GB1042593A - Improvements in hydro-suspension units for vehicles - Google Patents

Abstract

1,042,593. Self-levelling hydro-pneumatic suspension units. GIRLING Ltd. Oct. 25, 1963 [Oct. 2, 1962], No. 37246/62. Heading F2S. A self-levelling hydropneumatic suspension unit for a vehicle comprises a piston 12 which works in a cylinder 11 having a two-way valve unit 20 at its upper end leading to a pneumatic spring pressure chamber 10 and which is provided with a hollow piston-rod 13, the interior of which forms a reservoir 27 containing a flexible bag 28 filled with air or other gas. An annular space 30 around the piston-rod 13 between the piston 12 and a closure 31 for the lower end of the cylinder 11 communicates with a passage 17 in the piston 12 which accommodates two spring-loaded ball valves 18, 19 arranged in series so that the annular space can be placed in communication with the reservoir 27 on the high pressure chamber in the cylinder 11 above the piston 12. A needle 24, having a tapered free end, is fixed in the centre of the valve unit 20, and extends with a sliding fit through a bearing 26 and an axial bore 25 in the piston 12 and into a guide 29 in the piston-rod 13, the bore 25 communicating with the radial bore 32 leading to the passage 17. In operation as the unit contracts the volume of the annular space 30 increases and liquid is drawn from the reservoir 27 past the valve 18 and the passage 17. When the unit extends liquid is pumped from the annular space 30 through the passage 17 and the valve 19 into the high pressure chamber of the cylinder 11. Pumping continues until the length of the unit has increased sufficiently for the tapered end of the needle 24 to correspond with the bore 32 in the piston 12 so that a progressively increasing amount of liquid is bypassed to the reservoir 27. On further extension of the unit the tapered portion of the needle 24 clears the bearing 26 so that liquid can also flow from the high pressure cylinder chamber to the reservoir 27. The rate at which liquid is pumped into the high pressure chamber of the cylinder is progressively reduced until the bore 32 is uncovered and the extension of the unit ceases.