Planetary Carrier Web Curvature for Strength With Less Material
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Solution Overview
Problem
Existing planetary carriers in transmissions face challenges in achieving a balance between mechanical strength, weight reduction, and material efficiency, leading to increased mechanical stresses and complex production processes.
Innovation Solution
A planetary carrier design featuring anticlastic curved outer surfaces on webs that connect opposite side walls, allowing for increased radii and reduced material usage, which enhances mechanical strength and weight reduction while simplifying production by casting, and incorporating features like convex and concave curvatures to manage stress profiles and lubricant passages effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional planetary carrier designs with flat or simple curved webs are used, then material usage is reduced, but mechanical strength decreases and mechanical stresses increase
Solution Approach 1:
The web features an anticlastic curved outer surface with different radii of curvature in different directions (larger radius in the direction of applied load, smaller radius in the transverse direction). This curved geometry distributes mechanical stresses more effectively throughout the material, increasing structural strength while maintaining reduced material usage compared to conventional flat or uniformly curved designs.
2Strength
If planetary carrier components are produced with complex geometries to achieve high strength, then mechanical strength increases, but production complexity and manufacturing difficulty increase
Solution Approach 1:
The anticlastic curved outer surface of the web, with its specific combination of radii of curvature, can be directly formed during the casting process. This eliminates the need for complex secondary machining operations or assembly of multiple parts, thereby achieving high mechanical strength through geometry alone while maintaining ease of manufacture via conventional casting methods.
3Strength
If increased material usage is employed to enhance mechanical strength, then mechanical strength increases, but weight increases
Solution Approach 1:
The anticlastic curvature of the web outer surface optimizes the distribution of material in three-dimensional space, placing material where it is most effective for stress resistance. This allows the planetary carrier to achieve high mechanical strength with minimized material volume, thereby reducing weight while maintaining structural integrity under operational loads.
4Quantity of substance
If small radii are used in web geometry to reduce material usage, then material usage is reduced, but mechanical stresses increase
Solution Approach 1:
The web is designed with an anticlastic curved outer surface that has a larger radius of curvature in the direction where tensile stresses occur (direction of applied load) and a smaller radius in the transverse direction. This geometric configuration reduces stress concentrations by providing smoother transitions and more favorable stress distribution, thereby maintaining low material usage while preventing excessive mechanical stresses.
Data Source
AI summary
A one-piece planetary carrier includes first and second side walls connected to one another by a plurality of webs. At least one of the webs has a curved outer surface which is directed substantially outward in a radial direction and belongs to a lateral surface of the web. The web includes a transition to the first side wall and a transition to the second side wall. The curved outer surface is convexly curved about a first axis of curvature at the transition to the first side wall and the transition to the second side wall. The curved outer surface has at least one anticlastic region which lies in an axial central section and an axial edge section of the web, with a combination of the axial central section with the axial edge section substantially defining an axial dimension of the planetary carrier.