Positive locking fastener

Patent metadata

Field	Value
Publication number	US-11353054-B2
Application number	US-201816622932-A
Country	US
Kind code	B2
Filing date	Jun 14, 2018
Priority date	Jun 15, 2017
Publication date	Jun 7, 2022
Grant date	Jun 7, 2022

Abstract

The invention relates to a positive locking fastener comprising: a screw (1) having a cavity (110) at a threaded portion (11); a nut (2) having a tightening portion (21); a first cap (3); a second cap (4); and a pin (5). The first cap is suitable for being inserted into the cavity of the threaded portion. The second cap has a locking portion (402) intended to engage with the first cap and a blocking portion (401) intended to engage with a tightening portion (21) of the nut. The locking portion of said second cap comprises openings (4020) suitable for allowing the pin to be inserted through said openings in order to hold the first cap and the second cap together. The invention also relates to a method for implementing the fastener according to the invention.

First claim

The invention claimed is:

1. A positive locking device intended to limit the loosening of a nut installed on a screw, said screw extending along a longitudinal axis (Δ), said nut having a tightening portion of angular period θ, said locking device comprising a first cap and a second cap to be assembled on the screw and nut when the nut is placed on the screw, the first cap and the second cap being characterized in that:
the first cap, having a main first cap axis substantially coincident with the longitudinal axis (Δ) when the first cap is placed on an assembly of a screw and a nut, the first cap comprising:
means for centering and immobilizing in rotation configured to cooperate with a free end of the screw when the first cap is placed on the screw;
axial translation blocking means configured to cooperate with a thread of the screw when the first cap is placed on the screw, and a guide cylindrical outer surface parallel to the main first cap axis;
the second cap, having a main axis substantially coincident with the main first cap axis when the device is in place on an assembly of a screw and a nut, is configured to cooperate with such a nut and to engage with the first cap, and in that said second cap comprises:
a blocking portion at a first end, an inner surface of said blocking portion having, in a plane perpendicular to the main axis of said second cap, an internal profile (P′) of angular period θ/k, where k is a non-zero natural integer, around the main axis of said body, dimensions of the profile (P′) being configured to allow the blocking portion to be placed on a tightening portion of a nut when the second cap is placed on an assembly of a screw and a nut, and when such a tightening portion is inserted into said blocking portion, the dimensions of the profile (P′) are configured to allow a relative rotational movement of said blocking portion with respect to said nut, about the main axis of said second cap, of angular amplitude θ/2k;
a locking portion at a second end having a set of openings passing through said locking portion and intended to receive a pin;

said blocking and locking portions being secured and fixed together; an inner surface of the locking portion of the second cap and the outer surface of the first cap are adapted to engage with each other with an angular pitch θ/2k.

2. The device according to claim 1 , wherein the outer surface of the first cap has at least one tab, and the inner surface of the locking portion of the second cap has a set of splines, adapted to receive the at least one tab of the first cap.

3. The device according to claim 1 , wherein the inner surface of the locking portion of the second cap has at least one tab, and the outer surface of the first cap has a set of splines adapted to receive the at least one tab.

4. The device according to claim 1 , wherein the outer surface of the first cap and the inner surface of the locking portion both have a set of splines, separated by an angular pitch θ/2k.

5. The device according to claim 1 characterized in that k is equal to 1.

6. The device according to claim 1 , characterised in that:
the first cap comprises a plate substantially perpendicular to the main axis of said first cap;
the means for centering and immobilizing the first cap comprise a central pillar of substantially cylindrical shape with a non-circular cross-section, said central pillar extending from a central area of a lower face of the plate in the direction given by the main axis of the first cap;
the means for blocking in axial translation of said first cap comprise at least one foot extending in a direction of the main axis of said first cap from the lower face of the plate, said at least one foot comprising a claw extending in a plane substantially perpendicular to the main axis of said first cap from the at least one foot towards said central pillar, said at least one foot being made of an elastic material to allow the engagement of the at least one foot with a thread of a screw.

7. The device according to claim 6 , characterised in that the first cap comprises four feet.

8. The device according to claim 6 , wherein the central pillar has a cylindrical shape with a polygonal cross-section.

9. The device according to claim 1 , wherein the openings are notches.

10. The device according to claim 1 , wherein the openings are oblong holes.

11. A positive locking fastener comprising:
a screw having a longitudinal axis (Δ) and comprising at a first end a head and at a second free end a threaded portion comprising a cavity opening onto said second free end of the screw;
a nut intended to be placed on the screw, said nut comprising a tightening portion of which an outer surface defines in a plane perpendicular to the longitudinal axis (Δ) a profile (P) of angular period θ; said fastener being characterized in that it further comprises:
a positive locking device according to claim 1 , wherein the means for centering and immobilizing the first cap cooperate with the cavity in order to immobilize said first cap in rotation relative to the screw, the axial translation locking means cooperating with a thread of said screw in order to immobilize said first cap in axial translation with respect to said screw, a radial dimension of the profile (P′) being adapted to allow the insertion of the tightening portion into the blocking portion;
a pin for insertion into the openings of the second cap so as to hold together the first cap and the second cap.

12. The fastening according to claim 11 wherein:
the first cap comprises a plate substantially perpendicular to the main axis of said first cap;
the means for centering and immobilizing the first cap comprise a central pillar of substantially cylindrical shape with a non-circular cross-section, said central pillar extending from a central area of the lower face of the plate in the direction given by the main axis of the first cap;
the means for blocking in axial translation of said first cap comprise at least one foot extending in a direction of the main axis from the lower face of the plate, said at least one foot comprising a claw extending in a plane substantially perpendicular to the main axis from the at least one foot towards said central pillar, said at least one foot being made of an elastic material to allow the fitting of the at least one foot into a thread of the screw, and wherein
an inner surface of the cavity forms a complementary cavity of the central pillar so that said central pillar is adapted to be inserted into said cavity;
the claws of the first cap are interlocked in the thread of the screw.

13. The fastening according to claim 12 , wherein:
the nut defines a star-shaped profile (P) at twelve vertices of angular period 30°;
the outer surface of the first cap has twenty-four tabs separated by an angular pitch of 15°.

14. A method for implementing a fastening according to claim 1 , characterized in that it comprises the following steps:
inserting the screw having a longitudinal axis (Δ) into a previously made hole in a structural assembly that includes structural elements to be held together;
placing the nut on the screw by applying a tightening torque;
placing the first cap on the screw;
placing the second cap;
if the second cap engages with the first cap but does not cooperate with the tightening portion of the nut, removing said second cap in the direction of the longitudinal axis (Δ), rotating said second cap clockwise or counterclockwise about said longitudinal axis, by an angle equal to θ/2k, then resetting said second cap, this step being repeated, always in the same direction of rotation, until

Assignees

• Lisi Aerospace

Inventors

• Goyer Julien
• Abou Halima Mohamed
• Meiffre Loïc

Classifications

• F16B37/14 Primary

  Cap nuts; Nut caps or bolt caps · CPC title

• F16B39/08 Primary

  with a cap interacting with the nut, connected to the bolt by a pin or cotter pin · CPC title