Plastic caps filled with sealing compound as combined protection against fuel and hydraulic fluid and against lightning strikes

{
  "publication_number": "US12060160B2",
  "country": "US",
  "kind": "B2",
  "title": "Plastic caps filled with sealing compound as combined protection against fuel and hydraulic fluid and against lightning strikes",
  "abstract": "Provided herein are sealing compound-filled plastic caps for sealing of connecting elements in aircraft construction against liquids, wherein these plastic caps function as combined protection against fuel and hydraulic oil, especially that based on tributyl phosphate, and against lightning strikes, and can be produced and applied in an economically viable manner. The plastic cap for sealing of connecting elements in aircraft construction consists predominantly of at least one high-performance polymer having a breakdown resistance of at least 10 kV/mm to DIN IEC 60243, and has been filled with a sealing compound having a high energy absorption capacity and including at least one filler selected from the group consisting of gas- and/or air-filled hollow packings, where the plastic cap and the sealing compound are cohesively bonded to one another. Additionally provided is a method of filling and application of such plastic caps, and a corresponding aircraft.",
  "claims": [
    "1. A plastic cap for sealing of connecting elements in aircraft construction, which: comprises at least 50 wt % of at least one polymer, has a breakdown resistance of at least 10 kV/mm to DIN IEC 60243, and has been filled with a sealing compound including at least one filler selected from the group consisting of gas- and/or air-filled hollow packings, wherein the hollow packings in the at least one filler are microballoons, wherein the sealing compound has a content of the at least one filler in the range from 1% to 7% by weight, wherein the plastic cap and the sealing compound are cohesively bonded to one another, and wherein the at least one polymer is a polyetherimide.",
    "2. The plastic cap according to claim 1, wherein the at least one polymer has been impact-modified.",
    "3. The plastic cap according to claim 1, wherein the at least one polymer has a water absorption of not more than 1.5%.",
    "4. The plastic cap according to claim 1, wherein the sealing compound has a density between 0.7 and 1.5 g/cm 3.",
    "5. The plastic cap according to claim 1, wherein the sealing compound comprises a filler combination consisting of at least one filler selected from the group consisting of gas- and/or air-filled hollow packings and of at least one further filler selected from the group consisting of mineral and polymeric, non-gas-and/or-air-filled fillers.",
    "6. The plastic cap according to claim 1, wherein the plastic cap and the sealing compound are cohesively bonded to one another by a chemical attachment.",
    "7. The plastic cap according to claim 1, wherein the plastic cap is stable to kerosene and hydraulic oil.",
    "8. An aircraft having at least one connecting element to which a plastic cap according to claim 1 has been applied.",
    "9. A method of filling and mounting a plastic cap according to claim 1, wherein the plastic cap is filled with a sealing compound according to claim 1 by means of a metering robot or manually, then applied to a connecting element in an aircraft by means of an automated method step or manually, and the sealing compound is cured.",
    "10. The method according to claim 9, wherein the plastic cap is filled with the sealing compound by means of a metering robot and then applied to a connecting element in an aircraft by means of an automated method step."
  ],
  "description_excerpt": "The present invention is in the field of sealing of connecting elements in aircraft construction. It relates to sealing compound-filled plastic caps that function as combined protection against fuel and hydraulic oil and against lightning strikes. In addition, the invention includes a method of filling and application of such plastic caps and a corresponding aircraft.\n\nIn the aircraft industry, connecting elements, especially rivets, rivet heads and screw connections, are coated with sealing compound in order to seal them off from fuel and hydraulic oil and protect them from corrosion by moisture and also by electrochemical reaction.\n\nSuch sealing additionally prevents the possible loss of fuel via leaky sites at the connecting elements, and also a pressure drop within the aircraft.\n\nIn parts of an aircraft that are at particular risk, there is also use of special plastic caps sealed with sealing compound (=seal caps) which, by virtue of their complex construction - in the form of a twin-shell construction with an integrated air gap - are additionally intended to provide protection from lightning strikes. Configurations of such seal caps are known in the art and are depicted, for example, in FIGS. 1-3 of U.S. Patent Publication No. 2013/015316.\n\nBoth the filling of these caps with sealing compound and the application thereof, i.e. the mounting thereof on the connecting elements to be sealed, is very complex. Moreover, the surface of the caps has to be painted in order to assure good adhesion of the sealing compound on the inside.",
  "cpc": [
    "B64D 45/02",
    "C09K 3/10",
    "C09K 3/1006",
    "C09K 3/1012",
    "F16B 2013/006",
    "F16B 33/004",
    "F16B 37/14"
  ],
  "ipc": [
    "B64D 45/02",
    "C09K 3/10",
    "F16B 13/00",
    "F16B 33/00",
    "F16B 37/14"
  ],
  "assignees": [
    "Chemetall GmbH"
  ],
  "inventors": [
    "Heinz Burock",
    "Hendrik Becker"
  ],
  "filing_date": "2018-03-26",
  "publication_date": "2024-08-13",
  "grant_date": "2024-08-13",
  "priority_date": "2017-04-03",
  "application_number": "US-201816498517-A",
  "family_id": "62089707",
  "cited_by_count": 0,
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    "US20130153136A1",
    "US20170008636A1",
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    "WO2014172302A1",
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    "US20170108029A1",
    "WO2018019848A1",
    "US20190162223A1"
  ]
}