Patent ID: 7370706

Claim:
A gas lift valve capable of withstanding high differential pressure comprising: bellows containing a plurality of convolutions, wherein the bellows can contract and expand; an upper adapter secured to a first end of the bellows and containing a charge of gas; a lower adapter connected to a second end of the bellows; a sleeve disposed within the bellows, a first end of the sleeve secured to the lower adapter, and a second end slidably disposed through the upper adapter; a central bore in the sleeve, wherein a first end of the central bore is in fluid communication with the charge of gas in the upper adapter; a piston with an external seal slidably disposed in the internal bore of the sleeve; a first and second travel stop limiting the movement of the piston within the bore, wherein the first travel stop is located toward the first end of the central bore and the second travel stop is located toward the second end of the central bore; a longitudinal fluid port at the second end of the sleeve providing fluid communication between the inside of the convolutions of the bellows and the internal bore of the sleeve; an incompressible fluid located inside the convolutions of the bellows; wherein upon contraction of the bellows, the piston travels to the first travel stop, allowing more of the incompressible fluid to move from the interior of the bellows convolutions to the central bore through the fluid port; wherein upon extension of the bellows, the piston travels to the second travel stop, forcing more of the incompressible fluid from the central bore into the interior convolutions of the bellows; a fluid selected from the group consisting of an injection gas and a well fluid, wherein the fluid is located exterior of the bellows and provides an external pressure on the bellows; wherein the amount of incompressible fluid in the interior bellows convolutions when the piston is at the first and second travel stops is sufficient to provide an internal pressure that is approximately the same as the exterior pressure on the bellows from the injection gas.