The introduction of in-wheel motors for BEVs/PHEVs. When?

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edatoakrun

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This has been discussed before, but I thought it might be time for a dedicated thread, as IMO, this will be a major advance in PHEV/BEV engineering and design.

At 68 lbs for 75 kW, this would already seem to be a practical proposition for larger 4wd PHEVs (ICEV front wheel drive, electric rear?) and 2wd and 4wd BEV trucks/SUVs where the unsprung weight penalty of IWMs is not as significant as it is for smaller vehicles.

Protean Electric will introduce its production in-wheel motor at the 2013 Society of Automotive Engineers World Congress in Detroit.

Protean’s new production motor provides a 25% increase in peak torque compared with the previous generation’s design and can deliver 1,000 N·m (735 lb-ft) and 75 kW (100 hp), not quite keeping pace with the new industry benchmark.

Other features of Protean’s in-wheel motors include:


•Mass of only 31 kg (68 lbs) per motor.


•Up to 85% of the available kinetic energy to be recovered during braking...

http://www.electric-vehiclenews.com/2013/04/protean-unveils-production-in-wheel.html" onclick="window.open(this.href);return false;
 
What I found most impressive about it, is they claim the inverter is packaged in with the motor too.

So popping the hood of the LEAF, like 80% of what you see there, would either be unneeded (tranny) or in the wheel (motor, inverter).

Plus an independently controlled motor per wheel opens the door to better handling and tighter turning radiuses thanks to torque vectoring.
 
There was a thread on the Tesla Forums about this. Apparently it's a bad idea because it increases unsprung weight which is detrimental to handling...

http://www.teslamotors.com/forum/forums/why-not-inwheel-hub-engines" onclick="window.open(this.href);return false;
 
GeekEV said:
There was a thread on the Tesla Forums about this. Apparently it's a bad idea because it increases unsprung weight which is detrimental to handling...

http://www.teslamotors.com/forum/forums/why-not-inwheel-hub-engines" onclick="window.open(this.href);return false;

I'd like to think the same concept can be used on each wheel with a half shaft, mounting the motor solid to the body. Perhaps the motors for the right hand side wheels are on the left to make a long enough shaft for u-joint / constant velocity joint angles.
 
GeekEV said:
There was a thread on the Tesla Forums about this. Apparently it's a bad idea because it increases unsprung weight which is detrimental to handling...

http://www.teslamotors.com/forum/forums/why-not-inwheel-hub-engines" onclick="window.open(this.href);return false;


Why the multiple advantages of IWMs outweigh that one significant disadvantage, which does cause a "small performance deficit", according to Lotus engineering.

http://www.proteanelectric.com/wp-content/uploads/2012/10/The-Effect-of-Hub-Motors-on-Vehicle-Dynamics.pdf" onclick="window.open(this.href);return false;

As I mentioned in my OP, the first applications will be probably be in larger vehicles for which the superior load capacity, drive train efficiency, and/or 4WD performance, outweigh the disadvantage of higher unsprung weight.
 
If there was the slights variation in motor speed between the two sides, there would be immediate uncontrolled turning. Are the electronics of EV's sufficiently developed to prevent this?
 
SteveInSeattle said:
If there was the slights variation in motor speed between the two sides, there would be immediate uncontrolled turning. Are the electronics of EV's sufficiently developed to prevent this?
If you are talking about synchronous motors, like the LEAF has, that shouldn't be any problem at all, should it? In fact I would think the bigger problem would be dealing with differences in wheel speeds when turning.

Ray
 
planet4ever said:
If you are talking about synchronous motors, like the LEAF has, that shouldn't be any problem at all, should it? In fact I would think the bigger problem would be dealing with differences in wheel speeds when turning.
Our SL trim level LEAF certainly has a system for detecting steering position. You can see this sensor in action when backing as it creates curved lines to show where the car will go. It seems rather accurate so far. Assumedly these or similar sensors could be used to adjust for differential wheel speeds to allow a higher power level to be directed to the outer wheel(s) when turning.
 
Several technologies controlling the rotation of individual wheels so have to think its not a major challenge.

More interested if smaller lighter motors are out there. Seems like a lot of weight here. Granted a lot of weight is replaced bythis but we are talking X2 or X4?
 
planet4ever said:
SteveInSeattle said:
If there was the slights variation in motor speed between the two sides, there would be immediate uncontrolled turning. Are the electronics of EV's sufficiently developed to prevent this?
If you are talking about synchronous motors, like the LEAF has, that shouldn't be any problem at all, should it? In fact I would think the bigger problem would be dealing with differences in wheel speeds when turning.

Ray
But each motor has its own inverter.
Sublime said:
What I found most impressive about it, is they claim the inverter is packaged in with the motor too.
Therefore, the motors are not automatically synchronous to each other. In any case, you just need to do an electronic emulation of a differential.
 
Most "two-wheel drive" vehicles have open differentials, essentially meaning only one wheel is adding traction at any time.

The capability to have wheel motor on the same (or other) axle applying greater kW than the other(s) is one of the great benefits of WIMs, not a drawback.

Traction control, and all other computer controlled handling, will be greatly enhanced by the completely independent application of traction-power-by-wire to each wheel.

It could also be possible to have the individual wheel motors designed for optimum efficiency and performance at certain rpm and speed ranges, so that in low torque applications, such as steady speed cruising, the low speed motor(s) could be predominantly used in its (their) maximum efficiency range, with the high speed motor(s) taking over most or all of the job of laying out kW at higher speeds, at its (their) own optimal efficiency rpm and road speed.

This could largely replicate the motor efficiency benefits of a two-speed transmission (or a 4 speed, in a 4 WD BEV) without the cost and complexity and weight, of multiple gears, clutches, and drive shafts, that the Voltiacs claim to be such an engineering marvel in that two-motor-one-ICE Homer-mobile.
 
Another WIM project reported below.

Schaeffler will officially present their E-Wheel Drive electric wheel hub drive inside a Ford Fiesta at the “auto, motor und sport” congress in Stuttgard, Germany.

This electric Fiesta was produced in association with Ford as a “development vehicle,” so don’t look for this plug-in Ford at your local dealership anytime soon.

The Ford is propelled by twin E-Wheel Drives that are installed in the rear wheel arches. This in-wheel system includes all components required for “drive, deceleration, and driving safety in the highly-integrated wheel hub drive – like the electric motor, power electronics, controller, brake, and cooling system – are installed inside the wheel rim.”

Features of the drive units:

40 kW (110hp) per drive, continuous output of 2 x 33 kW (90 hp)
liquid-cooled wheel hub drive
delivers up to 700 Nm of torque
electrical voltage of the high-voltage drive is 360 – 420 V
total weight of 53 kilograms, or about 8 kg more than a traditional wheel and bearing
inside a 16-inch wheel rim

http://insideevs.com/got-it-schaeffler-puts-rear-e-wheel-drive-electric-fiesta-on-display/" onclick="window.open(this.href);return false;

What I want to know is, when will someone will put these on their LEAF's rear axle, lift the suspension, get some off-road wheels and tires and hit the Rubicon trail?

http://en.wikipedia.org/wiki/Rubicon_Trail" onclick="window.open(this.href);return false;
 
I think the other question that people rarely discuss is how durable the in-wheel motors would have to be to take the constant abuse direct shock operations.
 
redrunner said:
I think the other question that people rarely discuss is how durable the in-wheel motors would have to be to take the constant abuse direct shock operations.
Good Question. wondering If An In Wheel Motor Would Hav Survived My "Curb" Incident?
 
There are some of us that believe the main problem with In-wheel motors is not unsprung or sprung weight or poor sealing against dirt, sand, etc. or even maintaining the differental action. The problem is bearing wear. As many know, the closer the gap between the stator and rotor, the greater the torque. Maintaining this gap can be very difficult when you have the weight of the car carried by the in-wheel bearings and the gap measured in ten thousands of an inch? The slightest wear or movement can cause a rotor crash and an inoperative motor.

In fact, any damage to the rotor can ruin the motor.

Tony's suggestion of including a external shaft from each motor to the drive wheel would solve this problem; but, then you wouldn't have an in-wheel motor, would you? Well, maybe In-wheel motors aren't a good idea in the practical world!
 
Two more in-wheel motor BEVs in the news.

One a micro, in limited production, and the other a very ambitious (IMO) concept from Nissan:

What is it?

In the words of its creator Akihiro Yanaka, the Toyota i-Road combines “the manoeuvrability of a motorbike, with the economy and stability of a small family car.”

A tandem two seat three-wheeler, it tilts into bends while being steered from the rear by a tiny single wheel. Propulsion comes from a pair of electric motors located within the front wheels. In the UK it would be classified as a scooter, allowing it has a slightly disappointing 28mph top speed – for Japan this climbs to a more exciting 37mph - and has a range of just over 30 miles when driven with a bit of restraint, and 25 miles if you can’t resist extracting the most of its darting charms. It takes three hours to recharge.

The i-Road is intended purely as a set of urban wheels and promisingly, Toyota plans to trial it in both Toyota City, near Nagoya, and Grenoble in southern France as part of a 70-strong fleet of tiny electric tandem two-seaters entering service in autumn next year...

http://www.autocar.co.uk/car-review/toyota/first-drives/toyota-i-road-first-drive-review" onclick="window.open(this.href);return false;

And the Nissan BladeGlider concept, Xpost below from:

http://www.mynissanleaf.com/viewtopic.php?f=10&t=14949" onclick="window.open(this.href);return false;

edatoakrun said:
Insideevs has posted more videos and the press release from Nissan excerpted below.

Advances such as in-wheel motors and carbon fiber for weight reduction will both probably be commonplace in all BEVs soon, IMO.

I give Nissan a lot of credit for going long with the concept, but I want a smaller, lighter, more efficient and longer range sport BEV soon, so I hope Nissan either bring an Esflow into production in the next few years, or that it fast-tracks this next-generation design.

Yeah, the delta looks weird to our ICEV-formed conceptions of vehicle design, but if function determines this form, I hope Nissan has the guts to build it.


...A Provocative Shift in the Engineering Paradigm

With its narrow, 1.0 meter lightweight front track and wide, stable rear track, BladeGlider looks as if it could have sprung from a “skunk works” project. But the radical architecture all boils down to aerodynamics and balance. Having the front wheels close together reduces drag and enhances maneuverability for high G cornering power, assisted by its 30/70 front/rear weight distribution ratio. Aerodynamic downforce is created by the highly rigid yet lightweight carbon-fiber underbody, hence the lack of drag-inducing wings.

When BladeGlider matures into a production car, it could be Nissan’s first use of in-wheel motors. The in-wheel motors provide rear-wheel propulsion with independent motor management, while also contributing to freedom of upper body design and space-efficient packaging.

To power the electric motors, BladeGlider employs Nissan’s innovative lithium-ion battery technology, proven in Nissan LEAF. Battery modules are mounted low and toward the rear to enhance stability and handling.

Revolutionary Breakthrough in High-Performance Design

BladeGlider embodies a fearless vision of the EV future. Its tightly streamlined deltoid body comprises a tough and structurally optimized chassis wrapped in ultra-lightweight, yet strong and stiff, carbon fiber reinforced plastic (CFRP) finished in a pearlescent white color that evokes the pristine freedom of a glider. The racing-inspired exterior features a sculpted contour that is both functional and breathtakingly beautiful. Starting from the low, flat and narrow nose, the body line rises gracefully to the cockpit canopy and then curves forcefully back over the large rear wheels, evoking a sense of dynamic movement even when the vehicle is standing still...

http://insideevs.com/nissan-bladeglider-concept-headed-for-2013-tokyo-motor-show-wvideos/" onclick="window.open(this.href);return false;
 
Liquid cooling would be problematic as well. This may be a case of "good enough". I'm sure someone can pull off all of these technological marvels. At what cost, and what long-term reliability? And is the gain in performance worth the hassles when we already have pretty good traction and directional control technologies? And, considering that price point of EVs remains a pain point, these things might have to wait awhile except for exceptional supercar type applications.

I seem to recall a 4-wheel-motor EV that was reviewed a couple of years ago on FullyCharged, Transport Evolved or both.
 
edatoakrun said:
Two more in-wheel motor BEVs in the news.

One a micro, in limited production, and the other a very ambitious (IMO) concept from Nissan:

What is it?

In the words of its creator Akihiro Yanaka, the Toyota i-Road combines “the manoeuvrability of a motorbike, with the economy and stability of a small family car.”

A tandem two seat three-wheeler, it tilts into bends while being steered from the rear by a tiny single wheel. Propulsion comes from a pair of electric motors located within the front wheels. In the UK it would be classified as a scooter, allowing it has a slightly disappointing 28mph top speed – for Japan this climbs to a more exciting 37mph - and has a range of just over 30 miles when driven with a bit of restraint, and 25 miles if you can’t resist extracting the most of its darting charms. It takes three hours to recharge.

The i-Road is intended purely as a set of urban wheels and promisingly, Toyota plans to trial it in both Toyota City, near Nagoya, and Grenoble in southern France as part of a 70-strong fleet of tiny electric tandem two-seaters entering service in autumn next year...

http://www.autocar.co.uk/car-review/toyota/first-drives/toyota-i-road-first-drive-review" onclick="window.open(this.href);return false;

And the Nissan BladeGlider concept, Xpost below from:

http://www.mynissanleaf.com/viewtopic.php?f=10&t=14949" onclick="window.open(this.href);return false;

edatoakrun said:
Insideevs has posted more videos and the press release from Nissan excerpted below.

Advances such as in-wheel motors and carbon fiber for weight reduction will both probably be commonplace in all BEVs soon, IMO.

I give Nissan a lot of credit for going long with the concept, but I want a smaller, lighter, more efficient and longer range sport BEV soon, so I hope Nissan either bring an Esflow into production in the next few years, or that it fast-tracks this next-generation design.

Yeah, the delta looks weird to our ICEV-formed conceptions of vehicle design, but if function determines this form, I hope Nissan has the guts to build it.


...A Provocative Shift in the Engineering Paradigm

With its narrow, 1.0 meter lightweight front track and wide, stable rear track, BladeGlider looks as if it could have sprung from a “skunk works” project. But the radical architecture all boils down to aerodynamics and balance. Having the front wheels close together reduces drag and enhances maneuverability for high G cornering power, assisted by its 30/70 front/rear weight distribution ratio. Aerodynamic downforce is created by the highly rigid yet lightweight carbon-fiber underbody, hence the lack of drag-inducing wings.

When BladeGlider matures into a production car, it could be Nissan’s first use of in-wheel motors. The in-wheel motors provide rear-wheel propulsion with independent motor management, while also contributing to freedom of upper body design and space-efficient packaging.

To power the electric motors, BladeGlider employs Nissan’s innovative lithium-ion battery technology, proven in Nissan LEAF. Battery modules are mounted low and toward the rear to enhance stability and handling.

Revolutionary Breakthrough in High-Performance Design

BladeGlider embodies a fearless vision of the EV future. Its tightly streamlined deltoid body comprises a tough and structurally optimized chassis wrapped in ultra-lightweight, yet strong and stiff, carbon fiber reinforced plastic (CFRP) finished in a pearlescent white color that evokes the pristine freedom of a glider. The racing-inspired exterior features a sculpted contour that is both functional and breathtakingly beautiful. Starting from the low, flat and narrow nose, the body line rises gracefully to the cockpit canopy and then curves forcefully back over the large rear wheels, evoking a sense of dynamic movement even when the vehicle is standing still...

http://insideevs.com/nissan-bladeglider-concept-headed-for-2013-tokyo-motor-show-wvideos/" onclick="window.open(this.href);return false;

Nissan also has a vehicle like Toyota's as well. its a low speed, short range city commuter. speed up to about 40 mph and range of 30 miles but its really cool. its basically an enclosed motorcycle except that is considered "impossible" to tip over.
 
Hub motors suck, no other way to put it, plain and simple the RPMs are too low for a non-geared motor to be remotely efficient, add to that the fact that starting becomes much more difficult due to the very low starting torque. Sprung weight, honestly is meaningless, on the front its irritating but again mostly meaningless.

As built today they really only would be viable on a 1200lb or less car in non-mountainous terrain.

Now INBOARD hub motors, especially if run through a gear reduction or on small diameter tires (10"-13") would work OK
 
fotajoye said:
There are some of us that believe the main problem with In-wheel motors is not unsprung or sprung weight or poor sealing against dirt, sand, etc. or even maintaining the differental action. The problem is bearing wear. As many know, the closer the gap between the stator and rotor, the greater the torque. Maintaining this gap can be very difficult when you have the weight of the car carried by the in-wheel bearings and the gap measured in ten thousands of an inch? The slightest wear or movement can cause a rotor crash and an inoperative motor.

In fact, any damage to the rotor can ruin the motor.

Tony's suggestion of including a external shaft from each motor to the drive wheel would solve this problem; but, then you wouldn't have an in-wheel motor, would you? Well, maybe In-wheel motors aren't a good idea in the practical world!

Please allow me to quote myself.
 
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