Planetary Differential Transmission Device Space Optimization
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Solution Overview
Problem
Existing transmission devices for motor vehicles face challenges in compactly accommodating multi-speed capabilities within limited installation space, often requiring additional components like PTUs and occupying more space due to the use of ball differentials instead of planetary differentials.
Innovation Solution
A transmission device with a planetary gear set and a planetary differential, featuring a first ring gear, a second ring gear, and a locking element, which allows for a compact arrangement by integrating a range group in front of the axle drive and eliminating the need for a downstream PTU, utilizing a planetary differential instead of a ball differential to save space and achieve higher output torques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a ball differential is used in the axle drive, then the differential function is achieved, but the installation space is increased
Solution Approach 1:
The patent combines the differential function with the planetary gear set by integrating a planetary differential mechanism directly into the axle drive. The planetary differential is formed by the planetary gear set components (sun gear, planet gears, ring gear, and planet carrier), merging the differential function with the existing transmission structure to eliminate the need for a separate ball differential and reduce installation space.
Solution Approach 2:
The planetary gear set is designed to serve multiple functions simultaneously: it provides both the differential function and the transmission function. The same planetary components (sun gear, planet gears, ring gear, planet carrier) perform both differential motion distribution and gear ratio transformation, making the system multi-functional and space-efficient.
2Adaptability or versatility
If a downstream PTU is added to integrate a range group, then multi-speed capability is achieved, but the device complexity and installation space are increased
Solution Approach 1:
The patent integrates the range group functionality directly into the planetary gear set by using the planet carrier as a selectable output element. The locking element couples the ring gear to the planet carrier to provide a direct drive ratio, eliminating the need for a separate downstream PTU and reducing device complexity while maintaining multi-speed capability.
Solution Approach 2:
The locking element and range group mechanisms are nested within the planetary gear set structure. The locking element is integrated into the planet carrier assembly, and the direct drive path is formed by coupling existing planetary components together, nesting the range extension functionality within the existing gear set rather than adding external components.
3Productivity
If a locking element is added to couple the ring gear to the planetary gear carrier, then a direct drive ratio is achieved, but the device complexity is increased
Solution Approach 1:
The locking element merges the ring gear and planet carrier into a single kinematically coupled unit when engaged, creating a direct drive path. This coupling mechanism is integrated into the existing planetary gear structure, using the same structural components rather than adding entirely separate systems, thereby minimizing the increase in device complexity.
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a transmission device (10a; 10b) for a motor vehicle (11a), comprising: a final drive (12a; 12b); a planetary gearset (13a; 13b), which has at least one first transmission element (14a; 14b) formed by a first ring gear (15a; 15b), which first transmission element has external teeth for introducing a drive torque, at least one second transmission element (16a; 16b) and at least one third transmission element (17a; 17b), which is coupled to the final drive (12a; 12b); and at least one brake element (18a; 18b) for lockingly braking at least one of the transmission elements (14a, 16a, 17a; 14b, 16b, 17b) of the planetary gearset (13a; 13b), wherein the final drive (12a; 12b) is designed as a planetary differential, which is arranged radially inside the planetary gearset (13a; 13b) and is arranged in a gearwheel level (19a; 19b) with the planetary gearset (13a; 13b).