SAAB is Back

[MarkMas]

Apparently SAAB is back with an EV.

 

[MarkMas]

With 4 'in-wheel' motors. So in principle you could replace all four wheels (and wheel-bearings!) in your QPV or GT with those, and put loads of batteries somewhere.

 

[Ebenezer]

How does unsprung weight change with this sort of set up?
@Zep to the answer phone
Eb

 

[highlander]

if they can get this to production with the 600 mile range, it could be the game changer for EVCs people have been waiting for........a big IF though.

 

[tokyomb]

How does unsprung weight change with this sort of set up?
@Zep to the answer phone
Eb

The explanation given in the video is that it is the ratio of unsprung mass to overall mass that matters - and as such a heavy EV can accommodate higher unsprung mass than a lighter vehicle (with appropriate modifications to springs / dampers). Not sure how true that is, but there is clearly some very clever torque-vectoring also going on with this car that make it a lot more nimble than it looks.

 

[zagatoes30]

Clever, in wheel motors have been around for ages some of the industrial machines use them so why not a car

 

[Zep]

How does unsprung weight change with this sort of set up?
@Zep to the answer phone
Eb

The short answer is yes, it will make the wheel heavier. The ratio to overall mass is important because if you have a light body and a heavy wheel the firmer damping needed to control the wheel mass will just move the body instead, making the ride terrible. It’s all about inertia, for the wheel and the body.

There are some interesting things thrown up by this. Space saving, reduced components, reduced power losses in transmission are pros, cons are less wheel control, no options for gearing which could blunt acceleration.

 

[Motorsport3]

The unsprung weight ratio is reasonably well explained. My concern is heat management. I would expect these wheels to be getting really hot in highway run.

 

[Oneball]

if they can get this to production with the 600 mile range, it could be the game changer for EVCs people have been waiting for........a big IF though.

Unlikely as they went bust last year. This prototype has been dragged out of a Swedish shed by the Chinese company that makes the in wheel motors.

 

[33Nikaea]

The great thing about in-wheel electric motors is that torque and horsepower can be adjusted on the fly without relying on braking any particular wheel. Since the battery packs are lower than gasoline engines and usually tanks, the CG is low and even with that unsprung weight, they handle like stink. I spoke to Michelin a lot about that and Venturi in Monaco. Why we don't see them too often is mostly because there are only a handful of chassis makers out there and designing a car with in-wheel or in-hub electric motors, or EVs in general is outside the scope of what they do. I was hoping Canoo was going to kick up the heat there but it still hasn't happened.

As to SAAB, they've been working on that EV since the late 2000s and I hope they can make it.

 

[CatmanV2]

Hmm, software defined handing. Interesting idea. I'm kind of feeling the motors are quite exposed, but they're not really 'in wheel' are they? They're effectively 'in hub' and the wheel bolts directly to it

C

 

[33Nikaea]

Hmm, software defined handing. Interesting idea. I'm kind of feeling the motors are quite exposed, but they're not really 'in wheel' are they? They're effectively 'in hub' and the wheel bolts directly to it

C

There are different ways of doing it. In hub is where the motor is connected to the hub directly and in wheel means connected to the wheel, mostly through a cog system.

As far as exposed, there are electric motors made to handle military aircraft in desert operations. Depending on how good those electric motors are, they should weather storms, no pun intended. Michelin was working on this in 2007 already and other companies are still working on it. Protean is a good example of in hub. https://www.proteanelectric.com/ There was another newer EV maker that wants to use hydrogen but I forgot their name.

 

[CatmanV2]

There are different ways of doing it. In hub is where the motor is connected to the hub directly and in wheel means connected to the wheel, mostly through a cog system.

As far as exposed, there are electric motors made to handle military aircraft in desert operations. Depending on how good those electric motors are, they should weather storms, no pun intended. Michelin was working on this in 2007 already and other companies are still working on it. Protean is a good example of in hub. https://www.proteanelectric.com/ There was another newer EV maker that wants to use hydrogen but I forgot their name.

Ahh, OK. But I'd still say that it's not 'in wheel' as in part of the wheel any more than my discs and pads are 'in wheel'

Still looking interesting

C

 

[Zep]

if they can get this to production with the 600 mile range, it could be the game changer for EVCs people have been waiting for........a big IF though.

Wait a while and it will be so. Google One Next Energy Gemini. A dual chemistry battery with Lithium Iron Phosphate (LFP - note, no cobalt) or motive battery and an anode free manganese storage battery. When the LFP battery runs low it gets charged by the Manganese battery. Current range? 752 miles.

The unsprung weight ratio is reasonably well explained. My concern is heat management. I would expect these wheels to be getting really hot in highway run.

I doubt the heat would be an issue, these motors will be very efficient and if you can cool brakes which have very high peak energy dissipation, you can cool a motor.

 

[33Nikaea]

Ahh, OK. But I'd still say that it's not 'in wheel' as in part of the wheel any more than my discs and pads are 'in wheel'

Still looking interesting

C

Not sure I understand your reply. The electric motors in both cases are inside the wheel. Proterra is a bigger bus type of wheel. I'm not sure what they do now but at some point the inside part of the wheel was the stator and the outside the rotor. Micheline had an electric motor geared onto the hub and the other directly put the electric motor connected to the hub directly. In all these scenarios they are inside the wheel. Generically, it's called in-wheel, but there are subtleties in how they are designed mechanically.

 

[33Nikaea]

Wait a while and it will be so. Google One Next Energy Gemini. A dual chemistry battery with Lithium Iron Phosphate (LFP - note, no cobalt) or motive battery and an anode free manganese storage battery. When the LFP battery runs low it gets charged by the Manganese battery. Current range? 752 miles.



I doubt the heat would be an issue, these motors will be very efficient and if you can cool brakes which have very high peak energy dissipation, you can cool a motor.

Everyone is moving to oil-cooled electric motors these days.

For the best battery energy density I'm aware of, Amprius has 450 kWh packs using silicon. It's not commercialized yet but it's a proven chemistry. These packs are tested in the wild as we speak. They are testing 500 kWh cells and beyond in their labs right now, which is what is needed for aviation.