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1.Definition,systematicsandmethodologyofdesigninghydraulicgearmachines
-thedesignsolutionforthegearsystem,
-thedesignsolutionforthesystemofthechannelsandclearances.
Itisalsonecessarytodeterminethevaluesofthebasictechnicalparameterswhich
themachineissupposedtofeature.
Atthesecondstage,ananalysisofenergytransformationintheHGMiscarriedout,
whichFigure1.3depictswiththearrow-headlineontheinletandtheoutlet,
whichgoesthroughtheinsideofthemachine.Thisstageconsistsindeveloping
anenergymodelofthemachine,analysingitsenergybalance,andindevelopingantici-
patedcharacteristics,whicharerelatedtothetechnicalparametersofthemachine
assumedatstage1.
Atthethirdstage,agearsystemoftheHGMisdesigned,whichFigure1.3pre-
sentsinaformofacirclewiththeblackenedintertoothdisplacementchamber.
Thedesigningincludesthegeometryandkinematicsofthegearsystem,inorder
tominimizethedimensionsofthegearsystemandtomaximizethevolumeof
theintertoothdisplacementchambers.
Atthefourthstage,thesystemofchannelsandclearancesoftheHGMisdesigned,
whichFigure1.3presentsaslinesedgingthegearsystem.Thetaskofthesystem
istosupplyanddischargetheworkingfluidtoandfromtheintertoothdisplacement
chamberswhilethemachineisoperating.Asithasalreadybeenmentionedabove,
itcanbeeitherafixedoramoveablesystem.
Thesystemconsistsof:
-achannel,achamberandaninletbridge,
-achannel,achamberandanoutletbridge,
-anaxialandradialclearance.
Thequestionsoftheprimaryconcernatthedesigningoftheinternalchambers
andclearancessystem,aretosecurecontinuityoftheflow,tominimizetheflowresist-
ance,toeliminatethecavitationphenomenaandtominimizeinternalleakage.
Atthefifthstage,thedisplacement(capacity)Qandofthedisplacementpulsa-
tion(capacity)QoftheHGMarecalculated,whichinFigure1.3arepresentedin
aformofareferencemarkdirectedtowardstheoutletportofthemachine.Thecal-
culationsarecarriedoutbasingonthegearsystemwithitsgeometryandkinematics
definedatstage3.Accordingtothedesignedgearsystem,specificformulae
areapplied.Theformulaeallowtodeterminetheeffectofthegearsystemonthedis-
placement(capacity)andonthepulsationofthedisplacement(capacity).
Atthesixthstage,atheoreticalanalysisofpressurepandpulsationofpressurep
intheintertoothdisplacementchamberoftheHGMinthefullworkingcycle
iscarriedout,whichFigure1.3presentsinaformofareferencemarkdirectedtowards
theoutletportofthemachine.Theanalysisiscarriedouttotesttheaccuracyof
co-operationofthegearsystemandthesystemoftheinternalchambersand
clearances.