W-Shaped Spring Seal for Pivot Joint Lubrication Elimination

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Solution Overview

Problem

Lubricants in mechanical joints of machines break down or get expelled over time, leading to maintenance downtime and productivity losses due to the need for frequent replenishment, especially in moving parts like the steering system of off-highway machines.

Innovation Solution

A dry spring seal assembly with W-shaped cross-sectional spring seals is used between the sleeve joint and the lugs of the frame joint, eliminating the need for lubricants by maintaining sealing contact through resilient cantilevered legs and a spring leg, allowing for effective sealing and relative motion without contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lubricants are applied to mechanical joints to prevent wear and contamination, then the joints are protected from friction and dirt, but the lubricants break down or get expelled over time requiring frequent maintenance replenishment

Engineering Contradiction:
Improvejoint protectionVSAvoidmaintenance downtime
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent removes the lubricant from the sealing system entirely, extracting the harmful substance that requires maintenance replenishment while retaining the protective sealing function through alternative means (the seal assembly with resilient lips and spring mechanism)

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The spring mechanism automatically maintains sealing contact between the resilient lips and the joint surfaces, providing self-adjusting protection without external intervention or lubricant replenishment, enabling the system to service itself

Inventive Principle:
Principle #25Self-service

2Loss of time

If seals are used to protect joints without lubricants, then maintenance downtime is reduced, but the seal structure becomes more complex with multiple components

Engineering Contradiction:
Improvemaintenance downtimeVSAvoidseal structure
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The seal assembly performs multiple functions simultaneously: the resilient lips provide sealing contact, the spring maintains the sealing force, and the entire assembly protects against both contamination and wear in a single integrated component system

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 dry spring seal assembly reduces maintenance downtime and productivity losses by providing a reliable seal that prevents dirt and contaminants from entering the joint, facilitating the pivoting motion of the lever arm while eliminating the need for lubricant replenishment.

Implementation Method 1

a spring leg joined to and connecting the first and second cantilevered legs and adapted to maintain sealing contact with the frame join and the sleeve joint

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3277991B1Seal for a joint assembly
Publication Date: 2020.01.29 CATERPILLAR INC
  • EP3277991B1 patent drawingFigure 1
  • EP3277991B1 patent drawingFigure 2
  • EP3277991B1 patent drawingFigure 3

AI summary

A spring seal (180) for a joint assembly (150) pivotally joining a lever arm (128) to a machine frame (106) includes an annular body (200) having a W-shaped cross section. The W-shaped cross section includes a first cantilevered arm (220), a parallel and spaced apart second cantilevered arm (222), and a spring leg (230) joining the first and second cantilevered arms (220, 222). The spring seal (230) is disposed between a bearing surface (172) on the lever arm (128) and a lug (160) on the frame (106). The W-shaped cross section of the spring seal (180) can collapse and relax to accommodate movement between the lever arm (128) and the frame lug (160). A second spring seal (182) can be disposed between a second bearing surface (176) on the lever arm (128) and a second frame lug (162) opposite the first lug (160).