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Creating a Hydraulic Fluid Supply System

By December 9, 2020 No Comments

Valcor Engineering Corporation has been a preeminent designer and manufacturer of fluid controls for aerospace applications since the start of business in 1951. Known for producing solenoid valves, pressure regulators, relief valves, check valves, manually operated valves and hydraulic accumulators (piston and edge welded bellows types) for many different types of aircraft, Valcor’s Aerospace group was approached by a customer to provide a complete hydraulic system, This system consists of a custom designed piston type hydraulic accumulator, a pneumatic pressurization system (including an 3ksi bottle, isolation valve, pressure regulator, fill and drain valve, pressure gauge), and a hydraulic flow regulator.

The function of the system is to inject oil under pressure into the aircraft’s engine exit nozzle. This is accomplished by using GN2 to pressurize a piston accumulator filled with 6 gallons of oil. The oil pressure is controlled by the GN2 pressure, which is closely held to 320 psi by a pneumatic regulator. The pressure is supplied to the regulator by a GN2 bottle, which is charged to 3,000 psi. This pressure is isolated from the regulator by a solenoid valve. The oil from the accumulator flows through a solenoid valve to a flow control valve which maintains a constant flow of 3.75 +.35 gpm.

The system also contains additional components. Two fill valves are provided for filling the GN2 bottle and the accumulator with oil. A third valve is provided to allow venting of the GN2 side of the accumulator when filling with oil. These three valves are located on a panel along with two pressure gauges. The gauges are used to monitor the GN2 tank and the oil pressure. The system downstream of the regulator is protected by a relief valve and a burst disc. The relief valve is used for regulator leakage and the burst disc is used in case the regulator fails open. The oil side has a relief valve that is used to compensate for thermal expansion of the oil.

One of the key attributes to the success of this system is the custom designed accumulator that fits within a cavity on a fighter aircraft, that used to house the gun. Both the fluid port and the pressurization gas port need to be on the same face of the accumulator without having external plumbing to provide gas pressure to the far side of the accumulator (location of the piston, when the accumulator is full of hydraulic fluid). The Valcor accumulator accomplishes these functions in a compact, competitively priced package.

Valcor also uses a custom designed hydraulic flow regulator that controls the flow of pressurized fluid from the accumulator, when needed.

All major parts in this system are Valcor designs, and the system schematic is as follows:

Hydraulic Accumulator:

This accumulator was specifically designed to fit within the gun cavity. Valcor took full advantage of our extensive technology (piston design/seals, pressure vessel design, etc.) to create this optimally designed accumulator. This accumulator has an extremely high expulsion efficiency due to its unique design. The use of commercially available materials and parts makes this accumulator very affordable.

Pressurization System:

Valcor created a pneumatic pressure control system that includes a fill valve, pressure regulator and solenoid valve (and gauges), that controls the pressure into the gas side of the accumulator. This gas pressure provides the motive force that expels the hydraulic fluid from the accumulator.

Hydraulic Flow Control Manifold:

Valcor created a unique hydraulic flow control valve that precisely controls the flow rate of the hydraulic fluid from the accumulator, into the aircraft system. This flow control valve is an all mechanical valve, that does not require the use of electronic controls, thereby reducing the system cost.

Illustration of the components in their installed positions

Valcor created a unique hydraulic flow control valve that precisely controls the flow rate of the hydraulic fluid from the accumulator, into the aircraft system. This flow control valve is an all mechanical valve, that does not require the use of electronic controls, thereby reducing the system cost.

The above system was designed specifically for our customer’s application, utilizing many heritage Valcor valves and accumulator technology. To further reduce cost and minimize lead time, off the shelf parts were procured for mounting and porting the components. Let us design your next hydraulic supply system.

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