Patent Publication Number: US-6902373-B1

Title: Sheet metal exhaust adapter for draft inducers

Description:
BACKGROUND OF THE INVENTION 
   The present invention is directed to an exhaust adapter for use with a draft inducer of a high-efficiency furnace. More specifically, the present invention is a two-piece stamped metal exhaust adapter configured for attachment to the blower housing of a draft inducer such that the rectangular outlet of the blower housing can be coupled to a round exhaust pipe. 
   The need to heat structures to control the interior temperature has been a requirement for modern housing for a long time. One of the current popular methods to heat structures is with a furnace that burns either oil or natural gas. Due to the increasing cost of fossil fuels, the operating efficiency of furnaces has become a greater and greater concern. 
   One method of increasing the fuel efficiency of a burner within a furnace has been to utilize a blower to induce a draft through the furnace to draw the heated air and the products of combustion through a heat exchanger and exhaust them through an exhaust pipe. The blower includes an electric motor and impeller that create a source of negative air pressure such that the heated air and the products of combustion from the burner can travel through as tortured a path as possible to increase the amount of heat removed from the exhaust gases within the heat exchanger. The increase in the flow of air thereby increases the heat transfer and generating capacity of the burner by simultaneously using less fuel per BTU of heat generated. 
   The addition of a draft inducer to a furnace generates a rating of at least 80% fuel efficiency in a modern furnace. Thus, it is clearly a necessity to introduce a blower to a modern furnace to maintain minimum desired efficiency standards. 
   Since the introduction of a blower increases the overall cost of a furnace, it is important to manufacture and connect the blower assembly to the furnace in the most effective and efficient manner possible. One common type of blower motor assembly that is currently available is known as a “rectangular exhaust, flush mount blower assembly”. In this type of blower assembly, the blower housing is mounted flush to the furnace, which reduces the space requirement for the blower and provides for easier and more accurate mounting of the blower on the furnace. However, this type of blower assembly has the disadvantage of having a rectangular exhaust outlet. Therefore, to allow the customer to attach the blower assembly to a commonly used round exhaust pipe, a rectangular-to-round exhaust adapter must be used. Typically, the exhaust adapter is formed from cast aluminum, which is expensive to manufacture. 
   An attempt to address the cost of the exhaust adapter is to use an adapter made out of polymeric material. A polymer exhaust adapter is either injection molded or thermal formed. Polymer exhaust adapters have largely been disregarded because of the inherent problems associated with the use of plastics in the harsh operating environment in which the exhaust adapter is placed. Polymers that are able to withstand the harsh operating environment are very expensive, and even with the use of expensive engineering polymers, there still remains potential problems with durability. 
   The present invention solves the problems associated with currently available furnace blower motor assemblies with a novel and cost efficient solution. There has been an unrecognized but long felt need in the industry to solve the problems stated above. The present invention solves the above stated problems with an easy to manufacture and assemble solution that has eluded manufacturers for many years. 
   Accordingly, it is an object of the present invention to provide an exhaust adapter that is inexpensive to manufacture yet durable enough to withstand the harsh operating environment associated with a blower assembly. It is another object of the present invention to provide an exhaust adapter that can be easily attached to the blower housing before the blower housing has been mounted onto the furnace. It is yet another object of the invention to provide a simple, cost effective solution to provide a flush mounted blower assembly with an exhaust adapter to mate with a round exhaust pipe. 
   SUMMARY OF THE INVENTION 
   The present invention relates to an exhaust adapter formed from a two-piece construction of stamped steel members joined to each other. The exhaust adapter is configured to provide a transition from the rectangular blower outlet of a draft inducer to facilitate connection to a round exhaust pipe. The exhaust adapter includes a circular exhaust outlet that receives an end of the exhaust pipe for easy connection thereto. 
   The exhaust adapter includes a first section and a second section both formed from stamped metal members. The first and second sections of stamped metal mate with each other along a top seam and a bottom seam. Preferably, the first and second sections of the exhaust adapter can be joined to each other using conventional metal forming techniques, such as a clinch seam or a lap joint. 
   When the first and second sections of the exhaust adapter are joined to each other, the exhaust adapter defines an attachment flange that can be connected to the rectangular blower outlet of the blower housing. The attachment flange extends around the rectangular blower outlet and provides multiple points of attachment between the exhaust adapter and the blower housing. 
   The exhaust adapter further includes a transition section extending from the attachment flange to a circular outer rim. The transition section includes angled outer walls that create the transition from the rectangular blower outlet to the circular exhaust outlet. 
   In a first embodiment of the invention, the first and second sections of the exhaust adapter are joined to each other utilizing a clinch seam formed along both the top seam and the bottom seam of the exhaust adapter. The clinch seam is formed from upstanding flanges formed on both the first section and the second section, where one of the flanges is extended relative to the other flange and is bent over the adjacent flange to form a clinch seam. 
   In a second embodiment of the exhaust adapter of the present invention, one section of the exhaust adapter includes an upper attachment tab and a lower attachment tab that extend over desired portions of the opposite section of the exhaust adapter. The upper and lower attachment tabs are secured to the opposite section by utilizing either spaced welds or spaced toggle locks. In this manner, the first and second sections can be securely attached to each other after the sections have been formed utilizing conventional metal stamping techniques. 
   Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings illustrate the best mode presently contemplated of carrying out the invention. 
     In the drawings: 
       FIG. 1  is a perspective view of a blower housing of a draft inducer including the rectangular blower outlet with the exhaust adapter of the present invention installed thereon; 
       FIG. 2  is a front perspective view of the exhaust adapter mounted on the blower housing of the draft inducer; 
       FIG. 3  is a front perspective view of a first embodiment of the exhaust adapter; 
       FIG. 4  is an exploded perspective view of the first embodiment of the exhaust adapter showing the connections between the stamped metal sections; 
       FIG. 5  is a section view taken along line  5 — 5  of  FIG. 1  showing the joint created between the two sections of the exhaust adapter; 
       FIG. 6  is a front view of the exhaust adapter of the first embodiment of the invention; 
       FIG. 7  is a front perspective view illustrating the exhaust adapter of a second embodiment of the invention; 
       FIG. 8  is a front view of the exhaust adapter of the second embodiment of the invention; and 
       FIG. 9  is an exploded perspective view of the exhaust adapter of the second embodiment. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring first to  FIG. 1 , thereshown is a blower housing  10  that forms part of a blower assembly that is used to expel exhaust gases from a furnace or other similar heating device. The blower housing  10  includes a top mounting surface  12  having a central opening  14  for receiving the shaft of a drive motor (not shown) that is securely mounted to the top surface  12  by the mounting holes  16 . The drive motor of the blower assembly is not shown in the drawings for better illustration of the present invention. 
   The blower housing  10  includes a circular outer sidewall  18  that encloses a rotating impeller mounted to the drive motor shaft. Rotation of the impeller within the blower housing  10  creates a source of negative air pressure within the blower housing  10  to draw exhaust gases from the furnace and direct the exhaust gases out of a blower outlet  20  formed in the blower housing  10 . As shown in  FIG. 1 , the blower outlet  20  has a rectangular cross-section, as is typical with a rectangular exhaust/flush mount blower assembly. 
   The blower housing  10  includes a mounting flange  22  extending from the sidewall  18 . The mounting flange  22  includes a plurality of mounting holes  24  that allow the blower housing  10  to be securely attached to the top of a furnace or similar device. As can be seen in  FIG. 1 , the configuration of the blower housing  10 , including the mounting flange  22 , allows the blower housing  10  to be flush mounted with the top of a furnace, which allows the blower housing  10  to be more accurately mounted and positioned. 
   In the preferred embodiment of the invention, the blower housing  10  is formed from a stamped piece of metal that takes the form illustrated. The stamped metal blower housing shown in  FIG. 1  is a conventional design for a blower housing  10  and forms no part of the present invention. 
   As illustrated in  FIG. 1 , the blower assembly of the present invention includes an exhaust adapter  26  that is attached to the exhaust outlet  20  of the blower housing  10 . The exhaust adapter  26  provides a transition from the rectangular blower outlet  20  to a circular exhaust outlet  28 . As shown in broken lines in  FIG. 1 , the exhaust outlet  28  is configured to mate with a round exhaust pipe  30 . 
   Referring now to  FIG. 2 , the exhaust outlet  28  of the exhaust adapter  26  includes a circular outer rim  32  having an inner diameter approximately equal to the outer diameter of the exhaust pipe received by the exhaust outlet  28 . The outer rim  32  is formed as an extension of the transition section  34  which extends upward from an attachment flange  36 . The transition section  34  includes outer walls that extend upward and away from the blower housing  10 . The transition section  34  creates the transition from the rectangular blower outlet  20  of the blower housing  10  to the circular exhaust outlet  28 . 
   Referring now to  FIG. 3 , the attachment flange  36  of the exhaust adapter  26  includes a pair of spaced side flanges  38  and  40 , a top flange  42  and a bottom flange  44 . As can best be seen in  FIGS. 1 and 3 , the top flange  42  includes an attachment opening  45  and the side flanges  38  and  40  also include similar attachment openings  47 . The attachment openings  45  and  47  align with similar attachment openings formed in the blower housing  10  near the blower outlet  20  to allow the exhaust adapter  26  to be easily attached to the blower housing  10 . 
   As best illustrated in  FIGS. 1 and 3 , the exhaust adapter  26  is formed from a first, right section  46  and a second, left section  48  joined to each other along a top seam  50  and a bottom seam  52 . Preferably, both the first section  46  and the second section  48  are formed from stamped sections of metal. The formation of the first section  46  and the second section  48  from stamped metal greatly reduces the cost of forming the exhaust adapter  26 , as compared to prior art exhaust adapters that are formed from either die cast aluminum or expensive polymer materials. The use of stamped metal greatly reduces the material cost of the exhaust adapter and reduces the assembly time and cost as well. 
   As can best be seen in  FIGS. 4 and 6 , the first section  46  includes an upstanding lower flange  54  formed along its bottom edge. The lower flange  54  is positioned adjacent to a similar lower flange  56  formed on the second section  48 . The lower flange  56  formed on the second section  48  includes an extended section  58  that is bent over the outer edge  60  of the lower flange  54  to create a clinch seam between the first and second sections  46  and  48 . During the construction process of the exhaust adapter  26 , the bottom clinch seam  52  is formed using conventional metal working techniques. 
   Referring now to  FIG. 5 , the first section  46  of the exhaust adapter  26  includes an upstanding upper flange  62  that extends along the top seam of the exhaust adapter  26  from the attachment flange  36  to the outer rim  32 . As can be seen in  FIG. 1 , the opposite, first section  46  also includes an upper flange  64  that abuts against the upper flange  62  formed on the second section  48 . The upper flange  62  includes an extended portion  66  that is folded over the flange  64  to create the clinch seam. Referring to  FIG. 5 , the extended section  66  creates secure joint between the first section  46  and the second section  48  along the top seam  50 . As was discussed previously, the clinch seam is formed using conventional metal working practices and creates a secure joint between the two sections of the exhaust adapter  26 . 
   Referring back to  FIG. 1 , the second section  48  includes an overlap section  68  formed on the attachment flange  36 . The overlap section  68  is set off by an upward bend  70  such that the opening  46  formed in the overlap section  68  aligns with a corresponding opening  71  formed in the attachment flange  36  of the first section  46 , as shown in FIG.  4 . In this manner, both the first section  46  and the second section  48  can be securely attached to the blower housing  10 . 
   Referring now to  FIG. 7 , thereshown is a second embodiment of the exhaust adapter  72  of the present invention. The second embodiment of the exhaust adapter  72  includes a first, right section  74  and a second, left section  76  that are joined to each other to define the entire exhaust adapter  72 . When the first section  74  and the second section  76  are attached to each other, the combination creates an attachment flange  78 , a transition section  80  and a circular outer rim  82  that defines the circular exhaust outlet  84 . The different sections of the exhaust adapter  72  of the second embodiment of the invention shown in  FIG. 7  are identical to those shown in the first embodiment of the exhaust adapter  26  shown in FIG.  3 . However, the difference between the first embodiment of FIG.  3  and the second embodiment of  FIG. 7  is the method by which the first and second sections of the exhaust adapter are attached to each other to form the exhaust adapter. 
   As can be seen in  FIG. 7 , the exhaust adapter  72  includes a top seam  86  and a bottom seam  88 . The first section  74  and the second section  76  are joined to each other along the top and bottom seams  86  and  88 . 
   Referring now to  FIGS. 8 and 9 , the second section  76  includes a lower attachment tab  90  that extends over a mating protrusion  91  formed as a portion of the lower transition section of the first section  74 . As illustrated in  FIG. 9 , the attachment tab  90  extends past the bottom seam  88  and overlaps the lower protrusion  91  formed on the first section  74 . Referring back to  FIG. 8 , the protrusion  91  of the first section  74  is secured to the attachment tab of the second section  76  at a series of discrete locations  92  such that the two sections  74  and  76  are joined by the attachment tab  90 . In the preferred embodiment of the invention, the attachment locations  92  can be formed by a toggle lock or spot weld. 
   Referring back to  FIG. 9 , the second section  76  includes an upper attachment tab  94  that overlaps an upper protrusion  95  formed as part of the first section  74 . The upper attachment tab  94  is secured to the upper protrusion  95  formed on the first section  74  at a series of discrete locations  96 , as illustrated in FIG.  8 . Once again, the attachment locations  96  can be formed by a toggle lock or spot weld, or similar equivalent method of metal attachment. 
   As described in the above disclosure, the first and second embodiments of the exhaust adapter of the present invention are each formed from two separate, stamped sections of metal joined to each other along both a top seam and a bottom seam. The creation of the exhaust adapter from two sections of stamped metal is a dramatic improvement over the prior art. The use of stamped metal dramatically reduces the cost of production of the exhaust adapter compared to prior art cast aluminum exhaust adapters. The use of the two sections of stamped metal allow the exhaust adapter to be manufactured using relatively low cost materials while utilizing an inexpensive and rapid metal working techniques. 
   Although the present invention describes two methods of joining the two sections of the exhaust adapter to each other, it is contemplated by the inventor that other methods of joining two separate metal component could be utilized while operating within the scope of the present invention. Additionally, ultimate configurations for the shape and size of the exhaust adapter are also contemplated as being within the scope of the present invention. 
   Various alternatives and embodiments are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.