fotajoye wrote:Please allow me to quote myself.
Agreed, to paraphrase, they suck, dirt, torque, reliability unsprung weight = suck.
fotajoye wrote:Please allow me to quote myself.
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.
...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,...
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
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
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...
...Hub wheels have been an engineering idea for almost a century.
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.
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)...