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Nil RPM Idle, another way

Engine stops completely during short stops, e.g. traffic lights
  [vote for,

This idea is probably past it's time as it relies on a spring in the flywheel!

Engine management system senses that car is almost stopped and brake is lightly applied. Automatic system kills engine and applies a brake to the flywheel, the flywheen includes a spring that is wound by the action of retarding the motion of the car. Once completely stopped brake is applied to both the flywheel and the transmission.

When driver releases brake pedal pressure the brake on the flywheel releases first which allows the spring to spin the engine through one or two compression strokes, the engine starts and the transmission brake is released. Car moves away as per normal.

KiwiJohn, Dec 01 2003

a brief description of the flywheel... with links and references and all kinds of good stuff showing that people have already tried to use flywheels to do all of the things you have suggested and much, much more. http://en.wikipedia.org/wiki/Flywheel
Let Jim Watt rest in peace. [ato_de, Oct 04 2004, last modified Oct 21 2004]

The car in front is.... http://prius.toyota...logy/lowspeeds.html
No flywheel, but fully baked [converted, Oct 04 2004, last modified Oct 21 2004]

Touch-N-Mow http://www.amazon.c...175-3916476-8625721
Yard-Man Touch-N-Mow Mower on Amazon [cajunfj40, Jan 24 2012]

Owners' Manual http://manuals.mtdp...ial_num=&doSearch=Y
Owner's Manual for the Touch-N-Mow mower above. [cajunfj40, Jan 24 2012]

Exploded Engine Diagram http://www.ereplace...stratton/12V800.pdf
Exploded parts view of engine with Touch-N-Mow system (part number 1236 is the mechanical starter) [cajunfj40, Jan 24 2012]


       I remember old gas powered golf cars functioned simmilar to what you describe: I stop the cart, and the engine dies - I whack at the ball, get back in and mash the accelerator and the engine cranks up and I drive 22 feet to repeat the cycle.   

       I do like the idea of using a spring to stop/start the engine, but...   

       Once you release the flywheel brake, wouldn't the flywheel spin backwards?
1st2know, Dec 01 2003


       I don't know how those golf carts work, maybe they are like an old Buick (1925?) we had? The generator and starter motor were in one unit which was always in mesh with the flywheel. Turning on the ignition powered the starter motor which cranked the engine until it started then the engine drove the starter motor as a generator.   

       I think I have the spring the right way around, braking the flywheel while the car is still rolling winds the spring. It does this by stopping the engine from rotating in it's normal forward direction of rotation, so the spring is wound up and the brake is holding it, when the flywheel brake is released the engine then starts turning again in the same direction.
KiwiJohn, Dec 02 2003

       The only way I can see this working is if the spring is attached between the flywheel and the propshaft. The brake pressure would have to be carefully regulated to prevent overwinding of the spring under coasting.   

       How would the car deal with a situation where you're almost stopped, then the car in front stops before you expected, so you have to do an emergency stop and the spring isn't wound up enough to start the engine? Can the system be over-ridden so the starter can be used?
egbert, Dec 02 2003

       factoid: an engine produces the most amount of exhaust fumes and is subject to the greatest amount of wear per revolution when cold-started. Not that this is like that.
RayfordSteele, Dec 02 2003

       you don't need a flywheel to crank a spring when the brakes are depressed. Why have a flywheel to perform this function when you can wind the spring by simply engaging it when the brakes are applied and releasing it when the brakes are released....   

       no flywheel necessary.
ato_de, Dec 02 2003

       It is the engine that needs the flywheel.
KiwiJohn, Dec 02 2003

       [Rayford], that statement is true if you start with some very low RPM (like current electric starters do it) and let the engine work up to normal idle speed by itself. If something (flywheel?) brings the engine up to normal idle RMP before fuel is injected everything works fine.   

       [Kiwi] I agree that flywheels are a little outdated for this purpose. Get a hybrid car where the electric motor alone can give you the initial kick.
kbecker, Dec 02 2003

       Many years ago there were backup power generators that were started by an electrically powered flywheel being engaged with the crankshaft. There was a solenoid holding the massive spinning wheel off the engine which let the two connect when power failed. Maybe this could be adapted to your system.
Captain_Ignorant, Dec 02 2003

       It would have to be one hell of a spring to overcome engine compression on anything larger than a small 4 cyl.
I suppose you could use some kind of spark retard or compression release (like old Indian and Harley Davidsons).
soundman, Dec 03 2003

       [KJ] you either need a spring _or_ a flywheel, not both.
ato_de, Dec 03 2003

       /It would have to be one hell of a spring /   

       Maybe connect the arrangement to a series of levers that compress the coil springs in the suspension. On releasing the flywheel brake, the springs unwind, giving the engine the kick it requires. The car almost literally springs to life! Add fake opening eyelids with big lashes to the headlights for comic effect.
egbert, Dec 03 2003

       [KJ] you either need a spring _or_ a flywheel, not both.   

       Hmmm, don't think so, the flywheel is part of the engine, it is already there, it allows the engine to run smoothly at low revs, every piston engine since your friend James Watt had one (except aero engines where the propellor does the same job).   

       There is no additional flywheel in my idea. Your link to flywheels no doubt points to a wealth of interesting information but flywheels do not play any part in this suggestion except as the existing point in the cars power system where the spring would be located.   

       When the engine is stopped so is the flywheel, the function of the spring is to store some of the energy recovered by retarding the forward motion of the slowing vehicle and to later release that energy to push the flywheel around a turn or two so re-starting the engine.
KiwiJohn, Dec 04 2003

       Partly baked, in lawnmowers at least - to my knowledge not in anything much bigger than an 18.5hp riding mower engine. You may be able to patent an auto application for a no-extra-battery nearly all-mechanical idle-stop system.   

       YardMan Touch-N-Mow system, actually part of the Briggs and Stratton Quantum engine line. This mower has a regular rope pull "recoil" starter, and in addition has a mechanical spring starter geared to the flywheel that gets "energized" (wound) when the engine is shut down. For restarting, you do all the normal things you do to start the mower (this one also has a "safety key" that has to be turned to the "run" position to start and run it) but instead of pulling on the rope, you hit a starter button and grab the dead-man bar. The mechanical starter "de-energizes" (unwinds), rotating the engine up to speed, starting it.   

       Link 1 is to an Amazon.com listing for a mower with the system, link 2 is to a search for the owners' manual for that mower, and link 3 is an exploded diagram of the engine showing the touch-n-mow mechanical starter (numbered 1236 in the diagram).
cajunfj40, Jan 24 2012

       Would need to size the flywheel properly. Too small and it wouldn't work. Too large and the car would flip over when you pressed start. Volunteers needed to press button...
saedi, Jan 26 2012


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