U.S. patent application number 10/515161 was filed with the patent office on 2005-07-28 for marine vessel propulsion arrangement and method of operating a marine vessel propulsion arrangement.
Invention is credited to Levander, Oskar.
Application Number | 20050164574 10/515161 |
Document ID | / |
Family ID | 8564001 |
Filed Date | 2005-07-28 |
United States Patent
Application |
20050164574 |
Kind Code |
A1 |
Levander, Oskar |
July 28, 2005 |
Marine vessel propulsion arrangement and method of operating a
marine vessel propulsion arrangement
Abstract
Marine vessel propulsion system comprising engine system (2) for
producing propulsion power and several propulsion means (3, 9) at
its stem section, including a combination of at least two
propulsion arrangements (9) capable of steering action and at least
one shaft driven propeller drive (3) having a controllable pitch
propeller (6), being adjustable to substantially feathering
conditions. The invention relates also to method of operating a
marine vessel propulsion system in which at low speed and/or
harbour manoeuvring operation the shaft driven propeller drive (3)
is adjusted to be feathering and power transmission to the
propeller (6) is stopped.
Inventors: |
Levander, Oskar; (Turku,
FI) |
Correspondence
Address: |
SMITH-HILL AND BEDELL
12670 N W BARNES ROAD
SUITE 104
PORTLAND
OR
97229
|
Family ID: |
8564001 |
Appl. No.: |
10/515161 |
Filed: |
November 19, 2004 |
PCT Filed: |
May 15, 2003 |
PCT NO: |
PCT/FI03/00374 |
Current U.S.
Class: |
440/79 |
Current CPC
Class: |
B63H 23/30 20130101;
B63H 5/125 20130101; B63H 2005/1258 20130101; B63H 5/08 20130101;
B63H 3/00 20130101 |
Class at
Publication: |
440/079 |
International
Class: |
B63H 005/07 |
Foreign Application Data
Date |
Code |
Application Number |
May 24, 2002 |
FI |
20020981 |
Claims
1-13. (canceled)
14. Marine vessel propulsion system comprising engine system for
producing propulsion power and several propulsion means at its
stern section, characterized by combination of at least two
propulsion arrangements capable of steering action and at least one
shaft driven propeller drive having a controllable pitch propeller,
being adjustable to substantially feathering conditions.
15. Marine vessel propulsion system according to claim 14,
characterized in that the at least two propulsion arrangements
capable of steering are azimuthing propulsion arrangements.
16. Marine vessel propulsion system according to claim 15,
characterized in that the azimuthing propulsion arrangements are
provided with constant pitch propeller systems and/or variable
pitch propeller systems.
17. Marine vessel propulsion system according to claim 15,
characterized in that the azimuthing propulsion arrangements are
powered by electric motor, the power to which being supplied by
piston engine generator set and that the shaft driven propeller
drive is mechanically connected to a piston engine.
18. Marine vessel propulsion system according to claim 15,
characterized in that the propulsion system is arranged to be
driven at different operation modes, when at normal/cruise speed
operation mode both the at least two azimuthing propulsion
arrangements and the at the least one shaft driven propeller drive
are adapted to at least cause thrust in order to move the vessel,
and at low speed/maneuvering operation mode only the at least two
azimuthing propulsion arrangements are adapted to cause thrust in
order to move the vessel.
19. Marine vessel propulsion system according to claim 14,
characterized in that pitch angle of blades in the propeller of the
shaft driven propeller drive is adjustable to be either
+80.degree.-100.degree. or -80.degree.-100.degree..
20. Marine vessel propulsion system according to claim 14,
characterized in that the engine system comprises a coupling means
connecting the propeller drive shaft to an engine and being
shiftable to disengaged position.
21. Method of operating a marine vessel propulsion system
comprising at its stern section at least two propulsion
arrangements capable of steering action and at least one shaft
driven propeller drive having a controllable pitch propeller,
wherein at normal/cruise speed the propulsion thrust is provided by
the shaft driven propeller drive and said propulsion arrangements
capable of steering action and steering thrust is provided by the
propulsion arrangements capable of steering action, and the thrust
of the shaft driven propeller drive is mainly adjusted by adjusting
pitch angle of the propeller, characterized in that at low speed
and/or harbor maneuvering operation the shaft driven propeller
drive is adjusted to be feathering and that power transmission to
the propeller is stopped.
22. Method of operating a marine vessel propulsion system according
to claim 21, characterized in that power transmission to the shaft
driven propeller drive is stopped by disengaging the engine from
the shaft of the shaft driven propeller drive.
23. Method of operating a marine vessel propulsion system according
to claim 21, characterized in that power transmission to the shaft
driven propeller drive is stopped by stopping the engine.
24. Method of operating a marine vessel propulsion system according
to claim 21, characterized in that while the power supply to the
propeller drive is stopped from the engine system, the at least two
propulsion arrangements capable of steering action are maintained
in operation.
25. Method of operating a marine vessel propulsion system according
to claim 21, characterized in that at low speed and/or maneuvering
operation the pitch angle of propeller of the shaft driven
propeller means is adjusted to be advantageously either
+80-100.degree. or -80-100.degree..
26. Method of operating a marine vessel propulsion system according
to claim 21, wherein the at least two propulsion arrangements
capable of steering action are powered by electric motors, the
power to which being supplied by one or more piston engine
generator sets, characterized in that at low speed and/or harbor
maneuvering operation piston engines of the piston engine generator
sets are operated at greater speed than idle speed, substantially
at their most efficient constant speed substantially independently
from the power consumption of said propulsion arrangements.
Description
[0001] The invention relates to marine vessel propulsion system
according to the preamble of claim 1. The invention relates also to
method of operating a marine vessel propulsion system according to
the preamble of claim 8.
[0002] The general aims, just to mention a few, of designing
propulsion system to a marine vessel are good efficiency,
reliability, durability and good low speed manoeuvring
capabilities. Emphasis of the features is depending on an
application in question.
[0003] For example, in so called ROPAX (Roll On/Roll Off Passenger)
vessels there is a need to provide a propulsion system, which is
simultaneously efficient at cruise speeds, say over 25 knots, and
which also provides for good harbour manoeuvring capabilities.
[0004] It has been suggested to use azimuthing propulsion drives,
such as so called pod drives, instead of conventional mechanical
shaft propulsion. A reference is made to a publication EP 590867,
in which a propulsion arrangement is shown, which consists of a
turnable drive unit, inside which there is an electrical motor
acting as the ship's propulsion motor and being connected to a
propeller at the end of the drive unit. The pod drives are
favourable in a sense that they are flexible having azimuthing
control possibility, and they also provide freedom in location of
main engines. However, the pod drives are of high cost and the
electric power transmission cause considerable transmission
losses.
[0005] Mechanical propeller drive as such has clear advantages
being of low cost, simple and having substantially low power
transmission losses. However, mechanical propeller has
disadvantages as well. Propulsion efficiency is not as good as
desired and particularly at low speed conditions there is a risk
for pressure side cavitation when controllable pitch propeller is
used. This occurrence is caused when driving the propeller at low
pitch, high rotational speed conditions resulting in decreasing of
local pressure at the surface of the propeller blade. Also
manoeuvrability is substantially poor.
[0006] A combination of pod drives and mechanical propeller drive
in general level as such has been suggested in a paper
"Hydrodynamics of fast ropax vessel" by Raimo Hmlinen. The
suggested combination has been considered to have several benefits.
However, it has been found that the solution does not result in
optimum solution as such, particularly at low speed/manoeuvring
operation. Although the proposal in general seems to be promising,
there are still practical issues to be solved.
[0007] It is an object of the invention to provide marine vessel
propulsion system and method of operating a marine vessel
propulsion system in which the shortcomings of the prior art have
been minimised. Particularly it is an object of the invention to
provide a marine vessel hybrid propulsion system and method of
operating a marine vessel propulsion system, which result in good
overall and particularly low speed/manoeuvring operation efficiency
and operation, and also reduced propulsion vibration and noise
level.
[0008] Objects of the invention are met substantially as is
disclosed in the claim 1, 8 and as is more clearly disclosed in the
other claims.
[0009] According to a preferred embodiment of the invention, the
objects of the invention are met by marine vessel propulsion
system, which comprises engine system for producing propulsion
power and several propulsion means at its stern section, including
a combination of at least two propulsion arrangements capable of
steering action and at least one shaft driven propeller drive
having a controllable pitch propeller, and being adjustable to
substantially feathering conditions.
[0010] According to a preferred embodiment of the invention the at
least two propulsion arrangements capable of steering are
azimuthing propulsion arrangements, which may be provided with
either variable or constant pitch propeller systems. The azimuthing
propulsion arrangements are preferably powered by electric motor,
the power to which being supplied by piston engine generator set.
The shaft driven propeller drive is mechanically connected to a
piston engine by means of a gear system or alike. In some cases
also water jet propulsion systems may be used as propulsion
arrangements capable of steering.
[0011] The propulsion system according to invention is arranged to
be driven differently at different operation modes, namely
specifically at normal/cruise speed operation mode and at low
speed/harbour manoeuvring operation mode. At normal/cruise speed
operation mode both the at least two azimuthing propulsion
arrangements and the at least one shaft driven propeller drive are
adapted to at least cause thrust in order to move the vessel. At
low speed/harbour manoeuvring operation mode only the at least two
azimuthing propulsion arrangements are adapted to cause thrust in
order to move the vessel. This way the manoeuvring behaviour is
more advantageous. The steering of the vessel is accomplished
always by means of the at least two propulsion arrangements capable
of steering action i.e. the azimuthing propulsion arrangements.
[0012] The pitch angle of blades in the propeller of shaft driven
propeller drive is adjustable to be at angle
.+-.80.degree.-100.degree. in respect of the normal of the shaft of
the shaft driven propeller drive. This means in practise that the
blades of the propeller are rotated to either direction until they
are substantially parallel to longitudinal axis of the vessel. The
direction of rotation may be selected according to the shape of the
blades so that the flow resistance is minimised. Preferably the
engine system comprises a gear and a coupling means connecting the
propeller drive shaft to an engine and being shiftable to
disengaged position. This result in a benefit of stopping the
transmission of power to the drive shaft before and while the
propeller is at feathering conditions. Providing the propeller
drive with coupling means also results in a possibility of keeping
the engine running while the power transmission is disengaged.
However, it is advantageous to stop the engine e.g. in order to
reduce unnecessary emissions.
[0013] According to the method of operating a marine vessel
propulsion system comprising at its stern section at least two
propulsion arrangements capable of steering action and at least one
shaft driven propeller drive having a controllable pitch propeller,
at normal/cruise speed the propulsion thrust is provided by the
shaft driven propeller drive and the propulsion arrangements
capable of steering action. Steering thrust is provided by the
propulsion arrangements capable of steering action, and the thrust
of the shaft driven propeller drive is mainly adjusted by adjusting
pitch angle of propeller. Further at low speed and/or harbour
manoeuvring operation the shaft driven propeller drive is adjusted
to be feathering and that power transmission to the propeller is
stopped. This is accomplished by adjusting the pitch angle of the
shaft driven propeller.
[0014] While the power supply to the propeller drive is stopped
from the engine system, the at least two propulsion arrangements
capable of steering action are maintained in operation. Power
transmission to the shaft driven propeller drive is stopped by
disengaging the engine from the shaft of the shaft driven propeller
drive, or in case of single engine without a gear system, by
stopping the engine before adjusting the propeller to be
feathering.
[0015] The pitch angle of propeller of the shaft driven propeller
drive is adjusted to be advantageously either +80-100.degree. or
-80-100.degree.. The at least two propulsion arrangements capable
of steering action are preferably powered by electric motors, the
power to which being supplied by one or more piston engine
generator sets. During low speed and/or harbour manoeuvring
operation piston engines of the piston engine generator sets are
operated at greater speed than idle speed, substantially at their
most efficient constant speed, and preferably substantially
independently from the power consumption of said propulsion
arrangements. This manner the engines may run at optimum
circumstances regardless of the power demand and prevailing speed
of the vessel.
[0016] The invention provides several advantages over prior art.
First of all the propulsion system causes lower investment costs
compared to conventional diesel-electric propulsion system. It also
provides excellent manoeuvring characteristics as well as excellent
propulsion efficiency for high speed ships. With the present
invention, at the low speed/manoeuvring operation the engines may
operate at optimum conditions and there is no risk of cavitation of
the shaft driven propeller drive. Also one of the advantage of the
present invention is that the number of diesel generator sets
connected to the network can be varied according to the load demand
i.e. the engines may be started and stopped. This way the load of
the engine may be kept closer to the optimum.
[0017] In the following the invention will be described by the way
of example, with the reference to the appending drawings in
which
[0018] FIG. 1 shows schematically an embodiment of the propulsion
system according to the invention at normal operation, and
[0019] FIG. 2 shows the propulsion system according to FIG. 1 in
low speed/manoeuvring operation.
[0020] In the figures with the reference number 1 it is referred to
a hull of the vessel, only the stern section of which is shown. The
vessel is provided with engine system 2 having a number of piston
engine generator sets 2.1 and number of piston engines 2.2
mechanically connected to a shaft driven mechanical propeller drive
3. The shaft driven propeller drive 3 comprises a gear and a clutch
4 through which the engines 2.2 are connected to a drive shaft 5 of
the propeller drive 3. At the outer end of the drive shaft 5 there
is a propeller 6 connected thereto. The shaft driven propeller
system drive 3 comprises a controllable pitch propeller 6 and an
arrangement 7 for adjusting its pitch angle A, which is shown
herein very schematically. The arrangement 7 for adjusting the
pitch angle may be hydraulic or mechanically operated commercially
available system known as such. However, the pitch angle adjusting
arrangement 7 is such that the pitch of the propeller is adjustable
to substantially feathering conditions. In practise this means that
the mechanism for turning the propeller blades allows the blades to
turn over to greater angle than in normal pitch adjusting. This
will be described later in more detailed manner with the reference
to FIG. 2.
[0021] The piston engine generator sets 2.1 produce electric power
and supply it to a network 8, through which power may be
transmitted to the propulsion arrangements capable of steering
action, such as pod drive units 9. The pod drive unit 9 is turnable
about its vertical axis as depicted by the arrows in the figures.
This feature is utilised in the present invention so that the pod
units 9 operate as steering devices and the shaft driven propeller
drive 3 is without any rudder system.
[0022] The shaft driven propeller drive 3 is positioned at centre
line of the hull. In case there would be several shaft driven
propeller drives it is desired to position them symmetrically in
respect of the centre line of the hull 1. In the figures the two
propulsion arrangements capable of steering action i.e. the pod
drives 9 are positioned at both sides of the shaft driven propeller
drive 3 and substantially same longitudinal position as the
propeller 6 of the shaft driven propeller drive 3.
[0023] At normal cruise speed conditions the shaft driven propeller
drive 3 and the pod drives 9 are used for producing thrust force
for moving the vessel. The pod drives 9 are provided with variable
speed propeller systems and the thrust force of the pod drives 9 is
adjusted by controlling the rotational speed of their propellers.
The thrust force may also be controlled by controlling propeller
pitch angle, in the case they are provided with controllable pitch
propellers. The thrust force of the shaft driven propeller drive 3
is mainly adjusted by adjusting propeller pitch angle. Naturally,
it is possible to adjust rotational speed by adjusting the engine
speed.
[0024] In such operation in which better manoeuvrability is desired
and the speed is lower, only the pod drives 9 are used for
propulsion. At this mode of operation the pitch angle of the shaft
driven propeller drive is adjusted such that its flow resistance is
substantially decreased. This situation is shown in FIG. 2. This
way the overall efficiency may be increased. Preferably the pitch
angle (A) of the shaft driven propeller drive 3 is adjusted such
that the propeller is feathering. By the term feathering or
feathering conditions it is meant here that the angle (A) of the
blades is positioned so that the chords, straight line between the
leading and the trailing edge of a blade, become approximately
parallel to the water streamline or longitudinal axis of the
vessel. The blade angle (A) means an angle between normal of the
drive shaft axis and a mean direction of straight line joining the
leading and trailing edges of a blade.
[0025] When changing over to the low speed/harbour manoeuvring
operation first the power supply to the shaft driven propeller
drive 3 is stopped, which may be accomplished by shifting the
clutch 4 to disengaged position. After stopping the power
transmission, the propeller of the drive 3 is adjusted to
feathering conditions. In this manner it is possible to obtain
advantageous properties to the propulsion system for low
speed/manoeuvring operation. The pod drives 9 are maintained in
operation in such a manner that the piston engines of the piston
engine generator sets 2.1 are operated at greater speed than idle
speed, substantially at their most efficient constant speed
substantially independently from the power consumption of said
propulsion arrangements 9. This means that the total power
production may be greater than actual demand of the pod drives 9.
It is also advantageous to shut down the engine system 2.2.
According to the invention, in this operation mode the engine
system 2 is operated in most advantageous manner resulting in low
emissions and vibrations to the vessels hull constructions.
[0026] The invention is not limited to the embodiments shown but
several modifications of the invention are reasonable within the
scope of the attached claims.
* * * * *