Airless Spray Tip Seal Relocation to Eliminate Spit

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Solution Overview

Problem

Current reversible airless spray tip assemblies store energy in o-rings ahead of the mechanical fluid seal, leading to spit onto the painter's work when the gun is shut off due to de-energization of these seals.

Innovation Solution

The needle seat is mated to the tip assembly, moving the seal out of the 'dead zone' and eliminating o-rings ahead of the mechanical fluid shutoff to minimize energy storage and spit volume.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If o-rings are placed ahead of the mechanical fluid seal in the dead zone, then sealing function is improved, but energy storage increases causing spit volume to worsen

Engineering Contradiction:
Improvesealing functionVSAvoidspit volume
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent removes o-rings from the dead zone ahead of the mechanical fluid seal, extracting the harmful energy-storing element while maintaining sealing function through the mechanical seal design alone

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The seal is repositioned from the dead zone to a location where it can function effectively without storing energy, changing the spatial dimension of seal placement to eliminate the harmful effect

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If the seal is positioned in the dead zone, then sealing function is maintained, but energy storage occurs leading to spit when gun is shut off

Engineering Contradiction:
Improvesealing functionVSAvoidenergy storage
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The seal is extracted from the dead zone position and relocated to eliminate energy storage while preserving sealing capability through the mechanical fluid seal design

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The mechanical fluid seal is designed to maintain sealing function before the gun is shut off, preventing the need for additional o-rings in the dead zone that would store energy

Inventive Principle:
Principle #10Preliminary action

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

This configuration significantly reduces spit volume by eliminating energy storage in o-rings, preventing spit from occurring when the gun is shut off.

Implementation Method 1

o-ring seal 24 is located in the dead zone 16 and can store energy and release same. Seal 24 is compressible when exposed to typical airless spraying pressures, typically 2000-3000 psi

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2528694B1Airless spray tip
Publication Date: 2019.06.12 GRACO MINNESTOA INC
  • EP2528694B1 patent drawingFigure 1
  • EP2528694B1 patent drawingFigure 2

AI summary

In airless spray tip assembly 100 shown in Figure 2, cylinder 112 contains tip 114 and is at one end of dead zone 116. Shutoff 118 is comprised of ball 120 and seat 122. The needle seat 122 has been mated to each tip assembly 100 (See Figure 2). By mating the tip 114 and the seat assembly (shutoff) 118 into one, the seal 124 can be moved out of the 'dead zone' 116 thus reducing spit volume and energy storage.