Control system for a continuously variable transmission in a vehicle propulsion system

A continuously variable transmission for a vehicle propulsion system comprising:

• a torque input shaft adapted to be coupled to the torque transmitting shaft of a prime mover in the vehicle propulsion system;
• a first pulley coupled to the torque input shaft, the first pulley including a first moveable sheave that is translated along a first axis relative to a first stationary sheave in response to a first clamp pressure applied to a first actuator;
• a second pulley coupled to a torque output shaft, the second pulley including a second moveable sheave that is translated along a second axis relative to a second stationary sheave in response to a second clamp pressure applied to a second actuator;
• a flexible continuous rotatable device coupled to the first pulley and to the second pulley;
• and
• a controller including an instruction set, the instruction set executable to:
• determine whether a current inertia torque value is greater than a previous inertia torque value;
• execute control over one of the first clamp pressure and the second clamp pressure such that said one of the first clamp pressure and the second clamp pressure corresponds to current inertia torque value if the current inertia torque value is greater than a previous inertia torque value;
• and
• execute control over one of the first clamp pressure and the second clamp pressure such that said one of the first clamp pressure and the second clamp pressure corresponds to previous inertia torque value if the current inertia torque value is not greater than a previous inertia torque value for a predetermined period of time.

A method for controlling a vehicle propulsion system with a prime mover coupled to a torque transmitting shaft, a continuously variable transmission that includes a torque input shaft coupled to the torque transmitting shaft, a first pulley coupled to the torque input shaft, a flexible continuous rotatable device coupled to the first pulley and to a second pulley, the first pulley including a first moveable sheave that is translated along a first axis relative to a first stationary sheave in response to a first clamp pressure applied to a first actuator, the second pulley including a second moveable sheave that is translated along a second axis relative to a second stationary sheave in response to a second clamp pressure applied to a second actuator, and a torque output shaft coupled to the second pulley and to a final drive of the vehicle propulsion system, the method comprising:

• determining whether a current inertia torque value is greater than a previous inertia torque value;
• executing control over one of the first clamp pressure and the second clamp pressure such that said one of the first clamp pressure and the second clamp pressure corresponds to current inertia torque value if the current inertia torque value is greater than a previous inertia torque value;
• and
• executing control over one of the first clamp pressure and the second clamp pressure such that said one of the first clamp pressure and the second clamp pressure corresponds to previous inertia torque value if the current inertia torque value is not greater than a previous inertia torque value for a predetermined period of time.