Variable Thickness Differential Crown Rim for Tooth Biasing
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Solution Overview
Problem
The deformation of gearbox components under engine torque leads to reduced meshing quality and shortened gear teeth life due to biased teeth, which is not effectively addressed by existing technologies without modifying the gearbox or differential architecture.
Innovation Solution
The introduction of a differential crown with a circular intermediate rim featuring progressive thickness variations between thinner and thicker zones, positioned opposite the stiffest areas of the differential case, enhances flexibility and reduces tooth biasing without altering the gearbox or differential architecture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the diameter of shafts is increased or their length reduced to limit bending and tooth biasing, then the meshing quality improves, but the device complexity and manufacturing cost increase
Solution Approach 1:
The crown rim thickness is varied locally around its circumference, with thicker sections positioned opposite flexible zones of the differential case and thinner sections opposite stiff zones. This local variation in thickness provides targeted flexibility where needed without requiring global modification of shaft dimensions or case architecture.
2Reliability
If the crown rim thickness is reduced to increase flexibility and reduce tooth biasing, then the meshing quality improves, but the strength and robustness of the crown decreases
Solution Approach 1:
The crown rim thickness is varied locally around its circumference, with thicker sections positioned opposite flexible zones of the differential case and thinner sections opposite stiff zones. This local variation in thickness provides targeted flexibility where needed without requiring global modification of shaft dimensions or case architecture.
Solution Approach 2:
The thickness parameter of the crown rim is changed progressively around its circumference rather than being uniform. This parameter variation allows the crown to have different stiffness characteristics at different angular positions, reducing tooth biasing while maintaining overall structural integrity.
3Reliability
If lightening openings are introduced in the ring gear to reduce biasing, then the tooth biasing decreases, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The thickness parameter of the crown rim is changed progressively around its circumference rather than being uniform. This parameter variation allows the crown to have different stiffness characteristics at different angular positions, reducing tooth biasing while maintaining overall structural integrity.
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 tooth biasing by approximately 13 microns at maximum torque, maintaining robustness and improving gear meshing quality with a 7% reduction in slanting, while maintaining the existing architecture and fixing methods.
Implementation Method 1
the thickness of the crown evolves progressively on its circumference between narrower relief parts and thicker parts
Data Source
Figure 1~2B
Figure 3~4
Figure 5~6
AI summary
Differential ring (7) comprising an intermediate circular rim (12) between an outer ring (11) in which its drive teeth (7a) are made and an inner ring (13) ensuring the centering of the ring (7) on the differential housing (9), characterized in that the intermediate rim (12) has lightening zones (12b), intended to give the ring greater flexibility in these zones than on the rest of its circumference.