RPEK2 – From valve to modular blocks

The development of the RPEK1 directional control valve was driven by the desire to efficiently achieve simple directional functions while conserving space. The valves are designed for a flow of up to 20 l/min and pressures up to 250 bars, illustrating the focus of the series on applications using gear pumps to generate pressure. Combining the RPEK1 directional control valve and the SMA05 hydraulic power unit results in a compact unit which boasts a variety of functions in a minimum of space.
Both in combination with small units and as “valve islands”, the RPEK1 occasionally reached its limits because only directional functions without secondary functions were supported. An increasing number of applications with secondary valves and added functionality for the directional control valves led to the development of the RPEK2 block.

The challenge for the design engineers was the integration of:
- Pilot operated check valves
- throttle check valves
- secondary pressure relief valves
- pressure reducing valves
- 2/2 seat valves

As the ARGO-HYTOS product range already features a complete nominal size 04 CETOP series with all of the common modular valves, a two-tier expansion range of the RPEK2 valve series was introduced. The nominal size 04 modular valves, proven over many years and available around the world, are used as a longitudinal valve combination for the RPEK2 blocks (see Figure 1) and screw-in valves were combined with pre-existing valve assemblies in new flange housings for a sandwich arrangement of valves (see Figure 2).

Due to the modular design, the sandwich arrangement of valves and the longitudinal valve combination can be combined as desired. By using standardised flange patterns according to ISO 4401 and screw-in valves with the world’s most common hole geometries 3/4 UNF and 7/8 UNF, our design engineers have managed to combine the tried and trusted with innovation.
The number of sections is limited to eight due to the elastic limit of the assembly bolts. With an input block in the middle, up to eight sections can be flange-mounted to each side, making a maximum of 16 sections per valve interconnection possible.

Input blocks with centralised pressure relief devices and switchable depressurised cycles are available in addition to proportional control loops to influence the velocity of individual consumers. The proportional control loop features a three-way pressure maintenance valve and regulates the system pressure to approx. 10 bars above load. Orifices in the consumer connections can be used in conjunction with the adjustable three-way pressure maintenance valve as speed limitations for individual consumers.

Compared to valves with nominal size 04 and 06, the RPEK2 boasts significant advantages in terms of weight and space requirements (see comparison chart).
Areas of application for the RPEK2 series directional control valve include, for example, additional and auxiliary functions in construction and agricultural machines. The maximum power of 20 l/min at pressures of up to 250 bars is more than sufficient for a wide range of applications. In combination with the SMA05 hydraulic power unit, many functions for machine tools, sawing machines and mobile applications can be effectively realised in compact form.
The introduction of the RPEK2 series represents a further step for ARGO-HYTOS towards the principle “only as many valves as the function needs”.