Storage mechanism with locking and unlocking

[magicfrog]

Hi everyone, I tried searching the forum but couldn’t find anything directly related.

I’d like your opinion on the existence or feasibility of a mechanism concept I’d like to explore. I’m attaching a rough 2D sketch and I’ll try to be as clear as possible.

Imagine a rod that must perform a linear stroke of about 40 mm (just an example). A compression spring is installed between a mechanical stop and one end of the rod. During the rod’s stroke, the spring is compressed and stores energy. The goal is to stop the compression at a specific position (for example at 20 mm), but then allow the rod to continue its remaining stroke while decoupled from the spring—so the rod can keep moving freely.

In my mind, this would be a nested mechanism (made of sub-mechanisms): initially, all components move together and the spring is compressed. Before reaching the target stroke “x”, a first mechanism deploys “hooks” (or a locking feature) to create a mechanical stop that keeps the spring compressed. Once stroke “x” is reached, a second mechanism disengages the rod from the spring, allowing the rod to continue its travel without feeling the spring force.

My question is: does a system with this behavior already exist? Can anyone point me to similar solutions or share insights? In other words, I’m looking for a mechanism that can store energy, hold it mechanically, and release it only under specific conditions.

The sketch is very rough since I don’t yet have a clear architecture, dimensions, or supporting data. Thanks in advance.

 

[magicfrog]

More specifically, the idea is to have a linear mechanical system that, during the forward stroke, activates mechanisms needed to:

1. store energy (compress the spring),
2. retain it (mechanically lock the spring plate),
3. disengage the rod so it can continue the stroke freely.

During the return stroke, the sequence would be reversed:

1. free travel up to a certain point,
2. re-engagement between rod and spring plate,
3. release of the mechanical lock,
4. spring energy discharge (with some form of controlled release/dissipation as needed).

I realize this is likely a complex mechanism, and I don’t yet have concrete ideas for an efficient way to implement these “nested” functions, but it’s definitely an interesting concept.

 

[Filip Larsen]

I am not a mechanical engineer, but I would imagine that for a purely mechanical device you will need some kind of latching function.

Perhaps you can be inspired from the soft close mechanism used for drawers. Or perhaps the similar but opposite function of push to open. I am not aware if these two both utilize the same mechanism or if it is two different approaches, but both sort of do what I understand you seek.