Electric heating device and manufacturing method thereof

Abstract

The invention relates to a method for producing an electric heating device, comprising two conductor elements assigned with different polarities and at least one heating element in direct contact with the conductor elements. The method can be realized in a cost-saving manner, and the heating performance of the electric heating device is improved. The invention relates to a method in which a heating element is attached to a surface of at least one of two conductor elements and is connected to the conductor element, and the surface is provided with an electrically insulating coating such that both the surface and at least some of the conductor elements are provided with an electrically insulating coating. The invention relates to a method in which an electrically insulating coating is provided on a heating element, the electrically insulating coating being removed on a contact surface of the heating element in order to bring the heating element into contact with two conductor elements, at least one conductor element being provided with an electrically insulating coating while masking a contact surface formed on the surface of the conductor element, the heating element is attached to the contact surface and is connected to the conductor element.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an electric heating device, the electric heating device comprising two conductor elements and at least one heating element in direct contact with the conductor elements, and such heating device. Background Technology

[0002] A corresponding electric heating device is known prior art, for example, by EP1515587A1. In the method disclosed herein, one of the conductor elements, arranged in the form of a contact plate, is provided with an electrically insulating varnish layer. This varnish layer is applied to the entire surface of the contact plate, which is arranged to abut against a heating element in the form of a PTC element.

[0003] The paint is applied to the entire surface. Then, the PTC element is placed onto the electrically insulating surface. Here, the still-liquid paint is pushed to make electrical contact between the PTC element and the contact plate. The pushed paint forms a ring around and encapsulates the outer periphery of the PTC element. Furthermore, the cured paint achieves adhesive bonding, so the PTC element connected to the contact plate can be operated as a unit during further processing of the electric heating device.

[0004] In further processing, the PTC element contacts a contact plate on each of its opposite sides. On the side opposite the PTC element, the heat sink element is attached to the corresponding contact plate. This heating rod consists of an electric heating device and heat sink elements attached to it on both sides, and these components are mounted in a frame. Multiple layers of heat sink elements and electric heating devices can be accommodated in a single frame. Following the teachings of EP1515587A1, this layered structure is held in the frame by the tight action of springs. After the layered structure is installed in the frame, the individual layers of the layered structure are held together and connected to each other by external spring force. For the integrity of the layered structure, the retaining force of the paint layer is no longer required.

[0005] The foregoing details of an electric heating device that typically includes a layered structure within a frame can also be considered details of the present invention. Summary of the Invention

[0006] The purpose of this invention is to provide a method for manufacturing an electric heating device that can be implemented cost-effectively and yields an electric heating device with better heating performance.

[0007] To address this problem, the present invention proposes a method in which a heating element is mounted on the surface of at least one of two conductor elements and connected to the respective conductor element. An insulating coating is then applied to the surface, such that the surface of the conductor element and at least a portion of the heating element are coated with the insulating coating.

[0008] Therefore, unlike previously known methods, the heating element is first connected to at least one conductor element, preferably two conductor elements. This connection may be only temporary, but it must ensure that the various components of the electric heating device are interconnected until they are installed in the electric heating device, for example, as part of a layered structure held within the device. The connection can be made using an adhesive, for example, a volatile adhesive, which is not necessarily, but may be, conductive. After the connection, an insulating coating is applied. This coating can at least substantially completely, or at least substantially entirely, encapsulate the heating element and at least one conductor element, preferably two conductor elements. Thus, an electric heating device according to the method is provided in which the current-carrying components are completely or almost completely encapsulated by an electrically insulating coating. Preferably, the current-carrying components are completely encapsulated by the electrically insulating coating at locations where the electric heating device is exposed to the medium to be heated, such as within the frame or housing surrounding the heating chamber.

[0009] Therefore, the method according to the invention is particularly suitable for producing electric heating devices that operate at high voltages. In any case, the insulating coating ensures that the air gap and creepage distance do not exhibit significant problems when the electric heating device is operated at any operating voltage.

[0010] According to an alternative, the heating element is provided with an electrically insulating coating, preferably completely covered by the electrically insulating coating. This electrically insulating coating is removed from the contact surface of the heating element that contacts the conductor element. The contact surfaces are generally opposite each other. The conductor element is also provided with an electrically insulating coating. Here, the contact surface on the surface of the conductor element designated for electrical contact with the heating element is provided with a mask. This mask covers the corresponding contact surface such that when the surface is subsequently coated with the electrically insulating coating, the surface in the area of ​​the mask remains uncoated. After the conductor element is coated, the mask is removed, thereby exposing the contact surface for contacting the heating element, which is completely covered by the electrically insulating coating. The heating element abuts against the contact surface with its corresponding contact surface, thereby making conductive contact with the conductor element. Of course, the heating element is preferably connected to the conductor element, particularly by adhesive bonding.

[0011] Preferably, the two conductor elements are provided with an electrically insulating coating while concealing the contact surfaces formed on the surfaces of the conductor elements. The heating element is attached to the contact surfaces of the two conductor elements and connected to the conductor rail. The resulting electric heating device includes two conductor elements of different polarities and at least one heating element in conductive contact with the two conductor elements, wherein the directly energized surfaces and components of the electric heating device are preferably integrally provided with an electrically insulating portion on the outer side.

[0012] The shielding portion can be sized relative to the contact surface of the heating element such that the electrically insulating portion extends a short distance below the heating element. In this case, the contact surface is correspondingly smaller than the corresponding contact surface of the heating element. Thus, even with certain tolerance deviations when the heating element is positioned on the conductor element, the conductive surface of the conductor element is prevented from being directly exposed next to the heating element on the electric heating device.

[0013] In this variation of the solution according to the invention, both conductor elements can also be prepared in the same manner, such that a contact surface corresponding to the heating element is formed on each individual conductor element due to the presence of a shielding portion. The heating element contacts the contact surface by abutting against the conductor element.

[0014] In particular, the contact surfaces of PTC elements, which constitute the heating element, are typically metallized. This metallization is usually applied at the supplier's location using physical vapor deposition (PVD) or screen printing. The metallization is directly connected to the ceramic surface of the PTC element. The PTC element itself is typically made of semiconductor ceramic.

[0015] In an alternative implementation, where the heating element has an electrically insulating coating, which is subsequently at least partially removed, the PTC element can be coated prior to the application of the metallization. The electrically insulating coating is then removed from the contact surfaces, which are typically opposite each other. The metallization is then preferably applied only to the contact surfaces. Alternatively, the metallization can be applied first to the ceramic surface, and then the PTC element can be completely encased in the electrically insulating coating. The electrically insulating coating on the contact surfaces can then be removed, exposing the metallization.

[0016] Electrical insulation can be removed by chemical or mechanical means, such as by grinding.

[0017] To form an electrically insulating layer, a polymer can be applied to the heating element. Particularly preferred is the application of a xylene-based polymer, particularly parylene, which has the advantage that this electrically insulating coating can be applied at room temperature by vapor deposition. The coating method for applying the electrically insulating coating can be performed immediately following the metallization process and on the same production section.

[0018] The connection between the heating element and the conductor element, or between two conductors, is preferably achieved by means of an adhesive. This adhesive may act only temporarily and may, for example, be formed by a separate adhesive that does not constitute an electrically insulating layer as in EP1515587A1. Instead, the adhesive is applied to the mating and / or contact surfaces before the two mating parts to be bonded are brought against each other, typically pressed together. Here, the heating element is electrically connected to at least one corresponding conductor rail. The adhesive may also be designed in the form of an adhesive that evaporates during operation of the heating device or a retaining varnish. The heating element may also be soldered to the corresponding conductor rail. The use of a non-conductive adhesive is also conceivable, preferably with the contact and / or mating surfaces profiled simultaneously, such that the roughness or protrusions penetrate the adhesive layer that provides electrical insulation if necessary. For this purpose, the conductor element may be made of a modified metal plate forming protrusions. The profile configuration can also be achieved by metallizing the conductor element designed as a PTC element. Various measures are taken to ensure that the heating element establishes and maintains a good conductive connection with the corresponding conductor element, preferably with two corresponding conductor elements assigned different polarities, at least during the manufacture of the electric heating device using this electric heating device.

[0019] As is well known, multiple heating elements are typically arranged spaced apart from each other in an electric heating device. Therefore, it is preferable to arrange the heating elements spaced apart from each other on at least one conductor element using positioning aids. This arrangement is achieved by positioning each individual heating element on a corresponding contact surface based on the positioning aids. This results in a generally elongated electric heating device having two elongated conductor elements, particularly in the form of contact plates, wherein multiple heating elements are spaced apart from each other and arranged sequentially along the longitudinal direction of the conductor elements.

[0020] The contact surface of the heating element is the surface of the heating element that makes electrical contact with it. Whether the heating element was previously wrapped with an electrically insulating portion or the coating was applied after the heating element and conductor element were connected, in any case, the positioning aid ensures the correct positioning of the conductor element. This preferred method of implementation eliminates the need for a positioning frame, which in the prior art is typically made of plastic and is thinner than the PTC element, with a receiving portion within the positioning frame designed to accommodate at least one PTC element. Therefore, in the prior art, relative positioning is achieved by means of a positioning frame, which is also part of the electric heating device, whereas in the preferred embodiment discussed herein, positioning is temporarily achieved by a comb-shaped positioning aid. The comb-shaped positioning aid positions one of the heating elements with adjacent protrusions and holds it between the two conductor elements until the respective heating element is connected to its respective conductor element. The positioning aid is then removed from the gap between the two conductor elements.

[0021] The heating elements are spaced apart to prevent them from significantly affecting each other thermally. PTC elements have self-regulating characteristics; therefore, heating an adjacent PTC element can cause a temperature increase, leading to increased resistance. Positioning aids prevent this improper positioning between adjacent heating elements. Furthermore, the positioning aids can be designed so that only the contact surface left by the shielding section is precisely positioned with the corresponding heating element. Attached Figure Description

[0022] Other details and advantages of the present invention can be derived from the description of the embodiments in conjunction with the accompanying drawings. Wherein:

[0023] Figure 1 An exploded perspective view showing an embodiment of the electric heating device.

[0024] Figure 2 The following is shown after applying an electrically insulating coating: Figure 2 Examples of implementations.

[0025] Figures 3a to 3d The method steps for an alternative embodiment of the electric heating device are shown.

[0026] Figure 4 A side view of the electric heating device is shown when multiple electric heating devices are used. Detailed Implementation

[0027] Figure 1 An exploded view illustrates an embodiment of the electric heating device 2, which has an upper conductor element 4 in the form of a contact plate 6 and another conductor element 8 in the form of a contact plate 10. The two contact plates 6 and 10 form abutment surfaces 14 on their opposing inner surfaces 12. Figure 1 The text is displayed in dashed lines.

[0028] According to Figure 1 In the exploded view, the electric heating element 16, in the form of a PTC element 18, is shown between the upper conductor element 4 and the lower conductor element 8, and corresponds to their respective contact surfaces 14.

[0029] Figure 2 Show Figure 1 The connected embodiment is shown below. Therefore, [the following will be done]. Figure 1 The conductive adhesive designated as 20 is applied to the respective contact surfaces 14 of the two conductor elements 4 and 8. Contact plates 6 and 10 are then attached to the PTC element 18, such that the PTC element 18, with its contact surface designated as 22, is attached to and bonded to the corresponding contact surface 14. This forms a structural unit consisting of the two conductor elements 4 and 8 and the heating elements 16 and 18.

[0030] Then, in Figure 2 The structural unit shown is provided with an electrically insulating coating 24 by vapor deposition of parylene 23. This coating 24 surrounds the contact plates 6, 10 on its outer periphery and completely covers the PTC element 18. Only at one end of the elongated electric heating device 2 can the electrical coating 24 be omitted, for example, by masking the end before coating, so that the contact plates 6, 10 form an electrical connection piece, the electrical connection piece being... Figure 4 The figure is indicated by reference numeral 26.

[0031] Figure 4 Also shown is an element 28 in the form of a corrugated rib layer 30, which is alternately stacked with the electric heating device 2 to form a layered structure 32. This layered structure 32 is insulatedly housed and supported in a frame-like housing 34 made of insulating material, preferably plastic. Reference numeral 36 indicates a spring element, which is externally supported relative to the longitudinal beam 38 of the housing 34 and tensions the inner layers of the layered structure 32 such that the individual layers of the layered structure are pressed against each other under the spring preload. These layers include the corrugated rib layer 30, contact plates 6, 10, and the PTC element 18. The housing 34... Figure 4 The crossbeam, indicated by reference numeral 40 in the attached drawing, protrudes from the contact plates 6 and 10. These contact plates are assigned different polarities, and the corresponding connecting pieces 26 integrally formed with the contact plates 6 and 10 are marked with positive or negative polarity.

[0032] Due to the integrally formed insulating coating 24, the corrugated fin layer 30 is disposed in the housing 34 without potential. The frame-like housing 34 forms an inlet and outlet for the medium to be heated (which may be air in this example).

[0033] The connecting piece 26 at the end of the housing 34 is not electrically insulated and does not come into direct contact with the medium flowing through the frame-like housing 34 and to be heated.

[0034] Therefore, in Figure 4 The figure shows an electric heating device with improved electrical safety, indicated by reference numeral 42.

[0035] Figures 3a to 3d This demonstrates an alternative approach. According to Figure 3a Heating elements 16 and 18 are firstly covered with an electrically insulating coating 44. This electrically insulating coating 44 completely encloses the heating element 16. Figures 3a to 3d In the figure, the heating element is indicated by reference numeral 46 as a coated heating element.

[0036] Figure 3bThe drawing shows a coated conductor element, indicated by reference numeral 48, including one of conductor elements 4 and 8 having an electrically insulating coating 24. Reference numeral 50 indicates a masking portion that is attached to and covers the contact surface 14 before coating the conductor elements 4 and 8, so that in subsequent coating processes, only the outer surface of the masking portion 50 is coated, and the area of ​​the surface 12 of the conductor elements 4 and 8 that forms the contact surface 14 is not coated. The masking portion 50 is then removed.

[0037] In the illustrated embodiment, a masking portion is appropriately provided. However, masking can also be achieved by exposing the contact surface 14 during the coating process of conductor elements 4, 8. The masking portion can also be effectively achieved using a masking agent (e.g., varnish, wax, etc.), which can be removed, for example, by washing, after the coating process.

[0038] Figure 3c The process of placing multiple heating elements 46 onto the lower conductor element 4 is illustrated. For this purpose, the conductor element 8 is held by a positioning aid 52, which is comb-shaped and has receiving grooves 54 open on one side between protrusions 56, each groove accommodating one heating element 46. The relative movement of the positioning aid 52 and the conductor element 4 along or laterally to the conductor element 8 (direction arrow L) allows the corresponding heating element 46 to be precisely positioned on its corresponding contact surface 14. Typically, another upper conductor element 4, 6 is then abutted against the corresponding heating element 46 with its associated contact surface 14, while the heating element 46 is held in place by the positioning aid 52.

[0039] Prior to this step, the electrically insulating coating 44 on the opposing main sides of the heating element 16 has been removed. Here, the metallized portion already formed on the PTC element 18 can be exposed. Alternatively, after removing the electrically insulating coating 44, a metallized portion can be formed on the opposing main side surfaces of the PTC element 18. In either case, the PTC element 18 directly abuts its respective contact surface 22 against the contact surface 14 of the conductor elements 4 and 8, thereby achieving electrical contact. The electrically insulating coating 24 integrally formed on the conductor elements 4 and 8 and the electrically insulating coating 44 on the heating element 16 cover the energized components of the electric heating device 2.

[0040] As shown in the figure, direct electrical contact is achieved between the heating element 16 and the associated conductor elements 4 and 8, thereby ensuring good heating performance of the heating element 16. Especially when these elements are designed as PTC elements 12, heat is directly output from the PTC element through the contact surface 14 to the corresponding conductor element 4, and from there at least... Figure 4In the illustrated embodiment, heat is dissipated into the heat sink element 28. PTC elements 18 are individually disposed between the two conductor elements 4 and 8. This eliminates components that could cause heat buildup, such as positioning frames, but it also heats the surrounding environment of the respective PTC element 18, reducing the efficiency of the PTC element 18.

[0041] Electrically insulating coatings 24, 24, and 44 protect the current-carrying components of the electric heating device 22 from environmental influences. Since conductive components are not exposed outside the housing 34, corrosion is reduced and electrical safety is improved. The components within the housing 34 of the electric heating device 42 through which the heated medium flows are used solely for heat generation and conduction. The pressure loss of the medium flowing through the heating device 42 within the housing 34 is significantly reduced; therefore, any fan used to force convection of the heated medium can be designed to be low-power.

[0042] Similar to the aforementioned prior art, this invention is specifically designed to describe an electric heating device 2 or electric heating equipment 42 for motor vehicles. This simple, cost-effective, and relatively lightweight design brings additional advantages that are particularly valued in the automotive industry.

[0043] List of reference numerals

[0044] 2 Electric heating device

[0045] 4 conductor elements

[0046] 6 contact plates

[0047] 8 conductor elements

[0048] 10 contact plates

[0049] 12 surfaces

[0050] 14 backrests

[0051] 16 heating elements

[0052] 18PTC components

[0053] 20 adhesives

[0054] 22 contact surfaces

[0055] 24 Electrical insulation coating

[0056] 26 connecting pieces

[0057] 28 heat sink components

[0058] 30 corrugated rib layers

[0059] 32-layer structure

[0060] 34 housing

[0061] 36 Spring Components

[0062] 38 longitudinal beams

[0063] 40 crossbeam

[0064] 42 Electric heating equipment

[0065] 44 Electrical Insulation Coating

[0066] 46 Coated heating elements

[0067] 48 Coated conductor elements

[0068] 50 shelters

[0069] 52 Positioning Auxiliary Components

[0070] 54 Reservoir

[0071] 56 protrusions

Claims

1. A method for manufacturing an electric heating device (2), said electric heating device comprising two conductor elements (4; 8) assigned different polarities and at least one heating element (16), particularly a PTC element (18), in direct contact with the conductor elements (4; 8), wherein, The heating element (16) is mounted on and connected to the surface (12) of at least one of the two conductor elements (4; 8), and the surface (12) is provided with an electrically insulating coating (24) such that the surface (12) and at least a portion of the conductor elements (4; 8) are provided with the electrically insulating coating (24).

2. The method according to claim 1, characterized in that, The heating element (16) is connected to the opposite surface of the conductor element, and the electrical insulating coating (44) is applied in such a way that the surface of the conductor element and the heating element (16) are provided with an insulating coating.

3. A method for manufacturing an electric heating device (2), said electric heating device comprising two conductor elements (4; 8) assigned different polarities and at least one heating element (16), particularly a PTC element (18), in direct contact with the conductor elements (4; 8), wherein, The heating element (16) is provided with an electrically insulating coating (44), which is removed on the contact surface (22) of the heating element (16) to make the heating element (16) contact with two conductor elements (4; 8), at least one of the conductor elements (4; 8) having an electrically insulating coating (44) on a mating surface (14) constructed on the surface (8) of the conductor element (4; 8), and the heating element (16) abuts against the mating surface (14) and is connected to the conductor element (4; 8).

4. The method according to claim 3, characterized in that, The conductor element (4; 8) is provided with an electrically insulating coating (44) while masking the contact surface (14) on the surface (12) of the conductor element (4; 8), and the heating element (16) is attached to the contact surface (14) and connected to the conductor rail (4; 8).

5. The method according to any one of the preceding claims, characterized in that, The heating element (16) is connected to the conductor element (4; 8) by means of an adhesive (20).

6. The method according to claim 5, characterized in that, The heating element (16) is connected to the conductor element (4; 8) by a conductive adhesive (20).

7. The method according to any one of the preceding claims, characterized in that, The conductor elements (4; 8) are integrally provided with an electrically insulating coating (24).

8. The method according to any one of the preceding claims, characterized in that, Multiple heating elements (16) are arranged at intervals on at least one conductor element (4; 8) by means of positioning aids (52), such that each individual heating element (16) is positioned on the contact surface (14) of the conductor element (4; 8) corresponding to its respective heating element (16) based on the positioning aids (52).

9. An electric heating device (2) comprising two conductor elements (4; 8) assigned different polarities and at least one heating element (16), particularly a PTC element (18), in contact with the conductor elements (4; 8), wherein, The heating element (16) is directly electrically connected to the contact surface (14), which is formed by the surface (12) of at least one of the two conductor elements (4; 8), wherein the conductor element (4; 8) is provided with an electrically insulating coating (24).

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