Flow Tube Assembly With Defined Mounting Gap for Sensor Accuracy

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Solution Overview

Problem

Existing flow sensors face challenges in achieving reproducible mounting of the diaphragm element between housing halves, leading to inconsistent sensor characteristics and reduced measuring accuracy, particularly due to the variability in clamping forces and production tolerances during ultrasound welding.

Innovation Solution

A flow tube design where the housing halves are joined using laser welding outside the mounting gap and abutting surface sections, ensuring a defined width of the mounting gap and reproducible clamping of the diaphragm element, thereby maintaining a consistent opening characteristic and improving sensor accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If ultrasound welding is used to join housing halves, then the housing can be assembled, but the mounting gap width varies due to production tolerances and clamping force variability

Engineering Contradiction:

Improvehousing assemblyVSAvoidmounting gap width

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The mounting gap is defined by abutting surface sections that are prepared in advance on the housing halves. These surfaces are designed to abut against each other during assembly, preliminarily establishing a defined mounting gap width before the actual welding process occurs. This preliminary action ensures that the diaphragm element receives reproducible clamping forces regardless of variations in the welding process.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If ultrasound welding is used to join housing halves, then the housing can be assembled, but vibrations cause material damage to the diaphragm element

Engineering Contradiction:

Improvehousing assemblyVSAvoiddiaphragm element damage

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The housing is divided into two separate housing halves that are joined together. The diaphragm element is positioned within the mounting gap between these halves, which are then connected via abutting surface sections. This segmentation allows the welding process to occur on the housing structure itself rather than directly on the diaphragm element, isolating the sensitive component from harmful vibrations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The abutting surface sections act as intermediaries between the welding process and the diaphragm element. These surfaces provide a stable reference for defining the mounting gap width and transmit forces in a controlled manner, preventing direct transmission of harmful welding vibrations to the diaphragm element while maintaining proper clamping.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If the mounting gap width varies, then housing assembly is flexible, but the sensor characteristic curve becomes inconsistent

Engineering Contradiction:

Improvehousing assembly flexibilityVSAvoidsensor characteristic

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The abutting surface sections enable the housing assembly to self-regulate the mounting gap width. When the housing halves are brought together for assembly, the abutting surfaces automatically define the correct gap width through their geometric relationship, eliminating the need for external adjustment mechanisms or complex tooling. This self-service mechanism ensures consistent sensor characteristics across multiple assemblies.

Inventive Principle:

Principle #25Self-service

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 approach ensures a reproducible characteristic curve for the flow sensor, enhancing measuring accuracy and reliability without the need for special calibration, while avoiding material damage from vibrations associated with ultrasound welding.

Implementation Method 1

The other housing half is made of a material that absorbs the energy of the laser beam... The two housing halves are made of a material that is suitable for laser welding, especially a plastic suitable for laser welding

Methodology Applied

Scientific EffectLaser welding: Laser Beam Welding

Implementation Method 2

The other housing half is made of a material that absorbs the energy of the laser beam, especially made of such a material in the area of the connection in substance area

Methodology Applied

Scientific EffectLaser energy absorption: Absorption (EM radiation)

Data Source

PatentUS20240410728A1Flow tube for a flow sensor and process for manufacturing a flow tube

Publication Date: 2024.12.12 DRAGERWERK AG

AI summary

A flow tube (10) has a housing (12, 14) including at least a first housing half (12) and a second housing half (14). Each housing half (12, 14) has a connection surface (20, 22) intended for combination with the other housing half (12, 14). The connection surfaces (20, 22) enclose a mounting gap (30) for an orifice element (16). Outside of the mounting gap (30) the connection surfaces (20, 22) butt against each other in some sections by respective abutting surface portions (32, 34), and outside of the mounting gap (30) and outside of the abutting surface portions (32, 34) the housing halves (12, 14) are integrally combined with each other. A method is provided for producing the flow tube, namely for integrally joining the housing halves (12, 14).