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Optimised performances and integration of the greatest number of functions are the objectives planned and achieved through the development of the HPV
valves, a range of the latest generation of proportional directional valves that perform two simultaneous
functions: directional control and flow control that is unaffected by load
variations.
Their operation is based on the proportional hydraulic
principle, i.e. keeping pressure loss constant through a variable
section. The HPV spool can assume an infinite number of positions making the crossing areas infinitely
variable, thus regulating the flow in relation to the pressure difference (Δp) throughout the entire operating
range. By means of logical selection, an LS signal (feedback) is taken from the highest pressure ports and its sent to the flow-pressure regulator in the inlet section
(if the circuit operates with a fixed displacement pump) or directly to the Load Sensing pump
(for a closed centre circuit). As long as the circuit senses the Δp, the valve will maintain its proportionality
properties.
Instead, if Δp tends to decrease, for example if actuator flow demand exceeds the overall pump flow (multiple simultaneous
operations), the flow to the ports will be completely random, and in any case will tend to flow toward the actuators which will work at the lowest pressure
values. The baric compensation provided by the two-way pressure compensators installed on each
element, allows multiple operations to be performed at the same time without reciprocal
effects. On the other hand, operating at the same time elements without
compensators, the flows will vary in relation to the work pressure
values.
Technical features
The main hydraulic features of the HPV valves are summarised
below:
Flow control (metering) is independent from load, therefore the flow provided at the ports does not change with a variation in work pressure of the utilities they
control.
The flow of each function is independent from the simultaneous work
pressures, thus allowing simultaneous operations to be carried out without reciprocal
effects.
Electrical unloading of the LsA and LsB signals on each
element.
Excellent flow control characteristics, without dead
bands.
Symmetrical distribution, that allows the position of the manual control to be reversed with all
servocontrols.
Precise and safe remote controls (hydraulic, proportional
electrohydraulic) that are easy to install.
Funzionamento sia con pompe a cilindrata fissa che a cilindrata variabile con regolatore load
sensing.
Operation with both fixed displacement and variable displacement pumps with Load Sensing
regulator.
Remote control of operating pressure of each port.
Internal pilot line supply.
Externally fed hydraulic manipulators.
Possibility of lowering the stand-by pressure of the pump
(only with the open centre version).
 Modules and commands
Modules in accordance ATEX
direct.
Modules selection chart
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