Churning losses and efficiency in gearboxes
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Efficient transmissions systems are key to producing competitive motor vehicles that have a smaller environmental impact. Gears are the main components in vehicle transmissions and although they are already highly efficient, there is still room for improvement. In this study, the focus falls on the lubricant used to create separating films between gears and todissipate heat. When driving, the gears churn this lubricant, giving rise to power losses that are related to the amount and properties of the lubricant. However, any attempt to reduce these losses must not compromise the required lubrication and heat dissipation. Paper A reports on the use of an FZG gear test rig to investigate power losses and heat generation for different gear immersion depths, surface roughness and coatings. The results show that lower gear roughness reduces gear mesh losses and heat generation. A polishing affect was obtained when a non-coated gear ran against a coated gear.The aim of the research reported in paper B was to increase the accuracy of efficiency testing. It investigated how and whether repeated disassembly and re-assembly of the same test equipment, as well as test performance and rig conditions, affect the measured torque loss in an FZG gear test rig. It was shown that the measured torque loss changes between one assembly and another. Repeatability between tests is crucial for accurate conclusions.The aim of the research reported in paper C was to study whether gear efficiency could be increased by a running-in procedure, which would reduce the need for a coolant. A back-to-back gear test rig was used to test two running-in loads. Higher gear mesh efficiency was seen when a higher running-in load was used.
Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. , 22 p.
TRITA-MMK, ISSN 1400-1179 ; 2014:11
gears, efficiency, temperature, running-in, assembly, torque loss, surface roughness
IdentifiersURN: urn:nbn:se:kth:diva-152914ISBN: 978-91-7595-277-2OAI: oai:DiVA.org:kth-152914DiVA: diva2:752030
2014-10-23, Sal B242, Brinellvägen 85 KTH, Stockholm, 10:00 (English)
Alfredsson, Bo, Professor
Olofsson, Ulf, ProfessorBjörklund, Stefan, UniversitetslektorSellgren, Ulf, Universitetsadjunkt
FunderSwedish Energy Agency
QC 201410062014-10-062014-10-022014-10-06Bibliographically approved
List of papers