Nested Planetary Transmission Layout for Shifting Under Load
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Solution Overview
Problem
Modern transmissions face challenges in achieving small structural dimensions while enabling gear shifting under load with high power throughput, particularly in vehicles with hybrid drives, where existing designs often result in increased axial length due to the arrangement of planetary gears.
Innovation Solution
The transmission design incorporates a power split mechanism with a freewheel connecting the sun gear of the first planetary stage to the input shaft and a clutch connecting the ring gear of the second planetary stage to the input shaft, allowing selective coupling with multiple components, reducing the need for energy-dissipating brakes and enabling efficient shifting between numerous stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two planetary stages are arranged in front of each other to enable gear changes under load, then the transmission can switch between different gear stages, but the axial length increases
Solution Approach 1:
The patent applies nesting by arranging the first and second planetary stages concentrically, where components of one stage are positioned inside components of the other stage. The sun gear of the first planetary stage is surrounded by its planetary gears and ring gear, while the second planetary stage is arranged within the same radial space. This nested configuration allows both planetary stages to share the same axial space, enabling gear stage switching without increasing axial length.
Solution Approach 2:
The patent transitions from a linear arrangement of planetary stages along the axial direction to a radial/concentric arrangement in the transverse plane. By organizing the first and second planetary stages in concentric circles around the input shaft, the design utilizes the radial dimension to accommodate multiple stages, thereby maintaining compact axial length while preserving gear switching functionality.
2Length of moving object
If multiple planetary stages are combined to achieve compact dimensions, then the axial length is reduced, but the complexity of the transmission increases
Solution Approach 1:
The patent applies multi-functionality by designing the switching elements to perform multiple roles. Each switching element can selectively couple the input shaft to different components (sun gear, planetary bridge, ring gear) of either the first or second planetary stage, enabling a single switching element to control multiple gear stage transitions. This reduces the total number of switching elements needed and simplifies the overall control system.
Solution Approach 2:
The patent segments the power transmission path into distinct selectable routes through the first and second planetary stages. By dividing the complex multi-stage system into modular planetary units with standardized components (sun gear, planetary gears, ring gear, planetary bridge), the design simplifies the integration and control of each stage while maintaining compact overall dimensions.
3Adaptability or versatility
If switching elements are used to connect planetary stage components to enable gear changes under load, then gear stage switching is achieved, but the number of switching elements increases device complexity
Solution Approach 1:
The patent applies multi-functionality by designing the switching elements to perform multiple roles. Each switching element can selectively couple the input shaft to different components (sun gear, planetary bridge, ring gear) of either the first or second planetary stage, enabling a single switching element to control multiple gear stage transitions. This reduces the total number of switching elements needed and simplifies the overall control system.
Data Source
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AI summary
The invention relates to a transmission (100) comprising a housing (1), comprising an input shaft (2) for coupling-in a mechanical power and comprising an output shaft (3) for coupling-out the mechanical power, wherein the rotational speed of the output shaft (3) can be changed relative to the rotational speed of the input shaft (2) in shifting stages and under load, and comprising at least one planetary stage (5, 6) having multiple components at least including a sun gear (13), a planetary spider (14, 17) and a ring gear (15, 16, 18). According to the invention, a power split (4) is provided which is designed for splitting the mechanical power that can be coupled in at at least two different components of the planetary stage (5, 6), wherein, in addition, shifting elements (7, 9, 11) are designed such that, as part of the power split (4), the input shaft (2) can be optionally meshed with the at least two different components of the planetary stage (5, 6) by means of the shifting elements (7, 9, 11), wherein a first planetary stage (5) and a second planetary stage (6) are designed, and the ring gear of the first planetary stage (5) and the sun gear of the second planetary stage (6) are rotationally fixed to one another and form an intermediate element (16), wherein the first planetary stage (5) and the second planetary stage (6) are arranged sittingconfigured such that they sit inside one another and/or the shifting elements (7, 9, 11) connected to the input shaft (2) are arranged sittingdesigned such that they sit inside one another in a plane and/or the shifting elements (8, 10, 12) connected to the housing (1) are arranged sittingdesigned such that they sit inside one another.