Could compressed air lead to smaller engines?

Discussion in 'Technical' started by lucky strike, Feb 26, 2009.

  1. #1 lucky strike, Feb 26, 2009
    Last edited by a moderator: Apr 25, 2016
    A 1.0-liter two-cylinder that performs like a 3.0 liter V6? On what planet? Researchers at Switzerland's ETH Zurich school of engineering are developing pneumatic hybrid engines that use compressed air to deliver big performance and efficiency from a small package. During deceleration, the engine's pistons are used to compress air, which is diverted through a special valve and into a holding tank. Rather than try to propel the vehicle directly with compressed air, like Guy Negre's hybrid system, ETH Zurich's setup uses the compressed air as an instant supercharger to gap where a turbocharger would be spinning up.

    The goal is to offer much more efficient engines for less money than electric hybrids. Buyers in China or India can't afford the expensive premium that current hybrids command, so something less expensive has to be found. The compressed air systems would achieve 80% of the benefit while only costing 20% more. Dropping the cylinder count reduces frictional and pumping losses, and technologies like direct fuel injection and HCCI can offer diesel-like efficiency out of a gasoline engine. A small, turbocharged two-cylinder with a compressed air system for oomph when needed could return more than 100MPG in a small, light vehicle. Doesn't sound so crazy now, does it?

    full article
  2. whatever happened to those hydraulic hybrids? I know ford was doing well with an f-150, but it has since disappeared
  3. A hydraulic hybrid system was developed for garbage trucks. It was a pretty good idea, use a hydraulic pump to charge a cylinder filled with nitrogen and a piston, then under acceleration, use the built up pressure and the pump to assist. Its only worth all the extra weight when the vehicle is used for a lot of stops, like a garbage truck.
  4. someone like DHL or UPS has a hydraulic hybrid truck. Think it uses accumulators and uses hydraulic motors for assist on "take-off"
  5. hydraulic hybrids are really only useful for super frequently stopping vehicles, like mail or delivery trucks.
  6. Basically. I do like that the engine is decoupled from the drive components, like in fuel cell systems, allowing for the most effective engine speeds to be used.
  7. might as well use a turbine in that case. more reliable/efficient/etc
  8. Just as loud too.
  9. In the system I was talking about it isn't. The pump is on a pto from the trans, turning on when stopping to store the fluid under pressure, then using that pressure to add power when taking off from a stop. The fluid is send to a tank with a piston inside, that is charged with nitrogen at high pressure. The hydraulic fluid sent to the tank moves the piston, compressing the nitrogen higher, thus storing the energy.

    Like stated above, this is only efficient on vehicles that do a lot of stop and go driving, like garbage trucks.
  10. FI requires higher tolerances. on a small scale, I'd say the answer is no. but if through mass production a tight little motor 1l with FI can be economically as feasible as a 1.6l and provide the same power, there isn't any reason I can see why it wouldn't be possible.

    but I don't see a necessity to do so, either. not yet.
  11. Well, the UPS hydraulic hybrid that is currently testing uses the engine coupled not with a transmission but with a hydraulic pump that uses pumps fluid into a tank which in turn compresses the nitrogen.
  12. Am I the only one that thinks this is a great ideea ?
  13. Edit:
    my logic says:
    compressed air doesn`t go with turbo, but has mostly the same effect.

    So if you have a 100 HP 2.0D engine with compressed air --> 140 HP engine ( claimed +40% efficiencY)
    If you have a 100 KP 2.0D engine with turbo --> 130~170 HP engine

    The main advantages, in my opinion are cooling, weight reduction and of course less friction
  14. #15 SaabJohan, May 19, 2009
    Last edited by a moderator: Apr 25, 2016
  15. #16 FastNclassy, Aug 14, 2014
    Last edited by a moderator: Apr 25, 2016
    The compressed air tank would be empty in short time.

    You can also use electric superchargers, 2014 F1 turbo style.
    This way the batteries and electric motors can be smaller as they only need to power the electric supercharger, thus lighter and cheaper than hybrids.
  16. 2014 F1 cars have normal turbochargers, they are not electronic. The only think special about 2014 F1 superchargers is that the compressor and turbine are separated by a driveshaft in some engines.
  17. #18 962RACER, Aug 28, 2014
    Last edited by a moderator: Apr 25, 2016
    not exactly, many of them are in a sense "hybrid" turbos, as the turbo shaft is directly connected to an electric motor. this is a system that should certainly make it to the mainstream turbo engines because of its effectiveness and ease of application. instead of a wastegate, the electric motor generates power once a desired boost is reached, and the motor can also be used to drive the turbine, aiding in low end spool and engine response.

    and therein is the beauty, as the name implies, a waste gate literally wastes high energy exhaust gases in order to regulate boost, wasting a bunch of energy, which this system recovers.

    "MGU-H is an energy recovery system connected to the turbocharger of the engine and converts heat energy from exhaust gases into electrical energy. The energy can then be used to power the MGU-K (and thus the drivetrain) or be retained in the ES for subsequent use. Unlike the MGU-K which is limited to recovering 2MJ of energy per lap, the MGU-H is unlimited. MGU-H also controls the speed of the turbo, speeding it up (to prevent turbo lag) or slowing it down in place of a more traditional wastegate.

    A maximum of 4MJ per lap can be returned to the MGU-K and from there to the drivetrain - that’s ten times more than with 2013’s KERS. That means drivers should have an additional 160bhp or so for approximately 33 seconds per lap."
  18. They already make something like this, it's called a supercharger.
  19. #20 Veyronman, Nov 5, 2014
    Last edited by a moderator: Apr 25, 2016
    Peugeot-Citroen unveils compressed air hybrid tech

    PSA-developed Hybrid Air system which replaces electricity with compressed air for 81mpg

    Peugeot-Citroën PSA has unveiled a new hybrid drivetrain that uses compressed air instead of electricity to provide a secondary source of propulsion. Called Hybrid Air, the new technology could allow a car the size of a Citroën C3 or a Peugeot 208 to emit as little as 69g/km of CO2.

    Hybrid Air consists of a conventional petrol-powered internal combustion engine, mated to a bespoke epicyclic transmission, assisted by a hydraulic motor that’s powered by compressed air. The motor and a pump are positioned in the engine bay, fed by a compressed air tank underneath the car, running parallel to the exhaust. Using regenerative braking to generate energy, the motor and pump can refill the tank with air.

    It can run on the petrol engine or air power alone, or a combination of the two. Air power would be employed solely for urban use, automatically activated below 43mph, and available for “60 to 80 per cent of the time in city driving,” claims PSA. Three drive modes are provided: full petrol engine, combined (ICE and hybrid) and zero-emission.

    The system adds about 100kg to the weight of a traditional ICE powered small car, which is around half that of a conventional hybrid system. PSA claims it uses very simple, serviceable parts, with no rare metals like lithium-ion. The goal is to devlop a 'global' system that's cheaper than existing hybrids to appeal to China and Russia as much as European markets.

    The firm also cites a 45 per cent improvement in fuel consumption over a conventionally powered car with an equivalent power output, and a 90 per cent increase in range.

    PSA is looking to develop the technology for B- and C-segment cars, with petrol engines between 82 and 110bhp, as part of its drive to develop a car with 2l/100km (117mpg) fuel consumption by 2020. It also wants to use Hybrid Air in small vans. The first production models are planned for 2016, but both Peugeot and Citroen could display cars fitted with the technology at the Geneva motor show

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