Hand Dryer Nozzle Layout for Quiet Interdigital Drying

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Solution Overview

Problem

Conventional hand dryers suffer from noise due to airflow collisions and inefficiency in removing water between fingers due to parallel airflow directions that do not effectively target interdigital spaces.

Innovation Solution

The hand dryer design features air nozzle sections that project from the first wall section at a forward-tilt angle, allowing high-speed airflows to jet obliquely downward, ensuring consistent airflow between fingers and preventing collisions, thus minimizing noise and enhancing water removal efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If two air nozzle sections are provided on near side and far side to face each other, then water can be blown away from both palm and back of hand simultaneously, but high-speed airflows collide with each other causing noise

Engineering Contradiction:
Improvedrying efficiencyVSAvoidnoise
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent applies asymmetry by providing air nozzles only on the first wall section (one side) rather than symmetrically on both opposing wall sections. This asymmetric configuration allows high-speed airflows to jet onto the hand without colliding with opposing flows, thereby eliminating noise while maintaining effective water removal from both palm and back of hand.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent extracts the problematic opposing air nozzle section from the system. By removing the air nozzle from the second wall section that would face the first wall section, the design eliminates the source of airflow collision and noise while preserving the drying function through the remaining single air nozzle configuration.

Inventive Principle:
Principle #2Taking out (Extraction)

2Area of stationary object

If air nozzles jet high-speed airflows parallel with palms and backs of hands, then coverage area is increased, but water between fingers is difficult to remove

Engineering Contradiction:
Improveairflow coverage areaVSAvoidwater removal efficiency
Core Design Contradiction:
Area of stationary objectVSProductivity

Solution Approach 1:

The patent applies local quality by configuring the air nozzle to jet high-speed airflow in a direction that specifically targets interdigital spaces (spaces between fingers). Instead of uniform parallel airflow across the hand, the airflow is directed to penetrate between fingers where water accumulates, providing localized effective cleaning in the most problematic areas.

Inventive Principle:
Principle #3Local quality

3Object-generated harmful factors

If air nozzles are arranged to jet airflow obliquely downward, then noise is reduced by preventing collision, but may reduce effectiveness on upper hand areas

Engineering Contradiction:
ImprovenoiseVSAvoiddrying uniformity
Core Design Contradiction:
Object-generated harmful factorsVSProductivity

Solution Approach 1:

The patent applies dimensionality change by extending the air nozzle in the vertical direction rather than only horizontally. This vertical extension allows the single air nozzle to cover both upper and lower areas of the hand while jetting obliquely downward, maintaining noise reduction benefits while achieving uniform drying across the entire hand surface.

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

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 results in a quieter operation and effective removal of water from between fingers, ensuring thorough hand drying without reducing airflow speed or kinetic energy.

Implementation Method 1

a high-pressure airflow generating unit (11) that generates high-speed airflow

Methodology Applied
Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

jetting high-speed airflow onto wet hands... water is blown away from the hand

Methodology Applied
Scientific EffectAerodynamic force:

Data Source

PatentEP2399496B1Hand dryer
Publication Date: 2019.03.27 MITSUBISHI ELECTRIC CORP
  • EP2399496B1 patent drawingFigure 1
  • EP2399496B1 patent drawingFigure 2
  • EP2399496B1 patent drawingFigure 3

AI summary

A hand dryer comprising a hand drying chamber that includes a hand insertion opening from which left and right hands can be inserted in parallel; a first wall section that faces backs of the hands inserted from the hand insertion opening; a second wall section that faces palms of the hands and the first wall section; and a pair of air nozzle sections that is set on any one of a side of the first wall section and a side of the second wall section to extend roughly along an overall length of the inserted hands in a direction almost parallel to a direction of a finger of each of the inserted hands, and that jets a high-speed airflow toward any one of the backs and the palms of the hands. The pair of air nozzle sections is arranged such that a space on a side of the hand insertion opening is wide and a space on a far side is narrow to be almost parallel with directions of fingers of the inserted hands.