Patent GB-890089-A (GB)
Title: Improvements in hydropneumatic vehicle suspensions
IPC: B60G21/06
Filed: 1960-05-10
Abstract: 890,089. Hydropneumatic vehicle suspensions. VOLVO A.B. May 10, 1960 [May 13, 1959], No. 16529/60. Class 108(2). A hydropneumatic vehicle suspension comprises telescopic elements pivotally inserted between the sprung and unsprung parts 1, 4 of the vehicle and each consisting of a differential area piston 6, 8 movable in a cylinder 5, 7 filled with pressure liquid and further comprises pressure containers 16, 23 each having a space 15, 22 for pressure liquid separated by an elastic diaphragm 17, 24 from a space 18, 25 for a compressed gas, the larger space 9 in the cylinder 5 communicating through a conduit 20 with the space 22 and the smaller space 12 in the cylinder 7 while the larger space 11 of the latter cylinder communicates through a conduit 20 with the space 15 and the smaller space 10 in the cylinder 5. Levelling devices 26 actuated by suspension arms 3 connect the conduits 14 and 20, respectively, either with a conduit 27 for a high pressure liquid or with a return conduit 28. Shut-off valves 29, 31, 35 and 36 enable the spaces 9 or 11 to be connected with the conduit 28. Damping devices 30, 32 are also provided in the conduits 14, 20. If both wheels 1 are forced upwards, the space 9 is reduced and the space 12 increased, the difference between the changes in volume flowing to the container 16 to compress the gas in the space 18. During rolling in which the right hand element contracts and the left hand element expands spaces 9 and 12 increase while spaces 10 and 11 decrease resulting in a liquid flow into the space 22 and a high compression of the gas in the space 25. Consequently the rolling action is more stiffly sprung. If only the right hand element is subjected to contraction. liquid from space 11 compresses the gas 25 while the increase in space 12 causes the gas 18 to expand providing a spring rate between the values for rolling and symmetric springing movements. The telescopic units on the front and rear axles of a vehicle may be interconnected to provide a resistance to pitching movement which is either the same as that for rolling movement or between the values for rolling and parallel movement. The invention may be applied to a tanden axle bogie by providing a pair of telescopic units on each axle and connecting the corresponding spaces of the units on the separate axles together. Such an arrangement may also be combined with telescopic units on another bogie or on a single axle to provide resistance to pitching. Fig. 9 shows a telescopic unit in which the cylinder 53 has a bottom plate 55 bolted to a yoke 56 having two journals 57 pivotally mounted in the arm 3 while the piston 58 has a tube 59 secured to a head 60 having two journals 61 pivotally mounted in the chassis 62 of the vehicle. The space 9 of the unit communicates with the conduit 14 through a space 66 the right hand journal 61 and a hose connection 69. A similar connection 68 for the conduit 20 communicates through a space 65 and openings 67 with the space 10. A tube 71 having bores 72, a non-return valve 73 and apertures 74 and the openings 67 co-operate with the space 66 and a bushing 54, respectively, provide a buffer action at the ends of the stroke. A modified connection between the unit and its conduits, which may be fixed tubes in the chassis, is described.