Abstract: A power transmission device includes a friction clutch, an actuator with an output member, and a controller. The friction clutch is lubricated with a lubricant. The controller is configured to determine a current power state of the friction clutch and determine values for a plurality of thermal coefficients based on the current power state, a set of operation variables, and one or more multi-variable correlation data. The controller is further configured to determine an approximated temperature change of the lubricant based on the values of the plurality of thermal coefficients and a lubricant temperature model. The controller is further configured to determine an approximated lubricant temperature based on the approximated temperature change and a device ambient temperature, and to control operation of the actuator based at least on the approximated lubricant temperature.

Abstract: A power transmission device includes a friction clutch, an actuator, and a controller configured to determine an approximated temperature change of the friction clutch. The controller is configured to determine a current power state of the friction clutch, determine a desired power state change based on the current power state and a previous power state, determine a plurality of thermal coefficients based on a thermal coefficient model, the desired power state change, and a set of operation variables, determine an approximated temperature change of the friction clutch based on the thermal coefficients and a friction clutch temperature model, determine an approximated clutch temperature based on the approximated temperature change and a contemporaneous value of an device ambient temperature, and control operation of the actuator based at least on the approximated clutch temperature.