System and method to reduce transfer clutch overheating

A method for controlling a torque transfer clutch of a four-wheel drive vehicle comprising:

• monitoring a first data input source that indicates if the torque transfer clutch is in a four-wheel drive mode;
• monitoring an energy integrator system that monitors energy transferred across a transfer clutch and provides energy accumulator cycle data;
• monitoring a temperature data source that measures a torque transfer clutch temperature and provides clutch temperature data;
• accumulating energy accumulator cycle data provided to a controller programmed with an algorithm that controls the torque transfer clutch based in part on a transfer point value, wherein the algorithm;
• comparing in the controller in a first case during a monitoring period energy accumulator cycle data to a maximum accumulated energy value and requesting a powertrain torque dependent transfer point learn routine if the energy accumulator cycle data is greater than the maximum accumulated energy value;
• comparing in the controller in a second case energy accumulator cycle data to a maximum energy accumulator cycle data value by requesting a non-powertrain torque dependent transfer point learn routine if the energy accumulator cycle data is greater than the maximum energy accumulator cycle data value;
• and
• comparing in the controller in a third case clutch temperature data to a maximum clutch temperature value and initiating a non-powertrain torque dependent transfer point learn routine if the clutch temperature data is greater than the maximum clutch temperature value;
• wherein the controller, responsive to one of the above transfer point learn routines, revises the transfer point value to a revised transfer point value, and wherein the controller controls the torque transfer clutch based upon the revised transfer point value.

A system for controlling a torque transfer clutch of a four-wheel drive vehicle comprising:

• an energy integrator system that monitors the energy transferred across a transfer clutch, wherein the energy integrator system monitors the energy across a transfer clutch based on slippage of the torque transfer clutch and provides cycle data;
• a temperature data source provides transfer clutch temperature data;
• and
• a controller programmed with an algorithm that controls the torque transfer clutch based in part on a transfer point value, wherein the energy transferred across the transfer clutch is accumulated by the controller over the monitoring period:
• in a first case responds to energy integrator accumulated data as to the energy across the torque transfer clutch during a monitoring period and compares the accumulated data to a maximum accumulated energy value by initiating a powertrain torque dependent transfer point learn routine,
• in a second case responds to energy accumulator cycle data as to the energy across the torque transfer clutch in a single monitoring cycle and compares the cycle data to a maximum cycle data value by initiating a non-powertrain torque dependent transfer point learn routine,
• in a third case responds to clutch temperature data and compares the clutch temperature data to a maximum temperature value by initiating the non-powertrain torque dependent transfer point learn routine
• wherein the controller, responsive to one of the above transfer point learn routines, revises the transfer point value to a revised transfer point value, and wherein the controller controls the torque transfer clutch based upon the revised transfer point value.