Note: Descriptions are shown in the official language in which they were submitted.
GR 00 P 8524 P
Description
CA 02373465 2001-11-13
Electrical steering propeller having a small installed
height
The invention relates to an electrical steering
propeller having a small installed height for a
seagoing high-speed ship, having a polyphase electric
motor which is mounted under the stern of the ship via
a shaft which can rotate and preferably has two parts
in a gondola-like housing, and can be supplied with
electrical drive power via a slipring arrangement, and
can be rotated via drive motors.
The prospectus from Siemens and Schottel, entitled "The
SSP Propulsor", No. 159U559 04982, April 1998,
discloses a steering propeller which can be rotated, in
which the sliprings for transmission of the electrical
drive power are arranged, in the same way as the
hydraulic drive motors for the rotary movement and
their hydraulic pumps, in a drive machine room
(Propulsor 500 m) above the steering propeller. The
cables are supplied to the sliprings from above.
The object of the invention is to refine the known
drive such that, in particular for roro ships, more
space is obtained in the stern of the ship. In roro
ships, by way of example, it is intended to be possible
to construct a continuous internal car deck without the
stern door for the car deck, and the car deck itself,
having to be raised. In this case, as before, adequate
capabilities for repair and maintenance should be
provided. In this case, it is intended to be possible
to design the conditions downstream from the stern to
optimize the drag, taking account of the flow
conditions resulting from the use of steering
propellers.
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The object is achieved in that the steering propeller
is mounted in the stern of the ship via a flat collar
bearing in the vicinity of the outer skin, in
particular above the waterline, with the slipring
arrangement being
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accommodated in the upper part of the shaft at the
level of the annular bearing, and with the drive motors
for the rotary movement being physically small and
being arranged at least partially in the interior of
the collar bearing. This results in the small installed
arrangement, desired according to the invention, for
the electrical steering propeller. Admittedly, at
first, it appears to be impossible to accommodate the
sliprings and the drive motors for the rotary movement
etc. in the upper part of the shaft with its "rotating
bearing" constriction, so that it is still possible to
produce a passage downward. However, the invention is
feasible by optimizing the sizes of all the parts and
by largely dispensing with horizontally running struts.
This makes it possible to move the drive motors for the
rotary movement to the area under the slipring
arrangement.
The flat collar bearing can be arranged both above the
waterline and, alternatively, below the waterline. In
the case of an arrangement below the waterline, it is
advantageously kept at an increased pressure. The
arrangement disclosed in Canadian Patent Specification
1.311.657, with the shaft entering the ship below the
waterline and an internal extension of the shaft to
above the waterline, is considerably less advantageous.
This can result in seawater entering the interior of
the bearing.
If the shaft it mounted in a large-diameter collar
bearing above the waterline, with the bearing diameter
being approximately equal to or greater than the
winding length of the electric motor, this results,
especially when, as advantageously proposed, the collar
bearing also has a large internal diameter, in the
upper part of the shaft of the steering propeller being
so roomy that the slipring arrangement, whose size has
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been optimized, and the rotating motors can be
accommodated completely inside it. It is thus highly
advantageously possible to dispense with a separate
machine room above the steering propeller, and
installed height can be saved. The collar bearing can
be arranged directly under the car deck.
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In this case, it is advantageous for the shaft to have
a shaft upper part which is arranged above the ship's
waterline, and which is largely arranged recessed in
the ship's stern. This very advantageously results in
all the major parts of the rotating drive being
arranged in a protected manner outside the water
flowing around the hull. If the height of the shaft
lower part in this case corresponds approximately to
the gondola diameter, this results in a very physically
small drive overall, since the high-speed double
propeller intended for use makes it possible to choose
relatively small propeller diameters. This
advantageously allows a drive to be produced for
shallow-draft ships, configured according to the
invention.
A further refinement of the invention provides for the
drive motors for the rotary movement to be in the form
of flat hydraulic radial piston motors. This results in
a particularly advantageous configuration of the
rotating motors, with small dimensions and a large
torque.
The invention advantageously provides for the
possibility of connecting the shaft to the ship's hull
via an intermediate covering part immediately under the
lowermost cargo deck in the stern area, for example the
car deck in the case of roro ships. Such a small
intermediate covering part, which may also be in the
form of an annular disk, advantageously results in the
capability to install the electrical steering propeller
such that it is both particularly stable and is
physically small. The intermediate covering part can be
arranged in the stern area both via mounting elements,
for example boxes, and directly, for example by fitting
it on the double bottom.
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Particularly in the case of roro ships, it is in this
case advantageous if the shaft is mounted under a
steering propeller sealing cover in the ship's stern,
with the sealing cover advantageously being a component
of the car deck when the ship is in the form of a roro
ship. This results in particularly good utilization of
the physical height available in the stern of the
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ship, which allows vehicles to be driven directly onto
the inner car deck via the stern door. This allows the
car deck to be used over the full length of the ship,
thus resulting in previously impossibly good space
utilization for the main car deck. Full utilization of
the weather-deck area is likewise ensured, in which
case the capstan drives etc. can advantageously be
arranged under the weather-deck in order to enlarge the
usable area.
A refinement of the invention provides for the sealing
cover to have access openings to individual appliances
in the steering propeller, for example to the slipring
arrangement, to the drive motors for the rotary
movement and to other essential functional elements.
Thus, advantageously, there is no need to remove the
sealing cover in the car deck for servicing work and
minor repairs, since the corresponding appliances can
instead be accessed via access openings like manholes.
The invention in this case advantageously provides for
the upper part of the steering propeller to be sealed
in a fire-resistant manner from the lowermost deck in
the stern area. This advantageously makes it possible
to comply with the safety requirements for roro or
ropax ships, without needing to modify the advantageous
configuration, which requires a minimal installed
height, of the electrical steering propeller.
The invention furthermore provides for the electrical
steering propeller that the sliprings for supplying
power to and monitoring the motor are at least
partially in the form of concentric sliprings. This
results in a small physical shape for the power supply
and signal transmission components. For electric motors
having more than 3 phases, for example for 6-phase or
12-phase electric motors, as well as for split electric
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motors, the invention in this case provides in
particular for the power supply sliprings to be
designed to have only 3 phases and for a junction to a
motor winding system having more than 3 phases
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to be made behind the slipring arrangement via power
semiconductors, which form a local converter and are
arranged in the shaft. It is thus also possible to
supply power to polyphase or split electric motors with
a physically small, relatively simple slipring body.
This considerably simplifies the construction, and
considerably reduces the physical height of the
slipring arrangement. Polyphase winding systems can
thus be supplied with electrical power in a controlled,
advantageous manner. The power semiconductors can
highly advantageously by well cooled via heat
dissipation elements which are connected to the shaft
casing, which is well cooled by the seawater flowing
around it.
The cables for power transmission are advantageously
routed from the side to the slipring arrangement of the
shaft. This admittedly requires a separate connecting
element on the slipring arrangement. The additional
costs incurred as a result of this are, however, more
than compensated for by the gain in space. The
connecting element can advantageously run between the
vehicle lanes on the car deck of a roro ship. This
therefore does not detract from the small installed
height of the steering propeller.
As a result of the arrangement of the drives for the
rotary movement and for the slipring body etc. in the
shaft upper part, these must be [lacuna] close to the
auxiliary appliances in the shaft, for example the
bilge pumps and oil pumps etc. If required, power
semiconductors are also located in this area, since the
lower shaft part is designed to be narrow to assist the
flow (also acting as a rudder). It is impossible to
prevent heat accumulations from being formed. This is
overcome by arranging at least one fan in the upper
part of the shaft, which allows air to circulate in the
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shaft upper part, and if necessary also allows air to
be interchanged.
The invention furthermore advantageously provides for
the transition from the upper part to the lower part of
the shaft to be located at the same level as the outer
skin of the ship, preferably entirely above the
waterline. The flange between the upper part and lower
part
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of the ship can thus be removed from the flow around
the hull, thus also allowing the shaft to be replaced
with the electric motor for repairs, without any need
for the ship to be docked. For reliably "dry"
replacement, it is sufficient for the ship to be
trimmed bow-down.
A further refinement of the invention provides for the
motor shaft of the steering propeller to be inclined at
an angle matched approximately to the stern profile of
the ship. This results in a particularly advantageous
downstream flow in the stern area of the ship, which
highly advantageously makes use of the flow,
accelerated by the propellers, to reduce the stern drag
of the ship. The steering propeller according to the
invention can then be arranged right at the .stern
without any disadvantageous effects on the flow. This
advantageous configuration results in the maximum
amount of space being gained. Thus, overall, not only
does the use of the steering propeller according to the
invention, with a small installed height, result in
better utilization of the space available in the stern
area of the ship's hull, but there is also no
deterioration in the flow in the stern area in
comparison to conventional steering propellers arranged
more deeply under the ship.
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In accordance with this invention, there is
provided a seagoing high-speed ship having an electrical
steering propeller which has a polyphase electric motor
which is mounted under the stern of the ship via a shaft
which can rotate and preferably has two parts in a gondola
like housing, and can be supplied with electrical drive
power via a slipring arrangement, and can be rotated via
drive motors, characterized in that the steering propeller
is mounted in the stern of the ship via a flat collar
bearing in the vicinity of the outer skin, in particular
above the waterline, with the slipring arrangement being
accommodated in the upper part of the shaft at the level of
the annular bearing, and with the drive motors for the
rotary movement being physically small and being arranged at
least partially in the interior of the collar bearing, in
order to achieve a small installed arrangement for the
steering propeller.
The invention will be explained in more detail
with reference to the drawings from which, in the same way
as from the dependent claims, further details that are
essential to the invention will become evident. In detail:
Figure 1 shows a steering propeller according to
the invention with its installation that occupies very
little space, from the side,
Figure 2 shows a double steering propeller
arrangement in the stern area of the ship, from astern,
Figure 3 shows the double steering propeller
arrangement illustrated in Figure 2, from above,
Figure 4 shows the shaft upper part, with the
cable supply at the side, from the side.
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Figure 5 shows the shaft upper part as shown in Figure
4, from above, and
Figure 6 shows a compressed section through a collar
bearing arrangement with a particularly small
installed height.
Figure 1 shows a roro or ropax application with a very
small installed height between the outer skin 6 and the
car deck 5. All the components of the electrical
steering propeller, with the exception of the shaft 2
and the motor part 1, are fitted into this small
installed height.
The following measures are taken, by way of example, in
order to achieve the fit described above:
A small intermediate covering part 10, possibly in the
form of an annular disk, is inserted between the outer
skin 6 and the car deck 5, with the steering propeller
being mounted on it. The stationary parts of the collar
bearing 7 are arranged above the intermediate covering
part 10. A cover 4, which is advantageously sealed in a
fire-resistant manner, is installed in the car deck 5,
through which the steering propeller unit located
underneath is accessible. Various small covers (not
shown) which provide easy access to the major
functional parts of the steering propeller are inserted
into this - large - cover 4. The slipring arrangement 8
and the rotating motors 9 are very largely located in
the interior of the collar bearing 7 and in the shaft
upper part 3. The collar bearing 7, together with the
intermediate covering part 10 (which is physically
particularly small here), is advantageously arranged in
the stern of the ship, via a box structure 11.
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The large cover 4 can be supported directly or
indirectly on the intermediate covering part 10, so
that the space under the cover 4 has a very small
physical height, and the overall installed height is
thus optimally low. The bending-resistant power
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supply cable can advantageously be routed to the
slipring arrangement from the side, so that the cover 4
is smooth and can be mounted directly above the
slipring arrangement.
The steering propeller itself is advantageously
inclined such that its drive axis runs at a rising
angle to the rear. This improves the downstream flow,
even if the stern is short. In this case, the
separating flange between the upper part of the
steering propeller 3 and the shaft may be located
approximately at the same level as the outer skin so
that, if the steering propeller is arranged relatively
far to the stern, and it is physically short, no flange
parts need be arranged in the flow around the hull.
The cover 4 is advantageously provided with a fire-
resistant seal so that, in the event of a fire in this
part of the drive system, there is no risk to the car
decks located above it. Conversely, the operation of
the drive system is not adversely affected by a fire on
the car deck, and the ship can still be propelled.
The low height between the intermediate covering part
and the cover is also achieved by using flat radial
piston hydraulic motors for the azimuth drive. The
medium voltage for the main motor, the low voltage for
the auxiliary systems and the signals for
control/regulation of the motor are transmitted via the
electrical slipring arrangement 8, which is located in
the upper part 3 of the shaft and, in particular, has a
number of parts. The steering propeller itself can be
rotated endlessly through 360°. The sliprings of the
slipring arrangement 8 are arranged especially
concentrically with respect to one another, with the
signal transmission antennas (which are not shown in
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any greater detail) advantageously being located on the
outside.
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Figure 2 shows the two steering propeller units,
annotated 18 and 19. In this embodiment, the
intermediate covering part is advantageously located
directly on the double bottom 17. The column bearing is
mounted, for example, via struts, and the rotating
motors are arranged in the same way as the slipring
bodies, according to the invention, in the intermediate
space 16 underneath the car deck 15. This results in a
small physical height for the installation of the
steering propellers, which are arranged well astern.
As can be seen from Figure 3, the auxiliary appliances
12 for the azimuth drive, for example the hydraulic
pumps and their motors, are likewise located in the
intermediate space underneath the car deck. The two
steering propellers 13 and 14 are supplied with
rotation power via short hydraulic lines. According to
the invention, this also advantageously makes it
possible to dispense with a separate machine room above
the steering propellers 13 and 14.
In Figure 4, 21 denotes a cable connection which is
routed at the side, 23 denotes the upper cover on the
slipring arrangement, and 22 denotes the upper parts of
the drives for the rotary movement. Figure 4 shows a
particularly good example of the small installed height
which can be achieved.
In Figure 5, 24 denotes the connecting part of the
cable connection 29, 27 denotes an entry into the
shaft, and 26 denotes a spare cross section. 28 denotes
a fan, and 30 a drive for the rotary movement. Since
the components shown all also have connecting lines,
terminals, mounting elements, flanges etc., it is
obvious that optimization was required here,
necessitating detailed considerations.
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In Figure 6, which shows a physically small collar
bearing according to the invention, illustrated
partially in the form of a section, 31 denotes the
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ship structural part which forms the base for the
collar bearing. This may be, for example, an
intermediate covering part, a part of the double bottom
or an annular part on the outer skin of the ship. 32
denotes, for example, the car deck in the case of a
roro ship, or the deckhead on the car deck. 33 denotes
a motor for the rotary drive, which is mounted on a
support 37. 34 denotes a drive pinion for the rotating
ring 35 of the collar bearing. Finally, 36 denotes the
shaft of the steering propeller, which is connected
directly to the rotating part of the collar bearing.
The connecting elements between the individual parts,
such as flanges with bolts, welded seams, etc., are not
shown, since Figure 6 is an outline illustration of a
particularly physically small bearing arrangement. In
this case, the drive motors 33 for the rotary movement
are even arranged completely inside the shaft.
In the example shown in Figures 2 and 3, the flow
reaches the steering propellers 13, 14, 18 and 19
freely. This is important especially for particularly
low-vibration operation, although flow guide bodies can
also be arranged upstream of the steering propellers,
being designed in particular in the form of hooks with
the hook tip at the same level as the shafts of the
steering propellers. This results in the ship moving
straight ahead particularly well, a possible
improvement in the propulsion efficiency, and a
possible improvement in the downstream flow behavior of
the ship's stern. However, in this case, the tendency
of the drive system to vibrate must be optimized with
respect to the advantages achieved, so that these flow
guide bodies are more appropriate for roro ferries, and
are less suitable for ropax ferries or for cruise
ships. The optimization is in each case dependent on
the ship type, speed and field of use. With appropriate
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optimization, all the ship types can advantageously be
equipped with flow guide bodies
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arranged in front of the steering propellers and having
a roughly droplet-shaped cross section. The flow guide
bodies admittedly increase the wetted surface area, but
their advantages for the ship behavior, the downstream
drag and the propulsion efficiency may, however, more
than compensate for this disadvantage. It is
particularly advantageous to combine them (not shown)
with the physically small, possibly short, steering
propellers according to the invention, since this
allows the additional wetted area to be kept small.
