Abstract:
The invention regards a casing for an electronic device, such as a computer or especially a server. The casing has on its top a recess in which a modular fan unit can be inserted. The fan unit is a further element of the invention and serves for cooling the inner components in the casing by producing an air flow through it. For this purpose it comprises several fans. The casing and the fan unit are constructed for easy accessability of the inside of the casing, optimized air flow and handling.

Description:
FIELD OF APPLICATION AND PRIOR ART 
     The invention relates to a casing for an electrical device, particularly an electronic device or a computer, having a fan unit for producing an air flow in at least a part of the casing. 
     Normally heat builds up in electrical or electronic devices such as computers, as a result of components thereof and must be dissipated in order to avoid overheating. In particular, computer processors must be cooled in order to avoid malfunctions or damage. It is known to fit to a casing of the aforementioned type, generally to its rear wall, a fan unit, which is directed into the casing. As such fan units are generally internally screwed to the casing, replacement is only possible with considerable difficulty. 
     SUMMARY OF THE INVENTION 
     The problem of the invention is to provide a casing with a fan unit according to the preamble of claim  1 , in which the fitting of the fan unit is improved. 
     This problem is solved by the features of claim  1 . A fan unit insertable from the outside and secured in a casing recess within the casing or device can be easily and rapidly replaced, particularly without it being necessary to open or remove the entire casing. The inserted fan unit can at least substantially and in particular completely project into the casing or device. The fan unit can be located in a recess or a free space within the casing. The distance from further device components contained in the casing can differ as a function of the fan unit used and can in particular be very small. 
     Preferably the fan unit has at least one electromotive fan and preferably several fans. Several fans can be arranged in a group or at least two fans can be axially juxtaposed. In certain circumstances the fan unit can be detachably secured in the casing in a very simple manner. In the case of insertion from above into the casing, one possibility consists of a mounting support with stop action substantially solely on the basis of the weight of the fan unit. The fan unit is preferably lockable by a nonpositive connection, particularly by locking means. On inserting the fan unit into the casing said locking means can be automatically activated, particularly at the end of the insertion path. 
     Advantageously there is a locking nose on the casing and a corresponding locking receptacle on the fan unit, particularly in order to simplify a replacement off a defective locking receptacle on the accessible fan unit. 
     The fan unit is preferably detachable from the casing and is preferably completely detachable or separable. For the electrical supply of the fan unit it is possible to provide a plug connection in the casing and on the fan unit. Advantageously there is a plug coupling, particularly with contacts over which project an envelope, in the casing and a plug on the fan unit. According to ain embodiment the plug connection can be positioned laterally in the casing, preferably on a lateral face. It can in particular be substantially located at the beginning of an insertion path for the fain unit, in order for better centering of the plug connection. Preferably the plug coupling in the casing has some room to move for easier insertion of the plug on the fan unit. A plug connection can form part of the locking means for fixing the fan unit. It is also possible to construct a plug connection as part of guidance means for a positionally correct mounting of the fan unit in the casing. 
     In the vicinity of the recess the casing can have a guide device for the fan unit on insertion into the casing. The guide can be a system of guide rails and guide receptacles, the guide rails preferably being on the fan unit, e.g. in the form of elongated projections. Advantageously the lateral edge of the fan unit, particularly a fain or its casing, can be part of the guide rails, the casing being provided on the inside with a corresponding, preferably U-shaped guide receptacle. 
     The fan unit, particularly also the recess, can advantageously extend over a significant part of at least one extension direction of the casing and preferably perpendicular both to the insertion direction and also to the axial direction of the fan or the air flow produced. In this way an air flow can be produced, which moves substantially through the entire casing or its cross-section. The fan unit can in particular extend over a plane perpendicular to the axial direction and takes up a main part of cross-section. It preferably takes up about 80% of the width and about the same of the height. It is possible to install at least one separate channel in the casing running in its longitudinal direction. In one such channel under the fan unit a power unit or several power units can be accommodated. Such a channel can take up less than the entire length of the casing, for example start near the fan unit. The channel in this case can advantageously be made up of a sheet material with special characteristics regarding EMR (electromagnetic resistability) requirements. In this way it is possible to protect the rest of the casing from the electromagnetic radiation of the power unit. The power unit can be provided with its own ventilation, especially an in-built air fan. A preferred place for a power unit is near or on the back side of the casing. 
     The aeration for the casing and for the power unit can be partly together along the same path. Especially an aeration stream can enter the casing on the front side, then be parted and run on one hand through the fan unit and on the other hand enter the separate channel under the fan unit with the power unit. So the aeration stream is drawn in together by the fan unit and the in-built air fan of the poser unit, wherein it is blown through separately. 
     On at least one side of the fan unit a further channel can be provided in the casing. This channel preferably is a cable channel with electrical cables running through it. Such cables could be connector cables for disk drives or the like as well as power cables, for example for the fan unit. In such a channel the cables can be securely and orderly mounted and packed, and with such a separate channel there is no risk of injuring a cable. Preferably the cables are multi-cord cables. In one embodiment such multi-cord cables are originally flat connector cables with the single cords being separated after fixing the plug connection to its ends. Such a cable can be easily wound around corners or through small holes. 
     When the fan unit is inserted the recess in the casing can be at least partly and in particular completely sealed in the insertion area, so that a casing with inserted fan unit appears sealed from the outside. 
     The casing is advantageously substantially parallelepipedic, particularly flat and elongated in one direction. Along the elongated extension the recess can be located roughly centrally in the casing, advantageously in the area where most of the heal is evolved. Preferably the casing has a front panel and the fan unit air flow runs substantially from said front panel to the opposite back of the casing. In particularly preferred manner, at least on the back and in particular also on the front, there are air openings, preferably also on other lateral faces of the casing, especially in areas with the greatest heat evolution of the device. 
     According to an embodiment the casing can be a casing module of a computer, particularly a so-called 19″ slide-in module for a larger computer, e.g. a medium-s zed to large computer. Such computers can comprise several casing modules of the aforementioned type with different dimensions, particularly with regards to the height. Preferably a casing module of the presently described type has data carrier or disk drives and/or processors, which in particular have a high, lasting cooling air requirement. 
     The fan unit can be placed e.g. roughly in the middle of the longitudinal direction of the casing. Clearly, the chosen location of the fan unit will depend on the arrangement of the computer units and parts in the casing. Cooling air can be drawn in through the front side, especially through ventilation openings in the form of slits or the like, and run through the casing. Behind the fan the air is being blown through the back part of the casing, leaving the casing through ventilation openings on the lateral sides and on the back side. In the front part of the casing can be mounted components such as disk drives or the like. In the back part processors and electronic circuit boards can be mounted for better ventilation by blowing air at them. 
     The casing can have a lockable hinged front shutter, after opening of which the front part of the server in the casing is accessible. Furthermore, such a lock could also be used to secure the fan unit in the casing or Lock the whole modular casing against being opened. 
     The casing or the electrical device in the casing can have several power units, either for more power or for a safe supply. These power units are all connected together to a common busbar, to which the single components like disk drives or the like can be connected. Preferably such a busbar has several plug connections mounted to it, to which can be fitted appropriate plug connections of the components. In this way the change of a component in the casing is very simple, as there need only plug connections to be separated and connected. 
     It is also possible to create a fan unit for insertion in a casing for an electrical device which, according to the invention, has at least one fan located on a support or the like, with which it can be inserted and retained or locked at least to a very significant extent in a corresponding recess in the casing. On the one hand when the fan unit is inserted from above mounting can particularly easily take place and on the other a locking means can be provided. Advantageously the fan unit is constructed as a slide-in module for the casing. It is in particular mechanically and/or electrically detachable and preferably completely separable from the casing. In particularly preferred manner the fan unit is an independent assembly. 
     A fan unit can have several fans, which are arranged in a group or juxtaposed. They are preferably axially juxtaposed and in particular are connected directly to one another. 
     A fan can be detachably fitted to a support, particularly a flat support. Said support can simultaneously form or have a shield for sealing the recess of the casing to the outside. 
     The fan unit is advantageously detachably mountable in the casing in simple manner and is preferably locked by a nonpositive connection. For this locking means can be provided, particularly in the form of a locking receptacle, which corresponds to a locking nose located in the casing. A fitting of the locking receptacle to the removable fan unit offers the advantage that a defective locking receptacle can be easily replaced. 
     The at least one fan is preferably an axial flow fan with blades fitted to the rotor, particularly an external rotor of the fan motor. In particularly preferred manner use is made of direct current motors, particularly brushless d.c. motors, e.g. with an operating voltage of 12 V d.c. The operating voltage for the fans can be taken from a power supply unit of the associated casing, e.g. by means of plug contacts closing on inserting the fan unit and located on the latter and the casing. 
     These and further features can be gathered from the claims, description and drawings and the individual features, either singly or in the form of subcombinations, can be implemented in an embodiment of the invention and in other fields and can represent advantageous, independently protectable constructions for which protection is hereby claimed. The subdivision of the application into individual sections and the subtitles in no way restrict the general validity of the statements made thereunder. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An embodiment of the invention is explained hereinafter relative to the attached drawings, wherein show: 
     FIG. 1 An inclined view of a fan unit with three juxtaposed axial flow fans. 
     FIG. 2 A casing module with a central recess for a fan unit according to FIG.  1 . 
     FIG. 3 A schematic view of a longitudinal cross section of the casing with the fan unit inserted and the channels on its sides. 
     FIG. 4 A schematic view of a lateral cross section of a server casing with the fan unit and the components as well as the cooling air stream. 
     FIG. 5 A schematic view of the power units of the casing with a common busbar, to which are connected components of the server. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a fan unit  11  having three juxtaposed fans  12 . The fans  12  are constructed as axial flow fans with fan blades  14  fitted to the rotor  13  of a fan motor. With respect to the left-hand fan the blades  14  are solely shown in exemplified manner and are only diagrammatically represented for the two other fans. The three fans  12  form a type of fan field, in which they produce a wide, voluminous and preferably equidirectional air flow. 
     The fans  12  are connected by means of a not shown carrier or support to the underside of a cover shield  16 , which projects over the same both as regards width and depth. To the left and right the shield  16  has two catches  17  by means of which the fan unit  11  is held and can if necessary be drawn out of a casing. 
     Laterally a connector  19  with two contact pins  20  is fitted to the left-hand fan  12  and the contact pins  20  can be connected to the fans  12  by means of no shown cables. The connector  19  can simultaneously form part of locking means, particularly a locking receptacle. The contact pins  20  can also form part of locking means, preferably locking pins or noses. 
     FIG. 2 shows a casing  22 , which can be constructed in the form of a so-called 19″ slide-in module for a computer, particularly a server. Roughly centrally on its top  23  the casing  22  has a recess  24 , which extends virtually over the entire width of the casing. It is possible to see on the lateral edges of the recess  24  support profiles  26 , which give the casing  22  stability and serve as a supporting means for a fan unit  11  or its cover shield represented in broken line form. 
     Guide receptacles  29  shown in dotted Sine form extend along the inside of the casing  22 , particularly along the inner lateral faces  27  and serve to receive the fan unit  11 . In particular, the guidance width thereof corresponds to the extension of the fan unit  11 , which is guided in positionally secure manner between the guide receptacles  29 . A plug coupling  31  is represented in dotted line form in the upper area of the left-hand guide receptacle  29 . On or in said coupling can engage a connector of the fan unit  11  and form the electrical contact between the casing  22  or its power supply unit and the fan unit  11 . 
     The casing  22  has a front panel  33  formed by a plate, which projects somewhat over the sides of the casing. The front panel  33  has both grips  34  for extracting the casing from a casing support and venting slots  36 . It is also possible to provide operational units such as switches, displays, keyboards, etc., as well as insertion openings for data carriers or disks. Further venting slots  36  are e.g. provided on the rear, visible lateral face of the casing  22  and advantageously also on the not visible back, particularly substantially distributed over the same. With an air flow along the casing it is advantageous to provide ventilation possibilities at the corresponding casing ends. As a result of the fan unit  11  inserted in the casing  22  and which extends substantially over the entire casing cross-section, it is possible to pass through most and in particular all the devices located in the casing. 
     A replacement of the fan unit can take place by extraction using the catches  17 , particularly also when the fan unit and/or device is in operation. The plug connection is released and following extraction the fan unit is completely separated from the casing  22 . A different or a new, functional fan unit can be inserted in the opposite way. For insertion purposes, it is merely necessary to bring the fans  12  into the recess  24  and guide receptacle  29  and then completely slide or engage in the casing. 
     At the end of the insertion process the plug connection for the electrical contacting of the fans is automatically closed. An operation of the fans  12  can be controlled by the device or automatically started and also monitored. Monitoring permits the detection of a failure of one of the fans and a display or indication thereof. 
     The catches  17  in FIG. 1 could also be replaced by locks or lockable catches for locking the fan unit  11  in the casing  22 . Preferably the cover shield  16  is constructed so as to overlap the front and the back part of the top  23 , which can also be separated from the casing. For this it is only possible to remove the top parts  23  with the fan unit taken out. For example, the top parts on the front and the back of the casing  22  can be held under projections of the front end  33  and the back end of the casing. After removal of the fan unit  11  they can be pulled towards each other and be removed. 
     FIG. 3 shows a cross section of the casing  22  in a different embodiment compared to FIGS. 1 and 2. The fan unit  11  has on its sides three channels provided in the casing. On the lateral sides are provided cable channels  38 , being made up of sheet metal fixed to the inner sides of the casing  22 . They can run at least over the area in which the fan unit  11  is inserted. The cable channels  38  contain several electrical cables  39  These cables  39  mainly are the electrical connections from components in front of the fan unit  11  to components behind the fan unit. The channels  38  can be partly open to insert new cables in it. 
     Beneath the fan unit  11  is mounted a cover  41  extending over the whole width of the casing  22 . This cover  41  is provided for separating a further channel  42  from the rest of the inner of the casing  22 . In the channel  42  three power units  43  are provided, which are mounted to the back side of the casing. The cover  41  is for protecting the rest of the casing and its components against the electromagnetic radiation from the power units  42 . For this purpose the cover can be made up of advantageous materials like sheet metal combined with radiation screens. The power units  43  do have their own in-built air fans  44  for cooling purposes. 
     FIG. 4 mainly shows how the air stream is running through the casing  22 . Through ventilating slots  36  in the front  33  air enters the casing being drawn in by the fans  12  of the fan unit  11  as well as by the in-built fans  44  of the power units. In the front: part of the casing are mounted disk drives  46  such as hard disk drives, CD-ROM drives or the like. The air is being drawn through these towards the fans  12  and  44 . This is the part  47  of air being drawn. 
     Before reaching the fan unit  11  the air stream is separated through the channel  42 , a part of the air stream entering the channel. In the channel the air is being drawn towards the fans  44  of the power units  43 . After streaming along the power units  43  the air is blown out of the casing through ventilating slots  36  on the back side. 
     The main air stream is running through the upper part of the casing  22 , and is blown through the fan unit  11  in the back part. There deflector plates  46  are provided for directing the air flow in a desired direction. Mainly electronic circuit boards  48  are provided in the part  49  of the casing  22  where the air is being blown instead of being drawn. The circuit boards  48  are positioned in such a way that they do not totally block the path of the cooling air. Through ventilating slots  36  air that has been blown through two boards  48  close to each other can be directed outside. In this way a continuous air stream can be maintained even there. Some of the air leaves the casing  22  through slots  36  in the back side. 
     It can be clearly seen that the air stream running from the right to the left can often be divided and redirected, but the general direction is being maintained. By combining the air streams of the power units  43  with those of the fan unit  11  a stronger air stream and as such a better ventilation can be implemented. 
     FIG. 5 shows schematically how three power units  43  are connected to one single busbar  50 , from which the components of an electrical device such as a server draw their electrical power. On the busbar are mounted several plug connectors  51 , into which can be fitted appropriate plugs  52  of components such as the disk drives  46 . The provision of plugs instead of other possibilities like soldering or Ecrew connections is a much faster and easier connection. Through especially coded plug connections being characteristic for special kinds of components mistakes and wrong connections can be overcome. The power units  43  themselves are connected via connections  54  to a power source such as a mains connection in a server room. 
     For ecological reasons the casing  22  can be made up mainly of steel which is easily recyclable. No poisonous material is being used.