• Welcome to engineeringclicks.com
  • Wind powered washing machine

    Discussion in 'The main mechanical design forum' started by Outofmydepth, Oct 17, 2010.

    1. Lloyd

      Lloyd Member

      Joined:
      Oct 2010
      Posts:
      11
      Likes Received:
      0
      for the chain, considering its length, I would consider running the rising side on one tube and the falling side in another. In one tube I'd be concerned that over the length the whip of each chain half would become entagles and cause some damage. For the lubrication system, you could consider using a cotton or wool cord (wick) with one end submerged into a bottle of old engine oil and the other end dangled out of the top and in line with the chain/sprocket (best make something to hold the wick in place). This will create a drip feed. as the smal amount of surpluss drips off the chain you can just mop it up with sawdust/sand/old rags. you could even leave enough material to soak up enough oil that you only need attent to it once in a while.

      For stopping the drive, some form of clutch would be in order. perhaps you could use the derailleur set up off a bike. have one sproket fixed to your motor shaft, and the other connected to a free wheeling shatf. when you change gear, the drum disconects and simply free wheels the spare sprocket.
       
    2.  
    3. spiceage

      spiceage Member

      Joined:
      Apr 2010
      Posts:
      19
      Likes Received:
      0
      I am not sure if my last reply was posted so forgive me if this is boring. Outofmydepth has a good point about oil on the belt - maybe using grease would be satisfactory or, if sticking with oil, how about a labyrinth seal shaped from plastic milk bottles?

      Your slewing turntable will enable you literally to turn off the power! Then a spoke-in-wheel or a chain clamp will immobilise the machine. I suggest also something similar for the turntable to save wear and tear on all the moving parts.

      All the best
      Spiceage
       
    4. Outofmydepth

      Outofmydepth Active Member

      Joined:
      Oct 2010
      Posts:
      31
      Likes Received:
      0
      Thanks for replies and for taking my project seriously & not dismissing me as a nutter!

      I have been considering using 2 tubes instead of one mainly as I only have 2 inch tubes to hand. I figured to run both chains in one tube I would have needed a minimum size tube of 4 inches.

      Ref the complications of getting the polyvee belt contaminated with oil. Could the solution be to do away with the motor & polyvee belt and connect the bottom sprocket directly to the back of the drum?. I could then use oil as liberally as I wish providing I have an efficient method of catching any spills.

      Outofmydepth
       
    5. spiceage

      spiceage Member

      Joined:
      Apr 2010
      Posts:
      19
      Likes Received:
      0
      This is great fun, I hope you are enjoying it too. Two tubes are fine as far as supporting the weight and carrying the chains but 2" tubes depending on the height I feel are going to be too flimsy (without help) to manage the overturning moment due to the wind force. You might therefore need a bit of rigging to strengthen the tubes. Assuming that the poles rise up from the middle of the back of the machine, the rigging should be attached to the strong front two corners of the machine so that they are held in tension by the wind. You should also provide another stay for the reverse direction (extend the top of the machine rearwards to provide the attachment) because the machine is free to be turned the wrong way into wind.

      On the direct drum drive, it all depends on the relative diameters of the washer drum pulley/sprocket and your windmill rotor sprocket and the intended rotational speed of the windmill. Think in terms of the tip speed being about 6 times the wind speed to fix the relationship between rotor diameter and its rotational speed. We need to start playing with some figures.
       
    6. Outofmydepth

      Outofmydepth Active Member

      Joined:
      Oct 2010
      Posts:
      31
      Likes Received:
      0
      Hi again,

      I have not disappeared, I have just been in my shed!

      The 2 inch tubes I referred to are in fact old scaffolding poles so not as flimsy as you might have imagined. They may also be a little more than 2 inch!. However I have been planning to provide additional support. I have an old steel gate which I am planning to cut in half and erect on top of the washing machine as an "A" frame. This will support the steel pipes as well as the windmill shaft.

      As previously intimated engineering is not my area of expertees and accordingly I do not have materials or equipment to hand that most of you take for granted. However I had a productive day yesterday and worked out the practicalities of connecting one of my bike sprockets directly to the back of the drum and assembling the shaft to hold the propeller and the top sprocket. This shaft will run in 2 bearings.

      With regard to calculations/wind speed/rotational speed.

      The speed of rotation will depend on 4 things.

      1. Propeller design.
      2. Load.
      3. Gearing. (which effects load)
      4. Wind. (which even I am unable to control)

      I have made a first attempt/prototype propeller which measures a touch under 4 feet diameter.

      I think for these calculations it is safe to assume a circumference of 4 yards.

      Taking a factor of 6x at the tips as suggested by spiceage and a windspeed of 10 mph gives a speed at the tips of 60 mph.

      If it does 60 M in 1 hour it will do 1 mile (1760yards) in 1 minute.

      1760 divided by 4 = windmill shaft rotational speed of 440 RPM.

      We can now see if we multiply the windspeed by 44 we get the rotational speed of the windmill shaft.

      So a 50mph wind (not uncommon where I live) would give a shaft speed of 2,200 RPM.

      Becoming difficult to type typing is jumping about.

      To be continued.

      OUTOFMYDEPTH
       
    7. Outofmydepth

      Outofmydepth Active Member

      Joined:
      Oct 2010
      Posts:
      31
      Likes Received:
      0
      Hi again,

      Where was I?.

      If I used sprockets of equal size we would have a drum speed of 2,200?

      If I used a large top sprocket/small bottom sprocket the drum speed would be 4,400!

      If I used a small top sprocket/large bottom sprocket the drum speed would still be 1,100.

      This is assuming a tip speed of 6x.

      If the propeller was not so efficient (4x) or if there was a heavy load the calculations would be a lot different.

      If I was clever enough I would design a wind powered brake. The stronger the wind the more braking effect. Alternatively an automatic variable pitch propeller. Unfortunately these designs are beyond my comprehension.

      As I do not have a wind tunnel in my shed I am guessing this will have to be a suck it & see venture. I will wear the suit I use to fight grizzly bear when I test this machine!

      Outofmydepth
       
    8. spiceage

      spiceage Member

      Joined:
      Apr 2010
      Posts:
      19
      Likes Received:
      0
      Hi, my QuickReply just evaporated (second time this has happened so there is something a bit flakey with the forum’s software). I will try to recall as follows.

      I think we are heading for a 10:1 reduction between the prop shaft and the drum. This will give about 44 rpm on the drum (I imagine our washing machine’s wash cycle to run at about this speed) and will give buckets of torque to keep the speed nice and even. If you are worried about reverting to the polyvee sprocket-on-motor drive, why not soak up one or two of your spare bikes by having intermediate chain drives down the scaffold poles. A two stage arrangement of 3:1 each gets you almost there.

      Shall we go for a 15 mph design wind speed? Assuming this and reflecting that a 4:1 tip-to-wind speed would be more suitable for less streamlined propellers, your 60 mph design tip speed remains so it’s kids out of the way and hard hats on. Now for the blade angles: relative to the air velocity impinging on the blade, a reasonable blade angle would be between 10 and 12 degrees for a simple flat blade – any higher will stall the “wingâ€. At the design conditions at the tip, the relative circumferential and wind velocities create an angle of arc tan(15/60) or 14 degrees so your blade angle relative to the imaginary disk traced by the propeller should be about -2 degrees. At halfway along the propeller, the relative circumferential and wind velocities create an angle of arc tan(15/30) or 26.5 degrees so your blade angle relative to the imaginary disk traced by the propeller should be about -14 degrees. Now this is where it gets interesting because if the wind gusts to say 30mph, the blade will stall with a big loss of lift-to-drag ratio due to the separated streamlines. It may even slow down! But before we get too excited about self-governing, remember that this only applies when the propeller is doing 440 rpm. If it went faster for any reason, it could take advantage of the gust which in turn would make it go faster still so it is not fully self governing. Similarly, it might be difficult to start the propeller from scratch. You may need to crank the system (lucky you have some spare pedals) to get it going up to speed.

      There are two important things in your favour to re-stabilise the system. One is the drag from the washing machine (more speed = more drag) up to the point where the water and balls centrifuge to the drum; it is vital to avoid this. The second is the aerodynamic drag of the propeller whose drag goes up with the square of the speed (except of course where the blade is stalled and the higher speed pulls it back into efficient lift).

      Your emergency STOP is your turntable – you can simply head off the wind and you may find that you can regulate the speed quite well with this too.
       
    9. Outofmydepth

      Outofmydepth Active Member

      Joined:
      Oct 2010
      Posts:
      31
      Likes Received:
      0
      Hello spiceage,

      I have also have had my reply vaporised. Most frustrating. It has happened before and I have put it down to having a dodgy internet connection.

      Thanks again.

      I have to admit I did not understand some of your last post but the parts I do understand make eminent sence.

      I agree I must work on providing a larger reduction between the propeller shaft rotation & the drum. 10:1 sounds good and I guess it would not matter if I managed closer to 20:1. I must therefore re visit the polyvee belt arrangement and see what can be done about keeping the oil away. The bike cogs I have to hand generally range from 17 teeth to 34 teeth, hence the 50% reduction mentioned in my last post. First thing this morning I will measure the existing polyvee drives to assess the reduction I have available. I guess it will be in the region of 20:1.

      The propeller.

      I found a design on the net using a 3 foot length of 6 inch drainage pipe. Basically just cut it lengthways. 2 cuts straight and 2 at a pre designed angle and you end up with 4 blades. Bolted to a central hub (old circular saw blade) we have a propeller. Using this principle I realised I could use other pipes or cylindrical objects. I therefore made a prototype out of an old dustbin which although works very well seems to be a little too flexible. I do have some very strong 25 gallon plastic barrels and intend to make some blades from these in due course. Once I have a circular saw mounted on a shaft it is easy to produce a range of blades from materials that come my way & will eventually decide on the most suitable design.

      In particular I understand your point regarding torque, the drum would run more smoothly and reliably using a higher reduction.

      Outofmydepth
       
    10. Outofmydepth

      Outofmydepth Active Member

      Joined:
      Oct 2010
      Posts:
      31
      Likes Received:
      0
      Reduction on the polyvee belt is 12.5 : 1

      Might have thought of a way of keeping the oil away from the polyvee belt.

      Extend the shaft of the original motor through the back of the machine and run the bike chain in oil externally. The polyvee belt will be reasonably enclosed within the machine so should avoid the oil.

      Outofmydepth
       
    11. spiceage

      spiceage Member

      Joined:
      Apr 2010
      Posts:
      19
      Likes Received:
      0
      The Polyvee ratio sounds good. You might have quite a bit of detailed work ahead of you to extend the shaft (alignment and rigidity requirements) but it’s a sound idea. Because I am lazy, I would have been inclined to keep the motor and its pulley arrangement intact as far as possible because this already possesses a stiff attachment to the drum casing and appropriate well-aligned bearings. Whatever arrangement you decide upon, try to avoid putting the sprocket too far away from a supporting bearing – long shaft overhangs may over-stress the bearings.
       

    Share This Page

    1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies.
      Dismiss Notice