| 摘要 |
811,265. Road-vehicle undercarriages. GENERAL MOTORS CORPORATION. July 12, 1957 [Aug. 24, 1956], No. 22141 /57. Classes 108(2) and 108(3) A height control system operable independently on each wheel of a vehicle comprises air springs for. each wheel each controlled by a valve for the supply of air to or from the spring the rate of flow of air being controlled by a master valve responsive to said flow. The system tends to keep the height constant under changes of load and during stopping, starting and cornering and the master valve prevents too rapid changes or hunting. A springs 25, 27, 31 each have a piston 58 connected by levers 44, 46 to a valve assembly 30 while the left front spring 29 has its pressure chamber interconnected with that of the right front spring 31 through a valve assembly 61. Each valve assembly 30 has inlet and exhaust valves 32, 34 connected by pressure and exhaust lines 40, 42 through a master valve assembly 66 to high and low pressure tanks 22, 24 controlled by a compressor 10 driven by the engine. A plate 52 in each valve assembly 30 is attached to a lever 44 and on compression of the spring opens the inlet valve 32 while of expansion of the spring opens the exhaust valve 34. In operation upon compression of a spring its piston 58 opens its inlet valve 32 to admit air from the high pressure line 40 to restore the original height of the spring. The air in the line 40 is drawn from the high pressure tank 22 through passages 90, orifice 72 and passage 92 in the master valve, and a line 40a. The passage 90 has a restriction 88 the flow of air through which causes a resiliently mounted plunger 70 to close an orifice 74 so that any air to be drawn from the low pressure line 42 has to pass through a passage 112 having a greater restriction 114. The master valve thus prevents rapid simultaneous supply and exhaust movements of air so that levelling proceeds positively without any valve hunting. On cornering or starting or stopping one pair of springs is subject to expansion and one pair to compression and the attempted flow of air to and from the springs will close both orifices 72, 74 thus restricting any flow so that there is little change of height after the normal ride position has been restored. Omission of a valve assembly 30 for the spring 29 is compensated for by the restrictions 62a, 62b in the valve assembly 61.
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