Comparison Between Journal and Rolling Element Bearings in a Camshaft Application Mahle Powertrain, Limited

Format:

Conference/Event

Author/Creator:

Mackay, Mackay, author.

Conference Name:

SAE 2012 World Congress & Exhibition (2012-04-24 : Detroit, Michigan, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2012

Summary:

Concerns over greenhouse gas emissions are driving governmentsand the automotive industry to seek out ways of reducing vehicleCO₂ emissions. Engine friction reduction is one means of reducingCO₂ emissions, through fuel consumption improvements. One areawhere it is felt that friction reduction is possible is inconnection with the camshaft bearings.The use of rolling element bearings is generally considered toprovide friction reductions by two means: 1. As a directsubstitution of the journal bearings by rolling element bearingsand 2. As an enabling opportunity to reduce the oil flowrequirement of the engine.MAHLE has undertaken a motored friction-testing program on a2.5-liter gasoline engine, comparing the drive torques associatedwith the standard camshaft bearings and also with camshaftssupported by rolling element bearings.The test engine incorporated a direct-acting valve train design.For manufacturing reasons, the camshaft supported in rollingelement bearings incorporated sintered camshaft lobes whilst thestandard engine employed a chill cast camshaft supported inconventional journal bearings.Contrary to previously reported results, the direct substitutiontests demonstrated that the camshaft supported on journal bearingshad a lower level of friction than the camshaft supported byrolling element bearings. The test engine configuration fitted withrolling element bearings showed a lack of sensitivity to variationsin oil flowrates applied both to the rolling element bearings andalso to the tappet/cam lobe interfaceThis paper considers the approach to the testing, the testresults obtained and some further discussion, including a possiblebasis for the results obtained

Notes:

Vendor supplied data

Publisher Number:

2012-01-1324

Access Restriction:

Restricted for use by site license