Automatic transmission hot mode management
AssigneeGeneral Motors Corporation
InventorsWilliam Joseph Vukovich, Melissa Mei Koenig
Life of this patent
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Abstract
A multi-ratio automatic transmission has a plurality of fluid operated clutching devices, a fluidic torque converter and a fluid operated torque converter clutch mechanism. During certain operational periods, a hot mode is invoked to eliminate certain heat sources and increase heat dissipation to thereby prevent the fluid temperature from exceeding a predetermined maximum temperature. The hot mode is invoked as a function of both the temperature of the transmission fluid and the rate of change of the fluid temperature.
Claims6
A method for controlling entry into a hot mode of operation in an automatic transmission including a plurality of fluid operated friction elements, a fluidic torque converter and a fluid operated torque converter lock-up clutch, the method comprising the steps:
- monitoring a transmission fluid temperature;
- calculating a rate of fluid temperature change from said monitored transmission fluid temperature;
- comparing said rate of fluid temperature change to a reference rate of fluid temperature change determined as a function of said monitored transmission fluid temperature;
- and
- invoking said hot mode of operation when said rate of fluid temperature change exceeds said reference rate of fluid temperature change.
A method for controlling entry into a hot mode of operation in an automatic transmission including a plurality of fluid operated friction elements, a fluidic torque converter and a fluid operated torque converter lock-up clutch, the method comprising the steps:
- monitoring a transmission fluid temperature;
- calculating a rate of fluid temperature change from said monitored transmission fluid temperature;
- comparing said rate of fluid temperature change to a predetermined reference rate of fluid temperature change adjusted in response to a temperature differential between a peak fluid temperature during said hot mode of operation and a predetermined maximum desirable fluid temperature;
- and
- invoking said hot mode of transmission operation when said rate of fluid temperature change exceeds said reference rate of fluid temperature change.
Dependencies are inferred from the claim text.