Abstract:
An equipment fan has a housing ( 22 ) that externally defines an air passage opening ( 41 ) provided in the fan ( 20 ). The fan has a motor ( 21 ) for rotatably driving blades ( 40 ) about a rotation axis ( 23 ), as well as a carrier element ( 51 ), provided between the motor ( 21 ) and the housing ( 22 ), which extends transversely to the passage ( 41 ) and is configured as a trough ( 53 ) that serves to receive an electrical lead ( 52 ) and guides the lead along a predetermined path from the motor ( 21 ) to a location ( 64 ) on the housing ( 22 ). The fan also has a deflection device ( 50 ) which, by deflecting the lead ( 52 ) at a first deflection location ( 55 ) and at a second deflection location ( 84 ) and in at least two planes extending at a predetermined angle with respect to one another, effects strain relief for the lead ( 52 ) that proceeds to the motor ( 21 ).

Description:
CROSS-REFERENCE  
       [0001]     This application claims priority from my German application DE 20 2005 013 419.8, filed 19 Aug. 2005, the entire content of which is hereby incorporated by reference.  
       FIELD OF THE INVENTION  
       [0002]     The invention relates to a fan, in particular to an equipment fan, having a fan housing and having a motor for driving fan blades that are arranged rotatably in an air passage opening provided in the fan, and having an electrical connection that leads from the motor to a housing part, and comprises at least one electrical lead that is usually in the form of a stranded conductor.  
       BACKGROUND  
       [0003]     So-called strain-relief must be provided for such leads. This is because such leads are usually soldered onto a circuit board of the motor, and this soldered join cannot carry loads over the long term and can be damaged or destroyed by mechanical tension; such mechanical tension must therefore be stopped before it reaches the circuit board.  
         [0004]     WO 2004/046 557 and corresponding US-2004-0096325, WEISSER, assigned to the assignee of the present invention, describe a fan housing having a radial enlargement, in which is provided an opening to which an electrical lead extends from a motor that is arranged in the fan housing. A latchable holding member is introduced into this opening and latched therein. In the latched state, it deflects the electrical lead at two locations through a predetermined minimum angle, thus effecting strain relief on the side of the electrical lead proceeding to the motor. The result of using this holding member is that a flexible lead can be easily be inserted, prior to assembly of the holding member, into openings provided therefor (i.e. it does not need to be threaded in), and that the lead is deflected only upon introduction of the holding member. A lead immobilized in this fashion can be removed from the strain relief element either by removing the holding member or by pulling the flexible lead, provided it is not fitted with a connector plug, out of the deflections over its entire length.  
       SUMMARY OF THE INVENTION  
       [0005]     It is an object of the present invention to provide a novel fan having improved strain relief features.  
         [0006]     According to the invention, this object is achieved by a structure which deflects the electrical lead at a plurality of deflection locations, and along at least two planes oriented at a predetermined angle with respect to each other. The result is that a flexible lead can be hooked in easily and conveniently, the lead being retained in the strain relief apparatus, and reliable strain relief being achieved. Once it has been hooked in, a lead immobilized in this fashion can be removed again from the strain relief element only by unhooking it from the deflections over its entire length, or by pulling it out.  
         [0007]     Preferred refinements of a fan according to the present invention are described in greater detail below.  
     
    
     BRIEF FIGURE DESCRIPTION  
       [0008]     Further details and advantageous refinements of the invention are evident from the exemplifying embodiments, in no way to be understood as a limitation of the invention, that are described below and shown in the drawings.  
         [0009]      FIG. 1  is a perspective depiction of a fan according to the present invention; the motor is indicated merely schematically, and the fan blades are not depicted in  FIG. 1 ; one such blade  40  is indicated in  FIG. 3  with dot-dash lines;  
         [0010]      FIG. 2  is an enlarged depiction of the front (in  FIG. 1 ) corner of the fan;  
         [0011]      FIG. 3  is a plan view from above of the fan of  FIG. 1 , looking in the direction of arrow III of  FIG. 1 ;  
         [0012]      FIG. 4  is an enlarged depiction of the corner shown at the bottom left in  FIG. 3 ;  
         [0013]      FIG. 5  is an enlarged depiction of a detail, looking approximately in the direction of arrow V of  FIG. 2 ;  
         [0014]      FIG. 6  is a three-dimensional depiction looking approximately in the direction of arrow VI of  FIG. 1 ;  
         [0015]      FIG. 7  is a side view looking in the direction of arrow VII of  FIG. 1 ; and  
         [0016]      FIG. 8  is a section looking along line VIII-VIII of  FIG. 1   
     
    
     DETAILED DESCRIPTION  
       [0017]     In the description hereinafter, the terms “left,” “right,”, “upper,” and “lower” refer to the respective Figure of the drawings. Identical or identically functioning parts are labeled with the same reference characters in the various Figures, and are usually described only once.  
         [0018]      FIG. 1  is a three-dimensional depiction of an equipment fan  20  that is depicted here as an axial fan. The invention is not, however, limited to axial fans. It can instead be used in the same fashion in other types of fan, e.g. in diagonal and radial fans.  
         [0019]     Fan  20  has a fan housing  22  that is approximately in the shape of a cylindrical tube  24  and is provided with a mounting flange  26  at its lower (in  FIG. 1 ) end and a mounting flange  28  at its upper end. The air flow-through direction  25  is defined by an inflow side and an outflow side.  FIG. 1  shows the outflow side, labeled  34 , at the top.  
         [0020]     Fan  20  has a motor  21  to drive fan blades  40  ( FIG. 3 ) that are arranged, rotatably about a rotation axis  23 , in an air passage opening  41 . During operation, blades  40  rotate in the direction of an arrow  27 . The shape of fan blades  40  is adapted to the shape of the inner side of tube  24 . Motor  21  is preferably an electronically commutated external-rotor motor in which blades  40  are attached to the external rotor.  
         [0021]     A mounting flange  44  that is joined via struts  46  to fan housing  22  serves for the installation of motor  21  in fan housing  22 . Struts  46  are preferably implemented integrally with mounting flange  44  and housing  22 . Located on flange  44  is a bearing tube  48  on which motor  21  is mounted in known fashion.  
         [0022]     Extending through a lateral cutout  49  of flange  44  is a flexible electrical connector lead  52  of motor  21 , which lead can be implemented, for example, as a multi-conductor lead. It is soldered onto a circuit board (not shown) of motor  21  and from there is guided outward to fan housing  22 , a strain relief apparatus  50  being provided for lead  52 , in a manner to be described below.  
         [0023]     Lead  52  usually contains multiple flexible insulated leads, preferably so-called stranded conductors, each of which is made up of a plurality of thin wires that are surrounded by an insulating material. A fan requires two thick leads for delivery of an operating voltage. In many cases thinner leads are also provided, e.g. for a speed signal or alarm signal. All these flexible leads must be quickly and, above all, securely mounted during assembly, and this is described below.  
         [0024]     As  FIG. 1  and  FIG. 3  show, fan housing  22  has, viewed in the direction of rotation axis  23 , an approximately square outline having four corners  64  at which openings  62  are provided for mounting fan  20 . In a preferred embodiment, housing  22  consists essentially of plastic material, e.g. molded plastic. Alternatively, housing  22  could be made of fibers embedded in an elastomeric matrix, or other materials having suitable strength/weight ratios and durability.  
         [0025]     Located in the region of the front (in  FIG. 1 ) corner  64  is strain relief apparatus  50 . This can be arranged at any desired location of fan housing  22 , but corners  64  are particularly suitable therefor. Apparatus  50  is preferably formed integrally with fan housing  22  and serves, by deflecting lead  52  at at least two deflection locations and in two planes that converge with one another at a predetermined angle, to create a strain relief for the portion of lead  52  that proceeds to motor  21 . Details of strain relief apparatus  50  are shown in great detail, especially in  FIGS. 2, 4 , and  5 , so that a description in words would be superfluous for one of ordinary skill in the art.  
         [0026]      FIGS. 1 and 2  show how lead  52  emerges from cutout  49  of mounting flange  44  and is guided in a strut  51 , which is arranged between motor  21  and fan housing  22  and is equipped with a guide trough  53  in which lead  52  is guided from motor  21  to a lateral delimiting surface  29  of fan housing  22 , which surface is adjacent to the region of enlargement  64 . To prevent lead  52  from slipping out of guide trough  53 , it is prevented from slipping out there by a first hold-down  54 . The latter extends only far enough that it still allows lateral insertion of lead  52  into trough  53 , thus speeding up assembly.  
         [0027]     Trough  53  continues, in the region of corner  64 , into a conduit  56  ( FIG. 2 ) that generally runs approximately in a radial direction and is depicted as being radially open toward the outside, thus making stranded conductors  52  easier to hook in.  
         [0028]     Extending approximately transversely to conduit  56  are a second hold-down  57  that comes from the left in  FIG. 2 , and a third hold-down  58  that comes from the right in  FIG. 2 . Hold-downs  57 ,  58  form between them a narrow gap  59  through which stranded conductors  52  can be set in place. Gap  59  extends at an angle to conduit  56 , as is clearly evident from  FIG. 2 . The result of this is that lead  52  cannot spontaneously release itself from conduit  56 . Hold-downs  57  and  58  overlap in terms of their actions.  
         [0029]     As  FIG. 5  shows particularly clearly, located there below third hold-down  58  is a relatively sharp deflection edge  55  that can have, for example, a radius of 0.5 mm and around which lead  52  (as shown in  FIG. 4 ) is deflected approximately in the opposite direction. This deflection occurs approximately in a plane that extends perpendicular to rotation axis  23 , as clearly shown by  FIGS. 2, 4 , and  5 . The deflection angle, according to  FIG. 4 , is more than 120° and is preferably approximately 180°. This angle is of course variable within wide limits.  
         [0030]     To facilitate insertion, conduit  56  has, at its radially outer end, an oblique wall  63  that, as shown in  FIG. 2 , transitions downward into a stiffening wall  70 . Extending parallel to wall  70  and at a distance therefrom is a stiffening wall  72  that transitions upward, via an oblique wall  74 , into upper flange  28 . Stiffening walls  70 ,  72  extend between flanges  26  and  28 . Upon assembly of the fan, oblique walls  63 ,  74  (and corresponding oblique walls on lower flange  26 ) direct the force of a mounting screw (not depicted) directly from screw supporting surface  76  into ribs  70 ,  72 , thus enabling a doubling of the tightening torque of the relevant screw and consequently allowing such a fan  20  to be mounted particularly securely.  
         [0031]     The deflection of lead  52  around the sharp deflection edge  55  ( FIG. 5 ), with its small deflection radius, results in elevated friction there that counteracts any longitudinal displacement of lead  52 . As  FIG. 5  shows, deflection edge  55  encloses an angle of approximately 30-50° with the longitudinal direction of hold-down  58 . As  FIG. 4  shows particularly well, a guide conduit  78 , which is delimited externally by a wall segment  80 , extends on the lower (in  FIG. 4 ) side of deflection edge  55 . Lead  52  extends through this guide conduit  78  as far as a second deflection location  82 , at which lead  52  is deflected in a direction that extends approximately parallel to rotation axis  23 . This deflection is clearly shown in  FIG. 8 . Lead  52  extends there from upper flange  28 , through an opening  84  thereof, to an opening  86  ( FIG. 2 ) of lower flange  26 . Lead  52  thereby runs over a protruding, relatively sharp-edged rib  88  that extends from stiffening wall  70  to the outer periphery of segment  24  and extends approximately perpendicular to rotation axis  23 .  
         [0032]     As  FIG. 8  shows, rib  88  causes a slight deflection of lead  52 . The reason is as follows: Exertion of a force F 1  on lead  52 , as shown in  FIG. 2 , would of itself result in a movement of lead  52  in the direction of force arrow F 2  in the region of trough  53 . Rib  88  reduces force F 2 , and the two hold-downs  57  and  58  prevent lead  52  from jumping out of rib  53  and groove  56  as a result of force F 2 .  
         [0033]     As depicted in  FIG. 4 , opening  84  is accessible from outside via a curved hooking-in opening  90  (in flange  28 ), so that stranded conductors  52  can be hooked in by means of this opening  90  but cannot then spontaneously become unhooked. This effect is reinforced by rib  88 .  
         [0034]     Opening  86  ( FIG. 2 ) in lower flange  26  is accessible from outside via an approximately spiral-shaped conduit  92 , so that stranded conductors  52  can easily be hooked in by means of this conduit  92  but inadvertent unhooking of the stranded conductors, i.e. so-called self-release, is prevented by rib  88 .  
         [0035]     The following advantages, in particular, are obtained by way of the invention:  
         [0036]     Stranded conductors  52  of different diameters can be used simultaneously, e.g. a thinner stranded conductor for a signal lead.  
         [0037]     Stranded conductors  52  can be hooked in rapidly and without tools.  
         [0038]     Strain relief  50  acts on each individual stranded conductor  52 .  
         [0039]     Self-release of the stranded conductors from strain relief  50  is largely precluded.  
         [0040]     Strain relief apparatus  50  can be manufactured using a simple injection mold having only two sliders.  
         [0041]     Numerous variations and modifications are of course possible, within the scope of the present invention.