Heavy duty quick release lock washer and fastening system with such a lock washer.

Abstract

Robust quick-release locking washer and fastening system provided with such a locking washer. The locking washer (12) comprises an annular main part (14) provided with a ring provided on its internal periphery with a plurality of flexible tabs (16) which are curved so that their free ends deviate, on the same side, from a plane formed by the ring and substantially define arcs of the same circle called the locking circle (C1), so as to generate effective locking and obtain a robust locking washer (12), the locking washer (12) also comprising an annular auxiliary part (18) intended to cooperate with the main part (14) to achieve rapid unlocking of the locking washer (12). Figure for abstract: Figure 4.

Description

Title of the invention: Robust quick-release locking washer and fastening system provided with such a locking washer. Technical field

[0001] The present invention relates to a robust quick-release locking washer and a fastening system provided with such a locking washer. State of the art

[0002] The invention relates more particularly to a locking washer (or brake washer) for a screw fastening system intended to fasten at least two parts together. Such a screw fastening system can be used in many fields and in particular in the aeronautical field.

[0003] In the aeronautical field, although not exclusively, such screw fixing systems are, in particular, used to fix covering panels to support structures of an aircraft, for example a transport aircraft.

[0004] In such an application, each panel is secured using a plurality of screw fastening systems to the aircraft support structure, and this in a manner to satisfy both alignment tolerances and installation flexibility.

[0005] Usually, such a fixing system comprises a screw whose shank passes through openings in the panel and the structure to be fixed together. This shank is generally provided, on the panel side, with a head with which a washer is generally associated and on the structure side with a nut, for example a self-locking nut. A locking washer (or brake washer) intended to prevent the screw from turning under the effect of vibrations in particular, can be mounted on the shank longitudinally at the contact zone of the two parts. Generally, such a locking washer comprises a flat annular part provided on its internal periphery with tabs (or teeth) intended to catch in the thread of the screw in the event of vibrations for example.

[0006] When it is desired to separate a panel thus fixed from the support structure, the nuts of the fixing system are removed and the panel is removed. The screws then remain held to the panel by means of the locking washers. However, it frequently happens that locking washers become detached from their screw in such a configuration, due to their low mechanical inertia, and fall into the aircraft, sometimes also the screws.

[0007] There is therefore a need to find a solution to avoid such unwanted separation. Statement of the invention

[0008] The present invention relates to a locking washer which makes it possible to provide a solution to meet the aforementioned need, the locking washer comprising an annular main part provided with a ring provided on its internal periphery with at least two tabs arranged radially inwards, each of said tabs being linked by a first end to the ring and comprising a second opposite end called the free end.

[0009] According to the invention, the legs of the main annular part are flexible and are curved so that their free ends deviate, on the same side, from a plane formed by the ring and substantially define arcs of the same so-called blocking circle.

[0010] Thus, thanks to the invention, by this curved shape of the legs which therefore have a non-right angle relative to the axis of revolution of the ring of the main part (corresponding to the axis of a screw rod on which the locking washer is intended to be mounted), the holding (or locking) is more effective and the separation more difficult, which makes it possible to make the locking washer more robust and to prevent (when it is in a locking position on a screw) its unexpected detachment from the screw and thus to meet the aforementioned need.

[0011] Advantageously, said locking circle of the locking washer has a diameter between two predetermined values, specified below.

[0012] The peripheral edges of the free ends of the legs may have different shapes, in particular flat shapes. However, preferably, said peripheral edges of the free ends of the legs are rounded so as to each fit an arc of said locking circle.

[0013] Furthermore, advantageously, said legs are bent (i.e. curved into the shape of an elbow).

[0014] In a preferred embodiment, the locking washer also comprises an annular auxiliary part cooperating with the main part and arranged coaxially with said main part on the side opposite to that towards which the free ends of the legs are spaced, and the auxiliary part is provided with a ring provided with an internal rim, projecting towards the main part.

[0015] This auxiliary part cooperates with the main part so as to allow simple and rapid release of the locking washer in order to separate it from a screw on which it is mounted, as specified below.

[0016] In a particular embodiment, the rim of the auxiliary part has a conical shape.

[0017] Furthermore, advantageously, in a so-called unlocking position, the main part is pressed against the auxiliary part so that the peripheral edges of the free ends of the flexible legs of the main part form a circle called a circle release of diameter larger than that of the blocking circle and greater than a predetermined value, as specified below.

[0018] The present invention also relates to a fixing system comprising at least one screw comprising a rod provided at one longitudinal end with a head and at the other longitudinal end with a projecting annular edge as well as a locking washer mounted on the rod of the screw.

[0019] According to the invention, the locking washer corresponds to a locking washer such as that described above, and the diameter of the locking circle formed by the legs of the main part of the locking washer is greater than the diameter of the shank of the screw and less than the diameter of the annular edge of the screw.

[0020] Furthermore, advantageously, the diameter of the release circle of the locking washer is greater than the diameter of the projecting annular edge of the screw. Brief description of the figures

[0021] The attached figures will make it clear how the invention can be implemented. In these figures, identical references designate similar elements.

[0022] [Fig.l] is a view, partially in section, of a screw fixing system comprising a locking washer according to a particular embodiment of the invention, the fixing system participating in the fixing of a panel on a support structure.

[0023] [Fig.2] shows, in section, the part of the panel of [Fig.l] provided with the screw of the fixing system and the locking washer in the locking position.

[0024] [Fig. 3] is a figure similar to [Fig. 2] with the washer being brought into the unlocking position and the screw being removed from the panel.

[0025] [Fig.4] is a schematic perspective view of a screw of a fixing system on which a locking washer is mounted according to a particular embodiment, in the locking position.

[0026] [Fig.5] is a figure similar to [Fig.4] with the locking washer in the unlocked position.

[0027] [Fig.6] is a schematic perspective view of a main part of a particular embodiment of a locking washer.

[0028] [Fig.7] is a schematic perspective view of an auxiliary part of a particular embodiment of a locking washer. Detailed description

[0029] A fixing system 1 (screw) such as that shown in a particular embodiment in [Fig.l] is intended to fix together at least two parts 2 and 3 (partially shown in this [Fig.l] in a fixing position).

[0030] This fastening system 1 can be used in many fields and in particular in the aeronautical field. In the aeronautical field, fastening systems 1 are used more particularly for fastening covering panels to support structures of an aircraft, in particular of a transport aircraft.

[0031] Thus, in a preferred application in the aeronautical field, the part 2 is a panel (of wall covering) and the part 3 is a support structure intended to receive this panel 2. This support structure 3 can in particular be integral with an internal part of the fuselage of the aircraft, for example at the level of the hold of the aircraft.

[0032] The following description relates to such a preferred application. In this application, each panel 2 is fixed using a plurality of fixing systems 1 (only one of which is shown in [Fig.l], as well as in Figures 2 and 3) to the support structure 3.

[0033] The fixing system 1 comprises, as shown in Figures 4 and 5, a screw 4 comprising a rod 5 of cylindrical shape and longitudinal axis LL. This rod 5 is at least partially threaded and it is provided at a first longitudinal end 5A with a head 6 and at the second longitudinal end 5B with a radially projecting annular edge 7.

[0034] In the fixing position of [Fig.l], the rod 5 of the screw 1 passes through both an opening 8 (in the form of a right circular cylinder) made in the panel 2 and an opening 9 (in the form of a right circular cylinder) made in the support structure 3. The openings 8 and 9 are aligned and coaxial with an axis XX.

[0035] In this fixing position, the longitudinal axis LL of the rod 5 of the screw 4 is substantially coaxial with the axis XX, with a possibility of play to provide freedom during assembly.

[0036] In the following description: - the terms “internal” and “external” are defined in relation to these axes XX and LL, “internal” corresponding to elements which are located radially approaching these axes XX and LL, and “external” corresponding to elements which are located radially moving away from these axes XX and LL; and - the terms “upper” and “lower” are defined in relation to the direction of an arrow E (figures 4, 6 and 7) which is substantially parallel to the axes XX and LL, “upper” corresponding to elements which are located in the direction of arrow E, and “lower” corresponding to elements which are located in the opposite direction to that of arrow E.

[0037] More particularly, the diameter DI of the opening 9 and the diameter D2 of the opening 8 are larger than the diameter D3 of the rod 5 of the screw 4, as shown in [Fig.l], to ensure clearance and thus provide flexibility during installation.

[0038] In the example of [Fig.l], the diameter D3 of the opening 8 is even greater than the diameter D4 of the head 6 of the screw 4. In this example, the fixing system 1 thus further comprises a washer 10 which rests on a lower face 2B of the panel 2 around the opening 8 and is arranged between the panel 2 and the head 6 of the screw 4.

[0039] The fixing system 1 also comprises a usual nut 11, for example a self-locking anchor nut, which rests against an upper face 3A of the support structure 3 and which is fixed, in the usual manner, to the longitudinal end 5B of the rod 5 of the screw 4.

[0040] Therefore, the panel 2 and the support structure 3 (whose lower face 3B rests on the upper face 2A of the panel 2) are held together by the fixing system 1, via the contact of the washer 10 with the lower face 2B of the panel 2 and the contact of the nut 11 with the upper face 3A of the support structure 3, which are both linked to the screw 4.

[0041] The fixing system 1 also comprises a locking washer 12 (or brake washer) which is mounted on the rod 5 of the screw 4, as shown in Figures 1 to 5.

[0042] The locking washer 12 is intended to prevent the screw 4 from turning under the effect of vibrations in particular. It is mounted on the rod 5 at a contact zone 13 ([Fig.l]) of the panel 2 and the support part 3. A housing 13A ([Fig.2]) made in the panel 2 on the upper face 2A is provided, at the contact zone 13, to receive the locking washer 12.

[0043] As shown in Figures 4 and 5 in particular, the locking washer 12 comprises an annular main part 14. This main part 14 is provided, as shown in [Fig.6], with a ring 15 which is provided, on its radially internal periphery 15A, with a plurality of tabs 16 arranged radially inwards.

[0044] In the example of [Fig.6], the main part 14 comprises four legs 16, and in the example of figures 4 and 5, the main part 14 comprises around ten legs 16.

[0045] Each of the legs 16 of the main part 14 is connected by a first end 16A to the ring 15 and comprises a second end (opposite this first end 16A) called the free end 16B.

[0046] The legs 16 of the main part 14 are flexible. In addition, they are curved so that their free ends 16B deviate, on the same side 19, relative to a plane P formed by the ring 15 in the direction of the arrow E ([Fig.6]). The peripheral edges 17 (i.e. the internal edges) of the free ends 16B of the legs 16 substantially define arcs of a single circle called the locking circle CL. The peripheral edges 17 are not present over the entire locking circle. Cl, but only form circular arcs, next to each other, along the blocking circle Cl.

[0047] The locking circle C1 has a diameter DA (figures 4 and 6) slightly greater than the diameter D3 ([Fig.l]) of the threaded rod 5 of the screw 4 and less than the diameter D5 ([Fig.3]) of the annular edge 7 of the screw 4, which prevents the locking ring 12 from being released via the annular edge 7 (projecting radially outwards) in the configuration of [Fig.2] specified below.

[0048] In a preferred embodiment, the tabs 16 are distributed uniformly around the periphery 15A of the ring 15. In addition, preferably, the tabs 16 of the main part 14 of the locking washer 12 are identical. It is, however, also conceivable that the tabs 16 can have different widths, but with identical lengths so that the peripheral edges 17 of the free ends 16B of these tabs 16 are all located at the locking circle C1.

[0049] In the context of the present invention, the peripheral edges 17 of the free ends 16B of the legs 16 may have different shapes, in particular flat shapes. However, preferably, said peripheral edges 17 of the free ends 16B of the legs 16 are rounded (in an arc of a circle) so as to each fit an arc of said locking circle C1, as shown in [Fig.6].

[0050] In the context of the present invention, the legs 16 may have different curved shapes. However, in a preferred embodiment, the legs 16 are bent, that is to say they are curved in the form of an elbow and therefore each comprise two substantially rectilinear sections, having different directions and linked together at the elbow.

[0051] By this curved shape (in the direction of arrow E) of the legs 16, with a non-right angle relative to the axis of revolution of the ring 15 of the main part 14 (corresponding to the longitudinal axis LL of the rod 5 of the screw 4 on which the locking washer 12 is mounted), which allows them to grip better, the blocking or holding of the locking washer 12 on the screw 4 is more effective than if the legs (or teeth) were located in the plane of the ring and thus presented a right angle relative to the axis of revolution of the ring. This curved shape of the legs 16 makes it possible to prevent unexpected detachments of the locking washer 12 (in the configuration of [Fig.2]) and thus to obtain a more robust locking washer 12.

[0052] Also, to be able to more easily remove the locking washer 12 from a screw 4 on which it is mounted, the locking washer 12 comprises, in addition to the main part 14, an annular auxiliary part 18. This auxiliary part 18 is intended to cooperate with the main part 14 to unlock the latter, in order to be able to remove the locking washer 12 from the screw 4.

[0053] The auxiliary part 18 is arranged coaxially with the main part 14 on the side 20 ([Fig.6]) opposite the side 19 towards which the free ends 16B of the legs 16 are spaced.

[0054] The auxiliary part 18 is provided, as shown in [Fig.7], with a ring 22 provided with an internal rim 23, of conical shape, projecting towards the main part 14, in the direction of the arrow E.

[0055] This auxiliary part 18 allows simple and rapid unlocking of the main part 14 and therefore of the locking washer 12, as specified below.

[0056] In a particular embodiment, the rim 23 of the auxiliary part 18 has a triangular shape in cross section.

[0057] The locking washer 12 provided with the main part 14 and the auxiliary part 18 can in particular take two positions, a locking position and an unlocking position, as illustrated, respectively, in FIGS. 4 and 5.

[0058] In the locking position of [Fig.4], the auxiliary part 18 does not act on the main part 14 which takes the form of the example of [Fig.6] with its legs 16 which define the locking circle CL

[0059] The locking circle C1 has a diameter DA (figures 4 and 6) slightly greater than the diameter D3 ([Fig.l]) of the threaded rod 5 of the screw 4 and less than the diameter D5 ([Fig.3]) of the annular edge 7 of the screw. Thus, in this locking position, the locking washer 12 is held on the rod 5 of the screw 4, as shown in [Fig.4].

[0060] The locking washer 12 allows, thanks to the curved shapes of the legs 16 of the main part 14, to achieve effective attachment against the threaded rod 5 of the screw 4 to implement its functions as a locking washer (or brake washer).

[0061] In addition, its legs 16 make it possible to hold the locking washer 12 securely on the rod 5 of the screw 4 in the locking position shown in Figures 2 and 4 and prevent it from becoming detached from the latter.

[0062] Furthermore, in the unlocking position shown in Figures 3 and 5, the main part 14 is pressed against the auxiliary part 18 (which is supported against the upper face 2A of the panel 2 (as visible in [Fig.3])) so that the peripheral ends 17 of the free ends 16B of the tabs 16 of the main part 14 form a circle called the unlocking circle C2. The unlocking circle C2 has a diameter DB larger than the diameter DA of the locking circle CL. In addition, this diameter DB is also greater than the diameter D4 of the annular edge 7 of the screw 4.

[0063] Thus, it is possible to separate the screw 4 and the locking washer 12. To allow the locking washer 12 to be easily removed from the rod 5 of the screw 4, the locking washer 12 is brought into the unlocked position of Figures 3 and 5.

[0064] The different positions and configurations of the locking washer 12 and of the fixing system 1, as shown respectively in FIGS. 1 to 3, are presented in more detail below.

[0065] In the configuration of [Fig. 1], the panel 2 is fixed using a plurality of fixing systems 1 (only one of which is shown in this [Fig.l]) to the support structure 3. To do this, the washer 10 associated with the head 6 of the screw 4 is in contact with the lower face 2B of the panel 2 and the nut 11 which is in contact with the upper face 3A of the support structure 3, is made integral with the rod 5 of the screw 4. In addition, the locking washer 12 is in place on the rod 5 of the screw 4 and is arranged in the housing 13A at the interface 13 of the panel 2 and the support structure 3.

[0066] In the configuration of [Fig.2], compared to that of [Fig.l], the nut 11 has been removed and the panel 2 (with the screw 4 and the locking washer 12) separated from the structural element 3. The locking washer 12 which is in its locking position remains linked to the screw 4 and the assembly therefore remains integral with the panel 2.

[0067] From the configuration of [Fig.2], to separate the locking washer 12 from the rod 5 of the screw 4, a separation method is implemented.

[0068] This separation process comprises the following operations or steps: - a first step, during which pressure is exerted on the upper face 14A ([Fig.6]) of the main part 14, preferably at the level of the ring 15 of this main part 14, as illustrated by arrows H in [Fig.3] so that the latter is pressed against the upper face 18A ([Fig.7]) of the auxiliary part 18, the lower face 18B of the auxiliary part 18 being in abutment against the upper face 2A of the panel 2. By this pressure and due to the flexibility of the tabs 16, the lower face 14B of the main part 14 will come into contact with the upper face 18A of the auxiliary part 18 and takes the shape of the face 18A. Thanks to the conical annular rim 23, the pressing of the legs 16 against the face 14B will cause the peripheral edges 17 of the legs 16 to move radially outwards and thus increase the circle formed by the peripheral edges 17.When the main part 14 is completely pressed against the auxiliary part 18, the peripheral edges 17 define the unlocking circle C2. The diameter DB of this unlocking circle C2 is of course greater than the diameter DA of the locking circle C1, and also than the diameter D5 ([Fig.3]) of the annular edge 7 of the screw 4; and . - a second step, during which, while maintaining the aforementioned pressure illustrated by the arrows H so that the peripheral edges 17 of the free ends 16B of the legs 16 form the unlocking circle C2, the screw 4 is acted upon to remove it from the locking washer 12 as illustrated by an arrow I (in the opposite direction to that of the arrow E), and thus detach it from the panel 2.

[0069] In a preferred embodiment, the main part 14 and the auxiliary part 18 are formed, in particular by an appropriate size of the rim 23 and the length of the legs 16, so that the internal contour 23A of the rim 23 has a diameter DB ([Fig.7]) equal to the diameter of the unlocking circle C2 in the unlocking position.

[0070] In a first embodiment, the first aforementioned step is implemented by an operator, by pressing or pushing with some of his fingers, at least in two different places, on the ring 15 of the main part 14 of the locking washer 12, as illustrated by the arrows H in [Fig.3].

[0071] Furthermore, in a second embodiment, the aforementioned first step is implemented using a tool (not shown) which makes it possible to generate the pressure illustrated by the arrows H on the ring 15 of the main part 14.

[0072] As for the second step, it is implemented by an operator who pulls on the screw 4 in the direction illustrated by the arrow I in [Fig.3], for example directly with a hand or using a tool, in particular a gripping tool.

[0073] The locking washer 12 and also the fixing system 1 which comprises it, as described above, have several advantages. In particular, they allow: - to generate a blocking or holding of the locking washer 12 on the screw 4, which is particularly effective; - to thus obtain a locking washer 12 which is robust; and - to implement a simple and rapid release of the locking washer 12, and thus to be able to achieve a rapid and effective separation of the locking washer 12 from the screw 4.

Claims

Claims

1. Locking washer comprising an annular main part (14) provided with a ring (15) provided on its internal periphery (15A) with at least two tabs (16) arranged radially inwards, each of said tabs (16) being connected by a first end (16A) to the ring (15) and comprising a second opposite end (16) called the free end, said tabs (16) being flexible and being curved so that their free ends (16B) deviate, on the same side, from a plane (P) formed by the ring (15) and substantially define arcs of the same circle called the locking circle (Cl), characterized in that it comprises an annular auxiliary part (18) cooperating with the main part (14) and arranged coaxially with said main part (14) on the side opposite to that towards which the free ends (16B) of the tabs (16) are spaced, and in that the auxiliary part (18) is provided with a ring (22) provided with an internal rim (23),projecting towards the main room (14).,

2. Locking washer according to claim 1, characterized in that said locking circle (Cl) has a diameter (DA) between two predetermined values (D3, D5).

3. Locking washer according to claim 2, characterized in that the peripheral edges (17) of the free ends (16B) of the legs (16) are rounded so as to each fit an arc of said locking circle (Cl).

4. Locking washer according to any one of the preceding claims, characterized in that said legs (16) are bent.

5. Locking washer according to any one of the preceding claims, characterized in that the rim (23) has a conical shape.

6. Locking washer according to any one of the preceding claims, characterized in that, in a so-called unlocking position, the main part (12) is pressed against the auxiliary part (18) so that the peripheral edges (17) of the free ends (16B) of the flexible tabs (16) of the main part (14) form a circle called the unlocking circle (C2) with a diameter (DB) larger than that (DA) of the locking circle (Cl) and greater than a predetermined value (D5).

7. Fastening system comprising at least one screw (4) comprising a rod (5) provided at one longitudinal end (5A) with a head (6) and at the other longitudinal end (5B) with a projecting annular edge (7) as well as a locking washer (12) mounted on the rod (5) of the screw (4), characterized in that the locking washer (12) corresponds to a locking washer according to any one of claims 1 to 6, and in that the diameter (DA) of the locking circle (Cl) formed by the tabs (16) of the main part (14) of the locking washer (12) is greater than the diameter (D3) of the rod (5) of the screw (4) and less than the diameter (D5) of the annular edge (7) of the screw (4).

8. Fastening system according to claim 7 comprising a locking washer (12) according to claim 6, characterized in that the diameter (DB) of the unlocking circle (C2) is greater than the diameter (D5) of the annular edge (7) of the screw (4).

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