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Electric hydraulic hybrid

power under pressure....
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Reading all the stories about electric-combustion hybrids I wonder why Hydraulic is not used. The setup is as follow:

1. Use an electromotor to pressureize a Hydraulic system.

2. This Hydraulic system has a pressure tank where pressure is built up and stored.

3. Use a Hydraulic motor to drive the wheels direct via a axle.

4. The Hydraulic motor can again be used for breaking too, and at the same time pressureize the system. (re-generation breaking)

5. The accelerator is just a valve in the system.

6. All gearboxes are gone (losing weight, cost etc)

I realize that you do require a big tank, high oil flow etc. And I have no idea about the efficiency of hydraulic systems. But I do know that an hydraulic motor eliminates the need of any transmission. And that the powercurve of such a motor is flat. It also allows a electromotor to run at a constant (optimal) rev.

Am i missing anything here? Or is it a great invention????

(i keep on editting this post....)

EmileB, Dec 02 2003

Performance plot of motor http://www.rineer.c...FDAT_15_15_2K3.html
See one of my own responses [EmileB, Oct 04 2004, last modified Oct 21 2004]

AC Hydraulics. http://www.halfbake...ulic_20Transmission
Alternating current, not air conditioning. [gabe, Oct 04 2004]

baked by UPS! http://www.seedmaga...cess_at_the_epa.php
[bleh, Aug 22 2006]

[link]






       I'd expect this to be pretty heavy, but I could be wrong.
phoenix, Dec 02 2003
  

       The main purpose is to eliminate all transmission needs. So no gearboxes what so ever in the design. Then you would say: Use a direct drive electormotor. Nice, but puts extra weight in the wheel. and the wheel is the pre-suspention part of the car, and thats the place you want to keep as light as possible.   

       http://www.rineer.com/WEBPAGES_2K1/PERFDATA/PERFDAT_15_15_2K3.html This shows an 140 HP motor at 1400 rpm with the weight of only 43lbs.   

       I am not much of an mechanical engineer to figure out if this can be used for it, but it for sure looks in my limited mind promissing.   

       Emile
EmileB, Dec 02 2003
  

       Some farm implements use hydraulic pumps for motive power. 'Hydrostatic' they call it. Usually driven by a big gas engine.   

       You don't have to sign your work, the text does that for you. Also, use the 'link' button below your idea to post a link. Keeps 'em organized and keeps the page from getting wrapped too large by long links.
RayfordSteele, Dec 02 2003
  

       I have been going too fast in writing down my idea's. Yes, I want to eliminate all mechanical transmissions. The reason is weight and efficiency. Gearboxes weight a lot and eat up a lot of power. Besides that I want to keep it all "of the selve" . Sorry, I missed that part. Hydraulic seems to me a nice methode to transfer power. But I have no idea about efficiency rates...   

       So I will edit the original text.. Thanks.
EmileB, Dec 02 2003
  

       Excellent idea. Hydraulics are small light powerful and you could run the engine at constant revs. Brabham made a 1 litre Formula 2 car with a Honda engine and Daf transmission a while back that ran at constant revs. Scary little thing, hurtling into corners at 10,000 rpm. I think this has been done though. I'm pretty sure someone built a Triumph Herald with hydraulic motors in the wheels. I seem to recall that the wheels could be put individually into forward or reverse which, with the Herald's lock made a pretty impressive parker. A hydraulic motor would make a dandy brake too.
peterm, Dec 02 2003
  

       Sounds like a very elegant solution to me. Efficiency might kill you, but it's definately worth looking into.
Worldgineer, Dec 02 2003
  

       Don't judge a dutch guy for bad engish.. Which halfbakery genious came up with an idea for a spell check on the text entry boxes?????
EmileB, Dec 02 2003
  

       I had assumed it was all electric, but a re-read indicates a gas engine is involved as well. Thinking about this further, I don't see why you can't just get rid of the electric part and have a constant speed engine pressurize the system.
Worldgineer, Dec 02 2003
  

       You could use the pulsed hydraulic system which I proposed a while back which everybody hated and I'm still bitter about even though it was an excellent idea and I don't need to impress you and it would be more efficient than conventional hydraulic drivetrains no matter what you say so there....pfffft....
gabe, Dec 04 2003
  

       Sept. 2006 popular science article mentions "hybrid hydraulic" engine. Charles Gray of EPA Advanced Technology Division states: "I can hold a 500-horsepower hydraulic pump motor in my hand, and I'm not a big guy." The "hybrid hydraulic" "returns at least 70 percent of the braking energy back to the wheels. It uses compressed nitrogen gas rather than a liquid. It is not clear to me why a 500-horsepower hybrid pump motor would not also be seen as the primary motor rather than just an auxiliary system to return braking energy to the drivetrain! Combining this halfbakery idea with the EPA idea seems right, after all, we already have a 400 horsepower electric car (see TeslaMotors.com or ProEV.com ) so why not put it all together and get 1000 horsepower in an engine that can be lugged by one Schwarzenegger. How about proposing this halfbakery idea as a strategic partnership with the EPA/Ford/USArmy who haven't quite thought things through. (EPA did patent their hybrid hydraulic but it seems like they have been sort of sitting on it for a few years at least.) Remember also that Tesla the inventor around 1904 came up with his favorite invention which was the "surface boundary layer effect turbine" as a way to stop the incredibly stupid gasoline internal combustion engines and diesel engines which he hated with a passion. So that might figure into this. If the key system is a pump, then the Tesla turbine (which is reversible and can be used as a pump), should be considered. Present-day turbines can be improved; Capstone is not using the Tesla turbine as far as I know, and also a recent turbine blade improvement for standard turbines has been made by an MIT professor which offers huge turbine efficiency improvements (this alone could eventually wipe out any future energy crisis). So its not an energy crisis, its a stupidity crisis and an ignorance crisis. But halfbakery knows this.
LedFut, Aug 15 2006
  

       I don't think we have a stupidity crisis at all. In fact, stupidity seems to be in plentiful supply.
jutta, Aug 15 2006
  

       The hydraulic pump regen. braking would be neat, but I think the accumulator would have to be gigantic, and I would assume that piping would have to be large as well. There would be a lot of friction heat in the oil, how would you use this heat to some advantage? I think that friction and heat is one thing that gives electric hybrids the advantage here, and I think the accumulator would have to be much larger than a battery bank.
wittyhoosier, Aug 15 2006
  

       UPS has hybrid delivery trucks now (see link). they use almost the same system you describe here and claim a 60-70% fule efficency increase. they use desiel to charge the tanks though
bleh, Aug 22 2006
  

       A good idea, fur sure. Check out your basic convertible top drive mechanism = electro/hydraulic pump as described.
fasteddy, Jan 16 2009
  
      
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