Housing for an electrical device, in particular a switching device or a control device in a motor vehicle

[0002] The present invention relates to an electrical device, in particular, a switching device or a control device in a motor vehicle.

[0003] To sealingly join housing parts and a plug body to one another to prevent the ingress of moisture into the control-device interior, the individual component parts of the control device may be joined to one another by interposing a separating layer made of a flexible seal, as referred to in German Published Patent Application No. 195 16 708. Critical to production, however, are those joints where more than two parts, for example, the two housing parts and the plug body, come into direct contact, since manufacturing and assembly tolerances accumulate in this area. Sealing problems may therefore arise in series production.

[0004] It is believed that an exemplary electrical device and method according to the present invention, such as a switching or control device in a motor vehicle, have the advantage of achieving a reliable sealing of the control device towards the outside. This is essentially due to a projection of the plug body engaging with a recess in the one housing part, which is provided with sealing compound, in the join region where more than two component parts come into contact. In this manner, the sealing compound is displaced in a controlled manner in the direction of the other housing part, so that there is a certain volume of sealing compound present in the join region of the three component parts.

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[0006] FIG. 1 is an exploded view of a control device for a motor vehicle having an exemplary housing according to the present invention.

[0007] FIG. 2 is a sectional view of a control device in the critical join region.

[0008] FIG. 3 is a perspective view of part of the housing cover shown in FIG. 1.

[0009] FIG. 4 shows the housing cover of FIG. 3 subsequent to the application of a sealing compound.

[0010] FIG. 5 shows the housing cover of FIG. 4 showing the placement of the sealing compound in the housing base, without the housing base.

[0011] FIG. 1 shows the main components of an electrical control device 1 used, for example, as a switching or control device in a motor vehicle. Control device 1 has a housing 10, which is composed of a base 11 and a cover 12. In its closed state, housing 10 encloses a printed-circuit board 13, which is fitted with electrical and/or electronic components (not shown). Printed-circuit board 13 is connected to a plug body 15, which has two plug chambers 16, 17 projecting out from housing 10. Plug chambers 16, 17 encloses connector lugs 18, which are in electrical contact with the electronic components of printed-circuit board 13.

[0012] The essentially planar base 11 may be made of sheet metal and may have a depression 19, which accommodates the components positioned on the bottom side of printed-circuit board 13 and/or is set apart therefrom. Cover 12, which is either made from plastic provided with a metal-plated inner side to improve the electromagnetic capability (EMC) shield, or is designed as a metal die-cast part, has a trapezoidal formation 20 for accommodating plug body 15. On rear side 21 of control device 1 opposing plug body 15, as well as on the two housing sides 22, 23, the surfaces of base 11 are essentially planar, while cover 12 is formed with a circumferential sealing spring to ensure secure overlapping.

[0013] At each of the four corners of housing 10, a bore hole 24 is formed in base 11, and in alignment thereto, a threaded receptacle 25 in cover 12 is formed, enabling base 11 and cover 12 to be screwed together using mounting screws 26.

[0014] In base 11, on the side facing cover 12, a first seal in the form of a sealing compound 27 is circumferentially positioned in the edge area in a bead form. On rear side 21, and on both housing sides 22, 23 where the respective surfaces of base 11 and cover 12 lie directly against one another, sealing compound 27 produces an airtight and moisture-tight connection between base 11 and cover 12 when the housing parts are screwed together. On front side 28 of housing 10, from where plug body 15 projects out from housing 10, housing 10 optimizes the seal with respect to plug body 15. Plug body 15 has a circumferential intermediate wall 30 that is adapted to recessed formation 20. Intermediate wall 30 thus has a straight top side 31 that conforms to trapezoidal formation 20, a bottom side 32 disposed parallel thereto, as well as two oblique side edges 33, 34. In the assembled state of control device 1, bottom side 32 of intermediate wall 30 rests on the corresponding section of sealing compound 27, which is applied to base 11. Sealing compound 27 thus forms the seal between bottom side 32, intermediate wall 30 and base 11. To seal the two side edges 33, 34 and top side 31 of intermediate wall 30 towards cover 12, a second seal in the form of sealing compound 35 is provided, which is also applied as a bead at the appropriate locations of intermediate wall 30 in cover 12.

[0015] While the seal between intermediate wall 30 and cover 12 produced by sealing compound 35 is relatively uncritical in the areas of intermediate wall 30, where intermediate wall 30 only needs to be sealed toward cover 12, it is believed that the seal in the two lateral areas 36, where bottom side 32 of intermediate wall 30 transitions to the oblique side edges 33, 34, has presented problems heretofore. The problems may have arisen because, in areas 36, 37 of the assembled control device 1 including cover 12, base 11 and intermediate wall 30 and plug body 15, respectively, three components meet, which must be sealed to one another.

[0016] An exemplary embodiment according to the present invention proposes forming a groove 40 in cover 12 and applying sealing compound 35 thereto, at least in those sections where the two lateral areas 36 of intermediate wall 30 are configured. This groove 40 terminates at a surface 41 of cover 12 where sealing compound 27 is also placed, so that the sealing compound 35 placed in groove 40 directly contacts sealing compound 27 of base 11 when cover 12 is assembled, i.e., an overlap region 42 of the two sealing compounds 27, 35 is formed when control device 1 is assembled. This relationship is shown in FIG. 5, in which, besides cover 12 with its sealing compound 35 placed in groove 40, the placement of sealing compound 27 of base 11 is also shown, without base 11.

[0017] To ensure that the two sealing compounds 27, 35 form an overlap region 42 when the components are assembled, the corresponding section of intermediate wall 30 is positioned in groove 40. In this manner, intermediate wall 30 displaces sealing compound 35 along groove 40 in the direction of overlap region 42 and of sealing compound 27, respectively, when the components are assembled.

[0018] Control device 1 is assembled in the following manner: Once sealing compound 35 is introduced into cover 12, cover 12 is placed with its top facing down. Then, printed-circuit board 13, together with plug body 15 connected thereto, is joined to cover 12 so that intermediate wall 30 is congruent with formation 20 in cover 12. The corresponding sections of intermediate wall 30 displace sealing compound 35 out of groove 40 in the direction of surface 41 of cover 12. Base 11, provided with sealing compound 27, is subsequently brought into alignment with cover 12, so that bore holes 24 align with receptacles 25. Finally, mounting screws 26 are tightened, base 11, cover 12 and intermediate wall 30 of plug body 15 being joined to one another and sealing compounds 27, 35 being squeezed together. At this stage, the assembly of control device 1 is then complete, with sealing compounds 27, 35 subsequently hardening, thereby producing the air- and moisture-tight sealing of control device 1 and housing 10, respectively.