U.S. patent application number 14/690776 was filed with the patent office on 2015-10-29 for fan blade edge.
The applicant listed for this patent is ebm-papst Mulfingen GmbH & Co. KG. Invention is credited to Martin Baer, Daniel Gebert, Michael Strehle.
Application Number | 20150308451 14/690776 |
Document ID | / |
Family ID | 53002585 |
Filed Date | 2015-10-29 |
United States Patent
Application |
20150308451 |
Kind Code |
A1 |
Baer; Martin ; et
al. |
October 29, 2015 |
FAN BLADE EDGE
Abstract
The invention relates to the blades of a fan wheel. The
invention particularly relates to a hollow profiled blade for a fan
wheel. A hollow profiled blade according to the invention for a fan
wheel is made from a planar semi-finished product and has a leading
edge and a trailing edge as well as a compression side and a
suction side. A hollow area is formed in the interior of the hollow
profiled blade whereby the part of the planar semi-finished product
forming the one side of the hollow profiled blade extends over the
part of the planar semi-finished product forming the other side of
the hollow profiled blade.
Inventors: |
Baer; Martin; (Mulfingen,
DE) ; Gebert; Daniel; (Ohringen, DE) ;
Strehle; Michael; (Ingelfingen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ebm-papst Mulfingen GmbH & Co. KG |
Mulfingen |
|
DE |
|
|
Family ID: |
53002585 |
Appl. No.: |
14/690776 |
Filed: |
April 20, 2015 |
Current U.S.
Class: |
416/232 |
Current CPC
Class: |
F05D 2230/54 20130101;
F04D 29/281 20130101; F05D 2250/291 20130101; F04D 29/388 20130101;
F05D 2240/304 20130101; F05D 2230/232 20130101; F04D 29/626
20130101; F05D 2300/10 20130101; B23P 15/02 20130101; F05D 2220/36
20130101; F04D 17/16 20130101; F01D 5/147 20130101; F04D 29/30
20130101 |
International
Class: |
F04D 29/38 20060101
F04D029/38; F04D 29/62 20060101 F04D029/62; F04D 17/16 20060101
F04D017/16 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2014 |
DE |
102014207903.9 |
Claims
1. A hollow profiled blade for a fan wheel whereby the hollow
profiled blade is manufactured from at least a first planar
semi-finished product and has a leading edge and a trailing edge as
well as a compression side and a suction side and whereby a hollow
area is formed in the interior of the hollow profiled blade whereby
the compression side has a first part of the first planar
semi-finished product and the suction side has a second part of the
first planar semi-finished product, characterized in that the
hollow profiled blade has a wall thickness which is less than twice
the wall thickness of the first planar semi-finished product in an
area which is arranged in front of the trailing edge and directly
adjacent to the trailing edge.
2. A hollow profiled blade according to claim 1 characterized in
that the hollow profiled blade has a wall thickness in the area
which essentially corresponds to the wall thickness of the first
planar semi-finished product.
3. A hollow profiled blade according to claim 1 characterized in
that the first part of the first planar semi-finished product
extends beyond the second part of the planar semi-finished product
in the area.
4. A hollow profiled blade according to claim 1 characterized in
that the second part of the first planar semi-finished product
extends over the first part of the planar semi-finished product in
the area.
5. A hollow profiled blade according to claim 1 characterized in
that the first part of the planar semi-finished product of the
hollow profiled blade is connected tightly and flush with the
second part of the first planar semi-finished product.
6. A hollow profiled blade according to claim 4 characterized in
that the position of the bend of the first part of the first planar
semi-finished product forms an abrupt change in thickness in the
profile of the hollow profiled blade on the second part of the
first planar semi-finished product.
7. A hollow profiled blade according to claim 6 characterized in
that the first part of the planar semi-finished product of the
hollow profiled blade is welded tightly and flush to the second
part of the first planar semi-finished product by a fillet
weld.
8. A hollow profiled blade according to claim 6 characterized in
that the ratio of the magnitude of the abrupt change in thickness
to the length by which the second part of the first planar
semi-finished product of the hollow profiled blade extends over the
position of the bend of the first part of the first planar
semi-finished product lies in the range from 1:1 to 1:100.
9. A hollow profiled blade according to claim 6 characterized in
that the ratio of the magnitude of the abrupt change in thickness
to the length by which the second part of the first planar
semi-finished product of the hollow profiled blade extends over the
position of the bend of the first part of the first planar
semi-finished product lies in the range from 1:2 to 1:20.
10. A hollow profiled blade according to claim 1 characterized in
that, a stiffener profile is arranged in the interior of the hollow
profiled blade.
11. A hollow profiled blade according to claim 10 characterized in
that, the stiffener profile is formed from the bent portion of the
first part of the first planar semi-finished product.
12. A hollow profiled blade according to claim 10 characterized in
that the stiffener profile can be manufactured by bending.
13. A hollow profiled blade according to claim 1 characterized in
that a part of the first planar semi-finished product lies flat on
one side of the hollow profiled blade in the interior of the hollow
profiled blade in the area of the trailing edge.
14. A hollow profiled blade according to claim 13 characterized in
that the overlying part of the first planar semi-finished product
in the area of the trailing edge lies flat on the suction side of
the hollow profiled blade in the interior of the hollow profiled
blade.
15. A hollow profiled blade according to claim 1 characterized in
that the hollow profiled blade is made from precisely a first
planar semi-finished product,
16. A hollow profiled blade according to claim 1 characterized in
that, in the area a second planar semi-finished product is arranged
whereby this second planar semi-finished product extends over the
first planar semi-finished product in the direction of the trailing
edge of the hollow profiled blade and whereby the wall thickness of
the second planar semi-finished product is less than twice the wall
thickness of the first planar semi-finished product.
17. A hollow profiled blade according to claim 16 characterized in
that, the second planar semi-finished product extends into the
interior of the hollow profiled blade.
18. A hollow profiled blade according to claim 16 characterized in
that the first part of the first planar semi-finished product of
the hollow profiled blade and/or the second part of the first
planar semi-finished product is connected tightly and flush with
the second planar semi-finished product.
19. A hollow profiled blade according to claim 18 characterized in
that, the first part of the first planar semi-finished product of
the hollow profiled blade and/or the second part of the first
planar semi-finished product is welded to the second planar
semi-finished product by a fillet weld.
20. A hollow profiled blade according to claim 16 characterized in
that a stiffener profile is arranged in the interior of the hollow
profiled blade.
21. A hollow profiled blade according to claim 20 characterized in
that, the stiffener profile is formed from the second of the planar
semi-finished products.
22. A hollow profiled blade according to claim 20 characterized in
that the stiffener profile can be manufactured by bending.
23. A fan wheel for a radial fan with a top plate and a base plate,
characterized in that, the fan wheel has several hollow profiled
blades between the top plate and the base plate.
24. A fan wheel according to claim 23, characterized in that, the
hollow profiled blades have lugs in its upper and/or lower narrow
side, while the top plate and/or the base plate have slots into
which the lugs can be inserted to secure the hollow profiled blades
between the top plate and the base plate.
Description
[0001] The invention relates to the blades of a fan wheel. The
invention particularly relates to the edge of a hollow profiled
blade for a fan wheel.
[0002] The purpose of fan wheels in radial or axial fans is to
convey and/or compress gaseous media, particularly air. Several
blades are arranged in a fan wheel whereby the flow channels are
developed between the blades. Each blade has a compression and a
suction side. The manufacture of blades from metallic materials in
sheet form as hollow profiled blades for fan wheels is known from
the state of the art. The advantage of such a design is the
possibility it affords of manufacturing a blade from a
semi-finished product whereby the manufacture has economic
advantages. The hollow profile form also has advantages with regard
to the weight of the blade, whereby the load on the drive motor is
reduced. In addition, material is saved by using this design,
whereby costs can be reduced.
[0003] For example, the unexamined German application DE 10 2011
013 841 A1 discloses such a blade with a hollow profile made from a
metallic material. Each hollow profiled blade is made from a
semi-finished product whereby the blades have a cross-section of a
load-bearing type. In particular the blade has a leading edge and a
trailing edge whereby the leading edge is formed from the curved
semi-finished product. The two ends of the semi-finished product
meet such they lie flat on each other at the trailing edge. In
doing so, this design takes account of the knowledge that a hollow
profile blade has an ideal aerodynamic shape if its trailing edge
is as thin as possible. In other words, for an aerodynamically
ideal shape of a hollow profile blade it is necessary to have a
trailing edge which has a wall thickness which is as thin as
possible. In the example in the disclosure the wall thickness of
the trailing edge is approximately twice the wall thickness of the
semi-finished product which is used. Both ends of the semi-finished
product can be joined to each other with known methods such as
welding or hard soldering.
[0004] The blade profile of the disclosure also has a continuous
progression of the surface contour. According to the opinion known
in the state of the art, protrusions, ledges or similar in the
blade geometry have a deleterious effect on the flow behavior.
[0005] A progression which is aerodynamically favorable occurs if
the medium which is flowing moves if at all possible along the
adjacent surface of the blades in such a manner that its velocity
vectors are aligned as parallel as possible to the blade surface.
Flow separations, turbulence or similar are normally undesirable as
they cause losses in the flow. These flow situations which deviate
from a beneficial flow progression reduce efficiency, impair the
acoustic performance and can lead to unstable characteristic
curves.
[0006] The problem of the invention is to indicate a hollow
profiled blade for a fan wheel which optimizes the efficiency and
acoustic performance of known hollow profiled blades. It is also
the problem of the invention to indicate a fan wheel for a radial
fan which exhibits improved efficiency and an improved acoustic
performance compared with known fan wheels.
[0007] According to the invention, this problem is solved by a
hollow profiled blade with the attributes of the independent claim
1. Advantageous developments of the hollow profiled blade result
from sub-claims 2 to 22. The problem is further solved by a fan
wheel according to claim 23 and claim 24.
[0008] A hollow profiled blade for a fan wheel according to the
invention is manufactured from at least one first planar
semi-finished product and has a leading edge and a trailing edge as
well as a compression side and a suction side whereby the
compression side has a first part of the first planar semi-finished
product and the suction side has a second part of the first planar
semi-finished product. Inside the hollow profiled blade is a hollow
area in which the hollow profiled blade has a wall thickness in an
area arranged in front of the trailing edge and immediately
adjacent to the trailing edge which is less than twice the wall
thickness of the first planar semi-finished product. This design
achieves a blade with a trailing edge at the end with a very thin
geometry whereby the hollow profiled blade is aerodynamically
optimized. In addition, in the area of the trailing edge of the
hollow profiled blade the first part of the first planar
semi-finished product is bent through approximately 180.degree. and
passed inwards into the hollow area of the hollow profiled blade.
The first part of the first planar semi-finished product which is
passed inwards into the hollow area of the hollow profiled blade
has the effect of reinforcing the hollow profiled blade whereby the
deformations which are possible precisely in the area of the
trailing edge of the blade during the operation of the blade are
minimized. Alternatively, the second part of the first planar
semi-finished product can be bent through approximately 180.degree.
and passed inwards into the hollow area of the hollow profiled
blade, whereby the effect is the same.
[0009] In a preferred embodiment, in the area which is in front of
the trailing edge and directly adjacent to the trailing edge, the
hollow profiled blade has a wall thickness which corresponds
essentially to the single wall thickness of the first planar
semi-finished product.
[0010] As such, in one embodiment, the first part of the first
planar semi-finished product can extend over and beyond the second
part of the planar semi-finished product in the area which is in
front of the trailing edge and directly adjacent to the trailing
edge. For example, in a first embodiment the compression side of
the hollow profiled blade can be formed from the first part of the
first planar semi-finished product of the hollow profiled blade,
while the suction side is formed from the second part of the first
planar semi-finished product of the hollow profiled blade whereby
the first part of the first planar semi-finished product extends
over and beyond the second part of the planar semi-finished product
in the area of the trailing edge of the blade. In an alternative
embodiment the second part of the first planar semi-finished
product can extend over and beyond the first part of the planar
semi-finished product in the area of the trailing edge of the
blade.
[0011] The planar semi-finished product normally consists of a
sheet, for example of a metallic material. The sheet can be bent,
for example, on a press brake.
[0012] In an advantageous embodiment the first part of the first
planar semi-finished product of the hollow profiled blade is
connected tightly and flush with the second part of the first
planar semi-finished product. This connection can, for example,
consist of a weld seam or also of individual spot welds. It is
advantageous if the connection point lies in an area which is close
to the trailing edge of the blade and positioned at a distance from
the leading edge of the hollow profiled blade.
[0013] In a further particularly advantageous embodiment, the
position of the bend of the first part of the first planar
semi-finished product on the second part of the first planar
semi-finished product forms an abrupt difference in thickness in
the profile of the hollow profiled blade. The invention recognizes
that contrary to the state of the art which stipulates a constant
contour progression for a parallel, low loss flow over a blade, it
can be possible to diverge from this under certain circumstances.
If certain geometric ratios are maintained a largely parallel flow
over the blade can be achieved in spite of an irregular progression
of the blade.
[0014] In a further preferred embodiment, the first part of the
first planar semi-finished product of the hollow profiled blade is
welded to the second part of the first planar semi-finished product
by a fillet weld. Surprisingly, the weld seam has only a small
effect of the flow of the medium. A small area of turbulence forms
in the flow in this area which, from the point of view of the
flowing medium, almost equalizes the abrupt change in thickness of
the hollow profile blade at this point and therefore encourages a
parallel flow. Other forms of weld seams or alternatively spot
welding are also possible but encourage the formation of a parallel
flow at this point to a less optimal degree.
[0015] It has been shown to be advantageous if the length by which
the second part of the first planar semi-finished product of the
hollow profile blade extends over the position of the bend of the
first part of the first planar semi-finished product is precisely
so long that it is up to 100 times longer than the magnitude of the
abrupt change in thickness. In other words it is advantageous if
the ratio of the magnitude of the abrupt change in thickness to the
length by which the second part of the first planar semi-finished
product extends over the position of the bend of the first part of
the first planar semi-finished product lies in the range from 1:1
to 1:100. In this case it has been shown to be particularly
advantageous if this ratio lies in the range from 1:2 to 1:20. In
such an order of magnitude the flow turbulence which forms at the
abrupt change of thickness is particularly suited to minimize the
aerodynamic effects of the abrupt change in thickness.
[0016] In an advantageous embodiment a stiffener profile is
arranged in the interior of the hollow profiled blade. Deformations
appear when the blades are operating, for example through the
difference in pressure of the flow medium between the compression
and the suction sides and as a result of centrifugal forces; these
deformations usually occur in the elastic range of the material. As
a result of these deformations the blade profile can change and the
efficiency can be impaired thereby. In addition, a deformation of
this nature can also influence noise emission. The stiffener
profile reduces this potential deformation and therefore optimizes
efficiency and noise emission during operations. The resultant
mechanical tensions and deformations also limit the permissible
rotational speed range.
[0017] In a further advantageous embodiment, the stiffener profile
is formed from the reverse bent part of the first part of the first
planar semi-finished product. This embodiment can be manufactured
particularly easily whereby the advantage is particularly great if
the stiffener profile can be made by bending.
[0018] It has also proved to be advantageous if, in the interior of
the hollow profiled blade, a part of the first planar semi-finished
product lies flat on one side of the hollow profiled blade in the
region of the trailing edge. In this form, the area of the trailing
edge includes not only the part lying directly on the trailing edge
of the blade but also an area starting from about the central point
between the leading edge and the trailing edge through to the
trailing edge itself.
[0019] In an advantageous embodiment the part of the first planar
semi-finished product in the interior of the hollow profiled blade
lies flat on the suction side of the hollow profiled blade whereby
the area of the trailing edge is defined as described above. This
design can be manufactured particularly easily and leads to a
hollow profiled blade which is optimized from the point of view of
torsional stiffness. This development leads to the fact that in the
corresponding region the hollow profiled blade exhibits a wall
thickness which is three times that of the planar semi-finished
product used for the manufacture of the blade, while the region of
the trailing edge which extends beyond the reverse bent part of the
first part of the first planar semi-finished product consists of
only one layer of the first planar semi-finished product and
therefore has a wall thickness of only one layer of the first
planar semi-finished product which is used.
[0020] In a further advantageous embodiment the hollow profiled
blade is manufactured from precisely one first planar semi-finished
product whereby a particularly economic manufacturing process is
possible.
[0021] In an alternative embodiment a second planar semi-finished
product is arranged in the area which is in front of the trailing
edge and directly adjacent to the trailing edge. In this embodiment
this second planar semi-finished product extends over the first
planar semi-finished product in the direction of the trailing edge
of the hollow profiled blade. The wall thickness of the second
planar semi-finished product is less than twice the wall thickness
of the first planar semi-finished product. Thus also in this
embodiment in the area which is in front of the trailing edge and
immediately adjacent to the trailing edge a wall thickness of the
hollow profiled blade is created which is less than twice the wall
thickness of the first planar semi-finished product. In particular
the wall thickness of the hollow profiled blade in the area which
is in front of the trailing edge and directly adjacent to the
trailing edge is equal to a single wall thickness of the second
planar semi-finished product. This second planar semi-finished
product can, for example, consist of a sheet of a metallic material
like the first planar semi-finished product. Thus also in this
alternative design a blade with a trailing edge at the end is
achieved with a very thin geometry whereby the hollow profiled
blade is aerodynamically optimized.
[0022] In an advantageous embodiment the second planar
semi-finished product extends inwards into the interior of the
hollow profiled blade. In this way the second planar semi-finished
product can be fastened particularly easily and securely to the
hollow profiled blade. In order to achieve this, in a further
advantageous embodiment the second planar semi-finished product is
connected tightly and flush with the first part of the first planar
semi-finished product of the hollow profiled blade and/or with the
second part of the first planar semi-finished product. It has
proved to be advantageous if this tight and flush connection is
achieved by welding, particularly by means of a fillet weld.
[0023] In the alternative embodiment it is also advantageous if a
stiffener profile is arranged in the interior of the hollow
profiled blade. It is particularly advantageous if the stiffener
profile is formed from the second of the planar semi-finished
products.
[0024] In an advantageous embodiment the stiffener profile is made
by bending the second planar semi-finished product.
[0025] A fan wheel according to the invention for a radial fan has
a top plate and a base plate and is characterized in that it has
several hollow profiled blades between the top plate and the base
plate. In this wheel the hollow profiled blades correspond to one
of the embodiments described above.
[0026] In an advantageous embodiment of the fan wheel according to
the invention the hollow profiled blades have lugs on one of their
upper and/or lower narrow side, while the top plate and/or the base
plate have slots into which the lugs can be inserted to hold the
hollow profiled blades into position between the top plate and the
base plate whereby a particularly simple assembly of the hollow
profiled blades in the fan wheel is achieved.
[0027] Further advantages, peculiarities and useful developments of
the invention arise from the sub-claims and the following
representation of preferred embodiments by reference to the
Figures.
[0028] The various Figures show:
[0029] FIG. 1 A hollow profiled blade according to the state of the
art in a three dimensional presentation
[0030] FIG. 2 A diagram of the flow pattern at the trailing edge of
a hollow profiled blade according to the state of the art
[0031] FIG. 3 A three dimensional presentation of a hollow profiled
blade according to the invention
[0032] FIG. 4 A three dimensional presentation of an alternative
embodiment of a hollow profiled blade according to the
invention
[0033] FIG. 5 A three dimensional presentation of a further
alternative embodiment of a hollow profiled blade according to the
invention
[0034] FIG. 6 A cross sectional view of the alternative embodiment
in FIG. 5
[0035] FIG. 7 A three dimensional presentation of further
embodiment of a hollow profiled blade according to the invention
with an internal stiffener profile.
[0036] FIG. 8 A cross sectional view of the embodiment of the
hollow profiled blade according to the invention with an internal
stiffener profile in FIG. 4.
[0037] FIG. 9 A detailed presentation of the trailing edge of a
hollow profiled blade according to the invention in a cross
sectional view
[0038] FIG. 10 A diagram of the flow pattern of a hollow profiled
blade according to the invention
[0039] FIG. 11 A detailed presentation of a flow pattern diagram at
the trailing edge of a hollow profiled blade according to the
invention
[0040] FIG. 12 A three dimensional presentation of a fan wheel
according to the invention
[0041] FIG. 1 shows a hollow profiled blade 100 according to the
state of the art in a three dimensional presentation. The hollow
profiled blade 100 is manufactured from a first sheet in the form
of a planar semi-finished product 105 and has a compression side
130, a suction side 140, a leading edge 110 and a trailing edge
120. A hollow interior 101 is formed between the compression side
130 and the suction side 140. The sheet 105 is bent in such a
manner that the leading edge 110 has a thickness which is greater
than twice the wall thickness of the sheet 105. In contrast, at the
trailing edge 120 the ends of the sheet lie on top of each other in
such a manner that the trailing edge 120 has a thickness which is
of the magnitude of twice the wall thickness of the sheet used
105.
[0042] FIG. 2 shows a diagram of the flow pattern at the trailing
edge 120 of a hollow profiled blade 100 according to the state of
the art. The hollow profiled blade 100 is made from sheet. The
sheet 105 forming the compression side 130 and the suction side 140
meet on top of one another at the trailing edge. A hollow area 101
is formed in the area in front of the trailing edge. In addition,
flow lines 150 of a medium flowing round the hollow profiled blade,
for example air, can also be seen. The medium flows round the
hollow profiled blade 100 in a manner which is very largely
parallel. In addition, turbulence 151, which is created by the
abrupt edge in the form of the sheets lying on top of each other
105 with a thickness of approximately twice that of the sheet
thickness can be seen at the trailing edge 120 of the hollow
profiled blade 100. This turbulence leads to a deterioration in the
efficiency of the hollow profiled blade 100. In addition,
undesirable acoustic effects can occur as a result of the
turbulence.
[0043] A tree dimensional representation of a hollow profiled blade
according to the invention 100 can be seen in FIG. 3. The hollow
profiled blade 100 is manufactured from a sheet as the first planar
semi-finished product 105 and has a compression side 130, a suction
side 140, a leading edge 110 and a trailing edge 120. A hollow
interior 101 is formed between the compression side 130 and the
suction side 140. The sheet 105 is bent in such a manner that the
leading edge 110 has a thickness which is greater than twice the
wall thickness of the sheet 105. The ends of the sheet lie on top
of each other in a region 126 which is arranged in front of the
trailing edge 120 and directly adjacent to the trailing edge 120.
The compression side 130 of the hollow profiled blade 100 has a
first part 105d of the first planar semi-finished product 105 and
the suction side 140 of the hollow profiled blade 100 has a second
part 105s of the first planar semi-finished product. In this, the
second part 105s of the first planar semi-finished product 105
extends over the first part 105d of the first planar semi-finished
product 105 in such a manner that the trailing edge 120 itself has
a thickness which is the thickness of a single sheet. In this, the
suction side 130 has an abrupt increase in thickness 141 at the
position at which the first part 105d of the first planar
semi-finished product meets the second part 105s of the first
planar semi-finished product.
[0044] FIG. 4 shows the three dimensional presentation of an
alternative embodiment of a hollow profiled blade according to the
invention. Unlike the embodiment shown in FIG. 3, the first part
105d of the first planar semi-finished product 105 extends over the
second part 105s of the first planar semi-finished product 105 in
the region 126. Also in this embodiment the trailing edge 120
itself has a thickness of one sheet. As part of this, the
compression side 140 has an abrupt increase in thickness 141 at the
position at which the second part 105s of the first planar
semi-finished product 105 meets the first part 105d of the first
planar semi-finished product 105.
[0045] FIG. 5 is the three dimensional presentation of a further
alternative embodiment of a hollow profiled blade according to the
invention 100. In this embodiment the compression side 130 has a
first part 105d of the first planar semi-finished product 104,
while the suction side 140 has a second part 105s of the first
planar semi-finished product 105. In the area 126 arranged in front
of the trailing edge 120 and directly adjacent to the trailing edge
120 there is a second planar semi-finished product 107 which
projects into the interior 101 of the hollow profiled blade 100 and
which also extends both over the first part 105d and the second
part 104s of the first planar semi-finished product 105 in the
direction of the trailing edge 120. The wall thickness of the
second planar semi-finished product 107 is less than twice the wall
thickness of the first planar semi-finished product 105. For
example, the wall thickness of the second planar semi-finished
product 107 has essentially the same wall thickness as the first
planar semi-finished product 105. In this arrangement a wall
thickness of the hollow profiled blade 100 is created in the area
126 also in this embodiment which is smaller than twice the wall
thickness of the first planar semi-finished product 105. Thus also
by this alternative design a hollow profiled blade 105 with a
trailing edge at the end 120 is achieved with a very thin geometry
whereby the hollow profiled blade 100 is aerodynamically
optimized.
[0046] FIG. 6 is a cross sectional view of the alternative
embodiment in FIG. 5. The second semi-finished product 107 is
introduced into the interior 101 of the hollow profiled blade 100
between the first part 105d and the second part 105s of the first
planar semi-finished product 105 and is welded both to the first
part 105d and the second part 105s of the first planar
semi-finished product 105.
[0047] FIG. 7 shows in a three dimensional presentation a further
embodiment of a hollow profiled blade according to the invention
100 with an internal stiffener profile 125. The first part 105d of
the first planar semi-finished product 105 is bent through
approximately 180.degree. at the place where it meets the second
part 105s of the first planar semi-finished product 105 in front of
the trailing edge 120 and directly adjacent to the trailing edge
120 in the area 126 and is introduced and supported back into the
interior 101 of the hollow profiled blade 100 at the internal side
of the second part 105s of the first planar semi-finished product.
This first part 105d of the first planar semi-finished product 105
is bent at its end and in this way forms a stiffener profile 125.
By returning the first part 105d of the first semi-finished product
105, the hollow profiled blade has a thickness which is three times
the thickness of the sheet in an area 123 from the point where the
sheet is bent 122 to the end of the sheet which is turned inwards
105. In this way the hollow profiled blade 100 is strengthened in
this area and is therefore better able to resist the deformation
forces which occur during operation. The stiffener profile 125
makes a further contribution to stabilizing the hollow profiled
blade 100.
[0048] FIG. 8 is a cross sectional view of the embodiment of the
hollow profiled blade according to the invention 100 shown in FIG.
4 and with an internal stiffener profile. In this presentation the
area 123 in which the first part 105d of the first planar
semi-finished product 105 is introduced back into the interior 101
and lies on top of the second part 105s of the first planar
semi-finished product can be seen more clearly. The stiffener
profile 125 can be made as shown in FIG. 7. However, other
geometries capable of resisting a bending or torsional moment are
also conceivable.
[0049] In FIG. 9 the trailing edge 120 of a hollow profiled blade
according to the invention 100 is shown in an enlarged form. The
first part 105d of the first planar semi-finished product 105 is
bent through approximately 180.degree. at the position of the bend
122 and introduced back into the interior 101 of the hollow
profiled blade 100 on top of the second part 105s of the first
planar semi-finished product 105 whereby the second part 105s of
the first planar semi-finished product 105 is extended over the
position of the bend 122 in the direction of the trailing edge 120.
The parts 105d and 105s of the first planar semi-finished product
105 are welded together tightly and flush with each other with a
fillet weld 121 at the position of the bend 122.
[0050] FIG. 10 shows a diagram of the flow pattern of a hollow
profiled blade according to the invention 100. When the blade
rotates in the x direction the parallel flow pattern shown is
formed.
[0051] In FIG. 11 the flow pattern which forms at the trailing edge
120 of a hollow profiled blade according to the invention 100 is
shown in an enlarged diagram. A small area of turbulence 152 forms
in the area of the fillet weld 121 which, from the point of view of
the flowing medium, almost equalizes the abrupt change in thickness
141 of the hollow profile blade 100 at this point and therefore
encourages a parallel, low-loss flow.
[0052] FIG. 12 is the three dimensional presentation of a fan wheel
according to the invention 200. The fan wheel 200 has a top plate
210 and a base plate 220. Hollow profiled blades 100 are arranged
between the base plate 220 and the top plate 210. The hollow
profiled blades 100 can be installed in the fan wheel 200 by means
of lugs 106 which fit into slots 211 in the top plate 210 and
further lugs which fit into slots in the base plate (not shown in
the Figure).
[0053] The embodiments shown here only represent examples of this
invention and therefore must not be understood as restrictive.
Alternative embodiments considered by a person skilled in the art
are included equally in the extent of protection of this
invention.
LIST OF REFERENCE NUMBERS
[0054] 100 Hollow profiled blade [0055] 101 Hollow area, interior
[0056] 105 Planar semi-finished product, sheet [0057] 105d First
part of the first planar semi-finished product arranged on the
compression side [0058] 105s Second part of the first planar
semi-finished product arranged on the suction side [0059] 106 Lug
[0060] 107 Second planar semi-finished product, sheet [0061] 110
Leading edge [0062] 120 Trailing edge [0063] 121 Fillet weld [0064]
122 Position of the bend/bend position [0065] 123 Area of the
returned planar semi-finished product [0066] 125 Stiffener profile
[0067] 127 Area, region [0068] 130 Compression side [0069] 140
Suction side [0070] 141 Abrupt change of thickness [0071] 150 Flow
line [0072] 151 Turbulence [0073] 152 Flow turbulence [0074] 200
Fan wheel [0075] 210 Top plate [0076] 211 Slot [0077] 220 Base
plate [0078] x Direction of rotation
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