| 摘要 |
A multi-function valve assembly for controlling fluid flow through a single cavity, the valve assembly being particularly suited for use with an inflatable packer in a well bore. The valve assembly includes a control valve sliding piston in one end of a cavity such as a cavity in an inflatable packer, the cavity communicating between the interior of a tubular (such as well casing) and an annulus between the tubular and a wellbore in which the tubular is positioned. The control valve sliding piston isolates the packer until a certain predetermined pressure is reached, at which point it moves in response to the pressure of the fluid in the casing, thereby permitting flow of fluid from the casing into an inflatable bladder in the packer. An over-pressure piston disposed in the same cavity senses the packer inflation pressure and moves the control valve piston to close the valve, halting further inflation. A balancing locking stem is mounted within the cavity and both the control valve piston and the overpressure piston move in the cavity about this stem. The stem moves into the recess of an annulus gland in response to the action of the control valve piston.
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