Metal shell anti-explosion heating plate with PTC (Positive Temperature Coefficient) characteristic

Abstract

A metal shell anti-explosion heating plate with PTC characteristics belongs to the technical field of anti-explosion heating and comprises a PTC heating film, protection plates and a power connector, the power connector is electrically connected with the PTC heating film, the protection plates are arranged on the upper face and the lower face of the PTC heating film respectively, and the protection plates are connected with the ground; the PTC heating film made of the PET base material serves as a heating body, so that the final product has the PTC self-temperature-limiting characteristic, and the surface temperature requirement of T5 or T6 is met under the condition that a temperature control device does not exist. A temperature control device is omitted, product cost and complexity are reduced, product reliability is improved, protection plates are pasted on the upper surface and the lower surface of the PET insulating material, and the heat resistance grade of the material at high temperature is improved. And the insulation failure of the product in the high-temperature impact test process is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of explosion-proof heating, and specifically refers to a metal shell explosion-proof heating plate with PTC characteristics. Background Art

[0002] In the existing technology, non-metallic matrix infrared radiation heaters that meet GB / T4654 have the advantages of low cost and good designability. Some products also have certain PTC characteristics. The maximum surface temperature of the product can be controlled between T5 and T6 without the need for a thermostat, which has higher safety. However, such non-metallic matrix infrared radiation heaters generally cannot meet the relevant explosion-proof requirements of GB3836.1. The main reason is that the protection level of such products is weak and cannot meet the requirements of 7.4 "electrostatic charge of external non-metallic materials" and 26.4.2 "impact test" in the shell protection of GB3836.1 standard. Summary of the invention

[0003] In view of the above situation, in order to overcome the defects of the prior art, an embodiment of the present invention provides a metal shell explosion-proof heating plate with PTC characteristics, which at least partially solves the above technical problems.

[0004] The technical solution adopted in the embodiment of the present invention is as follows: a metal shell explosion-proof heating plate with PTC characteristics, including a PTC heating film, a protective plate, and a power connector, the power connector is electrically connected to the PTC heating film, the protective plates are respectively arranged on the upper and lower surfaces of the PTC heating film, and the protective plates are grounded.

[0005] Furthermore, the material of the protective plate is a rigid conductive metal plate.

[0006] Furthermore, the material of the protective plate is one of stainless steel plate, aluminum plate and galvanized iron plate.

[0007] Furthermore, the thickness of the heating plate is 2-6 mm.

[0008] Furthermore, the thickness of the protective plate is 0.05-0.2 mm.

[0009] Furthermore, a plurality of connection holes are evenly arranged along the edge line of the protection plate, and the connection holes on the protection plates on the upper and lower surfaces of the PTC heating film are arranged correspondingly.

[0010] Furthermore, the corresponding connection holes on the two protective plates are connected by rivets.

[0011] Furthermore, the preparation method of the PTC heating film is: Printing a silver paste layer on one side of the PET base film to obtain a silver paste printed coil; Printing a carbon paste layer on the side of the silver paste printed coil away from the PET base film to obtain a silver and carbon paste printed coil; Thermally laminating a first adhesive film layer on the side of the silver-printed and carbon-paste coil away from the PET base film to obtain a PTC base film; Attaching a metal shielding layer on the side of the PTC base film away from the PET base film; Attaching a second adhesive film layer on a side of the metal shielding layer away from the PET base film; A double-sided adhesive tape is attached to the side of the second adhesive film layer away from the metal shielding layer to obtain a PTC heating film.

[0012] Furthermore, the silver paste layer is printed on the PET base film by screen printing, and the silver paste layer is dried and cured after printing. Then the carbon paste layer is printed on the side of the carbon paste layer away from the PET base film by screen printing, and the carbon paste layer is dried and cured after printing before proceeding to the next process.

[0013] Furthermore, the method for preparing the PTC heating film also includes: Die-cutting the PTC heating film into a product shape through a die cutter; Cold-press riveting the wire harness terminal to the silver paste layer electrode of the die-cut PTC heating film; Use glue to encapsulate the exposed electrode area; After measuring the resistance of the packaged PTC heating film with a multimeter, thermal imaging is used to perform infrared detection when it is powered on.

[0014] The beneficial effects achieved by the present invention using the above structure are as follows: The present invention uses the PTC heating film of the PET substrate as the heating element, so that the final product has the PTC self-limiting temperature characteristic, and meets the surface temperature requirements of T5 or T6 without a temperature control device. The temperature control device is eliminated, the cost and complexity of the product are reduced, and the reliability of the product is improved. The protective plates are attached to the upper and lower surfaces of the PET insulating material to improve the heat resistance level of the material at high temperatures. The product will not have insulation failure during the high temperature impact test. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is an appearance diagram of an embodiment of the present invention; Figure 2 An exploded view of an embodiment of the present invention; In the figure: 1-PTC heating film; 2-protective plate; 3-power connector; 21-connection hole; 22-rivet.

[0016] The accompanying drawings are used to provide further understanding of the embodiments of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0018] In the description of the embodiments of the present invention, it should be understood that terms such as "up", "down", "front", "back", "left", "right", "top", "bottom", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0019] Non-metallic infrared radiation heaters that meet GB / T4654 have the advantages of low cost and good designability. Some products also have certain PTC characteristics. The maximum surface temperature of the product can be controlled between T5 and T6 without the need for a thermostat, which has higher safety. However, such non-metallic infrared radiation heaters generally cannot meet the relevant explosion-proof requirements of GB3836.1. The main reason is that the protection level of such products is weak and cannot meet the requirements of 7.4 "electrostatic charge of external non-metallic materials" and 26.4.2 "impact test" in the shell protection of GB3836.1 standard.

[0020] This type of heating film product with PTC characteristics usually uses thinner PET film as insulation and protection material, and cannot pass the relevant requirements for explosion-proof product housings.

[0021] The mechanical strength of PET material will decrease significantly at T5 and T6 temperatures, and the insulation resistance of PET material reaches 10E14Ω·m, which cannot eliminate static charges. Therefore, this type of heating film cannot be used in the explosion-proof field at present.

[0022] The present invention uses the PTC heating film of the PET substrate as the heating element, so that the final product has the PTC self-limiting temperature characteristic and meets the surface temperature requirements of T5 or T6 without a temperature control device.

[0023] Protective plates are pasted on the upper and lower surfaces of the PET insulating material to improve the material's heat resistance level and shell strength at high temperatures, while the product still maintains the advantages of simple structure and fast heat transfer speed.

[0024] The stainless steel plates on the upper and lower surfaces are grounded internally to meet the grounding requirements of explosion-proof electrical equipment.

[0025] like Figure 1 and Figure 2 As shown, the present invention provides a metal shell explosion-proof heating plate with PTC characteristics, including a PTC heating film, a protective plate, and a power connector. The power connector is electrically connected to the PTC heating film, and the protective plates are respectively arranged on the upper and lower surfaces of the PTC heating film, and the protective plates are grounded.

[0026] In a further implementation of this embodiment, the material of the protection plate is a rigid conductive metal plate.

[0027] In a further implementation of this embodiment, the material of the protective plate is one of stainless steel plate, aluminum plate, and galvanized iron plate.

[0028] In a further implementation of this embodiment, the thickness of the heating plate is 2-6 mm.

[0029] In a further implementation of this embodiment, the thickness of the protective plate is 0.05-0.2 mm.

[0030] In a further implementation of this embodiment, a plurality of connection holes are evenly arranged along the edge line of the protective plate, and the connection holes on the protective plates on the upper and lower surfaces of the PTC heating film are arranged correspondingly.

[0031] In a further implementation of this embodiment, the corresponding connection holes on the two protective plates are connected by rivets.

[0032] In a further implementation of this embodiment, the preparation method of the PTC heating film is: Printing a silver paste layer on one side of the PET base film to obtain a silver paste printed coil; Printing a carbon paste layer on the side of the silver paste printed coil away from the PET base film to obtain a silver and carbon paste printed coil; Thermally laminating a first adhesive film layer on the side of the silver-printed and carbon-paste coil away from the PET base film to obtain a PTC base film; Attaching a metal shielding layer on the side of the PTC base film away from the PET base film; Attaching a second adhesive film layer on a side of the metal shielding layer away from the PET base film; A double-sided adhesive tape is attached to the side of the second adhesive film layer away from the metal shielding layer to obtain a PTC heating film.

[0033] In a further implementation of this embodiment, the silver paste layer is printed on the PET base film by screen printing, and the silver paste layer is dried and cured after printing. Then the carbon paste layer is printed on the side of the carbon paste layer away from the PET base film by screen printing, and the carbon paste layer is dried and cured after printing before proceeding to the next process.

[0034] In a further implementation of this embodiment, the method for preparing the PTC heating film further includes: Die-cutting the PTC heating film into a product shape through a die cutter; Cold-press riveting the wire harness terminal to the silver paste layer electrode of the die-cut PTC heating film; Use glue to encapsulate the exposed electrode area; After measuring the resistance of the packaged PTC heating film with a multimeter, thermal imaging is used to perform infrared detection when it is powered on.

[0035] It should be noted that the present invention uses the PTC heating film of the PET substrate as the heating element, so that the final product has the PTC self-limiting temperature characteristic, and meets the surface temperature requirements of T5 or T6 without a temperature control device. The temperature control device is eliminated, the cost and complexity of the product are reduced, and the reliability of the product is improved.

[0036] Attach protective plates (the protective plates can be made of stainless steel, aluminum, galvanized iron, etc.) to the upper and lower surfaces of the PET insulation material to improve the heat resistance of the material at high temperatures. This ensures that the product will not experience insulation failure during high temperature impact testing.

[0037] Experimental test 1 The thickness of the metal protective plate involved is 0, 0.05, 0.1, and 0.2, and the material of the protective plate is stainless steel or color steel. According to Appendix C of GB 3836.1-2021, the drop height is 700mm. Qualification judgment basis: insulation resistance before and after the test ≥ 2000MΩ. The experimental results are shown in Table 1 below: Table 1

[0038] It can be seen from Table 1 that the 3, 4, and 7 structure specimens have sufficient protection levels and can meet the requirements for explosion-proof mechanical protection performance.

[0039] Experimental test 2 Samples with structure 3-1 were selected. According to Table 17 of GB 3836.1-2021, the samples were aged for 336 hours at 90°C and 95% hr humidity, and then dried at 100°C for 336 hours. According to Appendix C of GB 3836.1-2021, the impact characteristics were tested at a drop height of 700mm. The qualification was determined based on the following criteria: insulation resistance ≥ 2000MΩ before and after the test, and the maximum surface temperature of the test sample did not exceed 100°C. The experimental results are shown in Table 2 below: Table 2

[0040] After the wet heat accelerated aging test, it has sufficient protection level and can meet the requirements of explosion-proof mechanical protection performance.

[0041] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0042] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that many changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the invention.

[0043] The present invention and its embodiments are described above, and such description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the creative purpose of the embodiments of the present invention, they can design a structure and embodiment similar to the technical solution without creativity, which should belong to the protection scope of the present invention.

Claims

1. A metal shell explosion-proof heating plate with PTC characteristics, characterized in that: It includes a PTC heating film, a protective plate, and a power connector. The power connector is electrically connected to the PTC heating film. The protective plates are respectively arranged on the upper and lower surfaces of the PTC heating film. The protective plates are grounded and are made of a rigid conductive metal plate.

2. The metal shell explosion-proof heating plate with PTC characteristics according to claim 1, characterized in that: The material of the protective plate is one of stainless steel plate, aluminum plate and galvanized iron plate.

3. The metal shell explosion-proof heating plate with PTC characteristics according to claim 2 is characterized in that: The thickness of the heating plate is 2-6 mm.

4. The metal shell explosion-proof heating plate with PTC characteristics according to claim 3 is characterized in that: The thickness of the protective plate is 0.05-0.2 mm.

5. The metal shell explosion-proof heating plate with PTC characteristics according to claim 1, characterized in that: The protective plate is evenly provided with a plurality of connection holes along the edge line, and the connection holes on the protective plates on the upper and lower surfaces of the PTC heating film are respectively arranged correspondingly.

6. The metal shell explosion-proof heating plate with PTC characteristics according to claim 5, characterized in that: The corresponding connection holes on the two protective plates are connected by rivets.

7. The metal shell explosion-proof heating plate with PTC characteristics according to claim 6, characterized in that: The preparation method of the PTC heating film is as follows: Printing a silver paste layer on one side of the PET base film to obtain a silver paste printed coil; Printing a carbon paste layer on the side of the silver paste printed coil away from the PET base film to obtain a silver and carbon paste printed coil; Thermally laminating a first adhesive film layer on the side of the silver-printed and carbon-paste coil away from the PET base film to obtain a PTC base film; Attaching a metal shielding layer on the side of the PTC base film away from the PET base film; Attaching a second adhesive film layer on a side of the metal shielding layer away from the PET base film; A double-sided adhesive tape is attached to the side of the second adhesive film layer away from the metal shielding layer to obtain a PTC heating film.

8. The metal shell explosion-proof heating plate with PTC characteristics according to claim 7, characterized in that: The silver paste layer is printed on the PET base film by screen printing, and the silver paste layer is dried and solidified after printing. Then the carbon paste layer is printed on the side of the carbon paste layer away from the PET base film by screen printing, and the carbon paste layer is dried and solidified after printing before proceeding to the next process.

9. The metal shell explosion-proof heating plate with PTC characteristics according to claim 7, characterized in that: The method for preparing the PTC heating film further comprises: Die-cutting the PTC heating film into a product shape through a die cutter; Cold-press riveting the wire harness terminal to the silver paste layer electrode of the die-cut PTC heating film; Use glue to encapsulate the exposed electrode area; After measuring the resistance of the packaged PTC heating film with a multimeter, thermal imaging is used to perform infrared detection when it is powered on.

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