Planetary Spur Gear Differential With Reduced Axial Dimension
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Solution Overview
Problem
Conventional differential systems have large axial dimensions, heavy housing and angle gear masses, and poor reliability due to their symmetrical angle gear structure, which limits their effectiveness in power transmission.
Innovation Solution
A differential system utilizing a planetary differential principle with a compact and simple structure, featuring a high space utilization ratio, small axial dimension, and improved production and assembly advantages, achieved through the use of cylindrical gears and a unique gear ring configuration that reduces axial gaps and enhances reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a symmetrical angle gear structure is used to implement inter-wheel speed differential, then the differential function is achieved, but the axial dimension becomes excessively large
Solution Approach 1:
The patent replaces the conventional symmetrical angle gear mechanical system with a planetary gear system. This substitution fundamentally changes the mechanical arrangement from angle gears requiring large axial space to planetary gears that achieve differential function with compact axial dimension, directly resolving the contradiction between differential function and axial size.
Solution Approach 2:
The invention transitions from the angle gear's axial dimension dominance to the planetary gear's radial dimension utilization. By arranging gears in a radial planetary configuration rather than axial angle gear stacking, the differential function is achieved while minimizing axial dimension and utilizing radial space more efficiently.
2Reliability
If a symmetrical angle gear structure is used, then the differential function is implemented, but the mass of the housing and angle gear becomes heavy
Solution Approach 1:
The patent substitutes the heavy angle gear system with a planetary gear system. This replacement reduces mass by eliminating the need for large-angle gear teeth and extensive housing structures, achieving the same differential function with significantly reduced weight of moving components.
Solution Approach 2:
The invention merges multiple functions into the planetary gear assembly, where the planetary gears, carrier, and ring gear work together as an integrated unit. This consolidation eliminates separate angle gears and their supporting housing structures, reducing overall mass while maintaining differential functionality.
3Device complexity
If original components are omitted and planetary gear is directly mounted on secondary plate, then the number of parts is reduced and structure is simplified, but the axial dimension remains large
Solution Approach 1:
The patent addresses the axial dimension issue by changing the spatial arrangement from axial stacking (angle gears) to radial positioning (planetary gears). This dimensional change allows the simplified structure to achieve compact axial dimension by utilizing radial space for gear arrangement rather than requiring axial length.
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
The solution results in a more compact, reliable, and efficient power transmission system with reduced weight and size, improved torque distribution, and increased transmission efficiency, while also reducing friction, noise, and heat generation, thereby enhancing the overall performance and longevity of the differential.
Implementation Method 1
The planetary gear is mounted on a secondary plate of the driven gear of a final drive through a square shaft and a shaft sleeve and is meshed with the center gear, so as to implement revolution and moving functions thereof by a revolution pair and a planar moving pair
Data Source
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AI summary
A differential(100) includes: a first planetary carrier(11), a first gear ring(13), and a first planetary gear(12) disposed on the first planetary carrier(11) and meshed with the first gear ring(13); and a second planetary carrier(21), a second gear ring(23), and a second planetary gear(22) disposed on the second planetary carrier(21) and meshed with the second gear ring(23) and the first planetary gear(12); the first gear ring(13) and the second gear ring(23) are configured as two power output ends of the differential(100), the first planetary carrier(11) and the second planetary carrier (21) are configured as power input ends of the differential(100); and a revolution radius of the first planetary gear(12) is different from a revolution radius of the second planetary gear(22). A power transmission system and a vehicle which comprises the differential(100) are also provided. The differential(100) is spur gears type, thus it is simple to be manufactured.