GB929759A - Improvements in or relating to hydraulic damper units for vehicle suspensions - Google Patents

Abstract

929,759. Levelling. ARMSTRONG PATENTS CO. Ltd. Sept. 29, 1961 [Nov. 17, 1960], No. 39458/60. Classes 108(2) and 108(3). A hydraulic vibration damper is combined with a pump device for a levelling system. The unit comprises a housing 10 in which is provided two pairs of cylinders 14 and 16, the cylinders 14 each housing a piston 18 having a non-return valve 20 permitting the flow of fluid from above to below the piston, the space above the pistons comprising a fluid reservoir and housing a shaft 22 having a portion extending outside the housing upon which is fast an arm 24 connected to a sprung portion of the vehicle, the housing 10 being connected to an unsprung portion. A rocker shaft 28 is secured to shaft 22 and is connected to the pistons 18 by rods 26. The cylinders 14 are connected by passages 30 to a valve chamber comprising a valve 44 urged on to its seat by a spring 46 and a valve 52 urged on to its seat on a bore, (not shown) passing through the valve member 44, by a spring 54. The cylinders 14 and valves 42 and 44 thus form a vibration damping unit, the valves 42 and 44 permitting throttled flow from one cylinder to the other. The cylinders 16, incorporating sleeve members 56 each having a flange 60, house plungers 62 acted upon by a cam member 72. Each plunger comprises a non-return valve 78 allowing liquid to flow downwardly on an upstroke of the plunger and a non-return valve 82 permitting flow of liquid on a downstroke of the plunger into a chamber 88 connected via a pipe 92 to a ram and cylinder connected between the sprung and unsprung parts of the vehicle and incorporating a control device to maintain the vehicle at a predetermined height. Such control means may be incorporated in the vibration damper-pump unit, taking the form of a by-pass passage 96 leading from the chamber 88 back to the reservoir and controlled by a valve 98 having a stem 99 co-operating with a recessed cam surface 73 in the cam member 72 and being such that at the required vehicle height, the valve 98 is just at the point of closing, below that height, the valve is closed so that all the liquid pumped into the chamber 88 passes to the levelling ram, and above that height, the valve is open so discharging the fluid back to the reservoir 12, which may be complete per se or may be connected through a pipe 94 to a further reservoir. The plungers 62 may be replaced by pistons connected by rods to a crank arm in which the cam surface 73 is incorporated and the pistons 18 may be replaced by plungers, and the pump unit may alternatively comprise a single cylinder. Specification 867,514 is referred to.