U.S. patent application number 12/932532 was filed with the patent office on 2011-06-23 for radial fan.
This patent application is currently assigned to Gebr. Becker GmbH. Invention is credited to Frank Diedrichsen, Bernhard Radermacher, Achim Von Kathen.
Application Number | 20110150637 12/932532 |
Document ID | / |
Family ID | 36940452 |
Filed Date | 2011-06-23 |
United States Patent
Application |
20110150637 |
Kind Code |
A1 |
Radermacher; Bernhard ; et
al. |
June 23, 2011 |
Radial fan
Abstract
A radial fan, preferably a high-speed radial fan, includes a
blower wheel, a housing which receives a rotor and a stator of an
electrical drive of the blower wheel shaft, and a cooling system.
To develop one such radial fan in terms of the cooling system
required, paths for a first cooling medium and a second cooling
medium are provided in the housing, the second cooling medium being
cooled by the first cooling medium as provided for by the housing,
and the paths are separated from each other by intact material
walls of the housing.
Inventors: |
Radermacher; Bernhard;
(Moenchengladbach, DE) ; Diedrichsen; Frank;
(Wuppertal, DE) ; Von Kathen; Achim; (Wuppertal,
DE) |
Assignee: |
Gebr. Becker GmbH
Wuppertal
DE
|
Family ID: |
36940452 |
Appl. No.: |
12/932532 |
Filed: |
February 28, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11921714 |
Jan 9, 2008 |
7922466 |
|
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PCT/EP2006/062756 |
May 31, 2006 |
|
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12932532 |
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Current U.S.
Class: |
415/178 |
Current CPC
Class: |
F04D 29/584 20130101;
H02K 9/19 20130101; H02K 5/20 20130101; H02K 9/06 20130101; F05B
2220/40 20130101; F04D 29/4206 20130101; H02K 7/14 20130101 |
Class at
Publication: |
415/178 |
International
Class: |
F04D 29/58 20060101
F04D029/58 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 6, 2005 |
DE |
10 2005 025 857.3 |
Jun 6, 2005 |
DE |
10 2005 025 858.1 |
Jun 6, 2005 |
DE |
10 2005 025 865.4 |
Claims
1. Radial fan (1), preferably high-speed radial fan, having an
impeller (8) and a housing (2), the housing (2) accommodating a
rotor (6) and a stator (5) of an electric drive (4) for the
impeller shaft (7), a cooling means being provided, and paths (30,
37) being provided in the housing (2) for a first cooling medium
(K.sub.1) and a second cooling medium (K.sub.2), for cooling of the
second cooling medium (K.sub.2) by the first cooling medium
(K.sub.1) by means of the housing (2), wherein the second cooling
medium (K.sub.2) is based on an internal gas flow which is closed
off hermetically with respect to the exterior, in that the paths
(30, 37) are separated from one another by uninterrupted material
walls (40) of the housing (2) and, for this purpose, are formed by
the casting process and/or as bores, the separation between the
paths being achieved merely by way of intact housing material.
2. Radial fan according to claim 1, wherein the paths (30, 37) in
the housing (2) run at an angle in relation to one another.
3. Radial fan according to claim 1, wherein the paths (30, 37) run
perpendicularly to one another.
4. Radial fan according to claim 1, wherein the paths (30, 37) of
the first cooling medium (K.sub.1) are disposed in the outer wall
of the housing (2), in a cross-sectionally chamber-like housing
recess (38).
5. Radial fan according to claim 4, wherein two circumferentially
distributed paths (37) of the first cooling medium (K.sub.1) are
routed in a chamber-like housing recess (38).
6. Radial fan according to claim 4, wherein three or more
chamber-like housing recesses (38) are provided over the
circumference.
7. Radial fan according to claim 4, wherein the chamber-like
housing recesses (38) are bounded in the axial direction of the
housing (2) by integral walls (41) of the housing (2).
8. Radial fan according to claim 4, wherein the chamber-like
housing recesses (38) are closed by a covering (42) extending in
the axial direction of the housing (2).
9. Radial fan according to claim 8, wherein the covering (42) is in
the form of a tubular part (46) which encloses the housing (2).
10. Radial fan according to claim 4, wherein one chamber-like
housing recess (38) is formed as a cooling-medium infeed (44) and
one chamber-like housing recess (38) is formed as a cooling-medium
discharge (44).
11. Radial fan according to claim 1, wherein the housing (2) is
cylindrical, one end being associated with the impeller (8) and the
other end being closed via a foot part (9).
12. Radial fan according to claim 11, wherein the other end has a
stepped formation, and the foot part (9) is stepped
correspondingly.
13. Radial fan according to claim 4, wherein the paths (37) of the
first cooling medium (K.sub.1) run further toward the inside, as
seen in the radial direction, than the paths (30) of the second
cooling medium (K.sub.2) at least in the region between the
chamber-like housing recesses (38), the second cooling medium
(K.sub.2) also passing through the interior of the housing (2).
14. Radial fan according to claim 1, wherein the paths (37) of the
first cooling medium (K.sub.1), predominantly for the purpose of
dissipating the power loss of the stator (5), are brought close to
the stator (5).
15. Radial fan according to claim 1, wherein axial bores are
provided, which correspond to the paths (30) for the second cooling
medium (K.sub.2) and are used for accommodating electric lines.
16. Radial fan (1), preferably high-speed radial fan, having an
impeller (8) and a housing (2), the housing (2) accommodating a
rotor (6) and a stator (5) of an electric drive (4) for the
impeller shaft (7), a cooling means being provided and,
furthermore, cooling in particular of the drive (4) being achieved
by a partial gas stream (T) separated off from the gas which is to
be compressed, wherein the partial gas stream is channeled,
following separation, into paths (31) of a cooling-channel housing
(14), which, for its part, is actively cooled at least
indirectly.
17. Radial fan according to claim 16, wherein the housing paths
(31) are labyrinthine.
18. Radial fan according to claim 16, wherein the housing paths
(31) lead radially inward from the outside.
19. Radial fan according to claim 16, wherein the partial gas
stream (T) is branched off from the main gas stream (H) radially
outside the impeller (8), in the region of a diffuser (20).
20. Radial fan according to claim 19, wherein the partial gas
stream (T) then passes through the housing wall (35) of the housing
region which accommodates the electric drive (4).
21. Radial fan according to claim 16, wherein it is at that end of
the electric drive (4) which is directed away from the impeller (8)
that the partial gas stream. (T) is channeled out of the housing
(2) into the interspace between the stator (5) and rotor (6).
22. Radial fan according to claim 16, wherein the drive shaft (7)
is in the form of a hollow shaft, and wherein it is at that end of
the electric drive (4) which is directed away from the impeller (8)
that the partial gas stream (T) is channeled out of the housing (2)
into the drive shaft (7).
23. Radial fan according to claim 16, wherein the partial gas
stream (T) is channeled back into the main gas stream (H) at the
radially outer periphery of the impeller (8).
24. Radial fan according to claim 16, wherein the active cooling
means of the housing (2) is in the form of a water cooling
means.
25. Radial fan according to claim 16, wherein the gas consists of
helium and/or nitrogen and/or is air and/or is a mixture of two or
more of the gases mentioned.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of and Applicants claim
priority under 35 U.S.C..sctn..sctn.120 and 121 on U.S. application
Ser. No. 11/921,714 filed on Jan. 9, 2008, which application is a
national stage application under 35 U.S.C..sctn.371 of PCT
Application No. PCT/EP2006/062756 filed May 31, 2006, which claims
priority under 35 U.S.C..sctn.119 from German Patent Application
No. 10 2005 025 865.4 filed Jun. 6, 2005, German Patent Application
No. 10 2005 025 857.3 filed Jun. 6, 2005, and German Patent
Application No. 10 2005 025 858.1 filed Jun. 6, 2005, the
disclosures of each of which are hereby incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a radial fan, preferably high-speed
radial fan, having an impeller and a housing, the housing
accommodating a rotor and a stator of an electric drive for the
impeller shaft, and a cooling means being provided.
[0004] 2. The Prior Art
[0005] Radial fans of the type in question, in particular radial
fans which rotate at high speeds, are known and are used, for
example, in conjunction with lasers. Since considerable thermal
loads have to be dissipated here, a cooling means is provided.
SUMMARY OF THE INVENTION
[0006] In respect of the prior art described above, it is
considered to be an object of the invention to improve further a
radial fan of the type in question in respect of the cooling
required.
[0007] Since it is also the case with such radial fans that
considerable thermal loads have to be dissipated, it is also an
object of the invention to configure such a radial fan
advantageously in respect of the necessary cooling means.
[0008] Furthermore, it is also intended for the impeller, which is
driven by an electric drive accommodated in the housing, to be
configured advantageously in safety terms.
[0009] The first object is achieved first and foremost by the
invention in a first aspect which is based on the fact that paths
are provided in the housing for a first cooling medium and a second
cooling medium, for cooling of the second cooling medium by the
first cooling medium by means of the housing, and that these paths
are separated from one another by uninterrupted material walls of
the housing. This accordingly provides a sealing-free system which
allows two-fold cooling of the radial fan, in particular of the
housing and/or the rotor/stator region thereof, namely by a first
cooling medium and a second cooling medium, the second cooling
medium serving for secondary cooling, while the first cooling
medium provides primary cooling. The paths of the two cooling media
are separated hermetically from one another, this separation being
achieved by way of material walls of the housing itself. For this
purpose, the fan housing preferably consists of a casting material
such as, in particular, a lightweight material, for example
aluminum, which is formed with thick walls.
[0010] The subject matters of further developments are explained
hereinbelow.
[0011] Thus, in a preferred configuration, it is provided that the
paths in the housing run at an angle in relation to one another,
that is to say, when seen three-dimensionally, they are not
parallel to one another. Rather, the paths of the two cooling
media, in a projection, enclose for example an acute angle, which
results, in a projection, in the cooling-media paths crossing. A
preferred configuration is one in which the paths run
perpendicularly to one another, in which case, for example, paths
of the first cooling medium extend parallel to the impeller-shaft
axis, while the paths of the second cooling medium run
substantially in the circumferential direction in relation to the
impeller-shaft axis. The paths are formed in the housing in the
casting process and/or as bores. It is thus possible, during the
casting operation for producing the housing, to form these paths at
the same time. As an alternative, in particular in the case of a
solid housing component, the paths may be formed by bores. The
paths of the first cooling medium are preferably disposed in the
outer wall of the housing, in a cross-sectionally chamber-like
housing recess. This chamber-like housing recess is formed in the
housing preferably during the production process, therefore, in
particular, during production by casting. The chamber-like housing
recess is open in the radially outward direction in relation to the
housing and, furthermore, two circumferentially distributed paths
of the first cooling medium are routed in the chamber-like housing
recess. Correspondingly, two consecutive paths of the first cooling
medium open out, preferably in the circumferential direction, in a
housing recess. In a preferred configuration of the subject matter
of the invention, it is provided that three or more chamber-like
housing recesses are provided over the circumference, further
preferably four such housing recesses, which are distributed
uniformly in the circumferential direction. In the axial direction
of the housing, the chamber-like housing recesses are bounded by
integral walls of the housing. Also in the circumferential
direction, two adjacent chamber-like housing recesses are separated
from one another by a solid portion of the housing, which solid
portion has at least one path for the first cooling medium passing
through it in order to connect these adjacent chamber-like housing
recesses. The chamber-like housing recesses are closed by a
covering extending in the axial direction of the housing. As a
result, the chamber-like housing recesses, which are enclosed on
all sides, form part of the path for the first cooling medium.
Accordingly, taking account of housing recesses distributed over
the circumference and of paths which are provided in each case
between two adjacent housing recesses, and pass through the housing
portion, a circuit is provided in the circumferential direction of
the housing. The covering may be in the form of a tubular part
which encloses the housing. As an alternative, it is also possible
for plate-like individual coverings to be associated with each
chamber-like housing recess. The significant factor here is for
each individual housing recess to be closed in a sealing manner.
One chamber-like housing recess is preferably formed as a
cooling-medium infeed and a further chamber-like housing recess is
formed as a cooling-medium discharge. Accordingly, associated with
these housing recesses, or the coverings or covering portions which
close the same, there are preferably provided couplings or the like
for the connection of external pipe or hose portions. It is also
proposed that the housing be cylindrical, one end being associated
with the impeller and the other end being closed via a foot part,
for hermetically sealing the housing, which contains the paths for
the cooling media and accommodates the electric drive for the
impeller shaft. For sealing closure, it is further provided that
the other end has a stepped formation, and the foot part is stepped
correspondingly. In particular this stepped formation results in
sealing of the second cooling-medium path with respect to the
exterior. Furthermore, the foot part may form, at the same time, in
the direction of the housing interior, portions of paths for the
second cooling medium. In addition, the foot part may have
plug-like inlets for the power supply, on the one hand, and
possibly the sensor system and associated electronics, on the other
hand. Cooling-related advantages are achieved in that the paths of
the first cooling medium run further toward the inside, as seen in
the radial direction, than the paths of the second cooling medium
at least in the region between the chamber-like housing recesses,
the second cooling medium also passing through the interior of the
housing. The paths of the second cooling medium thus preferably run
parallel to the axial alignment of the impeller shaft in the region
of the solid housing portions which separate two circumferentially
adjacent, chamber-like housing recesses from one another. These
solid housing portions have both the paths of the first cooling
medium passing through them in one direction and the paths of the
second cooling medium passing through them preferably
perpendicularly thereto. As an alternative, it is also possible for
the paths of the first cooling medium to be provided further toward
the outside, as seen in the radial direction, than the paths of the
second cooling medium. Furthermore, in a preferred configuration,
it is provided that the paths of the first cooling medium run in
the circumferential direction in relation to the impeller-shaft
axis. A plurality of paths which are positioned axially one behind
the other, and are brought together in each case in the
chamber-like housing recesses, are provided here. This multiplicity
of paths for the first cooling medium is restricted, further
preferably, to the region of the electric drive in the housing. The
paths of the second cooling medium extend, further preferably, over
more or less the entire axial length of the housing from the
impeller to the foot part provided opposite. Thus, in a development
of the subject matter of the invention, it is provided that the
paths of the first cooling medium, predominantly for the purpose of
dissipating the power loss of the stator, are brought close to the
stator such that the thickness of the housing material remaining
between the paths and the stator which is to be cooled corresponds
to, or is less than, a cooling-medium-path diameter. It is also
proposed that axial bores which correspond to the paths for the
second cooling medium, and are used for accommodating electric
lines, be provided. It is thus extremely easy to provide for axial
lead-through of electric lines while, at the same time, ensuring
insulation in relation to the first cooling system.
[0012] The object in respect of the cooling system is achieved
first and foremost by the invention in another aspect which is
based on the fact that cooling in particular of the drive is
achieved by a partial gas stream separated off from the gas which
is to be compressed. This gives rise to a cooling system by means
of which, with hermetic closure with respect to the exterior,
considerable thermal loads can be dissipated. For this purpose, the
gas which is compressed in any case by the radial fan is used for
self-cooling of the fan drive, in particular of the housing region
which accommodates the rotor and stator, in which case the
branched-off partial gas stream, which serves for cooling purposes,
is channeled specifically through the housing and/or through the
rotor/stator region. In addition, this branched-off partial gas
stream, after passing through the cooling route, is fed back to the
main gas stream developed by the fan impeller. Hermetically sealed
cooling of the radial fan with respect to the exterior is achieved
as a result. In a preferred configuration, it is thus possible to
realize a sealing-free system.
[0013] The subject matter of a further development is explained
hereinbelow.
[0014] Thus, in a preferred development of the subject matter of
the invention, it is provided that cooling of the partial gas
stream takes place by way of contact with the housing wall, which,
for its part, is actively cooled. It is thus possible for the
partial gas stream to be channeled through channels which are
appropriately provided in the housing, and along the walls of which
heat exchange takes place.
[0015] The invention also relates to a radial fan, an improvement
in the cooling capacity being achieved in that a partial gas stream
separated off from the gas which is to be compressed is channeled,
following separation, into paths of a cooling-channel housing,
which, for its part, is actively cooled at least indirectly. This
results in (preliminary) cooling of the partial gas stream, in
first instance primarily by way of contact with the housing walls
which delimit the housing paths and also, secondarily, by way of
separate active cooling of the cooling-channel housing and thus of
the walls of the housing paths. The housing has good thermal
conductivity for this purpose and, further preferably, consists of
a metal material, in particular a light-metal material, for example
in the form of an aluminum casting. In order to improve the cooling
capacity further, an active cooling means for the housing is also
provided, this means absorbing, and dissipating, the heat which is
given up by the partial gas stream via the housing wall.
[0016] The subject matters of further developments are explained
hereinbelow.
[0017] The housing paths may be labyrinthine. This makes it
possible to achieve large-surface-area preliminary cooling of the
partial gas stream by way of contact with the housing wall in the
labyrinthine housing path, the housing paths, further preferably,
leading radially inward from the outside. It is also proposed that
the partial gas stream be branched off from the main gas stream
radially outside the impeller, in the region of a diffuser,
specifically preferably at the outlet from the diffuser. Use is
made here of the difference in pressure which prevails, during
operation of the radial fan, between the higher pressure at the
diffuser outlet and the lower pressure in the motor housing and/or
in the region where the partial gas stream re-enters the main gas
stream at the outer periphery of the impeller and/or at the
diffuser inlet, in order thus to achieve an automatically operating
partial gas cooling circuit within the fan housing. The partial gas
stream is accordingly forced through the fan housing and the
electric drive for cooling purposes. It is provided that the
partial gas stream is channeled radially inward in first instance
and then passes through the housing wall of the housing region
which accommodates the electric drive, thus preferably parallel to
the impeller axis, furthermore a plurality of such channels or the
like for the partial gas stream being provided in the housing
around the impeller axis, as seen in cross-section. It is at that
end of the electric drive which is directed away from the impeller
that the partial gas stream-is preferably channeled out of the
housing into the interspace between the stator and rotor,
accordingly passing over the surfaces of the rotor and stator for
heat dissipation. As an alternative, or also in combination
therewith, it may be provided that the drive shaft is in the form
of a hollow shaft, and that it is at that end of the electric drive
which is directed away from the impeller that the partial gas
stream is channeled out of the housing into the drive shaft, in
order to pass through the latter centrally in the direction in
which the drive shaft extends, heat dissipation taking place by way
of contact with the shaft wall. In the case of a combined solution
in which the partial gas stream is channeled both through the drive
shaft, in the form of a hollow shaft, and through the interspace
between the stator and rotor, these two partial gas streams are
preferably brought together downstream of the rotor and/or stator,
as seen in the flow direction, and furthermore the flow direction
of the partial gas stream as it passes through the interspace
between the stator and rotor and as it passes through the hollow
shaft being counter to the flow direction of the partial gas stream
which, coming from the labyrinthine housing path, passes through
the housing in the direction of the end which is directed away from
the impeller. Finally, the partial gas stream is channeled back
into the main gas stream at the radially outer periphery of the
impeller. A lower pressure prevails at this location than in the
radially outer position in the region of the diffuser outlet, at
which the partial gas stream is branched off from the main gas
stream, and a differential-pressure-controlled circuit is
accordingly established. In a preferred configuration of the
subject matter of the invention, it is provided that the active
cooling means of the housing is in the form of a water cooling
means. This water cooling means, which forms a secondary cooling
means, is separated hermetically from the gas cooling means, which
forms the primary cooling means, furthermore basically a
sealing-free system being present. Finally, it is provided that the
gas consists of helium and/or nitrogen and/or is air and/or is a
mixture of two or more of the gases mentioned.
[0018] The object, mentioned in the introduction, relating to the
safety aspect is achieved first and foremost by the invention in
another aspect which is based on the fact that, in order to form a
cage which encloses the impeller, cage plates are provided on the
cover side and underside of the impeller, and these cage plates are
held together around the periphery of the impeller by, for example,
stud-like connecting means, at least the connecting means and the
cover-side cage plate consisting of a hard and tough material such
as steel. This configuration provides a safeguard against bursting.
This prevents, in first instance in the event of the impeller
bursting, the cover-side housing part, which consists of a
light-metal casting material, from being lifted off and/or
destroyed. Such a situation where the cover is lifted off and/or
destroyed would result in enlargement of the air gap which, in the
case of a radial fan, opens outward, and relatively large fragments
of the ruptured impeller could escape at high speed through this
enlarged gap. This risk is countered by the provision of the
cover-side cage plate, which consists of a hard and tough material
such as steel, furthermore, for example, ST 50. This cover-side
cage plate forms a protective shield for the cover disposed at the
rear, that is to say on that side of the cage plate which is
directed away from the impeller. It is also the case that the cage
plates provided on the cover side and underside of the impeller are
secured against displacement--both in the radial and in the axial
directions--stud-like connecting means being provided for this
purpose. These connecting means keep the cage plates at a
predetermined, axial spacing. Since, according to the invention,
these connecting means also consist of a hard and tough material
such as steel, they are also protected against being destroyed by
fragments resulting from bursting.
[0019] The subject matters of further developments are explained
hereinbelow.
[0020] It is thus provided that, in order to form the cover, the
housing is divided parallel to a plane of revolution of the
impeller. Furthermore, it proves to be particularly advantageous if
both cage plates consist of a hard and tough material such as
steel, furthermore, for example, such as ST 50. As a result of this
configuration, the cage enclosing the impeller is formed entirely
from a hard and tough material. The radial air-outlet gap as seen
in thickness directions, that is to say as measured parallel to the
impeller axis, is selected such that, in the event of the impeller
bursting, in the worst-case scenario only small fragments can pass
radially outward. Larger, and thus also more dangerous, fragments
cannot pass through this annular gap since the cage provided does
not allow any widening of the gap. In addition to the cover
mentioned, it is also possible for the housing to be in the form of
a light-metal casting, and thus, furthermore, for example made of
aluminum. The cage plate which encloses the impeller on the
underside also protects such a light-metal housing against being
destroyed by fragments. In a preferred configuration, the
connecting means are screw-connected both in the housing and in the
cover and, accordingly, additionally form a connection between the
housing and cover which is resistant to fracture and impact. Force
transmission in the event of bursting takes place primarily via
steel nuts which are screwed onto the connecting means, support the
cage plates at the rear and counteract any enlargement of the gap
between the cage plates. As an alternative to a steel nut, it is
also possible for a steel collar to be formed on the connecting
means. A diffuser part is preferably disposed beneath the housing
cover, the cover-side cage plate being disposed between the housing
cover and the diffuser part. The connecting means here also pass
through the diffuser part for screw-connected engagement in the
housing cover. In a development of the subject matter of the
invention, it is provided that a first housing part is disposed
beneath the impeller and a cooling-channel cover is fitted on the
side of the first housing part which is directed away from the
impeller. The underside cage plate is preferably disposed between
the impeller and the first housing part. In addition, the first
housing part may have cooling channels which are closed by the
cooling-channel cover disposed on the underside. The housing, which
accommodates the electric drive for the impeller, is fastened on
the first housing part, which forms a cooling-channel housing. The
connecting means are secured, at one end, in the cooling-channel
housing and, at the other end, preferably in the housing cover,
with the interposition of the two cage plates and of the diffuser
and of the first housing part. For screw-connection, the connecting
means, in a preferred configuration, are in the form of studs which
have screw threads at the ends. In addition, it is proposed that
the cage plates be in the form of annular parts, further preferably
with a cage-plate internal diameter which is adapted to the
external diameter of the impeller, and therefore, furthermore, with
a slight oversize in relation to the external diameter of the
impeller. The radial extent of the annular part corresponds to a
radial dimension of the impeller or less, and therefore,
furthermore, approximately to a third, a quarter, half or also two
thirds or three quarters or also even further fractions of the
radial extent. The impeller has blades, having different heights in
the radial direction, the gap formed by the cage plates overlapping
only part of the height of the blades, to be precise that part
which corresponds at least to the height of the blades at their
greatest radial extent. Accordingly, the gap between the cage
plates is adapted to the axial extent of the impeller or of its
blade in the radially outer region.
[0021] Accordingly, the extent of the gap is only a fraction of the
axially measured overall height of the impeller, that is to say a
fraction of the maximum height of the blades. The gap thus
corresponds preferably approximately to half the maximum blade
height, but, in addition, may also correspond approximately to a
quarter, a third or also two thirds to three quarters of the
maximum blade height. In addition, it is provided that the lower
cage plate extends axially into a foot region of the blades, and,
further preferably, engages beneath the impeller in the radially
inward direction. Accordingly, the lower cage plate is provided
with a recessed portion which is adapted to the maximum external
radius of the impeller, and in which the impeller is positioned.
That portion of the lower cage plate which is provided for engaging
beneath the impeller has a radial extent which corresponds
approximately to the smallest height of the blades at their
greatest radial extent. In order for the cage to be resistant to
fracture and impact, it is further provided that, in the case of
the impeller having a diameter of 100 millimeters or more in the
foot region, at least one connecting stud is provided for each 25
millimeters of diameter. Accordingly, in the case of an impeller
having a diameter of 100 millimeters or more, at least four
connecting studs are provided, and these, in addition, are
distributed uniformly over the circumference. In this respect, it
is further preferred if, in the case of a diameter of 150
millimeters, six or more connecting studs, for example seven, eight
or ten connecting studs, are distributed at uniform angles over the
circumference, which connecting studs are all anchored preferably
by screw-connection, at one end, in the housing cover and, at the
other end, in the cooling-channel cover.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The invention is explained in more detail hereinbelow with
reference to the accompanying drawing, which merely illustrates
exemplary embodiments and in which:
[0023] FIG. 1 shows a perspective illustration of a radial fan
according to the invention;
[0024] FIG. 2 shows a perspective illustration corresponding to
FIG. 1, but following removal of a cover in order to expose a first
cage plate;
[0025] FIG. 3 shows an illustration corresponding to FIG. 2, but
following further removal of the cage plate in order to expose a
diffuser;
[0026] FIG. 4 shows a further illustration according to FIG. 1, but
following removal of the diffuser in order to expose a second cage
plate and an impeller;
[0027] FIG. 5 shows a further perspective illustration according to
the illustration in FIG. 2, but following removal of the second
cage plate in order to expose a housing part containing a
labyrinthine housing path;
[0028] FIG. 6 shows an exploded perspective view of the radial fan,
the electric drive which is required for driving the impeller
having been left out;
[0029] FIG. 7 shows the front view of the radial fan;
[0030] FIG. 8 shows the section through the radial fan along line
VIII-VIII in FIG. 7;
[0031] FIG. 8a shows the sectionally illustrated enlargement of the
region VIIIa in FIG. 8;
[0032] FIG. 9 shows the section along line IX-IX in FIG. 7;
[0033] FIG. 10 shows the cross-section along line X-X in FIG. 9,
here too with the electric drive having been left out;
[0034] FIG. 11 shows a sectional illustration corresponding to FIG.
9, but relating to an alternative embodiment of the radial fan, the
cage plates and the housing cover having been left out;
[0035] FIG. 12 shows the cross-section along line XII-XII in FIG.
11;
[0036] FIG. 13 shows a perspective illustration of the fan housing
of the second embodiment; and
[0037] FIG. 14 shows a further perspective illustration of the
housing with a covering which encloses the housing having been left
out.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0038] A first embodiment of a radial fan 1, which is in the form
of a high-speed radial fan, will be illustrated and described in
first instance with reference to the illustrations in FIGS. 1 to
6.
[0039] This radial fan 1 has a drive portion A and a fan portion B
associated therewith.
[0040] The drive portion A has a housing 2. The latter is in the
form of a light-metal casting and, in the end region which is
directed toward the fan portion B, is hollow-cylindrical with a
round cross-section. This cross-section continues substantially
over the entire longitudinal extent of the housing 2, but with
plane surfaces 3, which are positioned in the manner of secants in
relation to the circle cross-section, being formed. Four plane
surfaces 3 are provided in this respect, and these are disposed in
a square arrangement as seen in the cross-section according to the
illustration in FIG. 10. Correspondingly, the corner regions of the
square cross-section are rounded by the radius of the annular
housing portion.
[0041] In the housing 2, an electric drive 4 is accommodated,
having a stator 5 and a rotor 6. The latter forms a drive shaft 7
in the form of a shaft, specifically a hollow shaft.
[0042] The drive-shaft axis x coincides with the longitudinal axis
of the housing. Mounting of the drive shaft 7 is effected via
bearings (not illustrated specifically), for example magnetic
bearings.
[0043] The drive shaft 7 extends beyond the annular end portion of
the housing 2, as seen in plan view, for the rotationally fixed
connection of an impeller 8 of the fan portion B.
[0044] That end of the housing 2 which is directed away from the
impeller 8 is closed by a foot part 9. For this purpose, the
housing 2, which is generally in the form of a hollow body, has a
stepped formation 10, in which the correspondingly stepped foot
part 9 is positioned in a sealing manner.
[0045] The fan portion B is made up substantially of rotationally
symmetrical components disposed one behind the other along the
shaft axis x.
[0046] The fan portion B thus has, in first instance, a
cooling-channel cover 11. This cooling-channel cover 11 is
followed--as seen in the shaft-axis direction away from the housing
2--by a cooling-channel housing 14, which forms a first housing
part 13. This cooling-channel housing is screw-connected to the
cooling-channel cover 11 in order to cover that side of the
cooling-channel housing 14 which is directed toward the housing
2.
[0047] A further annular part which is designated by the numeral 15
forms a constituent part of the drive portion A and is
screw-connected to the housing 2.
[0048] It is also the case that the first housing part 13 or the
cooling-channel housing 14 is formed as an annular component in
plan view, having a free internal diameter which is reduced in
relation to the annular cooling-channel adapter part 15. The
internal diameter of the cooling-channel adapter part 15 is adapted
to the free internal diameter of the facing annular housing
portion.
[0049] In addition, the free internal diameter of the
cooling-channel housing 14 is selected to be somewhat smaller than
the maximum external diameter of the impeller 8, which is further
positioned on that side of the cooling-channel housing 14 which is
directed away from the cooling-channel cover 11, and is connected
there to the drive shaft 7 in a rotationally fixed manner.
[0050] Starting from a central region, the impeller 8 has radially
outwardly extending blades 16, which have different heights in the
radial direction, that is to say decrease in height in the radially
outward direction. The radially outwardly oriented peripheral edges
of the blades 16 are approximately concave in cross-section, for
example according to the illustration in FIG. 8, and a height h'
selected for the blades 16 in the region of the greatest radial
extent of the blades 16, that is to say in the foot region of the
impeller 8, this foot region being directed toward the
cooling-channel housing 14, corresponds approximately to a quarter
of the axially measured overall height h of the impeller 8.
[0051] That side of the cooling-channel housing 14 which is
directed toward the impeller 8 is provided with a central,
disk-like recessed portion 17. This has a larger diameter than the
foot region of the impeller 8.
[0052] In the recessed portion 17, a cage plate 18 is located,
which is annular in plan view. This cage plate consists of a hard
and tough material, for example ST 50 steel. The external diameter
of this cage plate 18 is adapted to the internal diameter of the
recessed portion 17 in the cooling-channel housing. The internal
diameter of the cage plate 18 is selected such that the impeller 8
has its greatest radial extent, that is to say the foot region,
positioned in a freely rotating manner, with a small gap being
left, in the annular space of the cage plate 18. Furthermore, the
cage plate 18 is formed such that it engages beneath the impeller 8
in a radially inward direction. Correspondingly, an annular collar
19, which is less thick than the overall thickness of the cage
plate 18, extends radially inward from the inner annular edge of
the cage plate 18.
[0053] A diffuser 20, which is likewise formed as a rotationally
symmetrical component, is secured on that side of the cage plate 18
which is directed away from the cooling-channel housing 14. This
diffuser has a central inlet cross-section into which the impeller
8 penetrates. In addition, a radially outwardly opening annular gap
21 which remains directly above the cage plate 18 has diffuser
blades 22 passing through it in a known manner, these diffuser
blades evening out the gas flow which passes out radially and, in
the process, increasing the gas pressure in the radially outward
direction.
[0054] It is also the case that the diffuser 20 has on the upper
side, which is directed away from the cage plate 18, an annular
recess 23, which is oriented concentrically in relation to the
shaft axis x. In this recess, a further cage plate 24 is located,
which in the exemplary embodiment illustrated has a thickness,
measured in the shaft-axis direction x, which corresponds
approximately to two thirds of the thickness of the cage plate 18,
which is provided on the underside of the diffuser 20. This cage
plate 24 also consists of a hard and tough material such as ST 50
steel.
[0055] Finally, disposed on the cage plate 24 is a housing cover 25
which also engages over the funnel-like intake portion of the
diffuser 20 and forms the axial gas inflow. This housing cover as
well as the diffuser 20 and/or the cooling-channel housing 14
and/or the cooling-channel adapter part 15 and the housing 2
preferably consist of a light-metal casting material, for example
aluminum.
[0056] The housing cover 25 and cooling-channel housing 14 are
braced in relation to one another with the interposition of the two
cage plates 24 and 18 and the diffuser 20. For this purpose, use is
made of, in the exemplary embodiment illustrated, seven connecting
means 26 which are distributed uniformly over the circumference and
are in the form of studs 27 which have screw threads at least at
the ends. These studs are screwed, at one end, to a limited extent
into corresponding threaded bores of the cooling-channel housing
14, and then form guiding and securing studs which are
correspondingly parallel to the shaft axis x. These studs 27, which
are used in the manner of stay bolts, have radial collars 27' which
are positioned in correspondingly shaped recesses in the
cooling-channel housing 14 such that they are substantially flush
with the associated surface of the cooling-channel housing 14.
During assembly, first of all the lower cage plate 18 is pushed on
in the axial direction over these studs 27--after which the
impeller 8 is initially secured on the drive shaft 7--and then the
diffuser 20 and the cage plate 24 are pushed on in the axial
direction over the studs 27. This is followed by the cage plate 24
being secured axially by means of steel nuts 27'' which are screwed
onto the studs 27 and are positioned in correspondingly formed
recessed portions of the housing cover 25, which is the last to be
placed in position. The stud ends passing through the housing cover
25 have nuts 28 screwed onto them in order for the above-mentioned
components to be clamped in and secured.
[0057] It is also the case that the stud-like connecting means 26
and the radial collars 27' thereof and also the nuts 27'' are
formed from a hard and tough material such as ST 50 steel, and
these accordingly form, together with the cage plates 18 and 24, a
cage 29 which serves for protecting the housing 2 and the
fan-portion components, for example the housing cover 25, in the
event of the impeller 8 bursting.
[0058] The gap s which is left between the two cage plates 18 and
24, and through which in particular the diffuser blades 22 pass,
covers only part of the height h of the impeller blades 16, that is
to say approximately the region of half the height h and thus at
least the height h' of the blades 16 at their greatest radial
extent, that is to say in the vicinity of the foot region of the
impeller 8.
[0059] The above-described configuration of the cage 29 formed from
hard and tough material ensures that, in the event of the impeller
8 bursting, large, and thus dangerous, fragments are not slung
radially outward by centrifugal force. It also counteracts any
fragment-induced damage to the housing cover 25 and/or the housing
2 or the cooling-channel housing 14, which is disposed on the
underside of the gap s. The cage plates 24 here serve as a
protective shield against destruction-induced enlargement of the
radial gap. The respectively rearward support of the cage plates 18
and 24 on the collars 27' and nuts 27'' reliably counteracts any
gap enlargement between the cage plates 18 and 24 (cf. FIG.
8a).
[0060] In particular for the purpose of cooling the electric drive
4, the radial fan 1 has a cooling system, which is substantially
divided in two. A primary cooling system is therefore provided, and
this uses an internal gas flow which is closed off hermetically in
the outward direction. A secondary cooling system is in the form of
a water cooling means which, passing through the housing 2, is
channeled outward, the water being delivered there by corresponding
pumping means or the like.
[0061] The second cooling medium, which is designated by K.sub.2 in
the drawings, is the above-mentioned internal gas flow of the
primary cooling system. In this case, the difference in pressure,
during operation of the radial fan 1, between the region of the
radially outer periphery of the impeller 8 and the radially outer
outlet region of the annular gap 21 of the diffuser is used in
order to create an automatic flow which has no active assistance. A
lower pressure P' thus prevails in the region of the radially outer
periphery of the impeller 8 than at the radially outer outlet
region of the annular gap 21. The pressure P, which is increased
there as a result of the diffuser blades 22, corresponds
approximately to twice the radially inner pressure P'.
[0062] The resulting difference in pressure is used in order to
branch off a partial gas stream T from the main gas stream H which
passes out radially, this partial gas stream then being fed via
appropriate paths 30 in order to cool the electric drive 4.
Re-entry of the partial gas stream into the main gas stream H is
effected in the region of the lower pressure P', that is to say in
the region of the radially outer periphery of the impeller 8, gas
circulation being achieved as a result.
[0063] The gas is preferably helium and/or nitrogen and/or air
and/or a mixture of two or more of the gases mentioned.
[0064] The above-described paths 30 for the second cooling medium
K.sub.2 run substantially parallel to the shaft axis x and,
furthermore, extend substantially between the cooling-channel
housing 14 and the foot part 9 of the housing 2.
[0065] On the upper side, which is directed toward the cage plate
18, the cooling-channel housing 14 is provided with a plurality of,
in the exemplary embodiment illustrated, with seven, labyrinthine
housing paths 31 which open out in the radially outward direction,
via a respective branch channel 32, in the radially outer region of
the annular gap 21, in which the increased pressure P prevails
during operation of the radial fan 1. The other end of each
labyrinthine housing path merges toward the inside of the
cooling-channel housing 14, as seen in the radial direction, into
an axial channel 33, which is connected to a correspondingly
positioned axial bore 34 in the annular part 15, this being
associated with the housing 2.
[0066] The labyrinthine paths 31 take a meandering course as seen
in a plan view of the cooling-channel housing 14, such a
labyrinthine path 31 being provided in each interspace between two
circumferentially adjacent stud-like connecting means 26.
[0067] The housing wall 35, which encloses the electric drive 4, is
of solid configuration, and accordingly also forms a cooling
body.
[0068] In extension of the axial bores 34 of the annular part 15,
coolant channels 36 extend in the housing wall 35. These channels
run parallel to the shaft axis x in the region of the
cross-sectionally rounded corner regions between two adjacent plane
surfaces 3. As can be seen, in particular, from the sectional
illustration in FIG. 10, each corner region of the housing wall 35
is assigned three such coolant channels 36, which are each
connected to a corresponding number of bores and channels in the
annular part 15 and/or in the cooling-channel housing 14.
[0069] As has been mentioned, primary cooling takes place by means
of the differential-pressure-controlled partial gas stream T
separated off from the main gas stream H. This partial gas stream
T, branching off from the radially outer position of the annular.
gap 21 in the region of the diffuser 20, is channeled radially
inward through the labyrinthine paths 31 of the cooling-channel
housing 14. The partial gas stream T then passes through the axial
channels 33 of the cooling-channel housing 14, the axial bores 34
of the annular part 15 and the coolant channels 36 in the region of
the housing walls 35 in order, finally, to be deflected through
approximately 180.degree., by means of paths which have not been
illustrated specifically, in that end of the housing 2 which is
directed away from the impeller 8, in the region of the foot part 9
provided there. Part of the partial gas stream T is then channeled
through the interspace between the rotor 6 and stator 5. A further
part of the gas stream also flows through the drive shaft 7, which
is formed as a hollow shaft, in order to pass out radially outward
into the interior of the housing 2 in the region beneath the
impeller 8. From this housing interior, the partial gas stream T
passes back, in the low-pressure region P' in the vicinity of the
radially outer periphery of the impeller 8, into the main gas
stream which is to be compressed.
[0070] First cooling of the partial gas stream T takes place by way
of contact with the housing wall 35. The cooling effect is
increased further by the active, secondary cooling system. This is
a water cooling means. This first cooling medium, which is
designated by K.sub.1, is channeled through paths 37 which, in the
exemplary embodiment illustrated, run perpendicularly to the paths
30 of the second cooling medium K.sub.2. These paths 37 thus run in
the circumferential direction in relation to the shaft axis x, in
doing so extending over an axial region which covers approximately
the stator region.
[0071] In order to form the paths 37, in first instance
chamber-like housing recesses 38, which initially open outward in
cross-section, are provided in the outer wall of the housing 2,
associated with the plane surfaces 3. These housing recesses are
accordingly positioned in each case between two circumferentially
adjacent, rounded corner regions of the housing wall 35, in which
corner regions--as has been mentioned--the paths 30 for the second
cooling medium K.sub.2 are placed, the paths 30 running
perpendicularly to these paths 37.
[0072] The, in the exemplary embodiment illustrated, four
chamber-like housing recesses 38, which are offset at an angle of
90.degree. in relation to one another, are flow-connected to one
another by bores 39 which are placed such that housing material
remains both in the direction of the stator 5, which is disposed
inside the housing, and in the direction of the gas-flow paths 37,
which run in the corner regions of the housing wall 35.
Accordingly, the paths 37 of the first cooling medium K.sub.1 and
the paths 30 of the second cooling medium K.sub.2 are separated
from one another by uninterrupted material walls 40.
[0073] As an alternative to the bores 39 proposed, the connections
between the housing recesses 38 may also be achieved in the casting
process.
[0074] The flow-connection between the housing recesses 38 results
in a path 37 for the first cooling medium K.sub.1 which runs all
the way around the circumference.
[0075] As seen in the axial direction, the chamber-like housing
recesses 38 are bounded by integral walls 41 of the housing 2. The
housing recesses 38 are delimited in the radially outward direction
by means of plate-like coverings 42 which are secured in a sealing
manner, in the region of the adjacent housing-corner formations,
along the recess periphery running round the outer wall of the
housing 2.
[0076] A covering 42 here is provided with a connection 43 in order
to form a cooling-medium infeed 44. The covering 42 which is
located diametrically opposite this covering likewise has a
connection 43, for forming a cooling-medium discharge 45.
[0077] As can also be seen, in particular, from the illustrations
in FIGS. 9 and 10, the bores 39, which connect the chamber-like
housing recesses 38, are configured as slot-like bores which extend
approximately over the entire axial length of the stator 5, which
is disposed in the housing interior.
[0078] The paths 37 of the first cooling medium K.sub.1 (water
circuit) are disposed further toward the inside, as seen in the
radial direction, than the paths 30 of the second cooling medium
K.sub.2 (gas circuit), at least in the region between the
chamber-like housing recesses 38, that is to say in the region of
the solid housing-corner regions which accommodate the paths
30.
[0079] The paths 30 and 37 of the two cooling media K.sub.1 and
K.sub.2 run at an angle in relation to one another, without any
sealing means being used for separating the paths 30 and 37 from
one another. This separation is achieved merely by way of intact
housing material.
[0080] FIGS. 11 to 13 show an alternative embodiment of the radial
fan 1, in particular of the housing 2. The cage, the diffuser and
the housing cover have been left out of the illustration for this
embodiment.
[0081] The functioning and the general course taken by the cooling
circuits correspond to those of the exemplary embodiment described
above.
[0082] The essential difference resides in the overall
configuration of the housing 2. In this second exemplary
embodiment, this housing is substantially cylindrical throughout
with a round cross-section. Four circumferentially uniformly
distributed, chamber-like housing recesses 38 are formed in the
solid housing wall 35 and intact housing-wall portions, which
accommodate axially running paths 30 for the second cooling medium
K.sub.2, remain between them--as seen over the circumference. These
paths 30 are associated with a radially outer region of these wall
portions. The bores 39, which connect the chamber-like housing
recesses 38, are provided in the radially inner region of these
wall portions. As can be seen, in particular, from the perspective
illustration in FIG. 14, each chamber-like housing recess 38 has a
plurality of bores 39 which are disposed one behind the other in
the direction of extent of the shaft axis x, which bores 39, in
accordance with the sectional illustration in FIG. 11, cover
substantially the region of extent of the stator as seen in the
same direction.
[0083] In this second embodiment, the covering 42, which closes the
chamber-like housing recesses 38, is formed as a tubular part 46
which encloses the housing 2 and can be secured on the outside of
the housing wall 35 by correspondingly positioned sealing
means.
[0084] The cooling-medium infeed 44, on the one hand, and the
cooling-medium discharge 45, on the other hand, are formed at two
diametrically opposite regions, each associated with a chamber-like
housing recess 38.
[0085] All features disclosed are (in themselves) pertinent to the
invention. The disclosure content of the associated/attached
priority documents (copy of the prior application) is hereby also
included in full in the disclosure of the application, also for the
purpose of incorporating features of these documents in claims of
the present application.
* * * * *