自动化专业毕业设计论文外文翻译电子动力转向系统的研究与设计.docx

1、自动化专业毕业设计论文外文翻译电子动力转向系统的研究与设计电气与信息学院自动化专业毕业设计（论文）外文翻译Electonic power steering system Research and Design电子动力转向系统的研究与设计Electronic power steering system What it isElectrically powered steering uses an electric motor to drive either the power steering hydraulic pump or the steering linkage directly. Th

2、e power steering function is therefore independent of engine speed, resulting in significant energy savings.How it works :Conventional power steering systems use an engine accessory belt to drive the pump, providing pressurized fluid that operates a piston in the power steering gear or actuator to a

3、ssist the driver.In electro-hydraulic steering, one electrically powered steering concept uses a high efficiency pump driven by an electric motor. Pump speed is regulated by an electric controller to vary pump pressure and flow, providing steering efforts tailored for different driving situations. T

4、he pump can be run at low speed or shut off to provide energy savings during straight ahead driving (which is most of the time in most world markets).Direct electric steering uses an electric motor attached to the steering rack via a gear mechanism (no pump or fluid). A variety of motor types and ge

5、ar drives is possible. A microprocessor controls steering dynamics and driver effort. Inputs include vehicle speed and steering, wheel torque, angular position and turning rate. Working In Detail:A steering sensor is located on the input shaft where it enters the gearbox housing. The steering sensor

6、 is actually two sensors in one: a torque sensor that converts steering torque input and its direction into voltage signals, and a rotation sensor that converts the rotation speed and direction into voltage signals. An interface circuit that shares the same housing converts the signals from the torq

7、ue sensor and rotation sensor into signals the control electronics can process.Inputs from the steering sensor are digested by a microprocessor control unit that also monitors input from the vehicles speed sensor. The sensor inputs are then compared to determine how much power assist is required acc

8、ording to a preprogrammed force map in the control units memory. The control unit then sends out the appropriate command to the power unit which then supplies the electric motor with current. The motor pushes the rack to the right or left depending on which way the voltage flows (reversing the curre

9、nt reverses the direction the motor spins). Increasing the current to the motor increases the amount of power assist.The system has three operating modes: a normal control mode in which left or right power assist is provided in response to input from the steering torque and rotation sensors inputs;

10、a return control mode which is used to assist steering return after completing a turn; and a damper control mode that changes with vehicle speed to improve road feel and dampen kickback.If the steering wheel is turned and held in the full-lock position and steering assist reaches a maximum, the cont

11、rol unit reduces current to the electric motor to prevent an overload situation that might damage the motor. The control unit is also designed to protect the motor against voltage surges from a faulty alternator or charging problem.The electronic steering control unit is capable of self-diagnosing f

12、aults by monitoring the systems inputs and outputs, and the driving current of the electric motor. If a problem occurs, the control unit turns the system off by actuating a fail-safe relay in the power unit. This eliminates all power assist, causing the system to revert back to manual steering. A da

13、sh EPS warning light is also illuminated to alert the driver. To diagnose the problem, a technician jumps the terminals on the service check connector and reads out the trouble codes. click here to see a bigger Electric power steering systems promise weight reduction, fuel savings and package flexib

14、ility, at no cost penalty.Europes high fuel prices and smaller vehicles make a fertile testbed for electric steering, a technology that promises automakers weight savings and fuel economy gains. And in a short time, electric steering will make it to the U.S., too. Its just just a matter of time, say

15、s Aly Badawy, director of research and development for Delphi Saginaw Steering Systems in Saginaw, Mich. The issue was cost and thats behind us now. By 2002 here in the U.S. the cost of electric power steering will absolutely be a wash over hydraulic.Today, electric and hybrid-powered vehicles (EV),

16、 including Toyotas Prius and GMs EV-1, are the perfect domain for electric steering. But by 2010, a TRW Inc. internal study estimates that one out of every three cars produced in the world will be equipped with some form of electrically-assisted steering. The Cleveland-based supplier claims its new

17、steering systems could improve fuel economy by up to 2 mpg, while enhancing handling. There are true bottom-line benefits as well for automakers by reducing overall costs and decreasing assembly time, since theres no need for pumps, hoses and fluids.Another claimed advantage is shortened development

18、 time. For instance, a Delphi group developed E-TUNE, a ride-and-handling software package that can be run off a laptop computer. They can take that computer and plug it in, attach it to the controller and change all the handling parameters - effort level, returnability, damping - on the fly, Badawy

19、 says. It used to take months. Delphi has one OEM customer that should start low-volume production in 99.Electric steering units are normally placed in one of three positions: column-drive, pinion-drive and rack-drive. Which system will become the norm is still unclear. Short term, OEMs will choose

20、the steering system that is easiest to integrate into an existing platform. Obviously, greater potential comes from designing the system into an all-new platform.We have all three designs under consideration, says Dr. Herman Strecker, group vice president of steering systems division at ZF in Schwae

21、bisch Gmuend, Germany. Its up to the market and OEMs which version finally will be used and manufactured.The large manufacturers have all grabbed hold of what they consider a core technology, explains James Handysides, TRW vice president, electrically assisted steering in Sterling Heights, Mich. His

22、 company offers a portfolio of electric steering systems (hybrid electric, rack-, pinion-, and column-drive). TRW originally concentrated on what it still believes is the purest engineering solution for electric steering-the rack-drive system. The system is sometimes refered to as direct drive or ba

23、ll/nut drive.Still, this winter TRW hedged its bet, forming a joint venture with LucasVarity. The British supplier received $50 million in exchange for its electric column-drive steering technology and as sets. Initial production of the column and pinion drive electric steering systems is expected t

24、o begin in Birmingham, England, in 2000.What we lack is the credibility in the steering market, says Brendan Conner, managing director, TRW/LucasVarity Electric Steering Ltd. The combination with TRW provides us with a good opportunity for us to bridge that gap. LucasVarity currently has experimenta

25、l systems on 11 different vehicle types, mostly European. TRW is currently supplying its EAS systems for Ford and Chrysler EVs in North America and for GMs new Opel Astra.In 1995, according to Delphi, traditional hydraulic power steering systems were on 7596 of all vehicles sold globally. That 37-mi

26、llion vehicle pool consumes about 10 million gallons in hydraulic fluid that could be superfluous, if electric steering really takes off.The present invention relates to an electrically powered drive mechamsm for providing powered assistance to a vehicle steering mechanism. According to one aspect o

27、f the present invention, there is provided an electrically powered driven mechanism for providing powered assistance to a vehicle steering mechanism having a manually rotatable member for operating the steering mechanism, the drive mechanism including a torque sensor operable to sense torque being m

28、anually applied to the rotatable member, an electrically powered drive motor drivingly connected to the rotatable member and a controller which is arranged to control the speed and direction of rotation of the drive motor in response to signals received from the torque sensor, the torque sensor incl

29、uding a sensor shaft adapted for connection to the rotatable member to form an extension thereof so that torque is transmitted through said sensor shaft when the rotatable member is manually rotated and a strain gauge mounted on the sensor shaft for producing a signal indicative of the amount of tor

30、que being transmitted through said shaft.Preferably the sensor shaft is non-rotatably mounted at one axial end in a first coupling member and is non-rotatably mounted at its opposite axial end in a second coupling member, the first and second coupling members being inter-engaged to permit limited ro

31、tation therebetween so that torque under a predetermined limit is transmitted by the sensor shaft only and so that torque above said predetermined limit is transmitted through the first and second coupling members.The first and second coupling members are preferably arranged to act as a bridge for d

32、rivingly connecting first and second portions of the rotating member to one another.Preferably the sensor shaft is of generally rectangular cross-section throughout the majority of its length.Preferably the strain gauge includes one or more SAW resonators secured to the sensor shaft.Preferably the motor is drivingly connected to the rotatable member via a clutch.Preferably the motor includes a gear box and is concentrically arranged relative to the rotatable member.Various aspects of the present invention will hereafter be described, with reference to th