Antonov gears up for China – and EVs
In the VW mule testing, the TX6 has proved capable of matching the fuel efficiency of a standard Golf 1.6 FSI equipped with an Aisin 6-speed automatic.
A 3-speed for EVs
While the TX6 is focusing Antonov’s development and production teams, a major R&D program concerns a 3-speed automatic gearbox for EVs. Antonov has built one for Jaguar in partnership with MIRA as part of the U.K. government’s Technology Strategy Board-funded “Limo-Green” project.
“We decided that for real efficiency an EV should have a 1st gear for launching and a 3rd for cruising, while the car would spend perhaps 95% of its running time in 2nd,” explained Roberts. “A 3-speed parallel-shaft gearbox with mainly commercial off-the-shelf (COTS) components maximizes motor efficiency. A single speed is not sufficient and a 2-speed provides a ratio step that feels like shifting from 1st to 4th in an IC car.
“It is virtually impossible to refine the shift and there is danger of gearbox damage,” he claimed.
Roberts noted that in the early days of the auto industry, large engines and small transmissions were common. Now, he said, “we are seeing small engines (or electric motors) and large (with more ratios) transmissions. We will see a downsizing policy for electric motors just as we are seeing it for IC engines today, and we will see efficiency improved by the use of multispeed transmissions.
“We can easily add four more speeds to our EV transmission,” he asserted.
For example, to use a 900-N·m (664-lb·ft) motor with a single-speed transmission would involve approximately “1200 A running round a vehicle” – an industrial level. But by using a three-speed transmission, 400 N·m (295 lb·ft) would be sufficient and bring the system down to 400-500 A, which he noted would be far more acceptable.
Roberts sees the 3-speed EV as suitable initially for larger vehicles in the U.S. and not city cars. But with the growing trend toward EV solutions, and with China always likely to want more and better technology, it could be that Antonov’s TX6 might eventually pave the way for the company’s multispeed EV transmission range, with applications in a wide span of vehicles.
Stuart Birch
Original article available here: http://www.sae.org/mags/AEI/9198