WO2014108119A1 - Electronic assembly comprising a housing with a pressure compensation element between the housing interior and the surroundings - Google Patents

Abstract

Disclosed is an electronic assembly comprising a housing with a pressure compensation element (2) between the housing interior (1) and the surroundings. The housing has a pressure supply conduit (3) with a first opening (3.1) to the interior of the housing, and the opening (3.1) is covered by the pressure compensation element (2) so as to be permeable to air, but impermeable to moisture. The pressure supply conduit also has a second opening (3.2) from the pressure supply conduit (3) towards the surroundings. However, especially in electronic assemblies in the field of motor vehicle technology, it cannot be ruled out that such an opening be struck by a pressurised water jet. Compared to the relatively low pressure difference in the air pressure, significant dynamic pressure can build up on the pressure compensation element (2) as a result of such a pressurised water jet. In order to avoid this, the pressure supply conduit (3) has at least one additional, i.e. third (3.3) opening to the surroundings that is separate from the second opening, and the first opening (3.1) is arranged at a distance both from the second and from the third opening (3.2, 3.3). The Venturi effect is exploited in the pressure supply conduit (3) by arranging the first opening (3.1) in a region with reduced cross-section.

Description

 Continental Automotive GmbH, Vahrenwalder Str. 9, 30165 Hanover

Electronic assembly having a housing with a pressure equalization element between the housing interior and the environment

The invention relates to an electronic assembly having a housing with a pressure compensation element between the housing interior and the environment according to the preamble of claim 1.

 Electronic assemblies, especially assemblies with a plastic housing, require a pressure compensation element in the housing, so that the pressure difference between the housing interior and the environment is not so large that moisture is sucked by the pressure difference from the environment into the housing interior. Especially for electronic assemblies in motor vehicles, the temperature differences are very high and the potential pressure differences not negligible. Accordingly, in the housing usually a pressure compensation element is present, which is formed for example by an air-permeable, but moisture-impermeable tissue membrane, for example. So-called Goretex ® (Goretex is a trademark of the company W. L. Gore & Associates, Inc). This membrane is usually adhered to the outside or inside of an opening in the housing and allows pressure equalization through this opening without moisture being able to penetrate through the opening.

 Disadvantage of this pressure compensation elements, in particular their bonding, but is the low stability against a strong spray or dynamic pressure, but how he can arise for example by pressure radiator for vehicle cleaning.

From DE 20 2008 005 548 U1 a pressure compensating screw with a tube membrane for electronics housing can be seen, in which a plurality of star-shaped arranged around a tube membrane pressure inlet openings are provided to the environment and inside the tube membrane, the opening into the interior of the housing is provided. Such an arrangement itself precedes a self-supporting tubular membrane of porous material and is unsuitable for a thin-membranous membrane. In a pressure jet test, the jet would always impinge directly on the tube membrane. The tube membrane is arranged in the chamber, which has a larger cross section with respect to the cross section of the openings towards the environment. EP 1 630 769 B1 discloses a label for covering gas exchange openings with a plurality of openings to the pressure inlet to the environment, wherein the label is additionally glued to the edge around the gas exchange opening. The channels for the gas exchange opening in each case have a constant identical cross-section and open above the gas exchange opening in a recess which opposite the flow direction for liquids radiated through one of the openings has a larger cross-section than the channels leading thereto.

 The object of the present invention is therefore to present an electronic assembly with a pressure compensation element, in which the pressure compensation element is even better protected against such loads.

 This object is solved by the features of the independent claims. Advantageous developments of the invention will become apparent from the dependent claims, wherein combinations and developments of individual features are conceivable with each other.

The housing thus initially has a pressure feed channel with a first opening to the interior of the housing. The pressure supply channel can also have a different function in addition to the function of the pressure compensation, for example, in pressure sensors and the supply of pressure to the arranged inside the housing pressure sensor serve. In the simplest case, the pressure feed channel has hitherto been designed as a bore in the housing in the prior art. This opening into the housing interior is air-permeable, but moisture-impermeable covered by the pressure-equalizing element, so for example protected by gluing such a membrane on the inside or outside of this opening. In addition, each pressure supply channel of course has a second opening from the pressure supply channel to the environment. The pressure compensation element is arranged in a pressure feed channel and to which the pressure supply channel has at least two openings to the environment, so that a water jet entering to an opening to the other opening can escape back to the environment and not to a complete blockage of the opening to the environment and This can lead to the blockage of the pressure compensation element. An essential idea of the invention is that the pressure feed channel has a reduced cross section transverse to the flow direction of liquids radiated through the openings in an area spaced from the openings to the environment and the inner opening is arranged in this area with reduced cross section, thereby physically seen a so-called Venturi element arises. It will be at the 1. Opening and thus exploited at the pressure compensation element of the Venturi effect, which in this area with reduced cross-section, although a significantly higher flow velocity, but a lower back pressure occurs. It should be pointed out that several directions are available for the reduction of the cross section and an optimization of the pressure feed channel is possible both with regard to a low flow resistance for the water jet and with regard to avoiding direct irradiation of the inner opening and the utilization of the Venturi effect ,

 Through the second and third opening, so the openings to the environment, or the course of the pressure supply channel creates a flow direction for radiated through one of the openings liquids. In this case, the first opening to this flow direction is preferably arranged at an angle other than zero or 180 degrees, preferably at least approximately at right angles (90 degrees).

 If, for example, one proceeds from a straight pressure feed channel, through which a water jet can flow from the second to the third opening or vice versa, then one of them, spaced apart and angled, preferably right-angled, outlet of FIG. Opening a measure by which a before or behind this 1. Opening arranged pressure compensation element is particularly effectively protected by the mechanical influence of the water jet.

 Preferably, moreover, the position of the first opening in the pressure feed channel is arranged so that a water jet can not impinge directly on the first opening either on entry through the second or through the third opening. For this purpose, in addition to the distance between the openings and their opening diameter or the angular orientation and the course of the pressure supply channel contribute.

In a particularly preferred embodiment, the pressure feed channel is at least substantially rectilinear, that is, the flow direction of a radiant water jet through the one opening to the environment is identical or at an angle smaller than 45 ° to the flow direction of the water jet flowing through the other opening. In addition, a projection of the second opening in the plane of the third opening overlaps each other at least partially, so you can see through the pressure supply channel. Thus designed Druckzuführungskanal thus has a water jet hardly resistance and effectively prevents the build-up of a back pressure before the pressure compensation element.

 In some embodiments, however, it is not possible to design the pressure supply channel in a straight line and to provide openings on both sides. Alternatively, it is proposed for such cases that the pressure feed channel then has at least one bend or kink, but also there means for deflecting a water jet from the second to the third opening and vice versa and the first opening spaced from the center of the bend or the kink is arranged. The means for deflecting the water jet may, for example, be a bend with a sufficiently large bending radius or a kind of deflection surface or deflection surface, which is preferably perpendicular to the bisecting line between the flow direction in the second opening and the flow direction in the third opening. If, for example, the flow direction s between the second and third openings are arranged at an angle of 90 ° to one another, such a deflection surface would be directed at 45 ° to each of these two directions of flow.

 This means that in turn the water jet can flow without major obstacle from the third opening to the second opening or vice versa, without causing a major backwater. In addition, the 1. Opening not arranged in this area of the deflecting means, but slightly spaced.

 The invention will now be explained in more detail by means of exemplary embodiments with the aid of the figures. Show it

 Figure 1: 1. preferred embodiment.

 Figure 2: section through the channel

 Figure 3: 2nd preferred embodiment

 Figure 4: 3rd preferred embodiment

 Figure 5: Sketch of an alternative means for deflecting the water jet

 Figure 6a / b sketches of the positions of the projection of the openings in a plane

 Figure 7: Sketch of a preferred reduction of the cross section 3.5

Figure 8: Sketch of another embodiment as a sectional view FIG. 9: top view of the exemplary embodiment according to FIG. 8

 In the following, functionally identical and / or identical elements may be designated by the same reference numerals. Thus, the housing interior is denoted by 1, with 3 of the pressure supply channel with 2 the pressure compensation element and with 4 the housing wall to the pressure supply channel third

 The housing has a pressure feed channel (3) with a first opening (3.1) to the interior of the housing, said opening (3.1) through the pressure compensation element (2) permeable to air, but is covered moisture impermeable. It is irrelevant whether the pressure compensation element 2 is arranged in the housing interior 1 or within the pressure supply channel 3. The pressure compensation element 2 is for example a membrane which is glued to the edge of the opening 3.1. The pressure compensation element 2 is permeable to air and thus allows an air flow A, through which a pressure equalization between the environment and the housing interior 1 is possible. The practically occurring pressure differences in the air pressure are relatively low compared to the pressure which can arise on the pressure compensation element 2, when water is injected into one of the openings 3.2 and 3.3 in the pressure supply channel by means of a pressure jet. Especially in the field of motor vehicles and electronic components thereof, however, it can not be ruled out that such a strong jet of water impinges on the openings 3.2 or 3.3 in a washing line or manually by means of a high-pressure cleaner. Since water is impermeable to the pressure compensation element 2, a considerable overpressure and destruction of the pressure compensation element 2 could theoretically occur in conventional arrangements according to the prior art. To avoid this, it is provided that in addition to the second opening (3.2) from the pressure supply channel (3) to the environment of the pressure supply channel (3) has at least a third (3.3), from the second separate opening to the environment and the first opening (3.1) spaced is arranged from both the second and third opening (3.2, 3.3). The third opening is therefore also spaced from the second opening. Through the second and third openings, a flow direction (W) is or is defined for liquids radiated through one of the openings.

Figure 1 shows a first preferred embodiment in which the first opening (3.1) to this flow direction (W) at an angle other than zero or 180 degrees, preferably at least approximately at right angles (90 degrees) is arranged. The position of the first opening (3.1) is also arranged in the pressure supply channel 3 so that a water jet can not impinge directly on the pressure compensation element 2 either on entry through the second or through the third opening (3.2, 3.3). It is understood as direct if the beam could strike without any distraction. Each deflection or reflection through the wall of the housing around the pressure feed channel absorbs part of the energy of the jet and protects the pressure compensation element 2.

 However, in FIG. 1, moreover, the pressure feed channel 3 is arranged in a straight line and completely overlaps a projection of the second opening into the plane of the third opening.

 A water jet, which penetrates through one of the openings (3.2, 3.3), also leaves the pressure feed channel 3 again directly through the opposite opening, so that no or only a significantly reduced tendency to build up a dynamic pressure is to be expected in the opening 3.1. The pressure compensation element 2 is therefore very well protected.

 However, the embodiment according to FIG. 1 nevertheless makes it possible to use the particularly preferred Venturi effect, according to FIG. 2, in a region spaced from the second and third openings, a reduced cross section (3.5) transversely to the flow direction (W) of FIG Having liquids radiated by the second or one of the third openings (3.2, 3.3) and the first opening (3.1) is arranged in this area with a reduced cross-section (3.5).

The Italian Giovanni Battista Venturi discovered that the flow rate of an incompressible fluid flowing through a pipe is inversely proportional to a changing pipe cross-section. That is, the velocity of the fluid is greatest where the cross-section of the tube is smallest. As a consequence, however, the pressure of the fluid in the region of the reduced tube cross section is also lower than before this constriction. This named after him Venturi effect (see Wikipedia) is used for example for nozzles. In the present application, a corresponding reduction of the cross-section 3.5 and arrangement of FIG. 1 provides. Opening in this area to the fact that the pressure on the pressure compensation element 2 is in any case lower than the pressure radiated by the externa ßeren openings 3.2 and 3.3 respectively. For the Venturi effect itself is irrelevant in what form and direction of the cross section 3.5 of the pressure supply channel 3 is reduced. In FIG. 2, in accordance with FIG. 1, a reduction purely in the Y direction is shown. Figure 3, however, shows a different design, which also uses the Venturi effect, but also by reducing the cross section 3.5 on the side facing the opening 3.1 side of the pressure supply channel 3 additional protection of the opening 3.1 and the pressure compensation element 2 against direct impingement of the beam allows.

 FIG. 7 shows yet another sketch of an embodiment of the reduced cross section 3.5 in both the X and Y directions using the Venturi effect.

FIG. 4 now shows a further embodiment in which the openings 3.2 and 3.3 are again aligned in the same direction on opposite sides of a straight tube but are arranged at an angle other than zero or 180 degrees, preferably at least approximately at right angles (90 degrees). Thus, the flow direction (W) for liquids radiated through one of the openings in the region of the second opening 3.2 deviates from the flow direction in the region of the third opening 3.3. This exemplary embodiment thus does not allow a straight-line water flow as in FIG. 1. However, in practice, it is not always possible to provide an assembly with such a rectilinear pressure feed channel. Nevertheless, it is possible to provide a third opening and a back pressure formation in the area of 1. Opening 3.1 to avoid. The pressure feed channel 3 thus has at least one bend or kink. Preferably, however, there are means (3.4) for deflecting a water jet from the second to the third opening (3.2, 3.3), ie in the region of the bend or bend. In addition, the first opening (3.1) is arranged at a distance from the center of the bend or the bend. In FIG. 4, a kind of deflection surface or deflection surface 3.4 is provided as such means for deflecting the water jet, which is at least approximately perpendicular to the bisector of that angle which through the flow direction W in the region of the second opening 3.2 to the flow direction W in the region 3. opening 3.3 is clamped. Thus, if the openings 3.2 and 3.3 are arranged at an angle of approximately 90 ° to one another, as shown in FIG. 4, the deflection surface 3.4 would be arranged at an angle of 45 °. Alternatively, of course, a curvature with a correspondingly large bending radius can be provided in this area, as indicated in sketchy way in Figure 5. The aim of these measures is in each case the deflection of the water jet without excessive increase of the dynamic pressure before the 1st Opening 3.1. Accordingly, this is 1. Opening 3.1 also preferably not provided in the region of these means for deflecting the water jet. FIGS. 6A and 6B outline what is to be understood by a projection of the second opening into the plane of the third opening, wherein a definition of a pressure feed channel 3 is defined as at least substantially rectilinear, which at least partially overlaps such a projection, such as by the attenuated Surfaces in Figure 6A and 6b to be shown.

 Optimally, the openings even completely overlap, as sketched in FIG. However, a small offset or a certain bend in the pressure feed channel 3 does not lead to any impairment of the effect.

 Figures 8 and 9 now outline yet another practical embodiment of the implementation of the invention in an existing assembly in which the operation of the invention could be tested in the originally provided pressure feed channel 3 adjacent to the opening 3.2 through a further hole 3.3. Opening angle and distance of the opening 3.3 with respect to the position of the first Opening 3.1 are limited here because of the spatial requirements of the assembly and since not optimal, thereby the opening 3.3 is still a direct irradiation of the opening 3.1 is possible. A more spaced arrangement would be preferable, but was not feasible here because of the formations in the housing of the assembly. Nevertheless, this embodiment also shows the basic idea of the invention and the derivation of a water jet flowing through the opening 3.2 through the third opening 3.3 and also the Venturi effect explained above is used and a corresponding area with a reduced cross-section is used, although this is shown in FIGS nciht is sketched closer.

 It should be noted that the invention already works when providing a third opening 3.3 works, but quite possible applications are conceivable in which a plurality of such further openings are provided, for example, arranged in a star shape.

Claims

claims 1) Electronic assembly with a housing with a pressure compensation element (2) between the housing interior (1) and the environment, wherein the housing has a pressure feed channel (3) with a first opening (3.1) to the interior of the housing and this opening (3.1) through the pressure compensation element (2) permeable to air, but is covered moisture impermeable and a second opening (3.2) from the pressure feed channel (3) to the environment, the pressure feed channel (3) having at least a third (3.3) from the second separate opening to the environment and the first opening (3.1) spaced from both the second, as also third opening (3.2, 3.3) is arranged, a flow direction (W) for liquids introduced through one of the openings is formed by the second and third openings, and the pressure feed channel has a reduced cross-section (3.5) transversely to this flow direction (W) in a region spaced from the second and third openings, and the first opening (3.1) is arranged in this region of reduced cross-section (3.5). 2) Electronic assembly according to claim 1, characterized in that the first opening (3.1) to this flow direction (W) in a different from zero or 180 degrees angle, preferably at least approximately at right angles (90 degrees) is arranged. 3) Electronic assembly according to one of the preceding claims, characterized in that the position of the first opening (3.1) in the pressure supply channel and the pressure compensation element (2) are arranged so that a water jet at least when entering through the second opening (3.2.), Preferably even when entering through the third opening (3.3) can not directly impact directly on the pressure compensation element (2). 4) Electronic assembly according to one of the preceding claims, characterized in that the pressure supply channel is at least substantially rectilinear, so a projection of the second opening in the plane of the third opening at least partially overlap each other (streamlined surfaces in Figure 6A and 6b). 5) Electronic assembly according to one of the preceding claims 1 to 3, characterized in that the pressure supply channel (3) at least one bend or kink and there means (3.4) for deflecting a water jet from the second to the third opening (3.2, 3.3 ) and vice versa and the first opening (3.1) spaced from the center of the bend or the Knicks is arranged.