ARGO-HYTOS' PRM8 Servo-Assisted Proportional Valve Enables Precise Movements of Machine Attachments

ARGO-HYTOS developed its PRM8 servo-assisted proportional valve to deliver precise movement of tiltrotator excavator attachments developed by Sweden-based Engcon.

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The Sweden-based company Engcon is the world’s leading manufacturer of tiltrotators. These extra attachments for excavators are installed between the handle (excavator boom) and the bucket, and enable the tool to rotate by 360 degrees and tilt laterally +/- 40 degrees. The precise movements of the tiltrotators are made possible by ARGO-HYTOS control blocks and single valves, where nominal size 06 directional valves and screw-in valves are used.

ARGO-HYTOS designed the PRM8 (nominal size 06) balanced proportional valve specifically for this application. It is characterized by the fact that, unlike commercially available solutions, the servo control is integrated into the valve itself. In terms of the electrical and hydraulic interfaces and dimensions, PRM8 is identical to nominal size 06 direct-acting proportional valves. This means it can regulate unusually high volume flows of 85 l/min.

The applied follower piston principle prevents the proportional valve from reducing the cross-section in the event of an increasing pressure difference over the control edge by way of internal compensation of the flow forces. This ensures a direct proportionality between the volume flow and the pressure differential with a constant electrical signal.

Back in the development phase, initial considerations were supported on the basis of a system simulation. The “Valve” system was reproduced in MATLAB-Simulink. The goal was to optimize the valve characteristics prior to creating the initial prototypes. To make the simulation as realistic as possible, data was accessed from existing measurements (e.g. force-displacement characteristic of the drive system) and from other detail simulation tools such as flow simulations for determining flow forces.

The quality of the simulation can be seen in both simulation software graphics. They illustrate the result of the simulation and the measuring result of a first sample in direct comparison. The high correlation between simulation and measurement is the result of the development team’s many years of experience and the development expertise in ARGO-HYTOS.

Development times are significantly reduced through the use of simulation tools in product development. This way reliable data is available early on for discussion with the customer. The quick and precise implementation of customer requirements was also the deciding factor for Engcon when selecting ARGO-HYTOS for the control of tiltrotators.