Split Group Transmission with Double Power-Branch Shifting
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Solution Overview
Problem
Existing group transmission devices lack a compact and variably shiftable design with a high gear spread, which limits their ability to efficiently manage torque distribution and gear shifting without interruption, particularly in motor vehicles.
Innovation Solution
A group transmission device with a planetary upshift and downshift assembly, featuring a second shift unit that connects the first idler gear for conjoint rotation to the third transmission element of the downshift assembly, allowing for double power-branched gears and a wide range of gears (12 forward and 4 reverse) with minimal circuit elements, enabling gear shifting without torque interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional gear transmission design is used, then the structure is simple, but the gear spread is limited and torque interruption occurs during shifting
Solution Approach 1:
The transmission is divided into two independent planetary assemblies (upshift and downshift) that can operate separately or in combination. Each assembly handles specific gear ranges, allowing the system to achieve a wide gear spread (12 forward gears) while maintaining structural simplicity within each segment. This segmentation eliminates torque interruption during shifting by allowing seamless transition between assemblies.
Solution Approach 2:
The transmission employs dynamic shifting mechanisms where planetary gears and clutch elements can be engaged or disengaged during operation. The first and second shift units dynamically reconfigure the power flow paths, enabling smooth gear transitions without torque interruption. The ability to switch between different planetary gear configurations provides adaptability for various driving conditions.
2Adaptability or versatility
If multiple shift units and circuit elements are added to achieve variable shifting, then gear variability improves, but device complexity increases
Solution Approach 1:
Two planetary assemblies are merged into a single integrated transmission system that shares common components such as the input shaft, housing, and lubrication system. The upshift and downshift assemblies are combined with shared clutch mechanisms, reducing the total number of independent circuit elements while maintaining the ability to provide 12 forward gears and 4 reverse gears through coordinated operation.
Solution Approach 2:
The planetary gear elements serve multiple functions: they provide gear reduction, enable torque multiplication, and facilitate smooth shifting through their inherent mechanical properties. The same planetary components are used across different gear ranges, and the shift units serve dual purposes of engaging different planetary sets and controlling torque flow paths, reducing the need for specialized components for each function.
3Volume of moving object
If a compact design is pursued, then space efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The planetary gears are nested within the planetary assemblies, with planet gears arranged around the sun gear in a compact circular configuration. The upshift and downshift assemblies are nested along the same input shaft, utilizing vertical space efficiently. This nested arrangement achieves a compact transmission volume while maintaining adequate clearance and meshing precision through standardized component design.
Data Source
AI summary
A group transmission device includes an upshift assembly with a first transmission element, a second transmission element and a third transmission element. A downshift assembly has a first transmission element, a second transmission element and a third transmission element. A main shaft is arranged coaxially to the upshift assembly and a layshaft is arranged parallel to the main shaft. A first idler gear is arranged coaxially to the main shaft and axially between the upshift assembly and the downshift assembly and is connectable to the main shaft for conjoint rotation by a first shift unit. The first idler gear is connectable to the third transmission element of the downshift assembly for conjoint rotation by a second shift unit.