Wetting Current Sequencing for Sensor Contact Oxidation

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Solution Overview

Problem

High accuracy aircraft sensor systems face reliability issues due to contact resistance caused by oxidation at connections, which introduces significant errors in low operational current environments, rendering sensor circuits unreliable.

Innovation Solution

An automated method involving a sequencing controller that generates a high initial current to burn off oxidation at contacts and then reduces the current to a lower operational level, ensuring a stable connection while preventing further oxidation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a high current is used to burn off oxidation at contact points, then contact reliability is improved, but the operational current requirement increases and sensor accuracy deteriorates

Engineering Contradiction:

Improvecontact reliabilityVSAvoidsensor accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by implementing an initialization sequence that activates a high current wetting circuit before the sensor becomes operational. This preliminary high current flow burns off oxidation from contact points in advance, ensuring clean contacts before low-current sensing begins. The sequencing controller ensures the wetting circuit operates only during initialization, preventing oxidation buildup before the sensor starts measuring.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent segments the electrical system into two distinct circuits: a high-current wetting circuit for oxidation removal and a low-current sensor circuit for accurate measurement. The wetting circuit includes separate wetting current sources for the sensor module and controller input, allowing independent control. This segmentation enables each circuit to be optimized for its specific function without interfering with the other.

Inventive Principle:

Principle #1Segmentation

2Reliability

If a high current is continuously applied to prevent oxidation, then contact reliability is improved, but energy consumption increases

Engineering Contradiction:

Improvecontact reliabilityVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic action by applying high current only during initialization and system startup, then switching to low-current operation. The sequencing controller manages the wetting circuit to provide high current pulses only when needed (during initialization sequence), rather than continuously. This periodic application of high current maintains contact reliability while minimizing energy consumption during normal operation.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies preliminary action by performing oxidation removal during system initialization before normal operation begins. The high current wetting circuit operates only during this preliminary phase to establish clean contacts, after which the system transitions to low-current operation. This preliminary treatment prevents the need for continuous high current application.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If a high current is used to wet the contact, then contact reliability is improved, but the sensor signal becomes overwhelmed and measurement precision deteriorates

Engineering Contradiction:

Improvecontact reliabilityVSAvoidsensor signal accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary action by implementing an initialization sequence that activates the high current wetting circuit before the sensor becomes operational. This preliminary high current flow burns off oxidation from contact points in advance, ensuring clean contacts before low-current sensing begins. The sequencing controller ensures the wetting circuit operates only during initialization, preventing oxidation buildup before the sensor starts measuring.

Inventive Principle:

Principle #10Preliminary action

4Use of energy by moving object

If the system remains unpowered for extended periods, then energy consumption is reduced, but oxidation develops on contact points and reliability deteriorates

Engineering Contradiction:

Improveenergy consumptionVSAvoidcontact reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies preliminary action by implementing an initialization sequence that activates high current wetting circuits when the system is powered on after extended unpowered periods. This preliminary high current flow burns off oxidation that developed during storage, ensuring clean contacts before normal operation begins. The sequencing controller detects system startup conditions and triggers the wetting sequence accordingly.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements periodic action by applying high current only during initialization and system startup after unpowered periods, then switching to low-current operation. The sequencing controller manages the wetting circuit to provide high current pulses only when needed (during initialization sequence), rather than continuously. This periodic application of high current maintains contact reliability while minimizing energy consumption during normal operation.

Inventive Principle:

Principle #19Periodic action

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 effectively maintains a reliable contact connection in high accuracy sensor systems by removing oxidation and allowing continued operation at low current levels, preventing further oxidation and ensuring accurate sensor signal interpretation.

Implementation Method 1

generating a first current through a contact by sequencing a first circuit on, the first current exceeding a wetting threshold of the contact

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

The contacts provide a physical contact point between one or more connections in each of the systems or modules. The contact point allows electrical signals to be transferred from one system or module to the other system or module

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3086419B1Wetting current sequencing for low current interface

Publication Date: 2017.10.18 HAMILTON SUNDSTRAND CORP

AI summary

A process for automated contact wetting in a sensor circuit includes generating a first current through a contact (40) by sequencing a first circuit on, the first current exceeding a wetting threshold of the contact (40), and reducing current through the contact (40) to a second current by sequencing a second circuit on, the second current being below the wetting threshold.