Electrical heater and method for manufacturing a cover for a heater

Abstract

Disclosed is an electrical heater comprising a housing, said housing comprising a first metallic housing part (6) and a second metallic housing part (10), wherein the first housing part (6) has a groove (8) containing a sealant, and the second housing part (10) has a flap (11) inserted into the groove (8). According to the invention, the flap (11) has bumps (12) contacting a wall (8a, 8b) of the groove (8). Also disclosed is a method for producing a cover for an electrical heater housing.

Description

[0001] The invention refers to an electrical heater. A heater according to the preamble of claim 1 is disclosed in US 2022 / 0082297 A1.

[0002] Electrical heaters are used in vehicles for various purposes, e.g. to heat various fluids, e.g. aqueous solutions in heating systems. Vehicle manufacturers place stringent requirements on electromagnetic compatibility of electric heaters. In order to meet these requirements, the housing of an electrical heater must provide electromagnet shielding and also protect the interior of the heater from dirt and moisture. In prior art heaters electromagnetic shielding is achieved by means of a metallic housing comprising two or more housing parts that are in electrical contact.

[0003] An object of the invention is to show how electrical contact and a sealed connection between a first and a second housing part of an electric heater can be achieved reliably at low cost.

[0004] This object is solved by an electrical heater according to claim 1 and a method for manufacturing a cover of an electrical heater according to claim 13.

[0005] According to the present invention, an electrical heater comprises a first metallic housing part and a second metallic housing part. The first housing part has a groove containing a sealant, e.g. an adhesive, and the second housing part has a flap that is arranged in the groove. In order to ensure electrical contact between the first and the second housing part, the flap of the second housing part is provided with bumps. When the flap is inserted into the groove, the bumps contact a wall of the groove and thereby establish electrical contact. The width of the groove and the height of the bumps are dimensioned to ensure that the bumps are pressed against a wall of the groove and reliably cause electrical contact between the first and the second metallic housing part.

[0006] Bumps can be cost-efficiently provided in the flap by embossing. A bump on one face of the flap then corresponds to a dimple on an opposite face of the flap.

[0007] In a refinement of the invention, bumps are provided both on an inner surface of the flap and on an outer surface of the flap. Bumps on the inner surface the flap point towards the inside of the heater whereas bumps on the outer surface of the flap point are oriented towards the outside of the heater. Bumps on both the inner and the outer surface of the flap facilitate elastic deformation of the flap when it is pushed into the groove. During insertion of the flap into the groove, the bumps scrape along both the inner and the outer wall of the groove and thereby reliably cause electrical contact. The bumps can then resiliently press against the walls of the groove and thus reliably cause and maintain electrical contact between the first housing part and the second housing part.

[0008] In a further refinement of the invention, bumps may be arranged on a circumferential line, e.g. in a row.

[0009] As the function of the bumps is primarily to ensure electrical contact between the first housing part and the second housing part, large sections of the flap may be free of bumps. For example, the bumps may be arranged in groups or equidistantly.

[0010] The second housing part may for example be a cover. Such a cover can be cost-efficiently manufactured by a method comprising cutting sheet metal to size and deep drawing the sheet metal to form a cover comprising a flap, wherein bumps and dimples are then created in the flap by embossing.

[0011] In a further refinement of the invention, the sealant arranged inside the groove is an adhesive. The adhesive may be an electrically conductive adhesive, e.g. an adhesive comprising electrically conductive particle, like metallic or graphite particles, but advantageously cheaper adhesives that are electrically isolating may also be used.

[0012] Reliable electrical contact between the first housing part and the second housing part makes the invention well suited for high voltage application, e.g. heater operated at voltages of 100 V or more.

[0013] The above-mentioned aspects of illustrative embodiments will become more apparent and will be better understood by reference to the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Fig. 1shows an electrical heater; Fig. 2shows a housing part of the heater; and Fig. 3shows a schematical detail view of a groove of a first housing part with an inserted flap of a second housing part of the heater.

[0014] Fig. 1 shows a heater 1 that is a flow heater comprising a housing having an inlet 2 and an outlet 3 as well as electrical connectors 4, 5. An electrical resistor is arranged inside the housing. A flow channel for liquid to be heated extends inside the housing from the inlet 2 to the outlet 3.

[0015] The housing comprises a first housing part 6 and a second housing part 10. Both the first housing part 6 and the second housing part 10 are made of metal, e.g. an aluminum alloy. The second housing part 10 is a cover, e.g. made of sheet metal by deep drawing, and shown in fig. 2. The second housing part 10 has a flap 11 extending along its entire rim. The flap 11 is provided with bumps 12. These bumps 12 may be created by embossing and are provided on both an inner side or surface of the flap 11 as well as on an outer side or surface of the flap. Bumps 12 on one side of the flap 11 then correspond to dimples 13 on an opposite side of the flap 11. Hence, some bumps 12 point outwards as shown in fig. 2 and the flap 11 has a dimple 13 on the backside of each such bump 12, i.e. on an inner side of the flap 11. Other bumps point inwards into the housing and the flap 11 has a dimple 13 on the outer side of the flap 11. In the embodiment shown, bumps 12 and dimples 13 are arranged alternatingly on the flap 11.

[0016] The first housing part 6 has a groove that extends circumferentially along the entire rim of the first housing part 6 and contains a sealant. The flap 11 of the second housing part 10 is inserted into the groove. Fig. 3 shows schematically a detail view of the groove 8 of the first housing part 6 with the flap 11 of the second housing part 10 inserted therein. As can be seen in fig. 3, bumps 12 on the outer side of the flap 11 contact the outer wall 8a of the groove 8 and bumps on an inner side of the flap 11 contact an inner wall 8b of the groove 8.

[0017] There may be only two housing parts. It is also possible to have housing comprising more than two housing parts, e.g. a housing with one first housing part and two second housing parts arranged above and below the first housing parts. Although the embodiment shown in fig. 1 is a flow heater, the combination of a first and second housing parts as described herein may also be used for other electrical heaters or other electrical devices.

[0018] In the embodiment shown, all bumps 12 are arranged on a circumferential line on the flap 11. This means that in a direction perpendicular to the circumferential direction, no bump 12 has a neighboring bump 12. All bumps 12 may be arranged on the same height of the flap 11 withing manufacturing tolerances, e.g. at the same distance from a bottom of the groove after insertion of the flap 11.

[0019] The flap 11 may touch the bottom of the groove. Another possibility is that there is a distance between the bottom of the groove 8 and the flap 11 and that the second housing part 10 rests on the inner wall 8b of the groove 8, as shown in fig. 3.

[0020] The flap 11 may have several linear sections that each have a plurality of bumps 12 in order to ensure electrical contact. Between such linear sections, the flap may be curved.

[0021] The sealant in the groove may be an adhesive, especially a cost efficient electrically isolating adhesive, but electrically conducting adhesives may also be used. Adhesives are usually electrically isolating, but can be made conductive by adding electrically conductive particles, e.g. metallic particles.List of reference signs

[0022] 1heater 2inlet 3outlet 4electrical connector 5electrical connector 6first housing part 8groove 8aouter wall of groove 8binner wall of groove 10second housing part 11flap 12bump 13dimple

Claims

1. Electrical heater comprising a housing, said housing comprising a first metallic housing part (6) and a second metallic housing part (10), wherein the first housing part (6) has a groove (8) containing a sealant, and the second housing part (10) has a flap (11) inserted into the groove (8), characterized in that the flap (11) has bumps (12) contacting a wall (8a, 8b) of the groove (8).

2. Heater according to claim 1, characterized in that the groove (8) is a circumferential groove extending along the entire rim of the first housing part (6).

3. Heater according to any one of the preceding claims, characterized in that the bumps (12) are arranged on an inner surface of the flap (11) and also on an outer surface of the flap (11).

4. Heater according to any one of the preceding claims, characterized in that the bumps (12) are embossed bumps.

5. Heater according to any one of the preceding claims, characterized in that there is a dimple (13) on a backside of each bump (12).

6. Heater according to claim 5, characterized in that on both the inner surface and the outer surface of the flap (11) bumps (12) and dimples (13) are arranged alternatingly in a row.

7. Heater according to any one of the preceding claims, characterized in that the second housing (10) part is a cover.

8. Heater according to any one of the preceding claims, characterized in that the second housing (10) part is made of sheet metal.

9. Heater according to any one of the preceding claims, characterized in that the sealant is an adhesive.

10. Heater according to any one of the preceding claims, characterized in that the flap (11) has several linear sections that each have a plurality of bumps (12).

11. Heater according to any one of the preceding claims, characterized in that the bumps (12) are arranged on a circumferential line.

12. Heater according to any one of the preceding claims, characterized in that an outer wall (8a)) of the groove (8) has a greater height than an inner wall (8b) of the groove (8), and that the second housing (10) part rests of the inner wall (8b).

13. Method of producing a cover for an electrical heater housing, said method comprising cutting sheet metal to size and deep drawing the sheet metal to form a cover comprising a flap (11), characterized by creating bumps (12) and dimples (13) in the flap (11) by embossing.

14. Method according to claim 13, characterized in that opposing surfaces of the flap (11) are embossed.

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