U.S. patent application number 12/631415 was filed with the patent office on 2010-10-21 for high efficiency furnace/air handler blower housing with a side wall having an exponentially increasing expansion angle.
This patent application is currently assigned to RBC Horizon, Inc.. Invention is credited to Steven Post.
Application Number | 20100263653 12/631415 |
Document ID | / |
Family ID | 42056057 |
Filed Date | 2010-10-21 |
United States Patent
Application |
20100263653 |
Kind Code |
A2 |
Post; Steven |
October 21, 2010 |
High Efficiency Furnace/Air Handler Blower Housing with a Side Wall
Having an Exponentially Increasing Expansion Angle
Abstract
An air distribution blower housing for an air handler such as a
residential furnace is designed with a volute-shaped outer wall
that has an exponentially increasing expansion angle in the
direction of air flow through the blower housing for at least a
portion of the volute-shaped outer wall length. This results in the
blower housing having an enlarged air outlet opening that slows
down and spreads out the air flow from the blower housing over a
greater area of the furnace heat exchanger. The blower housing
thereby enables less air pressure drop through the heat exchanger,
which increases the efficiency of the blower motor operation. The
design of the blower housing also efficiently turns the velocity
head of the air flow through the housing to usable static air
pressure at the housing air outlet.
Inventors: |
Post; Steven; (Cassville,
MO) |
Correspondence
Address: |
THOMPSON COBURN LLP
ONE US BANK PLAZA
SUITE 3500
ST LOUIS
MO
63101
UNITED STATES
314-552-6000
314-552-7000
IPDOCKET@THOMPSONCOBURN.COM
|
Assignee: |
RBC Horizon, Inc.
200 State Street
Beloit
WI
53511
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20100078007 A1 |
April 1, 2010 |
|
|
Family ID: |
42056057 |
Appl. No.: |
12/631415 |
Filed: |
December 4, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11/935,726 |
Nov 6, 2007 |
|
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12631415 |
Dec 4, 2009 |
|
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Current U.S.
Class: |
126/112 |
Current CPC
Class: |
F24H 9/0073 20130101;
F04D 29/4226 20130101; F04D 29/422 20130101; F24H 3/065 20130101;
F24H 3/087 20130101 |
Class at
Publication: |
126/112 |
International
Class: |
F24H 3/02 20060101
F24H003/02 |
Claims
1. An air handler comprising: an enclosure having an interior
volume and a distribution air outlet opening on the enclosure that
is adapted for communication with an air distribution system; a fan
wheel in the enclosure interior volume, the fan wheel having an
outer diameter dimension and a circumference dimension, the fan
wheel having a center axis of rotation that defines mutually
perpendicular axial and radial directions and the fan wheel being
rotatable about the center axis of rotation in a rotation
direction; a blower housing in the enclosure interior volume, the
blower housing containing the fan wheel and having an air outlet
opening, the air outlet opening having a minimum radial dimension,
a ratio of the minimum radial dimension and the fan wheel outer
diameter dimension being at least 0.73, the blower housing having
an outer wall with a volute-shaped portion that extends from a
first end of the volute-shaped portion around the fan wheel in the
rotation direction to the second end of the volute-shaped portion,
and the volute-shaped portion of the blower housing outer wall
having first and second sections as the volute-shaped portion
extends in the rotation direction around the fan wheel, where an
expansion angle of the second section of the volute-shaped length
portion increases at an exponential rate of 1.5 to 2.1.
2. The air handler of claim 1, further comprising: the first
section of the volute-shaped portion subtending an angle of at most
270.degree. at the fan wheel center axis.
3. The air handler of claim 1, further comprising: the first
section of the volute-shaped portion subtending an angle of
270.degree. at the fan wheel center axis and the second section of
the volute-shaped portion subtending an angle of 90.degree. at the
fan wheel center axis.
4. The air handler of claim 1, further comprising: an expansion
angle of the first section of the volute-shaped portion increases
at an exponential rate of 1.2 to 1.4.
5. The air handler of claim 1, further comprising: the air handler
being a furnace.
6. The air handler of claim 1, further comprising: the
volute-shaped portion of the outer wall consisting essentially of
the first section and the second section of the volute-shaped
portion.
7. (canceled)
8. An air handler comprising: an enclosure having an interior
volume and a distribution air outlet opening on the enclosure that
is adapted for communication with an air distribution system; a fan
wheel in the enclosure interior volume, the fan wheel having an
outer diameter dimension and a circumference dimension, the fan
wheel having a center axis of rotation that defines mutually
perpendicular axial and radial directions and the fan wheel being
rotatable about the center axis of rotation in a rotation
direction; a blower housing in the enclosure interior volume, the
blower housing containing the fan wheel and having an air outlet
opening, the air outlet opening having a minimum radial dimension,
a ratio of the minimum radial dimension and the fan wheel outer
diameter dimension being at least 0.73, the blower housing having
an outer wall with a volute-shaped portion that extends from a
first end of the volute-shaped portion around the fan wheel in the
rotation direction to the second end of the volute-shaped portion,
the first end of the volute-shaped portion being spaced radially a
first distance dimension from the fan wheel axis of rotation and
the second end of the volute-shaped portion being spaced radially a
second distance dimension from the fan wheel axis of rotation that
is larger than the first distance, and the volute-shaped portion of
the blower housing outer wall having first and second sections with
different generally increasing expansion angles as the
volute-shaped portion extends in the rotation direction around the
fan wheel, where the expansion angle of the second section of the
volute-shaped portion increases at an exponential rate of 1.5 to
2.1.
9. The air handler of claim 8, further comprising: the first
section of the volute-shaped portion extends over at most
270.degree. of the fan wheel circumference dimension.
10. The air handler of claim 8, further comprising: the first
section of the volute-shaped portion extends over 270.degree. of
the fan wheel circumference dimension and the second section of the
volute-shaped portion extends over 90.degree. of the fan wheel
circumference dimension.
11. (canceled)
12. The air handler of claim 8, further comprising: the blower
housing outer wall having a length that includes the volute-shaped
portion and extends from a first end of the outer wall around the
fan wheel in the rotation direction to the second end of the outer
wall, the first end of the outer wall being spaced radially a first
distance dimension from the fan wheel axis of rotation and the
second end of the outer wall being spaced radially a second
distance dimension from the fan wheel axis of rotation that is
larger than the first distance; and, a ratio of the second distance
dimension and the fan wheel outer diameter being at least 0.91.
13. The air handler of claim 8, further comprising: the air handler
being a furnace.
14. The air handler of claim 8, further comprising: the
volute-shaped portion of the outer wall consisting essentially of
the first section and the second section of the volute-shaped
portion.
15. An air handler comprising: an enclosure having an interior
volume enclosed in opposite front and rear walls of the enclosure
each having a width dimension, opposite left and right side walls
of the enclosure each having a length dimension, and an opposite
top and bottom of the enclosure, and a distribution air outlet
opening on the enclosure that is adapted for communication of a
distribution air stream from the enclosure to an exterior
environment of the enclosure; a fan wheel in the enclosure interior
volume, the fan wheel having an outer diameter dimension, an axis
of rotation that defines mutually perpendicular axial and radial
directions, and the fan wheel being rotatable in a rotation
direction around the axis of rotation; a blower housing in the
enclosure interior volume, the blower housing having an interior
volume containing the fan wheel and an air flow outlet opening, the
air outlet opening having a minimum radial dimension, a ratio of
the minimum radial dimension and the fan wheel outer diameter
dimension being at least 0.73, the blower housing having first and
second side walls on axially opposite ends of the fan wheel, and
the blower housing having an outer wall having a width dimension
extending between the first and second side walls, the outer wall
having a volute-shaped portion that spirals away from the fan wheel
axis of rotation as it extends in the rotation direction from a
first end of the volute-shaped portion at one side of the air flow
outlet opening around the blower housing interior volume to a
second end of the volute-shaped portion at an opposite side of the
air flow outlet opening from the first end, the volute-shaped
portion of the blower housing outer wall having first and second
sections, the second section being spaced from the first end of the
volute-shaped portion by the first section, and the second section
of the volute-shaped portion having an expansion angle that
increases at an exponential rate in a range of 1.5 to 2.1.
16. The air handler of claim 15, further comprising: the first
section of the volute-shaped portion subtending an angle of at most
270.degree. at the fan wheel center axis.
17. The air handler of claim 15, further comprising: the first
section of the volute-shaped portion subtending an angle of
270.degree. at the fan wheel center axis and the second section of
the volute-shaped portion subtending an angle of 90.degree. at the
fan wheel center axis.
18. The air handler of claim 15, further comprising: an expansion
angle of the first section of the volute-shaped portion increases
at an exponential rate of 1.2 to 1.4.
19. The air handler of claim 15, further comprising: the air
handler being a furnace.
20. The air handler of claim 15, further comprising: the
volute-shaped portion of the outer wall consisting essentially of
the first section and the second section of the volute-shaped
portion.
21. The air handler of claim 15, further comprising: the outer wall
having a straight portion that extends from the second end of the
volute-shaped portion to the air flow outlet opening of the blower
housing.
22. (canceled)
23. An air handler comprising: an enclosure having an interior
volume and a distribution air outlet opening on the enclosure that
is adapted for communication with an air distribution system; a fan
wheel in the enclosure interior volume, the fan wheel having an
outer diameter dimension and a circumference dimension, the fan
wheel having a center axis of rotation that defines mutually
perpendicular axial and radial directions and the fan wheel being
rotatable about the center axis of rotation in a rotation
direction; a blower housing in the enclosure interior volume, the
blower housing containing the fan wheel and having an air outlet
opening, the blower housing having an outer wall with a
volute-shaped portion that extends from a first end of the
volute-shaped portion around the fan wheel in the rotation
direction to the second end of the volute-shaped portion, and the
volute-shaped portion of the blower housing outer wall having first
and second sections as the volute-shaped portion extends in the
rotation direction around the fan wheel, where the first section of
the volute-shaped portion has a positive expansion angle and an
expansion angle of the second section of the volute-shaped portion
increases at an exponential rate of 1.5 to 2.1.
24. The air handler of claim 23, further comprising: the first
section of the volute-shaped portion subtending an angle of at most
270.degree. at the fan wheel center axis.
25. The air handler of claim 23, further comprising: the first
section of the volute-shaped portion subtending an angle of
270.degree. at the fan wheel center axis and the second section of
the volute-shaped portion subtending an angle of 90.degree. at the
fan wheel center axis.
26. The air handler of claim 23, further comprising: an expansion
angle of the first section of the volute-shaped portion increases
at an exponential rate of 1.2 to 1.4.
27. The air handler of claim 23, further comprising: the air
handler being a furnace.
28. The air handler of claim 23, further comprising: the
volute-shaped portion of the outer wall consisting essentially of
the first section and the second section of the volute-shaped
portion.
29. The air handler of claim 23, further comprising: the air outlet
opening having a minimum radial dimension and a ratio of the
minimum radial dimension and the fan wheel outer diameter dimension
being at least 0.73.
Description
RELATED APPLICATION DISCLOSURE
[0001] This patent application is a continuation-in-part of patent
application Ser. No. 11/935,726, which was filed on Nov. 6, 2007,
and is currently pending.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention pertains to a high efficiency furnace
and a low profile furnace that each comprise a compact enclosure
for residential use and an air distribution blower housing that is
designed with an outer wall having an exponentially increasing
expansion angle and an enlarged air outlet opening. The enlarged
outlet opening slows down and spreads out the air flow from the
blower housing over a greater area of the secondary heat exchanger
and the primary heat exchanger of the high efficiency furnace, and
over a greater area of the heat exchanger of a low profile furnace.
Thus, the blower housing enables less air pressure drop through the
heat exchangers, which increases the efficiency of the blower
operation. The design of the blower housing also efficiently turns
the velocity head of the air flow to usable static pressure at the
housing air outlet. The enlarged air outlet opening of the blower
housing is achieved without increasing the exterior dimensions of
the blower housing whereby the blower housing is used in a compact
enclosure for residential use. This is accomplished by utilizing a
unique design volute outer wall of the blower housing that has a
unique exponentially increasing expansion angle in the direction of
air flow through the blower housing and compact relative
positioning of the blower housing and heat exchangers in the
furnace enclosure.
[0004] 2. Description of Related Art
[0005] High efficiency residential natural gas powered furnaces are
becoming more and more common. A furnace of this type is defined in
the industry as a 90+ AFUE (Annul Fuel Utilization Efficiency)
furnace. A 90+ furnace converts more than 90% of the fuel supplied
to the furnace to heat, with the remainder being lost through the
chimney or exhaust flue. These particular types of furnaces employ
a primary heat exchanger found in most any type of furnace, plus an
additional secondary heat exchanger. The secondary heat exchanger
increases the capacity of the furnace to convert the heat of the
gas combustion to the distribution air flow from the furnace, and
thereby defines the furnace as a high efficiency furnace.
[0006] The typical construction of a high efficiency furnace 10 is
shown in FIG. 1. The furnace 10 has an external housing enclosure
12 with an interior volume 14. Several portions of the side walls
of the furnace enclosure 12 shown in FIG. 1 have been removed to
illustrate the interior components of the furnace. The dimensions
of the furnace enclosure 12 are determined to contain all of the
component parts of the furnace in the enclosure 12, without the
enclosure occupying a significant area in the residence in which
the furnace is installed. In contrast, commercial furnaces are
typically mounted on the roof of a building or at some other
location outside the building where there are no size restraints.
Because commercial furnaces with their large capacity are located
outside the structures they serve, there is no need to position the
component parts of the furnace relative to each other to minimize
the size of the furnace enclosure as there is in residential
furnaces.
[0007] An air inlet opening is typically provided in a side wall or
in the bottom of the furnace enclosure. The air inlet opening can
be covered by an air filter that allows ambient air in the
environment surrounding the enclosure 12 to easily pass through the
opening and enter the enclosure interior 14. Alternatively and more
frequently, the air inlet opening of the furnace enclosure
communicates with a cold air return duct system of the residence.
The cold air return duct system channels ambient air from
throughout the residence to the furnace enclosure.
[0008] The furnace enclosure also has an air distribution outlet
opening 18. The outlet opening communicates with an air
distribution conduit or duct system of the residence in which the
furnace is installed. In FIG. 1, the air distribution outlet
opening is located at the top of the enclosure 12. The air heated
by the high efficiency furnace 10 is discharged to the air
distribution conduit system (not shown) through the distribution
air outlet opening 18.
[0009] In the typical construction of a high efficiency furnace
represented in FIG. 1, a primary heat exchanger 22 is located at
the top of the enclosure 12 adjacent the distribution air outlet
opening 18. A secondary heat exchanger 24 that qualifies the
furnace as a high efficiency furnace is located directly below the
primary heat exchanger 22.
[0010] An air distribution blower 26 that draws ambient air into
the furnace enclosure 12 is positioned just below the secondary
heat exchanger 24. A motor (not shown) of the blower rotates a fan
wheel 28 in the interior of the blower in a clockwise direction as
viewed in FIG. 1. This rotation of the fan wheel 28 draws the
ambient air into the blower 26 as represented by the arrow labeled
(AIR FLOW) in FIG. 1, and pushes the ambient air out of the blower
through the secondary heat exchanger 24, then through the primary
heat exchanger 22, and then out of the enclosure through the air
distribution outlet opening 18.
[0011] A typical blower 26 includes a blower housing that contains
the fan wheel 28. The typical blower housing includes an exterior
or outer wall 32 having a scroll or volute configuration. The outer
wall 32 spirals around the fan wheel 28 in the direction of fan
wheel rotation. A pair of side walls 34, only one of which is shown
in FIG. 1, cover over opposite sides of the volute outer wall 32
and enclose the interior of the blower 26.
[0012] As shown in FIG. 1, the typical volute outer wall 32 of the
blower housing has a constant expansion angle as it extends in the
fan wheel rotation direction around the fan wheel. What is meant by
expansion angle is the angle at which the outer wall expands in the
direction of fan wheel rotation from any point on the exterior of
the outer wall 32. In the typical construction of a blower housing
outer wall 32 such as that shown in FIG. 1, this expansion angle is
constant for all points along the volute outer wall 32 in the
rotation direction, resulting in a gradually increasing distance
between the outer circumference of the fan wheel 28 and the outer
wall 32 as the outer wall extends in the rotation direction around
the fan wheel.
[0013] The air distribution blower 26 of the typical high
efficiency furnace represented in FIG. 1 has been found to be
disadvantaged in that the flow of air directed from the blower is
primarily concentrated on only small portions of the secondary heat
exchanger 24 and the primary heat exchanger 22. The air flow
directed from the blower through the portions of the heat
exchangers is represented by the arrows 34 shown in FIG. 1. As seen
in FIG. 1, the scroll configuration of the volute outer wall 32 and
the close positioning of the fan wheel 28 to the interior surface
of the outer wall 32 primarily concentrates the flow of air through
the reduced areas of the secondary heat exchanger 24 and the
primary heat exchanger 22 shown to the left in FIG. 1. This reduces
the efficiency of heat transfer from the heat exchangers to the air
flow. The concentration of the air flow to reduced areas of the
secondary 24 and the primary 22 heat exchanger also results in a
significant pressure drop. This additional pressure drop requires
additional blower horsepower, i.e. a larger blower motor. The
requirement for a larger blower motor decreases the electrical
efficiency of the furnace. Also, the heat generated by operating a
larger motor would especially detract from the cooling system
efficiency when an air conditioning heat exchanger is added at the
air outlet opening 18 in the enclosure 12. If the problem of the
concentration of air flow through the reduced areas of the heat
exchangers is attempted to be overcome by simply enlarging the size
of the exhaust outlet of the conventional blower housing, the
resulting scroll shape of the blower housing would not be able to
adequately convert the velocity head of the air flow through the
housing into static pressure of the resulting blower system and the
overall blower system would not be successful in saving energy.
SUMMARY OF THE INVENTION
[0014] The present invention overcomes the efficiency problems
associated with the constructions of prior art 90+ furnace blowers
by providing a blower with a unique housing design that spreads out
the distribution air flow over the secondary heat exchanger to a
larger extent than the existing blowers of the prior art. This
enables the blower to operate with less of a pressure drop through
the heat exchangers than that of prior art blowers. The scroll
design of the blower housing also efficiently turns the velocity
head of the air flow through the housing to usable static air
pressure. In addition, it has been found through testing that the
blower housing design of the invention applied to a low profile 80+
furnace blower has a similar or superior static efficiency to that
of a regular profile blower. In a similar manner to the 90+
furnace, in an 80+ furnace where the primary heat exchanger is
located close to the blower housing air outlet opening, the
enlarged air outlet opening of the blower housing of the invention
directs air over a larger area of the primary heat exchanger than
blower housings of the prior art, and thereby creates energy
savings. This enables the design of the blower housing to be
employed in low profile 80+ furnaces to provide an efficiency gain,
even though there is no secondary heat exchanger in the low profile
furnace. The improved efficiency of the blower housing enables a
reduction in the exterior dimensions of the furnace enclosure in
which the blower housing is used.
[0015] In the typical construction of an air distribution blower,
the pressure loss is proportional to the air flow velocity squared
through a given restriction of the blower housing. Just a 15
percent increase in a two dimensional rectangular plane that
represents the effective flow area across the secondary heat
exchanger of the furnace can potentially create a
(1.15.times.1.15=1.3225), (1/1.3225=0.756) 25% increase in
efficiency due to air pressure loss at the secondary heat
exchanger.
[0016] With this in mind, the high efficiency furnace of the
present invention employs a blower housing with an enlarged air
outlet opening, while the exterior dimensions of the blower housing
remain substantially the same as those of the prior art blower
housing used in a high efficiency furnace.
[0017] The blower housing of the present invention employs a fan
wheel with forward curved impeller blades for low noise and for
reducing the size of the fan wheel. Fan wheels with forward curved
impeller blades are known to create large amounts of pressure and
air flow for a relatively small size of fan wheel.
[0018] To obtain a large air outlet opening in the blower housing
without increasing the exterior dimensions of the blower housing,
the present invention utilizes an exponentially increasing
expansion angle along the length of the blower housing
volute-shaped outer wall. Alternatively, the blower housing of the
invention utilizes an exponentially increasing expansion angle
along a substantial portion of, or substantial portions of the
outer wall. Where the expansion angle of the volute outer wall of
prior art blower housings increases at a constant rate, the
expansion angle of the volute outer wall of the blower housing of
the present invention increases exponentially as the outer wall
extends around the fan wheel in the rotation direction of the fan
wheel. The exponentially increasing expansion angle of the volute
outer wall provides a very large air outlet opening while still
having a volute shape around the entire length of the blower
housing outer wall following the outer wall cutoff.
[0019] In a preferred embodiment, the expansion angle of the last
quarter of the volute-shaped outer wall length, from 270.degree. to
360.degree. of the volute-shaped length increase at an exponential
rate in a range of 1.5 to 2.1. This exponent range of 1.5 to 2.1
has proved to be critical to the operation of the high efficiency
blower housing of the invention. The expansion angle increasing at
a smaller exponential rate than the preferred range does not create
the desired coriollis component to pull the air flow through the
impeller or the required scroll housing volume. The expansion angle
increasing at a larger exponential rate than the preferred range
will concentrate excessive air flow through a small portion of the
impeller and the overall expanded blower housing will not smoothly
convert the air flow velocity head in the blower housing to static
pressure. All of these attributes are important for a high
efficiency blower housing's operation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Further features of the invention are set forth in the
following detailed description of the invention and in the drawing
figures.
[0021] FIG. 1 is a partial view of the construction of a prior art
high efficiency furnace.
[0022] FIG. 2 is a partial view of the high efficiency furnace of
FIG. 1 employing the unique blower housing of the present
invention.
[0023] FIG. 3 is a perspective view of the opposite side of the
blower housing in FIG. 2, removed from the furnace enclosure.
[0024] FIG. 4 is a side elevation view of the blower housing of
FIG. 3, and is a schematic representation of the dimensional
relationships between the circumference of the fan wheel and the
volute-shaped outer wall of the blower housing of the
invention.
[0025] FIG. 5 is a partial view of a low profile 80+ furnace
employing the blower housing of the invention.
[0026] FIGS. 6 and 7 are graphs comparing the operation of blower
housings of the invention with those of the prior art.
[0027] FIG. 8 is a view similar to FIG. 4 of a further
configuration of the blower housing.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0028] FIG. 2 is a perspective, cut away view of the high
efficiency furnace of the invention that employs the blower housing
of the invention having an enlarged air outlet opening and an
exponentially increasing expansion angle. The furnace of the
invention is primarily constructed in the same manner as known high
efficiency furnaces. The difference in the furnace of the invention
is in the unique design of the blower housing of the furnace. This
unique design of the blower housing provides a superior
distribution of air flow through the secondary and primary heat
exchangers of the furnace, and thereby reduces the horsepower
required by the distribution blower motor enabling an increase in
the efficiency of the high efficiency furnace. Because much of the
construction of the furnace shown in FIG. 2 is the same as that of
FIG. 1, the same component parts of the furnace of FIG. 2 will be
described only generally and are identified by the same reference
numbers used in identifying the component parts in FIG. 1, but with
the reference numbers being followed by a prime (').
[0029] The high efficiency furnace 10' of the present invention
also includes an external housing enclosure 12' that contains the
interior volume 14' of the furnace. Only a rear wall 12R and a left
side wall 12LS of the furnace enclosure 12' are entirely shown in
FIG. 2. The front wall 12F and right side 12RS wall are shown with
portions removed to provide a view of the interior components of
the furnace. It should be understood that the front and rear walls
have the same width and height dimensions and the left side and
right side walls have the same width and height dimensions whereby
the enclosure has the exterior configuration of a rectangular cube.
The front wall 12F of the furnace enclosure or the bottom of the
furnace enclosure is provided with an air inlet opening that allows
ambient air of the residence in which the furnace is used to enter
into the enclosure interior 14'. The air inlet opening is often
communicated with a cold air return duct system of the residence.
Air that is heated by the furnace 10' is discharged to an air
distribution conduit system of the residence (not shown) through a
distribution air outlet opening 18'. The distribution air outlet
opening 18' is positioned at the top of the enclosure shown in FIG.
2.
[0030] The primary heat exchanger 22' is positioned at the top of
the enclosure interior volume 14' adjacent the distribution air
outlet opening 18'. The secondary heat exchanger 24' is positioned
just below the primary heat exchanger 22'. The use of both a
primary heat exchanger and a secondary heat exchanger qualifies the
furnace of the invention as a high efficiency furnace, or a 90+
AFUE furnace.
[0031] The blower 38 of the invention is positioned in the
enclosure interior 14' at the same position as the prior art blower
26, i.e., just below the secondary heat exchanger 24'. Comparing
the prior art of FIG. 1 with the furnace of the invention shown in
FIG. 2, it can be seen that the blower 38 of the invention employs
a fan wheel 42 having a smaller circumferential dimension C and a
smaller diameter dimension D from the fan wheel 28 of the prior
art. The fan wheel has an axis of rotation 44 that defines mutually
perpendicular axial and radial directions relative to the blower
38. As shown in FIG. 2, the fan wheel rotates in a clockwise
rotation direction when the fan is operating. Rotation of the fan
wheel 42 draws ambient air into the blower 38 as represented by the
arrow labeled (AIR FLOW) in FIG. 2. In the preferred embodiment,
the fan wheel 42 is comprised of a plurality of forward curved fan
blades 46. The forward curved fan blades 46 of the fan wheel 42
reduce the noise of operation of the fan wheel 42. Furthermore, the
air flow moving through the fan wheel 42 is concentrated in the
last half of the scroll shaped outer wall of the blower housing,
and especially in the last 90 degrees of the scroll shaped outer
wall where the expansion angle of the outer wall exceeds 10
degrees. This creates a higher velocity of air flow through the
forward curved fan blades 46, which increases the static pressure
gained on the fan wheel 42 due to the coriollis effect. The higher
air flow velocity also increases the velocity head of the air flow
off of the forward curved blades 46. This effect reduces the size
of the fan wheel required for an equal powered blower, and
increases the efficiency of the blower due to the greater pressure
being generated on the fan wheel blades.
[0032] The apparent way to increase the exhaust area size of the
blower housing air outlet opening is to increase the expansion
angle of the blower housing outer wall. However, the prior art
practice has been to design blower housings with a constant
expansion angle. Some prior art blower housings have used
increasing expansion angles, but the manner in which the blower
housing's expansion angles were increased did not achieve the
desired effect due to either the rate of increasing the expansion
angle being inadequate, or the rate of increasing the expansion
angle being too large and thus missing the desired effect.
Additionally, increasing the expansion angle of the blower housing
outer wall creates an extremely large blower housing that does not
fit adequately in the typical furnace enclosure. The resultant
additional size of the furnace enclosure needed to house a blower
housing having an increased expansion angle creates a negative
aspect for the consumer, i.e., the furnace enclosure requires more
space in the consumer residence. Additionally, the manufacturer of
the furnace must add cost to make the larger enclosure to
accommodate the blower housing. Thus, merely increasing the exhaust
area of the air outlet opening of a blower housing by increasing
the expansion angle of the blower housing outer wall is not a
viable option.
[0033] FIG. 2 shows one side of the blower housing 48 of the
invention. FIG. 3 shows the opposite side of the blower housing 48,
with the blower housing having been removed from the high
efficiency furnace enclosure 12'. The opposite first 52 and second
54 side walls of the blower housing are constructed in the typical
manner as prior art blower housings and are basically flat,
parallel side walls positioned at axially opposite ends of the fan
wheel 42. An air inlet opening is provided in the first side wall
52, and an opening that accommodates the motor that rotates the fan
wheel 42 is provided in the second side wall 54. The side walls of
the blower housing of the invention are basically the same as those
of the prior art.
[0034] To obtain a large exhaust area of the blower housing air
outlet opening, the blower housing 48 of the present invention
utilizes an exponentially increasing expansion angle in the design
of the blower housing volute outer wall 56. FIG. 2 shows the blower
housing 48 positioned in the high efficiency furnace 10', with the
first side wall being removed to show the position of the fan wheel
42 in the interior of the blower housing 48 and the relative
positioning of the blower housing 48 in the furnace 10'. As shown
in FIG. 2, the novel configuration of the blower housing outer wall
56 creates an enlarged air outlet opening 58 of the blower housing.
This enlarged air outlet opening 58 directs distribution air over a
larger area of the secondary heat exchanger 24' and the primary
heat exchanger 22' than blower housings of the prior art such as
that shown in FIG. 1. This greater amount of distribution air is
represented by the arrows 62 in FIG. 2. The enlarged air outlet
opening 58 spreads the flow of air out over the furnace heat
exchanger and thereby reduces the pressure loss across the furnace.
This lowers the required pressure that the blower must generate,
and enables the use of a more efficient motor to operate the
blower.
[0035] Furthermore, the blower housing of the invention does a
superior job of pulling the air flow through the forward curved
impeller blades, along with converting the air flow velocity
through the housing scroll to usable static pressure. Although the
blower housing of the invention has special benefits with respect
to its use in furnaces by reducing the pressure through those
furnaces, the blower housing of the invention also has superior
efficiency as a blower housing used in an air handler where high
efficiency is desired.
[0036] As stated earlier, the larger air distribution outlet
opening 58 is achieved by employing an exponentially increasing
expansion angle in the design of the volute-shaped outer wall 56 of
the blower housing, as opposed to the constant increasing expansion
angle employed in the design of prior art blower housings. The
enlarged air outlet opening 58 is also achieved with the overall
blower housing width dimension, the length dimension and the depth
dimension of the blower housing 48 being the same as that of prior
art blower housings. The improved efficiency of the blower housing
enables a reduction in the exterior dimensions of the furnace
enclosure in which the blower housing is used.
[0037] With the exponentially increasing expansion angle of the
outer wall 56 of the blower housing, as the blower housing volute
outer wall 56 extends around the blower housing in the rotation
direction of the fan wheel, the scroll volume aggressively becomes
larger in the interior of the housing. This is especially true as
the outer wall 56 approaches the air outlet opening 58. This
increase in the interior volume enables exhaust velocities of air
flow to be reduced, and creates a blower housing where a greater
portion of the air flow velocity head is converted to static
pressure. This increases efficiency because the air flow velocity
head energy would have been lost outside of the scroll interior.
This further increases the overall efficiency of the blower
housing.
[0038] FIG. 4 is a schematic representation of a side view of the
blower housing volute outer wall 56 and the fan wheel 42 in the
blower housing. The description of the blower housing 48 and the
fan wheel 44 to follow is only one exemplary embodiment of the
blower 38 of the invention. In other environments the construction
of the blower housing and fan wheel may vary. However, as will be
explained, the construction and the design of the blower housing
outer wall 56 is based on an exponentially increasing expansion
angle, where many prior art blower housings have been designed with
a constant increasing expansion angle. The exponentially increasing
expansion angle can be utilized along the entire volute-shaped
length of the outer wall, or along only a portion of the
volute-shaped length of the outer wall, or along separate portions
of the volute-shaped length of the outer wall. Furthermore, the
construction of the volute outer wall radially opposite any point
on the circumference of the fan wheel is proportional to the
circumferential dimension of the fan wheel at that point, raised to
an exponential value.
[0039] The blower housing outer wall 56 has a volute-shaped portion
that defines a majority of the length of the outer wall. The
volute-shaped portion of the outer wall 56 could also be described
as having a scroll configuration or a spiral configuration. These
general configurations are common to blower housings of the prior
art. However, the novel configuration of the blower housing outer
wall 56 of the invention is defined as having an exponentially
increasing expansion angle as the volute-shaped wall 56 extends in
the rotation direction around the fan wheel axis of rotation 44. As
viewed in FIG. 4, the outer wall includes a cut-off portion 72. The
outer wall also includes a straight portion 74 at the enlarged air
outlet opening 58. The straight portion 74 of the outer wall has no
expansion angle and extends in a straight line. The volute-shaped
outer wall 56 is the length of the outer wall that extends from the
cutoff 72 to the straight portion 74.
[0040] FIG. 4 illustrates the dimensional relationship between the
circumference of the fan wheel 42 and the volute-shaped length of
the outer wall 56 of the invention. The fan wheel 42 shown in FIG.
4 has a diameter dimension D and circumference C dimension. In the
explanation of the construction of the blower housing outer wall 56
to follow, the dimensions of the outer wall are based on
circumferential dimensions of the fan wheel circumference. These
circumferential dimensions of the fan wheel begin at a beginning
point (a) on the fan wheel shown in FIG. 4. The dimensions are
measured around in a clockwise rotation direction as shown in FIG.
4 to an ending point on the fan wheel that coincides with the
beginning point (a). A line drawn from the fan wheel axis of
rotation 44 through the fan wheel beginning point (a) marks a zero
degree reference point on the circumference of the fan wheel.
[0041] Beginning from the fan wheel beginning point (a) at the zero
degree circumference of the fan wheel, and extending around the fan
wheel circumference in the clockwise direction of rotation of the
fan wheel shown in FIG. 4, a second point (b) is positioned on the
fan wheel 73 degrees from the first point (a). A third point (c) is
positioned on the fan wheel 90 degrees from the first point (a). A
fourth point (d) is positioned on the fan wheel 112.5 degrees from
the first point (a). A fifth point (e) is positioned on the fan
wheel 135 degrees from the first point (a). A sixth point (f) is
positioned on the fan wheel 157.5 degrees from the first point (a).
A seventh point (g) is positioned on the fan wheel 180 degrees from
the first point (a). An eighth point (h) is positioned on the fan
wheel 202.5 degrees from the first point (a). A ninth point (i) is
positioned on the fan wheel 225 degrees from the first point (a). A
tenth point (j) is positioned on the fan wheel 247.5 degrees from
the first point (a). An eleventh point (k) is positioned on the fan
wheel 270 degrees from the first point (a). A twelfth point (l) is
positioned on the fan wheel 292.5 degrees from the first point (a).
A thirteenth point (m) is positioned on the fan wheel 315 from the
first point (a). A fourteenth point (n) is positioned on the fan
wheel 337.5 degrees from the first point (a). A fifteenth point (o)
is positioned on the fan wheel 360 degrees from the first point (a)
and coincides with the first point. These multiple points on the
fan wheel are radially aligned with points on the blower housing
outer wall 56. The circumferential distances of the fan wheel
points (b-o) from the first point (a) on the fan wheel are employed
in calculating the distance of the blower housing outer wall 56
from the circumference of the fan wheel 44 at each of the radially
aligned points on the blower housing outer wall. In this way the
exponentially increasing expansion angle of the blower housing of
the invention is determined.
[0042] The beginning of the volute or scroll shaped configuration
of the outer wall 56 begins just past the cut-off portion 72 in the
direction of rotation of the fan wheel 44. The beginning end of the
volute-shaped length begins at a point (B) on the outer wall 56.
Point (B) is radially aligned with the 73 degree point (b) on the
circumference of the fan wheel 44. Although the cut-off 72 is shown
aligned with the 73.degree. point (b) in FIG. 4, locating the
cut-off at other angles, such as 68.degree., has been shown to be
effective in the blower housing of the invention. From this
beginning point (B) on the volute-shaped length on the outer wall
56, the outer wall length has points (C, D, E, F, G, H, I, J, K, L,
M, N, O) that are radially spaced outwardly from and correspond to
the respective circumferentially spaced points (c, d, e, f, g, h,
i, j, k, l, m, n, o) on the circumference on the fan wheel 42. The
volute-shaped length of the outer wall 56 has an ending point (O)
that is radially aligned with the zero degree fan wheel beginning
point (a) and the 360 degree fan wheel ending point (o).
[0043] The radial spacing between the points on the fan wheel
circumference and their radially aligned corresponding points on
the volute-shaped portion of the outer wall 56 is determined by the
equation: Y=A+B.times..sup.c
[0044] In the above equation, the "x" value is the circumferential
distance on the fan wheel circumference at which the radial spacing
between the fan wheel and the volute-shaped length of the outer
wall is being calculated. This value is raised to the exponential
power of (c). It has been determined empirically that the value (c)
for points on the circumference of the fan wheel 42 from the zero
degree fan wheel point (a) to the 270 degree fan wheel point (k) is
an exponent in the range of 1.2 to 1.4. In the example, the
exponent is 1.3. For points on the circumference of the fan wheel
from the 270 degree fan wheel point (k) to the fan wheel point
corresponding to 360 degrees (o), the value of the exponent "c" is
in the range of 1.5 to 2.1. In the example, the exponent is
1.81.
[0045] In an illustrative example of the above-referenced equation,
the "A" factor is a minimum height factor for the blower housing
48. In the example that follows, the minimum height factor "A" is
0.625 inches. The factor "B" in the above equation is a factor
picked by the furnace designer to create as large of an exhaust
opening as is practical, along with keeping the blower housing
within size restrictions of the furnace enclosure 12'. The furnace
designer designs the blower housing to allow a reasonable flow of
air around the blower housing in the enclosure 12', while trying to
hold down the exponential expansion of the blower housing outer
wall 56 as much as possible, while at the same time obtaining the
primary objective of a large air outlet opening 58. In the example
that follows, the factor "B" is 0.05645 for points on the
circumference of the fan wheel 42 from the zero degree fan wheel
point (a) to the 270 degree fan wheel point (k), and is 0.0128 for
the points on the circumference of the fan wheel from the 270
degree point (k) to the 360 degree fan wheel point (o).
[0046] The following is a table setting forth the circumferential
points on the circumference of the fan wheel 42 and the
corresponding radial distance (Y) to the radially aligned point on
the volute-shaped length 56 of the blower housing outer wall
calculated using the equation Y=A+B.times..sup.c. TABLE-US-00001
Fan A Y wheel circumference (inches) B C (inches) 1 a, A 0.degree.
2 b, B 73.degree. or 0.20 .pi. D 0.625 0.5645 1.3 5.938 3 c, C
90.degree. or 0.25 .pi. D 0.735 0.5645 1.3 6.047 4 d, D
112.5.degree. or 0.3125 .pi. D 0.940 0.5645 1.3 6.253 5 e, E
135.degree. or 0.375 .pi. D 1.185 0.5645 1.3 6.497 6 f, F
157.degree. or 0.4375 .pi. D 1.458 0.5645 1.3 6.770 7 g, G
180.degree. or 0.500 .pi. D 1.753 0.5645 1.3 7.066 8 h, H
202.5.degree. or 0.5625 .pi. D 2.068 0.5645 1.3 7.381 9 i, I
225.degree. or 0.625 .pi. D 2.400 0.5645 1.3 7.712 10 j, J
247.5.degree. or 0.6875 .pi. D 2.746 0.5645 1.3 8.059 11 k, K
270.degree. or 0.750 .pi. D 3.106 0.5645 1.3 8.419 12 l, L
292.5.degree. or 0.8125 .pi. D 3.641 0.0128 1.81 8.953 13 m, M
315.degree. or 0.875 .pi. D 4.220 0.0128 1.81 9.533 14 n, N
337.5.degree. or 0.9375 .pi. D 4.845 0.0128 1.81 10.158 15 o, O
360.degree. or .pi. D 5.515 0.0128 1.81 10.827 Y = A + Bx.sup.c D =
10.625''
[0047] The above table sets forth the exponentially increasing
expansion angle of the volute-shaped outer wall 56 of the invention
based on a fan wheel 42 having a diameter dimension D of 10.625
inches. It can be seen that the size of the fan wheel influences
the circumferential dimensions measured to the fan wheel points (b,
c, d, e, f, g, h, i, j, k, l, m, n, o) which are raised to an
exponential value to obtain the radial spacing between each of the
respective points on the circumference of the fan wheel 42 and a
radially aligned point on the volute outer wall 56. A blower
housing having a volute outer wall 56 designed according to the
earlier set forth equation and as illustrated in the above table
provides an enlarged air outlet opening 58 without significantly
increasing the overall dimensions of the blower housing 48 from
that of prior art blower housings.
[0048] In alternate embodiments of the invention, the expansion
angle of the volute outer wall 56 of the blower housing could
increase exponentially with there being a single exponent value for
the entire length of the volute-shaped outer wall 56. The expansion
angle could increase exponentially with there being a single
exponent value along a substantial portion of the volute-shaped
outer wall length 56, but not the entire length. Additionally, the
expansion angle could increase exponentially along separate
portions of the volute-shaped outer wall length, with there being
different exponent values for the separate portions of the
volute-shaped outer wall length.
[0049] In the alternate embodiments of the invention, in the last
90.degree. of the volute-shaped side wall length from point (K) to
point (0) or from 270.degree. to 360.degree. on the volute-shaped
length of the outer wall, the expansion angle increasing at an
exponential rate in a range of 1.5 to 2.1 enables the exhaust
velocities of the air flow to be reduced, and creates a blower
housing where a greater proportion of the air flow velocity head is
converted to static pressure. This increases the efficiency of the
blower housing because this velocity head energy would have been
lost outside of the blower housing. This further increases the
overall efficiency of the system. Too large of an expansion angle
outside of the desired range would over-expand the blower housing
and the area of air flow through the housing resulting in the air
flow velocity head conversion to static pressure being too little
and ineffective, failing to provide the effect needed.
[0050] In further embodiments of the invention, the blower housing
of the invention could be employed in a low profile furnace,
specifically an 80+ AFUE furnace, as well as in other types of
furnaces and air handlers, and also in AC units. The alternate
embodiment of a 80+ furnace is illustrated in FIG. 5. FIG. 5
illustrates the earlier described blower housing 48 of the
invention employed in a low profile furnace 82, where the low
profile furnace employs only a primary heat exchanger 84 and does
not include a secondary heat exchanger as described earlier. Used
in this environment, the blower housing 48 of the invention has
similar or superior static efficiency to that of a regular profile
blower. The use of the blower housing 48 in a low profile furnace
allows savings in shipping costs and sheet metal cost. The
particular two stage exponential growth of the volute outer wall 56
of the blower housing 48 provides similar performance and
efficiency to the low profile 80+ furnace as that of a regular
profile blower in a low profile size. In a similar manner to the
90+ furnace, in the 80+ furnace 82 where the primary heat exchanger
84 is located close to the blower housing air outlet opening, the
enlarged air outlet opening of the blower housing of the invention
directs air over a larger area of the heat exchanger 84 than blower
housings of the prior art, and thereby creates energy savings.
[0051] In addition to being employed in a 90+ furnace and an 80+
furnace, the blower housing 48 of the invention may be employed in
an air handler. Air handlers (abbreviated AHU) are employed in HVAC
systems to move air through the systems. A typical air handler
comprises a metal enclosure containing the blower housing of the
invention. The air handler enclosure is typically communicated with
one or more other enclosures containing heating and/or cooling
coils and air filters. The air handler typically communicates with
duct work that distributes the conditioned air through a building
and returns the air to the air handler. Air handlers are also used
to distribute air and return air directly to and from the area
being served by the air handler without duct work. In the typical
operation of an air handler, the rotation of the fan in the blower
housing of the invention would pull air through the air filter and
the heating and/or cooling coils to the blower housing and then
distribute the conditioned air from the blower housing.
[0052] Although the above equation and the above described method
of designing the volute-shaped outer wall of a blower housing based
on the circumference dimensions of the fan wheel are described with
reference to a particular fan wheel diameter dimension, there are
particular blower housing and fan wheel dimension relationships
that provide the synergistic effect of the increased efficiency of
the blower housing of the invention. In the blower housing of the
invention these synergistic results are achieved when the ratio of
the minimum radial dimension of the air outlet opening (for
example, the minimum dimension between the cutoff 72 at point (B)
and the end of the straight portion 74 of the blower housing outer
wall 48 opposite the point (O) shown in FIG. 4), and the fan wheel
outer diameter dimension is at least 0.73. In addition, the ratio
of the distance dimension between the fan wheel axis of rotation 44
and the second end of the blower housing outer wall volute-shaped
length at point (O), and the fan wheel outer diameter dimension is
at least 0.91. Furthermore, in the preferred embodiment the radial
distance between the fan wheel axis of rotation 44 and the
volute-shaped length of the blower housing outer wall increases as
the volute-shaped length extends from a first end of the
volute-shaped length around the fan wheel to the second end of the
volute-shaped length. Preferably the increase is exponential.
[0053] The dimensional relationships between the fan wheel and the
blower housing outer wall of the invention set forth above result
in the synergistic increase in the efficiency of the blower housing
of the invention. This synergistic increase in efficiency is the
result of three basic principles.
[0054] (1) The enlarged air outlet opening of the blower housing
spreads out the flow of air exiting the blower housing over the
furnace heat exchanger to a greater extent than prior art blower
housings, and thereby reduces the pressure loss across the furnace.
This lowers the required pressure that the blower must
generate.
[0055] (2) The flow of air moving through the fan wheel is
concentrated in the last half of the scroll configuration of the
blower housing, and especially in the last 90.degree. of the scroll
configuration from point (K) to point (0) or from 270.degree. to
360.degree. on the volute-shaped length of the outer wall. Here the
outer wall increases at an expansion angle of 10.degree. or
greater. This creates a higher air flow velocity through the
forward-curved blades of the fan wheel, which increases static
pressure gained on the fan wheel due to the coriollis effect. The
higher air flow velocity also increases the velocity head off of
the forwarded-curved blades of the fan wheel. This effect reduces
the size of the fan wheel required in the blower housing for an
equal powered blower, and increases the efficiency due to greater
pressure being generated on the fan wheel blades.
[0056] (3) The blower housing volume aggressively becomes larger in
the direction of fan wheel rotation in the blower housing of the
invention, especially toward the air outlet opening. This enables
the exhaust velocities of the air flow to be reduced, and creates a
blower housing where a greater portion of the air flow velocity
head is converted to static pressure. This increases the efficiency
of the blower housing because this velocity head energy would have
been lost outside of the blower housing. This further increases the
overall efficiency of the system.
[0057] FIG. 6 is a graph illustrating the gain in efficiency of a
high efficiency 90+ furnace employing the blower housing of the
invention as compared to high efficiency 90+ furnaces of the prior
art. In FIG. 6, the bottommost line on the graph represents the
operation of the blower housing of the invention in a 90+ furnace.
The other two graph lines represent the operation of 90+ furnaces
of the prior art. From this graph it can be seen that the blower
housing of the invention requires less horsepower of the fan wheel
motor to move a volume of air through the furnace than the blower
housings of the prior art.
[0058] FIG. 7 is a graph similar to that of FIG. 6, but showing a
comparison of the low profile 80+ blower housing of the invention
compared with a low profile blower housing of the prior art. In
FIG. 7, the lower line on the graph represents the operation of the
low profile blower housing of the invention. In this graph it can
also be seen that the low profile blower housing of the invention
requires less horsepower to move a volume of air as compared to a
blower housing of the prior art.
[0059] The above described embodiments of the invention were chosen
in order to best explain the principles of the invention and its
practical application to thereby enable others skilled in the art
to best utilize the invention in various embodiments and with
various modifications as are suited to the particular use
contemplated.
[0060] As various modifications could be made in the constructions
herein described and illustrated without departing from the scope
of the invention, it is intended that all matter contained in the
foregoing description or shown in the accompanying drawings shall
be interpreted as illustrative rather than limiting. Thus, the
breadth and scope of the present invention should not be limited by
any of the above-described exemplary embodiments, but should be
defined only in accordance with the following claims appended
hereto and their equivalents.
* * * * *