Hybrid Vehicle Drive Unit Torque Control for Engine Start
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Solution Overview
Problem
Hybrid vehicles face challenges in starting the internal combustion engine due to inaccuracies in separating clutches and varying friction and compression ratios, leading to torsional vibrations and impaired driving comfort, as the electric or hydraulic motor cannot precisely compensate for the starting torque or power.
Innovation Solution
The method involves intervening in the torque or power of the second drive unit based on measured or modeled longitudinal vehicle movement to counteract disturbances during the start or stop of the first drive unit, using high-pass filtering to address drive train vibrations and closed-loop control to compensate for inaccuracies in the drive train, thereby enhancing driving comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the separating clutch is used to start the internal combustion engine, then the engine can be started during electric or hydraulic driving, but inaccuracies in the clutch and varying friction/compression ratios prevent precise torque compensation, leading to torsional vibrations and impaired driving comfort
Solution Approach 1:
The patent implements a feedback control mechanism where the actual longitudinal movement of the vehicle is continuously measured and compared with a reference course. The deviation between actual and reference movement is used to dynamically adjust the torque of the second drive unit (electric/hydraulic motor), enabling precise compensation for torque fluctuations during engine starting. This closed-loop control eliminates torsional vibrations by continuously correcting torque delivery based on real-time vehicle response.
Solution Approach 2:
The patent dynamically changes the torque parameter of the second drive unit based on the deviation from the reference longitudinal movement course. By adjusting the torque output of the electric or hydraulic motor in real-time according to measured vehicle movement deviations, the system compensates for the imprecise torque transmission through the separating clutch, maintaining smooth vehicle operation during engine starting.
2Power
If the electric motor or hydraulic motor compensates for starting torque, then the first drive unit can be started during operation, but the varying friction and compression ratios prevent exact compensation, causing disturbances and torsional vibrations
Solution Approach 1:
The system uses feedback control by continuously measuring the actual longitudinal movement of the vehicle and comparing it with the reference course. The deviation signal is used to adjust the torque output of the second drive unit, ensuring reliable and smooth torque transition during engine starting. This feedback mechanism compensates for varying friction and compression ratios by adapting the compensation torque based on actual vehicle response.
Solution Approach 2:
The system uses the vehicle's own longitudinal movement data as the basis for torque compensation. By measuring how the vehicle actually responds to the engine starting process and using this information to adjust the second drive unit's torque, the system performs self-correction without requiring external intervention or complex additional sensors.
3Object-affected harmful factors
If high-pass filtering is applied to the derived variable, then drive train vibrations can be counteracted, but the control system complexity increases
Solution Approach 1:
The patent replaces complex mechanical vibration damping systems with a control-based approach. By using high-pass filtering on the derived variable from longitudinal movement, the system electronically identifies and counteracts vibration frequencies in the drive train. This substitution of mechanical damping elements with control algorithms reduces physical system complexity while effectively eliminating drive train vibrations.
4Manufacturing precision
If closed-loop control is implemented to compensate for drive train inaccuracies, then torsional vibrations are optimally controlled and driving comfort is improved, but the control system requires additional processing capability
Solution Approach 1:
The patent implements closed-loop control where the actual longitudinal movement is continuously measured and fed back to adjust the torque of the second drive unit. This feedback mechanism provides accurate torque regulation by comparing actual vehicle response with the reference course and making real-time corrections, achieving optimal control of torsional vibrations while utilizing existing vehicle sensors and processing capabilities.
Data Source
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AI summary
The invention relates to a method for operating a hybrid vehicle, wherein during the driving state of the hybrid vehicle, a first idle drive assembly (1) is started in that a torque (MEM) is partially transmitted from a second operating drive assembly (2) to the first drive assembly (1). In order to keep effects during a start and/or stop of the first drive assembly on the movements of the hybrid vehicle low, means (10) are provided that influence the torque (MEM) of the second, operating drive assembly (2) by at least one of the variables (?Fz; ?Fz-?EM; ?Fz) derived from the longitudinal vehicle movement of the hybrid vehicle.