CAE-Based Strategies to Improve Reliability of Variable Oil Pumps

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
Riccardo.Maccherini@it.kspg.com
Padmesh Mandloi
ANSYS
Padmesh.Mandloi@ansys.com

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

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

Pump Design Process
4
Performance
Pump
Characterization
Pump
Optimization
Reliability
Structural
Integrity
Fatigue Life
Vibrational
Behavior
Dynamic
Behavior
Sealing
Verification
Noise
Aeroacoustics Vibroacoustics
1D & 3DCFD
FEA
Multiphysics

Variable Oil Pump - Advantage
5
 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

Variable Oil Pump – Conventional Type
6
• 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.

Variable Oil Pump – Genesis of the
Product
7
Customer SOR
• Oil Flow Rate Requirement
• Oil Pressure Requirement
• The Minimum Absorbed Energy

Variable Oil Pump – Design Loop
8
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!

Variable Oil Pump - Performance
9
Lumped Parameters
Simulation
Equivalent hydraulic circuit build with
custom & standard sub-models.
Output results: instantaneous pressure -
flow - torque values in different pump areas

Variable Oil Pump - Performance
10
Output result: prediction of the cavitation
CFD Analyses

Variable Oil Pump - Reliability
11

Multi-Body Dynamic Analyses
12
Output results:
 Exchanged Forces
 Components Velocity
 Components Accelerations

Structural Analyses
13
Deformations
Stresses
 Linear analyses
 Non-linear analyses (contacts,
material plasticity, large strain)

Structural Analyses
14
Coarse Model
Sub-Model
Sub modelling (detail analyses)

Lifetime Prediction
15
Real Crack
 Classical theoretical approach
(Goodman, Haigh, Soderberg, …)
 Advanced theoretical approach
(Sines, Critical plane, Dang Van, …)
 Miner’s cumulative damage ratio
Virtual Crack

Multi-axial Fatigue Analyses
16
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

Sealing Analyses
17
 Full 3D approach
 Pre-stress effects
 Mesh rezoning

Sealing Analyses
18
 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

Output results:
 Contact pressure
 Bending stress on teeth
Gear Design Optimization
19

20
Structural Resonance
Experimental/Numerical Correlation
Modal Analyses
1st Frequency

21
Structural Resonance
Optimization of the pump structure
Modal Analyses
1st Frequency (New)

22
FEA Dynamic Analyses
Spectrum & PSD
Analyses
Transient Analyses

Acoustic Simulations
23
FEM Modal Analysis Vibrational Modes
CFD Results INPUT SIGNAL
Output results
 dB Sound Power
 Emission Type
 Noise Radiation

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
24
weak design engine conditions

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
25

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).
26
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.

• 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

• 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

Thank You!

CAE-Based Strategies to Improve Reliability of Variable Oil Pumps

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