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Flywheel Canister Vacuum

More efficient than batteries
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In terms of energy storage, a flywheel can weigh about the same as a battery pack and store an equivalent amount of energy (see first link), but the energy-conversion efficiency, between stored energy and dynamic energy is much better for a flywheel (95%) than for a battery (80%?). Since higher efficiency means "less waste", the net effect is that the flywheel stores more *usable* energy than the battery.

So, depending on how much energy you actually want a particular device to have usefully available, before recharging it, the flywheel can weigh a bit less than the battery pack.

See the second link for one design of a canister vacuum cleaner. It could easily hold a horizontally-mounted flywheel. It only needs to be plugged into a wall outlet to recharge the flywheel. You don't have to worry about a limited number of charge/discharge cycles, before replacing a battery pack. And there should be power sufficient to run the vacuum cleaner all over the house, cordlessly.

Vernon, Dec 16 2014

Flywheel powered car proposal https://books.googl...wheel%20car&f=false
The article contains significant information about what sorts of flywheels work best. [Vernon, Dec 16 2014]

Canister vacuum example http://hoover.com/p...on-bagged-canister/
As mentioned in the main text. [Vernon, Dec 16 2014]

[link]






       There's plenty of conflicting data, but there seems to be more information favouring that flywheels have very good power density and relatively poor energy density.   

       But in your vacuum application, the flywheel could be made to pump air by magnetic coupling to an impeller, which would minimise losses and simplify the design.
Ling, Dec 17 2014
  

       You'd want to park it on a "spin up" station, offloading the motor from vacuum entirely, and have the direct coupling to the impeller.   

       The big concern is that really energy dense flywheels require significant armoring around themselves in order to be safe in case of materials failure, and they don't react well to shocks (such as getting bounced down the stairs). Both of these limit their utility in small consumer applications like this.
MechE, Dec 17 2014
  

       Would gyroscopic effects make it hard to manoeuvre?
hippo, Dec 17 2014
  

       I think a vertical axis flywheel would also allow the vacuum cleaner to rotate easily around the vertical axis. An interesting side effect would be that the vacuum cleaner would fall down the stairs while remaining sort of vertical...ie it would precess down.
Ling, Dec 17 2014
  

       old pc hard disks?
not_morrison_rm, Dec 17 2014
  

       [hippo], on a flat horizontal surface a horizontal flywheel offers no extra resistance to being moved about in any horizontal direction. The canister would attempt to remain horizontal when going up/down stairs. It would be best if the canister had some sort of step-support legs that could be deployed in the middle of a stairway, to keep it horizontal.
Vernon, Dec 17 2014
  

       // Would gyroscopic effects make it hard to manoeuvre? //   

       Use a pair of contrarotating flywheels.
8th of 7, Dec 17 2014
  

       //Use a pair of contrarotating flywheels//   

       You actually end up needing three, 1x weight rotating in one direction, 2x weight rotating in the other, and then 1x in the first direction.   

       A pair tends to produce a very sharp rotation around the midpoint between them.
MechE, Dec 17 2014
  

       What [MechE] said in his first anno. To enable high RPMs with a direct connection to the impeller, perhaps a form of Tesla turbine would be appropriate. The spin-up station could operate by being the stator of a switched reluctance motor and the flywheel could be the rotor. I think it is possible to design a switched reluctance motor that has a non-rotating steel shell between the rotor and stator, so that can be a bit of containment. I guess a Kevlar or other composite containment shell could work with a more standard AC induction flywheel. The spin-up station could also function as a spin-down station, so when you're done you can put some of the power pack onto the grid and not hear your vacuum spinning for a long time after you're done.   

       Counter-rotating flywheels are fine, but don't they put a lot of stress on the bearings whenever the system rotates? It seems like it would be best to allow the flywheel to rotate freely on all axis inside the vacuum. Of course that might lend itself better to a system that doesn't have a direct connection between impeller and flywheel.
scad mientist, Dec 17 2014
  

       //If on the same axle which they don't necessarily have to be. //   

       If they aren't on the same axle, you just shift where the torque is located.
MechE, Dec 17 2014
  
      
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