How to initialize a check valve (TL)?

I have a simscape multi-domain model with a fixed-displacement pump (TL) which drives hydraulic fluid from a low pressure side of the system to a high pressure side of the system through a check valve at the discharge. I am initializing system pressures with a seperate subsystem using a Pressure Source (TL). I have had to connect both sides of the fixed displacement pump to the reservoir feeding the Pressure Source so that the pump doesn't turn into a generator at t=0 because it appears that the pressure source bypasses the check valve, and pressurizes both sides of that valve even when the valve is shut.

How can I better initialize hydraulic system pressures on the high pressure side, without turning the pump into a generator?

This is the pressure differential across the pump. At time 0.02 seconds, I am shutting a 2 way valve which sinks the pump discharge to the same reservoir which the pump inlet is sinked to.

[Dyuman Joshi]

"I am initializing system pressures with a seperate subsystem using a Pressure Source (TL). "

Any particular reasons why? Do you not have an actuator connected to the circuit?

"I have had to connect both sides of the fixed displacement pump to the reservoir feeding the Pressure Source ..."

Why both sides?

"At time 0.02 seconds, I am shutting a 2 way valve which sinks the pump discharge to the same reservoir which the pump inlet is sinked to."

I think it would be better for us to understand your problem with a circuit diagram.

[Yifeng Tang]

Hi @Bill,

It'll be easier for the community to understand your question and try to help if you could include your model, or at least a complete snapshot of your model. It's very difficult to diagnose based on text and a graph.

Answer 1

[Satyam]

Hi @Bill,

When initializing hydraulic systems in Simscape, pressure sources enforce conditions globally during initialization, which can bypass valve logic. You can try out the following steps:

Use Initial Targets Instead of Pressure Source

• Set initial pressure targets on the high-pressure side using the Initial Conditions tab of Reservoir (TL) or Hydraulic Reference blocks.
• Specify Initial Conditions

Assign Initialization Priority

• Give High Priority to the high-pressure reservoir and Low Priority to the pump to prevent reverse flow.
• Initialization Priority

Configure Check Valve

• Ensure the Cracking Pressure is set so the valve remains closed during initialization.
• Check Valve (TL)

Avoid Direct Pressure Source on Pump Discharge

• A direct pressure source bypasses the valve logic. Use a Controlled Pressure Source with zero flow or rely on initial targets.