http://www.ukintpress-conferences.com/uploads/SPKEX13/Day1_4_Omar_Milan.pdf
Mahle conference paper on thermal and oil flows in crankshaft bearings, plus changes in design to reduce lubricant pump capacity.
Some pertinent points:
Page 3 shows a "safe operation range"...(for explaination, that line to the right "oil film stability" is where the film is typically too thick for the load, and things like whip and whirl take place)
Page 5 gives indicative pressures in a bearing...note that a 60psi oil pump can't compete with the pressures in the oil wedge...the oil pump is only supplying oil to the bearings, the bearings draw from that supply what they need.
Page 6. heat generated through shearing in the mains, flows into the block (plus carried away with side leakage and convection to windage).
Page 6. heat generated through shearing in the big ends flows through the crank and into the mains (plus carried away with side leakage and convection to windage).
Page 9. Shows measured oil flows and temperature rises across bearings, both plain, semi grooved, and full grooved. Flow and temperature rise with RPM.
* Full grooved bearings flow more, and have less temperature rise. (Reason being, and it's not explained in the paper is that a full grooved bearing sits "lower", as it're really two very narrow bearings...holds less load than a plain shell...and the clearance at the top (feed end) is greater, letting more oil out.
* Do some mental arithmetic, and although the full grooves flow more, and run cooler, the delta T X Volume means that about the same overall heat needs to be dissipated with either strategy...one uses a LOT less oil in circulation 'though.
P10/11, shows crank drilling changes on a 3 cylinder engine that allows changes in bearing design, offering a 15% reduction in crank oil supply requirement.
P12 to 14, shows oil distribution volumes in a 4 cylinder diesel. Then same crank drilling changes as previous section, and measured results...45% reduction in crank flows possible through drilling/bearing changes.
Page 15 some flow to big ends. A little ambiguous, but I think the left chart "measured" is a centre drilled oil supply, and the red "measured" on the right with a traditional oiling, showing drop off at higher RPM...(presumably as the centrifugal effect of the drilling has an impact ???)
Balance some discussion on CFD and it's limitations.
Mahle conference paper on thermal and oil flows in crankshaft bearings, plus changes in design to reduce lubricant pump capacity.
Some pertinent points:
Page 3 shows a "safe operation range"...(for explaination, that line to the right "oil film stability" is where the film is typically too thick for the load, and things like whip and whirl take place)
Page 5 gives indicative pressures in a bearing...note that a 60psi oil pump can't compete with the pressures in the oil wedge...the oil pump is only supplying oil to the bearings, the bearings draw from that supply what they need.
Page 6. heat generated through shearing in the mains, flows into the block (plus carried away with side leakage and convection to windage).
Page 6. heat generated through shearing in the big ends flows through the crank and into the mains (plus carried away with side leakage and convection to windage).
Page 9. Shows measured oil flows and temperature rises across bearings, both plain, semi grooved, and full grooved. Flow and temperature rise with RPM.
* Full grooved bearings flow more, and have less temperature rise. (Reason being, and it's not explained in the paper is that a full grooved bearing sits "lower", as it're really two very narrow bearings...holds less load than a plain shell...and the clearance at the top (feed end) is greater, letting more oil out.
* Do some mental arithmetic, and although the full grooves flow more, and run cooler, the delta T X Volume means that about the same overall heat needs to be dissipated with either strategy...one uses a LOT less oil in circulation 'though.
P10/11, shows crank drilling changes on a 3 cylinder engine that allows changes in bearing design, offering a 15% reduction in crank oil supply requirement.
P12 to 14, shows oil distribution volumes in a 4 cylinder diesel. Then same crank drilling changes as previous section, and measured results...45% reduction in crank flows possible through drilling/bearing changes.
Page 15 some flow to big ends. A little ambiguous, but I think the left chart "measured" is a centre drilled oil supply, and the red "measured" on the right with a traditional oiling, showing drop off at higher RPM...(presumably as the centrifugal effect of the drilling has an impact ???)
Balance some discussion on CFD and it's limitations.