Rumor: Volkswagen Group may sell Ducati

AJV80 said:

My bad mate, your right, I was sure I saw a video of it years ago with them being all electric ... but I think thats just how I imagined and remembered it over time.

I know they can vary lift, opening and closing times. But you're right they use pneumatics (and tiny springs) to do the heavy lifting with electrical coils to vary timing and lift i assume.

Coil control is nothing ground breaking tech wise but given the size of the solenoid coil you would need to drive an engine valve open and shut it wouldnt imagine it being easy, probably why it hasn't been attempted. Crude example but simply connecting a low excitation current 24VDC relay in a 240VAC 50hz supply by mistake and they have a chattering heart attack then in seconds then melt trying keep up to the 50hz cycle which is about 3000 cycles a minute/ :

https://www.youtube.com/watch?v=Bch5B23_pu0

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Great video, thanks for that!

As I mentioned to Dr No, they are indeed profiling the speed for the final approach to the seat, to protect the valve. They don't say how they do that but it looks like natural, first order damping so, maybe some kind of pneumatic shock absorber? Did you hear for sure that they use an electrical component for actuator?

Regarding VS drives, the only reason they have resistor banks is for regenerative breaking, servos are an appropriate analogy and no such requirement there.

Your experiment to fry a 24V relay by connecting it to 240 V, 50 Hz is not really apropos mate [emoji39]

In a real situation, as well as having a capable mechanism, they would regulate the current to be constant and not leave it up to the natural (very small) resistance and the inductance of the coil. This is done with super-duper switch mode power supplies with a closed loop current regulator and with sufficient voltage headroom behind it to overcome any back-emf from inductance or voltage drop from resistance, to force the current (and therefore force) to the required profile.


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Cool Blue said:

Mate, check out the video posted by @AJV80. They show the waveform for the valve position and you can see how they slow it down as it approaches the seat. So, it's like a cam lobe with a square front and an initially square back that tapers to a normal profile for the final few (cam shaft) degrees.


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Will do. Once I access my VPN and a decent connection.

Found an article on EVA. They (a pretty dodgy investor-pitch) mentioned something about a power requirement of 250W at 5000rpm for a single valve. So making some hefty assumptions and extrapolating that out: 50W/1000rpm/valve. Hence a 4v 4cyl at 16000 would be in the order of 13kW to run the system (or perhaps half that since it's a ....... 4T and half the time the valve is sitting doing jack ....). Nice fat power source needed to run that.
The Cargine being pneumatic probably places less power demands on its control valves. But electrickery mostly goes over my head...so more investigation required.

Dr No said:

Will do. Once I access my VPN and a decent connection.



Found an article on EVA. They (a pretty dodgy investor-pitch) mentioned something about a power requirement of 250W at 5000rpm for a single valve. So making some hefty assumptions and extrapolating that out: 50W/1000rpm/valve. Hence a 4v 4cyl at 16000 would be in the order of 13kW to run the system (or perhaps half that since it's a ....... 4T and half the time the valve is sitting doing jack ....). Nice fat power source needed to run that.

The Cargine being pneumatic probably places less power demands on its control valves. But electrickery mostly goes over my head...so more investigation required.

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Yes, your assumption is fine: power is the same for each valve lift so linear with RPM but, at best 50% efficiency for the actuator/power supply and 50% for kinetic to electrickery conversion, so that's actually 12.8 standard toasters (1 ST = 250 W) for each valve at 16000.

Damping however is a different matter, can put a rare earth magnet in the valve stem (costing inertia) and a winding around the guide, with an electronic switch connected to a resistor. Could even bung a "winding" into the stem, aluminum rings for example and move the magnets into the actuator to avoid mass penalty on the valve. This would give the first order damping I saw in the video.

Can you re-inflate air bags? Maybe there's an application for tiny little air bags to seat the valve [emoji12]

von Koenigsegg explained they had plans for a compressed air storage tank on their prototype. The other advantage of pneumatic is that it's already available, no weight or energy conversion penalties.