923 replies to this topic

[Melbourne Park]

I think that F1 is only allowing electrical hybrid systems, which IMO is a shame.

[imaginesix]

Originally posted by Melbourne Park
How about a spring, which sounds lighter to me? Maybe not as linear, but the driver could unleash it when there's more grip available.

Or maybe a spinning disk for energy storage?

Would the most efficient light weight brake recovery systems require four wheel drive?

Wouldn't one also need drive shafts from the front wheels to the energy storage/conversion area?

A cylinder of compressed air is also a spring. The way I visualize it is a 1000kg car hitting a deformable barrier at 160km/h and coming to a stop in 4.5 sec at a steady rate (which I believe works out to 100m). Would it be better if that barrier were a huge pneumatic cylinder or a big solid spring? Keeping in mind of course that the chosen energy storage device would have to be carried on-board.

Flywheels are a worthwhile consideration too. How much space would they take? What would it take to spin them up to full RPM in 4.5s? How much weight would they be? That's part of what I'm asking.

As for AWD, I can't image a 1G braking capacity using only the front or only the rear wheels, but if it works then it meets the requirements of my original question. And you wouldn't necessarily need driveshafts at each wheel if powerful enough motors can be integrated into the wheels.

[crono33]

i am not sure whether you got thise piece of info directly or second hand but is not that simple. nobody would take money from unknow people and in many cases even from known people.
and even though for sure corruption is widespread, it is not a matter of "bribes"
the reality is that systems like public healthcare work as a substitute of welfare, hiring unnecessary people and distributing thousands of unearned wages, at the same time getting votes, and also has the function of "redistribution". it might sounds funny, but some governments dont see taxes as a way to pay for necessary services, but as a mean to redistribute wealth in a more "just" way :-)

why do you want to kill this thread? gives non-engineers like me the opportunity to write something, every now and then :-)

Originally posted by NRoshier
sorry drawing a point from your italian example and generalising to the rest of the world or even the rest of italy is more than foolish. Try and do any business in parts of italy without paying bribes. Now is this a feature of anywhere else I have lived...no.

[robroy]

I read in one of the weekly auto magazines that Volvo are planning a hybrid ev with motors in the wheel. The article said that no friction brakes were required, but was lacking in any technical details.
I've also come across this package which uses disc brakes and motors within the wheel, and some sort of sliding pillar looking suspension:

http://www.youtube.c...feature=related

The Mitsubushi in wheel concept also incorporates disc brakes:

http://www.youtube.c...feature=related

[McGuire]

Originally posted by crono33
the reality is that systems like public healthcare work as a substitute of welfare, hiring unnecessary people and distributing thousands of unearned wages, at the same time getting votes, and also has the function of "redistribution". it might sounds funny, but some governments dont see taxes as a way to pay for necessary services, but as a mean to redistribute wealth in a more "just" way :-)

You shouldn't be so hard on the Swiss health care system. It's really not all that bad. Sure, it is highly subsidized and socialized -- far, far more socialized than in the USA for example -- but the quality of care is apparently very good, and you do have universal health care. However, the cost is extremely high: you have the highest per capita health care costs in Europe, and the second-highest in the world.

[McGuire]

Originally posted by robroy
I read in one of the weekly auto magazines that Volvo are planning a hybrid ev with motors in the wheel.

Yep, they sprang that as a concept car at the Frankfurt Auto Show this year. Called the ReCharge I think. I have no idea how close it is to reality. It uses the PML Flightlink setup... they have a New Mini with the system they have been showing around.

[Greg Locock]

The ultimate limit on an electrical braking system is what the battery/capacitors can absorb. If you exceed that then you have to start using big resistors - and it seems to me that resizing all your motor and motor controller merely in order to heat resistors up is a bit crazy.

Hydraulic accumulator systems are powerful enough, and have appeared both on demo cars and I think are in production for garbage trucks.

Bear in mind that braking systems have to be sized for the worst case, not an average case. For automotive use that means they have to handle long descents, ie accumulate a lot of energy, as well as handling spike stop loads in the order of hundreds of kW.

The reason you use a parallel mechanical braking system is (a) redundancy and (b) >95% stops are at 0.4g or less, so the incremental useful energy captured in that last 5% of stops is not a huge proportion.

[imaginesix]

Originally posted by Greg Locock
Bear in mind that braking systems have to be sized for the worst case, not an average case. For automotive use that means they have to handle long descents, ie accumulate a lot of energy, as well as handling spike stop loads in the order of hundreds of kW.

The reason you use a parallel mechanical braking system is (a) redundancy and (b) >95% stops are at 0.4g or less, so the incremental useful energy captured in that last 5% of stops is not a huge proportion.

The reason I didn't mention inclines in my performance criteria is that it should be easy enough to free up some more room for energy storage in a long descent by either 'bleeding off' the pneumatic accumulator or by 'unwinding' the mechanical spring. The PCM would simply be programmed to control all elements of vehicle performance (including KERS) in whatever way necessary so as to ensure that the car always has the capacity to perform a full 1G panic stop.

As for your analysis of the merits of parallel braking systems, I believe it is oversimplified. First of all the small number of hard stops represent a disproportionately large amount of lost energy, so that 5% of stops may waste 10% or more energy. Also, existing KERS (electric hybrids) can only recover a fraction of the energy from a mere 0.4g deceleration, so there is far more wasted energy than you suggest, perhaps on the order of 80%. 90 if you're an enthusiast driver.

The real problem though is even if a higher-capacity KERS is developed in the near future, that would make it possible to drive the car daily without ever touching the friction brakes for months. As you know, this is very unhealthy for the brakes and can be disastrous if they are ever needed in a real panic situation. For this reason I believe that any improvement in a KERS would have to be so effective as to be able to supplant the friction brakes altogether. No "small step" improvements here, just "one giant leap". So yes, I realize the 100% KERS that I am discussing is a 'moon shot', but it feels like a technology that is just at the very edge of our grasp right now. But that's why I'm asking. Is it within our grasp?

BTW, there is another significant energy saving-advantage to a full KERS in that powertrains could be substantially downsized as they would no longer be required to perform the task of accelerating the car from a standstill. The average car could need only 35hp, performance cars could run with only 70. And cars like the 1000hp Veyron would end up properly categorized as the monsters that they are.

[Andy Donovan]

Originally posted by imaginesix
The real problem though is even if a higher-capacity KERS is developed in the near future, that would make it possible to drive the car daily without ever touching the friction brakes for months. As you know, this is very unhealthy for the brakes and can be disastrous if they are ever needed in a real panic situation.

A bit of thinking aloud here, but could they bridge the gap with some kind of friction braking system with sacrificial pads for emergency stops? I don't know what it would be off the top of my head, but some sort of brake material that would happily sit there for a year or two unused, but would burn itself away in the event that the KERS isn't able to provide enough braking power.

[McGuire]

And the end of all our exploring
Will be to arrive where we started
And know the place for the first time
- T. S. Eliot


Hey, great sig line. From Little Gidding... ya know, Eliot considered The Four Quartets his masterpiece, above The Wasteland and The Love Song of J. Alfred Prufrock. Don't know if I agree with that, but it is pretty damn good.

[imaginesix]

I don't know any of those works you mention. I just saw the quote and liked it.

I have Bertrand Russell's autobiography buried behind a pile of furniture, and I intend to read it before I die. Probably won't though (not that my death is imminent or anything).

[imaginesix]

Originally posted by Andy Donovan
A bit of thinking aloud here, but could they bridge the gap with some kind of friction braking system with sacrificial pads for emergency stops? I don't know what it would be off the top of my head, but some sort of brake material that would happily sit there for a year or two unused, but would burn itself away in the event that the KERS isn't able to provide enough braking power.

Yeah, that's a good point. Brake systems could be redesigned in some way to perform in the different environment presented by a full KERS system. For example there presently exist floating disk carbon brakes that while price-prohibitive for us commoners, don't have anything to seize or oxidize AFAIK.

[Canuck]

All this time I've been wanking that there are no Canadian car companies (unless you count Ford Canada, GM Canada, etc...which I don't). Turns out that Quebec, home of the 3-wheeled Raptor, is also home of the Zenn car - Zero Emissions, No Noise. Apparently they sell them in the US, but not in Canada...'cause they aren't legal here. Go figure.
Zenncars.com

[imaginesix]

I heard on CBC that there are something like eight, count them 8, Canadian electric car manufacturers. Apparently their competitiveness is being hampered by short-sighted bureaucrats (ie they can get much more significant government funding if they move to some states like NY).

[Canuck]

I know that Merch Performance (an aftermarket v-twin manufacturer formerly in Alberta) had nothing but problems dealing with the provincial and federal governments. He finally got sick of the hassles and stunning lack of support and moved lock-stock-and-barrel to Colorado (I believe). The Canadian government has a remarkable tendencey to crush anything not oil-related.

[Todd]

Originally posted by imaginesix
I heard on CBC that there are something like eight, count them 8, Canadian electric car manufacturers. Apparently their competitiveness is being hampered by short-sighted bureaucrats (ie they can get much more significant government funding if they move to some states like NY).

It is amazing how you can use a term like competitiveness in a sentence about taxpayer subsidies without irony. Or it should be anyway.

[cheapracer]

Originally posted by Canuck
All this time I've been wanking that there are no Canadian car companies (unless you count Ford Canada, GM Canada, etc...which I don't). Turns out that Quebec, home of the 3-wheeled Raptor, is also home of the Zenn car - Zero Emissions, No Noise. Apparently they sell them in the US, but not in Canada...'cause they aren't legal here. Go figure.
Zenncars.com

Can Am have been making bikes forever and now also have a 3 wheeler.

Annoys me the 'zero emissions' tag, electricity comes at a cost upstream as we all know.

[cheapracer]

Originally posted by McGuire
This thread needs to die. Lethal injection, cattle gun, whatever it takes.

Avert your gaze.

[scooperman]

After I get rich, I will buy a country and become king. Then I will have all my subjects study engineering and have them get started working on a practical KERS technology. I have decided KERS does not belong on vehicles. I decree that it shall be implemented in the road surface approaching intersections. So let it be written, so let it be done.

[imaginesix]

That's crazy. If all your subjects are engineers who's gonna patent the thing?

[crono33]

oops. sorry for not being very clear. i was talking about the italian system.

such thing as i have described could never happen in switzerland.

Originally posted by McGuire


You shouldn't be so hard on the Swiss health care system. It's really not all that bad. Sure, it is highly subsidized and socialized -- far, far more socialized than in the USA for example -- but the quality of care is apparently very good, and you do have universal health care. However, the cost is extremely high: you have the highest per capita health care costs in Europe, and the second-highest in the world.

[Engineguy]

Originally posted by robroy
Don't think this has been posted before:

http://www.e-traction.com/TheWheel.htm

Interesting solutions for direct drive wheels for commercial electric vehicles.

Anyone think direct drive wheels would be suitable for passenger vehicles? How crippling would the unsprung weight be to ride and handling?

Surely you must realize that all wheel-driven passenger cars have too much unsprung weight at the driven axle.

http://cgi.ebay.com/...tem180207694388

[McGuire]

I assume it has BEAM AXLES front and rear.

[Gerald Ryan]

Engineguy

I remember reading about some engineers in the UK who purchased an old F-1 car minus its Cosworth engine and Hewland box. For some reason they happened to have a gas turbine engine lying around and, being engineers, one thing led to another. The car ended up with the tubine. The drive was by reaction jet (no drive to the wheels). I understand they got a professional race driver to evaluate it and help them get it set up. They ran it on track and it was fast. The handling would have been different from a regular car! The jet-efflux was reckoned to be reasonable and not as severe on following traffic as may ahve been expected. Apart from that I heard nothing more of it. Have you come across this?

Regards
Gerald