Engagement behaviour of a paper-based wet clutch Part 2: Influence of temperature

Abstract

To increase comfort, performance and fuel economy, a more careful optimization of automatic transmissions is needed. Of special interest is how the temperature influences the engagement characteristics. In order to increase the level of knowledge in this area, a wet clutch test rig including a drive torque and inertia was used. The temperature and the developed energy were varied in order to investigate their influence on the characteristics of an engagement. As a consequence the influence of instant temperature, maximum temperature and instant normal force was also studied. Some of the most important conclusions of the investigation are that both the dynamic and static friction coefficients slightly decrease and the engagement time increases with increasing temperature. It was also found that the static and dynamic friction coefficients are not influenced by energy if the instant temperature is the same. An important parameter that describes the risk of stick-slip is the quotient between the static and dynamic friction. It was found that this quotient decreases with increasing temperature, and thus the risk of stick-slip is also supposed to decrease.

Simulation of the engagement of carbon fabric wet clutch: Analytical and experimental comparison

“…The lubrication oil has a vital effect on the tribological characteristics of wet clutches [30] and the temperature has an important influence on the lubrication oil [31]. Fig.…”

Effect of ATF temperature on the friction-wear characteristic of a wet multi-disc clutch during the running-in process

“…During a clutch engaging process, the ATF film at the friction components is squeezed, so sliding contact of the opposing surfaces occurs (Wang et al, 2018). The temperature will change the viscosity of ATF, thus altering the actual pressure of the contacting surface asperity summit (Zhang et al, 2016;Holgerson and Lundberg, 1999;Zhao et al, 2017aZhao et al, , 2017b. Additionally,…”

“…During a clutch engaging process, the ATF film at the friction components is squeezed, so sliding contact of the opposing surfaces occurs (Wang et al , 2018). The temperature will change the viscosity of ATF, thus altering the actual pressure of the contacting surface asperity summit (Zhang et al , 2016; Holgerson and Lundberg, 1999; Zhao et al , 2017a, 2017b). Additionally, the ATF temperature can also influence the static and dynamic friction coefficient, thus may induce a shuddering risk (Mäki et al , 2006; Ashikawa et al , 1993).…”

Anti-Shudder Properties of ATFs—An Investigation into Friction Modifying Mechanisms Using VSFT and SAE No. 2 Tests

“…13 Fig. 13-VSFT test results after 16-h durability test at (a) 27 • C, (b) 66 • C, and (c) (21)work, where they found that their ATF formulations provided positive µ-v characteristics only above a certain temperature (around 90-100 • C) in the VSFT test. They did not explain the temperature-dependent friction behavior mechanisms in their papers.…”