freely? Otherwise it's a very efficient way to spin and engine that can't possibly start without "compressing gasses".

Re: Fully digital valves open up engine possibilities

#15

Post by hevi_jos »

ak217 wrote: post #11
mkstowegnv wrote: post #7

Earlier quoted context omitted.

The inherently self destructive nature of ICE's make it likely that ICE vehicles will always be more complex, less reliable/ higher maintenance than comparable all electric vehicles. The simplicity advantage of electric will soon take a quantum leap when driveshaft-free 4 motor all wheel drive vehicles hit the market [1]. On the other hand as long as batteries are heavy, ICE's will have a place in aircraft, and I wou…

> The simplicity advantage of electric will soon take a quantum leap when driveshaft-free 4 motor all wheel drive vehicles hit the market You can't just eliminate the driveshaft because the wheel must be on a suspension. Remove the driveshaft and you have to put the motor on the wheel, increasing unsprung weight, exposing the motor and making high voltage parts subject to damage. 4 motors is more complex than 2 and d…

4 electric motors on wheels is extremely simpler than 2 motors, mechanical differentials and couplings.

I actually helped a mechanical engineer to create a simulator for car dynamics in software.

Today's cars are over engineered mechanically in order to support and resist the forces and torques from the motor to the wheels.

When you put the motors in wheel you basically reduce the required rigidity and the weight of the car substantially.

You point out some disadvantage of the approach. The biggest disadvantage of all is that is not a proven technology, like 100 years old driveshaft. That means the company that commercializes it will eat all the risk, like what happens when people exposes the motor-wheels to wet surfaces and some part of it is damaged. The lawsuits could bankrupt even the biggest company.

Re: Fully digital valves open up engine possibilities

#16

Post by dsfyu404ed »

mkstowegnv wrote: post #7
rmason wrote: post #2

It seems in tech just when the incumbents seem like they will lose to the upstart they achieve a breakthrough and the inevitable is delayed for a few more years. Combine this breakthrough with what Michigan State is doing in gas powered engines and battery powered cars dominance is delayed for at least another decade. http://www.wkar.org/post/reworking-michigan-msu-develops-lig...

The inherently self destructive nature of ICE's make it likely that ICE vehicles will always be more complex, less reliable/ higher maintenance than comparable all electric vehicles. The simplicity advantage of electric will soon take a quantum leap when driveshaft-free 4 motor all wheel drive vehicles hit the market [1]. On the other hand as long as batteries are heavy, ICE's will have a place in aircraft, and I wou…

>when driveshaft-free 4 motor all wheel drive vehicles

Two words: unsprung weight.

CV shafts are gong nowhere for the foreseeable future.

Re: Fully digital valves open up engine possibilities

#17

Post by ak217 »

rmason wrote: post #2

It seems in tech just when the incumbents seem like they will lose to the upstart they achieve a breakthrough and the inevitable is delayed for a few more years. Combine this breakthrough with what Michigan State is doing in gas powered engines and battery powered cars dominance is delayed for at least another decade. http://www.wkar.org/post/reworking-michigan-msu-develops-lig...

I wouldn't put either free valves or the "wave disk" engine on the list of technologies likely to affect mass produced ICE efficiency in the next decade or two. HCCI/SCCI gas engines with VVT, variable displacement, and cylinder deactivation are very close to full scale production though, and promise very substantial improvements. Mild hybrid (electric regenerative braking and assist with a small battery/large capacitor) gives another boost, though at a substantial complexity cost (not nearly as bad as a full hybrid though).

Re: Fully digital valves open up engine possibilities

#18

Post by ak217 »

hevi_jos wrote: post #15
ak217 wrote: post #11

Earlier quoted context omitted.

> The simplicity advantage of electric will soon take a quantum leap when driveshaft-free 4 motor all wheel drive vehicles hit the market You can't just eliminate the driveshaft because the wheel must be on a suspension. Remove the driveshaft and you have to put the motor on the wheel, increasing unsprung weight, exposing the motor and making high voltage parts subject to damage. 4 motors is more complex than 2 and d…

4 electric motors on wheels is extremely simpler than 2 motors, mechanical differentials and couplings. I actually helped a mechanical engineer to create a simulator for car dynamics in software. Today's cars are over engineered mechanically in order to support and resist the forces and torques from the motor to the wheels. When you put the motors in wheel you basically reduce the required rigidity and the weight of…

I agree with you. I should have clarified - 4 motors in the arrangement envisioned by Honda (see the link above) is more complex than 2. It doesn't eliminate any of the driveshafts.

I don't think we'll see in-wheel motors any time soon for the reasons you and I mentioned. (Also, in high performance applications (anything but econoboxes) won't you need to strengthen the suspension/chassis in some places even as you get to lighten it in others, since the motor is now torquing the rest of your suspension?)

Re: Fully digital valves open up engine possibilities

#19

Post by TheSpiceIsLife »

jondumbau wrote: post #14

Nitpicky, but compression release for easy (easier..) starting is already a thing. It talks about completely opening the valves so the starter only overcomes friction. Presumably they're talking about having the cylinders that aren't yet fired spinning over freely? Otherwise it's a very efficient way to spin and engine that can't possibly start without "compressing gasses".

Exhaust valves are open during the exhaust stroke anyway. Inlet valves are open during the intake stroke anyway.

The strongest plausible interpretation of what¹ they're saying is to open valves that are partway through the compression stroke, and open / close any other valves as necessary at the best possible time to promote rapid starting.

1. https://news.ycombinator.com/newsguidelines.html

Re: Fully digital valves open up engine possibilities

#20

Post by justinclift »

tomatotomato37 wrote: post #3

I thought koenigsegg was already doing this with their freevalve thing Also I saw an interesting point in an article about the koenigsegg thing that would pertain to this too; environmental laws would be much harder to practically enforce with this as you could run virtually any engine anemic enough to get though the emissions tests (and set it as the default mode to get around the Volkswagen nonsense) and then offer…

After market engine modding would be interesting too.
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