Powertrain Shift Control for Gearbox Cog-To-Cog Avoidance
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Solution Overview
Problem
The challenge of achieving fast and comfortable gear shifts during unsynchronized main gear engagements in vehicle powertrains, particularly when starting, is hindered by cog-to-cog conditions, which can result in prolonged engagement times and driver discomfort, and often requires repeated clutch engagement, leading to wear.
Innovation Solution
A method and control device that utilize a synchromesh arrangement to induce and control a difference in rotational speed between the gear wheel and coupling sleeve, avoiding cog-to-cog conditions by partially engaging the gear wheel with the input shaft, thereby ensuring proper intermeshing and minimizing clutch usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clutch is used to overcome cog-to-cog conditions by repeated engagement and disengagement, then the gear shift can eventually be completed, but the clutch wear increases and the gear shift time is prolonged
Solution Approach 1:
The patent introduces a synchromesh arrangement as an intermediary mechanism between the gear wheel and coupling sleeve. This synchromesh arrangement temporarily mediates the speed difference between rotating and stationary components, enabling smooth engagement without requiring repeated clutch operations, thereby reducing clutch wear while ensuring reliable gear shift completion
Solution Approach 2:
The patent applies preliminary action by using the synchromesh arrangement to pre-synchronize the rotational speeds of the gear wheel and coupling sleeve before the final engagement. This preliminary speed matching prevents cog-to-cog conditions from occurring in the first place, eliminating the need for corrective clutch operations and reducing overall clutch wear
2Reliability
If the difference in angular velocity between coupling sleeve and gear wheel is reduced to avoid cog-to-cog conditions, then proper engagement is more likely, but the gear shift time becomes excessively long
Solution Approach 1:
The patent employs periodic action through the synchromesh arrangement, which periodically engages and disengages to gradually reduce the speed difference between components. This periodic synchronization process maintains a controlled, moderate difference in angular velocity that prevents cog-to-cog conditions while achieving engagement in a reasonable time frame, rather than requiring extremely slow speed matching
3Reliability
If the vehicle is at standstill with zero angular velocity difference for starting gear, then propulsion can be initiated, but the engagement time becomes infinity if no action is taken
Solution Approach 1:
The patent applies preliminary action by using the synchromesh arrangement to pre-establish rotational speed difference before engagement. When the vehicle is at standstill, the synchromesh arrangement is engaged first to create the necessary speed difference, ensuring that when the coupling sleeve engages the gear wheel, there is already a controlled angular velocity difference that prevents infinity-long engagement while enabling reliable starting gear engagement
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 approach enables fast, accurate, and comfortable gear shifts by overcoming cog-to-cog conditions, reducing clutch wear, and improving starting gear engagement accuracy, while maintaining mechanical component integrity.
Implementation Method 1
controlling the synchromesh arrangement so as to induce and/or increase a difference in rotational speed between the first gear wheel and the first coupling sleeve by at least partly engaging the first gear wheel or the second gear wheel to the input shaft
Data Source
AI summary
A control device and a method for controlling a vehicle powertrain to overcome, or avoid, a cog-to-cog condition during gear shifting is provided. The method comprises, when an input shaft of the gearbox is rotating, controlling a synchromesh arrangement so as to induce a difference in rotational speed between a first gear wheel and a first coupling sleeve arranged to lock the first gear wheel to a main shaft of the gearbox by at least partly engaging the first gear wheel or a second gear wheel to the input shaft. Furthermore, a computer program, a computer-readable medium and a vehicle are provided.