Seeking ideas for how to achieve an adjustably damped shaft connector

[some bloke]

TL;DR

I want to make a shaft damper (such as that which connects a motorcycle rear sprocket carrier to the rear wheel) which can be adjusted in stiffness. I am sure that there will be such a design in the world, but I don't know where to start looking, or the right terms!

Hello everyone!

I am brainstorming a project which will require an adjustably damped shaft connector, which is a term I'm making up and I think it's about right.

The shaft will be driven at one end, with an intermittent drive. There will be a shaft dampener after this, which will cushion changes in shaft speed, either by springs or rubber mounts. The other end of the shaft will be fitted to a load which is subject to change during use.

I would like to find a way to change the stiffness of the dampening in the shaft dampener, whilst the mechanism is running, so that it goes anywhere from a hard start/stop to a very soft, cushioned one. I don't have exact requirements for the cushioning, as I will need to approach this by trial and error.

For the dampener, I have considered an air bladder for the cushion, but this would necessitate an air compressor, which I would prefer to avoid if possible. I am contemplating some form of magnetic braking, or a pair of leaf spring arcs which are squeezed together at one end, and the position of the closed part is adjusted by rotating a servo.

I anticipate that a real-time adjustable shaft dampener is likely to be something which exists already, but my google-fu is coming up weak I'm afraid! Does anyone know of any such mechanism?

 

[berkeman]

Have you considered using a hydraulic system between the input shaft and the output?

 

[Baluncore]

What range of RPM, torque and power are you considering?

Is there a known relationship between shaft angle and energy transfer?
What is the maximum angle, or number of turns of the shaft, that must be accumulated, before the rotational energy is recovered, or is this an energy dissipative system?

The ends of the system must be considered as part of the transmission.
From what source does the intermittent drive energy come?
Where does that energy go to be useful?

Is this a one-off experiment, or will you mass produce the problem?

 

[berkeman]

Is this a one-off experiment, or will you mass produce the problem solution?

Fixed that for you.

 

[Tom.G]

See if these approaches work for you.
https://www.google.com/search?hl=en&q=torque+limiter+coupling
https://www.google.com/search?hl=en&biw=&bih=&q=magnetic+clutch

There are a different technologies available. The three most likely ones for your project are:
1) Torque Limiter Coupling
2) Friction-disk-and pressure-plate as used in cars with manual transmissions.
3) One based on a viscous fluid media (Iron particles in an oil bath) which gets more viscous when a magnetic field is applied.

If frequent operation is involved, note that slippage in both of these is converted to heat, which will need to be dissipated somehow.

Cheers,
Tom

 

[tech99]

TL;DR Summary:
The shaft will be driven at one end, with an intermittent drive. There will be a shaft dampener after this, which will cushion changes in shaft speed, either by springs or rubber mounts. The other end of the shaft will be fitted to a load which is subject to change during use.

When you say damping, you might mean either springiness or friction. If the damper is springy, you might find the system oscillates whenever power or load are altered. If entirely friction, sudden load changes will be transmitted to the prime mover. So I imagine a combination of the two will be required to ensure that oscillations are damped out.

 

[Dullard]

The front forks of performance motorcycles use a system of springs, fluid, check valves, and adjustable orifices (orifi?) to provide a linear version of the device that you describe. I can imagine an externally-adjustable rotary version of such a device, but the practicality depends on the specifics of the required damping.