Nonlinear Spring Check Valve for Stable HVLP Airflow

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Solution Overview

Problem

High-volume low-pressure spray systems experience unstable check valve behavior due to rapid pressure changes, leading to chattering, noise, wear, and oscillating air supply, which existing technologies fail to adequately address.

Innovation Solution

A check valve design with a nonlinear spring force applied to the valve member, allowing it to tip open and close variably in response to pressure differentials, preventing full disengagement and reducing oscillation, thereby stabilizing the air supply.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a conventional check valve is used in an HVLP spray system, then the valve can respond to pressure differentials, but the valve exhibits unstable behavior with rapid opening and closing causing chattering

Engineering Contradiction:
Improveresponse speed to pressure differentialVSAvoidvalve stability
Core Design Contradiction:
SpeedVSStability of the object's composition

Solution Approach 1:

The patent applies the Dynamics principle by making the valve member's opening degree dynamic rather than binary. The valve member is designed to rock between a closed position and a fully open position, allowing it to assume intermediate positions. This dynamic behavior enables the valve to modulate airflow continuously in response to pressure differentials, preventing the rapid full-open/full-closed transitions that cause chattering, while maintaining responsive control.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent applies the Parameter changes principle by altering the physical state and movement characteristics of the valve member. Instead of maintaining a fixed binary state (open/closed), the valve member's position parameter is changed to allow continuous variation between closed and fully open states. This parameter transformation from discrete to continuous enables stable operation under varying pressure conditions by allowing gradual adjustment of the opening degree.

Inventive Principle:
Principle #35Parameter changes

2Speed

If the check valve opens and closes rapidly in response to pressure equalization, then the valve responds quickly to pressure changes, but this causes excessive noise and wear

Engineering Contradiction:
Improvepressure response speedVSAvoidnoise and wear
Core Design Contradiction:
SpeedVSObject-affected harmful factors

Solution Approach 1:

The Dynamics principle resolves this contradiction by enabling the valve member to transition gradually between closed and fully open positions rather than snapping rapidly between states. The rocking motion allows the valve to absorb pressure changes dynamically, maintaining quick response to pressure differentials while avoiding the mechanical shock and noise associated with abrupt full-open/full-closed transitions, thereby reducing wear.

Inventive Principle:
Principle #15Dynamics

3Productivity

If the check valve allows full opening in response to pressure differential, then maximum airflow is achieved, but this causes oscillating air supply

Engineering Contradiction:
Improveairflow volumeVSAvoidair supply stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The Dynamics principle resolves this contradiction by allowing the valve member to rock to a fully open position for maximum airflow when needed, but also to assume intermediate positions during transient conditions. This dynamic capability enables the system to achieve high productivity when pressure differentials are sustained while preventing oscillations during pressure equalization, as the valve can modulate its opening degree to match actual flow demands.

Inventive Principle:
Principle #15Dynamics

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 prevents chattering and oscillation, reducing noise, wear, and vibration, while providing a smooth and stable air supply by allowing the valve to open a variable degree responsive to pressure differentials.

Implementation Method 1

a spring configured to exert a nonlinear force on a downstream face of the valve member so that the valve member tips to an open position

Methodology Applied
Scientific EffectSpring force: Spring

Data Source

PatentEP3351309B1Check valve with nonlinear force load for HVLP spraying
Publication Date: 2021.04.14 GRACO MINNESTOA INC
  • EP3351309B1 patent drawingFigure 1A
  • EP3351309B1 patent drawingFigure 1B
  • EP3351309B1 patent drawingFigure 1C

AI summary

A high-volume low-pressure spray system includes a hose (16) disposed between a compressor and a spray gun (14). The hose acts as an accumulator when the spray gun is deactivated. A check valve (36) is disposed in a fitting (18) connecting the hose to the compressor. The check valve includes a spring (42) that applies a nonlinear force to a downstream end of a valve member (44), such that the valve member tips open in response to the pressure differential, providing a variable flowpath opening through the check valve.