pilot operated check valve to open only by pilot pressure x

The pilot operated checkvalve provided in simscape fluids is operated by pressure at A or pilot pressure X or both, I wish to open the checkvalve only by pilot pressure . can anyone say is there anything I can do?

[Yifeng Tang]

If it's only operated by the pilot pressure, will this still be a "check valve"?

In the "Pilot-Operated Check Valve (IL)" block, the opening pressure is p_control=p_pilot*kp+(p_A−p_B), which is compared to cracking pressure. Are you thinking about taking p_A and p_B out of this equation?

If so, a pilot valve actuator and a orifice can help you achieve that: https://www.mathworks.com/help/physmod/hydro/ref/pilotvalveactuatoril.html

[murali manohar boopathy]

actually my need is to close a checkvalve with a pilot pressure i.e even when there is craking pressure at A ,the pilot pressure should close the checkvalve but I found the checkvalve in simscape fluids opens with pilot pressure x so i chose to open the checkvalve when needed as i need to open and close 2 checkvalves but the checkvalve is in a way that it opens with both pressure at A and X like it's in double pilot checkvalve. I have attached a picture for your better understanding of my problem.

[Hamed Shamsi khani]

Hello.

I'm working at excavator engineering department.

It's very intersting that you want to open a check valve with a signal!

Do you want to analysis your hydraulic circuit( attached photo)?

Answer 1

[Yifeng Tang]

Thanks for the details.

The pilot in this case is acting in the opposite direction as in the "Pilot-Operated Check Valve (IL)" block. It's equivalent to having a negative pilot ratio, but it won't allow you to set a negative value in the block.

Anyway, I think your best bet is to use a "Cartridge Valve Actuator (IL)" and a "Orifice (IL)" block.

https://www.mathworks.com/help/physmod/hydro/ref/cartridgevalveactuatoril.html

https://www.mathworks.com/help/releases/R2021a/physmod/hydro/ref/orificeil.html

The actuator allow you to open the check valve, with a physical signal, when the pressure combination is correct, and the Orifice will translate that signal to an opening that allows/blocks flow.

[murali manohar boopathy]

Thanks a lot yifeng tang for your response , is that the cartridge valve actuator which only gives physical signal and not any flow so that we use the signal to open the orifice? and by using this arrangement we can eliminate the check valve right?

And also I used hydraulic cartridge valve actuator and not cartridge valve actuator(IL) in my model, I am also curious to know when to model a isothermal system and use isothermal components and when to model a hydraulic model, thanks in advance!

[Yifeng Tang]

Yes, the actuator should generate no flow in the Hydraulic or Isothermal Liquid ports and produces a physical signal that you can use to drive the Orifice. You may need a PS lookup table to estabilish the spool position PS from the actuator to the Orifice opening size (depending on which orifice block you end up using). But be careful with how you connect the ports and read the documentation here for when an opening condition is met with this actuator block: https://www.mathworks.com/help/physmod/hydro/ref/cartridgevalveactuatoril.html

I THINK you'll need the 4-port configuration, with the B port unused. PLEASE go over the math yourself.

"Hydraulics" vs "Isothermal Liquid": check out this page https://www.mathworks.com/help/physmod/simscape/ug/upgrading-hydraulic-models-to-use-isothermal-liquid-blocks.html#mw_6db868a4-020d-402e-9cc4-aed14307a38f

"Starting in R2020a, MathWorks recommends that you use the Isothermal Liquid blocks for modeling hydraulic systems where the working fluid temperature remains constant during simulation."

[murali manohar boopathy]

Thank you so much Yifeng Tang for your assistance!