Sensor Coil PCB Clamping for High-Temperature Flow Measurement

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Solution Overview

Problem

High-temperature applications cause mechanical stress and destruction of circuit boards in measuring sensors due to mismatched thermal expansion coefficients between the circuit board and its holder, leading to potential destruction.

Innovation Solution

The solution involves using a holding device with a holding element made of materials like zirconium, titanium, or tantalum, which have a closely matched thermal expansion coefficient with the circuit board, typically made of low-temperature cofired ceramic, to minimize mechanical stress and ensure stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a conventional coil device with circuit board and holder is used, then the sensor can be manufactured with standard components, but the circuit board is destroyed after repeated temperature changes or high temperature exposure due to mismatched thermal expansion coefficients

Engineering Contradiction:
ImprovemanufacturabilityVSAvoidhigh-temperature stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the material parameter (thermal expansion coefficient) of the holding element to match that of the circuit board. By selecting materials with comparable thermal expansion coefficients, the patent eliminates the destructive stress that occurs during temperature changes, thereby maintaining reliability in high-temperature applications while preserving ease of manufacture.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material selection by combining the circuit board with a holding element made of specific materials (zirconium, titanium, or tantalum) that have matched thermal expansion properties. This composite approach ensures both components can withstand high-temperature cycling without destruction, resolving the contradiction between manufacturability and high-temperature reliability.

Inventive Principle:
Principle #40Composite materials

2Ease of manufacture

If materials with different thermal expansion coefficients are used for circuit board and holding element, then manufacturing is simplified, but mechanical stress accumulates during temperature changes leading to component destruction

Engineering Contradiction:
Improveassembly simplicityVSAvoidmechanical integrity
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent modifies the material selection criterion by matching the thermal expansion coefficient parameter of the holding element to that of the circuit board. This parameter alignment prevents differential expansion during temperature changes, eliminating mechanical stress accumulation and preserving the mechanical integrity of the assembled components.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies homogeneity by ensuring the holding element and circuit board have matching thermal expansion properties. This material homogeneity in terms of thermal response ensures both components expand and contract together during temperature changes, preventing stress concentration and maintaining assembly integrity without complicating the manufacturing process.

Inventive Principle:
Principle #33Homogeneity

3Strength

If the circuit board is mechanically contacted with the holding device, then the coil device is securely mounted, but thermal stress destroys the circuit board in high-temperature applications

Engineering Contradiction:
Improvemounting securityVSAvoidthermal stability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent changes the material parameter of the holding element to have a thermal expansion coefficient that matches the circuit board. This parameter match allows secure mechanical contact and mounting while preventing thermal stress accumulation during high-temperature operation, thereby maintaining both mounting security and thermal reliability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The holding element acts as an intermediary component between the mounting structure and the circuit board. By selecting this intermediary material with matched thermal expansion properties, the patent enables secure mechanical contact while mediating against thermal stress transmission, thus protecting the circuit board in high-temperature applications.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 maintains the integrity of the circuit board by reducing thermal stress, ensuring the sensor's durability and magnetic properties remain consistent, even under high-temperature conditions.

Implementation Method 1

the holding device is configured to clamp the circuit board in order to hold the circuit board by means of lateral frictional engagement

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

the magnetic device and the coil device of an exciter or sensor interact with each other by means of magnetic fields

Methodology Applied
Scientific EffectMagnetic field interaction: Magnetic Field

Implementation Method 3

at least one exciter, which is configured to excite the at least one measuring tube to oscillate

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 4

at least two sensors, which are configured to detect the deflection of the oscillations of at least one measuring tube

Methodology Applied
Scientific EffectMagnetic field sensing: Magnetic Field

Data Source

PatentEP3833940B1Measuring sensor and measurement device
Publication Date: 2025.07.30 ENDRESS HAUSER FLOWTEC AG
  • EP3833940B1 patent drawingFigure 1
  • EP3833940B1 patent drawingFigure 2~3b
  • EP3833940B1 patent drawingFigure 4

AI summary

The invention relates to a measuring sensor (100) of a measurement device for detecting a mass flow or a density of a medium flowing through at least one measuring tube (110) of the measuring sensor, comprising the following features: the measuring tube has at least one exciter (10), which is designed to excite the at least one measuring tube to vibrate; at least two sensors (11) are provided, which are designed to detect the deflection of the vibrations of at least one measuring tube; the at least one exciter and the sensors each comprise a coil device (1), which coil device has a printed circuit board (2) having a first coefficient of thermal expansion, characterised in that at least one coil device of the sensors and/or the coil device of the exciter is secured by means of a retaining device (131), the retaining device being designed to clamp the printed circuit board, and the printed circuit board being mechanically contacted with the retaining device by means of at least one retaining element (132) of the retaining device, the retaining element having a second coefficient of thermal expansion, the first coefficient of thermal expansion and the second coefficient of thermal expansion differing from one another by less than 3*10-6 / Kelvin.