Patent ID: 9200496
Filing Date: 2015-12-01
Classification: E21B,Y10T

Abstract:
1. A pressure compensating device for compensating fluid pressure within a sealed enclosure, the pressure compensation device comprising a cylinder divided into a first chamber and a second chamber by a piston, the piston being movable within and supported for movement by the cylinder through a permitted range of movement, the piston being housed entirely within the cylinder such that no part thereof or integer movable therewith projects from the cylinder, in use, wherein: the first chamber communicates with the enclosure and the second chamber communicates with the environment; other than when the piston is at or near at least one end of the permitted range of movement, the piston is arranged to adjust the relative volumes of the first and second chambers in response to a difference in pressure between the said chambers by moving within the cylinder without permitting fluid communication therebetween; and the piston being arranged to allow fluid communication between the first and second chambers, and hence between the enclosure and the environment, only when the piston is at or near at least one end of the permitted range of movement, wherein a flow path is provided past the piston to allow fluid communication when the piston is at or near an end of the permitted range of movement of the piston, the flow path being defined between the piston and at least one axial groove in an inner wall of the cylinder.