GB818604A - Improved air spring - Google Patents

Abstract

818,604. Pneumatic springs. GENERAL TIRE & RUBBER CO. March 15, 1957 [Dec. 10, 1956], No. 8682/57. Class 108(3) In an air spring, for use between the frame and undercarriage of a vehicle, which has at least one piston member mounted on either the frame or undercarriage, a bellows of rubber-like material sealed to the edge portion of the face of the piston member to define therewith an airtight main air chamber, constraining means surrounding the bellows which is substantially coextensive in length with the bellows, and an auxiliary air chamber connected to the main air chamber by an orifice. the piston member is characterized in that its side-walls are of greater lateral extent than that of the face of the piston member so that the effective area of the piston member increases as the piston member approaches maximum deflection in compression. An air spring unit has top and bottom pistons 4, 5, Fig. 2, cylindrical bellows 6 of rubber or rubber-like polyurethanes, and a metal constraining band 7. The bellows is sealed against the pistons by beads 10, 11, reinforced with wires 14, 15, which fit in seats 12, 13. Constraining band 7 is held in position by groove 19 which engages ridge 20 in the bellows. An orifice 23 in face 24 of piston 4 leads from main air chamber 25 to an auxiliary air chamber 27. Sidewall portions 29, 30 of pistons 4, 5, diverge out from the face of the piston so as to increase the effective area of the piston as the spring is compressed, thus stiffening it and increasing its rate and frequency. Fig. 4 shows an embodiment with cylindrical pistons. To provide an increased effective area the thickness of the walls of hook portions 42, 43 of bellows 44, which lay up against the piston sidewalls as the spring is compressed, is increased from beads 45, 46, towards outer edges 47, 48, Fig. 5 shows a modification in which the diameters of the pistons increase in steps as at 53. Beads 61, 62, of bellows 63 are sealed to the piston faces by clamping members 64, 65. An orifice 74 in the top piston provides a connection between main air chamber 75 and auxiliary air chamber 76. An inner ring 36 holds bellows 63 in groove 37 of band 73. Fig. 7 shows a modification using a single elongated piston 77, mounted on either the frame or undercarriage, which gives a lower frequency and requires a smaller auxiliary air chamber than the foregoing springs. Fig. 9 shows a modified piston shape and bellows 120 are reinforced by inextensible fabric 121, e.g. rayon or nylon, bounded by top and bottom beads 122, 123. Air enters auxiliary chamber 126 through orifice 124. A vertical separation between inner and outer portions of the bellows, adjacent the bead 122, may be provided to allow the bellows loop to move inside the reinforcement during full compression deflection of the spring, Fig. 10, shows a modification in which the pistons and bellows are rectangular with rounded ends in cross-section. The bellows are clamped against the pistons, and bracing members 117, 118 prevent band 96 from being deformed.