Selector Drum Switching Contour for Multi-Downshift Gear Skipping
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Solution Overview
Problem
Dual-clutch transmissions require long shift times for multiple downshifts due to the sequential arrangement of gears, leading to inefficiencies and increased costs with complex active switches.
Innovation Solution
A shift drum design that allows multiple downshifts from high to low gear without engaging the middle gear, utilizing a switching contour with a widened section to maintain high gear engagement until low gear is engaged, and incorporating a passive or active switching mechanism to optimize shifting times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple downshifts are performed through sequential gear stages, then gear shifting is achieved, but shift time increases and transmission efficiency decreases
Solution Approach 1:
The patent enables skipping intermediate gear stages during downshifts. The shift drum is designed with switching contours that allow direct engagement of lower gears from higher gears without sequentially passing through intermediate gears. This skipping mechanism dramatically reduces shift time while maintaining transmission functionality.
Solution Approach 2:
The shift drum pre-positioning mechanism prepares the transmission for rapid downshifts by maintaining engagement of higher gear stages until the lower gear is ready to engage. The widened section of the switching contour allows the high gear stage to remain engaged longer, enabling smooth transitions without interrupting power flow.
2Ease of operation
If active switches are used to control gear shifting, then shifting control is improved, but device complexity and cost increase
Solution Approach 1:
The shift drum incorporates passive switches that automatically detect and respond to gear engagement positions without requiring complex active control systems. The switching contours are designed to mechanically interact with cam followers, enabling the system to self-regulate gear shifts based on physical position rather than electronic commands, thereby reducing complexity.
Solution Approach 2:
The patent introduces cam followers as intermediary elements that translate the mechanical position of the shift drum into gear engagement actions. These passive cam followers ride along the switching contours and automatically activate the appropriate gear stages, serving as a simple mechanical mediator between the shift drum and the gear sets.
Data Source
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AI summary
The invention relates to a selector drum (28; 34) for an automated manual transmission (14), in particular a dual clutch transmission (14), comprising a selector drum body (29; 35), which can be mounted in the manual transmission (14) for rotation about an axis of rotation (30; 36), at least one shifting contour (32; 38) being formed on the selector drum body (29; 35), which shifting contour extends over a peripheral portion (40) of the selector drum body (29; 35), the selector drum (28; 34) being designed for the selection of at least one high gear stage (7; 6), one middle gear stage (5; 4) and one low gear stage (3; 2), the at least one shifting contour (32; 38) having a shifting contour switch (64) in a region of a switch gear portion. The switch gear portion (60; 84) is associated with the middle gear stage (5; 4). The switch gear portion (60; 84) is designed, by means of the shifting contour switch (64), in such a way that the middle gear stage (5; 4) is selected in a first direction of rotation (42) of the selector drum body (29, 35) and is not selected in a second direction of rotation (44). The at least one shifting contour (32; 38) is also designed in such a way that, in the second direction of rotation (44) of the selector drum body (29; 35), the high gear stage (7; 6) can remain selected if a driver element (48) associated with the middle gear stage (5; 7) is in a region of the switch gear portion (60; 84), such that, proceeding from the high gear stage (7; 6), the low gear stage (3; 2) can be selected without selection of the middle gear stage (5; 4).