U.S. patent application number 09/828887 was filed with the patent office on 2002-01-17 for thruster.
Invention is credited to Duncan, Ian James.
Application Number | 20020005156 09/828887 |
Document ID | / |
Family ID | 9889569 |
Filed Date | 2002-01-17 |
United States Patent
Application |
20020005156 |
Kind Code |
A1 |
Duncan, Ian James |
January 17, 2002 |
Thruster
Abstract
A thruster is adapted to be laterally mounted through the hull
of the vessel and has propulsive ducts for opening to respective
sides of the vessel and an inlet to the inboard end of both of the
ducts, the inlet being at least partially provided by a tunnel
having an internal cross-sectional area greater than that of the
ducts, the tunnel at least partially surrounding each of the ducts
and opening to each side of the vessel.
Inventors: |
Duncan, Ian James;
(Blackburn, GB) |
Correspondence
Address: |
Ronald L. Grudziecki
BURNS, DOANE, SWECKER & MATHIS, L.L.P.
P.O. Box 1404
Alexandria
VA
22313-1404
US
|
Family ID: |
9889569 |
Appl. No.: |
09/828887 |
Filed: |
April 10, 2001 |
Current U.S.
Class: |
114/151 |
Current CPC
Class: |
B63H 2023/0216 20130101;
B63H 25/42 20130101 |
Class at
Publication: |
114/151 |
International
Class: |
B63H 025/46 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 10, 2000 |
GB |
0008763.5 |
Claims
I claim:
1. A thruster for lateral propulsion of a waterborne vessel having
a hull with two sides wherein said thruster is to be laterally
mounted through the hull of the vessel, said thruster having
propulsive ducts each having an inboard and an outboard end, said
outboard end for opening to respective sides of the vessel, and an
inlet to the inboard end of both of the ducts wherein said inlet is
at least partially provided by a tunnel having an internal
cross-sectional area greater than that of the ducts, said tunnel at
least partially surrounds each of the ducts, the tunnel for opening
to each side of the vessel.
2. A thruster according to claim I wherein said ducts are entirely
contained within said tunnel.
3. A thruster according to claim 1 wherein said tunnel is
cylindrical and said ducts are co-axial with said tunnel.
4. A thruster according to claim 1 further including an axial or
mixed flow pump rotor mounted in each of the ducts, said rotors
arranged for driving in respectively opposite lateral
directions.
5. A thruster according to claim 4 wherein drive to both the rotors
comes from a single prime mover to respective unidirectional drives
arranged coaxially with the rotors.
6. A thruster according to claim 5 further comprising a
transmission, the transmission comprising a synchronous driving
belt which drives one or other of the pump rotors by means of
unidirectional roller clutches.
7. A thruster according to claim 5 wherein said prime mover is
reversible.
8. A thruster according to claim 7 wherein said prime mover is a
reversible electric motor.
9. A thruster according to claim 6 wherein said inlet to the
inboard ends to the propulsive ducts are arranged symmetrically
about the drive to the unidirectional drives.
10. A waterborne vessel including a thruster as defined in claim
1.
11. A thruster comprising: at least one propulsive duct having an
inbound end; at least one tunnel at least partially surrounding the
at least one duct; and an axial or mixed flow pump rotor mounted in
the at least one duct, the rotor adapted for driving in opposite
lateral directions.
Description
FIELD OF THE INVENTION
[0001] The invention relates to thrusters, which are systems for
the lateral propulsion of waterborne vessels. More particularly,
the invention relates to thrusters that are permanently installed
in the vessel, as either original equipment or post-fitted, and
which may be found at the bow or the stern of the vessel, most
usually at the bow.
BACKGROUND OF THE INVENTION
[0002] Such thrusters are very well-known and for the most part can
be regarded as a ducted fan of which the propulsive duct is mounted
transversely through the hull of the vessel so as to open into the
water at each side of it. There may be a single or a double pump
rotor in the duct which may be reversible.
[0003] However, as far as we are aware, all such thrusters have
penetrated the hull only by the duct containing the pump rotor, and
have been constructed in the usual way for a ducted fan, namely
with the rotor occupying as far as practicable the complete
cross-sectional area of the duct.
SUMMARY OF THE INVENTION
[0004] By contrast, according to the present invention a thruster
for mounting laterally through the hull of a waterborne vessel has
propulsive ducts for opening to respective sides of the vessel and
an inlet to the inboard end of both of the ducts. The inlets, being
at least partially provided by a tunnel which at least partially
surrounds each of the ducts and, like the ducts, are for opening to
each side of the vessel. The tunnels having an internal
cross-sectional area greater than that of the ducts.
[0005] An axial or mixed flow pump rotor is mounted in each of the
ducts and arranged for driving in respectively opposite lateral
directions. Preferably, drive to both of the rotors comes from a
single prime mover to respective unidirectional drives arranged
coaxially with the rotors. The prime mover is preferably
reversible. Inboard inlets to the propulsive ducts are preferably
arranged symmetrically about the drive to the unidirectional
drives.
[0006] The propulsive ducts may be entirely contained within the
tunnel and may be coaxial with such a cylindrical tunnel or be off
center of it. The tunnel need not necessarily be circular in
outline in its internal cross-section, and its outboard ends may be
flared to conform to the vessel where it penetrates the vessel
hull.
[0007] A preferred prime mover is a reversible electric motor, and
a preferred transmission format is a synchronous driving belt which
drives one or other of the pump rotors by means of unidirectional
roller clutches.
[0008] The invention further includes a waterborne vessel equipped
with such a thruster.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Particular embodiments of the invention will now be
described with reference to the accompanying drawings, wherein:
[0010] FIG. 1 is a partial cutaway view of a thruster arrangement
according to one embodiment of the present invention; and
[0011] FIG. 2 is a perspective view showing ceratin details of the
construction of a propeller drive according to the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0012] Looking first at FIG. 1, a tunnel 1 of diameter D is for
positioning laterally through the hull of a waterborne vessel so
that its ends 2, 3 are respectively open to the water at the
lateral sides of the vessel.
[0013] The ends 2 and 3 of the tunnel wall are flared or othewise
shaped so as to be faired to the hull so as to reduce water
resistance and inlet losses when the vessel is proceeding
normally.
[0014] Alternatively, ends of the tunnel may comprise separate
mouldings, adapted for a particular vessel or type of vessel and to
be joined to a plain tunnel upon installation. As will become
evident, the tunnel need not be of circular cross-section but can
be any convenient shape conformable to the structure of the vessel,
and in particular of its bulkheads, to which it is fitted, or
intended to be fitted.
[0015] At its central portion the tunnel is flared outwardly at 4
to provide lateral support for a casing 5 and to provide increased
flow area.
[0016] This casing 5 has at one end a housing 6 for a reversible
electric motor and at the other surrounds a drive assembly for the
thruster.
[0017] The thruster has two cylindrical propulsion ducts 7 and 8
which are of diameter d, which have inboard ends 9, 10 disposed
laterally symmetrically on each side of the casing 5, and outboard
ends 11, 12 which are sharp edged and lie just within ends 2 and 3
of the tunnel.
[0018] Propulsion within the ducts is provided by respective
propeller assemblies 13, 14 which are to drive in the respective
outboard direction by means of an inboard rotor 15, 16 acting with
an outboard stator 17, 18.
[0019] The drive structure is seen in more detail in FIG. 2, where
a toothed pulley 20 driven by a synchronized belt from a like
pulley on the drive shaft of the motor in the casing 6, the
sychronized belt being contained within casing 5.
[0020] At each outboard side of the pulley 20 are unidirectional
drives 21 and 22 which are roller clutches set to drive in opposite
directions of rotation. Further details of construction are shown
only in respect of one side of the assembly but are identical in
mirror image on the other side. The unidirectional drive 21 drives
a rotor shaft 23 on a hub 24 of which the propeller rotor 15 is
mounted, thrust from the rotor being taken also on a needle roller
thrust race 25.
[0021] A PTFE ring 26 takes any reverse thrust which may occur when
the pump rotor 15 is idling and also locates the toothed pulley 20.
The shaft 23 is sealed by means of twin radial seals 28 at its
outboard end and by a V-seal 27 at its inboard end.
[0022] In operation, the motor is driven in a sense of rotation
appropriate for transmission of drive either to rotor 15 or to
rotor 16. Assuming rotor 15 to be driven, a jet of water will be
propelled through duct 7 as shown by arrows X; rotor 16 will
free-wheel in a partial inflow of water shown by arrows Y. However,
there will also be inflow of water through the free area of the
tunnel 1, as shown by arrows Z, and these flows will all be
available as an inlet flow to the inboard end 9 of the tunnel 7.
Hence, one has a propulsive column of water shown by arrows X of
which the output velocity is greater than an input velocity of
water whether contributed by arrows Y or arrows Z. In exactly the
same way, if rotor 16 is driven lateral propulsion in the opposite
direction will be assured by a propulsive jet of water of arrows Y
(now reversed in direction) with input from arrows Z through the
free area of the tunnel and through duct 7 by arrows X (now
reversed).
[0023] The relationship between the cross-sectional areas of the
propulsive ducts and of the tunnel is not critical. Although
increasing propulsive duct diameter would increase the efficiency
of the rotors and reduce the power needed, an increase in tunnel
cross-section would increase the space required. An example of
diameter d for a 3Kw, 50 Kgf thrust model would be 90 mm and of
diameter D 130 mm. On the other hand, given that the propulsion
duct diameters cannot for that reason be increased greatly the
rotor and stator lengths should be as axial lengths should be as
great as possible to reduce cavitation effects and for example as
shown the dimension W from end to end of the two propellers is 330
mm with a lateral dimension A for the casing of 30 mm.
[0024] While the present invention has been described by reference
to the above-mentioned embodiments, certain modifications and
variations will be evident to those of ordinary skill in the art.
Therefore, the present invention is to limited only by the scope
and spirit of the appended claims.
* * * * *