[150] 2-way flow control valve
The advancing piston rod
encounters a load half-way through its stroke. The flow control
valve nonetheless ensures that the advance speed remains
constant. From 0 to 2 seconds (shown at bottom right) the piston
rod is unloaded and the pressure conditions remain constant. When
the piston rod encounters the load, the pressure p_3 rises at the
outlet of the flow control valve. (In order to allow the rapid
control operations to be shown more clearly, the time scale now
changes to 1/100ths of a second.) The flow control valve briefly
raises the pressure p_2 downstream of the adjustable restrictor.
Following this, the regulating restrictor moves to the left, and
p_2 falls back to its original value, i.e. the pressure
difference between p_1 and p_2 remains constant. The regulating
operation shown is repeated a number of times, as the result of
which p_3 increases to 2.5 MPa (25 bar) in several steps and the
regulating restrictor opens more and more. (At the point at which
2.5 MPa (25 bar) is reached, the time scale changes back to 0.1
seconds.) The piston rod now travels under load just as fast as
previously without load.