Aircraft windscreen wiper drive arm and method of manufacture

Abstract

The invention relates to a drive arm (20) for an aircraft windscreen wiper, the drive arm (20) comprising a body (21) which extends longitudinally between a first end (22) equipped with a coupling member (24) configured to be coupled to drive means and a second end (23) equipped with a coupling interface (25) configured to support the windscreen wiper. According to the invention, the drive arm (20) comprises a core (26) which extends inside the body (21) between the coupling interface (25) and the coupling member (24), the core (26), the coupling member (24) and the coupling interface (25) being conductors of electricity and at least partially integrated into the body (21) of the drive arm (20), the body (21) comprising at least one composite material. The invention also relates to a method for manufacturing the drive arm (20).

Description

Description Title of the invention: Windshield wiper drive arm for an aircraft and its manufacturing method [Technical field]

[0001] The invention relates to a windshield wiper drive arm for an aircraft such as an airplane, helicopter, or any other type of aircraft with a windshield. The invention falls more broadly within the field of aeronautics.

[0002] In practice, an aircraft wiper drive arm constitutes an interface between motor means which enable the wiper sweeping motion, and the wiper blade itself which operates the wiping of the aircraft cockpit windshield.

[0003] The design of an aircraft windshield wiper drive arm is subject to numerous constraints that make innovation in this field very delicate.

[0004] A primary constraint is the ability to absorb the forces generated by the wiper blade's mass during its sweep across the cockpit windshield. Generally, the drive system generates a sinusoidal motion, giving the wiper blade an angular range of motion adapted to the cockpit dimensions. Therefore, the drive arm that supports and propels the wiper blade must be able to withstand the forces generated by the wiper's mass inertia to ensure continuous windshield wiping.

[0005] A second constraint is maintaining the wiper blade in contact with the windshield throughout its entire range of motion, regardless of the weather conditions encountered by the aircraft during flight. Therefore, if the wiper blade lifts, the drive arm must be sufficiently robust and flexible to bring the wiper blade back into contact with the windshield.

[0006] A third constraint relates to the reliability of the mechanical coupling, firstly, between the drive arm and the propulsion system, and secondly, between the drive arm and the windshield wiper. Indeed, the consequences of a cockpit windshield shattered during flight by a detached drive arm and / or wiper can be catastrophic.

[0007] A fourth constraint concerns resistance to collisions with groups of birds that aircraft may experience during flight. The term "bird strike" is commonly used by those skilled in the art to refer to this phenomenon.

[0008] Thus, the training arm must meet all the constraints we have just outlined, regardless of the weather conditions the aircraft is likely to encounter during its flights, such as rain, hail, wind, frost, LIV radiation, storm cells, etc.

[0009] In this regard, a fifth constraint is directly related to the meteorological conditions an aircraft may encounter: lightning strikes, which can occur when an aircraft flies through a storm cell. The challenge in such a situation lies in maintaining the integrity of the drive arm, firstly, to ensure it continues to perform its function, and secondly, to prevent it from disintegrating and damaging the cockpit windshield. Currently, standards defined by the aeronautical industry require that the drive arm be able to allow lightning to pass through so that the electrical charge continues its path along the aircraft's fuselage.

[0010] Another constraint to consider when designing a drive arm for an aircraft windshield wiper is the adaptability of the design to different windshield dimensions and shapes. Indeed, each aircraft model has its own specific windshield dimensions and shape. Therefore, to optimize design and manufacturing costs, the drive arm structure must be adaptable to various cockpit windshield shapes and sizes. [Prior art]

[0011] Given the constraints outlined above, an aircraft windshield wiper drive arm is traditionally made of steel and essentially consists of three elements. First, the drive arm includes a mechanical coupling element with the drive mechanism, which is generally configured to transmit a sinusoidal motion to the wiper blade. The drive arm then comprises a solid steel body coupled at one end to the coupling element and extending longitudinally to a second end that carries a wiper blade mounting interface. The drive arm body can have various shapes, each adapted to the windshield's contours. Thus, it is not uncommon for the drive arm body to have one or more curves to maintain the wiper blade in contact with the windshield, ensuring it wipes the pilots' field of vision.

[0012] In practice, the interface and coupling element are also made of steel. Steel is chosen for its mechanical strength, flexibility, and oxidation resistance. In this context, the various components of the drive arm are usually assembled from pre-assembled parts. This type of arm This drive arm has been used in the aeronautical field for over 20 years; consequently, it has proven its worth and meets all the constraints previously outlined. Moreover, over the past twenty years, the failure of a drive arm has not been officially recognized as a source of incidents. Despite the demonstrated effectiveness of the steel drive arm, the issue of reducing its mass falls within the broader context of aircraft weight reduction, particularly aimed at reducing energy consumption.

[0013] It is precisely with this in mind that US patent 2021 / 0403138 proposes a technical solution for lightening the drive arm. Specifically, this patent describes a drive arm whose body consists of a hollow cylinder made of composite material with a strictly straight shape. To meet the requirement of lightning protection, the composite cylinder is entirely covered by a metallic layer that provides electrical conductivity. This metallic layer is itself covered by an outer layer of epoxy resin. The straight body of the drive arm has coupling sockets at each end, which are partially integrated into the walls of the composite cylinder. These sockets allow, on the one hand, for the mechanical assembly of the coupling element and the mounting interface, and on the other hand, for the flow of electrical current.Furthermore, in order to keep the wiper blade in contact with the windshield, mechanical elastic return means are provided between the coupling element and the body of the drive arm.

[0014] Although this drive arm reduces the mass compared to a steel drive arm, it retains the drawbacks of a complex, prefabricated mechanical structure. These drawbacks stem from the sheer number of mechanical connectors, the complexity of the assembly, and the reduced electrical conductivity between the coupling interface, the arm body, and the coupling element. In fact, the flow of electrical current between the composite arm, the coupling interface, and the coupling element is limited to the rivet edges that secure the coupling interface and coupling element bushings to the drive arm body.

[0015] The invention aims to overcome all of these drawbacks. [Description of the invention]

[0016] The invention aims to reduce the mass of the drive arm of an aircraft wiper blade while respecting the constraints of an aircraft in flight.

[0017] The invention also aims to provide a drive arm having, on the one hand, elastic properties to maintain or return the wiper blade to contact with the aircraft windshield, and on the other hand, electrical conductivity properties to allow the passage of lightning.

[0018] The invention also aims to simplify the mechanical structure of known prior art drive arms.

[0019] In this context, the present invention relates to a wiper arm drive for an aircraft, the drive arm comprising a body extending longitudinally between a first end equipped with a coupling member configured to be coupled to motor means and a second end equipped with an interface configured to support the wiper blade.

[0020] The drive arm is characterized in that it has a core which extends inside the body between the coupling interface and the coupling member, the core, the coupling member and the coupling interface being electrically conductive and at least partially integrated into the body of the drive arm, the body comprising at least one composite material.

[0021] The composite body of the drive arm, which at least partially integrates the coupling element and the coupling interface, reduces the mass of the drive arm of the invention by at least half compared to a mechanically assembled steel drive arm of the same dimensions, thus reducing inertia during sweeping across the windshield. Furthermore, the electrical conductivity properties of the arm's core allow it to meet the requirements related to lightning strikes, as described in the introduction to this document. In addition, integrating the coupling element and the coupling interface into the body of the drive arm simplifies its mechanical structure.

[0022] In some embodiments, the core may include a metal blade extending within a recess formed inside the composite material body. The metal blade ensures continuity of electrical conductivity through the composite material body of the arm.

[0023] In some embodiments, the core may be made of metal; preferably, the core is made of copper. Copper is a malleable metal, allowing the core to be easily integrated into the body of the drive arm, regardless of the body's shape.

[0024] In some embodiments, the core can be coupled, on one end, to the coupling member, and on the other end, to the coupling interface; thus, the core, the coupling member, and the coupling interface form a single-piece armature. This feature ensures the passage of an electric current from one end of the drive arm to the other.

[0025] In particular, the metal blade can be welded, on one hand, at one end into a receiving groove made on the coupling member, and on the other On the other hand, at a second end, there is a receiving means provided on the coupling interface. The welded assembly of the armature ensures better electrical current flow than a mechanically assembled assembly.

[0026] In some embodiments, the body may include at least one curved section relative to at least one first plane in which the coupling member extends. The curved section allows, on the one hand, for the coupling interface to be offset from the coupling member, taking into account the shape of the aircraft cockpit windshield, and on the other hand, for the drive arm to be curved so that the coupling interface is able to apply pressure to the windshield through the wiper blade.

[0027] In some embodiments, the body may include an angled section that is positioned in line with the coupling member. The angled section allows the coupling member to be concealed and the drive arm to be stored along a windshield pillar when the drive arm is in its rest position.

[0028] In some embodiments, the body may include a section having at least one dimension that gradually decreases along the longitudinal direction of the body. In particular, the offset section of the body advantageously has such a profile, which gives the drive arm aerodynamic properties as well as elastic properties in bending and torsion.

[0029] In some embodiments, the composite material can be a solid and fibrous material. In particular, the body can be formed by an assembly of successive layers of composite fibers, the body comprising at least one layer of composite fibers which has a different spatial orientation of fibers with respect to a lower layer of composite fibers and / or with respect to a higher layer of composite fibers.

[0030] The crossing of composite fibers allows the body of the drive arm to have mechanical resistance properties in bending and torsion.

[0031] In embodiments, the composite material may comprise fibers selected from the following list: carbon fibers, aramid fibers, glass fibers, aluminum fibers, steel fibers, flax fibers, Hermes flax fibers, ramie fibers, hemp fibers, kenaf fibers, jute fibers, sisal fibers, silk fibers, bamboo fibers, or a mixture of these fibers.

[0032] The type of fibers chosen to make the composite material can be combined with a matrix whose material can be chosen from the following list: epoxy resins, polyester resins, vinyl ester resins, phenolic resins, BMI (polybismaleimide) resins, cyanester resins or a mixture of these materials.

[0033] In some embodiments, the drive arm may include a resin layer that at least partially encases the body, core, coupling member, and coupling interface. The resin layer protects, in particular, the composite material that makes up the body.

[0034] In some embodiments, the drive arm may have an external paint coating designed to resist abrasion. This paint coating helps maintain the integrity of the drive arm over time and thus extends its service life.

[0035] In some embodiments, the body may internally incorporate a cellular composite material. This structure reduces the mass of the drive arm while also increasing its mechanical strength.

[0036] In some embodiments, the coupling element consists of a rocker arm configured to be mounted on a shaft driven by the drive means.

[0037] In some embodiments, the coupling member can be crimped to the body of the drive arm. This increases the mechanical strength of the drive arm.

[0038] Similarly, in other embodiments, the coupling interface can be crimped to the body of the drive arm.

[0039] In some embodiments, the body comprises at least one profiled section. The section can be profiled by progressively reducing at least one dimension of its cross-section and / or through a curved profile along an X, Y, Z plane of a three-dimensional coordinate system.

[0040] The invention also relates to a method for manufacturing a conforming drive arm of the invention. The manufacturing method is characterized in that it comprises the following steps: generating a preform in composite material, contouring the preform in composite material so as to obtain the body of the drive arm according to a determined conformation, hollowing out at least partially the body of the drive arm, integrating the core, the coupling interface and the coupling member into the partially hollowed body of the drive arm, and applying a resin to coat the body and at least partially the coupling member and the coupling interface.

[0041] The manufacturing process makes it possible to manufacture a drive arm conforming to the invention, therefore it has the same advantages as the drive arm. [Description of the drawings]

[0042] Other features and advantages of the invention will become apparent upon reading the following description. This description is purely illustrative and should be read in conjunction with the accompanying drawings, in which:

[0043] [Fig. 1] is a perspective representation of the inner face of a drive arm of a conforming aircraft wiper of the invention.

[0044] [Fig. 2] is a perspective representation of the external face of the drive arm of figure 1.

[0045] [Fig. 3] is a schematic representation of a cross-section of the drive arm of Figure 1.

[0046] [Fig. 4] is a representation of a longitudinal section AA of the drive arm of figure 3.

[0047] [Fig. 5] is a representation of an exploded view of the armature of the drive arm of figure 1.

[0048] [Fig. 6] is a perspective representation of the coupling organ which connects the arm body to the motor means.

[0049] [Fig. 7] is a representation of a longitudinal section of the coupling element of figure 6.

[0050] [Fig. 8] is a representation of a wiper blade attachment interface which is arranged on the drive arm of Figure 1.

[0051] [Fig. 9] is a representation of a cross-section of the drive body according to a BB section of the drive arm body of Figure 3.

[0052] [Fig. 10] is a representation of a cross-section of the drive body according to a section BB of the drive arm body of figure 3 according to a second embodiment.

[0053] [Fig. 11] is a representation of a flowchart schematically illustrating the steps of the manufacturing process of a conforming drive arm of the invention. [Description of the embodiments]

[0054] With reference to Figures 1 to 5, the invention relates to a drive arm 20 for a windshield wiper blade for an aircraft. As explained in the introductory part of this document, the drive arm 20 essentially serves to interface the wiper blade with the drive means. To this end, the drive arm 20 comprises a body 21 extending longitudinally between a first end 22 and a second end 23.

[0055] As illustrated in Figure 9, the body 21 of the drive arm 20 may have a rectangular cross-section. However, in other embodiments, the cross-section of the body 21 of the drive arm 20 may take other shapes such as a circular, polygonal or oval shape.

[0056] The body 21 has at its first end 22 a coupling member 24 which is configured to be coupled to drive means. The drive means are not shown in this document. The drive means actuate, in a sinusoidal motion, the drive arm 20 which in turn drives the wiper blade in a similar motion.

[0057] At its second end 23, the body 21 has a coupling interface 25 which is configured to support the wiper blade. The wiper blade is not shown in the figures in the appendix to this document.

[0058] As illustrated in Figures 3 and 5, the drive arm 20 has a core 26. The core 26 extends inside the body 21 between the coupling interface 25 and the coupling member 24. The core 26 is shown as a dashed line in Figure 3. Advantageously, the core 26, the coupling member 24, and the coupling interface 25 are electrically conductive. This allows the passage of lightning between the two ends 22, 23 of the drive arm 20. In this example, the core 26 is made of metal. For example, the core 26 could be made of copper, aluminum, bronze, or any other metal or metallic alloy that exhibits good electrical conductivity. In particular, the core 26 could be made of a metal strip, such as a copper strip. The dimensions of the metal strip could vary depending on the dimensions of the drive arm 20.

[0059] As illustrated in Figures 3 and 5, the web 26 extends longitudinally between a first end 260 and a second end 261. The two ends 260 and 261 are opposite each other. In this example, the web 26 is coupled, on the one hand, at its first end 260 to the coupling member 24, and on the other hand, at its second end 261 to the coupling interface 25. Thus, the web 26, the coupling member 24, and the coupling interface 25 form a single-piece frame 27. An exploded view of the frame 27 is shown in Figure 5. Advantageously, the core 26 is welded at each of its ends 260, 261 to the coupling member 24 and to the coupling interface 25 respectively. For example, silver welding, TIG (Tungsten Inert Gas) welding, electron beam welding, etc., can be used.The coupling interface 25 and the coupling member 24 can be made of a metal or metal alloy that is electro-chemically compatible with the. solder used and the metallic material of the core 26. For example, stainless steel is compatible with copper and silver solder.

[0060] As illustrated in Figures 1 to 3, the core 26, the coupling member 24, and the coupling interface 25 are at least partially integrated into the body 21 of the drive arm 20. The body 21 comprises at least one composite material. In particular, the body 21 is made of a single piece whose structure is made using at least one composite material.

[0061] The coupling member 24 can be crimped to the body of the drive arm 20. This increases the cohesion between the body 21 and the coupling member 24. Similarly, the coupling interface 25 can also be crimped to the body 21. The cohesion between the various elements of the drive arm 20 ultimately contributes to improving its mechanical resistance properties, whether for load transfer, bending, or torsion of the drive arm 20.

[0062] For example, the composite material can be a solid and fibrous material. The composite material can then include fibers chosen from the following list: carbon fibers, aramid fibers, glass fibers, aluminum fibers, steel fibers, flax fibers, hermes flax fibers, ramie fibers, hemp fibers, kenaf fibers, jute fibers, sisal fibers, silk fibers, bamboo fibers or a mixture of these fibers.

[0063] In addition, the composite material also includes a matrix, the material of which can be chosen from the following list: epoxy resins, polyester resins, vinyl ester resins, phenolic resins, BMI (polybismaleimide) resins, cyanester resins, or a mixture of these materials.

[0064] In one embodiment of the invention, carbon fibers can be associated with an epoxy resin.

[0065] In some embodiments, the body 21 is formed by an assembly of successive layers of composite fibers. In practice, pre-impregnated composite fibers can be used, which are draped to form the body 21 of the drive arm 20.

[0066] For example, body 21 can have between 30 and 70 layers of composite fibers. Body 21 can also have between 40 and 50 layers of composite fibers. Furthermore, body 21 includes at least one layer of composite fibers with a different spatial fiber orientation compared to a lower layer of composite fibers and / or a higher layer of composite fibers. The intersection of one or more layers of composite fibers provides mechanical resistance to bending and torsion in the arm. training 20. For example, at least one layer of fibers may have an orientation offset by an angle between 50° and 90° relative to the straight fibers.

[0067] In embodiments of the invention, the body 21 may internally comprise a cellular composite material. For example, the cellular composite material may be arranged around the core 26 and surrounded by one or more layers of composite fibers.

[0068] Figure 9 schematically represents a section of the drive arm 20 according to section BB of the drive arm in Figure 3. As previously described, the web 26 is integrated into the composite material M. In particular, the web 26 extends within a recess 28 formed inside the composite material M. The recess 28 extends longitudinally between each end of the body 21. A machining method can be used to create the recess 28 within the composite material M.

[0069] According to one embodiment, the drive arm 20 may include a layer of resin 29 which coats the composite material M. In the embodiment of Figure 9, the layer of resin 29 also fills part of the recess 28.

[0070] The resin layer 29 can be made of an elastomeric material chosen from the following list: rubber, synthetic rubber such as a polythioether polymer, a polyisoprene polymer, an isobutylene-isoprene copolymer, a 1,3-butadiene polymer, a hydrogenated nitrile butadiene polymer, an ethylene-propylene-diene polymer, etc. The resin layer 29 is preferably made of an elastomeric material to fill the recess 28. This ensures that the mechanical properties of the body 21 of the drive arm 20 are not altered.

[0071] However, it is also possible to use epoxy resin as a material to make the resin layer 29. Indeed, if rigidity is desired, epoxy resin can be used as a filling material for the recess 28.

[0072] According to one embodiment, the resin layer 29 can also at least partially envelop the body 21, the core 26, the coupling member 24 and the coupling interface 25 in order to form a drive arm 20 whose contours are regular.

[0073] Epoxy resin can also be used to coat the body 21 of the drive arm 20. The epoxy resin then provides rigidity properties to the drive arm 21.

[0074] Furthermore, according to another embodiment, the drive arm 20 may include at least one layer of composite fibers covering the body 21 of the drive arm after the recess 28 has been filled with an elastomeric material or an epoxy resin. According to a third embodiment, a elastomeric material to fill the hollow 28 and an epoxy resin to coat the body 21 of the drive arm 20.

[0075] A demarcation 290 is schematically represented by a dotted line in figure 9; it illustrates the embodiments in which the filling material of the recess 28 is different from the encapsulating material of the body 21. One or the other embodiment is chosen according to the mechanical properties that are desired to be given to the drive arm 20.

[0076] As illustrated in Figure 9, the drive arm 20 may have a paint layer 30. The paint layer 30 is external, meaning that it encases the resin layer 29 and externally defines the drive arm 20. Preferably, the paint layer 30 is abrasion-resistant. This helps maintain the integrity of the drive arm 20 regardless of weather conditions or impacts that the aircraft may experience during flight.

[0077] The paint layer 30 can be made of a polymeric material chosen from the following list: polyurethane, polyvinyl, polyester, etc. The paint layer 30 can have a thickness between 100 and 300 µm. To improve the lifespan of the drive arm 20, the paint layer 30 has abrasion-resistant properties; for example, the paint layer 30 can have a Shore A hardness between 80 and 95.

[0078] According to an advantageous embodiment illustrated in Figure 10, the web 26 is embedded longitudinally within the composite material M. This increases the service life of the drive arm 20 by reducing wear-related cracking in the groove filled by the resin layer 29, as illustrated in Figure 9. This is achieved by using a sacrificial blade during the draping process to create the recess 28. This sacrificial blade is then extracted from the recess 28 to insert a metal blade that can form the web 26.

[0079] As illustrated in Figures 1 to 4, the body 21 is made from a single piece of composite material. However, in this example, the profile of the body 21 has at least three successive sections 31, 32, and 33. In particular, the body 21 has a first section 31 that incorporates the coupling member 24. Here, the first section 31 is straight and extends in an XY plane of a three-dimensional coordinate system X, Y, Z. The three-dimensional coordinate system is visible in Figure 3. The body 21 has a second section 32 that is angled. The second section 32 is positioned in line with the first section 31 and also extends in the XY plane.

[0080] As illustrated in Figures 1 to 4, the body 21 has a third section 33 extending between the bent section and the coupling interface 25. The third section 33 is straight along the XY plane, as illustrated in Figure 3. However, in the example of In Figure 3, the third section 33 is curved relative to the XZ plane, giving the outer face of the drive arm 20 a convex shape, while the inner face of the drive arm 20 is concave. The third section 33 corresponds to an offset section of the coupling interface 25. Indeed, the curvature offsets the coupling interface 25 relative to the coupling element 24, taking into account the shape of the aircraft cockpit windshield. On the other hand, the curvature of the third section 33 allows the coupling interface 25 to be pressed against the windshield of an aircraft through the wiper blade over the entire travel of the drive arm 20. The curvature of the third section 33 also provides resistance to torsion and bending of the body 21 of the drive arm 20. In the example of Figure 4, the third section 33 is convex with respect to the XZ plane.However, for a different cockpit windshield configuration, the third section 33 could be concave relative to the XZ plane.

[0081] Depending on the shape of the aircraft cockpit windshield, the body 21 may have one or more curved sections with respect to at least one plane in the three-dimensional X, Y, Z coordinate system.

[0082] As illustrated in Figures 1 to 3, the third section 33 can also be profiled. More specifically, the third section 33 can have at least one dimension that gradually decreases along the longitudinal direction of the body 21. In the example in Figure 3, the width of the cross-section of the body 21 decreases from the angled section towards the second end 23 of the drive arm 20. The decreasing width of the body 21 is visible in the XY plane of the three-dimensional X, Y, Z coordinate system in Figure 3. In contrast, as illustrated in Figure 4, the thickness of the body 21 remains constant. This profiling of the body 21 provides elastic properties in bending and torsion along the entire length of the third section 33. In this respect, the third section 33 can be compared to a leaf spring working in bending and torsion.

[0083] In the example shown in Figure 3, the angled section forms an angle α between the coupling member 24 and the body 21, and in particular the third section 33 of the body 21. The value of angle α also depends on the shape of the windshield on which the drive arm 20 is intended to be mounted. For example, angle α can be between 90° and 140°. Angle α can also be between 100° and 120°. The angled section 32 allows the coupling member 24 to be concealed and the drive arm 20 to be stored in the parking position. Indeed, when the drive arm 20 is in its resting position, the angled section 32 is located in the corner of the aircraft's windshield, while the third section 33 is adjacent to a windshield pillar. cockpit. Moreover, the opening of the angle facilitates the conduction of the electric current which runs through the core 26.

[0084] As illustrated in Figure 3, the first section 31 can have a length I between 100 mm and 200 mm, while the third section 33 can have a length L between 400 mm and 1000 mm. Generally, the dimensions of the drive arm 20 are determined empirically based on the dimensions and shape of the aircraft windshield on which the drive arm 20 is intended to be mounted.

[0085] The coupling member 24 is illustrated in particular in Figures 6 and 7. The coupling member 24 includes a bearing 240 located at one end of the coupling member 24. The bearing 240 allows the coupling member 24 to be coupled to the drive means, for example, via a transmission shaft. In this example, the bearing 240 has internal teeth 241. The teeth 241 improve the reliability of the mechanical coupling between the drive means and the drive arm 20 and consequently the load-bearing capacity, such as the inertia of the drive arm 20 during the sinusoidal sweeping motion.

[0086] As illustrated in Figures 6 and 7, the coupling member 24 has a lug 242. The lug 242 extends longitudinally between the bearing 240 and a free end 243 of the coupling member 24. The lug 242 forms an angle P with the outer wall of the bearing 240. The angle P can be between 50° and 120°. The value of angle P can also be between 60° and 90°. Preferably, the value of angle P is less than 90°. The value of angle P is determined based on several aircraft-related parameters, such as the position of the output shaft of the drive means to which the drive arm 20 is coupled, and the curvature and dimensions of the aircraft windshield. Angle P contributes to maintaining the windshield wiper blade in a perpendicular position to the windshield at all positions within its travel.

[0087] The angle P cooperates with the curvature of the curved section, in particular the third section 33, in order to give a certain convexity to the drive arm 20 so that the wiper blade can apply pressure to the windshield in all positions and ensure a constant sweep.

[0088] The lug 242 also has a groove 244 extending from the free end 243 towards the bearing 240. Preferably, the groove 244 is shorter than the lug 242. The groove 244 allows a first end 260 of the web 26 to be welded to the coupling member 24. In particular, the groove 244 is dimensioned to receive an end of the metal blade to allow for better welding.

[0089] The coupling member 24 also has at least one hole 245 located on the lug 242. In the example shown in Figures 6 and 7, the coupling member 24 has three holes 245 distributed along the lug 242. Here, the holes 245 are equally spaced. The holes 245 allow the coupling member 24 to be crimped to the body 21 of the drive arm. For example, the web 26 can be welded to the coupling member 24 to form the armature 27, and once the armature 27 is inserted into the recess provided for this purpose in the body 21, the holes 245 allow the passage of a mechanical connector 34, such as a rivet. This allows the coupling member 24 to be crimped to the body 21 of the drive arm. These mechanical connectors 34 are visible in transparency in Fig. 3.

[0090] Furthermore, as illustrated in Figures 6 and 7, the coupling member 24 has lateral reinforcements 246. The lateral reinforcements 246 extend over the upper face of the lug 242. Each lateral reinforcement 246 extends over one edge of the lug 242. The lateral reinforcements 246 extend longitudinally towards the free end 243. In this example, the lateral reinforcements 246 extend to the hole 245, which is proximal to the groove 244. The lateral reinforcements 246 ensure that the drive arm 20 can withstand the forces exerted on it without the coupling member 24 undergoing mechanical deformation.

[0091] Figure 8 shows a conforming coupling interface 25 of the invention. The coupling interface 25 is formed by a stirrup-shaped piece. The stirrup-shaped piece has two cheeks 250 and a dorsal portion 251. Here, the cheeks 250 are arranged on either side of the dorsal portion 251. The cheeks 250 are connected to the dorsal portion 251 by a first edge 252. As illustrated in Figure 8, the two cheeks 250 can be symmetrical with respect to a median longitudinal plane of the coupling interface 25.

[0092] In addition, each cheek 250 has a second edge 253 opposite the first edge 252. The second edge 253 is free and has a curved profile along at least part of its length. Here, the curved profile is oriented convexly with respect to the first edge 252. As illustrated in Figure 8, each cheek 250 has an opening 255. This opening 255 is aligned with the convex portion of the second edge 253. A dashed line illustrates this arrangement in Figure 8. The cheeks 250 of the stirrup-shaped part allow for the attachment of a wiper blade, for example, via a shaft that fits into the openings 255.

[0093] The dorsal part 251 has a flat face 256. This flat face 256 allows the core 26 to be welded to the coupling interface 25. The core 26 is shown as a dashed line in Figure 8. In this example, the dorsal part 251 also includes a stop 257. The stop 257 is projecting on one side of the dorsal part 251. The stop 257 allows the web 26 to be positioned against the stop in order to weld the web to the coupling interface 25. The dorsal part 251 and the stop 257 constitute a means of receiving the web 26.

[0094] Furthermore, the flat face 256 of the back portion 251 includes at least one hole 258. In the example of Figure 8, the flat face 256 has four holes 258. The holes 258 are distributed along the length of the flat face 256. The holes 258 allow the passage of mechanical connectors 35, such as rivets, for crimping the coupling interface 25 with the body 21 of the drive arm 20. In practice, the core 26 can initially be welded to the back portion 251 of the coupling interface 25 to form the reinforcement 27. Subsequently, the reinforcement 27 is inserted into a recess in the body 21. Once the coupling interface 25 is properly positioned in the body 21, the holes 258 are used as guides for drilling coaxially. the core 26 and the body 21 in order to crimp, using mechanical connectors 35, the coupling interface 25 to the body 21 of the drive arm 20.The mechanical connectors 35 are visible in transparency in figure 3.

[0095] In the example illustrated in Figure 8, the dorsal portion 251 also includes a bevel 259. The bevel 259 is located at the junction between the dorsal portion 251 and the first edge 252 of each cheek 250. The bevel 259 extends longitudinally along the length of the stirrup-shaped piece. The bevel 259 allows the wiper blade to rotate freely around an axis inserted in the opening 255 of each cheek 250 of the coupling interface 25.

[0096] With reference to figure 11, the invention also relates to a manufacturing method 50 for a drive arm 20 conforming to the invention.

[0097] The manufacturing process 50 includes a step 51 for generating a composite material preform. For this purpose, pre-impregnated composite material fiber layers can be draped into a mold of said preform. Once the pre-impregnated fiber layers are draped, the hardening of the composite material can be catalyzed, for example, by heating. However, depending on the type of pre-impregnated fibers used, the catalysis can also be of the radical type.

[0098] During the draping process, one or more layers of pre-impregnated fibers can be crossed to provide mechanical resistance in bending and / or torsion to the preform of the body 21 of the drive arm 20. According to one embodiment of the invention, the draping aims to form, on the one hand, a functional structure made of composite material that exhibits load-bearing capabilities in torsion and bending, and On the other hand, there is an encapsulation structure also made of composite material. The encapsulation structure is draped to enclose the functional structure. The encapsulation structure is designed to be machined without damaging the functional structure. Furthermore, during draping, an extra thickness can be draped at the ends of the preform. This extra thickness allows for the secure integration of the coupling member 24 and the coupling interface 25.

[0099] In one embodiment, a sacrificial blade can be introduced into the mold during draping. The sacrificial blade is positioned within the preform being draped and covered by a predetermined number of draping layers to create a passage extending inside the preform of the body 21 between the coupling interface 25 and the coupling member 24. In a first alternative, the sacrificial blade may comprise an elastomeric material such as silicone, polyurethane, or any other natural or synthetic rubber. In a second alternative, the sacrificial blade may comprise a chemically absorbable material such as polystyrene.

[0100] The draping is thus carried out around the sacrificial blade which allows a reservation impression to be made.

[0101] As illustrated in Figure 11, the manufacturing process 50 includes a trimming step 52 of the composite preform. The trimming step 52 enables the body 21 of the drive arm 20 to be shaped according to a predetermined conformation. The trimming step 52 can be carried out by a machining method known to those skilled in the art, such as milling. During this step, the encapsulation structure is trimmed while preserving the functional structure of the composite material M.

[0102] The manufacturing process 50 also includes a hollowing step 53. During this step, the body 21 is at least partially hollowed out by machining. In practice, it is the casing structure that is machined to form a hollow 28. The hollow 28 corresponds to a receiving cavity formed in the body 21 to receive the reinforcement 27. Milling is a machining method that can be used to perform the hollowing step 53.

[0103] According to the embodiment using a sacrificial blade, the recess 28 is formed by removing the sacrificial blade from the body 21. Removal of the sacrificial blade can be achieved by mechanical extraction or by chemical degradation. For example, if an elastomeric sacrificial blade is used, traction can be applied to one end of the blade to remove it from the recess 28 it created during draping. In the case of a resorbable sacrificial blade, a suitable chemical compound is used. to dissolve the sacrificial blade and form the recess 28. Thus, acetone can be used to dissolve a sacrificial blade that includes polystyrene.

[0104] The removal of the sacrificial blade provides an obvious 28 which can thus constitute a longitudinal passage within the body 21 of the training arm into which the soul 26 can be introduced.

[0105] According to this embodiment, one end of the body 21 can be machined to access one end of the sacrificial blade.

[0106] This embodiment is advantageous because it provides a body 21 whose composite material M forms a hollow body that encapsulates the core 26 and reduces cracking due to flexing of the drive arm 20 during prolonged use. This makes it possible to increase the mechanical strength of the drive arm 20, and consequently, its lifespan.

[0107] As illustrated in Figure 11, the manufacturing process 50 comprises a coupling step 54 of the coupling interface 25 and the coupling member 24 to a first end 260 and a second end 261 of the web 26, respectively. The coupling step 54 forms the frame 27 of the drive arm 20. The coupling step can be performed by welding each end of the web 260, 261 to the coupling member 24 and the coupling interface 25, respectively. As described previously, the groove 244 of the coupling member 24 and the flat face 256 of the coupling interface 25 can be used as weld supports. The weld is made by adding material, for example, silver. An abrasion operation to remove excess material can be performed to provide a clean finish.In the embodiment using a sacrificial blade, the core 26 can be coupled initially to the coupling member 24 and then, once the core is inserted into the recess 28, to the coupling interface 25 in order to form the frame 27. Alternatively, it is also possible to couple the coupling interface 25 initially and the coupling member 24 after the core has been inserted into the recess 28. According to another alternative, the metal blade can be inserted into the recess 28 and then coupled respectively at each of its ends 260, 261 to the coupling member 24 on the one hand, and to the coupling interface on the other.

[0108] The manufacturing process 50 includes an integration step 55 of the core 26, which is coupled to the coupling interface 25 and the coupling member 24 in the partially hollowed body 21 of the drive arm 20. In practice, the armature 27 is inserted into the cavity previously machined in the body 21 of the drive arm. Furthermore, an adhesive-type resin can be deposited in the bottom of the cavity to ensure that the core 26 is correctly positioned.

[0109] Furthermore, the manufacturing process 50 may include a crimping step 56 of the coupling member 24 and the coupling interface 25 to the body 21 of the drive arm 20. In practice, the holes 245, 258 provided on the coupling member 24 and the coupling interface 25 are used as guides for drilling the body 21. This allows a mechanical connector 34, 35 to be inserted into the composite material forming the body 21 through holes 245, 258. It should be noted that at the coupling interface 24, the mechanical connectors 35 pass through the core 26 so that their tips become embedded in the composite material that makes up the body 21.

[0110] The manufacturing process 50 may include a step 57 of applying a resin to coat the body 21 and at least partially the coupling member 24 and the coupling interface 25. The coating protects the functional structure of the body 21 and allows the drive arm 20 to take its final shape. In particular, during the resin application step 57, the reinforcement 27 is crimped to the body 21.

[0111] According to one embodiment of the invention, the resin application 57 can also be used to fill the hollow 28 in order to integrate the reinforcement 27 into the body 21 of the drive arm 20, even though the body 21 integrates the core 26 coupled to the coupling member 24 and the coupling interface 25. This embodiment makes it possible to produce an arm according to the embodiment illustrated in Figure 9. It should be noted that it is possible to use a layer of an elastomeric material to fill the hollow 28 and a layer of hard resin to coat the entire drive arm 20 including the filled hollow 28.

[0112] During this step, the heads of the mechanical connectors 34, 35, which crimp the coupling member 24 and the coupling interface 25, are coated with resin or the finishing layer of composite fibers. They can be seen in transparency in Figure 3. In contrast, the cheeks 250 of the coupling interface 25 and the bearing 240 of the coupling member 24 protrude from the body 21 after the resin layer is applied. The resin can be cured by catalysis using standard methods known to those skilled in the art. Alternatively, instead of coating with a hard resin such as an epoxy resin, the manufacturing process can include a draping step of the body 21 where the recess 28 is filled with resin and the coupling member 24 and the coupling interface 25 are crimped to the body 21. At least one or two layers are then draped.

[0113] Furthermore, regardless of the method of coating the drive arm 20, the process may include a sanding operation to define a smooth outer surface.

[0114] The manufacturing process 50 may include a finishing step 58 for the drive arm 20. The finishing step 58 consists of applying a finishing layer, such as a layer of paint 30, to the drive arm 20. Preferably, a paint with abrasion-resistant properties is used. The paint layer 30 protects the drive arm 20 from abrasion and thus helps to maintain the integrity of the drive arm 20 over time.

[0115] The drive arm according to the invention makes it possible to divide the mass by at least half compared to an arm of identical dimensions made of steel and mechanically assembled in accordance with the description of the state of the art.

[0116] Advantageously, the composite arm retains bending strength properties similar to those of a prior art steel arm. Indeed, the pressure exerted by the drive arm 20 on a test bench in the parked position, at mid-stroke, and at the end of its stroke is similar to that of a prior art steel arm. To measure this parameter, the drive arm is mounted on the shaft of a 350 W, 70 N / m torque motor from an ATPOUM1 1871-200 support test bench and a digital tensile and thrust dynamometer. The (MECMESIN® type AFG2500 N) is positioned at the coupling interface, which rests on the test bench. The motor carrying the drive arm is activated, and the dynamometer measures the pressure exerted by the coupling interface on the windshield. Table 1 below compares the results obtained after testing a prior art steel drive arm and a drive arm conforming to the invention. [Table 1]

[0117] The results shown in the table demonstrate that, with the exception of the parking position where the pressure exerted is not a determining factor since the arm is at rest in the parking position, similar performance is measured during sweeping for the prior art steel arm and the conformal drive arm of the invention. whether at the mid-stroke position or the end-stroke position. Therefore, the sweeping performance between these two arms is similar to each other, while the conformal arm of the invention is at least twice as light as the prior art arm.

[0118] This mass increase in the drive arm 20 allows for greater torsional flexibility. Indeed, during the sweep, the reduction in mass reduces the inertia to which the drive arm is subjected; consequently, the composite drive arm can exhibit greater torsional flexibility, whether in a clockwise or counterclockwise direction, without risk of breakage.

[0119] The flexibility of the conforming drive arm 20 of the invention can be compared to that of the prior art steel drive arm. To achieve this, the coupling member and the angled section of the drive arm are fixed to a support. The support is arranged in a plane parallel to the X, Y plane as illustrated in Figure 3. Simultaneously, the drive arm is curved along an X, Z plane perpendicular to the X, Y plane (illustrated in Figure 4). An inclinometer (“FISCO solatronic”® inclinometer Model EN 17) coupled to a dynamometer (for example a rotation dynamometer, “FACOM”® model 78090104 equipped with a J255 frame) are then secured to the coupling interface of the arm, a cylinder is placed in support between the body of the drive arm and the support to prevent the weight applied to the mass of the inclinometer and the dynamometer from distorting the measurements.Manually or mechanically, a twist of a predetermined angle is applied to the coupling interface. The angle value is monitored by measuring the inclinometer, which has been previously calibrated in its initial position. Simultaneously, the dynamometer measures the force required to achieve the desired angle. Table 2 shows the results obtained when a twist of a predetermined angle is applied to the coupling interface in a clockwise direction relative to the longitudinal direction of the drive arm body. [Table 2]

[0120] Table 3 shows measured results when applying a twist in an anti-clockwise direction following the same reference frame. [Table 3]

[0121] From Tables 2 and 3, it can be seen that when the torsion angle exceeds 7°, whether clockwise or counterclockwise, the flexibility of the conforming drive arm of the invention is more than twice that of the steel arm. This flexibility also helps to ensure relatively constant pressure on the windshield regardless of the wiper blade position and the stresses applied to the drive arm (see Table 1).

[0122] Furthermore, the inventors also compared the electrical impedance of the conforming drive arm 20 of the invention with that of the prior art steel arm. For this purpose, the inventors used an AOIP OM16 type micro-ohmmeter calibrated to 25 mΩ and 10 A for the tests. The negative electrode of the micro-ohmmeter was connected to the coupling interface 24, and the positive electrode was connected to the coupling member 25. According to this protocol, the electrical impedance of the current across the conforming drive arm of the invention was measured to be between 3.36 mΩ and 3.40 mΩ at the coupling member 25. The same test on a prior art steel arm yielded electrical impedance values ​​of approximately 3.946 mΩ.

[0123] Although the drive arm 20 according to the invention is not entirely made of electrically conductive material, it exhibits better electrical conductivity than the prior art steel arm. This advantage is conferred by the reinforcement 27, which runs through the body 21 of the drive arm 20 from one end to the other and is made up of three elements welded together.

Claims

Demands

1. A wiper arm (20) for an aircraft, the drive arm (20) comprising a body (21) extending longitudinally between a first end (22) equipped with a coupling member (24) configured to be coupled to drive means and a second end (23) equipped with a coupling interface (25) configured to support the wiper blade, characterized in that it comprises a core (26) extending inside the body (21) between the coupling interface (25) and the coupling member (24), the core (26), the coupling member (24) and the coupling interface (25) being electrically conductive and at least partially integrated into the body (21) of the drive arm (20), the body (21) comprising at least one composite material.

2. Drive arm (20) according to claim 1, wherein the core (26) comprises a metal blade extending within a recess formed inside the body (21) of composite material, the core (26) comprising metal, preferably, the core (26) comprising copper.

3. Drive arm (20) according to any one of claims 1 and 2, wherein the web (26) is coupled by welding, on the one hand, at a first end (260) to the coupling member (24), and on the other hand, at a second end (261) to the coupling interface (25), thus the web (26), the coupling member (24) and the coupling interface (25) form a frame (27) made of a single piece.

4. Drive arm (20) according to any one of claims 1 to 3, wherein the body (21) comprises, on the one hand, at least one curved section (33) with respect to at least one first plane in which the coupling member (24) extends, and on the other hand, an angled section which is arranged in the extension of the coupling member (24).

5. Drive arm (20) according to any one of claims 1 to 4, wherein the body (21) comprises a section (33) which has at least one dimension which gradually decreases along the longitudinal direction of the body (21).

6. Drive arm (20) according to any one of claims 1 to 5, wherein the body (21) is formed by an assembly of successive layers of composite fibers, the body (21) comprising at least one layer of composite fibers which has a different spatial orientation of fibers with respect to a lower layer of composite fibers and / or with respect to an upper layer of composite fibers.

7. Drive arm (20) according to any one of claims 1 to 6, wherein the composite material comprises fibers selected from the following list: carbon fibers, aramid fibers, glass fibers, aluminum fibers, steel fibers, flax fibers, hermes flax fibers, ramie fibers, hemp fibers, kenaf fibers, jute fibers, sisal fibers, silk fibers, bamboo fibers or a mixture of these fibers.

8. Drive arm (20) according to any one of claims 1 to 7, wherein the composite material comprises a matrix selected from the following list: epoxy resins, polyester resins, vinyl ester resins, phenolic resins, BMI (polybismaleimide) resins, cyanester resins or a mixture of these materials.

9. Drive arm (20) according to any one of claims 1 to 8, comprising a resin layer (29) which at least partially envelops the body (21), the core (26), the coupling member (24) and the coupling interface (25).

10. Drive arm (20) according to any one of claims 1 to 9, which comprises an external paint layer (30) which is configured to resist abrasions.

11. Drive arm (20) according to any one of claims 1 to 10, wherein the body (21) internally comprises a cellular composite material.

12. Drive arm (20) according to any one of claims 1 to 11, wherein the coupling member (24) is constituted by a rocker configured to be mounted on a shaft driven by the drive means.

13. Drive arm (20) according to any one of claims 1 to 12, wherein the coupling member (24) is crimped to the body (21) of the drive arm (20).

14. Drive arm (20) according to any one of claims 1 to 13, wherein the coupling interface (25) is crimped to the body (21) of the drive arm (20).

15. Drive arm (20) according to any one of claims 1 to 14, wherein the body (21) comprises at least one profiled section.

16. A method for manufacturing (50) a drive arm (20) according to any one of claims 1 to 15, characterized in that it comprises the following steps: Generate (51) a preform in composite material, to contour (52) the composite material preform so as to obtain the body of the drive arm according to a determined conformation, to hollow out (53) at least partially the body of the drive arm, to integrate (55) the core, the coupling interface and the coupling member into the partially hollowed body of the drive arm, and to apply (57) a resin to coat the body (21) and at least partially the coupling member (24) and the coupling interface (25).

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