Electro-hydraulically actuated proportional directional valves type 4WRZ(E)M…
Valves of type 4WRZ(E)M… are pilot-operated proportional directional valves with spool position indicator. They control the flow direction and size. They are actuated by the proportional solenoids of the pilot control valve.
Set-up:
The valve basically consists of:
- Pilot control valve (10) with proportional solenoids (5) and (6)
- Main valve (11) with main control spool (12), valve spring (13) and position indicator (14)
Function:
- With de-energized solenoids (5) and (6), the main control spool (12) is held in the central position by the valve spring (13).
- By energizing a proportional solenoid, e.g. solenoid "b" (6), the control spool (2) is moved to the right. Pilot oil enters the pressure chamber (15). The generated pressure moves the main control spool (12) proportionally to the electric input signal
- against the valve spring (13). This opens the connection from P to A and B to T via orifice-type cross-sections with progressive flow characteristics.
- Depending on the type, pilot oil is internally supplied to the pilot control valve via port P or externally via port X.
- When the solenoid (6) is switched off, the control spool (2) is returned into the central position by the compression springs (8) . This unloads the pressure chamber (15) towards the tank and the main control spool (12) is returned to the central position by the valve spring (13).
- Depending on the type, the pilot oil is returned internally from the pilot control valve to the tank via port T or externally via port Y.
- An optional manual override (16 and 17) allows the control spool (2) and with it the main control spool (12) to be moved.
Inadvertent activation of the manual override may result in uncontrolled machine movements!
Spool position indicator
The spool positions of the main control spool are detected by the inductive position switch (14) and displayed via two switching outputs with a preset logic. If the fixedly set switching points are exceeded, the deviation from the zero position is displayed within the control spool overlap.
The switching signals can be used in a superior control for monitoring functions.
The electrical connection is implemented separately via a 4-pole connector M12x1 with two pins for signal output and two pins for voltage supply.
Area of application:
The valve may be used in machines with high safety requirements, e.g. hydraulic press control systems.
In connection with a contact shut-off, the valve complies with the requirements for safety-related components of a control according to category 1, EN ISO 13849-1:2006 The "emergency stop" command or an error detected by the machine control has to result in the switching off of the valve supply voltage.
For the valve design the basic and well-tried safety principles according to ISO 13849-2:2003, tables C1 and C2 were used.
The valves are suitable for use in safety-related parts of controls according to category 4, EN ISO 13849-1:2006. This requires the entire control to meet the requirements of category 4, EN ISO 13849-1:2006 as well as the respective requirements of the applicable standards.
Please note chapter "Safety instructions"!
Notice:
The tank line must not be allowed to run empty. With corresponding installation conditions, a preload valve (preload pressure approx. 2 bar) must be installed.
