VDMA, Hannover 2017

Rotary slipper seals, physical limitations

2

Starved / non-existing

lubrication

High power-density

Potential seals rotation in

housing groove

Potential rotation between

seal parts

Temperature mainly limited

by hardware heat dissipation

No fluid exchange in contact

area

No removal of wear products

High mechanical loads on

rotary part

Practical considerations

3

Hardware

• Closed, symmetric

housing groove

• Standard groove

dimensions preferred

• Avoid back-to-back seals

installation between

channels

• Avoid internal drains

between channels

Seal

• Simple installation across

wide diameter range

• Suitable for high

temperature materials

• Suitable for fluid separation

• Symmetric, bi-directional

design preferred

• Uni-directional seal should

have poka-yoka features /

or positioning should be

verifiable

Prevention of seals rotation

4

Mechanical

Retention

Clamping

• Unidirectional

• Complicated

hardware

Lock seal

parts together

Bonding

• Poor installation

• Complicated

manufacturing

Reduce friction

Pressure balancing

• Not generally

bidirectional

• Assembly of

unidirectional seals

difficult to verify

Reduction of dynamic friction

5

By supporting fluid

film formation in the

contact area

And/or by introducing

pressure balancing

Bi-directional pressure-balancing

6

Existing concepts

+ O-ring automatically opens

high-pressure port

- Valve function highly sensitive

to tolerances

- Fundamentally less suited to

standard housing grooves

+ Pressure tilts seal body and

reduces pressurized contact

width

- Bi-directional function sensitive

to deformation in service

- Less suited for material with

low elasticity e.g. PTFE

Bi-directional pressure-balancing

7

Concept development

Standard rotary seal

design

Pressure ports close

against groove wall

Design idea

Bigger ports

Internal valve

element (O-Ring)

Refined contact

faces

Development

O-ring replaced by

Quadring

Further changes to

seal body

Final

Finalized design

8

Rotary seal performance, torque / time

9

All test results with mineral oil HLP46 and seal material Turcon M15

unless otherwise noted

0,00

1,00

2,00

3,00

4,00

5,00

0 50 100 150 200

Nm

Time (h)

50 mm shaft / 50 bar x 1 m/s

RTG

RTG-K

New Concept / RTG-V

0

1

2

3

4

5

6

7

8

0 50 100 150 200

Nm

Pressure (bar)

50 mm Shaft seal / 0,6 m/s

RTG

RTG-K

New Concept / RTG-V

Rotary seal performance, torque / pressure

10

0

10

20

30

40

0 50 100 150 200

Gram

Time (h)

50 mm Shaft seal / 50 bar x 1 m/s

RTG

New Concept / RTG-V

RTG-K

Rotary seal performance, Leakage / time

11

Rotary seal performance, Seal wear

12

50 mm shaft, 50 bar x 1 m/s, 200 hours

0

2

4

6

8

10

12

14

Sea

l ri

ng

wei

gh

t lo

ss [

wt%

]

RTG RTG-K New concept / RTG-V

0

2

4

6

8

10

12

14

O-R

ing

wei

gh

t lo

ss [

wt%

]

RTG RTG-K New concept/ RTG-V

Rotary seal performance, hardware wear

13

50 mm shaft, 50 bar x 1 m/s, 200 hours, pressure from left

Existing single-acting (RTG-K) New Concept / RTG-V

0

50

100

150

200

250

300

350

0 0,5 1 1,5 2 2,5 3 3,5

Bar

m / s

New Concept / RTG-V

RTG

Rotary seal performance, Limits

14

Limits for shafts ≥ Ø 50

Thank you for your attention