KERS and BER are acronyms; Kinetic Energy Recovery System and Brake Energy Recovery respectively-------i.e. related to brakes they mean the same thing. Actually BER is more specific while KERS can relate to KE more generally. BER pretty specifically relates to regenerative braking. KERS is somewhat more broad.
BER is used in both EV (electric only) and HYBRID vehicles and is needed to improve the mileage. In this context the BER idea is coupled to the electrically driven wheels and during stopping can provide re-charge energy into the main battery. I have written BLOGS on this subject and won’t repeat that here.
More recently, Audi won the 24 hour LeMans race using KERS ideas. This is similar to hybrids---in fact it has been mistakenly called a hybrid in the usual sense such as in the Toyota PRIUS—it it slightly different. What is a very subtle point is that is has the potential to improve the mileage significantly BUT without some of the cost penalty imposed on say the PRIUS and other current HYBRIDS.
KERS as practiced by Audi does NOT require a large Li-ion battery pack and associated costs. It uses “flywheel” storage and currently two companies---Williams Hybrid Flywheel and Flybrid Flywheel Power offer units. Not to be left out, Toyota is practicing KERS using SuperCaps for the KERS storage element. They did compete this in the LeMans but did not complete the race due to accident. BTW in both the Audi and Toyota case the energy saved allowed them to complete the entire 24 hour race WITHOUT brake pad replacement------VERY SIGNIFICANT.
The two flywheel packages offered by Williams and Flybrid are similar to each other, both claiming patented concepts. Sizewize both are about 30 to 34 inches in diameter and stand between 12 and 16 inches in height. Neither specifies the exact weight but estimated between 100 and 200 pounds. Both state that the top rpm for the flywheel element is 60,000 rpm. In the Flybrid the driving motor armature is INSIDE the flywheel rim. In the Audi configuration the Williams unit is just forward the driver’s feet and works through the front wheels. The conventional ICE drives through a (6-8) speed automatic transmission to the back wheels.
The Flybrid units are being evaluated by Volvo and reportedly Chrysler. The supposed cause for this interest is the 2025 EPA requirement of meeting 54.5 mpg on a fleet basis. I have written a BLOG about Chrysler wanting to build a factory devoted exclusively to build 8-speed automatic transmissions. Chrysler has stated they do NOT plan to build HYBRIDs such as the PRIUS but want to use a mix of EV and conventional to meet the 2025 requirement. Perhaps Chrysler sees the KERS approach as cost effective and perhaps will add it to the conventional 8-speed offering. Volvo has said little about its 2025 plans other than say they will offer EVs.
INTERESTING---
The flywheel axis is perpendicular to the road surface so there is no precession reaction to steering on a level surface. I wonder if it fights pitching, rolling, or twisting into a banked turn?
Posted by: Dick LaRosa | September 26, 2012 at 12:29 AM
Dick--------I think these are both single rotor systems and I suspect they both use “torquerer” drivers to precess the rotor to stay vehicle vertical. No detail info is given BUT this has been used before. Also on the LIRR KESR units TWO rotors driven in opposite rotation direction canalled the effect (BUT put one Helluva load on the bearings as the train rattled along.) Thanks for the comment-----Carl
Posted by: Carl Schwab | September 26, 2012 at 04:02 PM