Torque converter slip control based on motor torque during transient events
First Claim
1. A method for controlling a driveline in a hybrid vehicle having an engine and an electric motor selectively coupled to an automatic transmission with a torque converter having a bypass clutch, comprising:
- controlling bypass clutch pressure during a transient torque event to control torque converter slip using feed forward control based on electric motor torque and feedback control of the torque converter slip to maintain a desired torque ratio during the transient torque event.
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Accused Products
Abstract
A hybrid vehicle with an engine, an electric drive motor and battery, an automatic transmission with a torque converter having a bypass clutch, and a powertrain controller dynamically adjust the torque converter slip to balance fuel economy and drivability during a transient torque request by using motor torque to satisfy the transient torque and applying feed forward control of the fluid pressure in the bypass clutch based on the motor torque and feedback control of the slip to maintain torque converter torque ratio substantially constant during the transient event.
28 Citations
15 Claims
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1. A method for controlling a driveline in a hybrid vehicle having an engine and an electric motor selectively coupled to an automatic transmission with a torque converter having a bypass clutch, comprising:
controlling bypass clutch pressure during a transient torque event to control torque converter slip using feed forward control based on electric motor torque and feedback control of the torque converter slip to maintain a desired torque ratio during the transient torque event. - View Dependent Claims (2, 3, 4, 5)
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6. A hybrid electric vehicle, comprising:
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an engine; an automatic transmission having a torque converter with an impeller, a turbine, and a bypass clutch; a traction motor coupled to the impeller and selectively coupled to the engine by a disconnect clutch; a controller configured to control the bypass clutch to maintain non-zero slip between the impeller and the turbine to a target slip during a torque demand change by calculating a command for bypass clutch pressure based on a feed forward control using the traction motor torque needed to meet the torque demand, and controlling the command based on feedback control of the slip between the impeller and the turbine. - View Dependent Claims (7, 8, 9, 10)
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11. A hybrid vehicle, comprising:
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an engine; an electric machine operable as a traction motor or generator selectively coupled by a disconnect clutch to the engine; a battery coupled to the electric machine and tractive power to the electric machine when operating as a traction motor and storing energy from the electric machine when operating as a generator; a step-ratio automatic transmission having a torque converter with an impeller fluidly coupled to a turbine and a bypass clutch operable in an open mode, a locked mode that mechanically couples the turbine and the impeller, and a slip mode; a controller in communication with the engine, the electric machine, and the automatic transmission, the controller configured to operate the bypass clutch in the slip mode and control a speed difference between the impeller and the turbine in response to a transient torque request, the controller commanding an electric machine torque to meet the transient torque request while maintaining engine torque substantially constant, and applying feed forward control of bypass clutch pressure based on the electric machine torque and feedback control of the bypass clutch pressure based on the speed difference to maintain torque converter torque ratio substantially constant during the transient torque request. - View Dependent Claims (12, 13, 14, 15)
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Specification