## Getrag introduces new dual clutch transmission for electric drives, prototype of range extender, mild-hybrid dual-clutch variant

##### 15 September 2011
 The 2eDCT600. Click to enlarge.

Among Getrag’s introductions at the Frankfurt Motor Show were a new dual clutch electric drive unit; a further development of its Boosted Range Extender; and a variant of the PowerShift transmission with an integrated electric motor for mild hybrid applications.

The 2eDCT600 electric drive unit is suited for pure electric vehicles, plug-in hybrid vehicles and range extenders. It is designed for a maximum electric motor input torque of 500 N·m and an output torque of 6,000 N·m. This architecture extends the range by up to 10% in electric mode.

Due to a new actuator concept, the power can be transferred by the overlapping shifting through the disc clutches from one speed to the other without using a synchronisation or a dog clutch. Because of the modular system this topology allows axially parallel and coaxial drive train assemblies.

In comparison to known single-gear electric drives in hybrid or purely electric vehicles, the two-speed approach offers better starting performance and higher maximum speed, Getrag says.

Getrag also showcased a fully functional prototype of the Boosted Range Extender (earlier post). First presented in 2009, the range extender is being integrated into a Ford Fiesta equipped with additional components needed for electrical driving. The entire control for the hybrid powertrain was developed by Getrag.

The conventional powertrain was able to be replaced in the engine compartment by the new transmission with a cost-efficient 3-cylinder gasoline engine at an efficiency level of a diesel engine and an 88 kW electric motor without changing the vehicle structure. The power electronics for the electric motor and a modified cooling system for the additional e-drive components are also placed in the engine compartment. The high-voltage battery is located in the trunk.

Additional hybrid components such as control units and DC/DC converters with charge function are located beneath the floor of the trunk, meaning the passenger space can still be used in full. The Boosted Range Extender offers two gears for the e-motor as well as for direct drive by the combustion engine for a cost-optimized, scalable concept with high ranges and dynamic driving comfort in each operating mode.

 Dual-clutch transmission with integrated electric machine for high-torque Mild-Hybrid drive train. Click to enlarge.

The Mild-Hybrid 6HDT451 transmission, based on the GETRAG PowerShift 6DCT451, was developed for front transverse installation in the middle and upper-middle class segments and in sport utility vehicles (SUV). Total torques of up to 450 N·m can be transferred with simultaneous engine and electric machine operation. A 7-speed derivative and park-by-wire can be applied optionally.

The avoidance of torque break and a high continuous e-motor torque of 110 N·m enable sporty, dynamic driving experiences. The 6/7HDT451 increases driving performance with an unchanged, compact combustion engine or alternatively supports further downsizing of the combustion engine and consequently the reduction of CO2 emission.

I will wait for a 10%++ (battery-e-motor-controller) improvement instead of this mechanical wonder in our first EV.

@HarveyD - why not both?

It will come down to cost - how much does this transmission cost compared to adding 10% more battery?

The funny thing is - the 10% may be more beneficial on EVs with larger battery packs!

Let's assume that the cost of a battery pack is $500/kWh today. On a 100 mi EV (~25 kWh battery pack), 10% more range will cost$1250. Can this transmission be built for less than that?

If you have a 200 mi EV (~50 kWh battery pack), 10% more range will cost $2500. Probably safe to assume that the transmission will cost less in this case. All of this ignores the other benefits of faster acceleration and higher top speed. I know that I would have gladly paid another$1500 or so for another 10% range and a noticable improvement in acceleration in my LEAF.

Only in the land of the no speeds, is the one-speed transmission king.

EVs with 2 or 4 in-wheel or near wheel variable torque e-motors do not need expensive (heavy) mechanical transmissions. Batteries performance will improve at about 10%/year (average) and by 2015 or 2020 their energy storage and power gains will be 50% to 100% and even more, making a multi-speed transmission extra luggage, except for race cars and heavy trucks/buses.

Let's keep mass produced e-cars as simple and as light as possible.

I think the market will determine if the improved efficiency and performance provided by more speeds becomes predominant.

Dave R explained it quite succinctly.

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