Radial Shaft Seal with Sinusoidal Sealing Edge

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Solution Overview

Problem

Existing radial shaft seals are unable to consistently provide a tight seal against various lubricants, particularly oils, and often require additional sealing elements due to limitations in operating conditions and shaft speeds.

Innovation Solution

A radial shaft seal with a sinusoidally curved sealing edge, where the angles formed with the shaft's longitudinal axis ensure a tight seal, and additional geometric parameters enhance seal tightness, eliminating the need for a separate spring and incorporating an auxiliary sealing edge for pressure stability, while maintaining a low sealing lip temperature and effective dirt particle management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional radial shaft seal with a straight sealing edge is used, then the structure is simple, but it cannot guarantee a tight seal against lubricants, particularly oils

Engineering Contradiction:

Improveseal tightnessVSAvoidsealing structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The sealing edge is designed with a sinusoidal curve instead of a straight line, creating a curved geometry that improves sealing performance. The sinusoidal shape allows the sealing lip to conform better to the shaft surface and maintain contact under varying operating conditions, achieving reliable seal tightness against lubricants while remaining a single-component design.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Reliability

If additional sealing elements are added to improve seal tightness, then sealing reliability improves, but the device complexity and cost increase

Engineering Contradiction:

Improveseal tightnessVSAvoidnumber of sealing components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The radial shaft seal is designed as a single multi-functional component that performs both sealing and self-lubrication functions. The sinusoidal sealing edge geometry enables the seal to maintain tightness against various lubricants while the curved surface promotes lubricant retention and heat dissipation, eliminating the need for additional sealing elements or springs.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Temperature

If a straight sealing edge is used, then manufacturing is simple, but heat dissipation is insufficient leading to high sealing lip temperature

Engineering Contradiction:

Improvesealing lip temperatureVSAvoidsealing edge geometry

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The sinusoidal curve of the sealing edge increases the surface area and creates a more favorable heat transfer geometry. The curved surfaces promote better contact with the shaft and enhance heat dissipation from the sealing lip to the shaft, reducing operating temperature without significantly complicating the manufacturing process.

Inventive Principle:

Principle #14Spheroidality (Curvature)

4Reliability

If the sealing lip is pressed against the circumferential face using a coiled spring, then seal tightness improves, but the device complexity and cost increase

Engineering Contradiction:

Improveseal tightnessVSAvoidspring mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The coiled spring component is completely removed from the sealing system. Instead of using an external spring mechanism to press the sealing lip against the shaft, the invention relies on the elastic properties of the sealing lip material itself and the geometric design of the sinusoidal edge to maintain contact pressure, simplifying the overall structure.

Inventive Principle:

Principle #2Taking out (Extraction)

5Object-affected harmful factors

If conventional sealing lips are used, then the design is simple, but thermal and mechanical damage to the lubricant occurs

Engineering Contradiction:

Improvelubricant damageVSAvoidsealing lip design

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The sealing edge geometry is changed from a straight line to a sinusoidal curve with specific amplitude and wavelength parameters. This parameter change optimizes the contact pressure distribution and heat transfer characteristics, reducing thermal and mechanical degradation of the lubricant while maintaining sealing effectiveness.

Inventive Principle:

Principle #35Parameter changes

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 solution achieves a reliable seal against all types of lubricants, independent of operating conditions and shaft speeds, with reduced thermal and mechanical damage to the lubricant, and eliminates the need for additional sealing elements, ensuring high dynamic seal tightness and efficient heat dissipation.

Implementation Method 1

heat is removed substantially more quickly into the shaft

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Data Source

PatentUS9482344B2Arrangement with a radial shaft seal having a sinusoidally curved sealing edge

Publication Date: 2016.11.01 CARL FREUDENBERG KG

AI summary

An arrangement includes a radial shaft seal (2) that surrounds a shaft (1), wherein an elastomer body (4) forms a sealing lip (5) for bearing against the shaft (1), wherein the sealing lip (5) has a sinusoidally curved sealing edge (6) on its side which faces the shaft (1), which sealing edge runs around along the inner circumference of the sealing lip (5), and wherein the sealing edge (6) bears against the circumferential face (7) of the shaft (1). The radial shaft seal as a single component is able to produce high dynamic seal tightness in a plurality of different applications.