Patent ID: 8640602

Claim:
A fluid injection type actuator comprising: a tubular body consisting of an elastic body; and a lid member at each end of the tubular body, configured to have a pressure of a fluid supplied into a space formed by the tubular body and the lid members expand the tubular body radially thereby contracting it longitudinally, wherein the tubular body has three or more annular fiber groups of a plurality of fibers, and wherein the three or more annular fiber groups comprises at least: a first group of fibers arranged in an annular array along the circumference thereof and extending longitudinally therein, a second group of fibers being disposed radially outside of the first group fibers and extending in a longitudinal direction of the tubular body and third group of fibers being disposed radially inside of the first group of fibers and extending in the longitudinal direction of the tubular body therein.