Integrally-formed insulating PTC heater and preparation process thereof

Abstract

The integrally-formed insulating PTC heater comprises PTC chip sets, electrode plate sets and insulating heat conduction materials, the multiple PTC chip sets are fixedly arranged between the electrode plate sets, each electrode plate set is composed of two first electrode plates, electrode interfaces are formed in the ends of the first electrode plates, the electrode interfaces of the first electrode plates are arranged in a staggered mode, and the insulating heat conduction materials are arranged in the electrode interfaces of the first electrode plates. The electrode plate is coated with an insulating heat-conducting material, and the insulating heat-conducting material is provided with an electrode port corresponding to the electrode interface; according to the integrally-formed insulating PTC heater, the structure of the heater is redesigned, a traditional polyimide film is omitted, the insulating heat conduction material is arranged so that the heating PTC heating piece can make direct contact with the insulating heat conduction material, traditional aluminum pipe heat conduction is replaced, heat effect conduction is greatly improved, safety is greatly improved, and the service life of the heater is prolonged. And the cost of a large amount of aluminum materials is saved, the weight of the PTC heater is reduced, the economic benefit is high, and the application field is wide.

Description

Technical Field

[0001] The invention belongs to the technical field of PTC heaters, and in particular relates to an integrally formed insulating PTC heater and a preparation process thereof. Background Art

[0002] The PTC heater uses PTC ceramic as the core heating element. Compared with traditional electric heating wires, electric heating tubes, and far-infrared quartz heaters, it can automatically control temperature, has a wide voltage range, and has no open flames. It is safe, reliable, and has a long service life. The PTC heater generally uses polyimide film as an insulating material to wrap the PTC ceramic sheet and electrode plate, and then places the wrapped PTC ceramic sheet and electrode plate in an aluminum tube and presses the aluminum tube so that the PTC ceramic sheet and electrode plate fit tightly with the aluminum tube. Finally, the aluminum tube and the aluminum strip for heat dissipation are bonded with thermal conductive silicone. The electrode plate is used to energize the PTC ceramic sheet. The current passes through the PTC ceramic sheet to generate heat, and the heat is transferred to the aluminum tube through the polyimide film, and then the aluminum tube transfers the heat to the aluminum strip. The function of the polyimide film is to isolate the electrode plate from the aluminum tube for heat conduction to prevent the aluminum tube from conducting electricity. However, due to the relatively large thermal resistance of polyimide, the heat loss from the PTC ceramic sheet to the aluminum tube is large, which affects the performance of the PTC heater.

[0003] Patent CN105554924A discloses a PTC heater with an insulating coating and a preparation method thereof. The electrode plate and the PTC heating sheet are bonded with silicone. The insulating coating is applied on the inner surface of the heat dissipation aluminum strip to insulate the electrode plate from the heat dissipation aluminum strip, thereby eliminating the need for polyimide film and aluminum tube. However, the purpose of eliminating the polyimide film and aluminum tube in this patent is to save costs, provided that the heating effect of the PTC heater is not affected. The insulating coating used in this patent is also a polyimide resin coating, which still has a large thermal resistance and does not improve the heating effect of the PTC heater.

[0004] Patent CN111901910A discloses a PTC heater, which attaches a PTC heating material to an insulating substrate, and uses the substrate to replace the aluminum tube for heating, solving the problem that the PTC heating material and the aluminum tube are connected by thermally conductive silicone, which is easy to age and affects the thermal conductivity of the PTC heater. However, its substrate is porous ceramic, which is brittle and needs to be sintered to attach the PTC heating material. The bonding force between the PTC heating material and the substrate is not strong, which greatly limits the application field of the PTC heater. Summary of the invention

[0005] The first object of the present invention is to solve the problem of how to cover the electrode plate with insulating material by integral molding to replace the polyimide film and improve the thermal effect of the PTC heater.

[0006] The second object of the present invention is to solve the problem of how to improve the bonding strength between the insulating material and the PTC chip and the electrode plate, so as to improve the overall mechanical strength and thermal conductivity of the PTC heater.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] An integrally formed insulating PTC heater comprises a PTC chip group, an electrode plate group and an insulating heat-conducting material.

[0009] A plurality of PTC chip groups are fixedly arranged between the electrode plate groups. The PTC chip group is composed of a plurality of PTC chips arranged in an array. The electrode plate group is composed of two first electrode plates. Electrode interfaces are arranged at the ends of the first electrode plates. The electrode interfaces of the first electrode plates are staggered. The area of ​​the electrode plates is larger than that of the PTC chip group. The electrode plates are coated with insulating thermally conductive material. Electrode openings are arranged at positions of the insulating thermally conductive material corresponding to the electrode interfaces.

[0010] The electrode plate group is made of stainless steel, and the electrode plate group and the PTC chip group are fixed by silicone dispensing.

[0011] A silicone ring is arranged in the area between the two first electrode plates which is not in contact with the PTC chip, and the insulating heat-conducting material is coated with a silicone heat-conducting film.

[0012] A preparation process of an integrally formed insulating PTC heater comprises the following steps:

[0013] Step 1: Arrange the PTC chips to form a PTC chipset, fix the two sides of the PTC chipset in the electrode plate group using a dispensing process, fill the PTC chipset with silicone until it is flush with the edge of the electrode plate group, and then cure the silicone to form a silicone ring to obtain the PTC heater to be coated.

[0014] Step 2: Use a grinder to grind the surface of the cured silicone to be coated on the PTC heater to make it smooth so that the silicone ring is flush with the edge of the electrode plate group. Wash it twice with water to remove surface stains, electrolyze it with sodium phosphate solution to remove surface oil, then soak it in 5-10wt% sulfuric acid solution, wash it with deionized water and dry it.

[0015] Step 3: The dried PTC heater to be coated is plated with an insulating thermal conductive material with a coating thickness of 0.1-0.2 mm to obtain an integrally formed insulating PTC heater.

[0016] Furthermore, the specific methods of coating with insulating thermal conductive material in step 3 include the following two methods:

[0017] Method 1: The dried PTC heater to be coated is electrophoretically plated with electrophoretic paint in an electrophoretic pool. The electrophoretic paint is a water-soluble resin paint. After washing with UF1 and UF2 respectively, it is washed twice with deionized water and then cured in an oven at a curing temperature of 170-175°C.

[0018] Method 2: Use a 3-5mm caliber spray gun to spray TSC-L ultra-high temperature insulating varnish on the surface of the dried PTC heater to be coated at a pressure of 0.6-0.8Mpa. The thickness of a single spray is less than 0.1mm. After a single spray, wait for 2-3 hours for the TSC-L ultra-high temperature insulating varnish on the surface of the PTC heater to be coated to dry, then spray again, and repeat 3-6 times.

[0019] Furthermore, the electrode plate group consists of a first electrode plate and a second electrode plate, and electrode interfaces are arranged at the ends of the first electrode plate and the second electrode plate, and the electrode interfaces of the first electrode plate and the second electrode plate are arranged in a staggered manner.

[0020] Two first openings are arranged on the first electrode plate and the second electrode plate between each two adjacent PTC chip groups. The two first openings are arranged on both sides of the first electrode plate and the second electrode plate respectively. Two second openings are arranged equidistantly between the two first openings on the second electrode plate.

[0021] The insulating heat-conductive material enters the gap between adjacent PTC chip groups through the first opening and the second opening, and forms a reinforcing strip in the gap after solidification.

[0022] A preparation process of an integrally formed insulating PTC heater comprises the following steps:

[0023] Step 1: Arrange the PTC chips to form a PTC chipset, fix both sides of the PTC chipset on the electrode plate using a dispensing process, fill the PTC chipset with silicone until it is flush with the edge of the electrode plate, and then cure the silicone to form a silicone ring to obtain the PTC heater to be coated.

[0024] Step 2: Use a grinder to grind the surface of the cured silicone to be coated on the PTC heater to make it smooth so that the silicone ring is flush with the edge of the electrode plate. Wash it twice with water to remove surface stains, electrolyze it with sodium phosphate solution to remove surface oil, then soak it in 5-10wt% sulfuric acid solution, wash it with deionized water and dry it.

[0025] Step 3: Place the dried PTC heater to be coated in a mold, with the distance between the four inner walls of the mold and the PTC heater to be coated being 2 mm, and the distance between the top and bottom side walls of the mold and the PTC heater to be coated being 0.4-0.5 mm. Insulating thermally conductive material is injected into the mold and then cured to obtain an integrally formed insulating PTC heater.

[0026] Furthermore, in step three, the mold includes an upper mold and a lower mold;

[0027] The upper mold and the lower mold are both provided with a cavity in the center, a closing block is provided at the front end of the cavity of the upper mold, a closing groove is provided at one end of the cavity of the lower mold, two injection channels are provided through the closing block, and the injection channels are located between the first openings of the electrode plate group;

[0028] A boss and a groove are respectively arranged on both sides of the block, and a boss and a groove are respectively arranged on both sides of the groove. The bosses and grooves on both sides of the groove are arranged in opposite directions to the bosses and grooves on both sides of the block. The electrode interface of the first electrode plate is arranged on the boss on one side of the block, and the electrode interface of the second electrode plate is arranged in the groove on the other side of the block.

[0029] An exhaust channel is arranged around the cavities of the upper mold and the lower mold, and the exhaust channel is led to the outside of the mold along one side of the boss and the groove;

[0030] Wedge blocks are arranged at the four corners of the lower mold, and wedge grooves are arranged at the positions of the upper mold corresponding to the wedge blocks of the lower mold.

[0031] Furthermore, a guide block is centrally arranged at the other end of the cavity of the lower mold, and a limiting groove with the same width as the first opening is arranged on the guide block corresponding to the first opening position of the first electrode plate. The length of the guide block is the same as the width of the electrode plate group, and the guide block is fixedly connected to the lower mold.

[0032] Furthermore, a support frame is slidably arranged on the guide block, and the support frame is an inverted "U" shape. A limit block is arranged at a position on the support frame corresponding to the limit groove. The shape of the support frame after being engaged with the guide block is a rectangle, and the height of the rectangle is the same as the height after the two cavities are combined. The guide block is slidably arranged in the cavity.

[0033] Furthermore, there are three specific ways to inject the insulating thermal conductive material into the mold and then solidify it:

[0034] Method 1: Inject molten rubber material into the cavity through the injection channel. After the rubber material fills the mold, vulcanize at 165-175℃ for 10-12min, and the vulcanization pressure is 12-14Mpa;

[0035] Method 2: injecting polyphenylene sulfide thermoplastic resin heated to melt and plasticize into the cavity through the injection channel at a pressure of 2-2.5 MPa, performing pressure-maintaining treatment on the mold in sections and then releasing the pressure to obtain an integrally formed insulating PTC heater;

[0036] Method three: inject thermal conductive silicone into the cavity through the injection channel, wait for the silicone to dry and solidify at room temperature, and obtain an integrally formed insulated PTC heater.

[0037] Beneficial effects of the present invention:

[0038] (1) The one-piece insulated PTC heater prepared by the present invention redesigns the structure of the heater, eliminates the traditional polyimide film, and sets an insulating thermal conductive material so that the heat-generating PTC heating plate is in direct contact with the insulating thermal conductive material, replacing the traditional aluminum tube heat conduction, greatly improving the conduction of the thermal effect. The insulating thermal conductive material also solves the problem of possible electrical conductivity between the traditional aluminum tube and the electrode plate, greatly improving the safety, saving a lot of aluminum material costs, reducing the weight of the PTC heater, and having high economic benefits and a wide range of applications.

[0039] (2) The one-piece insulating PTC heater prepared by the present invention has two structures according to the process settings of different insulating thermally conductive materials, is suitable for the coating process of various insulating thermally conductive materials, and has good bonding strength with the insulating thermally conductive materials. Different insulating thermally conductive materials can be replaced according to the actual use scenario of the PTC heater. The thickness of the insulating thermally conductive material is thinner than that of the traditional aluminum shell, and the insulating thermally conductive material prepared in the mold of the present invention has uniform thickness and better thermal conductivity. The obtained PTC heating chip is smaller in size. The richer selection of insulating thermally conductive materials and the smaller size make the present invention have broad application prospects.

[0040] (3) The preparation process of the present invention can be used to coat the insulating thermal conductive material and form an integral body after assembling the PTC chip group and the electrode plate. There is no need to wrap the polyimide film on the outside of the electrode plate and then assemble it into an aluminum shell. This greatly shortens the preparation process and installation process, reduces the short circuit of the electrode plate caused by damage to the polyimide film due to installation, greatly improves the safety and economy of the preparation process, and has a very high economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be further described below in conjunction with the accompanying drawings.

[0042] Figure 1 is an exploded view of one of the structures of the present invention;

[0043] Figure 2 It is a schematic diagram of the appearance of the present invention;

[0044] Figure 3 It is a schematic diagram of the internal structure of the second structure of the present invention;

[0045] Figure 4 It is the upper half of the cross-sectional view of the insulating material in the second structure of the present invention;

[0046] Figure 5 It is the lower half of the cross-sectional view of the insulating material in the second structure of the present invention;

[0047] Figure 6 It is a schematic diagram of the internal structure of the mold of the present invention;

[0048] Figure 7It is a schematic diagram of the internal structure of the lower mold in the mold of the present invention;

[0049] Figure 8 It is a schematic diagram of the support frame structure in the mold of the present invention;

[0050] In the figure: 1. PTC chipset; 2. electrode plate group; 21. electrode interface; 22. first electrode plate; 23. second electrode plate; 24. first opening; 25. second opening; 3. silicone ring; 4. insulating thermal conductive material; 41. electrode port; 42. reinforcing strip; 5. upper mold; 51. wedge block; 52. closing block; 53. injection channel; 6. lower mold; 61. wedge groove; 62. guide block; 621. limit groove; 63. support frame; 631. limit block; 64. closing groove; 7. boss; 8. groove; 9. cavity; 10. exhaust channel. DETAILED DESCRIPTION

[0051] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] Example 1: Please refer to Figure 1-2 As shown, an integrally formed insulating PTC heater comprises a PTC chip group 1, an electrode plate group 2 and an insulating thermal conductive material 4;

[0053] A plurality of PTC chip groups 1 are fixedly arranged between the electrode plate groups 2. The PTC chip groups 1 are composed of a plurality of PTC chips arranged in an array. In this embodiment, there are three PTC chip groups 1, and each PTC chip group 1 is composed of six PTC chips.

[0054] The electrode plate group 2 is made of stainless steel, and the electrode plate group 2 and the PTC chip group 1 are fixed by silicone glue dispensing.

[0055] The electrode plate group 2 is composed of two first electrode plates 22 . The ends of the first electrode plates 22 are provided with electrode interfaces 21 . The electrode interfaces 21 of the two first electrode plates 22 are staggered.

[0056] The area of ​​the first electrode plate 22 is larger than that of the PTC chip group 1, so that the upper and lower surfaces of each PTC chip are in contact with the electrode plate, and a silicone ring 3 is set in the area between the two first electrode plates 22 that is not in contact with the PTC chip, so that the electrode plate, the PTC chip group 1 and the silicone ring 3 form a cube with flat sides.

[0057] The electrode plate group 2 is coated with an insulating thermally conductive material 4, and an electrode port 41 is arranged at a position corresponding to the electrode interface 21, so that the electrode interface 21 is exposed to the outside and connected to a power source. The insulating thermally conductive material 4 is electrophoretic paint, and is coated with a silicone thermally conductive film.

[0058] The gap between the electrode plate group 2 and the PTC chip is filled with a silicone ring 3, so that the PTC chip group 1 and the electrode plate group 2 form a cube with flat sides, which is convenient for forming a coating of insulating thermal conductive material 4 with uniform thickness on the surface of the PTC heater during the electrophoresis process and the spraying process, which not only enhances the heat transfer effect of the PTC chip, but also improves the bonding force between the coating of insulating thermal conductive material 4 and the electrode plate group 2.

[0059] A preparation process of an integrally formed insulating PTC heater comprises the following steps:

[0060] Step 1: Arrange the PTC chips to form a PTC chipset 1, fix both sides of the PTC chipset 1 in the electrode plate group 2 using a dispensing process, fill the PTC chipset 1 with silicone until it is flush with the edge of the electrode plate group 2, and then cure the silicone to form a silicone ring 3 to obtain the PTC heater to be coated.

[0061] Step 2: Use a grinder to grind the surface of the cured silicone to be coated on the PTC heater to make it smooth so that the silicone ring 3 is flush with the edge of the electrode plate group 2. Wash it twice with water to remove surface stains, electrolyze it with a sodium phosphate solution to remove surface oil, and then soak it in a 5-10wt% sulfuric acid solution, wash it with deionized water and dry it to increase the roughness of the surface of the electrode plate group 2 and enhance the bonding strength between the electrode plate group 2 and the insulating thermal conductive material 4.

[0062] Step 3: Clamp the two electrode interfaces 21 of the dried PTC heater to be coated with a clamp, and electrophoretically plate the electrophoretic paint in an electrophoretic pool. The electrophoretic paint is a water-soluble resin paint. After washing with UF1 and UF2 respectively, it is washed twice with deionized water and then cured in an oven. The coating thickness is 0.1-0.2mm and the curing temperature is 170-175°C. Then, a silicone thermal conductive film is coated on all sides to obtain an integrally formed insulated PTC heater.

[0063] Embodiment 2: The difference from Embodiment 1 is that the insulating thermally conductive material 4 is TSC-L ultra-high temperature insulating varnish.

[0064] A preparation process of an integrally formed insulating PTC heater comprises the following steps:

[0065] Step 1: Arrange the PTC chips to form a PTC chipset 1, fix both sides of the PTC chipset 1 in the electrode plate group 2 using a dispensing process, fill the PTC chipset 1 with silicone until it is flush with the edge of the electrode plate group 2, and then cure the silicone to form a silicone ring 3 to obtain the PTC heater to be coated.

[0066] Step 2: Use a grinder to grind the surface of the cured silicone to be coated on the PTC heater to make it smooth so that the silicone ring 3 is flush with the edge of the electrode plate group 2. Wash it twice with water to remove surface stains, electrolyze it with a sodium phosphate solution to remove surface oil, and then soak it in a 5-10wt% sulfuric acid solution, wash it with deionized water and dry it to increase the roughness of the surface of the electrode plate group 2 and enhance the bonding strength between the electrode plate group 2 and the insulating thermal conductive material 4.

[0067] Step 3: Use a 3-5mm caliber spray gun to spray TSC-L ultra-high temperature insulating varnish on the surface of the dried PTC heater to be coated at a pressure of 0.6-0.8Mpa. The thickness of a single spray is less than 0.1mm. After a single spray, place it for 2-3 hours to wait for the TSC-L ultra-high temperature insulating varnish on the surface of the PTC heater to be coated to dry, spray it again, repeat 3-6 times, and the total spraying thickness is 0.1-0.2mm. After drying, cover it with a silicone thermal conductive film on all sides to obtain an integrated insulating PTC heater.

[0068] Example 3: Please refer to Figure 3-Figure 5 As shown, an integrally formed insulating PTC heater comprises a PTC chip group 1, an electrode plate group 2 and an insulating thermal conductive material 4;

[0069] A plurality of PTC chip groups 1 are fixedly arranged between the electrode plate groups 2. The PTC chip groups 1 are composed of a plurality of PTC chips arranged in an array. In this embodiment, there are three PTC chip groups 1, and each PTC chip group 1 is composed of six PTC chips.

[0070] The electrode plate group 2 is made of stainless steel, and the electrode plate group 2 and the PTC chip group 1 are fixed by silicone glue dispensing.

[0071] The electrode plate group 2 is composed of a first electrode plate 22 and a second electrode plate 23 . The ends of the first electrode plate 22 and the second electrode plate 23 are both provided with electrode interfaces 21 . The electrode interfaces 21 of the first electrode plate 22 and the second electrode plate 23 are staggered.

[0072] The area of ​​the electrode plate group 2 is larger than the area of ​​the PTC chip group 1 , so that the upper surface and the lower surface of each PTC chip are in contact with the electrode plate group 2 .

[0073] Two first openings 24 are provided on the first electrode plate 22 and the second electrode plate 23 between each two adjacent PTC chip groups 1. The two first openings 24 are respectively provided on both sides of the first electrode plate 22 and the second electrode plate 23. Two second openings 25 are equidistantly provided between the two first openings 24 on the second electrode plate 23.

[0074] The electrode plate group 2 is coated with an insulating thermally conductive material 4, and an electrode opening 41 is set at the position of the insulating thermally conductive material 4 corresponding to the electrode interface 21, so that the electrode interface 21 is exposed to the outside and connected to the power supply. The insulating thermally conductive material 4 is a rubber material, and the molten rubber material enters the gap between the adjacent PTC chip groups 1 through the first opening 24 and the second opening 25, forming a reinforcing strip 42 in the gap to improve the bonding force between the rubber and the electrode plate group 2.

[0075] The structure in the present embodiment is suitable for using a mold to fix the insulating thermally conductive material 4 and then solidify it. However, since the insulating thermally conductive material 4 of the PTC heater of the present invention is relatively thin, that is, the distance between the electrode plate 2 and the inner side of the mold is relatively small, the first opening 24 and the second opening 25 are provided so that the insulating thermally conductive material 4 can be injected from the first opening 24 and fill the mold through the first opening 24 and the second opening 25 on the other side, which is beneficial to the coating of the insulating thermally conductive material 4. At the same time, the reinforcing strip 42 formed in the gap also strengthens the bonding force between the insulating thermally conductive material 4 and the electrode plate 2.

[0076] A preparation process of an integrally formed insulating PTC heater comprises the following steps:

[0077] Step 1: Arrange the PTC chips to form a PTC chipset 1, fix both sides of the PTC chipset 1 in the electrode plate group 2 using a dispensing process, fill the PTC chipset 1 with silicone until it is flush with the edge of the electrode plate group 2, and then cure the silicone to form a silicone ring 3 to obtain the PTC heater to be coated.

[0078] Step 2: Use a grinder to grind the surface of the cured silicone to be coated on the PTC heater to make it smooth so that the silicone ring 3 is flush with the edge of the electrode plate group 2. Wash it twice with water to remove surface stains, electrolyze it with a sodium phosphate solution to remove surface oil, and then soak it in a 5-10wt% sulfuric acid solution, wash it with deionized water and dry it to increase the roughness of the surface of the electrode plate group 2 and enhance the bonding strength between the electrode plate group 2 and the insulating thermal conductive material 4.

[0079] Step three, place the dried PTC heater to be coated in the mold, the distance between the four inner walls of the mold and the PTC heater to be coated is 2 mm, the distance between the top side wall and the bottom side wall of the mold and the PTC heater to be coated is 0.4-0.5 mm, and the molten rubber material is injected into the cavity 9 through the injection channel 53. After the rubber material fills the mold, it is vulcanized at 165-175°C for 10-12 minutes, the vulcanization pressure is 12-14Mpa, and the thickness of the vulcanized rubber is 0.4-0.5mm to obtain an integrally molded insulating PTC heater.

[0080] The melting and vulcanization process of the rubber material in this embodiment adopts conventional processes well known to those skilled in the art.

[0081] See also Figure 6-8 As shown, a mold for an integrally formed insulating PTC heater includes an upper mold 5 and a lower mold 6 .

[0082] The upper mold 5 and the lower mold 6 are both provided with a cavity 9 in the center. A block 52 is provided at the front end of the cavity 9 of the upper mold 5. A groove 64 is provided at one end of the cavity 9 of the lower mold 6 for engaging with the block 52 of the upper mold 5. Two injection channels 53 are provided through the block 52. The injection channels 53 are located between the first openings 24 of the electrode plate group 2. Bosses 7 and grooves 8 are provided on both sides of the block 52. Bosses 7 and grooves 8 are provided on both sides of the groove 64. The bosses 7 and the grooves 8 are arranged in the opposite direction to the bosses 7 and the grooves 8 on both sides of the block 52. The electrode interface 21 of the first electrode plate 22 is arranged on the boss 7 on one side of the block 52, and the electrode interface 21 of the second electrode plate 23 is arranged in the groove 8 on the other side of the block 52. The block 52 and the groove 64 are engaged with each other, and the bosses 7 and the grooves 8 on both sides of the groove 64 are respectively engaged with the grooves 8 and the bosses 7 on both sides of the block 52, so that the electrode interface 21 arranged in an offset manner is clamped by the bosses 7 and the grooves 8.

[0083] A guide block 62 is centrally arranged at the other end of the cavity 9 of the lower mold 6, and a limiting groove 621 with the same width as the first opening 24 is arranged on the guide block 62 corresponding to the first opening 24 of the first electrode plate 22. The length of the guide block 62 is the same as the width of the electrode plate group 2, and the guide block 62 is fixedly connected to the lower mold 6.

[0084] A support frame 63 is slidably arranged on the guide block 62, and the support frame 63 is an inverted "U" shape. A limit block 631 is arranged on the support frame 63 at a position corresponding to the limit groove 621. The shape of the support frame 63 after being engaged with the guide block 62 is a rectangle, and the height of the rectangle is the same as the height of the two cavities 9 after being combined. The guide block 62 is slidably arranged in the cavity 9.

[0085] Wedge blocks 51 are arranged at the four corners of the lower mold 6 , and wedge grooves 61 are arranged on the upper mold 5 at positions corresponding to the wedge blocks 51 of the lower mold 6 , so as to calibrate the engagement between the upper mold 5 and the lower mold 6 .

[0086] An exhaust channel 10 is arranged around the mold cavity 9 of the upper mold 5 and the lower mold 6 , and the exhaust channel 10 is connected to the outside of the mold along one side of the boss 7 and the groove 8 .

[0087] Steps to use the mold:

[0088] The dried PTC heater to be coated is placed in the cavity 9 of the lower mold 6 coated with a release agent, with the electrode plate of the PTC heater to be coated containing the second opening 25 facing downward, and the two electrode interfaces 21 are respectively placed in the boss 7 and the groove 8 of the lower mold 6, and the limit block 631 of the support frame 63 is opened downward and engaged with the first opening 24 at the tail end of the PTC heater to be coated, and the limit block 631 of the support frame 63 is also engaged with the limit groove 621 on the guide block 62, and then the wedge block 51 of the upper mold 5 is aligned with the wedge groove 61 of the lower mold 6, the upper mold 5 and the lower mold 6 are locked, and the insulating thermal conductive material 4 is injected into the cavity 9 through the injection channel 53.

[0089] The invention principle of the mold:

[0090] The injection channel 53 provided on the assembly block 52 allows the insulating thermally conductive material 4 to be injected from the gap of the PTC chip group 1, filling the cavity 9 from the inside out, so that the insulating thermally conductive material 4 is filled more evenly. Since the second electrode plate 23 is provided with a second opening 25, the insulating thermally conductive material 4 will first fill the cavity 9 of the lower mold 6. At this time, the insulating thermally conductive material 4 will provide support and upward pressure to the second electrode plate 23. By providing a support frame 63, that is, by engaging the first opening 24 of the first electrode plate 22 with the limit block 631, the electrode plate group 2 is located in the center of the cavity 9 in the left and right directions, which plays a role of limiting. Moreover, the top end of the support frame 63 contacts the bottom of the cavity 9 of the upper mold 5, so that the first electrode plate 22 is supported. The support frame 63 is restricted. At this time, the second electrode plate 23 is also supported by the insulating thermally conductive material 4 in the cavity 9 of the lower mold 6, so that the electrode plate group 2 is located in the center of the cavity 9 in the up and down directions. When the cavity 9 of the upper mold 5 is also filled with the insulating thermally conductive material 4, the pressure from the injection channel 53 is transmitted to the support frame 63 through the insulating thermally conductive material 4, so that the support frame 63 slides from the first electrode plate 22 to the guide block 62. At this time, the rectangle formed by the guide block 62 and the support frame 63 is the bottom of the cavity 9 of the mold of the present invention, and does not affect the coating of the insulating thermally conductive material 4, so that the heater coated with the insulating thermally conductive material 4 is smooth and has a uniform thickness, thereby improving the heating efficiency of the insulated PTC heater obtained by the present invention.

[0091] Embodiment 4: The difference from Embodiment 3 is that the insulating thermally conductive material 4 is polyphenylene sulfide thermoplastic resin (PPS).

[0092] A preparation process of an integrally formed insulating PTC heater comprises the following steps:

[0093] Step 1: Arrange the PTC chips to form a PTC chipset 1, fix both sides of the PTC chipset 1 in the electrode plate group 2 using a dispensing process, fill the PTC chipset 1 with silicone until it is flush with the edge of the electrode plate group 2, and then cure the silicone to form a silicone ring 3 to obtain the PTC heater to be coated.

[0094] Step 2: Use a grinder to grind the surface of the cured silicone to be coated on the PTC heater to make it smooth so that the silicone ring 3 is flush with the edge of the electrode plate group 2. Wash it twice with water to remove surface stains, electrolyze it with a sodium phosphate solution to remove surface oil, and then soak it in a 5-10wt% sulfuric acid solution, wash it with deionized water and dry it to increase the roughness of the surface of the electrode plate group 2 and enhance the bonding strength between the electrode plate group 2 and the insulating thermal conductive material 4.

[0095] Step three, place the dried PTC heater to be coated in the mold, the distance between the four inner walls of the mold and the PTC heater to be coated is 2 mm, the distance between the top side wall and the bottom side wall of the mold and the PTC heater to be coated is 0.4-0.5 mm, and the polyphenylene sulfide thermoplastic resin heated to melt and plasticize is injected into the cavity 9 through the injection channel 53 at a pressure of 2-2.5 MPa. After the mold is subjected to segmented pressure maintenance treatment, the pressure is released to obtain an integrally molded insulating PTC heater.

[0096] The melt plasticization and pressure-maintaining and pressure-releasing processes of the polyphenylene sulfide thermoplastic resin in this embodiment adopt conventional processes well known to those skilled in the art.

[0097] Embodiment 5: The difference from Embodiment 3 is that the insulating heat-conducting material 4 is heat-conducting silicone.

[0098] A preparation process of an integrally formed insulating PTC heater comprises the following steps:

[0099] Step 1: Arrange the PTC chips to form a PTC chipset 1, fix both sides of the PTC chipset 1 in the electrode plate group 2 using a dispensing process, fill the PTC chipset 1 with silicone until it is flush with the edge of the electrode plate group 2, and then cure the silicone to form a silicone ring 3 to obtain the PTC heater to be coated.

[0100] Step 2: Use a grinder to grind the surface of the cured silicone to be coated on the PTC heater to make it smooth so that the silicone ring 3 is flush with the edge of the electrode plate group 2. Wash it twice with water to remove surface stains, electrolyze it with a sodium phosphate solution to remove surface oil, and then soak it in a 5-10wt% sulfuric acid solution, wash it with deionized water and dry it to increase the roughness of the surface of the electrode plate group 2 and enhance the bonding strength between the electrode plate group 2 and the insulating thermal conductive material 4.

[0101] Step three: place the dried PTC heater to be coated in a mold, with the distance between the four inner walls of the mold and the PTC heater to be coated being 2 mm, and the distance between the top side wall and the bottom side wall of the mold and the PTC heater to be coated being 0.4-0.5 mm. Inject thermal conductive silicone into the cavity 9 through the injection channel 53, and wait for the silicone to dry and solidify at room temperature to obtain an integrally formed insulating PTC heater.

[0102] The silica gel injection and drying and curing process in this embodiment adopts conventional processes well known to those skilled in the art.

[0103] 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.

[0104] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An integrally formed insulated PTC heater, characterized in that: include: PTC chip group (1), electrode plate group (2) and insulating thermal conductive material (4); A plurality of PTC chip groups (1) are fixedly arranged between the electrode plate groups (2), the PTC chip group (1) is composed of a plurality of PTC chips arranged in an array, the electrode plate group (2) is composed of two first electrode plates (22), the ends of the first electrode plates (22) are provided with electrode interfaces (21), the electrode interfaces (21) of the first electrode plates (22) are arranged in a staggered manner, the area of ​​the electrode plates (2) is larger than the area of ​​the PTC chip group (1), the electrode plates (2) are coated with an insulating heat-conducting material (4), and the insulating heat-conducting material (4) is provided with an electrode opening (41) at a position corresponding to the electrode interface (21); The electrode plate group (2) is made of stainless steel, and the electrode plate group (2) and the PTC chip group (1) are fixed by silicone glue dispensing.

2. The one-piece insulated PTC heater according to claim 1, characterized in that: A silicone ring (3) is provided in an area between the two first electrode plates (22) that is not in contact with the PTC chip, and the insulating heat-conducting material (4) is coated with a silicone heat-conducting film.

3. The process for preparing an integrally formed insulating PTC heater according to claim 2, characterized in that: The steps include: Step 1: Arrange the PTC chips to form a PTC chipset (1), fix the two sides of the PTC chipset (1) in the electrode plate group (2) by using a dispensing process, fill the periphery of the PTC chipset (1) with silica gel until it is flush with the edge of the electrode plate group (2), and then cure the silica gel to form a silica gel ring (3), thereby obtaining a PTC heater to be coated; Step 2: Use a grinder to grind the surface of the cured silicone to be coated on the PTC heater to make it smooth, so that the silicone ring (3) is flush with the edge of the electrode plate group (2), wash it twice with water to remove surface stains, electrolyze it with a sodium phosphate solution to remove surface oil, then rinse it with a 5-10wt% sulfuric acid solution, wash it with deionized water and dry it; Step 3: The dried PTC heater to be coated is plated with an insulating thermal conductive material (4) with a coating thickness of 0.1-0.2 mm to obtain an integrally formed insulating PTC heater.

4. The process for preparing an integrally formed insulating PTC heater according to claim 3, characterized in that: The specific methods of coating with insulating thermal conductive material (4) in step 3 include the following two methods: Method 1: The dried PTC heater to be coated is electrophoretically plated with electrophoretic paint in an electrophoretic pool. The electrophoretic paint is a water-soluble resin paint. After washing with UF1 and UF2, it is washed twice with deionized water and then cured in an oven at a curing temperature of 170-175°C. Method 2: Use a 3-5mm caliber spray gun to spray TSC-L ultra-high temperature insulating varnish on the surface of the dried PTC heater to be coated at a pressure of 0.6-0.8Mpa. The thickness of a single spray is less than 0.1mm. After a single spray, wait for 2-3 hours for the TSC-L ultra-high temperature insulating varnish on the surface of the PTC heater to be coated to dry, then spray again, and repeat 3-6 times.

5. The one-piece insulated PTC heater according to claim 1, characterized in that: The electrode plate group (2) is composed of a first electrode plate (22) and a second electrode plate (23); the ends of the first electrode plate (22) and the second electrode plate (23) are both provided with electrode interfaces (21); and the electrode interfaces (21) of the first electrode plate (22) and the second electrode plate (23) are staggered; Two first openings (24) are provided on the first electrode plate (22) and the second electrode plate (23) between each two adjacent PTC chip groups (1); the two first openings (24) are respectively provided on both sides of the first electrode plate (22) and the second electrode plate (23); and two second openings (25) are equidistantly provided between the two first openings (24) on the second electrode plate (23); The insulating heat-conductive material (4) enters the gap between adjacent PTC chip groups (1) through the first opening (24) and the second opening (25), and forms a reinforcing strip (42) in the gap after solidification.

6. The process for preparing an integrally formed insulating PTC heater according to claim 5, characterized in that: The steps include: Step 1: Arrange the PTC chips to form a PTC chipset (1), fix the two sides of the PTC chipset (1) on the electrode plate (2) by using a dispensing process, fill the periphery of the PTC chipset (1) with silicone until it is flush with the edge of the electrode plate (2), and then cure the silicone to form a silicone ring (3), thereby obtaining a PTC heater to be coated; Step 2: Use a grinder to grind the surface of the cured silicone to be coated on the PTC heater to make it smooth, so that the silicone ring (3) is flush with the edge of the electrode plate (2), wash it twice with water to remove surface stains, electrolyze it with a sodium phosphate solution to remove surface oil, then rinse it with a 5-10wt% sulfuric acid solution, wash it with deionized water and dry it; Step 3: Place the dried PTC heater to be coated in a mold, wherein the distance between the four inner side walls of the mold and the PTC heater to be coated is 2 mm, and the distance between the top side wall and the bottom side wall of the mold and the PTC heater to be coated is 0.4-0.5 mm. Insulating thermally conductive material (4) is injected into the mold and then cured to obtain an integrally formed insulating PTC heater.

7. The process for preparing an integrally formed insulating PTC heater according to claim 6, characterized in that: The mold in step 3 comprises an upper mold (5) and a lower mold (6); A cavity (9) is provided in the center of both the upper mold (5) and the lower mold (6); a closing block (52) is provided at the front end of the cavity (9) of the upper mold (5); a closing groove (64) is provided at one end of the cavity (9) of the lower mold (6); two injection channels (53) are provided through the closing block (52); and the injection channels (53) are located between the first openings (24) of the electrode plate group (2); A boss (7) and a groove (8) are respectively arranged on both sides of the assembly block (52), and a boss (7) and a groove (8) are respectively arranged on both sides of the assembly groove (64); the bosses (7) and the grooves (8) on both sides of the assembly groove (64) are arranged in opposite directions to the bosses (7) and the grooves (8) on both sides of the assembly block (52); an electrode interface (21) of a first electrode plate (22) is arranged on the boss (7) on one side of the assembly block (52), and an electrode interface (21) of a second electrode plate (23) is arranged in the groove (8) on the other side of the assembly block (52); An exhaust channel (10) is arranged around the mold cavity (9) of the upper mold (5) and the lower mold (6), and the exhaust channel (10) is connected to the outside of the mold along one side of the boss (7) and the groove (8); Wedge blocks (51) are arranged at the four corners of the lower mold (6), and wedge grooves (61) are arranged on the upper mold (5) at positions corresponding to the wedge blocks (51) of the lower mold (6).

8. The process for preparing an integrally formed insulating PTC heater according to claim 7, characterized in that: A guide block (62) is centrally arranged at the other end of the cavity (9) of the lower mold (6); a limiting groove (621) having the same width as the first opening (24) is arranged on the guide block (62) at a position corresponding to the first opening (24) of the first electrode plate (22); the length of the guide block (62) is the same as the width of the electrode plate group (2); and the guide block (62) is fixedly connected to the lower mold (6).

9. The process for preparing an integrally formed insulating PTC heater according to claim 8, characterized in that: A support frame (63) is slidably arranged on the guide block (62); the support frame (63) is in an inverted "U" shape; a limit block (631) is arranged on the support frame (63) at a position corresponding to the limit groove (621); the shape of the support frame (63) and the guide block (62) after being engaged is a rectangle; the height of the rectangle is the same as the height of the two cavities (9) after being combined; and the guide block (62) is slidably arranged in the cavity (9).

10. The process for preparing an integrally formed insulating PTC heater according to claim 9, characterized in that: The specific methods of injecting the insulating heat-conducting material (4) into the mold and then curing it include the following three methods: Method 1: injecting molten rubber material into the mold cavity (9) through the injection channel (53), and after the rubber material fills the mold, vulcanizing at 165-175° C. for 10-12 minutes, with a vulcanization pressure of 12-14 MPa; Method 2: injecting polyphenylene sulfide thermoplastic resin heated to melt and plasticize into the cavity (9) through the injection channel (53) at a pressure of 2-2.5 MPa, subjecting the mold to pressure-maintaining treatment in sections and then releasing the pressure to obtain an integrally formed insulating PTC heater; Method three: injecting thermally conductive silica gel into the cavity (9) through the injection channel (53), and waiting for the silica gel to dry and solidify at room temperature to obtain an integrally formed insulating PTC heater.

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