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GETRAG Introduces Concept Hybrid Drivetrain

Getrag_eyecathcer
The concept GETRAG-Bosch hybrid drivetrain. Click to enlarge.

The GETRAG Corporate Group has introduced a new concept modular hybrid drivetrain based on the combination of a parallel hybrid module and an electric rear axle drive. Getrag developed the concept in partnership with Bosch; the two companies agreed last year to work together on hybrid systems. (Earlier post.)

The concept drivetrain combines a 6-speed Getrag PowerShift transverse transmission, Bosch electric motor, Bosch power electronics and electric rear axle drive (eAD). The system supports all-wheel and hybrid functions, including boost, regenerative braking and all-electric driving.

Getrag_eyecatcher2
Components of the hybrid drive with electric axle. Click to enlarge.

The foundation of the drive is the GETRAG PowerShift transmission—in this application, a 6-speed dry dual clutch transmission with 250Nm (184 lb-ft) torque capacity. A separate motor-generator (SMG) is mounted axially parallel to the transmission and connected to one or both (switchable) of the two part-transmissions of the dual-clutch transmission via a newly developed electromagnetic shift unit (EMAGS).

This configuration supports the use of different applicable ratios for the connection of the motor, allowing it to run at an optimum operating point. The motor can also be disconnected when necessary.

This enables full hybrid functionality (boost, regenerative braking, pure electric driving) and the operation of the engine and the motor at the optimum operating points for each, resulting in fuel efficiency benefits.

The peak torque of the Bosch separate motor generator (SMG) is scalable by the length of the machine (50-200mm) and ranges from 70-120 Nm (52-89 lb-ft).

The transmission, motor and power electronics constitute a torque-split hybrid module that can be applied with or without the electric axle drive. Similarly, the electric axle drive (eAD) can be applied as a stand-alone unit without the torque-split hybrid module, thereby creating a “through-the-road” hybrid.

The eAD features a 1-speed transmission and a 30 kW motor with peak torque of 858 Nm (633 lb-ft). The eAD’s elimination of PTU/transfer case and propeller shaft helps offset the additional weight of the hybrid components, and also helps reduce drivetrain costs.

Comments

K

Egad! (or should that be 'Egads') This sure seems intricate and expensive.

Getrag wants to sell their transmissions. Nothing wrong with that. And a lot of complex things are actually worthwhile.

andrichrose

looks incredibly complicated , expensive and probably heavy !

Mick

Is it a manual shift or an automatic?

michel

...let me guess. Is it a modern 4x4 system without mechanical links to the rear axle?
Is this the future of 4x4 cars and trucks?

Ben

Why not simple have the electic motor on the back axle and forgo the connection between the frot and rear axle and the extra clutch.

John Schreiber

Ben,
I think we shall see exactly what you suggest, with of course idle stop for the ICE.

AES

"Why not simple have the electic motor on the back axle and forgo the connection between the frot and rear axle and the extra clutch."

That's actually what GM did with its parallel hybrid variant of the EV1.

Rafael Seidl

@Ben -

you just described eAD aspect of the Bosch-Getrag system.

The front axle drivetrain inludes a dual-clutch transmission for the ICE plus one electric machine. In the base case, that machine acts as either a boost motor or as a generator, to operate the ICE more efficiently and during recuperative braking.

The optional eAD provides purely electric traction for the rear axle. In 4x4 mode, the electric machine in the front always acts as a generator, delivering power either to the rear motor or the battery. This architecture is analogous to the Lexus 400RH, though that uses a compound rather than a parallel hybrid drivetrain up front.

The third option is to use the rear electric machine for recuperative braking and use only that power for traction later on. This is how the 1990s vintage Audi 80 Avant Duo worked, but only 50 units were built before the product was canceled. The battery and control systems technology back then simply wasn't up to the job.

In purely technical terms then, the Bosch-Getrag system isn't really all that innovative or remarkable. Using a DCT is a new and good idea, though, especially because European consumers are much more receptive to them than they have ever been toward conventional ATs with torque converters.

Angelo

"Why not simple have the electic motor on the back axle and forgo the connection between the frot and rear axle and the extra clutch."

Ben, where are you getting that from? What they are calling the eAD does not seem to have a mechanical connection to the transmission/hybrid module. I think they very clearly state that this setup gets rid of the transfer case and drive shaft.

Compared to other hybrid setups, I don't think this will be complicated, expensive, or heavy. Nearly every auto company is working on developing dual-clutch SMG's like this Powershift, as they are smaller, lighter, and less complex than a typical automatic, create less drivetrain loss than a CVT, and are cheaper than both. Combine that with the elimination of the transfer case and drive shaft, and I think the weight gain is minimal, as they stated.

This would make a lot of sense for the next generation Ford Escape Hybrid.

Angelo

Sorry, Ben - didn't see Rafeal's post (that pointed out the same thing) before I started writing - got a little distracted....

Tim Russell

Humm, since Ford is going to be using PowerShift trannys in the future I wonder if we'll see this system show up in some of their cars.

Mario

"looks incredibly complicated, expensive and probably heavy"
May be, but you can rest the starter, alternator and have the bonus (thanks to dual-clutch) of different ratios for the electric motor-generator, this is very important in regenerative braking and in low-speed electric only mode.
Rear eAD could be an optional.

sjc

A through the ground hybrid might be interesting with small 4X crossover SUVs like the RAV4 or CRV.

You could remove the drive shaft to the back and put the electric motor on the rear differential.

Getting everything synced up could be a challenge, but it might be able to be retrofitted to existing vehicles.

Ben

I see a drive shaft: http://www.getrag.de/media/0000000811.zip

T2

Angelo, From your post :
" Compared to other hybrid setups, I don't think this will be complicated, expensive, or heavy. Nearly every auto company is working on developing dual-clutch SMG's like this Powershift, as they are smaller, lighter, and less complex than a typical automatic, create less drivetrain loss than a CVT, and are cheaper than both. Combine that with the elimination of the transfer case and drive shaft, and I think the weight gain is minimal "

I like the way you state 'weight gain is minimal' isn't that just another way of admitting it is in fact heavier. It also looks pretty complicated. I examined the drawings and to me, its operation was not intuitive. If replacing the transfer case and prop shaft cancels the increase due to a rear eAD, then by the same argument going to a full series hybrid My rant is that both GETRAG and ALLISON are mechanical engineering companies primarily. They are hammers that see every problem as a nail - to use a well worn cliche. As far as personal transportation is concerned they are pushing vacuum tube technology in a semiconductor world. I feel research would be better concentrated on the low cost manufacture of induction motors that can do 14k rpms. And would be better concentrated on the low cost manufacture of a single stage reducer using chevron gears, or even a planetary gearset built into endbells of two of the aforementioned motors as was done with the original EV-1show car. Finally, research would be better concentrated on the low cost manufacture of 6-pak inverter modules with 460vac 300A capability. Stepped transmissions with two clutches can then just go away.

We have to stop saying that something is too expensive to do, like it was said about flat LCD screens but look where they are now. I hope not to diffuse my argument but recently brand name Flat Screen technology in the 32 inch size became priced the same as brand name CRT tvs were selling just three years ago. It appears that with electronics sometimes when change comes, change comes fast. That is a good reason not to waste time on yesteryear technology. The introduction of a new mechanical transmission this late in the game is like finding a hickey on a cadaver - unexpected and pointless !
T2

G

Question:
How is the motor grounded on hybrid drive vehicles?
Thanx

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