Optical Gear Speed Detection for Hot Melt Adhesive Metering

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Solution Overview

Problem

Current metering devices for fluids, such as hot melt adhesive, require multiple components to monitor rotational speed, leading to increased complexity, cost, and space requirements, as well as vulnerability to high temperatures and pressure variations.

Innovation Solution

A contactless optical detection system for measuring the rotational speed of the gear, eliminating the need for additional rotating components and rotary encoders, using probes to emit and detect light signals from the gear, which are guided by fiber optics and processed to regulate fluid flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a rotary encoder and additional rotating components are used to monitor rotational speed, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improverotational speed measurement precisionVSAvoidnumber of components
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical rotary encoder system with an optical measurement system. A light source emits light onto the gear, and a light receiver detects the reflected light. The gear's rotation modulates the reflected light signal, allowing rotational speed measurement without mechanical contact. This substitution eliminates the need for rotary encoders and additional rotating components while maintaining measurement precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces light as an intermediary medium to transfer information about gear rotation. Instead of direct mechanical coupling between the gear and measurement device, light serves as the mediator that carries rotational information from the gear surface to the detector, enabling non-contact measurement and reducing system complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If rotary encoders and additional components are installed, then rotational speed monitoring is improved, but manufacturing cost increases

Engineering Contradiction:
Improverotational speed monitoring capabilityVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

By replacing expensive rotary encoders with a simple optical system consisting of a light source and light receiver, the patent significantly reduces component costs. The optical components are more readily available and can be integrated into the housing without requiring precision mechanical assemblies, thereby lowering manufacturing costs while maintaining monitoring capability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If additional rotating components are used for measurement, then measurement accuracy is improved, but space requirements increase

Engineering Contradiction:
Improverotational speed detection accuracyVSAvoiddevice compactness
Core Design Contradiction:
Measurement precisionVSVolume of moving object

Solution Approach 1:

The optical measurement system requires no additional rotating components or mechanical assemblies, allowing the measurement function to be integrated directly into the existing housing space. The light source and receiver can be positioned on stationary surfaces, eliminating the need for additional mechanical volume and maintaining device compactness.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If traditional measurement systems are used, then reliability is maintained, but temperature stability deteriorates

Engineering Contradiction:
Improvefunction reliabilityVSAvoidtemperature stability
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

By replacing mechanical contact-based measurement systems with an optical system, the patent eliminates friction, wear, and thermal expansion issues associated with mechanical components. The optical components are less sensitive to temperature variations, improving temperature stability and overall reliability in high-temperature environments.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

5Reliability

If mechanical sealing components are added, then measurement reliability is improved, but device complexity increases

Engineering Contradiction:
Improvesealing reliabilityVSAvoidnumber of sealing components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The contactless optical measurement system eliminates the need for mechanical seals and bearing assemblies that would be required to protect rotating measurement components. Since the light source and receiver remain stationary and do not rotate with the gear, no dynamic sealing is needed, reducing device complexity while maintaining reliability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 solution reduces component count, lowers costs, enhances temperature and pressure stability, and increases compactness, allowing for precise fluid flow control with high resolution, even with small gear modules, while minimizing heat impact on electronics.

Implementation Method 1

The probe is adapted to emit light onto a portion of the gear, said probe being adapted to receive light reflected from the portion of the gear

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

which are guided by fiber optics and processed to regulate fluid flow

Methodology Applied
Scientific EffectOptical fiber transmission: Optical Fibre

Data Source

PatentEP2897738B1Metering device for a fluid
Publication Date: 2019.08.28 NORDSON CORP
  • EP2897738B1 patent drawingFigure 1
  • EP2897738B1 patent drawingFigure 2
  • EP2897738B1 patent drawingFigure 3

AI summary

The invention relates to a metering device (5) for a fluid, in particular hot melt adhesive, adapted for use with a dispensing apparatus (1) for said fluid or a remote metering apparatus (16) for transporting said fluid, comprising a housing (28), said housing comprising a fluid inlet and one or more fluid outlets, a gear (34) which is rotatably supported in said housing (28) and inserted in a gear chamber (31) in the housing (28) such that a cavity for fluid transport is formed in between two adjacent teeth and said housing (28), one or more chamber inlets in fluid communication with said fluid inlet and said gear chamber (31) such that fluid may flow into said gear chamber (31).