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Toyota Prius, Toyota Highlander Hybrid, Ford Escape Hybrid, Hybrid Cars, Coupe, Hatchback, Truck, Sedan, SUV
#13 of 22 Re: hybrid [wwest]
Feb 04, 2009 (8:19 am)
wwest said: "Maybe a 40,000 PSI hydraulic pump/accumulator and a few gallons of ATF. "
wwest is right. See Hydraulic Hybrid Truck saves 50% fuel in stop-n-go UPS delivery style driving!!!! -- click here.... And for the comment about using ATF fluid, I know for a fact that there is a wonderful biodegradable hydraulic fluid on the market now, so there is no problem there, either.
Actually, I think they run the accumulator at 3,000 PSI. Works great on trucks in city driving cycles. How does 50% fuel savings for those massive fleets of UPS, Fedex, garbage trucks, local mail trucks, etc. sound to you? Obama should be putting TARP money and/or econ stimulus money into that to sock-it-to the mideast and Chavez (Citgo)! And who in this economy doesn't use Fedex, UPS, garbage trucks, and/or the Post Office on a regular basis? It would benefit every working man out there and stim the econ, too. Those big-ass trucks suck diesel like its going out of style. And the pollution it would cut? Another benefit. (Vote for me after Obama is done, and I'll fix stuff.)
Tesla would have a hard time using hydrualic accumlators because of the space limitations on a sports car chassis, although if they come out with a sedan and devote half the trunk space to it, then we got something......
I'm with the group that hates batteries. They are too heavy and expensive. None of which appeals to the engineer in me (performance) and economist in me. Still, I know electric hybrids can work very well for many applications, of course.
Tesla could cut down the cost of their laptop-computer-battery monstrosity if they cut the amount of batteries in half and put a sweet little low-friction internal combustion gas engine in there. Remember, freight trains have been using a series hybrid arrangement (no transmission) for many years, and that is essentially like an 80% efficient transmission, not great, but acceptable, and I don't even think a freight train stores much of its excess energy in what very minimal batteries (lead-acid) they have on board.
#14 of 22 Re: hybrid [wwest]
Feb 04, 2009 (12:29 pm)
-wwest, I do understand your strategy. Many other posters here and elsewhere suscribe to the same strategy, I admit.
They all start with what is a basic BEV and then add what Coldcranker just described as a sweet little low-friction internal combustion gas engine.
This does indeed reduce the need for substantial onboard storage of electrical energy. The problem is we can't do that with the Tesla.
We can't just remove half of the Tesla's battery since that would cut the Power Capability of 220 Kw in half as well.
Obviously that would compromise performance. A situation that it won't be possible to redress even with help from that small gas engine which I assume to be designed with technology significantly beyond that permitted in a lawn mower engine in terms of emissions and fuel efficiency. Consequently the engine has to be added to the Tesla on top of what is already there and won't be displacing any battery.
That aside, what seems to be missing from this range extender strategy is that the infrastructure to support such an internal combustion engine is not minor. Considerations for air intake and exhaust, pressurised fuel storage for the fuel injection system, and provision for a cooling radiator will still exist. The costing for these parts won't be significantly below that of a conventional automobile engine. Manufacturing costs just do not scale down very well - as much as we would like them too.
That being the case one might as well select an engine with increased bore diameter and operate it at increased piston speeds for a lot more power as per the previously described Honda engine with its optimized cylinder head cooling and oil jet-cooled pistons. Then there is still the option to go even further with the use of a titanium con rod and sodium filled valves, With such an engine we can start extracting some real power and dispense with a storage battery entirely.
For the Tesla I would think that at least two of these engines would be required but they could share the infrastructure.
Since there are no mechanical couplings, when cruising only one engine need be operational at a time.
This is all known technology and does not rely on the longterm properties of Li-ion battery arrays nor hydraulic/accumulators running at potentially dangerous pressures.
The Tesla model swaps 600lbs of engine technology with 600lbs of boutique priced power to provide off the line performance second to none, additionally getting 'off oil' - perceived by some as a bonus.
Only experienced drivers in Ferraris and Lambos will give this vehicle any competition at all. With superlative throttle response, on the track, this vehicle will come out of the turns faster than any gas powered vehicle. On that account I can see it having its own racing series.
However I believe all this is due to the electric drive and not specifically due to the Li-ion power source. When it comes to power to mass I am convinced that the reduced mass of the series hybrid approach is also viable and although it may not be completely off-oil as others would want, it certainly will be an off-a-helluva-lot-of-oil design.
#15 of 22 Re: hybrid [toyolla2]
Feb 04, 2009 (3:37 pm)
Back when I had my name on a list for an early purchase of an RXh I was considering this issue, but in a different aspect. Removed my name when it became obvious teh RXh was aimed at "boy-racer", 0-60MPH, type personalities.
My thought was to buy a "tag-a-long" one wheel trailer on which would be mounted a 12-16KW (18-24HP) solid state inverter CNG genset used to continuously "charge" the hybrid battery. The idea would be to size the genset so it would run mostly at 80% throttle during constant speed highway cruising and only go WOT for "make-up".
#16 of 22 Re: hybrid [wwest]
Feb 04, 2009 (7:13 pm)
wwest, The only thing wrong with having an internal combustion engine to do nothing but charge the batteries is that energy produced by the engine itself is only about 30% efficient, and then the act of charging batteries is about 50% efficient, so you are left with 15% overall efficiency, very low. It is why the Chevy Volt engineers decided NOT to try and charge the batteries on board up very much (only enough to keep them at minimum charge). The Chevy Volt pretty much works like a diesel-electric freight train (very common for years) where the internal combustion engine simply turns a generator and the current from that flow mostly directly to the electric motor to turn the wheels. The battery only gets leftover power enough to maintain a minimal state of charge.
#18 of 22 Tesla hybrid
Feb 05, 2009 (9:11 am)
look we are getting a bit off topic here with mechanical systems and the Volt There are the Advanced hybrids forum for normal cars and also the Volt forum, we should continue on those.
The Tesla is on its own as a hybrid application due to the power required. It will definitely require a multicylinder engine if it is to run on oil, although for our personal transportation needs I feel that is exactly the type of engine that we should all be trying to get away from .
#19 of 22 Re: hybrid [wwest]
Feb 05, 2009 (12:14 pm)
Thanks for the link. TESLA SHOULD DO THAT!
Hydraulic hybrids kick butt, man. Big trucks and whatever can benefit.
If Tesla did this hybrid arrangement (forget battery crap!), they would have a rocket ship off the line. People should understand that hydraulic hybrid TORQUE is incredible, very high. Thats why Tesla, wanting to give us a satisfying sports car, should give us this accleeration kick.
That answers the purpose of this thread exactly. Thats why Tesla would want to "go hybrid".
#20 of 22 Re: hybrid [coldcranker]
Feb 05, 2009 (3:03 pm)
Very few of us in "this" market are looking to take off like a rocket ship.
#21 of 22 Re: hybrid [wwest]
Feb 05, 2009 (8:28 pm)
wwest said "Very few of us in "this" market are looking to take off like a rocket ship."
Huh? This is a Tesla thread. You didn't know that a lot of the appeal of buying a Tesla is the amazing acceleration you are getting in a sports car? I think its something like 4 seconds 0 to 60 mph. Thats HUGE in this market. This ain't no Prius thread. The snail-lovers are over there. Prius takes 11 seconds to get to 60.
Any Tesla-going-to-hybrid has to keep that Tesla-wild acceleration intact, at least most of it.
When people pay their $100,000+ for a Tesla roadster, at least they get neck-snapping accleration, and Tesla is proud of that.