Hybrid Gearbox Idler Pinion Synchronization via Torque Desaturation
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Solution Overview
Problem
In hybrid vehicle gearboxes with concentric input shafts, the inertia driven by the electric machine during gear changes leads to torque saturation issues due to the absence of mechanical synchronization members, causing uncontrollable system behavior and potential mechanical wear during gear shifts, especially during 'ramp' type trajectories and hard braking scenarios.
Innovation Solution
A control strategy involving two de-saturating blocks that temporarily lighten the torque of the electric machine during synchronization phases by adjusting the torque setpoints of both the electric and heat engines to ensure perfect coupling, using a regulator to manage torque within defined limits and desaturate the electric machine's torque quickly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical synchronization members are used in the coupling system, then speed synchronization between shafts is improved, but device complexity and mechanical wear increase
Solution Approach 1:
The patent replaces mechanical synchronization members with an electronic control system that uses sensors to detect shaft speeds and actuators to adjust the coupling engagement timing, thereby achieving speed synchronization without mechanical synchronization components
Solution Approach 2:
The patent introduces an electronic control unit as an intermediary between the shafts and coupling system, which processes speed signals and coordinates the coupling engagement to achieve synchronization without direct mechanical synchronization members
2Productivity
If the electric machine torque is increased during gear changes, then gear shifting speed is improved, but torque saturation and loss of control occur
Solution Approach 1:
The patent applies periodic modulation to the electric machine torque during gear changes, using pulsed torque applications coordinated with the coupling engagement timing to achieve rapid shifting while maintaining average torque within controllable limits
Solution Approach 2:
The patent dynamically adjusts the electric machine torque in real-time based on feedback from speed sensors and coupling position sensors, allowing torque to vary during the gear change process to optimize shifting speed while preventing saturation
3Device complexity
If the coupling system operates without mechanical synchronization members, then device complexity is reduced, but torque surges and mechanical wear increase
Solution Approach 1:
The patent implements a feedback control system that continuously monitors shaft speeds and coupling engagement position, using this information to adjust actuator commands in real-time to prevent torque surges during engagement without requiring mechanical synchronization members
Solution Approach 2:
The patent performs preliminary speed matching of the shafts using the electric machine before engaging the coupling, thereby reducing speed differential and preventing torque surges at the moment of engagement
4Power
If the inertia of the electric machine is increased during hybrid operation, then power output is improved, but torque saturation during gear changes worsens
Solution Approach 1:
The patent segments the torque control into distinct phases during gear changes, with different control strategies applied to the electric machine and heat engine separately, allowing the high-inertia electric machine to contribute power while its torque is managed independently to prevent saturation
Data Source
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AI summary
The invention relates to a method for synchronising the common speed (ω p) of two concentric primary shafts (1, 6) of a hybrid transmission in a hybrid operating mode wherein said two shafts are rotatably connected by a first coupling means (5), with the speed (ω s) of a secondary transmission shaft (10) comprising at least one idler pinion for allowing the coupling of one of said pinions (11, 12) to the shaft (10) thereof by closing a second coupling means (13) that does not have mechanical synchronisation bodies, the torque (Te) of the electric machine being temporarily reduced during the synchronisation phase in order to meet the conditions of a perfect coupling when the value thereof caps at an upper limit value ( T e max ) or a lower limit value ( T e min ).