Hybrid Drive Train Mode Switching Control
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Solution Overview
Problem
Hybrid drive trains in motor vehicles face challenges in dynamic driving operation and power-specific noise emission, particularly when transitioning from parallel to serial mode of operation, leading to undesirable 'howling' of the internal combustion engine and inefficient energy usage.
Innovation Solution
A method for operating a hybrid drive train that involves determining the switchover power based on actual vehicle speed and issuing a warning message when the difference between switchover power and target drive power falls below a prescribed tolerance value, allowing the driver to adjust and prevent unnecessary mode changes, thereby maintaining efficient energy use and reducing noise emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the parallel mode of operation is used to supply drive torque partially by the internal combustion engine and partially by the second electric machine, then the system efficiency is improved, but the maximum achievable drive torque is limited at low rotational speeds due to the direct gear stage
Solution Approach 1:
The patent applies dynamics by making the gear ratio variable through a shiftable first gear (transmission) between the internal combustion engine and the wheels. This allows the gear ratio to be adapted dynamically to vehicle speed and torque demand, enabling the internal combustion engine to deliver adequate torque at lower speeds while maintaining high system efficiency through optimal operating points.
Solution Approach 2:
The patent changes the parameter of gear ratio from fixed (direct gear stage) to variable (shiftable first gear). This parameter change enables the internal combustion engine to operate efficiently across a wider speed range while providing sufficient torque multiplication at lower speeds, resolving the contradiction between efficiency and maximum achievable torque.
2Use of energy by moving object
If the serial mode of operation is used to supply drive torque exclusively by the second electric machine with the first electric machine generating electric energy, then the internal combustion engine can be operated at optimized efficiency, but power-specific noise emission increases due to high rotational speed operation
Solution Approach 1:
The patent uses a shiftable first gear to dynamically adjust the mechanical coupling between the internal combustion engine and the wheels. This allows the system to operate in parallel mode (reducing noise) when vehicle speed and torque demand permit, while still maintaining the ability to switch to serial mode for optimized efficiency when conditions require it.
Solution Approach 2:
The shiftable first gear acts as an intermediary between the internal combustion engine and the wheels, providing a mechanical transmission path that allows the engine to contribute torque directly to the wheels in parallel mode. This intermediary mechanism reduces the need for the internal combustion engine to operate at high rotational speeds in serial mode, thereby reducing power-specific noise emission while maintaining efficiency benefits.
3Device complexity
If a direct gear stage with prescribed gear ratio is used to mechanically couple the internal combustion engine to the wheels, then the system is simplified, but the separating clutch can only be closed above a minimum speed of about 55 km/h
Solution Approach 1:
The patent replaces the static direct gear stage with a dynamic shiftable first gear (transmission). This dynamic element allows the gear ratio to be changed based on operating conditions, enabling the separating clutch to be closed at lower speeds while maintaining system simplicity through a well-defined transmission structure.
Solution Approach 2:
The patent changes the gear ratio parameter from fixed (direct gear stage) to variable (shiftable first gear). This parameter change expands the operating speed range by allowing appropriate gear selection for different speed and torque conditions, while maintaining system simplicity through a standard transmission architecture.
Data Source
AI summary
A method for operating a hybrid drive train of a motor vehicle, comprises the following steps: closing the separating clutch in order to mechanically couple the internal combustion engine to at least one wheel and to propel the motor vehicle, whereby the drive power is supplied at least partially by the internal combustion engine; determining the TARGET drive power (P) of the drive train of the motor vehicle; determining the ACTUAL speed (V) of the motor vehicle; determining the switchover power (U) to separate the separating clutch and to operate the drive train in the serial mode of operation (SB) as a function of the determined ACTUAL speed (V); and issuing a warning message when the difference between the switchover power (U) and the TARGET drive power (P) falls below a prescribed drive power tolerance value (T). Furthermore, the invention relates to a motor vehicle.