DIE AUSBILDUNG EINER HYDROPNEUMATISCHEN, EINSTELLBAREN FEDERUNG FUER FAHRZEUGSITZE

1308501 Resiliently mounted seats UNIVERSAL OIL PRODUCTS CO 13 July 1970 [16 July 1969] 33859/70 Heading A4U A resiliently mounted vehicle seat comprises front and rear pairs of guides 20, 26 restraining fore-and-aft and lateral movement of a seat cushion 14, which is spring-biased vertically away from a base 22 and which pivots about a point P in the area of the knee of the user, forward and rear shock absorbers 62, 66 being provided, each consisting of a piston rod 61, 67 pivoted to a seat pan 32 and a cylinder 64, 65 divided by a piston into upper and lower compartments, the area of the upper surface of the rear piston being equal to the area of the lower surface of the forward piston multiplied by the ratio of the respective distances of the pivot points of the piston rods 61, 67 on front and rear parts of the cushion from the point P, and the lower compartment of the front shock absorber being connected to the upper compartment of the rear shock absorber by a connection tube 51. The biasing spring consists of a gas tight hydraulic accumulator 50 charged with fluid and gas, preferably nitrogen and connected by a connection tube 52 to the lower compartment of the rear shock absorber, an initial precharge of gas in the accumulator transmitting pressure through the fluid in tubes 51, 52 to the shock absorbers to bias the cushion upwards. Both compartments of shock absorber 66 and the lower compartment of shock absorber 62 contain hydraulic fluid, the upper compartment of shock absorber 62 being open to atmosphere through a valve 19 and downward movement of the cushion forces down the piston of shock absorber 62, forces hydraulic fluid through tube 51 to lower the piston in shock absorber 66 and forces hydraulic fluid into the accumulator, the cushion being constrained to move counter-clockwise about the point P by pivotal connections between brackets 60 and sockets 70 on the seat pan 32 with piston rods 61, 67 and guide arms 73, which have rollers 72 movable in C-channels 70 rigid with the base 22, and pivotal connections of cylinders 64, 65 on the base. In modifications, the biasing spring is a gas, coil, tension or leaf-spring, the cylinders of the front and rear shock absorbers are connected, respectively, to the rear and front parts of the base, or the cylinders of the shock absorbers are connected to the seat pan. The maximum oscillation of the seat is controlled by a pin 138 connected by a link 140 to the seat pan and moving in a slot 136 in a plate