Patent ID: 6953098

Claim:
A hydraulic accumulator for use in a drill string having a fluid passageway for a supply of fluid at a selected pressure to a hydraulic drill string tool to maintain the selected pressure in the drill string, the accumulator comprising: (a) a body provided with connecting means for connecting the accumulator to the drill string; and (b) an expansion chamber in fluid communication with the drill string and having a fluid passageway therethrough, the expansion chamber being expandable between a first and a second position, wherein the expansion chamber volume is greater in the second position, and wherein the expansion chamber is provided with means for moving the expansion chamber from the first to the second volume upon a fluid pressure increase in the fluid passageway and for moving the expansion chamber from the second to the first volume upon a pressure decrease in the fluid passageway, wherein the expansion chamber further provides for a first fluid outlet from the expansion chamber to the hydraulic drill string tool as the expansion chamber moves to its second position, the first fluid outlet being closed when the expansion chamber is in its first position, and wherein the expansion chamber has a second fluid outlet in fluid communication with a part of the fluid passage down stream the accumulator when the accumulator is connected to the drill string by the connecting means.