An internal wire corrosion protection method for an airborne rotating speed sensor and the airborne rotating speed sensor

Abstract

The application relates to the technical field of engine rotating speed testing, and discloses an internal wire corrosion protection method of an airborne rotating speed sensor and the airborne rotating speed sensor, which comprises the following steps: selecting a welding wire capable of inhibiting the galvanic corrosion effect between two metal wires, and welding a dissimilar metal connecting structure; coating a plurality of layers of insulating paint on the welded part after welding is completed and the connection transition area between the welding wire and the two sides of the wire, so as to isolate the galvanic contact between the two metal wires; and after the plurality of layers of insulating paint are coated and formed, a heat-shrinkable sleeve is sleeved on the welded part and the coated area and is subjected to heat shrinkage treatment. Through the cooperation of potential difference inhibition, multi-layer insulation isolation and heat-shrinkable sleeve protection, the galvanic corrosion tendency of the dissimilar metal connecting part is reduced, the corrosion ion conduction path is cut off, the corrosion resistance of the internal wire connection of the sensor is improved, and the stability and reliability of the rotating speed signal transmission are ensured.

Description

Technical Field

[0001] This invention relates to the field of engine speed testing technology, specifically to a method for protecting the internal wires of an airborne speed sensor from corrosion and an airborne speed sensor. Background Technology

[0002] Engine speed is a crucial design and performance indicator, as well as a vital parameter for engine control and health management. Airborne speed sensors must be directly mounted on hot-end components of the engine for signal extraction. Due to engine operating conditions, these sensors face a harsh dual-temperature environment: the front-end sensing area operates at approximately 180°C, while the rear-end signal transmission area can reach temperatures as high as 500°C.

[0003] To meet the signal transmission and heat resistance requirements under the aforementioned dual-temperature conditions, existing sensors typically employ a combination of dissimilar metal wires. The sensing element uses silver-plated copper wire as the signal line, leveraging its good compatibility with the coil's enameled wire and its high conductivity. The high-temperature signal transmission line uses nickel wire to utilize its heat resistance, ensuring stable operation below 600℃. The two are electrically connected by welding.

[0004] However, there is a significant galvanic corrosion potential difference between the silver-plated copper wire and the nickel wire. In actual working environments such as high temperature, humidity, and salt spray, this dissimilar metal connection is prone to forming a galvanic cell, initiating galvanic corrosion. The accumulation and spread of corrosion products will cause the solder joint area to gradually corrode and break, ultimately leading to the interruption of speed signal transmission and affecting the reliable operation of the engine control system. Summary of the Invention

[0005] In view of this, the present invention provides a method for protecting the internal wires of an airborne speed sensor from corrosion and an airborne speed sensor, so as to solve the problems mentioned in the background art.

[0006] In a first aspect, the present invention provides a method for protecting the internal wires of an airborne speed sensor from corrosion. The airborne speed sensor has an internal dissimilar metal connection structure formed by welding a first metal wire and a second metal wire, and there is a corrosion potential difference between the first metal wire and the second metal wire. The corrosion protection method includes: selecting a welding wire capable of suppressing the galvanic corrosion effect between the first metal wire and the second metal wire, and welding the dissimilar metal connection structure; applying multiple layers of insulating varnish to the welded area and the transition area between the welding wire and the two metal wires to isolate the galvanic contact between the first metal wire and the second metal wire; and after the multiple layers of insulating varnish are coated and formed, fitting a heat-shrinkable sleeve onto the welded area and the coated area and performing heat-shrink treatment.

[0007] Beneficial Effects: This application addresses the problem of galvanic corrosion caused by the formation of galvanic cells in high-temperature, humid, and salt spray environments between silver-plated copper wire and nickel wire due to corrosion potential differences, leading to solder joint corrosion, wire breakage, and signal interruption. It constructs a technical design combining potential difference suppression, multi-layer isolation, and sealing protection. Welding wire capable of suppressing galvanic corrosion effects is selected for welding to reduce the corrosion driving force at the dissimilar metal connection and decrease the tendency for electrochemical corrosion. By applying multiple layers of insulating varnish to the welding area and the transition area between the welding wire and the two side conductors, the galvanic contact between the first and second metal conductors can be isolated, thereby cutting off the conduction path of corrosion ions between the dissimilar metals. A heat-shrinkable sleeve is fitted over the insulating varnish and then heat-shrinked to form a protective outer layer, preventing the insulating varnish layer from being scratched or damaged by external forces, enhancing the isolation effect, and applying elastic force to strengthen the bonding ability of the welding area. Through the above design, the tendency for corrosion is reduced, the ion pathway is cut off, the protective capability is strengthened, and the corrosion resistance of the dissimilar metal conductor connection is improved, thereby ensuring the stability and reliability of speed signal transmission.

[0008] In some embodiments, the coating of the multilayer insulating varnish adopts a molding process of layer-by-layer coating and curing. The multilayer insulating varnish includes a primer layer, an intermediate varnish layer and a topcoat layer, and the sum of the thicknesses of each varnish layer is ≤0.2mm.

[0009] Beneficial effects: Layered coating allows each layer of paint to spread evenly and form a dense film, avoiding defects such as pinholes or bubbles caused by a single thick coat. Layer-by-layer curing ensures a tight and strong bond between layers. The total thickness of the multi-layer insulating varnish is controlled within 0.2mm, providing sufficient insulation and structural strength while preventing excessive thickness from reducing flexibility and causing stress concentration. This allows the varnish film to expand and deform along with the substrate during temperature cycling without cracking or peeling, thus maintaining the integrity and longevity of the protective layer.

[0010] In some embodiments, the thickness of the primer layer is 0.03mm-0.05mm, the thickness of the intermediate paint layer is 0.06mm-0.08mm, and the thickness of the topcoat layer is 0.04mm-0.06mm.

[0011] Beneficial effects: The primer layer, with a thickness of 0.03mm to 0.05mm, is relatively thin, ensuring full wetting and firm adhesion to the metal substrate. The intermediate coat, with a thickness of 0.06mm to 0.08mm, serves as the main insulating layer, providing the primary isolation thickness and insulation strength. The topcoat layer, with a thickness of 0.04mm to 0.06mm, provides surface sealing and gloss protection. Through the rational distribution of the three coat thicknesses, an optimized match of adhesion performance, insulation effect, and surface protection function is achieved within the constraint of total thickness. Each coat layer has a clearly defined function, resulting in overall reliability.

[0012] In some embodiments, during the layer coating step, after each layer is coated, a segmented heating and drying process is performed, controlling the heating rate and holding time; after the current layer is completely dry and formed, the next layer is coated.

[0013] Beneficial effects: Each paint layer is applied using a segmented heating and drying method, controlling the heating rate and holding time to allow solvents and low-molecular-weight substances to slowly escape from the paint film. This prevents rapid heating from causing the surface to dry first while the interior bubbles or accumulates internal stress. The next layer is applied only after the current layer is completely dry and set, avoiding interlayer dissolution or undercoating, ensuring clear interfaces and good adhesion between layers.

[0014] In some embodiments, the insulating varnish is a high-temperature resistant flexible silicone insulating varnish.

[0015] Beneficial effects: The insulating varnish is made of high-temperature resistant flexible silicone material, which maintains stable insulation and isolation performance in the high-temperature operating section of the sensor. Its flexible characteristics can effectively buffer the deformation stress caused by the thermal expansion difference of dissimilar metals and prevent the varnish film from cracking during temperature cycling.

[0016] In some embodiments, the heat shrink tubing is fitted over the outside of the multilayer insulating varnish.

[0017] Beneficial effects: The inner insulating varnish isolates against galvanic corrosion, the middle filling layer buffers thermal expansion stress and provides support, and the outer heat-shrink tubing tightly presses the internal layers together through shrinkage, eliminating gaps and providing external protection and constraint to prevent loosening or displacement of the internal structure. In this design, the functions of each layer are complementary, effectively releasing internal thermal stress, strengthening the overall structure, and improving the long-term stability of dissimilar metal connections.

[0018] In some embodiments, the heat shrink tubing is a highly elastic flame-retardant heat shrink tubing, and the material of the heat shrink tubing is one of polyvinylidene fluoride, fluororubber, polytetrafluoroethylene, or silicone rubber.

[0019] Beneficial effects: High elasticity ensures that the heat-shrinkable tubing can tightly fit the shape of the internal structure after heat shrinking, eliminating gaps and providing continuous radial restraint; flame-retardant properties meet the fire safety requirements of airborne equipment for aero engines; all the above materials have good high-temperature resistance and chemical inertness, enabling long-term stable use in the high-temperature environment of the sensor working section, and do not react with the protected insulating varnish layer. The heat-shrinkable tubing can provide a durable and reliable external barrier for the internal anti-corrosion structure.

[0020] In some embodiments, the corrosion protection method further includes: applying a potting filler to the outside of the heat shrink tubing to form a filler layer.

[0021] Beneficial effects: The filler layer provides auxiliary support for the internal solder joints, and together with the heat shrink tubing, it alleviates stress concentration caused by the difference in thermal expansion coefficients between the silver-plated copper wire and the nickel wire, which helps reduce the risk of fatigue cracking of the solder joints under temperature alternation. In addition, the filler layer increases the mass and damping around the heat shrink tubing, further buffering and protecting the solder joints under vibration conditions, thereby improving the stability of the connection structure under the vibration conditions of aero-engines.

[0022] In some embodiments, the airborne speed sensor is filled with inert gas, and the sensor housing and electrical connector are welded and sealed in an inert gas environment.

[0023] Beneficial effects: The airborne speed sensor is filled with inert gas, and the housing and electrical connectors are welded and sealed in an inert atmosphere to form a closed space, which isolates external corrosive media and eliminates the effect of internal oxygen conditions on electrochemical corrosion.

[0024] In some embodiments, the first metal wire is a silver-plated copper wire, and the second metal wire is a nickel wire; the welding is performed using argon arc welding. The welding wire is a nickel-based Monel welding wire with the following composition by mass percentage: Ni 62%-69%, Cu 28%-32%, Ti 1.5%-3%, Mn≤4%, Fe≤2.5%; or the welding wire is a copper-nickel alloy welding wire with the following composition by mass percentage: Ni 29%-32%, Mn≤1.0%, Fe 0.4%-0.7%, Cu balance.

[0025] Beneficial effects: Silver-plated copper wire meets the welding compatibility and high conductivity requirements of the inductor and coil enameled wire, while nickel wire meets the heat resistance requirements of 500℃ in the high-temperature range. Nickel-based Monel welding wire and copper-nickel alloy welding wire are electrochemically compatible with silver-plated copper wire and nickel wire, effectively suppressing galvanic corrosion between dissimilar metals. Argon arc welding provides inert gas protection during the welding process, preventing oxidation of the weld metal at high temperatures, ensuring the metallurgical quality and conductivity of the weld joint, and giving the weld itself good initial corrosion resistance, providing a reliable foundation for subsequent coating, potting, and sealing protective measures.

[0026] Secondly, the present invention also provides an airborne speed sensor, comprising a coil, a magnet, a housing, a filling layer, a signal transmission line, and an electrical connector. The coil is disposed in the front sensing region inside the housing, the magnet is adapted to cooperate with the coil to generate an inductive signal, and the electrical connector is mounted on the rear end of the housing. The signal transmission line comprises a silver-plated copper wire and a nickel wire. One end of the silver-plated copper wire is soldered to the coil, one end of the nickel wire is soldered to the other end of the silver-plated copper wire, and the other end of the nickel wire extends to the rear end of the housing and is electrically connected to the terminal of the electrical connector. The silver-plated copper wire and the nickel wire are connected and protected using the corrosion protection method described above.

[0027] Beneficial effects: The signal transmission line uses segmented connections of silver-plated copper wire and nickel wire. One end of the silver-plated copper wire is soldered to the coil, and the other end is soldered to the nickel wire. The nickel wire extends to the rear end of the housing and connects to the electrical connector. The connection between the silver-plated copper wire and the nickel wire is protected according to the aforementioned corrosion protection method, effectively reducing corrosion tendency, cutting off ion pathways, strengthening protection capabilities, and improving the corrosion resistance of dissimilar metal wire connections, thus enabling the airborne speed sensor signal transmission to have good stability and reliability.

[0028] In some embodiments, the airborne speed sensor is a dual-temperature-segment sensor, wherein the upper limit of the operating temperature of the sensing part of the sensor is 180°C, and the upper limit of the operating temperature of the signal transmission section of the sensor is 500°C; and / or, The airborne speed sensor is filled with inert gas.

[0029] Beneficial effects: The airborne speed sensor can operate reliably for extended periods under dual-temperature conditions, with the sensing section at 180°C and the signal transmission section at 500°C, providing stable signal transmission for aero-engine speed measurement. Simultaneously, the airborne speed sensor is filled with inert gas, isolating it from external corrosive environments and eliminating the possibility of electrochemical corrosion caused by internal oxygen conditions. Combined with the aforementioned filling and sealing welding design, this ensures that the internal environment of the airborne speed sensor remains inert during operation, guaranteeing the long-term corrosion resistance stability of the dissimilar metal connection structure and the reliability of signal transmission. Attached Figure Description

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 This is a schematic flowchart of the corrosion protection method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the internal structure of an airborne speed sensor according to an embodiment of the present invention; Figure 3 for Figure 2 A magnified view of a portion of point A in the middle.

[0032] Explanation of reference numerals in the attached figures: 1. Coil; 2. Magnet; 3. Housing; 4. Filler layer; 5. Signal transmission line; 6. Electrical connector; 7. Heat shrink tubing. Detailed Implementation

[0033] 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.

[0034] The following is combined with Figures 1 to 3 The following describes embodiments of the present invention.

[0035] According to an embodiment of the present invention, a method for corrosion protection of internal wires in an airborne speed sensor is provided, which is used to solve the problem of galvanic corrosion and wire breakage caused by corrosion potential difference between silver-plated copper wire and nickel wire inside the airborne speed sensor.

[0036] The airborne speed sensor has an internal dissimilar metal connection structure formed by welding a first metal wire and a second metal wire, and there is a corrosion potential difference between the first metal wire and the second metal wire.

[0037] The corrosion protection method includes: selecting a welding wire capable of suppressing the galvanic corrosion effect between the first and second metal wires to weld the dissimilar metal connection structure; applying multiple layers of insulating varnish to the welded area and the transition area between the welding wire and the two metal wires to isolate the galvanic contact between the first and second metal wires; and after the multiple layers of insulating varnish are coated and formed, fitting a heat-shrinkable sleeve 7 onto the welded area and the coated area and performing heat-shrink treatment. The transition area is defined as the region extending 5mm-10mm axially from the weld boundary along both the first and second metal wires.

[0038] The corrosion protection method provided in this embodiment, such as Figures 1 to 3 As shown, the specific steps are as follows: Step 1: Welding of dissimilar metals.

[0039] The first metal conductor is silver-plated copper wire, and the second metal conductor is nickel wire; the welding wire is nickel-based Monel welding wire, and the silver-plated copper wire and the nickel wire are welded using argon arc welding.

[0040] The specific welding process steps for TIG welding are as follows: 1. Test assembly of the welding sample: Perform a test assembly of the silver-plated copper wire and nickel wire to be welded. 2. Cleaning of the sample to be welded: Clean the silver-plated copper wire and nickel wire to be welded. 3. Setting of welding process parameters: The TIG welding process parameters need to be confirmed through actual process testing. The process parameters are: welding current (6-10) A, argon flow rate (6-8) L / min, tungsten electrode diameter 1.6 mm. 4. Formal welding: It is recommended to use manual TIG welding to ensure that all cores of the two types of conductors are fused together after welding.

[0041] The welding wire is a nickel-based Monel welding wire, and its composition by mass percentage is: Ni 62%-69%, Cu 28%-32%, Ti 1.5%-3%, Mn≤4%, Fe≤2.5%.

[0042] In the first embodiment, the composition of the nickel-based Monel welding wire, by mass percentage, is: Ni 65%, Cu 30%, Ti 2%, Mn 1.5%, Fe 1.2%, with the balance being unavoidable impurities. The sum of the mass percentages of all components is 100%.

[0043] In the second embodiment, the composition of the nickel-based Monel welding wire, by mass percentage, is: Ni 62%, Cu 32%, Ti 2.5%, Mn 2%, Fe 1.5%, with the balance being unavoidable impurities.

[0044] In the third embodiment, the composition of the nickel-based Monel welding wire, by mass percentage, is: Ni 69%, Cu 28%, Ti 1.5%, Mn 1%, Fe 0.5%, with the balance being unavoidable impurities.

[0045] In the fourth embodiment, the composition of the nickel-based Monel welding wire, by mass percentage, is: Ni 66%, Cu 29%, Ti 3.0%, Mn 1%, Fe 1%, with the balance being unavoidable impurities.

[0046] The welding wire is a copper-nickel alloy welding wire, and its composition by mass percentage is: Ni 29%-32%, Mn≤1.0%, Fe 0.4%-0.7%, Cu balance.

[0047] In the first embodiment, the composition of the copper-nickel alloy welding wire by mass percentage is: Ni 30.5%, Mn 0.6%, Fe 0.5%, Cu balance, i.e. Cu is 68.4%, and the sum of the mass percentages of each component is 100%.

[0048] In the second embodiment, the composition of the copper-nickel alloy welding wire by mass percentage is: Ni 29.0%, Mn 0.3%, Fe 0.7%, Cu balance, i.e., Cu is 70.0%.

[0049] In the third embodiment, the composition of the copper-nickel alloy welding wire by mass percentage is: Ni 32.0%, Mn 0.9%, Fe 0.4%, Cu balance, i.e., Cu is 66.7%.

[0050] In the fourth embodiment, the composition of the copper-nickel alloy welding wire by mass percentage is: Ni 31.0%, Mn 0.1%, Fe 0.6%, Cu balance, i.e., Cu is 68.3%.

[0051] In this embodiment, the electrochemical properties of the nickel-based Monel welding wire are compatible and matched with those of the silver-plated copper wire and nickel wire, which reduces the potential gradient in the weld zone and can effectively suppress galvanic corrosion between dissimilar metals.

[0052] Among them, the silver-plated copper wire meets the welding compatibility and high conductivity requirements of the inductor and the enameled wire of coil 1, while the nickel wire meets the heat resistance requirement of 500℃ in the high-temperature section. Argon arc welding provides inert gas protection during the welding process, preventing the weld metal from oxidizing at high temperatures, ensuring the metallurgical quality and conductivity of the weld joint, and giving the weld itself good initial corrosion resistance, providing a reliable foundation for subsequent coating, potting and sealing protective measures.

[0053] Step 2: Apply multiple layers of insulating varnish.

[0054] After welding, the welded areas and the transition areas extending from the weld seam towards the silver-plated copper and nickel wires on both sides are coated with multiple layers of high-temperature resistant flexible silicone insulating varnish to isolate the galvanic contact between the two metals. The multi-layer insulating varnish is applied using a layer-by-layer coating and curing process. The multi-layer insulating varnish includes a primer layer, an intermediate varnish layer, and a topcoat layer, and the sum of the thicknesses of each varnish layer is ≤0.2mm.

[0055] First, apply a primer layer. For solder joints, use a manual brushing process; for the transition area between the solder joint and the lead wire, use a combination of brushing and dipping to ensure a natural transition. The primer layer thickness is controlled between 0.03mm and 0.05mm. This thin thickness ensures full wetting and firm adhesion to the metal substrate. After the primer is applied, place the workpiece in a temperature chamber for staged heating and drying. Starting from room temperature, gradually increase the temperature to the insulating varnish curing temperature (180℃ to 200℃) at a set rate not exceeding 5℃ / min. Hold the temperature at multiple temperature steps for at least 2 hours to control the slow escape of solvents and low-molecular-weight substances, preventing rapid heating that could cause the surface of the varnish to dry prematurely, resulting in blistering or stress buildup. After the holding period, cool the workpiece in the oven until the primer layer is completely dry and set.

[0056] Next, the intermediate layer of varnish is applied; an intermediate insulating varnish is brushed onto the surface of the primer layer, with a thickness controlled between 0.06 mm and 0.08 mm. As the main insulating layer, the intermediate layer primarily provides insulation thickness and strength. After coating, a segmented heating and drying process is performed, controlling the heating rate and holding time to ensure sufficient release of internal stress within the intermediate varnish film. Once the intermediate varnish is completely dry and set, the topcoat layer is then applied.

[0057] Next, the topcoat layer is applied; the thickness of the topcoat layer is controlled between 0.04mm and 0.06mm. The topcoat layer mainly provides surface sealing and gloss protection, and enhances the density of the paint film. After coating, the same segmented heating and drying process as the previous two layers is performed.

[0058] Layered coating allows each layer of paint to spread evenly and form a dense film, avoiding defects such as pinholes or bubbles that can occur with a single thick coat. Layer-by-layer curing ensures a tight and strong bond between the layers.

[0059] Each paint layer is applied using a segmented heating and drying method, controlling the heating rate and holding time to allow solvents and low-molecular-weight substances to slowly escape from the paint film. This prevents rapid heating from causing the surface to dry first while the interior bubbles or accumulates internal stress. The next layer is applied only after the current layer is completely dry and set, avoiding interlayer dissolution or undercoating, ensuring clear interfaces and good adhesion between layers.

[0060] The total thickness of the three-layer coating does not exceed 0.2mm. This thickness range ensures sufficient insulation and structural strength while preventing excessive coating thickness from causing a decrease in flexibility and stress concentration. It also allows the coating to expand and deform along with the substrate during temperature cycling without cracking or peeling, thus maintaining the integrity and longevity of the protective layer.

[0061] This step, through the reasonable distribution of the thickness of the three coating layers, achieves an optimized match of adhesion performance, insulation effect and surface protection function under the constraint of total thickness. The function of each coating layer is clear and the overall system is reliable.

[0062] The insulating varnish is made of high-temperature resistant flexible silicone. The use of high-temperature resistant flexible silicone material ensures stable insulation and isolation performance during the high-temperature operating range of the sensor. Furthermore, its flexibility effectively buffers the deformation stress caused by the thermal expansion difference between the silver-plated copper wire and the nickel wire, preventing the varnish film from cracking during temperature cycling.

[0063] Step 3: Install the heat shrink tubing 7.

[0064] After all the multi-layer insulating varnish has been applied and cured, heat shrink tubing 7 is selected according to the outer diameter of the welded area and the coated area. The heat shrink tubing 7 can be pre-inserted with wires and left in the designated position. The heat shrink tubing 7 is then fitted onto the protected area, covering the welded area and the coated area. A heat gun or other heating tool is then used to heat the tubing evenly, causing it to shrink and fit tightly against the internal structure.

[0065] The heat shrink tubing 7 is a highly elastic, flame-retardant heat shrink tubing. The material of the heat shrink tubing 7 is one of polyvinylidene fluoride, fluororubber, polytetrafluoroethylene, or silicone rubber. High elasticity ensures that the heat shrink tubing 7 can tightly fit the internal structure after heat shrinking, eliminating gaps and providing continuous radial restraint; its flame-retardant properties meet the fire safety requirements of airborne equipment for aero-engines; all the aforementioned materials possess excellent high-temperature resistance and chemical inertness, enabling long-term stable use in the high-temperature environment of the sensor's operating section, and it does not react with the protected insulating varnish layer. The heat shrink tubing 7 provides a durable and reliable external barrier for the internal corrosion-resistant structure.

[0066] In this embodiment, the solder joints formed by the nickel-based Monel welding wire have a smooth surface and low oxidation level, which can provide a good adhesion substrate for the insulating varnish. Moreover, the multilayer flexible insulating varnish, while buffering the stress generated by the thermal expansion difference of dissimilar metals, and in conjunction with the radial compression of the heat shrink tubing 7, forms a gradient sealing structure from the inside to the outside of the solder joint.

[0067] Step 4: Potting and filling to form the filling layer 4.

[0068] After the heat shrink tubing 7 is installed, the outside of the heat shrink tubing 7 is potted and filled to form a filling layer 4.

[0069] In practice, a high-temperature resistant and elastic potting material, such as silicone potting compound, is selected and fully filled around the heat shrink tubing 7, ensuring the filling material completely covers the welding protection area. The potting material cures at room temperature or under heating conditions, forming a compact filling layer 4. The filling material inside the sensor, typically potting compound, acts as a buffer against vibration at the welding point. The filling layer 4 provides auxiliary support for the weld joint, working together with the heat shrink tubing 7 to alleviate stress concentration caused by the difference in thermal expansion coefficients between the silver-plated copper wire and the nickel wire, thus reducing the risk of fatigue cracking during temperature fluctuations. Furthermore, the filling layer 4 increases the mass and damping around the heat shrink tubing 7, further buffering and protecting the weld joint under vibration conditions, thereby improving the stability of the connection structure under aero-engine vibration conditions.

[0070] The inner insulating varnish isolates the structure from galvanic corrosion, while the middle heat-shrink tubing 7 tightly presses the internal layers together through shrinkage, eliminating gaps and providing external protection and constraint to prevent loosening or displacement of the internal structure. The outer filler layer 4 buffers thermal expansion stress and provides support. In this embodiment, the functions of each layer are complementary, effectively releasing internal thermal stress, strengthening the overall integrity of the structure, and improving the long-term stability of dissimilar metal connections.

[0071] Step 5: Inert gas filling and sealing.

[0072] After the potting filler layer 4 has cured, the sensor is filled with an inert gas, such as argon. Then, in the inert gas environment, the housing 3 and the electrical connector 6 are welded together to form a fully sealed structure. By filling with inert gas and sealing, external corrosive environments such as high temperature, humidity, and salt spray are isolated, and the promoting effect of oxygen conditions inside the sensor on electrochemical corrosion is eliminated, thereby inhibiting electrochemical corrosion. Filling the sensor with inert gas before sealing the overall structure further prevents corrosion of the welded parts in an oxygen-rich environment.

[0073] This embodiment addresses the problem of galvanic corrosion caused by the formation of galvanic cells in high-temperature, humid, and salt spray environments due to corrosion potential differences between silver-plated copper wires and nickel wires, leading to solder joint corrosion, wire breakage, and signal interruption. It constructs a technical design that combines potential difference suppression, multi-layer isolation, and sealing protection.

[0074] In this embodiment, welding wire capable of suppressing galvanic corrosion is selected for welding to reduce the corrosion driving force at the dissimilar metal joint and decrease the tendency for electrochemical corrosion. By coating the welding area and the transition area between the welding wire and the two side conductors with multiple layers of insulating varnish, the galvanic contact between the first and second metal conductors can be isolated, thereby cutting off the conduction path of corrosion ions between dissimilar metals. A heat-shrinkable sleeve 7 is fitted over the insulating varnish and then heat-shrinked to form a protective outer layer, preventing the insulating varnish layer from being scratched or damaged by external forces, enhancing the isolation effect, and applying elastic force to strengthen the bonding ability of the welding area.

[0075] The above design reduces corrosion tendency, cuts off ion pathways, strengthens protection capabilities, and improves the corrosion resistance of dissimilar metal wire connections, thereby ensuring the stability and reliability of speed signal transmission.

[0076] Of course, the above corrosion protection methods can be applied not only to airborne speed sensors, but also to the corrosion protection of internal wires in other sensors with dual temperature ranges.

[0077] This embodiment also provides an airborne speed sensor, such as Figure 2 and Figure 3As shown, the device includes a coil 1, a magnet 2, a housing 3, a signal transmission line 5, and an electrical connector 6. The coil 1 is located in the front sensing area inside the housing 3. The magnet 2 is adapted to cooperate with the coil 1 to generate an induced signal. The electrical connector 6 is installed at the rear end of the housing 3. The signal transmission line 5 includes a silver-plated copper wire and a nickel wire. One end of the silver-plated copper wire is soldered to the coil 1, and one end of the nickel wire is soldered to the other end of the silver-plated copper wire. The other end of the nickel wire extends to the rear end of the housing 3 and is electrically connected to the terminal of the electrical connector 6. The silver-plated copper wire and the nickel wire are connected and protected using the corrosion protection method described above.

[0078] The signal transmission line 5 uses segmented connections of silver-plated copper wire and nickel wire. One end of the silver-plated copper wire is soldered to the coil 1, and the other end is soldered to the nickel wire. The nickel wire extends to the rear end of the outer casing 3 and connects to the electrical connector 6. The connection between the silver-plated copper wire and the nickel wire is protected according to the corrosion protection method described above, which effectively reduces the tendency to corrode, cuts off the ion pathway, strengthens the protection capability, and improves the corrosion resistance of dissimilar metal wire connections, enabling the airborne speed sensor signal transmission to have good stability and reliability.

[0079] In a specific embodiment, the airborne speed sensor is a dual-temperature-range sensor, with the upper limit of the sensing part's operating temperature being 180°C and the upper limit of the signal transmission part's operating temperature being 500°C. The airborne speed sensor can operate reliably for extended periods under dual-temperature conditions of 180°C for the sensing part and 500°C for the signal transmission part, providing stable signal transmission assurance for aero-engine speed measurement.

[0080] In a specific embodiment, the airborne speed sensor is filled with an inert gas to isolate it from the external corrosive environment and eliminate the possibility of electrochemical corrosion caused by internal oxygen conditions. Combined with the above-mentioned filling and sealing welding design, it ensures that the internal environment of the airborne speed sensor remains inert during operation, ensuring the long-term corrosion resistance stability of the dissimilar metal connection structure and the reliability of signal transmission.

[0081] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for protecting the internal wires of an airborne speed sensor from corrosion, characterized in that, The airborne speed sensor has an internal dissimilar metal connection structure formed by welding a first metal wire and a second metal wire, and there is a corrosion potential difference between the first metal wire and the second metal wire. The corrosion protection method includes: selecting a welding wire capable of suppressing the galvanic corrosion effect between the first metal wire and the second metal wire, and welding the dissimilar metal connection structure. The welded parts and the transition area between the welding wire and the two metal wires are coated with multiple layers of insulating varnish to isolate the galvanic contact between the first metal wire and the second metal wire; after the multiple layers of insulating varnish are coated and formed, the heat shrink tubing (7) is fitted onto the welded parts and the coated area and heat shrinked.

2. The corrosion protection method according to claim 1, characterized in that, The multi-layer insulating varnish is applied using a layered coating and curing process. The multi-layer insulating varnish includes a primer layer, a middle varnish layer, and a topcoat layer, and the sum of the thicknesses of each varnish layer is ≤0.2mm.

3. The corrosion protection method according to claim 2, characterized in that, The thickness of the primer layer is 0.03mm-0.05mm, the thickness of the intermediate paint layer is 0.06mm-0.08mm, and the thickness of the topcoat layer is 0.04mm-0.06mm.

4. The method for protecting the internal wires of an airborne speed sensor from corrosion according to claim 2, characterized in that, In the layered coating process, after each layer is coated, a segmented heating and drying process is performed, controlling the heating rate and holding time; the next layer is applied only after the current layer is completely dry and formed; and / or, The insulating varnish is made of high-temperature resistant flexible silicone.

5. The method for protecting the internal wires of an airborne speed sensor from corrosion according to claim 1, characterized in that, The heat shrink tubing (7) is sleeved on the outside of the multilayer insulating varnish; The heat shrink tubing (7) is a highly elastic flame-retardant heat shrink tubing (7), and the material of the heat shrink tubing (7) is one of polyvinylidene fluoride, fluororubber, polytetrafluoroethylene or silicone rubber.

6. The method for protecting the internal wires of an airborne speed sensor from corrosion according to claim 1, characterized in that, The corrosion protection method further includes: potting and filling the outside of the heat shrink tubing (7) to form a filling layer (4).

7. The method for protecting the internal wires of an airborne speed sensor from corrosion according to claim 1, characterized in that, The airborne speed sensor is filled with inert gas, and the sensor housing (3) and electrical connector (6) are welded and sealed in an inert gas environment.

8. The method for protecting the internal wires of an airborne speed sensor from corrosion according to any one of claims 1 to 7, characterized in that, The first metal conductor is a silver-plated copper wire, and the second metal conductor is a nickel wire; the welding is performed using argon arc welding. The welding wire is a nickel-based Monel welding wire with the following composition by mass percentage: Ni 62%-69%, Cu 28%-32%, Ti 1.5%-3%, Mn≤4%, Fe≤2.5%; or the welding wire is a copper-nickel alloy welding wire with the following composition by mass percentage: Ni 29%-32%, Mn≤1.0%, Fe 0.4%-0.7%, Cu balance.

9. An airborne speed sensor, characterized in that, The device includes a coil (1), a magnet (2), a housing (3), a filling layer (4), a signal transmission line (5), and an electrical connector (6). The coil (1) is located in the front sensing area inside the housing (3). The magnet (2) is adapted to cooperate with the coil (1) to generate an induction signal. The electrical connector (6) is installed at the rear end of the housing (3). The signal transmission line (5) includes a silver-plated copper wire and a nickel wire. One end of the silver-plated copper wire is welded to the coil (1), and one end of the nickel wire is welded to the other end of the silver-plated copper wire. The other end of the nickel wire extends to the rear end of the housing (3) and is electrically connected to the terminal of the electrical connector (6). The silver-plated copper wire and the nickel wire are connected and protected using the corrosion protection method as described in any one of claims 1 to 8.

10. The airborne speed sensor according to claim 9, characterized in that, The sensor is a dual-temperature-range sensor, with an upper limit of 180°C for the sensing element and an upper limit of 500°C for the signal transmission section; and / or, The airborne speed sensor is filled with inert gas.

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