Electric heating device and method of manufacturing the same

Abstract

This invention relates to an electric heating device, particularly an electric heating device for motor vehicles, comprising: a housing that is at least partially conductive and a cover made of a metal plate, wherein a circumferential groove is provided on the front side of the housing, the cover closing the housing and engaging the circumferential edge in the groove, the groove containing a sealant. To improve the sealing of the housing while reliably shielding the electrical components housed therein, the circumferential edge has a first leg engaging in the groove and a second leg bent away from the first leg, the second leg extending from the circumferential edge and making conductive contact with one of the boundary walls of the groove. In a method for manufacturing the electric heating device, the circumferential edge is first introduced into the groove, followed by the introduction of a sealant to seal the groove, the sealant hardening within the groove.

Description

Technical Field

[0001] This invention relates to an electric heating device and a method for manufacturing the same. Electric heating devices known from DE202020000689U1 are considered general-purpose. This prior art discloses an electric heating device having a housing that is at least partially conductive and a cover made of a metal plate that closes the housing and covers the housing opening.

[0002] This invention particularly relates to an electric heating device, wherein the housing has a heating chamber with inlet and outlet openings for the fluid to be heated, and a heating device connected thermally to the heating chamber, which may be designed as a thick-film heating device or a PTC heating device, and may be electrically connected in a connecting chamber. A partition wall typically separates the heating chamber from the connecting chamber in a fluid-tight manner. Background Technology

[0003] In the electric heating device according to the invention, multiple PTC heating devices can be housed within a housing. Therefore, the multiple PTC heating devices are typically electrically connected in a connection chamber, or they can be grouped into heating circuits. For this purpose, a printed circuit board can be provided in the connection chamber, which assigns different PTC heating devices to different heating circuits. A printed circuit board with mounted components can also be provided in the connection chamber; this printed circuit board is the central component of a control device used to control the heating devices in order to appropriately adjust the power of the electric heating devices.

[0004] Heating devices are typically located on one side of the partition wall, while control devices are typically located on the other side.

[0005] These details were also obtained from DE202020000689U1.

[0006] The above-mentioned features may also be preferred features of the electric heating device according to the present invention.

[0007] For the corresponding electric heating devices, there is the problem of electromagnetic interference from affecting other nearby components, especially when switching PTC heating devices. For example, in vehicles, these components may include electronic components or parts of the in-vehicle entertainment system. Therefore, it is known that the housing is designed to be at least partially conductive for shielding purposes. Electrical contact is achieved not only for EMC reasons but also specifically for high-voltage safety (grounding connection). Otherwise, a potential might be adjacent to the cover, and this would not be detectable by insulation monitoring. In particular, the connection chamber and the control devices housed therein are housed in a metal housing. The components surrounding or defining the housing of the heating chamber may be made of non-conductive materials. Plastic is preferred for weight reduction.

[0008] The requirements for electric heating devices in motor vehicles impose various additional requirements. For example, electric heating devices cannot simply be designed to be as lightweight as possible. Rather, the electrical components of the electric heating device must be reliably protected from environmental influences. This is particularly true for electric heating devices used in motorized applications. These devices typically operate under high voltage. For example, moisture and / or contaminants seeping into the connection chamber can impair the desired electrical insulation of the various components. Contaminated or damp surfaces can promote leakage current formation. Summary of the Invention

[0009] The purpose of this invention is to solve the following problems by providing an electric heating device and a method for manufacturing the same, which can reliably shield the electrical components housed therein while achieving the best possible seal of the housing.

[0010] To address this problem, the present invention proposes an electric heating device of the type described above, wherein the housing has a circumferential groove on one end face. A circumferential groove is understood in this sense as a groove formed circumferentially along the circumferential direction of the groove. It is not important that the groove has the same depth throughout the entire circumference. A sealant is applied to the groove to seal it around its entire circumference. The cap has a circumferential edge that engages with the groove, such that the edge of the cap is immersed in the sealant around its entire circumference. This results in a completely fluid-impermeable seal of the cap in the area of ​​the groove. Adhesives, especially hardened adhesives that remain elastic even upon curing, are particularly suitable as sealants. For example, silicone adhesives can be used.

[0011] Due to its adhesive properties, the adhesive can help the cover stay on the housing. However, the adhesive can also be used simply as a sealing compound, preventing contamination and / or moisture from entering the recessed area by drawing the surrounding edges into the adhesive and thus bonding them together.

[0012] The cover is preferably a sheet metal cover. This means that the cover material has a wall thickness predetermined by the raw material of the sheet metal. Preferably, the cover is provided by stamping and bending or other forming processes, such that the surrounding edge and / or additional contact tabs on the edge protrude at substantially right angles from the cover surface formed by the cover from the originally substantially flat cover surface of the cover.

[0013] The adhesive is preferably applied to the recess in volumetric doses. It is typically applied after the cap has been attached to the housing by pressing it into place. This also protects the contact points used to electrically connect the cap to the housing from external influences. The adhesive is preferably applied separately to the gap between the inner surface defining the recess and the surrounding edge of the cap. This allows the amount of adhesive to be kept to a minimum.

[0014] Due to the sealing effect of the adhesive, corrosion at the contact points is not a problem, ensuring a strong electrical connection between the cover and the housing even during extended periods of use of the electric heating device. Furthermore, there is an improved connection between the cover and the housing because not only is the cover or contact piece mechanically clamped in the groove, but it is also secured in the groove by the at least partially cured adhesive and its bonding properties.

[0015] The adhesive typically extends beyond the free outer end of the cap's edge along the height direction of the groove. According to the invention, the free outer end of the cap's edge is formed by outwardly curved outer legs projecting outward from the inner legs of the edge. The filling height can therefore be flexibly varied and adjusted according to product requirements.

[0016] The rim of the surround has a first leg that engages in the groove and a second leg that extends from the first leg. The first leg typically extends from the cover surface; the second leg connects to the first leg via a curved area. The first and second legs are typically arranged in a V-shape relative to each other, with the curved area positioned opposite the bottom of the groove and typically forming the deepest engagement within the groove.

[0017] The first leg is usually the inner leg, while the second leg is usually the outer leg. The first leg mates with the inner boundary wall of the groove; the second leg mates with the outer boundary wall of the groove.

[0018] "Outer" and "inner" preferably refer to corresponding regions relative to the interior of the shell. Therefore, the outer legs are typically farther from the interior of the shell than the inner legs at the edges. However, the outer legs and the outer boundary walls they provide can also be formed by recesses and edge regions closer to the interior of the shell. In this variation, the inner legs and the inner boundary walls they provide are farther from the interior of the shell than the outer legs and the outer boundary walls.

[0019] One leg, preferably an outer leg, contacts the associated boundary wall of the groove in an conductive manner. For this purpose, a preload against the outer boundary wall is typically applied to the outer leg. This contact point should be covered with a sealant or adhesive to provide the best possible corrosion protection. Inner legs at the edges are arranged within the groove and are typically supported by the inner boundary wall of the groove.

[0020] The housing forming the groove is preferably a die-cast part. According to the invention, the circumferential edge has two legs, with a curved region formed between them. Under stress-free conditions, the maximum distance between the two legs, preferably the maximum distance between the inner surface of the inner leg and the outermost surface of the outer leg, is greater than the width of the groove. Under stress-free conditions, one leg, preferably the outer leg, typically protrudes diagonally outward and upward from the curved region. Therefore, the circumferential edge preferably has a funnel-shaped geometry with an outwardly widening cross-section. This means that when the circumferential edge is inserted into the groove, the edge is elastically clamped within the groove.

[0021] Typically, the assembly tool is inserted from above into the curved area and the upwardly open circumferential edge, pressing the curved area and therefore the circumferential edge completely into the circumferential groove of the housing. The curved area allows for increased bending, particularly in the outer legs, which typically interact with and interlock with the outer boundary wall of the outer end segment with a sharp edge on the inside. This also prevents the cover from being lost from the housing. An elastic preload between the outer and inner legs reinforces this locking effect through interlocking. This elastic preload is generated and maintained, particularly in the curved area. The curved area can be reinforced by embossing the sheet metal, thereby increasing its strength, which increases the preload force holding the edge in the groove. The embossing is distributed circumferentially, preferably adjacent to and / or within the hook formed by the two legs.

[0022] It is understood that the preload is preferably counteracted by the inner leg and its support against the inner boundary wall of the groove. This typically extends in the height direction of the groove. While the outer boundary wall typically has a flat inner surface in the height direction, on which the outermost end segment slides when the circumferential edge is inserted into the groove, the inner boundary wall may be thinner in its upper region than in its lower region, with a certain sloping surface between the two regions. This design facilitates insertion of the circumferential groove under preload and enhances the interlocking at the end of the component movement by narrowing the groove on the one hand and by forming a thickened inner wall that resists the elastic tension of the circumferential edge in the groove with increased resistance.

[0023] To reduce mechanical stress on the housing, a preferred further improvement of the invention proposes that the circumferential edge be provided only in sections of the outer boundary wall of the groove in the circumferential direction. Therefore, the elastic interlocking occurs only in segments, thereby reducing the mechanical stress on the wall of the housing defining the groove.

[0024] Furthermore, the shell can form a web extending through the groove, the web being segmented and connecting the outer boundary wall of the groove to the inner boundary wall, thereby increasing the strength of the groove. Despite the elastic tension of the circumferential edges within the groove, the web allows for a relatively thin-walled design of the wall bordering the groove, as the web laterally supports and reinforces the groove. The web typically protrudes vertically above the bottom of the groove by at least 40%, preferably at least 50%, of the groove height. The height of the groove is determined by the distance between the bottom of the groove and the boundary wall of the groove with the lowest height. The boundary walls of the groove can have the same height on both the inner and outer sides. However, for improved electrical contact and sealing, and for the compact design of the invention, it is preferable to form the outer boundary wall higher than the inner boundary wall. Preferably, the cover is designed such that it rests on the inner boundary wall.

[0025] This design also provides the possibility of arranging a cover surface formed by the cover and substantially covering the housing, such that the cover surface does not rise above the upper edge of the outer boundary wall. The outer boundary wall can extend beyond the cover surface, and thus allows the electric heating device to be stored on the front edge surface of the outer legs during transport after manufacturing. Therefore, the electric heating device does not need to be supported by the relatively thin-walled cover surface during transport. The cover preferably rests on top of the inner boundary wall.

[0026] At the location where the web intersects the groove, the circumferential edge preferably has an inner leg flange and terminates there. This means that at the location of the web, there is no outer leg interacting with the outer boundary wall, resulting in the mechanical release of the outer boundary wall. The leg flange may terminate at the inner boundary wall at or slightly above the aforementioned inclined surface. The leg flange may be wider than the web covered by the leg flange in the direction of the groove. The leg flange may also extend on two webs spaced apart from each other.

[0027] According to the method of the invention, the circumferential edge is first inserted into the groove, and then a sealant, typically in liquid form and preferably in metered form such as an adhesive, is introduced into the groove to seal the circumferential edge. Metered feeding is typically by volume to ensure that the sealant does not flow beyond the boundaries of the groove; the sealant also prevents undesirable leakage into the interior of the housing, as it rests against the inner boundary wall.

[0028] Preferably, the amount of adhesive is adjusted so that it does not fill the entire groove, but rather fills the smaller volume of the gap formed between the outer wall of the groove and the inner leg. Attached Figure Description

[0029] Further details and advantages of the present invention will become apparent from the following description of embodiments taken in conjunction with the accompanying drawings. Wherein:

[0030] Figure 1 This is an exploded perspective view of an embodiment of the electric heating device;

[0031] Figure 2 This is a longitudinal sectional view of an example heating device using a PTC heating device;

[0032] Figure 3 This is a perspective top view of the cover mounted on the housing;

[0033] Figure 4 yes Figure 3 The example shown is a perspective sectional view of the groove and the edge of the cover; and

[0034] Figure 5 yes Figure 3 and Figure 4 The example shown is an enlarged cross-sectional view of the groove and the edge of the cover. Detailed Implementation

[0035] Figure 1 An example of an electric heating device 2 with a multi-part heater housing is shown, the heater housing including a lower housing part 4 made of plastic and an upper housing part 6 made of metal formed integrally by die casting.

[0036] The lower housing component 4 is recessed and surrounds the heating chamber 8, forming inlet and outlet connections 10 that communicate with the heating chamber 8. These inlet and outlet connections 10 are integrally formed with the lower housing component 4 by injection molding. A plurality of heating devices 12 are shown between the upper housing component 6 and the lower housing component 4.

[0037] like Figure 2 As shown, each of these heating devices 12 has at least one PTC element 14, with contact elements 16.1 and 16.2 adjacent to the PTC element, the contact elements forming contact tongues 18 protruding from the metal housing 20. The PTC element 14 is housed in the frame 22 and between the contact elements 16.1 and 16.2. An insulating layer 26 is provided between the metal housing 20 and the heating unit 24 formed by the two contact elements 16.1 and 16.2, and the PTC element 14.

[0038] The heating device 12 is held in a socket 28 in a partition wall 30 of the upper part 6 of the housing for this purpose by an insertion contact, and is electrically connected in a connection chamber 32 that houses the control device 34 that controls the heating device 12. The main components of the heating device are formed of a printed circuit board 36. Details of this design are described in EP3334242A1 filed by the applicant.

[0039] The upper component 6 of the housing is connected to the cover 38 in a sealing and conductive manner, the cover surface 40 of which covers the connection chamber 32 and is substantially flat. Thus, the upper component 6 of the housing forms, for example, the housing according to claim 1, and is hereinafter simply referred to as housing 6.

[0040] like Figures 3 to 5 As shown, the cover 38 has a circumferential edge 42 that engages in a circumferential groove 44 of the housing 6. The groove 44 is defined on the inner side by an inner boundary wall 46 and on the outer side by an outer boundary wall 48 of the housing 6, and has a bottom 50 disposed therebetween. The bottom of the groove has webs 52 that are segmentally distributed along the circumferential direction of the groove 44. The circumferential edge 42 has an inner leg 54 that extends substantially parallel to the inner boundary wall 46 and an outer leg 56 that points obliquely outward and away from the bottom 50 of the groove by bending the metal sheet forming the cover 38.

[0041] At the position of web 52, the leg flange 58 ends within the circumferential edge 42. (Example) Figure 4 and Figure 5As shown, the inner boundary wall 46 has a slightly stepped profile with a widened lower section 62, an upper section 64 above which the thickness decreases, and an inclined surface 66 between the lower and upper sections. This inclined surface is located in the region of the free end 60 and between the webs 52 associated with the leg flange 58, such that the sealant subsequently introduced into the groove 44 can also reach between the inner leg 54 and the inner boundary wall 46 and act as a seal there.

[0042] The curved region of the circumferential edge 62, marked by reference numeral 68, is spaced apart from the bottom 50 of the groove in the height direction, so that the circumferential edge 42 can move freely and elastically within the curved region 68. Reference numeral 69 indicates an indentation applied from the outside to the curved region 68, which reinforces the inner support leg 54 relative to the outer support leg 56. This provides sufficient clamping force to secure the cover 38 in the groove 44. Figure 4 In the final position shown, the tip of the outermost end segment 70 of the outer leg 56, or the slightly rounded end if applicable, engages with the outer boundary wall 48, thus fixing the final position of the circumferential edge 42, and thus fixing the final position of the cover 38 relative to the housing 6.

[0043] like Figure 4 and Figure 5 As shown, the height of the inner boundary wall 46 is lower than that of the outer boundary wall 58. Figure 4 and Figure 5 The assembled cover 38 shown rests on the free end of the inner boundary wall 64 with the section marked by reference numeral 72. The cover surface 40 is entirely lower than the upper free end of the outer boundary wall 48.

[0044] During assembly, the circumferential edge 42 of the cover 38 is positioned above the recess 44. A tool (not shown) essentially engages the curved region 68 of the circumferential edge 42 and presses the cover 38 into the recess 44. During this process, the curved region 68 bends further, and the outer leg 56, initially sized too large relative to the width of the recess 44, protrudes outward from it, elastically abutting against and sliding downward along the inner boundary wall 46. As the insertion movement proceeds, the inner leg 54 is supported by the inner boundary wall 46, and the outward curvature of the curved region 68 impacts the inclined surface 66, further increasing the elastic tension of the surrounding edge 42. The insertion movement or pressing process is completed when the cover 38 is applied to the inner boundary wall 46 with its resting section 72.

[0045] Subsequently, a sealant, such as an adhesive, is distributed by volume and circumferentially into the circumferential groove 44 between the inner leg 54 and the inner boundary wall 46. The adhesive in... Figure 4 The part is indicated by reference numeral 74 in the accompanying drawings. The fill height of the adhesive 74 is above the inclined surface 66. In the embodiment shown here, the adhesive 74 extends substantially into the support section 72 within the groove 44.

[0046] This invention requires a certain groove depth. The sealant 74, which completely or partially fills the groove 44, results in an extended creep path. During production or storage, the finished product's electric heating device 2 can be placed on the outer boundary wall 48 because it protrudes as a whole beyond the cover 38. This prevents the circumferential edge 42 from moving relative to the groove 44, which would impair the bond between the circumferential edge 42 and the sealing material 74, and thus compromise the seal. Incidentally, the support sections 72 rest against the inner boundary wall 46. These webs 52 are distributed circumferentially so that the cover 38 is supported circumferentially along the groove 44. This also protects the bond with the sealant 74 and increases the seal. The outer legs 56 are segmented circumferentially on the outer boundary wall 48 between the inner leg flanges 58 and thus interlock with the outer boundary wall. The elastic tension of the circumferential edge 42 in the groove 44 ensures the connection between the cover 38 and the housing 6.

[0047] List of reference numerals

[0048] 2 Heating device

[0049] 4. Lower housing components

[0050] 6. Upper housing components

[0051] 8 heating chambers

[0052] 10. Entrance and exit connection section

[0053] 12 heating devices

[0054] 14 PTC components

[0055] 16 contact elements

[0056] 16.1 Lower Contact Element

[0057] 16.2 Upper Contact Element

[0058] 18 contact tongue

[0059] 20 housing

[0060] 22-frame

[0061] 24 heating units

[0062] 26 insulation layers

[0063] 28 sockets

[0064] 30 partitions

[0065] 32 connecting room

[0066] 34 control devices

[0067] 36 Printed Circuit Boards

[0068] 38 caps

[0069] 40 Cover Surface

[0070] 42 circumferential edge

[0071] 44 grooves

[0072] 46 Inner Boundary Wall

[0073] 48 outer boundary wall

[0074] 50 groove bottom

[0075] 52 webs

[0076] 54 inner support legs

[0077] 56 Outer legs

[0078] 58 Inner support leg flange

[0079] 60 free end

[0080] 62 Lower Region

[0081] 64 Upper Area

[0082] 66 inclined surface

[0083] 68-bend area

[0084] 70 outermost region

[0085] 72 Shelved Section

[0086] 74 Adhesives / Sealants

Claims

1. An electric heating device (2) having a housing (6) that is at least partially conductive and a cover (38) made of a metal plate, wherein a circumferential groove (44) is provided on an end face of the housing, the cover closing the housing (6) and engaging the groove (44) with a circumferential edge (42), the groove containing a sealant (74), wherein, The circumferential edge (42) has a first leg (54) engaged in a groove (44) and a second leg (56) bent away from the first leg.

2. The electric heating device (2) according to claim 1, wherein, At least one of the legs (54, 56) is in conductive contact with the boundary wall (48) of the groove (44).

3. The electric heating device (2) according to claim 1, wherein, At least one of the outriggers (56) is interlocked with at least one of the associated boundary walls (48).

4. The electric heating device (2) according to claim 3, wherein, At least one outer leg (56) is interlocked with the outer boundary wall (48).

5. The electric heating device (2) according to claim 1, wherein, At least one of the outriggers (56) is applied to at least one of the associated boundary walls (48) under elastic preload.

6. The electric heating device (2) according to claim 5, wherein, The outer outrigger (56) is applied to the outer boundary wall (48) under elastic preload.

7. The electric heating device (2) according to claim 5, wherein, The preload is counteracted by supporting one of the legs (54) against one of the boundary walls (48).

8. The electric heating device (2) according to claim 6, wherein, The preload is counteracted by supporting the inner leg (54) against the inner boundary wall (46) of the groove (44).

9. The electric heating device (2) according to claim 1, wherein, The circumferential edge (42) abuts against one of the boundary walls (48) only in a segmented manner in the circumferential direction.

10. The electric heating device (2) according to claim 5 or 6, wherein, The circumferential edge (42) abuts against the outer boundary wall (48) only in segments in the circumferential direction.

11. The electric heating device (2) according to claim 1, wherein, The housing (6) forms a web (52) through the groove (44), and the circumferential edge (42) terminates at the location of the web (52) with an inner flange (58).

12. The electric heating device (2) according to claim 1, wherein, The outer boundary wall (48) protrudes beyond the inner boundary wall (46) of the groove (44), and the cover (38) rests on the inner boundary wall (46).

13. The electric heating device (2) according to claim 1, wherein, The cover surface (40) covering the housing (6) protrudes beyond the portion (72) of the cover (38) resting on the inner boundary wall (46) of the groove (44).

14. A method for manufacturing an electric heating device (2), the electric heating device having a housing (6) that is at least partially conductive and a cover (38) made of a metal plate, wherein a circumferential groove (44) is provided on an end face of the housing, the cover closing the housing (6) and engaging in the groove (44) with a circumferential edge (42), wherein, The circumferential edge (42) is inserted into the groove (44) and then a sealant (74) is applied to the groove (44) and the sealant hardens in the groove (44).

Images