On friction reduction in rubber lip seals for rotating shafts
✍ Scribed by Gawliñski Marek
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 368 KB
- Volume
- 1997
- Category
- Article
- ISSN
- 1350-4789
No coin nor oath required. For personal study only.
✦ Synopsis
Rubber lip seals are widely used in the automotive industry, for sealing marine stern tubes, drainage pumps and as the seals built in to roller bearings. All seal users have the same requirements irrespective of usage: tightness and high durability.
Seal durability t is inversely proportional to the frictional losses Ill:
t =Wt
Wr
where Wt -energy which the seal can absorb in its lifetime, Wrenergy spent to overcome frictional losses.
Almost all energy spent to overcome frictional losses is converted into heat. The area density of heat flux in contemporary lip seals for crankshafts varies within 8-12 W/ram 2 at linear shaft speed exceeding 20 m/s and oil temperature above 110°C. Because of limited flow round the lip and due to insufficient heat conduction, the underlip temperature -at this heat flux -considerably increases. The underlip temperature can reach 160 -185°C in the rear crankshaft lip seal. It is generally accepted fact that a temperature increase of 10 ° almost doubles the speed of chemical reaction in the rubber being and is also responsible for rubber ageing. Temperature increase at lip-shaft interface has many negative effects leading to...