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Schoemacker, Florian 3/19/2018 Schoemacker, Florian Murrenhoff, Hubertus Piston Slippers for Robust Water Hydraulic Pumps n 1
Schoemacker, Florian
3/19/2018
Schoemacker, Florian
Murrenhoff, Hubertus
Piston Slippers for Robust Water Hydraulic Pumps
n
1
Schoemacker, Florian
3/19/2018
Motivation
Water Hydraulics
2
Not flammable
Not toxic
Good availability of
tap water
Advantages
Low viscosity
Poor lubrication
Different materials
Complex components
Challenges
Food industries
Pharmaceutic industries
Mining
Descaling
Applications
Plunger pumps
Axial piston pumps
Radial piston pumps
Schoemacker, Florian
3/19/2018
Research at IFAS
Development of water hydraulic radial piston pump
– Tap water as pressure medium
– Water lubrication
– Pressure level > 160 bar
Increased power density
Tribological contacts
– Load carrying capacity
– Leakage, wear
Simulation development
Comparison of piston slippers
– Axial piston pump
– Radial piston pump
3
120
110
100
90
80
70
60
50
40
30
200 50 100 150 200 250 300 350
pressure (bar)
flo
w r
ate
(l/m
in)
3730221511 power supply (kW)
oil
water
Schoemacker, Florian
3/19/2018
1
2
3
4
Introduction
Simulation Model and Results
Conclusion and Outlook
Effect of Slipper Deformation
4
Schoemacker, Florian
3/19/2018
Reynold-Equation in Polar Coordinate System
5
𝜕
𝜕𝑟𝑟 ∙
ℎ3
12 ∙ 𝜇∙𝜕𝑝
𝜕𝑟+
𝜕
𝜕𝜑
ℎ3
12 ∙ 𝜇∙1
𝑟∙𝜕𝑝
𝜕𝜑−
𝑢𝑟2
∙ 𝑟 ∙𝜕ℎ
𝜕𝑟−
𝑢𝜑
2∙𝜕ℎ
𝜕𝜑=
𝜕ℎ
𝜕𝑡= 0
Reynolds-Equation
– Newtonian fluid
– Incompressible fluid
– Laminar flow with Re
Schoemacker, Florian
3/19/2018
Slipper geometry
Axial piston pump (APP)
Radial piston pump (RPP)
6
𝑞𝐶,𝑒𝑓𝑓 =𝐹𝐹𝑙𝑢𝑖𝑑𝐹𝑃𝑖𝑠𝑡𝑜𝑛
= 𝑝(𝑟,φ) ∙ 𝑑𝐴
𝑝𝐻𝑃 ∙ 𝐷𝑃𝑖𝑠𝑡𝑜𝑛2 ∙
𝜋4
Calculation of hydrostatic compensation
Load carrying capacity
Leakage
Comparison of Piston Slippers
DSlipper DSlipper
DPocket DPocket
DPiston
𝑄𝐿𝑒𝑎𝑘𝑎𝑔𝑒 = 𝑄𝑝 + 𝑄𝑣 𝑟=𝐷𝑃𝑜𝑐𝑘𝑒𝑡 2
10 µm
∆𝑅 = 𝑅𝐶𝑢𝑟𝑣𝑒 − 𝑅𝐸𝑐𝑐
20 µm
APP RPP
Schoemacker, Florian
3/19/2018
Slipper geometry
Axial piston pump (APP)
Radial piston pump (RPP)
7
𝑞𝐶,𝑒𝑓𝑓 =𝐹𝐹𝑙𝑢𝑖𝑑𝐹𝑃𝑖𝑠𝑡𝑜𝑛
= 𝑝(𝑟,φ) ∙ 𝑑𝐴
𝑝𝐻𝑃 ∙ 𝐷𝑃𝑖𝑠𝑡𝑜𝑛2 ∙
𝜋4
Calculation of hydrostatic compensation
Load carrying capacity
Leakage
Comparison of Piston Slippers
DSlipper DSlipper
DPocket DPocket
DPiston
𝑄𝐿𝑒𝑎𝑘𝑎𝑔𝑒 = 𝑄𝑝 + 𝑄𝑣 𝑟=𝐷𝑃𝑜𝑐𝑘𝑒𝑡 2
10 µm
∆𝑅 = 𝑅𝐶𝑢𝑟𝑣𝑒 − 𝑅𝐸𝑐𝑐
20 µm
APP RPP
piston
slipper
Pressure
distribution
eccentric shaft
pHP
pCase
Schoemacker, Florian
3/19/2018
Dynamic Pressure Build-Up during Motion
Calculation of dynamic pressure build-up
– Lateral movement of piston-slipper-assembly
– Slipper is tilted against plane surface
Hydrodynamic compensation
Leakage
Additional tilting torque
8
piston
slipper
pressure pHP
pressure distribution
𝑞𝐶,𝑒𝑓𝑓 =𝐹𝐹𝑙𝑢𝑖𝑑𝐹𝑃𝑖𝑠𝑡𝑜𝑛
= 𝑝(𝑟,φ) ∙ 𝑑𝐴
𝑝𝐻𝑃 ∙ 𝐷𝑃𝑖𝑠𝑡𝑜𝑛2 ∙
𝜋4
𝑇𝑇𝑖𝑙𝑡 = 𝑝(𝑟,φ) ∙ 𝑟 ∙ cos 𝜑 ∙ 𝑑𝐴
𝑇𝑇𝑖𝑙𝑡
Gap height: 0.5 µm
Angle 𝛽: 0.001° Pressure: 100 bar
Velocity: 1 m/s
Simulation parameter
Velocity
𝑄𝐿𝑒𝑎𝑘𝑎𝑔𝑒 = 𝑄𝑝 + 𝑄𝑣 𝑟=𝐷𝑃𝑜𝑐𝑘𝑒𝑡 2
Schoemacker, Florian
3/19/2018
0
10
20
30
40
50
60
70
80
90
100
6.5 7 7.5 8 8.5 9 9.5 10
Pre
ssure
(bar)
Radius (mm)
APP
RPP ΔR=10 µm
RPP ΔR=20 µm
Results
9
Static, no motion
APP RPP
∆𝑹 = 10 µm RPP
∆𝑹 = 20 µm
𝑞𝐶,𝑒𝑓𝑓 93.2 % 91.6 % 89.8 %
𝑄𝐿𝑒𝑎𝑘𝑎𝑔𝑒 100 % (0.088
ml/min)
176 %
(0.155
ml/min)
300 %
(0.264
ml/min)
Schoemacker, Florian
3/19/2018
0
10
20
30
40
50
60
70
80
90
100
6.5 7 7.5 8 8.5 9 9.5 10
Pre
ssu
re (
ba
r)
Radius (mm)
APP
RPP ΔR=10 µm
RPP ΔR=20 µm
Results
10
Static, no motion
Dynamic APM RPM
APP RPP
∆𝑹 = 10 µm RPP
∆𝑹 = 20 µm
𝑞𝐶,𝑒𝑓𝑓 93.2 % 91.6 % 89.8 %
𝑄𝐿𝑒𝑎𝑘𝑎𝑔𝑒 100 % (0.088
ml/min)
176 %
(0.155
ml/min)
300 %
(0.264
ml/min)
𝑞𝐶,𝑒𝑓𝑓 = 94.2 %
𝑄𝐿𝑒𝑐𝑘𝑎𝑔𝑒 = 0.617 ml/min
𝑞𝐶,𝑒𝑓𝑓 = 93.3 %
𝑄𝐿𝑒𝑐𝑘𝑎𝑔𝑒 = 0.837 ml/min
Schoemacker, Florian
3/19/2018
1
2
3
4
Introduction
Simulation Model and Results
Conclusion and Outlook
Effect of Slipper Deformation
11
Schoemacker, Florian
3/19/2018
Deformation of Slipper
Effects of using plastic materials
– Deformation of materials under pressure load
– Altered gap height distribution
– Increased leakage due to enlarged gap height
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Simulation
– Deformation in Ansys
– Matlab-Code for
Reynolds-Equation
steel body
steel body PEEK
sliding disc
µm
Schoemacker, Florian
3/19/2018
Results
13
Increased load carrying capacity due to over
compensation
Leakage increased by factor 5 compared to
undeformed result
steel body PEEK
sliding disc
Gap height Pressure distribution
𝑞𝐶,𝑒𝑓𝑓 = 106.7 %
𝑄𝐿𝑒𝑎𝑘𝑎𝑔𝑒 = 0.81 ml/min
Simulation results
Schoemacker, Florian
3/19/2018
Results
14
Increased load carrying capacity due to over
compensation
Leakage increased by factor 5 compared to
undeformed result
steel body PEEK
sliding disc
Gap height Pressure distribution
𝑞𝐶,𝑒𝑓𝑓 = 106.7 %
𝑄𝐿𝑒𝑎𝑘𝑎𝑔𝑒 = 0.81 ml/min
Simulation results
Deformed Undeformed
Schoemacker, Florian
3/19/2018
1
2
3
4
Introduction
Simulation Model and Results
Conclusion and Outlook
Effect of Slipper Deformation
15
Schoemacker, Florian
3/19/2018
Conclusion and Outlook
Simulation of piston slippers
Radial piston pump
– Effect of manufacturing tolerances
Lower load carrying capacity
Deformation of plastic slippers
– Same magnitude as gap height
– Overcompensation
– Increased leakage
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steel body PEEK
sliding disc
Maximum pressure level for water hydraulics
Development water hydraulic
radial piston pump
piston
slipper
pressure pHP
pressure distribution
Schoemacker, Florian
3/19/2018
Thank you for your attention!
Contact:
17
Schoemacker, Florian
