Water contamination effect in wet clutch system

Abstract

Water contamination in wet clutch systems can be a problem since both torque characteristics and wear resistance can be influenced by the presence of water. The present paper reveals the effect of externally added water on the wet clutch frictional performance. Commercially available standard paper-based friction plates and steel separator plates lubricated with commercially available automatic transmission fluid were investigated in a recently developed automated test rig using a well-confined experimental approach. Frictional response was observed for three different situations with different amounts of water and different exposure times. An undesirable friction increase is observed with increasing amounts of water in the system. The rate of increase in friction coefficient does not linearly depend on the amount of added water, and this is a noticeable outcome from the common possible water contamination effects, such as change in lubricant viscosity, inadequate additive performance and weakening of the friction material. The greater reduction in the separator plates' surface roughness (R a ) in a water contaminated clutch system compared to an uncontaminated one may be a reason for the change in friction. It is also shown that different water exposure time has no great impact on the change in friction level and the separator plates' roughness.

On-board Clutch Slippage Detection and Diagnosis in Heavy Duty Machine

“…Regarding related future work, it would be interesting to continue with monitoring the health of Automatic Transmission Fluids (ATF) on-board via additional sensors attached to the machine, since the oil has a lot of information concerning the health of the automatic transmission clutches (Fatima et al, 2012). In practical settings, to offer customers a possibility to monitor a fleet of machines with diagnostics for each machine may save both money and time, as for instance potential clutch failures may be predicted well in advance before they occur.…”

“…Furthermore, a clutch is considered to have failed when it can no longer transmit the desired torque. The level of torque transfer in wet clutches is controlled by the generated friction in it, and a good and stable friction coefficient which keeps output torque at a required level is important (Fatima et al, 2013;Fatima, Marklund, & Larsson, 2012). Thus, clutch slippage is a result of diminishing frictional characteristics of the clutch system (Fatima et al, 2013).…”

“…The friction characteristics of the clutch material are influenced by different factors such as the clutch material structure, porosity, lubricant and permeability (Berglund, 2013;Marklund, 2010). Furthermore, the coefficient of friction may be affected by sliding speed, varying load, boundary friction, contact temperature of clutch plates and friction due to fluid flow through the friction material (thin-film friction) (Fatima et al, 2012;Devlin et al, 2004).…”

Scalable validation of industrial equipment using a functional DSMS

“…In other work on anomaly detection from equipment, e.g by Miura et al (1998), Mäki (2003b), Marklund (2010), Ito et al (2012), Fatima et al (2012), Okabe (2009), Berglund (2013, the anomaly detection is made in test-rigs, but not in the actual heavy duty machines. In our application clutch slippage detection and diagnoses are done on-board the equipment where streams of sensors are processed on the machine by SVALI using a CAN bus wrapper.…”

Degradation mechanism of automatic transmission fluid by water as a contaminant

“…Previous studies by the authors 11,12 showed that the antishudder behavior and friction stability of a wet clutch system can be hindered by increasing friction and negative friction-velocity relationship, when water has been added to the ATF. As mentioned before, both these friction outcomes, increasing friction level and negative slope of the friction-velocity curve, are not favorable conditions for a proper clutch function.…”