Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Nozzle propeller device
5 The present invention relates to a nozzle propeller device, which propeller
device comprises a propeller nozzle, inside which is arranged a propeller drivenby a propeller shaft.
As is previously known, the propelling force of a propeller can especially at low
10 speeds be improved by means of a propeller nozzle to be placed around a
circular propeller nozzle. For achieving the necessary propelling force, the
diameter of the propeller then used can be possibly even slightly decreased. In
ice conditions, however, a fairly considerable problem occurs in connection witha nozzle propeller device, i.e., the propeller device can be blocked when ice
15 blocks wedge between the frame of the propeller device and the nozzle, or on
the other hand, when travelling in brash and the front part is filled with brash.
In both cases, the water supply of the propeller is prevented either partially or
totally, which results in an essential decrease in the propelling force of the
propeller. This problem is especially apparent in connection with small propel-
20 ling devices. In many cases, a propeller nozzle is therefore not used. Forexample in harbour icebreakers, it has not been possible to use a propeller
nozzle, since in narrow docks ice often packs and accumulates in such a way thatdocks contain packed ice down to the bottom.
25 Attempts have previously been made to prevent the blocking of a nozzle in
several ways, but with fairly poor results. In propeller nozzles used without
additional devices, attempts have been made to prevent the blocks in such way
that the rotational direction of the propeller has been reversed. However, this
solution is fairly poor especially in cases, in which there is plenty of packed ice.
30 A vessel can then advance only by jerks and by very short distances at a time.
In addition, an attempt has been made to prevent a blockage by arranging
various additional devices in connection with the propeller nozzle device. Such
solutions have been previously described e.g. in Finnish patent applications no.
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861370 and 861371. In these publications, attèmpts have been made to prevent
the blocks in such a way that prongs or the like have been fastened to the
nozzle, the purpose of which is to crush the ice blocks, or in such a way that aseparate circular part has been arranged in front of the propeller nozzle, the
S purpose of which is to prevent the ice blocks from blocking the propeller nozle.
However, these solutions have not eliminated the problem, but ice blocks have
still blocked the propeller nozle, since they have fastened to said prongs or
circular part.
10 Attempts have previously been made to prevent the blocking of the nozzle alsoin such a way that an "ice cage" has been arranged in front of the nozzle to
prevent ice blocks from entering the nozzle. However, essential drawbacks of
this solution are a high resistance caused by the ice cage and its poor durability.
In addition, at high speeds the "ice cage" itself blocks in spite of whether said
15 cage is streamlined or not. The cage can fill with crushed ice, since suitably
small pieces of ice can succeed in entering the gaps of the cage, but do not
come into a correct position to be able to come out of a gap of the same size.
Such cages can be mounted stationary on the hull of a vessel, or e.g. in connec-tion with a turning propeller device, they can be mounted stationary on the
20 propeller device itself to turn with it. It has yet not been possible to solve the
blocking prob1em by means of them, as mentioned above.
The object of the present invention is to create such a nozzle propeller device,which avoids the drawbacks related to prior art and which prevents the wedging
25 of ice b10cks between the propeller device frame and the nozzle. For achieving
this, the invention is mainly characterized in that in front of a prope11er arranged
to rotate inside a propeller nozzle is arranged a front piece acting as an ice
crusher and provided with blades or corresponding extensions, which front piece
is arranged to rotate on the same rotational shaft as the propeller.
As the most important advantage of the invention in comparison with solutions
of prior art can be regarded that the solutions of prior art have been "passiw"
and tried only to prevent ice blocks from blocking the propeller device, whe-
reas the device in accordance with the invention is arranged to operate "actively"
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in such a way that the inventive nozzle propeller device is provided with an
arrangement, which tries to crush large ice blocks stuck in the nozzle so that
they can pass through the nozzle, in which case the nozzle itself does not block.
At the same time, the crusher acts a feeder screw that packs the ice blocks to
the nozzle. The other advantages and characteristics of the invention are
presented in the following more detailed description of the invention.
The invention is next described in more detail with reference to the figures of
the accompanying drawing.
Fig. 1 is a schematic side view of an inventive nozzle propeller device in the
form of a turnable propeller device.
Fig. 2 corresponds to Fig. 1 seen from view D.
Fig. 3 is a schematic sectional view of a propeller device of Fig. 1 and 2 and
shows an alternative embodiment of a driving system of the propeller device.
Fig. 4 shows schematically the inventive nozzle propeller device in connection
with a conventional unturnable propeller drive.
In Fig. 1-3 of the drawing, the inventive nozle propeller device is marked
generally by a reference number 10. The type of the nozle propeller device 10
of Fig. 1-3 is e.g. such a turnable propeller device, which is described previously
in the Finnish patent applications no. 830373 and 853173. The propeller device
thus comprises a frame 11, to which a propeller nozzle 12 is fastened by means
of a support construction 13. A propeller 14 is fastened rotatively inside the
propeller nozzle 12. Power is supplied to the propeller device 10 by a vertical
shaft 18, which drives by means of an bevel gearing 20 a propeller shaft 22, to
which a hub 15 is fastened and which is rotatively mounted on an bevel-gearing
frame 21.
In conventional propeller devices, the front part of the bevel-gearing frame is
formed as a streamlined front dome, but in the solution in accordance with the
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invention the front dome is replaced by a rotating front piece 16, to whose
surface blades 17 are fastened. The front piece 16 is arranged tO rotate with the
propeller 14 around a cornmon rotational shaft S-S. The front piece 16 can be
mounted freely rotatively on the propeller device frame 11, but in the most
5 preferable embodiment of the invention the front piece is arranged to be driven.
The purpose of the front piece and the blades 17 fastened thereto is to produce
movement in the ice blockage in front of the propeller nozzle 12 and crush the
ice blocks in front of the propeller nozzle 12 in such a way that they can pass
through the propeller nozzle 12 or are guided outside the propeller nozzle. The
10 blades 17 can be e.g. straight or prong-like, in which case they act only as an ice
crusher, but on the other hand, they can be arranged, as shown in the figure, inan ascending form, whereby they in a way act as a second propeller and as a
device guiding the crushed ice. In the figures of the drawing, the blades 17 areshown to have a fairly small size, but their size can also be considerably larger
15 than that shown in the figures, which improves their propelling and crushing
effect.
The propeller nozzle 12 is in a conventional manner formed in such a way that
it narrows from its leading edge 12a, until it after the narrowest point of the
20 propeller nozzle 12, which is marked in the figures of the drawing with a
reference A, continues mainly cylindrical to the trailing edge 12b of the propel-
ler nozzle. In order that the front piece 16 with its blades 17 would act in theintended manner, it is placed with respect to the propeller nozzle 12 in such a
way that it is located at the narrowest point A of the propeller nozzle 12, at the
25 start of the cylindrical portion or on its front side. This ensures that the ice
blocks are crushed so small that they can pass through the narrowest point A of
the propeller nozzle 12.
It was mentioned above that the front piece 16 acting as an ice crusher can be
30 arranged freely rotatively in the propeller device 10, but in its most preferred
form it is driven. Fig. 3 shows an alternative embodiment of a drive of the front
piece 16 acting as an ice crusher. As mentioned above, in the embodiment of
Fig. 3 power is supplied to the propeller shaft 22 on a vertical shaft 18 via a
bevel gearing 20. The bevel gearing 20 is comprised of a first bevel gear 19 on
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the vertical shaft 18 and of a second bevel gear 23 on the propeller shaft 22. In
the embodiment of Fig. 3, the propeller shaft is extended past the front bearingpoint to the front side of the bevel-gearing frame 21, and the front piece 16
acting as an ice crusher is fastened in a suitable manner to said propel1er shaft
5 22. In the solution of Fig. 3, the front piece 16 acting as an ice crusher thus
rotates in the same direction as the propeller 14 and at the same rotational
speed.
The solution of Fig.3 may be regarded as the best embodiment of the invention,
10 since its construction is the simplest and thereby the most reliable in operation.
However, the drive of the front piece 16 acting as an ice crusher can be ar-
ranged mechanically for example so that the front piece 16 is arranged to rotatein an opposite direction relative to the propeller 14. The drive of the front piece
can then be realized in a known manner, as according to a Finnish patent
application no. 861798. The construction of the propeller device will then yet be
more complicated than the construction of Fig. 3. However, the rotation of the
front piece 16 can be arranged also e.g. electrically, hydraulically or in some
other non-mechanical manner. Such modes of operation nevertheless further
increase the complexity of the construction of the propeller device 10 and are
20 thus more expensive than a mechanical mode of operation.
Fig. 1-3 show the use of the front piece 16 acting as an ice crusher in connection
vrith a turnable propeller device 10 provided with a bevel gearing 20. However,
the invention can also be applied to conventional nozzle propeller devices, and
25 an attempt is made to illustrate this schematically in Fig. 4. In Fig. 4, the hull of
the vessel is marked with a reference number 5. Power is supplied to a propeller34 via a propeller shaft 42, which is in a conventional manner mounted on the
vessel hull 5. Around a propeller 34 is arranged a propeller nozzle 32, which isin a suitable manner fastened to the vessel hull 5. Fixing elements are not shown
30 in Fig. 4. In the embodiment of Fig. 4, the propeller shaft 42 is extended from
the vessel hull 5 by such a distance that it has been possible to place between
the propeller and the hull S a front piece 36 provided with blades 37, which is
in a suitable manner fastened to the propeller shaft 42, to which also a propeller
hub 35 is fixed. In the embodiment of Fig. 4, the front piece 36 acting as an ice
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crusher thus rotates together with the propeller 34. As regards the location of
the front piece 36, the same principle as that described above is followed, i.e.the front piece is placed at the narrowest point A of the propeller nozzle 32 oron its front side.
s
In Fig. 4, the nozzle propeller device is generally marked with a reference
number 30 and the leading edge of the propeller nozzle 32 with a reference
number 32 and the trailing edge with a reference number 32b. Although the
inventive nozzle propeller device 30 can also be realized as a conventional
10 solution according to Fig. 4, problems may however occur in this connection e.g.
with respect to the bearing arrangement of the propeller shaft 42, since the
propeller shaft 42 is extended longer th~n in conventional solutions. As a result,
the solution according to the invention can be regarded as the most preferable
in the embodiment of Fig. 1-3. In Fig. 1-3, the use of the invention is more
15 preferable also because the front piece 16 and the blades 17 therein can be
formed more freely than in the solution of Fig. 4.
The invention has above been described by way of example with reference to
the ffgures of the accompanying drawings. However, this is not intended to limit20 the invention only to the examples shown it the figures, but many modifications
are possible within the scope of the inventhe idea defined in the enclosed
patent claims.
