GB810644A - Improved height control system for motor vehicle air suspension - Google Patents

Abstract

810,644. Road vehicle spring suspension systems; dashpots. GENERAL MOTORS CORPORATION. May 28, 1957 [June 18, 1956; Sept. 17, 1956; Sept. 21, 1956], No. 16880/57. Classes 108(2) and 108(3) A height control system for a motor vehicle air suspension comprising first fluid control valve means to control flow of fluid to and from the air springs responsive to height has a second fluid control valve means which in one position affords a restricted flow of fluid to and from the first fluid control valve means for slow height correction and in a second position affords relatively unrestricted flow of fluid to and from the first fluid control valve means for rapid height correction. Front air springs 11, 12, Fig. 1, are controlled by control valve 42 which is operated by links 50, 51 to maintain the chassis at a constant height. A combined check and resistance valve 85 is disposed between control valve 42 and front air springs 11, 12 to provide a free flow of air to the springs from the control valve but a restricted flow of air from the springs, thus preventing rapid transfer of air from one spring to the other when the vehicle negotiates a bend. Rear air springs 13, 14 are controlled by control valves 40, 41. All control valves are of identical construction. Housing 52, Fig. 5, contains inlet valve 53 and exhaust valve 54 operated by platform 58, and a pair of check valves 64, 65. Valve 64 permits air under pressure to flow through inlet port 66 into inlet passage 55, and valve 65 permits free flow of air from exhaust passage 57 into exhaust port 68. Rotation of lever 50, Fig. 2, operates valves 53, 54 through lever arm 40<SP>1</SP>, resiliently connected by torsion spring 50<SP>1</SP> to arm 45 which carries platform 58, Figs. 5. Movement of arm 45 is restricted by a limit stop and its oscillations are damped by a rotary damper 70<SP>1</SP>, Fig. 2, consisting of a metal plate 72<SP>1</SP> which is rotated by pin 71<SP>1</SP> about pivot pin 83<SP>1</SP> in the chamber defined by recess 73<SP>1</SP> and cover wall 74<SP>1</SP>. Damping action is provided by shear of a viscous liquid which is substantially unaffected by temperature chainges, e.g. a dimethyl silicone fluid. The fluid is retained by seals 78<SP>1</SP>, 81<SP>1</SP>. Fluid flow control valve 80, Fig. 1, has solenoid-actuated slide valve elements 100, 101, having passages 102, 103 which align with exhaust conduit 79 and inlet conduit 73 when solenoids 104, 105 respectively are energized. With the solenoids de-energized conduits 79, 73 are closed. Solenoids 104, 105 are energized by relay 111 when ignition switch 112 is closed, thus, closing the ignition switch permits a full flow of fluid through the valves. Fluid flow control valve 75 has solenoid actuated slide valve elements 115, 116 having full flow fluid passages 117, 118, and resistance flow passages 119, 120 respectively. Elements 115, 116 are moved by solenoids 121, 122 from the normal position shown to full flow position. Energization of relay 125 by closing door actuated switch 126 causes energization of solenoids 121, 122. Thus, when a door is opened and the load on the springs chamged, a rapid flow of air is permitted to adjust the chassis height, this occurs even with the ignition switch open since relay 111 bridges contacts 130, 131 and provides a path for energization of solenoids 104, 105. With the doors closed and the ignition switch closed changes in height can only occur slowly as the resistance passages are aligned with the conduits. Check valves 65 in control valves 40, 41, which control rear springs 13, 14, prevent transfer of air between springs 13, 14, when a reduction in pressure is necessary in both springs simultantously, e.g. when the vehicle brakes are applied. There is a tendency fnr this transfer of air to occur due to the resistance passage 120 of valve 75 restricting the exhaust conduit and preventing the free flow of air to the atmosphere.