Rocker Arm Spring Retainer Non-Uniform Radius Design
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Solution Overview
Problem
Conventional rocker arm assemblies experience stress-related failures due to repetitive use, leading to micro-cracks and fanning of springs, which results in valve actuation failure and contamination in the engine compartment.
Innovation Solution
A retainer with a unique annular retaining surface design that abuts the coil spring without contacting the first arm, reducing stress points and minimizing fanning, featuring an inner tubular portion with specific radii and chord configurations to secure the spring effectively against the rocker arm body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional rocker arm assembly is used, then the valve train can operate, but stress-related failures occur due to repetitive use leading to micro-cracks and spring fanning
Solution Approach 1:
The patent applies local quality by creating a non-uniform annular retaining surface with varying radius (R1 at outer edge, R2 at inner edge, where R1 > R2). This varying radius design distributes contact stress non-uniformly across the retaining surface, concentrating support where needed while reducing stress concentration at critical points. The result is improved local stress resistance at the retaining surface without compromising overall assembly durability.
2Strength
If the retainer contacts the first arm, then structural support is provided, but stress points increase leading to micro-fractures and cracking
Solution Approach 1:
The patent applies the taking out principle by explicitly excluding contact between the retainer and the first arm. The retainer is designed to contact only the coil spring, not the first arm extending from it. This extraction of the first arm from the contact interface eliminates stress concentration and potential micro-fracture initiation points on the first arm, while maintaining adequate structural support through proper retainer-coil engagement.
3Ease of operation
If the spring is tensioned between extension and ledge, then valve actuation is enabled, but repetitive stress causes fanning and contamination
Solution Approach 1:
The patent applies segmentation by dividing the retainer into distinct functional zones: an inner tubular portion for mounting body engagement, and an annular retaining surface for coil contact. The annular retaining surface is further segmented with a non-uniform radius profile (R1 outer, R2 inner). This segmentation allows the retainer to independently manage coil retention while providing distributed support that prevents spring fanning, thereby eliminating contamination without compromising valve actuation functionality.
Data Source
Figure 1A~1C
Figure 2~3
Figure 4
AI summary
A retainer comprises an inner tubular portion fitted to a mounting body. The inner tubular portion comprises an inner circular edge having a radius R3. An annular retaining surface is connected to the tubular portion. The annular retaining surface comprises an area bounded by an outer edge and the inner circular edge. The outer edge being bounded by an arc AD comprising a first radius R1, a sector CB comprising a second radius R2, where R1>R2, a first chord DC connecting the arc AD to the sector CB, and a second chord BA connecting the arc AD to the sector CB. A rocker arm assembly comprises a rocker arm body configured to actuate a valve in a valve train. The retaining surface abuts a spring coil to retain the coil against the rocker arm body, but the retaining surface does not abut a first arm of the spring.