| 摘要 |
An inflatable packer assembly includes a cylindrical mandrel with a cylindrical valve body concentrically disposed about the mandrel. The valve body includes an inlet communicating with an interior of the mandrel and an outlet for directing fluid to an inflatable element of the packer assembly. First and second axial bores, containing first and second pistons, respectively, are disposed in said valve body and communicate with an end surface thereof. The first bore also communicates with said inlet. A first port connects the first and second bores. A second port connects the second bore and the outlet. The first piston which includes a check valve is held in a first position blocking said first port until a pressure differential across the first piston reaches a first level at which the first piston is released and is moved to a second position allowing fluid communication between the inlet and the first port. The second piston is held in a first position allowing fluid communication between said first and second ports until a pressure differential across said second piston which senses the packer element inflation pressure reaches a second level, higher than said first level, at which said second piston is released and is moved to a second position blocking said second port. At this time the check valve of the first piston is actuated blocking said first port. A check valve disposed about the packer mandrel also prevents fluid flow from said inflated packer element.
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