Valves of type 4WRTE are pilot-operated directional control valves with electrical position feedback, integrated electronics (OBE) and optional spool position monitoring.
Set-up
The valve basically consists of 3 main assemblies:
- Housing (1) with main stage control spool (2) and optional spool position monitoring (13)
- Integrated electronics (optionally with electronics protection membrane (14)) with inductive position transducer (3) of the main stage
- Pilot control valve (4) with control spool/socket unit (5), inductive position transducer (6) and pressure feed back for central position of the main stage control spool (2)
Function
- With de-energized proportional solenoids (7; 8) central position of the main stage control spool (2) due to centering spring (9) and pressure feed back
- Control of the main stage control spool (2) via the pilot control valve (4) → the main stage control spool (2) is positioned in a regulated manner
- Controlling the control spool of the pilot control valve (4) by changing the solenoid force of the proportional solenoids (7; 8)
- Connection of the command and actual values in the integrated electronics
- Pilot oil supply to the pilot control valve internally via port P or externally via port X Pilot oil return internally via port T or externally via Y to the tank
- With a command value of 0 V, the electronics control the main stage control spool (2) in central position
Spool position monitoring
The spool positions of the main stage control spool (2) are detected by the inductive position switch (13) 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 monitored within the control spool overlap (see "Accessories").
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 can be used in safety-related two-channel applications (category 3, PL d and category 4, PL e according to EN 13849-1) as switch-off element for one channel. The valve meets the requirements of a secure start inhibitor according to EN 60204, stop category 0.
If safety requirements are needed, the supply voltage of the valve must be safely disconnected based on the
required safety level (category PL).
Depending on the application and the requirements of work equipment-specific standards according to EN 13849-1, the user must provide appropriate monitoring/plausibility checks which comply with the required
diagnostic coverage DCavg using a superior control.
Electronics protection membrane "-967"
To prevent condensate formation in the housing of the integrated electronics (OBE), an electronics protection
membrane (14) can be used.
Recommended for use outside industry-standard conditions with high ambient air humidity and significant cyclic temperature changes (e. g. outdoors).
Failure of supply voltage
- Integrated electronics de-energize the solenoid in case of supply voltage failure or cable break
- Automatic pressure control on the same level in the control chambers (10 and 11) by the pilot control valve
- In case of pressure supply failure, centering of the main stage control spool by centering spring (9)
- Central position of the main stage control spool (2)
Notices:
- Failure of the supply voltage will lead to an abrupt standstill of the control axis. The acceleration forces occurring in this connection may cause machine damage.
With control spool symbols E, E1-, W6- and W8-, the centering spring (9) sets the main stage control spool (2) in central position, control spools V- and V1 are switched to the preferred direction P to B and A to T in a tolerance range of 1% to a maximum of 11% of the control spool stroke.
- The PG fitting (12) must not be opened. Mechanical adjustment of the adjustment nut located below is prohibited and damages the valve.
- The zero point has been adjusted at the factory. Changes in the zero point may result in damage to the system and may only be implemented by instructed specialists.
- If the pilot control valve or the electronics are exchanged, the zero point has to be adjusted once again by instructed specialists.
Pilot oil supply
(schematic illustration)
Size 10
Size 16
Size 25
Size 27
Size 32
Size 35
| 1
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Plug screw M6 according to DIN 906, wrench size 3 – pilot oil return
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| 2
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Plug screw M6 according to DIN 906, wrench size 3 – pilot oil supply
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| 3
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Plug screw M12 x 1.5 according DIN 906, wrench size 6 – pilot oil supply
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| 4
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Plug screw M10 x 1 according to DIN 906, wrench size 5 – pilot oil return
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| 5
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Plug screw M10 x 1 according DIN 906, wrench size 5 – pilot oil supply
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| 6
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Main stage housing cover (opposite the OBE)
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Pilot oil supply external: 2, 3, 5 closed
Pilot oil supply internal: 2, 3, 5 open
Pilot oil return external: 1, 4 closed
Pilot oil return internal: 1, 4 open
"No code" version
External pilot oil supply
External pilot oil return
In this version, the pilot oil is supplied from a separate control circuit (external).
The pilot oil return is not directed into channel T of the main valve, but is separately directed to the tank via port Y (external).
Version "E"
Internal pilot oil supply
External pilot oil return
With this version, the pilot oil is supplied from channel P of the main valve (internally).
The pilot oil return is not directed into channel T of the main valve, but is separately directed to the tank via port Y (external).
In the subplate, port X is to be closed.
Version "ET"
Internal pilot oil supply
Internal pilot oil return
With this version, the pilot oil is supplied from channel P of the main valve (internally).
The pilot oil is directly returned to channel T of the main valve (internally).
In the subplate, ports X and Y are to be closed.
Version "T"
External pilot oil supply
Internal pilot oil return
In this version, the pilot oil is supplied from a separate control circuit (external).
The pilot oil is directly returned to channel T of the main valve (internally).
In the subplate, port Y is to be closed.
