Research On The Testing System For The Performance Of Automobile Power Steering

The performance test system of the power steering can test the workperformance of the power steering ,and finish every kind of the test of the nationalstandingoperatingprocedure.The automobile industry has always been one of pillar industries of the stateeconomy development. In recent years, with the technology advancement and theautomobile profession standard promotion, enhance the automobile the quality,guaranteed the travelthe security, while vigorously developing our countryautomobile industry, this requests the factory have to carry on the qualityexamination to each batch of products, but the automobile steering system is thespecial-purpose part which applies mechanically changes or restores the automobiletravel direction, is the important part of the automobile, is the basic safeguard of theautomobilestabletravel,alsodirectlyrelatespeople'slifeandpropertysafety.Forit ,wemust first understandthetypeand theprincipleof work ofthe powersteering, Specially the power steering of the hydraulic pressure type .When bringpressure on the steering wheel,it can lead the input axis to rotate together . But thistime, as a result of the wheel resistance function , the piston and the screw rod aremotionless .Like this , as a result of the twisted bar`s elastic function, the input axisand the valve cover rotation slightly ahead of time with changes the screw rod, thevalve cover has the relative rotation with the screw rod . This time the relativepositionsofsixgroupsofoilgroovesofthevalvecoverandthescrewrodrelativetotheposition of the state of equilibrium time has changed and distributed the pressure oilto a side of the piston through the gap, thus overcomed the steering resistance tohavethedisplacement,finishedthesteering.Based it on ,I analyze the mechanical structure of the test system and theprinciple of work of the hydraulic pressure system . The hydraulic control systemdivides into mainly two parts, the first supplies the oil for the power steering, thesecondsupplies theoil fortheliquiddampingcylinder. Thehydraulicpressureoil ofthe oil box enter the timing valve through the vane pump, then enter the liquiddamping cylinder through electromagnetism commutation valve . the oil comingfrom the ram pump supplies the power steering, the pressure sensor is installed inthe input oil place and the output oil place of the power steering, it uses forexamining the oil pressure.The electromagnetism commutation valve is establishedin the parallel oil way of the power steering, it may carry on the experiment of theinsideleakthroughtheadjustment,moreoveraflowsensorisinstalledinthewayofthe experiment of the inside leak , surveyed the distributaries'capacity through theelectromagnetismcommutationvalve.But the key is that we must use the suitable sensor according to the differenttest object, design or choice the hardware of the effective and accurate meteringcircuit and finishing the realization of the signal transformation and the signalprocessing, consider the economy and the practice, show the result of the test in themost convenient and most scientific form. The paper has mainly maken theresearches on the basic structure composition of the test system and the principle ofwork,mainly has carried on the circuit analysis of the data acquisition system ,theoutputcontrolsystemandtheelectricitycontrolsystem.Thesensortransforms eachkindofphysical quantityoftheobject likepressureand the torque signal and so on into electrical signal voltage and electricity . Themajority of the examination signals which the sensor produced are the simulantquantity, but the computer only can recognize the digital quantity, in order to enablethe computer to process or save the examination signal, we must transform thesimulant quantity into the digital quantity .So we need transform the signal throughtheadjustment intotheelectrical signal,suitingto thesystem operatingregion, thenpasses through the multichannel analog switch, transforms the parallel inputmultichannel simulant signal into the separate time signal, under the logic circuitcontrol,transforms each roadthesimulatedsignal throughtheA/Dconvertoronebyone into the digital code, the signal is processed through the connection electriccircuitinputtothecomputer.The output control system applies the DI/O digital output module,realizes thedigital output, drivers the electromagnetism valve of the hydraulic system. But thedriving force of the output control system is limited, it needs to add the relaybetween the output control card and the electromagnetism valve. The DI/O outputdigital signal controls the operation of the relay, so the relay can drive thecorrespondingelectromagnetismvalve,completethecorrespondingexperiment.And we applied the computer control technology, carried on the output controlto the test system . The software part of the test system mainly finished the test ofthepowersteeringandthecontrolworkoftheexperiments.Duringthedesignofthesoftware of the test system , the software package which the production factory ofthe chip card supported ,has sealed some essential functions for specially hardwaredriver and the debugging, it is the key function to finish the signal processing . Thesoftware design of the test system applices the modulation design, is composed bythe master routine and the multi- stature program module. In the programmingprocess, it makes every part as far as possible independent in order to softwarecompilationand debugging.The paper based on the Windows NT operatingsystem ,used the Visual C++ software tool to carry on the development for the testsystem, Emphatically carries on the design of the data acquisition program and thedataprocessingprogram.The paper takes the performance test condition and the testing method of thepower steering of the national standing operating procedure as a standard, and hasmaken the innovations in the testing method to carry on the performance test , andmakes the analysis to the main test results of the power steering .It makes thebeneficial exploration for automatically ,accurately ,reliably testing the powersteering performance . The test result has confirmed the test system reliability andaccuracy.Thetestsystemhasthefollowingadvantages:(1)The test automation. Because the computer has the ability of the savingsignal,the judgement and the handling, therefore it can control the switch pass orbreaks, automatic diagnosis breakdown, result automatic output and so on. Thecomputer as the core of the test system, causes the entire test system to become anorganic whole, caused the test to realize the automation, also greatly enhanced thetestspeed.(2)The test precision to be high. As a result of outside disturbance, internalnoise, power source undulation change, componentnon-linear and so on, inevitablyreduces the test precision. The test system may carry on the digital filter, carries onthe effect to the component non-linearity; The test system also may carry on theautomatic calibration to eliminate the system error, repeate the surveyto be possiblemany times to reduce the random measurement errors,it will improve the testprecision.(3)The test system is economic and practical, easy to operate, may realize theautomatic operation, and carry on the manual operation debugging. Software hasrealized the many kinds of logicunits, the comparator, the filter and so on, canceledsome hardware, thus reduced the cost of the test system. Because the computerperformance unceasinglyenhances, the price drops year by year, this advantage willbecomemoreprominent.(4)Improvingthereliabilityofthetestingsystem.About the content of the paper, we should strengthen to the research about thefollowingseveralaspects:(1)The test system can only carry on the static characteristics experiment. Wemay consider to makes the improvement for the hydraulic system, enables the testsystem to complete the dynamic characteristic experiment;(2)we may consider touse the hardware module of the better performance;(3)the software function of thetestsystemcanbefurtherimproved.