| With rapidly developing of traffic and transport as well as rising ofconstructing item in our country, the number of heavy-duty vehicle is alsoincreasing. For designing of super heavy-duty vehicle, the limit of axes load needbe considered in order to make its structure feasible and accord with request ofhighway-code. Simple and convenient method is to increase the number of axes,namely, substituting single-front-axle for double-front-axle. Accordingly, the outputand distribution of double-front-axle steering automobile start to increase rapidly. Double-front-axle steering automobile is usually called "four-front andeight-back automobile". Double-front-axle steering structure has multifold formswhich add front adjustable pole and back adjustable pole whose length can beadjusted, two steering cantalevers and four joining pins to steering transmissionstructure. Two steering cantalevers are fastened to the frame of vehicle. The twosections of the adjustable pole are reversely screwed. Pole and two sections arejointed by fastener and bolt, bolt of two sections need be loosened in order tocircumrotate body of pole for adjusting length. The unusual tyre abrasion is the most prominent problem aboutdouble-front-axle steering automobile. The abrasion is caused by wheel sideslipwhich happen when wheel rolls. Wheel sideslip include sideslip between wheelsand sideslip between axles. Sideslip between wheels is accustomed wheel sideslip,namely, because of the parameter matching of the wheel location improperly,especially the matching between the wheel toe-in and the wheel camber angleimproperly, the phenomenon makes the wheel slide to left or right relatively to theground when the automobile travels in the beeline. Sideslip between axles isdefined that, because the two steering axles of double-front-axle steering systemcan not harmoniously cooperate, they deflect along different direction separately,which lead to wheel sideslip. Wheel sideslip affect the controlling stability ofautomobile, consume more fuel and aggravate tyre abrasion.Tyre abrasion is a main factor of affecting the useful life of a tyre. Secundabrasion is main format of abrasion about double-front-axle steering automobileand is different from secund abrasion caused by the parameter matching of thewheel location improperly. When the parameter matching of the wheel location isimproper, namely, the matching between the wheel toe-in and the wheel camberangle is ill-suited, abrasion of the two wheels of the same steering axle is inside oroutside simultaneously, because of wheels sideslip. However, whendouble-front-axle steering system failure take place, abrasion of the two wheels ofthe same steering axle is in the same side, and that, tyre abrasion direction of frontand back steering axles is rightabout. That is to say, if tyre abrasion of frontsteering axle lie in the left side, tyre abrasion of back steering axle lie in the rightside to a certainty, which is the rule of tyre abrasion of double-front-axle steeringautomobile.Tyre abrasion of double-front-axle steering automobile follows above rule as aresult of two factors namely change of adjustable pole's length and deflexion offront and back steering axles. The two sections of the adjustable pole are reverselyscrewed. Pole and two sections are jointed by fastener and bolts, bolt of twosections need be loosened in order to turn body of pole for adjusting length. Whenfastener and bolt become loose or adjustable pole is curved, adjustable pole'slength will change. Change of adjustable pole's length will result in deflexion ofwheel. Direction of wheel deflexion of front and back steering axles leads to fourresultants namely left deflexion of both axles, right deflexion of both axles, leftdeflexion of front axle and right deflexion of back axle, right deflexion of frontaxle and left deflexion of back axle. All instances bring on wheel sideslip.Undercarriage distortion, axle distortion, and U-shaped bolt etc will lead todeflexion of front and back steering axles. Deflexion of steering axles includesreversed deflexion and unreversed deflexion. Deflexion of steering axles affects thecontrolling stability of automobile like deflexion of steering wheel. In fact, fromthe point of view of kinematics, turn of axle and wheel arouse the result likesideslip angle of wheel.In course of running of automobile, ponderance and abnormity of tyre abrasion isonly able to be estimated by detection of wheel sideslip because it is unable to bedetected directly. Detection of wheel sideslip includes detection of sideslip betweenwheels and detection of sideslip between axles. Method and means of detectionabout sideslip between wheels are already very advanced, but detection aboutsideslip between axles is void at all times. In practice,double-board-separate-movement sideslip tester is capable of detection of sideslipbetween axles by fixing two displacement sensors. Value of sideslip betweenwheels and sideslip between axles can be calculated with formula. However,experiment indicate that the result of the detection method is inaccurate andanamorphic. The paper discusses a new detection method which achieves aim ofaccurate and fast detection. The detection method based on double-board-linkagesideslip tester can detect sideslip between wheels and sideslip between axlesdirectly.This paper researches and designs detection system of wheel sideslip in detail,aim of which is to realize integrative detection for sideslip between wheels andsideslip between axles. Finally, the detection system will be applied to detectionstation of integrative performance for automobile in order to carry out fast andonline detection. The system includes mainly two sections of hardware designationand software designation. Hardware designation consists of mechanism, signalcollection and disposal. Designation of mechanism involves frame, release device,slip-board device, equal-rocker-leverage machine, equal-rocker-axle shift machine,comeback device, oriented device, locked device and so on. Designation of signalcollection and disposal comprises selection of sensor, photoelectric on-off,signal-disposal board and A/D transform board. Designation of software includesselecting circumstance of programme, whole designation and designation of everymodule etc.At last, Whole system is validated by experiment. Make an analysis formetrical data for the sake of show error. The practical experiment proves that thesystem can be used in the detection of the sideslip. |
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