PROBLEM TO BE SOLVED: To provide an exploratory device in a pipe body capable of quickly advancing in a pipe body, an extendable unit being favorably adoptable for the exploratory device in the pipe body, and a mobile body in the pipe body.SOLUTION: The extendable unit includes a tubular extendable body being extendable/contractable in the axial direction, and an elastic expansion body that is disposed at an outer peripheral side of the tubular extendable body, axially contracts by a supply of fluid to an air chamber formed between itself and the tubular extendable body and axially extends by discharge of the fluid, and is assembled in a mobile body in a pipe body capable of advancing in the pipe body. The extendable unit further includes at the outer peripheral surface side of the elastic expansion body, a low-frictional layer, a friction coefficient of which with the inner peripheral surface of the pipe body is smaller than a friction coefficient between the outer peripheral surface of the elastic expansion body and the inner peripheral surface of the pipe body and that, in the contraction of the elastic expansion body, allows the outer peripheral surface of the elastic expansion body to be exposed to the inner peripheral surface side of the pipe body.COPYRIGHT: (C)2015,JPO&INPIT【課題】管体内を速やかに進行可能な管体内探査装置、及び当該管体内探査装置に好適に採用可能な伸縮ユニット、管体内移動体を提供する。【解決手段】軸方向に伸縮可能な筒状伸縮体と、筒状伸縮体の外周側に配設され、筒状伸縮体との間に形成された空気室への流体の供給により軸方向に収縮し、流体の排出により軸方向へ伸長する弾性膨張体とを備え、管体内を進行可能な管体内移動体に組み込まれる伸縮ユニットであって、弾性膨張体の外周面側に、管体の内周面との摩擦係数が弾性膨張体の外周面と管体の内周面との摩擦係数よりも小さく、弾性膨張体の収縮時において管体の内周面側への弾性膨張体の外周面の露出を許容する低摩擦層を設けた。【選択図】図1
