Improvements in or relating to hydraulic dampers especially for vehicle suspensions

摘要

771,299. Hydraulic shock absorbers. GRANET, C., ROLAND, G., and CRAUC, R. Sept. 21, 1955 [Sept. 22, 1954; Aug. 2, 1955], No. 27002/55. Class 108(3). A hydraulic damper comprises a crank 41 rigid with a shaft 42 and engaging with doubleheaded pistons 31, 32, slidable in a cylinder 21 above which is situated a reservoir 24, flow of liquid to which, from working chambers 55, 55SP1/SP, defined by the piston heads 31, 32, and the closed ends 26, 27, of the cylinder, is controlled by non-return valves 48 (one valve only, shown in Fig. 2) having variable spring-loading controlled by a cam 56 rigid with the shaft 42. The arrangement is such that as the crank 41 is displaced from a central position (shown) the spring-loading of the valve 48 is progressivelyincreased. As shown, the cam 56 comprises a pair of diametrically opposed concave recesses 61 (one recess only shown in Fig. 2) formed in a ring 56 secured to a side face of the crank 41. Each valve 48 is slidable in a bore 47 formed in the body of the damper and closed on its outside by a screw-threaded plug 50. The latter is formed with ports 51, 52, which comprise a seating for the valve 48 and connect with a passage 54 leading to the chamber 55. A further passage 62SP1/SP leads from the valve 48 to the reservoir 24. Each piston has a non-return valve 37 permitting flow from the reservoir 24 to the cylinder. The lift of the valve 37 may be limited by a member 64. In a modification, Fig. 1 (not shown), the concave recesses forming the cam portions 61 are replaced by flats. In opreation, as applied to the suspension of a vehicle, the position shown in Fig. 2 corresponds to normal static loading of the vehicle. Under a heavier static loading due to the action of the cam surface 61 on the spring loading of the valve 48, the resistance to deflection of the damper is increased.