Valve Stem Seal Lip Structure for Stable Oil Leakage

Solution Overview

Problem

Existing valve stem seal sealing devices experience variations in oil leakage amount due to increased axial contact force from back pressure, leading to potential seizure or excessive oil introduction into the combustion chamber.

Innovation Solution

A valve stem seal sealing device with a metal ring and a seal body having a seal lip, back pressure lip, and back pressure auxiliary lip that slidably contact the valve stem, with the auxiliary lip distributed evenly to stabilize the oil leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a back pressure lip is provided to stabilize oil leakage amount under back pressure, then oil leakage stability is improved, but axial contact force increases causing excessive oil scraping at valve closing

Engineering Contradiction:

Improveoil leakage stabilityVSAvoidaxial contact force

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The seal body is divided into multiple functional lips: a seal lip for primary sealing, a back pressure lip for stabilizing leakage under pressure, and multiple back pressure auxiliary lips distributed circumferentially. This segmentation allows each lip to share the contact force, preventing excessive scraping while maintaining leakage stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different lips are positioned at different locations along the valve stem to perform specialized functions. The back pressure auxiliary lips are specifically positioned between the seal lip and back pressure lip to locally distribute the contact force in regions where back pressure causes excessive scraping.

Inventive Principle:

Principle #3Local quality

2Reliability

If back pressure is applied during port pressure loading, then sealing performance is improved, but oil leakage amount varies due to increased contact force

Engineering Contradiction:

Improvesealing performanceVSAvoidoil leakage amount

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The seal body is divided into multiple functional lips: a seal lip for primary sealing, a back pressure lip for stabilizing leakage under pressure, and multiple back pressure auxiliary lips distributed circumferentially. This segmentation allows each lip to share the contact force, preventing excessive scraping while maintaining leakage stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The back pressure auxiliary lips provide feedback by detecting variations in contact force caused by back pressure, and their distributed configuration automatically compensates for these variations, stabilizing the overall oil leakage amount despite changes in operating conditions.

Inventive Principle:

Principle #23Feedback

3Reliability

If the seal lip contacts the valve stem to seal oil, then oil sealing is improved, but seizure may occur if leakage amount is too small

Engineering Contradiction:

Improveoil sealingVSAvoidseizure risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The seal body is divided into multiple functional lips: a seal lip for primary sealing, a back pressure lip for stabilizing leakage under pressure, and multiple back pressure auxiliary lips distributed circumferentially. This segmentation allows each lip to share the contact force, preventing excessive scraping while maintaining leakage stability.

Inventive Principle:

Principle #1Segmentation

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 device stabilizes the oil leakage amount by reducing variations and preventing excessive oil introduction, thereby preventing seizure and white smoke generation.

Implementation Method 1

a seal body that is fixed integrally with the metal ring and that slidably contacts an outer peripheral surface of the valve stem

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

a seal lip that slidably contacts the outer peripheral surface of the valve stem

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 3

a back pressure auxiliary lip that slidably contacts the outer peripheral surface of the valve stem between the back pressure lip and the seal lip

Methodology Applied

Scientific EffectPressure distribution: Pressure Gradient

Data Source

PatentEP4600530A1Valve-stem-sealing seal apparatus

Publication Date: 2025.08.13 NOK CORP

Figure 1a~1b
Figure 2
Figure 3a~3b

AI summary

Variations in oil leakage amount are suppressed, and an oil leakage amount is stabilized. A valve stem seal sealing device (1) that seals a gap between a valve stem (2), and a valve stem guide (3) that guides movement in an axis (X) direction of the valve stem (2), includes a metal ring (5) in an annular shape to be attached to an end portion of the valve stem guide (3), and a seal body (7) that is fixed integrally with the metal ring (5) and that slidably contacts an outer peripheral surface of the valve stem (2), the seal body (7) has a seal lip (721, 722) that slidably contacts the outer peripheral surface of the valve stem (2), a back pressure lip (725) that slidably contacts the outer peripheral surface of the valve stem (2) on a valve stem guide (3) side from the seal lip (721, 722), and a back pressure auxiliary lip (726) that slidably contacts the outer peripheral surface of the valve stem (2), between the back pressure lip (725) and the seal lip (721, 722).