The working principles of pilot-operated relief valves and ordinary relief valves
The direct-acting relief valve changes the pre-compression of the spring by adjusting the adjusting nut, thereby obtaining different opening pressures. Since there is a relief valve, why is there a need for a pilot-operated relief valve? It must be that the direct-acting relief valve has irreparable shortcomings. We know that as the working pressure of the relief valve increases, if a large opening pressure is required, the only way is to increase the spring stiffness. The greater the spring stiffness, the more difficult it is to assemble the relief valve. Therefore, someone has fully exerted their imagination and invented the pilot-operated relief valve. I won't go into detail about the specific structure of the pilot-operated relief valve. Let's mainly talk about the role of the pilot in the pilot-operated relief valve compared to the direct-acting relief valve.
The pilot-operated relief valve consists of a main valve and a pilot valve. The structure is shown in the figure.
When the system hydraulic oil enters the oil inlet of the pilot-operated relief valve, it will then enter the oil inlet of the pilot valve through the throttle orifice. This throttle orifice is very important. At the same time, the hydraulic oil also enters the upper cavity of the main valve spool. When the pressure of the hydraulic oil at the oil inlet is greater than the set pressure of the pilot valve, the pilot valve spool opens, and the hydraulic oil flows from the oil inlet of the pilot valve through the oil outlet to the fuel tank. The amount of oil in the oil inlet cavity of the pilot valve decreases, and the hydraulic oil at the oil inlet of the main valve will flow in through the throttle orifice to replenish the lost hydraulic oil. At this time, there is liquid flow in the throttle orifice. When the liquid passes through the throttle orifice, the pressure will decrease. That is, at this time, the pressure of the hydraulic oil at the oil inlet of the main valve is greater than the pressure at the oil inlet of the pilot valve. The pressure at the oil inlet of the pilot valve is equal to the pressure in the upper cavity of the main valve. That is, at this time, the pressure of the hydraulic oil at the oil inlet of the main valve is greater than the pressure in the upper cavity of the main valve, that is, the pressure acting on the lower end surface of the main valve spool is greater than the force acting on the upper end surface of the main valve spool. The main valve spool is lifted, and the oil inlet and oil outlet of the main valve are connected, playing the role of overflow and pressure stabilization.
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Shenyang HOlian Precision instrument co.,Ltd founded in 2017,is specialized production of oxygen generator accessories :Miniature solenoid valve for Portable Medical oxygen generator,4 Way 2 position Medical oxygen generator,3L to 10L Medical Oxygen Generator Solenoid Valve,pressure regulator assembly for oxygen concentrator,Pressure reducing Assembly for oxygen concentrator,Pinhole flowmeter of oxygen concentraror,Pinhole flowmeter of Medical oxygen concentrator,5L flowmeter for oxygen concentrator,Special firesafe Valve for oxygen concentrator,Firesafe Cannula Valve Oxygen Supply Tubing Connector,Oxygen primary filter,Medical Grade Filter,Check valve (material PA6),Check valve (material ABS),Oxygen generator accessories Molecular sieve tank head,Oxygen Concentrator Accessories Air Filters,Oxygen Concentrator Accessories NPT1/8-∅8 Connector,Oxygen Concentrator Accessories NPT1/8-∅10 Connector,Oxygen Concentrator Accessories 3 way Nozzle,Oxygen Concentrator Accessories 90° Nozzle,Mold manufacturing and i jection molding.