Nested Planetary Drive Axle for Compact High-Ratio Packaging
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Solution Overview
Problem
Existing drive axles for vehicles face challenges in achieving a compact packaging size while maintaining high performance and durability, particularly in systems with planetary gear sets and bevel gear differentials.
Innovation Solution
A drive axle design featuring a bevel gear differential nested within a stepped planet stage, where the larger and smaller planet gear wheels and planet carrier axle form a torsionally rigid unit, connected via a differential input bearing, and supported by a support bearing, allowing for compact nesting and efficient torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the bevel gear differential is nested inside the stepped planet stage, then the packaging size is reduced, but the assembly complexity increases
Solution Approach 1:
The bevel gear differential is nested inside the stepped planet stage, with the differential housing positioned within the planetary gear structure. This nesting arrangement allows the differential to share space with the planet gears, significantly reducing the overall packaging volume of the drive axle while maintaining all necessary functional components.
Solution Approach 2:
The differential input is merged with the planet carrier axle by forming a torsionally rigid unit between the larger planet gear wheel, smaller planet gear wheel, and planet carrier axle. This merging eliminates the need for additional bearings and reduces assembly complexity despite the nested configuration.
2Reliability
If the differential input is connected to the planet carrier axle via a differential input bearing, then the rotational movement is compensated, but the number of bearings increases
Solution Approach 1:
The differential input is merged with the planet carrier axle by forming a torsionally rigid unit between the larger planet gear wheel, smaller planet gear wheel, and planet carrier axle. This merging eliminates the need for additional bearings that would otherwise be required to support separate differential and planetary gear assemblies, thereby reducing the total bearing count while maintaining rotational movement compensation through the integrated structure.
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 design reduces abrasive effects, enhances durability, and achieves a high total gear ratio with reduced packaging size and mass moment of inertia, improving efficiency and durability.
Implementation Method 1
the interface between the differential cage and the planet shaft comprises a differential input bearing
Implementation Method 2
a planetary gear set, comprising a static ring gear wheel and a stepped planet stage, wherein said bevel gear differential is at least in sections nested inside said stepped planet stage
Data Source
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AI summary
The disclosed invention refers to a drive axle (12) with a bevel gear differential (24) having a differential cage (26) as an input (28) and two drive shafts (16; 18) as differential outputs (32; 34). The differential cage (26) is driven by a planet carrier (40) of a planetary gear set (36), said planet carrier (40) providing a plurality of planet shafts (40), each forming a stiff unit with two planet wheels (42; 44) stepped in diameter. The planet carrier (40) is driven by a sun wheel (46) and counter-acts with a static ring wheel (48). While the planet carrier (40) drives the differential cage (26) and orbits around the differential (24) in its entirety, said differential (24) is compactly disposed between the planet shafts (40).