Multispeed transmission for EVs
The next major step in boosting EV viability is upon us with the development of a clutchless manual transmission for electric motorsUK company Zeroshift has come up with a multispeed gearbox delivering EVs the same efficiency benefits cog-shifting has long given combustion engines.
Automotive electric motors have several major advantages over internal combustion engines beyond zero emissions. Firstly, they're much simpler mechanically, making them cheaper to build and maintain. They also deliver all their torque from the moment they're activated. This, along with the electric motor's ability to run at far higher revs than the IC engine, has made it both harder and less necessary to hook it up with a multispeed transmission -- even though there's no doubt that to do so has the potential to let it run more efficiently. The locally converted Blade Electron couples the electric motor to a modified version of Hyundai's five-speed manual transmission, but in the main manufacturers have not bothered with multi-gear transmissions for electric vehicles, despite the prospects of improved range.
That's why UK transmission specialist Zeroshift has come up with a multi-speed gearbox for electric vehicles (EVs). Importantly, it's clutchless, using instead an internal damper and ECU programming to make gearshifts seamless. Removing interruptions to the delivery of the motor's torque further boosts running efficiency to extend both range and the lifespan of the power pack by what Zeroshift claims is up to 10 percent.
Zeroshift has achieved this by using a system of interlocking rings in place of a conventional synchromesh system. The ECU is programmed to match revs on the motor side with those on the drivetrain side, with a passive damper system using silicone fluid and mechanical compression springs inside the gear hub to absorb impact and iron out vibrations.
With extensive optimisation testing, the company says the result is shifts smooth enough to be almost undetectable.
Zeroshift claims the improvements to operating efficiency in single and multiple EV motors gives manufacturers the potential to use smaller motors. It also improves the viability of electric power in delivery vehicles by allowing them to take off more efficiently on hills with a full payload without sacrificing efficiency under light load on freeways and the like.
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