GB652697A - Improvements in or relating to hydraulic shock absorbers - Google Patents

Abstract

652,697. Hydraulic shock absorbers. SOC. D'INVENTIONS AERONAUTIQUES ET MECANIQUES S.I.A.M. Feb. 20, 1948, No. 5150. Convention date, Feb. 22, 1947. [Class 108(iii)] In a shock absorber of the type in which a piston separates, inside the cylinder in which it moves, two terminal chambers filled with liquid which flows from one chamber to the other during movement of the piston through narrow orifices and valves, the piston is formed with two or more longitudinal ducts for the passage of the liquid and one-way flap valves are mounted upon the working faces of the piston for controlling flow through the ducts each flap valve being of the spring seal type comprising a blade of spring steel or the like seated over the mouth of the duct, the blade being secured to the working face of the piston at one end only to permit it to flex away from its seat to a progressively increasing extent as the pressure in the duct behind it increases. In the arrangement (shown) a piston 1, which is slidable in a liquid filled cylinder 2, is provided with two grooves 6a and 6b which communicate with terminal chambers 7a and 7b in the cylinder 2. Spring steel flap valves 8a and 8b are mounted on opposite faces of the piston at one of the open ends of each of the grooves 6a and 6b. The valves are provided with stroke limiting devices 9a and 9b. In a modification (Figs. 3, 4 and 5, not shown), each groove extends to one face only of the piston, the other end of each groove communicating with the corresponding second face of the piston through a calibrated orifice. The flow of liquid through the grooves may be restricted by screws which are manually adjustable externally of the cylinder, through which they project into the grooves. In a further modification (Fig. 7, not shown), the piston 1 comprises a central liquid reservoir chamber which communicates with the chamber 7a and 7b through respective grooves and orifices. Each orifice is controlled by a respective flap valve which is also fitted with a stroke limiting device. In all arrangements, the grooves 6a, 6b, the cross-section of each of which may vary along its length, may be replaced by ducts which extend through the body of the piston and which terminate in orifices controlled by flexible flap valves. Also the flap valves 8a and 8b may be inclined slightly to the face of the piston by means of wedges 17 (Fig. 2).