Various applications exist where high-pressure valves are required, but the problem for control of such valves lies in that they have to move against a strong pressure differential that may require significant force, energy, and large actuators. The solution to this problem is to take advantage of the in situ pressure differential to operate valves by opening small valves to change the pressure on either chamber of a hydraulic cylinder that is connected to the valve’s moving element.

A schematic diagram of the concept of the valve control system that uses in situ pressure differentials to operate a linear sleeve valve. This concept could also be designed to be a rotary valve.
A sleeve valve is mounted on a pipe to control the flow between the inside and outside of the pipe. In the case where a sizable pressure difference exists between the outside and inside of the pipe, one could adjust the pressure in the up or low chamber of the cylinder to be high or low to change the direction of motion of the piston by opening a 3-way valve to expose the chamber to a high-pressure or low-pressure region. The maximum output force of the cylinder is proportional to the pressure differential and the effective area of the cross-section of the cylinder. With a sufficient effective area, the cylinder actuator is able to overcome the resistance to move the sleeve where the pressure differential is sizable. In the case where the pressure differential is small, a small pump, sized to account for the remaining friction of the valve, can be used to create a pressure to drive the hydraulic cylinder. The operation of this small pump and the 3-way valves requires much lower force/torque and power than that of the one required to operate the valve against the high pressure directly.

The specific solution for application to oil down-hole flow consists of a 4-port valve that is able to connect the pressure of inlet P2 and outlet P1 to a cylinder actuator to drive a sleeve choke valve that controls the flow from the outside of the inner pipe to the inside. A small pump is inserted into the high-pressure (P2) connection line in order to produce additional pressure difference of p and to increase the P2 to P2 + p in case the pressure difference of P = P2 – P1 is not large enough. In this configuration, the 4-port valve has three positions for three different outcomes.

This work was done by Xiaoqi Bao, Stewart Sherrit, Mircea Badescu, Yoseph Bar-Cohen, and Jeffery L. Hall of Caltech for NASA’s Jet Propulsion Laboratory.

In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:

Innovative Technology Assets Management
JPL
Mail Stop 321-123
4800 Oak Grove Drive
Pasadena, CA 91109-8099
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Refer to NPO-48798.

NASA Tech Briefs Magazine

This article first appeared in the November, 2014 issue of NASA Tech Briefs Magazine.

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