Rexroth Proportional Valve 4WRKE

Rexroth Propotional Valve 4WRKE Description

Rexroth proportional directional valve 4WRKE is a high-performance closed-loop proportional directional valve. Through the pilot proportional valve to control the movement of the main valve core, a high-precision electric position feedback device and a built-in amplifier are installed on the main valve body for the valve itself. The closed-loop control allows precise proportional control of the flow direction and flow. However, some problems have also been exposed during use. If they do not cause a high degree of daring, they may severely restrict the stable operation of the equipment, shorten its service life, and increase maintenance costs.

Compared with the ordinary open-loop proportional directional valve, the 4WRKE type valve can realize its own closed-loop control, so it is not sensitive to the sudden change of the large range of flow, and it will not cause the valve core to lose control due to the hydraulic force acting on the valve core. This valve also has a relatively good frequency response characteristics (frequency response up to tens of Hertz), and is particularly suitable for occasions where there is a high requirement for pre-buffering in the device's constant acceleration/deceleration shifting motion. Compared to the servo valve, the main stage and the pilot stage of this type of valve adopt the structure of the slide valve, which is not sensitive to the cleanness of the oil and the price is also low. The dead zone, gain, vibration and offset of the valve have been adjusted and packaged in the factory according to the standard. Therefore, it has good maintainability, convenient disassembly and installation, and no adjustment after installation. It is a kind of high-performance ratio that is ready to use. Valves can be used in place of servo valves in some applications to control the opening, stopping, and direction of fluid flow.

Pilot control valve type Rexroth 4WRAP 6 W7.3X/G24… (1st stage)

The pilot control valve is a direct operated proportional valve. The control edge geometry has been optimized for the use as pilot control valve for proportional directional valves type 4WRKE. The proportional solenoids are pressure-tight, wet-pin DC solenoids with detachable coils. They convert the electric current proportionally into mechanical force. An increase of the current results in a correspondingly higher solenoid force. The set solenoid force will remain constant over the entire control stroke.

The pilot control valve mainly consists of the housing (1), the proportional solenoid (2 and 3), the valve control spool (4) and springs (5 and 6). In non-actuated state both actuators are connected to the tank. If one of the two solenoids (2 or 3) is excited, the magnetic force will move the valve control spool (4) towards the spring (5 or 6). After having overcome the overlap area, the connection of one of the two actuators to the tank is blocked and the connection to the pressure chamber is made. There is a flow from P to the control chamber of the main stage.

Rexroth Valves of type 4WRKE are 2-stage proportional directional valves. They control the flow direction and size. The main stage is position-controlled so that the control spool position is independent from flow forces also in the case of bigger flows.

The valves mainly consist of the pilot control valve (1), the housing (8), the main control spool (7), the covers (5 and 6), the centering spring (4), the inductive position transducer (9) and the pressure reducing valve (3). If there is no input signal, the main control spool (7) will be kept in the central position by the centering spring (4). Both control chambers in the covers (5 and 6) are connected to the tank via the valve control spool (2). The main control spool (7) is connected to suited control electronics via the inductive position transducer (9). Both the position change of the main control spool (7) and the change of the command value at the junction summing of the amplifier create a voltage difference. During the comparison of command value and actual value, a possible control deviation is determined via the electronics and the proportional solenoid of the pilot control valve (1) is supplied with current. The current induces a force in the solenoid which operates the control spool via a plunger in a row. The flow which is activated via the control cross-sections leads to an adjustment of the main control spool. The main control spool (7) with the core of the inductive position transducer (9) attached to it is displaced until the actual value corresponds to the command value. In controlled state, the main control spool (7) is force-balanced and kept in this controlled position. The control spool stroke and the control opening change proportionally to the command value. The control electronics is integrated in the valve. By adjusting valve and electronics, the deviation in series production of the devices is kept low.

The tank lines must not be allowed to run empty; with corresponding installation conditions, a preload valve (preload pressure approx. 2 bar) must be installed.

Rexroth 4WRKE valve particularities

The 2nd stage is basically set-up of modules of our proportional valves. The zero point adjustment at "zero point main stage" is made at the factory and can be adjusted in a range of ± 30% of the nominal stroke via a potentiometer in the control electronics. Access in the integrated control electronics by removing a plug screw on the front side of the cover housing. When the pilot control valve or the control electronics are exchanged, they are to be re-adjusted. All adjustments may be implemented by instructed experts only.

Welcome enquiry us if you interested in Rexroth valve 4WRKE or any other Rexroth proportional valves and servo valves.  4WRKE 10, 4WRKE 16, 4WRKE 25, 4WRKE 27, 4WRKE 32, 4WRKE 35. TECHNIQUE B.V. is your components resource from the Netherlands for hydraulics and electronics. 

Rexroth 4WRKE Features

-Pilot-operated 2-stage proportional directional valves with electrical position feedback of the main control spool and integrated electronics (OBE)

-Control of flow direction and size

-Proportional solenoid operation

-For subplate mounting: Porting pattern according to ISO 4401

-Electrical position feedback

-Spring-centered main control spool

-Pilot control valve: single-stage proportional directional valve

-Main stage with position control

Rexroth valves 4WRKE are used in steel, metallurgical, aluminum, petrochemical, aerospace, shipbuilding, coal, cement, electricity, automotive, construction machinery, food, forestry, textile, leather, papermaking and other industries.