Patent GB-1132778-A (GB)
Title: Improvements in or relating to spring suspension for vehicles
IPC: B60G15/06
Filed: 1966-04-15
Abstract: 1,132,778. Self-levelling hydro-pneumatic shock-absorber. H. TEVES, E. A. TEVES, and M. TAUSEND, [trading as ALFRED TEVES MASCHINENUND ARMATURENFABRIK K.G.]. 15 April, 1966 [18 Sept., 1965], No. 16548/66. Heading F2S. A spring suspension for vehicles, more particularly motor vehicles, comprises a suspension spring 2 and a unitary hydro-pneumatic shockabsorber 5, 15 disposed in the suspension spring and having a pump system, a level-regulating system and an hydraulic reservoir 40, a damper control being disposed in the level regulating system. As shown, a valved piston 5 with a hollow rod 4 works in a cylinder 15 having a widened upper end which co-operates with a stepped cylinder 17 which, through a swing- able cup, 20, supports the upper end of the spring 2, and which bounds a spring-stressing chamber 16 hermetically sealed by gaskets 18, 19, the lower end of the spring 2 being carried by a protective tube 3. A pre-stressed coil spring 12, accommodated in the hollow rod 4, has its upper end connected to a retaining bush 14 and its lower end rigidly connected to a regulating rod 13. The widened upper end of the cylinder 15 receives the level regulating-system, the main elements of which consist of a slide valve 21, a control casing 22, and a valve 23. A disc piston 24, connected to the slide valve 21, co-operates with the end face of the casing 22 to bound a damper chamber 25 having a compression spring 27. A perforated disc 29, disposed in the control valve 21, forms a lower abutment for a spring 30 the other end of which abuts a second perforated disc 31 on a valve needle 32. When the mean level of the vehicle has been reached, the control rod 13 disengages from the perforated disc 29, liquid being supplied to the chamber 25 as a control aperture 50 in the valve 21 registers with a control passage (52) having a non-return valve 61 so that the valve 21 can drop, substantially without interruption, and a groove 43, leading to a compression valve 42 which controls flow of liquid from the working space 41 of the cylinder 15 to the reservoir 40, begins to uncover. When the groove 43 is fully open, so that liquid is displaced by way of valves 42, 38 to and from the space 41 to the reservoir 40 and not pumped to the spring stressing chamber 16 through a non- return valve 66, the control aperture 50 registers with a control passage 53 which is connected to the chamber 25 through a reversed non-return valve 62 so that further downward movement of the slide valve 21 is strongly decelerated, the chamber 25 then only being fillable through a very small throttle in a disc (59), Fig. 3, not shown, which disc (59) is located in a parallel passage connecting the valve chamber 66 in the valve 21 to the chamber 25. In this way the slide valve 21 is prevented from descending further from this standby position since the regulating rod 13 follows the movement of the vehicle wheel, and can, in a single upward stroke, return the slide valve 21, which may have slowly dropped, to the standby position. When the vehicle is stationary and unloaded the spring 2 expands and the regulating rod 13, having no pulsations, allows the valve 21 to drop under the action of the spring 26, the throttle in the disc (59) controlling the rate of drop. Shortly before the disc piston 24 abuts a stop 63 a collar 64 on the valve entrains the second perforated disc 31 so that the valve needle 32 is disengaged and opens passages 36, 37 and 33-35 so that liquid from the spring stressing chamber 16 can pass to the reservoir 40, the level of the vehicle being reduced until the regulating rod 13 again abuts the perforated disc 29 and moves the valve 21 upwards so that, through the spring 30, the needle valve 32 closes the passages 33-35. When the vehicle starts to move, its first oscillation acts on the rod 13 to move the valve 21 upwards, liquid being displaced from the chamber 25 relatively easily through the reversed non-return valve 62, until the top edge of the valve 21 is at the lower edge of the groove 43. Heavily loading the vehicle causes the valve 21 to rise and close the groove 43, liquid then being pumped by the piston 5 through the chambers 41, 60 and the one way valve 66 to the spring stressing chamber 16 to stress the spring 2 and restore the vehicle body to its desired level. Pumping continues until the rod 13 no longer bears on the disc 29 and the valve 21 sinks to uncover the groove 43, the damper chamber 25 in this position communicating with the chamber 65 through the apertured disc (66) which has filters (58, 60) and also through the control aperture 50 which registers with a passage (51, 52), Fig. 3, not shown, having a throttle in a disc 55 which throttle is smaller than that in the disc (66). The reservoir has a filter 47 which acts as a non-return valve and a filling cap 49.