REXROTH 4WRPEH series Directional control valves

REXROTH 4WRPEH series proportional directional valve: an Industry 4.0 solution that integrates intelligence and precise control

Product positioning and technological innovation

In the wave of modern industrial automation transforming towards intelligence and networking, hydraulic control technology has also undergone profound changes. The 4WRPEH series proportional directional valve launched by Bosch Rexroth is an outstanding representative of this trend. As a direct operated directional control valve with electrical position feedback and integrated electronic devices (On Board Electronics, OBE), it integrates traditional high-performance hydraulic technology with modern digital communication, intelligent diagnosis, and safety functions, providing a new solution for precise closed-loop control of position, speed, and pressure.

The 4WRPEH valve belongs to the 10 port, 3X component series, and its core design philosophy revolves around reliability, safety, energy efficiency, high quality, flexibility, and precision. The most eye-catching feature is its optional IO Link interface, which not only makes it an intelligent component that complies with Industry 4.0 (I4.0) standards, but also achieves a safety shutdown function that complies with EN 13849-1 standards and can reach up to Category 3, Performance Level (PL) d through specific configurations, paving the way for building a safety integrated machine control system.

Interpretation of Core Technical Characteristics and Models

1. Core components and structure

The 4WRPEH valve is essentially an electro-hydraulic proportional valve, and its core structure includes:

Servo quality valve core and sleeve (1): High precision matching valve core and sleeve are used to ensure extremely low hysteresis (≤ 0.2%) and excellent repeatability, which is the foundation for achieving high dynamic response and precision control.

Control electromagnet with position sensor (2): Built in non-contact position sensor, providing real-time and accurate feedback of the actual displacement of the valve core, forming the core feedback loop of closed-loop control.

Integrated Electronic Device (OBE) (3): This is the "brain" of the valve, integrating signal processing, power amplification, closed-loop control algorithms, and communication interfaces. It directly compares the instruction value with the actual value of the valve core position and drives the electromagnet.

Communication interface (4): Multiple interfaces can be selected, including analog (± 10V, 4-20mA) and digital (IO Link), to meet the access requirements of different control systems.

2. Model code and key options

The ordering code system defines all key parameters of the valve, which is the basis for correct selection. Taking code 4WRPEH 10 B 50 L 3X M 24 L1 as an example:

Valve core function (6th and 7th digit codes): such as "C3", "C5", "C1", etc., define the connection relationship between oil ports P, A, B, and T at different valve core positions. This is the core of selecting control logic (such as median function).

Rated flow rate (8th code): defined when the pressure difference Δ p on a single control edge is 35 bar, with two options: 50 L/min and 100 L/min. The flow rate follows the square root relationship formula with the change of pressure difference:

qx=qVnom⋅Δpx35q x=q Vnom⋅ 35Δp x

Traffic characteristics (9th code):

L-type (linear): The displacement of the valve core is linearly related to the output flow rate, suitable for applications that require linear speed control.

P-type (inflection point characteristic): There is an inflection point at about 40% of the spool stroke, with lower gain near zero position, providing finer micro motion control, and higher gain in high flow area, suitable for situations requiring fine low-speed control and fast high-speed response.

Sealing material (11th digit code): NBR (nitrile rubber) or FKM (fluororubber), the choice depends on the compatibility of the hydraulic oil used.

Electronic interface (14th code): This is the key to the level of intelligence.

A1: Analog voltage command input (± 10V), analog voltage actual value output (± 10V).

F1: Analog current command input (4-20mA), analog current actual value output (4-20mA).

L1: IO Link digital communication interface. This is the core of implementing Industry 4.0 integration, supporting parameter settings, status monitoring, diagnostic data reading, and firmware updates.

C6: Combination interface (± 10mA instruction, 4-20mA actual value, with enable signal).

Electronic protective film (15th digit code "967"): Recommended for use in high environmental humidity or severe cyclic temperature changes (such as outdoor applications) to prevent condensation from forming inside the electronic compartment.

Working principle and advanced functions

1. Closed loop proportional control

OBE receives command signals (analog voltage/current or IO Link digital commands) from the controller and compares them with the actual value of the spool position sensor. Once a control deviation occurs, OBE will immediately adjust the current output to the control electromagnet, thereby changing the electromagnetic force. This electromagnetic force opposes the reset spring, driving the valve core to move precisely to a position proportional to the command value, thereby infinitely adjusting the flow rate through the valve port. When the command value is zero, the electronic device adjusts the valve core to the neutral position. When the power is cut off, the spring is fully released and the valve core enters the fault safe position.