US 7,931,561 B2Granted

Aggressive torque converter clutch slip control design through driveline torsional velocity measurements

AssigneeGM Global Technology Operations LLC

InventorsPaul G Otanez, Farzad Samie, Chunhao J. Lee

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Abstract

A system and method for setting the slip of a torque converter for a plurality of selected engine speeds and transmission gears. The method includes populating a table off-line, typically using a dynamometer, with torque converter slips for a plurality of selected engine speeds and transmission gears. A speed sensor is used to measure vibrations transmitted through the torque converter to the driveline of the vehicle. The sensor signal is sent to an analyzing system where it is converted to the frequency domain. A separate minimum slip value for each selected engine speed and transmission gear is stored in a table so that during vehicle operation, a controller will instruct the torque converter clutch to set the desired converter slip for the current engine speed and transmission gear provided for a particular throttle position and/or engine torque.

A method for determining a desired torque converter slip for a torque converter that transfers torque between a vehicle engine and a vehicle transmission, said method comprising:

selecting a gear of the transmission and a torque converter clutch (TCC) slip level;
increasing an engine speed of the engine within a predetermined speed range;
providing a sensor signal from a sensor at an output of the transmission that measures transmission output speed;
transforming the sensor signal to a frequency signal;
plotting a resultant vibration amplitude for the transmission gear and the TCC slip level using the frequency signal;
repeating the steps of increasing the engine speed, providing a sensor signal, transforming the sensor signal and plotting the resultant vibration amplitude for all transmission gears and TCC slip levels, wherein transforming the sensor signal to a frequency signal can be done as the measurements of the sensor signal are obtained or after a predetermined number of sensor signals have been obtained and wherein plotting a resultant vibration amplitude is done after the frequency signals have been obtained;
determining a desired vibration amplitude threshold;
determining whether an amplitude of the frequency signal exceeds the vibration amplitude threshold for a transmission gear, engine speed and TCC slip level;
increasing the TCC slip level a predetermined amount if the amplitude threshold is exceeded;
increasing the TCC slip level until the amplitude threshold is not exceeded;
storing a minimum torque converter slip in a table corresponding to a selected transmission gear and engine speed;
and
repeating the steps of determining a desired vibration amplitude threshold, determining whether an amplitude of the frequency signal exceeds the vibration amplitude threshold, increasing the TCC slip level, and storing the minimum torque converter slip for all of the transmission gears and engine speeds.

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Abstract

Claims21