Multi-speed EV Transmission Confirms High Efficiency in Testing
Results for innovative new design surpass predictions; to be presented at CTI Symposium, Shanghai
Leamington Spa, UK, 20 August 2015 – Evolute Drives will present practical test results for its high efficiency MSYS electric vehicle transmission at the CTI Symposium in Shanghai (16-18 Sept). In independent tests, a B-class demonstrator vehicle fitted with the transmission achieved a reduction in energy consumption of up to 18 percent over the NEDC test cycle, compared to the single-speed base vehicle.
“The results, obtained at the MIRA facility in the UK, endorse our previous expectations of a 10-15 percent improvement when a single-speed drive is replaced by our MSYS transmission,” said Alex Tylee-Birdsall, Managing Director of Evolute Drives. “Reducing the energy required by an EV leads to a corresponding improvement in range, which is still a key issue for many EV users.”
Since technical details of MSYS were presented at the 2013 CTI Symposium, development has continued in several areas, towards a production-intent prototype specification. These developments, along with the detailed results from the MIRA tests, will be presented by
Tylee-Birdsall in a paper entitled ‘Next Generation Development - MSYS 3-speed EV Transmission’ on 18 Sept at 16:45 in session D.
The cone clutches used in MSYS allow much greater torque transmission density than a wet multi-plate clutch, providing over four times the torque capacity within the same package size. Recent developments include minimising torque oscillation during engagement to ensure good and consistent shift feel, through the management of concentricity of the assembly.
The presentation will also describe efficiency improvements obtained through a novel twin-mode lubrication system. The lubricant flow rate to the clutches is increased only during shift events, when greater cooling is required, by a simple variable distribution system. At other times the flow rate is reduced to minimise energy requirements.
“MSYS allows full torque power shifts to be made but requires no energy to hold the transmission in gear, which improves system efficiency,” explained Tylee-Birdsall. “The key to the technology is the separation of the two functions provided by a synchroniser (friction and latching), while enhancing the friction capacity so it can be used to temporarily drive the vehicle.”
Production-intent prototypes of the MSYS transmission should complete their testing during 2016 and validated production units are scheduled for sign-off around mid-2017.
About Evolute Drives
Evolute Drives Ltd. was established to exploit the intellectual property developed by the innovative and well respected engineering consultancy Drive System Design Ltd, and bring it to the market place. Drive System Design works with many of the major vehicle manufacturers in developing transmission and driveline products for the next generation of vehicles.
The electric vehicle market needs a range of solutions to increase vehicle range in order to unlock projected vehicle sales due to “range anxiety” of potential end users. Part of this solution will come from the transmission.
Adding multiple speeds to electric vehicle transmissions will reduce the energy consumption by 10-15% and therefore increase range. The reason for this is it allows the power electronics to consume less power as the motor runs at lower speed. The problem is changing gear without interruption of power to the wheels whilst also not consuming additional energy to hold the transmission in gear. In all current transmissions you either require energy to hold in gear (planetary automatic and dual clutch systems) or the power is interrupted giving poor shift feel.
Evolute Drives’ 3 speed MSYS transmission overcomes this by providing a seamless power shift but requires no energy to hold the transmission in gear. Therefore this technology unlocks the potential of multi speed electric vehicle transmissions and provides vehicle manufacturers with the additional vehicle range they have been looking for. This technology is therefore an enabler to increase electric vehicle sales.
The prime market for this technology will be premium segment electric vehicles as these will attract the highest sales and provide the best showcase. The pure electric and plug-in hybrid electric vehicle markets are due to hit 3,000,000 sales by 2020 and will continue to grow.
Paul Chadderton at Market Engineering
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