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  • Concept for fuel saving device...

    ... but it is probably 50 years out of date!

    Consider all the cars the are right this moment sitting at traffic lights all around the world while the engine idles or even sitting there stirring the auto transmission fluid for no useful purpose.

    The concept is simple, when the vehicle is slowing under braking just before the vehicle comes to a stop some of the braking reaction is used to wind a spring. When the vehicle stops the engine is killed. When the driver releases the brake the spring unwinds by turning the engine which being already up to operating temperature will start without additional noise or fuss.

    The device would be between the transmission and the engine and might even be practical to make it as an after market add-on.

  • #2
    In general, hybrid electric vehicles do try to recover some of the kinetic energy of the vehicle motion during braking ( regenerative braking) . There have also been proposals to store that energy, normally disapated as heat by the brakes, in large flywheels. I believe there have been some buses that actually used the flywheel energy storage method. I can't say that I've seen a system using springs, but I suppose some arrangement of that kind might be made. The flywheel idea was criticized by some because of the danger of storing a lot of energy in a rotating mass, and the spring method might also represent some danger. Turning off the engine during idle has indeed become a method of saving fuel.

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    • #3
      I believe there may be a law in place that says you cannot stop your engine at an intersection. Has to do with getting out of the way in an emergency. Kind of like mexican overdrive being illegal.

      Anyways at an idle the transmission is not using much. More power is being sucked up running the cars electronics, AC, power steering, and the like.

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      • #4
        There is the Dana Permodrive system intended for mid range and heavy duty fleet trucks(garbage and route trucks).



        It basically does what your talking about,but uses hydraulic fluid in an accumulator as the spring.
        I just need one more tool,just one!

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        • #5
          When I graduated from graduate school, I interviewed at Ford Research Labs. They had a working copy of you concept at the time (1979). It used a rubber linkage to hold the energy.

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          • #6
            In many Asian cities, it's the law to turn the engine off while waiting for the light to turn green. It's a good idea and one that the rest of the world should adopt.

            As for storing the energy during deceleration, unless you're constantly driving and stopping, I think the energy that you recover is relatively small. It would be better to put some kind of acceleration limiter in the car, which would be a significantly greater savings.

            You don't need some esoteric solution to save the world. Drive a smaller and more fuel efficient IC engine cars.

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            • #7
              Originally posted by macona
              Anyways at an idle the transmission is not using much. More power is being sucked up running the cars electronics, AC, power steering, and the like.
              When I had a GM V8 Holden (c1969) the noise from the fan was very loud so I took the blades off but the motor then ran hot when idling. I fitted a much better ignition system and reduced the idle. The vehicle would then idle in 'Drive' and not move even when no brakes on and neither did it get over hot.

              In that vehicle, at least, while the brakes were holding the vehicle the engine worked against the stalled torque converter and the heat in the trans fluid was passed to the radiator which tended to overheat the engine. 40 years later things might be different but somehow I doubt it.

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              • #8
                WS,BG, I am not suprised it has been tried before as like it said I am probably 50 or more years too late. On consulting my bookshelve I will revise that to be 100 years too late!

                Among the self starting systems tried in the early days were compressed air and of course electric but also a spring system.

                The way it is described the driver killed the engine before the vehicle had stopped and applied a brake to the engine so that the inertia of the vehicle wound a spring in the drive line. The driver then set both brakes leaving the car in gear. Next morning the driver released the engine brake and the engine was started by the spring. The book just said it was a system fitted to 'some luxury cars'.

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                • #9
                  Artful,IIRC the Permodrive was originally an Aussie design.Last I heard it was being develpoed for use in US military vehicles.It was first tested in Garbage trucks were it produced a 25-30% fuel savings.

                  The engine doesn't shut off,the unit acts as a braking system and pumps up the accumulator as the truck comes to a stop.When it's time to go it acts as a pump and uses the stored pressure to accelerate from a stop.Works great on stop and start driving.

                  I suppose a system of torsion springs,clutches and sprag clutches could be made.First application would something like Evan's trik-bike.
                  I just need one more tool,just one!

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                  • #10
                    http://reviews.cnet.com/8301-13746_7-10081298-48.html

                    I haven't researched exactly what it does but I have seen talk about regenerative braking and using the starter motor to accelerate the car again after stopping.

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                    • #11
                      I wonder how hard it is on the engine to do this start stop thing. Engine wear is at its highest at start because of no oil pressure. Plus wear on starters and ring gears. Starters just are not designed for that kind of duty cycle. Also cant see a system like that working on manual transmissions either.

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                      • #12
                        Best fuel saving transportation device known to man is the bicycle. It gets (quite literally) 60 miles per hamburger.

                        I recall seening a graphic in Scienfific American showing a man on a bicycle is roughly equivalent to a soaring bird in specific energy consumption per mile.

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                        • #13
                          Our local bus company trialled a system some years ago that cut out 3 injectors on a 6 cylinder engine, when parked at a bus stop to save fuel.

                          Don't know what the results were but it wasn't adapted.

                          .
                          .

                          Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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                          • #14
                            Honda IMA

                            http://en.wikipedia.org/wiki/Integrated_Motor_Assist
                            Paul Compton
                            www.morini-mania.co.uk
                            http://www.youtube.com/user/EVguru

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                            • #15
                              This is standard on BMW 4-cylinders in Europe.
                              Basically, it tries to only charge the battery when braking, thus recovering electrical energy.
                              When stopping at a red light, putting the transmission in neutral, the motor stops.
                              As soon as you engage a gear again, the motor starts automatically.
                              Other European car manufacturers are introducing the same system.
                              http://en.wikipedia.org/wiki/Start-stop_system

                              Benta.

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