determining dither frequency and amplitude for a solenoid valve?

Thread Starter

navidelec

Joined Jul 12, 2014
29
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
 

Attachments

Reloadron

Joined Jan 15, 2015
5,916
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
 

Thread Starter

navidelec

Joined Jul 12, 2014
29
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
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:

timgow

Joined Aug 12, 2015
10
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
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
 

Reloadron

Joined Jan 15, 2015
5,916
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
 

timgow

Joined Aug 12, 2015
10
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
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
 

alfacliff

Joined Dec 13, 2013
2,458
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.
 

Reloadron

Joined Jan 15, 2015
5,916
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
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.

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.
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
 
Top