Heard about Volvo's KERS?

[tjts1]

A turbo has substantially less mass and is not mechanically driven through a gear box. From the articles I found, the volvo KERS flywheel weighs 13.2 lb. Now lets spin that up to 60,000rpm and have a bearing fail or better yet how about and old worn bearing and a crash. Any takers?

I'll bite. Let's go back to that example of the GE90-115B; Volvo Aero builds a fiber composite braid primary fan casing, designed to fully contain a fan blade breaking loose at takeoff speed. That's a blade weighing ~35 lbs (~16 kg) with a tip velocity of 400 m/s or ~900 mph (at Standard Sea Level) going at right angles into a composite casing lighter than its aluminum equivalent. I have no doubt that Volvo's engineers will design a flywheel casing capable of containing a loose flywheel as well as, if not better than, their Volvo Aero counterparts which make parts of the most reliable jet engine in the world.

A GE90 costs $25 million dollars. Volvo would have to find a way to stick this stuff in a $40-50k car and still eek out a profit. A G90 gets regular maintenance by trained technicians for its entire service life. This device won't. If the 200k rpm turbo from the example above fails, you replace it for anywhere between $200 to $1000 depending on who does the work. How much is this thing going to cost when the gearbox, clutch, bearings or vacuum fail? I'm sorry but this thing isn't going into production. Volvo is seriously falling behind its competitors at this point. It doesn't have any fuel efficient cars on the US market. They have that C30 EV which is stupidly expensive ($2100/month lease) and the V60 PHEV which is not for US consumption. KERS is fun racecar technology but they need a diesel or a hybrid or some kind of realistic fuel efficient model for sale NOW if they want to at least keep their tiny market share.

[matthew1]

Not to get too far off topic, but tjts1, if Volvo felt very worried about keeping up with high mpg vehicles in the US, wouldn't they have brought over the D5 engine?

By the way, and going even more off topic, I've always thought technical give-and-take in forums was one of the greatest things about the 'Net. I for one am enjoying this topic immensely.

I'm starting to understand why this might not work on a daily driver: think of the torque that's going to come at the flywheel's bearings when the car moves at right angles to the rotation (did I say that right?). At 60k rpm that thing is not going to want to move perpendicularly.

[tjts1]

Not to get too far off topic, but tjts1, if Volvo felt very worried about keeping up with high mpg vehicles in the US, wouldn't they have brought over the D5 engine?

I would have thought so too. It never dawned on them that some Americans are willing to pay a premium for fuel efficient vehicles in the same way that others pay up for a turbo or V8 engine. Lexus, BMW, Audi, Mercedes even Lincoln have diesels or hybrids or both and they've all been successful thus far.I drove an old V70 D5 a few years ago in Europe and I thought it was brilliant. Probably one of the quietest diesels I've ever seen.

By the way, and going even more off topic, I've always thought technical give-and-take in forums was one of the greatest things about the 'Net. I for one am enjoying this topic immensely.

I'm starting to understand why this might not work on a daily driver: think of the torque that's going to come at the flywheel's bearings when the car moves at right angles to the rotation (did I say that right?). At 60k rpm that thing is not going to want to move perpendicularly.

For what its worth, Porsche positions its KERS device on a vertical axis and uses electric motors/generators to move power to and from the wheels.


In F1, KERS is on a horizontal axis. It would make more sense if Volvo could also package it into the engine's gearbox.

[tjts1]

Now it all makes sense.

A light, cheap and very eco-efficient solution that makes a four-cylinder engine feel like a six at the same time as fuel consumption drops with up to 20 percent. This autumn, Volvo Car Corporation will be one of the world's first car makers to test the potential of flywheel technology on public roads. The company has received a grant of 6.57 million Swedish kronor from the Swedish Energy Agency for developing next-generation technology for kinetic recovery of braking energy in a joint project together with Volvo Powertrain and SKF.

http://green.autoblog.com/2011/06/02/vo ... #continued
This isn't a viable technology otherwise Volvo would have paid for the development.

[matthew1]

Ahh, free money, good catch there. That does make a difference.