Electric heating device

Abstract

The utility model relates to the technical field of electric heating materials, in particular to an electric heating device, which comprises a heat insulation layer, a flexible conductive heating layer and a uniform heat conduction layer which are sequentially stacked from bottom to top. The heat insulation layer comprises a heat insulation glue layer and an elastic breathable layer; the flexible conductive heating layer is formed by adding a protective coating on the periphery of a textile fiber layer compounded with a conductive material; the uniform heat conduction layer comprises graphene, resin and a silane coupling agent. The electric heating device provided by the utility model has the advantages that the working current is low, the consumed electric energy is less, the electromagnetic radiation value is far lower than the limit value specified by the International Non-ionizing Radiation Protection Committee Public Safety Standard, the electric heating device can be used trustingly, overload is not generated, fire hazards are avoided, and the preparation process is environment-friendly and does not pollute the environment.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of electric heating material, especially relates to an electric heating device. BACKGROUND

[0002] The existing heating technologies of automobile seat heating, automobile steering wheel heating or civil electric blanket all adopt traditional electric heating devices, and take electric heating wire 10 (copper wire or carbon fiber) as heating material, the cross section diameter of electric heating wire 10 is usually 1mm~2mm, and the spacing between electric heating wire 10 is generally 10-40mm, such as Figure 1 In the spacing range, if the effective heating temperature to human body is wanted to be reached, the working current of the cross section of electric heating wire 10 needs to reach 3A-10A, and the large working current consumption needs too much electric energy, which is not good for new energy electric vehicle, and the simultaneous heating of multiple seats and steering wheels in winter will consume too much electric energy of battery, and reduce the endurance mileage.

[0003] For electric blanket, only the heat generated by electric heating wire 10 to the upper part is useful to human body, and the heat to the lower half is basically lost to the back of electric blanket, so as to cause heat loss.If alternating current is used, such as civil electric blanket, excessive electromagnetic radiation will be generated, and the radiation value far exceeds the safety value 0.1uT specified in the international standard "International Non-ionizing Radiation Protection Committee Public Safety Standard", for example, the electromagnetic radiation measured value of single-person electric blanket exceeds 1.0uT, and the electromagnetic radiation value of double-person electric blanket exceeds 2.0uT. And large working current is easy to cause overload of electric heating device, and there is fire hazard. The above electromagnetic radiation problem exists universally in the process of using electric blanket.

[0004] Meanwhile, the large spacing of electric heating wire 10 and heat loss will also cause that the time from the power supply of heating wire to the feeling of heat by human body is long, for example, the heating of automobile seat or steering wheel in winter generally needs 2-3 minutes to feel hot, and the buttocks and fingers of human body will feel cold in the first few minutes. Figure 2 As shown in the figure, the current flows from the positive electrode to the negative electrode when electric heating wire 10 heats, the line is arranged in the form of reciprocating bending, the current directions of adjacent two electric heating wires 10 are opposite, according to the right-hand amperes rule, the electromagnetic field direction (as shown in the figure) is superimposed in the same direction in the middle position, instead of being counteracted, so that the electromagnetic radiation intensity generated by adjacent electric heating wires is superimposed and amplified, and harm is caused to human body. Figure 1

[0005] The difference from the above-mentioned electric heating device is the heating device of electric heating film, such as Figure 3As shown, electrothermal film heating devices typically use copper / aluminum foil or silver paste as adjacent, non-conductive electrodes 20, and carbon paste 21 as the heating material. The operating current and electromagnetic radiation of electrothermal film heating devices are relatively small. However, the electrodes 20 of the electrothermal film need to be fabricated using silver paste printing or copper / aluminum foil etching processes. Figure 4 As shown, the overall thickness of the electrodes 20 and carbon paste 21 of the heating film 22 is generally less than 0.2mm, much smaller than the thickness of the heating wire (1-2mm in diameter). It can be arbitrarily set in the heating width direction. Furthermore, a heat insulation layer is added under the heating film, which directs the downward heat of the entire heating film upwards, converting it into heat useful to the human body. Compared to the heating wire, the heating speed of the heating film is very fast; the human body can feel the heat within one minute or even a few seconds. Moreover, compared to… Figure 1 The heating wire consumes less current and emits less electromagnetic radiation. Figure 1 and Figure 4 Put together, such as Figure 5 As shown, the heating wire 10 has a large operating current and generates a large heat intensity, dissipating heat in a circular radial pattern. The heating film 22 has a small operating current and generates a relatively small heat intensity per unit width. The width of the heating film 22 is much greater than its thickness, so the heat dissipation direction is vertical. The heat insulation layer on the bottom surface blocks the downward heat, preventing heat transfer downwards. Therefore, under the condition that the heating film 22 and the heating wire 10 have the same width, the heat accumulated upwards by the heating film 22 can reach the same amount of heating heat as the heating wire 10. That is, heating with the heating film can compensate for the disadvantage of the heating wire consuming a large operating current, achieving the same heating effect on the human body.

[0006] However, as mentioned earlier, this type of electric heating film 22 requires a heat insulation layer on its bottom surface to achieve its energy-saving advantage. Because the carbon paste is extremely thin and brittle, protective layers are needed on both the top and bottom surfaces to prevent it from breaking under stress. The bottom heat insulation layer needs to be made of a smooth and uniform material, such as a flexible resin adhesive layer, to prevent increased internal fracture resistance under stress. Extensive fatigue tests (standard seat fatigue tests: pseudo-hip torsion and knee impact) have been conducted in engineering practice, and the results show that it is difficult to find a satisfactory material. Furthermore, the limited heat generated by the electric heating film comes into contact with the heat insulation layer, causing some heat to be lost into the insulation layer. The thicker the insulation layer, the better the protection of the carbon paste, but the more heat is lost, and the less effective heat is provided for heating the human body. In addition, the production process of this type of electric heating film 22 involves a series of problems such as pollution from heavy metals, heavy acids and heavy alkalis in the waste liquid. Therefore, this type of electric heating film heating device cannot be used in heating fields such as car seat heating or household electric blankets, which are often subject to fatigue stress. It can only be used for underfloor heating. However, in order to achieve a sufficient indoor heating temperature, it is necessary to increase the working current to allow heat to pass through the floor, which consumes a lot of electrical energy and generates electromagnetic radiation. Utility Model Content

[0007] In view of this, the present invention aims to provide an electric heating device to solve the technical problems of existing electric heating devices, such as high operating current, high energy consumption, excessive electromagnetic radiation, environmental pollution, and low reliability.

[0008] To achieve the above objectives, the technical solution created by this utility model is implemented as follows:

[0009] An electric heating device includes, from bottom to top, a heat insulation layer, a flexible conductive heating layer, and a uniform heat-conducting layer stacked sequentially.

[0010] Furthermore, the flexible conductive heating layer is a textile fiber layer composited with conductive particles, and a protective coating is applied around the flexible conductive heating layer.

[0011] Furthermore, the flexible conductive heating layer has a length of 1m to 10m, a width of 5mm to 80mm, a thickness of 0.05mm to 35mm, and an effective heating area of ​​0.25m². 2 Within the specified range, the operating current of the flexible conductive heating layer is less than 3A; or, the length of the flexible conductive heating layer is 10m~30m, the width is 5mm~100mm, the thickness is 0.05mm~100mm, and the effective heating area is 0.25m². 2 ~5m 2 Within the specified range, the operating current of the flexible conductive heating layer is less than 5A.

[0012] Furthermore, the protective coating consists of a resin and a silane coupling agent, with the resin accounting for 98% by weight and the silane coupling agent accounting for 2% by weight.

[0013] Furthermore, the resin is an aliphatic resin or a polycarbonate resin.

[0014] Furthermore, the insulation layer includes an insulation adhesive layer and an elastic breathable layer located below the insulation adhesive layer.

[0015] Furthermore, the heat-insulating adhesive layer consists of a breathable substrate and an adhesive coated on the breathable substrate, and the elastic breathable layer is a 3D spacer fabric or a sandwich mesh fabric.

[0016] Furthermore, the adhesive is a solvent-free butyl adhesive, and the weight percentages of each component in the solvent-free butyl adhesive are as follows:

[0017] Butyl rubber: 55%;

[0018] Polyisobutylene: 15%;

[0019] Calcium carbonate: 10%;

[0020] C5 / C9 petroleum resin: 10%;

[0021] Talc: 6.5%;

[0022] Antioxidant: 1%;

[0023] UV absorber: 1%;

[0024] Aminosilane: 1.5%.

[0025] Furthermore, the uniform thermally conductive layer is composed of graphene, resin and silane coupling agent, with the resin accounting for 98% by weight, the silane coupling agent accounting for 1.5% by weight, and the graphene nanosheets accounting for 0.5% by weight.

[0026] Furthermore, the resin is a polycarbonate-type waterborne anionic polyurethane resin.

[0027] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0028] (1) This utility model reduces the contact thickness between the heating layer and the insulation layer by setting a heat insulation layer, thereby reducing heat transfer and preventing downward heat loss, making the heating speed faster and more energy-efficient; by setting a flexible conductive heating layer: according to the heating area and heating temperature of the heater, the content of conductive particles inside the heating layer is adjusted when making the heating layer material, and then the length, width and thickness of the heating layer are set so that the resistance value between the wires at both ends of the heating layer reaches the set resistance value range, so that the working current flowing through the heating layer is less than 3A or 5A, achieving the expected heating temperature effect. At the same time, by setting a uniform heat-conducting layer, the heat in the vertical direction of the heating layer is conducted upward as quickly as possible. Compared with existing electric heating devices, under the same heating area and heating effect, the working current of this utility model is less than 3A or 5A, and the measured electromagnetic radiation value is 0.001μT-0.01μT, which is far less than the 0.1μT specified in the "International Commission on Non-Ionizing Radiation Protection Public Safety Standard", and the impact on the human body is basically negligible. It is safer, more reliable and practical than existing electric heating devices.

[0029] (2) Under the same heating area and heating effect, the working current required by this utility model is less than half of the working current of existing electric heating devices, so this utility model can save more than 50% of electrical energy.

[0030] (3) Because the flexible conductive heating layer of this utility model has a protective coating around its perimeter, leakage and discharge phenomena can be avoided on the top, bottom and sides of the heating layer. In particular, since the heating layer circuit is arranged in a reciprocating bending form, the distance between two adjacent heating layer circuits will be very small according to the wiring requirements, making them easy to come into contact. If there is no protective layer on both sides, short circuits will occur on the sides of the heating layer, causing the heater to fail. Applying a protective layer can prevent this hidden danger. At the same time, the protective coating is flexibly applied around the heating layer, so that the conductive particles inside the flexible conductive heating layer remain stable inside the textile fiber layer. They will not increase the resistance due to bending force, causing the working current to decrease and the heater to not heat up or fail.

[0031] (4) This utility model uses a non-chemical reaction process to manufacture electric heating devices, which overcomes the pollution problems caused by silver paste printing or copper / aluminum foil etching in traditional processing processes.

[0032] (5) The electric heating device provided by this utility model is flexible and can be made into a three-dimensional shape, not limited to a planar layout.

[0033] (6) The electric heating device provided by this utility model can be widely used in the military-civilian integration industry, such as wearable heating, electric blankets, car seats, steering wheel heating and battery pack winter failure prevention. Attached Figure Description

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of this invention. The illustrative embodiments and descriptions of this invention are used to explain this invention and do not constitute an undue limitation of this invention. In the drawings:

[0035] Figure 1 This is a schematic diagram of the cross-sectional structure of the heating wire in an existing electric heating device.

[0036] Figure 2 This is a schematic diagram of the wiring of the heating wire in an existing electric heating device.

[0037] Figure 3 This is a schematic diagram of the structure of an existing electrothermal film heating device;

[0038] Figure 4 This is a schematic diagram comparing the cross-sectional structures of existing electric heating wire devices and electric heating film devices;

[0039] Figure 5 This is a schematic diagram comparing the performance of existing electric heating wire devices and electric heating film devices.

[0040] Figure 6 This is a schematic cross-sectional view of the electric heating device described in the embodiment of this utility model.

[0041] Figure 7 These are cross-sectional and top views of the elastic breathable layer under pressure according to the embodiments of this utility model.

[0042] Figure 8 This is a schematic diagram of the circuit distribution of the flexible conductive heating layer arranged on a car seat according to an embodiment of the present invention;

[0043] Figure 9 This is a schematic diagram showing the factors affecting the resistance of the flexible conductive heating layer cross-section in the vertical direction and the circuit layout direction.

[0044] Explanation of reference numerals in the attached figures:

[0045] Heating wire 10, electrode 20, carbon paste 21, heating film 22, heat insulation layer 30, flexible conductive heating layer 31, uniform heat-conducting layer 32, heat insulation adhesive layer 301, elastic breathable layer 302, protective coating 311. Detailed Implementation

[0046] To make the purpose, technical solution, and advantages of this utility model clearer, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this utility model and do not constitute a limitation thereof.

[0047] It should be noted that, without conflict, the embodiments and features in the embodiments of this utility model can be combined with each other.

[0048] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this utility model and 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, and therefore should not be construed as a limitation on this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0049] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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 utility model based on the specific circumstances.

[0050] The present invention will now be described in detail with reference to the figures and embodiments.

[0051] like Figure 6 As shown, Embodiment 1 of this utility model provides an electric heating device, comprising, from bottom to top, a heat insulation layer 30, a flexible conductive heating layer 31, and a uniform heat-conducting layer 32, stacked sequentially. The heat insulation layer 30 and the flexible conductive heating layer 31, as well as the flexible conductive heating layer 31 and the uniform heat-conducting layer 32, are bonded and fixed together. The two ends of the flexible conductive heating layer 31 are connected to the positive and negative terminals of a power source via wires, serving as the heat source for the electric heating device. The flexible conductive heating layer 31 generates heat after being energized. The heat insulation layer 30 provides downward heat insulation, preventing heat from being transferred downwards and ensuring that heat is only transferred upwards. The uniform heat-conducting layer 32 provides uniform heat conduction. A protective coating 311 is applied around the flexible conductive heating layer 31 to prevent wear.

[0052] The heat insulation layer 30 includes, but is not limited to, the heat insulation adhesive layer 301 and the elastic breathable layer 302. The elastic breathable layer 302 is a 3D spacer fabric or a sandwich mesh fabric. The present invention can also use heat insulation layer 30 made of other heat insulation materials besides the heat insulation adhesive layer and the elastic breathable layer 302.

[0053] like Figure 6 As shown, the heat-insulating adhesive layer 301 is made of a breathable substrate, such as non-woven fabric. Adhesive is coated onto the non-woven fabric to form the heat-insulating adhesive layer 301, which mainly serves as an adhesive and heat-insulating layer. One side of the heat-insulating adhesive layer 301 is bonded to the flexible conductive heating layer 31, and the other side is bonded to the elastic breathable layer 302. The elastic breathable layer 302 is made of polyester fibers woven into a mesh-like structure through warp knitting. It can withstand pressure and has elasticity, and the mesh-like spaces are filled with air. This 3D mesh typically serves as a seat ventilation system. Figure 7As shown, when the elastic breathable layer 302 is compressed vertically under pressure, there are certain gaps between the layers. Looking from above, there are also gaps in the vertical direction between the mesh layers, which are sealed off by pressure. Because when the flexible conductive heating layer 31 of this invention comes into contact with the heat insulation layer 30, the heat insulation adhesive layer 301 of the heat insulation layer 30 is in direct contact with the flexible conductive heating layer 31. While the heat insulation adhesive layer 301 can prevent the heat from the flexible conductive heating layer 31 from being conducted downwards, the heat insulation adhesive layer 301 itself will be heated, resulting in a small loss of heat. However, further down, as... Figure 7 As shown, only a portion of the upper surface of the elastic breathable layer 302 has substantial contact with the heat insulation layer 301, while the rest is void with no substantial contact. Therefore, there is no heat loss. The actual contact thickness is only a portion of the upper surface of the heat insulation layer 301 and the elastic breathable layer 302. Thus, the elastic breathable layer 302 can achieve a good heat insulation effect. As mentioned in the background art, the bottom surface of the electric heating film also needs a heat insulation layer to achieve its energy-saving advantage. However, because the heating carbon paste is extremely thin and brittle, protective layers need to be added to both the upper and lower surfaces of the carbon paste to prevent it from breaking under stress. The lower heat insulation layer needs to be made of a flat and uniform material, such as a flexible resin adhesive layer, to prevent internal fracture under stress, which would lead to increased resistance. In engineering practice, a large number of fatigue tests (standard fatigue tests for seats: pseudo-hip torsion and knee pressure impact) have been conducted, and the results show that it is difficult to find a satisfactory material. Furthermore, the limited heat generated by the electric heating film comes into contact with the insulation layer, causing some heat to be lost into the insulation layer. The thicker the insulation layer, the better the carbon paste protection, but the more heat is lost, resulting in less effective heat for heating the human body. Compared to the insulation layer of the electric heating film, this invention uses a 3D mesh material. Due to the air barrier between layers, the actual contact thickness of the insulation layer 30 is reduced. Heat loss is limited to the insulation adhesive layer 301 and a portion transferred to the upper surface of the elastic breathable layer 302. In contrast, the insulation layer of the electric heating film requires insulation across the entire surface; the thicker the layer, the more heat is lost, while a thinner layer can lead to carbon paste breakage and film failure. Therefore, the electric heating device provided by this invention can more effectively prevent downward heat loss than the electric heating film, allowing for better heat utilization and faster heating.

[0054] The heat insulation layer 30 provided by this invention provides satisfactory heat insulation from both economic and practical perspectives. When heating is required, the 3D mesh material acts as an insulator; when heating is not needed, it allows for ventilation. In contrast, while silicone or aerogel materials have lower thermal conductivity and can better impede airflow and reduce heat transfer, their insulation performance is directly proportional to their thickness. For the limited heat generated by the heating layer of this invention, better insulation results in greater heat loss, making the 3D mesh material superior in terms of heat insulation. Extensive testing with various heat insulation materials has verified that the 3D mesh material offers better insulation.

[0055] In one specific embodiment of this utility model, the heat insulation layer 301 of the heat insulation layer 30 is a 60-gram non-woven fabric substrate coated with a 0.8 mm thick solvent-free butyl adhesive. The 60-gram non-woven fabric has moderate strength and can support the butyl adhesive, thus serving as a substrate. The 0.8 mm thick solvent-free butyl adhesive itself is viscous and can provide both bonding and heat insulation. The weight percentages of the components in the solvent-free butyl adhesive are as follows:

[0056] Butyl rubber: 55%;

[0057] Polyisobutylene: 15%;

[0058] Calcium carbonate: 10%;

[0059] C5 / C9 petroleum resin: 10%;

[0060] Talc: 6.5%;

[0061] Antioxidant: 1%;

[0062] UV absorber: 1%;

[0063] Aminosilane: 1.5%.

[0064] By adjusting the proportions of the above components and the thickness of the solvent-free butyl adhesive, a comprehensive comparison shows that the adhesive with a thickness of about 0.8 mm prepared by the above combination can achieve a satisfactory heat insulation effect.

[0065] The substrate of the flexible conductive heating layer 31 is a textile fiber layer, which can be natural fiber or chemical fiber. Natural fibers include plant fibers, animal fibers, and mineral fibers, while chemical fibers include regenerated fibers, synthetic fibers, and inorganic fibers. When the flexible conductive heating layer 31 uses a textile fiber layer, since the textile fibers themselves do not have conductivity, conductive particles need to be composited on the textile fiber layer.

[0066] The conductive particles can be any of copper, aluminum, silver, carbon fiber powder, or other conductive materials. When making the flexible conductive heating layer 31, copper powder, aluminum powder, silver powder, and carbon fiber powder are added to the resin. The copper powder, aluminum powder, silver powder, and carbon fiber powder are composited in the structure of the textile fiber layer by coating or immersion to form a conductive coating, so that the flexible conductive heating layer 31 has conductivity.

[0067] The above-mentioned manufacturing process of the flexible conductive heating layer 31 is a cold processing process, while traditional silver paste printing is a hot processing process. During the silver paste printing process, heavy metal waste liquid is generated, which pollutes water sources and land, causing heavy metal pollution to the environment. In addition, the drying process of silver paste printing requires a lot of electrical energy and generates a lot of waste gas, which not only seriously pollutes the air, but also wastes a lot of electrical energy.

[0068] This invention uses coating or immersion to form a conductive coating, which does not produce heavy metal waste liquid and waste gas, thus avoiding heavy metal pollution to the environment. Furthermore, it eliminates the need for a drying step, preventing energy waste.

[0069] In one specific embodiment of this utility model, such as Figure 8 As shown, the flexible conductive heating layer 31 has a length of 7.83m, a width of 25mm, a thickness of 0.1mm, and an effective heating area of ​​approximately 160,000mm². 2 (0.16m) 2 The flexible conductive heating layer 31 operates at a current of 2.5A, at which point the average temperature within the effective heating area reaches 41°C, meeting the temperature requirements for seat heating. The arrangement parameters of the flexible conductive heating layer 31, such as line length, width, and thickness, are set based on the given foam shape of the car seat, as well as the heating area and temperature requirements of the seat heater. The conductive particles inside the flexible conductive heating layer 31 are physically distributed within the textile fiber structure. By varying the amount of conductive particles added during manufacturing, different resistivity ρs can be obtained for the flexible conductive heating layer 31. The resistance value R at both ends of the flexible conductive heating layer 31 is calculated based on the resistivity ρ. The formula for calculating the resistance value R is as follows:

[0070] R=ρ L / S;

[0071] Where: L is the length of the flexible conductive heating layer 31, and S is the cross-sectional area of ​​the flexible conductive heating layer 31, which is the product of the width and thickness of the flexible conductive heating layer 31.

[0072] When ρ=1.18 10 -6 At Ω / m, the resistance value R across the flexible conductive heating layer 31 is 1.18 x 10⁻⁶. -6 11.83 / 0.025x0.0001=5.58Ω.

[0073] exist Figure 8 When the wiring of the heater reaches the conditions of seat heating area and heating temperature, the measured working current of the flexible conductive heating layer 31 is 2.5A and the working voltage is 14V. According to the relationship between voltage, current and resistance, the resistance value of the two ends of the flexible conductive heating layer 31 can be obtained as R=14 / 2.5=5.6Ω, which is consistent with the calculation.

[0074] The above is a specific embodiment of this utility model, in which the flexible conductive heating layer 31 has a uniform width of 25mm. It can also be adapted to meet different requirements of the electric heating device, such as different heating temperatures in heating areas along different length directions. Figure 9 As shown, different widths are set in the width (y) direction; different thicknesses are set in the thickness (x) direction; and different resistivity (d) is set in the length (z) direction. The setting is to change the content of conductive particles in the textile fiber layer within different length ranges; by changing the parameters in the x, y, and z directions and the resistivity in the length direction, the heating requirements of different regions of the flexible conductive heating layer 31 at different temperatures can be achieved.

[0075] At this point, the integral formula for calculating the resistance value at both ends of the flexible conductive heating layer 31 (for reference) is:

[0076] R= dxdydz

[0077] in: dx is the resistivity variable along the length of the flexible conductive heating layer 31, di is the curvature variable along the length of the flexible conductive heating layer 31, dx is the thickness variable along the thickness of the flexible conductive heating layer 31, dy is the width variable along the width of the flexible conductive heating layer 31, and dz is the length variable along the length of the flexible conductive heating layer 31.

[0078] like Figure 6As shown, the flexible conductive heating layer 31 provided by this utility model is manufactured by adding copper powder, aluminum powder, silver powder, carbon fiber powder, or other conductive powders to resin during the manufacturing process. The copper powder, aluminum powder, silver powder, carbon fiber powder, or other conductive powders are then incorporated into the structure of the textile fiber layer through coating or immersion methods to form a conductive coating, thus giving the flexible conductive heating layer 31 conductivity. The conductive particles exist in a dispersed form within the heating layer, i.e., as dispersed electrodes, rather than as solid electrodes. Therefore, this avoids the problem mentioned in the background art where the electrodes of existing heating wires and heating films are all in solid form; the electrodes of heating wires are copper wires or carbon fiber wires, and the electrodes of heating films are silver paste, etched copper foil, or aluminum foil. Physical electrodes generate electromagnetic radiation under alternating current. The distributed electrodes of this invention do not generate electromagnetic radiation, and the operating current is less than 3A or 5A. The measured electromagnetic radiation value is 0.001μT-0.01μT, which is far less than the 0.1μT specified in the International Commission on Non-Ionizing Radiation Protection Public Safety Standard. The impact on the human body is negligible. Compared with existing electric heating devices, it is safer, more reliable and practical.

[0079] In another specific embodiment of this utility model, based on the general dimensions of existing single-person electric blanket products, the flexible conductive heating layer 31 is given to have a length of 15.5m, a width of 40mm, a thickness of 0.1mm, and an effective heating area of ​​approximately 0.96m². 2 The flexible conductive heating layer 31 operates at a current of 3.5A, and the average temperature within the effective heating area reaches 39.5°C, which meets the temperature requirements of a typical single-person electric blanket.

[0080] like Figure 6 As shown, the flexible conductive heating layer 31 has a protective coating 311 around its perimeter. The resin contained in the protective coating 311 is an aliphatic resin or a polycarbonate resin. The protective coating 311 can prevent leakage and discharge phenomena on the top, bottom, and sides of the flexible conductive heating layer 31, especially as... Figure 8 As shown, the circuitry of the flexible conductive heating layer 31 is arranged in a reciprocating bending pattern. The spacing between the circuits of adjacent flexible conductive heating layers 31 is very small depending on the wiring requirements, making them easy to contact. If there is no protective coating 311 on both sides, a short circuit may occur on the sides of the flexible conductive heating layer 31, causing the electric heating device to fail. Applying the protective coating 311 can prevent this potential hazard. At the same time, the protective coating 311 is applied around the flexible conductive heating layer 31, ensuring that the conductive particles inside the flexible conductive heating layer 31 remain stable within the textile fiber layer, preventing resistance changes due to bending and thus avoiding increased operating current and electric heating device failure.

[0081] In one specific embodiment of this utility model, the resin contained in the protective coating 311 is an anionic aliphatic aqueous polyurethane dispersion. The formulation of the protective coating 311 is as follows:

[0082] ① Anionic aliphatic waterborne polyurethane dispersion with a solid content of 35%: its weight percentage is 98%;

[0083] ②Silane coupling agent: An organosilicon compound is used, the chemical name of which is 3-aminopropyltrimethoxysilane, the chemical formula is (CN3O)3SiC3H6NH2, and the weight percentage is 2%.

[0084] Anionic aliphatic waterborne polyurethane dispersions have excellent wear resistance and dry / wet rubbing properties. Silane coupling agents can improve the strength, weather resistance, and water resistance of the dispersions. In particular, the higher the heating temperature in the heating layer, the stronger the adhesion between the dispersion and the heating layer becomes, thus making the internal structure of the heating layer more stable.

[0085] The polyurethane dispersion and silane coupling agent are mixed in the above proportions and dispersed and stirred to form a coating emulsion. Then, the flexible conductive heating layer 31 is partially immersed in the emulsion with the other two ends remaining intact. After being removed, it is placed in a blower box and dried at 150°C for 30 minutes.

[0086] Using the above method, a sealed protective coating 311 was formed around the flexible conductive heating layer 31. In a specific embodiment of this utility model, three groups of 21 identical samples (7 samples in each group) were fabricated. The samples were 300 mm long, 20 mm wide, and 0.1 mm thick. Wires were connected to both ends of the samples where the protective coating 311 was not applied along their length. Then, three different durability fatigue tests were conducted on each group of samples to verify the actual protective effect of the protective coating 311. These three sets of tests were the fatigue life tests commonly used in the automotive seat industry for electronic products.

[0087] Group 1, knee impact fatigue test, 75kg round head with a diameter of 100mm, single-point impact cycle 100,000 times. Detailed test results are listed in Table 1.

[0088] Table 1

[0089]

[0090] The test results show that the protective coating 311 has a bending resistance to the flexible conductive heating layer 31 that far exceeds the test standard.

[0091] Group 2, torsional fatigue test, 75kg artificial buttock, 100,000 torsional fatigue cycles. Detailed test results are listed in Table 2.

[0092] Table 2

[0093]

[0094] The test results show that the radial torsional stress resistance of the protective coating 311 to the flexible conductive heating layer 31 far exceeds the test standard.

[0095] Group 3, high and low temperature impact fatigue test, 12 hours x 100 cycles. Detailed test results are listed in Table 3.

[0096] Table 3

[0097]

[0098] The test results show that the weather resistance of the protective coating 311 to the flexible conductive heating layer 31 far exceeds the test standard.

[0099] The above is a specific embodiment of the present invention, which verifies that the protective coating 311 has reliable adhesion to the flexible conductive heating layer 31. At the same time, the protective coating 311 is applied around the flexible conductive heating layer 31, so that the conductive particles inside the flexible conductive heating layer 31 remain stable inside the textile fiber layer and will not cause resistance changes due to bending, resulting in increased working current and failure of the electric heating device.

[0100] Because the flexible conductive heating layer 31 is flexible and coated with a protective coating 311 around its perimeter, it does not require a physical electrode and is filled with conductive particles. The flexible conductive heating layer 31 itself acts as the heating element, unlike the heating carbon paste in an electric heating film. The heating carbon paste in an electric heating film is thin and brittle, requiring a flat insulating layer for protection to prevent breakage and failure. Therefore, the flexible conductive heating layer 31 can use an insulating layer that only requires partial contact. This invention uses a 3D mesh material. Due to the air barrier between layers, the actual contact thickness of the insulating layer is reduced, and heat loss is limited to the insulating adhesive layer 301 and a portion transferred to the upper surface of the elastic breathable layer 302. In contrast, the insulating layer of an electric heating film requires insulation across its entire surface; the thicker the layer, the more heat is lost, while a thinner layer can lead to carbon paste breakage and electric heating film failure. Therefore, the electric heating device provided by this invention can utilize heat more effectively than an electric heating film, with less heat loss and a faster heating speed.

[0101] Existing electric heating wire devices typically use copper or carbon fiber wires with a cross-sectional diameter of 1mm to 2mm. Whether or not a heat insulation layer is placed beneath the copper or carbon fiber wires, they offer no heat insulation effect. Therefore, a working current of 3A or higher is required to cover the corresponding heating area. In contrast, the flexible conductive heating layer 31 of this invention has a width of 10mm to 40mm, providing a larger contact area. Furthermore, a heat insulation layer 30 is placed beneath the flexible conductive heating layer 31. Therefore, this invention only requires a working current of less than 3A to ensure coverage of the same heating area. Therefore, this invention can achieve the same heating effect as traditional electric heating devices (composed of copper or carbon fiber wires) with a lower operating current. In terms of thickness, the flexible conductive heating layer 31 in this invention is only 0.05mm to 0.5mm thick, and the cross-sectional thickness of the copper or carbon fiber wire is between 1mm and 2mm. The current passing through the cross-section reaches 3A-10A, which places high demands on the material of the copper or carbon fiber wire. If there are cracks in the local area or the wire breaks under stress during use, it is easy to cause current overload and fire. Even without the above-mentioned hazards, the large current flowing through the cross-section of the heating wire during use can cause local overheating around the heating wire. Usually, an NTC temperature sensor needs to be installed on the surface of such electric heating devices to monitor whether the entire heater is overheating. Once the temperature exceeds the standard, the current will be automatically cut off to cool down. Therefore, such electric heating devices have many safety hazards during use. Moreover, as mentioned in the background art, the heating wire will generate seriously excessive electromagnetic radiation, which will harm human health. The flexible conductive heating layer 31 provided by this utility model has a thin thickness, and the current passing through a unit cross section is very small. The current passing through the entire cross section is less than 3A. The working current is a safe working current, so it can be used with confidence. It will not cause local overheating or overload, eliminates fire hazards, does not have physical electrodes, has no electromagnetic radiation, and the manufacturing process is environmentally friendly and does not pollute the environment.

[0102] Because the flexible conductive heating layer 31 is a flexible thin-layer structure, it can be configured into any shape. An example is... Figure 8 As shown, the flexible conductive heating layer 31 is distributed as evenly as possible to achieve a uniform heating effect.

[0103] The uniform thermally conductive layer 32 is composed of graphene, resin, and silane coupling agent. During its fabrication, the graphene, resin, and silane coupling agent are mixed together to form a mixed emulsion, which is then coated onto the surface of the flexible conductive heating layer 31, thus forming the uniform thermally conductive layer 32 on top of the flexible conductive heating layer 31. Graphene primarily serves a heat dissipation function, the resin provides wear resistance, and the silane coupling agent provides both wear resistance and adhesion.

[0104] In one specific embodiment of this utility model, the resin contained in the uniform heat-conducting layer 32 is a polycarbonate-type waterborne anionic polyurethane resin. Specifically, the formulation of the uniform heat-conducting layer 32 is as follows:

[0105] ① Polycarbonate-type waterborne anionic polyurethane resin with a solid content of 30%: 98% by weight;

[0106] ②Silane coupling agent: An organosilicon compound is used, its chemical name is 3-aminopropyltrimethoxysilane, its chemical formula is (CH3O)3SiC3H6NH2, and its weight percentage is 1.5%;

[0107] ③ Graphene nanosheets: 0.5% by weight.

[0108] Polycarbon-based waterborne anionic polyurethane resin has excellent wear resistance and aging resistance. Silane coupling agent can improve the resin's weather resistance and water resistance. Graphene is the material with the highest thermal conductivity, which can enhance the mechanical strength of the resin and also play a role in fully dissipating and conducting heat from the flexible conductive heating layer 31 upwards.

[0109] The polyurethane resin, silane coupling agent, and graphene nanosheets are mixed in the above proportions, dispersed and stirred to form a coating emulsion, and then coated on the surface of the flexible conductive heating layer 31. The emulsion is then placed in a blower box and dried at 150°C for 30 minutes.

[0110] Using the above method, a uniform heat-conducting layer 32 that serves to dissipate heat is formed on the top of the flexible conductive heating layer 31. At the same time, the polycarbonate resin has excellent aging resistance and strength, which can better protect the flexible conductive heating layer from wear and failure.

[0111] Since the heat insulation layer 30, the flexible conductive heating layer 31 and the uniform heat-conducting layer 32 are all flexible, they can be made into any shape and are not limited to a planar layout.

[0112] The electric heating device provided by this utility model can be widely used in the field of military-civilian integration, such as wearable heating, electric blankets, car seats, steering wheel heating, and battery pack winter failure prevention.

[0113] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this utility model disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this utility model can be achieved, and this is not limited herein.

[0114] The specific embodiments described above do not constitute a limitation on the scope of protection of this utility model. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. An electric heating device, characterized in that The heat insulation layer, the flexible conductive heating layer and the uniform heat conduction layer are sequentially stacked from bottom to top; the length of the flexible conductive heating layer is 1m-10m, the width is 5mm-80mm, the thickness is 0.05mm-35mm, the effective heating area is 0.25m 2 The working current of the flexible conductive heating layer is less than 3A within the range. Alternatively, the length of the flexible conductive heating layer is 10 m~30 m, the width is 5 mm~100 mm, the thickness is 0.05 mm~100 mm, and the effective heating area is within 0.25 m 2 ~5 m 2 The working current of the flexible conductive heating layer is less than 5 A.

2. An electric heating device according to claim 1, characterised in that The heat insulation layer comprises a heat insulation glue layer and an elastic breathable layer located below the heat insulation glue layer.

3. An electric heating device according to claim 2, c h a r a c t e r i z e d in that The heat insulation glue layer is composed of a breathable base material and glue coated on the breathable base material, and the elastic breathable layer is a 3D spacer fabric or a sandwich mesh cloth.

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