Is the Leaf front-wheel drive?

[Volusiano]

Somebody asked me if the Leaf is front-wheel drive or all-wheel drive and I wasn't sure what the answer is. I'd imagine that it's front-wheel drive since the motor is located up front under the hood, and there's no drive shaft going to the rear wheels.

Then that same person asked me why don't they put the motors independently inside each wheel so they can truly have all-wheel drive in that sense. I told them that they may do that in future cars, but for now it's probably cost prohibitive to break it out into 4 motors instead of just 1.

Of course all of this is guessing on my part.

I thought I read somewhere that it was one of the brainstorming ideas when GM looked into developing the Volt. To have a common electric platform with independent motor inside each wheel, and put whatever shell on top, like a car shell or SUV shell or minivan shell.

 

[LEAFfan]

It's front-wheel drive.

 

[johnr]

Yes, the Leaf is front-wheel drive. There are lots of ideas floating around, and all-wheel drive in-wheel motor EVs are being explored by some manufacturers, but I think Nissan doesn't consider the technology ready yet for mass-market. For one thing, it increases un-suspended weight, and for another, it could have cost and reliability issues. But yeah, all wheel hub motor drive has some intriguing potential.

 

[Anonymous]

My [limited] reading on hub motors is that they are incredibly efficient and make for a very powerful and effective drive system, but they are very expensive and means you have more points where failure can happen (as johnr eluded to). Very cool, and in the future highly possible, but just not ready for mass market right now.

Think of how Subaru made a name for themselves by having AWD be a standard. I'd see other companies doing similar things with different technologies like this once EVs really take off in the market. Of course, even for a 2WD vehicle it might be beneficial (in terms besides cost) to have hub motors as well.

 

[aqn]

The LEAF is front wheel drive. I imagine just about any specs sheet you can find on it will say so, e.g. at edmunds.com.

The electric Jaguar C-X75 concept car has four motors. I don't know if the motors are integral/inside the wheels or not i.e. whether or not the motor is unsprung weight (weight not supported by the car's suspension, such as wheel, tire, brake components etc.). I would hope not: more unsprung weight = poorer suspension performance.

 

[Volusiano]

The LEAF is front wheel drive. I imagine just about any specs sheet you can find on it will say so, e.g. at edmunds.com.

Funny that you said this. I went on the Nissan Leaf website looking for information on this under the Features/Specifications link and came up with nothing about whether it's front or rear or all wheel drive. Is there anywhere on the Nissan Leaf website that mentions this?

 

[aqn]

The LEAF is front wheel drive. I imagine just about any specs sheet you can find on it will say so, e.g. at edmunds.com.

Funny that you said this. I went on the Nissan Leaf website looking for information on this under the Features/Specifications link and came up with nothing about whether it's front or rear or all wheel drive. Is there anywhere on the Nissan Leaf website that mentions this?

Yeah, I know. In fact, I looked at all the "official" specs and documents and found no mention of "front wheel drive". I had to go to my old reliable, edmunds.com, to see it mentioned. Maybe it's one of those things nobody cares about anymore or just takes for granted, like whether the car has power brakes; or headlights, or a windshield.

 

[Herm]

Both hub and regular motors are very efficient already, around 92% for combined motor and inverter losses. You wont see any until some company (probably Chinese) starts to manufacture and sell an integrated hub motor/inverter unit for a reasonable price.. it would save the cost of the CV joints, halfshafts and differential but you would have to buy a whole second motor/inverter. I doubt it will ever make economic sense, car manufacturers worry about $0.50 parts, let alone another whole motor.

An electric bus company is doing this already.. for packaging reasons on a low slung 40ft bus.

 

[intrepion]

The LEAF is front wheel drive. I imagine just about any specs sheet you can find on it will say so, e.g. at edmunds.com.

Funny that you said this. I went on the Nissan Leaf website looking for information on this under the Features/Specifications link and came up with nothing about whether it's front or rear or all wheel drive. Is there anywhere on the Nissan Leaf website that mentions this?

The only way I could find it was to use their search box and I got this

http://www.nissanusa.com/leaf-electric-car/faq/view/33

 

[UkrainianKozak]

Volvo had a ReCharge concept with wheel hub motors 4 years ago
http://www.gizmag.com/go/7975/

But they moved away from it in their production C-30, so looks like that did study it extensively and decided not to go with wheel motors... But I can't find any source that would say the real reasoning why they dropped it... I bet everything comes down to the cost at the end, current technology exists to produce a viable wheel hub motor.

 

[garsh]

Hub motors aren't going to be popular because they add unsprung weight, which generally results in poor handling.

 

[mxp]

The LEAF is front wheel drive. I imagine just about any specs sheet you can find on it will say so, e.g. at edmunds.com.

The electric Jaguar C-X75 concept car has four motors. I don't know if the motors are integral/inside the wheels or not i.e. whether or not the motor is unsprung weight (weight not supported by the car's suspension, such as wheel, tire, brake components etc.). I would hope not: more unsprung weight = poorer suspension performance.

It uses the Michelin Active wheel.
http://armdevices.net/2011/06/27/michelin-active-wheel-electric-traction-suspension-breaking/

I have a brochure about it and there are a number of concept vehicles trialling this. By adopting this technology, it frees up space for other components such as a larger battery.

I saw this technology in person at a technology event and also had a chance to speak with the engineers from Switzerland.

 

[Herm]

Michelin's Active Wheels system fixes the unsprung weight issue by replacing the coil spring and shock absorber with linear motors.. other companies have done the same by replacing the iron disc brake rotor with an aluminum one, and then using strong regen braking to compensate.

 

[garygid]

Remember, in an EV, Regen usually only works when the battery pack is sufficiently discharged to handle quite-fast charging, so the mechanical brakes SHOULD be "bigger", not less capable.

 

[davewill]

Remember, in an EV, Regen usually only works when the battery pack is sufficiently discharged to handle quite-fast charging, so the mechanical brakes SHOULD be "bigger", not less capable.

You could always design the system to waste the regen into a dummy load if you wanted to rely on it when the battery was charged. You'd have a lot of heat to dissipate, but you have that with friction brakes, too.

 

[Herm]

You could always design the system to waste the regen into a dummy load if you wanted to rely on it when the battery was charged. You'd have a lot of heat to dissipate, but you have that with friction brakes, too.

Just like diesel electric locomotives do.

Not sure how aluminum disc rotors would work, it does dissipate heat a lot quicker than iron. Perhaps a special alloy.. and it would solve the rusting issues that iron rotors have in BEVs.

 

[aqn]

It uses the Michelin Active wheel. ...
I saw this technology in person at a technology event and also had a chance to speak with the engineers from Switzerland.

I don't think the Jaguar C-X75 uses Michelin's Active Wheel, or even a motor-in-hub arrangement: it uses one motor per wheel, driving the wheel via a shaft (which IMHO would be the smart way to do it):

http://www.insideline.com/jaguar/jaguar-c-x75-concept-first-drive.html
"There are four electric motors, each developing 145 kW (the equivalent of 195
horsepower). They're actually mounted in pairs fore and aft along the
centerline of the car as if they were differentials, each driving its own axle
shaft and wheel."

Did you actually see Michelin Active Wheels on the Jaguar C-X75?

Also, the brakes on the C-X75 are conventional disc brakes:
http://www.jaguar.com/us/en/about_jaguar/news_pr/cx75
"...disc brakes..."

http://www.caranddriver.com/news/car/10q3/jaguar_c-x75_concept-auto_shows
"The brakes are from the supercharged XFR sedan..."

http://www.jaguar-cx75.com/jaguar-cx75-specifications
"...brakes used on the supercharged XFR...
...380 mm internally ventilated front discs and 345 mm rears..."

Michelin's Active Wheels system fixes the unsprung weight issue by replacing the coil spring and shock absorber with linear motors.

I'd say it "addresses the unsprung weight issue" rather than "fixes" it: there is still a mass (wheel, tire, and now motor and pinion) whose up and down movements need to be controlled, only now it's controlled by an electric motor instead of by a spring and damper. It is still true that the smaller that mass, the easier it is to control and the better the suspension's performance.