Idler Gear Synchronization for Shock-Free Gearbox Coupling

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Solution Overview

Problem

Existing methods for synchronizing an idler gear in a parallel-shaft gearbox without mechanical synchronization members result in unpleasant shocks during gear changes due to excessive energy absorption by the vehicle, leading to uncomfortable riding experiences.

Innovation Solution

The speed differential during idler gear synchronization is dynamically calculated and controlled based on the energy absorbed by the vehicle, ensuring it remains below a tolerance threshold by adjusting the speed differential as a function of the energy absorbed, thereby minimizing the shock felt during gear changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a speed differential is established to enable gear engagement, then the gear coupling is achieved, but the vehicle absorbs excessive energy causing unpleasant shocks

Engineering Contradiction:
Improvegear engagementVSAvoidenergy absorbed by vehicle
Core Design Contradiction:
Ease of operationVSLoss of energy

Solution Approach 1:

The system performs preliminary synchronization of the idler gear speed with the secondary shaft speed before engagement occurs. By pre-adjusting the speed differential to be minimal rather than large, the system prepares the components for smooth coupling, preventing excessive energy absorption and shocks during the actual engagement moment.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system dynamically controls the speed differential between the idler gear and secondary shaft during the engagement process. Rather than using a fixed large speed differential, the control system continuously adjusts the differential to maintain optimal values that enable engagement while minimizing energy absorption and shock transmission to the vehicle.

Inventive Principle:
Principle #15Dynamics

2Object-affected harmful factors

If the speed differential is reduced to minimize energy absorption, then vehicle comfort is improved, but the duration of tooth-to-tooth engagement increases

Engineering Contradiction:
Improvevehicle shockVSAvoidengagement duration
Core Design Contradiction:
Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The system changes the parameter of speed differential from a large fixed value to a dynamically adjusted minimal value. This parameter transformation allows the system to achieve smooth engagement with minimal energy absorption while the control system manages the engagement duration by precisely controlling the timing and magnitude of the speed differential throughout the engagement sequence.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3516270B1Method for synchronising an idler gear on a gearbox shaft
Publication Date: 2021.02.24 RENAULT SA
  • EP3516270B1 patent drawingFigure 1~2
  • EP3516270B1 patent drawingFigure 3
  • EP3516270B1 patent drawingFigure 4

AI summary

A method for synchronising an idler gear before coupling of same on a secondary shaft of a parallel-shaft gearbox comprising at least one primary shaft connected to a drive source of a vehicle, at least one secondary shaft carrying the idler gear for transmitting the torque from the drive source to the wheels of the vehicle at a transmission ratio, and at least one coupling means for coupling the idler gear to the shaft of same having no mechanical synchronisation members, characterised in that the drive source is controlled, before the coupling, at a speed imposing a differential speed with respect to the synchronisation speed thereof at the transmission ratio which is to be engaged, this differential being determined as a function of the quantity of energy absorbed by the vehicle at the time of coupling in response to the disappearance of the differential.