Oil nozzle of methanol engine and manufacturing method of protective structure of oil nozzle

Abstract

The invention relates to the technical field of fuel injection nozzle protection of methanol engines, in particular to a fuel injection nozzle of a methanol engine and a manufacturing method of a protection structure of the fuel injection nozzle of the methanol engine. By means of the hollow heat insulation structure of the heat insulation layer, influences of external heat on the interior of the oil nozzle are reduced, and thermal fatigue cracks are restrained; then a conductive heating layer and an anti-corrosion protection layer are sequentially sprayed on the insulating heat-insulating layer, an electrode is led out of the conductive heating layer to be electrified, and the problem that the top of the methanol engine oil nozzle is easy to freeze due to condensation of low-temperature water vapor is effectively solved by utilizing heat generated by the conductive heating layer in an electrified state; in addition, corrosion damage resistance of the top of the methanol engine oil nozzle is effectively improved through the anti-corrosion protection layer.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel injection nozzle protection of an engine, and in particular to a fuel injection nozzle of a methanol engine and a manufacturing method of a protective structure thereof. Background Art

[0002] The gradual increase in engine power and the rapid development of engines powered by alternative fuels such as methanol pose significant challenges to the service life and reliability of engine fuel injection systems. This is particularly true of the injector tip, which is directly exposed to high-temperature, high-pressure combustion gases. Combustion products such as diesel and methanol (formaldehyde, formic acid, acetic acid, hydrogen, and CO2) can easily corrode the injector tip.

[0003] Furthermore, the tops of methanol engine fuel injectors are subject to high temperatures, making them susceptible to deformation and fatigue cracking, which directly impacts their fuel injection performance and service life. Especially in the northwest climate, in addition to being highly corrosive, methanol engine fuel injectors are susceptible to freezing at low temperatures, which weakens the performance of the methanol engine's fuel injection system and affects its overall performance and operational stability.

[0004] Therefore, it is urgent to propose a protective structure that can improve the corrosion damage resistance, fatigue resistance and hydrophobicity and anti-icing performance of the top of the methanol engine fuel injector. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, one of the purposes of the present invention is to provide a methanol engine fuel injector and a method for manufacturing a protective structure thereof, which can effectively improve the corrosion damage resistance and fatigue resistance of the engine fuel injector top, and at the same time solve the problem that the top of the engine fuel injector is easily frozen due to condensation of low-temperature water vapor.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a fuel injector for a methanol engine, wherein a protective area is provided on the top of the fuel injector, and a protective structure is provided on the protective area. The protective structure includes an insulating heat insulation layer, a conductive heating layer and an anti-corrosion protection layer. The insulating heat insulation layer is arranged in the protective area, and a hollow heat insulation structure is provided inside the insulating heat insulation layer; the conductive heating layer is covered on the upper surface of the insulating heat insulation layer, and a positive electrode and a negative electrode are led out on the conductive heating layer; the anti-corrosion protection layer is covered on the upper surface of the conductive heating layer.

[0008] Furthermore, the material of the insulating and heat-insulating layer is hollow glass powder or hollow SiO2 powder.

[0009] Furthermore, the material of the conductive heating layer is a ceramic composite material doped with metal powder, and the ceramic composite material is composed of metal powder, conductive ceramic material and titanium carbide, or the ceramic composite material is composed of metal powder, conductive ceramic material and zirconium carbide, or the ceramic composite material is composed of metal powder, conductive ceramic material and copper iodide; wherein the metal powder accounts for 1% to 3% of the total amount of the ceramic composite material; the conductive ceramic material accounts for 80% to 90% of the total amount of the ceramic composite material; and the titanium carbide or zirconium carbide or copper iodide accounts for 7% to 19% of the total amount of the ceramic composite material.

[0010] Furthermore, the metal powder is lead, thallium, antimony, bismuth or manganese metal powder.

[0011] Furthermore, the conductive ceramic material is titanium oxide or aluminum oxide conductive material.

[0012] Furthermore, the material of the anti-corrosion protective layer is titanium dioxide powder.

[0013] In a second aspect, the present invention provides a method for manufacturing a protective structure for a fuel injector of a methanol engine, wherein the protective structure is manufactured in a protective area at the top of the fuel injector of the engine, comprising the following steps:

[0014] S1. Clean the fuel injector: Use ultrasonic cleaning with detergent for 15 minutes, and then use ultrasonic cleaning with desalted water for 15 minutes;

[0015] S2. Dry the fuel injector: Take out the fuel injector and blow it dry with compressed air;

[0016] S3. Drying the fuel injector: Place the fuel injector in an oven and dry it at a preset temperature of 120°C for 15 minutes.

[0017] S4, spraying an insulating and heat-insulating layer: spraying an insulating and heat-insulating layer on the protective area on the top of the fuel injector nozzle dried in step S3;

[0018] S5. Spraying a conductive heating layer: The process involves spraying a conductive heating layer on the insulating ceramic layer in step S4, spraying a nickel alloy film and an aluminum alloy film on the end surface of the conductive heating layer, and welding the negative electrode and the positive electrode to the nickel alloy film and the aluminum alloy film respectively;

[0019] S6. Spraying an anti-corrosion protective layer: spraying an anti-corrosion protective layer on the conductive heating layer in step S5.

[0020] Furthermore, in step S4, a plasma spraying process is used to spray SiO2 powder with a hollow structure on the top protection area of ​​the fuel injector to form the insulating and heat-insulating layer.

[0021] Furthermore, in step S5, a plasma spraying process is used to spray a mixed powder of bismuth, titanium oxide and titanium carbide onto the upper surface of the insulating and heat-insulating layer to form the conductive heating layer.

[0022] Furthermore, in step S6, titanium dioxide powder is sprayed on the upper surface of the conductive heating layer using a plasma spraying process to form the anti-corrosion protective layer.

[0023] Compared with the prior art, the present invention has the following significant effects:

[0024] The fuel injector protection structure of the methanol engine of the present invention adopts a multi-layer structure design. First, an insulating heat-insulating layer is coated on the protective area of ​​the top of the fuel injector. The hollow heat-insulating structure of the insulating heat-insulating layer is used to reduce the influence of external heat on the inside of the fuel injector and inhibit the occurrence of thermal fatigue cracks. Then, a conductive heating layer and an anti-corrosion protective layer are sprayed in sequence on the insulating heat-insulating layer. Electrodes are drawn out of the conductive heating layer and energized. The conductive heating layer in the energized state generates heat, effectively solving the problem of condensation and easy icing of the top of the fuel injector of the methanol engine due to low-temperature water vapor. In addition, the anti-corrosion protective layer is used to effectively improve the corrosion damage resistance of the top of the fuel injector of the methanol engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic structural diagram of the fuel injection nozzle protection structure of the methanol engine of the present invention;

[0026] Figure 2 This is a schematic diagram of a structure in which a protective structure is provided on a protective area at the top of a fuel injector according to an embodiment of the present invention;

[0027] Figure 3 The present invention is a flowchart of spraying a protective structure on a fuel injection nozzle according to an embodiment of the present invention.

[0028] Numbers in the figure:

[0029] 1. Protective structure; 10. Insulation layer; 11. Conductive heating layer; 12. Anti-corrosion protection layer; 2. Fuel injector; 20. Protective area. DETAILED DESCRIPTION

[0030] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] In the description of the present invention, it should be understood that the terms "width", "up", "down", "front", "back", "top", "bottom", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", and "set" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0032] In the present invention, unless otherwise clearly stipulated and limited, the first feature being "on" or "under" the second feature may include the first and second features being in direct contact, or the first and second features not being in direct contact but being in contact through another feature between them.

[0033] Example 1

[0034] Please refer to Figure 1 - Figure 2 In the first aspect, the present invention provides a fuel injector 2 for a methanol engine, wherein a protective area 20 is provided on the top of the fuel injector 2, and a protective structure 1 is provided on the protective area 20, wherein the protective structure 1 includes an insulating heat-insulating layer 10, a conductive heating layer 11 and an anti-corrosion protective layer 12. The insulating heat-insulating layer 10 is fixed to the protective area at the top of the fuel injector, and a hollow heat-insulating structure is provided inside the insulating heat-insulating layer 10. The conductive heating layer 11 is fixed on the insulating heat-insulating layer 10, and a positive electrode and a negative electrode are led out on the conductive heating layer 11, and the positive electrode and the negative electrode can be copper wires. The conductive heating layer 11 covers the upper surface of the insulating heat-insulating layer 10. The anti-corrosion protective layer 12 is fixed on the conductive heating layer 11, and the anti-corrosion protective layer 12 covers the upper surface of the conductive heating layer 11.

[0035] The fuel injector protection structure 1 of the methanol engine of the present invention is designed with a multi-layer structure. First, an insulating heat-insulating layer 10 is coated on the protective area 20 at the top of the fuel injector. The hollow heat-insulating structure of the insulating heat-insulating layer 10 is used to reduce the influence of external heat on the inside of the fuel injector and inhibit the occurrence of thermal fatigue cracks. Then, a conductive heating layer 11 and an anti-corrosion protection layer 12 are sprayed in sequence on the insulating heat-insulating layer 10. The electrodes of the conductive heating layer 11 are energized, and the conductive heating layer 11 in the energized state is used to generate heat, effectively solving the problem of condensation and easy freezing of low-temperature water vapor at the top of the fuel injector of the methanol engine. In addition, the anti-corrosion protection layer 12 is used to effectively improve the corrosion damage resistance of the top of the fuel injector of the methanol engine.

[0036] In one embodiment, the thickness of the insulating layer 10 is 5 to 20 μm. For example, the thickness of the insulating layer 10 is 5 μm, 6 μm, 20 μm, or 10 μm. Of course, the insulating layer 10 is made of a material with a low thermal conductivity, a high resistance, and an insulator-like conductivity, and has an air insulation structure. Specifically, the insulating layer 10 is made of SiO2 powder with a hollow structure. The hollow SiO2 powder contains a large number of closed micropores, which can effectively hinder the transfer of heat. The hollow SiO2 powder greatly increases the path and difficulty of heat transfer, thereby significantly reducing the thermal conductivity of the material. In addition, SiO2 itself has a certain reflective ability for thermal radiation, and the hollow structure further enhances this reflective effect. When thermal radiation hits the surface of the hollow SiO2, part of the radiation will be reflected back, reducing the material's absorption of thermal radiation, thereby reducing the temperature rise inside the material and improving the thermal insulation performance.

[0037] In other embodiments, the material of the insulating layer 10 can also be hollow glass powder. The interior of the hollow glass microbeads (a form of hollow glass powder) is close to a vacuum and has an extremely low thermal conductivity, which can significantly reduce the thermal conductivity of the coating or material and improve the thermal insulation effect. Its high closed porosity, small particle size, and low moisture absorption rate can effectively reduce heat transfer. In addition, glass powder exhibits good corrosion resistance to chemicals such as acids and alkalis at high temperatures and does not easily react with other substances. Hollow glass powder inherits this characteristic and can maintain stable performance in harsh chemical environments.

[0038] In one embodiment, the thickness of the conductive heating protection layer is 10 to 50 μm. For example, the thickness of the insulating heat-insulating layer 10 is 10 μm, 20 μm, or 50 μm. The conductive heating layer 11 is made of a ceramic composite material doped with metal powder. The ceramic composite material is composed of metal powder, conductive ceramic material, and titanium carbide. The metal powder accounts for 1 to 3% of the total ceramic composite material; the conductive ceramic material accounts for 80 to 90% of the total ceramic composite material; and the titanium carbide accounts for 7 to 19% of the total ceramic composite material. Exemplarily, the metal powder accounts for 1% of the total amount of the ceramic composite material, the conductive ceramic material accounts for 80% of the total amount of the ceramic composite material, and titanium carbide accounts for 19% of the total amount of the ceramic composite material; in another exemplary embodiment, the metal powder accounts for 3% of the total amount of the ceramic composite material, the conductive ceramic material accounts for 90% of the total amount of the ceramic composite material, and titanium carbide accounts for 7% of the total amount of the ceramic composite material; in another exemplary embodiment, the metal powder accounts for 3% of the total amount of the ceramic composite material, the conductive ceramic material accounts for 90% of the total amount of the ceramic composite material, and titanium carbide accounts for 7% of the total amount of the ceramic composite material; in another exemplary embodiment, the metal powder accounts for 1% of the total amount of the ceramic composite material, the conductive ceramic material accounts for 89% of the total amount of the ceramic composite material, and titanium carbide accounts for 10% of the total amount of the ceramic composite material.

[0039] It is understandable that the metal powder (accounting for 1-3%) forms a conductive network in the composite material, which can effectively connect the conductive ceramic particles, optimize the electron transmission path, significantly reduce the resistivity of the material, and improve the conductive performance. Conductive ceramic materials (accounting for 80% to 90%) provide basic conductivity, and their high conductivity properties work synergistically with the metal powder to ensure that the material can achieve efficient heat generation at low voltage. Titanium carbide (accounting for 7% to 19%), as a high melting point and high hardness component, not only improves the wear resistance of the material, but also optimizes the heating efficiency through its semiconductor properties. Its interface bonding with the conductive ceramic promotes uniform distribution of heat energy and avoids local overheating. In short, the composite structure of metal powder, conductive ceramic and titanium carbide forms an integrated "conductivity-heating-thermal conductivity" system, which quickly converts electrical energy into thermal energy through conductive ceramics, evenly disperses heat through titanium carbide, and ensures stable current transmission through metal powder. The three work together to improve heating efficiency and stability.

[0040] In one embodiment, the metal powder is bismuth metal powder. Bismuth metal powder has a certain electrical conductivity. When doped into a ceramic composite material as a metal powder, it can form a conductive network, improve the conductivity of the ceramic composite material, and thus enhance the heating efficiency of the conductive heating layer 11. At the same time, the addition of bismuth may help improve the thermal stability of the material, allowing it to maintain stable performance in high-temperature environments. In addition, bismuth powder reacts with oxygen and water vapor in the air to form compounds such as bismuth oxide. These compounds may have certain anti-corrosion properties and can enhance the protective effect of the anti-corrosion protective layer.

[0041] In other embodiments, the metal powder may also be lead metal powder, thallium metal powder, antimony metal powder, or manganese metal powder, which is not limited here.

[0042] In one embodiment, the conductive ceramic material is titanium oxide. Titanium oxide ceramics have high electrical conductivity and stability. Their conductivity stems from defects in the lattice structure (such as oxygen vacancies and titanium ion vacancies) and doping with other ions (such as niobium ions and manganese ions). These defects and doping ions increase the number of conductive carriers in the conductive ceramic, improving its conductivity. Furthermore, titanium oxide ceramics have excellent thermal stability, maintaining their structural and performance stability at high temperatures, even extreme temperatures, making them suitable for high-temperature operating environments. Furthermore, titanium oxide conductive ceramics have good sensitivity and stability.

[0043] In other embodiments, the conductive ceramic material may also be an alumina conductive material. Alumina itself is an insulating material, but by adding a conductive or semiconductive material to the alumina matrix and co-firing it, a conductive network can be formed. Alumina ceramics have good thermal conductivity and can effectively dissipate heat, making them suitable for high-power components. They are also heat-resistant and can maintain stable performance in high-temperature environments, with a temperature resistance of over 1600°C. Furthermore, alumina ceramics have high hardness and mechanical strength, and are corrosion-resistant to most chemicals, allowing them to maintain stable performance in harsh environments.

[0044] In one embodiment, the anti-corrosion protective layer is made of titanium dioxide powder. Because titanium dioxide powder has extremely high chemical stability and can resist corrosion from a variety of chemicals such as acids, alkalis, and salts, the anti-corrosion protective layer formed by the titanium dioxide powder can effectively isolate the conductive heating layer 11 from contact with the corrosive medium, thereby preventing or slowing down the occurrence of corrosion.

[0045] In addition, when forming an anti-corrosion protective layer, titanium dioxide powder can form a dense structure, effectively preventing the penetration of corrosive media. This dense structure can significantly improve the protective effect. Moreover, the titanium dioxide powder has good adhesion to the base material (ceramic composite material), which can ensure that the anti-corrosion protective layer is tightly bonded to the base material and is not easy to fall off or crack.

[0046] Secondly, refer to Figure 3 The present invention provides a method for manufacturing a protective structure for a fuel injector of a methanol engine, which is used to manufacture the protective structure 1 in the protective area at the top of the fuel injector of the engine, comprising the following steps:

[0047] S1. Clean the fuel injector: Use ultrasonic cleaning with detergent for 15 minutes, and then use desalted water for another 15 minutes;

[0048] S2. Dry the fuel injector: Take out the fuel injector 2 and dry it with compressed air;

[0049] S3, drying the fuel injector: placing the fuel injector 2 in an oven and drying it at a preset temperature of 120°C for 15 minutes;

[0050] S4, spraying an insulating and heat-insulating layer 10: spraying an insulating and heat-insulating layer 10 on the nozzle top protection area 20 dried in step S3;

[0051] S5. Spraying a conductive heating layer 11: The conductive heating layer 11 is sprayed on the insulating ceramic layer in step S4, and a nickel alloy film and an aluminum alloy film are sprayed on the end surface of the conductive heating layer 11. The negative electrode and the positive electrode are welded to the nickel alloy film and the aluminum alloy film respectively;

[0052] S6. Spraying an anti-corrosion protective layer 12: spraying an anti-corrosion protective layer 12 on the conductive heating layer 11 in step S5.

[0053] In step S4, a plasma spraying process is used to spray a hollow SiO2 powder (in powder form) onto the top protective area of ​​the fuel injector to form the above-mentioned insulating and heat-insulating layer 10. It can be understood that the use of a plasma spraying process can enable the powder to obtain greater kinetic energy and a higher temperature, and the density of the resulting coating is generally between 88% and 99%. The high-density coating can effectively isolate heat transfer, reduce the performance degradation or damage of the fuel injector caused by high temperature, and improve its working stability and life. In addition, the bonding strength between the coating formed by plasma spraying and the fuel injector can reach 30 to 80 MPa, ensuring that the insulating and heat-insulating layer 10 is firmly bonded to the top surface of the fuel injector and is not easy to fall off or crack.

[0054] In step S5, a plasma spraying process is used to spray a powder mixed with bismuth, titanium oxide and titanium carbide on the upper surface of the insulating heat-insulating layer 10 to form the above-mentioned conductive heating layer 11. Since the plasma spraying process can form a coating with high bonding strength and low porosity, after the powder mixed with bismuth, titanium oxide and titanium carbide is sprayed on the upper surface of the insulating heat-insulating layer 10, the conductive heating layer 11 formed has good bonding strength with the substrate (insulating heat-insulating layer 10) and is not easy to fall off or crack. At the same time, the density of the coating also helps to prevent the penetration of corrosive media and improve the protective effect of the conductive heating layer 11.

[0055] In step S6, a plasma spraying process is used to spray titanium dioxide powder onto the upper surface of the conductive heating layer 11 to form the above-mentioned anti-corrosion protective layer 12. The particle size of the titanium dioxide powder is less than 50 nm. During the plasma spraying process, titanium dioxide powder with a particle size less than 50 nm can easily form a more uniform and dense coating structure due to its small particle size and large specific surface area. This structure helps to improve the bonding strength and hardness of the coating, and may also reduce the porosity of the coating, thereby improving the corrosion resistance and wear resistance of the coating.

[0056] In addition, after the anti-corrosion protective layer 12 is sprayed, the surface of the anti-corrosion protective layer 12 is ground flat with a grinding wheel and then ground to a surface finish of 1 to 2 μm. The surface finish of the anti-corrosion protective layer 12 is preferably 1.6 μm.

[0057] In summary, when the injector protection structure 1 is sprayed on the injector, the plasma spraying process is first used to spray the hollow structure SiO2 powder on the top protection area 20 of the injector to form an insulating and thermal insulation layer 10; then the plasma spraying process is used to spray the mixed powder of bismuth, titanium oxide and titanium carbide on the upper surface of the insulating and thermal insulation layer 10 to form a conductive heating layer 11, and at the same time, the positive electrode and the negative motor are led out at both ends of the conductive heating layer 11; finally, the plasma spraying process is used to spray titanium dioxide powder on the upper surface of the conductive heating layer 11 to form an anti-corrosion protection layer 12.

[0058] Example 2

[0059] The difference between this embodiment and the first embodiment lies in the difference in the ceramic composite material.

[0060] The ceramic composite material is composed of metal powder, conductive ceramic material and zirconium carbide, wherein the metal powder accounts for 1-3% of the total amount of the ceramic composite material; the conductive ceramic material accounts for 80%-90% of the total amount of the ceramic composite material; and the zirconium carbide accounts for 7%-19% of the total amount of the ceramic composite material. Exemplarily, the metal powder accounts for 1% of the total amount of the ceramic composite material, the conductive ceramic material accounts for 80% of the total amount of the ceramic composite material, and the zirconium carbide accounts for 19% of the total amount of the ceramic composite material; in another exemplary embodiment, the metal powder accounts for 3% of the total amount of the ceramic composite material, the conductive ceramic material accounts for 90% of the total amount of the ceramic composite material, and the zirconium carbide accounts for 7% of the total amount of the ceramic composite material; in another exemplary embodiment, the metal powder accounts for 3% of the total amount of the ceramic composite material, the conductive ceramic material accounts for 90% of the total amount of the ceramic composite material, and the zirconium carbide accounts for 7% of the total amount of the ceramic composite material; in another exemplary embodiment, the metal powder accounts for 1% of the total amount of the ceramic composite material, the conductive ceramic material accounts for 89% of the total amount of the ceramic composite material, and the zirconium carbide accounts for 10% of the total amount of the ceramic composite material.

[0061] Because metal powders are highly conductive, they form a conductive network within ceramic composites, where the metal powder particles contact each other or are connected through other conductive media (such as conductive ceramic materials). For example, when the metal powder content is between 1% and 3%, these dispersed metal powders can create conductive pathways within the ceramic matrix, allowing current to flow smoothly and significantly improving the composite's conductivity.

[0062] In addition, the conductive ceramic material itself also has a certain degree of conductivity, which, in combination with the metal powder, further enhances the conductive properties of the composite material. This synergistic effect enables the conductive heating layer 11 to achieve high current conduction at a low voltage, providing sufficient electrical energy for the heating process.

[0063] In addition, the high thermal conductivity of the conductive ceramic material and zirconium carbide helps to conduct the generated heat quickly and evenly, avoid local overheating, and improve the heating efficiency. The synergistic effect of the metal powder, conductive ceramic material and zirconium carbide makes the distribution of current in the ceramic composite material more uniform, thereby ensuring the uniformity of heating. Since ceramic materials usually have the disadvantage of being brittle, the addition of metal powder can improve the toughness of the ceramic composite material to a certain extent. The metal powder plays a role similar to "pinning" in the ceramic matrix, which can prevent the expansion of cracks and enhance the material's resistance to fracture. For example, when subjected to external force impact, the metal powder can absorb part of the energy, reduce the generation and expansion of cracks, thereby improving the reliability and service life of the conductive heating layer 11.

[0064] Since both the conductive ceramic material and zirconium carbide have high hardness and good wear resistance, their presence significantly improves the overall hardness and wear resistance of the composite material. This plays an important role in the conductive heating layer 11 resisting damage such as wear and scratches during long-term use, ensuring the stable performance of the conductive heating layer 11. In addition, both the conductive ceramic material and zirconium carbide have high melting points and can maintain stable performance in high temperature environments, which allows the conductive heating layer 11 to operate normally under high temperature conditions without softening, deformation or performance degradation. In addition, the conductive ceramic material itself has good chemical stability and can resist the erosion of a variety of chemical substances. Therefore, the combination of metal powder, conductive ceramic material and zirconium carbide further enhances the corrosion resistance of the ceramic composite material, so that it can maintain stable performance even in harsh chemical environments, so that the conductive heating layer 11 of the present invention will not react with chemical substances, thereby ensuring the normal operation and service life of the methanol engine injector.

[0065] In a high-temperature, oxygen-rich environment, the metal powder in the ceramic composite material may undergo oxidation. However, the presence of the conductive ceramic material and zirconium carbide can protect the metal powder to a certain extent, slowing the oxidation rate. Furthermore, the ceramic matrix itself has certain antioxidant properties, which can prevent oxygen from corroding the material and ensure the long-term stability of the conductive heating layer 11 in a high-temperature, oxidizing environment.

[0066] Example 3

[0067] The difference between this embodiment and the above embodiments lies in the difference in the ceramic composite material.

[0068] The ceramic composite material is composed of metal powder, conductive ceramic material and copper iodide; the metal powder accounts for 1-3% of the total amount of the ceramic composite material; the conductive ceramic material accounts for 80%-90% of the total amount of the ceramic composite material; and the copper iodide accounts for 7%-19% of the total amount of the ceramic composite material. Exemplarily, the metal powder accounts for 1% of the total amount of the ceramic composite material, the conductive ceramic material accounts for 80% of the total amount of the ceramic composite material, and the copper iodide accounts for 19% of the total amount of the ceramic composite material; in another exemplary embodiment, the metal powder accounts for 3% of the total amount of the ceramic composite material, the conductive ceramic material accounts for 90% of the total amount of the ceramic composite material, and the copper iodide accounts for 7% of the total amount of the ceramic composite material; in another exemplary embodiment, the metal powder accounts for 3% of the total amount of the ceramic composite material, the conductive ceramic material accounts for 90% of the total amount of the ceramic composite material, and the copper iodide accounts for 7% of the total amount of the ceramic composite material; in another exemplary embodiment, the metal powder accounts for 1% of the total amount of the ceramic composite material, the conductive ceramic material accounts for 89% of the total amount of the ceramic composite material, and the copper iodide accounts for 10% of the total amount of the ceramic composite material.

[0069] Metal powder has excellent electrical conductivity. In ceramic composite materials, the metal powder particles contact each other or form a conductive network through the conductive ceramic material, allowing current to flow smoothly, significantly improving the conductivity of the composite material. Copper iodide also has a certain degree of conductivity. The synergistic effect of the metal powder, conductive ceramic material, and copper iodide enables the conductive heating layer 11 to achieve high current conduction at a low voltage, providing sufficient electrical energy for the heating process.

[0070] Because ceramic composites have excellent electrical conductivity, when current passes through them, according to Joule's law, they rapidly generate heat. The presence of the conductive ceramic material and copper iodide helps to quickly and evenly conduct the generated heat, preventing localized overheating and improving heating efficiency. Furthermore, the uniform distribution of metal powder within the ceramic matrix and the synergistic effect of the conductive ceramic material and copper iodide ensure even distribution of current within the composite, thus ensuring uniform heating.

[0071] In addition, ceramic materials themselves have good chemical stability and can resist corrosion from a variety of chemicals. The combination of metal powder, conductive ceramic material and copper iodide further enhances the corrosion resistance of the composite material, allowing it to maintain stable performance even in harsh chemical environments.

[0072] Furthermore, the conductive ceramic material has a high melting point and can maintain stable performance in high-temperature environments. Copper iodide also has a certain degree of stability at high temperatures, which allows the conductive heating layer 11 to operate normally under high-temperature conditions without softening, deformation, or performance degradation.

[0073] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A fuel injector for a methanol engine, wherein a protective area is provided on the top of the fuel injector, characterized in that: A protective structure is arranged on the protective area, and the protective structure includes an insulating heat-insulating layer, a conductive heating layer and an anti-corrosion protective layer. The insulating heat-insulating layer is arranged in the protective area, and a hollow heat-insulating structure is provided inside the insulating heat-insulating layer; the conductive heating layer is covered on the upper surface of the insulating heat-insulating layer, and a positive electrode and a negative electrode are led out on the conductive heating layer; the anti-corrosion protective layer is covered on the upper surface of the conductive heating layer.

2. The fuel injector for a methanol engine according to claim 1, characterized in that: The material of the insulating and heat-insulating layer is hollow glass powder or hollow SiO2 powder.

3. The fuel injection nozzle of a methanol engine according to claim 1, characterized in that: The material of the conductive heating layer is a ceramic composite material doped with metal powder, and the ceramic composite material is composed of metal powder, conductive ceramic material and titanium carbide, or the ceramic composite material is composed of metal powder, conductive ceramic material and zirconium carbide, or the ceramic composite material is composed of metal powder, conductive ceramic material and copper iodide; wherein the metal powder accounts for 1% to 3% of the total amount of the ceramic composite material; the conductive ceramic material accounts for 80% to 90% of the total amount of the ceramic composite material; and the titanium carbide or zirconium carbide or copper iodide accounts for 7% to 19% of the total amount of the ceramic composite material.

4. The fuel injection nozzle of a methanol engine according to claim 3, characterized in that: The metal powder is lead, thallium, antimony, bismuth or manganese metal powder.

5. The fuel injector for a methanol engine according to claim 3, characterized in that: The conductive ceramic material is titanium oxide or aluminum oxide conductive material.

6. The fuel injection nozzle of a methanol engine according to claim 1, characterized in that: The material of the anti-corrosion protection layer is titanium dioxide powder.

7. A method for manufacturing a protective structure for a fuel injector of a methanol engine, for manufacturing the protective structure according to any one of claims 1 to 6 in the protective area at the top of the fuel injector of the engine, characterized in that: The steps include: S1. Clean the fuel injector: Use ultrasonic cleaning with detergent for 15 minutes, and then use ultrasonic cleaning with desalted water for 15 minutes; S2. Dry the fuel injector: Take out the fuel injector and blow it dry with compressed air; S3. Drying the fuel injector: Place the fuel injector in an oven and dry it at a preset temperature of 120°C for 15 minutes. S4, spraying an insulating and heat-insulating layer: spraying an insulating and heat-insulating layer on the protective area on the top of the fuel injector nozzle dried in step S3; S5. Spraying a conductive heating layer: The process involves spraying a conductive heating layer on the insulating ceramic layer in step S4, spraying a nickel alloy film and an aluminum alloy film on the end surface of the conductive heating layer, and welding the negative electrode and the positive electrode to the nickel alloy film and the aluminum alloy film respectively; S6. Spraying an anti-corrosion protective layer: spraying an anti-corrosion protective layer on the conductive heating layer in step S5.

8. The method for manufacturing a protective structure of a fuel injector of a methanol engine according to claim 7, characterized in that: In step S4, a plasma spraying process is used to spray SiO2 powder with a hollow structure onto the top protection area of ​​the fuel injection nozzle to form the insulating and heat-insulating layer.

9. The method for manufacturing a protective structure of a fuel injector of a methanol engine according to claim 7, characterized in that: In step S5, a plasma spraying process is used to spray a mixed powder of bismuth, titanium oxide and titanium carbide onto the upper surface of the insulating and heat-insulating layer to form the conductive heating layer.

10. The method for manufacturing a protective structure of a fuel injector of a methanol engine according to claim 7, characterized in that: In step S6, titanium dioxide powder is sprayed on the upper surface of the conductive heating layer using a plasma spraying process to form the anti-corrosion protective layer.

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