GB460985A - Improved shock absorber - Google Patents

Abstract

460,985. Shock-absorbers. EBSWORTH, R. H. April 30, 1935, No. 12880. Void. Convention date, March 13. [Class 108 (iii)] In a fluid pressure shockabsorber of the oscillatory or rotary type, the resistance to the circulation of fluid is regulated by a valve element which is positioned by a sustained force but is not moved appreciably by forces due to shocks of short duration. The resistance to the fluid circulation is regulated automatically according to the supported load so that the initial resistance to the rebound or return movement increases with the load, whilst the resistance to the compression movement may also vary with the load or may be substantially constant. In the arrangement shown in Fig. 1, the relative movement between the axle and chassis of a motor vehicle is transmitted by a lever 22 to an arm 24, the free end of which engages a piston 19 located between springs 21 in a valve member 15 which can move axially in a casing 12. Spaces 13a, 13b between the valve member 15 and the ends of the casing 12 communicate with a chamber 14 through openings 16a, 16b controlled by adjustable needle-valves 17, 18, the former incorporating a relatively strong spring. The movement of the piston under a steady load, such as that due to the weight carried by the vehicle, is communicated gradually to the valve member 15 which remains approximately stationary under sudden shocks of normal magnitude. The valve member 15 is formed with an opening 27 which is associated with an aperture 26 in the casing 12 and, at its opposite end, is provided with an elongated opening 29 in register with an aperture 28 in the casing. The opening 20, Fig. 5, is tapered, so that the initial resistance to the rebound movement is dependent upon the position of the valve element, i.e., the load carried by the vehicle. In addition, the piston is provided with a channel 32 having an opening in communication with an aperture 34 through an elongated opening 33, preferably of uniform width, and at its opposite end with a channel 36 in register with a tapered slot 35, and an aperture 37 leading to the chamber 14. The slot 36, Fig. 9, is shaped to provide increased resistance at the beginning and end of the rebound movement, the initial resistance being dependent on the extent of the preceding compression movement, i.e. the motion of the piston 19 relative to the valve element. A port 39 in the wall of the chamber 12, normally closed by a spring pressed valve, registers with an elongated slot 38 in the valve casing and is opened under a heavy shock. If the shock is excessive, the spring-loaded valve 17 also opens and the valve element moves to the right, thus decreasing the effective size of the aperture 29 and increasing the initial resistance to the rebound. The casing is provided with a filler opening 41. The elongated openings 33, 36 may be formed in the piston 19. An analogous arrangement, using a rotary piston, is described in connection with Fig. 2 (not shown). The device may be arranged to operate as a one-way shock-absorber, and the valve member 15 may be actuated independently of the fluid-circulating piston 19.