LoopFlushingValve-States

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LoopFlushingValve-States

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Iconic Diagrams\Hydraulics\Valves

Use

Domains: Continuous. Size: 1-D. Kind: Iconic Diagrams (Hydraulics).

Description

This model describes a loop flushing valve with lumped volumes.

LoopFlushingValve-States

 

Loop flushing valves are used to maintain a high quality working fluid in closed hydraulic circuits.  In closed hydraulic circuits  the oil is continuously flowing from a pump to an actuator. A loop flushing valve allows the oil to leave the circuit for cooling and filtering. If one side (pa) of the valve has a higher pressure, oil will flow from the other side (pb) out of the closed circuit and vice versa.

LoopFlushingValve

The circuit is always equipped (not shown above) with a charge pump to keep the suction side of the pump on a pre-pressure to avoid cavitation and so damage to the pump, and to exchange the fluid that is flushed.

 

Loop flushing valves are spring operated. I.e. a certain pressure difference between port a and b is required to open the valve. This pressure can be adjusted and is indicated by the parameter p_sw.

 

LoopFlushingValveDiagram

 

A small pressure difference is required to turn a valve from completely closed to completely opened. This overlap pressure is indicated by the parameter p_o.

Interface

Ports

Description

pa, pb

p_out

Input terminals of the valve.

Output terminal.

Causality

 

preferred pressure out pa

preferred pressure out pb

preferred pressure out p_out

 

Inputs

 

spoolpos

position of the spool valve: 0 =closed, 1 = open

0 <= spoolpos <= 1

Parameters

 

rho

GLeak

Amax

Cd

f

d

p_o

p_sw

Mass density of the fluid [kg/m3].

Conductance of the laminar leakage flows [m3/s.Pa], GLeak >= 0.

Maximum spool valve areas when the valves are open [m2], Amax > 0.

Discharge coefficient [], Cd > 0.

Bandwidth of the spool dynamics [Hz], f > 0.

Damping of the spool dynamics [], d > 0

Overlap pressure [Pa].

Switching pressure [Pa].