Hermetic Housing for Data Loggers Resisting Autoclave Stress

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Solution Overview

Problem

Data loggers used in sterile environments face corrosion and damage during autoclaving due to saturated steam penetration, and existing protective measures like casting compounds fail to prevent thermal stress cracks.

Innovation Solution

A data logger with a housing comprising two parts joined by a gas-tight metal/metal connection, which hermetically seals the electronics and prevents thermal expansion-induced stress, using welding or brazing for a secure seal, and allowing for interchangeable sensors and power sources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electronics are covered with casting compound for protection, then protection against environmental factors is improved, but thermal expansion stress causes cracks and damage

Engineering Contradiction:

Improveprotection against environmental factorsVSAvoidresistance to thermal expansion stress

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The housing is divided into multiple segments (first housing part, second housing part, cover) that are joined together. This segmentation allows each part to expand independently under thermal stress, preventing the stress concentration that causes cracks in monolithic casting compound encasements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A sealing element is introduced as an intermediary component between the housing parts and electronics. This sealing element absorbs and accommodates thermal expansion differences, protecting the electronics from stress while maintaining the hermetic seal against environmental factors.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If housing parts are joined by non-metallic connections, then manufacturing ease is improved, but gas-tight sealing against saturated steam is insufficient

Engineering Contradiction:

Improvehousing assemblyVSAvoidsaturated steam penetration

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The housing employs composite construction combining metallic components (first housing part, second housing part, cover) with non-metallic sealing elements. The metal parts provide structural integrity and gas-tight connections resistant to steam penetration, while the sealing elements ensure hermetic closure at joints.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Different regions of the housing have different material properties optimized for their specific functions. The metallic housing parts provide structural strength and steam resistance, while localized sealing elements provide hermetic closure. The cover is selectively designed with a gas-tight metal/metal connection at specific areas requiring enhanced sealing.

Inventive Principle:

Principle #3Local quality

3Device complexity

If electronics are encased in single-piece housing, then protection is simplified, but thermal stress from temperature differences causes damage

Engineering Contradiction:

Improvehousing structureVSAvoidresistance to thermal expansion

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The housing structure transitions from a rigid monolithic design to a dynamic segmented structure that can adapt to thermal expansion. The joints between housing parts allow for controlled movement and expansion, accommodating temperature changes from -50 to 140 degrees Celsius without causing damage.

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 provides reliable protection against autoclaving conditions, enabling multiple cycles and long-term use while preventing damage to electronics, ensuring cost-effectiveness and secure sealing.

Implementation Method 1

the two housing parts have at least one metallic connection site and are joined together at the connection site by a gas-tight metal/metal connection

Methodology Applied

Scientific EffectHermetic sealing:

Implementation Method 2

the gas-tight metal/metal connection is produced by welding or brazing

Methodology Applied

Scientific EffectWelding: Welding

Implementation Method 3

the gas-tight metal/metal connection is produced by welding or brazing

Methodology Applied

Scientific EffectBrazing: Brazing

Implementation Method 4

A seamless tube is much more stable, since no axial weld seam runs along the tube, being subjected to thermal stresses

Methodology Applied

Scientific EffectThermal stress resistance: Thermal Expansion

Data Source

PatentUS11576274B2Device for detecting and registering of measurement data

Publication Date: 2023.02.07 TESTO SE & CO KGAA

AI summary

A device (1) for the detecting and registering of measurement data, having a first housing (2) in which electronics (7) are arranged, and having at least one sensor (14), which is electrically connected to the electronics (7). The first housing (2) includes at least two housing parts (3, 4), having at least one metallic connection site and being joined together at the connection site by a gas-tight metal/metal connection. The at least one sensor (13) is arranged in a second housing (11), which encloses the first housing (2) substantially entirely, and which includes at least two housing parts (12, 15), which are detachably joined together or can be so joined.