Control of power-on downshifts in a multiple-ratio powertrain for a hybrid vehicle
AssigneeFord Global Technologies, LLC
InventorsDan Colvin, Walt Ortmann, Michael Encelewski
Life of this patent
Estimating the term…
Abstract
A method for controlling engagement and release of friction clutches in a multiple-ratio transmission for a hybrid electric vehicle powertrain uses electric motor torque to augment engine torque as a power-on downshift is commanded. Near the end of a downshift event, total powertrain torque is modulated or reduced to reduce torque disturbances.
Claims10
A method for controlling a speed ratio shift for a multiple speed ratio power transmission in a hybrid electric vehicle powertrain, the powertrain having an internal combustion engine and an electric motor for developing a total vehicle driving power source, the multiple speed ratio power transmission having multiple-ratio gearing with first and second selectively engageable fluid pressure actuated friction elements for establishing and disestablishing low speed ratio and high speed ratio torque flow paths from the driving power source to a transmission torque output member, the first friction element being applied and the second friction element being released during low speed ratio operation, the second friction element being applied and the first friction element being released during high speed ratio operation, the method comprising:
- increasing motor torque during an inertia phase of a speed ratio downshift as the first friction element is released;
- and
- reducing motor torque when the pressure of the second friction element is increased toward a full engagement value during the speed ratio downshift whereby inertia torque disturbances due to changing engine speed during the speed ratio downshift are reduced.
A method for controlling a speed ratio shift for a multiple speed ratio power transmission in a hybrid electric vehicle powertrain, the powertrain having an internal combustion engine and an electric motor for developing a total vehicle driving power source, the transmission having multiple-ratio gearing with first and second selectively engageable fluid pressure actuated friction elements for establishing and disestablishing low speed ratio and high speed ratio torque flow paths from the driving power source to a transmission torque output member, the first friction element being applied and the second friction element being released during low speed ratio operation, the second friction element being applied and the first friction element being released during high speed ratio operation, the method comprising:
- modulating engine torque following an inertia phase of a speed ratio downshift as the second friction element is applied;
- and
- ending the engine torque modulation following completion of the downshift when the second friction element is fully applied, whereby torque fluctuations at the transmission torque output member are reduced.
A method for controlling a speed ratio shift for a multiple speed ratio power transmission in a hybrid electric vehicle powertrain, the powertrain having an internal combustion engine and an electric motor for developing a total vehicle driving power source, a multiple-ratio power transmission, the transmission having multiple-ratio gearing with first and second selectively engageable fluid pressure actuated friction elements for establishing and disestablishing low speed ratio and high speed ratio torque flow paths from the driving power source to a transmission torque output member, the first friction element being applied and the second friction element being released during low speed ratio operation, the second friction element being applied and the first friction element being released during high speed ratio operation, the method comprising:
- increasing motor torque during an inertia phase of a speed ratio downshift as the first friction element is released;
- modulating engine torque as the pressure of the second friction element is increased toward a full engagement value;
- and
- ending the engine torque modulation following completion of the downshift when the second friction element is fully applied, whereby torque fluctuations at the transmission torque output member are reduced.
A method for controlling a speed ratio shift for a multiple speed ratio power transmission in a hybrid electric vehicle powertrain, the powertrain having an internal combustion engine and an electric motor for developing a total vehicle driving power source, the transmission having multiple-ratio gearing with first and second selectively engageable fluid pressure actuated friction elements for establishing and disestablishing low speed ratio and high speed ratio torque flow paths from the driving power source to a transmission torque output member, the first friction element being applied and the second friction element being released during low speed ratio operation, the second friction element being applied and the first friction element being released during high speed ratio operation, the method comprising:
- generating negative regenerative motor torque as actuating pressure for the second friction element increases to its fully engaged value and actuating pressure for the first friction element is reduced toward zero value at the end of the downshift whereby torque fluctuations at the transmission torque output member are reduced.
Dependencies are inferred from the claim text.