U.S. patent application number 10/080200 was filed with the patent office on 2002-08-29 for centrifugal blower with partitioned scroll diffuser.
Invention is credited to Dickinson, Roger B., Marvin, Russel H., O'Connor,, John F. JR..
Application Number | 20020119044 10/080200 |
Document ID | / |
Family ID | 26763204 |
Filed Date | 2002-08-29 |
United States Patent
Application |
20020119044 |
Kind Code |
A1 |
O'Connor,, John F. JR. ; et
al. |
August 29, 2002 |
Centrifugal blower with partitioned scroll diffuser
Abstract
A centrifugal blower having at least one radial plane dividing
its scroll into sub-sections which may vary as to cut-off points
and axial and radial dimensions as well as axial displacement to
meet requirements of individual application system flow paths.
Inventors: |
O'Connor,, John F. JR.; (New
Hartford, CT) ; Dickinson, Roger B.; (Torrington,
CT) ; Marvin, Russel H.; (Goshen, CT) |
Correspondence
Address: |
Russel H. Marvin, CTO
Torrington Research Company
88 Commercial Boulevard
Torrington
CT
06790
US
|
Family ID: |
26763204 |
Appl. No.: |
10/080200 |
Filed: |
February 19, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60270932 |
Feb 26, 2001 |
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Current U.S.
Class: |
415/204 ;
415/206 |
Current CPC
Class: |
F04D 29/4246
20130101 |
Class at
Publication: |
415/204 ;
415/206 |
International
Class: |
F01D 001/02 |
Claims
What is claimed is:
1. A centrifugal blower assembly comprising: a centrifugal impeller
adapted to receive air axially and discharge the same radially; an
electric motor connected in driving relationship with the impeller;
a scroll diffuser defining at least one axial inlet opening for
supplying air to the impeller, and at least one scroll section for
collecting and discharging air from the impeller, and at least one
partition extending substantially in a radial plane mounted within
the housing with an inner opening receiving and having an edge in
close proximity to the periphery of the centrifugal impeller, said
partition serving to divide the scroll interior into at least two
discrete axially adjacent flows for the discharge of air from the
scroll section.
2. A centrifugal blower assembly as set forth in claim 1, wherein
said scroll section comprises at least two discrete scroll
sub-sections associated respectively with said at least two axially
adjacent flows.
3. A centrifugal blower assembly as set forth in claim 2, wherein
each of said at least two scroll sub-sections is configured to
provide an independently optimized expansion rate.
4. A centrifugal blower assembly as set forth in claim 2, wherein
said at least two scroll sub-sections have differing configurations
of their outer walls, each spaced radially from but facing the
periphery of the impeller.
5. A centrifugal blower assembly as set forth in claim 2, wherein
the axial dimension of at least one of said at least two scroll
sub-sections varies as the air proceeds from the impeller to an
associated discharge opening.
6. A centrifugal blower assembly as set forth in claim 5, wherein
the manner in which the axial dimensions of said two sub-sections
varies is different.
7. A centrifugal blower assembly as set forth in claim 2, wherein
the centerlines of the flows through the sub-sections differ.
8. A centrifugal blower assembly as set forth in claim 4, wherein
the discharge openings of the two sub-sections are substantially
rectangular in cross section and are arranged in adjacent
end-to-end relationship to provide an elongated discharge
opening.
9. A centrifugal blower assembly as set forth in claim 4, wherein
the discharge openings of the two sub-sections are arranged in
adjacent side-by-side relationship to provide an aggregate
discharge opening of substantially enlarged width.
10. A centrifugal blower assembly as set forth in claim 4, wherein
the discharge openings of the two sub-sections are arranged in
angularly spaced apart relationship.
11. A centrifugal blower assembly as set forth in claim 8, wherein
the scroll sub-sections are configured with varying axial
dimensions and at least one sub-section is displaced axially as it
approaches its discharge opening to provide for an aggregate
elongated discharge opening having substantially a common
longitudinal centerline.
12. A centrifugal blower assembly as set forth in claim 2, wherein
said at least two scroll sub-sections have cut-off points
substantially at the same point circumferentially along the
periphery of the impeller opening in the partition.
13. A centrifugal blower assembly as set forth in claim 2, wherein
said at least two scroll sub-sections have cut-off points spaced
circumferentially from each other.
14. A centrifugal blower assembly as set forth in claim 2, wherein
said at least two scroll subsections have discharge openings with
substantially parallel centerlines.
15. A centrifugal blower assembly as set forth in claim 2, wherein
said at least two scroll sub-sections have discharge openings with
centerlines angularly related to each other.
16. A centrifugal blower assembly as set forth in claim 1, wherein
said edge of said inner opening in said partition takes a thin
rounded configuration facing the impeller.
17. A centrifugal blower assembly as set forth in claim 16, wherein
said edge is inclined gradually outwardly on opposite sides from
said rounded configuration to the full thickness of the
partition.
18. A low profile centrifugal impeller assembly comprising: a
centrifugal impeller adapted to receive air axially and discharge
the same radially; said impeller comprising a back plate with a
radially outwardly disposed annular portion extending substantially
in a radial plane, and a plurality of substantially axially
extending parallel air moving blades spaced circumferentially and
having one end portion mounted on said outwardly disposed annular
portion of the back plate, a radially inwardly disposed portion of
the back plate having a cup-shaped configuration and extending
axially within the outer back plate portion in a cylindrical
opening defined by the air moving blades thereon, and at least a
permanent magnet portion of an electric motor for driving the
impeller disposed within the cup-shaped radially inner portion of
the back plate; a housing defining at least one axial inlet opening
for supplying air to the impeller and at least one scroll section
for collecting and discharging air from the impeller.
19. A centrifugal blower assembly as set forth in claim 18, wherein
the depth of said cup-shaped back plate portion is at least equal
to the length of the air moving blades.
20. A centrifugal blower assembly as set forth in claim 19, wherein
said back plate is constructed of a molded thermoplastic.
21. A centrifugal blower assembly as set forth in claim 1, wherein
a flow balancing restriction is incorporated in at least one of
said scroll sub-sections.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a partitioned scroll diffuser,
designed to efficiently provide multiple flow paths from a single
centrifugal impeller.
[0002] One of the challenges for a designer of centrifugal blowers
is to provide a scroll diffuser which efficiently converts velocity
pressure to static pressure and at the same time aligns discharge
flow accurately with the system flow paths required in a particular
application of the blower. Efficient alignment of the discharge
flow with the required system flow paths is essential in achieving
the desired performance in a small package with low noise
characteristics.
[0003] In certain applications, aligning the discharge flow from
the scroll diffuser requires multiple discharges or a "high aspect
ratio" single discharge. To date, one of two scroll housing
configurations has been employed. The first is a multiple guide
vane arrangement in the scroll diffuser as illustrated in FIGS. 1a,
1b and 1c. The second configuration employs multiple discharges
from single plane symmetrical scroll diffusers, in some instances
in combination with guide vanes, see FIGS. 2a and 2b. Efficiency of
the impeller assembly is adversely affected along with excess noise
generation in either of these configurations.
SUMMARY OF THE INVENTION
[0004] A general object of the present invention is to provide an
improved scroll diffuser which overcomes the disadvantages of the
aforesaid scroll diffusers, this result being achieved with a
single centrifugal impeller.
[0005] In accordance with the present invention, at least one
partition extending substantially in a radial plane is provided
within the scroll diffuser of a centrifugal blower and has an inner
opening receiving and having its edge in close proximity with the
periphery of the centrifugal impeller. The partition serves to
divide the scroll diffuser interior into at least two discrete
axially adjacent flows for the discharge of air from the scroll
section. More specifically, the scroll section of the impeller
assembly is divided into at least two discrete scroll sub-sections
in axially adjacent relationship and associated respectively with
said at least two axially adjacent flows. The scroll sub-sections
may provide for discharge openings which are axially and/or
angularly displaced or the scroll sub-sections may be axially
configured or displaced relative to each other to provide a common
axially aligned discharge opening of increased length. Each scroll
sub-section can be designed with its own expansion rate as required
by discharge flow requirements and the scroll sub-section cut-offs
can be rotated through an infinite number of angular positions
while maintaining efficient impeller performance for each
sub-section flow. It should be noted that prior art configurations
require that scroll cut-offs be 180.degree. apart to achieve
reasonable efficiency in the absence of a vane diffuser as in FIGS.
2a and 2b.
[0006] The design concept may be employed in any centrifugal blower
assembly including but not limited to a forward curved impeller
blade type, a backward inclined impeller blade, and a backward
curved impeller blade. Plastic, metal or other construction is also
accommodated. The number of radial plane partitions in the diffuser
may vary as required. The axial width of each flow channel may also
vary as well as the diffuser radial expansion angle and/or rate of
expansion.
[0007] Benefits to the designer include allowing for variations in
size and position of each housing discharge opening as the system
application may require. Further, each scroll diffuser section may
be designed to optimize the flow and pressure characteristics of
the particular system flow paths involved. Benefits to the
purchaser of the improved blower with partitioned scroll diffuser
include a simple design versus multiple motorized impellers. The
single impeller approach helps to reduce noise generation, lower
power consumption, minimize space use, and increase
reliability.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1a is a schematic view of a prior art centrifugal
blower with vanes provided in the diffuser resulting in a broad
band discharge flow equal to approximately the diameter of the
impeller.
[0009] FIG. 1b is a prior art schematic showing a centrifugal
blower assembly provided with vanes resulting in a broad band
discharge approximating twice the diameter of the impeller.
[0010] FIG. 1c is a further prior art schematic showing a
centrifugal blower assembly with outlet vanes resulting in a
diameter approximating three diameters of an impeller wheel.
[0011] FIG. 2a is a prior art schematic showing a centrifugal
blower having discharge openings 180.degree. opposed.
[0012] FIG. 2b is a further prior art schematic showing a vane
diffuser with multiple discharge flow paths.
[0013] FIG. 3 is a sectional side view of a centrifugal blower
constructed in accordance with the present invention and having a
radial plane partition in the scroll section.
[0014] FIG. 4 is a perspective view of a centrifugal blower
constructed in accordance with the present invention and having
discrete angularly related discharge flows.
[0015] FIG. 5 is a schematic of the FIG. 4 blower assembly and
illustrates the flexibility of the invention in providing for an
infinite choice of scroll cut-off angles.
[0016] FIG. 6 is a schematic view of a centrifugal blower similar
to FIG. 5 and illustrates the ability to provide for a variety of
selected scroll expansion dimensions as may be required for
selected flow paths.
[0017] FIG. 7 is a schematic showing the arrangement of scroll
subsections providing for an elongated aligned discharge flow.
[0018] FIG. 8 is an end view of the schematic of FIG. 7.
[0019] FIG. 9 is an enlarged sectional view showing the radial
plane partition of FIG. 3.
[0020] FIG. 10 is an enlarged sectional view of an impeller with a
deep cup-shaped back plate.
DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
[0021] FIGS. 1a through 2b illustrate various prior art designs
employed in providing broad band and other discharge flow patterns
primarily through the use of a plurality of vanes mounted in the
scroll diffuser outlet section.
[0022] Referring particularly to FIG. 3, a centrifugal blower in
accordance with the invention and indicated generally at 10
includes an impeller 12 which may take a conventional form and
which receives inlet air axially through an opening 14 in an upper
scroll sub-section 18. Upper and lower scroll sub-sections 18 and
20 are partially shown at the left-hand portion of the drawing. The
scroll may be of metal or thermoplastic construction and includes a
radial plane partition 22 mounted therewithin and which has a
central opening 24 closely surrounding the periphery of the
impeller 12.
[0023] In accordance with the invention, the sub-sections 18 and 20
of the scroll are separated by the partition 22 and as illustrated
in FIG. 5 are wholly independent of each other. Thus, the sections
18 and 20 may be designed with their cut-off points 26 and 28
angularly spaced apart circumferentially as shown. Similarly, the
design of the sub-sections may have their expansion angles or rates
wholly independent of each other. In FIG. 5, the radial expansion
of the sub-sections 18 and 20 is substantially the same, but may
vary substantially as will be seen hereinbelow.
[0024] FIG. 7 illustrates an impeller assembly 30 in accordance
with the present invention and which has scroll sub-sections 32 and
34 which differ substantially with regard to their expansion rates.
That is, the width of the scroll or the dimension from the impeller
measured radially to the scroll sidewall varies substantially
between scroll sub-sections 32 and 34. Further, the axial
dimensions of the scrolls 32 and 34 may be varied and the scroll
sub-sections may be progressively displaced bodily in an axial
direction as they approach their respective discharge openings 36
and 38, each of which may be substantially rectangular. FIG. 8
illustrates the discharge openings 36, 38 from the front and it
will be observed that the openings are aligned in end-to-end
relationship with a common centerline 40, and a flow balancing
restriction 39 in opening 38. Thus, a substantially elongated
combined discharge opening is provided with the single impeller and
discharge flow path requirements for the impeller are
satisfied.
[0025] From the foregoing it will be seen that the scroll
sub-sections may vary in axial dimension, radial dimension and the
sections may also be bodily displaced axially relative to each
other to provide an aligned elongated opening having a common
centerline as in FIG. 8.
[0026] FIG. 9 illustrates a preferred construction of the edge of
the central opening in the radial partition 22. As will be seen, a
rounded "bullet nose" leading edge is provided at 42 and gradually
inclined sections 44, 44 extend outwardly therefrom to the full
thickness of the partition. Efficient operation is achieved with
this construction at low levels of noise generation.
[0027] In FIG. 10 an impeller 45, partially illustrated in
cross-section, has a back plate with an outer annular portion 46 in
a radial plane. A central section 48 of the back plate takes a
cup-shape and resides within a central opening defined by impeller
blades, 50, 50. The impeller blades 50, 50 are mounted at one end
portion on the outer annular back plate portion 46 and extend
therefrom with the central opening defined therewithin. At least a
portion of an electric motor is mounted within the cup-shaped
element 48 in the form of a permanent magnet 52. Preferably and as
shown, the cup-shaped element 48 is of equal length with the blades
50, 50 to maximize the reduction in height of the overall assembly.
This dimension is particularly important in applications of small
centrifugal impellers for cooling purposes in electronic
devices.
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