Note: Descriptions are shown in the official language in which they were submitted.
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SUBMERSIBLE MOTOR-DRIVEN PUMP WITH AN ANTI-FREEZE DEVICE
The present invention concerns a submersible
motor-driven pump, which comprises a housing; an intake pipe
mounted in the housing; an impeller mounted in the intake
pipe to produce an intake flow and to convey a fluid to a
discharge connection, said impeller being supported on a
shaft connected to a motor; and a can into which the shaft
extends.
Submersible motor-driven pumps are already known
from the general state of the art. If they are installed in
a pond or a liquid medium without freeze protection, they
must be removed from their site of installation in the
wintertime and stored where they are protected from
freezing. In a submersible pump, an impeller is usually
connected by a ceramic shaft to a motor, which drives the
impeller when the pump is being operated.
It is well known that ceramic shafts are sensitive
to pressure acting on them and can easily break.
Nevertheless, ceramic shafts are preferred in known
submersible pumps for their many other favorable properties.
In the winter, the liquid medium, which is not
frostproof, freezes solid from the surface towards the
bottom. If, for example, a submersible motor-driven pump
spends the winter in a garden pond, it can freeze during a
period of freezing weather. A submersible motor-driven pump
of this type contains pond water that has remained in the
housing since the last operation of the pump or has
subsequently penetrated the chambers of the housing. This
water slowly freezes solid from top to bottom and exerts
pressure on the generally horizontally oriented shaft. When
the ice formation in the housing progresses downward, and
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the water below the intake pipe, which is arranged laterally
and concentrically with the shaft, also expands, the actual
risk of fracture of the shaft due to freezing begins,
especially in the case of a ceramic shaft.
Therefore, the objective of the invention is to
develop a submersible motor-driven pump that can remain in a
liquid and freezing medium, even during periods of freezing
weather, without sustaining any damage.
In accordance with the invention, this objective
is achieved by installing an anti-freeze device for the
shaft in the housing.
The anti-freeze device protects the shaft from
freezing damage to a very great extent and protects it
especially from freeze-related fracture.
Another advantage of the present invention is that
the anti-freeze device is supported in an elastic bushing at
the entrance to the can. Pressure transverse to a shaft
axis X can be absorbed in this way.
Another advantage is that the anti-freeze device
comprises a water displacer, which is arranged
concentrically to the shaft or shaft axis X in free spaces.
In particular, depending on the shaft length, there is a
large free space in the can between the elastic bushing and
a part of the motor that forms a rotor. The water displacer
occupies a space in which the liquid medium and especially
the freezing-susceptible pond water would otherwise collect
and would exert pressure on the shaft. The water displacer
thus keeps the water away from the shaft.
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Another advantage is that the impeller is
elastically mounted on the shaft. Elastic mounting of this
type is accomplished, e.g., with an elastomer.
Still another advantage is that the lowest point
of the water-containing region, generally a closed drain
hole below the impeller, is closed with an elastic diaphragm
that can expand when exposed to frost to absorb ice pressure
from the shaft.
Specific embodiments of the present invention are
described in greater detail below with reference to the
drawings.
Figure 1 shows a schematic longitudinal section
through a submersible motor-driven pump with an anti-freeze
device in accordance with a first embodiment of the present
invention.
Figure 2 shows a schematic detail view from Figure
1, which shows an elastic diaphragm in the expanded state in
the right half and in the unexpanded state in the left half.
Figure 3 shows a schematic detail view from Figure
1, which shows an elastic impeller mounting.
Figure 4 shows a schematic longitudinal section
through another submersible motor-driven pump with an anti-
freeze device in accordance with a second embodiment of the
present invention.
Figure 5 shows a schematic longitudinal section
through another submersible motor-driven pump with an anti-
freeze device in accordance with a third embodiment of the
present invention.
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Figure 1 shows a schematic longitudinal section
through a submersible motor-driven pump 1 in its working or
operating position. A housing 3 is connected with an intake
pipe 5 at one of its end faces (left side in Figure 1). The
intake pipe 5 is part of an intake housing 7, on which a
pump connection 9 and a discharge connection 11 are also
formed. An impeller 13, which is mounted on a shaft,
especially a ceramic shaft 15, is installed in working
connection with the intake pipe 5 and the pump connection 9
in the intake housing 7. The ceramic shaft 15 has a shaft
axis X, which, in the illustrated operating position,
extends in an essentially horizontal direction into a can
17, which is installed in the housing 3. The ceramic shaft
is supported at the junction between the intake housing 7
15 and the can 17 in a ceramic bearing 19, which in turn is
supported in an elastic bushing 20. A water displacer 23,
which fills a structural free space, is formed
concentrically on the ceramic shaft 15 between the ceramic
bearing 19 and a rotor 21 located on the ceramic shaft 25 in
the can 17. The water displacer 23 preferably extends the
same radial distance from the shaft axis X as the rotor 21,
so that a more or less uniform air gap 25 is formed between
the inner wall of the can 17 and the rotor 21 and water
displacer 23. The air gap 25 can have a width of, for
example, 0.2 mm.
The discharge connection 11 is located at the
lowest point of the region of the submersible motor-driven
pump 1 that contains water or other liquid medium and is
separated from this region in the vertical direction by an
elastic diaphragm 25. The left half of Figure 2 shows how
the elastic diaphragm 25 is undeformed under normal pressure
conditions of the water or other liquid medium. The right
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half of Figure 2 shows how the elastic diaphragm 25 is
deformed by ice pressure when the liquid medium freezes.
The impeller 13 is also elastically mounted on the
ceramic shaft 15. Figure 3 shows an elastic mounting 27 for
the impeller 13, which holds the impeller on the ceramic
shaft 15. In the present embodiment, the elastic mounting
27 for the impeller 13 is an elastomer, which is designed as
an inner sleeve 31 between an outer sleeve 29 of the
impeller 13 and the ceramic shaft 15 and extends over a
portion of the length of the ceramic shaft 15 in the
direction of the shaft axis X.
Each of the anti-freeze features of the
submersible motor-driven pump, namely, the elastic bushing
19, water displacer 23, elastic diaphragm 25, and elastic
impeller mounting 27, by itself improves the freezing
protection of the pump. The freezing protection is further
optimized by the combination of the specified individual
anti-freeze features. Therefore, in other embodiments, it
is possible to use only some of the aforementioned anti-
freeze features or any desired combinations of these
features in a submersible motor-driven pump 1.
The choice of the elastic materials used for the
features mentioned in the preceding paragraph depends on the
subfreezing temperatures to be expected. Thus, it is
possible to use any known state-of-the-art elastomeric
materials that are dimensionally stable and water-resistant
and do not lose their elastic properties even at subfreezing
temperatures. Elastomeric materials of this type are known
from the state of the art and include, for example, such
elastomeric materials as natural or synthetic rubbers and
rubber mixtures.
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Figure 4 shows a schematic longitudinal section
through a second embodiment of a submersible motor-driven
pump 10 in a working or operating position. A housing 30 is
connected with an intake pipe 50 at one of its end faces
(left side in Figure 4). The intake pipe 50 is part of an
intake housing 70, on which a pump connection 90 is also
formed. An impeller 130, which is mounted on a shaft,
especially an oxide ceramic shaft 150, is installed in
working connection with the intake pipe 50 and the pump
connection 90. The oxide ceramic shaft 150 has a shaft axis
X, which, in the illustrated operating position, extends in
an essentially horizontal direction into a can 170, which is
installed in the housing 30.
The impeller 130 can be mounted on the oxide
ceramic shaft 150 in the same way that is shown in Figure 3
for the first embodiment.
In the second embodiment in Figure 4, an annular
space 190 is arranged in front of the intake housing 70 in
the direction of the intake pipe 150. In the second
embodiment with the annular space 190, the intake pipe 150
is screwed onto the intake housing 70. Other types of
joints are also conceivable. A water displacer 210 is
installed in the annular space 190. It consists, for
example, of a closed-cell foamed plastic or a similar
material that is well known from the state of the art. An
air-filled membrane, similar to an expansion vessel in a
heating system, is also conceivable, for example.
The annular space 190 is connected with the
interior of the intake housing 70 by channels or slots 230.
These slots 230 are distributed on the inside bordering on
the periphery of the intake housing 70. Water/ice pressure
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can escape into the annular space 190 through these slots
230. In this embodiment, the submersible pump 10 can freeze
in various spatial positions without being damaged by the
water/ice pressure.
A third embodiment of a submersible pump 10 is
shown schematically in Figure 5. The submersible pump 1 is
identical to the submersible pump 10 of the second
embodiment, except for the anti-freeze device, so that
another general description is unnecessary. Corresponding
parts are labeled with reference numbers that correspond to
the reference numbers of the first and second embodiment.
In this third embodiment, the anti-freeze device also
includes an annular space 1900. However, it is arranged
between the intake housing 70 and the can 170. The water
displacer 210 is located in the annular space 1900 and can
consist of the same materials as in the second embodiment.
The annular space 1900 is connected by channels or slots
2300 with the interior of the can 170, on the one hand, and
with the interior of the intake housing 70, on the other
hand. The slots 2300 are also arranged here on the inside
bordering on the periphery of the intake housing 70 and the
can 170. In this way, the water/ice pressure can escape
both from the can 170 and from the intake housing, and the
submersible pump can freeze in various spatial positions
without sustaining any freezing damage.
The third embodiment is suitable for so-called
wet-running motors, in which the can 170 is filled with
water.
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