Test Results Show 18% Reduction In Energy Consumption For 3 Speed Versus 1 Speed EV Transmission
Evolute Drive, a new company from the UK, intends to present its 3-speed MSYS electric vehicle transmission at the CTI Symposium in Shanghai (16-18 Sept) – and a paper entitled ‘Next Generation Development – MSYS 3-speed EV Transmission’ on 18 Sept at 16:45 in session D.
According to the press release, prototype of MSYS tested independently in a B-class demonstrator vehicle at the MIRA facility achieved up to 18% reduction in energy consumption over the NEDC test cycle compared to a single-speed gearbox.
18% is a significant improvement (even more than the expected 10-15%). But we believe that real world range will increase by less value as the energy savings concerns only the drivetrain specifically.
About the MSYS:
“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.”
“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.”
Alex Tylee-Birdsall, Managing Director of Evolute Drives said:
“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.”
“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.”
Single-speed drive is a brilliant solution for EVs, but 18% more efficient sounds swell too.
There are concerns about reliability and maintenance of EV transmissions that we are unable to settle until someone introduces a non-performance electric car with two or three gears in volume.
There is another side of the equation, which we can handle better. For cars like the Nissan LEAF, 18% is like about 4 kWh more usable energy. At contractual $500/kWh, let’s say batteries would cost $2,000 total. Weight of additional batteries and MSYS will be similar, so manufacturers considering more gears must decide whether to offer a larger pack or a multi-speed transmission – for $2,000? Nissan recently choose to offer some 6 kWh more for total 30 kWh.
“E-Machine Type Axial Flux YASA motor
E-Machine Power 55kW continuous (100kW+ for 60s peak)
E-Machine Max Torque 200Nm @ 4000 rpm (limited by power electronic)
(3 speed) 1st – 9.93:1
2nd – 7.11:1
3rd – 5.08:1
Gear Shift Hydraulically Actuated Powershift Technology
Driveline Efficiency 98% Transmission, 95% Motor, 97% Power electronics, 91% Overall
Lubrication System Dry Sump (Light Oil Spray)
Park Lock Integrated Plunger Type with Electrical Actuation
Powertrain Weight 55kg Prototype Unit (wet) 45kg Production Intent (wet)
Installation Length 366mm Prototype Unit 320mm Production Intent
Cooling System Pump and In-built Sump Radiator
Options Output disconnect for e-AWD application”