System and method to predict the remaining useful life of a clutch by coefficient of friction estimation

A method for determining a remaining useful life of a portion of a wet clutch system, the method comprising the steps of:

• providing the wet clutch system, the wet clutch system comprising:
• a first clutch assembly rotatingly disposed in a housing, a first portion of the first clutch assembly drivingly engaged with an input member and a second portion of the first clutch assembly drivingly engaged with an output member,
• a second clutch assembly rotatingly disposed in a housing comprising a first portion drivingly engaged with an input member and a second portion drivingly engaged with an output member,
• a proportional valve for regulating a pressure applied to the first clutch assembly and the second clutch assembly,
• a controller controlling the proportional valve,
• actuating the first clutch assembly to one of engage and disengage the first portion of the first clutch assembly with the second portion of the first clutch assembly;
• actuating the second clutch assembly to one of engage and disengage the first portion of the second clutch assembly with the second portion of the second clutch assembly;
• obtaining a torque value and a pressure value of one of the first clutch assembly and the second clutch assembly for each of a plurality of actuations of a respective one of the first clutch assembly and the second clutch assembly;
• calculating with the controller coefficient of friction values of the respective one of the first clutch assembly and the second clutch assembly by dividing each torque value by an associated pressure value;
• calculating a mean coefficient of friction of the respective one of the first clutch assembly and the second clutch assembly from the calculated coefficient of friction values;
• and
• determining a remaining useful life of the respective one of the first clutch assembly and second clutch assembly based on the mean coefficient of friction of respective one of the first clutch assembly and the second clutch assembly.

A system for determining a remaining useful life of a portion of a wet clutch system, the system comprising:

• a first clutch assembly rotatingly disposed in a housing, a first portion of the first clutch assembly drivingly engaged with an input member and a second portion of the first clutch assembly drivingly engaged with an output member;
• a proportional valve for regulating a pressure applied to the first clutch assembly;
• a sensor for obtaining a torque value of the first clutch assembly during a slipping condition of the first portion of the first clutch assembly with the second portion of the first clutch assembly;
• and a controller controlling the proportional valve, wherein the controller calculates a plurality of coefficient of friction values of the first clutch assembly by dividing a torque value of the first clutch assembly by a pressure applied to the first clutch assembly for a plurality of actuations of the first clutch assembly, and the controller calculates a mean coefficient of friction from the calculated coefficient of friction values to determine a remaining useful life of a portion of the wet clutch system based on the mean coefficient of friction of the first clutch assembly and a stored or learned relationship between the mean coefficient of friction and the clutch cycle life.