Measuring Circuit Test Signal Injection via Sensing Element

Solution Overview

Problem

Current measuring circuits for monitoring vibrations in machines, such as engines and turbines, are limited in their built-in test equipment (BITE) functionality, as they cannot effectively test the sensing element, and require additional injection capacitors that increase production costs and potential error sources.

Innovation Solution

The measuring circuit design interconnects the injection line and transmission line series via the sensing element, allowing the test signal to be fed through the sensing element, thereby enabling monitoring and testing of the sensing element's functionality, eliminating the need for additional injection capacitors and reducing complexity and error sources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional injection capacitors are provided to enable test signal injection, then the measuring circuit can perform permanent surveillance, but the production costs increase and additional error sources are introduced

Engineering Contradiction:

Improvepermanent surveillance capabilityVSAvoidnumber of additional components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the additional injection capacitors from the circuit design. Instead of using separate capacitors for test signal injection, the invention utilizes the existing transmission line and sensing element combination to achieve both measurement and test signal transmission functions, thereby eliminating unnecessary components while maintaining permanent surveillance capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The transmission line is designed to serve dual purposes: transmitting both measuring signals from the sensing element and test signals from the signal injector to the evaluation circuit. This multi-functionality eliminates the need for separate injection capacitors and reduces overall circuit complexity while maintaining reliable operation and testing capabilities

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If additional injection capacitors are provided for test signal injection, then the measuring circuit can perform permanent surveillance, but possible error sources increase

Engineering Contradiction:

Improvepermanent surveillance capabilityVSAvoiderror sources

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent removes the additional injection capacitors from the circuit design. Instead of using separate capacitors for test signal injection, the invention utilizes the existing transmission line and sensing element combination to achieve both measurement and test signal transmission functions, thereby eliminating unnecessary components while maintaining permanent surveillance capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the sensing element from being merely a measurement component into a dual-purpose component that also serves as the test signal injection path. By feeding the test signal through the sensing element itself, the invention turns the sensing element into a benefit for self-testing, eliminating the need for separate injection capacitors that would introduce additional error sources

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Measurement precision

If the test signal is passed around the terminals of the sensing element by injection capacitors, then the transmission line can be tested, but the sensing element itself cannot be tested

Engineering Contradiction:

Improvetransmission line monitoringVSAvoidsensing element testing capability

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The transmission line is designed to serve dual purposes: transmitting both measuring signals from the sensing element and test signals from the signal injector to the evaluation circuit. This multi-functionality eliminates the need for separate injection capacitors and reduces overall circuit complexity while maintaining reliable operation and testing capabilities

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

Instead of passing the test signal around the sensing element terminals as in prior art, the invention inverts the approach by feeding the test signal directly through the sensing element itself. This reversal enables comprehensive testing of the sensing element's functionality while maintaining transmission line monitoring capabilities

Inventive Principle:

Principle #13The other way round (Inversion)

4Adaptability or versatility

If the injection line and transmission line are interconnected in series via the sensing element, then the sensing element can be tested, but the circuit complexity increases

Engineering Contradiction:

Improvesensing element testing capabilityVSAvoidcircuit configuration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The transmission line is designed to serve dual purposes: transmitting both measuring signals from the sensing element and test signals from the signal injector to the evaluation circuit. This multi-functionality eliminates the need for separate injection capacitors and reduces overall circuit complexity while maintaining reliable operation and testing capabilities

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 design enhances BITE functionality, making error sources related to the sensing element identifiable, reduces production costs, and increases the reliability and economy of the circuit by directly feeding the test signal through the sensing element, ensuring unambiguous quality verification.

Implementation Method 1

The sensing element of this circuit is provided by a piezoelectric transducer

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP2767808B9Measuring circuit

Publication Date: 2021.09.01 MEGGITT SA

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AI summary

The invention relates to a measuring circuit comprising - an evaluation circuit (13, 63); - a sensing circuit (39, 40) comprising a sensing element (6, 55) configured to generate a measuring signal from a measuring object (7) and a transmission line (26, 69) for transmitting the measuring signal to the evaluation circuit (13, 63); and - a test signal injection circuit (21) comprising a signal injector (12) and an injection line (20) connecting a signal output of the signal injector (12) with the sensing circuit (39, 40) for feeding a test signal into the sensing circuit (39, 40) such that the test signal is transmittable to the evaluation circuit (13, 63) over the transmission line (26, 69). To provide the measuring circuit with an improved surveillance and/or testing operability, the invention suggests that the injection line (20) and the transmission line (26, 69) are interconnected in series via the sensing element (6, 55) such that said test signal can be fed through the sensing element (6, 55).