Universal Joint Socket Geometry to Prevent High-Torque Sticking
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Solution Overview
Problem
Existing universal joints for power tools face issues with the spherical head getting stuck in the socket hole under high torque, preventing smooth pivoting due to the design of convex and concave surfaces.
Innovation Solution
A universal joint design featuring a socket member with staggered, linear abutting portions and a driving member with a rounded base and column, where the abutting portions and evading portions are arranged to allow for smooth rotation and prevent sticking, utilizing an annular slot and retaining ring for secure engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the inner surface of the socket hole is composed of convex arc surfaces and concave arc surfaces to enable pivoting, then the spherical head can pivot relative to the socket hole, but the spherical head may get stuck in the socket hole under large torque at startup
Solution Approach 1:
The inner surface of the socket hole is segmented into multiple linear abutting portions and evading portions arranged alternately along the axial direction. This segmentation creates discrete contact points rather than continuous curved surfaces, allowing the spherical head to pivot smoothly while preventing it from getting stuck under high torque conditions.
Solution Approach 2:
Instead of using the conventional convex and concave arc surface design, the patent inverts the approach by using linear abutting portions with specific angle configurations. The abutting portions have adjacent edges forming angles between 177-180 degrees, creating a geometry that prevents sticking while enabling pivoting motion.
2Shape
If the spherical head has end corner portions formed by equiangular cross surfaces, then the structure provides defined contact points, but the spherical head may still get stuck under large torque
Solution Approach 1:
The patent applies local quality by creating evading portions at specific locations between the abutting portions on the spherical head. These evading portions have different geometric properties (circular arc shapes) compared to the linear abutting portions, providing localized clearance spaces that prevent the spherical head from getting stuck under high torque while maintaining defined contact points for pivoting.
Data Source
AI summary
A universal joint includes a socket member and a driving member. The socket member includes a receiving hole, and an inner periphery of the receiving hole is formed with first evading portions and first abutting portions staggered with each other to cause the first abutting portions not connected to each other. Each first abutting portion is provided with a first abutting face, a second abutting face, and an adjacent edge formed between the first abutting face and the second abutting face. One side of the adjacent edge forms an adjacent edge angle being greater than 177 degrees and less than 180 degrees. The driving member includes a rounded base arranged in the receiving hole and a driving column opposite to the rounded base.