U.S. patent application number 16/720714 was filed with the patent office on 2020-06-25 for pump assembly.
The applicant listed for this patent is GRUNDFOS HOLDING A/S. Invention is credited to Jens Andersen GAD.
Application Number | 20200200189 16/720714 |
Document ID | / |
Family ID | 64755173 |
Filed Date | 2020-06-25 |
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United States Patent
Application |
20200200189 |
Kind Code |
A1 |
GAD; Jens Andersen |
June 25, 2020 |
PUMP ASSEMBLY
Abstract
A pump assembly (1) includes a rotor shaft, a pump base (3), a
pump housing (5), a motor housing (9) enclosing a motor for driving
the rotor shaft, and a motor stool (7) that includes a motor
coupling portion (13) and a pump coupling portion (15). The pump
housing encloses one or more impeller stages (10) arranged between
the motor stool and the pump base. The motor stool is clamped to
the pump base by at least two tie rods (17). The motor stool
includes at least two fixation protrusions (39) each having a
protrusion end (41) in the motor coupling portion. Each of the tie
rods is fixed to the motor stool by way of a fastener (37) at least
partially extending through one of the fixation protrusions. Each
fastener is only accessible when the motor housing is decoupled
from the motor coupling portion of the motor stool.
Inventors: |
GAD; Jens Andersen;
(Bjerringbro, DK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GRUNDFOS HOLDING A/S |
Bjerringbro |
|
DK |
|
|
Family ID: |
64755173 |
Appl. No.: |
16/720714 |
Filed: |
December 19, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 29/628 20130101;
F04D 13/06 20130101; F05D 2230/54 20130101; F04D 13/021 20130101;
F04D 1/066 20130101; F04D 1/063 20130101; F04D 29/426 20130101 |
International
Class: |
F04D 29/62 20060101
F04D029/62; F04D 29/42 20060101 F04D029/42 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2018 |
EP |
18214652.2 |
Claims
1. A pump assembly comprising: a rotor shaft extending along a
rotor axis; a pump base; a pump housing; a motor for driving the
rotor shaft; a motor housing enclosing the motor; a motor stool
comprising a motor coupling portion and a pump coupling portion,
wherein the pump housing encloses one or more impeller stages
arranged between the motor stool and the pump base and the motor
stool comprises at least two fixation protrusions, each having a
protrusion end in the motor coupling portion; and at least two
fasteners; at least two tie rods, wherein the motor stool is
clamped to the pump base by the at least two tie rods and each of
the tie rods is fixed to the motor stool by way of one of the
fasteners at least partially extending through one of the fixation
protrusions, wherein each of the fasteners is only accessible when
the motor housing is decoupled from the motor coupling portion of
the motor stool.
2. The pump assembly according to claim 1, wherein each of the tie
rods comprises a motor stool connection part at a motor stool end
portion of each tie rods and a pump base connection part at a pump
base end portion of each tie rod.
3. The pump assembly according to claim 2, wherein each of the tie
rods comprises a longitudinal panel, wherein: the longitudinal
panel has a radially outer face and a radially inner face; the
motor stool connection part or the pump base connection part or
both the motor stool connection part or the pump base connection
part extend inwardly from the radially inner face of the panel
towards the rotor axis.
4. The pump assembly according to claim 1, wherein: the motor stool
is clamped to the pump base by exactly two of the tie rods; and the
fixation protrusions of the motor stool are located at
diametrically opposite radial sides of the motor stool.
5. The pump assembly according to claim 1, wherein: each of the tie
rods extend essentially parallel to the rotor axis; or the fixation
protrusions extend essentially parallel to the rotor axis; or both
the tie rods and the fixation protrusions extend essentially
parallel to the rotor axis.
6. The pump assembly according to claim 1, wherein: the motor stool
comprises at least two radially outwardly open motor stool
recesses; the protrusion end, facing towards the motor housing, is
a first protrusion end; each fixation protrusion comprises a second
protrusion end facing towards the pump base and ending in one of
the motor stool recesses; and each of the motor stool recesses
accommodates a motor stool connection part of one of the tie
rods.
7. The pump assembly according to claim 1, wherein: the pump base
comprises at least two radially outwardly open pump base recesses;
each of the pump base recesses accommodates a pump base connection
part of one of the tie rods.
8. The pump assembly according to claim 7, wherein each of the pump
base recesses comprises an anchor face for a positive form locking
with a hook face of the pump base connection part of a tie rod.
9. The pump assembly according to claim 8, wherein: the anchor face
of each pump base recess has an angular orientation with an angle
in the range of 0.degree. to 60.degree. with respect to a plane
perpendicular to the rotor axis; a surface normal of the anchor
face has a vector component pointing radially inward towards the
rotor axis.
10. The pump assembly according to claim 7, wherein: at least one
of the pump base recesses comprises a securing face for abutting
against a radial outer face of a panel of each tie rod; a surface
normal of the securing face has a vector component facing radially
inward toward the rotor axis.
11. The pump assembly according to claim 1, wherein a longitudinal
panel of each tie rod lies at least partially against a radially
outer face of the pump housing.
12. The pump assembly according to claim 1, wherein the
circumferential extension of all of the tie rods in cumulation
spans over a fraction in the range of 1/18 to 1/4 of a
circumference of the pump housing.
13. The pump assembly according to claim 1, wherein: at least one
of the fasteners comprises an engagement means for engaging a tool;
and the engagement means is laterally enclosed by the motor
stool.
14. The pump assembly according to claim 13, wherein the protrusion
end in the motor coupling portion is laterally enclosed by the
motor stool and forms a laterally shielded inner seat for
engagement means of the fastener within the motor coupling portion
of the motor stool.
15. The pump assembly according to claim 1, wherein: at least one
of the fasteners comprises a bolt; and a motor stool connection
part of each tie rod comprises a thread for receiving the bolt.
16. The pump assembly according to claim 1, wherein: each of the
fasteners comprises a nut with an inner thread; a motor stool
connection part of each tie rod comprises a bolt portion with an
outer thread, the bolt portion extending through the fixation
protrusion for receiving the inner thread of the nut located at the
protrusion end facing towards the motor housing.
17. The pump assembly according to claim 1, wherein: a motor stool
connection part of each tie rod is movable parallel to the rotor
axis within a range inside a motor stool recess; an upper stop is
defined by a positive form locking between a hook face of a pump
base connection part of the tie rod and an anchor face of a
radially outwardly open pump base recess in the pump base.
18. The pump assembly according to claim 1, wherein the pump
assembly is a multi-stage centrifugal pump assembly.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority under 35
U.S.C. .sctn. 119 of European Application 18 21 4652.2, filed Dec.
20, 2018, the entire contents of which are incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present disclosure is directed to a pump assembly, in
particular to a multi-stage centrifugal pump assembly.
TECHNICAL BACKGROUND
[0003] The shape and size of a pump assembly is designed to meet
certain technical requirements and specifications. In particular,
multi-stage centrifugal pumps like the pumps of the Grundfos CR
series come in a wide range of sizes to cover a power range of 0.1
to 100 kW. The more pumping power is needed, the larger the pump is
typically designed.
[0004] Typically, such pumps comprise a rotor axis that may extend
vertically or horizontally. An electric motor drives a rotor shaft
extending along a rotor axis into a pump housing enclosing at least
one impeller stage. A pump base typically provides a stand and/or a
mounting bracket to fix the pump on a floor or a wall. Inlet and
outlet flanges for mounting the pump to a piping system may be part
of the pump base and/or the pump housing. The pump housing is
arranged between the motor and the pump base. The more pumping
power or head is needed, the more impeller stages may be stacked
along the rotor axis within the pump housing. Therefore, the axial
length of the pump housing typically scales with the number of
impeller stages. Depending on the maximum flow the pump is supposed
to be able to deliver, the radial extension of the impellers and
the pump housing may be larger or smaller.
[0005] As one type of electric motor can be used for a certain
range of pumps, different pumps within a certain performance range
can be driven with the same type of motor. Vice versa, the same
pump may be driven by a range of motors that come in different
sizes. In order to adapt differently shaped pump housings to the
same motor or the same pump housing to different sizes of motors, a
motor stool typically serves as a mounting adapter between the
motor and the pump. Thereby, standard electric motors can be used,
which need not to be specifically designed to drive pumps and may
be used in other fields.
[0006] It is known from EP 3 181 908 A1 to use four straps
circumferentially distributed around the pump housing and extending
axially alongside the pump housing for clamping the motor stool to
the pump base.
[0007] In view of such known pumps, it is an object of the present
disclosure to provide a pump assembly, which can be assembled more
easily and is safer against unwanted disassembling.
SUMMARY
[0008] In contrast to such known pumps, embodiments of the present
disclosure provide a pump assembly, which can be mounted more
easily and is safer against unwanted demounting.
[0009] In accordance with a first aspect of the present disclosure,
a pump assembly is provided comprising [0010] a rotor shaft
extending along a rotor axis, [0011] a pump base, [0012] a pump
housing, [0013] a motor housing enclosing a motor for driving the
rotor shaft, and [0014] a motor stool comprising a motor coupling
portion and a pump coupling portion, [0015] wherein the motor
coupling portion is located closer to the motor housing than the
pump coupling portion and the pump coupling portion is located
closer to the pump housing than the motor coupling portion, [0016]
wherein the pump housing encloses one or more impeller stages
arranged between the motor stool and the pump base, [0017] wherein
the motor stool is clamped to the pump base by at least two tie
rods, [0018] wherein the motor stool comprises at least two
fixation protrusions each having a protrusion end in the motor
coupling portion, wherein each of the tie rods is fixed to the
motor stool by way of a fastener at least partially extending
through one of the fixation protrusions, wherein each fastener is
only accessible when the motor housing is decoupled from the motor
coupling portion of the motor stool.
[0019] Thus, the tie rods cannot be unmounted as long as the motor
housing is coupled to the motor stool. This prevents unwanted
demounting of the tie rods as long as the motor is still coupled to
the rotor shaft. Furthermore, the assembling process is easier
compared to previously known pumps. As the fixation protrusions are
placed within the motor stool with a certain distance to the radial
periphery of the motor stool, the motor stool can be easily placed
at the pump housing before the tie rods are fixed to the motor
stool by way of the fasteners extending at least partially through
the fixation protrusions. The fixation protrusions may be axial
inner bores in the motor stool, i.e. they may be closed towards the
radial periphery of the motor stool. Alternatively, one or more of
the fixation protrusions may be recesses in the motor stool that
extend radially inwardly, i.e. they may be open towards the radial
periphery of the motor stool. However, irrespective of whether the
fixation protrusions are open or closed towards the radial
periphery of the motor stool, the fastener may comprise engagement
means, e.g. a bolt head or a nut, for engaging a tool like a
spanner or a hex, wherein the engagement means are laterally
enclosed by the motor stool and only accessible axially from the
side where the motor housing is to be coupled to the motor stool,
i.e. when the motor housing is actually decoupled from the motor
coupling portion of the motor stool. Preferably, a motor stool end
portion of the tie rods is pulled by the fastener towards the motor
coupling portion of the motor stool and away from the pump coupling
portion of the motor stool. Thereby, the pump coupling portion of
the motor stool is pushed towards the pump housing by a tension
force conveyed by the tie rods. Accordingly, a pump base end
portion of the tie rods pulls the pump base towards the pump
housing, so that the pump housing is securely sandwiched between
the motor stool and the pump base due to the clamping tension force
conveyed by the tie rods.
[0020] Optionally, each of the tie rods may comprise a motor stool
connection part at a motor stool end portion of the tie rod and a
pump base connection part at a pump base end portion of the tie
rod. Preferably, each of the tie rods may comprise a longitudinal
panel, wherein said panel has a radially outer face and a radially
inner face, wherein the motor stool connection part and/or the pump
base connection part extend inwardly from the radially inner face
of the panel towards the rotor axis. The panel may thus outwardly
shield the motor stool connection part and/or the pump base
connection part, so that they are not visible and/or accessible
when the pump is fully assembled. At least a part of the radially
outer face of the panel may be flush with the outer periphery of at
least a part of the motor stool and/or the pump housing. Such part
of the motor stool and/or the pump housing may comprise a
longitudinal groove to accommodate at least a part of the panel
essentially filling the longitudinal groove. This is particularly
useful for pumps to be used in clean or sterile environments like
the food industry, because flush and smooth surfaces are easier to
keep clean and sterile.
[0021] Optionally, the motor stool may be clamped to the pump base
by exactly two tie rods extending alongside the pump housing,
wherein the fixation protrusions of the motor stool are located at
diametrically opposite radial sides of the motor stool. The
fixation of the tie rods to the motor stool by way of a fastener at
least partially extending through one of the fixation protrusions
allows for more tensile stress per tie rod compared to known
four-strap fixation systems. Therefore, only two tie rods may be
sufficient to securely hold the motor stool, the pump housing and
the pump base together. This saves time for assembling the
pump.
[0022] Optionally, each of the tie rods and/or the fixation
protrusions may extend essentially parallel to the rotor axis. This
is beneficial, because the main component of the tension force is
essentially parallel to the rotor axis. However, the motor coupling
portion of the motor stool may have a larger radial extension than
the pump coupling portion of the motor stool, so that the motor
stool may effectively widen towards the motor. It is thus possible
that the tie rods and/or the fixation protrusions may not extend
exactly parallel to the rotor axis.
[0023] Optionally, the motor stool may comprise at least two
radially outwardly open motor stool recesses, wherein the
protrusion end facing towards the motor housing is a first
protrusion end, wherein each fixation protrusion comprises a second
protrusion end facing towards the pump base and ending in one of
the motor stool recesses, wherein each of the motor stool recesses
accommodates a motor stool connection part of one of the tie rods.
The motor stool recess may radially outwardly merge into a
longitudinal groove at the motor stool for accommodating the motor
stool end of the panel of the tie rod.
[0024] Optionally, the pump base may comprise at least two radially
outwardly open pump base recesses, wherein each of the pump base
recesses accommodate a pump base connection part of one of the tie
rods. It is advantageous that the pump base connection part, in
contrast to the motor stool connection part, is not actively fixed
to the pump base by way of a fastener, but passively hooked into
the pump base recess of the pump base for a secure positive form
locking. Thus, each pump base recess may comprise an anchor face
for positive form locking with a hook face of a pump base
connection part of the tie rods. Preferably, the anchor face of the
pump base recess may have an angular orientation with an angle
.beta. in the range of 0.degree. to 60.degree., most preferably
0.degree. to 15.degree., with respect to a plane perpendicular to
the rotor axis, wherein the surface normal of the anchor face has a
vector component pointing radially inward towards the rotor axis
and/or downwards. Likewise, the hook face of the pump base
connection part may have a corresponding angular orientation with
the angle .beta. in the range of 0.degree. to 60.degree., most
preferably 0.degree. to 15.degree., with respect to a plane
perpendicular to the rotor axis, wherein the surface normal of the
hook face has a vector component pointing radially outward away
from the rotor axis and/or upward. The contact between the anchor
face and the hook face provides for a secure positive form locking
of the pump base end portion of each tie rod.
[0025] Optionally, in order to make sure that the pump base
connection part cannot slip off the pump base recess, at least one
of the pump base recesses may comprise a securing face for abutting
against the radial outer face of the panel of the tie rod, wherein
the surface normal of the securing face has a vector component
facing radially inward toward the rotor axis. Preferably, the
securing face is located axially further away from the pump housing
than the anchor face, wherein the pump base laterally widens in the
direction away from the pump housing. Preferably, the securing face
is located radially more outward than the outer periphery of the
pump housing. Thereby, the panel of the tie rods can be designed
straight in longitudinal direction.
[0026] In some cases, it may be advantageous for the anchor face
and the hook face to have an angular orientation with a zero or
negative angle .beta. in the range of 0.degree. to -30.degree.,
with respect to a plane perpendicular to the rotor axis, with the
surface normal of the anchor face having a vector component
pointing radially outward and the surface normal of the hook face
having a vector component pointing radially inward. In such a case,
the securing face may prevent the pump base connection part from
slipping off the pump base recess.
[0027] Optionally, a panel of each tie rod may lie at least
partially against a radially outer face of the pump housing.
Thereby, a thermal contact may provide for an enhanced heat
dissipation of the pump housing via the panels of the tie rods.
Optionally, in order to enhance the thermal transfer between the
pump housing and the panel, the tie rod may comprise a thermally
conducting pad at the radially inner face of the panel. The pad may
thus be placed between the panel and the pump housing transferring
heat from the pump housing to the panel which has a relatively
large radially outer face to radiate heat off and to be cooled by
ambient air.
[0028] Optionally, the circumferential extension of the panels of
all tie rods in cumulation may cover a fraction in the range of
1/18 to 1/4 or more, preferably about 1/5 or about 1/6, of the
circumference of the pump housing. Thereby, the tensile stress on
the tie rods can be efficiently distributed over the width of the
panels in circumferential direction. The circumferential extension
of the panels may be constant or vary over their length. In case it
varies over the length, the maximum of the circumferential
extension of the panels of all tie rods in cumulation may cover a
fraction in the range of 1/18 to 1/4 or more, preferably about 1/5
or about 1/6, of the circumference of the pump housing.
[0029] Optionally, at least one of the fasteners may comprise an
engagement means, e.g. a bolt head or a nut, for engaging a tool,
e.g. a spanner or a hex, wherein the engagement means is laterally
enclosed by the motor stool.
[0030] Optionally, the protrusion end in the motor coupling portion
may be laterally enclosed by the motor stool and may form a
laterally shielded inner seat for engagement means of the fastener
within the motor coupling portion of the motor stool.
[0031] Optionally, at least one face of a panel of each tie rod may
be arc-shaped in a cross-sectional plane perpendicular to the rotor
axis, wherein the curvature of the arc-shaped face corresponds to a
curvature of a radial outer face of the pump housing. This is not
only beneficial to achieve a flush transition between the panel and
the motor stool for an appealing aesthetic design and easier
cleaning, but also increases the stiffness of the tie rods without
adding weight and material to it.
[0032] Optionally, a panel of each tie rod may be stiff against
bending perpendicular to the rotor axis, so that the motor stool
end of the tie rod deflects by less than 5% of the tie rod length
when a nominal test weight of 1 kg is applied vertically downward
to the motor stool end of the tie rod while the tie rod is fixed
horizontally at the base end of the tie rod. This is beneficial for
coping with the tensile stress, in particular when only two tie
rods are used to clamp the motor stool to the pump base.
[0033] Optionally, each of the fasteners may comprise a bolt,
wherein a motor stool connection part of each tie rod comprises a
thread for receiving the bolt. The bolt may comprise an outer
thread to be inserted through the fixation protrusions of the motor
stool and to be screwed into an inner thread of the motor stool
connection part of the tie rod placed in the motor stool recess.
Alternatively, the bolt may extend from the motor stool connection
part placed in the motor stool recess through the fixation
protrusions of the motor stool towards the motor housing to be
fixed by a nut at the motor coupling portion of the motor
stool.
[0034] Optionally, each of the protrusion ends facing the motor
housing may comprise a counterbore, wherein each of the bolt heads
is formed as a socket head and at least partially sunk into one of
the counterbores. It is advantageous if the bolt heads to not
axially protrude out of the motor coupling portion of the motor
stool, because a variety of motor housings may thereby be mounted
on the motor stool.
[0035] Optionally, each of the fasteners may comprise a nut with an
inner thread portion, wherein a motor stool connection part of each
tie rod comprises a bolt portion with an outer thread, the bolt
portion extending through the fixation protrusion for receiving the
inner thread portion of the nut located at the protrusion end
facing towards the motor housing. Optionally, each of the fixation
protrusions may comprise a counterbore, wherein each nut is at
least partially sunk into one of the counterbores.
[0036] Optionally, a motor stool connection part of each tie rod is
movable parallel to the rotor axis within a range inside a motor
stool recesses, wherein an upper limit of the range is defined by a
positive form locking between a hook face of a pump base connection
part of the tie rod and an anchor face of a radially outwardly open
pump base recess in the pump base.
[0037] Optionally, the pump base recess may be downwardly open so
that a lower limit of the range is defined by the ground on which
the pump assembly is standing.
[0038] Optionally, the pump assembly is a multi-stage centrifugal
pump assembly.
[0039] The various features of novelty which characterize the
invention are pointed out with particularity in the claims annexed
to and forming a part of this disclosure. For a better
understanding of the invention, its operating advantages and
specific objects attained by its uses, reference is made to the
accompanying drawings and descriptive matter in which preferred
embodiments of the invention are illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] In the drawings:
[0041] FIG. 1a is a perspective view of one of three examples of
pump assemblies according to the present disclosure;
[0042] FIG. 1b is a perspective view of another of three examples
of pump assemblies according to the present disclosure;
[0043] FIG. 1c is a perspective view of another of three examples
of pump assemblies according to the present disclosure;
[0044] FIG. 2 is a perspective view of the example as a first
embodiment shown in FIG. 1b without a motor housing and one of the
tie rods being installed;
[0045] FIG. 3 is a longitudinal sectional cut view through a
yz-plane of the example shown in FIG. 2;
[0046] FIG. 4a is a perspective view of a second embodiment of a
pump assembly according to the present disclosure in one of
different phases of one of the tie rods being installed;
[0047] FIG. 4b is a perspective view of a second embodiment of a
pump assembly according to the present disclosure in another of
different phases of one of the tie rods being installed;
[0048] FIG. 4c is a top view of the example as shown in FIG.
4a;
[0049] FIG. 5 is a partial sectional view of the examples as shown
in FIGS. 1b and 4b;
[0050] FIG. 6a is a simplified longitudinal sectional view through
the yz-plane as shown in FIG. 2 in one of five phases of assembling
the first embodiment of a pump assembly according to the present
disclosure;
[0051] FIG. 6b is a simplified longitudinal sectional view through
the yz-plane as shown in FIG. 2 in another of the five phases of
assembling the first embodiment of a pump assembly according to the
present disclosure;
[0052] FIG. 6c is a simplified longitudinal sectional view through
the yz-plane as shown in FIG. 2 in another of the five phases of
assembling the first embodiment of a pump assembly according to the
present disclosure;
[0053] FIG. 6d is a simplified longitudinal sectional view through
the yz-plane as shown in FIG. 2 in another of the five phases of
assembling the first embodiment of a pump assembly according to the
present disclosure;
[0054] FIG. 6e is a simplified longitudinal sectional view through
the yz-plane as shown in FIG. 2 in another of the five phases of
assembling the first embodiment of a pump assembly according to the
present disclosure;
[0055] FIG. 7a is a simplified longitudinal sectional view through
the yz-plane as shown in FIGS. 4a,b in one of five phases of
assembling the second embodiment of a pump assembly according to
the present disclosure;
[0056] FIG. 7b is a simplified longitudinal sectional view through
the yz-plane as shown in FIGS. 4a,b in another of the five phases
of assembling the second embodiment of a pump assembly according to
the present disclosure;
[0057] FIG. 7c is a simplified longitudinal sectional view through
the yz-plane as shown in FIGS. 4a,b in another of the five phases
of assembling the second embodiment of a pump assembly according to
the present disclosure;
[0058] FIG. 7d is a simplified longitudinal sectional view through
the yz-plane as shown in FIGS. 4a,b in another of the five phases
of assembling the second embodiment of a pump assembly according to
the present disclosure;
[0059] FIG. 7e is a simplified longitudinal sectional view through
the yz-plane as shown in FIGS. 4a,b in another of the five phases
of assembling the second embodiment of a pump assembly according to
the present disclosure;
[0060] FIG. 8a is a simplified longitudinal sectional view through
the yz-plane in one of five phases of assembling a third embodiment
of a pump assembly according to the present disclosure;
[0061] FIG. 8b is a simplified longitudinal sectional view through
the yz-plane in another of the five phases of assembling a third
embodiment of a pump assembly according to the present
disclosure;
[0062] FIG. 8c is a simplified longitudinal sectional view through
the yz-plane in another of the five phases of assembling a third
embodiment of a pump assembly according to the present
disclosure;
[0063] FIG. 8d is a simplified longitudinal sectional view through
the yz-plane in another of the five phases of assembling a third
embodiment of a pump assembly according to the present disclosure;
and
[0064] FIG. 8e is a simplified longitudinal sectional view through
the yz-plane in another of the five phases of assembling a third
embodiment of a pump assembly according to the present
disclosure.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0065] Referring to the drawings, FIG. 1a-c show pump assemblies 1
in form a multi-stage centrifugal pump assemblies. The shown pump
assemblies 1 all have a rotor axis R extending along a vertical
direction z. The horizontal plane perpendicular to the vertical
direction z is spanned by the vectors x and y, so that xyz define a
right-handed Cartesian coordinate system. It should be noted that
the right-handed Cartesian coordinate system may have any
orientation, e.g. in a horizontal pump setup the rotor axis R may
alternatively extend along a horizontal axis in the xy-plane. The
terms "upper" or "lower" herein refer to the position in a vertical
pump setup and shall be construed as relative positions along the
rotor axis R in a horizontal or other pump setup.
[0066] Each of the pump assemblies 1 comprises a pump base 3 (in
the shown vertical pump setup at the bottom of the pump assembly
1), a pump housing 5, a motor stool 7 and a motor housing 9 (in the
shown vertical pump setup at the top of the pump assembly 1)
enclosing a motor. The motor drives an inner rotor shaft (not
shown) extending along the vertical rotor axis R into the pump
housing 5. The pump housing 5 rests on the pump base 3 and encloses
a stack of two impeller stages 10 arranged between the motor stool
7 and the pump base 3. The pump base 5 serves as a stand for the
pump assembly 1 and provides lugs or bores 11 for fixing the pump
assembly 1 to the ground it stands on. The motor housing 9 is
mounted on the motor stool 7 that serves as a mounting adapter
between the pump housing 5 and the motor housing 9. The motor
housing 9 is fixed to the motor stool 7 by accessible bolts 8. The
motor stool 7 thus comprise a motor coupling portion 13 at a first
(upper) axial end to attach the motor housing 9 and a pump coupling
portion 15 at a second (lower) axial end to attach the pump housing
5.
[0067] The example shown FIG. 1b differs from the example shown in
FIG. 1a that the embodiment in FIG. 1b comprises a larger motor
housing 9 with a more powerful motor and one more impeller stage
10, i.e. in total three (see FIG. 3), than the example shown in
FIG. 1a. The motor coupling portion 13 of the motor stool 7 is
therefore adapted to the larger motor housing 9. The pump base 3,
the diameter of the pump housing 5 and the pump coupling portion 15
of the motor stool 7 are basically identical between these two
examples. The motor housing 9 in FIG. 1a has a smaller lateral
extension than the motor coupling portion 13 of the motor stool 7.
The motor housing 9 in FIG. 1b has a larger lateral extension than
the motor coupling portion 13 of the motor stool 7. A certain range
of motor sizes can be mounted on the same motor stool 7. The pump
assembly 1 shown in FIG. 1b is able to provide a higher maximal
fluid flow and head than the pump assembly 1 shown in FIG. 1a. The
motor housing 9 and the motor may be standard multi-purpose
electric motors that may be not only be suitable to drive a rotor
shaft of a pump, but may be applicable for other purposes as
well.
[0068] FIG. 1c shows an example with a pump housing that is longer
in the direction of the vertical rotor axis R, because it encloses
even more impeller stages 10. Thereby, the pump assembly 1 shown in
FIG. 1c is able to provide a higher maximal fluid flow and a higher
head than the examples shown in FIGS. 1a and 1b. Furthermore, the
motor housing 9 in FIG. 1c is larger than in FIG. 1b to enclose a
more powerful motor than in FIG. 1b. The motor stool 7 differs also
from FIGS. 1a and 1b, because the motor housing 9 has such a wide
lateral extension that the motor coupling portion 13 provides for a
mounting flange having a substantially larger diameter than the
pump coupling portion 15 of the motor stool 7. The pump housing 5
and the impeller stages 10 have the same diameter in all three
examples. The pump base 3 is identical for all three examples.
However, the diameter of the pump housing 5, the impeller stages 10
and the pump base 3 may differ between different examples depending
on the requirements of the pump assembly 1.
[0069] In all three examples shown in FIGS. 1a-c, the motor stool 7
is clamped to the pump base 3 by exactly two essentially identical
tie rods 17, of which only a radially outer face 21 of a steel
panel 19 of one of the tie rods 17 is visible in FIG. 1a-c. The
other tie rod 17 is located at the diametrically opposite radial
side of the pump housing 5. The tie rods 17 are under tensile
stress to pull, with an upper motor stool end portion 25 of the tie
rods 17, the upper motor coupling portion 13 of the motor stool 7
downwards and to thereby press the lower pump coupling portion 15
of the motor stool 7 downward against the pump housing 5. A lower
pump base end portion 29 of the tie rods 17 is hooked into the pump
base 3 and pulls the pump base 3 upward against the pump housing 5.
The pump housing 5 is thus securely sandwiched between the motor
stool 7 and the pump base 3.
[0070] FIG. 2 shows the example of FIG. 1b as a first embodiment
with one tie rod 17 dissembled and without the motor housing 9.
This is, because the tie rods 17 cannot be dissembled as long as
the motor housing 9 is coupled to the motor stool 7. This adds
safety to the pump assembly 1. As shown in FIG. 2, the tie rod 17
comprises a longitudinal panel 19 extending essentially straight in
its longitudinal direction. The panel is curved or arc-shaped in a
plane perpendicular to its longitudinal direction, wherein the
curvature essentially corresponds to the curvature of the outer
periphery of the pump housing 5. The panel 19 is thus very stiff
and not flexible. The panel 19 comprises a radially outer face 21
that is visible when the pump assembly 1 is fully assembled and a
radially inner face 23 that at least partially lies at the pump
housing 5 when the pump assembly 1 is fully assembled. A thermal
contact, possibly direct or enhanced by a thermally conductively
pad intermediately placed between the panel 19 and the pump housing
5, provides for a good heat dissipation of the pump housing 5. The
circumferential extension of the panels 19 is significantly larger
than straps known in the prior art. The sum of the circumferential
extension of the panels 19, which is for each panel 19 essentially
constant over the length of the panel 19, covers a fraction in the
range of 1/18 to 1/4 or more, preferably 1/6 or 1/5, of the
circumference of the pump housing 5. As shown in FIG. 5, an angle
.gamma. of circumferential extension of one panel 19 is here
38.degree., which results in a total circumferential extension of
both panels of 76.degree., i.e. .about.1/5 of the circumference.
Thereby, the tensile stress on the tie rods 17 can be efficiently
distributed over the width of the panels 19 in circumferential
direction.
[0071] At an upper motor stool end portion 25 of the tie rod 17,
the tie rod 17 comprises a motor stool connection part 27 extending
radially inward from the radially inner face 23. The motor stool
connection part 27 may be made of steel and welded to the radially
inner face 23 of the steel panel 19. Similarly, and better visible
in FIG. 3, the tie rod 17 comprises, at a lower pump base end
portion 29 of the tie rod 17, a pump base connection part 31
extending radially inward from the radially inner face 23. The pump
base connection part 31 may also be made of steel and welded to the
radially inner face 23 of the steel panel 19. In this first
embodiment, the motor stool connection part 27 comprises an inner
thread 33 for receiving an outer thread 35 of a fastener 37 in form
of a bolt. The inner thread 33 within the motor stool connection
part 27 essentially extends parallel to the longitudinal direction
of the panel 19. The upper motor stool end portion 25 of the panel
19 is flush with the outer periphery of the motor stool 7 when the
tie rod 17 is mounted. In order to accommodate the panel 19, the
motor stool 7 comprises a longitudinal groove 38 into which the
panel snuggly fits to complement the outer periphery of the motor
stool 7 and yield a flush surface. This is aesthetically appealing
and particularly useful for pumps to be used in clean or sterile
environments like the food industry, because flush and smooth
surfaces are easier to keep clean and sterile.
[0072] In this first embodiment, the motor stool 7 comprises two
fixation protrusions 39 in form of inner bores each having a
protrusion end 41 at the motor coupling portion 13. It is important
to note that the protrusions 39 have a lateral distance to the
outer periphery of the motor coupling portion 13 of the motor stool
7 so that the motor housing 9, when coupled to the motor stool 7,
blocks the axial access to the upper protrusion end 41. The
protrusion end 41 is thus inaccessible when the motor housing 9 is
coupled to the motor stool 7. The protrusion end 41 is shielded
against lateral access by the motor stool 7 itself.
[0073] As can be seen better in FIG. 3, the motor stool 7 comprises
two radially outwardly open motor stool recesses 43 for
accommodating the motor stool connection parts 27 of the tie rods
17. When the tie rods 17 are in an installation position as shown
in FIG. 3, the inner threads 33 of the motor stool connection parts
27 are coaxially aligned with the fixation protrusions 39 of the
motor stool 7. The fixation protrusions 39 have a first protrusion
end 41 facing towards the motor housing 9 and a second protrusion
end 45 facing towards the pump base 3 and ending in the motor stool
recesses 43. The bolt of the fastener 37 is inserted from the axial
top end of the motor stool 7 into the first protrusion end 41 and
extends with its outer thread 35 through the fixation protrusion 41
into the inner thread 33 of the motor stool connection part 27 of
the tie rod 17. The motor stool connection part 27 of each tie rod
17 is movable parallel to the rotor axis R within a range inside
the motor stool recesses 43, wherein an upper stop is defined by a
positive form locking between the pump base connection part 31 of
the tie rod 17 and the pump base recess 49 in the pump base 3. So,
the motor stool connection part 27 has some room inside the motor
stool recess 43 in move parallel to the rotor axis R, so that it
can be slightly pulled upward by tightening the bolt 37. Thereby,
the tie rods 17 are put under tensile stress to clamp the motor
stool 7 and the pump base 3 together, because the lower pump base
end portion 29 of the tie rod 17 is hooked into the pump base 3 by
the pump base connection part 31. A bolt head 47 in form of a
socket head of the bolt is fully sunk into the first protrusion end
41 that is formed as a counterbore. Thereby, the bolt does not
axially protrude out of the upper axial end of the motor stool 7,
which makes the motor stool 7 more flexible to receive different
kinds of motor housings 9. The bolt head 47 is an engagement means
of the fastener 37 for a hex to engage with for screwing the bolt.
The bolt head 47 is enclosed by the motor stool 7 so that a hex can
only be applied axially from the upper side of the motor stool 7
when the motor housing 9 is decoupled. There is no access to the
bolt head 47 to laterally apply a hex or another tool.
[0074] The pump base connection part 31 at the lower pump base end
portion 29 of the tie rod 17 projects radially inward into a
radially outwardly open pump base recess 49 of the pump base 3. In
order to provide for a secure positive form locking, each pump base
recess 49 comprise an anchor face 51 for positive form locking with
a hook face 53 of the pump base connection part 31. The anchor face
51 of the pump base recess 49 is inclined by an angle .beta. in the
range of 0.degree. to 15.degree. with respect to the horizontal
xy-plane extending perpendicular to the rotor axis R. The surface
normal N of the anchor face 51 has a vector component pointing
radially inward towards the rotor axis R. Likewise, the hook face
53 of the pump base connection part 31 be correspondingly inclined
by the angle .beta. in the range of 0.degree. to 15.degree. with
respect to the horizontal xy-plane extending perpendicular to the
rotor axis R. The surface normal M of the hook face 53 has a vector
component pointing radially outward away from the rotor axis R. The
surface normal N and the surface normal M are essentially parallel
with opposite vector directions. The contact between the anchor
face 51 and the hook face 53 provides for a secure positive form
locking of the pump base end portion 29 of each tie rod 17.
[0075] Each pump base recess 49 comprises a securing face 55 facing
radially inward toward the rotor axis R for abutting against the
radial outer face 21 of the panel 19 of the tie rod 17. The
securing face 55 is located axially further away from the pump
housing 5 than the anchor face 51. Furthermore, the securing face
55 is located radially more outward than the outer periphery of the
pump housing 5. The pump base recess 49 is axially open to the
bottom so that the pump base end portion 29 of the tie rod 17 can
be placed into the pump base recess 49 when being inclined as shown
in FIG. 2. The securing face 55 adds safety against the pump base
connection part 31 slipping off its positive form fit with the pump
base 3.
[0076] A second embodiment is shown in FIGS. 4a-c, wherein the
second embodiment has a different fastener 37 and fixation
protrusions 39 than the first embodiment. The fastener 37 now
comprises a nut 57 with an inner thread engaging with an outer
thread of a bolt that is now part of or forms the motor stool
connection part 27 of the tie rods 17. When the pump assembly 1 is
fully assembled, the nut 57 is essentially positioned at the same
laterally inaccessible inner seat that the upper protrusion end 41
provides within the motor stool 7 than the bolt head 47 in the
first embodiment. A nut wrench or a spanner may be applied only
from the top side when the motor housing 9 is decoupled from the
motor stool 7. A washer 59 may be placed underneath the nut 57. In
the second embodiment shown in FIGS. 4a-c, the fixation protrusions
39 are radially open recesses in order to facilitate the insertion
of the bolt of the motor stool connection part 27.
[0077] FIGS. 6a-e show how the tie rods 17 of the first embodiment
are mounted. At first, as shown in FIG. 6a, the tie rod 17 is
tilted by a certain angle so that the lower pump base end portion
29 of the tie rods 17 can be fed into the pump base recess 49 of
the pump base 3. Once the pump base connection part 31 is fully
accommodated in the pump base recess 49 as shown in FIG. 6b, the
tie rod 17 is pivoted into a vertical orientation. The motor stool
connection part 27 is thereby inserted laterally into the outwardly
open motor stool recess 43 of the motor stool 7 as shown in FIG.
6c. The panel 19 of the tie rod 17 now extends essentially vertical
parallel to the rotor axis R and rests at the outer periphery of
the pump housing. As shown in FIG. 6d, the bolt of the fastener 37
is inserted from the top side of the motor stool 7 into the
fixation protrusions 39 and screwed into the motor stool connection
part 27 of the tie rod 17. The bolt head 47 is sunk into the motor
coupling portion 13 of the motor stool 7 and rests at a first upper
protrusion end 41 of the fixation protrusions 39 in the motor stool
7. Tightening the bolt 37 results in tensile stress along the panel
19 of the tie rods 17, which clamps the motor stool 7 and the pump
base 3 together while the pump housing is securely sandwiched
between them. As shown in FIG. 6e, once all tie rods 17 are fixed,
the motor housing 9 can be coupled to the upper motor stool
coupling portion 13 of the motor stool 9. The bolt heads 47 are
inaccessible as long as the motor housing 9 is coupled to the motor
stool coupling portion 13 of the motor stool 7.
[0078] FIGS. 7a-e show how the tie rods 17 of a second embodiment
are mounted. In contrast to the first embodiment shown in FIG.
6a-d, the bolt is now part of or forms the motor stool connection
part 27 of the tie rods 17. As the fixation protrusions 39 are
radially open in this embodiment, the motor stool connection part
27 can be placed into the motor stool recess 43 similarly to FIGS.
6a-c. As shown in FIG. 7d, the bolt of the motor stool connection
part 27 is pulled upwards to protrude from below through the
fixation protrusion 39 at the first protrusion end 41 by screwing
the nut 57. As shown in FIG. 7e, once all tie rods 17 are fixed,
the motor housing 9 can be coupled to the upper motor stool
coupling portion 13 of the motor stool 9. The nuts 57 are
inaccessible as long as the motor housing 9 is coupled to the motor
stool coupling portion 13 of the motor stool 7.
[0079] FIGS. 8a-e show how the tie rods 17 of a third embodiment
are mounted. In contrast to the second embodiment shown in FIG.
7a-d, the fixation protrusions 39 are radially closed in form of
inner bores similar to the first embodiment. Therefore, slightly
more room for axial motion is needed for the motor stool connection
part 27 in the motor stool recess 43 and for the pump base
connection part 31 in the pump base recess 49. As shown in FIG. 8c,
the pump base end portion 29 of the tie rod 17 may even need to
shortly protrude downwardly out of the pump base recess 49 of the
pump base 3. For this, the pump assembly 1 may be manually tilted
to shortly allow the necessary space between the pump base 3 and
the ground on which the pump assembly 1 stands. As shown in FIG.
8e, once all tie rods 17 are fixed, the motor housing 9 can be
coupled to the upper motor stool coupling portion 13 of the motor
stool 9. The nuts 57 are inaccessible as long as the motor housing
9 is coupled to the motor stool coupling portion 13 of the motor
stool 7.
[0080] Where, in the foregoing description, integers or elements
are mentioned which have known, obvious or foreseeable equivalents,
then such equivalents are herein incorporated as if individually
set forth. Reference should be made to the claims for determining
the true scope of the present disclosure, which should be construed
so as to encompass any such equivalents. It will also be
appreciated by the reader that integers or features of the
disclosure that are described as optional, preferable,
advantageous, convenient or the like are optional and do not limit
the scope of the independent claims.
[0081] The above embodiments are to be understood as illustrative
examples of the disclosure. It is to be understood that any feature
described in relation to any one embodiment may be used alone, or
in combination with other features described, and may also be used
in combination with one or more features of any other of the
embodiments, or any combination of any other of the embodiments.
While at least one exemplary embodiment has been shown and
described, it should be understood that other modifications,
substitutions and alternatives are apparent to one of ordinary
skill in the art and may be changed without departing from the
scope of the subject matter described herein, and this application
is intended to cover any adaptations or variations of the specific
embodiments discussed herein.
[0082] In addition, "comprising" does not exclude other elements or
steps, and "a" or "one" does not exclude a plural number.
Furthermore, characteristics or steps which have been described
with reference to one of the above exemplary embodiments may also
be used in combination with other characteristics or steps of other
exemplary embodiments described above. Method steps may be applied
in any order or in parallel or may constitute a part or a more
detailed version of another method step. It should be understood
that there should be embodied within the scope of the patent
warranted hereon all such modifications as reasonably and properly
come within the scope of the contribution to the art. Such
modifications, substitutions and alternatives can be made without
departing from the spirit and scope of the disclosure, which should
be determined from the appended claims and their legal
equivalents.
[0083] While specific embodiments of the invention have been shown
and described in detail to illustrate the application of the
principles of the invention, it will be understood that the
invention may be embodied otherwise without departing from such
principles.
LIST OF REFERENCE DESIGNATIONS
[0084] 1 pump assembly [0085] 3 pump base [0086] 5 pump housing
[0087] 7 motor stool [0088] 8 accessible bolts for mounting the
motor housing [0089] 9 motor housing [0090] 10 impeller stages
[0091] 11 bores or lugs in the pump base [0092] 13 motor coupling
portion of the motor stool [0093] 15 pump coupling portion of the
motor stool [0094] 17 tie rods [0095] 19 panel of the tie rod
[0096] 21 radially outer face of the panel of the tie rod [0097] 23
radially inner face of the panel of the tie rod [0098] 25 motor
stool end portion of the tie rod [0099] 27 motor stool connection
part of the tie rod [0100] 29 pump base end portion of the tie rod
[0101] 31 pump base connection part of the tie rod [0102] 33 inner
thread of the motor stool connection part of the tie rod [0103] 35
outer thread of a bolt [0104] 37 fastener [0105] 38 longitudinal
groove of the motor stool [0106] 39 fixation protrusions of the
motor stool [0107] 41 first protrusion end of the fixation
protrusion [0108] 43 motor stool recesses [0109] 45 second
protrusion end of the fixation protrusion [0110] 47 bolt head
[0111] 49 pump base recess [0112] 51 anchor face of the pump base
recess [0113] 53 hook face of the pump base connection part of the
tie rod [0114] 55 securing face of the pump base recess [0115] 57
nut [0116] 59 washer [0117] K surface normal of the securing face
[0118] M surface normal of the hook face [0119] N surface normal of
the anchor face [0120] .beta. angle of orientation of the
hook/anchor face [0121] .gamma. angle of circumferential extension
of a panel of a tie rod
* * * * *