German transmission specialist Getrag used the floor of the 2011 Frankfurt Motor Show to reveal its groundbreaking, dual-clutch transmission for electric-drive vehicles.

Dubbed 2eDCT600, Getrag's two-speed unit is supposedly ideal for pure electric vehicles, plug-in hybrids and range-extended automobiles. Getrag claims the 2eDCT600 can cope with a maximum electric motor input torque of 369 pound-feet and an output torque of up to 4,425 lb-ft.

The German firm touts its 2eDCT600 as a multi-speed solution that gives electric-drive vehicles improved launch capability and an increased top speed. Perhaps most importantly, Getrag claims its dual-clutch unit extends an electric-only vehicle's range by up to ten percent. That's a big number in the EV range game. Follow the jump for full details on Getrag's consumption-reducing gearbox.
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Getrag demonstrates "Global Power" with new products

Untergruppenbach/Frankfurt, 14. September 2011

GETRAG consequently aligns its product strategy with the future global challenges of the automotive market and focuses on its core business transmissions.

At this year's Frankfurt Motor Show it is all about global trends. In line with the motto "Discover the Global Power" GETRAG presents a product portfolio that is guided by the worldwide developments of the automotive market. Priorities are growth and market needs in China, increasing demand of dual clutch transmissions worldwide and further engineering activities in e-mobility.

Electric drive unit 2eDCT600 is celebrating its world premiere

The dual clutch transmission provides an overlap shift under full load without having the need for engagement of synchronisations or dog clutches. The usage of multiple gears offers better launch performance and an increased maximum speed. Thanks to the modular kit this topology allows for parallel axis and coaxial drive train assemblies. The 2eDCT600 is ideal for pure electric vehicles, plug-in hybrid vehicles and range extenders. It is designed for a maximum electric motor input torque of 500 Nm and an output torque of 6,000 Nm. This architecture extends the range by up to ten percent in electric mode. The concept simultaneously enables energy savings, range extension and high driving comfort by the integrated PowerShift transmission without torque break.

Fully functional prototype of GETRAG's Boosted Range Extender in testing phase

The study presented at Frankfurt Motor Show 2009 has meanwhile become a prototype 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 gas engine at an efficiency level of a Diesel engine and an 88 kW electric motor without changing the vehicle structure. That is also where the power electronics for the electric motor and a modified cooling system for the additional e-drive components is integrated. 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 with two gears for the e-motor as well as for direct drive by the combustion engine a cost-optimised, scalable concept with high ranges and dynamic driving comfort in each operating mode.

Getrag introduces the future PowerShift transmission

The dual clutch transmissions DCT451 provides higher efficiency, new software features, optionally park-by-wire and up to seven gears compared to the previous model. The transmission supports start/stop without additional hardware like electrically driven pump or oil pressure accumulator.

Based on the DCT451 a mild hybrid variant with an integrated e-motor has been developed: the 6/7HDT451. This mild hybrid with the same installation length as the basic transmission is ideal for front transverse installation in the middle class and upper middle class segments and in sport utility vehicles (SUV). The avoidance of torque break and a high continuous e-motor torque of 110 Nm 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.

New dual wet clutch is now developed in-house

In order to further optimise the GETRAG PowerShift® transmission GETRAG developed the clutch inhouse being the most important component. The dual wet clutch DC500 allows an integrated optimization of the subsystem interactions and enhances the individual tailoring capabilities of transmission characteristics to vehicle attributes. Hereby, GETRAG concentrated on minimizing drag torque, weight and inertias to further improve the best-in-class fuel efficiency attributes. The dual wet clutch DC500 supports Diesel as well as gasoline applications up to 8,200 rpm. Within the modular kit another dual wet clutch, the DC300, has been developed and supports all smaller future PowerShift transmissions up to 300 Nm.

GETRAG continues to back manual transmissions as segment with strong global growth
With the 6MTT250 GETRAG develops and manufactures the basic transmission architecture for the new generation of small engines. The manual transmission sets new standards in shiftability and offers an ideal relation between torque and weight. It covers a globally growing market segment. With the 6MTI300 the modular kit of inline manual transmissions was extended by a further variant with direct fourth gear for gasoline engines. Thus, the torque capacity of the existing architecture is significantly increased without additional weight.


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    • 1 Second Ago
  • 30 Comments
      • 3 Years Ago
      One of the biggest advantages to me of this set-up is that it can be used with minimal changes in different combinations, so that for instance the BMW with minimal changes would be able to be a hybrid or an electric as they have indicated they want to do. This leads to very large savings.
      Ladson
      • 3 Years Ago
      The torque curve of most electric motors show an immediate rise to full value and then an even value until the eddy currents and reverse electromotive forces force the torque to drop rather quickly. There is no question that gearing to keep the torque in the sweet section of the curve will result in more power; however, the transmission must be sturdy and strong because of the immediate torque. As many know making a car lighter, more aerodynamic and with less friction is the current preferred way to improve efficiency. For example; the Leaf has combined the motor control, differential gearing and the motor into a one ratio, front drive unit to save space and weight; the front doors and hood are aluminum for the weight savings; and the car uses the can protocol to save wiring. So, for all these reasons, perhaps the idea of keeping the driveline simple, i.e., not adding a gearbox, etc., for a production electric automobile makes sense.
        Noz
        • 3 Years Ago
        @Ladson
        I imagine full torque will NOT be available for most electric vehicles with these types of transmissions and will be electronically controlled from off the line to prevent transmission failures...
          2 Wheeled Menace
          • 3 Years Ago
          @Noz
          Well if they can build a transmission that can deal with an 8.4L V10 ( dodge viper ), they can certainly build a transmission that can handle an electric motor :) You can limit torque by telling the controller to dole out less amps.
      Chris M
      • 3 Years Ago
      I suspect they started this EV transmission project when they heard of the problems Tesla was having, and it's finally available after years of design and testing. I noticed the press release also mentioned other transmissions, including a 7 speed dual clutch, a transmission with integrated motor for mild hybrid application, and even a new manual transmission.
      markkiernan
      • 3 Years Ago
      What is wrong with having a 6 or 9 speed gearbox for an EV?
      krisztiant
      • 3 Years Ago
      Every reliable source says, a transmission takes ~10% efficiency from the engine / motor. So here's the math: EV transmission gains ~10% efficiency + EV transmission takes ~10% efficiency = 0 (zero) /confused :(
        BipDBo
        • 3 Years Ago
        @krisztiant
        A standard EV with only a single ratio like the Leaf has gears between the motor and the wheels. The gears do cause a friction loss, but it is minimal. This transmission has basically the same gears between the motor and the wheels. The only difference is that it has two sets of them, with some clutches to change from one set of gears to the next. Therefore, the friction loss from a 2 speed transmission like this would be identical to the friction loss of a single ratio gearset like that found on the Leaf. Also, the main cause of friction loss in a transmission is the torque converter in an automatic, or on a vearible speed transmission there is some friction loss in the belts. Gears cause friction loss, but it is relatively small. Clutches do not cause friction loss. Any transmission with clutches is therefore inherantly more efficient. Automatics sometimes get better mpg numbers than manualsfor 2 reasons: * On EPA test cycles, where the car is driven so very gingerly, the loss through the torque converter is very small. In real world driving, when the driver stomps on the gas, an engine connected to a torque converter revs disproportionately to the car's speed and energy is lost. With a clutch, as soon as the clutch is fully engaged, the engine cannot rev disproportionatley to the speed of the car, so energy cannot be lost in excessive rpm. The manual, or dual clutch transmission will therfore more likely have better real world mpgs than the automatic despite EPA values. All of this is releant only in city driving, because automatics with torque converters lock in their gearing in the highest ratio only. So in this mode, only seen in higher speed cruising, they will perform just like a transmission locked in with a clutch. * All too often, the highest gear ratio on a manual transmission is much lower than the highest ratio available in the automatic or variable speed option. I think that they do this because they believe that most people wanting to buy a manual is doing so for sportiness rather than efficiency. Sometimes, they also limit the highest ratio to avoid low rpm noise from the engine during highway cruising. Personally, I'd rather have a nice low cruising rpm in my final ratio.
        2 Wheeled Menace
        • 3 Years Ago
        @krisztiant
        You're talking about a transmission meant for an internal combustion engine, having either a clutch/flywheel or even worse, torque converter system... and additionally, at least 4 gears or more.. plus a reverse gear and a spot for the gear selector to be in 'neutral'. An electric motor needs none of the above things. A transmission for an electric motor is extremely simple in comparison. An electric transmission wouldn't even have to deal with a multi-hundred degree furnace butted up against it.. I think it would be safe to assume that an electric motor is more efficient.
          krisztiant
          • 3 Years Ago
          @2 Wheeled Menace
          You might be right, but some would argue that even a single gear mesh can cause about 4-8% loss of energy, not to mention, a tranny needs differential too (some more % loss), so why not use 2 (or 4) smaller direct motors (and call it a day). I'd rather believe in some kind of - yet to be invented - computer controlled "RPM agnostic" motor optimization (variable torque motor?), bypassing the mess of good ol' transmission. But let's here this straight from e.g. Volvo (ReCharge Concept) why they chose the 4 individual electric motors setup (video at 1:12): "[4 independent motors] allow us to independently control the wheels and also give much better efficiency, because we eliminated the transmission, that takes away about ten percent of the energy..." http://www.youtube.com/watch?v=HJwQ18I0vgY
      Dan Frederiksen
      • 3 Years Ago
      same premise. it'll be interesting to see if 2 speed is ever used. if a slightly bigger motor can do the same or better with fixed gearing..
      2 Wheeled Menace
      • 3 Years Ago
      All criticisms aside, there is something inherently cool about transmissions on EVs.. The noise that the engine makes when shifting from gear to gear is actually what a lot of people do miss, including myself, as i have driven manual transmission cars forever. I believe you would not need a clutch at all. A computerized manual transmission or a manual shift transmission would only need to cut power for a fraction of a second to protect the outer edge of each gear. A transmission on an EV would be like operating a DSG ( direct shift ) style system. Another advantage is that you could use a high winding count motor with a slower top speed but use a transmission with 3-5 gears to extend it's RPM further out. This could potentially be more efficient. It could be kept in it's peak efficiency range for the majority of the time spent driving. I do strongly think that despite the high efficiency of electric motors, and fairly broad efficiency band, that we will see transmissions to eke out an extra 5%-15% of range until batteries get to where they need to be.
        JP
        • 3 Years Ago
        @2 Wheeled Menace
        There is also something inherently cool about not needing a transmission in EV's. Also, please do not expect a transmission to give you 15% more range, or even 10% more range, it's not going to happen. In certain conditions it might give you 5% more range, and in other conditions the added weight might actually hurt your range if you would have been traveling in the motors max efficiency speed range to begin with. It's not a miracle boost to range, and with people complaining that EV's are already too expensive adding the cost and weight of a transmission might not be a great idea. In a performance EV, sure, why not, since performance is the goal, but not for most EV's.
      thepennyracer
      • 3 Years Ago
      dry weight is 42kg sourced: http://www.getrag.de/iaa/fileadmin/content/pdf/products/engl/Press_information_2eDCT600.pdf hell yeah this could be worth it.
        Dave D
        • 3 Years Ago
        @thepennyracer
        Depends on the car and the design goals. This adds about 9 miles or range to a Leaf...or you could buy another 2kWh of batteries which would weigh about 15kg with the Leaf's current battery tech. Depends on if your goal is better performance or the cheapest, easiest way to gain extra range.
          2 Wheeled Menace
          • 3 Years Ago
          @Dave D
          Pennyracer, there isn't much to an EV transmission. There may be a small gear reduction and differential box, or they may just plug the axles straight into the motor.
          2 Wheeled Menace
          • 3 Years Ago
          @Dave D
          Batteries ain't cheap though.. a 2 speed transmission isn't going to be all that expensive. When the battery needs replacement down the road, you'll be thankful for that transmission.
          thepennyracer
          • 3 Years Ago
          @Dave D
          good point. i would love to assume the application for a two-speed would be sports car use (like tesla originally tried out). since people will pay a premium for go fast parts, this seems like a great option, and possibly a stepping stone for a manual EV? i was trying to get a generic weight of an EV transmission, but 15 minutes of google left me high and dry. If the average isn't far off of 42kg, the new tech could not only be an option but a full replacement.
      JP
      • 3 Years Ago
      For the extra weight and cost I'll just take more batteries, thank you. Remember, that 10% improvement is a maximum, in reality for most driving, which is already done in the efficiency range of the motor, there will be little to no improvement. I don't care about increasing my top speed which would already get me a ticket as is.
        Rotation
        • 3 Years Ago
        @JP
        It depends on the situation, but look at the Volt (or Prius) for example. It has to have a small motor for low speeds and a second large motor for higher speeds in order to be efficient. You can't use just one motor, it wouldn't be efficient in the large span of RPMs from 5 to 65 miles an hour, it would reduce your efficiency by 10% or more. So a single motor and this transmission could perhaps do the job instead. Don't get me wrong, I think partly this transmission was designed simply because Getrag wants to make sure they have products that make sense in an electric car world, but it's quite possible they are onto something too.
          Rotation
          • 3 Years Ago
          @Rotation
          Dan, the two motors in the Volt are for high and low speed. Chris M: the newest versions of hybrid synergy drive try to minimize the situations where one is acting as a generator and the other as a motor because it isn't efficient. Neither motor just changes gearing, their power output is used to move the vehicle.
          Dan Frederiksen
          • 3 Years Ago
          @Rotation
          play around with that http://eahart.com/prius/psd/ then you can learn how it works.
          Chris M
          • 3 Years Ago
          @Rotation
          Correct, Dan. The two motor/generators in the Prius work together, sometimes they both provide torque, sometimes one will act as a generator supplying power to the other acting as a motor, or the other way around, and sometimes they both act as generators for regenerative braking. The two motor/generators working together with the planetary gears gives an electric continuously variable transmission with an infinite number of gear ratios. .
          Dan Frederiksen
          • 3 Years Ago
          @Rotation
          the two motors in the volt and prius is not for high and low speed. and a leaf, imiev and tesla roadster have only one motor and fixed gearing.
      2 Wheeled Menace
      • 3 Years Ago
      Increased top speed is the selling point here, as well as potentially better city "mileage". Electric motors are most efficient at high RPM, yet produce progressively less torque the closer you get to the maximum RPM. So a highway gear would be nice because it could kick the RPMs down just enough that you still have torque to climb a 10% grade at 70mph without losing power. This could make a smaller motor operate much better at a higher range of speeds. I like it a lot.
      Peter
      • 3 Years Ago
      Better range and 0-60 and top speed whats not to like? You have the choice of improved dynamic performance with the weight and cost of the tranny offset by a 10% smaller battery needed for a given range or Pony up for the tranny and get longer range with the current battery and better performace
      Smith Jim
      • 3 Years Ago
      The Volt drive train is effectively a two-speed transmission in EV mode. At low speeds the 111 kW motor turns the sun gear while the ring gear is held stationary and the output is taken from the planetary carrier. At higher speeds the 111 kW motor still drives the sun gear but the ring gear is driven by the 55 kW motor. Planetary gears have a high torque capacity because the force is distributed among three (or four) planetary gears. This is why drag racers prefer conventional automatic transmissions for high torque monster big block V8s.
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