cae-based strategies to improve reliability of variable oil pumps
TRANSCRIPT
1 © 2014 ANSYS, Inc. May 20, 2014 ANSYS Confidential
CAE Based Strategies to Improve Reliability of Variable Oil Pumps
Riccardo Maccherini
Pierburg Pump Technology, KSPG Automotive
Padmesh Mandloi
ANSYS
2 © 2014 ANSYS, Inc. May 20, 2014 ANSYS Confidential
Key Vehicle Systems Are Undergoing Drastic Changes To Reduce Carbon Footprints
Reduce Carbon Footprint
Aerodynamics
Road Resistance
Powertrain
HEV/EV Thermal
Management Energy
Leightweight
Design Energy Recovery
3 © 2014 ANSYS, Inc. May 20, 2014 ANSYS Confidential
Warranty Expenses Due to Increasingly Complex And Interdependent Automotive Systems
Warranty Reduction
KBI
Early introduction of quality and
reliability prediction system
Innovative manufacturing
processes
Insights into system
level interdependencies
Courtesy of Pierburg Pump Technology Italy SpA
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Pump Design Process
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Performance
Pump Characterization
Pump Optimization
Reliability
Structural Integrity
Fatigue Life Vibrational Behavior
Dynamic Behavior
Sealing Verification
Noise
Aeroacoustics Vibroacoustics
1D & 3DCFD
FEA
Multiphysics
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Variable Oil Pump - Advantage
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Reduction of the energy consumption: this is also valid for engines’
accessories!
VOP: an innovative concept of oil pump
Up to 3% CO2 saving in the
NEDC cycle
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Variable Oil Pump – Conventional Type
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• Features:
– Vane pump.
– Displacement controlled by the linear (or pivoting) movement of the control ring driven by the pressure signal.
– Continuous control of the volume of the working chamber.
– Simple design, few components.
– Pressure working directly on the volume control system.
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Variable Oil Pump – Genesis of the Product
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Customer SOR
• Oil Flow Rate Requirement • Oil Pressure Requirement • The Minimum Absorbed Energy
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Variable Oil Pump – Design Loop
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VOP design
1 2 3 4 5 6 7 8 Suggested
Shaft diameter d [mm] 10.00 10.00 10.00 10.00 10.00 12.00 12.00 10.00 >10
Max eccentricity e [mm] 3.00 3.00 3.00 3.00 3.00 2.70 2.37 3.00
Vane inside rotor i [mm] 3.60 6.00 6.00 6.00 6.00 5.00 5.34 6.00
Rotor - hub thickness s [mm] 3.00 4.00 4.00 4.00 4.00 3.70 3.70 4.00
Rotor collar max thickness p [mm] 3.10 3.00 3.00 3.00 3.00 0.30 0.64 3.00 >3,0
"Small" ring thickness b [mm] 2.50 2.50 2.50 2.50 2.50 0.30 0.64 2.50 >2,5
Vane - rotor slot f [mm] 0.50 0.30 0.30 0.30 0.30 0.30 0.64 0.30 >0,3
Rotor - control ring g [mm] 0.50 0.30 0.30 0.30 0.30 0.30 0.64 0.30 >0,3
"Small" ring - shaft n [mm] 1.00 1.80 1.80 1.80 1.80 3.70 3.70 1.80 >0,3
"Small" ring - rotor m [mm] 0.50 3.00 3.00 3.00 3.00 4.70 4.70 3.00 >0,3
Rotor external diameter dr [mm] 36.200 42.600 42.600 42.600 42.600 40.800 40.800 42.600
Control ring internal diameter da [mm] 43.200 49.200 49.200 49.200 49.200 46.800 46.800 49.200
Vane length h [mm] 10.100 12.300 12.300 12.300 12.300 10.700 10.700 12.300
Vane length outside rotor slot a [mm] 6.500 6.300 6.300 6.300 6.300 5.700 5.365 6.300
Percentage of length outside rotor slot % 64.4 51.2 51.2 51.2 51.2 53.3 50.1 51.2 <55%
"Small" ring diameter c [mm] 23.000 24.600 24.600 24.600 24.600 25.400 25.400 24.600
Ratio e/D e/D [adim] 0.0694 0.0610 0.0610 0.0610 0.0610 0.0577 0.0505 0.0610 <0,055
Required displacement C [cc/rev] 20.17 20.00 20.00 20.00 20.00 20.00 20.00 20.00
Vane number N [adim] 7 7 7 7 7 7 7 7
Vane thickness w [mm] 2 2 2 2 2 2 2 2
Max head radius for vane rmax [mm] 5.40 6.15 6.15 6.15 6.15 6.32 6.95 6.15
Max area Amax [mm2] 109.749 123.572 123.572 123.572 123.572 105.818 98.950 123.572
Min area Amin [mm2] 8.166 6.361 6.361 6.361 6.361 5.943 11.458 6.361
N*(Amax-Amin) [mm2] 711.081 820.477 820.477 820.477 820.477 699.124 612.446 820.477
Pump height 28.365 24.376 24.376 24.376 24.376 28.607 32.656 24.376
Pump height (rounded) 28.4 24.4 24.4 24.4 24.4 28.6 32.7 24.4 < 35
Delivery pressure Pd [bar] 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00
Area of vane outside rotor slot A [mm2] 184.600 153.720 153.720 153.720 153.720 163.020 175.436 153.720
Total force on vane outside rotor slot F [N] 92.30 76.86 76.86 76.86 76.86 81.51 87.72 76.86
Unit pressure on vane punit [N/mm] 3.250 3.150 3.150 3.150 3.150 2.850 2.683 3.150
---Input data
---Output data
Data - Main geometric parameters
Data - Displacement
Results - Height
H [mm]
Data & Results - Clearances
Results - Main geometric dimensions
Preliminary verifications
Optimization of the geometry best design
Best Pump!
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Variable Oil Pump - Performance
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Lumped Parameters Simulation
Equivalent hydraulic circuit build with custom & standard sub-models.
Output results: instantaneous pressure - flow - torque values in different pump areas
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Variable Oil Pump - Performance
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Output result: prediction of the cavitation
CFD Analyses
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Variable Oil Pump - Reliability
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Multi-Body Dynamic Analyses
Variable Oil Pump - Reliability
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Output results:
Exchanged Forces Components Velocity Components Accelerations
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Structural Analyses
Variable Oil Pump - Reliability
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Deformations
Stresses
Linear analyses
Non-linear analyses (contacts, material plasticity, large strain)
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Structural Analyses
Variable Oil Pump - Reliability
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Coarse Model
Sub-Model
Sub modelling (detail analyses)
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Lifetime Prediction
Variable Oil Pump - Reliability
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Real Crack
Classical theoretical approach (Goodman, Haigh, Soderberg, …)
Advanced theoretical approach (Sines, Critical plane, Dang Van, …)
Miner’s cumulative damage ratio
Virtual Crack
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Multi-axial Fatigue Analyses
Variable Oil Pump - Reliability
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The PPT F – Code Tool
Dynamic Loads
Sampling Results Data
Multi Body Simulation
Structural Analyses
Equivalency Criterion Choice
Rainflow Algorithm
Palmgren – Miner Hypothesis
Are Stress Principal Directions Varyimg?
ANSYS Plot of μ Parameter
No Yes
Life in Every Node
Proportional Fatigue?
Material Data
Import Data MatLab/SCILAB
Proportional and not proportional fatigue evaluation
Total load cycles by means of Rainflow algorithm
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Sealing Analyses
Variable Oil Pump - Reliability
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Full 3D approach
Pre-stress effects
Mesh rezoning
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Sealing Analyses
Variable Oil Pump - Reliability
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Mono-dimensional approach
“Bed” of springs
Linear or not linear springs
gasket 3D model
load – crush curve
spring elements modelling the
gasket
resulting sealing force
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Output results:
Contact pressure
Bending stress on teeth
Gear Design Optimization
Variable Oil Pump - Reliability
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Variable Oil Pump - Reliability
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Structural Resonance
Experimental/Numerical Correlation
Modal Analyses
1st Frequency
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Variable Oil Pump - Reliability
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Structural Resonance
Optimization of the pump structure
Modal Analyses
1st Frequency (New)
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Variable Oil Pump - Reliability
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FEA Dynamic Analyses
Spectrum & PSD Analyses
Transient Analyses
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Acoustic Simulations
Variable Oil Pump - Reliability
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FEM Modal Analysis Vibrational Modes
CFD Results INPUT SIGNAL
Output results
dB Sound Power Emission Type Noise Radiation
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The increased “know how” gained in different simulation areas like the FEM, CFD and MBA has allowed to run complex combined simulations. These skills gives the possibility to manage difficult situation during the product development.
fluid dynamics analysis (CFD) internal pressure peaks
dynamical analysis (MBA) contact forces crankshaft-rotor structural analysis (FEM) lifetime prediction
or
PROBLEM: crack on a VOP rotor.
Cause of the failure ?
Variable Oil Pump – Example of a Successfully Solved Problem
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weak design engine conditions
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Dynamic analysis was run in order to evaluate contact forces between crankshaft and rotor under crankshaft torsional vibration (measured directly on the engine). Clear effect of high unexpected vibration of the new engine against an existing application were highlighted.
Crankshaft mounted camera
New engine Old engine
Variable Oil Pump – Example of a Successfully Solved Problem
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26 © 2014 ANSYS, Inc. May 20, 2014 ANSYS Confidential
Calculated loads on shaft has been used to evaluate the lifetime of the component.
mesh internal stresses submodeling fatigue life
At the end of this activity it was shown that the problem was engine related (excessive crankshaft torsional vibrations).
Variable Oil Pump – Example of a Successfully Solved Problem
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Customer worked to reduce the amplitude of torsional vibrations by tuning the engine (crankshaft modifications, new damper, etc).
No re-design of the pump was necessary. No additional costs for PPT.
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• The present work has shown some possible numerical analyses which can be performed to design, optimize and verify a generic variable oil pump, in order to have a successful product with a reasonable cost.
• Thanks to CAE software, all of the numerical evaluations are executed without the building of any prototype, with a great economy in terms of materials and money.
• Thanks to the virtual prototyping it’s possible to explore “unusual” working loads, not reachable with experimental tests, in order to verify the pump also outside from the nominal conditions.
• Finally, it is worth noting the great flexibility of the current CAE software, like ANSYS, which permit a complete multidisciplinary approach in designing and verifying whatever mechanical component, providing reliable results in short time
Conclusions
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28 © 2014 ANSYS, Inc. May 20, 2014 ANSYS Confidential
• Simulation Driven Design and Development of a Variable Vane Pump has been presented
• ANSYS provides simulation based solutions for every aspect of pump analysis
• Concepts discussed here can be applied to all types of positive displacement and centrifugal pumps
Summary
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Thank You!