Dielectric isolators

Patent metadata

Field	Value
Publication number	US-9618148-B2
Application number	US-201514589518-A
Country	US
Kind code	B2
Filing date	Jan 5, 2015
Priority date	Jul 2, 2008
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

The invention comprises dielectric isolators for use in aircraft fuel systems to control lightning induced current and allow dissipation of electrostatic charge. The dielectric isolators are configured to have a high enough impedance to limit lightning currents to low levels, but low enough impedance to allow electrostatic charge to dissipate without allowing buildup. Although the dielectric isolators may develop a potential difference across the dielectric length due to the effects of lightning currents and its inherent impedance, they are configured to withstand these induced voltages without dielectric breakdown or performance degradation. In one embodiment, the dielectric isolator includes a tube constructed of a composition including a thermoplastic organic polymer (e.g., PEEK) and carbon nanotubes, and a pair of fittings attached to opposing ends of the tube. In another embodiment, the dielectric isolator includes a tube, an outer annular portion, and an interconnecting web, each constructed from the composition including a thermoplastic organic polymer (e.g., PEEK) and carbon nanotubes. This later embodiment is an integrally formed one-piece structure. The dielectric isolator is capable of exhibiting an electrical resistance from about 10 5 Ω to 10 8 Ω at an applied potential of greater than 500 volts DC when measured from one fitting to the other fitting.

First claim

The invention claimed is:

1. A fluid carrying element for use in a fuel system of an aircraft as a dielectric isolator and especially adapted for interconnecting facing ends of a fluid carrying member disposed concentrically within an outer shroud, comprising:
a fluid carrying element within the fuel system of the aircraft including: (i) an inner tubular element interconnecting the facing ends of the fluid carrying member and arranged in an inline configuration with said facing ends; (ii) an outer annular portion interconnecting facing ends of the outer shroud; (iii) a circumferential web interconnecting the inner tubular element to the outer annular portion, said circumferential web including a plurality of openings; (iv) a pair of couplings for securing opposing ends of the outer annular portion to the facing ends of the outer shroud; and
wherein the inner tubular element is constructed of a composition including about 50 wt % to 98 wt % of PEEK, about 0.05 wt % to 2.0 wt % of carbon nanotubes; and
wherein the inner tubular element composition exhibits a bulk volume resistivity from about 10 3 Ω-cm to 10 10 Ω-cm at an applied potential of 5,000 volts DC.

2. The fluid carrying element of claim 1 , wherein:
said inner tubular element further includes an extension formed at each end of the inner tubular element, the extensions each defining annular cavities therein for receiving a protective rim; and
wherein each facing end of the fluid carrying member includes a fitting secured thereto, each fitting including an O ring placed in sealing contact with a corresponding protective rim thereby providing sealed contact between the inner tubular element and the facing ends of the fluid carrying member.

3. The fluid carrying element of claim 1 , wherein:
said outer annular portion further includes an extension formed at each end of the outer annular portion, the extensions each defining annular cavities therein for receiving a protective rim; and
wherein each facing end of the outer shroud includes a fitting secured thereto, each fitting including an O ring placed in sealing contact with a corresponding protective rim thereby providing sealed contact between the outer annular portion and the facing ends of the outer shroud.

4. The fluid carrying element of claim 1 , wherein:
each of the couplings includes a threaded portion that threadably mates with corresponding external threads formed on said outer extensions of said outer annular portion, and each coupling further includes a biasing element for urging said couplings in threaded engagement with said outer annular portion.

5. The fluid carrying element of claim 1 , wherein:
the dielectric isolator is capable of not exhibiting electrical arcing or sparking, either internally or externally, or waveform collapse during and after exposure to twelve voltage pulses, six in each polarity (positive and negative), having a peak amplitude of 9,000 volts that conform to voltage waveform B in accordance with SAE ARP5412.

6. The fluid carrying element of claim 1 , wherein the pair of couplings each includes a lock nut and a lock ring releasably engaged with one another.

Assignees

• Eaton Corp

Inventors

• Breay Clifton P
• Pfannenstiel Sara D
• Matthews Stephen C
• Bryant Edward W S

Classifications

• B64D37/32

  Safety measures not otherwise provided for, e.g. preventing explosive conditions · CPC title

• F16L25/025

  for joints with sleeve or socket · CPC title

• H01B17/42

  Means for obtaining improved distribution of voltage (capacitor-type lead-through insulators H01B17/28); Protection against arc discharges · CPC title

• Y10S977/742

  Carbon nanotubes, CNTs · CPC title

• B64D45/02

  Lightning protectors; Static dischargers · CPC title