GB933358A - Improvements in or relating to hydro-pneumatic suspension units - Google Patents

Abstract

933,358. Hydro-pneumatic shock-absorbers; levelling. ARMSTRONG PATENTS CO. Ltd. March 6, 1962 [March 8, 1961], No. 8450/61. Classes 108(2) and 108(3). In a self-levelling hydro-pneumatic suspension unit, comprising a piston 12 which works in a cylinder 10 and has a hollow piston rod 14 to provide a reservoir space 56 and a co-axial outer cylinder assembly 18, 20 divided by a collar 16 into two compartments 22, 24 separated respectively, by elastic diaphragms 26, 32, into inner hydraulic chambers 28, 36 and outer pneumatic chambers 30, 38 respectively, as the piston 12 is reciprocated in the cylinder 10 hydraulic fluid is pumped by the relative movement between the piston 12 and a plunger 44 from the reservoir 56 through valves 58, 62, a bore 46 in the plunger 44, and openings 54 in a valve plate 50 and into the space in the cylinder 10 to cause the mean position of the piston 12 to be displaced out of the cylinder 10. Displacement of the piston 12 continues until it reaches a position where a shoulder 80 on the plunger 44 bears on a ball 78 which, through a rod 76, unseats the ball 70 of a relief valve 64, the piston 12 being maintained in a mean position corresponding to the point where the ball 78 meets the shoulder 80. The relief valve 64 controls a passage 66, 68 which connects the high pressure cylinder space with the hydraulic chamber 36 the latter having a blow-off valve 82 leading to the reservoir 56. The valve 58 is located in a passage leading from a piston bore 60 which receives the plunger 44 to the reservoir 56 the valve 62 being accommodated in the bore 46 of the plunger 44 which is secured by a locknut 48 on a screw-plug 40 which, except for the apertures 42, closes the cylinder the apertures 42 which are controlled by the spring-loaded valve plate 50, providing communication between the hydraulic chamber 28 and the cylinder space. The outer cylinder assembly 18, 20 comprises cylinders which are screwed at their adjacent ends to the collar 16 the cylinder 18 having a closed rounded end and the cylinder 20 being closed by a ring 34, which also provides a bearing for the piston rod 14. The diaphragm 32 is clamped at one end between the collar 16 and the sleeve 20 and at the other end between the latter and the ring 34 the free end of the diaphragm 26 being clamped between the collar 16 and the cylinder 18. For mountings which require a maximum extension longer than that which the integral reservoir 56 can accommodate the cylinder 10 is made longer to extend the combined lengths of the outer sleeves 18, 20 and the hydraulic chamber 36 is provided with an external, instead of an internal, blow-off valve which leads to an external reservoir connected by a line to the reservoir 56. This arrangement allows a number of suspension units to be operated from a common external reservoir, if desired.