WO2008146213A2

WO2008146213A2 - A watertight metal housing and a method for producing such housing

Info

Publication number: WO2008146213A2
Application number: PCT/IB2008/052021
Authority: WO
Inventors: Jan Van Voorst; Johannes W. M. M. Kemperman; Marcus J. Van Bommel; Ralph H. Peters; Hendrik E. J. Gijsbers
Original assignee: Koninklijke Philips Electronics N.V.; Philips Intellectual Property & Standards Gmbh
Priority date: 2007-05-25
Filing date: 2008-05-22
Publication date: 2008-12-04
Also published as: WO2008146213A3

Abstract

A housing comprising a metal housing part (1) and a metal lid (2) for watertight closure of the housing, where the housing part (1) has a circular opening and the lid (2) has a circular edge, which edge is pressed into the opening of the housing part (1). The housing part (1) and the lid (2) are made of different materials, one material being softer than the other material, and in that a sealing ring between the opening and the lid (2) is present, which sealing ring is formed by plastic deformation of the softer material when the lid (2) is pressed into the opening of the housing part (1).

Description

A watertight metal housing and a method for producing such housing

FIELD OF THE INVENTION

The invention is related to a housing comprising a metal housing part and a metal lid for watertight closure of the housing, the housing part having a circular opening and the lid having a circular edge, which edge is pressed into the opening of the housing part. In fact, the housing has two parts, whereby both parts may enclose a space and may have a complicated shape, however, both assembled parts form the housing and enclose the space inside the housing. Hereinafter, the part of the housing that fits inside the opening of the other part of the housing will be referred to as 'lid', and the other part will be indicated as 'housing part'.

BACKGROUND OF THE INVENTION

The housing can be used, for example, for enclosing electric components, the housing protecting the components against influences from outside such as humidity, electromagnetic radiation, etc. Known housings for such purposes comprise a press fit connection between the housing part and the lid, provided with a rubber O-ring between a smooth circular surface at the opening of the housing part and a corresponding smooth circular surface at the edge of the lid, in order to make the connection between the housing part and the lid watertight. However, application of an O-ring or similar sealing ring requires machining of both circular surfaces to make them smooth. Known watertight engagements between a metal housing part and a metal lid are relatively complicated and expensive.

SUMMARY OF THE INVENTION

An object of the invention is a watertight metal housing comprising a housing part and a lid which are joined together in a simple and cost effective way, whereby a strong connection between the housing part and the lid is obtained.

Another object of the invention is a housing, where the metal housing part and the metal lid are in good electro-conductive contact with each other. Another object of the invention is a housing, where the metal housing part and the metal lid are in good heat-conductive contact with each other.

Another object of the invention is a watertight metal housing comprising a housing part and a lid, where the tolerances of the surfaces engaging each other when pressing the lid into the opening of the housing part are not so strict.

In order to achieve one or more of these objects, the housing part and the lid are made of different materials, where one material is softer than the other material, and in that a sealing ring between the opening and the lid is present, which sealing ring is formed by plastic deformation of the softer material when the lid is pressed into the opening of the housing part. According to the invention, the metal material of the housing part may be softer than the metal material of the lid, but preferably, the material of the lid is softer than the material of the housing part.

The sealing ring can be formed because the metal material of the lid is softer than the relatively hard metal of the housing part. Furthermore, after its creation, the sealing ring can automatically be located between the surface of the edge of the lid and the surface of the wall of the opening of the housing part, whereby the metal sealing ring is firmly clamped between said two surfaces. The expression 'softer' means more ductile, so that plastic deformation of the material is relatively easy.

Several shapes of the edge of the lid and of the wall of the opening of the housing part may result in the establishing of such sealing ring. However, in a preferred embodiment, the wall of the circular opening comprises a tapered portion, where, before the lid is pressed into the opening, the tapered portion tapers from a first diameter at the outer side of the opening to a smaller second diameter, and a cylindrical portion having said second diameter, whereby said circular edge of the lid has a substantially cylindrical surface with a diameter between said first and said second diameter of the opening. Thereby, when the lid is pressed into the opening of the housing part, the side of the edge facing the space inside the housing part will first contact the conical portion of the wall of the opening, whereby the softer material of the lid will deform and move towards the more central part of the surface of the edge when the edge arrives in the cylindrical portion of the wall of the opening of the housing part. Thereby, the metal sealing ring will be clamped between the surface of the edge and the cylindrical portion of the wall of the opening, whereby the material of the housing part around the opening is stretched, resulting in the clamping action.

Preferably, the diameter of the cylindrical portion of the edge of the lid is more than 0.2% larger, preferably more than 0.6% larger than said second diameter of the opening, whereby an appropriate clamping of the sealing ring is established.

In a preferred embodiment, the tapered portion of the opening of the housing part has a substantially conical shape, the apex angle of the cone being between 40° and 90°, preferably between 60° and 70°, the apex angle being the largest angle between two straight lines on the surface of the cone. Experience has shown that such apex angle provides for an effective deformation of the soft material of the lid.

Depending on the shape of the edge of the lid and the shape of the wall of the opening, a relatively small difference in hardness of the metal material of the lid and the metal material of the housing part can be sufficient to create plastic deformation of the metal of the lid. However, preferably, the difference between the hardness of metal material of the lid and the metal material of the housing part is at least 20 HV, preferably at least 35 HV. Experience has shown that such difference in hardness allows a sufficient deformation of the material of the lid for forming an appropriate sealing ring.

In a preferred embodiment, the material of the lid is aluminum, and, preferably, the material of the housing part is also aluminum. Aluminum has good heat- conductive and electro-conductive properties and can be made with different hardness properties. The expression 'aluminum' includes aluminum alloys.

Preferably, the edge of the lid is formed by a punching operation, which operation produces a burr at the side of the lid facing the space inside the housing part. A punching operation is a simple and inexpensive production operation, whereby, in general, the punched parts need a further treatment in order to remove the burr and/or to meet the required tolerances. However, such treatment is not necessary when applying the invention, and the presence of a burr has appeared to be an advantage for forming the sealing ring. The invention can preferably be applied for producing the housing for enclosing automotive electronic components. Such components have to be enclosed in a watertight housing, and often the housing has to shield the electronic components from electromagnetic radiation. Such housings including automotive components are mass produced, whereby inexpensive and reliable manufacturing is of great importance.

A preferable application of the invention is the housing enclosing the PCB (printed circuit board) of a LED (light emitting diode), whereby the housing part as well as the lid function as a heat sink for cooling the LED. Thereby the housing will shield the PCB from electromagnetic radiation, and the whole housing, both the housing part and the lid, can function as the heat sink for cooling the LED, because of the heat-conductive properties of the metal sealing ring located between these two portions of the housing.

The invention is also related to a method for closure of a metal housing part by means of a metal lid to obtain a watertight housing, where the housing part has a circular opening and the lid has a circular edge, whereby the edge of the lid is pressed into the opening of the housing part, wherein the housing part and the lid are made of different materials, one material being softer than the other material, and wherein a sealing ring between the opening and the lid is formed by plastic deformation of the softer material when pressing the lid into the opening of the housing part.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be further elucidated by means of a description of two embodiments of the watertight metal housing comprising a housing part and a lid. The first embodiment is a simple housing in order to explain the principle of the invention and the second embodiment is an example wherein the invention is applied in practice. Reference is made to the diagrammatical drawing, where:

Fig. 1 is a sectional view of the first embodiment;

Fig. 2 is a view according to arrow II in figure 1;

Fig. 3, 4 and 5 are sectional views of a detail of the first embodiment; and

Fig. 6 and 7 are exploded views of the second embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

Figures 1 and 2 are schematic views the first embodiment. The sectional view of figure 1 shows a housing part 1 and a flat disk- like lid 2. The housing part 1 comprises a flat bottom wall 3 and a cylindrical side wall 4. The edge 5 of the side wall 4 has a tapered surface 6. The flat lid 2 is fixed to the housing part 1 by means of a press fit, whereby the lid 2 is pressed into the opening of housing part 1, so that the housing part 1 and the lid 2 enclose the space 7 inside the housing. Figure 2 is a view of the housing along the arrow II in figure 1, and shows the edge 5 having the tapered surface 6 surrounding the flat disk- like lid 2.

The housing part 1 and the lid 2 are made of different aluminum alloys, whereby the grade of the aluminum material of the lid 2 is softer than the aluminum material of housing part 1. This means that the material of the lid 2 will be deformed by the harder material of the housing part 1 when the lid 2 is pressed into the housing part 1. The deformation of the softer material of the lid 2 is shown in the figures 3, 4 and 5.

Figures 3, 4 and 5 are sectional views of a detail of the housing, which detail is indicated with circle 8 in figure 1. Figure 3 shows the lid 2 and the side wall 4 of the housing part 1 before the press fit operation has taken place, whereby the lid 2 is at a distance from the side wall 4. The diameter of the lid 2 is larger than the inner diameter of the side wall 4. The edge 5 of the side wall 4 is provided with an inclined portion 6, being a tapered conical surface. When the press fit operation starts, the lid 2 and the side wall 4 move towards each other, as is indicated with arrow 10. Then, the inner side 9 of the substantially cylindrical edge of lid 2 will contact the inclined portion 6 as is shown in figure 4. Because the aluminum material of lid 2 is softer than the aluminum material of side wall 4, the inner side 9 of the edge of lid 2 will be deformed by the contact with the tapered portion 6 of the side wall 4, whereby material 11 of lid 2 moves away from the inner side 9 of the edge of lid 2 to the space between the cylindrical edge of the lid 2 and the inclined portion 6 of side wall 4. Subsequently, the aluminum material 11 will form a sealing ring 12 between the edge of the lid 2 and the cylindrical inner surface of side wall 4 when the lid 2 is further pressed along the side wall 4, as is shown in figure 5. Thereby the edge 5 of the side wall 4 of the housing part 1 will deform elastically, so that the lid 2 is clamped into the side wall 4, and whereby the sealing ring 12 is clamped between the lid 2 and the side wall 4 of housing part 1. Thereby, a watertight sealing is obtained, as well as an electro-conductive and heat- conducting connection between the lid 2 and the side wall 4. In case the flat disk- like lid 2 is punched out of aluminum plate material, the side 5 of the substantially cylindrical edge of lid 2 will be provided with a burr, so that more aluminum material 11 (figure 4) will be deformed in order to form the sealing ring 12 (figure 5).

The second embodiment, shown in figures 6 and 7 in exploded views, is a housing of a LED for the rear lighting module for a car, where the PCB 21 of the LED 22 is enclosed in the housing and where the LED 22 (light emitting diode) is mounted on the outer side of the housing part 23 of the housing. Figure 6 shows the complete lighting module and figure 7 shows the lower side of PCB 21 (printed circuit board) and the lower side of the housing part 23. Compared to figure 6, the parts in figure 7 are represented upside down.

The housing part 23 is provided with connection means 24 for supplying electric power to the lighting module. The LED 22 is fixed on top of the housing part 23 by connection member 27. The circular edge 28 of the housing part 23 has an inner cylindrical surface and a tapered portion similar to the edge 5 of side wall 4 of the described first embodiment. The lid 29 has a cylindrical outer edge 30, which edge 30 cooperates with edge 28 of the opening of housing part 23 when the lid 29 is pressed into the opening of the housing part 23, whereby a sealing ring is formed by material of the edge 30 of lid 29, as was elucidated in the description of the first embodiment.

The housing for the PCB 21 is not only watertight, but also forms a shield against electromagnetic radiation, because of the electro-conductive properties of the sealing ring 12. Furthermore, the whole housing provides a cooling of the lighting module, because of the heat-conductive properties of the sealing ring 12. For cooling purposes the outer side of the lid 29 is provided with protrusions 31.

The two embodiments described above are only examples of a metal watertight housing according to the invention, many other embodiments and applications of the housing are possible.

Claims

CLAIMS:

1. A housing comprising a metal housing part (1,23) and a metal lid (2,29) for watertight closure of the housing, whereby the housing part (1,23) has a circular opening and the lid (2,29) has a circular edge (30), which edge (30) is pressed into the opening of the housing part (1,23), characterized in that the housing part (1,23) and the lid (2,29) are made of different materials, where one material is softer than the other material, and in that a sealing ring (12) between the opening and the lid (2,29) is present, the sealing ring (12) being formed by plastic deformation of the softer material (11) when the lid (2,29) is pressed into the opening of the housing part (1,23).

2. A housing as claimed in claim 1, characterized in that the material of the lid (2,29) is softer than the material of the housing part (1,23).

3. A housing as claimed in claim 2, characterized in that the wall (4) of the circular opening comprises a tapered portion (6), where, before the lid (2,29) is pressed into the opening, the tapered portion (6) tapers from a first diameter at the outer side of the opening to a smaller second diameter, and a cylindrical portion having said second diameter, whereby said circular edge of the lid (2,29) has a substantially cylindrical surface (30) having a diameter between said first and said second diameter of the opening.

4. A housing as claimed in claim 3, characterized in that the diameter of the cylindrical portion (30) of the edge of the lid (2,29) is more than 0.2% larger, preferably more than 0.6% larger than said second diameter of the opening.

5. A housing as claimed in claim 3 or 4, characterized in that the tapered portion (6) of the opening of the housing part (1,23) has a substantially conical shape, the apex angle of the cone being between 40° and 90°, preferably between 60° and 70°.

6. A housing as claimed in any one of the preceding claims, characterized in that the difference between the hardness of material of the lid (2,29) and the material of the housing part (1,23) is at least 20 HV, preferably at least 35 HV.

7. A housing as claimed in any one of the preceding claims, characterized in that the material of the lid (2,29) is aluminum, and, preferably, the material of the housing part (1,23) is also aluminum.

8. A housing as claimed in any one of the preceding claims, characterized in that the edge (30) of the lid (2,29) is formed by a punching operation, which operation produces a burr at the side (9) of the lid (2,29) facing the space inside the housing part (1,23).

9. A housing as claimed in any one of the preceding claims, characterized in that the housing encloses an electronic component for an automobile.

10. A housing as claimed in any one of the preceding claims, characterized in that the housing encloses the PCB (printed circuit board) of a LED, whereby the housing part (1,23) as well as the lid (2,29) is a heat sink for cooling the LED.

11. A method for closure of a metal housing part (1 ,23) by means of a metal lid (2,29) to obtain a watertight housing, where the housing part (1,23) has a circular opening and the lid (2,29) has a circular edge (30), whereby the edge (30) of the lid (2,29) is pressed into the opening of the housing part (1,23), characterized in that the housing part (1,23) and the lid (2,29) are made of different materials, one material being softer than the other material, and in that a sealing ring (12) between the opening and the lid (2,29) is formed by plastic deformation of the softer material (11) when pressing the lid (2,29) into the opening of the housing part (1,23).