Oerlikon Graziano showcasing family of hybrid and EV transmissions at VDI Wissenforum
19 June 2013
Transmission specialist Oerlikon Graziano, an Oerlikon Business Unit and part of Oerlikon’s Drive System Segment, will present its family of hybrid and electric transmission systems at VDI Wissenforum. Among the systems to be shown are:
A four-speed seamless-shift transaxle. The new eDCT multi-speed transmission provides EVs with greater range while reducing vehicle weight and battery pack size. This innovative transaxle uses the principles of dual clutch transmissions (DCTs) to provide seamless shifting and up to 15% improvement in vehicle efficiency. (Earlier post.)
A hybrid transmission with torque infill, the OG-Eco. The technology combines the seamless shifting benefits of a Dual Clutch Transmission (DCT) with the packaging and weight advantages of an AMT. The gearbox can be combined with a hybrid system that is fully integrated into the transmission package.
The electric motor is linked to the main transmission through a two-speed gear set, providing torque to the drivetrain in between gear selection enabling constant torque delivery. The technology combines two benefits: engine working in a more efficient condition and smoother gearshift compared to a traditional AMT. It also allows vehicle manufacturers to further benefit from their investment in hybrid technologies, by optimizing the efficiency and overall system weight.
For passenger cars and light commercial vehicles the company will exhibit a dual-speed seamless-shifting transaxle that can be coupled with a transversal electric motor, for front or rear full electric axle. The transaxle has been developed together with VOCIS Driveline Controls, contributing with its control software and electronic hardware design skills to the transmission design.
Electric drive is a field where integrated system-level optimization is the only way to offer significantly improved customer benefits and our efforts are aimed at increasing as much as possible the integration level of motor and transmission within the powertrain. Another crucial element for us is the innovation level of transmissions conceived for the ultimate electric and hybrid vehicles: our multi-speed concepts are the most suitable for a modern full electric or even hybrid vehicle, allowing the best sizing of the electric motor and usage of batteries’ power.
—Paolo Mantelli, Head of Performance Automotive Oerlikon Graziano
The speaker makes the point that emotors have optimum operating conditions that can be complimented by transmission optimisation.We hear a lot from the electrical/ electronic designers, but not as much from the other perspective.
Given that so many efficiency benefits are seen from ice systems and the similar electrical efficiency tweaking can offer practical outcomes It makes sense to design the transmissions from the perspective of the motors optimum output.
More on transmission placement.etc
With conventional transmission losses traditionally very large, direct drive with full, partial or nil gearboxes options are available to suit emotor output characteristics.
With increasing usage, the need for new ways of looking at the problem increases as can the returns on r&d so expect see more clean sheet and innovative products coming to market.
Posted by: Arnold | 19 June 2013 at 05:42 PM
I'm not sure what to make of all this. Since electric motors have a high efficiency across their operating range, it seems the room for improvement is limited.
They claims 'up to 15% improvement'. We all know that 'up to' is marketing speak and renders any claim thereafter totally worthless. Average improvement may be 10% or 5% or as little as 1%. Due to the extra components in the drive train, the losses may be even higher under certain circumstances.
If I look at the vehicles taking part in the World Solar Challenge, where optimum use of every single Wh of energy is of paramount importance, they nearly all use a direct drive in wheel motor from CSIRO. 98% efficient. No gearbox. That says a lot. These teams have access to some of the brightest people and best (aerospace grade) technology out there. Why would they choose not to use a gearbox?
107 days until the next World Solar Challenge!
http://www.solarracing.org/
Posted by: Arne | 19 June 2013 at 11:32 PM
An AC or tri-phase electric motor is conventionally designed for a fixed frequency and rpm rate at which it produces given torque from the first revolution. Due to the load on the motor, when accelerating from nil, the apparent resistance of the motor is extremely low and draws immense amounts of current which reduces as the motor gains rpms. These current peaks are rough-shod on the battery and detrimental to battery life expectancy.
A transmission not only adjusts to certain speeds, it is also a torque converter. The greater torque via transmission delivers an even bigger kick to the vehicle at start whilst drawing less current from the battery and helps to overcome the crux situation as described before. A transmission definitely improves the wear and tear situation for a battery which is one of the most expensive items in an EV.
Posted by: yoatmon | 20 June 2013 at 04:21 AM
Anne, I think you hit it, if you look at the successful hybrids and EVs sold now, they have very minimal transmissons, in the hybrids a single planatary gearset, in the EVs just a gear reducer. Some of the experemental inwheel motor systems have none at all! If your business is making transmissions you have to be worried. I think something will be needed for a time, wheelmotors increase unsprung weight but the traditional multispeed transmission is on it's way out, replaced in part by electric motors, (or in pure EVs largely eliminated).
Posted by: Dave K. | 20 June 2013 at 05:39 AM
There have been previous posts on GCC detailing efforts to make multi-speed EV transmissions in order to operate the e-motor at speeds where it is more efficient. A lower gear also allows greater starting torque than a single speed provides, improving performance.
Because their application is highly optimized for cruising, mostly on level ground. Towing, hill-climbing and stop-and-go operation with lots of regenerative braking may benefit from a multi-speed transmission.
Posted by: Engineer-Poet | 21 June 2013 at 05:07 AM
Moving 2+ tons from '0' to '100+ kph' will always require energy regardless of how many in-wheel e-motors and/or multiple-speed transmissions are use.
Effective ways to reduce the energy required would be to reduce the weight of the vehicle (from 2+ to under 1-ton), reduce the size of drivers and passengers, increase drive train efficiency, reduce frictions and drag and reduce peak energy demand by reducing acceleration rate.
All the above can be done in the next 10 years or so.
However, a simple 2 or 3 speed transmission would help for hill climbing, towing and braking energy recovery?
Posted by: HarveyD | 21 June 2013 at 08:22 AM