Sintered Electromagnetic Coupling Cam With Segmented Spline Teeth
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Solution Overview
Problem
The first cam in conventional electromagnetic couplings experiences stress concentration on spline teeth roots due to the absence of tooth-missing parts, leading to reduced fatigue strength and a shorter lifespan.
Innovation Solution
A sintered member with alternating tooth groups and tooth-missing parts, where the tooth-missing parts overlap ball grooves, reducing stress concentration on spline teeth roots by forming a rounded shape in the overlapping areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If continuous spline teeth are provided along the circumferential direction of the first cam, then the transmission of rotational force is improved, but stress concentration occurs at the spline teeth roots reducing fatigue strength
Solution Approach 1:
The first cam is designed with segmented spline teeth that are discontinuous along the circumferential direction, with intentional gaps (tooth-missing parts) between them. This segmentation prevents continuous stress propagation around the circumference while maintaining sufficient force transmission capability through the distributed tooth groups, thereby resolving the contradiction between force transmission and fatigue strength.
Solution Approach 2:
The first cam exhibits non-uniform structural distribution along the circumferential direction, with tooth groups concentrated in specific angular regions and tooth-missing parts in others. This local quality variation allows stress to be distributed to specific zones rather than concentrated continuously, improving fatigue strength while maintaining adequate force transmission in the toothed regions.
2Strength
If tooth-missing parts are introduced to reduce stress concentration, then fatigue strength is improved, but the transmission of rotational force may be reduced
Solution Approach 1:
Instead of providing continuous spline teeth around the entire circumference, tooth groups are provided only in specific angular regions (partial action), with intentional gaps elsewhere. This partial tooth configuration reduces overall stress accumulation while maintaining sufficient force transmission capability in the regions where teeth are present, balancing fatigue strength and force transmission.
3Ease of manufacture
If the first cam is made as a single piece, then manufacturing is simplified, but stress concentration cannot be effectively controlled
Solution Approach 1:
The first cam is designed with specific geometric parameters including discontinuous tooth distribution, varying tooth depths, and controlled root radii in different angular positions. These parameter variations allow stress concentration to be controlled through geometric design rather than requiring complex multi-piece construction, maintaining manufacturing simplicity while improving fatigue strength.
Data Source
AI summary
A sintered member having an annular shape, includes: a first face facing one side in an axial direction; a second face facing the other side in the axial direction; an inner peripheral face connected to an inner peripheral edge of the first face; and a plurality of tooth groups and a plurality of tooth-missing parts which are alternately disposed along a circumferential direction of the inner peripheral face. The second face includes a plurality of ball grooves arranged in parallel in the circumferential direction. Each tooth group includes a plurality of spline teeth that are continuous in the circumferential direction of the peripheral face. The number of plurality of tooth-missing parts is the same as the plurality of ball grooves. Positions in a radial direction in which the plurality of tooth-missing parts are formed are within ranges in the radial direction in which the ball grooves are formed.