# Design of a window opener mechanism -- problems

#### Frederik

I have been struggling with this problem for a long time now, and are hoping you can help me. The assignment was to design a mechanism for opening a window with less effort. My way of solving this is to store energy in a spiral torsional spring as the window closes, which would be released when opening the window. I have tried to explain the resulting challenge in the picture below.

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#### berkeman

Mentor
Welcome to the PF.

Normally, schoolwork problems go in the Homework Help forums, but for projects like this where you show lots of work, we can sometimes allow them in the technical forums. I'll leave the thread here in ME for now.

I'm not seeing where the wire and spring mechanism are in relation to the window in your diagram in the upper left. Do you have more of a perspective drawing of the setup available? Or a drawing like in the upper left that shows where the wire is?

#### Frederik

I hope these sketches illustrate the concept better:

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#### Frederik

The axle which the window rotates about will actually be geared 1:2, meaning the pulley with varying radius will turn 90 degrees, from a fully open to fylly closed position of the window (window opens 45 degrees).

#### BvU

Homework Helper
Note that in your very first formula in post #1 a factor $1\over 2$ is missing.

Question: why such a complicated design if you could simply let the window hinges be halfway the window (ie where mg acts) instead of at the top ?

Or counterbalance above the hinges in your design with something as heavy as the window but smaller

#### Frederik

Note that in your very first formula in post #1 a factor $1\over 2$ is missing.

Question: why such a complicated design if you could simply let the window hinges be halfway the window (ie where mg acts) instead of at the top ?

Or counterbalance above the hinges in your design with something as heavy as the window but smaller
Such a window has already been produced by the company. Our lecturers want us to come up with a completely new design, not currently used by the company, therefore leaving out the simpler or more obvious mechanisms.

#### Dr.D

Why not rotate the window about a vertical axis, with the result that there is no change in potential energy required?

#### Frederik

Why not rotate the window about a vertical axis, with the result that there is no change in potential energy required?
That's not an option unfortunately, i should have mentioned that it's a window ment for a roof angled 45 degrees.

#### berkeman

Mentor
That's not an option unfortunately, i should have mentioned that it's a window ment for a roof angled 45 degrees.
Seems like it would work fine. Put the axle down the middle of the window matching the slope of the roof. Turn the window 90 degrees (half in and half out of the roof) to open it. The main challenge will be to design a good weather seal that can work with such a window opening scheme & motion...

#### BvU

Homework Helper

"Design of a window opener mechanism -- problems"

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