Frontloading of cam bearing friction and lubrication assessment through EHD analysis
2022-01-0768
03/29/2022
- Event
- Content
- One of the key thrust areas in engine design and development is achieving friction reduction between rotating parts in engine bearings. Valvetrain and cam bearing friction losses contribute to around 15% of all friction losses. Inline to cranktrain bearings, cam bearings are also supplied oil through oil gallery. Hence, cam bearings also operate under mixed lubrication regime. There is an opportunity to frontload cam bearing assessment through EHD simulation with similar approach as in cranktrain EHD modeling. This paper discusses about simulation methodology developed for cam bearing EHD in AVL Excite Powerunit. Crantrain dynamic model has been extended by appending complete valvetrain dynamic model. A substructure of camshaft has been used to drive valvetrain. Engine is also defined as a substructure with retained nodes at cam bearing interface. These nodes are connected to camshaft using EHD joints. Timing of each cam has been defined to allow synchronous valve opening and closure. This model can provide dynamic time dependent valve forces on cam bearing joint which is a critical input to EHD joint. This high-fidelity model was deployed on a 4-cylinder high density diesel engine. Coupling of valvetrain with cranktrain allows us to extract engine speed dependent valve forces with higher accuracy. With these inputs, a realistic oil film evaluation was possible in EHD joint which was used to assess asperity contact pressure, total pressure and friction losses. Keywords: Cam bearing EHD, valvetrain
- Citation
- Bhattacharya, A., "Frontloading of cam bearing friction and lubrication assessment through EHD analysis," SAE Technical Paper 2022-01-0768, 2022, .