Nested Planetary Differential Transmission for Compact Vehicle Drivetrains
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Solution Overview
Problem
Existing differential transmissions for vehicles face challenges in extending service life, reducing production costs, and minimizing installation space while maintaining efficiency.
Innovation Solution
The proposed differential transmission design incorporates a first and second planetary gearset with specific torque-proof connections and support structures, allowing for a thinner and more efficient design that eliminates the need for direct oil supply between output shafts, thereby reducing weight and installation space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional differential transmission design is used, then the structure is robust and reliable, but the installation space is large and production costs are high
Solution Approach 1:
The first planetary gearset is nested within the second planetary gearset, with the first ring gear positioned inside the second ring gear. This nested arrangement allows both gearsets to occupy the same radial space, significantly reducing the overall installation space and volume of the differential transmission while maintaining the reliability provided by the dual planetary gearset configuration
Solution Approach 2:
The patent transitions from a conventional side-by-side planetary gearset arrangement to a nested concentric arrangement, utilizing the radial dimension more efficiently. By stacking gearsets in the radial direction rather than placing them laterally, the design reduces the overall footprint and installation space while preserving structural robustness
2Reliability
If direct oil supply between output shafts is implemented, then lubrication is effective, but the structure becomes complex and requires additional sealing elements
Solution Approach 1:
The second output shaft serves multiple functions: it acts as both an output shaft for torque transmission and as a support structure for the first planet carrier. This multi-functionality eliminates the need for separate support elements and complex oil supply channels, reducing structural complexity while maintaining effective lubrication through the integrated design
Solution Approach 2:
The support function for the first planet carrier is merged with the second output shaft structure itself, rather than being a separate component. This integration combines multiple functions into a single element, reducing the number of parts, simplifying the oil supply structure, and eliminating the need for additional sealing elements between separate components
3Reliability
If the first planet carrier is made thicker for structural strength, then reliability is improved, but the weight increases and service life is reduced
Solution Approach 1:
Instead of uniformly thickening the entire first planet carrier, the patent provides targeted reinforcement only at the critical load-bearing regions where the planet gears engage with the ring gear and sun gear. This local quality approach maintains structural strength and reliability at stress points while keeping the overall carrier thinner and lighter, thereby extending service life
Solution Approach 2:
The first planet carrier is constructed using composite material structures, combining different materials or material treatments in different regions. This allows for optimized strength-to-weight ratio, providing necessary structural strength at critical locations while maintaining overall thinness and reducing weight for extended service life
Data Source
AI summary
A differential transmission for a vehicle has a first planetary gearset and a second planetary gearset, where the first ring gear is in torque-proof connection with the second sun gear. The transmission further includes a first output shaft in torque-proof connection with the first planet carrier at a first side of the first planet gear in an axial direction, a second output shaft in torque-proof connection with the second ring gear, and a stationary component, with the second planet carrier being supported on the stationary component. The transmission additionally includes a support for rotatably supporting the first planet carrier on the stationary component, the support for the first planet carrier being at a second side of the first planet gear in the axial direction, the second side being opposite the first side relative to the first planet gear.