U-Shaped Spacer Centering for Coaxial Fluid Level Sensors

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Solution Overview

Problem

Current coaxial probes used in fluid level sensors are difficult to assemble, especially in the field, due to the requirement of sliding specially shaped spacers onto the inner rod, which can be cumbersome and inefficient.

Innovation Solution

The coaxial probe design incorporates U-shaped spacers that are snapped onto the inner rod using friction, with additional locking mechanisms such as crimpings and fasteners, allowing for easier assembly and secure positioning, while maintaining fluid flow channels and using non-conductive, impervious materials like stainless steel and PTFE.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If specially shaped spacers (star or disk shapes) are used to center the inner rod, then the inner rod is properly centered in the outer shell, but the assembly process becomes difficult and time-consuming as the spacers must be slid down the length of the inner rod

Engineering Contradiction:
Improvecentering precisionVSAvoidassembly ease
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

Instead of sliding the spacer down the inner rod from the top, the invention inverts the approach by attaching the spacer to the bottom end of the inner rod. The U-shaped spacer is positioned at the lower end and secured there, eliminating the need to slide it along the rod's length. This inversion of the attachment sequence resolves the assembly difficulty while maintaining centering precision.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The spacer is segmented into a U-shaped configuration with an opening, allowing it to be attached at the bottom end of the inner rod rather than requiring insertion from the top. This segmentation enables the spacer to be secured in place without sliding, simplifying the assembly process while still achieving proper centering of the inner rod within the outer shell.

Inventive Principle:
Principle #1Segmentation

2Strength

If solid spacers are used to center the inner rod, then the spacers provide structural support, but they prevent fluid from flowing up the inside of the probe between the inner rod and outer shell

Engineering Contradiction:
Improvespacer structural supportVSAvoidfluid flow blockage
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The spacer is designed with a U-shaped configuration that includes an opening, creating a porous or open structure rather than a solid block. This allows fluid to flow through the spacer and up the inside of the probe between the inner rod and outer shell, eliminating the harmful effect of fluid flow blockage while the spacer continues to provide the necessary structural support for centering.

Inventive Principle:
Principle #31Porous materials

3Ease of manufacture

If U-shaped spacers are snapped onto the inner rod using friction, then the assembly process is simplified, but additional locking mechanisms are required to ensure the spacers remain securely in position

Engineering Contradiction:
Improveassembly easeVSAvoidlocking mechanism complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The invention combines multiple functions into the spacer structure itself: the U-shape provides both the friction attachment mechanism and the fluid flow passage, while the stepped zones on the inner rod serve dual purposes of positioning and locking. This merging reduces the need for separate locking components, simplifying the overall device complexity while maintaining ease of assembly.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The spacer design enables self-locking through the interaction between the U-shaped structure and the stepped zones on the inner rod. The friction fit combined with the geometric constraints of the stepped zones allows the spacer to secure itself in position without requiring additional external locking mechanisms, thereby maintaining assembly ease while minimizing device complexity.

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 design simplifies the assembly process of coaxial probes by utilizing friction and locking mechanisms to secure U-shaped spacers, ensuring reliable fluid flow and accurate level measurements, even in harsh conditions, with the ability to disassemble for maintenance.

Implementation Method 1

the U-shaped spacers are held in position by friction

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2995914B1A mechanical system for centering and holding a coax conductor in the center of an outer conductor
Publication Date: 2023.04.05 HONEYWELL INTERNATIONAL INC
  • EP2995914B1 patent drawingFigure 1~2
  • EP2995914B1 patent drawingFigure 3~4
  • EP2995914B1 patent drawingFigure 5~6

AI summary

A coaxial fluid level sensor can be easily assembled and maintained with a minimum of required tooling by using U-shaped spacers to center an inner rod within an outer shell. The U-shaped spacers can be snapped onto the inner rod before or as the inner rod is inserted into the outer shell. The sensor can be extended by attaching additional inner rods and outer shells end to end.