Patent Abstract:
A fan has a hub and a fan housing connected to the hub. The fan housing delimits an air passage of the fan outwardly. A fan wheel is connected to the hub and rotatably arranged in the air passage. A motor is arranged on the hub for driving the fan wheel. An electrical connection with at least one flexible line is connected to the motor and extends from the motor to the fan housing. A recess is provided within the fan housing and the flexible line extends from the motor to the recess. A holding member locks in place in the recess and deflects the flexible line at least at one deflection location about a predetermined minimum angle to thereby effect strain relief on the portion of the flexible line extending from the deflection location to the motor.

Full Description:
BACKGROUND OF INVENTION 
   1. Field of the Invention 
   The invention relates to a fan, in particular, a fan for electrical and electronic devices. The fan comprises a hub and a fan housing connected to the hub, wherein the fan housing delimits an air passage provided in the fan in the outward direction. The fan further comprises a fan wheel which is arranged rotatably in the air passage and a motor arranged on the hub for driving the fan wheel. An electrical connection is provided which extends from the motor to the fan housing and comprises at least one flexible line. 
   2. Description of the Related Art 
   A so-called strain relief must be provided for such flexible lines. Usually, the flexible lines are connected by soldering to a printed circuit board of the motor. This solder connection cannot be stressed permanently; it can be damaged or destroyed by mechanical strain or tension. Therefore, such a tension or strain must be stopped before it reaches the printed circuit board. 
   There are different possibilities of realizing such a strain relief. For example, the flexible line can be deflected by a certain angle at least at two locations so that the strain is absorbed in the area of these deflections and the rearward portion of the flexible line extending beyond the deflection locations to the motor remains free of strain. In this way, it is prevented that during transport, during mounting, and during operation of such a fan, a tensile force or strain will be transmitted via the flexible line into the interior of the fan and onto the contact locations or soldering locations or plug contacts and onto the printed circuit board of the motor. 
   In order to permanently ensure such a strain relief, it must be ensured that the flexible line is secured or fixed at this deflection location. 
   In the case of fans with plastic housings, such a strain relief is achieved, for example, in that the flexible line is threaded into stationary or fixed deflection means. When threading it into locking cams or narrow portions, the flexible line is secured therein permanently. 
   In the case of metal housings, the flexible line is threaded through an opening in the flange and then fixed by insertion of a holder and is permanently secured in this way. When a plug is connected to the flexible line, the plug must not be greater than the opening within the flange because otherwise it cannot be threaded through the opening. In such a case, mounting is carried out such that either the plug is connected to the flexible line only after the flexible line has been mounted or the flexible line provided with the plug is soldered to the printed circuit board of the motor only after mounting of the flexible line; both methods prolong the time required for assembly and increase costs for assembly. 
   SUMMARY OF INVENTION 
   It is therefore an object of the present invention to provide a fan configuration which eliminates the aforementioned problems. 
   In accordance with the present invention, this is achieved in that a cutout is provided within the fan housing to which the at least one flexible line extends and in which a holding member can be locked in place, wherein the holding member in the mounted state deflects the at least one flexible line at least at one location about a predetermined minimum angle and, in this way, effects strain relief on the part of the flexible line extending to the motor. 
   By employing a holding member which can be locked in place on the fan housing, it is possible to place the flexible line, before mounting of this holding member, in a simple way into a recess or cutout provided for this purpose, so that it must not be threaded, and to deflect the flexible line only upon mounting of the holding member. After mounting of the holding member, the flexible line—without plug—which has been fixed in place in this way, can only be removed from the strain relief device in that the holding member is removed or in that the flexible line is removed (unthreading) over its entire length out of these deflections. A flexible line which has a plug attached thereto can be removed from the strain relief device only in that the holding member is removed again from its locking position. It is thus very advantageous that the flexible line must not be threaded into the at least one deflection device; instead, it is deflected upon insertion and locking of the holding member and, in this way, the deflection required for strain relief is automatically provided in the locked position of the holding member. 
   Preferably, this is realized in that the holding member in the locked state deflects the flexible line at two deflection locations about a predetermined minimum angle in order to effect the strain relief. This provides a very safe strain relief without this requiring extra expenditure for assembly. Moreover, the present invention enables that the time for assembly becomes independent of the length of the flexible line and that even flexible lines provided at their end with a plug can be mounted entirely without problems. 
   A very advantageous embodiment is provided in that a support member for at least one flexible line is provided on the hub and supports the flexible line in the area of the air passage at least partially. Such a support member provides the advantage that the flexible line must not be threaded at this location but can be simply placed onto the support member; this simplifies mounting significantly. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a perspective view of a preferred embodiment of the fan according to the invention before completion of assembly. 
       FIG. 2  is an exploded view of the fan of FIG.  1 . 
       FIG. 3  is a plan view onto the air exit side of the fan of FIG.  1 . 
       FIG. 4  is a section along the line IV—IV of FIG.  3 . 
       FIG. 5  is a side view of a lockable holding member, viewed in the direction of arrow V of FIG.  7 . 
       FIG. 6  is a section along the line VI—VI of FIG.  3 . 
       FIG. 7  is a plan view viewed in the direction of arrow VII of FIG.  5 . 
       FIG. 8  is a schematic illustration of the holding member of  FIG. 5  in the mounted state. 
       FIG. 9  is a section viewed along the line IX—IX of FIG.  11 . 
       FIG. 10  is a plan view onto a corner of the fan in which a holding member is mounted. 
       FIG. 11  is a section (analog to  FIG. 4 ) viewed along the line XI—XI of  FIG. 10  but with the holding member mounted and the flexible line mounted. 
       FIG. 12  is a perspective illustration of the holding member viewed in a first direction. 
       FIG. 13  is a perspective illustration of the holding member viewed in a second direction. 
       FIG. 14  is a perspective illustration of the holding member viewed in a third direction. 
       FIG. 15  is a perspective illustration of the holding member viewed in a fourth direction. 
   

   DETAILED DESCRIPTION 
     FIG. 1  shows in a perspective illustration a so-called device fan  20 . It is illustrated in an exemplary fashion as a diagonal fan; this configuration has advantages for certain applications because a more beneficial characteristic line of the fan results: for example, when a filter is plugged and the flow rate dV/dt of the fan  20  drops, the generated pressure (static pressure) Δpf increases in a diagonal fan more strongly than in an axial fan. This provides a safety reserve for the user, in particular, when high pressure and high airflow are required. 
     FIG. 2  shows the configuration of the fan  20  in an exploded view. The fan  20  has a fan housing  22  which is essentially a pipe-shaped section  24  of a truncated cone shape having at both end portions fastening flanges  26 ,  28 . The flow direction  30  of the air is illustrated in FIG.  1 . The intake side of the fan  20  is shown at  32  and the exit side at  34 . 
   The fan  20  has a motor  36  whose stator in FIG.  1  through  FIG. 3  is illustrated in dashed lines. It drives a fan wheel  38  with fan vanes  40 . The motor  36  is preferably an electronically commutated two-phase external rotor motor in which the fan wheel  38  is mounted directly on the external rotor. 
   The shape of the fan vanes  40  is matched to the conical shape of the inner side of the pipe  24 . The fan wheel  38  has a center part  39  having a truncated cone shape at its exterior side, as illustrated in FIG.  2 . It forms together with the truncated cone shaped pipe  24  an air passage  41 . The air passage has a smaller diameter at the intake side  32  than at the exit side  34 . Also, the fan wheel  38  has a smaller diameter at the intake side  32 . The diameter increases in the direction toward the exit side  34 . 
   For mounting the motor  36 , a fastening flange  44 , which is also referred to in the following as a hub, is provided and connected by thin securing stays  46  to the fan housing  22 . This is realized preferably by screw connections  48  indicated in FIG.  1  through FIG.  3 . The outer or free ends of the stays  46  have widened portions  21  which fit in corresponding recesses  23  of the fan housing  22  (see FIGS.  1  through  3 ). A positive locking guide is provided: Two diametrically opposed recesses  23  have a guide member in the form of a centering pin  25 , respectively, which locks positively in a corresponding complementary guide member (cutout)  27  of the correlated widened portion  21  and, in this way, centers the hub  44  exactly within the conical pipe  24 . The screws  48  serve thus only for fastening but not for centering. This is a very advantageous type of connection, also with respect to automated manufacture. 
   Moreover, a shortened stay  50  is provided on the hub  44  whose function it is to support the flexible electric connecting line  52  of the motor  36 . The electric line  52  can be configured, for example, as a multi-strand plastic-sheathed cable. As illustrated clearly in  FIG. 2 , the flexible line  52 , coming from the motor  36  where it is, for example, soldered to a printed circuit board (not illustrated), passes through a lateral opening  49  of the hub  44 , is then placed into a guide groove or support member  53  provided on the stay  50 , and extends then farther outwardly to the fan housing  22  where a so-called strain relief for the cable  52  is provided which will be explained in the following. 
   The motor  36  is fixedly connected by non-illustrated securing pawls to the hub  44 . The stays  46 ,  50  are preferably formed as unitary parts of the hub  44 . In  FIG. 1 , the direction of rotation  56  of the illustrated fan  20  is shown. 
   The connecting line or cable  52  of the fan  20  usually contains several flexible insulated lines, preferably, so-called litz wires, each comprised of a plurality of thin wires which are embedded in an insulating material. In the home, such flexible lines or litz wires are used, for example, in the form of multi-strand plastic-sheathed cables for electrical connections of electric irons or television sets. The fan  20  requires two lines for supplying its operational voltage. In many cases, extra lines are provided, for example, for a tachometer generator signal or for an alarm signal. All of these flexible lines or cables must be attached quickly and primarily securely when mounting the fan  20 ; this will be explained in the following. 
   As shown in  FIG. 1 , the fan housing  22 , viewed in the direction of the axis of rotation  60  ( FIG. 2 ) of the motor  36  has a substantially rectangular, in particular, square, contour with four corners provided with bores  62  for attachment of the fan  20 . On the corner  64 , illustrated in  FIGS. 1 through 3 , at the forward end to the right, a recess  66  is provided. For this purpose, the pipe  24  is provided at its exterior with a flat widened portion  68  which extends preferably parallel to the axis of rotation  60  and transverse to the corner  64 . At least one of the flanges  26 ,  28  has a cutout adjacent to this widened portion  68  (cutout  26 A at the flange  26 ; cutout  28 A at the flange  28 ). Preferably, the cutouts  26 A,  28 A are substantially aligned with one another so that the flexible line  52  can be guided through them in the axial direction, i.e., approximately parallel to the axis of rotation  60  (compare FIG.  1 ). In the area of the corner  64 , the flanges  26 ,  28  are connected with one another by a connecting member  69  whose shape and position is illustrated clearly in  FIGS. 1 through 3 . Its function in the context of mounting the flexible line  52  will be explained in the following. 
   At the exit side  34  of the truncated cone-shaped pipe  24  a lateral recess  70  is provided which is positioned substantially on an imaginary extension of the shortened stay or support  50  so that the flexible line or cable  52 , which is guided in the groove  53  of the stay  50 , can be placed subsequently through the cutout  70  and through the cutouts  28 A and  26 A without having to be threaded anywhere. This type of guiding of the line  52  is clearly illustrated in  FIGS. 1 through 3 . The line  52  extends approximately parallel to the flat widened portion  68 . This represents an intermediate step of assembly which will become apparent from the following description. 
     FIG. 3  shows a plan view onto the exit side of the fan  20 . The five fan vanes  40  are clearly illustrated as well as their shape which is characteristic of a diagonal fan. The concave ends  72  of the vanes  40  are positioned on the intake side  32 . Moreover, the shape of the three stays  46  is clearly shown as well as the connections  48  with the fan housing  22 . Also shown is the shape of the shortened stay  50  and the support member or groove  53  provided thereon in which the at least one flexible line or cable  52  is inserted in the illustrated way. This groove  53  extends only across a portion of the air passage cross-section  41 , for example, as illustrated, across one-third of its radial extension. Moreover, the flat widened portion  68  has a transition into a projection  74 , illustrated in  FIG. 3  to the right, where a locking action is possible. The left end has a transition into an analog projection  76  whose function will be explained in the following. 
   As illustrated, the flexible line  52  extends from the motor  36  via the groove  53  and through the cutout  70  of the truncated cone-shaped pipe  24  to the two cutouts  28 A,  26 A of the flanges  28  and  26 . This is illustrated also in  FIG. 4  which shows a section of the indicated part of FIG.  3 . 
     FIG. 5  shows a holding member  80  viewed in the direction of arrow V of  FIG. 7 , i.e., viewed in a side view.  FIG. 6  shows a section viewed along the line VI—VI of  FIG. 5 , and  FIG. 7  shows a plan view onto the holding member  80 , viewed in the direction of arrow VII of FIG.  5 .  FIGS. 12 through 15  show the holding member  80  in different perspective views in order to facilitate understanding of its shape. 
   The holding member  80  has a substantially flat base part  82  which is illustrated in  FIGS. 6 and 7  in a plan view and serves for locking the holding member  80  at the corner  64  of the fan  20  in the recess  66  provided thereat. For this purpose, it is provided at its underside to the left with a hook  84  which, according to  FIG. 8 , engages in the mounted state behind the projection  76  of the fan housing  22 . To the right, the holding member  80  has a detachable springy locking hook  86  which, according to  FIG. 8 , can be locked on the projection  74  of the fan housing  22 . In  FIG. 9 , the holding member  80  is thus moved from the left into the recess  66  to such an extent that it is secured on the projection  74 ,  76  in the way illustrated in  FIGS. 8 and 9 . 
   In  FIG. 5 , above the base part  82  a roof part  90  is provided which is connected with its left end via a slanted potion  92  with the base  82 . The upper areas of the roof part  90  of  FIGS. 6 and 7  are wider than the base part  82 , and a limiting wall  94  is formed which extends perpendicularly to the base part  82  and whose shape and position can be seen clearly in  FIGS. 5 and 6 . 
   The roof part  90  is also connected at a location provided approximately at its center by means of a deflection member  96  to the base part  82 . As illustrated in  FIGS. 8  to  11 , the deflection member  96  has the purpose of deflecting the flexible line  52  by a certain minimum angle after the holding member  80  has been inserted into the fan housing  22 . 
   To the right of the deflection member  96 , the roof part  90  has a raised section  98  which, according to  FIGS. 8 and 9 , rests in the mounted state with tension against the part  69  which prevents that the holding member  80  will be released when exposed to strain by becoming detached from the location  74 . Detachment is possible however when moving by hand the holding member  80  to the right in  FIG. 8  or  9  and when bending with the other hand the springy locking hook  86  in the upward direction and subsequently pulling or pushing by hand the holding member  80  out of the recess  66  to the left. The holding member  80  is preferably made of a springy plastic material. 
   As illustrated in  FIG. 7 , the roof part  90  covers only a portion of the base part  82  in the lower area. The flexible line  52  can be guided through this free area  99 . Should this not be desired, the area  99  can also be covered completely by the roof part  90 . 
     FIG. 9  shows the holding member  80  in the mounted state in the recess  66  at the corner  64  of the fan housing  22 . After mounting, the holding member  80  is locked in this position but can be unlocked by lifting the springy locking member  86  and can be moved or pulled out of the recess  66  to the left. 
     FIG. 10  shows the same corner  64  of the fan housing  22  but in a plan view and not in a sectional view. The flexible line  52  is shown which is guided via the stay or support  50  to the recess  70 . The lateral cutout  28 A of the fan housing  22  is substantially closed by the section  94  of the holding member  80  so that a guide opening is formed for the flexible line  52 ; this is illustrated clearly in FIG.  11 . 
   By means of the deflection member  96 , the flexible line  52  is moved in  FIG. 111  to the right upon insertion of the holding member  80  so that it is deflected once at a first deflection location  106  where it exits the cutout  70 . Moreover, the flexible line  52  is deflected by the deflection member  96  at a second deflection location  108  by an angle which, depending on the application, can be approximately between 60 and 110 degrees. When the flexible line  52  is guided in direction  52 A out of the fan  20 , the deflection angle at the second deflection location  108  is approximately 60 degrees; when the flexible line  52  is guided in the direction  52 B out of the fan  20 , i.e., through the cutout  26 A, the deflection angle at the location  108  is greater than 90 degrees. Finally, the flexible line  52  can also be guided in the direction  52 C illustrated in  FIG. 9 ; in this embodiment it rests against the part  69  of the fan housing  22 . The line  52  then extends through the free space  99  illustrated in FIG.  7 . When this configuration is to be excluded, the free space  99  is covered completely by the roof part  90  in that this roof part  80  is shaped correspondingly wider. 
   Because of the two deflection locations  106 ,  108  of  FIG. 11 , the required strain relief is realized in any case on that side of the flexible line  52  which extends to the motor  36 . Mounting is very easy, i.e., the flexible line  52  is inserted into the fan  20  as illustrated in FIG.  1  and then the holding member  80  is pushed into the recess  66  and locked therein. In this way, the two deflection locations  106 , 108  ( FIG. 11 ) are automatically realized so that the desired strain relief is provided. Such an assembly is thus independent of whether a plug is connected to the line  52  or not. As an alternative, a plug can be attached directly in or on the holding member  80  or the holding member  80  itself can be configured as a plug and this plug can be inserted into the recess  66  and locked therein. 
   Advantages of the invention result primarily from the following features: Before mounting the holding member  80 , at least one flexible line  52  can be inserted directly into the corresponding openings of the fan  20 , i.e., it is no longer required to thread the line  52 ; the line  52  is deflected at the locations  106 , 108  once the holding member  80  is mounted. 
   After mounting, the flexible line  52 , inasmuch as no plug is connected thereto, can be removed only by unthreading its entire free length or by demounting the holding member  80  from the strain relief. 
   A flexible line  52  to which a plug is attached can be removed only by releasing the holding member  80  from the strain relief. 
   The insertion and locking of the holding member  80  deflects the at least one flexible line  52  at the same time at two locations  106 , 108  ( FIG. 11 ) so that in the end position of the holding member  80  automatically the required number and type of deflections required for strain relief are provided. 
   Inasmuch as several flexible lines  52  are used, a significant labor simplification is realized by the two cutouts  26 A,  28 A into which these lines  52  are introduced before mounting as shown in FIG.  1 . When the lines  52  have been inserted, subsequently the holding member  80  can be inserted and locked. However, the invention can be realized, for example, without the cutout  26 A because strain relief can be obtained also by deflection in this case. 
   The time for assembly is independent of the length of the flexible line(s)  52 . 
   Flexible lines having a plug at their free end can be mounted without problems in the described way. 
   By means of the stay  69  provided on the housing  22 , unthreading of the flexible line  52  in the locked state of the holding member  80  is not possible or possible only with difficulties. 
   Threading of the flexible line  52  in stationary deflection means on the housing is eliminated by the invention so that the time for assembly is shortened correspondingly. 
   In place of the illustrated individual flexible lines  52 , the invention can also be employed in the same way with several flexible lines or lines which are enclosed in an insulating hose and require a strain relief. 
   Instead of the holding member  80  it is also possible to provide a plug connector. 
   Inasmuch as a tensile force acts on the flexible line  52  in a direction perpendicularly to the insertion direction, it is not received by the holding member  80  but by part  69  of the housing  22 ; compare line  52 C in FIG.  9 . 
   The part  69  stabilizes in the area of the corner  64  the two flange parts  26  and  28  relative to one another. This is advantageous when attaching the fan  20  by means of its flanges  26 ,  28 , for example, in the case of a screw connection with screws passing through. In the area of the other corners analog reinforcements can be provided, as illustrated clearly in FIG.  1 . 
   The invention is particularly advantageous in combination with a diagonal fan but can also be used in axial fans. Naturally, within the context of the invention several variations are possible. For example, the shortened stay or support  50  can also be of such a length that it is connected to the corner  64  of the fan housing  22 , for which purpose a somewhat different shape than that of the stays  46  must be provided. Also, the invention can be used in the same way where lines are used which are relatively rigid, i.e., no litz wires, for connecting a fan. These and other modifications are within the scope of the invention. 
   While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

Technology Classification (CPC): 5