Isothermal Fluids Pump/Motor Case Drain

Will there be case drain options available at some point for pump/motor models in Simscape Fluids?

The models are working well overall but there are some corner case problems that result from not having case drains. For example, when a model is static (no rotary motion) the pressure doesn't bleed off from A/B ports as it would naturally in a typical closed-circuit hydrostatic transmission. To work around this I've added very small orifice models to replicate A-to-Case and B-to-Case leakage that is typical for axial piston motors.

If another solution exists already please advise.

Thank you

Answer 1

[Yifeng Tang]

Hi Philip,

I feel the way you model it is very reasonable. Adding an small orifice or check valve mimics what happens in real life.

A similar modeling concept may be found in this actuator block: https://www.mathworks.com/help/hydro/ref/doubleactingactuatoril.html where the diagram shows how the leakage is implemented, and indeed it's an orifice.

The parametrization of that orifice will require some empirical data though.