Sökning: "valve wear"

Visar resultat 1 - 5 av 11 avhandlingar innehållade orden valve wear.

1. 1. Combustion Valve Wear : A Tribological Study of Combustion Valve Sealing Interfaces

   Författare :Peter Forsberg; Staffan Jacobson; Rob Dwyer-Joyce; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Combustion valves; wear; tribofilm; test rig; combustion residue; Teknisk fysik med inriktning mot tribomaterial; Engineering Science with specialization in Tribo Materials;

   Sammanfattning : The exhaust valve system of combustion engines experiences a very complex contact situation of frequent impact involving micro sliding, high and varying temperatures, complex exhaust gas chemistry and possible particulates, etc. In addition, the tribological situation in the exhaust valve system is expected to become even worse due to strict future emission regulations, which will require enhanced combustion and cleaner fuels. LÄS MER

3. 2. Friction and wear in rolling and sliding contacts

   Författare :Christer Spiegelberg; Sören Andersson; Roland Larsson; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; tribology; friction; wear; rolling and sliding contacts; Engineering mechanics; Teknisk mekanik;

   Sammanfattning : Mechanical products are always expected to perform better, last longer, be more environmentally friendly and preferably cost less. Rolling and sliding contacts are found in many mechanical products, and friction and wear in the contacts have a direct impact on the products’ ability to meet these demands. LÄS MER

4. 3. Protective Tribofilms on Combustion Engine Valves

   Författare :Robin Elo; Staffan Jacobson; Mikael Åstrand; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Internal combustion engine; valve; sealing surface; tribofilm; oil residue; test rig; Teknisk fysik med inriktning mot tribomaterial; Engineering Science with specialization in Tribo Materials;

   Sammanfattning : Inside the complex machinery of modern heavy-duty engines, the sealing surfaces of the valve and valve seat insert have to endure. Right next to the combustion, temperatures are high and high pressure deforms the components, causing a small relative motion in the interface. LÄS MER

5. 4. Wear resistant low friction coatings for engine components

   Författare :Per Lindholm; Sören Andersson; Rickard Larker; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Engineering materials; cam; roller follower; carbon coating; engine test; finite element method; Konstruktionsmaterial; Construction materials; Konstruktionsmaterial;

   Sammanfattning : Engine development today is driven by cost, performance and government regulations. Customers want cars and trucks to consume less fuel, last longer, pollute less and be safer. Several of the requirements have tribological associations. For example, product longevity can be improved by lowering friction and using more wear-resistant components. LÄS MER

7. 5. Aortic valve calcification : in vivo and ex vivo evaluation

   Författare :Mohamed Yousry; Karolinska Institutet; Karolinska Institutet; []
   Nyckelord :;

   Sammanfattning : Aortic valve calcification (AVC) or thickening is found in around one fifth of the general population between 65-75 years of age and increasingly thereafter. The process of aortic valve thickening and calcification is not only an aging (wear and tear) process of the valve leaflets. It is now considered to be closely related to atherosclerosis. LÄS MER