×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

how to simulate a proportional valve?

how to simulate a proportional valve?

how to simulate a proportional valve?

(OP)
does anyone know how to simulate a proportional valve feedback, i wish the information for i can probe a board that drive ones of this valves.

thanks for your help

RE: how to simulate a proportional valve?

morens; not much information to work with... What kind of signals?????? What kind of valve????

RE: how to simulate a proportional valve?

(OP)
its a hidraulic valve, for a molding injection machine. the board that i want to probe its rexroth mark. and the board uses many valves for injection, for closing clamp.

thanks again

RE: how to simulate a proportional valve?

If you are talking about SPICE simulation or a similar electronic circuit simulator then get a triangular waveform generator as one input to a comparator and use the error signal as the other input to the comparator. You will have to mess around with the signal offset and gain factors to get the proportional gain settings correct.

This simulation is non-trivial.

I am of course assuming that you are talking about proportional control of an on/off type of valve, where the duty cycle controls the proportional output. If you have a linear actuated valve then the simulation would simply consist of a few opamps, R's, C's and L's, to simulate the various system components.

RE: how to simulate a proportional valve?

I assume the basic purpose is for testing a board.  For that purpose, I would just use a resistor that was twice the DC resistance of the servo coil.  Then I would take a 470 ohm resistor from each side of the load resistor and feed that to a 1 uF non polarized capacitor.  A DVM could then measure the voltage across that capacitor.

RE: how to simulate a proportional valve?

Ok, I think I understand better what he means now.

http://www.boschrexroth.com/

I checked out the proportional hydraulic valves on the above site. The fluid flow is apparently monotonically dependant on the analog current into the solenoid coil. One beast in particular takes 30W (12V, 2.5A, 5 ohm coil). Testing the driver board would then consist of putting on a suitable load resistor and perhaps a moving coil meter to measure the output voltage. Obviously the board would have to be put into some sort of open-loop test condition.

RE: how to simulate a proportional valve?

(OP)
thanks for the comments logbook & operahouse

i dont know much about proportional hidraulics but i saw the drawings for the feedback wiring on a ENGEL manual for a mold injection machine and it seems to be a LVDT or a resolver, more than a variable resistor. i assume by this fact that the valvule hasnt a linear output.

thanks again

RE: how to simulate a proportional valve?

Most newer designs will have a pulse width modulated output.  Even older analog designs will have about 100Hz dither signal added to them to keep the valve from sticking.  Doubling the coil DC resistance should approximate the coil AC resistance, might even consider 3X.  The added resistors and capacitor will smooth out this signal so it doesn't drive a meter crazy. Tou could even attach a very small geared dc motor in place of the resistance.

On the other end ia a little more difficult.  The LVDT may output a signal that will vary the phase of the signal.  I you had a spare transducer, you could attach it to the motor via a cam or lever.  You would have to allow for continuous rotation.  An electronic simularor would likely be beyond explanation here.

RE: how to simulate a proportional valve?

(OP)
thanks for your advices.

and for the rexroth page

RE: how to simulate a proportional valve?

Morens,

You might also check out Moog's page. They're well-known in the precision servo valve business.

http://www.moog.com/

----------------------------------
  I don't suffer from insanity. I enjoy it...

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources