Drain nut attachment structure for synthetic resin cover

{
  "publication_number": "US10787941B2",
  "country": "US",
  "kind": "B2",
  "title": "Drain nut attachment structure for synthetic resin cover",
  "abstract": "Disclosed is a structure for attachment of a drain nut to a synthetic resin cover. The cover has a nut engagement portion formed in an outer surface of the cover, a cylindrical engagement portion formed with a plurality of piece parts on an inner surface of the cover, and a stepped portion formed between the nut and cylindrical engagement portions. The drain nut has a nut portion engaged in the nut engagement portion, a female thread portion formed in the nut portion for screw-in of a drain plug, a cylindrical portion formed concentrically with the nut portion and engaged in the cylindrical engagement portion, a large-diameter portion formed between the nut and cylindrical portions and engaged in the stepped portion, with an O-ring held between the large-diameter portion and stepped portion, and a collar portion formed around the cylindrical portion and retained by front ends of the piece parts.",
  "claims": [
    "1. A drain nut attachment structure comprising: a synthetic resin cover; and a drain nut made of a metal material and attached to the synthetic resin cover, wherein the drain nut comprises: a nut portion having a noncircular outer circumferential surface; a female thread portion formed in the center of the nut portion such that a drain plug is screwed in the female thread portion; a cylindrical portion formed concentrically with the nut portion; and a large-diameter portion formed coaxially between the nut portion and the cylindrical portion and having a cylindrical outer circumferential surface larger in diameter than the cylindrical portion and smaller in diameter than the nut portion, wherein the synthetic resin cover comprises: a nut engagement portion formed in a noncircular shape to be open to an outer surface of the synthetic resin cover such that the nut portion is engaged in the nut engagement portion; a stepped portion formed to be open to a bottom surface of the nut engagement portion and having a cylindrical inner circumferential surface: a though hole formed to be open at one end thereof to a bottom surface of the stepped portion; and a cylindrical engagement portion formed on the inner surface of the synthetic resin cover and having a plurality of piece parts disposed circumferentially at predetermined intervals in an annular arrangement around the through hole, wherein an O-ring is arranged to establish a radial seal between the inner circumferential surface of the stepped portion and the outer circumferential surface of the large-diameter portion, and wherein the drain nut further comprises a collar portion formed on a front end of the cylindrical portion and protruding radially outwardly from the cylindrical portion so as to be retained by front ends of the piece parts.",
    "2. The drain nut attachment structure according to claim 1, wherein the cylindrical portion has at least two drain holes formed therethrough from an inner circumferential surface to an outer circumferential surface of the cylindrical portion at positions opposed to each other in a diameter direction.",
    "3. The drain nut attachment structure according to claim 1, wherein the piece parts include radially inwardly protruding hooks provided on the front ends thereof, wherein each of the hooks has a tapered surface formed on an inner circumferential side thereof and inclined radially inwardly toward the front, and wherein the collar portion has a tapered surface formed on an outer circumferential side thereof and inclined radially inwardly toward the front.",
    "4. The drain nut attachment structure according to claim 1, wherein the drain nut further comprises a second collar portion protruding radially outwardly from the outer circumferential surface of the nut portion so as to cover a slight clearance between the nut portion and the nut engagement portion from a side of the outer surface of the synthetic resin cover.",
    "5. The drain nut attachment structure according to claim 4, wherein the synthetic resin cover comprises a recess portion formed in the outer surface of the synthetic resin cover such that an outer circumferential edge of the second collar portion is engaged in the recess portion.",
    "6. The drain nut attachment structure according to claim 5, wherein the synthetic resin cover comprises a protruding portion protruding from the outer surface of the synthetic resin cover according to an outer shape of the second collar portion such that the recess portion is defined by the protruding portion."
  ],
  "description_excerpt": "The present invention relates to a drain nut attachment structure for a synthetic resin cover that is suitable as an oil pan of an internal combustion engine or automatic transmission etc.\n\nAlthough oil pans made of steel are generally widely used in internal combustion engines, there has recently been made an attempt to use oil pans made of synthetic resins such as FRP (fiber-reinforced plastics). The oil pan of the internal combustion engine needs to be equipped with a detachable screw-in drain plug so as to drain oil from the inside of the oil pan.\n\nFor example, Japanese Laid-Open Patent Publication No. 2012-255373 (abbreviated as JP 2012-255373 A) discloses a drain plug installing structure for a synthetic resin oil pan, which includes a metal drain nut attached to the oil pan from the inside of the oil pan and a drain plug screwed in a female thread portion of the drain nut from the outside of the oil pan. More specifically, the drain nut is unrotatably fixed to the oil pan by engaging a hexagonal nut portion of the drain nut in a hexagonal nut engagement portion of the oil pan, with a cylindrical portion of the drain nut passing through a through hole of the oil pan, and tightening the drain plug to the cylindrical portion of the drain nut.\n\nAn O-ring is provided as a radial seal between the oil pan and the drain nut, while there is a slight radial clearance left between other parts of the oil pan and the drain nut.",
  "cpc": [
    "F01M 11/0408",
    "B62D 29/041",
    "F01M 11/04",
    "F01M 11/0458",
    "F01M 2011/0416",
    "F16B 33/006",
    "F16H 57/0408",
    "F16N 31/00"
  ],
  "ipc": [
    "B62D 29/04",
    "F01M 11/04",
    "F16B 33/00",
    "F16N 31/00"
  ],
  "assignees": [
    "Mahle Filter Systems Japan Corp"
  ],
  "inventors": [
    "Daizo ITO",
    "Shin Yoshida",
    "Atsushi Nonaka",
    "Yuichi Kato"
  ],
  "filing_date": "2017-11-15",
  "publication_date": "2020-09-29",
  "grant_date": "2020-09-29",
  "priority_date": "2016-12-01",
  "application_number": "US-201715813446-A",
  "family_id": "60409165",
  "cited_by_count": 0,
  "citations": [
    "JPS61108813U",
    "DE3838250C1",
    "US4938314A",
    "US20090218168A1",
    "WO2011008261A1",
    "US8109704B2",
    "US20110284539A1",
    "JP2012255373A",
    "US20160252191A1"
  ]
}