Patent Application
20110308481
The present invention relates to a blower housing for a water heater and to a method of reducing the noise produced by a blower of a water heater.
Many water heaters commonly include a water storage tank for storing water, a gas-fired or oil-fired burner that produces hot combustion gases or flue gases, a flue tube that is positioned within the water tank to transfer heat from combustion gases to water in the water storage tank, and a blower that draws the hot flue gases through the flue tube and out of the water heater. Such water heaters may be installed in a residence or a commercial building, for example.
The following patent documents describe samples of water heater systems and are incorporated by reference herein in their entirety: U.S. Pat. Nos. 5,199,385, 7,484,688, 7,540,354 7,559,293, and 7,604,463 and U.S. Patent App. Pub. Nos. 2009/0205901 and 2009/0173572.
Despite past improvements to water heater systems such as those described in the foregoing patent documents, there remains a need for improved water heater systems and for improved blower components for use in such water heater systems.
In one exemplary embodiment, this invention provides a fuel-fired water heater. The fuel-fired water heater generally comprises a water storage tank, a flue positioned to receive combustion gases and transfer heat from combustion gases to water in the water storage tank, and a blower assembly. The blower assembly includes a housing defining an inlet positioned to receive combustion gases from the flue, an interior defined by the housing, an inlet to draw in dilution air, and an outlet positioned to exhaust combustion gases from the interior of the housing. The blower assembly further comprises a motor/impeller assembly that is positioned in the interior of the housing and is configured to direct combustion gases from the inlet of the housing toward the outlet of the housing. The housing of the blower assembly comprises an interior wall portion, an exterior wall portion, and sound-absorbing material interposed between the interior and exterior wall portions. The interior wall portion defines perforations extending between the sound-absorbing material and the interior of the housing.
In another exemplary embodiment, a blower assembly for a fuel-fired water heater having a water storage tank and a flue positioned to receive combustion gases and transfer heat from combustion gases to water in the water storage tank is provided. The blower assembly comprises a blower housing assembly including a perforated sheet having an interior surface that defines a hollow interior region configured to receive combustion gases from the flue. A sound-absorbing material is positioned adjacent an entire exterior surface of the perforated sheet that is opposite the interior surface of the perforated sheet. A housing encapsulates both the sound-absorbing material and the perforated sheet, wherein an exterior surface of the sound-absorbing material and an interior surface of the housing together define an air gap between the sound-absorbing material and the housing. A motor/impeller assembly is positioned within the hollow interior region defined by the perforated sheet. The arrangement of the sound-absorbing material, the perforated sheet and the air-gap dampens audible noise emitted by the motor/impeller assembly.
In yet another exemplary embodiment, a housing assembly for a water heater is provided. The housing assembly generally comprises a perforated sheet having an interior surface that defines a hollow interior region for encapsulating a noise producing component of the water heater. A sound-absorbing sheet, which is composed of sound-absorbing material, is positioned adjacent an exterior surface of the perforated sheet that is opposite the interior surface of the perforated sheet. A housing encapsulates the sound-absorbing sheet and the perforated sheet. The sound-absorbing sheet is separated from an interior surface of the housing by a pre-determined distance thereby defining an air gap between the sound-absorbing sheet and the housing. The arrangement of the sound-absorbing sheet, the perforated sheet and the air-gap dampens audible noise emitted by the noise producing component positioned within the hollow interior region.
The invention is best understood from the following detailed description when read in connection with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawings are the following figures:
Exemplary features of selected embodiments of this invention will now be described with reference to the figures. It will be appreciated that the spirit and scope of the invention is not limited to the embodiments selected for illustration. Also, it should be noted that the drawings are not rendered to any particular scale or proportion. It is contemplated that any of the exemplary configurations and materials and sizes described hereafter can be modified within the scope of this invention.
Referring generally to the figures and according to one exemplary embodiment of the invention, this invention provides a fuel-fired water heater 15. The fuel-fired water heater 15 generally comprises a water storage tank 22, a flue 25 positioned to receive combustion gases and transfer heat from combustion gases to water in the water storage tank 22, and a blower assembly 30. The blower assembly 30 includes a housing 31 defining an inlet 38 positioned to receive combustion gases from the flue 25, an interior defined by the housing 31, and an outlet 42 positioned to exhaust combustion gases from the interior of the housing 31. The blower assembly 30 further comprises a motor/impeller assembly 32 and 36 that is positioned in the interior of the housing 31 and is configured to direct combustion gases from the inlet 38 of the housing 31 toward the outlet 42 of the housing 31. The housing 31 of the blower assembly 30 comprises an interior wall portion 60, an exterior wall portion 50, and sound-absorbing material 52 interposed between the interior and exterior wall portions. The interior wall portion 60 defines perforations 70 extending between the sound-absorbing material 52 and the interior of the housing 31.
In another exemplary embodiment, a blower assembly 30 for a fuel-fired water heater 15 having a water storage tank 22 and a flue 25 positioned to receive combustion gases and transfer heat from combustion gases to water in the water storage tank 22 is provided. The blower assembly 30 comprises a blower housing assembly 31 including a perforated sheet 60 having an interior surface that defines a hollow interior region configured to receive combustion gases from the flue 25. A sound-absorbing material 52 is positioned adjacent an entire exterior surface of the perforated sheet 60 that is opposite the interior surface of the perforated sheet 60. A housing 50 encapsulates both the sound-absorbing material 52 and the perforated sheet 60, wherein an exterior surface of the sound-absorbing material 52 and an interior surface of the housing 50 together define an air gap 54 between the sound-absorbing material 52 and the housing 50. A motor/impeller assembly 32 and 36 is positioned within the hollow interior region defined by the perforated sheet 60. The arrangement of the sound-absorbing material 52, the perforated sheet 60 and the air-gap 54 dampens audible noise emitted by the motor/impeller assembly 32 and 36.
In yet another exemplary embodiment, a housing assembly 31 for a water heater 15 is provided. The housing assembly 31 generally comprises a perforated sheet 60 having an interior surface that defines a hollow interior region for encapsulating a noise producing component 32 and/or 36 of the water heater 15. A sound-absorbing sheet 52, which is composed of sound-absorbing material, is positioned adjacent an exterior surface of the perforated sheet 60 that is opposite the interior surface of the perforated sheet 60. A housing 50 encapsulates the sound-absorbing sheet 52 and the perforated sheet 60. The sound-absorbing sheet 52 is separated from an interior surface of the housing 50 by a pre-determined distance thereby defining an air gap 54 between the sound-absorbing sheet 52 and the housing 50. The arrangement of the sound-absorbing sheet 52, the perforated sheet 60 and the air-gap 54 dampens audible noise emitted by the noise producing component 32 and/or 36 positioned within the hollow interior region.
Referring now to
The water heater 15 generally includes a water storage tank 22 for containing water, an outer shell 24 for encapsulating the water tank 22, and a flue 25 positioned within the interior region of the water tank 22 for distributing combustion products for heat exchange with water in the water tank 22. The fuel burner 21 produces combustion products and is positioned within a combustion chamber 29 beneath the water tank 22. The combustion chamber 29 directs the combustion products into an inlet end 27 of the flue 25. The flue 25 is positioned within the interior of the water tank 22 for distributing combustion products for heat exchange with water in the water tank 22. The outlet end 23 of the flue 25 extends through apertures provided in the top surface of the water tank 22 and the top surface of the outer shell 24.
A blower assembly 30 is mounted to the top surface of the outer shell 24. The blower assembly 30 generally includes a housing assembly 31, a motor 32 that is fastened to the housing assembly 31 by a plurality of brackets 34, and an impeller 36 that is coupled to the motor 32 by a shaft 37 such that the impeller 36 is driven by the motor 32. The impeller 36 includes veins (not shown) which urge combustion products and air into the housing assembly 31 and exhaust the combustion products and air into the exhaust vent 20.
Referring now to
The motor 32 and the impeller 36 are almost entirely surrounded by, i.e., encapsulated by, a perforated wall such as a perforated sheet 60. The perforated sheet 60 includes an array of perforations 70 (see
A sound-absorbing material such as a sheet 52 is positioned adjacent the perforated sheet 60. In an exemplary embodiment, sound-absorbing sheet 60 is mounted to the entire outer surface of the perforated sheet 60 by either adhesive or mechanical fasteners, for example. The sound-absorbing sheet 52, which may also be referred to herein as a sound-absorbing layer or a sound-absorbing portion, is provided to dampen audible noise emitted by the motor 32 and/or the impeller 36. The sound-absorbing sheet 52 may be composed of fiberglass or mineral wool, for example, or any other materials having sound dampening properties that are known in the art, and its thickness may vary.
The sound-absorbing sheet 52 and the perforated sheet 60 are completely encapsulated within an exterior shell 50 of the housing assembly 31. All or substantially all of the exterior surface of the sound-absorbing sheet 52 is separated from an interior surface of the exterior shell 50 by an air gap 54. The depth of the air gap 54 is substantially constant, as measured from any point on the exterior surface of the sound-absorbing sheet 52. According to one exemplary embodiment of the invention, the depth of the air gap 54 may vary from 0.01 inches to 3.0 inches, for example. The depth of the air gap and the size of the air gap at selected locations in the shell 50 may vary without departing from the scope or spirit of the invention.
The inlet port 38 is formed in the exterior shell 50, the sound-absorbing sheet 52 and the perforated sheet 60 to accommodate the flue tube 25. A passageway 66 is formed in the exterior shell 50, the sound-absorbing sheet 52 and the perforated sheet 60 to permit the passage of air into the housing assembly 31. The air and combustion products exit the housing assembly 31 through another passageway (not shown) that is formed in the exterior shell 50, the sound-absorbing sheet 52 and the perforated sheet 60 at a location that is proximal to the exhaust port 42.
Although not shown, provisions such as bosses or brackets may be provided on the interior surfaces of the exterior shell 50 for mounting the sound-absorbing sheet 52 and the perforated sheet 60 to the exterior shell 50. The exterior shell 50 may be composed of plastic or metal, for example. The exterior shell 50 may also be referred to herein as a housing, a blower housing or a blower housing wall.
The arrangement of the perforated sheet 60, the air gap 54 and the sound-absorbing sheet 52 may be characterized by those skilled in the art as a resonant sound absorber. The resonant sound absorber of the housing assembly 31 is particularly suited to dampen the sound waves produced by the motor 32 and the impeller 36. While simply increasing the thickness of the sound-absorbing sheet 52 would improve the sound dampening qualities of the housing assembly 31, such improvements in sound dampening, however, would come at the expense of reduced space within the housing assembly 31 and added material costs. By attaching the perforated sheet 60 to one side of the sound-absorbing sheet 52 and optionally providing an air gap 54 on the opposite side of the sound-absorbing sheet 52, the thickness of the sound-absorbing sheet 52 may be relatively small to achieve superior sound dampening.
In operation of the resonant sound absorber, the perforations 70 provide a passageway through which sound waves pass, without being diminished or reflected, to reach the sound-absorbing sheet 52. The air motion into and out of the perforations 70 of the perforated sheet 60 oscillates in response to an incident sound wave. At the frequency of oscillation, the air moves violently in and out of the perforations 70 and, also, back and forth in the sound-absorbing sheet 52.
The resultant friction between the air and the perforations 70 and the sound-absorbing material 50 converts the acoustic energy of the sound wave into heat, thereby diminishing the acoustic energy and the resultant sound emitted by the blower assembly 30. The frequency of oscillation is influenced by the thickness of the perforated sheet 60, the size and number of the perforations 70, and the depth of the air gap 54. The thickness of the sound-absorbing sheet 52 that is required to either remove or significantly reduce the sound emitted by the blower assembly 30 is calculated as a function of the frequency of oscillation.
The housing assemblies described herein may be assembled onto a new water heater in the factory, or, alternatively, the housing assembly 31 may be retrofitted onto an existing water heater in a residence or commercial building, for example.
It should be understood that the housing assemblies described herein are not limited for use with the blower shown in
Although this invention has been described with reference to exemplary embodiments and variations thereof, it will be appreciated that additional variations and modifications can be made within the spirit and scope of this invention. Although this invention may be of particular benefit in the field of residential water heaters, it will be appreciated that this invention can be beneficially applied in connection with commercial, industrial or domestic water heaters and other heating systems as well. Additionally, the invention disclosed herein is not limited to fuel-fired water heaters. Many of the details of this invention may also apply to any other type of heat exchanger or insulated tank.
