The proportional valves D631 Series consist of an electromechanical
transformer (torque motor), a hydraulic amplifier
(nozzle/flapper principle), a spool in a bushing and a cantilever
feedback spring. The torque motor contains coils, pole pieces,
permanent magnets and an armature. The armature is connected
to a flexible tube which allows a limited rotation of the
armature and at the same time seals the electromagnetic components
against the hydraulic fluid.
The hydraulic amplifier is a full bridge arrangement with two
upstream fixed orifices and two downstream variable orifices
created by two nozzles and a flapper between them. The flapper
is connected at its upper end to the centre of the armature
and extends downward through the flexure tube to the
nozzles. A deflection of the flapper between the nozzles changes
the size of the variable orifices in opposite sense.
The 4-way spool controls fluid flow from pressure port to one
of the load ports and also from the other load port to return.
Deflection of the feedback spring due to spool displacement
produces a torque which is fed back to the torquemotor.

 Manual Detalhado do Produto