Inductive Proximity Probe Piston Sensing for Compact Fuel Valves

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Solution Overview

Problem

Conventional methods for determining the position of pistons in aircraft fuel systems, such as using Linear Variable Differential Transformers (LVDTs, are inefficient and require significant space, limiting their applicability and ease of tuning.

Innovation Solution

The use of an inductive or capacitive proximity probe sensor with a piston assembly featuring a variable surface, such as a tapered or notched surface, to detect the piston's position within a housing, allowing for more compact and efficient positioning systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional LVDTs are used to detect piston position, then measurement precision is achieved, but device complexity and volume increase significantly

Engineering Contradiction:

Improvepiston position detection accuracyVSAvoidpositioning system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical LVDT system with an inductive proximity sensor that uses electromagnetic fields to detect piston position. The inductive sensor generates an oscillating magnetic field that interacts with the metallic piston surface, providing contactless measurement and eliminating the mechanical complexity of LVDT components while maintaining measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts only the essential sensing function from the complex LVDT system by using a simple inductive proximity sensor. This extraction approach removes unnecessary mechanical components while retaining the core capability of detecting piston position through electromagnetic interaction with the piston's metallic surface.

Inventive Principle:

Principle #2Taking out (Extraction)

2Measurement precision

If conventional LVDTs are used to detect piston position, then measurement precision is achieved, but the volume and weight of the system increase

Engineering Contradiction:

Improvepiston position detection accuracyVSAvoidpositioning system volume

Core Design Contradiction:

Measurement precisionVSVolume of moving object

Solution Approach 1:

The inductive proximity sensor replaces the bulky mechanical LVDT assembly with a compact electromagnetic sensing device. This substitution dramatically reduces the volume required for position detection while maintaining measurement accuracy, as the inductive sensor can be mounted directly on the housing near the piston without requiring extensive mechanical linkages.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the measurement approach from mechanical displacement sensing to electromagnetic field interaction. By altering the fundamental measurement parameter from mechanical position to inductive coupling strength, the system achieves accurate piston position detection with significantly reduced component volume and weight.

Inventive Principle:

Principle #35Parameter changes

3Loss of information

If conventional LVDTs are used, then piston position feedback is obtained, but ease of operation and tuning are reduced

Engineering Contradiction:

Improvepiston position feedbackVSAvoidsystem tuning ease

Core Design Contradiction:

Loss of informationVSEase of operation

Solution Approach 1:

The inductive proximity sensor provides electronic feedback signals that are more easily processed and tuned than mechanical LVDT outputs. The sensor's electrical signal can be directly integrated with electronic control systems, eliminating the need for complex mechanical tuning and adjustment procedures while maintaining full piston position feedback capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The inductive sensor system requires minimal manual tuning and adjustment, as it automatically adapts to the piston's metallic surface characteristics. The sensor's electromagnetic field naturally couples with the piston, providing self-adjusting feedback that reduces the need for operator intervention and complex tuning procedures.

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 solution enables precise and compact piston position detection, reducing weight and volume, and allowing for easier interchangeability and tuning, thereby improving the reliability and efficiency of fuel control systems.

Implementation Method 1

an inductive proximity probe sensor positioned on the housing configured to detect a position of the piston with the housing

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4400751A1Proximity probe piston positioning systems

Publication Date: 2024.07.17 HAMILTON SUNDSTRAND CORP

Figure 1~3
Figure 4

AI summary

A piston assembly includes a housing, a piston (106) positioned within the valve housing (102), and an inductive proximity probe sensor (104) positioned on the housing configured to detect a position of the piston with the housing. The piston is configured to at least one of rotate or translate axially relative to the housing. The piston includes a variable surface (108). A fuel control system includes the piston assembly (100), a servo valve (116) in fluid communication with the piston assembly, and an engine controller (114). The engine controller is operatively connected to the inductive proximity probe sensor.