determining dither frequency and amplitude for a solenoid valve?

Discussion in 'General Electronics Chat' started by navidelec, Jan 22, 2015.

  1. navidelec

    Thread Starter New Member

    Jul 12, 2014
    29
    0
    In the above figure from Hydraforce.com the frequency and amplitude for a solenoid valve is 70-350 Hz , regarding the valve mechanical response it is too high for the valve response to this range of frequency dither,
    I wonder if you tell me what is the procedure to determine the valve mechanical response to the dither,
    the relation between the amplitude of the dither to the frequency of it,
    and what is the procedure to determine the amplitude and frequency of the dither for a special valve?

    the Figure address:
    http://www.hydraforce.com/electro/E...ec_Mobile_Equip/3-440-1_Elec_Mobile_Equip.htm
     
  2. Reloadron

    Active Member

    Jan 15, 2015
    969
    235
    My best guess is dither amplitude and frequency will be a function of the valve body or the specific valve. It's been maybe 30 years ago I got involved (more like sucked into) several hydraulic shaker tables and other fun filled hydraulic things using mostly Moog Valves and Moog servo controllers. You may want to give some of these documents a glance as to dither. For a special valve, as you mention you may want to contact the valve manufacturer for detailed info.

    Ron
     
    navidelec likes this.
  3. navidelec

    Thread Starter New Member

    Jul 12, 2014
    29
    0
    Dear friend

    in the one of the moog documents I saw this: The dither frequency depends on the electrical characteristics of the valve.
    I want to find the valve cut-off frequency by finding the L and R with LRC meter and by the equation of f=R/(2*pi*L) the cut-off freq. is been define.
    and after finding the cut-off freq. for example 160 Hz, then use a dither frequency near and less than this cut-off frequency about 150 Hz.
    Is this correct, according to the moog document that it mentioned the dither is depends on electrical characteristics.
    I wonder if you help me on this.
     
    Last edited: Jan 23, 2015
  4. Reloadron

    Active Member

    Jan 15, 2015
    969
    235
    Getting the dither right requires more than just knowing the frequency response of the coil. I suggest you start with giving this a read. Finding the valve cut off frequency is a good start. Also this may help a little. Again, I generally just look at the manufacturers data sheet or contact the manufacturer.

    Ron
     
    navidelec likes this.
  5. timgow

    New Member

    Aug 12, 2015
    10
    0
    Thank you Navidelec for asking the question.

    Reloadron,
    The link to 'may help a little' is broken, do you have the document title or a current link?
    Tim
     
  6. Reloadron

    Active Member

    Jan 15, 2015
    969
    235
    That was awhile ago and yes, the link no longer works. I don't remember where it went unfortunately. A Google of Dither Frequency brings up quite a few hits. Used dither years ago on hydraulic vibration tables.

    Ron
     
  7. timgow

    New Member

    Aug 12, 2015
    10
    0
    Ron, thank you for the quick reply.
    I'm using pressure difference across an orifice plate as gas flow rate feedback to a proportional valve. I'm going to try using an H-bridge driver + microprocessor.
    Tim
     
  8. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    dither is the ripple from the pwm, the valve does not produce dither, or need it for operation. it is ripple, and should be higher than the response time of the valve.
     
  9. Reloadron

    Active Member

    Jan 15, 2015
    969
    235
    While I never did it with gas I did do it with water at 600 degrees F. and close to 3,000 PSIG. Measured the differential pressure across an orifice plate to calculate flow. That signal went to my flow control circuits. We just used a large proportioning valve to control flow less any dither.

    That about covers it. It was used to keep the valve from sticking and the frequency was faster than the valve could respond to.

    Ron
     
Loading...