Patent ID: 9162860
Filing Date: 2015-10-20
Classification: B66F,F15B

Abstract:
1. A hydraulic cylinder that performs an extension operation using a pressurized working fluid led into a driving pressure chamber from an external fluid pressure source, comprising: a tubular cylinder tube; a piston that defines the driving pressure chamber and a cushion pressure chamber within the cylinder tube; a piston rod coupled to the piston; an air chamber defined inside the hollow piston rod; an orifice that leads a working fluid in the cushion pressure chamber into the air chamber when the cushion pressure chamber contracts during the extension operation; a check valve that returns a working fluid in the air chamber to the driving pressure chamber when a differential pressure between the air chamber and the driving pressure chamber rises to or above a predetermined value; a valve housing that houses the check valve, and a cylindrical return pipe that stands upright in the valve housing, the return pipe having an outside diameter that is smaller than an outside diameter of the valve housing, the cylinder return pipe affixed to the valve housing, wherein a throttle gap is defined between an inner peripheral surface of the piston rod and an outer peripheral surface of the valve housing that is disposed to face an open end of the orifice, the throttle gap being formed so as to extend in a perpendicular direction from the outer peripheral surface of the valve housing relative to a central axis of the cylinder tube, and a working fluid ejected from the orifice during the extension operation flows into the air chamber through the throttle gap.