GB812395A - Improvements in or relating to suspension systems for motor vehicles - Google Patents

Abstract

812,395. Pneumatic shock absorbers. DEVILLERS, R. July 25,1956, No. 23000/56. Class 108(3) A motor vehicle suspension system includes a pneumatic telescopic suspension and shock damping device which comprises an elastic suspension member 38 precompressed to a value greater than the minimum static load of the vehicle, in series with a suspension and damping system comprising at least two separate damping stages in which damping is effected by throttling the passage of a gas which is under pressure. As shown, the spring 38 comprises two concentrically disposed coil springs 37, 38, acting between an abutment rigid with a piston rod 25, and an abutment 13, rigid with the lower end of a tubular member 11 which is slidable with respect to a rod 10 rigid with a main cylinder 1 of the device. The upper abutment of the springs 37, 38, is rigid with a cylinder 40, which by virtue of a seal ring 39 and a spacer ring 41, functions as a piston within the cylinder 42. Damping results from restricted air flow, resulting from relative movement between the sleeve 11 and the rod 10, and between the abutment 13 and the wall of the cylinder 40. There is a one-way valve at the upper end of the sleeve 11. Alternatively, the sleeve 11 may be closed at its top and the one-way valve may be formed in the plug 48 closing the upper end of the rod 10. The latter may be solid however, and may be of conical form so as to result in a damping action which progressively varies. The springs 37, 38, may be replaced by the action of pneumatic pressure which may be charged via a valve 20 in the piston rod 25. In this case, a seal ring is provided between the foot of the sleeve 11 and the inner wall of the cylinder 40. The sealing ring may however be replaced by machined surfaces if the air connection 20 is coupled to a source of external air pressure. The spacer'ring 41 may be replaced by a packing ring. A one-way valve may be mounted at the base of the cylinder 40 in order to promote the transfer of air between the abutment 13 and the annular head 14 at the base of the cylinder 2. The plug 48 in the rod 10 may be of rubber. Sound deadening is promoted by the provision of suitable material 45 for the mounting of the rod 10, and a disc 49 resting on the head 14 of the cylinder 2. The pressure in the main cylinder 42 may also be maintained by a connection via a reducing valve 9 to a source of external pressure. A valve may be provided in the upper head 42a of the cylinder 42 to enable the space above the seal ring 39 to be charged with a counter-acting pneumatic pressure. This may be effected by allowing this space to be open to atmospheric-pressure when the shock absorber is fully compressed.