Abstract:
Due to variations arising during manufacturing, axial fans often are slightly imbalanced, resulting in noise during operation, which is undesirable in many contexts, for example when the fan is used for ventilation purposes in a motor vehicle. A fan with improved vibration and noise damping can be achieved by elastically suspending the fan wheel within a first ring formed of a hard plastic, the first ring having a tubular extension formed of a softer plastic, and serving to mechanically connect the first ring to a surrounding annular carrier part. Optionally, the first ring and extension unit can include a spring element. Preferably, the first ring and tubular extension are produced by a multi-component forming technology such as two-plastic technology. The fan is preferably driven by an electronically commutated motor (ECM).

Description:
CROSS-REFERENCE 
     This application claims priority from my German application DE 20 2008 001 613.4, filed 25 JAN. 2008, the disclosure of which is hereby incorporated by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a fan unit having an axial fan. 
     BACKGROUND 
     Axial fans, and fans in general, usually have a manufacturing-related imbalance that can result in undesirable vibration when they are operated. Obtrusive noise can moreover be caused by motor and air-flow noise produced by the fan. This undesirable vibration and obtrusive noise must be damped, especially in convenience-related applications. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a novel fan unit having an axial fan with improved noise-damping features. This object is achieved by a fan structure defining an airflow passage or channel in which the fan hub and blades are suspended. The suspension employs a first ring, made of a hard plastic, which has at least one tubular extension, made of a soft plastic, serving as a noise-damping mechanical connection to an annular carrier part. A very compact configuration is achieved in this context by the use of the first ring equipped with the tubular extension. This configuration exhibits improved vibration and noise damping because of the joining of the first ring made from a hard plastic to the tubular extension made from a soft plastic. 
     Preferred refinements of the fan according to the present invention are described in more detail below. 
    
    
     
       BRIEF FIGURE DESCRIPTION 
       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 depicted in the drawings. 
         FIG. 1  is a perspective view of the back side of a fan unit having an axial fan, in accordance with a first embodiment; 
         FIG. 2  is a perspective view of the front side of the fan unit of  FIG. 1 ; 
         FIG. 3  is a partly sectioned exploded view of the fan unit of  FIG. 1 ; 
         FIG. 4  is a partly sectioned perspective view of the fan unit of  FIG. 1 ; 
         FIG. 5  is a sectioned view of the fan unit of  FIG. 1 ; 
         FIG. 6  is a sectioned view of the bellows of  FIG. 1  joined to a carrier ring  40 ; 
         FIG. 7  is a sectioned view of the bellows of  FIG. 1 ; 
         FIG. 8  is a perspective view of bracing ring  60  of  FIG. 1 ; 
         FIG. 9  is a perspective view of carrier ring  40  of  FIG. 1 ; 
         FIG. 10  is a sectioned view of an alternative embodiment of the bellows of  FIG. 7 ; 
         FIG. 11  is a perspective view of a back side of a fan unit having an axial fan, in accordance with a second embodiment; 
         FIG. 12  is a perspective view of the front side of the fan unit of  FIG. 11 ; 
         FIG. 13  is a partly sectioned exploded view of the fan unit of  FIG. 11 ; 
         FIG. 14  is a sectioned view of the fan unit of  FIG. 11 ; 
         FIG. 15  is a partly sectioned perspective view of the fan unit of  FIG. 11 ; 
         FIG. 16  is a partly sectioned perspective view of the bellows of  FIG. 11  joined to the carrier ring; 
         FIG. 17  is a sectioned view of the bellows of  FIG. 11 ; 
         FIG. 18  is a perspective view of bracing ring  60  of  FIG. 11 ; and 
         FIG. 19  is a perspective view of carrier ring  140  of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     In the description that follows, the terms “left,” “right,” “front,” “rear,” “upper,” and “lower” refer to the respective figure of the drawings, and can vary from one figure to the next as a function of a particular orientation (portrait or landscape) that is selected. Identical, or identically functioning, parts are labeled with the same reference characters in the various figures, and usually are described only once. 
       FIG. 1  shows, in a rear view, a first embodiment of a fan unit  10  having an axial fan  20  and a vibration- and noise-damping apparatus  30 . Axial fan  20  has an approximately hollow-cylindrical airflow or air-guiding tube  22  that can be made from plastic or metal, or any mixed form thereof. Provided on the outer circumference of air-guiding tube  22  are several suspension members  23  made of an elastomeric material, of which suspension members  23  to  23   r  are visible in  FIG. 1 . Arranged in the interior of air-guiding tube  22  is a fan wheel  24  that is arranged rotatably about a rotation axis  23  which proceeds along the longitudinal axis of air-guiding tube  22 . Fan wheel  24  has fan blades  26 ′ to  26   V , the shapes of which are adapted to the shape of the inner side or surface of air-guiding tube  22 . 
     Fan  20  has a motor  21  ( FIGS. 4 and 5 ) to drive its fan wheel  24 . Motor  21  is preferably implemented as an electronically commutated external-rotor motor. It has a rotor cup  25  ( FIG. 1 ) on which fan wheel  24  is mounted. A mounting flange  38  ( FIG. 2 ), which is joined to air-guiding tube  22  via thin holding struts  29  to  29   III  ( FIG. 2 ) as described with reference to  FIG. 2 , serves for installation of motor  21  in air-guiding tube  22 . 
     Motor  21  is connected to a flexible electrical connector lead  70 . The latter is soldered onto a circuit board  90  ( FIG. 5 ) of motor  21 . Fan  20  has two leads  70 ′ and  70 ″ for supply of an operating voltage. In many cases, further leads are provided, for example for input of a target speed signal or for output of an alarm signal. 
     As is evident from  FIG. 1 , fan or blower  20  is arranged in vibration- and noise-damping apparatus  30 . The latter has a first ring  40  for elastic suspension of fan  20 , a tubular extension  50  joined thereto for oscillation damping, and a second ring  60  for joining fan unit  10  to a carrier part  15  ( FIG. 5 ). First ring  40  thus carries fan  20  and is therefore hereinafter also referred to as a “carrier ring.” Extension  50  is braced, relative to the carrier part, on second ring  60 . This ring is therefore also referred to as a “bracing ring.” Tubular extension  50  is preferably implemented as a bellows, and has a spring element  86  having a predetermined oscillation characteristic for vibration damping and noise damping, as described in detail with reference to  FIG. 3 . 
     According to a preferred embodiment, carrier ring  40 , tubular extension  50 , and bracing ring  60  are implemented as a physical unit using multi-component forming technology, in particular using so-called two-plastic technology. Carrier ring  40  and bracing ring  60  are preferably made from a hard plastic, and tubular extension  50  from a soft material. Tubular extension  50  can be joined to carrier ring  40  and/or to bracing ring  60 , for example, by injection molding, by a clamping join, by an adhesive join, or by plastic welding. 
     Several securing members  55  made of a hard plastic are provided on carrier ring  40  in order to secure the suspension members  23 ; of these, securing members  55  to  55   IV  are visible in  FIG. 1 . Securing members  55  can also be made at least in part, on the inner circumference of tubular extension  50 , from a soft plastic, as described with reference to  FIGS. 3 and 7 . 
     During the operation of axial fan  20 , motor  21  drives fan wheel  24  in such a way that the latter rotates about its rotation axis  23 , for example in the direction of an arrow  27  ( FIG. 1 ), in order to generate an air flow. The undesirable vibration and noise resulting, for example, from an imbalance of fan  20 , are damped in this context by apparatus  30 , as described with reference to  FIG. 5 . 
       FIG. 2  is a front view of fan unit  10  of  FIG. 1  showing a further suspension member  23 ′; also illustrated is the installation of motor  21 , associated with fan  20  for driving fan wheel  24 , on a flange plate  38  mounted on air-guiding tube  22 , which plate is joined to air-guiding tube  22  via thin holding struts  29 ′ to  29   III . A bearing element  80 , for example a bearing tube, on which the rotor of motor  21  is journaled, is arranged on flange  38 . Element  80  is mounted on flange  38  with three screws  82 , of which only screws  82 ′ and  82 ″, are visible in  FIG. 2 . 
       FIG. 2  also shows the cable routing of connector lead  70 . The latter is routed from motor  21 , over flange  38  (where it is mounted on a holder  72 ) to the inner wall of tubular extension  50 , along it to an opening  52 , and through the latter outward in a radial direction. 
       FIG. 3  shows an embodiment in which securing members  55 , made of a soft plastic, are implemented as an integral component of tubular extension  50 , which latter at least partly surrounds carrier ring  40 . Carrier ring  40  has apertures  42 , of which only apertures  42 ′,  42 ″,  42   IV , and  42   V  are visible in  FIG. 3 ; and through which securing members  55  extend. 
     In  FIG. 3 , securing members  55  are implemented as support elements on which suspension members  23  are supported after fan unit  10  is assembled. Apertures  42  are preferably implemented in such a way that suspension members  23  at least partly engage therein, in order to ensure jamming or hooking into apertures  42 , and thus stable support on the associated support elements. 
     Securing members  55 , implemented as support elements, are implemented with groove-shaped cutouts  28  and reinforced side regions  31 ,  33 . For example, support element  23   VI  has a groove-shaped cutout  28   VI  and reinforced side regions  31   VI  and  33   VI . 
     As is apparent from  FIG. 3 , bearing element  80  has a further mounting element  82 ′″, and spring element  86  is arranged between a hollow-cylindrical portion  88 ′ and a collar  68 ″ of tubular extension  50 . Portion  88 ′ is joined to carrier ring  40 , and collar  88 ″ is joined to bracing ring  60 . Spring element  86  has a predetermined oscillation characteristic, in order to enable relative motion between carrier ring  40  and bracing ring  60 , for vibration damping and noise damping, and, in accordance with a first embodiment, is implemented as a curved, approximately S-shaped oscillation membrane. 
       FIG. 4  is a partly sectioned perspective view of fan unit  10 .  FIG. 4  illustrates, on the one hand, suspension members  23  supported on securing members  55  and, on the other hand, an annular shoulder  49  against which carrier ring  40  abuts. 
       FIG. 5  shows fan unit  10  arranged in a carrier part  15 . Carrier part  15  is made, for example, from foamed material such as that which is used to upholster a vehicle seat. Fan unit  10  can serve in this context to ventilate or heat the seat, the unit being recessed (as shown) into carrier part  15  in order to ensure a predetermined spacing between collar  88 ″ and a corresponding seat surface. 
       FIG. 5  furthermore shows motor  21  having a stator arrangement  37  and a circuit board  90  to which connector lead  70  is connected. Motor  21  can be implemented using any desired electronically commutated electric motor that is suitable for driving axial fan  20 , so that a detailed description of motor  21  can be dispensed with. 
       FIG. 5  illustrates, in particular, the suspension of air-guiding tube  22  in vibration- and noise-damping apparatus  30  by means of suspension members  23  supported on securing members  55 , only suspension members  23 ″ and  23   IV  supported respectively on securing members  55 ″ and  55   IV  being visible. These interact in such a way that oscillations of fan  20  are compensated for by relative motions of spring element  86  between carrier ring  40  and bracing ring  60 , so as thereby to produce efficient vibration damping and noise damping for fan unit  10 . Apparatus  30  has, for this purpose, a predetermined number of degrees of freedom in both the horizontal and the vertical directions. 
       FIG. 6  is a sectioned view of vibration- and noise-damping apparatus  30  in accordance with an embodiment.  FIG. 6  illustrates securing members  55 ′ to  55 ′″, provided on tubular extension  50 , which engage through apertures  42 ′ to  42 ′″ provided in carrier ring  40 .  FIG. 6  also shows an annular projection  97  provided on extension  50 , which projection engages into an annular groove  96 , provided on carrier ring  40 , in order to ensure a slip-proof join between carrier ring  40  and extension  50 . 
       FIG. 7  is a sectioned view of tubular extension  50  illustrating securing members  55 ′ to  55 ′″ provided-thereon, as well as annular projection  97  and annular shoulder  49 . 
       FIG. 8  is a perspective view of bracing ring  60 , which has a trough-formed deformation  62  to guide connector lead  70  of  FIG. 1 ; and  FIG. 9  is a perspective view of carrier ring  40  illustrating apertures  42 ′ to  42 ′″ provided therein. 
       FIG. 10  shows a tubular extension  50 ′ in accordance with a second embodiment, which is usable with vibration- and noise-damping apparatus  30  instead of extension  50  described above. In contrast to extension  50 , tubular extension  50 ′ comprises a modified spring element  86 ′ having a first circumferential bead  86 ″ that joins collar  88 ″ to cylindrical portion  88 ′, and having a second circumferential bead  86 ′″ provided in the upper (in  FIG. 10 ) region of portion  88 ′. As a result of circumferential beads  86 ″ and  86 ′″, extension  50 ′ has an oscillation characteristic that differs from that of the above-described extension  50  having the oscillation membrane. In other words, spring element  86  or  86 ′ can be configured in different ways, depending on the oscillation characteristic that is required. Many possible configurations of spring element  86  or  86 ′ are accordingly to be understood as part of the invention. 
       FIGS. 11 to 19  show another embodiment of a fan unit  110 . In this, components whose functionality corresponds to the functionality of components of fan unit  10  described with reference to  FIGS. 1 to 10  are given the same reference characters as components of fan unit  10 , but incremented by 100. The description of such components is accordingly not repeated below in every detail. 
       FIG. 11  shows, in a rear view, a second embodiment of a fan unit  110  having an axial fan  120  and a vibration- and noise-damping apparatus  130 . 
     Axial fan  120  corresponds substantially to axial fan  20  of the first embodiment having motor  21  shown in  FIG. 14 , but has a modified air-guiding tube  122 . The latter is approximately hollow-cylindrical, can be made from plastic or metal or any mixed form thereof and, as described with reference to  FIG. 13 , is joined to a suspension member  123  made of an elastomeric material. 
     Axial fan  120  of  FIG. 11  is arranged in vibration- and noise-damping apparatus  130 , associated with which are a first ring or carrier ring  140  for elastic suspension of fan  120 , a tubular extension  150  joined thereto for oscillation damping, and bracing ring  60 . Carrier ring  140 , tubular extension  150 , and bracing ring  60  are once again preferably implemented as a physical unit using multi-component technology, especially two-plastic technology, carrier ring  140  and bracing ring  60  being manufactured from a hard plastic and tubular extension  150  from a soft material. Carrier ring  140 , tubular extension  150 , and bracing ring  60  can be joined to one another as described above with reference to  FIG. 1 . 
     Spring element  86  ( FIG. 13 ) is provided on extension  150  for oscillation damping. Alternatively, extension  150  can be implemented with spring element  86 ′ described with reference to  FIG. 10 , or with similar spring elements having a predefined oscillation characteristic. 
     Several securing members  155 ′ to  155 ′″ (also referred to hereinafter as securing members  155 ), made of a hard plastic and arranged in lateral apertures  142 ′ to  142 ′″ (hereinafter also referred to as apertures  142 ) provided for them, are provided for securing suspension member  123 . Suspension member  123  is implemented as an annular carrier strip, as described with reference to  FIGS. 13 and 16 . 
       FIG. 12  is a front view of fan unit  110  of  FIG. 11  illustrating the installation of motor  21  on flange plate  38  that is mounted on air-guiding tube  122 , which plate is joined via holding struts  29 ′ to  29   III  to air-guiding tube  122 . Located in plate  38  is bearing element  80 , which is equipped with mounting elements  82 .  FIG. 12  illustrates an example of a cable routing for connector lead  70  via plate  38 , holder  72 , and opening  52 . 
       FIG. 13  shows an embodiment of the present invention in which securing members  155  are made from a hard plastic and are implemented as components of tubular extension  150 . They are arranged in apertures  142 , of which only apertures  142 ′ and  142 ′″, having securing members  155 ′ and  155 ′″ respectively, are visible in  FIG. 13 . 
     Securing members  155  are depicted in  FIG. 13  as hooks on which suspension member  123  is suspended after the assembly of fan unit  110 . These hooks are preferably implemented as components of carrier ring  140 , in such a way that suspension member  123  engages at least partly into apertures  142 . 
     Suspension member  123  is likewise secured in holding hooks  168 ′,  168 ″,  168 ′″,  169 ′,  169 ″,  169 ′″. These are provided on the outer circumference of carrier ring  140  and are manufactured from a hard plastic; for example as constituents of carrier ring  140 . In order to prevent sliding of suspension member  123  during the operation of fan unit  110 , stiffening members  143  and  145  are provided on said member; of these, only stiffening members  143 ″,  143 ′″,  143   V ,  143   VI ,  145 ′,  145 ″,  145 ′″,  145 ″, and  145   VI  are visible in  FIG. 13 . They are arranged respectively in the region of securing members  155  and of holding hooks  168 ′,  168 ″,  168 ′″,  169 ′,  169 ″,  169 ′″ in such a way that suspension member  123  is held therein in slipproof fashion. 
       FIG. 14  is a sectioned view of fan unit  110  in which axial fan  120  is installed in vibration- and noise-damping apparatus  130 .  FIG. 14  furthermore shows motor  21  with stator arrangement  37 . 
       FIG. 15  is a partly sectioned perspective view of fan unit  110 .  FIG. 15  illustrates on the one hand annular shoulder  49  provided on tubular extension  150 , against which shoulder carrier ring  140  abuts. On the other hand,  FIG. 15  illustrates the suspension of air-guiding tube  122  in vibration- and noise-damping apparatus  130  by way of suspension member  123  secured in securing members  155 , only securing member  155 ′″ being visible. 
     This suspension is further illustrated in  FIG. 16 , which omits any depiction of fan  120 . It is additionally evident from  FIG. 16  that tubular extension  150  abuts against carrier ring  140  or sits on it, without surrounding it. In this embodiment as well, however, tubular extension  150  can be implemented in such a way that it at least partly surrounds carrier ring  140 . 
       FIG. 17  is a sectioned view of tubular extension  150 , illustrating spring element  86  that is implemented as a curved, approximately S-shaped oscillation membrane. This element can alternatively be implemented, like the modified spring element  86 ′ described above with reference to  FIG. 10 , with circumferential beads  86 ″ and  86 ′″, or in another different fashion, depending on the oscillation characteristic that is required. 
       FIG. 18  is a perspective view of bracing ring  60 , which has a trough-formed deformation  62  for guidance of connector lead  70  of  FIG. 11 ; and  FIG. 19  is a perspective view of carrier ring  140  illustrating apertures  142 ′ to  142 ′″ provided therein, with securing members  155 ′ to  155 ′″ provided therein and implemented as hooks. 
     Many variants and modifications are, of course, possible within the scope of the present invention.