Asymmetric CV Joint Tracks for Low-NVH High-Angle Torque Transfer
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Solution Overview
Problem
Existing constant velocity joints face challenges in efficiently transmitting rotational torque at various angles while minimizing noise, vibration, and harshness (NVH) issues.
Innovation Solution
The constant velocity joint assembly features an outer and inner joint member with asymmetric tracks, including first and second sets of tracks with specific piecewise continuous functions, which constrain the path of balls to form funnels that bias the cage and control over-ball clearance at high articulation angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If symmetric tracks are used in constant velocity joints, then the structure is simple and easy to manufacture, but noise, vibration, and harshness (NVH) issues occur at high articulation angles
Solution Approach 1:
The patent applies asymmetry by designing the outer race track with a different profile than the inner race track. Specifically, the outer race track has a first arc portion with a first radius of curvature and a second arc portion with a second radius of curvature, while the inner race track has corresponding arc portions with different radii of curvature. This asymmetric configuration creates a funnel-shaped ball path that biases the cage and reduces over-ball clearance at high articulation angles, thereby reducing NVH issues while maintaining manufacturing feasibility through precise but not overly complex track geometries.
2Ease of manufacture
If conventional track designs are used, then manufacturing is straightforward, but even loading of balls is not maintained at various articulation angles
Solution Approach 1:
The patent applies local quality by creating different track profiles at different locations along the ball path. The outer race track has a first arc portion with a first radius of curvature and a second arc portion with a second radius of curvature, while the inner race track has corresponding arc portions with different radii of curvature. This local variation in track geometry creates a funnel-shaped ball path that maintains even ball loading at high articulation angles, while the overall track design remains manufacturable through precise but not excessively complex geometries.
3Reliability
If asymmetric opposed tracks with specific piecewise continuous functions are used, then NVH issues are reduced and ball loading is maintained, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the race track paths into distinct segments or portions. The outer race track is divided into a first arc portion and a second arc portion, each with different radii of curvature. The inner race track is similarly divided into corresponding arc portions. This segmentation allows each portion to be optimized for specific functions (creating the funnel shape and biasing the cage) while keeping the overall design manageable and manufacturable through precise but not overly complex geometries.
Data Source
AI summary
A constant velocity joint assembly includes an outer joint member defining a first longitudinal axis and including a closed end, an open end, a first set of outer tracks extending at least partially between the closed end and the open end, and a second set of outer tracks extending at least partially between the closed end and the open end. The assembly also includes an inner joint member defining a second longitudinal axis coaxial with the first longitudinal axis and including a first set of inner tracks and a second set of inner tracks, the inner joint including an attachment feature to receive a driveshaft. A path followed by the center of a ball in the first set of tracks is constrained by an outer race track path and an inner race track path, the outer race track path being a piecewise continuous function.