Cab environment warning and control method and app.docx

Cab environment warning and control method and app.docx

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Cabenvironmentwarningandcontrolmethodandapp

Cabenvironmentwarningandcontrolmethodandapparatus

STATEMENTREGARDINGFEDERALLYSPONSOREDRESEARCH

Notapplicable.

CROSS-REFERENCETORELATEDAPPLICATIONS

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CROSS-REFERENCETORELATEDAPPLICATIONS

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BACKGROUNDOFTHEINVENTION

Whilethepresentinventionmaybeemployedinseveraldifferentoff-highwayapplications,inordertosimplifythisexplanation,thepresentinventionwillbedescribedinthecontextofanexemplaryagriculturaltractorandassociatedcab.

Today,infarming,asinotherindustries,competitivepressureshaveforcedfarmerstosearchforwaysinwhichtoincreaseefficiencyandproductivity.Oneobviouswaytoincreaseefficiencyandproductivityistousebetterandmoreefficientequipmentsuchasstateoftheartagriculturaltractorsorcombines.Aproperlyconfiguredtractorappreciablyincreasesthespeedwithwhichfarmerscanplant,till,fertilizeandharvest.

Oneotherwayinwhichtoincreaseefficiencyandproductivityistoemployhighlyspecializedequipmenttoperformcertainfarmingtasks.Forinstance,somespecializedtractorsareequippedwithsprayersorotherchemicalspreadingimplementsthatapplypesticidesandothernoxiousproductswithinfieldsextremelyefficiently.

Unfortunately,stateofthearttractorsarerelativelyexpensiveandtherefore,inordertojustifythecostsassociatedwithsuchtractors,eventhoughthetractorsreducethetimerequiredtoperformvarioustasks,farmersmustspreadthecostsofsuchequipmentoverincreasinglylargerenterprises.Infarming,alargerenterprisetypicallytranslates,atleastinpart,intofarmingmoreacreageand,notsurprisingly,farmingmoreacreagetypicallyrequiresagreatertimecommitmentonthepartofthefarmer.

Inthecaseofspecializedequipmentsuchassprayerequippedtractorsandthelike,highcostsassociatedwiththatequipmentandlimitedusesfortheequipmentrendersitdifficultforsomefarmerstopurchasetheirownsuchequipment.Instead,asegmentoftheserviceindustryhasevolvedaroundspecializedtypesofequipmentwhereasingleownerpurchasessuchequipmentandprovidesservicestomanyfarmerswithinanareasothat,again,thecostoftheequipmentisspreadoutamongmanyfarmersandtheiracreage.

Becausefarmersandspecialserviceprovidersarespendinggreateramountsoftimeintheirtractorcabs,cabcomforthasbecomearelativelyimportantfeatureinnewtractorconfiguration.Thus,newtractorsaretypicallyfittedwithstateoftheartcabsincludingergonomicallydesignedseatingandcontrols,betterlinesofsightandcabspaceconditioningsystemsthatcontroltemperature,aircirculationandhumidity.

Inadditiontothefeaturesdescribedabove,theindustryhasalsorecognizedthatairqualitywithinthecabspaceisimportanttooperatorcomfortandhealthandalsotooverallsystemefficiency.Tothisend,inmanyapplications,agriculturaltractorsoperateinenvironmentsthatincludehighconcentrationsofairbornedirtanddust.Moreover,whereatractorimplementisusedtosprayorapplyanoxiouschemical,portions（e.g.,dropletsorparticles）ofthenoxiouschemicalsoftenbecomeairborneandcanbeinhaledbyatractoroperator.Hereinafterairborneparticleswithinanenvironmentwillcollectivelybereferredtoas“contaminants”.

Inhalingcontaminantscancausediscomfortovershortperiodsoftimeand,overlongperiodsoftime,canleadtoothermedicalsymptoms.Moreover,contaminantshavebeenknowntoaccumulateonheatingandcoolingsystemcomponentsandreducebothefficiencyandeffectiveness,therebyfurtherreducingoperatorcomfort.

Tominimizecontaminants（e.g.,dirt,dust,etc.）withinthecabspace,itiswellknowntoprovideacompletelyenclosedcabandanaircirculationsystemthattakesinandfilters“fresh”outsideairfromtheambient,heatsorcoolstheairviaanatmospherecontrolsystemandcirculatestheconditionedairwithinthecabviaoneormorepressurizationblowers/fans.Preferably,cabairpressureismaintainedaboveathresholdpressurethatisslightlyhigherthanatmosphericpressure（i.e.,atleastafewmillimetersofheadofwater）.Thepressuredifferentialbetweentheambientandthresholdpressureinhibitsentryofcontaminantsintothecabthrough,forexample,imperfectlysealeddoorsorwindows.

Toincreasecoolingandheatingefficiency,manytractorairconditioningsystemswillincludetwoseparatefans.Intwofansystems,afirstfanistypicallypositioneddownstreamoftheairinletandfilterfordrawingfreshairintotheconditioningsystemfromtheoutsideambientwhileasecondrecirculatingfanispositioneddownstreamofasysteminletlocatedwithinthecabfordrawingairintotheconditioningsystemfromwithinthecab.Therecirculatingfan,asthenameimplies,recirculatesairfromwithinthecabthroughtheconditioningunit.Intwofansystems,therecirculatedandfreshairarecombinedwithintheconditioningunitpriortobeingdirectedintothecabspace.Becausetherecirculatedairisalreadygenerallyatthetemperatureandhumiditylevelrequiredinsidethecabspace,thesystemcapacityrequiredtoconditiontherecirculatedairisrelativelylessthanthesystemcapacityrequiredtoconditionfreshairandthereforeoverallconditioningefficiencyisincreased.

Unfortunately,undercertaincircumstances,acabconditioningsystemisrenderedincapableofmaintainingacabpressurethatisgreaterthantheambientpressure.Forinstance,overtime,cabdoorandwindowsealsdeteriorateandairescapestherethroughatanunexpectedlyhighratetherebyreducingcabpressureappreciably.Asanotherinstance,“fresh”airfilters（i.e.,filtersthatcleanairdrawninfromtheoutsideambient）oftenbecomecloggedtherebystarvingthefansofinletairandreducingcabspaceairpressure.Asyetanotherexample,inadvertentplacementofanyiteminfrontofabloweroutletportcancauseareductionincabpressure.Otherpotentialcausesofcabpressuredropincludemalfunctioningfans,improperlypositionedairlouvers,slightlyopendoorsorwindows,anitem（e.g.,aseatbelt）stuckwithinacloseddoor,etc.

Onesolutionformaintainingadesiredcabpressureinspiteofsomeofthecausesofpressuredropdescribedabovehasbeentofacilitateeithermanualorautomaticfanspeedadjustment.Tothisend,pressuresensorshavebeendevelopedthatcompareambientandcabpressuresandgeneratealarmsignalsindicatingwhenthecabpressuredipsbelowathresholdpressurethatisslightlyabovetheambientpressure.Inthecaseofmanuallyadjustablesystems,thealarmsignalsarefedtoindicators（i.e.,asmalllight）withinthecaband,whenanindicatorisactivated,theoperatoriswarnedofthepressureproblem.Anoperator'smanualmayadvisetoadjustthefanspeedortomodifythepositionsoflouverswithinthesystemplenumandductsub-systemtoincreaseairflow.

Inthecaseofautomaticallyadjustablesystems,thealarmsignalsarefedtoacontrollerthatadjustsfanspeedeitherupordownorlouverpositionstomaintainthecabpressureabovethethresholdpressuretherebymaintainingcabspace-ambientpressuredifferentialyetminimizingrequiredfreshairfiltering.OneexemplaryautomaticfanspeedadjustmentsystemisdescribedinU.S.Pat.No.4,581,988（hereinafter“the'988patent”）whichissuedonApr.15,1986andwhichisentitled“ProtectiveDeviceforWorkinPollutedEnvironment”.The'988patentalsoteachesthat,afterincreasingfanspeed,ifcabpressureremainsbelowthethresholdpressure,thecontrolleractivatesanindicator（e.g.,asmalllight）towarntheoperatorthattheautomaticcorrectiveactionhasfailedtomaintainthecabspace-ambientpressuredifferential.

Ineitherofthemanualorautomaticblowerspeedadjustmentcases,ifanalarmconditionoccursdespitemaximumfanspeed,thetractoroperatorissupposedtorecognizethattheintakefilteriscloggedandtakestepstounclogthefilter.Filteruncloggingmayincluderemovingafilterelementandeitherreplacingtheelementorcleaningtheelementandplacingthecleanedelementbackintothesystem.Unfortunately,whileadvantageous,theautomaticandmanualpressuremaintainingsystemsdescribedabovehaveseveralshortcomings.

First,thesystemsdescribedaboverelyontractoroperatorstotakestepstocorrectcabpressureproblemsaftertheproblemshavebeenindicated.Whileoperatorinitiativewouldnotbeaprobleminsomeindustries,asindicatedabove,farmersandspecializedserviceprovidersoftenworkunderseeminglyunreasonabletimeconstraintsand,forthatreason,mayelecttoforegoperformingtasksthatthefarmer“perceives”asunnecessary.Thiswillingnesstoforegoseeminglyunnecessarytasksisparticularlytrueduringintenseperiodssuchasplantingseason,harvestingseason,fertilizingtimes,etc.,whereparticulartaskshavetobecompletedwithinrelativelyshortperiods.Underthesecircumstances,anactivatedcabpressurelightmaybecompletelyignoredasrelativelyunimportant（i.e.,operatorcomfortissacrificedforgreaterefficiency）.

Second,evenwhereanoperatormayelecttoperformsimpleremedialtaskstoincreasecabpressure,theoperatormaybeunawarethatthepressureproblemcanbecorrectedviasuchsimpletasksandthereforemayforegoperformingthetasks.Forinstance,anoperatormayassumethecabpressureproblemisduetoacloggedfilterthatneedstobereplacedwhichwouldrequireatripoutofthefieldtoamaintenancelocationwhiletherealproblemisanimproperlylatchedcabdoor.Clearlytheburdenoftheperceivedremedyaffectswhetherornotanoperatormayele