Split Sun Gear Automatic Transmission Output Diameter Reduction
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Solution Overview
Problem
Existing automatic transmissions face challenges in reducing the diameter of the output side, particularly in longitudinally disposed configurations, which can compromise seating comfort due to increased dimensions, especially when transitioning from transversely to longitudinally disposed setups.
Innovation Solution
The design incorporates a first and second split sun gear configuration, where the input shaft passes through the first split sun gear, and the output shaft is constantly coupled to the second carrier, allowing for a compact configuration that avoids increasing the diameter of the planetary gear set, thereby reducing the overall transmission diameter on the output side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the output shaft diameter is increased to transmit larger torque in a longitudinally disposed automatic transmission, then the torque transmission capability is improved, but the overall diameter of the transmission increases, deteriorating seating comfort
Solution Approach 1:
The patent transitions from a transverse disposition (output shaft perpendicular to input shaft) to a longitudinal disposition (output shaft coaxial with input shaft), changing the spatial arrangement dimension. This allows the output shaft to be positioned centrally through the planetary gear set without increasing the radial diameter, as torque transmission is achieved through axial positioning rather than radial expansion.
Solution Approach 2:
The sun gear is divided into multiple segments (first sun gear and second sun gear) that can be independently engaged by different clutches. This segmentation allows selective torque transmission paths, enabling the output shaft to transmit required torque through engaged segments without needing to increase the overall shaft or gear diameter.
2Adaptability or versatility
If a transverse automatic transmission is converted to a longitudinal configuration without changing the transmission mechanism, then the adaptation to FR vehicles is improved, but the coupling of the output portion to the coaxial output shaft becomes impossible
Solution Approach 1:
The planetary gear set is segmented into multiple independent engagement zones with separate clutches (first clutch, second clutch) that can control different sun gears or gear elements. This segmentation allows the transmission mechanism to be reconfigured for longitudinal disposition by selectively engaging different segments, enabling adaptation from transverse to longitudinal configuration without redesigning the entire transmission mechanism.
Solution Approach 2:
The patent employs multiple clutches that can dynamically engage and disengage different planetary gear paths, allowing the transmission to adapt its configuration. This dynamic control enables the same transmission mechanism to function in both transverse and longitudinal dispositions by changing which clutch elements are engaged, providing versatility across different vehicle platforms.
Data Source
AI summary
An automatic transmission includes a first planetary gear set, a second planetary gear set, and a first brake. A first sun gear includes a first split sun gear on a drive source side, and a second split sun gear on a side opposite to the drive source. The first spilt sun gear is coupled to the first brake, and is fixed to a transmission case during engagement of the first brake. The second split sun gear is constantly coupled to a second sun gear. An input shaft is constantly coupled to a first carrier while passing through the first split sun gear, and between the first and second split sun gears. An output shaft is constantly coupled to a second carrier.