Abstract:
A blower housing having a resilient bottom piece and a rigid top piece assembling with the bottom piece is provided. The top piece includes a plurality of depending legs which are urged against a matching plurality of flanges formed in the resilient bottom piece to cushion mount the top piece to a furnace or the like. A plurality of mechanical fasteners such as screws or the like extend through a plurality of lugs on the top piece and through the flanges to urge the depending legs against the flanges and the furnace. Through this construction, a generally rigid connection between the motor mounting plate and the furnace is achieved while providing the sound and vibration attenuation of a resilient housing.

Description:
RELATED APPLICATION DATA 
     This application is a continuation-in-part of application Ser. No. 09/651,643, filed Aug. 30, 2000, now U.S. Pat. No. 6,435,818 . 
    
    
     BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The invention relates to blowers for high efficiency furnaces for drawing combustion gases into the furnace and propelling the products of combustion into the exhaust pipe to be vented to atmosphere. More specifically, the invention relates to the construction of the blower housing. 
     (2) Description of the Related Art 
     Blowers to which the present invention is directed are common in the art. The blower is used on high efficiency furnaces (e.g. 90% efficiency) to draw combustion air into the furnace from outside the home. Generally, these blowers are located downstream of a combustion chamber or combustion tubes in the furnace, depending upon the style of furnace. Combustion air is drawn into the combustion chamber or combustion tubes, mixed with fuel, and ignited to generate heat for the furnace. The exhaust gases are then drawn into the suction of the blower and discharged from the blower to an exhaust pipe that vents to outside atmosphere. 
     FIG. 1A shows a blower  20  of the prior art arranged on a blower mounting surface  21  of a furnace  23 . The blower  20  includes a blower motor  47  and a blower housing  24 . In FIG. 1A, the blower motor has been removed from its center mount  26  on top of the blower housing  24  to show greater detail of the blower housing  24 . The blower housing  24  has a side wall  28  extending between a top piece  30  and a bottom piece  32 . Locator surfaces  33 A, 33 B are provided on the top and bottom pieces  30 , 32  to align the top and bottom pieces  30 , 32 . The locator surfaces  33 A, 33 B also form a seal between the top and bottom pieces  30 , 32  to contain exhaust gases within the blower housing  24 . The top piece  30  is molded with the center mount  26  recessed to receive the blower motor  47 . The side wall  28 , top piece  30 , and bottom piece  32  form a volute  34  for the blower housing  24 . When the blower  20  is energized, an impeller (not shown), operably connected to a shaft of the blower motor , rotates in the volute  34  to draw exhaust gases through an inlet hole  35  in the center of the bottom piece  32  and to compress gases in the volute  34 . The pressurized exhaust gases are directed into a discharge pipe  36  that extends outward and away from the blower  20  and the furnace  23 . Mounting feet  38  for attaching the blower  20  to the blower mounting surface  21  of the furnace  23  are provided on the side wall  28  of the blower housing  24 . 
     FIG. 1B shows the blower  20  arranged on the blower mounting surface  21  in the furnace  23 . The blower housing  24  is positioned to allow the impeller (not shown) to draw exhaust gases directly from the combustion chamber or combustion tubes (not shown) into the blower housing  24 . The discharge pipe  36  is coupled to an exhaust pipe  39  using a gasket  40  to vent the exhaust gases to atmosphere. The top piece  30  is attached to the blower mounting surface  21  using mechanical fasteners  41  through holes  42  on the mounting feet  38 . The mechanical fasteners  41  have a screw head driving end  43  and an opposite driven end  44  spaced from the driving end  43  by a shaft  45 . The screw head driving end  43  engages a seating surface  46  on the mounting foot  38  and holds the top piece  30  onto the blower mounting surface  21 . The bottom piece  32  is preferably held in position between the top piece  30  and the blower mounting surface  21  by compression from the mechanical fasteners  41 . 
     Typically, the impeller rotates at a high rate of speed to generate sufficient air flow into the combustion chamber and combustion tubes and to draw the exhaust gases out into the exhaust pipe  39 . As shown in FIG. 1B, the blower motor  47  is positioned directly atop of the blower housing  24  and the shaft (not shown) of the blower motor  47  is directly coupled to the impeller (not shown) in the blower housing  24 . The high speed rotation of the impeller and the motor  47  tends to create noise and other vibrations that are transferred directly into the blower housing  24 . As shown in FIG. 1B, the blower  20  is directly mounted onto the blower mounting surface  21  of the furnace  23 . Therefore, noise and vibrations are transmitted directly to the blower mounting surface  21  in the furnace  23 . This vibration results in unwanted noise being transmitted into the associated structures of the furnace  23  such as ducting where the noise can be transmitted throughout the house. The vibration also contributes to a decreased life span of the blower  20 . 
     In the prior art to combat these problems, the installation of the blower housing onto the furnace mounting surface generally involved installing cushioning mounts  48  and other vibration absorbing gaskets between the blower housing  24  and the blower mounting surface  21 . This technique complicates installation and causes a small air gap between the blower housing and the blower mounting surface. Often, the impeller or motor shaft must be dynamically balanced to reduce vibration; however, this process adds manufacturing cost. 
     What is needed to overcome the disadvantages of the prior art is to form a blower housing which has sound dampening qualities integrally formed in the housing to reduce noise and vibration transmitted from the motor and impeller into the blower mounting surface. Such a blower housing would have the vibration absorbing material integrally formed in the housing so that gaskets and other additional cushioning devices are not needed. Moreover, such a blower housing needs to be sufficiently sturdy to withstand high temperature exhaust gases passing through it. 
     SUMMARY OF THE INVENTION 
     In order to overcome the disadvantages of the prior art, the blower of the present invention includes a blower housing having a resilient bottom piece and a rigid top piece covering over the bottom piece to enclose an interior of the blower housing. The bottom piece of the blower housing is preferably cylindrically shaped and directly abuts the exterior mounting surface of the furnace with cushioned mounting flanges provided. The top piece of the blower housing is secured to the bottom piece and also provides the support for mounting the blower motor as explained below. 
     The bottom piece of the blower housing may be made from a vibration dampening material. Preferably, materials such as sanoprene and viram are suitable for dampening and attenuating vibrations and withstanding the heat from the products of combustion which flow through the blower housing. The top piece of the blower housing may be made from a material such as polypropylene to provide a rigid mount for the blower motor and with what may preferably be integrally formed depending mounting legs, the rigid mount for the motor extends to the furnace housing as explained below. 
     The top piece of the blower housing includes an annular central lower support portion for supporting the blower motor and an annular upper portion extending above and around the lower portion. The upper portion of the top piece of the blower housing has an outer peripheral edge and preferably a plurality of lugs extending outwardly beyond the outer peripheral edge. The bottom piece of the blower housing has preferably a plurality of flanges that align with the lugs when the blower housing is assembled. The flange interlocks with the lug to detachably engage the top piece to the bottom piece. The top piece, side wall and bottom piece form a volute for the blower housing. 
     The lugs on the top piece have a lug hole to receive a mechanical fastener such as a screw or bolt and provide the surface against which the mechanical fastener is snugged as it is tightened to mount the blower. The flanges on the bottom piece preferably have flange holes that receive the mechanical fasteners therethrough as the mechanical fasteners join the top piece to the blower mounting surface of the furnace. The mechanical fasteners preferably attach the blower housing to a blower mounting surface of the furnace such that the blower housing is positioned between a blower motor and an exterior mounting surface of the furnace. 
     To provide further structural integrity to the top and bottom pieces when the housing is assembled, the lugs on the top piece are preferably provided with a depending leg. The depending leg extends downwardly and away from the outer peripheral edge of the top piece and is received and cushioned in an associated flange hole. The mechanical fasteners thus are inserted through the lugs, beneath the depending legs, through the flange holes, and into the furnace to mount the blower housing. Thus the rigid mount for the motor is achieved while being cushioned by the cushioning flanges of the bottom piece. 
     The blower housing of the present invention may be installed on a furnace without the use of sound absorbing or other vibration dampening devices separate from the actual blower housing materials themselves and yet provide a relatively vibration and noise free installation. The blower housing of the present invention eliminates the need for balancing of the motor shaft and/or impeller to reduce undesirable vibrations. 
    
    
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
     Further objects and features of the invention are revealed in the following detailed description of the preferred embodiment of the invention and in the drawings wherein: 
     FIG. 1A is an exploded, perspective view of a blower of the prior art; 
     FIG. 1B is a side view of the blower of the prior art installed on a mounting structure of a furnace; 
     FIG. 2 is a side view of a blower of the present invention installed on the mounting structure of the furnace; 
     FIG. 3 is a perspective view of a blower housing of the blower of FIG. 2; 
     FIG. 4 is a top, perspective view of a top piece of the blower housing of FIG. 3; 
     FIG. 5 is a bottom, perspective view of the top piece of FIG. 4; 
     FIG. 6 is a top, perspective view of a bottom piece of the blower housing of FIG. 3; 
     FIG. 7 is a bottom, perspective view of the bottom piece of FIG. 6; 
     FIG. 8 is a cross-sectional view of the top piece installed with the bottom piece to form the blower housing of FIG. 3; and 
     FIG. 9 is a cross-sectional view of the top piece installed with the bottom piece to form the blower housing of FIG.  3 . 
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 2 shows the blower of the present invention installed in a furnace. The blower  50  includes a blower motor  52  and a blower housing  54 . The blower housing  54  has an annular upstanding wall  56  extending between a top piece  58  and bottom piece  60 . The bottom piece  60  is mounted on a blower mounting surface  21  in the furnace  23 , or the furnace bonnet, using mechanical fasteners  41 . The driving end  43  of each of the fasteners  41  seats against the top most portion of top piece  58  and the driven end  44  is installed in the blower mounting surface  21  on the furnace  23 . In the arrangement shown in FIG. 2, the bottom piece  60  is preferably held in position between the top piece  58  and the blower mounting surface  21  by compression from the mechanical fasteners  41 . 
     As shown in FIG. 2, the blower  50  is mounted on a blower mounting surface  21  on the furnace  23  where the blower housing  54  is positioned to allow the impeller (not shown) to draw exhaust gases directly from the combustion chamber or combustion tubes (not shown) into the blower housing  54 . A discharge pipe  61  is coupled to an exhaust pipe  62  using a gasket  64  to vent the exhaust gases to atmosphere. 
     FIG. 3 shows a perspective view of the blower housing  54  with top piece assembled on the bottom piece  60 . The top piece  58  covers over the bottom piece  60  to tightly enclose the blower housing  54  and prevent exhaust gases from leaking from the blower housing  54  during operation. The top piece  58  has a lower portion  66  that is recessed into the top piece  58  and extends into the blower housing casing  54 . The diameter of the recessed lower portion  66  is sized to accommodate the blower motor  52 . The lower portion  66  has mounting fittings  68  for securing the blower motor to the top piece  58 . The lower portion  66  may also have screw fittings  70  for securing the motor to the top piece  58 . At the center of the lower portion  66 , a through hole  72  is provided to allow a shaft (not shown) from the blower motor to pass into the interior of the blower housing  54  to be coupled with the impeller (not shown). The top piece  58  has an upper portion  74  which extends around and above the lower portion  66  and includes a seating surface  76  for the mechanical fasteners  41 . 
     FIGS. 4 and 5 provide greater detail of the top piece  58 . The upper portion  74  of the top piece  58  has an outer peripheral edge  78  and lugs  80  extending radially outward beyond the outer peripheral edge  78 . The lugs  80  preferably have arcuate lug holes  82  formed therein to allow minor positioning of the blower housing  54  on the blower mounting surface  21  of the furnace  23  when the blower  50  is installed on the furnace  23 . Preferably, each of the lugs  80  has a depending leg  84  extending downward and away from the outer peripheral edge  78  of the top piece  58 . Each leg  84  preferably has an exterior surface  86  and an arcuate interior surface  88  which gives each leg  84  a generally concave aspect when it is installed on the blower housing  54 . The arcuate interior surface  88  of the depending leg  84  preferably has a circumferential guide portion  90  that conforms to the upstanding annular wall  56  on the bottom piece  60 . The circumferential guide portion  90  on the depending leg  84  supports and aligns the top piece  58  with the bottom piece  60  during operation. The depending leg  84  bears some of the weight of the blower motor when the blower  50  is installed on the blower mounting surface  21  of the furnace  23 . 
     As shown in FIG. 5, an annular locating groove  92  is provided around the upper portion  74  radially inward of the outer peripheral edge  78 . The annular locating groove  92  is positioned a sufficient distance away from the outer peripheral edge  78 , lug hole  82 , and depending leg  84  to so as not to interfere with the seal between the top piece  58  and bottom piece  60  when the blower housing  54  is assembled. Greater detail of the annular locating groove  92  and seal between the top and bottom pieces  58 , 60  will be discussed later with reference to FIG.  8 . 
     FIGS. 6 and 7 provide detail of the bottom piece  60  of the blower housing  54 . The bottom piece  60  has a bottom disk portion  94  with a center inlet hole  95  that allows the blower  50  to draw exhaust gases into the housing  54  during blower operation. The bottom disk portion  94  has an outer perimeter border  96  and the upstanding annular wall  56  extends outward and away from the outer perimeter border  96 . The underside of the bottom disk portion  94  of the blower housing  54  is generally flat so that it may be mounted flush against the blower mounting surface  21  of the furnace  23 . The upstanding annular wall  56  has an interior surface  98  which defines a portion of a volute  100  of the blower housing  54  and an exterior surface  102  that surrounds the interior surface  98 . The discharge pipe  61  extends outward and away from the annular wall  56  and communicates with the volute  100  to direct pressurized exhaust gases from the blower housing  54 . The discharge pipe  61  may have a boss end  105  to allow connection to the exhaust pipe  62 , as required. Preferably, the bottom disk portion  94 , the upstanding wall  56 , and the discharge pipe  61  are formed monolithically. 
     The bottom piece  58  is provided with a plurality of mounting flanges  106  circumferentially spaced around the outer perimeter border  96  of the bottom disk portion  94 . Each of the mounting flanges  106  extends radially outward from the outer perimeter border  96  and has a flange hole  108  therethrough. Each of the mounting flanges  106  preferably aligns with a corresponding lug  80  on the top piece  58 . The alignment of the lugs  80  and flanges  106  may be such that the top piece  58  and bottom piece  60  are assembled in only one orientation. Similar to the lug hole  82 , the flange hole  108  is also preferably arcuate to allow minor adjustment of the blower  50  when the blower  50  is mounted on the blower mounting surface  21  of the furnace  23 . To maximize the diameter of the upstanding annular wall  56 , an inner edge  110  of the flange hole  108  may be formed flush with the exterior surface  102  of the upstanding annular wall  56 . 
     Preferably, the flange hole  108  is also formed to receive the depending leg  84  of the top piece  58  when the blower  50  is assembled. As shown in FIG. 9, the flange hole  108  preferably has a step recess  112  which is shaped to receive the depending leg  84  from the lug  80  of the top piece  58  and a through hole  113 . The through hole  113  allows the mechanical fastener to be directed from the lug  80  and lug hole  82  on the top piece  58  to the blower mounting surface  21  on the furnace  23  when the blower  50  is secured to the blower mounting surface  21  on the furnace  23 . The step recess  112  positively aligns the depending leg  84  and captures a bottom portion of the circumferential guide portion  90  of the depending leg  84  so that the top piece  58  and bottom piece  60  remain positively engaged during operation of the blower  50 . It is preferred that the bottom piece  60  be held in position by the compressive forces exerted by the mechanical fastener  41  on the top piece  58 . The step recess  112  bears some of this compressive force and stabilizes the position of the bottom piece  60  adjacent the blower mounting surface  21  of the furnace  23 . 
     Details of the attachment between the top and bottom pieces are best shown in FIG.  8 . The upstanding annular wall  56  of the bottom piece  60  has an upper section  114  that cooperates with the annular groove  92  in the upper portion  74  of the top piece  58 . The upper section  114  includes an annular end  116  that extends between the interior and exterior surfaces  98 , 102  of the upstanding wall  56 . The annular end  116  has a lip  118  extending axially outward from the bottom disk portion  94  intermediate the coterminous edges of the annular end  116  and the interior and exterior surfaces  98 ,  102  of the upstanding annular wall  56 . Preferably, the annular lip  118  has a triangular shaped cross section to allow a locking-type fit between the top and bottom pieces  58 , 60 . The upper section  114  also includes an annular notch  120  extending around the interior surface  98  of the upstanding wall  56 . 
     The annular groove  92  formed in the upper portion  74  of the top piece  58  includes a primary groove  122  and a secondary groove  124 . The primary groove  122  includes an annular inner side wall  126  and an annular outer side wall  128  spaced apart from the annular inner side wall  126  by an annular groove wall  130 . When the top piece  58  is installed on the bottom piece  60 , the annular inner side wall  126  abuts the interior surface  98  of the upstanding annular wall  56 , and the annular outer side wall  128  faces the exterior surface  102  of the upstanding annular wall  56 . The annular outer side wall  128  may be formed with a lead-in taper  132  to allow the top and bottom pieces  58 , 60  to more easily fit together. 
     The primary groove  122  also includes an annular rib  134  axially spaced below the annular groove wall  130 . The annular rib  134  cooperates with the annular notch  120  in the upstanding annular wall  56  of the bottom piece  58  to form a first sealing area  136  for the blower housing  54 . When the top piece  58  is fully installed on the bottom piece  60 , the top piece  58  will snap fit onto the bottom piece  60  as the annular rib  134  slides across the interior surface  98  of the upstanding annular wall  56  and into the annular notch  120 . The rib  134  and notch  120  provide a positive lock indication for a blower assembly operator when assembling the blower housing  54  during manufacture. 
     The secondary groove  124  in the annular groove  92  on the upper portion  74  of the top piece  58  is formed internal to primary groove  122 . The secondary groove  124  is formed intermediate the coterminous edges of the annular groove wall  130  and inner and outer side walls  126 , 128 . The secondary groove  124  has a triangular shaped cross section that matches the geometry of the annular lip  118  on the upstanding wall  56  of the bottom piece  60 . The secondary groove  124  provides a secondary sealing area  138  for the blower housing. 
     In assembling the blower housing  54  into the arrangement shown in FIG. 3, the top piece  58  may be installed with the bottom piece  60  to create the blower housing  54  of the present invention. The upper section  114  of the annular wall  56  of the bottom piece  60  may be inserted into the annular groove  92  on the underside of the top piece  58  and positively locked in place to seal the blower housing  54 . 
     The depending legs  84  of the lug  80  of the top piece  58  may be inserted into the step recess  112  formed in the flange hole  108  such that the circumferential guide portion  90  of the interior arcuate surface  88  of the depending lug  84  mounts flush against the exterior surface  102  of the upstanding annular wall  56  of the bottom piece  60  and a bottom portion of the leg  84  is nested within the recess  112  of the flange hole  108 . Preferably, the lengths of the depending legs  84  are sized such that when the upper section  114  of the annular wall  56  is fully inserted into the annular groove  92  in the top piece  58 , the leg  84  is captured by the flange hole  108 . The lugs  80  and matching flanges  106  may have irregular angular placement along each of the respective top and bottom pieces  58 , 60  to provide a keying assembly for the blower housing  54  such that the top and bottom pieces  58 , 60  may be assembled in only one orientation. 
     Each of the top and bottom pieces  58 , 60  may be formed from materials that are capable of withstanding relatively high temperatures from the exhaust gases being expelled from the blower housing  54 . To provide vibration dampening capability, the bottom piece may be made from viram or sanoprene. The top piece of the blower housing may be constructed from a polypropylene material that is sufficiently rigid and sturdy to prevent deformation under the weight of the blower motor during high temperature operation. Polypropylene is sufficiently rigid and does not require any stiffening panels as might be otherwise required should the entire blower housing itself be made from a rubber material. The polypropylene is also sufficiently rigid to prevent misalignment of the impeller during high temperature operation of the blower and furnace. 
     Although the Figures shows the bottom piece formed with the upstanding wall and discharge pipe extending from the upstanding wall, the top piece may be formed with an upstanding wall and the discharge pipe extending from the upstanding similar to blower housing shown in FIG.  1 A. Similarly, each of the top and bottom pieces may have a portion of the upstanding wall and a portion of the discharge pipe formed therein. The primary consideration for forming the bottom piece of a resilient material is to provide vibration dampening material between the motor and the blower mounting surface of the furnace. The blower must also be constructed in such a way to resist deformation by the weight of the motor during high temperature operation so that the radial clearance between the impeller and the bottom piece is maintained. 
     As is apparent to those skilled in the art, by locating the lugs  80  on the upper portion  74  of the blower housing  54 , the diameter of the upstanding annular wall  56  can be increased. By moving the driving end of the mechanical fastener  40  above the lug  80  on the top piece  58 , the clearance between the screw head driving end  42 , its slot, and the upstanding annular wall  56  of the blower housing  50  can be eliminated. The mechanical fastener  40  used to secure the blower housing to the blower mounting surface of the furnace may run directly down the exterior surface  102  of the upstanding annular wall  56  because there is sufficient clearance on the upper portion  74  of the top piece  58  for the screw head driving end  42  of the mechanical fastener  40 . 
     Additionally, since the top piece  58  snap fits with the bottom piece  60  to create a sealed unit, the blower housing more effectively contains exhaust gases. By locating the lugs  80  on the outer peripheral edge  78  of the upper portion  74  of the top piece  58 , the upper portion  74  of the top piece  58  may flex inward such that the normally tapered outer side wall  128  of the primary groove  122  contacts the exterior surface  102  of the upstanding wall  56 . Thus, the combination of the primary seal  136  and internal secondary seal  138  provides improved sealing characteristics for the blower housing  54  not found in the prior art. 
     Although the description of the blower housing presented herein refers to primary and secondary seals formed on respective portions of the top and bottom pieces, it should be noted that the location and combination of the components comprising the primary and secondary seals may reversed and positioned on the other of the top and bottom pieces of the blower housing. 
     By constructing the bottom piece of the blower housing with a sound dampening material, excessive noise and vibration being transmitted by the blower motor and impeller is dampened and attenuated before reaching the blower mounting surface of the furnace. This prevents the noise from being transmitted into associated duct work throughout the house. The lower noise and vibrations increases the life of the blower. 
     Various other changes to the preferred embodiment of the invention described above may be envisioned by those of ordinary skill in the art. However, those changes and modification should be considered as part of the invention which is limited only by the scope of the claims appended hereto and their legal equivalents.