KERS - explained


Somewhat related.........
I found this while reading some blurb on the net trying to fathom if I could fit KERS to my 1.6L Laguna... :D

I'm not sure if we already have an article on KERS if so, admin please delete.

"The mechanical KERS system utilises flywheel technology developed by Flybrid Systems to recover and store a moving vehicle’s kinetic energy which is otherwise wasted when the vehicle is decelerated. The energy is received from the driveline through the Torotrak CVT, engineered and supplied by Xtrac, as the vehicle decelerates, and is subsequently released back into the driveline, again through the CVT, as the vehicle accelerates. The FIA has defined the amount of energy recovery for the 2009 season as 400kJ per lap giving the driver an extra 80hp over a period of 6.67 seconds.

“Compared to the alternative of electrical-battery systems, the mechanical KERS system provides a significantly more compact, efficient, lighter and environmentally-friendly solution.

“The components within each variator include an input disc and an opposing output disc. Each disc is formed so that the gap created between the discs is ‘doughnut’ shaped; that is, the toroidal surfaces on each disc form the toroidal cavity.

“Two or three rollers are located inside each toroidal cavity and are positioned so that the outer edge of each roller is in contact with the toroidal surfaces of the input disc and output disc.

“As the input disc rotates, power is transferred via the rollers to the output disc, which rotates in the opposite direction to the input disc.

“The angle of the roller determines the ratio of the Variator and therefore a change in the angle of the roller results in a change in the ratio. So, with the roller at a small radius (near the centre) on the input disc and at a large radius (near the edge) on the output disc the Variator produces a ‘low’ ratio. Moving the roller across the discs to a large radius at the input disc and corresponding low radius at the output produces the ‘high’ ratio and provides the full ratio sweep in a smooth, continuous manner.

“The transfer of power through the contacting surfaces of the discs and rollers takes place via a microscopic film of specially developed long-molecule traction fluid. This fluid separates the rolling surfaces of the discs and rollers at their contact points.

“The input and output discs are clamped together within each variator unit. The traction fluid in the contact points between the discs and rollers become highly viscous under this clamping pressure, increasing its ’stickiness’ and creating an efficient mechanism for transferring power between the rotating discs and rollers.”

There we have it, simple eh? :s

So basically they get an extra possible 80Bhp over 6-7 seconds, almost like the nitro switch in computer racing games, and I always remember what happened when I pressed that... :D
Just a few thoughts on what I understand of the KERS from what I've found so far. In a nutshell it's no different to those toy pull back-whizz forward type cars. Only backwards obviously. It harnesses some of the energy of the braking force to drive the KERS which can be used subsequently to lighten the load on the drive train later.
The mechanicle KERS system stores the energy in a flywheel and therefore doesn't have the electrostatic problems of the electro-mechanical system. The variator system has been used for many years in the machine tool industry, it provides a constant torque output over a range without steps, in a nutshell it is like the infamous DAF variomatics that used a mechanical variator instead of a gearbox. Be interesting to see the effect of the flywheel on the handling, there's an awful lot of processional energy there.
The electro-mechanical system simple uses generating motors to store the electricty in batteries, which in turn drive the motors when needed. Problem here is the batteries, big, heavy, and made from some pretty exotic rare earth materials, and of course the efficiency of the motors. And then there are the rumours of static discharge problems.
What suprises me in all this is that no one seems to be talking of pneumatic systems. Simple freewheel turbines in the brake hubs compress air, storage in an accumulator is pretty simple and the same types of turbines used to re-drive the wheels.
Two colleagues of mine have been to the Mercedes (old Ilmor) factory to look at their KERS system. Unfortunately I couldn't attach myself to the trip as I had no reason to be there and Mercedes are uptight about espionage. My colleagues signed a non-disclosure agreement and have taken it seriously refusing to tell me anything! So I have nothing useful or interesting to add to this thread, I just wanted to share my frustration...
Is it possible that by installing KERS a team may well gain a "boost" advantage but the overall acceleration and speed will drop due to increased friction resistance and moving the weight of the flywheel and ancillaries?

It will be interesting to see how the testing proceeds this winter but of course it will be difficult to quanitfy due to the other changes (slicks, narrower wings, etc.).
Ideally it would be great if we could see some times with and without KERS fitted on identical vehicles but I doubt we'll get to see that data.
I think there are several reasons as to why pneumatic KERs isn't being considered (Mercedes'll prove me wrong now!). Firstly the weight of the bottles required to store the compressed air may well be prohibitive, secondly compressors aren't the most efficient of devices (if i recall correctly from uni), thirdly compressors don't like particulates at all, in fact they are destroyed by them very rapidly, so reliability would be a major issue (especially with all the brake dust/road dirt). I think there would also be serious challenges involved in getting the most of out the energy stored as compressed gas, however if you could place the air storage bottles in the inlet airflow to the engine you could use the cooling of the bottles as they are discharged to cool the inlet air to the engine and boost power further. phew!
Top Bottom