力士乐比例换向阀(5)

力士乐 比例换向阀

T A P Y X

B Function, section

Pilot operated proportional directional valves

Type 4WRZ…-7X/..XE...

Valves of the type 4WRZ... are pilot operated 4-way direc-tional valves that are actuated by means of proportional sole-noids. Their function is to control the flow direction and size.Set-up:

The valve basically consists of:

– Pilot control valve (9) with proportional solenoids (5 and 6)– Main valve (10) with main control spool (11) and centering spring (12)Functional description:– With de-energized solenoids (5 and 6), the main control spool (11) is held in central position by means of a center-ing spring (12).– Actuation of the main control spool (11) by means of the pilot control valve (9) – the main control spool is proportion-ally moved – e.g. actuation of solenoid "b" (6)→ Displacement of the control spool (2) to the right, pilot oil reaches the pressure chamber (13) pilot control valve (9) and displaces the main control spool (11) proportionally to the electrical input signal to the left → Connection of P → A and B → T via orifice-type cross-

sections with progressive flow characteristics

– Pilot oil supply to the pilot control valve internally via port P or externally via port X

– Switching off the solenoid (6)

→ Control spool (2) and main control spool (11) are returned to central position

– Flow depending on spool position from P → A and

B → T or P → B and A → T.

Type 4WRZ…-7X/..XE...