Self-Aligning Cam Follower Roller for Misalignment Stress Relief
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Solution Overview
Problem
Cam follower roller devices in automotive and industrial applications experience edge stresses and increased contact pressure due to angular misalignment between the tappet body and housing axes, leading to operational inefficiencies.
Innovation Solution
A self-aligning cam follower roller device design featuring a tappet body with transverse gaps between the roller's frontal end faces and tappet bore, and a central cylindrical bore mounted on an annular rolling surface with a transverse convex profile, allowing the roller to tilt and accommodate angular misalignment, thereby reducing edge stresses and contact pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the roller is rigidly mounted on the pin with fixed transverse axis, then the structure is simple and stable, but edge stresses occur at the roller ends due to angular misalignment between tappet body and housing axes
Solution Approach 1:
The roller is designed to tilt angularly relative to the pin axis by utilizing transverse gaps between the roller's frontal end faces and the tappet bore. This dynamic adjustment allows the roller to accommodate angular misalignment between the tappet body and housing axes, reducing edge stresses at the roller ends while maintaining a relatively simple structural configuration.
2Reliability
If transverse gaps are provided between roller and tappet bore to allow angular movement, then edge stresses are reduced, but the roller may exhibit excessive play or instability
Solution Approach 1:
The transverse gaps between the roller's frontal end faces and the tappet bore are precisely controlled within specific dimensional ranges. This parameter optimization allows the roller to tilt sufficiently to accommodate angular misalignment and reduce edge stresses, while preventing excessive play that would compromise stability. The convex rolling surface geometry further constrains the roller's angular movement to appropriate limits.
3Ease of manufacture
If the roller axis is fixed perpendicular to pin axis, then manufacturing is simple, but contact pressure between roller and cam is increased due to misalignment
Solution Approach 1:
The roller is designed with the capability to tilt angularly relative to the pin axis through transverse gaps between the roller ends and tappet bore. This dynamic adjustment enables the roller to align itself with the cam surface even when there is angular misalignment between the tappet body and housing axes, thereby reducing contact pressure while maintaining manufacturing simplicity.
Solution Approach 2:
The pin is provided with a convex rolling surface that engages with the roller. This curved surface geometry facilitates the angular tilting of the roller relative to the pin axis, allowing the roller to accommodate misalignment and reduce contact pressure while maintaining a relatively simple manufacturing process for the convex surface.
Data Source
AI summary
A cam follower roller device including a tappet body extending along a longitudinal axis and defining a tappet bore, a pin centered on a transverse axis, through holes having mounting ends for supporting the pin on the tappet body, and a roller rotatably mounted on the pin around the transverse axis, the roller having a cylindrical outer surface, a central cylindrical bore and two frontal end faces. Transverse gaps are provided between frontal end faces of the roller and the tappet bore, and the central cylindrical bore of the roller is mounted around an annular rolling surface of transverse convex profile.