Recommandé
Recommandé
Contenu connexe
Tendances
Tendances (20)
En vedette
En vedette (9)
Similaire à A 20-year experience with LMS Amesim: the simulation of positive displacement pumps
Similaire à A 20-year experience with LMS Amesim: the simulation of positive displacement pumps (20)
Dernier
Dernier (20)
A 20-year experience with LMS Amesim: the simulation of positive displacement pumps
- 1. A 20-year experience with LMS Amesim: the simulation of positive displacement pumps Naples, June 27, 2016 Massimo Rundo Politecnico di Torino – Dipartimento Energia Fluid Power Research Laboratory New Trends in Fluid Power Design & Simulation Symposium
- 2. 2/25 FPRL at a glance - 1st course of Fluid Power in Italy (1979) - 1979 - 2016: about 9500 students - From 2014: 2 courses in English at M.Sc. - More than 100 M.Sc. theses - About 100 scientific papers - Development of simulation models of positive displacement machines and valves Research Didactics Laboratory - 1985: construction of the 1st Lab - 2005: completion of the new Lab www.fprl.polito.it
- 5. 5/25 The experience with LMS Amesim ‐ Users since 1995 with v0.3 ‐ 1998: 1st international publication on gerotor pump ‐ 2000: presentation at the 1st AMESim Users’ Conference in Paris ‐ Since 2006 used by the students in didactic laboratories ‐ Several customized libraries created in Ameset
- 6. 6/25 Systems/components studied with Amesim Detailed 1D modelling of positive displacement machines (with customized libraries) • 1997: Gerotor pumps • 1999: External gear pumps • 2000: Swash plate and bent axis pumps, also in cosimulation with MSC Adams (2006) • 2001: Vane pumps, also in cosimulation with MSC Adams (2008) • 2005: Crescent pumps ‐ Swash plate motors • 2012: Single vane vacuum pumps Vehicle systems • 1999: Variable Valve Actuation ‐ Electro hydraulic braking system • 2002: Lubrication circuit, also aeronautical (2001) • 2004: Clutch actuation ‐ Steering units Mobile hydraulics • 2001: Hydrostatic transmissions • 2006: Load sensing proportional valves • 2011: Excavator and telehandler hydraulic circuits (coupled simulation with LMS Virtual Lab) Industrial hydraulics • 2001: Hydraulic power unit for hydroforming system
- 7. 7/257/ Equivalent hydraulic circuit Need to evaluate the geometric features N variable chambers Delivery volume Suction volume Flow areas Flow areas drainInternal leakages J J+1 Gerotor machine Variable chambers The simulation of a positive displacement machine Flow area volume areaarea j‐th chamber • Hydraulic volume: continuity equation • Hydraulic resistance: flow equation
- 9. 9/25 Numerical evaluation of geometric features Procedure valid for any shape of the port plate: profiles are supplied as XY data table port profile Flow area Numerical technique used to calculate the flow area vs. angle: • Discretization of the domain • Calculation of number of elementary cells belonging to both closed lines • Interpolation of the flow area chamber profile Gerotor pump
- 10. 10/25 Automatic CAD method CARCONI G., D’ARCANO C., NERVEGNA N., RUNDO M.: “Geometric Features of Gerotor Pumps: Analytic vs Cad Methods”, Bath/ASME Symposium on Fluid Power & Motion Control, Sept. 12‐14, 2012, Bath, UK Based on commercial CAD software PTC Creo Elements/Pro (formerly Pro/ENGINEER) 1. Creation of: • Assembly parts • Constraints • Global parameters • Relations (correct movement) 2. Creation of virtual parts (fluid volume): • Chamber volume • Suction / Delivery • Inter-sections 3. Evaluation of geometric quantities: • Analysis features • Relational features • Numerical derivation • Simulation area volume
- 11. 11/25 inlet outlet A B Variable flow gerotor pump2000 Early Closing Inlet Port Delayed Closing Delivery Port Timing can be varied with respect to the gearing DCDP The end of the delivery phase is progressively delayed The flow area is also function of the sector position Flow rate vs. sector position NERVEGNA N., MANCO' S., RUNDO M.: “Variable Flow Internal Gear Pump”, ASME International Mechanical Engineering Congress and Exposition, New York, 11‐16 November, 2001 Piston linked to the sector
- 15. 15/25 Interaction between bodies (analytic approach) Contact vane‐stator in a vane pump (detachment analysis) 2001 Force equilibrium on each vane: MANCO' S., NERVEGNA N., RUNDO M., ARMENIO G., “Modelling and Simulation of Variable Displacement Vane Pumps for IC Engine Lubrication”, SAE World Congress, 8‐11 Mar. 2004, Detroit, USA Fr = reaction forces Fp = pressure forces Ff = friction forces Fc = centrifugal force x ( ) ( ) ....mx j cx j Endstops management (contact with stator track) If contact evaluation of contact force on the stator contribution to the stator equilibrium If detachment evaluation of the leakage on vane tip influence on the chamber pressures Small movements of mechanical parts influence on leakages
- 16. 16/25 Multibody simulation (fuel pump) fluid viscosity ≈ 2‐3 cSt The issue: the current positions of the gears axes is critical for the leakages evaluation x y Model in MSC Adams with all clearances: • inner gear – outer gear • inner gear ‐ shaft • outer gear ‐ housing Forces on gears calculated with Amesim 2005 Theoretical eccentricity (not in scale) Amesim output Adams output RIELLO Research Contract, 2006
- 17. 17/2517/ Need of cosimulation Floating ring ICE lubricating vane pump Analysis of vane detachment The issue: interaction vanes‐ring The solution: cosimulation LMS Amesim – MSC Adams LMS Amesim (master) • User interface • Hydraulic model • Solver MSC Adams (slave) Forces on the vanes Vanes and rings positions • Mechanical model • Solver Communication at constant Δt 2008
- 18. 18/25 Adams model by Amesim model by FPRL without bodies dynamics Implementation of cosimulation Output example theoretical vane lift calculated lift Contact force vane root Contact force vane tip Trajectory of ring centre x y Rotor axis (fixed) interface PIERBURG Research Contract, 2008
- 19. 19/25 Vacuum pump for brake booster Rundo, M. and Squarcini, R., "Modelling and Simulation of Brake Booster Vacuum Pumps" SAE Int. J. Commer. Veh. 6(1), 2013 The issue: Fluid mainly air + small % oil pneumatic chamber … but at the end of the delivery phase 100% oil hydraulic chamber Hydraulic‐pneumatic chamber 2012 variable chambers Pump geometry 1c pV x Vc 2 ,p oil airx V V Virtual piston equilibrium Mass conservation ,oil airp p Force on piston 2 1 ?p px xYES air + oil NO only oil oil cV V The equilibrium of the virtual piston adjusts the volume of air/oil so that oil airp p Mass conservation ( , , )oil oil c cp f m V V (purely hydraulic chamber)
- 23. 23/25 1D simulation of lubricating circuit lubrication of each cylinder: • main bearing • piston cooling jet • crankshaft drilled holes • conrod bearing SINGLE OVERHEAD CAMSHAFT DIESEL ENGINE 2003 Circuit layout Load on the bearings (supplied as data file) FURNO F., RUNDO M.: “Simulazione del sistema di lubrificazione di un motore a combustione interna”, 58° Congresso Nazionale ATI, Padova ‐ S. Martino di Castrozza, Italy, 9‐12 September, 2003
- 24. 24/25 Overall flow‐pressure curve Validation: flow rates and pressures 140 °C Oil pump outlet Main gallery Head gallery 90 °C 140 °C90 °C FURNO F., “The Lubrication Network in Internal Combustion Engines: a Simulation Approach”, 3rd FPNI PhD Symposium, Terrassa, Spain, 30 June – 2 July, 2004. continuous lines: simulation dots: experimental values
- 25. 25/25 Some final remarks / curiosities • First model of gerotor pump in 1997 ran on a Sun SparcStation 10 @ 50 MHz ‐ 96 Mb RAM About 2‐3 minutes to simulate a shaft revolution Now about 2 seconds : 2 orders of magnitude smaller !! • In 1997 an entire month spent for the development of the model of a simple relief valve (at that time the Hydraulic Component Design Library in Amesim did not exist !) Now the same valve is built in 30 min by the students of the Fluid Power courses • The nightmare : When you realize that your model no longer runs on the new release of a software !!
- 26. Fluid Power Research Laboratory www.fprl.polito.it Politecnico di Torino