Efficient grounding of electrical connection with challenging bonding path

Patent metadata

Field	Value
Publication number	US-11530633-B2
Application number	US-201916704596-A
Country	US
Kind code	B2
Filing date	Dec 5, 2019
Priority date	Dec 5, 2019
Publication date	Dec 20, 2022
Grant date	Dec 20, 2022

Abstract

A system and method of safely servicing a liquid-tight container installed in a location where flammable vapors or electrostatic shock exist, where the structure of the container is fabricated of a non-conductive material. The electrostatic charge build-up inside the container is achieved by coating the inside surface with a dissipative plastic and connecting the dissipative coating to a conductive feed-through with a metallic layer, where at least one of the metallic layer or the conductive layer extends over at least the region between a lower design fill level and an upper design fill level. The conductive feed-through is connected to a system static ground point which is isolated from electronic power supply grounds.

First claim

What is claimed is:

1. A liquid-tight container, comprising:
a non-conductive composite-material strength member enclosing a volume;
a filler aperture;
an interface for power and communications with an electronics assembly, the electronics assembly located within the liquid-tight container;
a static ground feed-through located to penetrate a wall of the liquid-tight container in a location different from the filler aperture;
a dissipative coating coated on an inner surface of the liquid-tight container; and
a metallic layer overlaying the dissipative coating on the inner surface of the liquid-tight container, the metallic layer connecting the dissipative coating to the static ground feed-through.

2. The container of claim 1 , wherein a surface resistivity of the dissipative coating is at least three orders of magnitude less than that of the non-conductive composite-material strength member.

3. The container of claim 1 , wherein the non-conductive composite-material strength member is comprised of a fiber embedded in a carbon matrix.

4. The container of claim 1 , wherein a location of the static ground feed-through on the container is selected to minimize a physical length of a cable connecting the static ground feed-through to an external static ground connection.

5. The container of claim 1 , wherein a ground of the electronics assembly is isolated from an external static ground.

6. The container of claim 1 , wherein at least one of the metallic layer or the dissipative coating extends over a height range including a lower design liquid level and an upper design liquid level.

7. The container of claim 1 , wherein the dissipative coating is a first dissipative coating, the container further comprising: a second dissipative coating on an outer surface of the liquid-tight container.

8. The container of claim 7 , wherein the second dissipative coating on the outer surface of the liquid-tight container and the first dissipative coating on the inner surface of the liquid-tight container are different materials.

9. The container of claim 1 , wherein a surface resistivity of the dissipative coating is between 10 6 -10 12 ohms/sq. and a surface resistivity of the non-conductive composite material is between 10 14 -10 18 ohms/sq.

10. A method of preventing electrostatic discharge in a liquid-tight container, the method comprising:
providing a non-conductive composite material forming a liquid-tight volume;
coating an interior surface of the liquid-tight volume with a dissipative layer;
applying a metallic layer to the interior surface of the liquid-tight volume;
providing a first static ground feed-through in a wall of the liquid-tight volume in a location different from a filler aperture of the liquid-tight container; and
connecting the metallic layer to the first static ground feed-through.

11. The method of claim 10 , wherein a surface resistivity of the dissipative layer is at least three orders of magnitude less than a surface resistivity of the non-conductive composite material.

12. The method of claim 11 , wherein the surface resistivity of the dissipative layer is between 10 6 -10 12 ohms/sq. and the surface resistivity of the non-conductive composite material is between 10 14 -10 18 ohms/sq.

13. The method of claim 10 , further comprising providing a liquid-tight interface for power and communications to an electronics module inside the liquid-tight liquid container.

14. The method of claim 13 , wherein there is no electrical connection between the liquid-tight interface and either the first static ground feed-through.

Assignees

• Rolls Royce Corp

Inventors

• Gebhard John
• Kempers Adam
• Gallagher Jeremy

Classifications

• F16N2210/02

  Turbines · CPC title

• F16N19/003

  Indicating oil level (measuring liquid level in general G01F) · CPC title

• F01M11/12 Primary

  concerning lubricant level · CPC title

• F16N2210/08

  Aircraft · CPC title