U.S. patent application number 09/838704 was filed with the patent office on 2001-12-13 for twin-propeller drive for watercraft.
Invention is credited to Kaul, Stefan, Reuter, Reinhold.
Application Number | 20010051475 09/838704 |
Document ID | / |
Family ID | 27438495 |
Filed Date | 2001-12-13 |
United States Patent
Application |
20010051475 |
Kind Code |
A1 |
Reuter, Reinhold ; et
al. |
December 13, 2001 |
Twin-propeller drive for watercraft
Abstract
Dual propeller propulsion system for water crafts having two
propellers (3, 4) fitted in the same axis outside the ends of an
underwater housing (2) configured as a gondola so as to facilitate
flow, said housing being placed under the hull of the water craft
having a driving mechanism lodged in the underwater housing for
both propellers (3, 4) to which the energy coming out for both
propellers (3, 4) to which the energy coming out of the hull of the
water craft is guided by means of a housing shank (18), one of the
ends of which is mounted on the hull (24) of the water craft while
the other is mounted in the underwater housing (2). Said propulsion
system is characterized in that the underwater housing (2) forms
part of a control device (20) by means of which the water jet
coming out with increased energy from the front propeller (3) in
the direction of travel of the water craft is guided with minimal
energy loss and optimal irrotational flow to the back propeller (4)
placed in the other end of the underwater housing in the direction
of travel of the water craft. Both propellers (3, 4) are driven by
the driving mechanism placed in the underwater housing in the same
direction of rotation and are configured in the area of the
respective water jet cross section in such a way that the differing
flow energy entering both propellers (3, 4) is optimally used.
Inventors: |
Reuter, Reinhold; (Schwall,
DE) ; Kaul, Stefan; (Harschbach, DE) |
Correspondence
Address: |
LEVINE & MANDELBAUM
350 FIFTH AVENUE SUITE 7814
EMPIRE STATE BUILDING
NEW YORK
NY
10118
US
|
Family ID: |
27438495 |
Appl. No.: |
09/838704 |
Filed: |
April 19, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09838704 |
Apr 19, 2001 |
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09297715 |
Jun 21, 1999 |
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09297715 |
Jun 21, 1999 |
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PCT/EP97/06207 |
Nov 7, 1997 |
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Current U.S.
Class: |
440/66 |
Current CPC
Class: |
B63H 2005/075 20130101;
B63H 23/24 20130101; B63H 2005/1258 20130101; B63H 23/30 20130101;
B63H 5/10 20130101; B63H 5/125 20130101; B63H 2005/1254 20130101;
B63H 2005/103 20130101; B63H 23/321 20130101 |
Class at
Publication: |
440/66 |
International
Class: |
B63H 001/18 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 7, 1996 |
DE |
296 19 385.2 |
Nov 22, 1996 |
DE |
196 48 417.0 |
Apr 17, 1997 |
DE |
297 07 028.2 |
Claims
What is claimed is:
1. A watercraft drive for a watercraft having a hull, said
watercraft drive comprising, drive means including a motor having
two drive shafts, and front and rear propellers respectively
mounted on said drive shafts in coaxial longitudinally displaced
relationship, each of said propellers having at least two blades,
control means disposed between said front and rear propellers, for
increasing the energy of a jet of water exiting the front propeller
as said jet is transmitted to the rear propeller, said control
means causing the water jet leaving the front propeller with a
contracted cross-section and both circular and axial flow
components to reach the rear propeller substantially without
circular components, said front and rear propellers having equal
diameters and being driven at like rotational velocities, said rear
propeller having a core area conforming with the cross section of
the contracted cross section of the jet leaving the front
propeller, the geometry of the blades of the rear propeller being
optimized for an incoming jet energy substantially equal to the
exit energy of the jet exiting the front propeller, said rear
propeller further having an annular area extending from said core
area to a circular path defined by an outer circumference of the
rear propeller, the geometry of the blades in said annular area
conforming to the geometry of the blades of the front propeller,
said annular area of the rear propeller receiving a flow of
surrounding ambient water, said control means comprising, a hollow
shaft having an upper end connected to said hull, and a lower end,
a gondola-shaped underwater housing mounted on the lower end of
said hollow shaft and containing said drive means, said drive
shafts extending from opposite ends of said housing, and a
plurality of guide blades connected to at least one of said hollow
shaft and gondola-shaped underwater housing, power means mounted in
said hull for transmitting power through said hollow shaft to said
drive means for rotating said front and rear propellers, said motor
having a rotor covered by a motor housing, said motor housing being
connected, in heat conducting relationship to the inside wall of
said underwater housing, whereby heat from said motor is
transferred to water surrounding said shaft and said underwater
housing.
2. A watercraft drive in accordance with claim 1, wherein the pitch
of the blades in the core area of the rear propeller is 1.04 to
1.52 times the pitch of the blades in the core area of the front
propeller.
3. A watercraft drive in accordance with claim 2, wherein the pitch
of the blades in the annular area of the front propeller is between
95 percent and 105 percent of the pitch of the blades in the
annular area of the rear propeller.
4. A watercraft drive in accordance with claim 2 wherein the
pitches of the blades of each of the front and rear propellers is
in the range of 0.9 to 1.6.
5. A watercraft drive in accordance with claim 2 wherein the blades
of the front and rear propellers have different degrees of
arcing.
6. A watercraft drive in accordance with claim 1 wherein said guide
blades which have an arc length ratio in the range of 0.0 to 0.2
and an angle of incidence in the range of -7 to +7.
7. A watercraft drive in accordance with claim 6, wherein the
control device has two guide blades which are angularly
symmetrically disposed about the common axis of rotation of the
front and rear propellers.
8. A watercraft drive in accordance with claim 1 wherein the drive
means further comprises a transmission, said drive shafts extending
from opposite ends thereof, and a connection shaft extending from
said transmission through said hollow shaft into said hull for
connection to an engine disposed therein.
9. A watercraft drive in accordance with claim 1 further comprising
a plurality of electrical conductors extending from said motor
through said hollow shaft into said hull for connection to a source
of electrical power therein.
10. A watercraft drive in accordance with claim 1 wherein said
motor comprises a hydraulic engine operatively connected to
hydraulic fluid lines extending through said hollow shaft into said
hull for connection to a source of hydraulic power.
11. A watercraft drive in accordance with claim 1 further
comprising an accelerating nozzle jacketing the front propeller,
said accelerating nozzle having a cross section which tapers from
an inlet end upstream of the front propeller to a plane of rotation
of the front propeller.
12. A watercraft drive in accordance with claim 1 wherein each of
said front and rear propellers is jacketed by a decelerating nozzle
having a cross section which increases from a respective nozzle
inlet to a plane of rotation of the respective propeller.
13. A watercraft drive in accordance with claim 1, wherein the
upper end of the hollow shaft is rotatably mounted on the hull for
enabling rotation of the underwater housing relative to the
hull.
14. A watercraft drive in accordance with claim 13, wherein the
hollow shaft is rotatable about a longitudinal axis relative to the
hull by 360 degrees.
15. A watercraft drive in accordance with claim 1 further
comprising a front hub for fastening the front propeller to its
respective drive shaft and a rear hub for fastening the rear
propeller to its respective drive shaft, the front hub and rear hub
being contoured for enhancing flow from the front propeller to the
rear propeller.
16. A watercraft drive in accordance with claim 1 wherein the motor
is a permanently excited synchronous electric motor.
17. A watercraft drive in accordance with claim 16 further
comprising clutch means for connecting said driving shafts to said
rotor, said driving shafts passing concentrically through the rotor
and extending from both ends of the rotor for receiving the
propellers which rotate in unison with said driving shaft.
18. A watercraft drive in accordance with claim 17 further
comprising bearing means operatively mounted between said housing
and said rotor.
19. A watercraft drive in accordance with claim 1 further
comprising rotor support tube means for coupling said drive shaft
and said rotor.
20. A watercraft drive in accordance with claim 17 wherein the axis
of the hollow shaft intersects and is orthogonal to the axis of the
drive shaft, and further comprising a carrier cone to which the
upper end of the hollow shaft is connected, the housing being
continuously pivotable by 360 degrees around the longitudinal axis
of the hollow shaft.
21. A watercraft drive in accordance with claim 20, wherein the
hollow shaft and the carrier cone are mutually detachably connected
in a plane of the hull.
22. A watercraft drive in accordance with claim 20 wherein the
carrier cone has a large end and a small end having a smaller cross
section than said large end, the hollow shaft being connected to
the small end of the carrier cone and the large end of the carrier
cone being connected to the watercraft within the hull.
23. A watercraft drive in accordance with claim 7 wherein the
hollow shaft comprises one of said guide blades which are
rotationally symmetrical disposed about the common axis of rotation
of the front and rear propellers.
24. A watercraft drive in accordance with claim 1 wherein the front
propeller is jacketed by a decelerating nozzle having an inlet and
a cross section which increases from the inlet to the plane of
rotation of the propeller.
25. A watercraft drive in accordance with claim 1 wherein each of
the front and rear propeller is jacketed by one of an accelerating
nozzle having an inlet and a cross section that decreases with
distance from its inlet to the plane of rotation of its respective
propeller, and a decelerating nozzle having an inlet and a cross
section that increases from its inlet to the plane of rotation of
its respective propeller.
26. A watercraft drive in accordance with claim 1 wherein each of
the front and rear propellers is surrounded either one of an
accelerating nozzle having an inlet and a cross section decreasing
with distance from the inlet of the nozzle toward the plane of
rotation of the first propeller, and a decelerating nozzle having a
cross section increasing with distance from the inlet of the nozzle
toward the plane of rotation of the first propeller.
27. A watercraft drive in accordance with claim 1 wherein said
motor is an electric motor having a rotor and a stator and further
comprising, a first support tube connected in heat conducting
relationship to said rotor, a second support tube having an inner
surface connected in heat conducting relationship to said stator
and an outer surface connected in heat conducting relationship to
said underwater housing, means for connecting said shafts to said
first support tube, a plurality of flanges connected in heat
conducting relationship to said underwater housing, and bearing
means operatively connected between said first support tube and
said flanges, whereby heat from said rotor and stator is conducted
to ambient water surrounding said underwater housing and shaft for
cooling said motor.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention pertains to a hydrojet with a drive
unit and a twin propeller, which is driven by the drive unit.
[0002] Such drives have been known with a design wherein the drive
unit proper, for example a diesel engine, is arranged within the
hull and a transmission, being another part of the drive unit, is
located in a gondola under the hull, from which shafts are led out
at mutually opposite ends, the shafts being connected to the
transmission and, at their outer ends, to one of two propellers
shown as identical propellers, rotating in unison with them. Such a
solution is described in DE 44 40 738 A1, in which an essential
feature is a control device, which is arranged between the two
propellers and eliminates the twist in the water after it leaves
the propeller that is the front propeller in the direction of
travel, so that this water flows to the propeller that is the rear
propeller in the direction of travel with a higher energy, but
likewise without twist, as it does to the front propeller. The
control device is formed by guide blades and a shaft, which
connects gondola or the underwater housing to the hull. Such a
drive is also described with some additional information in THE
MOTORSHIP, October 1996, pp. 47, 48: "Double the props: half the
problem." This additional information includes the statement that
the underwater housing or the gondola is optimized in terms of
flow, without offering further details on what this specifically
means. At any rate, it appears from the overall context that the
gondola with its design that is favorable in terms of flow is the
carrier of the control device, but it is not part of the control
device, which means that no statements are made from which an
action of the gondola that would functionally support the control
device could be inferred. Also, despite the relatively detailed
explanation of the drive, no data are presented on the design of
the blades of the propeller that is the second propeller in the
direction of flow in the sense of the present invention. Thus, the
additional data show only that equal propeller size of an
additional for improving the effect is possible by a special
geometry having been developed for the rear propeller, but what
this special geometry is characterized by is not indicated. Drives
of this class have also been known in a such a design in which the
entire drive is located in the aforementioned gondola. The suitable
drive unit in this solution is an electric motor for the propellers
at both ends of the gondola, to which electricity is supplied from
a power generating unit, which is accommodated in the hull. Such a
solution is described in EP 0 590 867 A1.
[0003] A shaft is surrounded by a jacket tube between the drive
motor within the hull and its transmission in the gondola in the
drive according to the first design, and the electric lines between
the power generating unit within the hull and the electric motor in
the gondola are surrounded by a jacket tube in the drive according
to the second design. This jacket tube is the above-mentioned
shaft, which forms the control device together with guide blades.
If the jacket tube is associated with the hull rotatably around its
longitudinal axis at its top end and nonrotatably carries the
gondola at its lower end, it can be associated with a motor
operator, which is able to forcibly rotate the jacket tube with the
gondola and the propellers associated with the gondola around the
longitudinal axis of the jacket tube, so that the direction of
discharge from the rear propeller into the free water changes and a
rudder twin propeller unit is obtained. In addition, the jacket
tube is designed as part of the guide baffles in the first
embodiment.
SUMMARY OF THE INVENTION
[0004] Against this and other state of the art, which does not,
however, offer any further aspects in respect to the present
invention, the object of the present invention is to optimize a
ship drive such that an efficiency that is optimal according to the
current state of knowledge is obtained, and the design and
manufacturing technical efforts do not substantially exceed what is
associated with the state of the art.
[0005] This object is accomplished according to the present
invention by the combination of individual, appropriately selected
individual problem solutions, not only to add up but to potentiate
the individual advantages into an overall concept that is optimal
in its entirety.
[0006] Consequently, the ship drive according to the present
invention pertains to a hydrojet with two propellers led out of a
gondola outside the hull at its ends, with a drive arranged in the
gondola, to which drive energy is supplied from the hull through a
jacket tube, one end of which is associated with the hull, and the
other end of which is associated with the gondola, wherein the
jacket tube is part of a control device, by which the water jet
leaving the propeller that is the front propeller in the direction
of travel with enriched flow energy at one end of the shaft and of
the gondola is made twist-free in order to feed the water jet
leaving the front propeller with high energy but with low twist to
the propeller that is the rear propeller in the direction of travel
of the watercraft, for which purpose both propellers are driven by
the drive in the gondola in the same direction of rotation and have
essentially the same design in the area of the jet cross section.
In the ship drive of this class, the underwater housing or the
gondola has an optimized shape, and the propeller that is the rear
propeller of the two propellers in the direction of travel of the
watercraft has a special geometry according to Motorship, Vol. 77,
No. 915, October 1996, London, pp. 47, 48: "Double the props: half
the problem."
[0007] In the drive according to the present invention, the two
propellers have essentially the same diameter, so that the
propeller that is the front propeller in the direction of travel of
the watercraft and the propeller that is the rear propeller in the
direction of travel of the watercraft both have different blade
configurations in the entire diameter range and in the diameter
range that is determined by the contraction of the jet as it leaves
the front propeller, respectively, while the propeller that is the
front propeller in the direction of travel of the watercraft and
the propeller that is the rear propeller in the direction of travel
of the watercraft have the same blade configuration in an annular
area located outside the diameter range determined by the jet
contraction.
[0008] These and other features of the present invention appear
from the following description of a plurality of exemplary
embodiments of the present invention, the exemplary embodiments of
the present invention shown in the drawings, and, finally, from the
subclaims.
DESCRIPTION OF THE DRAWINGS
[0009] In the drawings,
[0010] FIG. 1 shows a first exemplary embodiment of a hydrojet
according to the present invention with one propeller each at the
ends of a shaft led out of a gondola-like underwater housing, which
has a favorable design with respect to flow, is arranged by means
of a housing shaft or foot on the underside of a ship under the
ship and accommodates an electric motor, on the shaft or ends of
which a propeller each is arranged;
[0011] FIG. 2 shows a second exemplary embodiment of another design
that is advantageous compared with FIG. 1;
[0012] FIG. 3 shows a third exemplary embodiment, in which a
right-angle gear drive, into which drive energy is supplied via a
shafting accommodated in a jacket tube or housing shaft from a
drive motor, which is arranged inboard and is not shown but may be
a usual internal combustion engine, an electric motor or the like,
is arranged in the underwater housing;
[0013] FIG. 4 through FIG. 6 show, in representations which
correspond to be above representations, three variants of an
additional exemplary embodiment with an electric motor in the
underwater housing, to which energy is supplied from an inboard
power generator via cables, which are led through the housing
shaft; and
[0014] FIG. 7 shows a twin-propeller design, which is particularly
advantageous and is a twin-propeller arrangement which is
especially the subject of the present invention and may be used in
all the above-mentioned embodiments.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] Description of the Embodiment According to FIG. 1
[0016] The drive comprises essentially an electric motor 1.sup. in
a housing 2.sup. outside and especially under the hull and two
propellers, 3.sup., 4.sup., which are driven by the electric motor
1.sup.. The two propellers are usually of different designs, even
though they may have tip circles 5.sup. of equal diameter as well
as a similar wing geometry. They have the same direction of
rotation and the same speed of rotation and the flow is directed
toward them in the same direction, e.g., according to arrow
A.sup..
[0017] The electric motor 1.sup. is arranged in the underwater
housing 2.sup. in a watertight manner. The driven shaft 7.sup. is
led out of it on both sides and the shaft is mounted in it
rotatably in one of two bearings 8.sup., 9.sup. of the housing
2.sup. to the side of the motor. Seals 10.sup., 11.sup. to the side
of the bearings 8.sup., 9.sup. between the shaft 7.sup. and the
front-side housing walls 2a.sup., 2b.sup. are used for sealing in
conjunction with the front surfaces being designed as parts of
labyrinth seals. Shaft ends 12.sup., 13.sup., each of which carries
one of the two propellers 3.sup., 4.sup., rotating in unison, are
flanged on the shaft 7.sup. outside the housing 2.sup.. On the
front side, the housing 2.sup. is joined by hub caps 14.sup.,
15.sup., wherein a continuous outer contour with head 14.sup.,
which said contour is favorable in terms of flow, is formed in the
area of the front propeller 3.sup., the middle part in the form of
the housing 2.sup. and the end part 15.sup. in the area of the rear
propeller 4.sup.. The front walls 14a.sup., 15a.sup. of the hub
caps 14.sup., 15.sup. facing the housing 2.sup. are second parts of
the labyrinth seals 16.sup., 17.sup., whose first parts are the
aforementioned front surfaces 2a.sup., 2b.sup.. The housing 2.sup.
is held at the hull with a foot 18.sup., which is designed as a
hollow foot, whose outer contour is part of the control device
19.sup. between the propellers 3.sup., 4.sup., which has additional
blades associated with the housing 2.sup., of which one blade,
which is located diametrically opposite the foot 18.sup., is
designated by 20.sup.. On the whole, the blades of the control
device 19.sup. are rigidly associated with the housing 2.sup.,
distributed uniformly around the longitudinal axis of the shaft
7.sup..
[0018] On the whole, the propellers 37.sup., 4.sup. are designed
such that the output energy level of the second propeller 4.sup. is
approximately equal to the final energy level of the first
propeller 3.sup. and, in conjunction with the control device
19.sup., the output twist of the first propeller 3.sup. as well as
the input twist of the second propeller 4.sup. are influenced
corresponding to the purpose such that only slight energy losses
occur at best at the time of the transition of the liquid from the
first propeller to the second one.
[0019] The energy is supplied to the electric motor by lines
21.sup., which are led to the motor in the foot 18.sup. and in the
housing 2.sup., and the inner spaces of the foot 18.sup. and of the
housing 2.sup. are therefore in connection with one another.
[0020] To make it possible to use the drive not only to generate a
thrust in the longitudinal direction of the ship (longitudinal axis
of the drive shaft), but also to steer the ship, the entire drive
is pivotable around the vertical longitudinal axis 22.sup. in the
middle between the two propellers, optionally all around by
360.degree. due to the corresponding association with the ship and
by means of an appropriate pivoting mechanism in the known manner,
the axis 22.sup. being directed at right angles to the axis of
rotation of the longitudinal axis 23.sup. of the shaft.
[0021] Description of the Embodiment According to FIG. 2
[0022] The drive comprises essentially an electric motor
1.sup..cndot..cndot. in a housing 2.sup..cndot..cndot. outside and
especially under the hull and two propellers 3.sup..cndot..cndot.,
4.sup..cndot..cndot., which are driven by the electric motor
1.sup..cndot..cndot.. The two propellers usually have different
designs, even though they may have tip circles 5.sup..cndot..cndot.
of equal diameter as well as similar wing geometry. They have the
same direction of rotation and the same speed of rotation and the
flow is directed toward them in the same direction, e.g., according
to the arrow A.sup..cndot..cndot..
[0023] The electric motor 1.sup..cndot..cndot. is arranged in the
underwater housing 2.sup..cndot..cndot. in a watertight manner. The
driven shaft 7.sup..cndot..cndot. is led out of it on both sides
and is mounted in it rotatably in one of two bearings
8.sup..cndot..cndot., 9.sup..cndot..cndot. each of the housing
2.sup..cndot..cndot. to the side of the motor. Seals
10.sup..cndot..cndot.. 11.sup..cndot..cndot. to the side of the
bearings 8.sup..cndot..cndot., 9.sup..cndot..cndot. between the
shaft 7.sup..cndot..cndot. and the front-side housing walls
2a.sup..cndot..cndot., 2b.sup..cndot..cndot. are used for sealing
in conjunction with the front surfaces being designed as parts of
labyrinth seals. Shaft ends 12.sup..cndot..cndot.,
13.sup..cndot..cndot., each of which carries one of the two
propellers 3.sup..cndot..cndot., 4.sup..cndot..cndot., rotating in
unison, are flanged to the shaft 7.sup..cndot..cndot. outside the
housing 2.sup..cndot..cndot.. On the front side, the housing
2.sup..cndot..cndot. is joined by hub caps 14.sup..cndot..cndot.,
15.sup..cndot..cndot., wherein a continuous outer contour with head
14.sup..cndot..cndot., which contour is favorable with respect to
flow, is formed in the area of the front propeller
3.sup..cndot..cndot., the middle part in the form of the housing
2.sup..cndot..cndot. and the end part 15.sup..cndot..cndot. in the
area of the rear propeller 4.sup..cndot..cndot.. The front walls
14a.sup..cndot..cndot., 15a.sup..cndot..cndot. of the hub caps
14.sup..cndot..cndot., 15.sup..cndot..cndot. facing the housing
2.sup..cndot..cndot. are two parts of the labyrinth seals
16.sup..cndot..cndot., 17.sup..cndot..cndot., whose first parts are
the aforementioned front surfaces 2a.sup..cndot..cndot.,
2b.sup..cndot..cndot.. The housing 2.sup..cndot..cndot. is held at
the hull with a foot 18.sup..cndot..cndot., which is designed as a
hollow foot, whose outer contour is part of the control device
19.sup..cndot..cndot. between the propellers 3.sup..cndot..cndot.,
4.sup..cndot..cndot., which has additional blades associated with
the housing 2.sup..cndot..cndot., of which one blade, which is
located diametrically opposite the foot 18.sup..cndot..cndot., is
designated by 20.sup..cndot..cndot.. On the whole, the blades of
the control device 19.sup..cndot..cndot. are rigidly associated
with the housing 2.sup..cndot..cndot., uniformly distributed around
the longitudinal axis of the shaft 7.sup..cndot..cndot..
[0024] On the whole, the propellers 3.sup..cndot..cndot.,
4.sup..cndot..cndot. are designed such that the output energy level
of the second propeller 4.sup..cndot..cndot. is approximately equal
to the final energy level of the first propeller
3.sup..cndot..cndot. and, in conjunction with the control device
19.sup..cndot..cndot., the output twist of the first propeller
3.sup..cndot..cndot. as well as the input twist of the second
propeller 4.sup..cndot..cndot. are influenced corresponding to the
purpose such that only slight energy losses occur at best at the
time of the transition of the liquid from the first propeller to
the second one.
[0025] The energy is supplied to the electric motor by lines
21.sup..cndot..cndot., which are led to the motor in the foot
18.sup..cndot..cndot. and in the housing 2.sup..cndot..cndot., and
the inner spaces of the foot 18.sup..cndot..cndot. and of the
housing 2.sup..cndot..cndot. are therefore in connection with one
another.
[0026] To make it possible to use the drive not only to generate a
thrust in the longitudinal direction of the ship (longitudinal axis
of the drive shaft), but also to steer the ship, the entire drive
is pivotable around the vertical longitudinal axis
22.sup..cndot..cndot. in the middle between the two propellers,
optionally all around by 360.degree. due to the corresponding
association with the ship and by means of an appropriate pivoting
mechanism in the known manner, the axis 22.sup..cndot..cndot. being
directed at right angles to the axis of rotation of the
longitudinal axis 23.sup..cndot..cndot. of the shaft.
[0027] The motor 1.sup..cndot..cndot. is designed as a permanent
synchronous motor and thus it is an electric machine with very high
power density. Due to the technology of such a motor, it is
possible to design the housing 2.sup..cndot..cndot. between the two
propellers hydrodynamically such that a very high efficiency will
be reached.
[0028] It is possible in the case of this technology for the foot
18.sup..cndot..cndot. to be designed as a shaft, so that it will
also have an optimal hydrodynamic shape.
[0029] In the lower area located in the proximity of the housing
2.sup..cndot..cndot., the shaft 18.sup..cndot..cndot. is designed
such that it forms a guide fin pair and thus a control device
together with a second, diametrically opposite guide fin
20.sup..cndot..cndot., so that an optimal flow of water to the
propeller 4.sup..cndot..cndot., which is the second propeller when
viewed in the oncoming flow direction A.sup..cndot..cndot., is
possible. The guide fins end in the tip circles
5.sup..cndot..cndot. of equal diameter of the two propellers
3.sup..cndot..cndot., 4.sup..cndot..cndot..
[0030] Due to the combination of the permanent synchronous motor of
high power density on a small diameter with the optimal guide means
(guide fin pair or control device 20.sup..cndot..cndot.) as well as
with the two propellers 3.sup..cndot..cndot., 4.sup..cndot..cndot.,
a drive unit is obtained which is characterized by an extremely
great improvement in efficiency both electrically and
hydrodynamically.
[0031] The design of the motor 1.sup..cndot..cndot. as a permanent
synchronous motor makes it possible to reduce the diameter of the
housing 2.sup..cndot..cndot. by up to 20% compared with other,
prior-art motors. The advantages are obvious: Only the smaller
masses and more favorable flow conditions and lower flow resistance
shall be mentioned.
[0032] Another design according to the present invention pertains
to the mounting of the rotor of the permanent motor, which also
contains the mounting of the propeller shaft. To reduce or
eliminate the displacements and deformations as well as the dynamic
loads from the propellers, the rotor, i.e., the drive shaft
7.sup..cndot..cndot., is connected to the propeller shafts
12.sup..cndot..cndot., 13.sup..cndot..cndot. via disk clutches
23.sup..cndot..cndot., 24.sup..cndot..cndot.. As a result, it is
possible to obtain a minimal air gap between the stator and the
rotor, which means a considerable, additional improvement in
efficiency.
[0033] Description of the Exemplary Embodiment According to FIG.
3
[0034] FIG. 3 shows a ship drive designed as a rudder twin
propeller with a drive unit arranged in the hull with vertical
drive shaft 1.sup..cndot. and drive propellers outside the hull. A
drive unit comprising a motor and transmission acts on the top end
of the vertical drive shaft 1.sup..cndot. in the known manner,
therefore not shown in FIG. 3, in order to set the drive shaft
1.sup..cndot. into rotation around the longitudinal axis
2.sup..cndot. at variable speed of rotation. The input bevel gear
3.sup..cndot. of a right-angle gear drive 3.sup..cndot.,
4.sup..cndot., which bevel gear 3.sup..cndot. is in functional
connection with the output bevel gear 4.sup..cndot. of the
right-angle gear drive 3.sup..cndot., 4.sup..cndot., is associated
with the lower end of the drive shaft 1.sup..cndot., rotating in
unison. The output bevel gear 4.sup..cndot. carries a horizontal
output shaft 5.sup..cndot. extending in both directions, rotating
in unison with it, with the propellers 6.sup..cndot., 7.sup..cndot.
arranged at the free ends of the output shaft, rotating in unison
with it. The propellers usually have different designs, even though
tip circles 14.sup..cndot. of equal diameter as well as similar
wing geometries may be possible. Due to the joint association with
the output shaft 5.sup..cndot., they have the same direction of
rotation and the same speed of rotation and the flow is directed
toward them in the same direction, e.g., according to arrow
A.sup..cndot..
[0035] The right-angle gear drive 3.sup..cndot., 4.sup..cndot. is
surrounded by a housing 9.sup..cndot., in which the output shaft
5.sup..cndot. is mounted rotatably by means of two bearings
10.sup..cndot., 11.sup..cndot.. This housing 9.sup..cndot. is
carried by a housing pipe 9a.sup..cndot., which concentrically
surrounds the vertical drive axis 1.sup..cndot. and is pivotable
around its longitudinal axis for the rudder function.
[0036] The underwater part of the drive system may be arranged
within a nozzle 12.sup..cndot..
[0037] In its wake, the front propeller 6.sup..cndot. generates a
rest or aftertwist, which represents lost energy. The wake of the
front propeller is admitted to the downstream propeller
7.sup..cndot., rotating in the same direction. Without a guide
means between the two propellers 6.sup..cndot., 7.sup..cndot., the
above-mentioned unfavorable wake would lead to intensified
cavitation and to an increase in the energy losses.
[0038] To counteract this energy loss, a guide means 8.sup..cndot.,
with which the aftertwist of the front propeller 6.sup..cndot. is
directed, is provided between the two propellers 6.sup..cndot.,
7.sup..cndot.. Lost energy is now recovered by a propulsive force
being generated during the flow around the guide means.
Furthermore, a pretwist is generated for the downstream propeller
7.sup..cndot., so that the latter can realize a greater energy
gradient. Taking this criterion into account, the second propeller
7.sup..cndot. preferably has a design different from that of the
first propeller 6.sup..cndot..
[0039] According to FIG. 3, the guide means 8.sup..cndot. comprises
two guide blades 8a.sup..cndot. and 8b.sup..cndot., wherein one
guide blade 8a.sup..cndot. is formed by the housing pipe
9a.sup..cndot. surrounding the vertical drive shaft 1.sup..cndot..
The second guide blade 8b.sup..cndot. is located on the underside
9b.sup..cndot. of the housing 9.sup..cndot. surrounding the
horizontal output shaft 5.sup..cndot., i.e., offset by 180.degree.
from the first guide blade. The two guide blades 6.sup..cndot.,
7.sup..cndot. form an assembly unit with the overall housing
9.sup..cndot., 9a.sup..cndot..
[0040] Description of the Exemplary Embodiment According to FIG. 4
Through FIG. 6
[0041] The drive comprises essentially an electric motor 1 in a
housing 2 outside and especially under the hull and two propellers
3, 4, which are driven by the electric motor 1. The two propellers
are usually of different design, even though they may have tip
circles 5 of equal diameter as well as a similar wing geometry.
They have the same direction of rotation and the same speed of
rotation and the flow is directed toward them in the same
direction, e.g., according to arrow A.
[0042] The electric motor 1 is arranged in the underwater housing 2
in a watertight manner. The driven shaft 7 is led out of it on both
sides and the shaft is mounted in it rotatably in one of two
bearings 8, 9 of the housing 2 to the side of the motor. Seals 10,
11 to the side of the bearings 8, 9 between the shaft 7 and the
front-side housing walls 2a, 2b are used for sealing in conjunction
with the front surfaces being designed as parts of labyrinth seals.
Shaft ends 12, 13, each of which carries one of the two propellers
3, 4, rotating in unison, are flanged on the shaft 7 outside the
housing 2. On the front side, the housing 2 is joined by hub caps
14, 15, wherein a continuous outer contour with head 14, which said
contour is favorable in terms of flow, is formed in the area of the
front propeller 3, the middle part in the form of the housing 2 and
the end part 15 in the area of the rear propeller 4. The front
walls 14a, 15a of the hub caps 14, 15 facing the housing 2 are
second parts of the labyrinth seals 16, 17, whose first parts are
the aforementioned front surfaces 2a, 2b. The housing 2 is held at
the hull with a foot 18, which is designed as a hollow foot, whose
outer contour is part of the control device 19 between the
propellers 3, 4, which has additional blades associated with the
housing 2, of which one blade, which is located diametrically
opposite the foot 18, is designated by 20. On the whole, the blades
of the control device 19 are rigidly associated with the housing 2,
distributed uniformly around the longitudinal axis of the shaft
7.
[0043] On the whole, the propellers 3, 4 are designed such that the
output energy level of the second propeller 4 is approximately
equal to the final energy level of the first propeller 3 and, in
the control device 19, the output twist of the first propeller 3 is
removed from the input to the second propeller 4, and thus only
slight energy losses occur, at worst, at the time of the transition
of the liquid from the first propeller to the second one.
[0044] When leaving the first propeller 3 the water flow has an
axial component ("conveyor direction") and a circumferential
component ("twist"). The latter component, i.e. the component in
the circumferential direction, is deflected by a guide blade 19
into the axial direction, so that the water flow entering the
second propeller 4 has only components in the axial direction,
similar to the water flow entering the first propeller 3.
[0045] The energy is supplied to the electric motor by lines 21,
which are led to the motor in the foot 18 and in the housing 2, and
the inner spaces of the foot 18 and of the housing 2 are therefore
in connection with one another.
[0046] To make it possible to use the drive not only to generate a
thrust in the longitudinal direction of the ship (longitudinal axis
of the drive shaft), but also to steer the ship, the entire drive
is pivotable around the vertical longitudinal axis 22 in the middle
between the two propellers, optionally all around by 360.degree.
due to the corresponding association with the ship and by means of
an appropriate pivoting mechanism in the known manner, the axis 22
being directed at right angles to the axis of rotation of the
longitudinal axis 23 of the shaft.
[0047] An especially advantageous embodiment of the drive according
to the present invention will be described below with reference to
FIGS. 5 and 6. The electric motor 1 is advantageously, but not
essentially, a permanently excited synchronous motor with permanent
magnet rotor 25 and stator laminations 26. Such motors have are
known in the art, so that the electric motor, which is
advantageously a permanently excited synchronous motor, as well as
other suitable types of electric motors, are not specifically
described.
[0048] The use of such a motor in the housing 2, which has a
gondola-like design and is arranged under the hull of the ship 24,
beneath the water surface, for driving the two co-rotating
propellers 3, 4, which face the same direction A, has various
application-specific advantages, especially in terms of electric
efficiency, and it makes it possible to dispense with forced
cooling apparatus. In addition, a small overall volume is made
possible which in turn makes possible an optimal shape of the
underwater housing with respect to resistance, especially a housing
with a small maximum diameter. The gondola-shape of the housing 2
performs a guiding function whereby the gondola-shaped housing 2
serves as part of the control device in addition to the guide fins
20 and hollow shaft or foot 18.
[0049] In order to be able to avoid forced cooling, the outer
stator 26 is constructed as a laminated yoke of the electric motor
1, and is connected tightly and in direct heat contact to the
underwater housing 2. The inner rotor 25 of the motor 1 is rigidly
connected via support tube 27 to the rotatable shafts 12, 13. In a
similar way, the stator 26 is rigidly supported in the housing 2
via support tube 26' which is made of heat conducting material, and
which is firmly connected to the motor 26, as well as to the
housing 2. In this arrangement there is direct heat transfer from
the stator 26 of the motor (motor housing) to the support tube 26'
and finally to the underwater housing 2, from which the heat is
dissipated into the surrounding water flow. The underwater housing
2, the support tube 26' and the motor housing 26 are, thereby,
sufficiently cooled.
[0050] The tight connection between support tube 26' and underwater
housing 2, and between stator 26 and support tube 26' respectively,
can be accomplished, e.g., by pressing each inner part held at
lower temperature into the respective outer part held at a higher
temperature. In use, at running temperature, the two parts will
then be tightly connected.
[0051] For cooling the bearings 8, 9 correspondingly, the bearings
8, 9, which support the shafts 12, 13, are in turn supported on by
flanges 8a, 9a which are made of heat conducting material. The
outer flange surfaces 8b, 9b are tightly connected to the inner
surface of the underwater housing 2 and to the motor housing
26.
[0052] In another design, such a permanently excited synchronous
motor is arranged in the gondola-like housing 2 such that the
continuous propeller shaft 12, 13 and the rotor 25 have a common
mounting with the two bearings 8, 9. This is specifically realized
such that the permanent rotor 25 is seated on a support tube 27,
which is concentrically surrounded by it and which is associated
with the propeller shaft 12, 13, rotating in unison with it, in the
proximity of its two ends via one of two annular disk clutches 28,
29 each, wherein the disk clutches 28 and 29 as well as the
corresponding bearing 8 or 9 are located close to one another at
the two shaft ends. Due to the propeller shaft and the electric
motor tube having a common mounting, the number of components is
minimized and the reliability of the drive unit is increased. Due
to the use of the respective disk clutch located in close proximity
to the respective plain bearing, a highly accurate centering of the
rotor, which is extensively independent from the sag of the
propeller shaft, is achieved within the stator. This leads to
considerable advantages in terms of the dynamic behavior of the
rotor within the machine (e.g., the excitation of structure-borne
noise is minimized).
[0053] Likewise as a consequence of the electric motor being
designed as a permanently excited synchronous motor 1 (FIGS. 2, 3),
integration of the underwater housing shaft 18 (called a "foot" in
connection with FIG. 1) within the drive is possible in a
particularly advantageous manner. This housing shaft may be made as
an especially slender shaft, as a result of which the flow
resistance of the unit is considerably reduced. This slender
underwater housing shaft 18 has such a cross-sectional profile that
an additional untwisting of the wake of the front propeller 3 is
achieved in conjunction with a lateral guide fin pair (not shown),
which is offset by 90.degree., the geometry of the housing 2, and
the opposite guide fin 20, which is offset by 180.degree.. This
results in an improvement in efficiency of the drive with two
essentially identical co-rotating propellers (in terms of speed of
rotation and direction of rotation).
[0054] A parking brake for fixing the propeller shaft 12, 13 and
thus the assembly unit, whose parts include the propeller shaft, is
arranged within the underwater gondola 2 and is designated by
33.
[0055] Finally, the design according to FIGS. 5, 6 leads to an
essential simplification of the underwater assembly efforts.
[0056] Rudder propellers that can be assembled/disassembled with
the ship floating are offered by various rudder propeller
manufacturers. The corresponding assembly effort is still
considerable. The present invention makes possible, especially in
the embodiment according to FIGS. 5 and 6, a greatly simplified
underwater assembly/disassembly at the underwater housing
shaft-carrier cone separation point. The underwater housing shaft
is also designated by the reference number 18 in FIG. 6; its top
end is located in the plane 24 of the shell of the ship and is
connected to the carrier cone 30. At the top end, the carrier cone
is mounted in a steering bearing 31 in the support structure of a
ship. This steering bearing 31 has an inner ring 31a with an inner
toothed ring 31b, and this bearing inner ring 31a is rigidly
associated with the outer circumference of the carrier cone 30. The
outer ring 31c cooperates with the inner ring via the rolling
bodies and it is rigidly integrated in the support structure of the
ship. The pinion (not shown) of a drive (not shown) engages the
inner toothed ring of the inner ring of the steering bearing, so
that the entire drive can be rotated by 360.degree. around the
longitudinal axis 22 for steering the ship.
[0057] The detachable connection between the housing shaft 18 and
the carrier cone 30 is symbolized by a flanged connection 32.
[0058] Common to all embodiments is the combination of the features
of claim 1, according to which the drive is a hydrojet for
watercraft, especially ships, which has a drive unit and two
propellers driven by same, which said propellers are arranged at
the two ends of a gondola-like, streamlined underwater housing
outside the underwater housing and are driven by a drive means,
which is located within the underwater housing and a common drive
shaft acts on the two propellers, wherein the first propeller
markedly increases the flow energy of the flow medium and this flow
medium is supplied with a high energy content, after eliminating
the inevitable aftertwist in a guide means, to the second
propeller, which differs from the first propeller in terms of its
blading such that the relatively low flow energy in the first
propeller is optimally increased, while the relatively high flow
energy is increased further in the second propeller; in a special
embodiment, described below on the basis of FIG. 2, the second
propeller has a central part, which differs from the first
propeller in the described manner, and a peripheral part, which is
identical to the first propeller to this extent and to which the
medium flows in the same manner as to the first propeller.
[0059] Description of the Embodiment According to FIG. 7
[0060] The propeller 3 that is the front propeller in the direction
A of the incoming flow has an optimal blading for increasing the
energy of the flow medium. The propeller 4 that is the rear
propeller in the direction A of the incoming flow has the same
blading in this respect in a peripheral area. This peripheral area
surrounds a central area, in which the blading differs from that of
the front propeller 3 as was described several times above, i.e.,
it once again increases the energy increased in the first propeller
from this energy level after the flow medium leaving the first
propeller 3 has been untwisted in the control device 19 and the
energy loss caused by the twist has been compensated. The core area
and the peripheral area are separated from one another by the
contraction surface 100, i.e., by the jacket surface, which
surrounds the flowing fluid after it has left the first propeller 3
and circumscribes a cross section that is markedly smaller than the
incoming flow cross section. The flow medium B consequently flows
to the second propeller in the peripheral area in the same manner
as the flow medium that is characterized by the arrows A flows to
the first propeller.
* * * * *