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Prototype Volvo Flywheel Tech Uses Car's Wasted Brake Energy 262

cartechboy (2660665) writes "Sometimes we get carried away with sexy moonshot car tech--whereas most everyday gains are about reducing inefficiencies, piece by piece. Volvo's flywheel energy-recovery prototype is a great example of the latter--not to mention similar to one used in Formula 1 racing. The system recaptures energy that would be wasted in braking, like a hybrid does, to reduce fuel consumption by up to 25 percent. When you hit the brakes, kinetic energy that's usually wasted as heat is transferred to a "Kinetic Energy Recovery System" mounted to the undriven axle. It spools up a carbon flywheel that turns at 60,000 rpm to store the energy. When the driver hits the gas, some of the stored energy is transferred back to power the wheels through a specially designed transmission, either boosting total power to the wheels or substituting for engine torque to cut fuel consumption."
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Prototype Volvo Flywheel Tech Uses Car's Wasted Brake Energy

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  • by raymorris ( 2726007 ) on Thursday March 27, 2014 @04:10PM (#46595751) Journal

    It briefly stores energy from braking and uses it to accelerate a moment later. If you don't hit the brakes, it does nothing. If you hit the brakes and stay at a low speed for five minutes, it does nothing.

    When it works is when you stop (which stores energy), then go (which uses the stored energy). In other words "stop and go" traffic is EXACTLY what this is designed for.

  • by Anonymous Coward on Thursday March 27, 2014 @04:19PM (#46595851)

    This was discussed when flywheel KERS was added to formula one. The forces involved are not significant, and on a heavy vehicle (as opposed to an F1 car) would have even less effects.

    Ultimately it is just a stop gap. Electric is so much more flexible than the complex CVT and fundamentally limited flywheel used in this. Which is why F1 all went to battery based systems.

  • by Virtucon ( 127420 ) on Thursday March 27, 2014 @04:20PM (#46595861)

    Williams F1 has been working on this technology for quite awhile now. It's definitely fascinating. This video shows [williamsf1.com] the technology applications.

  • by Todd Palin ( 1402501 ) on Thursday March 27, 2014 @04:26PM (#46595925)
    If you are a careful driver and plan ahead to avoid quick braking, and also accelerate at a very modest rate your benefits would be small with this kind of system. It helps compensate for aggressive driving but it seems like it won't benefit drivers that already are trying to get good gas mileage.
  • by Immerman ( 2627577 ) on Thursday March 27, 2014 @04:38PM (#46596039)

    Not at all - if you hit the brakes at all you're throwing away kinetic energy as heat, no matter how aggressively or gently you do so. This system allows you to capture some of that energy instead and use it to accelerate again later. Unless you are in the habit of coasting to a stop without using the brakes or engine-braking at all this will reduce the associated energy waste.

  • by Bengie ( 1121981 ) on Thursday March 27, 2014 @05:05PM (#46596403)
    Going from memory from many years back, there was a few very interesting points when I was reading about flywheel research for hybrid F1 racers

    1) Something like 90%+ efficient at converting physical energy into rotational and back out
    2) Decided to use carbon fiber because instead of turning into shrapnel, it disintegrates when it smashes into its cage
    3) Added less weight than an extra person
    4) Was able to supply 80hp for 10 seconds at max
    5) Was able to quickly and efficiently capture energy, so you could slam on the breaks and get your 80hp for 10 seconds very easily
    6) Increased fuel efficiency for F1 racers by 10%-20% because of lots of hard breaking followed by hard acceleration.

    I'm sure other safety issues will bring down the effectiveness of these devices for regular car users, but there is a lot of margin to make it an overall win.
  • by necro81 ( 917438 ) on Thursday March 27, 2014 @05:22PM (#46596583) Journal
    The F-1 flywheel systems have a vertically oriented axis, so that the gyro forces are reduced.

    The model demonstrated by Volvo has a horizontal axis, so the gyro forces will be greater and must be dealt with. Thankfully, it's pretty easy to quantify. If you get the flywheel spinning in the correct direction, you can even make the forces work in your favor to reduce roll during a turn.

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