Evaluating lifetime performance of limited slip differentials

Berglund, Kim; Marklund, Pär; Larsson, Roland; Olsson, Richard T.

doi:10.1002/ls.1244

Cited by 2 publications

(1 citation statement)

References 14 publications

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“…However, low slip levels during long periods of time characterize the typical operating conditions of the wet clutches used in limited slip couplings. 15 Thus, power levels are low. The difference between the operating conditions of the wet clutches used in automatic transmissions and those in limited slip couplings is reflected by the friction material used.…”

Section: Introductionmentioning

confidence: 99%

Prediction of driveline vibrations caused by ageing the limited slip coupling

Berglund

Marklund

Lundh

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part D:

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The prediction of the wet-clutch service life still remains a challenge for scientists and engineers. Previous research has shown the significance of the wet-clutch friction characteristics on the driveline dynamics. To avoid driveline vibrations an increasing friction coefficient with increasing sliding speed is desirable. Consequently, prediction of the occurrence of driveline vibrations relies on a detailed knowledge of how the friction characteristics are affected by wet-clutch degradation, as well as an understanding of the driveline dynamics. Wet clutches are used in both automatic transmissions and all-wheel-drive systems in cars, where they are referred to as limited slip couplings by manufacturers. Wet clutches used in automatic transmissions are subjected to high slip levels, but for very limited time periods. In all-wheel-drive systems, where the limited slip coupling can be used to control the torque transfer to, for example, the rear wheels, the slip levels are low but continuous. Most wet-clutch research has been performed for clutches in automatic transmissions and not for clutches used in all-wheel-drive systems. Thus, a simulation model was developed to evaluate how different operating conditions of the limited slip coupling influence degradation of the friction characteristics and the tendencies towards driveline vibrations. First, the changes in the friction characteristics with the time of ageing are simulated. The friction characteristics after ageing are used as the input to a simplified driveline model, which is used to evaluate the occurrence of vibrations. It is shown how the developed simulation model can be used as an efficient tool for engineers. The developed simulation model can be used to predict how the operating conditions for the limited slip coupling influence degradation of the friction characteristics.

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Section: Introductionmentioning

confidence: 99%

Prediction of driveline vibrations caused by ageing the limited slip coupling

Berglund

Marklund

Lundh

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part D:

Self Cite

View full text Add to dashboard Cite

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Predicting Boundary Friction of Aging Limited Slip Differentials

Berglund

Marklund

Larsson

et al. 2014

Journal of Tribology

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The prediction of friction is a challenge for scientists and engineers in a wide variety of applications in industry today. One such an application is the limited slip differential. The friction characteristics of the wet clutch are central to the performance of the limited slip differential system. Frictional changes with aging of the limited slip differential affect both the torque transfer accuracy and the tendencies to vibrations and noise generation due to stick-slip or shudder. Therefore, the objective of this work is to establish a method to predict the frictional changes of aging limited slip differential systems. In this study, a number of experiments were performed to establish a method to predict the changes in boundary friction with time due to aging. Accelerated aging was performed for different sets of operating conditions. Results from the tests were used to establish and verify a model to predict friction increase in limited slip differentials. The method assumes that frictional changes with aging are caused by decreased concentrations of friction modifying additives. The decrease in concentration was assumed to depend on the lubricant bulk temperature according to the Arrhenius equation. The model agreed well with tests performed at operating conditions close to the real operating conditions of the limited slip differential. The developed method can be implemented in a vehicle where it can be used to compensate for frictional changes and to indicate when service should be made.

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Evaluating lifetime performance of limited slip differentials

Cited by 2 publications

References 14 publications

Prediction of driveline vibrations caused by ageing the limited slip coupling

Prediction of driveline vibrations caused by ageing the limited slip coupling

Predicting Boundary Friction of Aging Limited Slip Differentials

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