Abstract
Friction loss is one of the main factors affecting engine power. Reducing friction power losses to improve the power of engines is a significant concern for designers. Especially, under the background of energy-saving and emission reduction, it is indispensable to carry out an in-depth investigation on engine bearing lubrication characteristics. Unlike the previous studies of separate modelling, a new modelling method of coupling the dynamic and lubrication model is proposed in this paper. The bearing capacity, friction force, friction coefficient and eccentricity ratio were taken as the evaluation criterion, and the influence of design parameters such as angular speed, bearing radius and width on the lubrication efficiency and friction power loss (LE-FPL) were studied. The results indicate that increasing the angular speed, bearing radius or width can effectively reduce the eccentricity ratio and raise the minimum oil film thickness, which is beneficial to improve the lubrication efficiency. However, the above methods to improve engine lubrication efficiency will lead to more power loss of engine to a certain extent. Therefore, studies on reducing the friction power loss for the engine and on improving the lubrication efficiency for the engine should be considered coordinately in the dynamic design and optimisation of the engine.
Highlights
With the continuous improvement of people’s requirements for fuel economy and energy conservation and emission reduction for the oil-fueled automotive, reducing friction power losses to enhance engine power has been a significant concern for automotive designers
The new contributions of this study lie in the following aspects: (i) a new numerical method established by combining the SCM dynamic model and the crankpin bearing (CB) lubrication model to investigate the LE-FPL of engines has been proposed, (ii) the influence of the eccentricity between the shaft and the bearing on vibration and lubrication stability has been revealed and, (iii) both lubrication efficiency and friction power loss of the engine under different angular speeds, loads, and dimensions of the CB have been analysed
The analysis shows that in the combustion stroke of the engine, the maximum dynamic load W affects the lubrication efficiency of CB, and the engine power
Summary
With the continuous improvement of people’s requirements for fuel economy and energy conservation and emission reduction for the oil-fueled automotive, reducing friction power losses to enhance engine power has been a significant concern for automotive designers. To illustrate the stability of the oil film thickness of the friction surface pairs in an engine, especially the crankpin bearing (CB), a CB’s lubrication model was built under different conditions of external load and speed of the shaft; based on the evaluation indexes of the friction force and load-bearing capacity [11-13]. The new contributions of this study lie in the following aspects: (i) a new numerical method established by combining the SCM dynamic model and the CB lubrication model to investigate the LE-FPL of engines has been proposed, (ii) the influence of the eccentricity between the shaft and the bearing on vibration and lubrication stability has been revealed and, (iii) both lubrication efficiency and friction power loss of the engine under different angular speeds, loads, and dimensions of the CB have been analysed.
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