My electric fan is making a strange noise! Causes and solutions (Hypothesis testing and prototyping)

It's nearly 30°C in the Kanto region. My electric fan is working hard too!

The one I use in the living room is already 25 years old (made in 1996), but it's still going strong. However, recently, it started making a strange buzzing sound.

Where is the sound coming from?

Son: "Maybe the motor is coming loose?"

Me: "That's impossible!" I dismissed it immediately.

If the motor were coming loose, it definitely wouldn't be such a gentle sound. The buzzing sound repeats periodically. It's what you call a resonance sound.

Investigating the cause of the sound

Based on how the sound occurs, I suspect that the outer cover is resonating.

The way to check is simple. Just place your hand on the cover...

See? The sound stopped. The fact that the sound disappears just by touching it lightly with my hand is proof that the cover is vibrating due to resonance.

The solution is just one sheet of paper!

Once the cause is known, it's time for a solution. It doesn't make noise if I hold it with my hand, but I can't keep holding it forever. I need someone to hold it for me instead.

Is there anyone I can ask?

No, no, this is a job for an object, not a person.

Since I just need to suppress the resonance, it seems like a good idea to insert some cushioning material. Since durability is also needed, I decided to insert a single sheet of advertising paper.

To keep it from being seen from the outside, I cut it into small pieces and inserted four layers. I did this based on intuition.

I've inserted the paper in the area circled in red, but can you see it? I made it small, so it's almost invisible lol

Looking at it from directly above, it looks like this. The paper is neatly hidden inside.

With this, the buzzing sound has completely disappeared. Yay!

From hypothesis testing to prototyping

To identify the cause, you first start with hypothesis-based thinking and verify it with a simple experiment. This is exactly the process of hypothesis testing. Using a single sheet of paper for the solution is prototyping. You quickly create a form and verify its effectiveness. In this case, we are finished with just the prototype.

Zero cost. This might even be useful for a summer independent research project, so if you are interested, please give it a try!

This article was written by
Mousou Biz Planning Representative Shigeki Kawahara
https://mousoubiz.com/
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