Note: Descriptions are shown in the official language in which they were submitted.
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WATER HEATER BLOWER HOUSING
FIELD OF THE INVENTION
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.
BACKGROUND OF THE INVENTION
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:
U.S. Patent 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.
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SUMMARY OF THE INVENTION
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
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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.
BRIEF DESCRIPTION OF THE DRAWINGS
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:
FIG. 1 depicts a schematic cross-sectional elevation view of an embodiment of
a water heating system, which is shown schematically, according to aspects of
this
invention.
FIG. 2 depicts a schematic cross-sectional view of a blower assembly of the
water heating system of FIG. 1.
FIGS. 3A through 3D depict perspective, rear elevation, side elevation and top
plan views, respectively, of another embodiment of a blower assembly according
to
aspects of this invention.
FIG. 3E depicts a detailed view of the air inlet plenum of the blower assembly
of FIG. 3C taken along the lines 3E-3E.
FIG. 4 depicts a rear elevation view of yet another exemplary embodiment of
a blower assembly according to aspects of this invention.
DETAILED DESCRIPTION OF THE DRAWINGS
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
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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
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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 FIG. 1, a fuel-fired water heating system embodying
exemplary aspects of this invention is shown schematically and is generally
designated by the numeral "10." In the water heating system 10, a water heater
15
is attached to a fuel supply line 17 and an exhaust vent 20. The fuel supply
line 17
supplies fuel (e.g., oil or combustible gas) to a fuel burner 21 of the water
heater 15
for combustion, and the exhaust vent 20 provides a conduit for exhausting the
products of combustion from the water heater 15. The exhaust vent 20 may be
integrated with a residential structure, or integrated with the water heater
15.
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
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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 FIGS. 1 and 2, the housing assembly 31 of the blower
assembly 30 includes an inlet port 38 that is connected to the outlet end 23
of the
flue 25, an air intake plenum 41 defining an air intake port 40, and an
exhaust port
42 that is coupled to the exhaust vent 20. In operation, as indicated by the
arrows
in FIG. 1, combustion products from the flue 25 are urged by the impeller 36
into the
interior of the housing assembly 31 through the inlet port 38. Atmospheric air
is
urged by the impeller 36 into the interior of the housing assembly 31 through
the air
intake port 40. The products of combustion and the atmospheric air are then
exhausted through the exhaust port 42 into the exhaust vent 20. Further
details of
the structure and operation of examples of a blower motor and a impeller are
disclosed in U.S. Patent No. 5,199,385.
FIG. 2 depicts a detailed view of a cross-section of the blower assembly 30 of
the water heating system of FIG. 1. The blower assembly 30 is shown
schematically
in FIGS. 1 and 2. As described in detail hereinafter, the housing assembly 31
of the
blower assembly 30 is uniquely arranged to dampen (i.e., muffle) audible noise
that
is produced by the motor 32 and/or the impeller 36 of the blower assembly 30,
thereby reducing the noise emanating from the blower assembly.
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 FIG. 3E) in the form of
small
apertures, the purpose of which will be described later. The number, size and
shape
of the perforations 70 may vary, and the perforations are optionally provided
uniformly throughout the perforated wall or at one or more selected locations.
The
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perforated sheet 60 may be composed of a metallic material, such as carbon
steel,
stainless steel, aluminum, for example. Alternatively, the perforated sheet 60
may
be composed of a polymer. The thickness of the perforated sheet 60 may vary.
The
perforated wall may be formed by stamping, molding, bending, or other
manufacturing methods.
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
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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.
FIGS. 3A through 3D depict exterior views of another exemplary embodiment
of a blower assembly. With the exception of the shape, the blower assemblies
of
FIG. 1 and FIGS. 3A-3D are substantially similar, thus, like numerals refer to
like
elements of the blower assemblies 30 in those figures. FIG. 3E depicts a
detailed
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view of the air inlet plenum 41 of the blower assembly 30 of FIG. 3C taken
along the
lines 3E-3E. A rectangular shaped perforated sheet 62 is positioned over the
air
intake port 40 of the air intake plenum 41. The perforated sheet 62 dampens
the
noise produced by the blower assembly 30.
FIG. 4 depicts a rear elevation view of another exemplary embodiment of a
blower housing 131 according to aspects of this invention. The blower housing
131
is substantially similar to the blower housing 31 of FIG. 3A-3E, with the
exception
that the blower housing 131 does not include an air intake plenum, such as
intake
plenum 41. The air intake port 140 of the blower housing 131 is disposed on
the
rear face of the blower housing 131. The air intake port 140 is concealed by a
circular perforated sheet 162 that includes a series of perforations 170. The
purpose
and function of the perforations 170 are the same as that of the perforations
70 of
the perforated sheet 62 of FIG. 3E.
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 FIGS. 1 through 4. With only minor
modifications, the housing assembly may be utilized to muffle noise produced
by
other noise-producing components of a water heater. For example, minor
modifications may be made to the housing assembly 31 to configure it for use
with a
forced draft burner. A forced draft burner delivers products of combustion
directly
into a flue tube. An example of a forced draft burner is disclosed in U.S.
Patent No.
7,559,293. The modified housing assembly would be positioned to encapsulate a
blower of the forced draft burner to dampen the noise produced by the blower.
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-
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fired water heaters. Many of the details of this invention may also apply to
any other
type of heat exchanger or insulated tank.
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