Cross Shaft Seal Ring Structure for Water Ingress Prevention

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Solution Overview

Problem

Existing seal rings in cross shaft couplings are prone to water ingress and corrosion under harsh conditions, leading to concerns about sealing performance.

Innovation Solution

A seal ring design featuring a center section with four shaft sections, step faces, and a seal lip that deforms inwardly to contact the step face, along with an annular core member for enhanced rigidity and positioning, effectively preventing water ingress and improving sealing performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional seal ring design is used, then the structure is simple, but water ingress occurs and sealing performance deteriorates under harsh conditions

Engineering Contradiction:

Improvesealing performanceVSAvoidseal ring structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The seal ring is divided into multiple functional segments: a seal lip for contact with the step face, an indentation for deformation and sealing, a seat for positioning, and a core member for structural support. This segmentation allows each part to perform its specific function optimally, preventing water ingress while maintaining manageable complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The seal ring combines a flexible seal lip material with a rigid core member. The core member provides structural integrity and positioning, while the seal lip material provides flexibility for deformation and sealing contact. This composite structure enhances sealing performance without excessive complexity

Inventive Principle:

Principle #40Composite materials

2Reliability

If the seal lip deforms toward the radial direction inside to contact the step face, then sealing performance improves, but the step face size must be larger

Engineering Contradiction:

Improvesealing performanceVSAvoidstep face area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The seal lip is designed with localized deformation characteristics, concentrating the sealing action at a specific point where the seal lip contacts the step face. This allows the step face to be smaller because the sealing force is concentrated rather than distributed, improving sealing performance without requiring large contact area

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If the seal ring includes a seat and indentation structure, then positioning accuracy improves, but manufacturing complexity increases

Engineering Contradiction:

Improvepositioning accuracyVSAvoidseal ring manufacturing

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The seat and indentation are designed as pre-formed features in the seal ring structure, establishing correct positioning and deformation characteristics before the seal ring is installed. This preliminary configuration ensures accurate positioning during operation without requiring complex assembly procedures or additional manufacturing steps

Inventive Principle:

Principle #10Preliminary action

4Stability of the object's composition

If the core member is made with high rigidity, then seal lip tension stability improves, but the overall seal ring size increases

Engineering Contradiction:

Improveseal lip tension stabilityVSAvoidseal ring volume

Core Design Contradiction:

Stability of the object's compositionVSVolume of stationary object

Solution Approach 1:

The core member is nested within the seal ring structure, with the seal lip material surrounding it. This nested configuration allows the high-rigidity core member to provide structural stability and seal lip tension stability while being contained within the existing seal ring volume, preventing excessive size increase

Inventive Principle:

Principle #7Nested doll (Nesting)

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 provides excellent sealing performance, prevents rotation with the bearing, and allows for a more compact cross shaft coupling, while maintaining high sealing efficacy even under harsh conditions.

Implementation Method 1

the seal lip enters an indentation when the seal lip is deformed by the contact

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS11598420B2Seal ring, cross shaft coupling, intermediate shaft assembly, steering device

Publication Date: 2023.03.07 NSK LTD

AI summary

A seal ring (26) configured to be employed with a cross shaft (16) including a center section (17) and four shaft sections (18a, 18b, 18c, 18d) extending in four directions from the center section and formed with step faces (17a) where the center section widens out from base ends of the shaft sections outward in radial directions of the shaft sections, and with bearings (21) for mounting to leading end portions of the shaft sections. The seal ring is fitted over the shaft section and interposed between the bearing and the step face. The seal ring includes a seal lip (34) configured to contact the step face around the entire circumference, and an indentation (36) the seal lip enters by deforming when mounted to the cross shaft.