Abstract:
In a heat dissipating internally fan-less housing ( 20 ) for electronic circuits and components ( 28 ), the housing has an assembly of two container ( 10 ) parts comprising heat-sink fins ( 12 ). Each part has a substantially diagonal ( 14 ) shaped profile. In the housing, a circuit-board ( 29 ) is mounted along the diagonal ( 14 ) profile thus providing that the long-side ends of the circuit-board ( 29 ) on each side of the board are covered by a greater mass of heat-sink fins ( 12 ) compared to a horizontally mounted circuit board for a better cooling of components.

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The present invention pertains to a heat dissipating internally fan-less housing for electronic circuits and components. 
   2. Description of the Background Art 
   Current housings for electronic components are in excess of heat-sink fins provided with an internal fan for cooling of electronic components. A fan inside the housing imposes limitations to the dimension of the housing and how electronic components for instance on a printed circuit board (PCB) should be mounted to accomplish best possible heat dissipating features. Fans provide a disadvantage in having a mechanical cooling mechanism with moving parts thus having a much shorter life length than a heat sink passive cooling mechanism. 
   A limitation imposed to a housing for the intended purpose of being utilized for instance for routers and switches in a broadband network is set by a standard for mounting in a rack or cabinet. This standard stipulates a 19 inch (48.26 cm) wide housing, a height or vertical space of one rack unit (1U), 1.75 inches (4.45 cm) and a maximum depth of 30 cm. The standard thus sets out limitations making it hard to mount fans outside and on top of a housing. 
   Another limitation for such a housing is set out by the possibility to mount status indicators and console ports on a front panel of the housing. Present techniques admit a one row mounting of for instance indicator LEDs on the front panel. If a plurality of rows of LEDs or other interfaces are to be mounted this could be accomplished by providing them on a rear panel. Such a mounting is undesirable, because it is favorable to be able to actually see all status indicators on the front panel for maintenance, status reading purposes or other. Numerous by hand chassis mounted LEDs are expensive compared to for instance LCD displays, but such displays require more space for mounting on a front panel than is currently available. 
   In current technology a possible technique for achieving a front panel mounting with a plurality of rows of indicators comprises, for example, to put a main PCB board as far to the bottom of the housing as possible and to additionally connect smaller/daughter PCB cards above the main board and mounting those to the front panel and connecting the smaller boards to the main board via cabling. A cabled connection is vulnerable to come loose and imposes additional manufacturing costs. Another disadvantage for a cabled connection between two boards is directed to molding of parts, especially if the additional board is mounted on the front panel, for example, molding of circuit boards in a heat dissipating substance such as silicone compounds with different elasticity could impose stress on cable connections. Using a daughter PCB card for additional interfaces or LED indicators forces a main board to be mounted in the bottom of the housing. When using heat sinks for cooling this would not provide enough cooling on the bottom of the housing since there is little or no space left for heat sink fins. 
   One other obvious reason for not having status indicators on a rear panel is that a rack or cabinet is often placed close to a wall with the rear panels facing the wall, or if not placed in this manner the rack is covered by a housing of screw attached or riveted metal sheets on the rear of the rack. The housing thus aims to protect rack-mounted equipment from dust, humidity, dirt etc. Hence, present rack mounted equipment is maintained or changed by pulling it out from its rack position and replacing it with new or maintained equipment. 
   Also, to overcome manufacturing costs, it would be appreciated that one and the same tool can be used for pressing the top and bottom parts of a housing and still fulfill the 19 inches, 1U rack standard. 
   SUMMARY OF THE INVENTION The present invention aims to provide a solution to the above mentioned and other problems in relation to rack-mounted equipment. For this purpose the invention sets forth a heat dissipating internally fan-less housing for electronic circuits and components. The housing comprises an assembly of two container parts comprising heat-sink fins each part having a substantially diagonal shaped profile. These parts are assembled to form the greater part of the housing as being substantially box shaped by positioning the diagonal profiles to form the box shape. In the housing is mounted a circuit-board along the diagonal profile thus providing that the long-side ends of the circuit-board on each side of the board are covered by a greater mass of heat-sink fins for a better cooling of components compared to a horizontally mounted circuit board. 
   In one embodiment of the present invention the container parts that form the housing are spaced apart through spacing/distance pieces, and the pieces are designed to be able to penetrate through apertures made in the circuit board. 
   Another embodiment comprises that the apertures have at least fitting allowance to the spacing pieces. A further embodiment comprises that the housing is filled with a heat dissipating elastic substance. This embodiment provides that the circuit board is laying floating in the heat dissipating substance substantially free from touching the housing. The circuit board thus in addition to heat dissipation being protected against damage imposed to the housing. 
   A still further embodiment comprises that the mounting of the circuit board in addition to a better cooling enables the mounting of multiple indicators and/or at least one display on long-side panels attached to the housing. 
   Yet a further embodiment provides that the housing dimension is adapted within stipulated standard rack measures for a 19-inch, 1U rack. 
   A further embodiment provides that fastening means enable the mounting of the housing in a vertical position in a rack, thus taking advantage of the chimney effect for heat dissipation. 
   Yet another embodiment provides that one long side of the housing is made shorter then the stipulated standard of 48.26 cm to fit at least one fan, and thereafter equipped with a smaller housing at one short side in order to fill a 19-inch rack standard. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     Henceforth reference is had to the description and its accompanying drawings for a better understanding of the present invention with its given examples and embodiments, wherein: 
       FIGS. 1   a  and  1   b  are schematically illustrating a side elevation view of a bottom or top container for a housing, and a schematic perspective view of a diagonal profile for a container in accordance with the present invention, respectively; 
       FIGS. 2   a ,  2   b  and  2   c  are illustrating side elevation view, front elevation view and a bottom or top elevation view of an assembled box shaped housing in accordance with the present invention; 
       FIG. 3  is illustrating a circuit board with electronic components and apertures for spacing pieces in accordance with the present invention; 
       FIG. 4  is illustrating a spacing piece in accordance with the present invention; 
       FIG. 5  is illustrating a front panel to the housing in accordance with the present invention; and 
       FIG. 6  is illustrating a housing in accordance with the present invention for mounting in a rack. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   The present invention provides a housing/casing for electronic components, especially for a router or switch in a broadband network. The housing is provided heat-sink fins but no internal fan for cooling of the electronic components. 
   Moreover, the housing fulfills the standard set out for a rack/cabinet mounting, which stipulates a 19 inch (48.26 cm) wide housing, and the height or vertical space of one rack unit, 1.75 inches (4.45 cm). It also provides the possibility to mount status indicators, displays, connectors, other interfaces etc. on its front panel in excess of what is currently achievable. 
   Furthermore, the present invention in one embodiment provides one and the same tool for pressing a top and bottom container of the housing fulfilling the 19 inches, 1U rack standard. 
     FIG. 1   a  is schematically illustrating a side elevation view, the short side elevation, of a bottom or top container  10  for a housing in accordance with the present invention. The container  10  is provided with heat-sink fins  12 , and a diagonal profile  14 , i.e., the profile of a box if it is cut through along its short side diagonal from one long side to the other as schematically depicted in  FIG. 1   b . A container with a heat-sink fin  12  pattern could be manufactured by pressing aluminum in a tool. As is depicted in  FIGS. 1   a - 1   b  and  FIGS. 2   a - 2   c , with two containers  10  it is possible to assemble a box shaped housing  20  by positioning the diagonal profiles  14  to form the box shape. Two panels, one front panel  22  and a rear panel  24 , are utilized to accomplish the assembly of the box shaped housing  20 . 
   In  FIG. 1   a , it can be seen that the heat-sink fin  12  part close to the highest  16  elevation of the container  10  has a greater mass, which provides an enhanced cooling effect to electronic components mounted adjacent to those fins. 
     FIGS. 2   a ,  2   b  and  2   c  are schematically illustrating an assembled box shaped housing in accordance with the present invention through a side elevation view (in  FIG. 2   a ), a front elevation view (in  FIG. 2   b ), and a bottom or top elevation view (in  FIG. 2   c ). 
   Depicted in  FIG. 2   a  is a solid line  26  schematically showing how a circuit board ( FIG. 3 ) is diagonally mounted inside the housing  20 . Conventionally a circuit board is mounted horizontally with electronic components  28  protruding upwards providing an even distribution of heat-sink fins over the circuit board  29 . By employing the present invention, electronic components  28  placed on the circuit board adjacent to the front panel  22  benefit from a greater mass of heat-sink fins  12  which provides a better cooling effect to those components  28 . Heat intensive electronic components, such as FE ports/transceivers (FE; Fast Ethernet) in a router, are mounted adjacent to the front panel to have their indicators, connections and/or other known interfaces abutting, being flush to or protruding out off the front panel  22 . Further heat conductivity between the board  29  and the fins  12  can be established by applying for instance Bromancob GAP Pad material. 
   As mentioned, the utilization of a daughter PCB card for additional interfaces or LED indicators forces the mounting of a main board  29  to the bottom of the housing. When using heat sinks for cooling this would not provide enough cooling on the bottom of the housing  20  as there is limited space left for heat sink fins  12 . To obtain enough cooling area on both the top and bottom side of the housing, the inventive idea provided through one embodiment of the present invention is to place the circuit board  29  diagonally in the housing, thus providing enough heat sink cooling area on both sides of the housing. 
   The front panel  22  in  FIG. 2   b  is schematically depicted as equipped with FE ports/and transceivers. Additionally depicted in  FIG. 2  is a LCD display  30  replacing status indication through LED:S. Conventional routers/switches equipped with a horizontal placed PCB cannot provide an LCD display on the front panel  22  and at the same moment fulfill the 1U rack height of 4.45 cm, for example, due to lack of space taken by the horizontal placed PCB with its mounted electronic components. 
     FIG. 3  illustrates a circuit board  29  utilized for a router/switch in accordance with the present invention. The board is provided with apertures  30  in which spacing/distance pieces  40  ( FIG. 4 ) are to be housed. These spacing pieces  40  are abutting the two diagonally profiled containers  10  and fastened by screws, bolts or other suitable fastening means by utilizing through holes  42  in the spacing pieces  40 . The apertures  30  in the circuit board  29  are bigger than the diameter of the spacing pieces  40  with at least a fitting distance so that the pieces  40  are not holding the circuit board  29  in its place when the housing  20  is assembled. 
   To further enhance the heat dissipating features of the present invention all voids in the housing  20  are filled with a heat dissipating substance such as silicone used for this purpose. When the housing is filled with the heat dissipating substance, the circuit board so to speak “floats” in the substance inside of the housing  20  due to not being fastened directly to the containers  10  making up the housing  20 . Hence, the circuit board  29  is substantially free from touching the housing, and the circuit board thus in addition to heat dissipation being protected when the housing itself should be damaged.  FIG. 5  is depicting a front panel  22  to be attached to the housing  20  in accordance with the present invention with its apertures for FE ports/transceivers, display  30 , connectors, indicators, other interfaces etc. 
     FIG. 6  is illustrating a housing  20  fully equipped for mounting in a rack or cabinet in accordance with the present invention. The housing  20  has attached to it fastening means  60  for attachment in a rack. Furthermore, the housing is equipped with an aperture  62 , which is utilized for injection of a heat dissipating substance to fill out the voids inside the housing, and thus establishing the floating circuit board  29 . With the fastening means  60  it is possible to mount the housing  20  in a vertical position in a rack, thus taking advantage of the so called chimney effect as heated air dissipates upwards. If housings  20  in a rack were mounted horizontal, the heated air would so to speak get “stuck” between stacked housings. 
   In one embodiment of the present invention, it is provided that a fan can be mounted on one short side of the housing. The fans are then so attached that they convey airflow along the fins  12 , when desirable the airflow can be provided along the fins  12  both on the top and bottom containers  10 . To achieve this, one long side of the housing  20  is made shorter than the stipulated standard 48.26 cm (19 inches) with a suitable shortening such as for instance 1.3 cm shorter to fit at least one fan. In one embodiment the housing is assembled with a shorter long side, and thereafter equipped with a smaller housing at one short side in order to fulfil the 19-inch rack standard. When called upon, this smaller housing is able to house fans. In this manner the housing  20  is made very versatile an adaptable to different environmental conditions. 
   The present invention has been described through given examples and embodiments, but not intended to be limited to those. It is believed that the attached set of claims teaches other embodiments obvious for a person skilled in the art.