Gearbox Pinion Synchronization with Torque-Limited Speed Matching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for synchronizing gearbox shafts in vehicles with parallel shafts, particularly during hard braking on steep gradients, face challenges with torque surges and mechanical wear due to the inertia and response time of traction machines, especially thermal engines.
Innovation Solution
A method that limits the amplitude of a calculated torque signal when the speed difference between primary and secondary shafts multiplied by the reduction ratio exceeds a desired precision, using a calibrated coefficient to minimize torque surges and ensure synchronization in minimum time, applicable to both electric and hybrid powertrains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the traction machine is controlled to minimize the speed difference between primary and secondary shafts, then synchronization precision is improved, but the response time is worsened due to the inertia of the traction machine
Solution Approach 1:
The patent applies preliminary action by initiating the synchronization process before the actual gear coupling occurs. The control system starts adjusting the traction machine torque in advance to minimize speed differences, allowing the shafts to be closer to synchronization before the dog clutch engages, thereby reducing the negative effects of inertia during the critical coupling moment
Solution Approach 2:
The patent implements dynamics by continuously and dynamically adjusting the torque command to the traction machine based on real-time speed measurements. The control system modifies the torque signal dynamically during the synchronization phase to optimize the balance between response speed and synchronization precision, adapting to the changing inertial conditions
2Ease of operation
If the speed difference is reduced quickly to ensure transparent operation, then the driver experience is improved, but torque surges are generated causing mechanical wear
Solution Approach 1:
The patent applies beforehand cushioning by implementing a controlled torque limitation strategy during the synchronization phase. The system pre-calculates and limits the maximum torque that can be applied to the traction machine, cushioning against potential torque surges before they occur. This ensures that even when speed differences are reduced quickly for smooth operation, the torque remains within safe limits to prevent mechanical wear
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the torque command parameter to the traction machine. The control system modifies the torque signal amplitude and rate of change based on the current speed difference and synchronization progress, allowing quick speed equalization while preventing excessive torque that would cause surges and mechanical wear
Data Source
Figure 1A~1C
Figure 2
AI summary
A method for controlling the synchronisation of a pinion (4) rotating on a primary shaft driven by a traction machine of the vehicle and linked in rotation to a secondary shaft of a parallel shaft gearbox that has no synchronisation mechanisms, by sending, to the traction machine, before the coupling of the pinion on the primary shaft, a torque command (T1 ref )that depends on a torque signal (T1 calcul) calculated to minimise the difference (σ) between the primary speed (ω1) and the secondary speed (ω2) multiplied by the reduction ratio (K) between said two shafts, characterised in that the amplitude of the calculated torque signal (T1 calcul) is limited when the difference in speed (σ) is of a greater absolute value than the desired accuracy (ε) of the targeted primary speed (ω1) at the end of the synchronisation phase.