Comments on: KERS explained: how a mechanical Kinetic Energy Recovery System works

By: keiththeengineer

keiththeengineer — Mon, 12 Oct 2009 18:53:14 +0000

as a thought could not a kers system be done with harnessing the air compressing ability of the engine to first of all provide braking and then a store of compressed air to provide boost air to replace the now missing ram air due to cornering slowly or even as a pseudo turbo … would be easier to make than the other systems only pipework and valves and a storage volume which is to all intents and purposes empty air at 10 bar which if incorporated into the structure would make it very very stiff when inflated

By: build

build — Fri, 05 Jun 2009 06:11:16 +0000

I’m no expert but I’m told …
Don’t really need two rotors, the flywheel is actually very, very light but spins incredibly quickly therefore the gyroscopic effect is minimised and I would imagine on the inverse plan to the engine.

Someone said “As soon as braking stops the spinning flywheel will also start slowing down” … The flywheel runs in a vacuum with so called frictionless bearings so the loss is absolutely minimal even over many months of storage. I’m told as many as six months, so it can retain the energy for a much greater time than a single lap.

Someone said “the flywheel operates only operates when the engine is turning”, that is incorrect the flywheel continues to spin for months or until all the energy is drawn from it.

hth,
build

By: Ben

Ben — Mon, 30 Mar 2009 09:05:04 +0000

Needed too know!! Thanks. not even that into f1. just the tech/mech.

By: Max

Max — Sun, 29 Mar 2009 14:08:59 +0000

It’s interesting how they use the green button. In qualifying 2 we saw Kimi just tap the green button at the start of a straight and the KERS seemed to stay on for a pre-programmed time. In the race we saw others mixing it up a bit more.

By: Robert McKay

Robert McKay — Sun, 29 Mar 2009 13:54:48 +0000

No, I don’t think so. The charging only happens under braking, so I would imagine that the system recharges as much as it can whenever the brakes are applied. Don’t know how they manage to maintain a consistent brake balance.

Cheers. It sounded like Croft on R5L was alluding to that being the case (the driver selecting when to charge I mean) but I wasn’t sure if this was the case.

Just another of the many complications of KERS that the fans are somehow meant to know about

By: Max

Max — Sun, 29 Mar 2009 13:49:51 +0000

No, I don’t think so. The charging only happens under braking, so I would imagine that the system recharges as much as it can whenever the brakes are applied. Don’t know how they manage to maintain a consistent brake balance.

Unfortunately the “batter bar” on the TV only shows the time allowance left for that lap, not the state of charge of the system.

By: Robert McKay

Robert McKay — Sun, 29 Mar 2009 13:44:10 +0000

Just while we’re talking about KERS – is it true to say that the driver chooses where and when it “charges up”? So it’s not that the system automatically charges itself wheneve braking, but the driver has to push a button to charge it when they want?

By: Mahmoud Samir

Mahmoud Samir — Sat, 28 Mar 2009 08:55:25 +0000

hi, for sure gyroscopic effect is taken into consideration
so they should use 2 counter rotating flywheels or they should choose the best orientation position for the flywheel & the least severe orientation is to have the flywheel’s rotational axis perpendicular to the road or track

By: George Ruthven

George Ruthven — Fri, 27 Mar 2009 10:28:54 +0000

When braking the flywheel is attached to the drive system and wound up untill the brake is released. The spinning flywheel is now available for a few seconds to transfer its spinning back to the drive wheels. As soon as braking stops the spinning flywheel will also start slowing down and most probably be useless by the end of the round if no more braking is done. It is possible with a sufficiently large flywheel to stop the car in total because a large flywheel will require all the energy that is released when coming to a standstill etc. Hope this helps.

By: Max

Max — Thu, 26 Mar 2009 22:19:32 +0000

No, the large black cylinder on the right is the carbon-fibre flywheel. The two metal discs to the left of it, with bearings in the middle, are the discs of the variator (continuously variable transmission).

By: Worrab

Worrab — Thu, 26 Mar 2009 22:05:21 +0000

Perhaps there are two flywheels working in opposite directions?

By: Alejandro

Alejandro — Fri, 23 Jan 2009 00:45:48 +0000

That makes a lot of sense, many thanks Max!!!

By: Max

Max — Fri, 23 Jan 2009 00:12:13 +0000

Generally the advantage of an epicyclic gearbox over a simple pair of spur gears is that you get multiple contact with the input pinion. The load is shared between the three or four contacts with the planetary gears, so the gears can be much smaller. As well as resulting in a compact gearbox, it enables you to use a smaller diameter pinion gear, so reducing the tooth speed – possibly a major consideration when it’s doing 64000 rpm.

By: Alejandro

Alejandro — Thu, 22 Jan 2009 17:21:38 +0000

@ Max

Thank you. Now, the reason behind using said epicyclic gearbox as opposed to a simpler reduction mechanism, is it robustness? performance?

By: Max

Max — Thu, 22 Jan 2009 10:59:28 +0000

Note that the maximum output of current KERS devices is limited to around 80 bhp – so only around 10% extra power. And the driver is in control of it and will know what to expect. Rather less dramatic, and more predictable, than a turbo coming in.

Would be nice if they had something on the TV so that we could see when the drivers were using it.

By: Max

Max — Thu, 22 Jan 2009 10:52:58 +0000

The reason for the epicyclic gearbox, in additon to CVT, is to get the revs down from the 64000 of the flywheel to something that the CVT can survive at. It would be extremely difficult to built a CVT to operate at 64000.

By: Keith Collantine

Keith Collantine — Thu, 15 Jan 2009 13:15:19 +0000

As I understand they have a set quantity of use per lap, which translates to 6.6s if the KERS operates at maximum power. They can use that in multiple bursts per lap, not just one long shot. Perhaps at some circuits it would be more beneficial to have a lot of little bursts of power than one big blast.

By: Alastair

Alastair — Thu, 15 Jan 2009 12:54:50 +0000

Hey Keith, in another post (which I can’t find) you said that the KERS boost may only be used once per lap, but http://www.formula1.com/news/technical/2009/0/611.html says it “may be used for up to 6.6 seconds per lap”. Is that one 6.6 second boost or six 1.1 second boosts?

By: theRoswellite

theRoswellite — Thu, 15 Jan 2009 01:47:10 +0000

Lots of questions! So, I’ll only add a little one.

Luke S: his question about gyroscopic effect…will it be a problem? (Do we have a mechanical engineer in the crowd?) I can’t believe they would go to all the trouble of building this if GE was, in any way, a significant problem.

By: Alejandro

Alejandro — Wed, 14 Jan 2009 21:17:01 +0000

Excellent article, but damn, wish i could say i fully get it . For one thing i don’t get the need behind the epicyclic gearbox, one would think the CVT would take care of all gearing?
Also, would i be correct in thinking the energy stored would decrease over time? ie, after braking the flywheel speeds up, but then starts spinning down due to friction?
If significant power is lost to friction, then the best moment to use it would be shortly after heavy braking.