Explosion-Proof Proportional Directional Valve 4WRZ

Industrial Applications

• Explosion-proof directional valve 4WRZ-L7X is used to control the direction and flow in coil mining, coal mining machinery, metallurgical machinery.
• ■Pilot valve type 3DREP 6...
• The pilot valve is a proportional solenoid operated 3-way pressure reducing valve. It is used to convert an electrical input signal into a proportional pressure output signal and is used on all 4WRZ...valves.
• The proportional solenoids are controllable DC wet pin solenoids with central thread and detachable coil. The solenoid is optionally controlled by external electronics.
• Design:
• The valve basically consists of:
• – Housing (1)
• – Control spool (2) with pressure measuring spools (3 and 4)
• – Solenoids (5 and 6) with central thread
• Work principle
• –When the solenoids (5 and 6) are in the de-energized condition, the control spool (2) is held
• by compression springs in the central position
• –Direct operation of the control spool (2)by energizing a proportional solenoid, e.g. energization of solenoid "a" (5). Pressure measuring spool (3) and control spool (2) are shifted to the left in proportion to the electrical input signal; Connection from P to B and A to T through the orifice-like cross sections with progressive flow characteristics; De-energization of the solenoid (5), control spool (2) is returned to the central position by the compression spring, In the central position, ports A and B are open to T, i.e. the hydraulic fluid can flow to the tank without any restrictions.
• –Manual override, optional, with the help of it, the control spool (2) can be moved without requiring the energization of the solenoid.
• Notes:
• Type 3DREP 6: Draining of the tank line must be prevented. In the case of a corresponding installation situation, a pre-load valve is to be installed (pre-load pressure approx. 2 bar).
• Pilot valve with two spool positions
• (Type 3DREP 6...B...)
• In principle, the function of this valve version corresponds to that of the valve with three spool positions. However, this 2-position valve is provided with solenoid "a" (5) only. Instead of the 2nd proportional solenoid, a plug screw (7) is fitted.
• ■Pilot operated proportional directional valves Type 4WRZ...
• Valves of type 4WRZ... are pilot operated directional valves with operation by proportional in proportion solenoids. They control the direction and magnitude of a flow.
• Design:
• The valves basically consist of:
• – A pilot valve (9) with proportional solenoids (5 and 6), control spool (2) and orifce plugs (15)
• – A main valve (10) with main spool (11) and centering spring (12).
• Work principle
• – When the solenoids (5 and 6) are de-energised, the main spool (11) is held by centering springs (12) in the central position.
• – Op5eration of 1thAe TmBain spool (11) through the pilot valve (9),the main spool is moved proportionally, depending on the spool position, flow from P to A and B to T(R) or P to B and A to T(R).
• e.g. by energising solenoid "b" (6), the control spool (2) is shifted to the right, pilot oil is fed through the pilot valve (9) into the pressure chamber (13) and moves the main spool (11) in proportion to the electrical input signal; Connection from P to A and B to T through orifice-like cross-sections with progressive flow.
• characteristics.
• De-energization of the solenoid (6), the control spool (2) and main spool (11) are returned to the central position.
• – Pilot oil supply to the pilot valve internally via port P or externally via port X.
• – With the help of an optional manual override the control spool (2) can be moved without requiring the energization of the solenoid.
• Notes:
• For system pressures above 100bar the type D3 pilot pressure reducing module(14) must be fitted between pilot valve (9) and main valve (10).
• Symbols of Explosion-Proof Proportional Directional Valve 4WRZ