Sealing Compound Housing and Electronic Control Device

Abstract

The disclosure relates to a sealing compound that can be applied wet and is curable to form an elastic seal. The sealing compound contains a matrix material and a corrosion-inhibiting additive. In addition, a housing having the elastic seal as well as an electronic control device with the housing are disclosed.

Claims

1. A sealing compound that can be applied wet and can be cured to give an elastic seal, wherein the sealing compound comprises a matrix material and a corrosion-inhibiting additive.

2. The sealing compound of claim 1, wherein the matrix material comprises a silicone material or a polyurethane material.

3. The sealing compound of claim 1, wherein the corrosion-inhibiting additive has been added to the matrix material in the form of a multiplicity of particles.

4. The sealing compound of claim 3, wherein the particles are bead-shaped.

5. The sealing compound of claim 4, wherein the particles have the same diameter and the diameter has a value of 0.1 mm or more and of 0.4 mm or less.

6. The sealing compound of claim 1, further comprising a thixotropic agent for uniform distribution of the corrosion-inhibiting additive in the sealing compound.

7. The sealing compound of claim 1, wherein the corrosion-inhibiting additive is designed as a sacrificial anode.

8. The sealing compound of claim 1, wherein the corrosion-inhibiting additive comprises zinc particles.

9. The sealing compound of claim 1, wherein the corrosion-inhibiting additive is designed to bind intermediate products of a corrosion reaction.

10. The sealing compound of claim 1, wherein the corrosion-inhibiting additive comprises zinc phosphate particles.

11. The sealing compound of claim 1, wherein the corrosion-inhibiting additive comprises particles of a pH-buffering material.

12. A housing for an electronic control unit, that housing having a metallic housing part and a further housing part, there being formed, between the metallic housing part and the further housing part, a sealing joint filled with an elastic seal composed of a cured sealing compound, the cured sealing compound can be applied wet and can be cured to give an elastic seal, wherein the sealing compound comprises a matrix material and a corrosion-inhibiting additive.

13. The housing of claim 12, wherein the metallic housing part is formed at least in a region of the sealing joint from a first metallic material, and the sealing compound comprises particles of a second metallic material as corrosion-inhibiting additive, an electronegativity of the second metallic material being greater than that of the first metallic material.

14. The housing of claim 13, wherein the first metallic material is an aluminum alloy comprising silicon and copper.

15. The housing of claim 12, wherein the further housing part is formed of a metal sheet that has been coated.

16. The housing of claim 15, wherein the metal sheet is an iron sheet.

17. The housing of claim 12, wherein the corrosion-inhibiting additive has been added to the matrix material in the form of a multiplicity of bead-shaped particles of which two or more contact both the metallic housing part and the further housing part to establish a minimum height of the sealing joint.

Description

DESCRIPTION OF DRAWINGS

[0030] FIG. 1 shows a schematic sectional representation of a detail of a conventional housing,

[0031] FIG. 2 shows a schematic sectional representation of a detail of a housing for a control unit according to a first example,

[0032] FIG. 3 shows a schematic sectional representation of a detail of a housing for a control unit according to a second example, and

[0033] FIG. 4 shows a schematic sectional representation of a detail of a housing for a control unit according to a third example.

[0034] Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

[0035] Elements which are the same, which are of the same kind or which have the same effect are given the same reference symbols in the figures. In certain figures, individual reference symbols may be omitted in order to improve clarity. The figures and the size ratios of the elements shown in the figures to one another should not be considered as being to scale. Instead, for improved representation and/or for greater ease of understanding, individual elements may be shown with exaggerated size.

[0036] FIG. 1 shows a housing 20 of an electronic control unit with a conventional elastic seal 1, which is disposed in a sealing joint 26 between a first metallic housing part 22 and a further metallic housing part 24. By means of the seal 1 extending along the sealing joint 26, an interior space 28 of the housing 20 is sealed with respect, for example, to penetrating moisture.

[0037] Over the lifetime of the control unit, the metallic housing parts 22, 24 may suffer corrosion. In that case, corrosion pathways 32, 34 may form, which undermine the seal 1. For instance, moisture may penetrate through the sealing joint 26 into the interior space 28 of the housing (see, for example, the corrosion pathway 34 in FIG. 1). The penetrating moisture may adversely affect the functional capacity of the control unit.

[0038] FIG. 2 shows a schematic sectional view of a detail of a housing 20 according to the disclosure. More precisely, FIG. 2 shows a marginal region of the housing 20. In some examples, the housing 20 is a housing 20 of an electronic control unit, such as of a motor vehicle control unit, for example. The control unit is, for example, an engine control unit.

[0039] The housing 20 has a first, metallic housing part 22. This part is, for example, a pressure casting made of an aluminum alloy, more particularly of an alloy familiar to the skilled person as AlSiCu. The first housing part is, for example, a main housing body into which a circuit board populated with electronic components can be insertedand, in the completed control unit, is inserted.

[0040] The housing 20 has a further housing part 24. The further housing part 24, for example, is a cover that seals an assembly aperture in the first housing part 22. In the present case, the further housing part 24 is formed from an iron sheet, by means of embossing, deep drawing or the like, for example.

[0041] The further housing part 24 is mounted in the region of the assembly aperture onto the first housing part 22 in such a way that a sealing joint 26 is formed along a peripheral marginal region, this sealing joint 26 producing a fluid-impervious connection between the housing parts 22, 24.

[0042] The fluid-impervious connection is obtained by means of an elastic seal 1 which is disposed in the sealing joint 26 in a gap-filling manner, and which therefore borders both the first housing part 22 and the further housing part 24 in order to seal the sealing joint 26. By means of the elastic seal 1, an interior space 28 in the housing 20 is given fluid-impervious closure with respect to the surroundings of the housing 20.

[0043] To produce the elastic seal 1, a sealing compound is applied wet to one of the housing parts 22, 24in the form of a sealing bead, for exampleand subsequently the other housing part 22, 24 is pressed onto the sealing compound. In this process, the sealing compound becomes plastically deformed and thus acquires its ultimate form. The sealing compound is subsequently cured to give the elastic seal 1. For this purpose, depending on the material involved, the sealing compound may be subjected, for example, to light, such as UV light, or to heat.

[0044] In some examples, the sealing compoundand hence also the elastic seal 1 after the curing of the sealing compoundincludes a silicone material or a polyurethane material as matrix material 11. In the case of polyurethane material, for example, a heavy metal plasticizer may have been added to the matrix material 11.

[0045] Embedded into the matrix material are zinc particles with a volume fraction of 10% or more, such as of 30%, for example, as corrosion-inhibiting additive 12. The sealing compound may further include silica gel as thixotropic agent in order to distribute the zinc particles uniformly within the silicone material.

[0046] Because of moisture in the region of the sealing joint 26, for example, there may be a corrosion reaction with the metallic housing parts 22, 24. In that case, the zinc particles present as corrosion-inhibiting additive 12 in the seal 1 act as sacrificial anodes, which give up electrons and in the process are oxidized. The giving-up of electrons by the housing parts 22, 24 is thereby advantageously reduced or prevented entirely in the region of the sealing joint 26, meaning that at that location the housing parts 22, 24 do not undergo corrosion. The volume fraction of the corrosion-inhibiting additive 12 is below the percolation limit, and so, even if the additive is corroded, a reliably sealing contact between the seal 1 and the housing parts 22, 24 is ensured by means of the matrix material 11. The risk of moisture penetrating into the interior space 28 of the housing 20 through the sealing joint 26 is therefore particularly low.

[0047] Instead of the zinc particles or in addition to them, the sealing compound may have a different corrosion-inhibiting additive 12 selected from those described earlier on above.

[0048] FIG. 3 shows a schematic sectional representation of a marginal section of a housing 20 according to a second example. The housing 20 of the second example corresponds essentially to that of the first example shown in FIG. 2.

[0049] As shown in FIG. 3, however, the further housing part 24 has a main body 242 formed of an iron sheet. This body is provided, on its side facing the sealing joint 26, with a coating 244. In the present case, the coating 244 is formed of a zinc layer or of a zinc-magnesium layer, which is applied on the main body 242. By means of the coating 244, corrosion protection of the further housing part 24 can be achieved even at locations not covered by the seal 1. Alternatively or additionally, the main body 242 may have been provided with the coating 244 on its side facing away from the sealing joint 26.

[0050] Moreover, the first housing part 22 is provided with a groove 222 extending along the sealing joint 26. At production, the sealing compound is applied, preferably as a sealing bead, along the groove 222 to the first housing part 22. In this case, by means of the groove 222, the sealing compound can be positioned with particular accuracy.

[0051] FIG. 4 shows a schematic sectional representation of a marginal section of a housing 20 according to a third example. The housing 20 of the third example corresponds essentially to that of the first example shown in FIG. 2.

[0052] As shown in FIG. 4, however, spherical zinc particles, rather than zinc dust, have been added as corrosion-inhibiting additive 12 to the matrix material 11. All particles have the same diameter of 0.3 mm.

[0053] The spherical zinc particles set the minimum height of the sealing joint 26. For this purpose, at production, the housing parts 22, 24 are pressed against one anotherwith plastic deformation of the sealing compound applied to at least one of the housing parts 22, 24until the zinc particles make contact with both the first housing part 22 and the second housing part 24. The sealing compound is subsequently cured to give the seal 1.

[0054] The description using examples does not confine the invention to these examples. Instead, the invention encompasses every new feature and also every combination of features, including in particular every combination of features in the examples and the claims.