GB641251A - Improvements in hydraulic shock absorbers for the suspension of vehicles - Google Patents

Abstract

641,251. Hydraulic shock absorbers. HELBIG, M. July 16, 1947, No. 18912. Addition to 627,508. [A Specification was laid open to inspection under Sect. 91 of the Acts, Nov. 6, 1947] [Class 108(iii)] The shock absorber claimed in the parent Specification is modified by the seat for each escape valve being formed at the end of an axially-extending cylindrical sleeve which is fixed in the piston and on which the associated admission valve is arranged to slide, the sleeve also serving as a guide for one end of the stem of the escape valve the other end of the stem being formed with a piston for a hydraulic servo-motor controlling the tension of the loading spring of the escape valve. As shown, each end of the piston has lightly loaded escape valves 24, 25 controlling flow on recoil to the respective cylinder spaces 9, 10 via ports (not shown) connected with a reservoir 11 and valve chambers 13, 16. Flow from the spaces 9, 10 to the reservoir on compression takes place through respective escape valves 12, 15 which are loaded by springs 22, 23. The abutment of the spring 22 at its end remote from the valve is formed by a plunger 20 carried by a stem 52 on which the valve 12 is slidable. The plunger 20 is slidably mounted in a recess 36 in the piston which is connected by a passage 62 with the space 9. A restriction is formed in the passage 62 by a screw 70 adjustable by means of a screwdriver inserted through a respective aperture 68 in the shock absorber casing. The other end of the stem 52 is slidable in a plug 78 mounted in the cylinder. A member 46 having grooves 29, 30 adjacent each cylinder chamber 9, 10 has limited sliding movement relative to the cylinder and is disposed in an axial groove formed in the periphery of the cylinder. The ends of the cylinder are closed by members 72 73 which are formed with recesses within which the respective ends of the member 46 slides with clearance. Passages 60, 61 are formed in the wall at each end of the piston and connect the respective valve chambers 13, 16 with the cylinder chambers 9, 10 via the respective groove 29 or 30, when the piston is substantially in its central position. Operation. On movement to the right from a central position liquid at first passes freely from the right-hand cylinder chamber 10 via groove 30, passage 61, a passage (not shown) connecting the space 16 with the reservoir space 11, and valve 24 to the left-hand cylinder chamber 9. Further movement of the piston isolates the groove 30 from the chamber 10 and pressure transmitted through the passage 63 acts on the piston 21 to progressively load the valve spring 23 of the escape valve 15. On movement to the left, liquid cannot escape from the chamber 9 via the groove 29 since the passage 60 is closed by the member 46. Damping due to flow through the escape valve 12 is progressively increased due to pressure acting through the passage 62, but rapidly decreases to zero near the central position when the passage 60 registers with the groove 29.