An electric heating device for de-icing rectifier caps and its application.

Abstract

This invention relates to the field of electrothermal technology and discloses an electrothermal device for electric heating and de-icing of a rectifier cap and its application. The electrothermal device includes a first heating component and a second heating component. The first heating component is arranged near the tip of the rectifier cap and is connected to several first conductive fabric substrates through first and second electrodes arranged side by side to form multiple first temperature zones. The second heating component is arranged adjacent to or spaced apart along the periphery of the rectifier cap through several heating elements. Each heating element consists of a third electrode and a fourth electrode arranged on the second conductive fabric substrate to form multiple second temperature zones in the periphery of the rectifier cap. The temperature distribution coefficient between the first and second temperature zones is within 10%, which ensures a relatively balanced heating intensity in each part while effectively preventing ice residue or local thermal damage caused by temperature difference, and significantly improving the overall de-icing effect and structural stability of the rectifier cap.

Description

Technical Field

[0001] This invention relates to the field of electrothermal technology, specifically to an electrothermal device for electric heating and de-icing of rectifier caps and its application. Background Technology

[0002] As a crucial component of an aircraft engine's intake system, the fairing typically features a streamlined design to guide airflow into the compressor in a low-drag, stable manner, thereby improving engine intake efficiency and overall aircraft flight stability. Under complex weather conditions, especially in low-temperature, high-humidity icing environments, supercooled water droplets easily accumulate on the fairing surface and rapidly freeze, altering the original aerodynamic shape and increasing the distortion of the engine inlet flow field. This negatively impacts engine performance and operability, and in severe cases, can even jeopardize flight safety.

[0003] Therefore, existing technologies often employ hot gas de-icing or electric heating de-icing methods. Hot gas de-icing mainly relies on engine bleed air passing through the internal channels of the hood to achieve convective heat transfer, thereby melting the surface ice. However, this method suffers from problems such as low precision in hot gas temperature and flow control, limited heat transfer paths, and uneven heat distribution, making it difficult to achieve uniform heating of the entire hood, resulting in poor local de-icing effects and affecting overall de-icing efficiency.

[0004] Electric heating de-icing typically achieves Joule heating by using heating elements such as resistance wires or heating films, offering good controllability and allowing precise temperature control through voltage adjustment. However, due to the complex curved structure of the rectifier cap and the high material performance requirements, traditional heating elements struggle to achieve a tight fit with the cap surface. Furthermore, the composite material molding process presents challenges such as poor thermal expansion matching and difficulties in structural integration, which in turn affect the uniformity and stability of the heating element distribution. Consequently, it remains difficult to meet the technical requirements of overall, continuous, and uniform heating of the rectifier cap. Summary of the Invention

[0005] In view of this, the present invention provides an electric heating device for electric heating and de-icing of rectifier caps and its application, so as to solve the problem that electric heating de-icing in the prior art is difficult to achieve uniform heating of the entire rectifier cap.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides an electric heating device for de-icing a rectifier cap, the electric heating device being conformally fitted to the rectifier cap, the electric heating device comprising: a first heating assembly and a second heating assembly; the first heating assembly comprising a first electrode and a second electrode extending from the near tip of the rectifier cap towards the peripheral wall, and a plurality of first conductive fabric substrates, the first electrode and the second electrode being arranged side by side and simultaneously connected to the plurality of first conductive fabric substrates, a first gap being present between the first electrode and the second electrode, and the plurality of first conductive fabric substrates being spaced apart along the direction from the near tip of the rectifier cap towards the peripheral wall, the first electrode and the second electrode being connected to the first conductive fabric substrates. When the electrodes are energized, the first heating component has several first temperature zones; the second heating component includes several heating elements disposed on the peripheral wall of the rectifier cap, with adjacent heating elements arranged adjacently or spaced apart, each heating element including a second conductive fabric substrate, and a third electrode and a fourth electrode disposed on the second conductive fabric substrate, the third electrode and the fourth electrode forming a ring structure and coaxially spaced on both sides of the second conductive fabric substrate, and when the third electrode and the fourth electrode are energized, the second heating component has several second temperature zones; the temperature distribution coefficient within the first temperature zone and the second temperature zone is within 10%.

[0008] It has the following advantages:

[0009] This invention provides an electric heating device for de-icing a rectifier cap. A first heating component is positioned near the tip of the rectifier cap. A plurality of first conductive fabric substrates are connected by parallel first and second electrodes to form multiple first temperature zones. A second heating component is arranged at intervals along the periphery of the rectifier cap using several heating elements. Each heating element consists of an annular third and fourth electrode disposed on a second conductive fabric substrate, forming multiple second temperature zones in the periphery of the rectifier cap. By rationally designing the heating structure and power supply method for the first and second temperature zones, the temperature distribution coefficient between the two zones is kept within 10%. This ensures a relatively balanced heating intensity across all parts while effectively preventing icing residue or localized thermal damage caused by temperature differences, significantly improving the overall de-icing effect and structural stability of the rectifier cap.

[0010] According to some embodiments of the present invention, the first heating component unfolds into a fan-shaped structure, the first conductive fabric substrate is provided with multiple components, all of which are in the form of annular structures, the length direction of the first electrode and the second electrode are arranged radially along the fan-shaped structure, and are respectively disposed at both ends of the first conductive fabric substrate to be suitable for simultaneously connecting multiple first conductive fabric substrates, and a second gap is provided between two adjacent first conductive fabric substrates.

[0011] According to some embodiments of the present invention, the heating element is provided in a plurality of ring structures, and the fourth electrode of any heating element and the third electrode of another adjacent heating element are arranged adjacently and have the same polarity.

[0012] According to some embodiments of the present invention, the heating element is provided in a plurality of ring structures, wherein the fourth electrode of any heating element and the third electrode of an adjacent heating element are spaced apart and have a third gap, and have opposite polarities.

[0013] According to some embodiments of the present invention, the values ​​of the first gap and the third gap are both in the range of 1-3 mm, and the value of the second gap is in the range of 0.3-0.7 mm.

[0014] According to some embodiments of the present invention, both the first conductive fabric substrate and the second conductive fabric substrate include an inorganic fiber fabric and a graphene layer deposited on the surface of the inorganic fiber fabric. The inorganic fiber fabric includes quartz fiber fabric, glass fiber fabric, ceramic fiber fabric, alumina fiber fabric or boron fiber fabric.

[0015] According to some embodiments of the present invention, the first electrode and the second electrode are both formed on the first conductive fabric substrate by plasma spraying or electroplating; the third electrode and the fourth electrode are formed on the second conductive fabric substrate by plasma spraying or electroplating.

[0016] According to some embodiments of the present invention, the first electrode, the second electrode, the third electrode, and the fourth electrode are arranged in a strip-like structure, and the first electrode, the second electrode, the third electrode, and the fourth electrode are made of silver or copper.

[0017] Secondly, the present invention provides a rectifier cap, including the application of the electric heating device on the rectifier cap.

[0018] Thirdly, the present invention also provides a method for preparing a rectifier cap, comprising the following steps:

[0019] A mold is prepared according to the size of the rectifier cap, and the mold is preheated.

[0020] The heating element is set according to the size of the rectifier cap, and the heating element is impregnated. The heating element and several reinforcing materials are laid in the mold in sequence according to the designed layup order to form a preform.

[0021] A molding auxiliary layer is applied to the surface of the ply, and the mold is then vacuum-sealed.

[0022] The preform is then cured and molded. Attached Figure Description

[0023] 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.

[0024] Figure 1 This is a schematic diagram of the structure of the electrothermal device provided in some embodiments of the present invention;

[0025] Figure 2 This is a plan view of the first heating component provided in some embodiments of the present invention;

[0026] Figure 3 This is a plan view of the second heating component provided in some embodiments of the present invention;

[0027] Figure 4 The image shows an infrared image of the rectifier cap sample prepared in the third aspect embodiment of the present invention after stabilization at 90V. In the image, sp1, sp2, sp3...sp16 represent temperature measurement points.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. First heating component; 11. First electrode; 12. Second electrode; 13. First conductive fabric substrate; 2. Second heating component; 21. Heating element; 211. Third electrode; 212. Fourth electrode; 213. Second conductive fabric substrate. 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] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] 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. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] Reference Figure 1 , Figure 2 and Figure 3 As shown, in a first aspect of the present invention, an electric heating device for de-icing a rectifier cap is provided. The electric heating device is conformal to the rectifier cap and includes: a first heating assembly 1 and a second heating assembly 2; the first heating assembly 1 includes a first electrode 11 and a second electrode 12 extending from the near tip of the rectifier cap towards the peripheral wall, and a plurality of first conductive fabric substrates 13. The first electrode 11 and the second electrode 12 are arranged side by side and simultaneously connected to the plurality of first conductive fabric substrates 13. A first gap exists between the first electrode 11 and the second electrode 12. The plurality of first conductive fabric substrates 13 are spaced apart along the direction from the near tip of the rectifier cap towards the peripheral wall. 2. When energized, the first heating component 1 has several first temperature zones; the second heating component 2 includes several heating elements 21 disposed on the peripheral wall of the rectifier cap, with adjacent heating elements 21 arranged adjacently or spaced apart. Each heating element 21 includes a second conductive fabric substrate 213, and a third electrode 211 and a fourth electrode 212 disposed on the second conductive fabric substrate 213. The third electrode 211 and the fourth electrode 212 have a ring structure and are coaxially spaced on both sides of the second conductive fabric substrate 213. When the third electrode 211 and the fourth electrode 212 are energized, the second heating component 2 has several second temperature zones; the temperature distribution coefficient in the first temperature zone and the second temperature zone is within 10%.

[0035] Specifically, the first heating component 1 is positioned near the tip of the rectifier cap. It is connected to several first conductive fabric substrates 13 through a first electrode 11 and a second electrode 12 arranged side by side, forming multiple first temperature zones with reasonable distribution and uniform temperature. The second heating component 2 is arranged adjacent to or at intervals along the periphery of the rectifier cap through several heating elements 21. Each heating element 21 consists of an annular third electrode 211 and a fourth electrode 212 disposed on a second conductive fabric substrate 213, forming multiple second temperature zones in the periphery of the rectifier cap. By rationally designing the heating structure and power supply method of the first and second temperature zones, the temperature distribution coefficient of the two zones is kept within 10%. This ensures a relatively balanced heating intensity in each part while effectively preventing icing residue or localized thermal damage caused by temperature differences, significantly improving the overall de-icing effect and structural stability of the rectifier cap.

[0036] It is understood that a first gap exists between the first electrode 11 and the second electrode 12, and both extend from the near tip of the rectifier cap towards the peripheral wall, jointly connecting to several first conductive fabric substrates 13. This avoids current accumulation leading to a significant increase in current density, resulting in a uniform temperature distribution near the tip. Several first conductive fabric substrates 13 are provided, spaced apart, with the first electrode 11 and the second electrode 12 located at opposite ends of each first conductive fabric substrate 13. The more segments of the first conductive fabric substrate 13, the more uniform the temperature.

[0037] In the second heating assembly 2, since both the third electrode 211 and the fourth electrode 212 are arranged in a ring shape, the current flows along the direction of the fastest potential drop between the two ring electrodes, causing the current to concentrate on the shorter ring electrode, resulting in a higher current density and thus forming a hot end. To ensure the uniformity of heating of the rectifier cap's peripheral wall, multiple heating elements 21 are provided, thereby reducing the circumference difference between the third electrode 211 and the fourth electrode 212 and improving heating uniformity. The multiple heating elements 21 are arranged adjacently or spaced apart and in parallel, which helps to achieve independent zone control and coordinated heat distribution, resulting in a stable and uniform heating effect on the peripheral wall. The parallel circuit connection method ensures that even if one heating element 21 fails, the remaining heating elements 21 can still work normally without affecting the overall system operation, thus improving the fault tolerance and operational reliability of the second heating assembly 2. In practical applications, the number of heating elements 21 in the second heating component 2 is related to the size of the rectifier cap. While ensuring the mechanical strength of the second heating component 2, the temperature of the heating area should be made as uniform as possible. This number includes, but is not limited to, 2, 3, 4, 5, 6, etc.

[0038] In some embodiments of the present invention, the first heating component 1 is unfolded into a fan-shaped structure, and multiple first conductive fabric substrates 13 are provided, all of which are in the form of annular structures. The length direction of the first electrode 11 and the second electrode 12 are arranged radially along the fan-shaped structure and are respectively disposed at both ends of the first conductive fabric substrate 13 to be suitable for simultaneously connecting multiple first conductive fabric substrates 13. A second gap is provided between two adjacent first conductive fabric substrates 13.

[0039] Specifically, the first heating component 1, divided between the first electrode 11 and the second electrode 12, has a fan-shaped unfolded structure. The first conductive fabric substrate 13 has a ring-shaped structure, which better fits the curved surface of the rectifier cap, which gradually expands from the tip to the periphery. The first electrode 11 and the second electrode 12 are radially arranged at both ends of the first conductive fabric substrate 13, ensuring that the current distribution direction in the multiple first conductive fabric substrates 13 is consistent with the heat conduction direction. A second gap is provided between two adjacent first conductive fabric substrates 13. This gap can prevent adjacent first conductive fabric substrates 13 from accidentally contacting each other, which helps to maintain the multiple heating elements composed of multiple first conductive fabric substrates 13 in a parallel circuit state, so as to achieve a more uniform temperature rise effect and thus improve the temperature field uniformity of de-icing. In practical applications, the number of multiple first conductive fabric substrates 13 is related to the size of the rectifier cap. It should ensure the mechanical strength of the first heating component 1 while making the temperature of the heating area as uniform as possible. This number includes, but is not limited to, 2, 3, 4, 5, 6, etc.

[0040] In some embodiments of the present invention, multiple heating elements 21 are provided and arranged in a ring structure. The fourth electrode 212 of any heating element 21 and the third electrode 211 of another adjacent heating element 21 are arranged adjacent to each other and have the same polarity.

[0041] In some embodiments of the present invention, multiple heating elements 21 are provided and arranged in a ring structure. The fourth electrode 212 of any heating element 21 and the third electrode 211 of another adjacent heating element 21 are spaced apart and have a third gap, and their polarities are opposite.

[0042] Specifically, when the fourth electrode 212 of any heating element 21 and the third electrode 211 of an adjacent heating element 21 have the same polarity, the fourth electrode 212 and the third electrode 211 of the two adjacent heating elements 21 are arranged adjacent to each other; when the fourth electrode 212 of any heating element 21 and the third electrode 211 of an adjacent heating element 21 have opposite polarities, in order to avoid short circuit between the electrodes, there is a third gap between the fourth electrode 212 and the third electrode 211 of the two adjacent heating elements 21 respectively.

[0043] In some embodiments of the present invention, the values ​​of the first gap and the third gap are both in the range of 1-3 mm, and the value of the second gap is in the range of 0.3-0.7 mm.

[0044] Specifically, by precisely controlling the gap size between adjacent heating elements, on the one hand, the gap can prevent adjacent heating elements from short-circuiting and causing them to fail; on the other hand, the gap area itself cannot generate heat, but is heated through heat diffusion from adjacent heating elements. A reasonable gap size can ensure that the gap area receives sufficient diffused heat, thereby further improving the heating uniformity of the rectifier cap surface and enhancing the overall anti-icing and de-icing effect.

[0045] In addition, limiting the first and third gaps to between 1–3 mm and the second gap to between 0.3–0.7 mm can effectively avoid structural interference or component compression caused by thermal expansion and contraction of materials during heating, and can also ensure that the heating components maintain an appropriate distance, which is beneficial to long-term operational stability and heating uniformity.

[0046] In some embodiments of the present invention, the first conductive fabric substrate 13 and the second conductive fabric substrate 213 both include an inorganic fiber fabric and a graphene layer deposited on the surface of the inorganic fiber fabric. The inorganic fiber fabric includes quartz fiber fabric, glass fiber fabric, ceramic fiber fabric, alumina fiber fabric or boron fiber fabric.

[0047] Specifically, the graphene layer has excellent electrical conductivity and specific surface area. After being deposited on the surface of inorganic fiber fabric, it can form a continuous and uniform conductive network, thereby effectively improving the overall electrothermal conversion efficiency of the conductive fabric and achieving a faster heating response speed.

[0048] In some embodiments of the present invention, the first electrode 11 and the second electrode 12 are both formed by plasma spraying or electroplating on the first conductive fabric substrate 13; the third electrode 211 and the fourth electrode 212 are formed by plasma spraying or electroplating on the second conductive fabric substrate 213.

[0049] Specifically, both plasma spraying and electroplating processes can achieve a strong bond between the electrode and the conductive fabric substrate, forming a dense and stable electrode structure. This avoids failures such as peeling and cracking during long-term thermal cycling or mechanical vibration, thereby enhancing the structural stability and service life of the system.

[0050] In some embodiments of the present invention, the first electrode 11, the second electrode 12, the third electrode 211 and the fourth electrode 212 are arranged in a strip structure, and the first electrode 11, the second electrode 12, the third electrode 211 and the fourth electrode 212 are made of silver or copper.

[0051] Reference Figure 4 As shown, in a second aspect of the invention, a rectifier cap is also provided, including the application of an electric heating device on the rectifier cap.

[0052] Thirdly, the present invention also provides a method for preparing a rectifier cap, comprising the following steps:

[0053] The mold is prepared according to the size of the rectifier cap, and the mold is preheated.

[0054] The heating element is set according to the size of the rectifier cap, and the heating element is impregnated. The heating element and several reinforcing materials are laid in the mold in sequence according to the design to form a preform.

[0055] A molding auxiliary layer is applied to the surface of the ply, and the mold is vacuum-sealed.

[0056] The preform is cured and shaped.

[0057] Specifically, to reduce the impact of thermal stress during curing, the pretreated mold is placed in a preheating oven and preheated to 50-80℃. The mold is made of aluminum alloy, and the pretreatment includes polishing the mold surface and uniformly applying a release agent to it.

[0058] The reinforcing material is an inorganic fiber fabric, specifically glass fiber fabric. The reinforcing material is laid layer by layer inside the mold, and the heating element is placed between the two layers of reinforcing material near the outside to form a preform. The layup sequence is not unique, and the specific layup design of the reinforcing material is subject to the actual application.

[0059] A molding auxiliary layer, comprising a release membrane and a breathable felt, is applied to the surface of the preform. The entire mold is then sealed with a vacuum bag, and a vacuum pump is connected to evacuate the pressure to 0.1 MPa, creating a negative pressure environment to remove volatiles and air bubbles. After the pressure stabilizes, the vacuum pump is turned off, and the pressure is maintained for 20 minutes.

[0060] The sealed mold is transferred to an autoclave, which is pressurized to 0.25~0.35MPa. Then, the temperature is increased in stages according to the resin system curing curve to achieve curing. After curing, the mold is demolded after cooling and rough and fine machining is performed to obtain the composite material rectifier cap.

[0061] After the composite material is formed, the positive and negative electrodes of the first heating component 1 and the second heating component 2 in the electrothermal device of the sample are led out. A voltage adjustable power supply is used to apply voltage to the sample, and the surface temperature rises. An infrared imager is used to record the surface temperature and observe its uniformity. When a 90 V voltage is applied to the sample, the surface reaches saturation temperature after about 4 minutes, and the temperature essentially stops changing. At this time, the infrared image is as follows: Figure 4As shown, the sample surface temperature is relatively uniform. The temperature distribution coefficient is used to quantitatively describe the uniformity and dispersion of the temperature field, reflecting the degree of non-uniformity in temperature distribution. The temperature distribution coefficient is the ratio of the temperature variation range within a specific region to the average temperature within that region. The smaller the temperature distribution coefficient, the more uniform the temperature distribution; conversely, the larger the coefficient, the more non-uniform the temperature distribution. The formula for calculating the temperature distribution coefficient is as follows:

[0062]

[0063] In the formula:

[0064] —Average temperature of the sample, in degrees Celsius (°C);

[0065] —No. i The temperature value at a point, in degrees Celsius (°C);

[0066] —Number of temperature measurement points on the sample, dimensionless;

[0067] —Temperature distribution coefficient, dimensionless;

[0068] Calculations showed that the temperature distribution coefficient for the first temperature zone was 6.63%, the temperature distribution coefficient for the second temperature zone was 5.56%, and the overall temperature distribution coefficient was 5.88%. The results indicate that the temperature distribution coefficient of the sample does not exceed 10%, demonstrating that the proposed electrothermal device structure design can effectively solve the problem of uneven electric heating of the rectifier cap.

[0069] 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. An electric heating device for de-icing a rectifier cap, characterized in that, The heating element conforms to the rectifier cap, and the heating element includes: The first heating component (1) includes a first electrode (11) and a second electrode (12) extending from the near tip of the rectifier cap towards the peripheral wall, and a plurality of first conductive fabric substrates (13). The first electrode (11) and the second electrode (12) are arranged side by side and connected to the plurality of first conductive fabric substrates (13). There is a first gap between the first electrode (11) and the second electrode (12). The plurality of first conductive fabric substrates (13) are spaced apart from the near tip of the rectifier cap towards the peripheral wall. When the first electrode (11) and the second electrode (12) are energized, the first heating component (1) has a plurality of first temperature zones. The second heating assembly (2) includes a plurality of heating elements (21) disposed on the peripheral wall of the rectifier cap. Two adjacent heating elements (21) are arranged adjacently or spaced apart. Each heating element (21) includes a second conductive fabric substrate (213) and a third electrode (211) and a fourth electrode (212) disposed on the second conductive fabric substrate (213). The third electrode (211) and the fourth electrode (212) are arranged in a ring structure and are coaxially spaced on both sides of the second conductive fabric substrate (213). When the third electrode (211) and the fourth electrode (212) are energized, the second heating assembly (2) has a plurality of second temperature zones. The temperature distribution coefficients of the first and second temperature zones are both within 10%.

2. The electric heating device for electric heating and de-icing of rectifier caps according to claim 1, characterized in that, The first heating component (1) unfolds into a fan-shaped structure. The first conductive fabric substrate (13) is provided in multiple ways, and each of them is in a ring structure. The length direction of the first electrode (11) and the second electrode (12) is arranged along the radial direction of the fan-shaped structure and is respectively located at both ends of the first conductive fabric substrate (13) to be suitable for connecting multiple first conductive fabric substrates (13) at the same time. There is a second gap between two adjacent first conductive fabric substrates (13).

3. The electric heating device for electric heating and de-icing of rectifier caps according to claim 2, characterized in that, The heating element (21) is provided in multiple and in a ring structure. The fourth electrode (212) of any heating element (21) and the third electrode (211) of the adjacent heating element (21) are arranged adjacent to each other and have the same polarity.

4. The electric heating device for electric heating and de-icing of rectifier caps according to claim 2, characterized in that, The heating element (21) is provided in multiple and has a ring structure. The fourth electrode (212) of any heating element (21) and the third electrode (211) of the adjacent heating element (21) are spaced apart and have a third gap, and their polarities are opposite.

5. The electric heating device for electric heating and de-icing of rectifier caps according to claim 4, characterized in that, The values ​​of the first gap and the third gap are both in the range of 1-3 mm, and the value of the second gap is in the range of 0.3-0.7 mm.

6. The electric heating device for electric heating and de-icing of a rectifier cap according to any one of claims 1-5, characterized in that, Both the first conductive fabric substrate (13) and the second conductive fabric substrate (213) include inorganic fiber fabric and graphene layer deposited on the surface of the inorganic fiber fabric. The inorganic fiber fabric includes quartz fiber fabric, glass fiber fabric, ceramic fiber fabric, alumina fiber fabric or boron fiber fabric.

7. The electric heating device for electric heating and de-icing of rectifier caps according to claim 1, characterized in that, The first electrode (11) and the second electrode (12) are formed on the first conductive fabric substrate (13) by plasma spraying or electroplating; the third electrode (211) and the fourth electrode (212) are formed on the second conductive fabric substrate (213) by plasma spraying or electroplating.

8. The electric heating device for electric heating and de-icing of rectifier caps according to claim 1, characterized in that, The first electrode (11), the second electrode (12), the third electrode (211) and the fourth electrode (212) are arranged in a strip structure; the first electrode (11), the second electrode (12), the third electrode (211) and the fourth electrode (212) are made of silver or copper.

9. A rectifier cap, characterized in that, The application of the electric heating device according to any one of claims 1-8 in a rectifier cap.

10. A method for preparing a rectifier cap, used to prepare the rectifier cap as described in claim 9, characterized in that, Includes the following steps: A mold is prepared according to the size of the rectifier cap, and the mold is preheated. The heating element is set according to the size of the rectifier cap, and the heating element is impregnated. The heating element and several reinforcing materials are laid in the mold in sequence according to the designed layup order to form a preform. A molding auxiliary layer is applied to the surface of the ply, and the mold is then vacuum-sealed. The preform is then cured and molded.

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