Gearbox Shift Assist via Electric Machine Speed Control
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Solution Overview
Problem
Manual gear changes in vehicles with internal combustion engines can result in jerks due to unsynchronized rotation speeds between the engine and gearbox, especially during upshifts and downshifts, which are unpleasant for occupants and can stress vehicle components.
Innovation Solution
An electric machine permanently coupled to the crankshaft of the internal combustion engine is used to control the engine's rotational speed during gear changes by adjusting its torque based on vehicle speed, accelerator pedal position, and gear ratio, ensuring synchronization with the gearbox before re-engaging the clutch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the clutch is re-engaged abruptly after gear change, then the gear shift is completed quickly, but the engine speed becomes unsynchronized with gearbox speed causing jerks
Solution Approach 1:
The electric machine performs preliminary speed synchronization of the engine with the target gear ratio before the clutch is fully re-engaged. This preliminary action ensures that when the clutch closes, the speeds are already matched, preventing jerks while maintaining quick shift completion
Solution Approach 2:
The patent replaces the purely mechanical driver-controlled clutch dosing with an electrically assisted system. The electric machine substitutes for the mechanical synchronization mechanism by actively controlling engine speed through electrical torque, enabling precise speed matching without relying solely on driver skill
2Device complexity
If the driver manually controls engine speed during re-clutching, then no additional components are needed, but synchronization precision is insufficient leading to jerks
Solution Approach 1:
The electric machine acts as an intermediary between the driver's gear change command and the engine's rotational speed. It mediates the synchronization process by providing electrical torque control that bridges the speed gap, achieving precision unattainable through manual mechanical control alone
Solution Approach 2:
The control system uses sensors to automatically detect gear change events and autonomously activates the electric machine for speed synchronization. This self-service capability eliminates the need for complex manual coordination while maintaining high precision, as the system self-regulates based on detected conditions
3Ease of operation
If clutch dosing is performed to synchronize speeds, then jerks are reduced, but the gear change process becomes longer
Solution Approach 1:
The electric machine provides rapid electrical torque response that replaces slow mechanical clutch dosing. This substitution enables much faster speed adjustment, achieving smooth synchronization in a fraction of the time required by mechanical means alone, thus reducing overall gear change duration
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 method improves the smoothness and fluidity of gear changes by synchronizing engine and gearbox speeds, reducing jerks and clutch slippage, and extending the lifespan of clutch and gearbox components.
Implementation Method 1
an electric machine, the torque of which is exerted on a shaft permanently coupled to the crankshaft of the heat engine
Data Source
Figure 1A~1C
Figure 2~3
Figure 4
AI summary
method of assisting gear shifting in a gearbox of a powertrain provided with a heat engine (1) coupled to the gearbox (4) by an input clutch (6) which, when disengaged, interrupts the transmission of torque from the engine (1) to the gearbox (4) during gear shifting, and an assisting electric machine (3) of which the torque is exerted on a shaft permanently coupled to the crankshaft (2) of the heat engine, according to which the electric machine is used to control the rotational speed of the heat engine before the clutch is engaged in the new engaged speed, characterised in that the electric machine (3) is controlled such that the rotational speed of the heat engine (1) reaches a target speed based on the type of shift engaged.