1、中文 3000 单词 ,2000 单词， 1 万英文字符 本文来自于 http:/ The conventional hydraulically-assisted power steering used in most cars is soon to be replaced with electric power steering. Already, many manufacturers are using electronically controlled hydraulic systems, while some car manufacturers have recently introd
2、uced purely electric systems to their vehicles. In addition to reducing engine loads, full electric power steering allows steering responsiveness to be automatically varied depending on speed, road conditions - and even the drivers ability! Traditional Hydraulic Power-Assisted Steering Hydraulic Pow
3、er Assisted Steering has been used in automotive applications for about 50 years. The systems use an engine-driven hydraulic pump, a control valve, steering cylinder and connecting hydraulic hoses. The pump is usually of a vane design with an integrated internal bypass. It is sized so that - even at
4、 idle rpm - it delivers enough oil flow to provide a suitable degree of power assistance. The control valve uses a flexible torque-measuring device (such as a torsion bar, spiral spring or leaf spring) to convert the steering torque into a small control movement. This movement is transferred to a va
5、lve that regulates fluid flow to the power assistance mechanism. In rack and pinion steering, a double-ended hydraulic ram mounted parallel to the rack (within the rack assembly) is used, while recirculating ball systems incorporate the mechanism into the steering box. Note that in the Nissan system shown here, the fluid reservoir is incorporated into the pump. A major problem with simple conventional hydraulic steering systems is that the assistance level is not reduced at high speeds, giving a lack of steering feel. Amer
