A Japanese company has built an electric car that offers a driving range comparable to some gas-powered vehicles -- although it won't be hitting the streets any time soon.
The SIM-LEI, developed by SIM-Drive Corporation, can go 207 miles on a single charge, twice the distance of the Nissan Leaf. And with a 0 to60 acceleration time of just 4.8 seconds, the automaker has demonstrated that exceptional fuel economy for EVs can be achieved all the while flexing a little muscle too.
The secret, however, isn't under the hood but rather in the wheels. The LEI, which stands for Leading Efficiency In-Wheel motor, is powered by a technology first developed in the late 1800's, just prior to the auto industry's widespread adoption of the internal combustion engine.
It was right before the turn of the century that inventors began toying with the concept of bringing to the market an electric motor that can be fitted within the hub of a car's two front wheels. In fact, Ferdinand Porsche earliest models were powered by electric wheel hub motors that ran on batteries. A notable example was the Lohner Porsche, which created quite a buzz when it was introduced at the World's Fair in Paris in 1900.
Although these early versions were unable to match the performance output of gas engines, the technology did boast one important advantage. Internal combustion engines used a complex mechanical process to deliver energy to the wheels, which resulted in much of it being lost. In contrast, the electric motor powered the wheel directly, leading to greater fuel efficiency.
Considering that the SIM-Drive relies on a 24.9 kWh lithium ion battery similar to the Leaf's, the improvement in fuel efficiency can be largely credited to this simple design principle. But the car also features a few innovative tweaks that allow it to keep pace with gas-powered cars in ways its earlier predecessors had only hoped.
Until now, in-wheel motors have been thought to lack the power necessary to propel a car in a manner that most are used to. SIM-Drive appears to have overcome this problem however, with new technology (including using outer-rotors and inner stators, instead of the traditional inner rotors and outer stators) as the SIM-LEI is able to move from 0 to 62 mph in just 4.8 seconds. And because the individual motors can be fitted with sensors, allowing nearly instantaneous reaction to conditions, responsiveness is expected to be better than most cars now on the road.
In-wheel motor technology has also been hampered by the fact that the additional "unsprung weight" of the motor, which can't be supported by a car's standard suspension system, tends to have an adverse affect on road handling.
SIM-DRIVE hasn't released any details in regards to how or even if they've addressed the problem in their latest prototype, but other manufacturers have developed in-wheel systems that they say have made the issue less of concern. For instance, Bridgestone's Dynamic-Damping In-Wheel Motor Drive System overcomes this hurdle by designing the motor to also work as "vibration dampers" that can absorb road bumpiness and others vibrations.
According to the company's press release, "their own vibration offsets the vibration from the road and tires, allowing for better traction and a more-comfortable ride than are possible with other in-wheel or electric drive systems."
Michelin has also created an in-wheel motor known as "Active Wheel" that negates the drawbacks of unsprung weight by replacing a car's entire cast iron friction brake system with a compact electrical system featuring integrated suspension, braking and motor functions.
SIM-DRIVE has yet to announce a starting price for the vehicle and doesn't appear to be in a rush in bringing the car to market. The company plans to have the first models roll off the production line in 2013, which can seem like a lifetime in the auto industry.