Developer Unit Seal Fluid Channels for Wear Reduction

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Solution Overview

Problem

Developer units in liquid electrophotography systems face premature failure and leakage due to inadequate lubrication and cooling at the rotating/stationary interface, leading to wear and reduced lifespan, especially at higher process speeds.

Innovation Solution

A seal system that integrates channels for print fluid to flow between the dynamic seal interfaces, acting as both a coolant and lubricant, preventing groove formation and leakage by directing print fluid from a higher-pressure inlet region to the roller/end cap interface, and allowing its reuse in the developer unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the developer unit is sealed to prevent fluid leakage, then reliability is improved, but the rotating/stationary interface becomes inadequate for lubrication and cooling, leading to wear and reduced lifespan

Engineering Contradiction:
Improvesealing effectivenessVSAvoidroller lifespan
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The seal is divided into multiple components: a first seal member with first channels, a second seal member with second channels, and a bridge member connecting them. This segmentation allows independent optimization of each component's function while maintaining overall sealing effectiveness and lubrication performance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The bridge member acts as an intermediary element connecting the first and second seal members, providing structural support and enabling the seal to accommodate the rotating roller while maintaining the lubrication channels open to the roller surface.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Duration of action of moving object

If the seal structure is made more complex to provide lubrication channels, then the lifespan is improved, but device complexity increases

Engineering Contradiction:
Improveseal lifespanVSAvoidseal structure complexity
Core Design Contradiction:
Duration of action of moving objectVSDevice complexity

Solution Approach 1:

The lubrication channels are merged into the seal structure itself rather than being separate components. The first and second channels are integrated within the seal members, reducing the number of separate parts while providing the necessary lubrication function.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The seal structure serves multiple functions simultaneously: it seals the developer unit to prevent fluid leakage, provides lubrication channels to supply print fluid to the roller interface, and maintains structural integrity through the bridge member connection.

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

3Strength

If print fluid is directed to the roller interface for lubrication, then wear is reduced, but fluid pressure distribution becomes critical

Engineering Contradiction:
Improveinterface lubricationVSAvoidfluid pressure distribution
Core Design Contradiction:
StrengthVSStress or pressure

Solution Approach 1:

The seal structure creates localized high-pressure zones at the interface between the roller and seal members, ensuring concentrated lubrication where it is most needed. The bridge member and channel configuration focus the print fluid pressure directly at the wear-prone interface areas.

Inventive Principle:
Principle #3Local quality

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 effectively prolongs the lifespan of developer units by reducing leaks, preventing wear, and maintaining performance by lubricating and cooling the sealing surfaces, thus extending the expected life of the units.

Implementation Method 1

directing print fluid from a higher-pressure inlet region to the roller/end cap interface

Methodology Applied
Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

acting as both a coolant and lubricant, preventing groove formation and leakage

Methodology Applied
Scientific EffectLubrication: Lubrication

Implementation Method 3

acting as both a coolant and lubricant

Methodology Applied
Scientific EffectConvection cooling: Convection

Data Source

PatentEP3997523B1Developer unit seals with fluid channels
Publication Date: 2024.09.04 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP3997523B1 patent drawingFigure 1
  • EP3997523B1 patent drawingFigure 2
  • EP3997523B1 patent drawingFigure 3

AI summary

In one example in accordance with the present disclosure, a developer unit seal is described. The seal includes a first sealing member to contact an end cap of the developer unit. The first sealing member has ports to align with rollers that are to protrude into the end cap. The seal includes a second sealing member to contact the first sealing member. The second sealing member has ports to align with the rollers. Channels are disposed between the first sealing member and the second sealing member to direct print fluid to each of the ports.