Patent ID: 8303463
Filing Date: 2012-11-06
Classification: B60K,F16D,F16H,Y02T,Y10T

Abstract:
1. Method for controlling a powertrain comprising an electro-mechanical transmission mechanically-operatively coupled to an internal combustion engine and an electric machine adapted to selectively transmit mechanical power to an output member via selective application of a plurality of hydraulically-applied torque transfer clutches, said method comprising: applying through a series of clutch fill events a series of incrementally changing command pressures in a pressure control solenoid controllably connected to one of said clutches, each successive applied command pressure having a lower pressure than an immediately preceding applied command pressure and each command pressure is directed to a command pressure line feeding a command pressure volume to achieve a full feed state within the pressure control solenoid allowing full exposure of a main pressure line to said clutch being filled; monitoring a pressure switch fluidly connected to said pressure control solenoid and configured to indicate when said pressure switch is in the full feed state; determining changes in cycle times of said pressure switch, each cycle time measuring a time between an initiation and an end of the full feed state for each of the incrementally changed command pressures; selecting a preferred command pressure to achieve a touching state in said clutch based upon said changes in pressure switch cycle times; and controlling said clutch based upon said preferred command pressure.