System and method for securing a wall

Abstract

A system (10) for securing a wall (20), such as a wall (20) of a luminaire head housing (1000), comprising an opening (O) with a non-rotational-symmetric surface (21), said system (10) comprising: a threaded rod (100) configured to extend through the opening (O), said threaded rod (100) comprising a non-rotational-symmetric surface (101) configured to match the non-rotational-symmetric surface (21) oO f the opening (O); a nut (200) configured to be fixed to the threaded rod (100) and to be secured to the wall (20); and a washer (300) configured to be secured to the threaded rod (100) and to the nut (200); wherein the nut (200) is arranged between the washer (300) and the wall (20); wherein a central portion (310) of the washer (300) is configured to engage with the threaded rod (100) so as to block a rotation and a translation of the washer (300) with respect to the threaded rod (100); and wherein a peripheral portion (320) of the washer (300) is configured to be folded and to abut a peripheral portion (220) of the nut (200) so as to secure the washer (300) to the nut (200).

Description

[0001] SYSTEM AND METHOD FOR SECURING A WALL

[0002] FIELD OF INVENTION

[0003] The present invention relates to systems and methods. Particular embodiments relate to a system and a method for securing a wall, such as a wall of a luminaire head housing.

[0004] BACKGROUND

[0005] Generally, in various fields of mechanics wherein mechanical parts are secured to one another, such as in luminaire heads or the like, conventional securement systems comprising a threaded rod and an associated nut are used. Such conventional securement systems may be used for securing a wall, such as a wall of a luminaire head housing or the like, and more generally any wall, plate, or sheet.

[0006] A current problem occurring in said various fields of mechanics, and more in particular in the industry of outdoor luminaire heads, is that vibration of the mechanical parts that are secured to one another, such as the above-mentioned threaded rod, nut, and wall, may cause a loss of torque, i.e., a loosening of the nut with respect to the wall. Said loss of torque, or loosening, of the nut may have severe consequences depending on the specific application in the various fields of mechanics.

[0007] In order to avoid the above-mentioned loss of torque, or loosening, of the nut with respect to the wall, an improved system for securing a wall is needed.

[0008] SUMMARY

[0009] An object of embodiments of the invention is to provide a system for securing a wall, such as a wall of a luminaire head housing. More in particular, embodiments of the invention aim at providing a system for securing a wall, such as a wall of a luminaire head housing, which prevents a loss of torque, i.e., a loosening of the nut with respect to the wall that may occur e.g. during vibration of the wall.

[0010] Further, embodiments of the invention provide a washer for securing a threaded rod and a nut to a wall, such as a wall of a luminaire head housing, and a method for securing a wall, such as a wall of a luminaire head housing. Said washer and said method prevent a loss of torque, i.e., a loosening of the nut with respect to the wall that may occur e.g. during vibration of the wall. According to a first aspect of the invention, there is provided a system for securing a wall, such as a wall of a luminaire head housing, comprising an opening with a non-rotational-symmetric surface, said system comprising a threaded rod, a nut, and a washer. The threaded rod is configured to extend through the opening, and comprises a non-rotational-symmetric surface configured to match the non- rotational-symmetric surface of the opening. The nut is configured to be fixed to the threaded rod and to be secured to the wall. The washer is configured to be secured to the threaded rod and to the nut. The nut is arranged between the washer and the wall. A central portion of the washer is configured to engage with the threaded rod so as to block a rotation and a translation of the washer with respect to the threaded rod. A peripheral portion of the washer is configured to be folded and to abut a peripheral portion of the nut so as to secure the washer to the nut.

[0011] In the context of the invention, it is meant by “washer” an orifice flange configured to surround a threaded rod, the threaded rod extending in the orifice, or through-hole, of the flange. A peripheral portion of said orifice flange is deformable so as to abut a peripheral portion of the nut. Opposite surfaces of the orifice flange may be flat, but need not be flat.

[0012] Embodiments of the invention are based inter alia on the insight that, in conventional systems for securing a wall using a threaded rod and one or more nuts, a loss of torque, i.e., a loosening of the nut with respect to the wall may occur e.g. during vibration of the wall.

[0013] A first solution consisting in using two adjacent nuts, one above the other, in connection with a threaded rod encounters the same problem, as the first nut, which is arranged between the wall and the second nut, may not be firmly secured to the wall. Thus, according to said first solution, the first nut may rotate with respect to the wall and to the second nut, thereby in turn incurring a loss of torque of the second nut with respect to the wall.

[0014] A second solution consisting in arranging a washer between the nut and the wall may prevent a peripheral portion of the washer to be folded towards the nut, especially in applications where little space is available and wherein proper access to the washer cannot be guaranteed, such as the inside of a luminaire head housing. Thus, according to said second solution, the washer may not be properly secured to the nut, thereby enabling a rotation of the nut with respect to the washer and incurring a loss of torque of the nut with respect to the wall. In addition, according to said second solution, a position of the washer with respect to the threaded rod and the nut must be adjusted in accordance with a relative orientation of the nut with respect to the threaded rod, which is impractical. By contrast, in the system of embodiments of the invention, the matching non-rotational-symmetric surfaces of the opening and the threaded rod, respectively, prevent a rotation of the threaded rod with respect to the wall. In addition, the central portion of the washer prevents a rotation and a translation of the washer with respect to the threaded rod. Moreover, the peripheral portion of the washer prevents a rotation of the nut with respect to the washer. Thus, since a rotation of the nut with respect to the washer, a rotation of the washer with respect to the threaded rod, and a rotation of the threaded rod with respect to the wall are prevented, the overall effect is that a rotation of the nut with respect to the wall is prevented. Therefore, the system of embodiments of the invention prevents a loss of torque of the nut with respect to the wall that may occur e.g. during vibration of the wall.

[0015] Further, in the system of embodiments of the invention, the nut is arranged between the washer and the wall, and the peripheral portion of the washer is configured to be folded and to abut a peripheral portion of the nut. Thus, the washer of embodiments of the invention may be properly secured to the nut, thereby preventing a rotation of the nut with respect to the washer and thus a loss of torque of the nut with respect to the wall, even in applications where little space is available and wherein proper access to the washer cannot be guaranteed, such as the inside of a luminaire head housing.

[0016] Furthermore, in the system of embodiments of the invention, the central portion of the washer is configured to engage with the threaded rod not only to block a rotation of the washer with respect to the threaded rod, but also to block a translation of the washer with respect to the threaded rod. This improves the tightening of the washer with respect to the threaded rod.

[0017] Finally, contrary to the above-mentioned second solution, in the system of embodiments of the invention, the washer may be secured to the threaded rod and to the nut irrespective of a relative orientation of the nut with respect to the threaded rod, thereby facilitating the securement of the wall.

[0018] In some embodiments, the wall may be part of a luminaire head housing. The luminaire head housing may comprise any one or more of the following electrical / electronic components: a light source, a light source driving means, a light source dimming means, surge protection circuitry, electrostatic discharge protection circuitry, a fuse, a metering circuitry, a driving and / or control circuitry for any electrical components of the light source.

[0019] In some other embodiments, the wall may be part of a housing configured to accommodate a functional unit different from a light source, i.e., the wall may be part of a housing which is different from a luminaire head housing. The functional unit may comprise any one or more of the following: an image sensing means such as a camera, a communication means such as an antenna, a sensing means such as an air quality sensor or a pollution sensor or a visibility sensor or a smoke sensor or a sound sensor (microphone) or a radio-frequency, RF, sensor or a movement sensor or a temperature sensor, a loudspeaker, a light projecting means such as a projector, a display, a laser device, a radar device, a light emitting device such as an ultraviolet (UV) light or an infrared (IR) light or a light for light fidelity (Li-Fi) communication, or a spraying / sanitizing device.

[0020] In yet some other embodiments, the wall may be a plate or a sheet, e.g., a plate or a sheet of metal or of other suitable material. The sheet may be substantially flat at least at a portion surround the opening. The sheet may have a constant thickness at least at the portion surrounding the opening. In other words, the wall according to said yet other embodiments need not be part of a luminaire head housing or of a housing configured to accommodate a functional unit different from a light source.

[0021] In view of the above, the system of embodiments of the invention is not limited to a particular application, such as a luminaire head or a functional head comprising a functional unit different from a light source. Indeed, according to embodiments of the invention, the wall may correspond to any wall, or any plate, or any sheet that may be secured to a system comprising a threaded rod, a nut, and a washer as defined above. Thus, the technical field of the invention is not limited to luminaire heads or the like but extends to various fields of mechanics wherein mechanical parts are secured to one another. Said various fields of mechanics may include automotive industry, aeronautical / aerospatial industry, naval industry, civil engineering, etc. Said list is not exhaustive.

[0022] Exemplary embodiments relate to a system for securing a wall of a luminaire head housing for an outdoor luminaire. By outdoor luminaire, it is meant luminaires which are installed on roads, tunnels, industrial plants, stadiums, airports, harbors, rail stations, campuses, parks, cycle paths, pedestrian paths or in pedestrian zones, for example, and which can be used notably for the lighting of an outdoor area, such as roads and residential areas in the public domain, private parking areas, access roads to private building infrastructures, warehouses, industry halls, etc.

[0023] According to an exemplary embodiment, the threaded rod is a hollow rod. In embodiments wherein the wall is part of a luminaire head housing, or of a housing configured to accommodate a functional unit different from a light source, the hollow threaded rod may be configured to accommodate at least one cable, such as an electric cable, extending from outside the luminaire head housing or other housing accommodating another kind of functional unit, to the inside of the luminaire head housing or the other housing. In other embodiments, e.g., wherein the wall is the above-mentioned plate or sheet, the threaded rod may be plain, i.e., not hollow. According to a preferred embodiment, the central portion of the washer comprises a through-hole comprising a non-rotational-symmetric surface configured to match the non-rotational-symmetric surface of the threaded rod so as to block the rotation of the washer with respect to the threaded rod.

[0024] In this way, since the rotation of the washer with respect to the threaded rod is prevented thanks to the central portion of the washer, and since a rotation of the nut with respect to the washer is also prevented thanks to the peripheral portion of the washer, a rotation of the nut with respect to the threaded rod is prevented, thereby preventing a loss of torque of the nut with respect to the wall.

[0025] According to a preferred embodiment, the non-rotational-symmetric surface of the opening and the non-rotational-symmetric surface of the threaded rod are flat surfaces.

[0026] It should be clear to the skilled person that any other shape of the non-rotational-symmetric surface of the opening and the non-rotational-symmetric surface of the threaded rod may be envisaged, said shape enabling to avoid a rotation of the threaded rod with respect to the wall.

[0027] In an alternative embodiment, the non-rotational-symmetric surface of the threaded rod may correspond to a recessed portion, i.e., a channel or a groove, extending along the threaded rod, and the non-rotational-symmetric surface of the opening may correspond to a protrusion configured to match the recessed portion of the threaded rod.

[0028] Vice versa, in yet an alternative embodiment, the non-rotational-symmetric surface of the opening may correspond to a recessed portion, i.e., a channel or a groove, extending along a thickness of the wall at the opening, and the non-rotational-symmetric surface of the threaded rod may correspond to a protrusion configured to match the recessed portion of the opening.

[0029] According to an exemplary embodiment, the opening further comprises a rotational-symmetric, i.e., cylindrical, surface, connecting the non-rotational-symmetric surface. Accordingly, the threaded rod may further comprise a rotational-symmetric, i.e., cylindrical, surface, connecting the non-rotational- symmetric surface. In the above-mentioned alternative embodiments, the cylindrical surface of the threaded rod may be provided with the above-mentioned recessed portion, i.e., the channel or the groove, to define the non-rotational-symmetric surface, and the cylindrical surface of the opening may be provided with the above-mentioned protrusion to define the non-rotational-symmetric surface, or vice versa. According to a preferred embodiment, the non-rotational-symmetric surface of the washer is a flat surface.

[0030] It should be clear to the skilled person that any other shape of the non-rotational-symmetric surface of the threaded rod and the non-rotational-symmetric surface of the washer may be envisaged, said shape enabling to avoid a rotation of the washer with respect to the threaded rod.

[0031] In an alternative embodiment, the non-rotational-symmetric surface of the threaded rod may correspond to a recessed portion, i.e., a channel or a groove, extending along the threaded rod, and the non-rotational-symmetric surface of the washer may correspond to a protrusion configured to match the recessed portion of the threaded rod.

[0032] Vice versa, in yet an alternative embodiment, the non-rotational-symmetric surface of the washer may correspond to a recessed portion, i.e., a channel or a groove, extending along a thickness of the washer at the through-hole, and the non-rotational-symmetric surface of the threaded rod may correspond to a protrusion configured to match the recessed portion of the washer.

[0033] According to an exemplary embodiment, the washer further comprises a rotational-symmetric, i.e., cylindrical, surface, connecting the non-rotational-symmetric surface. In the above-mentioned alternative embodiments, the cylindrical surface of the threaded rod may be provided with the above- mentioned recessed portion to define the non-rotational-symmetric surface, and the cylindrical surface of the washer may be provided with the above-mentioned protrusion to define the non- rotational-symmetric surface, or vice versa.

[0034] According to a preferred embodiment, the central portion of the washer comprises a plurality of teeth protruding from an inner surface of the central portion, said plurality of teeth being configured to engage with the thread of the threaded rod so as to block the translation of the washer with respect to the threaded rod.

[0035] In this way, the plurality of teeth may be interlocked between two adjacent lines of the thread of the threaded rod so as to block the translation of the washer with respect to the threaded rod.

[0036] In some embodiments, the plurality of teeth may be configured to be oriented towards the nut prior to engaging with the thread of the threaded rod. During engagement with the thread of the threaded rod, the plurality of teeth may be folded in an opposite direction due to the contact with the thread. Depending on the plasticity or elasticity of the plurality of teeth, which in turn may depend on a material used for the plurality of teeth and / or on the dimensions (thickness, radial length, width) of the plurality of teeth, the plurality of teeth may, after being folded during engagement with the thread of the threaded rod, be oriented in a direction included in a plane defined by the washer, or be oriented away from the nut.

[0037] According to a preferred embodiment, the plurality of teeth is integrally formed with the washer, and the central portion of the washer is provided with a cut on either side of each tooth, thereby defining the plurality of teeth.

[0038] According to a preferred embodiment, the plurality of teeth is distributed along the inner surface of the central portion. Preferably, the plurality of teeth is arranged symmetrically with respect to a center of the through-hole.

[0039] In this way, a uniform securement of the washer to the threaded rod is enabled, thereby preventing the translation of the washer with respect to the threaded rod in an improved manner.

[0040] According to a preferred embodiment, the through-hole further comprises a plurality of curved, preferably circular, surfaces connecting the non-rotational-symmetric surface of the through-hole, and respective edges of the plurality of teeth form part of the plurality of curved surfaces.

[0041] According to a preferred embodiment, the respective edges of the plurality of teeth protrude from the remainder of the plurality of curved surfaces so as to engage with the thread of the threaded rod.

[0042] In this way, the plurality of teeth may be interlocked between two adjacent lines of the thread of the threaded rod so as to block the translation of the washer with respect to the threaded rod, whilst the remainder of the plurality of curved surfaces of the through-hole may not engage with the threaded rod.

[0043] According to a preferred embodiment, a thickness of the plurality of teeth is smaller than the pitch of the thread of the threaded rod. Preferably, the thickness of the plurality of teeth is between 10 % and 75 % of said pitch.

[0044] In this way, the plurality of teeth may be interlocked between two adjacent lines of the thread, which adjacent lines are by definition separated by a distance equal to the pitch of the thread, of the threaded rod so as to block the translation of the washer with respect to the threaded rod. The above-mentioned range of thickness of the plurality of teeth confers sufficient elasticity and yet robustness to the teeth. According to a preferred embodiment, the central portion of the washer comprises at least three teeth, preferably at least four teeth. Preferably, said at least three teeth or said at least four teeth are arranged symmetrically with respect to a center of the through-hole.

[0045] According to a preferred embodiment, the peripheral portion of the washer comprises a plurality of protrusions from an outer surface of the peripheral portion, said plurality of protrusions being configured to be folded and each to abut a corresponding area of the peripheral portion of the nut so as to secure the washer to the nut. The plurality of protrusions may correspond to a plurality of protruding wings which protrude from the outer surface of the peripheral portion of the washer.

[0046] In this way, a rotation of the nut with respect to the washer and also with respect to the threaded rod is prevented, thereby in turn preventing a loss of torque of the nut with respect to the wall.

[0047] In other embodiments, substantially the entire peripheral portion of the washer may be folded and abut a peripheral portion of the nut so as to secure the washer to the nut.

[0048] According to a preferred embodiment, the peripheral portion of the nut comprises a plurality of flat surfaces. Each protrusion may abut a corresponding flat surface of the peripheral portion of the nut. Alternatively, one protrusion may abut an area around an edge of the peripheral portion of the nut, and another protrusion may abut a flat surface of the peripheral portion of the nut. Yet alternatively, each protrusion may abut a corresponding area around an edge of the peripheral portion of the nut.

[0049] In other words, depending on the relative orientation of the nut with respect to the washer, each protrusion may partly abut a flat surface and partly abut an edge of the peripheral portion of the nut. However, irrespective of the relative orientation of the nut with respect to the washer, the plurality of protrusions may be configured to be folded and each to abut a corresponding area of the peripheral portion of the nut so as to secure the washer to the nut.

[0050] According to a preferred embodiment, the plurality of protrusions is integrally formed with the washer, and the peripheral portion of the washer is provided with a cut on either side of each protrusion, thereby defining the plurality of protrusions.

[0051] According to a preferred embodiment, wherein the plurality of protrusions is distributed along the outer surface of the peripheral portion. Preferably, the plurality of protrusions is arranged symmetrically with respect to a center of the through-hole. In this way, a uniform securement of the washer to the nut is enabled, thereby preventing the rotation of the nut with respect to the washer in an improved manner.

[0052] According to a preferred embodiment, the peripheral portion of the washer comprises a plurality of flat surfaces, and each protrusion is connected to a corresponding flat surface.

[0053] According to a preferred embodiment, the peripheral portion of the washer further comprises a plurality of curved, preferably circular, surfaces, each respectively connecting two of the plurality of flat surfaces, and each tooth is facing away a corresponding curved surface.

[0054] According to a preferred embodiment, each protrusion is provided with one or more cuts so as to divide each protrusion into two or more respective portions.

[0055] In this way, the washer may be secured to the threaded rod and to the nut irrespective of a relative orientation of the nut with respect to the threaded rod, thereby facilitating the securement of the wall. Depending on the relative orientation of the nut with respect to the washer, the two or more respective portions of each protrusion may abut the same flat surface of the peripheral portion of the nut, or may abut two corresponding areas around an edge of the peripheral portion of the nut. However, irrespective of the relative orientation of the nut with respect to the washer, the two or more respective portions of each protrusion may be configured to be folded and each to abut a corresponding area of the peripheral portion of the nut so as to secure the washer to the nut.

[0056] According to a preferred embodiment, a radial length, i.e., a length of each protrusion measured radially from the center of the through-hole, of each protrusion is substantially equal to a height of the peripheral portion of the nut.

[0057] In this way, a securement of the washer to the nut is improved, thereby preventing the rotation of the nut with respect to the washer in an improved manner.

[0058] According to a preferred embodiment, the one or more cuts extend along substantially the entire radial length of each protrusion.

[0059] According to a preferred embodiment, the peripheral portion of the washer comprises at least three protrusions, preferably at least four protrusions. Preferably, said at least three protrusions or said at least four protrusions are arranged symmetrically with respect to a center of the through-hole. According to a preferred embodiment, a thickness of the washer is between 0.5 mm and 2 mm, preferably between 1 mm and 1.5 mm.

[0060] Geometric properties of the washer, such as the thickness of the washer, may vary depending on the application of the washer, i.e., depending on the technical field in which the wall, the threaded rod, and the nut are used in connection with the washer.

[0061] Other properties of the washer may be adapted to the specific application of the washer. For example, a weight and / or a material of the washer may be adapted. A material of the washer may be an alloy such as steel, e.g. stainless steel. The washer may be coated (galvanized) e.g. with zinc on both sides of the washer. A rigidity / plasticity or elasticity of the washer may be adapted to the specific application. The choice of thickness and / or material may influence the rigidity / plasticity or elasticity of the washer. In some examples, a material of the washer may be an alloy, such as steel, e.g. stainless steel, having an increased elasticity in order to increase the tightening range of the washer, compared to an alloy commonly found in the market. Such an alloy may thus have a function similar to that of a spring, and may be referred to as a “spring” alloy, e.g., “spring” stainless steel. A rigidity / plasticity or elasticity of the plurality of teeth may be adapted to the specific application. For example, a thickness and / or a radial length and / or a width of the plurality of teeth may be adapted to the specific application. In some examples, a material of the plurality of teeth may be the above-described material of the washer, i.e., the “spring” alloy, e.g., “spring” stainless steel.

[0062] In embodiments wherein the wall is part of a luminaire head housing, a nut with an external dimension between 40 mm and 50 mm, e.g. 46 mm, and a height between 5 mm and 15 mm, e.g. 10 mm, may be used in connection with a threaded rod and a washer.

[0063] Dimensions of the washer may be adapted to the specific application of the washer. For example, a thickness of the washer may be adapted, varying between 0.5 mm and 2 mm, preferably between 1 mm and 1.5 mm. In some examples, dimensions of the washer may be adapted to threaded rods having a large diameter, to avoid that the peripheral portion of the washer be overly folded onto the peripheral portion of the nut so as to correctly secure the washer to the nut. In some other examples, dimensions of the washer may be adapted to threaded rods having a small diameter, to ensure that the peripheral portion of the washer abut the peripheral portion of the nut over a sufficient contact area so as to correctly secure the washer to the nut. Dimensions of the central portion of the washer may be adapted to the type of threaded rod. For example, a diameter of the through-hole may be adapted to the diameter of the threaded rod which is selected for a specific application.

[0064] Dimensions of the peripheral portion of the washer may be adapted to the type of nut. For example, a radial length and / or a width of the peripheral portion of the washer may be adapted to the external dimensions of the nut which is selected for a specific application.

[0065] According to a preferred embodiment, the peripheral portion of the washer is provided with a plurality of holes at one or more folding areas of the peripheral portion.

[0066] In other words, the peripheral portion of the washer may be perforated at one or more folding areas of the peripheral portion. In some embodiments, the peripheral portion of the washer may be perforated at folding areas of the peripheral portion corresponding to the arrangement of the plurality of protrusions. In other embodiments, substantially the entire peripheral portion of the washer may be folded and abut a peripheral portion of the nut so as to secure the washer to the nut. In said other embodiments, substantially the entire peripheral portion of the washer may be perforated so as to fold a substantial entirety of the peripheral portion.

[0067] According to a preferred embodiment, the threaded rod comprises a portion, preferably integrally formed therewith, configured to abut the wall at a side opposite to the nut, the wall being secured between the nut and said portion of the threaded rod. Preferably, a seal is arranged between said portion of the threaded rod and said side of the wall opposite to the nut.

[0068] According to a preferred embodiment, a portion of the threaded rod at a side opposite the nut may have a rotational symmetry, i.e., may be cylindrical. Accordingly, the portion of the threaded rod may have a rotational symmetry, i.e., may be cylindrical, and the seal may be an O-ring, i.e., may have a toroidal shape. By contrast, a portion of the threaded rod at a side in contact with the nut has a non-rotational symmetry, i.e., comprises the above-mentioned non-rotational-symmetric surface. The threaded rod may be threaded only on the portion of the threaded rod at the side in contact with the nut.

[0069] According to a preferred embodiment, the wall is part of the luminaire head housing, said luminaire head housing being configured to be suspended to a luminaire pole. In this way, embodiments of the invention aim at providing a system for securing a wall of a suspended luminaire head housing, which prevents a loss of torque, i.e., a loosening of the nut with respect to the wall that may occur e.g. during vibration of the suspended luminaire head housing. For example, suspended luminaire heads sold in the European Union must pass the vibration requirements under the 0.5g IEC 60068-2-6 / -64 international standard of the International Electrotechnical Commission (IEC). The system according to embodiments of the invention enables said suspended luminaire heads to pass the above vibration requirements.

[0070] According to a preferred embodiment, the threaded rod is configured to be fixed to the luminaire pole at an end opposite the luminaire head housing, so as to suspend the luminaire head housing.

[0071] According to a preferred embodiment, the end of the threaded rod (male) opposite the luminaire head housing is configured to match a threaded bore (female) of the luminaire pole to fix the threaded rod to the luminaire pole. In an alternative embodiment, the end of the threaded rod opposite the luminaire head housing may be provided with a threaded bore (female) configured to match a threaded rod (male) of the luminaire pole to fix the threaded rod to the luminaire pole.

[0072] According to a preferred embodiment, the wall comprises a protruding portion surrounding the opening and defining a cavity of the luminaire head housing. A peripheral outer surface of the protruding portion may be cylindrical. A peripheral inner surface of the cavity may be substantially cylindrical, and may comprise a plurality of reinforcing ribs. The threaded rod, the nut, and the washer may extend in the cavity.

[0073] In this way, the washer may be properly secured to the nut, thereby preventing a rotation of the nut with respect to the washer and thus a loss of torque of the nut with respect to the wall, even in applications where little space is available and wherein proper access to the washer cannot be guaranteed, such as the above-mentioned cavity inside the luminaire head housing.

[0074] According to a preferred embodiment, the central portion of the washer has at least one symmetry axis, and the peripheral portion of the washer has at least two symmetry axes, preferably four symmetry axes, more preferably exhibits a central symmetry with respect to a center of the through- hole.

[0075] According to a preferred embodiment, opposite sides of the washer are symmetric with respect to a plane intersecting the washer at half of a thickness thereof. In other words, both sides of the washer may be identical, so that the washer may be secured to the threaded rod and to the nut irrespective of the orientation of both sides of the washer.

[0076] According to a second aspect of the invention, there is provided a washer for securing a threaded rod comprising a non-rotational-symmetric surface, and a nut to a wall, such as a wall of a luminaire head housing, comprising an opening with a non-rotational-symmetric surface matching the non- rotational-symmetric surface of the threaded rod. A central portion of the washer is configured to engage with the threaded rod so as to block a rotation and a translation of the washer with respect to the threaded rod. A peripheral portion of the washer is configured to be folded and to abut a peripheral portion of the nut so as to secure the washer to the nut.

[0077] The skilled person will understand that the hereinabove described technical considerations and advantages for the system embodiments of the first aspect also apply to the corresponding washer embodiments of the second aspect, mutatis mutandis.

[0078] According to a preferred embodiment, the central portion of the washer comprises a through-hole comprising a non-rotational-symmetric surface configured to match the non-rotational-symmetric surface of the threaded rod so as to block the rotation of the washer with respect to the threaded rod.

[0079] According to a preferred embodiment, the central portion of the washer comprises a plurality of teeth protruding from an inner surface of the central portion, said plurality of teeth being configured to engage with the thread of the threaded rod so as to block the translation of the washer with respect to the threaded rod.

[0080] According to a preferred embodiment, the peripheral portion of the washer comprises a plurality of protrusions from an outer surface of the peripheral portion, said plurality of protrusions being configured to be folded and each to abut a corresponding area of the peripheral portion of the nut so as to secure the washer to the nut.

[0081] According to a third aspect of the invention, there is provided a method for securing a threaded rod comprising a non-rotational-symmetric surface, and a nut to a wall, such as a wall of a luminaire head housing, comprising an opening with a non-rotational-symmetric surface, using the washer of any one of the above-mentioned embodiments. Said method comprises inserting the threaded rod into the opening in an orientation such that the respective non-rotational-symmetric surfaces match, fixing the nut to the threaded rod and securing the nut to the wall, and securing the washer to the threaded rod and to the nut, the nut being arranged between the washer and the wall. The securing the washer to the threaded rod and to the nut comprises inserting the washer around the threaded rod in an orientation so as to block a rotation of the washer with respect to the threaded rod, engaging the central portion of the washer with the threaded rod so as to block a rotation and a translation of the washer with respect to the threaded rod, and folding and abutting the peripheral portion of the washer to a peripheral portion of the nut so as to secure the washer to the nut.

[0082] The skilled person will understand that the hereinabove described technical considerations and advantages for the system embodiments of the first aspect also apply to the corresponding method embodiments of the third aspect, mutatis mutandis.

[0083] According to a preferred embodiment, the central portion of the washer comprises said through-hole, and the engaging the central portion of the washer with the threaded rod comprises matching the non-rotational-symmetric surface of the through-hole with the non-rotational-symmetric surface of the threaded rod so as to block the rotation of the washer with respect to the threaded rod.

[0084] According to a preferred embodiment, the central portion of the washer comprises said plurality of teeth, and the engaging the central portion of the washer with the threaded rod comprises engaging the plurality of teeth with the thread of the threaded rod so as to block the translation of the washer with respect to the threaded rod.

[0085] According to a preferred embodiment, the peripheral portion of the washer comprises said plurality of protrusions, and the folding and abutting the peripheral portion of the washer to a peripheral portion of the nut comprises folding, preferably simultaneously, and abutting, preferably simultaneously, each protrusion to a corresponding area of the peripheral portion of the nut so as to secure the washer to the nut.

[0086] Preferably, the folding and abutting of each protrusion to a corresponding area of the peripheral portion of the nut is realized using a tool which enables to simultaneous fold each protrusion irrespective of the relative orientation of the nut with respect to the washer. The tool may be configured to be coupled with a pneumatic or hydraulic machine in order to apply sufficient and uniform pressure to simultaneously fold the protrusions and abut them to a corresponding area of the peripheral portion of the nut.

[0087] BRIEF DESCRIPTION OF THE FIGURES This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing a currently preferred embodiment of the invention. Like numbers refer to like features throughout the drawings.

[0088] Figures 1A and IB respectively illustrate a cross-sectional view and an enlarged perspective cross- sectional view of a system for securing a wall of a luminaire head housing according to an exemplary embodiment;

[0089] Figures 2A-2C respectively illustrate a perspective view, a bottom view, and a perspective bottom view of a system for securing a wall according to an exemplary embodiment; and

[0090] Figures 3A-3C respectively illustrate a top view, a side view, and a perspective view of a washer according to an exemplary embodiment.

[0091] DESCRIPTION OF THE EMBODIMENTS

[0092] Figures 1A and IB respectively illustrate a cross-sectional view and an enlarged perspective cross- sectional view of a system for securing a wall of a luminaire head housing according to an exemplary embodiment.

[0093] A system 10 for securing a wall 20 of a luminaire head housing 1000 is illustrated in Figures 1 A and IB. The wall 20 comprises an opening O with a non-rotational-symmetric surface 21. The system 10 comprises a threaded rod 100, a nut 200, and a washer 300. The threaded rod 100 is configured to extend through the opening O, and comprises a non-rotational-symmetric surface 101 configured to match the non-rotational-symmetric surface 21 of the opening O. The nut 200 is configured to be fixed to the threaded rod 100 and to be secured to the wall 20. The washer 300 is configured to be secured to the threaded rod 100 and to the nut 200. The nut 200 is arranged between the washer 300 and the wall 20. A central portion 310 (see Figure IB) of the washer 300 is configured to engage with the threaded rod 100 so as to block a rotation and a translation of the washer 300 with respect to the threaded rod 100. A peripheral portion 320 (see Figure IB) of the washer 300 is configured to be folded and to abut a peripheral portion 220 (see Figure IB) of the nut 200 so as to secure the washer 300 to the nut 200.

[0094] As illustrated in Figures 1A and IB, the wall 20 may be part of the luminaire head housing 1000. The wall 20 may comprise a protruding portion 22 surrounding the opening O and defining a cavity of the luminaire head housing 1000. A peripheral outer surface of the protruding portion 22 may be cylindrical. A peripheral inner surface of the cavity may be substantially cylindrical, and may comprise a plurality of reinforcing ribs. The threaded rod 100, the nut 200, and the washer 300 may extend in the cavity. The luminaire head housing 1000 may be configured to be suspended to a luminaire pole P (see Figure 1A). The threaded rod 100 may be configured to be fixed to the luminaire pole P at an end opposite the luminaire head housing 1000, so as to suspend the luminaire head housing 1000. The end of the threaded rod 100 (male) opposite the luminaire head housing 1000 may be configured to match a threaded bore (female) of the luminaire pole P (see Figure 1A) to fix the threaded rod 100 to the luminaire pole P. In an alternative embodiment, the end of the threaded rod 100 opposite the luminaire head housing 1000 may be provided with a threaded bore (female) configured to match a threaded rod (male) of the luminaire pole P to fix the threaded rod 100 to the luminaire pole P.

[0095] The luminaire head housing 1000 may comprise any one or more of the following electrical / electronic components: a light source, a light source driving means, a light source dimming means, surge protection circuitry, electrostatic discharge protection circuitry, a fuse, a metering circuitry, a driving and / or control circuitry for any electrical components of the light source.

[0096] The light source may face a lower surface of the luminaire head housing 1000, and the above- mentioned electrical / electronic components, such as the light source driving means, may be arranged in the luminaire head housing 1000 above the light source. The luminaire head housing 1000 may comprise a light cover covering the light source and configured to be releasably attached to the luminaire head housing 1000. The light cover may comprise a transparent or translucent portion. Optionally, a color filter may be arranged between the light source and the transparent or translucent portion of the light cover. For example, the color filter may be a sheet arranged above the transparent or translucent portion. The color filter is configured to absorb a portion of the light emitted by the light source in specific wavelength ranges so as to change the color of the light emitted by the luminaire head. Preferably, the color filter is accessible by opening the luminaire head housing 1000. In that way, the color filter can be easily changed, e.g. when it is desirable to change the color of the emitted light for a special occasion or festivity.

[0097] The light source may comprise a light support, such as a PCB, on which a plurality of light emitting diodes (LEDs) is mounted. The LEDs may be arranged in an array of multiple columns and rows. The light source may comprise RGB and / or RGBW and / or RGBA LEDs and associated control circuitry for controlling the color and / or the color temperature emitted by the light source. The number (e.g., 6, 12, 16, 24, 28, 36, 52, etc.) and / or the arrangement (e.g. square(s), (concentric) circle(s), etc.) of the LEDs on the light support may vary. Thus, the overall light color and / or light pattern and / or light intensity of the luminaire head may vary. One or more optical elements may be associated with the light source. The one or more optical elements may comprise a plurality of lens elements associated with the plurality of LEDs, e.g. grouped in a lens plate. However, also other types of optical elements may be additionally or alternatively present, such as reflectors, backlights, prisms, collimators, diffusors, and the like. In the context of the invention, a lens element may include any transmissive optical element that focuses or disperses light by means of refraction. It may also include any one of the following: a reflective portion, a backlight portion, a prismatic portion, a collimator portion, a diffusor portion. For example, a lens element may have a lens portion with a concave or convex surface facing a LED, or more generally a lens portion with a flat or curved surface facing the LED, and optionally a collimator portion integrally formed with said lens portion, said collimator portion being configured for collimating light transmitted through said lens portion. Also, a lens element may be provided with a reflective portion or surface or with a diffusive portion.

[0098] Thus, in the embodiment of Figures 1A and IB, the luminaire head may comprise a housing 1000 wherein the light source, the optical elements, the electrical / electronic components, and optionally a heat sink and a flux exhauster are arranged. The above-mentioned transparent or translucent portion facing the light source may be part of the housing 1000. Preferably, the light cover and the housing 1000 form a sealed luminaire head. A seal may be arranged at an interface between the housing 1000 and the light cover, either on the housing 1000 or on the light cover. The luminaire head may correspond to an outdoor luminaire head, with suitable ingress protection (IP) rating such as IP66 or IP67, or an indoor luminaire head, with suitable IP rating such as IP22-IP24 or more.

[0099] In other embodiments, the wall 20 may be part of a housing configured to accommodate a functional unit different from a light source, i.e., the wall 20 may be part of a housing which is different from a luminaire head housing. The functional unit may comprise any one or more of the following: an image sensing means such as a camera, a communication means such as an antenna, a sensing means such as an air quality sensor or a pollution sensor or a visibility sensor or a smoke sensor or a sound sensor (microphone) or a radio-frequency, RF, sensor or a movement sensor or a temperature sensor, a loudspeaker, a light projecting means such as a projector, a display, a laser device, a radar device, a light emitting device such as an ultraviolet (UV) light or an infrared (IR) light or a light for light fidelity (Li-Fi) communication, or a spraying / sanitizing device. In the embodiment of Figures 1A and IB, the luminaire head housing 1000 comprises a light source. It should be clear to the skilled person that in other embodiments, the functional unit may comprise any one or more of the other components mentioned above, in addition to or as an alternative of the light source. More generally, the functional unit may be any kind of sensor means, communicating means, signaling means, Human Interface Device and / or receiving means. It is noted that there may be multiple functional units accommodated in the housing, and the multiple functional units may be the same or different. Some functional units may emit signals containing information. For example, in case of a laser device, a laser beam may be projected on the ground, and the laser beam may be controlled such that information is displayed on the ground or in the sky. For example, in case of a microphone, audio or speech information may be emitted.

[0100] In yet other embodiments, the wall 20 may be a plate or a sheet, e.g., a plate or a sheet of metal or of other suitable material. The sheet may be substantially flat at least at a portion surround the opening O. The sheet may have a constant thickness at least at the portion surrounding the opening O. In other words, the wall 20 according to said yet other embodiments need not be part of a luminaire head housing or of a housing configured to accommodate a functional unit different from a light source.

[0101] As illustrated in Figures 1A and IB, the non-rotational-symmetric surface 21 of the opening O and the non-rotational-symmetric surface 101 of the threaded rod 100 may be flat surfaces. It should be clear to the skilled person that any other shape of the non-rotational-symmetric surface 21 of the opening O and the non-rotational-symmetric surface 101 of the threaded rod 100 may be envisaged, said shape enabling to avoid a rotation of the threaded rod 100 with respect to the wall 20. In an alternative embodiment, the non-rotational-symmetric surface 101 of the threaded rod 100 may correspond to a recessed portion, i.e., a channel or a groove, extending along the threaded rod 100, and the non-rotational-symmetric surface 21 of the opening O may correspond to a protrusion configured to match the recessed portion of the threaded rod 100. Vice versa, in yet an alternative embodiment, the non-rotational-symmetric surface 21 of the opening O may correspond to a recessed portion, i.e., a channel or a groove, extending along a thickness of the wall 20 at the opening O, and the non-rotational-symmetric surface 101 of the threaded rod 100 may correspond to a protrusion configured to match the recessed portion of the opening O.

[0102] The opening O may further comprise a rotational-symmetric, i.e., cylindrical, surface, connecting the non-rotational-symmetric surface 21. Accordingly, the threaded rod 100 may further comprise a rotational-symmetric, i.e., cylindrical, surface, connecting the non-rotational-symmetric surface 101. In the above-mentioned alternative embodiments, the cylindrical surface of the threaded rod 100 may be provided with the above-mentioned recessed portion, i.e., the channel or the groove, to define the non-rotational-symmetric surface 101, and the cylindrical surface of the opening O may be provided with the above-mentioned protrusion to define the non-rotational-symmetric surface 21, or vice versa.

[0103] The threaded rod 100 may comprise a portion 102, preferably integrally formed therewith as illustrated in Figures 1 A and IB, configured to abut the wall 20 at a side opposite to the nut 200, the wall 20 being secured between the nut 200 and said portion 102 of the threaded rod 100. Preferably, a seal S may be arranged between said portion 102 of the threaded rod 100 and said side of the wall 20 opposite to the nut 200, as illustrated in Figures 1A and IB. A portion of the threaded rod 100 outside the luminaire head housing 1000 may have a rotational symmetry, i.e., may be cylindrical. Accordingly, the portion 102 of the threaded rod 100 may have a rotational symmetry, i.e., may be cylindrical, and the seal S may be an O-ring, i.e., may have a toroidal shape. By contrast, a portion of the threaded rod 100 inside the luminaire head housing 1000 has a non-rotational symmetry, i.e., comprises the above-mentioned non-rotational-symmetric surface 101. The threaded rod 100 may be threaded only on the portion of the threaded rod 100 inside the luminaire head housing 1000.

[0104] As illustrated in Figures 1A and IB, the threaded rod 100 may be a hollow rod. In embodiments wherein the wall 20 is part of a luminaire head housing 1000, such as the embodiment of Figures 1 A and IB, or of a housing configured to accommodate a functional unit different from a light source, the hollow threaded rod 100 may be configured to accommodate at least one cable, such as an electric cable, extending from outside the luminaire head housing 1000 or other housing accommodating another kind of functional unit, to the inside of the luminaire head housing 1000 or the other housing. In other embodiments, e.g., wherein the wall 20 is the above-mentioned plate or sheet, the threaded rod may be plain, i.e., not hollow.

[0105] Figures 2A-2C respectively illustrate a perspective view, a bottom view, and a perspective bottom view of a system for securing a wall according to an exemplary embodiment.

[0106] A system 10 for securing a wall 20 is illustrated in Figures 2A-2C. The wall 20 comprises an opening O with a non-rotational-symmetric surface 21. The system 10 comprises a threaded rod 100, a nut 200, and a washer 300. The threaded rod 100 is configured to extend through the opening O, and comprises a non-rotational-symmetric surface 101 configured to match the non-rotational-symmetric surface 21 of the opening O. The nut 200 is configured to be fixed to the threaded rod 100 and to be secured to the wall 20. The washer 300 is configured to be secured to the threaded rod 100 and to the nut 200. The nut 200 is arranged between the washer 300 and the wall 20. A central portion 310 (see Figures 2B and 2C) of the washer 300 is configured to engage with the threaded rod 100 so as to block a rotation and a translation of the washer 300 with respect to the threaded rod 100. A peripheral portion 320 (see Figures 2B and 2C) of the washer 300 is configured to be folded and to abut a peripheral portion 220 of the nut 200 so as to secure the washer 300 to the nut 200.

[0107] The wall 20 may be part of a luminaire head housing, such as the luminaire head housing 1000 of Figures 1A and IB. In other embodiments, the wall 20 may be part of a housing which is different from a luminaire head housing, as described above. In yet other embodiments, the wall 20 may be a plate or a sheet, e.g., a plate or a sheet of metal or of other suitable material, as described above.

[0108] The threaded rod 100, the nut 200, and the washer 300 may respectively correspond to the threaded rod 100, the nut 200, and the washer 300 illustrated in Figures 1A and IB and described above. The threaded rod 100, the nut 200, and the washer 300 may be made of metal, e.g., stainless steel.

[0109] As illustrated in Figures 2A-2C, the peripheral portion 220 of the nut 200 may comprise six flat surfaces, i.e., seen in a direction perpendicular to a plane defined by one side of the nut 200, the peripheral portion 220 of the nut 200 may be hexagonal. The six flat surfaces may be identical, i.e., the hexagon may be a regular hexagon. It should be clear to the skilled person that in other embodiments the peripheral portion 220 of the nut 200 may comprise more or less than six flat surfaces, e.g., seen in the direction perpendicular to the plane defined by one side of the nut 200, the peripheral portion 220 of the nut 200 may be triangular, square, or octagonal.

[0110] The central portion 310 of the washer 300 may comprise a through-hole H (see Figure 2B) comprising a non-rotational-symmetric surface 301 configured to match the non-rotational- symmetric surface 101 of the threaded rod 100 so as to block the rotation of the washer 300 with respect to the threaded rod 100. The non-rotational-symmetric surface 101 of the threaded rod 100 and the non-rotational-symmetric surface 301 of the washer 300 may be flat surfaces. It should be clear to the skilled person that any other shape of the non-rotational-symmetric surface 101 of the threaded rod 100 and the non-rotational-symmetric surface 301 of the washer 300 may be envisaged, said shape enabling to avoid a rotation of the washer 300 with respect to the threaded rod 100. In an alternative embodiment, the non-rotational-symmetric surface 101 of the threaded rod 100 may correspond to a recessed portion, i.e., a channel or a groove, extending along the threaded rod 100, and the non-rotational-symmetric surface 301 of the washer 300 may correspond to a protrusion configured to match the recessed portion of the threaded rod 100. Vice versa, in yet an alternative embodiment, the non-rotational-symmetric surface 301 of the washer 300 may correspond to a recessed portion, i.e., a channel or a groove, extending along a thickness of the washer 300 at the through-hole H, and the non-rotational-symmetric surface 101 of the threaded rod 100 may correspond to a protrusion configured to match the recessed portion of the washer 300. The threaded rod 100 may further comprise a rotational-symmetric, i.e., cylindrical, surface, connecting the non-rotational-symmetric surface 101. Accordingly, the washer 300 may further comprise a rotational-symmetric, i.e., cylindrical, surface, connecting the non-rotational-symmetric surface 301. In the above-mentioned alternative embodiments, the cylindrical surface of the threaded rod 100 may be provided with the above-mentioned recessed portion to define the non-rotational- symmetric surface 101, and the cylindrical surface of the washer 300 may be provided with the above-mentioned protrusion to define the non-rotational-symmetric surface 301, or vice versa.

[0111] As illustrated in Figures 2A-2C, the central portion 310 of the washer 300 may comprise a plurality of teeth 311 protruding from an inner surface of the central portion 310. The plurality of teeth 311 may be configured to engage with the thread of the threaded rod 100 so as to block the translation of the washer 300 with respect to the threaded rod 100. The plurality of teeth 311 may be integrally formed with the washer 300, and the central portion 310 of the washer 300 may be provided with a cut 312 on either side of each tooth 311, thereby defining the plurality of teeth 311. The plurality of teeth 311 may be distributed along the inner surface of the central portion 310. The plurality of teeth 311 may be arranged symmetrically with respect to a center of the through-hole H (see Figure 2B). In other embodiments, the plurality of teeth 311 may be arranged asymmetrically with respect to the center of the through-hole H.

[0112] In some embodiments, the plurality of teeth 311 may be configured to be oriented towards the nut 200 prior to engaging with the thread of the threaded rod 100. During engagement with the thread of the threaded rod 100, the plurality of teeth 311 may be folded in an opposite direction due to the contact with the thread. Depending on the plasticity or elasticity of the plurality of teeth 311, which in turn may depend on a material used for the plurality of teeth 311 and / or on the dimensions (thickness, radial length, width) of the plurality of teeth 311, the plurality of teeth 311 may, after being folded during engagement with the thread of the threaded rod 100, be oriented in a direction included in a plane defined by the washer 300, or be oriented away from the nut 200.

[0113] The through-hole H may further comprise a plurality of curved, preferably circular as illustrated in Figures 2A-2C, surfaces 302 connecting the non-rotational-symmetric surface 301 of the through- hole H, and respective edges of the plurality of teeth 311 may form part of the plurality of curved surfaces 302. The respective edges of the plurality of teeth 311 may protrude from the remainder of the plurality of curved surfaces 302 so as to engage with the thread of the threaded rod 100. A thickness of the plurality of teeth 311 may be smaller than the pitch of the thread of the threaded rod 100. Preferably, the thickness of the plurality of teeth 311 may be between 10 % and 75 % of said pitch, e.g. may be 50 % of said pitch.

[0114] In the embodiment of Figures 2A-2C, the central portion 310 of the washer 300 comprises four teeth 311 arranged symmetrically with respect to a center of the through-hole H. The through-hole H further comprises six circular surfaces 302 connecting the non-rotational-symmetric surface 301 of the through-hole H, and the four respective edges of the four teeth 311 form four of the six circular surfaces 302. The four respective edges of the four teeth 311 protrude from the remainder of the six circular surfaces 302 so as to engage with the thread of the threaded rod 100.

[0115] As illustrated in Figures 2A-2C, the peripheral portion 320 of the washer 300 may comprise a plurality of protrusions 321 from an outer surface of the peripheral portion 320. The plurality of protrusions 321 may be configured to be folded and each to abut a corresponding area of the peripheral portion 220 of the nut 200 so as to secure the washer 300 to the nut 200. The plurality of protrusions 321 may be integrally formed with the washer 300, and the peripheral portion 320 of the washer 300 may be provided with a cut 322 (see Figures 2A and 2C) on either side of each protrusion 321, thereby defining the plurality of protrusions 321. The plurality of protrusions 321 may be distributed along the outer surface of the peripheral portion 320. The plurality of protrusions 321 may be arranged symmetrically with respect to a center of the through-hole H (see Figure 2B). In other embodiments, the plurality of protrusions 321 may be arranged asymmetrically with respect to the center of the through-hole H.

[0116] In other embodiments, substantially the entire peripheral portion 320 of the washer 300 may be folded and abut a peripheral portion 220 of the nut 200 so as to secure the washer 300 to the nut 200.

[0117] The peripheral portion 220 of the nut 200 may comprise a plurality of flat surfaces. Each protrusion 321 may abut a corresponding flat surface of the peripheral portion 220 of the nut 200. Alternatively, one protrusion 321 may abut an area around an edge of the peripheral portion 220 of the nut 200, and another protrusion 321 may abut a flat surface of the peripheral portion 220 of the nut 200. Yet alternatively, each protrusion 321 may abut a corresponding area around an edge of the peripheral portion 220 of the nut 200.

[0118] In the embodiment of Figures 2A-2C, the peripheral portion 220 of the nut 200 comprises six identical flat surfaces, i.e., seen in a direction perpendicular to a plane defined by one side of the nut 200, is a regular hexagon, and the peripheral portion 320 of the washer 300 comprises four protrusions 321 arranged symmetrically with respect to the center of the through-hole H, i.e., at 90° with respect to one another. A first pair of opposite protrusions 321 abut two corresponding opposite flat surfaces of the peripheral portion 220 of the nut 200, and a second pair of opposite protrusions 321 abut two corresponding areas around opposite edges of the peripheral portion 220 of the nut 200. It should be clear to the skilled person that in other embodiments, the peripheral portion 320 of the washer 300 comprises more or less that four protrusions 321, e.g. two opposite protrusions, i.e., at 180° with respect to one another, or three opposite protrusions, i.e., at 120° with respect to one another, or six opposite protrusions, i.e., at 60° with respect to one another.

[0119] Depending on the relative orientation of the nut 200 with respect to the washer 300, each of the four protrusions 321 may partly abut a flat surface and partly abut an edge of the peripheral portion 220 of the nut 200. However, irrespective of the relative orientation of the nut 200 with respect to the washer 300, the plurality of protrusions 321 may be configured to be folded and each to abut a corresponding area of the peripheral portion 220 of the nut 200 so as to secure the washer 300 to the nut 200.

[0120] The peripheral portion 320 of the washer 300 may comprise a plurality of flat surfaces 323 (see Figures 2B and 2C), and each protrusion 321 may be connected to a corresponding flat surface 323. The peripheral portion 320 of the washer 300 may further comprise a plurality of curved, preferably circular, surfaces 324 (see Figures 2B and 2C), each respectively connecting two of the plurality of flat surfaces 323, and each tooth 311 may be facing away a corresponding curved surface 324.

[0121] In the embodiment of Figures 2A-2C, the peripheral portion 320 of the washer 300 comprises four flat surfaces 323, and four curved surfaces 324, each respectively connecting two of the four flat surfaces 323. In other words, seen in a direction perpendicular to a plane defined by the washer 300, the peripheral portion 320 of the washer 300 is a square with rounded corners (see Figure 2B). The four protrusions 321 are connected to a corresponding flat surface 323, and each of the four teeth 311 is facing away a corresponding curved surface 324.

[0122] As illustrated in Figures 2A-2C, each protrusion 321 may be provided with one or more cuts 325 so as to divide each protrusion 321 into two or more respective portions 321a, 321b. A radial length of each protrusion 321, i.e., a length of each protrusion 321 measured radially from the center of the through-hole H, may be substantially equal to a height of the peripheral portion 220 of the nut 200. The one or more cuts 325 may extend along substantially the entire radial length of each protrusion 321. In the embodiment of Figures 2A-2C, each protrusion 321 is provided with one cut 325 so as to divide each protrusion 321 into two respective portions 321a, 321b. Depending on the relative orientation of the nut 200 with respect to the washer 300, the two respective portions 321a, 321b of each protrusion 321 may abut the same flat surface of the peripheral portion 220 of the nut 200, or may abut two corresponding areas around an edge of the peripheral portion 220 of the nut 200. In other embodiments, each protrusion 321 may be provided with more than one cut 325 so as to divide each protrusion 321 into more than two respective portions 321a, 321b.

[0123] The threaded rod 100 may comprise a portion 102, preferably integrally formed therewith as illustrated in Figure 2A, configured to abut the wall 20 at a side opposite to the nut 200, the wall 20 being secured between the nut 200 and said portion 102 of the threaded rod 100. Preferably, a seal S may be arranged between said portion 102 of the threaded rod 100 and said side of the wall 20 opposite to the nut 200, as illustrated in Figure 2 A. A portion of the threaded rod 100 at a side opposite the nut 200 may have a rotational symmetry, i.e., may be cylindrical. Accordingly, the portion 102 of the threaded rod 100 may have a rotational symmetry, i.e., may be cylindrical, and the seal S may be an O-ring, i.e., may have a toroidal shape. By contrast, a portion of the threaded rod 100 at a side in contact with the nut 200 has a non-rotational symmetry, i.e., comprises the above- mentioned non-rotational-symmetric surface 101. The threaded rod 100 may be threaded only on the portion of the threaded rod 100 at the side in contact with the nut 200.

[0124] Although not illustrated in Figures 2A-2C, the peripheral portion 320 of the washer 300 may be provided with a plurality of holes at one or more folding areas of the peripheral portion 320. In other words, the peripheral portion 320 of the washer 300 may be perforated at one or more folding areas of the peripheral portion 320. In the embodiment of Figures 2A-2C, the peripheral portion 320 of the washer 300 may be perforated at folding areas of the peripheral portion 320 corresponding to the arrangement of the four protrusions 321. In other embodiments, substantially the entire peripheral portion 320 of the washer 300 may be folded and abut a peripheral portion 220 of the nut 200 so as to secure the washer 300 to the nut 200. In said other embodiments, substantially the entire peripheral portion 320 of the washer 300 may be perforated so as to fold a substantial entirety of the peripheral portion 320.

[0125] Figures 3A-3C respectively illustrate a top view, a side view, and a perspective view of a washer according to an exemplary embodiment.

[0126] A washer 300 for securing a threaded rod comprising a non-rotational-symmetric surface, and a nut to a wall is illustrated in Figures 3A-3C. The wall comprises an opening with a non-rotational- symmetric surface matching the non-rotational-symmetric surface of the threaded rod. A central portion 310 of the washer 300 is configured to engage with the threaded rod so as to block a rotation and a translation of the washer 300 with respect to the threaded rod. A peripheral portion 320 of the washer 300 is configured to be folded and to abut a peripheral portion 220 of the nut so as to secure the washer 300 to the nut.

[0127] The wall may be part of a luminaire head housing, such as the luminaire head housing 1000 of Figures 1 A and IB. In other embodiments, the wall may be part of a housing which is different from a luminaire head housing, as described above. In yet other embodiments, the wall may be a plate or a sheet, e.g., a plate or a sheet of metal or of other suitable material, as described above.

[0128] The threaded rod, the nut, and the wall may respectively correspond to the threaded rod 100, the nut 200, and the wall 20 illustrated in Figures 1 A and IB and Figures 2A-2C. The threaded rod 100, the nut 200, and the washer 300 may be made of metal, e.g., stainless steel.

[0129] As illustrated in Figures 3A and 3C, the central portion 310 of the washer 300 may comprise a through-hole H comprising a non-rotational-symmetric surface 301 configured to match the non- rotational-symmetric surface of the threaded rod so as to block the rotation of the washer 300 with respect to the threaded rod 100. The non-rotational-symmetric surface 301 of the washer 300 may be a flat surface, as illustrated in Figures 3A and 3C.

[0130] The central portion 310 of the washer 300 may comprise a plurality of teeth 311 protruding from an inner surface of the central portion 310. The plurality of teeth 311 may be configured to engage with the thread of the threaded rod so as to block the translation of the washer 300 with respect to the threaded rod. The peripheral portion 320 of the washer 300 may comprise a plurality of protrusions 321 from an outer surface of the peripheral portion 320. The plurality of protrusions 321 may be configured to be folded and each to abut a corresponding area of the peripheral portion of the nut so as to secure the washer 300 to the nut.

[0131] The further description of the washer 300 with respect to Figures 1A and IB and Figures 2A-2C equally applies to the washer 300 of Figures 3A-3C, and thus will not be repeated in the following.

[0132] As illustrated in Figures 3A and 3C, the plurality of teeth 311 may be distributed along the inner surface of the central portion 310. The plurality of teeth 311 may be arranged symmetrically with respect to a center of the through-hole H. The plurality of protrusions 321 may be distributed along the outer surface of the peripheral portion 320. The plurality of protrusions 321 may be arranged symmetrically with respect to a center of the through-hole H. The central portion 310 of the washer 300 may have at least one symmetry axis Al. The peripheral portion 320 of the washer 300 may have at least two symmetry axes A2, preferably four symmetry axes A2 as illustrated in Figures 3A and 3C, more preferably may exhibit a central symmetry with respect to a center of the through-hole H as illustrated in Figures 3A and 3C.

[0133] The central portion 310 of the washer 300 may comprise at least three teeth 311, preferably at least four teeth 311 as illustrated in Figures 3 A and 3C. In the embodiment of Figures 3 A-3C, the central portion 310 of the washer 300 comprises four teeth 311 arranged symmetrically with respect to a center of the through-hole H. The through-hole H further comprises six circular surfaces 302 connecting the non-rotational-symmetric surface 301 of the through-hole H, and the four respective edges of the four teeth 311 form four of the six circular surfaces 302. The four respective edges of the four teeth 311 protrude from the remainder of the six circular surfaces 302 so as to engage with the thread of the threaded rod.

[0134] The peripheral portion 320 of the washer 300 may comprise at least three protrusions 321, preferably at least four protrusions 321 as illustrated in Figures 3A and 3C. In the embodiment of Figures 3A- 3C, the peripheral portion 320 of the washer 300 comprises four protrusions 321 arranged symmetrically with respect to the center of the through-hole H, i.e., at 90° with respect to one another. The peripheral portion 320 of the washer 300 comprises four flat surfaces 323, and four curved surfaces 324, each respectively connecting two of the four flat surfaces 323. In other words, seen in a direction perpendicular to a plane defined by the washer 300, the peripheral portion 320 of the washer 300 is a square with rounded corners (see Figure 3A). The four protrusions 321 are connected to a corresponding flat surface 323, and each of the four teeth 311 is facing away a corresponding curved surface 324.

[0135] As illustrated in Figure 3B, a thickness of the washer 300 may be between 0.5 mm and 2 mm, preferably between 1 mm and 1.5 mm. Opposite sides of the washer 300 may be symmetric with respect to a plane intersecting the washer 300 at half of a thickness thereof. In other words, both sides of the washer 300 may be identical, so that the washer 300 may be secured to the threaded rod and to the nut irrespective of the orientation of both sides of the washer 300.

[0136] Geometric properties of the washer 300 may vary depending on the application of the washer 300, i.e., depending on the technical field in which the wall, the threaded rod, and the nut are used in connection with the washer 300. In embodiments wherein the wall is part of a luminaire head housing, such as the luminaire head housing 1000 of Figures 1A and IB, a nut with an external diameter for example between 40 mm and 50 mm, e.g. 46 mm, and a height for example between 5 mm and 15 mm, e.g. 10 mm, may be used in connection with a threaded rod and a washer 300.

[0137] It should be clear to the skilled person that nuts with other dimensions may be used in such embodiments. It should also be clear to the skilled person that, for other applications in other technical fields, for example in the automotive industry, the aeronautical / aerospatial industry, the naval industry, in civil engineering, etc., nuts with other dimensions may be used.

[0138] Dimensions of the washer 300 may be adapted to the specific application of the washer 300. For example, a thickness of the washer 300 may be adapted, varying between 0.5 mm and 2 mm, preferably between 1 mm and 1.5 mm. In some examples, dimensions of the washer 300 may be adapted to threaded rods having a large diameter, to avoid that the peripheral portion 320 of the washer 300 be overly folded onto the peripheral portion 220 of the nut 200 so as to correctly secure the washer 300 to the nut 200. In some other examples, dimensions of the washer 300 may be adapted to threaded rods having a small diameter, to ensure that the peripheral portion 320 of the washer 300 abut the peripheral portion 220 of the nut 200 over a sufficient contact area so as to correctly secure the washer 300 to the nut 200. Dimensions of the central portion 310 of the washer 300 may be adapted to the type of threaded rod. For example, a diameter of the through-hole H may be adapted to the diameter of the threaded rod which is selected for a specific application. Dimensions of the peripheral portion 320 of the washer 300 may be adapted to the type of nut. For example, a radial length and / or a width of the peripheral portion 320 of the washer 300 may be adapted to the external dimensions of the nut which is selected for a specific application.

[0139] In embodiments wherein the wall is part of a luminaire head housing, such as the luminaire head housing 1000 of Figures 1A and IB, a thickness of the washer 300 may for example be between 1 mm and 1.5 mm, e.g. 1 mm. A diameter of the through-hole H may for example be between 30 mm and 35 mm, e.g. 32.5 mm. A distance between the center of the through-hole H and the non- rotational-symmetric surface 301 may for example be between 10 mm and 15 mm, e.g. 13 mm. An outer dimension of the washer 300 with the protrusions 321 unfolded may for example be between 60 mm and 70 mm, e.g. 64 mm. A radial length of each protrusion 321 may for example be between 5 mm and 15 mm, e.g. 10 mm. A length of each respective portion 321a, 321b of each protrusion 321 may for example be between 5 mm and 15 mm, e.g. 9.5 mm. It should be clear to the skilled person that the above-mentioned dimensions of the washer 300 are merely exemplary.

[0140] It should also be clear to the skilled person that other values for the above-mentioned dimensions of the washer 300 may be envisaged, depending on the technical field in which the wall, the threaded rod, and the nut are used in connection with the washer 300. For example, the diameter of the through-hole H and / or the distance between the center of the through-hole H and the non-rotational- symmetric surface 301 may be adapted to the external diameter of the threaded rod. For example, the outer dimension of the washer 300 with the protrusions 321 unfolded and / or the radial length of each protrusion 321 may be adapted to the external diameter of the nut. For example, the length of each protrusion 321, and especially of each respective portion 321a, 321b of each protrusion 321, may be adapted to the number of flat surfaces of the peripheral portion of the nut (hexagonal, etc.).

[0141] Other properties of the washer 300 may be adapted to the specific application of the washer 300. For example, a weight and / or a material of the washer 300 may be adapted. In embodiments wherein the wall is part of a luminaire head housing, such as the luminaire head housing 1000 of Figures 1 A and IB, a weight of the washer 300 may for example be between 10 g and 20 g, e.g. 14 g. A material of the washer 300 may for example be an alloy such as steel, e.g. stainless steel. The washer 300 may for example be coated (galvanized) e.g. with zinc on both sides of the washer 300. A rigidity / plasticity or elasticity of the washer 300 may be adapted to the specific application. The choice of thickness and / or material may influence the rigidity / plasticity or elasticity of the washer 300. In some examples, a material of the washer 300 may be an alloy, such as steel, e.g. stainless steel, having an increased elasticity in order to increase the tightening range of the washer 300, compared to an alloy commonly found in the market. Such an alloy may thus have a function similar to that of a spring, and may be referred to as a “spring” alloy, e.g., “spring” stainless steel. A rigidity / plasticity or elasticity of the plurality of teeth 311 may be adapted to the specific application. For example, a thickness and / or a radial length and / or a width of the plurality of teeth 311 may be adapted to the specific application. In some examples, a material of the plurality of teeth 311 may be the above-described material of the washer 300, i.e., the “spring” alloy, e.g., “spring” stainless steel.

[0142] Although not illustrated in Figures 3A-3C, the peripheral portion 320 of the washer 300 may be provided with a plurality of holes at one or more folding areas of the peripheral portion 320. In other words, the peripheral portion 320 of the washer 300 may be perforated at one or more folding areas of the peripheral portion 320. In the embodiment of Figures 3A-3C, the peripheral portion 320 of the washer 300 may be perforated at folding areas of the peripheral portion 320 corresponding to the arrangement of the four protrusions 321. In other embodiments, substantially the entire peripheral portion 320 of the washer 300 may be folded and abut a peripheral portion of the nut so as to secure the washer 300 to the nut. In said other embodiments, substantially the entire peripheral portion 320 of the washer 300 may be perforated so as to fold a substantial entirety of the peripheral portion 320. In connection with Figures 1 A-3C, a method for securing a threaded rod 100 and a nut 200 to a wall 20 using the above-described washer 300 is described in the following. The threaded rod 100 comprises a non-rotational-symmetric surface 101. The wall 20 may be a wall 20 of a luminaire head housing 1000. The wall 20 comprises an opening O with a non-rotational-symmetric surface 21.

[0143] The method comprises inserting the threaded rod 100 into the opening O in an orientation such that the respective non-rotational-symmetric surfaces 21, 101 match, fixing the nut 200 to the threaded rod 100 and securing the nut 200 to the wall 20, and securing the washer 300 to the threaded rod 100 and to the nut 200, the nut 200 being arranged between the washer 300 and the wall 20.

[0144] The securing the washer 300 to the threaded rod 100 and to the nut 200 comprises inserting the washer 300 around the threaded rod 100 in an orientation so as to block a rotation of the washer 300 with respect to the threaded rod 100, engaging the central portion 310 of the washer 300 with the threaded rod 100 so as to block a rotation and a translation of the washer 300 with respect to the threaded rod 100, and folding and abutting the peripheral portion 320 of the washer 300 to a peripheral portion 220 of the nut 200 so as to secure the washer 300 to the nut 200.

[0145] In an embodiment wherein the central portion 310 of the washer 300 comprises the above-described through-hole H, the engaging the central portion 310 of the washer 300 with the threaded rod 100 may comprise matching the non-rotational-symmetric surface 301 of the through-hole H with the non-rotational-symmetric surface 101 of the threaded rod 100 so as to block the rotation of the washer 300 with respect to the threaded rod 100.

[0146] In an embodiment wherein the central portion 310 of the washer 300 comprises the above-described plurality of teeth 311, the engaging the central portion 310 of the washer 300 with the threaded rod 100 may comprise engaging the plurality of teeth 311 with the thread of the threaded rod 100 so as to block the translation of the washer 300 with respect to the threaded rod 100.

[0147] In an embodiment wherein the peripheral portion 320 of the washer 300 comprises the abovedescribed plurality of protrusions 321, the folding and abutting the peripheral portion 320 of the washer 300 to a peripheral portion 220 of the nut 200 may comprise folding, preferably simultaneously, and abutting, preferably simultaneously, each protrusion 321 to a corresponding area of the peripheral portion 220 of the nut 200 so as to secure the washer 300 to the nut 200.

[0148] The folding and abutting of each protrusion 321 to a corresponding area of the peripheral portion 220 of the nut 200 may be realized using a tool which enables to simultaneous fold each protrusion 321 irrespective of the relative orientation of the nut 200 with respect to the washer 300. The tool may be configured to be coupled with a pneumatic or hydraulic machine in order to apply sufficient and uniform pressure to simultaneously fold the protrusions 321 and abut them to a corresponding area of the peripheral portion 220 of the nut 200.

[0149] Whilst the principles of the invention have been set out above in connection with specific embodiments, it is to be understood that this description is merely made by way of example and not as a limitation of the scope of protection which is determined by the appended claims.

Claims

CLAIMS1. A system (10) for securing a wall (20), such as a wall (20) of a luminaire head housing (1000), comprising an opening (O) with a non-rotational-symmetric surface (21), said system (10) comprising: a threaded rod (100) configured to extend through the opening (O), said threaded rod (100) comprising a non-rotational-symmetric surface (101) configured to match the non- rotational-symmetric surface (21) of the opening (O); a nut (200) configured to be fixed to the threaded rod (100) and to be secured to the wall (20); and a washer (300) configured to be secured to the threaded rod (100) and to the nut (200); wherein the nut (200) is arranged between the washer (300) and the wall (20); wherein a central portion (310) of the washer (300) is configured to engage with the threaded rod (100) so as to block a rotation and a translation of the washer (300) with respect to the threaded rod (100); and wherein a peripheral portion (320) of the washer (300) is configured to be folded and to abut a peripheral portion (220) of the nut (200) so as to secure the washer (300) to the nut (200).

2. The system of claim 1, wherein the central portion (310) of the washer (300) comprises a through-hole (H) comprising a non-rotational-symmetric surface (301) configured to match the non-rotational-symmetric surface (101) of the threaded rod (100) so as to block the rotation of the washer (300) with respect to the threaded rod (100).

3. The system of claim 1 or 2, wherein the non-rotational-symmetric surface (21) of the opening (O) and the non-rotational-symmetric surface (101) of the threaded rod (100) are flat surfaces.

4. The system of claim 2, wherein the non-rotational-symmetric surface (301) of the washer (300) is a flat surface.

5. The system of any one of the previous claims, wherein the central portion (310) of the washer (300) comprises a plurality of teeth (311) protruding from an inner surface of the central portion (310), said plurality of teeth (311) being configured to engage with the thread of the threaded rod (100) so as to block the translation of the washer (300) with respect to the threaded rod (100).

6. The system of claim 5, wherein the plurality of teeth (311) is integrally formed with the washer (300), and wherein the central portion (310) of the washer (300) is provided with a cut (312) on either side of each tooth (311), thereby defining the plurality of teeth (311).

7. The system of claim 5 or 6, wherein the plurality of teeth (311) is distributed along the inner surface of the central portion (310), wherein preferably the plurality of teeth (311) is arranged symmetrically with respect to a center of the through-hole (H).

8. The system of any one of claims 5-7, wherein the through-hole (H) further comprises a plurality of curved, preferably circular, surfaces (302) connecting the non-rotational- symmetric surface (301) of the through-hole (H), and wherein respective edges of the plurality of teeth (311) form part of the plurality of curved surfaces (302).

9. The system of claim 8, wherein the respective edges of the plurality of teeth (311) protrude from the remainder of the plurality of curved surfaces (302) so as to engage with the thread of the threaded rod (100).

10. The system of any one of claims 5-9, wherein a thickness of the plurality of teeth (311) is smaller than the pitch of the thread of the threaded rod (100), wherein preferably the thickness of the plurality of teeth (311) is between 10 % and 75 % of said pitch.

11. The system of any one of claims 5-10, wherein the central portion (310) of the washer (300) comprises at least three teeth (311), preferably at least four teeth (311).

12. The system of any one of the previous claims, wherein the peripheral portion (320) of the washer (300) comprises a plurality of protrusions (321) from an outer surface of the peripheral portion (320), said plurality of protrusions (321) being configured to be folded and each to abut a corresponding area of the peripheral portion (220) of the nut (200) so as to secure the washer (300) to the nut (200).

13. The system of claim 12, wherein the plurality of protrusions (321) is integrally formed with the washer (300), and wherein the peripheral portion (320) of the washer (300) is provided with a cut (322) on either side of each protrusion (321), thereby defining the plurality of protrusions (321).

14. The system of claim 12 or 13, wherein the plurality of protrusions (321) is distributed along the outer surface of the peripheral portion (320), wherein preferably the plurality of protrusions (321) is arranged symmetrically with respect to a center of the through-hole (H).

15. The system of any one of claims 12-14, wherein the peripheral portion (320) of the washer (300) comprises a plurality of flat surfaces (323), and wherein each protrusion (321) is connected to a corresponding flat surface (323).

16. The system of claim 15 and any one of claims 5-11, wherein the peripheral portion (320) of the washer (300) further comprises a plurality of curved, preferably circular, surfaces (324), each respectively connecting two of the plurality of flat surfaces (323), and wherein each tooth (311) is facing away a corresponding curved surface (324).

17. The system of any one of claims 12-16, wherein each protrusion (321) is provided with one or more cuts (325) so as to divide each protrusion (321) into two or more respective portions (321a, 321b).

18. The system of any one of claims 12-17, wherein a radial length of each protrusion (321) is substantially equal to a height of the peripheral portion (220) of the nut (200).

19. The system of claims 17 and 18, wherein the one or more cuts (325) extend along substantially the entire radial length of each protrusion (321).

20. The system of any one of claims 12-19, wherein the peripheral portion (320) of the washer (300) comprises at least three protrusions (321), preferably at least four protrusions (321).

21. The system of any one of the previous claims, wherein a thickness of the washer (300) is between 0.5 mm and 2 mm, preferably between 1 mm and 1.5 mm.

22. The system of any one of the previous claims, wherein the peripheral portion (320) of the washer (300) is provided with a plurality of holes at one or more folding areas of the peripheral portion (320).

23. The system of any one of the previous claims, wherein the threaded rod (100) comprises a portion (102), preferably integrally formed therewith, configured to abut the wall (20) at a side opposite to the nut (200), the wall (20) being secured between the nut (200) and said portion (102) of the threaded rod (100); wherein preferably a seal (S) is arranged between said portion (102) of the threaded rod (100) and said side of the wall (20) opposite to the nut (200).

24. The system of any one of the previous claims, wherein the wall (20) is part of the luminaire head housing (1000), said luminaire head housing (1000) being configured to be suspended to a luminaire pole (P).

25. The system of claim 24, wherein the threaded rod (100) is configured to be fixed to the luminaire pole (P) at an end opposite the luminaire head housing (1000), so as to suspend the luminaire head housing (1000).

26. The system of claim 24 or 25, wherein the wall (20) comprises a protruding portion (22) surrounding the opening (O) and defining a cavity of the luminaire head housing (1000).

27. The system of any one of the previous claims, wherein the central portion (310) of the washer (300) has at least one symmetry axis (Al), and wherein the peripheral portion (320) of the washer (300) has at least two symmetry axes (A2), preferably four symmetry axes (A2), more preferably exhibits a central symmetry with respect to a center of the through-hole (H).

28. The system of any one of the previous claims, wherein opposite sides of the washer (300) are symmetric with respect to a plane intersecting the washer (300) at half of a thickness thereof.

29. A washer (300) for securing a threaded rod (100) comprising a non-rotational-symmetric surface (101), and a nut (200) to a wall (20), such as a wall (20) of a luminaire head housing (1000), comprising an opening (O) with a non-rotational-symmetric surface (21) matching the non-rotational-symmetric surface (101) of the threaded rod (100); wherein a central portion (310) of the washer (300) is configured to engage with the threaded rod (100) so as to block a rotation and a translation of the washer (300) with respect to the threaded rod (100); and wherein a peripheral portion (320) of the washer (300) is configured to be folded and to abut a peripheral portion (220) of the nut (200) so as to secure the washer (300) to the nut (200).

30. The washer of claim 29, wherein the central portion (310) of the washer (300) comprises a through-hole (H) comprising a non-rotational-symmetric surface (301) configured to match the non-rotational-symmetric surface (101) of the threaded rod (100) so as to block the rotation of the washer (300) with respect to the threaded rod (100).

31. The washer of claim 29 or 30, wherein the central portion (310) of the washer (300) comprises a plurality of teeth (311) protruding from an inner surface of the central portion (310), said plurality of teeth (311) being configured to engage with the thread of the threaded rod (100) so as to block the translation of the washer (300) with respect to the threaded rod (100).

32. The washer of any one of claims 29-31 , wherein the peripheral portion (320) of the washer (300) comprises a plurality of protrusions (321) from an outer surface of the peripheral portion (320), said plurality of protrusions (321) being configured to be folded and each to abut a corresponding area of the peripheral portion (220) of the nut (200) so as to secure the washer (300) to the nut (200).

33. A method for securing a threaded rod (100) comprising a non-rotational-symmetric surface (101), and a nut (200) to a wall (20), such as a wall (20) of a luminaire head housing (1000), comprising an opening (O) with a non-rotational-symmetric surface (21), using the washer (300) of any one of claims 29-32, said method comprising: inserting the threaded rod (100) into the opening (O) in an orientation such that the respective non-rotational-symmetric surfaces (21, 101) match; fixing the nut (200) to the threaded rod (100) and securing the nut (200) to the wall (20); and securing the washer (300) to the threaded rod (100) and to the nut (200), the nut (200) being arranged between the washer (300) and the wall (20); wherein the securing the washer (300) to the threaded rod (100) and to the nut (200) comprises: inserting the washer (300) around the threaded rod (100) in an orientation so as to block a rotation of the washer (300) with respect to the threaded rod (100); engaging the central portion (310) of the washer (300) with the threaded rod (100) so as to block a rotation and a translation of the washer (300) with respect to the threaded rod (100); and folding and abutting the peripheral portion (320) of the washer (300) to a peripheral portion (220) of the nut (200) so as to secure the washer (300) to the nut (200).

34. The method of claim 33, wherein the washer is according to claim 30, wherein the engaging the central portion (310) of the washer (300) with the threaded rod (100) comprises matching the non-rotational-symmetric surface (301) of the through-hole (H) with the non-rotational- symmetric surface (101) of the threaded rod (100) so as to block the rotation of the washer (300) with respect to the threaded rod (100).

35. The method of claim 33 or 34, wherein the washer is according to claim 31, wherein the engaging the central portion (310) of the washer (300) with the threaded rod (100) comprises engaging the plurality of teeth (311) with the thread of the threaded rod (100) so as to block the translation of the washer (300) with respect to the threaded rod (100).

36. The method of any one of claims 33-35, wherein the washer is according to claim 32, wherein the folding and abutting the peripheral portion (320) of the washer (300) to a peripheral portion (220) of the nut (200) comprises folding, preferably simultaneously, and abutting, preferably simultaneously, each protrusion (321) to a corresponding area of the peripheral portion (220) of the nut (200) so as to secure the washer (300) to the nut (200).

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