rmay635703
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Re: The introduction of in-wheel motors for BEVs/PHEVs. When

Wed Nov 13, 2013 4:53 pm

fotajoye wrote:Please allow me to quote myself.

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

edatoakrun
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Re: The introduction of in-wheel motors for BEVs/PHEVs. When

Thu Nov 14, 2013 9:55 am

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 wrote: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 ... led?page=1
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rmay635703
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Re: The introduction of in-wheel motors for BEVs/PHEVs. When

Wed Nov 20, 2013 11:18 am

edatoakrun wrote: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 ... led?page=1


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.

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

Wed Nov 20, 2013 11:32 am

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.

rumpole
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Re: The introduction of in-wheel motors for BEVs/PHEVs. When

Wed Nov 20, 2013 11:54 am

GeekEV wrote: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 ... ub-engines



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".
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edatoakrun
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Re: The introduction of in-wheel motors for BEVs/PHEVs. When

Sat Dec 14, 2013 10:40 am

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 ... otean.html
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fotajoye
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Re: The introduction of in-wheel motors for BEVs/PHEVs. When

Sat Dec 14, 2013 11:41 am

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.

edatoakrun
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Re: The introduction of in-wheel motors for BEVs/PHEVs. When

Sat Dec 14, 2013 12:05 pm

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


Yes.

As were BEVs with sufficient range, at low enough cost, to make them superior to ICEVs for many or most uses.

I've been driving one of those for ~2.5 years now...
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palmermd
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Re: The introduction of in-wheel motors for BEVs/PHEVs. When

Sat Dec 14, 2013 3:05 pm

fotajoye wrote: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.
Michael

Leaf since 31 March 2011
Driving electric since 1996


First Bar Loss
Second Bar Loss
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edatoakrun
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Re: The introduction of in-wheel motors for BEVs/PHEVs. When

Wed Apr 02, 2014 12:24 pm

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/si ... rty-coupe/
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