Motor/damper assembly for fuel-fired water heater

The present application claims the benefit of the filing date of provisional U.S. patent application No. 61/379,026 filed Sep. 1, 2010. The entire disclosure of the provisional application is hereby incorporated herein by this reference.

In representatively illustrated embodiments thereof, this invention provides specially designed motor/damper apparatus for a fuel-fired liquid heating apparatus, such as a fuel-fired water heater, and a liquid heating apparatus operatively incorporating the motor/damper apparatus.

The primary purpose of the present invention is to improve the performance, construction and appearance of a motorized damper assembly used in conjunction with a fuel-fired water heater or other type of fuel-fired liquid heating apparatus such as, for example, a fuel-fired boiler. Traditional motorized flue damper assemblies, particularly for commercial fuel-fired water heaters, are constructed as two separate units comprising a drive system and an associated damper plate joined together by a steel channel such that the damper plate portion of the assembly is cantilevered from the drive system.

This conventional motor/damper assembly tends to be bulky and not particularly well suited, either from a structural or aesthetic standpoint, for residential water heaters. Some of the structural problems present in this conventional motor/damper assembly design include skewing of the damper plate that creates misalignment of and leakage around the damper plate, bending of the motor shaft or rod in shipping and handling, and providing the motor/damper assembly with a less than aesthetically pleasing appearance when installed on a residential water heater.

A need thus exists for an improved motor/damper assembly which eliminates or at least substantially alleviates these problems, limitations and disadvantages commonly associated with motor/damper assemblies of the conventional type generally described above. It is to this need that the present invention is primarily directed.

FIG. 1 is a perspective, partially cut away view of a top end portion of a representative fuel-fired water heater on a top end surface of which a motor/damper assembly embodying principles of the present invention is mounted;

FIG. 2 is a view similar to that in FIG. 1 , but with the motor/damper assembly removed from the water heater and shown in exploded perspective form;

FIG. 3 is an enlarged scale exploded perspective view of the motor/damper assembly;

FIG. 4 is an enlarged scale cross-sectional view through the motor/damper assembly taken generally along line 4 - 4 of FIG. 1 ; and

FIG. 5 is a partially cut away side elevational view of the motor/damper assembly, and an upper end portion of the water heater, taken generally along line 5 - 5 of FIG. 1 .

As illustrated in the accompanying FIGS. 1-5 , this invention provides a specially designed motor/damper assembly 10 which embodies principles of the present invention and is mountable on the top end surface 12 of the insulated hot water storage tank portion 14 of a fuel-fired water heater 16 . Alternatively, the motor/damper assembly 10 could be utilized in conjunction with other types of fuel-fired liquid heating apparatus such as, for example, fuel-fired boilers. Representatively, the fuel-fired water heater 16 is a residential water heater, but could also be a commercial water heater.

Water storage tank portion 14 (see FIGS. 1 and 5 ) includes a vertically oriented cylindrical water storage tank 18 surrounded by a suitable insulation material 20 which, in turn, is surrounded by a metal jacket 22 . Extending upwardly from the top end surface 12 of the storage tank portion 14 is a tubular exhaust flue 24 (see FIGS. 2 and 4 ) having an open upper end 26 . During firing of the water heater 16 , combustion exhaust products (not shown) are upwardly exhausted through the flue 24 . Also projecting upwardly from the top end surface 12 of the storage tank portion 14 are a cold water inlet pipe 28 and a hot water outlet pipe 30 (see FIGS. 1, 2 and 5 ) 32 operatively coupled to the tank 18 .

The motor/damper assembly 10 , as later discussed herein, provides several advantages over conventional motor/damper assemblies, and includes a metal support plate structure 32 (see FIGS. 2-4 ) having a rectangular base plate portion 34 , an end plate 36 portion projecting upwardly from an end edge of the base plate portion 34 , and a pair of side plate portions 38 , 40 projecting upwardly from opposite side edges of the base plate portion 34 . Mounted on the outer side of the end plate 36 , in an elevated relationship with the base plate 34 , is an electric motor 42 . The inner end of a horizontally oriented drive shaft 44 is drivably coupled to the motor 42 . As schematically depicted in FIG. 2 , the motor 42 may be incorporated in a damper control module having suitable control electronics therein which are operatively associated with the motor 42 .

At the right end of the base plate 34 is an upstanding tubular collar 46 having an open lower end portion 48 complementarily received and welded within a corresponding circular opening 50 extending upwardly through the base plate 34 . Collar 46 may have a reduced diameter upper end portion 52 as shown or, alternatively, the upper end portion may be of substantially the same diameter as the rest of the collar 46 . An outer end portion of the drive shaft 44 extends through an upper end slot 54 in the upper collar end portion 52 and is drivingly coupled to a disc-shaped damper plate 56 which is received in the open upper end portion 52 of the collar 46 and rotatable by the motor 42 between a fully open vertical position (see FIGS. 2-4 ) and a fully closed horizontal position (not shown).

The motor/damper assembly 10 further includes a hollow cover structure or housing 58 (see FIGS. 1-5 ) having an elongated, generally rectangular shape, an open bottom side 60 , a top side wall 62 , a left end wall 64 , a right end wall 66 , a left side wall 68 , a right side wall 70 , and a circular opening 72 formed in the top side wall 62 and configured to complementarily receive the open end portion 52 of the tubular collar 46 as later described herein. As best illustrated in FIGS. 3 and 4 , a left end portion of the housing 58 is vertically enlarged relative to the balance of the housing 58 .

To assemble the motor/damper assembly 10 and operatively secure it to the top end surface 12 of the storage tank portion 16 of the water heater 16 , as shown in FIG. 1 , the base plate 34 is first placed on the top tank end surface 12 in a manner such that the upper end of the flue 24 is complementarily received in the open lower end portion 48 of the tubular collar 46 as best illustrated in FIG. 4 . The base plate 34 is then secured to the top tank end surface 12 using screws 73 (see FIGS. 2-4 ) extended downwardly through the base plate 34 and threaded into corresponding openings in the top tank end.

Next, an end portion of an electrical power wiring harness 74 is inserted through a an opening (not shown) in the housing 58 side wall 70 and secured to the housing 58 via a suitable strain relief fitting 76 . Via a connector 78 , the inserted end of the power wiring harness 74 is coupled to a power wiring harness 80 coupled to the motor 42 . Additionally, an electrical control wiring harness 82 coupled to the motor 42 is secured, via a connector 84 to an electrical control wiring harness 86 that extends through an opening 88 and associated strain relief fitting 90 in the top end surface 12 and downwardly through the tank insulation 20 to the fuel valve controller of the water heater (not shown).

During operation of the water heater 16 , in a generally conventional manner known to those of skill in this particular art, electrical power is transmitted to the motor 42 and the fuel valve controller through the interconnected wiring harnesses 74 , 80 , 82 and 86 , and control signals between the valve controller and the motor 42 are transmitted via the wiring harnesses 82 and 86 . Such signals include calls for the damper 56 to open and close, and signals confirming the proper positioning of the damper 56 .

After the wiring connections are made to the motor 42 as described above, the housing 58 is placed downwardly over the motor 42 and the support structure 32 in a manner such that the open upper end portion 52 of the tubular collar 46 is complementarily received in and projects upwardly beyond the opening 72 in the top side 44 of the housing 58 , and the open bottom side 60 of the housing 58 contacts the top end surface 12 as best shown in FIG. 4 . The housing 58 is then anchored to the support plate structure 32 by means of screws 92 (see FIG. 3 ) extended through the opposite side walls 68 , 70 of the housing 58 and threaded into openings 94 in the side plates 38 , 40 of the support plate structure 32 .

Finally, a conventional draft hood 96 is secured to the top side 62 of the housing 58 , over the upwardly projecting open upper end portion 52 of the tubular collar 46 (see FIG. 4 ), by extending screws 98 downwardly through bottom ends 100 of depending support leg portions 102 of the draft hood 96 into corresponding holes 104 in the top housing side wall 62 . Draft hood 96 has, it its upper end, a circular flange 106 to which a suitable flue pipe extension (not shown) may be secured when the completed water heater 16 is installed at a job site. If desired, the draft hood 96 may be secured to the housing 58 before the housing 58 is installed on the water heater.

With reference now to FIG. 4 , it can be seen that the vertically enlarged left end portion of the installed housing 58 defines therein a chamber 108 which protectively encloses the electric motor 42 . Other accessories, controls, etc. for the motor/damper assembly 10 (not shown) could also be disposed in this chamber if desired. It should also be noted that the top side wall 62 of the housing 58 protectively overlies and shields (from both view and damage) substantially the entire length of the drive shaft 44 .

As previously mentioned herein, the motor/damper assembly 10 provides several advantages over conventional motor/damper assemblies previously utilized in conjunction with fuel-fired water heaters. For example, compared to conventional water heater motor/damper assemblies, the installed assembly 10 is more aesthetically pleasing, with the housing 58 being centered between the cold and hot water pipes 28 and 30 (see FIGS. 1 and 5 ) and hiding the motor 42 and shaft 44 portions of the assembly. The configuration of the support plate structure 32 , coupled with its use of the collar 46 , provides a high degree of support rigidity and alignment precision for the motor 42 and the shaft 44 relative to the damper member 56 which substantially eliminates skewing of the damper member resulting in misalignment of and leakage past the damper. Further, the use of the assembly base plate opening 50 that complementarily receives an upper end portion of the flue 24 provides for repeatable precise manufacturing placement of the motor/drive assembly 10 on the top end of the water heater 16 . Also, the protective enclosure of the motor 42 and the shaft 44 within the housing 58 substantially reduces the possibility of shipping and handling damage of the shaft 44 which would adversely affect the precise motor/shaft/damper alignment advantageously provided by the use of the motor/damper assembly 10 .

The foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims.