Seal Ring Radial Gap Design for Oil Passage Clogging

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Solution Overview

Problem

Existing seal rings for hydraulic units face issues with foreign matter clogging the oil passage due to complex abutment shapes and narrow grooves, leading to difficulties in discharging foreign matter from the oil pressure side to the non-oil pressure side.

Innovation Solution

A seal ring design featuring juxtaposed protrusions and recesses with a radial gap and circumferential gap that form a simple passage for oil communication between the oil pressure and non-oil pressure sides, made of polyetheretherketone resin with carbon fibers for enhanced wear resistance, where the radial gap is less than 30% of the protrusion thickness to prevent deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If grooves are formed along many ridgelines of the protrusions of the abutments, then the oil passage is formed to allow oil flow, but the abutments become complicated in shape and foreign matter tends to clog the oil passage at bent portions

Engineering Contradiction:

Improveoil passage functionalityVSAvoidabutment shape complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The oil passage is segmented into multiple straight sections rather than forming a single complex bent passage. The circumferential gap and radial gap are positioned at different locations to create separate flow paths, avoiding concentrated bends and foreign matter accumulation points.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of forming the oil passage through complex grooves along ridgelines, the invention inverts the approach by creating the passage through gaps between simplified abutment surfaces. The circumferential gap is formed between radially outer surfaces, and the radial gap is formed between radially inner surfaces, eliminating the need for complex groove formations.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If a crank-shaped oil passage with a circumferentially extending third oil groove is formed between abutments, then oil can flow between sides of the annular gap, but the protrusions deflect toward the inner side surface under oil pressure, narrowing or closing the third oil groove

Engineering Contradiction:

Improveoil passage stabilityVSAvoidoil passage structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The problematic circumferentially extending third oil groove is extracted and removed from the design. The oil passage functionality is achieved through the circumferential gap and radial gap combination, which eliminates the deflection issue while maintaining oil flow capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The oil passage is repositioned from a three-dimensional complex groove structure to a two-dimensional gap system. The circumferential gap and radial gap are formed at different radial positions, creating a stable passage that does not deflect under pressure while maintaining simplicity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If the seal ring is made of resin material, then it provides good sealing properties, but the abutments may deflect under oil pressure, affecting the oil passage geometry

Engineering Contradiction:

Improvesealing performanceVSAvoidresistance to oil pressure deflection

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The seal ring uses a composite material consisting of resin base material reinforced with carbon fibers. This composite structure maintains the good sealing properties of resin while significantly improving the resistance to oil pressure deflection through the high-strength carbon fiber reinforcement.

Inventive Principle:

Principle #40Composite materials

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 allows for smooth discharge of foreign matter from the oil pressure side to the non-oil pressure side without clogging, maintaining the seal ring's structural integrity and extending its lifespan with improved wear resistance.

Implementation Method 1

made of polyetheretherketone resin with carbon fibers for enhanced wear resistance

Methodology Applied

Scientific EffectWear resistance: Wear

Implementation Method 2

the radial gap and the circumferential gap between the abutments forming a passage through which the oil pressure side communicates with the non-oil pressure side

Methodology Applied

Scientific EffectPressure-driven flow: Pressure Gradient

Data Source

PatentUS8454024B2Seal ring

Publication Date: 2013.06.04 NTN CORP

AI summary

In a seal ring, first and second abutments that are opposed to each other at a cut-apart portion have first and second protrusions 3a and 3b and first and second recesses 4a and 4b that are juxtaposed to each other in the axial direction, and a radial gap 5a is defined between the first protrusion 3a of the first abutment 1a that is pressed against a side wall 13a of an annular groove 13 formed in a shaft member 12 near a non-oil pressure side 14b and the second recess 4b of the second abutment 1b, with the radial gap 5a and a circumferential gap 2 between the first and second abutments 1a and 1b forming a passage through which an oil pressure side 14a of the annular gap 14 communicates with the non-oil pressure side 14b. The abutments 1a and 1b are not complicated in shape, and still, foreign matter contained in oil in the oil pressure side 14a can be smoothly discharged into the non-oil pressure side 14b.