Abstract:
A device housing, especially for accommodating an electronic unit or a mechatronic unit, has parts which are sealed against one another in assembled condition via an encircling, stationary seal. At least one pressure-relief device is integrated into the seal for admission of air into the housing. The seal is formed at least in part as a lip that opens under overpressure conditions inside the housing. To allow any water that has penetrated to flow away, the housing is mounted vertically, with the pressure-relief device disposed at the bottom.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates generally to a device housing, and, more particularly, to a housing for an electronic unit or a mechatronic unit. The present invention has particular application in vehicle systems.  
         [0002]     Large numbers of housings for electronic and mechatronic units are routinely manufactured, and so they must be capable of being manufactured at a favorable cost. In addition, however, adequate protection of the electronic or mechatronic unit disposed in the housing must also be ensured, especially for service under difficult ambient conditions, such as in motor vehicles. In particular, uncontrolled ingress of water into the housing must be prevented. For this purpose, the housing is typically equipped with an encircling, statically designed, elastic seal, which seals a top part against a bottom part of the housing in the assembled condition.  
         [0003]     Furthermore, it is advantageous for the housing to be capable of controlled air exchange with the surrounding atmosphere (“breathing”). This serves to prevent condensation from forming in the interior of the housing under fluctuating ambient temperatures. In mechatronic units, which may operate with injection of compressed air into the housing, this also serves to prevent potentially harmful overpressure in the housing.  
         [0004]     DE 19704532 A1 as well as EP 0772959 B1 describe watertight housings composed of a top part and a bottom part, wherein the two parts in assembled condition are sealed against one another by an encircling seal. This arrangement prevents the ingress of dirty water into the housing. However, conventional housings for electronic and mechatronic units do not have any openings to atmosphere that permit a breathing process.  
         [0005]     DE 10022124 A1 describes a housing for a control unit, especially a mechatronic unit, which is provided with a pressure-relief bore for venting or admitting air. This arrangement prevents condensation from forming in the housing and also maintains the pressure in the interior space at atmospheric pressure. This arrangement also prevents a pressure rise in the interior space of the housing in the event of a leak from a compressed-air supply to a pressure sensor. The housing described in DE 10022124 A1, however, suffers from the disadvantage that dirty water can reach the interior space through the bore. As a result, sensitive components can be damaged.  
         [0006]     Accordingly, it is desired to provide a device housing, especially for an electronic unit or a mechatronic unit, that protects against the ingress of dirty water and, at the same time, permits rapid pressure relief to atmosphere in the event of an overpressure condition in the housing.  
       SUMMARY OF THE INVENTION  
       [0007]     Generally speaking, it is an object of the present invention to provide a housing for an electronic unit or a mechatronic unit that avoids the disadvantages of conventional housings.  
         [0008]     The housing according to the present invention integrates a pressure-relief device in an encircling seal between top and bottom parts of the housing. By virtue of a labyrinth effect, extensive sealing of the housing against external dirty water is achieved, while, by virtue of a lip, rapid discharge of overpressure from the interior space to atmosphere is also permitted. The present invention avoids the need for special devices such as overpressure valves, allowing the inventive housing to be manufactured inexpensively.  
         [0009]     Still other objects and advantages of the present invention will in part be obvious and will in part be apparent from the specification.  
         [0010]     The present invention accordingly comprises the features of construction, combination of elements, and arrangements of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     For a fuller understanding of the present invention, reference is had to the following description taken in connection with the accompanying drawings in which:  
         [0012]      FIG. 1  depicts a part of a housing according to an embodiment of the present invention with an encircling seal lodged in place;  
         [0013]      FIG. 2  depicts the part of the housing according to  FIG. 1  without an encircling seal lodged in place;  
         [0014]      FIG. 3  depicts an encircling seal with integrated pressure-relief devices in accordance with an embodiment of the present invention;  
         [0015]      FIG. 4  is an enlarged view of a pressure-relief device in accordance with an embodiment of the present invention;  
         [0016]      FIG. 5  is a rear view of the pressure-relief device depicted in  FIG. 4 ;  
         [0017]      FIG. 6  is a cross-sectional view of an encircling seal in a static region in accordance with an embodiment of the present invention;  
         [0018]      FIG. 7  is a cross sectional view of an encircling seal in a region of a pressure-relief device in accordance with an embodiment of the present invention; and  
         [0019]      FIG. 8  is a cross sectional view of a housing in assembled condition with an encircling seal lodged in place in accordance with an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     Referring to the drawing figures, where like reference numerals are used for corresponding parts,  FIG. 1  is a perspective view of a “bottom” part ( 2 ) of a housing ( 1 ) for an electronic unit or a mechatronic unit. An encircling seal ( 3 ) is shown lodged in a groove ( 12 ) defined in the housing (compare with  FIG. 2 ).  
         [0021]     Although housing ( 1 ) is generally designed for installation and use in vertical position with a pressure-relief device ( 4 ) disposed at the bottom, (see  FIG. 8 ), for ease of explanation, the terms “top” part and “bottom” part of the housing will hereinafter be used to refer to the housing parts ( 17 ) and ( 2 ), respectively, shown mounted side-by-side in  FIG. 8 . Parts ( 17 ) and ( 2 ) may also be referred to as “side” parts.  
         [0022]     Seal ( 3 ) is preferably formed from an elastic material, such as rubber or plastic, for example. Mechanical, pneumatic and electronic components can be disposed in known manner in the interior of housing ( 1 ). Seal ( 3 ) is provided with two pressure-relief devices ( 4 ) which will be described in greater detail hereinafter.  
         [0023]      FIG. 2  depicts the bottom part ( 2 ) of housing ( 1 ) as shown in  FIG. 1 , but without seal ( 3 ) lodged in place. Groove ( 12 ) is defined in the bottom part of the housing and widens to become semicircular in shape at two places—i.e., where the two pressure-relief devices ( 4 ) are disposed (see e.g.,  FIGS. 1 and 3 ). These devices ( 4 ) are fixed in place, e.g., by means of retaining pins ( 9 ,  10 ) which engage through corresponding perforations ( 7 ,  8 ) in the seal ( 3 ) (see e.g.,  FIGS. 4 and 8 ).  
         [0024]      FIG. 2  further shows two breathing bores ( 15 ,  16 ) disposed in bottom part ( 2 ) of housing ( 1 ) and which open from outside into pressure-relief devices ( 4 ) from the underside or from the side thereof. Bores ( 15 ,  16 ) can be used in known manner to test the ability of the housing to resist leaks. They also permit air exchange or a “breathing” process between the interior space of housing ( 1 ) and the surrounding atmosphere under fluctuating ambient temperatures.  
         [0025]     In  FIG. 3 , encircling seal ( 3 ) is depicted by itself. Seal ( 3 ) includes a static part ( 6 ). The static part ( 6 ) of seal ( 3 ) is depicted in cross section in  FIG. 6 .  
         [0026]     In the bottom part, seal ( 3 ) has two pressure-relief devices ( 4 ) which are equipped on the underside or outside with a V-shaped elastic lip ( 5 ) (see  FIG. 7 ). A transition ( 11 ) between static part ( 6 ) of seal ( 3 ) and lip ( 5 ) is a preferably continuous structure with constant profile height. Lip ( 5 ) has a double-edge structure (see  FIG. 7 ). In contrast, the static part ( 6 ) of seal ( 3 ) has a rectangular shape with one rounded narrow side ( 18 ) (see  FIG. 6 ).  
         [0027]     Along the inner periphery of the seal in the region of pressure-relief devices ( 4 ) there are disposed a plurality of protuberances ( 19 ) between which air can pass.  
         [0028]      FIG. 4  is an enlarged view of one of the pressure-relief devices ( 4 ). Perforations ( 7 ,  8 ) function, as indicated above, to accommodate retaining pins ( 9 ,  10 ) (see  FIG. 2 ) and thus to fix pressure-relief device ( 4 ) in place.  
         [0029]     Between discrete protuberances ( 19 ) it is possible for air to pass through (labyrinth seal)—not only from the housing interior to the outside but also in the opposite direction. Protuberances ( 19 ) also function as support for a bead portion ( 21 ) (see  FIG. 5 ) on the back side of the seal and for fixing the pressure-relief devices in place.  
         [0030]     In its static part, seal ( 3 ) is further provided with knobs ( 13 ,  14 ) which are distributed over its periphery and prevent seal ( 3 ) from falling out of groove ( 12 ) during assembly. Moreover, centering of seal ( 3 ) in groove ( 12 ) is achieved by knobs ( 13 ,  14 ).  
         [0031]      FIG. 5  shows one of the pressure-relief devices ( 4 ) from  FIG. 4  from the back side, together with bead ( 21 ).  
         [0032]      FIG. 6  shows, as indicated above, seal ( 3 ) in cross section in the static region. Here, seal ( 3 ) has a rectangular shape with a rounded narrow side ( 18 ).  
         [0033]      FIG. 7  shows seal ( 3 ) in cross section in the region of one of the pressure-relief devices ( 4 ). As shown, lip ( 5 ) has a preferably double-edged structure. It is also possible, however, for lip ( 5 ) to have a single-edged structure. In such case, the other side is formed as a bead.  FIG. 7  further shows one of the protuberances ( 19 ) and the oppositely disposed bead ( 21 ).  
         [0034]      FIG. 8  is a cross-sectional view of housing ( 1 ) in assembled condition with seal ( 3 ) lodged in place. As indicated above, the housing is disposed vertically with pressure-relief devices ( 4 ) at the bottom. Encircling seal ( 3 ) seals bottom part ( 2 ) of the housing against top part ( 17 ) of the housing. In the region of the pressure-relief devices ( 4 ), the seal is equipped in its outer part with a double-edged lip ( 5 ), as described above. This prevents ingress of dirty water from the outside, but permits pressure relief from the inside to the outside.  
         [0035]     As indicated above, lip ( 5 ) is fixed by at least one retaining pin ( 9 ,  10 ). Retaining pins ( 9 ,  10 ) can also be attached to top part ( 17 ) of housing ( 1 ).  
         [0036]     For pressure tests and also for air exchange, the bottom part of housing ( 1 ) is equipped with at least one breathing bore ( 15 ,  16 ) which opens in the region of lip ( 5 ). Breathing bores can also be provided in top part ( 17 ) of the housing.  
         [0037]     At least in the region of pressure-relief devices ( 4 ), housing ( 1 ) has one or more steps ( 20 ) structured and spaced relative to one another in such a way that they define a stepped gap or labyrinth structure between opposing sides. This labyrinth formation further inhibits the ingress of dirt into the region of lip ( 5 ).  
         [0038]     It should be appreciated that one or more boards for mounting electronic and/or mechatronic components can be disposed in the interior of housing ( 1 ).  
         [0039]     The functional principle of the inventive electronic or mechatronic housing will now be described in greater detail with reference to  FIG. 8 .  
         [0040]     Should an overpressure condition present itself in the interior of housing ( 1 ) due to a leak in a pneumatic line, for example, pressure can easily be released to the outside by squeezing elastic lip ( 5 ) together. In contrast, while lip ( 5 ) is spread apart, ingress of air in the opposite direction is prevented. Nevertheless, such ingress of outside air for breathing purposes is permitted by the breathing bores ( 15 ,  16 ).  
         [0041]     The labyrinth effect of housing ( 1 ) opposing ingress of dirty water is achieved because the water must first penetrate through the breathing bores ( 15 ,  16 ) into the space between lip ( 5 ) and bead ( 21 ). From there it can penetrate into the neighboring cavity only through the narrow gaps between retaining pins ( 9 ,  10 ) and perforations ( 7 ,  8 ). The water must then pass further through the perforations between protuberances ( 19 ) and then through a narrow gap ( 22 ) between the two housing halves in order to reach the interior space of the housing.  
         [0042]     The weight of the water that has penetrated in this way into the interior of housing ( 1 ) then acts on the two lips ( 5 ) provided at the lowest point of the housing in such a way that the lips are squeezed together and the water is again released into the surroundings. In this way, rapid drainage of the housing is achieved.  
         [0043]     Housing ( 1 ) can also be designed such that it has a frame-like middle part, which contains a board on which electronic as well as mechatronic components are mounted. On this middle part there can then be placed, as sealing members, the two housing halves or bottom part ( 2 ) and top part ( 17 ) shown in  FIG. 8 . In this case, seal ( 3 ) described hereinabove can be mounted on both sides of the middle part.  
         [0044]     Accordingly, the present invention provides a housing, especially for an electronic unit or a mechatronic unit, that is protected against the ingress of dirty water while, at the same time, permitting rapid pressure relief to atmosphere in the event of an overpressure condition in the housing.  
         [0045]     It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and since certain changes may be made in the above constructions without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.  
         [0046]     It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.