Hybrid Drive Train Torque Coordination During Gear Shifts
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Solution Overview
Problem
Drive trains with frictional shifting elements in hybrid vehicles experience power loss during power shifts, leading to increased wear and unnecessary fuel consumption.
Innovation Solution
A method that reduces torque from the internal combustion engine during power upshifts and downshifts, particularly when shifting into the last three gears, and compensates with increased torque from the electric machine, if present, to minimize power loss and wear on frictional shifting elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If friction-based shifting elements are used in automatic transmission during load shifts, then gear changing capability is improved, but power loss increases and wear occurs
Solution Approach 1:
The method applies preliminary action by reducing the torque from the internal combustion engine before the friction-based shifting elements engage during load shifts. This preventive measure ensures that the torque load is already reduced when the clutches engage, minimizing power loss and wear at the friction elements while maintaining smooth gear transitions.
2Loss of energy
If torque from internal combustion engine is reduced during upshifts or downshifts, then power loss at friction elements is reduced, but torque output to output may be insufficient
Solution Approach 1:
The method merges the torque contribution from two power sources: the internal combustion engine and the electric machine. During load shifts, the electric machine compensates for the reduced torque from the internal combustion engine, ensuring that the total torque output to the output remains sufficient while the friction elements experience reduced power loss.
3Power
If electric machine compensates for reduced combustion engine torque during shifts, then torque output is maintained, but control complexity increases
Solution Approach 1:
The method implements feedback control by continuously monitoring the torque requirements during load shifts and dynamically adjusting the torque distribution between the internal combustion engine and the electric machine. The control unit receives feedback on the shifting state and engine torque, automatically coordinating the torque contribution from both power sources to maintain sufficient output torque while minimizing friction element wear.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces mechanical load and wear on shifting elements, lowering fuel consumption and maintaining effective torque output by optimizing torque distribution between the internal combustion engine and electric machine.
Implementation Method 1
the electric machine can at least partially compensate for the reduction in the internal combustion engine's torque
Implementation Method 2
automatic transmission with friction-based shifting elements, which is connected between the drive unit and an output
Data Source
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AI summary
Method for operating a drive train of a motor vehicle with a drive unit comprising at least one internal combustion engine (1) and with an automatic transmission (3) with friction-fit switching elements connected between the drive unit and an output (2), namely for performing an upshift or a downshift involving at least one engaging friction-fit switching element of the automatic transmission (3) and at least one disengaging friction-fit switching element of the automatic transmission (3), wherein, for performing an upshift, the torque provided by the internal combustion engine (1) is reduced at least during the engagement process of an engaging friction-fit switching element.and wherein, in order to execute a train downshift, at least during the lowering process, the torque provided by the internal combustion engine (1) is reduced in the transmission capacity of a disengaging friction-locked switching element.