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

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fotajoye wrote:

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...

maybe In-wheel motors aren't a good idea in the practical world!


rmay635703 said:
Agreed, to paraphrase, they suck, dirt, torque, reliability unsprung weight = suck.

Well, if Autocar is correct in it's BladeGlider report below, you may soon have a real-world test of your beliefs.

...the in-wheel electric motors...(have) been confirmed for the production car, a Nissan first...

"I've driven the prototype, and it is unlike anything I have sampled before," said Palmer. "This is the car that takes advantage of all the packaging benefits of an electric powertrain. All that weight and the set-up of the front racks means that the car is incredibly pointy, but the rear track and downforce mean that you can catch the oversteer with amazing ease."

Palmer confirmed the car will make production,...

http://www.autocar.co.uk/car-news/motor-shows/nissan-bladeglider-sports-ev-unveiled?page=1" onclick="window.open(this.href);return false;
 
edatoakrun said:
Well, if Autocar is correct in it's BladeGlider report below, you may soon have a real-world test of your beliefs.

http://www.autocar.co.uk/car-news/motor-shows/nissan-bladeglider-sports-ev-unveiled?page=1" onclick="window.open(this.href);return false;

I'm always capable of changing my views based on experience, hub motors have been for sale since at least 2003.

The folks who have used them in conversions have had a fair number of problems and have found they do not have enough starting torque to drive normal sized vehicles.

If a game changer comes along that changes or addresses the issues present on currently available hub motors then by all means, but until I can buy one easily and see it used in product style vehicles I have little patience for claims made for hub motors.

Check diyelectric car if you want lots of discussion on why hub motors suck.
 
They would be great if we had superconductors as there would be no weight issue. This is a way off, too much weight and other issues.
 
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've heard discussion about this amongst my EV-friends. Another argument against wheel motors is that they are placed in a very challenging, dirty, jarring, life-shortening environment, whereas they can be protected much more near the bottom of what used to be called the "engine compartment".
 
Lots of claims in the story below that remain to be proven.

First of course, is to see whether it actually will lead to a production vehicle.

The new (?) regen % claim (not to be confused with the usually much higher % recovery of ascent energy) certainly sounds better than the ~70-80% I believe you can get from the LEAF.

Issues of wheel bearings, increased torque, etc. also addressed in the full article, FWIW.


Protean Electric and FAW-VW developing production-intent electric propulsion system with in-wheel motors

12 December 2013


In-wheel electric drive developer Protean Electric is partnering with FAW-Volkswagen Automotive Co., Ltd. (FAW-VW) in China to develop a new electric propulsion system that will include Protean Electric’s Protean Drive with intent towards a demonstration vehicle program and production.

FAW-VW will create a new rear-wheel drivetrain for an electric vehicle (EV) based on the new Bora compact sedan, utilizing two Protean in-wheel motors. This cooperation began several months ago; all bench testing, engineering calibration and on-site application support is expected to be completed within a year. Protean Electric will also assist FAW-VW in the development of safety and vehicle controls that can be applied to additional vehicle programs.


This is a two-phase project that will capitalize on the torque and packaging freedoms that Protean Drive can bring to an automaker. Our technology will return the space to the new Bora vehicle platform that was formerly occupied by an in-board motor and powertrain.

The permanent magnet synchronous motors reside in the space behind the wheel. Protean’s new production motor provides a 25% increase in peak torque compared with the previous generation’s design and can deliver peak output 1,000 N·m (735 lb-ft) and 75 kW (100 hp), with 700 N·m (516 lb-ft) and 54 kW (72 hp) continuous. (Earlier post.) Protean says that its new production motor provides the highest torque and power density of any leading electric propulsion system.

In a paper presented at the EVS 27 conference in Barcelona, Gareth Roberts from Protean and Alessandro Galeazzi from SKF Automotive (a strategic partner of Protean), noted that:


The performance gain with respect to other more conventional arrangements is due to the full integration and synergies created with the mechanical components and in particular the wheel bearing. The final performance is connected to the ability of the wheel bearing to provide the required stiffness that controls the reduction of the air gap between the motor rotor and stator.


… There are three geometric factors that make up the motor air gap: the diameter Z, the motor length X and air gap length Y. For motor performance, it is desirable to maximise the diameter and motor length and minimise the air gap length.


The control of this air gap under different operating conditions is vital to ensuring efficiency and high levels of performance targeted by the In-Wheel motor. Road loads in their worst cases however, represent a significant challenge in maintaining the optimum level of air gap, hence the need to tightly control its variation. Furthermore, there is a risk of magnets touching the wound teeth if too much variation is allowed, with serious consequences for mechanical damage, performance and durability of the In-Wheel motor. The wheel bearing design and in particular the tilting stiffness, influence the design of the motor length and airgap length, which in turn influence the motor performance.

Protean engineers inverted the conventional motor design; the rotor is on the outside and the stator on the inside. This improves performance, makes it compact, and provides space inside the motor for power electronics and controls, the company says.

Each in-wheel motor, with an operating range of 200 - 400 Vdc, comes with its own integrated power and control electronics, which communicates with the vehicle by utilizing a common vehicle control system. Other features of Protean’s in-wheel motors include:
•Mass of only 34 kg (75 lbs.) per motor
•Integrated friction brake
•Superior regenerative braking capabilities, which allow up to 85% of the available kinetic energy to be recovered during braking
•Fits within a conventional 18" road wheel...


http://www.greencarcongress.com/2013/12/20131212-protean.html" onclick="window.open(this.href);return false;
 
In this configuration motor bearings are required to carry the load and abuse normally reserved for the wheel bearings. In an electric motor the spacing between the rotor and the stator are exceedingly critical and must be maintained within thousands of an inch. In fact the torque of the motor is indirectly proportional to this gap, i.e., the smaller the gap the larger the torque. If you have a bearing failure or excessive wear at the bearing, the motor can easily fail.

Hub wheels have been an engineering idea for almost a century.
 
fotajoye said:
In this configuration motor bearings are required to carry the load and abuse normally reserved for the wheel bearings. In an electric motor the spacing between the rotor and the stator are exceedingly critical and must be maintained within thousands of an inch. In fact the torque of the motor is indirectly proportional to this gap, i.e., the smaller the gap the larger the torque. If you have a bearing failure or excessive wear at the bearing, the motor can easily fail.

Hub wheels have been an engineering idea for almost a century.


Correct. There is a reason why there have been dozens of announcements of companies working on in wheel motors, some of them quite large corporations with lots of resources, and every one of them sort of fades away and then later practically disavows ever working on such a project. The technical obstacles are just too difficult to become practical. Motors are not designed for all the various load angles that a automotive wheel will place on it. The motor will get damaged with the slightest movement. It works great when everything is new, but after 20k miles you not only need new tires, but also a new wheel motor; seem like some very expensive maintenance.
 
Even for a 2-seater using the JC08, impressive efficiency claimed for SIM's latest prototype.

A ~150-freeway-miles-range-2-seater happens to be what I would want for my next BEV.

In Japan, it seems the forth time's a charm. Meet SIM-HAL, the latest prototype from SIM-Drive and its partners...

Standing for "High efficiency All-wheel Link", HAL celebrates the company's continuing technological progress, boasting its latest "light-weight/high efficiency SS motor." These units are capable of an impressive 65 kW (87.17 horsepower) and 620 Nm (457.28 pound-feet) of torque each. Multiplied by four, that's 260 kW (348.7 hp) and 1,829.15 lb-ft of twisting force. Apply those numbers to the pavement in the 1,510-kg (3,329-pound) car and you're hitting 100 kph (62.14 miles per hour) in a respectable 4.7 seconds. Top speed is capped at 180 kph (111.8 mph).

While we, of course, love performance, efficiency is what really counts when it comes to electric vehicles. Here, the two-seater raises both eyebrows and the corners of lips, coaxing 404.1 km (251.1 miles) from its 35.1 kWh lithium battery using the somewhat generous JC08 protocol. That works out to a very economical 86.9 Wh/km (139.91 Wh/mile)...

http://green.autoblog.com/2014/04/02/sim-drives-latest-wheel-motored-prototype-is-a-sporty-coupe/" onclick="window.open(this.href);return false;
 
Don't get me wrong; I hope someday the tech problems can be solved for hub motors; the advantage of having everything inside the rim is enormous. I can't think of a better EV configuration than to have the inverter, brakes,suspension, and motors at the four corners and the battery in the bottom center; think of all that space.
 
http://sunswift.com/eve.html" onclick="window.open(this.href);return false; are hoping to have their vehicle road registerable next year.
 
Yet another benefit from applying torque to each wheel individually.

I expect this would probably increase tread life also, unless you get into the habit of making a lot of very tight turns by opposite side wheels in reverse drive directions...

Torque Vector Steering Improves Electric Vehicle Energy Efficiency

Germany's Karlsruhe Institute for Technology along with industry partner Schaeffler are researching improvements in electric vehicle energy efficiency by using brake steer or torque vector control of wheel motors to assist power steering.

The project "Intelligent Assisted Steering System with Optimum Energy Efficiency for Electric Vehicles (e²-Lenk)" subsidized by the Federal Ministry for Education and Research (BMBF) focuses on a new assisted steering concept. In conventional vehicles, the internal combustion engine not only accelerates the car but also supplies on-board assist systems with energy; such as the assisted steering system, which reduces the strain on the driver at the wheel.

In electric vehicles, this energy comes from the battery and also reduces the range as a result. In this research project by the collaborating partners, Karlsruhe Institute for Technology (KIT) and Schaeffler, the steering system is assisted in an energy-efficient manner by intelligent control of the drive torques transmitted to the individual wheels. The project is being sponsored by BMBF with a sum of around 0.6 million euros over 3 years and was started in January 2015.

"The new assisted steering system would require less system components in an electric vehicle, this would mean savings in terms of weight and energy in an electric vehicle", explain project managers Dr. Marcel Mayer, Schaeffler, and Dr. Michael Frey, KIT. "This would mean that an electric car would be cheaper and have a greater range." Materials and production steps can be saved due to the potential optimization of the design and weight.

The basic idea of the e²-Lenk project is simple: The wheels in an electric car will be driven individually by electric motors in contrast to a car with an internal combustion engine where all the wheels are provided with equal force. If the wheels on the left side transmit more drive torque to the road than those on the right side, this will result in acceleration of the vehicle to the right without the need to turn the front wheels or consume additional energy for steering...
http://www.electric-vehiclenews.com/2015/04/torque-vector-steering-improves.html" onclick="window.open(this.href);return false;
 
We've heard it all before, but that doesn't mean we don't enjoy listening to Nissan CEO Carlos Ghosn explain why he's still in favor of electric vehicles. Plus, if we've heard it a few times, imagine how many times he's had to say it. It happened again this morning at the opening breakfast for the New York Auto Show, and it was as clear and concise an explanation as you can imagine...
http://www.autoblog.com/2016/03/23/for-carlos-ghosn-electric-vehicles-are-the-only-solution/

And at about two minutes thirty seconds into the wide-ranging video, Carlos Ghosn mentions:

...in-wheel motors...the future of the electric car...
I doubt CG would have brought that subject up if he hadn't already seen them in use in prototypes.

Still, I will be (pleasantly) surprised if in-wheel motors were to show up as soon as the gen 2 LEAF.
 
Nissan has had five years and couldn't, or wouldn't develop a long range battery pack for the Leaf; like all the other legacy car makers they run in the middle of the pack as a follower, not as a leader/innovator. They are excellent at press releases and vapor on products they will never offer to the Public. It's amazing how my '100 mile 2011 Leaf" turned out to be good for 50-60 miles from the day I bought it. In-wheel motors on a Leaf...I don't think so!
 
It's not really about Nissan being a follower. Heck, when it comes to mass-market BEV, they were the first. But they are mainly a traditional automaker, and they weren't "all-in" like Tesla was. Now Tesla will be coming out with a mass-market car that should blow the doors off the Leaf, and Chevy may have also passed them up when the Bolt comes out. We'll have to see what the next version of the Leaf looks like, but to me it looks like Nissan didn't do enough to build upon its first-mover position and will quickly lose it.
 
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