Method and system for controlling driveline lash in a hybrid vehicle

A method for controlling a hybrid vehicle having an engine and an electric machine, the method comprising:

• engaging a clutch downstream of the electric machine;
• controlling an electric machine torque output to a designated rate of change when a vehicle torque changes direction and the electric machine is operating, wherein the vehicle torque comprises a road load torque, the electric machine torque output, and an engine torque output;
• and
• controlling the electric machine torque output and the engine torque output to meet driver demand before and after a time zone when the vehicle is operating in a hybrid mode;
• wherein the electric machine torque output is controlled to the designated rate of change when the vehicle is operating in the hybrid mode and the vehicle torque changes direction, thereby reducing lash in a driveline, wherein the vehicle torque changing direction occurs within the time zone when the vehicle torque is substantially zero, the time zone occurring after a driver demand event.

A hybrid vehicle system comprising:

• an electric machine;
• a torque converter having a bypass clutch, the bypass clutch being a downstream clutch;
• and
• a controller configured to (i) control a torque output of the electric machine to a designated rate of change within a time zone to reduce lash in a driveline when the downstream clutch is engaged, wherein the time zone is characterized by a vehicle torque being substantially zero and the vehicle is in one of an accelerating state and a decelerating state, and (ii) control at least one of the torque output of the electric machine and an engine torque output to meet driver demand outside of the zone.