1、 自动化专业毕业设计（论文）外文翻译 Electronic power steering system What it is Electrically powered steering uses an electric motor to drive either the power steering HYPERLINK http:/ t _top hydraulic pump or the steering linkage directly. The power steering function is therefore independent of engine speed, result
2、ing in significant energy savings. How it works : Conventional power HYPERLINK http:/ t _top 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 assist the driver. In electro-hydraulic steering,
3、 one electrically powered steering concept uses a high efficiencypump driven by an HYPERLINK http:/ t _top electric motor. Pump speed is regulated by an electric controller to vary pump pressure and flow, providing steering efforts tailored for different driving situations. The pump can be run at lo
4、w 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 HYPERLINK http:/ t _top steering rack via a gear mechanism (no pump or fluid). A variety of motor types and g
5、ear 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 sens
6、or 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 to
7、rque 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 HYPERLINK http:/ t _top speed sensor. The sensor inputs are then compared to determine how much p
8、ower assist is required according to a preprogrammed force map in the control units memory. The control unit then sends out the appropriate command to the HYPERLINK http:/ t _top power unit which then supplies the electric motor with current. The motor pushes the rack to the right or left depending
9、on which way the voltage flows (reversing the current 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 fr
10、om the steering torque and rotation sensors inputs； 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 pos
11、ition and steering assist reaches a maximum, the control 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 HYPERLINK http:/ t _top alternator or charging
12、 problem. The electronic steering control unit is capable of self-diagnosing faults 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 eliminate
13、s all power assist, causing the system to revert back to manual steering. A dash 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 HYPERLINK http:/ t _top trouble codes. INCLUDEPICTURE
14、 http:/ * MERGEFORMATINET HYPERLINK http:/ click here to see a bigger HYPERLINK http:/ INCLUDEPICTURE http:/ * MERGEFORMATINET Electric power steering systems promise weight reduction, fuel savings and package flexibility, at no cost penalty. Europes high fuel prices and smaller vehicles make a fert
15、ile 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, says AlyBadawy, director of research and development for Delphi Saginaw Steering Syste
16、ms 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), including Toyotas Prius and GMs EV-1, are the perfect domain for electric steering
17、. 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 steering systems could improve fuel economy by up to 2 mpg, while enhancing handlin
18、g. 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 time. For instance, a Delphi group developed E-TUNE, a ride-and-handling software
19、 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 says. It used to take months. Delphi has one OEM customer that should start low-v
20、olume production in 99. HYPERLINK http:/ t _blank 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 the steering system that is easiest to integrate into a
21、n 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 SchwaebischGmuend, Germany. Its up to the market and OEMs wh
22、ich version finally will be used and manufactured. The large manufacturers have all grabbed hold of what they consider a core technology, explains James Handy sides, TRW vice president, electrically assisted steering in Sterling Heights, Mich. His company offers a portfolio of electric steering syst
23、ems (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 refer to as direct drive or ball/nut drive. Still, this winter TRW hedged its bet, fo
24、rming 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 to begin in Birmingham, England, in 2000. What we lack
25、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 experimental systems on 11 different vehicle types, mostly Europ
26、ean. 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-million vehicle pool consumes about 10 million gallons
27、 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 of the present invention, there is provided an elect
28、rically 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 manually applied to the rotatable member, an electri
29、cally 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 including a sensor shaft adapted for connection to the
30、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 torque being transmitted through said shaft. Preferabl
31、y 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 rotation there between so that torque under a predetermined limit is transmitted by the sensor shaft only
