High-reliability blade de-icing device and assembly method thereof

Abstract

The application belongs to the technical field of helicopter rotor system anti-icing, and particularly relates to a high-reliability blade anti-icing device and an assembling method thereof. The device comprises a nickel leading edge wrapping sheet and a heating pad, wherein the nickel leading edge wrapping sheet extends from 1R to the blade root along the span direction; the heating pad is arranged between the blade root and the nickel leading edge wrapping sheet and below the blade tip of the nickel leading edge wrapping sheet.

Description

Technical Field

[0001] This invention belongs to the field of anti-icing technology for helicopter rotor systems, specifically relating to a highly reliable blade anti-icing device and its assembly method. Background Technology

[0002] my country has complex climate conditions. In the plateau regions and coastal areas north of the Yangtze River, icing conditions are widespread in spring and winter, posing a serious threat to the safe flight of helicopters and severely restricting their use. The anti-icing system of the helicopter rotor system is a crucial component to ensure all-weather flight. As the core component of the anti-icing system, the blade anti-icing device converts electrical energy into heat energy to prevent icing on the leading edge of the blades, thus enabling the helicopter rotor blades to operate safely under moderate icing conditions.

[0003] To ensure heating capacity, protection against sand and gravel, lightning strike protection, and internal and external insulation, the anti-icing device typically consists of a heating element, a rubber insulation layer, a nickel leading-edge sheath, a conductor (one end of which is a copper braid), and a ground wire. The heating element converts electrical energy into heat energy; the rubber insulation layer separates the heating element from the nickel leading-edge sheath and the blade body, providing insulation and heat conduction; the nickel leading-edge sheath protects the anti-icing device and the blade from impacts from sand and gravel; the ground wire connects the nickel leading-edge sheath and the blade hub, forming a conductive path and providing lightning strike protection; and the conductor transmits electricity from the slip ring to the heating element.

[0004] The anti-icing device, with its complex structure, is a crucial component of a typical rotor system. Located on the upper and lower surfaces of the blade's leading edge, it experiences extreme stress due to the blade's flapping, oscillating, and torsional movements. The heating element, typically a thin copper-nickel alloy strip, is prone to fatigue fracture under these conditions. Furthermore, the increased width of the heating wire at the welding point to the conductor, to ensure weld strength, causes abrupt changes in its shape, leading to stress concentration and further fatigue fracture. The welded connection of the heating wire and conductor's copper braid creates a rough, bulging surface that directly contacts the insulating rubber, causing wear during blade operation, reducing insulation resistance, and potentially leading to short circuits. The leading-edge flap typically begins at the midpoint of the heating element's span and extends to the blade tip. Therefore, the abrupt change in stiffness at the beginning of the leading-edge flap causes stress concentration, frequently resulting in fatigue fracture of the heating element at this location. Simultaneously, to electrically connect the nickel leading-edge cladding to the propeller hub, after the anti-icing device is integrated with the propeller blade, a grounding strip must be welded to the outside of the anti-icing device and riveted to the propeller hub, a cover cloth must be bonded, and finally, a polyurethane protective strip must be bonded. Since the grounding strip, cover cloth, and polyurethane protective strip are all bonded to the outer surface of the integrated propeller blade, this complicates the blade manufacturing process and also affects aerodynamic characteristics. Because the two heating elements in the same heating zone are typically laser-cut into a single piece, the insulation resistance between the two heating elements cannot be tested. If the initial insulation resistance is lower than the design requirements, a short circuit may occur during use. Finally, the inner surface of the anti-icing device is theoretically identical in shape to the surface to be integrated with the propeller blade. If dimensional changes occur due to manufacturing reasons, fitting will be difficult, resulting in poor integration. Summary of the Invention

[0005] Purpose of the invention: To provide a highly reliable blade anti-icing device and its assembly method, overcoming the shortcomings of the original anti-icing device, such as easy short circuits, open circuits, complex processes, and poor integration adaptability.

[0006] Technical solution:

[0007] A highly reliable blade anti-icing device includes: a nickel leading edge cladding 1 and a heating pad 2. The nickel leading edge cladding 1 extends longitudinally from 1R to the blade root. Heating pads 2 are provided from the blade root to the nickel leading edge cladding and below the nickel leading edge cladding 1, except for the blade tip. The heating pad includes: two layers of insulating rubber, multiple wires, a grounding strip, and multiple heating elements. One end of the wires is a copper braided strip. The heating elements and the copper braided strip of the wires are welded together and then laid between the two layers of insulating rubber. A groove is cut into one layer of insulating rubber, and one end of the grounding strip is placed in the groove. After vulcanization, the entire device forms a heating pad. A hard rubber sheet is filled between the welding positions of two adjacent heating elements. The thickness of the hard rubber sheet is higher than the thickness of the welding point between the heating element and the copper braided strip. One end of the grounding strip is welded to the inner surface of the nickel leading edge cladding. Two heating elements in the same area are respectively laid on the rubber layer. The insulation resistance between the two heating elements is tested. If it is qualified, the two heating elements are welded together. R is the length from the blade tip to the blade rotation center.

[0008] Furthermore, the propeller root portion corresponds to 0.28R.

[0009] Furthermore, the heating element and the copper braided strip of the wire are connected by soldering.

[0010] Furthermore, the nickel leading edge sheath 1 and the heating pad 2 have the same chordal cutoff position, and their edges are both perpendicular to the inner surface of the heating pad.

[0011] Furthermore, the blade interface corresponding to the chordal cutoff position of the nickel leading edge cladding 1 and the heating pad 2 is obtuse.

[0012] Furthermore, the position between the heating element A4 and the copper braided strip A5 is optimized by shape transition treatment to reduce maximum stress.

[0013] The assembly method of the aforementioned high-reliability blade anti-icing device includes:

[0014] Step 1: Weld the copper braided strip A5 to the heating element A4, and weld the nickel leading edge cladding 1 to the grounding strip A3;

[0015] Step 2: Lay the first layer of insulating rubber A1 flat in the mold;

[0016] Step 3: Lay the heating element A4 on the insulating rubber A1 according to the chord and span dimensions and position requirements;

[0017] Step 4: Check the insulation resistance between adjacent heating elements A4. If there are no problems, solder the heating elements A4 in the same area.

[0018] Step 5: Lay a hard plastic sheet A6 between the adjacent positions of the copper braided tape A5 and the heating element A4, and lay the second layer of insulating rubber A1 on the first layer of insulating rubber A1 to cover the wire A2, copper braided tape A5 and heating element A4 to form heating pad 2.

[0019] Step 6: Vulcanize and mold the heating pad 2;

[0020] Step 7: On the heating pad 2, at the position corresponding to the grounding strip A3, cut out a groove for placing the grounding strip A3;

[0021] Step 8: Place the grounding tape A3 in the groove of the heating pad 2 and attach it. Then attach the heating pad 2 to the nickel leading edge cladding 2.

[0022] Step 9: Weld the grounding strip A3 to the nickel leading edge cladding 2 to form a complete blade anti-icing device.

[0023] Beneficial effects:

[0024] The high-reliability blade anti-icing device provided by this invention, while maintaining the original heating function, reduces the maximum stress on the heating element by optimizing the shape of the transition area between the heating element and the copper braided strip and extending the nickel leading edge cladding to 0.28R. By filling the welding position between the copper braided strip A5 and the heating element A4 with a slightly thicker hard rubber sheet, wear on the insulating rubber at the welding position is reduced, thus lowering the risk of insulation resistance decrease. Designing the heating elements in the same area as disconnected rather than circuitous allows for increased insulation detection measures, significantly reducing the short-circuit failure rate after the heating pad vulcanizes. Finally, compared to traditional heating devices, it eliminates processes such as "welding the grounding strip to the outside of the anti-icing device and riveting it to the blade hub, bonding the cover cloth, and finally bonding the polyurethane protective strip," and adds assembly margin for the integration of the blade anti-icing device and the blade, enhancing adaptability and improving manufacturability. This solution is highly operable and has extremely low additional costs. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A view of the heating device along the blade span;

[0027] Figure 2 This is a sectional view of the heating device along the chord of the blades;

[0028] Figure 3 This is a diagram of the heating pad's layer structure.

[0029] Among them, nickel leading edge cladding 1, heating pad 2, insulating rubber A1, wire A2, grounding tape A3, heating element A4, copper braided tape A5, and rigid rubber sheet A6. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0032] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing and simplifying the invention, and should not be construed as limiting the invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0033] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, encompassing both direct connection and indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0034] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0035] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0036] like Figure 1-3 A highly reliable blade anti-icing device includes a nickel leading edge cladding 1 and a heating pad 2. The nickel leading edge cladding 1 extends longitudinally from 1R to the blade root, for example, 0.28R. Heating pads 2 are installed between 0.28R and the nickel leading edge cladding 1, as well as below the nickel leading edge cladding 1 (except near the blade tip). The areas of the blade where icing is not allowed and where self-icing is not possible are covered by the heating pads, thereby ensuring that the blade can operate normally in icy environments. R is the length from the blade tip to the blade rotation center.

[0037] The nickel leading edge sheath 1 and the heating pad 2 have the same tangential cutoff position, and their edges are perpendicular to the inner surface of the heating pad.

[0038] The heating pad 2 includes: two layers of insulating rubber A1, multiple wires A2 (one end of which is a copper braided strip A5), a grounding strip A3, multiple heating elements A4, and a rigid rubber sheet A6. The heating elements A4 are welded to the copper braided strip A5 of the wires A2, and then laid on a layer of insulating rubber A1 according to the relevant position requirements.

[0039] The welding between two adjacent heating elements A4 on the insulating rubber A1 and the filling of the area of ​​copper braided tape A5 with hard rubber sheet A6 are carried out. At the same time, the insulating rubber at the location of grounding tape A3 is cut out to create a groove, and one end of grounding tape A3 is placed in the groove. One end of grounding tape A3 is welded to the inner surface of nickel leading edge sheath 1.

[0040] After placement, another layer of insulating rubber A1 is laid, and after vulcanization, heating pad 2 is formed. Heating pad 2 with this arrangement can ensure the position requirements of each component during vulcanization, improve the pass rate, reduce process steps, and at the same time allow for assembly margins when integrating the blade anti-icing device with the blade.

[0041] The thickness of the rigid rubber sheet A6 is greater than the thickness of the weld joint between the heating element A4 and the copper braided strip A5. After vulcanization, the slightly thicker rigid rubber sheet A6 reduces wear on the insulating rubber at the weld area, lowering the risk of decreased insulation resistance.

[0042] Finally, the rubber part of the heating pad 2 is cut and trimmed according to the shape requirements, and the exposed grounding strip A3 is glued to the nickel front edge cladding 1 at a certain position.

[0043] Furthermore, the position between the heating element A4 and the copper braided strip A5 is optimized by shape transition treatment to reduce maximum stress.

[0044] Furthermore, extending the nickel leading edge cladding 1 from the initial position to 0.28R can alleviate stress concentration caused by abrupt changes in stiffness and reduce the maximum stress.

[0045] Furthermore, the welding between two adjacent heating elements A4 on the insulating rubber A1 and the filling of the area of ​​copper braided tape A5 with hard rubber sheet A6 can effectively prevent the heating elements from shifting on the insulating rubber, resulting in poor molding quality.

[0046] Furthermore, the thickness of the hard rubber sheet A6 is slightly higher than the thickness of the weld between the heating element A4 and the copper braided strip A5, in order to prevent the weld from causing wear on the insulating rubber A1.

[0047] Furthermore, welding the grounding strip A3 to the inner surface of the nickel leading edge cladding 1 eliminates the need for subsequent steps of bonding the grounding strip A3, the covering cloth, and the polyurethane protective strip to the outer surface of the nickel leading edge cladding 1. This reduces the number of operation steps, improves processability, and avoids any impact on the blade airfoil.

[0048] Furthermore, the two heating elements in the same area are made into two separate pieces. After being laid onto the rubber layer, the insulation resistance between the two heating elements is tested. Only after passing the test are the two heating elements welded together. Compared to making the heating elements in the same area into one piece, insulation problems can be effectively detected before the heating pad is vulcanized, thus improving the product qualification rate.

[0049] Furthermore, the nickel leading edge cladding 1 and the chordal cutoff of the heating pad 2 are made perpendicular, while the corresponding interface of the blade is obtuse, thus allowing for adjustment and preventing assembly difficulties due to the large chordal dimension of the heating device.

[0050] The high-reliability blade anti-icing device provided by this invention, while maintaining the original heating function, reduces the maximum stress on the heating element by optimizing the shape of the transition area between the heating element and the copper braided strip and extending the nickel leading edge cladding to 0.28R. By filling the welding position between the copper braided strip A5 and the heating element A4 with a slightly thicker hard rubber sheet, wear on the insulating rubber at the welding position is reduced, thus lowering the risk of insulation resistance decrease. Designing the heating elements in the same area as disconnected rather than circuitous allows for increased insulation detection measures, significantly reducing the short-circuit failure rate after the heating pad vulcanizes. Finally, compared to traditional heating devices, it eliminates processes such as "welding the grounding strip to the outside of the anti-icing device and riveting it to the blade hub, bonding the cover cloth, and finally bonding the polyurethane protective strip," and adds assembly margin for the integration of the blade anti-icing device and the blade, enhancing adaptability and improving manufacturability. This solution is highly operable and has extremely low additional costs.

[0051] An assembly method for a high-reliability blade anti-icing device according to an embodiment of this application includes:

[0052] Step 1: Weld the copper braided strip A5 to the heating element A4, and weld the nickel leading edge cladding 1 to the grounding strip A3;

[0053] Step 2: Lay the first layer of insulating rubber A1 flat in the mold;

[0054] Step 3: Lay the heating element A4 on the insulating rubber A1 according to the chord and span dimensions and position requirements;

[0055] Step 4: Check the insulation resistance between adjacent heating elements A4. If there are no problems, solder the heating elements A4 in the same area.

[0056] Step 5: Lay a hard plastic sheet A6 between the adjacent positions of the copper braided tape A5 and the heating element A4, and lay the second layer of insulating rubber A1 on the first layer of insulating rubber A1 to cover the wire A2, copper braided tape A5 and heating element A4 to form heating pad 2.

[0057] Step 6: Vulcanize and mold the heating pad 2;

[0058] Step 7: On the heating pad 2, at the position corresponding to the grounding strip A3, cut out a groove for placing the grounding strip A3;

[0059] Step 8: Place the grounding tape A3 in the groove of the heating pad 2 and attach it. Then attach the heating pad 2 to the nickel leading edge cladding 2.

[0060] Step 9: Weld the grounding strip A3 to the nickel leading edge cladding 2 to form a complete blade anti-icing device.

[0061] Working principle:

[0062] Step 4 designs the heating element A4 in the same area as an open circuit rather than a closed circuit. The insulation resistance between adjacent heating elements A4 is checked before welding, significantly reducing the short-circuit failure rate after the heating pad is vulcanized. Step 5 fills the welding area with a slightly thicker hard rubber sheet A6, reducing wear on the insulating rubber at the welding point and lowering the risk of insulation resistance degradation. Finally, the structure of embedding the grounding strip A3 between the nickel leading edge sheath 2 and the heating pad 1 reduces the steps of "welding the grounding strip to the outside of the anti-icing device and riveting it to the propeller hub, bonding the cover cloth, and finally bonding the polyurethane protective strip," improving manufacturability.

[0063] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A highly reliable blade anti-icing device, characterized in that, include: Nickel leading edge cladding and heating pad; the nickel leading edge cladding extends longitudinally from 1R to the propeller root. Heating pads are installed from the blade root to the nickel leading edge sheath and below the nickel leading edge sheath, except at the blade tip. The heating pads consist of two layers of insulating rubber, multiple wires, a grounding strip, and multiple heating elements. One end of each wire is a copper braided strip. The heating elements and the copper braided strip of the wires are welded together and then laid between the two layers of insulating rubber. A groove is cut into one layer of insulating rubber, and one end of the grounding strip is placed in the groove. After vulcanization, the entire heating pad is formed. A hard rubber sheet is filled between the welding positions of two adjacent heating elements. The thickness of the hard rubber sheet is higher than the thickness of the welding point between the heating element and the copper braided strip. One end of the grounding strip is welded to the inner surface of the nickel leading edge sheath. Two heating elements in the same area are respectively laid on the rubber layer. The insulation resistance between the two heating elements is tested. If it is qualified, the two heating elements are then welded together. R is the length from the blade tip to the blade rotation center.

2. The high-reliability blade anti-icing device according to claim 1, characterized in that, The propeller root section corresponds to 0.28R.

3. The high-reliability blade anti-icing device according to claim 2, characterized in that, The heating element and the copper braided strip of the wire are connected by soldering.

4. The high-reliability blade anti-icing device according to claim 2, characterized in that, The nickel leading edge cladding has the same tangential cutoff position as the heating pad, and the edges are perpendicular to the inner surface of the heating pad.

5. The high-reliability blade anti-icing device according to claim 1, characterized in that, The blade interface corresponding to the tangential cutoff position of the nickel leading edge cladding and the heating pad is obtuse.

6. The high-reliability blade anti-icing device according to claim 2, characterized in that, The position between the heating element and the copper braided strip is optimized by shape transition to reduce maximum stress.

7. A method for assembling a high-reliability blade anti-icing device as described in any one of claims 2-6, characterized in that, include: Step 1: Weld the copper braided strip to the heating element, and weld the nickel leading edge cladding and grounding strip; Step 2: Lay the first layer of insulating rubber flat in the mold; Step 3: Lay the heating elements on the insulating rubber according to the chordal and spanwise dimensions and positions; Step 4: Check the insulation resistance between adjacent heating elements. If there are no problems, solder the heating elements in the same area. Step 5: Lay a hard rubber sheet between the copper braided tape and the welding point of the heating element, and lay the second layer of insulating rubber on the first layer of insulating rubber to cover the wire, copper braided tape and heating element to form a heating pad; Step 6: Vulcanize and mold the heating pad; Step 7: Cut out a groove on the heating pad at the position corresponding to the grounding strip to place the grounding strip; Step 8: Place the grounding tape in the groove of the heating pad and attach it, then attach the heating pad to the nickel leading edge cladding; Step 9: Weld the grounding strip to the nickel leading edge cladding to form a complete blade anti-icing device.

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