Patent GB-820857-A (GB)
Title: Improved fluid suspension spring
IPC: B60G21/06
Filed: 1958-01-02
Abstract: 820,857. Adjusting body height; pneumatic springs. GENERAL MOTORS CORPORATION. Jan. 2, 1958 [Jan. 18, 1957; Feb. 26, 1957], No. 164/58. Classes 108(2) and 108(3) A fluid spring 12, Fig. 8, adapted to be interposed between sprung and unsprung portions of a vehicle, comprises a fluid chamber 35, and a piston member 38 connected by a flexible diaphragm 36. A valve 72 mounted on the chamber to control flow of fluid in and out of the spring has a valve operating mechanism 100 disposed internally of the spring. The valve mechanism 100 operates the valve means to exhaust or introduce fluid from or to the spring responsive to the position of the piston member in the chamber. Piston 38, Fig. 8, moves into and out of air chamber 35 to which it is connected by rubber diaphragm 36. Four air springs are applied to a vehicle suspension system as shown diagrammatically in Fig. 1. Pump 40 forces air under pressure into high pressure reservoir 42, the pressure being regulated by controls in the pump through pipe line 43. High pressure air is delivered to springs 12, 13. 15, 16 through valve 50 and pipe line 46. Exhaust air from the springs passes to low pressure reservoir 58 via pipe line 47 and valve 50. Pump 40 draws its air supply from reservoir 58, a closed circuit being thus provided. To provide a constant ride height each spring has a level control valve controlled by a lever 100, Figs. 8, 2, which bears on top of the piston through a roller 102, spring 110 maintaining this contact. When shaft 85, Fig. 7, is rotated anti-clockwise by lever 100, ear 114 opens inlet valve 82 and allows air to be admitted to the spring until the pre-determined ride height is restored. Conversely when shaft 85 is rotated clockwise, ear 115 lifts valve 83 off the exhaust port and air is allowed to escape from the spring. Stop pin 112 engages ear 114 to prevent excessive opening of exhaust valve 83. The ride height may be increased by pushing in cable 130, one end of which is located in the vehicle cab, to move spool 131, Fig. 1, valve 50 to the right so that end 55 bears on valve 135 to lift it off seat 136 and close passage 138. Since passage 138 is closed, no high pressure air can escape from line 44 through line 57 to low pressure reservoir 58, and the direct connection of the high pressure chamber 45 to exhaust line 47 supplies check valves 125, Figs. 4, 6, with high pressure air, which passes round flexible valves 128 into the air springs through inlet valves 82. The height to which the vehicle rises is controlled by limit stops. When spool 131 is pulled to the left into its normal position, the vehicle returns to normal height since the exhaust valves will be open and an exhaust path is available through passage 138 of spool 131. Fig. 9 shows an alternative construction of air spring and levelling valve. As the piston moves up and down level 296 turns shaft 260, Figs. 9, 10, and with it two-armed lever 288, so that one or other of ears 284, 286, of lever 288, lift up the appropriate one of valves 262, 268, to admit or exhaust air to or from the spring. Arcuate slots 310 permit limited rotation of the valve body so that the ride height of the vehicle can be readily adjusted. Specifications 820,856 and 820,858 are referred to.