auto balancer 1

[jclough]

I'm trying to design an automatic balancer to balance a fan attached to an electric motor. I've made a disc withh a groove containing a few steel balls which are free to move around to conpensate for the fans unbalance. This assembly seems to do a pretty good job of reducing vibration but there's one problem. Since the motor is mounted horizontally, the balls all drop to the bottom of the disc when the motor stops. This causes a grest deal of vibration at start up until the assembly can re balance itself. I've considered filling the groove with a grease or fluid to help the balls retain their position while the motor is stopped. Any suggestions as to what material to use? The assembly must operate outdoors year round.


Thanks

jon

 

[EnglishMuffin]

jclough : I don't know. I don't even know whether it worked that way. You are quite right about the stiffness of grinders. I mentioned that grinder in earlier posts - I was hoping somebody who knew about that particular grinder would respond and explain how it worked. The balls were on display at the center of the wheel - you could see them through a transparent window in their oil filled cavity.
wmccracken : What you are saying may amount to the same thing as I am saying. It really amounts to a variant of the "spin dryer" balancing principle - in those, the drum is made ultra flexible, with a very low critical speed, and it just ends up rotating about it's center of mass - no extra mechanism is required at all.

 

[Compositepro]

I've always wondered why putting fix-a-flat into a tire didn't throw-off the wheel balance. This explains it. It seems to me that balls in an autobalancer are unnecessary. All you need is a fluid! The balls simply have higher density and allow for a more compact design. But oil will provide balancing and damping.

 

[EnglishMuffin]

Yes - as an earlier poster said, that is the way the suntech balancemasters work - they use mercury. As I said before - the EPA might be interested.

 

[EnglishMuffin]

By the way, here is the web site:

http://www.balancemasters.com/index.html

I'm highly skeptical, but they seem to be making them to fit everything under the sun!

 

[EnglishMuffin]

Also, here is a paper which touches on the theory of liquid balancers, with some interesting references, including one from Machine design.

http://www.mscsoftware.com/support/library/conf/adams/korea/2001/paper/KAUC_21.pdf

 

[rmw]

Google: baladyne
or, go to

http://www.lordmpd.com.

They have been at this for a long time, starting out on grinding machinery that is in constant need of rebalancing due to the grinding away of the rotating mass.
or, just go out to your local truckstop and get a trucking magazine, because the rings filled with oil and balls, some as small as steel shot, are used on truck and bus wheel assemblies for dynamic balance. Difference is, the truck wheel rotating assembly obviously does not accelerate to speed as fast as your fan does.
Lord bought Baladyne, who had a halon automatic fan balancer that worked great. Good luck.

RMW

 

[jclough]

Thanks RMW- excellent link! There's an excellent link in the fan balancer section.
Someone approached me about making one for boat props. I'm looking into whether or not it will work though. Not sure about where the first critical would be. I think this will be one of those situations where it will be easier to try it than figure it out.

Happy Thanksgiving to all


Jon

 

[EnglishMuffin]

But the system referred to in that link is a completely different technology - it requires vibration sensors and complex electronics, which is then used to actively control the balancing device (either electronically controlled weights or a vaporisable liquid). It rests on a much firmer theoretical footing, and does not rely on operation above the critical speed. The balancemaster stuff on the other hand is highly questionable - it is not clear whether the inventor understands it himself, or is running some sort of scam, since I noticed that on one occasion he referred to "ultrasonics". I also don't think it is accurate to classify it as an "active" system, although that may be arguable. The only way this stuff can work is if the propeller shafts, Harley Davidson motorcycle components, ultralight engines etc are all operating above their critical speeds - which I find hard to believe. But perhaps I am missing something.

 

[lesgutzy]

I have tried your approach years ago with no success. I suggest you look at the excellent auto-balancing device already available on the market by Baladyne Corporation (now purchased by "Lord&quot. A good contact there is Tom Schulte.

 

[EnglishMuffin]

lesgutzy: Sounds as though you concur with my view, if I read you correctly. So what's your opinion of Balancemasters? Is it a massive intentional con, or is it a case of the inventor having erroneously convinced himself that his device really works, while laughing all the way to the bank in the process? Or does it really work for some unexplained reason?
I have had quite a bit of contact with Baladyne some years ago (before the Lord purchase) - I was involved in a machine tool spindle balance application, and yes, their active device with balance weights definitely works. However, at that time, very expensive and somewhat limited in the amount of imbalance it could handle.

 

[sloop]

I am not familiar with auto balancing.
I wonder if there is a way to use a set of magnets attached to the blade to stabilze the ball locations.