Patent ID: 6601652
Filing Date: 2003-08-05
Classification: E21B

Abstract:
A self-propelled tool for moving within a passage comprising:a body configured to convey a working fluid for powering movement of the tool; a gripper movably engaged with said body, said gripper including at least one gripper portion, said gripper portion having a first position in which said gripper portion limits movement of said gripper portion relative to an inner surface of said passage and a second position in which said gripper portion permits substantially free relative movement between said gripper portion and said inner surface; a thrust-receiving member longitudinally fixed with respect to said body; and a propulsion assembly for selectively thrusting said body with respect to said gripper portion of said gripper in said first position, by controlling the flow of fluid in contact with said thrust-receiving member, said propulsion assembly comprising: flow regulating means for selectively permitting the working fluid to flow through said flow regulating means to a side of said thrust-receiving member to impart a thrust onto said member for moving said body with respect to said inner surface of said passage, said flow regulating means being controlled substantially by fluid pressure forces; and thrust control means for preventing said thrust from exceeding a set threshold value regardless of a pressure of the working fluid flowing through said flow regulating means, by internally continuously self-regulating at least one of pressure and flow of fluid within the tool.