Evolute Drives test results show 18% reduction in energy consumption with 3-speed MSYS EV transmission compared to single speed
Evolute Drives, incorporated as a separate entity by its sister company Drive System Design (DSD) (earlier post), will present practical test results for its high efficiency 3-speed MSYS electric vehicle transmission (earlier post) at the upcoming 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% 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. Reducing the energy required by an EV leads to a corresponding improvement in range, which is still a key issue for many EV users—Alex Tylee-Birdsall, Managing Director of Evolute Drives
|3-speed MSYS transmission fitted in B-class tester. Click to enlarge.|
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”.
The cone clutches used in MSYS allow much greater torque transmission density than a wet multi-plate clutch, providing more than four times the torque capacity within the same package size. Recent developments include minimizing 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. 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.—Alex Tylee-Birdsall
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.