CONNECTION

FIELD OF THE INVENTION

[1] The invention relates to an aircraft seat fastener provided with a helicoidal clamping connection. Some embodiments of the invention relate to an aircraft seat attachment provided with a system for maintaining a clamping force by friction. Some embodiments of the invention relate to an aircraft seat attachment provided with a system for locking an activation lever.

BACKGROUND

[2] The passenger seats of civilian airliners are generally mounted on a rail 1 shown in Figures la and lb. The rail 1 is a section piece having a top lip 2 to which the seat fastener is clamped, this lip 2 being machined to allow the lower part of the fastener (studs) to be inserted under the lip of the rail.

[3] A seat is generally attached to the rail using a minimum of three but typically four fasteners, two at the front of the seat and two at the rear. Typically, a passenger seat fastener 3, such as the one shown in Figure 2, needs to perform two key functions, namely:

- clamping the fastener 3 to the lip 2 of the rail to prevent any movement, and

in the case of the rear fasteners, transferring longitudinal loads from the seat to the rail, in the event of a crash for example.

[4] The fastener 3 for this purpose comprises at least one stud 6, which will be positioned under the lip 2 of the rail. This stud 6 is either fixed with respect to the fastener 3, in which case the fastener 3 needs to comprise a plunger 8 able to move vertically relative to a body 4 of the fastener (cf. Figure 2), or is able to move with respect to said body 4 of the fastener 3.

[5] In order to fasten the seat to the rail 1, the stud 6 passes through the drilling in the rail, and then moves by half the pitch of the drilling in order to position itself under the lip 2 of the rail 1. Thereafter, the stud 6 is moved vertically until it comes into contact with the underside of the lip 2 and creates positive clamping against the lip 2 of the rail. [6] There are two techniques usually employed for generating the force with which the fastener is clamped to the lip 2 of the rail:

the use of a screw that moves the stud 6 or the plunger 8 vertically. In that case, a hand tool is required and the tightening torque needs to be controlled so as to guarantee clamping. This solution furthermore allows infinite adjustment, making it possible to absorb any tolerances on the components involved, or

the use of an adjustment-free system that may or may not demand the use of a hand tool, and generally using a spring effect, provided by an elastic element 9 (spring washer, block of elastomer, spring etc.) to absorb geometric tolerances and guarantee the required level of clamping.

[7] If need be, longitudinal loads are transferred to the rail by a shear element 10 protruding from an underside of the plunger 8 and nestling in the drillings of the rail.

[8] The adjustment-free systems generally employ an activation lever 11. In most cases, the lever 11 generates the clamping, and the path Bl of the clamping load passes through the lever 11 as can be seen in Figure 2. In order to keep the lever 11 in place, use is made of a locking system 12 for example situated at one end of the lever 11. This system 12 takes, for example, the form of a hook intended to collaborate with a corresponding pin belonging to the body 4. However, some of these systems are not sufficiently secure as the lever and/or the locking facility remains in a locked position that is unstable (cf. Figure 3) insofar as it is unable to maintain the energy spike corresponding to clamping if the fastener experiences pressures such as vibrations. In other systems, this locked position is not clearly identifiable.

[9] The invention seeks effectively to overcome at least one of these disadvantages by proposing an aircraft seat fastener which comprises a body intended to be secured to an aircraft seat and a shank provided at one of its ends with a stud, said body and said shank being connected to one another by a helicoidal connection that is irreversible under axial load so that a turning of the shank brought about via an operating device is able to cause the stud to move toward the body so as to clamp a lip of a rail between said stud and an underside of said body. SUMMARY OF THE INVENTION

[10] The terms "invention," "the invention," "this invention" and "the present invention" used in this patent are intended to refer broadly to all of the subject matter of this patent and the patent claims below. Statements containing these terms should be understood not to limit the subject matter described herein or to limit the meaning or scope of the patent claims below. Embodiments of the invention covered by this patent are defined by the claims below, not this summary. This summary is a high-level overview of various aspects of the invention and introduces some of the concepts that are further described in the Detailed Description section below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification of this patent, any or all drawings and each claim.

[11] According to certain embodiments of the present invention, an aircraft seat fastener comprises a body secured to an aircraft seat, a shank comprising a stud positioned at an end of the shank, and a lip of a rail positioned between the stud and an underside of the body, wherein the body and the shank are connected to one another by a helicoidal connection that is irreversible under axial load, wherein turning of the shank causes the stud to move toward the body so as to clamp the lip of the rail between the stud and the underside of the body.

[12] In some embodiments, the helicoidal connection is formed by a first helicoid that rotates as one with the shank and a second helicoid secured to the body in such a way that as the shank is turned, the first helicoid of the shank presses against the second helicoid of the body so as to cause the stud to move toward the body.

[13] In certain embodiments, an operating device turns the shank. According to some embodiments, the operating device comprises an activation lever mounted with freedom to turn about the shank and allow elastic means providing a connection between said activation lever and the shank.

[14] According to some embodiments, the elastic means is a torsion spring. [15] In some embodiments, the shank comprises a stop piece positioned at a second end of the shank, wherein the stop piece is able to create a torque on the shank allowing an unlocking of the helicoidal connection under an action of the activation lever.

[16] According to some embodiments, the stop piece and the activation lever have toothed contact faces so that the shank is driven only in a direction of unlocking the helicoidal connection.

[17] According to certain embodiments, the fastener comprises an immobilizing system for immobilizing the activation lever.

[18] According to some embodiments, the immobilizing system comprises a catch able to turn with respect to the body and able to collaborate with a radially oriented face of the activation lever.

[19] In some embodiments, the catch has an axis of rotation substantially perpendicular to a direction of elongation of the shank.

[20] According to certain embodiments, the body has a hollow shape constituting a housing.

BRIEF DESCRIPTION OF THE DRAWINGS

[21] The invention will be better understood on reading the following description and examining the Figures that accompany it. These Figures are provided by way of illustration only and are in no way limiting on the invention.

[22] Figures la and lb, already described, show views from above and in perspective of a seat rail on which aircraft seats are intended to be secured via fasteners.

[23] Figure 2 is a schematic depiction of a seat fastener according to the prior art, equipped with a spring system for generating the clamping load on the rail.

[24] Figure 3 is a graphical depiction of the level of energy of an activation lever of the fastener in Figure 2 in an unlocked and in a locked state.

[25] Figure 4 is a functional schematic depiction of an aircraft seat fastener, according to certain embodiments of the present invention.

[26] Figures 5a and 5b show side views of the seat fastener in an unlocked state and in a locked state, respectively, according to certain embodiments of the present invention. [27] Figures 6a and 6b depict views of the immobilizing device that immobilizes the activation lever in a closed state and in an open state, respectively, according to certain embodiments of the present invention.

[28] Identical, similar or analogous elements retain the same references from one Figure to another.

DETAILED DESCRIPTION

[29] The subject matter of embodiments of the present invention is described here with specificity to meet statutory requirements, but this description is not necessarily intended to limit the scope of the claims. The claimed subject matter may be embodied in other ways, may include different elements or steps, and may be used in conjunction with other existing or future technologies. This description should not be interpreted as implying any particular order or arrangement among or between various steps or elements except when the order of individual steps or arrangement of elements is explicitly described.

[30] Figures 4, 5a, 5b, 6a, and 6b show a seat fastener 20 according to certain embodiments of the present invention comprising a body 21 fixed to the seat having an underside 22 intended to bear against a top face of a lip 2 of a seat attachment rail 1.

[31] The fastener 20 also comprises a shank 24 equipped at its bottom end with a stud 25 intended to press against an underside of the lip 2 of the rail 1. The shank 24 also comprises a stop piece 27 situated at its top end. The stop piece 27 includes but is not limited to a nut, fastener, or other mechanical securing device.

[32] The body 21 and the shank 24 are joined together by a helicoidal connection

30. In this particular instance, as can be clearly seen from Figures 5a, 5b, 6a and 6b, the helicoidal connection 28 is formed by a first helicoid 31 connected in rotation to the shank 24 and a second helicoid 32 secured to the body 21 in its bottom part. The helicoids 31, 32 are such that the helicoidal connection 30 is maintained by friction between the helicoids 31, 32 when the connection 30 is locked, making it possible to obtain a connection 30 that is irreversible under the effect of an axial load so that the fastener 20 is practically insensitive to the vibrations generated by the seat.

[33] The fastener 20 further comprises an operating device 34 formed by an activation lever 35 mounted so that it is free to turn about the shank 24, and an elastic means, in this particular instance a torsion spring 36, providing a connection between the lever 35 and the shank 24. For this purpose, the ends of the spring 36 collaborate with axially directed grooves formed in the lever 35 and in the helicoid 31 of the shank, respectively.

[34] It will be noted that the body 21 of hollow shape constitutes a housing of the fastener 20 in which the helicoids 31, 32, as well as the spring 36 and at least part of the shank 24 surrounded by the housing, are positioned.

[35] The locking of the fastener 20 once the stud 25 has been positioned under the lip 2 of the rail 1 and the underside 22 of the body 21 has been pressed firmly against the top face of the lip 2 is described hereinafter. This locking is performed by turning the activation lever 35 which action, through the action of the torsion spring 36, causes the shank 24 and the helicoid 31 connected to the shank 24, to turn. This helicoid 31, pressing against the helicoid 32 of the body 21, causes the shank 24 and therefore the stud 25, to move upward until the latter is in contact with the underside of the lip 2 of the securing rail 1 (cf. Figure 5b).

[36] Once in this position, the shank 24 and the stud 25 are fixed and the turning of the lever 35 builds up torsion in the spring 36. The fastener 20 is then in a locked state. The helicoidal connection 28, of which the helicoids 31, 32 are held in position by friction, is likewise locked.

[37] Once the fastener is locked, irreversibility of the helicoidal connection 28 along the shank 24 and the tension within the torsion spring 36 hold the fastener 20 in place and in contact with the rail 1. It will be noted that the path B2 of the clamping load for keeping the fastener depicted in Figure 5b locked passes only through rigid components: the body 21, the stud 25, the shank 24, the rail 1, and the helicoidal connection 30. In particular, the path B2 of the clamping load does not involve any compressible components of the spring, elastomer, or similar type, as is the case with the prior art configuration of Figure 2. Limiting the clamping load path B2 to rigid components ensures that the locked state of the fastener 20a is a stable state.

[38] In certain embodiments, the lever 35 is immobilized using an immobilizing system 40 that immobilizes the lever 35 once the fastener 20 is locked. To that end, the immobilizing system 40 shown in Figures 6a and 6b comprises a catch 41, which is able to turn with respect to the body 21 about a horizontal axis X' substantially perpendicular to a direction of elongation of the shank 24 corresponding to its axis X. This catch 41 is able to collaborate with a face 42 of the activation lever 35 that is oriented radially with respect to the axis X. The catch 42 then in a closed state restrains the turning of the lever 35, and is clearly visible in Figure 6a. The face 42 is in this instance situated at the base of the lever 35 but as an alternative could be situated near its free end.

[39] When the fastener 20 is being unlocked, the catch 41 is turned so that it disengages from the bearing face 42. The catch 41 is then in an open state which has the effect of freeing the lever 35, as is clearly visible in Figure 6b. The catch 41 may, for example, be moved using a hand tool. The hand tool includes but is not limited to slotted, star, square, hex, torx, or other suitable screw driver head types.

[40] The relaxation of the spring 36 forces the lever 35 toward the stop piece 27 of the shank 24. The turning of the lever 35 causes the turning of the shank 24 through friction or mechanical action between the stop piece 27 and the lever 35. Turning of the shank 24 has the effect of making the helicoid 31 of the shank 24 turn, which tends to cause the shank 24 and therefore the stud 25 to move downward to bring the fastener 20 and the helicoidal connection 28 into an unlocked state. In other words, the stop piece 27 is able to create a torque on the shank 24 that allows the helicoidal connection 28 to be unlocked under the action of the activation lever 35.

[41] If need be, the stop piece 27 and the activation lever 35 may have toothed or otherwise geared contact faces 271, 351 so that the shank 24 is driven only in the direction of unlocking the helicoidal connection 30 (cf. Figure 5b).

[42] It will thus be noted that the catch 41 is thus able, through its angular position, to indicate whether the lock is in the open or closed state.

[43] Alternatively, the torsion spring 36 may be replaced by another elastic means, such as an elastic washer or other type of elastomer.

[44] Different arrangements of the components depicted in the drawings or described above, as well as components and steps not shown or described are possible. Similarly, some features and sub-combinations are useful and may be employed without reference to other features and sub-combinations. Embodiments of the invention have been described for illustrative and not restrictive purposes, and alternative embodiments will become apparent to readers of this patent. Accordingly, the present invention is not limited to the embodiments described above or depicted in the drawings, and various embodiments and modifications may be made without departing from the scope of the claims below.