Selector Drum Shifting Contour for Faster Multiple Downshifts

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Solution Overview

Problem

Dual clutch transmissions with selector drums require long shifting times for multiple downshifts due to the sequential arrangement of gear stages, leading to prolonged clutch slip and inefficient tractive effort transmission.

Innovation Solution

A selector drum design with a switch gear portion and shifting contour that allows the high gear stage to remain engaged during multiple downshifts from high to low gear without shifting the middle gear stage, utilizing a shifting contour switch that prevents middle gear engagement in the second direction of rotation, enabling immediate engagement of the low gear stage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If gear stages are arranged sequentially on the selector drum for multiple downshifts, then all gear stages can be accessed, but shifting time increases and clutch slip prolongs

Engineering Contradiction:

Improveaccess to all gear stagesVSAvoidshifting time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The shifting contour is segmented into distinct functional regions: a first region for engaging the middle gear stage, a second region for disengaging the middle gear stage, and a third region that allows the high gear stage to remain engaged. This segmentation enables selective engagement/disengagement of gear stages during rotation, allowing multiple downshifts without traversing the entire circumferential path for each shift.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The shifting contour is designed in advance with predetermined engagement and disengagement regions positioned at specific circumferential locations. The middle gear stage engagement region is positioned such that when traversed in the first rotational direction, the middle gear stage is engaged before the high gear stage is disengaged, preparing the transmission for subsequent downshifts without requiring full sequential traversal.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the selector drum rotates through all gear stages for multiple downshifts, then proper gear engagement is achieved, but clutch slip time increases

Engineering Contradiction:

Improvegear engagement accuracyVSAvoidclutch slip energy

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The shifting contour is divided into specialized segments: a first segment that engages the middle gear stage at a specific circumferential position, a second segment that disengages it, and a third segment that maintains high gear engagement. This segmentation allows the transmission to skip unnecessary gear stage traversals during multiple downshifts, reducing clutch slip time and energy loss while ensuring reliable engagement at critical points.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The shifting contour dynamically adapts its engagement behavior based on rotational direction. When rotated in the first direction, it engages the middle gear stage; when rotated in the second direction, it allows the high gear stage to remain engaged while skipping the middle gear stage. This dynamic behavior optimizes clutch slip minimization while maintaining engagement reliability.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If a passive switch design is used for the shifting contour switch, then device complexity is reduced, but functionality for multiple downshifts is limited

Engineering Contradiction:

Improveswitch construction complexityVSAvoidmultiple downshift capability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The shifting contour incorporates a localized switch gear portion with an active shifting contour switch at a specific circumferential position, while other regions maintain simpler contour features. This active switch provides directional sensitivity to enable multiple downshifts without requiring complex mechanisms throughout the entire shifting contour, thus balancing functionality with controlled complexity.

Inventive Principle:

Principle #3Local quality

4Stability of the object's composition

If the middle gear stage is engaged during multiple downshifts, then sequential shifting is maintained, but shifting time increases

Engineering Contradiction:

Improvesequential shifting sequenceVSAvoidmultiple downshift time

Core Design Contradiction:

Stability of the object's compositionVSLoss of time

Solution Approach 1:

The shifting contour dynamically adjusts the engagement state of the middle gear stage based on rotational direction. In the second rotational direction, the contour is designed to disengage the middle gear stage while maintaining high gear engagement, allowing multiple downshifts to occur without sequentially traversing the middle gear stage. This dynamic approach maintains transmission stability while significantly reducing multiple downshift time.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11460107B2Selector drum and motor-vehicle manual transmission

Publication Date: 2022.10.04 MAGNA PT B V & CO KG

AI summary

A selector drum for an automated manual transmission, in particular a dual clutch transmission, having a selector drum body, which can be mounted in the manual transmission for rotation about an axis of rotation, wherein at least one shifting contour is formed on the selector drum body, said shifting contour extending over a peripheral portion of the selector drum body, wherein the selector drum is designed for shifting at least one high gear stage, one middle gear stage and one low gear stage, wherein the at least one shifting contour has a shifting contour switch in a region of a switch gear portion.