Patent Application
20150264829
The invention relates to an electronic assembly with a housing having a plastic part and a metal part, which together enclose an interior space of the housing, in which at least one electronic component is arranged, for example on a circuit board. The housing has a mounting flange or mounting lug by which the electronic assembly is mechanically mounted on an external support structure.
Known electronic assemblies comprise a housing that is typically a two-part housing including a main housing body or container that bounds an inner space therein, and a lid or cover that closes at least one side of the main housing body or container. Thus, electronic components arranged in the inner space of the housing are preferably entirely surrounded and enclosed by the housing, which is preferably also sealed, in order to protect the electronic components from the outside environment (e.g. water, moisture, dust, etc.). Such housed electronic assemblies are especially known, for example, in the field of automobile electronics, where the housing protects the electronic components from the harsh operating environment within the engine compartment of the automobile, for example. In order to reduce the weight, the manufacturing cost, and the assembly and installation cost, it is becoming increasingly common to use housings that comprise a plastic part, e.g. a main housing body or container made of plastic, and a metal part, e.g. a metal lid or cover for the plastic housing part.
It is further known to provide an electrical ground connection for such an electronic assembly via a metal insert part that is injection molded in the plastic material of the plastic housing, for example as disclosed in German Patent Publication DE 197 42 458 A1. The metal insert part is provided on a mounting flange or lug and is secured on a metal carrier or support structure via mechanical fastener or connection means. Furthermore, the metal insert part has an electrical connection into the interior of the housing and is there connected with a ground contact on the circuit board of the electrical components. However, the manufacturing of such a housing with a metal insert part injection-molded into the plastic material of the housing is expensive and complicated.
The German Utility Model Publication DE 201 12 595 U1 discloses an electrical ground connection via metallic bushings in the mounting flange of a housing, in which the circuit board of the electronic assembly extends outwardly into the mounting flange and there contacts the metal bushings. However, due to the high forces that arise in the mounting flange during the mounting (e.g. screwing or bolting) thereof onto a support structure, or during the driving operation of the motor vehicle in which the electronic assembly is installed, there is the danger that these high forces are transmitted directly into the circuit board at the location of the mounting flange, and the circuit board may thereby be damaged.
It is also known to provide a metal adapter plate for securing a housing in a motor vehicle, for example as disclosed in German Patent Publication DE 10 2009 045 565 A1. In that known arrangement, the mounting flange or mounting lug is formed directly on this adapter plate itself. Therefore, the adapter plate must have a considerable thickness in order to have sufficient strength to take up and withstand the arising mechanical forces of the mounting flange.
The US Patent Application Publications US 2011/0170269 A1 and US 2012/0261409 A1 disclose electronic assembly housings as well as suitable manufacturing methods, in which lugs extend from the metal lid into the mounting flange of the plastic housing. The metal lid including the protruding lugs thereof are constructed and formed to provide structural support and carry mechanical loads. As a result, mechanical vibrations, for example as arise in a motor vehicle especially when driving on uneven or bumpy streets, are transmitted through the mounting points via the metal lid directly to the circuit board, where the transmitted mechanical forces and vibrations disadvantageously load or even entirely destroy solder connections, electronic components, sensors or the like on the circuit board.
In view of the above, it is an object of an embodiment of the invention to provide an improved electronic assembly with a housing that provides an electrical ground connection, substantially protects or isolates the circuit board and electronic components mounted thereon from mechanical forces or vibrations that arise at the mounting points, and that can be produced, assembled and installed simply and economically. The invention further aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification. The attainment of these objects is, however, not a required limitation of the claimed invention. The above objects can be achieved in an electronic assembly and/or a housing for an electronic assembly according to an embodiment of the invention. For example, such an electronic assembly comprises a housing and electronic components mounted therein. The housing comprises a plastic part, for example including a main plastic housing body or container, and a metal part, for example including a metal cover or lid. Together, the plastic part and the metal part substantially, and preferably completely, enclose the electronic components within an interior space of the housing. The plastic part further has at least one mounting flange or mounting lug by which the electronic assembly is mechanically mounted on an external metal support structure, such as a metal support bracket or a metal component of a motor vehicle frame, body, engine, etc. (alternatively and equivalently, the support structure need not consist of metal, but may be made of plastic, composite material, ceramic, etc. with a metalized surface layer or a metal conductor thereon). The metal part further includes at least one grounding tab that protrudes from a main body or lid of the metal part. The grounding tab is configured and arranged generally along or aligned with or in registration with the mounting flange or mounting lug of the plastic housing part. Within the housing, the metal lid is electrically connected to a ground contact of one or more electronic components of the assembly, and outside of the housing the grounding tab is contacted and electrically connected with the metal support structure, between the mounting flange or lug and the support structure.
In further preferred embodiments, the metal part is purposely configured and arranged so as to substantially isolate mechanical forces and vibrations between the mounting points and the circuit board or electronic components within the housing. Preferably, the metal part provides no (or no significant) mechanical structural support for the circuit board or the electronic components within the housing, or for mounting the assembly on the external structural support. Instead, such mechanical and structural support is provided only (or substantially only) by the plastic housing part. Each grounding tab includes a connection portion in alignment or registration with the mounting portion of a mounting lug of the plastic part, and a transition portion or neck that extends from the connection portion to the main body or lid portion of the metal part. The connection portion establishes the electrical grounding connection to the support structure. The transition portion or neck serves as an electrical grounding path, and serves to isolate external mechanical forces or vibrations from the main body or lid portion of the metal part and the electronic components contained in the housing. In this regard, respective embodiments of the assembly according to the invention have at least one force or vibration isolating feature as follows.
For this purpose, the transition portion may have a narrower width than the connection portion of the grounding tab, and/or the transition portion may have a thinner thickness than the connection portion of the grounding tab or than the main lid portion of the metal housing part, and/or the transition portion may have a thickness of at most 2 mm, and/or the transition portion may include a bent portion with at least one bend or deflection adjoining the main portion of the metal part or adjoining the connection portion. The bent portion has at least one or preferably two or more bends or deflections out of a plane on which the transition portion and/or connection portion lie. The bent portion may thus have a serpentine or zig-zag or Z-shaped or U-shaped configuration with at least two or more deflections or bends. The transition portion having a narrower and/or thinner configuration than the connection portion may form a predetermined bending location or even a predetermined breaking location to protect the assembly from the transmission of excessive mechanical forces or vibrations. Any individual one of the above special features of the grounding tab can be included individually in a respective single embodiment, or can be combined in an embodiment that has two or more or all of these features. Each one of these features serves to isolate and minimize the transmission of mechanical forces and vibrations from the connection portion of the grounding tab to the main body or lid panel of the metal part. Thereby, the transmission of mechanical forces and vibrations to the electronic components within the housing is minimized.
Another feature by which the metal part does not provide significant mechanical structural support, and instead isolates and reduces the transmission of mechanical forces and vibrations, is that the overall metal part is very thin, for example having a maximum thickness no more than 2 mm thick, preferably no more than or less than 1 mm thick, and more preferably from 0.5 mm to 0.6 mm thick. Such a very thin metal part is too thin to provide mechanical structural support, and instead is easily elastically bendable or deflectable so as to prevent or isolate the transmission of mechanical forces and vibrations. Because the metal part is very thin and thus not very robust or sturdy, it may be further reinforced and protected in further embodiments. Namely, in one embodiment, the main body portion or lid panel of the metal part is stiffened by embossed or press-molded stiffening ribs, simply to provide the lid panel with sufficient stiffness to support itself in a flat planar condition. In another embodiment, the connection portion and optionally the transition portion of each grounding tab of the metal part is recessed in a correspondingly shaped recess of the associated mounting lug of the plastic housing part, such that all edges of the metal grounding tab are surrounded and covered by a plastic perimeter wall of the plastic part. The main body portion or lid panel of the metal part may similarly be received in a recess of the plastic housing part, whereby the perimeter edges of the metal lid panel are also surrounded by a plastic perimeter rim wall of the plastic housing. Thereby, the thin metal part, and especially the thin grounding tab thereof, is protected against mechanical damage before and during mounting thereof. Once mounted, the metal part is completely covered and enclosed by the plastic part. These embodiment features can be combined with one another, or included individually in respective embodiments, and/or combined with any one or more of the force-isolating features mentioned above.
Embodiments of the invention thus provide an advantageous combination of several features. The metal part and the plastic part of the housing together surround and enclose the interior space of the housing, in which the electronic components are housed and preferably entirely surrounded and enclosed, most preferably in a sealed manner. Furthermore, the plastic part mounts the housing on an external support structure, while the metal part of the housing provides an electrical ground connection for the electronic components to the support structure on which the electronic assembly is mounted. To establish the electrical connection of the grounding tab with the metal support structure, the grounding tab is received and clampingly held between the mounting lug of the plastic housing part and the metal support structure, or between the mounting lug and the fastener or securing means by which the assembly is secured to the support structure. Thereby, the need for a separate additional insert part (e.g. a metal part that is inserted and injection molded in the plastic housing part) is avoided. Furthermore, the metal part is configured and constructed so that the grounding tab or tabs thereof are substantially mechanically de-coupled from the rest of the housing so as to isolate or minimize the transmission of mechanical forces and vibrations from the mounting locations into the main portion of the metal housing part. This is achieved, as mentioned above, by any one or more of the following features: a reduced width of the transition portion relative to the connection portion of the grounding tab, a reduced thickness of the transition portion relative to the connection portion of the grounding tab, a thickness of the transition portion of not more than 2 mm, and/or a bent portion having one or more bends or deflections out of a plane of the connection portion or transition portion of the grounding tab.
The mechanical mounting forces and any arising vibrations are supported by the plastic housing part, and particularly by the mounting flange or mounting lugs of the plastic housing part mechanically secured to the support structure, for example a mounting bracket or other rigid part of a motor vehicle. Because the metal part does not need to withstand any significant mechanical loading, it may be made of a rather thin sheet metal, e.g. of at most 2 mm thickness. Thereby the metal part is lighter in weight and more economical to produce.
To further protect the metal part, e.g. the metal lid, of the housing from mechanical forces and influences, the entire metal part is preferably recessed or set into a corresponding recess in the plastic part of the housing, and preferably entirely circumferentially surrounded or enclosed by a perimeter rim or wall of plastic housing material.
In order that the invention may be clearly understood, it will now be explained in further detail, in connection with example embodiments thereof, with reference to the accompanying drawings, wherein:
For mounting the housing on an external support structure 6 (see
The metal part 1 of the housing is configured as a metal cover or lid in the present embodiment, and includes a main body or lid panel 1.3 and at least one, but in the present embodiment three, grounding tabs 1.1 protruding laterally outwardly from the lid panel 1.3 of the metal cover 1. Preferably, the entire plastic part 2, including the main body or container of the plastic housing and the mounting lugs 2.1, is integrally formed as a one-piece component of plastic, for example by injection molding. Similarly, the metal part 1 including the main body or lid panel 1.3 as well as the grounding tabs 1.1, is formed as a single one-piece metal component of thin sheet metal, for example by stamp-cutting and stamp-forming or drawing.
The grounding tabs 1.1 are generally aligned or in registration with the mounting lugs 2.1 of the plastic housing part 2, and arranged thereunder, so that in the mounted state, these grounding tabs 1.1 are received between the mounting lugs 2.1 and the metal support structure 6. Thereby, when the mounting lugs 2.1 are mechanically secured to the support structure 6, the grounding tabs 1.1 become electrically conductively connected to the support structure 6 without requiring additional steps or efforts for grounding.
A mounting location of the electronic assembly in the mounted or installed arrangement is shown in detail in an enlarged sectional view in
The mounting sleeve 2.2 as shown in
The mounting arrangement shown in
Namely, embodiments of the invention aim to isolate or reduce the transmission of mechanical forces and vibrations into the metal housing part 1, so that the metal housing part 1 can be made weaker, and thereby thinner and lighter, and thus more economically, while also protecting against vibrations, the electronic components contacted on the metal part 1 inside the housing, and while still providing an electrical grounding connection to the external support structure 6. As shown in
While it is sufficient that only one of the depressions 1.2 of the metal part 1 makes electrical contact with a ground conductor 7.1 of the circuit board 7, and only a single grounding tab 1.1 is provided to establish the electrical grounding connection to the support structure 6, it can be preferred to provide plural depressions 1.2 making electrical grounding contact with the circuit board 7, and plural grounding tabs 1.1. This arrangement provides redundancy in the electrical grounding connection, and/or permits variable mounting configurations in which at least only one of the available plural grounding tabs 1.1 must be secured to a grounded/metal support structure, while the other mounting tabs and mounting lugs may be secured to ungrounded support members.
The metal part 1 is preferably formed from sheet metal with a thickness of at most 2 mm, preferably not more than 1 mm or even less than 1 mm, and especially preferably from 0.5 mm to 0.6 mm. The metal part 1 can be formed by stamp-cutting and stamp-forming or drawing the sheet metal to form the contoured shape of the part including the depressions 1.2, the special configuration of the grounding tabs 1.1, as well as stamped or embossed stiffening ribs 1.4 that stiffen the main body or lid panel 1.3 of the metal part 1 to be self-supporting. Thereby, the entire metal part 1 is embodied as a single one-piece component of sheet metal as is shown and will be described in further detail with reference to
As can be seen in
The reduced width and/or thickness of the transition portion may form a predetermined bending location or even a predetermined breaking location of the grounding tab, which will bend or break if the grounding tab is exposed to excessive forces or vibrations, thereby preventing such excessive forces or vibrations from being transmitted to the main body 1.3.
Particularly, for example, the transition portion 1.1.2 may have a width B1.1.2 that is at most 80%, or preferably at most 75%, or more preferably at most 70%, or at most 65%, or at most 60%, or at most 50% of the width B1.1.1 of the connection portion 1.1.1. The transition portion 1.1.2 may have a thickness, for example, that is no more than 80% or no more than 75% of the thickness of the connection portion 1.1.1 or of the main body 1.3. The entire grounding tab 1.1 or only the transition portion 1.1.2 may be thinner than the main body 1.3
Furthermore, alternatively or additionally, the transition portion 1.1.2 may comprise a bent portion 1.1.3 having at least one bend or deflection, or preferably at least two bends or deflections, out of a plane of the connection portion 1.1.1 or of a main part of the transition portion 1.1.2. Each one of these features (reduced width, reduced thickness, or at least one bend), or any combination of one or more or all of these features, serve to de-couple the connection portion 1.1.1 from the main body 1.3 of the metal part 1 with respect to the transmission of mechanical forces and/or vibrations.
While the bent portion includes at least one bend or deflection 1.1.3 in the transition portion 1.1.2 of the grounding tab 1.1, it preferably includes at least two bends or deflections, thereby forming a Z-shaped, or U-shaped, or zig-zag or serpentine configuration (for example in a sectional side view as shown in
By providing a feature wherein the transition portion has a reduced width compared to the connection portion, and/or the transition portion has at least one out-of-plane bend, thereby the reduced width and/or the bend serve to reduce a strength or stiffness of the grounding tab relative to a condition without such a reduced width (e.g. a comparative grounding tab having a transition portion and connection portion with the same uniform width) and/or without such a bend (e.g. a comparative grounding tab having a flat planar configuration). This helps to ensure that no significant or no substantial mechanical forces and/or vibrations are transmitted through the transition portion 1.1.2 into the main body or lid 1.3
The feature that no significant or no substantial mechanical forces and/or vibrations are transmitted through the transition portion 1.1.2 into the main body or lid 1.3, may mean that the plastic housing 2 and particularly the plastic mounting lugs 2.1 carry at least 80% or at least 90% or at least 95% (or even more) of the total mechanical forces and vibrations arising at the mounting locations of the mounting lugs secured to the support structure(s), or in other words the transition portions 1.1.2 transmit at most 20% or at most 10% or at most 5% (or even less) of the total mechanical forces and vibrations. Another way to consider this, is that at each mounting location, the mounting lug 2.1 carries at least 90% or at least 95% (or even more) of any bending force acting on the combination of the mounting lug 2.1 and the grounding tab 1.1, as exerted by the support structure 6 relative to the housing at the respective mounting location.
The isolation of forces is also improved because the overall metal part 1 is quite thin, as described above. But to ensure that the metal part 1 and especially its main body or lid panel 1.3 is nonetheless sufficiently self-stable in a generally flat planar configuration, and does not sag, bend or vibrate excessively, the main body 1.3 is provided with stiffening ribs 1.4. The stiffening ribs 1.4 only provide sufficient stiffness to make the metal lid flat and self-supporting, and do not provide sufficient mechanical strength for taking on a mechanical supporting function of the entire housing or the circuit board. Also in this regard, to stiffen the thin main body 1.3 of the metal part 1, it is formed with a slightly tub-shaped configuration in which a preferably continuous perimeter rim or wall 1.5 protrudes upwardly from the lid panel or main body 1.3. In
Because the metal part, i.e. the metal cover or lid 1, is quite thin and mechanically not strong, it is preferred to protect the metal lid 1 by substantially enclosing it around its perimeter by the plastic housing part 2. Namely, the metal part 1 does not protrude outwardly from or beyond the plastic housing part 2. Instead, the metal part 1 is received in a recess 2.1.2 at the open end of the plastic housing part 2, such that preferably the entire perimeter edge of the metal part 1 is surrounded and covered by a plastic perimeter rim or wall 2.1.1 of the plastic housing part 2, whereby the thin (and mechanically weak or damage-sensitive) metal part 1 is laterally covered and protected by the plastic housing part 2. This can be seen especially in
Furthermore, the main body or lid panel 1.3 of the metal cover part 1 being received in the recess of the main body of the plastic housing part 2 may preferably have a guiding and/or engaging function when the metal part 1 is inserted into the open end of the plastic part 2 to close the housing. In this regard,
Although the invention has been described with reference to specific example embodiments, it will be appreciated that it is intended to cover all modifications and equivalents within the scope of the appended claims. It should also be understood that the present disclosure includes all possible combinations of any individual features recited in any of the appended claims or in the disclosure of this application. The abstract of the disclosure does not define or limit the claimed invention, but rather merely abstracts certain features disclosed in the application.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2013 224 588 | Nov 2013 | DE | national |
This application is a Continuation-In-Part (CIP) under 35 USC 111(a) and 120 of PCT International Application PCT/DE2014/200600 filed on Oct. 28, 2014. Through the PCT application, the present application also claims priority under 35 USC 119 of German Patent Application DE 10 2013 224 588 filed on Nov. 29, 2013. The entire disclosures of the priority application and the PCT application are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/DE2014/200600 | Oct 2014 | US |
| Child | 14724237 | US |
