畢業(yè)論文外文翻譯-電子動力轉(zhuǎn)向系統(tǒng)

1、electronic power steering systemwhat 辻 iselectricallypoweredsteering uses an electric motor to drive either the power steering hydraulic pump or the steering linkage directly. the power steering function is therefore independent of engine speed, resulting in significant energy savings.how it works :

2、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 assist the driver.in electro-hydraulic steering, one electrically powered steering concept uses a high efficiency pump driv

3、en 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. the pump can be run at low speedl or shut off to provide energy savings during straight ahead driving (which is most of the

4、 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 gear drives is possible. a microprocessor controls steering dynamics and driver effort. inputs include vehicle speed and st

5、eering, wheel torque, angular position and turning rate.working in detail:a nsteering sensor1' is located on the input shaft where it enters the gearbox housing. the steering sensor is actually two sensors in one: a "torque sensor” that converts steering torque input and its direction into

6、voltage signals, and a nrotation sensor11 that converts the rotation speed and direction into voltage signals. an "interface” circuit that shares the same housing converts the signals from the torquesensor and rotation sensor into signals the control electronics can process.inputs from the stee

7、ring sensor are digested by a microprocessor control unit that also monitors input from the vehicle's speed sensor. the sensor inputs are then compared to determine how much power assist is required according to a preprogrammed hforce maph in the control units memory. the control unit then sends

8、 out the appropriate command to the hpower unith 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 current reverses the direction the motor spins). increasing the current to the motor increases

9、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 sensofs inputs; a hreturnh control mode which is used to assist steering return after completing a

10、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 control unit reduces current to the electric motor to prevent an overload situ

11、ation 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 faults by monitoring the system's inputs and outputs, and the driving c

12、urrent 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 dash eps warning light is also illuminated to alert the driver. to diag

13、nose the problem, a technician jumps the terminals on the service check connector and reads out the trouble codes.constructionball screw unit motor unn rack axistorque sensor unttrack & pinion whh variable gear ratiosteering torque 'click here to see a biggerassist mapphasecomocnsalorcurrent

14、 controllerassist torquecompensatorelectric power steering systems promise weight reduction, fuel savings and package flexibility, at no cost penalty.europe's high fuel prices and smaller vehicles make a fertile testbed for electric steering, a technology that promises automakers weight savings

15、and fuel economy gains. and in a short time, electric steering will make it to the u.s.，too. nitfs just just a matter of time/1 says aly badawy, director of research and development for delphi saginaw steering systems in saginaw, mich. "the issue was cost and that's behind us now. by 2002 h

16、ere 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 toyota's prius and gm's ev-1, are the perfect domain for electric steering. but by 2010, a trw inc. internal study estimates that one out o

17、f 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 handling. there are true bottom-line benefits as well for automakers by

18、reducing overall costs and decreasing assembly time, since there's no need for pumps, hoses and fluids.another claimed advantage is shortened development time. for instance, a delphi group developed etune, a ride-and-handling software package that can be run off a laptop computer. ”they can take

19、 that computer and plug it in, attach it to the controller and change all the handling parameters effort level, returnability, damping 一 on the fly/1 badawy says. hit used to take months.h delphi has one oem customer that should start low-volume production in f99.electric steering units are normally

20、 placed in one of three positions: columdrive, pinion-drive and rack-drive. which system will become the norm is still unclean short term, oems will choose the steering system that is easiest to integrate into an existing platform. obviously, greater potential comes from designing the system into an

21、 allnew platform. "we have all three designs under consideration,' says dr. herman strecker, group vice president of steering systems division at zf in schwaebisch gmuend, germany. "it's up to the market and oems which version finally will be used and manufactured/* nthe large manu

22、facturers have all grabbed hold of what they consider a core technology/1 explains james handy sides, trw vice president, electrically assisted steering insterling heights, mich his company offers a portfolio of electric steering systems (hybrid electric, rack-, pinion-, and column-drive). trw origi

23、nally concentrated on what it still believes is the purest engineering solution for electric steeringthe rack-drive system. the system is sometimes refer to as direct drive or ball/nut drive.still, this winter trw hedged its bet, forming a joint venture with lucas vari ty the british supplier receiv

24、ed $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 is the credibility in the steering market/1 says brendan conner, ma

25、naging director, trw/lucasvarity electric steering ltd. nthe combination withtrw provides us with a good opportunity for us to bridge that gap/1 lucasvarity currently has experimental systems on 11 different vehicle types, mostly european. trw is currently supplying its eas systems for ford and chry

26、sler evs in north america and for gm s 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 in hydraulic fluid that could be superfluous, if electric steeri

27、ng 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 electrically powered driven mechanism for providing powered assistance t

28、o 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 electrically powered drive motor drivingly connected to the rotatable memb

29、er 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 rotatable member to form an extension thereof so that torque is tra

30、nsmitted 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. preferably the sensor shaft is non-rotatably mounted at one axial end in a f

31、irst 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 and so that t

32、orque 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 drivingly connecting first and second portions of the rotating member to one another. preferably the sensor shaft is

33、 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 i

34、s concentrically arranged relative to the rotatable member. various aspects of the present invention will hereafter be described, with reference to the accompanying drawings, in which :figure 1 is a diagrammatic view of a vehicle steering mechanism including an electrically powered drive mechanism a

35、ccording to the present invention, figure 2 is a flow diagram illustrating interaction between various components of the drive mechanism shown in figure 1 ,figure 3 is an axial section through the drive mechanism shown in figure 1, figure 4 is a sectional view taken along lines iv-iv in figure 3,fig

36、ure 5 is a more detailed exploded view of the input drives coupling shown in figure 3, and figure 6 is a more detailed exploded view of the clutch showing in figure 3. referring initially to figure 1 , there is shown a vehicle steering mechanism 1() drivingly connected to a pair of steerable road wh

37、eels the steering mechanism 10 shown includes a rack and pinion assembly 14 connected to the road wheels 12 via joints 15. the pinion(not shown) of assembly 14 is rotatably driven by a manually rotatable member in the form of a steering column 18 which is manually rotated by a steering wheel 19.the

38、steering column 18 includes an electric powered drive mechanism 30 which in eludes an electric drive motor (not shown in figure 1) for driving the pinion in response to torque loadings in the steering column 18 in order to provide power assistance for the operative when rotating the steering wheel 1

39、9.as schematically illustrated in figure 2, the electric powered drive mechanism includes a torque sensor20 which measures the torque applied by the steering column 18 when driving the pinion and supplies a signal to a controller 40. the controller 40 is connected to a drive motor 50 and controls th

40、e electric cuirent supplied to the motor 50 to control the amount of torque generated by the motor 50 and the direction of its rotation. the motor 50 is drivingly connected to the steering column 18 preferably via a gear box 60, preferably an epicyclic gear box, and a clutch 70. the clutch 70 is pre

41、ferably permanently engaged during normal operation and is operative under certain conditions to isolate drive from the motor 50 to enable the pinion to be driven manually through the drive mechanism 30. this is a safety feature to enable the mechanism to function in the event of the motor 50 attemp

42、ting to drive the steering column too fast and/or in the wrong direction or in the case where the motor and/or gear box have seized the torque sensor 20 is preferably an assembly including a short sensor shaft on which is mounted a strain gauge capable of accurately measuring strain in the sensor sh

43、aft brought about by the application of torque within a predetermined range. preferably the predetermined range of torque which is measured is 0-lonm; more preferably is about l-5nm.preferably the range of measured torque coitesponds to about 0-1000 microstrain and the construction of the sensor sha

44、ft is chosen such that a torque of 5nm will result in a twist of less than 2° in the shaft, more preferably less than 1 ° .preferably the strain gauge is a saw resonator, a suitable saw resonator being described in wo91/13832. preferably a configuration similar to that shown in figure 3 of

45、 wo91/13832 is utilised wherein two saw resonators are arranged at 45° to the shaft axis and at 90° to one another. preferably the resonators operate with a resonance frequency of between 200-400 mhz and are arranged to produce a signal to the controller 40 of 1 mhz ± 500 khz dependin

46、g upon the direction of rotation of the sensor shaft. thus, when the sensor shaft is not being twisted due to the absence of torque, it produces a i mhz signal. when the sensor shaft is twisted in one direction it produces a signal between 1.0 to 1.5 mh乙 when the sensor shaft is twisted in the oppos

47、ite direction it produces a signal between 1.0 to 0.5 mhz. thus the same sensor is able to produce a signal indicative of the degree of torque and also the direction of rotation of the sensor shaft preferably the amount of torque generated by the motor in response to a measured torque of between 0-1

48、 onm is 040nm and for a measured torque of between l-5nm is 0-25nm.preferably a feed back circuit is provided whereby the electric current being used by the motor is measured and compared by the controller 40 to ensure that the motor is running in the correct direction and providing the desired amou

49、nt of power assistanee. preferably the controller acts to reduce the measured torque to zero and so controls the motor to increase its torque output to reduce the measured torque. a vehicle speed sensor (not shown) is preferably provided which sends a signal indicative of vehicle speed to the contro

50、ller. the controller uses this signal to modify the degree of power assistance provided in response to the measured torque. thus at low vehicle speeds maximum power assistance will be provided and a high vehicle speeds minimum power assistance will be provided。 the controller is preferably a logic s

51、equencer having a field programmable gate array for example a xc 4005 as supplied by xilinx. such a controller does not rely upon software and so is able to function more reliably in a car vehicle environment. it is envisaged that a logic sequence not having a field programmable array may be used.el

52、ectronic power steering system (english as eps), and hydraulic power steering system (hps) compared to, eps has many advantages.the advantage is that the eps:1) high efficiency. hps efficiency is very low, generally 60% to 70%, while eps and electrical connections, high efficiency, and some can be a

53、s high as 90 percent.2) less energy consumption. automobile traffic in the actual process, at the time to about 5 percent of the time travelling, the hps system, engine running, the pumps will always be in working condition, the oil pipeline has been in circulation, so that vehicle fuel consumption

54、rate by 4 % to 6%, while eps only when needed for energy, vehicle fuel consumption rates only increased by 0.5 percent.3) "road sense of1' good. because eps internal use of rigid, system of the lag can be controlled by software, and can be used in accordance with the operation of the driver

55、 to adjust.4) back to being good. eps simple structure of small internal resistance, is a good back, get back to being the best characteristics, improve vehicle handling and stability.5) little environmental pollution. hps hydraulic circuit in the hydraulic hoses and connectors, the existence of oil

56、 leaking, but hydraulic hoses can not be recovered, the environmental pollution are to a certain extent, while eps almost no pollution to the environment.6) can be independent of the engines work. eps for battery powered devices, as long as sufficient battery power, no matter what the condition for

57、the engine, can produce power role.7) should have a wide range.8) easy to assemble and good layout.now, power steering systems of some cars have become the standard-setting, the whole world about half of the cars used to power steering. with the development of automotive electronics technology, some

58、 cars have been using electric power steering gear, the car of the economy, power and mobility has improved. electric power steering device on the car is a new power steering system device, developed rapidly in recent years both at home and abroad, because of its use of programmable electronic contr

59、ol devices, the flexibility in the same time there are also potential safety problems. in the analysis this unique product on the basis of the author of the characteristics of electronic control devices, security clearance just that the factors that deal with security measures, and discussed a number of concerns the safety of specific issues. the results show that : existing standards can not meet the electric power steering device security needs and made the electric power steering device saf