Patent ID: 8807932

Claim:
A hydraulic power unit comprising: an inner tube comprising a hollow portion, wherein a fluid inlet through which a fluid flows in and a fluid outlet through which a fluid is discharged are formed on a surface of the inner tube, and a front end portion of the inner tube is closed; a vibration tube comprising a hollow portion, an elastic tube layer formed of a flexible material, and a metal tube layer contacting the elastic tuber layer and formed of a metal having elasticity, wherein a plurality of slits extended in a length direction of the vibration tube are formed in the metal tube layer along a circumference of the metal tube layer, and the hollow portion of the vibration tube is connected to the hollow portion of the inner tube to form a hydraulic chamber, and a back portion of the vibration tube is closed; a back end protrusion disposed to contact a back end of the vibration tube, wherein the back end protrusion is disposed so that the back end of the vibration tube maintains a form that protrudes into the hydraulic chamber; an oscillator that is fixed to the back end protrusion and is disposed such that the back end protrusion is deformed in inward and outward directions of the hydraulic chamber so as to increase or decrease a pressure of a fluid in the hollow portion formed by the inner tube; an outer check member that is formed of an elastic material and is disposed to be adhered to a V-shaped groove of the fluid outlet formed in an outer wall of the inner tube; and an inner check ring that is formed of an elastic material and is disposed to be adhered to a V-shaped groove of the fluid inlet formed in an inner wall of the inner tube so as to close the fluid inlet of the inner tube 380 inside the hollow portion of the inner tube.