Patent GB-1058795-A (GB)
Title: Hydropneumatic spring suspension element
IPC: B60G17/044
Filed: 1963-12-20
Abstract: 1,058,795. Hydropneumatic spring suspension device. FICHTEL & SACHS A.G. Dec. 20, 1963 [Dec. 24, 1962], No. 50385/63. Heading F2S. A hydropneumatic spring suspension device comprises a working plunger 10 in a working chamber filled with a pressure liquid, a resilient gaseous compression space 2 under load from the pressure liquid, a pressure liquid reservoir 8 and a pump which is automatically connected between the reservoir 8 and the working chamber in dependence on the position of the working plunger 10 in relation to the work chamber, the pump being actuated by the relative fluctuations of the plunger 10 and working chamber. A liquid return flow path is provided between the working chamber and the reservoir and is also connected in dependence on the position of the plunger 10 in relation to the working chamber. The pump includes the plunger 10, an extension 13 of the plunger, the extension being of a different diameter than that of the plunger, a dividing disc 3 in the working chamber having a passage which is normally open but is closed by the extension 13 in a position of the plunger inwardly with respect to its normal position, a check valve between two compartments 4, 44 formed by the dividing disc which valve opens in the direction of that one of the compartments 44 which communicates with the compression space 2 and a further check valve 20, 21 between the pressure liquid reservoir and the other of the compartments 4 and which opens in the direction of the other of the compartments. In the construction shown the reservoir 8 is concentric with the working chamber and communicates through passages 18 with a further chamber 16 and through passages 20 with the working chamber. The passages 20 are covered with an elastic diaphragm 21. When the extension 13 enters the passage 6 in the dividing disc 3 it co-operates with a sealing sleeve 57 to act as the check valve between the compartments. As the plunger 10 has a smaller displacement than a similar length of the extension 13 which is of greater diameter, the loss of volume in the working chamber due to the movement of the extension 13 through the disc 3 causes hydraulic fluid to be drawn through the passages 20 from the reservoir. In the normal working of the shock absorber the extension 13 reciprocates in the sealing sleeve 57 and the pumping action produced by this reciprocation extends the shock absorber. Should the shock absorber load be decreased and the extension become too great a slot 23 cut in the plunger 10 bridges the closure plate 14 to allow pressurized fluid to flow back to the reservoir 8, the reservoir being under a pneumatic pressure. The extension may have a diameter less than that of the piston-rod, the dividing disc end of the working chamber then communicating with the reservoir 8 through passages situated adjacent the dividing disc and capillary tubes which depend downwardly into the hydraulic fluid in the reservoir (Fig. 5, not shown). In modifications the extension passes through a passage 6 in the dividing disc 3 which is not provided with the sealing sleeve 57, one way ball or flap valves being formed in the dividing disc (Fig. 3, not shown) or a ball valve is provided in a chamber in the extension, the chamber being connected across the damping piston by channels in the extension and the piston-rod (Fig. 4, not shown).