Tribodynamics of hydraulic actuated clutch system for engine-downsizing in heavy duty off-highway vehicles

Engine downsizing is desired for modern heavy-duty vehicles to enhance fuel economy and reduce emissions. However, the smaller engines usually cannot overcome the parasitic loads during engine start-up. A new clutch system is designed to disconnect the downsized engine from the parasitic losses prio...

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Bibliographic Details
Published in:Proceedings of the Institution of Mechanical Engineers. Part D, Journal of automobile engineering Journal of automobile engineering, 2019-03, Vol.233 (4), p.976-993
Main Authors: Dolatabadi, Nader, Rahmani, Ramin, Theodossiades, Stephanos, Rahnejat, Homer, Blundell, Guy, Bernard, Guillaume
Format: Article
Language:English
Subjects:
Clutches
Computer simulation
Contact pressure
Downsizing
Fuel economy
Hydraulic fluids
Idling
Leakage
Lubricants
Lubricants & lubrication
Multibody systems
Multiscale analysis
Parameter sensitivity
Product design
Repair & maintenance
Sensitivity analysis
Torque
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Summary:Engine downsizing is desired for modern heavy-duty vehicles to enhance fuel economy and reduce emissions. However, the smaller engines usually cannot overcome the parasitic loads during engine start-up. A new clutch system is designed to disconnect the downsized engine from the parasitic losses prior to the idling speed. A multi-scale, multi-physics model is developed to study the clutch system. Multi-body dynamics is used to study the combined translational–rotational motions of the clutch components. A micro-scale contact model is incorporated to represent the frictional characteristics of the sliding surfaces. Although the clutch is designed for dry contact operation, leakage of actuating hydraulic fluid can affect the interfacial frictional characteristics. These are integrated into the multi-body dynamic analysis through tribometric studies of partially wetted surfaces using fresh and shear-degraded lubricants. Multi-scale simulations include sensitivity analysis of key operating parameters, such as contact pressure. This multi-physics approach is not hitherto reported in the literature. The study shows the importance of adhesion in dry clutch engagement, enabling full torque capacity. The same is also noted for any leakage of significantly shear-degraded lubricant into the clutch interfaces. However, the ingression of fresh lubricant into the contact is found to reduce the clutch torque capacity.
ISSN:0954-4070
2041-2991
DOI:10.1177/0954407018756789