Abstract:
A blower for a furnace is provided with an exhaust flange having a compressible end portion, and a flexible fitting adapted to receive an exhaust pipe is insertable into an interior of the exhaust flange. A clamp compresses the compressible end portion about the flexible fitting and the exhaust pipe to secure the exhaust pipe to the blower. A drain may be provided adjacent the compressible end portion to remove condensate which may be entrained in the exhaust gases from the exhaust pipe, exhaust fitting and exhaust flange.

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     This invention relates to blowers used on high efficiency furnaces and, more particularly, to an exhaust interface formed on a discharge pipe of a blower housing. 
     (2) Background of the Invention 
     Blowers are commonly used in high efficiency furnaces (e.g. 90% efficiency) for drawing combustion air into the furnace and for removing exhaust gases from the furnace. Generally, these blowers are located downstream of a combustion chamber or combustion tubes in the furnace, depending upon the style of furnace, and propel exhaust gases out the furnace through an exhaust pipe that vents to outside atmosphere. 
     FIGS. 1 and 2 show the typical arrangement of a blower  20  of the prior art. The blower  20  includes a blower motor  22  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 an upstanding annular wall  28  extending between a top piece  30  and a bottom piece  32 . The top piece  30  is molded to include the center mount recess  26  to receive the blower motor  22 . The annular wall  28 , top piece  30 , and bottom piece  32  form a volute  34  for the blower housing  24 . An impeller  22 , operably connected to a shaft of the blower motor  22  rotates in the volute  34  when the blower  20  is energized to draw exhaust gases through an inlet hole (not shown) in the center of the bottom piece  32 . The gases are then compressed in the volute  34  and directed into a discharge pipe  36  that extends outward and away from the volute  34 . 
     FIG. 2 shows the general arrangement of the blower installed in a furnace  38 . The blower is mounted on a blower mounting surface  40  on the furnace  38  where the inlet hole (not shown) of the blower housing  24  is positioned to allow the impeller 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  42  using a double booted rubber gasket  46  to vent the exhaust gases to atmosphere. In the prior art, the blower housing  24  and exhaust pipe  42  are commonly made from a polypropylene or polyvinyl chloride (PVC) plastic material. 
     Greater detail of the double booted gasket  46  of the prior art is shown in FIG.  1 B. The double booted rubber gasket  46  is a cylindrically shaped tubular member with first and second ends  48 , 50 . The first end  48  has a first internal annular groove  52  that forms a first annular socket  54  that fits on a boss end  56  of the discharge pipe  36  of the blower housing  24 . To secure the double booted rubber gasket  46  to the discharge pipe  36  of the blower housing  24 , a first hose clamp  58  is typically used. The second end  50  of the double booted gasket  46  has a similar arrangement with a tubular insert  60  concentrically disposed within the gasket  46  to form a second internal annular groove  62 . The exhaust pipe  42  is received within the second internal annular groove  62  and is secured to the double booted gasket  46  by tightening a second hose clamp  64 . The second internal annular groove  62  has a groove root  66  with baffles  68  to collect condensate that is entrained in the exhaust gas stream. This condensate is collected at the root  66  and is removed from the double booted gasket  46  through drain portals  70  on the sides of the double booted gasket  46  that communicate with the groove root  66 . 
     The use of the double booted gasket  46  has several drawbacks. The double booted gasket  46  is a complex part that must be manufactured in an intricate molding process. Because the gasket  46  is an added part to be fitted between the blower housing  24  and the exhaust pipe  42 , it complicates the installation process. Further, as is readily apparent to those of skill in the art, a pair of pipe clamps must be aligned and screwed tight to complete the installation which takes some time and careful attention. The added part also increases the expense of the blower  20  and the installation of the blower  20  on the furnace  38 . 
     The double booted gasket  46  must also be made from a relatively strong material that must withstand industry standards for mechanical strength and exhaust system integrity. Generally, in this application on a high efficiency furnace, the double booted gasket  46  must be able to maintain its connection to the discharge pipe  36  with a 25 ft-lb torque exerted on the exhaust pipe  42  (the “twist” condition). The gasket  46  must also maintain its connection to the discharge pipe  36  with a 50 lb. parallel pull out force exerted axially along the exhaust pipe  42  (the “pull-out” condition). Because the double booted gasket  46  has one hose clamp connection with the discharge pipe  36  and another hose clamp connection with the exhaust pipe  42 , the double booted gasket  46  has two points for failure. Thus, the gasket  46  is susceptible to failure at either one of these two connections which represent the most likely point of failure. 
     What is needed in the art is a method of improving the connection between the blower housing  24  and the exhaust pipe  36  such that the industry standard mechanical tests for strength and exhaust system integrity are maintained while providing a less expensive part with an easier install procedure. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide an exhaust interface for a blower that simplifies the connection between the blower housing and the exhaust pipe while meeting the requisite industry standards for strength and exhaust system integrity. 
     The blower of the present invention includes a blower housing and a blower motor. The blower housing has an impeller and a discharge pipe for directing exhaust gases out and away from the blower. The discharge pipe has a first end that is formed adjacent the housing and an opposite second end that is spaced from the housing, or volute. The second end includes an exhaust flange with an annular socket and a plurality of resilient teeth extending axially outwardly from the second end and circumferentially spaced around the annular socket. 
     The blower includes an exhaust fitting that has an outer cylinder with a front end and an axially opposite back end, and a generally tubular insert disposed within the outer cylinder. An annular back wall extends between the outer cylinder and tubular insert. The tubular insert is attached to the annular back wall at the back end of the outer cylinder such that the tubular insert extends outward and away from the back wall and through the front end of the outer cylinder. The tubular insert forms an annular groove in the front end of the exhaust fitting. 
     The exhaust fitting is received in the annular socket of the exhaust flange, and the exhaust pipe is received in the annular groove. A clamping means such as preferably a pipe clamp for radially compressing the plurality of circumferentialy spaced teeth on the exhaust flange may be used to secure the exhaust pipe within the exhaust fitting and the exhaust fitting within the annular socket of the exhaust flange. 
     The exhaust fitting and exhaust flange are preferably keyed so that the exhaust fitting may be assembled in the annual socket on the exhaust flange in only one circumferential orientation. The exhaust flange preferably has an integral drain for removing condensate in the exhaust gases. In this configuration, the exhaust fitting may have a guttering system adjacent the back wall of the annular groove that directs condensate from the exhaust pipe into the drain on the exhaust flange. Preferably, each of the circumferentialy spaced teeth has a proximal end which is cantileverly attached to the second end of the discharge pipe and a distal end which is spaced away from the proximal end. The distal end of each of the teeth may have an annular ridge that extends radially outward and engages a portion of the clamping means to prevent the clamping means from sliding off the teeth when the clamping means is tightened around the teeth. The clamping means is preferably a pipe clamp, as in the prior art. The discharge pipe, exhaust flange, and volute of the blower housing are preferably monolithically constructed as the exhaust flange may be molded as a mold insert as the blower housing is molded. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEW 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 a perspective view of a blower housing of the prior art; 
     FIG. 1B is a cross-sectional side view of a double booted gasket of the prior art; 
     FIG. 2 is an exploded view of the blower and double booted gasket of the prior art; 
     FIG. 3 is an exploded view of a blower of the present invention; 
     FIG. 4 is a partial, front, perspective view of an exhaust fitting inserted into the blower housing of FIG. 3; 
     FIG. 5 is a top plan view of a blower housing of the blower of FIG. 3 with a partial, sectional view of an exhaust flange; 
     FIG. 6 is a rear, perspective view of the exhaust fitting of FIG. 4; and 
     FIG. 7 is a front, perspective view of an exhaust fitting of FIG.  4 . 
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 3 shows a blower  100  of the present invention in its arrangement in a furnace  101 . The blower  100  includes a blower motor  102  and a blower housing  104 . The blower housing  104  has an annular upstanding wall  106  extending between a top piece  108  and bottom piece  110 . The bottom piece  110  is mounted on a blower mounting surface  112  in the furnace  101 , or the furnace bonnet, and has a center hole (not shown) through which exhaust gases are drawn into the blower housing  104 . 
     FIGS. 4 and 5 provide greater detail of the blower housing  104 . The top piece  108  has an annular recessed area  114  adapted to hold the blower motor  102 . The top piece  108  has mounting screws  116  for securely fastening the motor  102  to the blower housing  104  and a through hole  118  to allow a shaft on the blower motor  102  to pass into the housing  104 . The blower motor shaft (not shown) is operably connected to an impeller (not shown) rotatably disposed within the blower housing  104 . The upstanding annular wall  106 , and top and bottom pieces  108 , 110  form a volute  120 . The blower housing  104  also includes a discharge pipe  122  for directing exhaust gases pressurized in the volute  120  out of the blower housing  104 . An outermost end  124  of the discharge pipe  122  has an exhaust flange  126  that allows the blower  100  to be connected to the exhaust pipe  42 . 
     The Figures show a blower housing  104  having a top piece  108  with the discharge pipe  122 , an upstanding wall  106 , and exhaust flange  126 , and a relatively flat, separate bottom piece  110 . It is also possible to construct the bottom piece with the upstanding annular wall, discharge pipe, and exhaust flange and a separate top piece that attaches to the bottom piece to enclose the blower housing. The bottom piece may also have the upstanding wall, discharge pipe, and exhaust flange constructed monolithically. The bottom piece may also be made from a polypropylene material. 
     FIG. 4 shows an exhaust fitting  128  of the present invention installed in the exhaust flange  126  to form an exhaust interface  130  for the blower  100  and the exhaust pipe  42 . The exhaust flange  126  is formed on the outermost end  124  of the discharge pipe  122  and has an outer cylinder portion  132  extending around the discharge pipe  122 . The outer cylinder portion  132  has a rear annular wall  134  that connects the outer cylinder portion  132  to the discharge pipe  122  and forms an internal shoulder  136  inside the outer cylinder portion  132  for the exhaust fitting  128  to rest against when the exhaust fitting  128  is installed in the exhaust flange  126 . The rear annular wall  134  and internal shoulder  136  are shown in the partial sectional view in FIG.  5 . The outer cylinder portion  132  has an inner diameter that is preferably larger than the bore of the discharge pipe  122 . This arrangement prevents a restriction in the discharge path of the exhaust gases when the exhaust fitting  128  is installed in the exhaust flange  126 . The rear annular wall  134  and outer cylinder portion  132  define an annular socket  138  on the end of the discharge pipe  122 . The annular socket  138  has an interior that is sized to receive the exhaust fitting  128  and prevent the exhaust fitting  128  from twisting out of the annular socket  138 . 
     As shown in FIGS. 4 and 5, the outer cylinder portion  132  of the exhaust flange  126  has an annular ridge  140 , and a plurality of axial slots  142  extending inwardly from the outermost edge  124  of the outer cylinder portion  132 . The slots  142  are circumferentially spaced around the annular socket  138  and form a plurality of resilient teeth  144 . Each of the teeth  144  has a proximal end  146  and distal end  148 . The proximal end  146  is cantileverly attached to the outer cylinder portion  132  so that the tooth  144  may flex radially inward into the annular socket  138 . The distal end of each tooth  148  includes a portion of the annular ridge  140  formed on the outermost edge  124  of the outer cylinder portion  132 . 
     To allow the teeth  144  to compress radially inward, the outermost edge of each of the slots  142  is wider than the portion of the slot  142  near the proximal edge of each tooth  144 . To provide a keying alignment between the exhaust flange  126  and the exhaust fitting  128 , a slot in the outer cylinder portion  132  is preferably widened to function as a key slot  150 . 
     Positioned between the outermost edge  124  of the outer cylinder portion  132  and the rear annual wall  134  is a drain  152 . The drain  152  extends outward and away from the outer cylinder portion  132  and communicates with the annular socket  138 . Preferably, the drain  152 , the outer cylinder portion  132  and the discharge pipe  122  are monolithically formed. 
     FIGS. 6 and 7 show the preferred embodiment of the exhaust fitting  128 . The exhaust fitting  128  has a first tube portion  154  and a second tube portion  156  with each tube portion  154 , 156  having first and second ends  158 , 160  and an annular side wall  162  extending between the first and second tube portions  154 , 156  at the first end  158 . Preferably, the second tube portion  156  is positioned concentrically within the first tube portion  154 . The arrangement of the first and second tube portions  154 , 156  and the annular side wall  162  create an annular groove  164  in the second end  160  of the exhaust fitting  128 . Preferably, the second tube portion  156  is axially longer than the first tube portion  154  such that the second tube portion  156  extends through the second end  160  of the first tube portion  154 . 
     The first tube portion  154  preferably has a circumferential slot  166  which is relieved through the annular side wall  162 . The slot  166  communicates with the annular groove  164 , and when the exhaust fitting  128  is installed in the exhaust flange  126 , the slot  166  ultimately communicates with the drain  152 . The first tube portion  154  has an outer surface  168  and a key  170  extending outward from the outer surface  168  that is received in the key slot  150  on the exhaust flange  126  when the exhaust fitting  128  is installed in the exhaust flange  126 . The key arrangement between the exhaust flange  126  and the exhaust fitting  128  ensures alignment and communication between the slot  166  and the drain  152  to ensure the removal of condensate entrained in the exhaust gas. Preferably, a plurality of stops  172  are circumferentialy spaced around the inside of the annular groove  164 . The stops  172  are arranged in the annular groove  164  to permit communication around the groove  164  and into the slot  166  and drain  152 . The stops  172  hold the end of the exhaust pipe  42  off the bottom of the annular groove  164 , when the exhaust pipe  42  is installed in the exhaust fitting  128 . This arrangement permits condensate forming in the exhaust pipe to collect in the annular groove  164 , flow to the slot  166 , and out of the exhaust system via the drain  152 . 
     The first tube portion  154  preferably has a circumferential lip  174  extending radially outward on its outer surface  168  on the first end  158 . The lip  174  functions as a positive stop to abut the circumferential ridge  140  on the outer cylinder portion  132  of the exhaust flange  126  when the exhaust fitting  128  is installed in the exhaust flange  126 . The outer surface  168  of the first tube portion  158  is sized to be slidingly received in the annular socket  138  of the exhaust flange  126 . When the exhaust fitting  128  is installed in the exhaust flange  126 , the annular side wall  162  of the exhaust fitting  128  preferably abuts the internal shoulder  136  in the annular socket  138  of the exhaust flange  126 . The depth of the annular socket  138  provides proper support for the exhaust fitting  128 . 
     During installation of the blower  100  in the furnace  101  and connection of the blower  100  to the exhaust pipe  42 , the blower  100  may be attached to the blower mounting surface  112  and the exhaust fitting  128  may be inserted into the exhaust flange  126 . Preferably, the exhaust fitting  128  is assembled with the exhaust flange  126  in only one orientation using the key  170  and key slot  150  arrangement on the exhaust interface  130 . Once the exhaust fitting  128  is inserted in the exhaust flange  126 , the exhaust pipe  42  may be inserted into the annular groove  164  such that the exhaust pipe  42  rests upon the stops  172  inside the annular groove  164 . A clamping means  176 , such as band clamp or common hose clamp, may be installed around the circumferentialy spaced teeth  144  on the outer cylinder portion  132 . The clamping means  176  may then be tightened, radially deflecting the teeth  144  inward to compress the teeth  144  against the outer surface  168  of the first tube portion  154  and the exhaust pipe  42 . 
     Because the exhaust fitting  128  is preferably made from a rubber material, the pressure exerted from the teeth  144  may be transmitted directly to the exhaust pipe  42  to ensure a tight fit. The size and length of the annular socket  138  and the annular groove  164  allow the exhaust interface  130  to meet the industry standards for torque and parallel force failure. 
     In operation, condensate entrained in the exhaust gases is collected in the annular groove  164  provided in the exhaust fitting  128  and is directed to the slot  166  where it is removed to the appropriate collection facility in the furnace  101 . 
     As will be appreciated by those skilled in the art, the exhaust interface  130  of the present invention is less complex than the prior art and uses less parts, thus decreasing the cost of the blower  100 . The exhaust flange may be formed with a die insert that is installed in the mold when forming the conventional blower. 
     Although a band clamp is shown as the clamping means  176  to radially compress the teeth  144  inward to secure the exhaust pipe  42  in the exhaust fitting  128  and the exhaust fitting  128  in the exhaust flange  126 , other clamping means may be used. The clamping means may include a ring which is threadably attached to the outer cylinder portion of the discharge pipe. The ring may be rotated and tightened so as to compress the teeth radially inward. The clamping means may also include a hose clamp or other strap clamp which is tightened by tangential force exerted on the strap. 
     As various changes could be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in any limiting sense. The invention therefore shall be solely limited by the scope of the claims set forth below.