Featured Digital Valvetrain

Discussion in 'Prius, Hybrid, EV and Alt-Fuel News' started by bobzchemist, Nov 7, 2018.

  1. bobzchemist

    bobzchemist Active Member

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  2. bwilson4web

    bwilson4web i3 and Prime

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    First, I like it but I also realize it is unlikely to be coming to any manufacturer soon ... 'not invented here.'

    When I step back to a systems view, my vision is:
    • high-power motor-battery - primary power to drive wheels sized for ~2,000 ft elevation change at 75-80 mph.
    • high-efficiency, low pollution engine - sized for sustained speed at 75-80 mph
    By letting the motor-battery handle peak power, the cars become much more nimble and compatible with automatic driving aids. Disconnected from the wheels, the engines become quieter, significantly more efficient, and easier to control emissions.

    Personally, I like opposed piston engines and/or fix speed, Wankel. With modern fuel injection, problem solved. The opposed piston engine expands the combustion gasses about 2x faster than single piston engines which reduces the high temperature, dwell time that leads to the worst nasties. The Wankel because I love small power plants.

    Bob Wilson
     
  3. bobzchemist

    bobzchemist Active Member

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    All great ideas. I know the Wankel is most efficient at constant speed. Would it make more sense to have it drive a generator instead of couple it directly to the drivetrain? To get even further out of the box, do you think the hybrid drivetrain technology is finally sufficiently advanced to make a turbine engine feasible? (Please, no Batman jokes - even if it really is the source of my long-held desire to drive a turbine car)

    I posted the article because I keep getting annoyed at the "electric will be everywhere" crowd that has no use for hybrids. I think that batteries have a ways to go before they rival the power density of gasoline. Even if the ICE is essentially reduced to a highly efficient back-up generator, I would always feel more secure driving a car that has more than one fuel source. (I couldn't afford a PiP or I would have gotten one).
     
  4. bwilson4web

    bwilson4web i3 and Prime

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    That is how my BMW i3-REx works. The two-cylinder, 640 cc, motorcycle engine only drives the generator.

    If the waste heat of the turbine could be used for another cycle or pre-heat the compressed air before the combustion chamber, OK. The key metric is the exhaust gas temperature. The lower it is, the more efficient the engine.

    Bob Wilson
     
  5. Trollbait

    Trollbait It's a D&D thing

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    The original Audi A1 E-tron program was a series PHEV like the i3 REx that used a 250cc Wankel for the genset. That genset was small enough to sit between the rear wheels. Initially, it ran at one speed, but they switched to three set speeds after user feedback showed some people were disconcerted by hearing a constant speed engine hum that had no relation to road speed. They might have had as many as twenty cars running for testing, but the program got shelved during the Recession. Even if it continued, there was a good chance the Wankel would have been replaced by some small piston engine Audi was already producing.

    As for turbines, Wrightspeed is offering series hybrid conversions for commercial trucks that uses one.
    Technology | Wrightspeed Powertrains
     
  6. austingreen

    austingreen Senior Member

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    Electronic valves are in a chinese partnership car, the Qoros with Freevalve.
    https://www.motortrend.com/news/is-the-era-of-the-camless-valvetrain-finally-upon-us-technologue/

    The problem today for both are costs. With some breakthroughs in engineering electronic valving, at least for intake valves

    Therodynamically wankels have some severe problems and then there are problems with seals. You can build them at low cost, but that comes at the expense of efficiency. A 3 cyclinder 1.2L turbo charged engine with an iron block and aluminum heads is quite small and can be built to be less than 200lbs, not really a big advantage getting much smaller or lighter. Toyota has had trouble getting their most efficient cylinders bellow half a liter, so maybe a 3 cylinder 1.5L which is also quite small. See this 1.5L 88lb engine. Nissan 1.5L, 3-cylinder 400 hp engine to complement electric Le Mans ZEOD RC powerplant - Green Car Congress

    Mazda seems to be furthest on track for efficiency with skyactiv-X again using half liter cylinders for their prototype. 2019 Mazda 3 with Skyactiv-X Compression-Ignition Gas Engine Prototype Drive | Review | Car and Driver
    The beuty of camless is on something like this engine it could stay in the efficient range longer, and use an electronic turbo mostly as a regen to charge the battery from exhaust pressure after acceleration. Camless would also drop the weight and size of the engine like it did on the quoros. Skip cylinder also is easier with camless. Camless will happen when fuel prices get higher and electronic costs go lower. It does need a big battery, but if its a hybrid or phev its got one already ;-)
     
  7. bobzchemist

    bobzchemist Active Member

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    Wow.

    "We have designed our own motor, motor controller, clutchless transmission, and vehicle dynamics software, as well as our own multi-fuel turbine generator, the Wrightspeed Fulcrum™. Our Wrightspeed GTD™ is an exceptionally high-power, compact, and lightweight drive system. Together, the Wrightspeed Fulcrum™ and the Wrightspeed GTD™ reduce fuel consumption, emissions, and noise pollution. And, with fewer moving parts and drastically reduced brake wear, maintenance costs also go down."

    "The GTD™ (Geared Traction Drive) delivers power to the wheels exclusively through a whisper-quiet electric motor – combustion power never drives the wheels.

    Our sophisticated four-speed clutchless gearbox uses software controls in place of heavy and complex traditional transmission components, saving on weight while delivering an exceptional range of power and speed. The gearbox magnifies the already high torque of the electric motors for brisk starts, even on hills when fully loaded, and also allows efficient cruising speed for highway segments. Unlike some EV powertrains, the GTD™ delivers equal or greater power to the wheels as the diesel piston-engine systems it displaces."

    "Our Fulcrum™ works only as an on-board generator, running at peak efficiency to charge the batteries. The job of driving the wheels is left to the electric motors (which are exceptionally good at it). The Fulcrum™ is designed to run on diesel, compressed natural gas (CNG), liquid natural gas (LNG), liquid propane (LPG), or sour gas (landfill gasses). The Fulcrum™ only runs when needed, eliminating idle consumption. Even when running the system is quiet – comparable to a household vacuum cleaner."

    "In most cases fleet managers actually want less rapid acceleration than we could deliver, if asked... We can configure the appropriate speed and acceleration to suit each particular application.

    But that’s only the beginning. Our patented Vehicle Dynamics Control System (VDCS) controls each GTD™ separately, optimizing slip rate for ultimate traction on any surface, all the time. It’s a bit like combining AWD, ABS, and ESC into one synchronized system for braking, stability, acceleration, and handling. Finally, the power to do what you want."

    I wonder how much it would cost to squeeze this system into a Prius? Just having a diesel powered turbine Prius would be cool enough, but it sure sounds like this could potentially deliver exceptional acceleration.
     
  8. a_gray_prius

    a_gray_prius Rare Non-Old-Blowhard Priuschat Member

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    Why would you want to preheat the charge air? That's kind of just asking for pre-detonation.

    Anyone who has ever owned a turbo RX-7 will commiserate when you mention apex seals. A few people with high-power ones have seen the (parts of) seals flying out of the exhaust.
     
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  9. bwilson4web

    bwilson4web i3 and Prime

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    It was reference to a turbine engine. You take the turbine exhaust and run it through an intercooler. The intercooler is between the compressor and combustion chamber so part of the waste heat is captured.

    Bob Wilson
     
  10. bobzchemist

    bobzchemist Active Member

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    Or there's this to capture the waste heat:
    Cyclone Power

    "The Cyclone Engine is a Rankine Cycle heat regenerative external combustion, otherwise known as a “Schoell Cycle” engine. In short, the Cyclone is a 21st century, high efficiency, compact and powerful steam engine."

    A turbine + steam-engine Prius?
     
  11. Trollbait

    Trollbait It's a D&D thing

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    Turbo and super chargers today already have intercoolers. To cool the compressed air down. The act of compression generates heat. Without cooling it, the hot air limits the efficiency of the charger. For designs going for better vehicle efficiency, that is a limit on the downsizing of the engine. The hot compressed air also isn't good for reliability and longevity.

    Warmed intake air for a natural aspirated engine could help efficiency; it is a common ecomod. A factory car would simply use a smaller engine.
     
  12. a_gray_prius

    a_gray_prius Rare Non-Old-Blowhard Priuschat Member

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    "Cyclone power" sounds like something advertised in an infomercial at 2am.
     
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