Patent GB-681243-A (GB)
Title: Oleo pneumatic shock absorber
IPC: F16F9/06
Filed: 1948-03-30
Abstract: 681,243. Oleo-pneumatic shock-absorbers. LAUGAUDIN, E. March 30, 1948 [March 27, 1947], No. 8998/48. Class 108 (iii). In an oleo - pneumatic shock - absorber comprising two cylinders sliding one within the other and closed at their outer ends to form a chamber of variable volume, a central hollow rod secured to the closed end of the outer cylinder, and terminating at its free end in a piston head sliding in the inner cylinder, the hollow rod being provided with apertures near the closed end of the outer cylinder permitting a limited flow of liquid into the hollow rod, a piston with an incompletely fluid-tight valve surrounding the hollow rod and secured to the inner cylinder near its open end, a loose piston located between the closed end of the inner cylinder serving as a compression chamber for a gaseous fluid and the remainder of the shock-absorber being filled with liquid, the volume of the space between the end and side walls of the outer cylinder on the one hand, and the wall of the inner cylinder, the piston head on the hollow rod and the hollow rod itself, on the other hand, is changed when the cylinders slide one in the other, only by an amount equal to the volume of that portion of the wall of the inner cylinder that enters the space. In the arrangement shown, an outer cylinder 1 carries a hollow rod 6 which extends into an inner cylinder 2 and terminates in a hollow piston 9. A floating piston 10, preferably of resilient material, within the cylinder 2 seals a space above the piston 10 which contains compressed gas, from the rest of the shock-absorber which is filled with a liquid, such as oil. The gas may be compressed air. A partially fluid-tight valve within the hollow piston 9 comprises a ball 29 which during compression of the shock absorber, engages an orificed seating 31 and which during expansion, engages a lower part 32 having apertures which permit substantially free flow of oil through the valve. The valve may be located at the lower end of the hollow rod 6 above apertures 8 therein and may be of the type described below with reference to Fig. 5. An annular ring 13 secured to the lower end of the inner cylinder 2 and abutting an apertured annular head 11, also secured to the cylinder 2, defines a conical chamber around the hollow rod 6. A correspondingly shaped loose ring 14 is located within the chamber and a tapered packing ring 15 ensures liquid tightness between the inner and outer cylinders. In operation, compression of the gas above the piston 10 is damped by the restricted flow of liquid through the valve seating 31, while subsequent expansion of the gas is checked by the flow of liquid from the space between the piston 9 and the head 11, which flow is restricted by the ring 14. In a modification, (Fig. 3, not shown), the head 11 and ring 15 are formed in one piece. In a further modification, Fig. 4 (not shown), a member, slidable on the hollow rod 6, cooperates with an annular member secured to the lower end of the inner tube 2 to permit substantially free flow of liquid through the annular member during compression of the shockabsorber, but restricts the flow during expansion of the latter. In another arrangement, Fig. 5 (not shown), the inner and outer cylinders are spaced concentrically and the partially fluidtight ball valve comprises a spring-loaded ball which normally engages an orificed seat above the apertures at the lower end of the hollow rod. In all arrangements, fluid-tightness of the shockabsorber is ensured by a tapered packing ring between the open end of the inner cylinder and the adjacent wall of the outer cylinder. The Specification as open to inspection under Sect. 91 describes an arrangement, Fig. 6 (Cancelled), in which the inner cylinder is located wholly within the outer cylinder and is carried by a rod which extends into the latter. This subject-matter does not appear in the Specification as accepted.