Page 492 - Mechatronics with Experiments

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P > P
L1 L2

P P
s L1

Q
v1

P s P L2

Q
s
P Q
relief
v2

FIGURE 7.58: An example illustrating the need for pressure compensator valves in multi
function parallel circuits.

goes into each cylinder depends on the load pressure. More flow will go to the circuit with
the smaller load pressure, and the flow ratio is
√
Q v1 p − p l1
s
= √ (7.211)
Q v2 p − p l2
s
For instance, let p = 3000 psi, p = 2000 psi, p = 1000 psi, same size valves, and same
l2
s
l1
valve spool displacement in each circuit. The flow rate distribution betwen the two
circuits is
√
Q v1 3000 − 2000 1
= √ = √ (7.212)
Q v2 3000 − 1000 2
If the load condition changes, the flow rate will change: let p = 3000 psi, p =
s l1
1000 psi, p = 2000 psi, and same size valves and valve spool displacement in each circuit.
l2
The flow rate distribution betwen the two circuits under this load condition is
√ √
Q v1 3000 − 1000 2
= √ = (7.213)
Q v2 3000 − 2000 1