Split Shift Drum for Dual Clutch Transmission Multiple Downshifts
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Solution Overview
Problem
Dual-clutch transmissions in motor vehicles face limitations in performing multiple downshifts without traction interruption, as existing shifting devices either require sequential gear changes or necessitate complex and space-consuming designs with multiple shift drums or decoupling shafts.
Innovation Solution
A shift drum design featuring an axially non-displaceable but rotatable first shift drum part and an axially displaceable second shift drum part, mounted via splines, allows for both sequential upshifts and downshifts, as well as multiple downshifts, by varying the effective course of shifting gates through a switching mechanism with control links, eliminating the need for separate shift drums and parallel selector shafts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single shift drum is used for both sub-transmissions, then device complexity is reduced, but multiple downshifts without traction interruption cannot be achieved
Solution Approach 1:
The shift drum is divided into two independently controllable parts: a first shift drum part for controlling the first sliding sleeve and a second shift drum part for controlling the second sliding sleeve. This segmentation allows each part to be actuated independently, enabling multiple downshifts without requiring a complete traction interruption, while maintaining relatively simple overall device complexity.
Solution Approach 2:
The shift drum parts are designed with different axial displacement capabilities: the first shift drum part is axially displaceable to enable sequential shifting, while the second shift drum part is axially fixed to enable direct multiple downshifts. This dynamic differentiation allows the system to adapt to different shifting requirements without increasing overall device complexity.
2Adaptability or versatility
If multiple shift drums or decoupling shafts are used to enable multiple downshifts, then multiple downshift capability is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent combines the functions of multiple shift drums into a single integrated shift drum structure with two controllable parts. The first and second shift drum parts work together on the same drum body, merging what would traditionally require separate components. This reduces device complexity and space requirements while maintaining the capability for multiple downshifts without traction interruption.
Solution Approach 2:
The single shift drum is designed to perform multiple functions: it controls both the first sliding sleeve (for odd gear stages) and the second sliding sleeve (for even gear stages) through its two independent parts. This multi-functionality eliminates the need for separate shift drums or decoupling shafts, reducing overall device complexity while enabling multiple downshift capabilities.
3Ease of operation
If axial displacement of shift drum parts is allowed for sequential shifting, then ease of operation is improved, but precision control for multiple downshifts becomes difficult
Solution Approach 1:
Different axial displacement characteristics are assigned to different parts of the shift drum: the first shift drum part has axial displacement capability for easy sequential shifting operation, while the second shift drum part has axial fixation for precise control of multiple downshifts. This local differentiation of properties allows each part to optimize for its specific function without compromising the other.
Solution Approach 2:
The system uses dynamic control where the first shift drum part can be axially displaced during sequential shifting operations, while the second shift drum part remains axially fixed during multiple downshift operations. This dynamic behavior is controlled through different actuation mechanisms, allowing the system to switch between operational modes as needed.
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
The device has a switching roller (2) which is connected with input shaft of a dual clutch transmission. The gear stage (I,III,V) is associated with input shaft of the dual clutch transmission. A shift drum controls the movement of shift rail (7b,9b), switching link (3-6) and switching contour. The shift drum is provided within the dual clutch transmission. The rotatable first shift drum portion (2a) is axially slidably mounted on second shift drum portion (2b), when shift drum is provided in the axially non-displaceable manner. An independent claim is included for dual clutch transmission.