Constant Velocity Joint Holding Geometry for Lower Induced Thrust
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Solution Overview
Problem
Existing constant velocity joints experience increased induced thrust and frictional resistance due to unstable contact loads and high sliding resistance between holding portions and rollers, leading to noise and vibration issues.
Innovation Solution
A constant velocity joint design featuring an outer member with guide grooves and an inner member with holding portions that include alternating contact and non-contact parts, where the contact parts have specific parallel and orthogonal surfaces with varying curvature radii, allowing for stable contact loads and reduced frictional resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If protrusions are formed on a curved sidewall of a holding portion to increase contact area, then contact load increases, but sliding resistance and induced thrust increase leading to noise and vibration
Solution Approach 1:
The holding portion sidewall is divided into multiple localized contact parts with different orientations (first parallel part, second parallel part, first orthogonal part, second orthogonal part) that contact the roller at different locations and angles. This local differentiation allows optimized contact distribution that reduces sliding resistance while maintaining adequate contact load.
Solution Approach 2:
The holding portion sidewall incorporates curved surfaces with varying curvature radii - the first curved surface has a smaller curvature radius while the second curved surface has a larger curvature radius. This curved geometry enables smoother roller contact and rotation, reducing sliding resistance and induced thrust compared to flat surfaces.
2Ease of manufacture
If the holding portion structure is simplified for easier manufacturing, then manufacturing cost decreases, but contact load stability deteriorates
Solution Approach 1:
The sidewall structure uses localized functional regions (different contact parts with specific orientations) that can be integrated into a single forging operation. Each contact part serves a specific purpose in maintaining stable contact load, while the overall structure remains manufacturable through conventional forging processes.
Solution Approach 2:
The curved surfaces with controlled curvature radii are designed to be compatible with forging processes. The gradual curvature transitions from the first curved surface to the second curved surface can be achieved through controlled metal flow during forging, maintaining structural stability while ensuring manufacturability.
3Reliability
If the curvature radius of the holding portion sidewall is increased to reduce stress concentration, then durability improves, but roller rotation friction increases
Solution Approach 1:
The sidewall curvature is segmented into two distinct regions: the first curved surface with smaller curvature radius that facilitates roller rotation and reduces friction, and the second curved surface with larger curvature radius that reduces stress concentration. This segmentation allows each region to optimize for its specific function.
Solution Approach 2:
Different curvature radii are applied to different locations on the sidewall based on functional requirements. The first curved surface near the contact point uses smaller curvature to minimize friction during roller rotation, while the second curved surface further away uses larger curvature to reduce stress concentration and improve durability.
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 design achieves stable contact loads and reduced frictional resistance, resulting in lower induced thrust and improved durability by maintaining roller assemblies parallel to guide grooves, thus enhancing the joint's operational efficiency and reducing noise and vibration.
Implementation Method 1
Each of the roller assemblies is rotatably attached to the corresponding holding portion. Each of the roller assemblies includes an inner roller and an outer roller, the outer roller being attached to an outside of the inner roller via a rolling member.
Data Source
AI summary
An inner member of a constant velocity joint includes holding portions that hold roller assemblies. Each of the holding portions includes a first orthogonal part and a second orthogonal part brought into contact with an inner roller of the roller assembly. When first and second transmission shafts are coaxially disposed, top parts of the first and second orthogonal parts are brought into contact with the inner circumferential wall of the inner roller. The first and second orthogonal parts are each sectioned into a first curved surface extending from the proximal end of the holding portion to the top part and a second curved surface extending from the top part to the distal end of the holding portion. The curvature radius of the second curved surfaces is larger than the curvature radius of the first curved surfaces.