Planet Carrier Preload Sealing in Vehicle Transmissions
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Solution Overview
Problem
Existing power train transmissions with a housing-fixed planet carrier face challenges in preventing tilting during assembly and operation, which can lead to stress peaks and damage in the planetary gear set.
Innovation Solution
The implementation of an axially compressible sealing element or spring element to preload the planet carrier against a stationary housing part, ensuring it remains parallel to the rotation axis and preventing tilting, while also providing a sealing effect to maintain lubricant within the transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the planet carrier is fixed to the housing, then the transmission can be used in different applications including integral differentials, but the planet carrier may tilt during assembly and operation causing stress peaks and damage
Solution Approach 1:
The sealing element is pre-compressed during assembly to create an axial preload force that holds the planet carrier in its correct position before operation begins. This preliminary action prevents tilting from occurring during both assembly and operation, ensuring the planet carrier remains stable while maintaining the fixed-to-housing configuration needed for various applications
2Reliability
If the planet carrier is rigidly fixed to prevent tilting, then stability is improved, but the transmission requires additional components increasing complexity
Solution Approach 1:
The sealing element serves dual functions: it provides the necessary sealing to prevent lubricant leakage and simultaneously generates the axial preload force to prevent planet carrier tilting. By combining these two functions into a single component, the solution improves planet carrier stability without proportionally increasing transmission complexity
Solution Approach 2:
The sealing element automatically generates the required axial preload force through its own compression during assembly, without requiring separate adjustment mechanisms or additional active components. The sealing element self-regulates to maintain the planet carrier in the correct position, reducing the need for complex external stabilization systems
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively prevents the planet carrier from tilting, ensuring a uniform load on the planetary gear set, reduces stress peaks, and maintains lubricant within the transmission, enhancing the transmission's operational stability and longevity.
Implementation Method 1
an axially compressible sealing element or spring element to preload the planet carrier against a stationary housing part
Implementation Method 2
providing a sealing effect to maintain lubricant within the transmission
Data Source
AI summary
A transmission for a power train of a motor vehicle has a first stationary housing part having a first axial contact surface, a second stationary housing part, and a first sealing element on the second stationary housing part, the first sealing element being axially compressible. Additionally, the transmission includes a first planetary gear set including a planet carrier, at least one planet gear, a sun gear, and a ring gear. The planet carrier is fixed relative to one or both of the first stationary housing part and the second stationary housing part. One side of the planet carrier rests against the first axial contact surface, where the first sealing element acts on another side of the planet carrier to axially preload the planet carrier against the first axial contact surface to prevent the planet carrier from tilting relative to a rotation axis of the first planetary gear set.