Sinusoidal Pressure Controller

I once used a proportional hydraulic valve, and to reduce "sticktion" introduced a 60HZ ac signal onto the DC control signal. It was simply a small isolating transformer that gave out sufficient volts to dither the valve. I used a simple potentiometer to adjust the magnitude. Application was an automatic gauge control for a rolling mill for coin stock. Stock was used to create blanks for the mint. (You NEVER put your hands in your pockets unless you wanted an immediate strip search!)

Not exactly what I'm looking for, but thanks for the reply. I'm starting to get the feeling that what I'm looking for isn't really out there. A pressure generator that generates sinusoidal pressure 0-50Hz and up to, say, 500 PSI is more specifically what I'm looking for (I had to clear some things up). Since I'm just an intern and am supposed to magically come up with this device, I can't really get too creative.

Feels a lot like a wild goose chase.

There are quite a few I/P and V/P commercial hydraulic transducers in the market place, Such as Rexroth.

Your challenge will be to verify the specifications for bandwidth and then generate the appropriate reference signal.

Hi,

This sounds like a pretty specialised application. My first thought was use a Proportional Valve where you feed in a sine wave electrical signal and get a sinusoidal pressure output. I asked around at the (valve) company where I work and it seems that our Proportional Valve will not respond quickly enough to regulate at this frequency; 10ms is not much time for a relatively heavy, 400bar, valve to react. I don't know what quantities you have in mind, but developing a new lightweight model would be expensive.

Does this have to be one device? Could you use a 100 psi regulator feeding a quick-acting stop valve which could be operated by several different means to give a varying output?

Does your output have to go from 0 to 100psi and back? or do you want to go from say 50 to 150psi which would be a more difficult scenario?

Please bear in mind that sudden opening and closing of valves in a high pressure system can lead to 'Dieseling' if the air is contaminated with oil.

I hope that this is of some help.

Drew

It's starting to look like we're abandoning the sinusoidal pressure (seems like they gave me a MacGuffin) and going with a great looking pressure generator from PMI that can achieve what we want through some different means.

No worries.

Just out of curiosity, what is a MacGuffin? It's not something I have come across in the UK

Drew

A MacGuffin.. It's a goal that leads you through a lot of machinations not generally for the purpose of the goal, but for the purpose of the machinations.

The wikipedia article on it has a pretty good general idea.

Thanks for that.

It sounds like a harsh way to treat someone!

Drew

The point is to learn, so it's not really that bad. Though I still do need to find a sinusoidal pressure generator. Looking into it the actual pressure range of the generator isn't as important. But it does need to go up to about 20Hz.

Ray and I are both looking for the same thing. Let's say we need a 20 psi offset, and a 10 psi dither about the offset. We need to test the dither frequency from .01 hz to say 20 hz, in small increments. BTW, Ray was not on a wild goose chase, no matter what he may have you believe. We are testing the frequency response of a device and this is method will provide us the info we need, if we can acquire or build it. Some of the ranges are slightly flexible. Any thoughts or assistance will be appreciated. AJ