Sun’s new electrohydraulic pressure relief valve
By Mike Brezonick07 July 2021
Sun Hydraulics, the Sarasota, Fla.-based manufacturer of hydraulic cartridge valves, has developed a new high-capacity pressure control designed for fan drive motor systems. Sun said the RPEI electrohydraulic inverse proportional pressure relief valve combines attributes of an electro-proportional adjustable pilot stage valve and a high-capacity main stage valve to provide precise pressure control inversely proportional to the input electrical current. In the event of power or signal loss, the RPEI defaults to the maximum pressure setting to ensure that the fan drive continues to cool, the company said.
The two-port, pilot-operated relief cartridge is an electro-proportionally controlled, normally closed pressure regulating valve. The valve is spring biased closed to its highest setting, which is specified by the customer. Increasing current to the coil will proportionally decrease the pressure setting. When the pressure at the inlet is sufficient to overcome the spring force minus the solenoid force (as determined by the analog input signal) the poppet lifts and allows flow from the inlet to the outlet port.
Varying the analog input signal to the proportional solenoid provides a stepless control of pressure, the company said, and damped construction provides stable operation over a wide range of operating conditions.
The RPEI has a 25 gpm (95 lpm) flow capacity and is available in 3000 psi (210 bar) and 5000 psi (350) bar nominal pressure settings. Sun said it has been designed and tested to five million on-off operational cycles and it exceeds the new NFPA T2.6.1 R2014 test standard for fatigue and burst pressure ratings.
The RPEI works with Sun’s XMD valve drivers for any applications requiring closed-loop control. All configurations of the RPEI valve include zinc-nickel plating as standard for 1000-hour salt fog protection. Coil connector options offer ratings up to IP69K, Sun said.