US 20170O81 01 0A1(19) United States(12) Patent Application Publication (10) Pub. No.: US 2017/0081010 A1(43) Pub. Date:

KURIBAYASH et al.

(54)

STEERING DEVICE AND METHOD FOR
STEERING THE SAME(71) Applicants:Noriyuki SASAKI, Kanagawa (JP);KAY SEVEN CO., LTD., Tokyo (JP);Mar. 23, 2017

Publication Classification(51) Int. Cl.
B63H 25/38(2006.01)(52) U.S. Cl.
CPC ........... B63H 25/38 (2013.01); B63H 25/382

NATIONAL MARITIME(2013.01); B63H 2025/066 (2013.01)

RESEARCH INSTITUTE, Tokyo (JP);YAMANAKA SHIPBUILDING CO.,LTD., Ehime (JP); KAMOME
PROPELLER CO.,LTD., Kanagawa(JP)(72) Inventors: Sadatomo KURIBAYASHI, Tokyo(JP); Noriyuki SASAKI, Kanagawa(JP)(73) Assignees: Kay Seven Co., Ltd., Tokyo (JP);Noriyuki Saska, Chigasaki-shi,
Kanagawa (JP); National Institute od
Maritime, Port and Aviation

Technology, Tokyo (JP); Yamanaka
Shipbuilding Co., Ltd., Imabari, Ehime(JP); Kamome Propeller Co., Ltd.,
Yokohama, Kanagawa (JP)(21) Appl. No.:

15/115,601(22) PCT Fed:

Nov. 19, 2014

(86)

PCT/UP2O14/080623

PCT No.:

S 371 (c)(1),
Oct. 13, 2016
(2) Date:
Foreign Application Priority Data
(30)
Jan. 31, 2014
Mar. 14, 2014

(JP) ................................. 2014-0174O1(JP) ................................. 2014-052040(57)

ABSTRACTA steering device in which a rudder plate is verticallySuspended at a positive minimum distance C. from an outeredge of a propeller having a radius R from a steering shaft
which is biaxially arranged and symmetrically rotatesaround a screw shaft within a propeller radius R from ascrew shaft center, on a propeller rotation plane, and can beturned from aside of a propeller to a downstream of thepropeller by rotation of the steering shafts, each of which isdriven independently by two hydraulic driving mechanisms,
and the steering device is characterized in that the steering
action is divided into two modes: the two-independent modeand the two-same direction modes, and each mode isadapted as follows: at the time of ahead condition, each oneof the two rudder plates is retained on both sides of apropeller parallel with a ship axis, and at the time of veeringof the two-same direction mode, a rudder plate opposite toa veering direction turns 45° from aside of the propeller tothe downstream of the propeller, and the other rudder plateturns -45° from aside of the propeller to the upstream of thepropeller, and at the time of veering of the two-independentmode, the rudder plate opposite to a veering direction turns
45° from aside of the propeller to the downstream of thepropeller, and simultaneously, the other rudder plate turns
from aside of the propeller to the upstream of the propeller
to take a rudder angle of 90° or more, to generate a thrust
flow, and a method for steering the same to enhance a thrust
flow by increase in a propeller rate.

Patent Application Publication

Mar. 23, 2017. Sheet 1 of 26

Fig.

2.

US 2017/008101.0 A1

Patent Application Publication

Fig. 2Mar. 23, 2017. Sheet 2 of 26

US 2017/008101.0 A1

Patent Application Publication

Fig. 30Mar. 23, 2017. Sheet 3 of 26

US 2017/008101.0 A1

Patent Application Publication

Fig. 4Mar. 23, 2017. Sheet 4 of 26

US 2017/008101.0 A1

Patent Application Publication

Fig. 5Mar. 23, 2017. Sheet 5 of 26

US 2017/008101.0 A1

Patent Application Publication

Fig. 6A

Mar. 23, 2017. Sheet 6 of 26

US 2017/008101.0 A1

Patent Application Publication

Fig. 6B

Mar. 23, 2017. Sheet 7 of 26

US 2017/008101.0 A1

Patent Application Publication

Fig. 7Mar. 23, 2017. Sheet 8 of 26

US 2017/008101.0 A1

Patent Application Publication

Fig. 8Mar. 23, 2017. Sheet 9 of 26

US 2017/008101.0 A1

Patent Application Publication

Fig. 9Mar. 23, 2017. Sheet 10 of 26

US 2017/0081010 A1

Patent Application Publication

Fig. O

Mar. 23, 2017. Sheet 11 of 26

US 2017/0081010 A1

Patent Application Publication

Mar. 23, 2017. Sheet 12 of 26

Fig.

24)

(~ $,

US 2017/008101.0 A1

Patent Application Publication Mar. 23, 2017. Sheet 13 of 26

Fig. 2

US 2017/0081010 A1

Patent Application Publication

Fig. 3Mar. 23, 2017. Sheet 14 of 26

US 2017/0081010 A1

Patent Application Publication

Fig. 4Mar. 23, 2017. Sheet 15 of 26

US 2017/0081010 A1

Patent Application Publication

Fig. 15

Mar. 23, 2017. Sheet 16 of 26

US 2017/0081010 A1

Patent Application Publication

Fig. 6

Mar. 23, 2017. Sheet 17 of 26

US 2017/0081010 A1

Patent Application Publication

Fig. 17Mar. 23, 2017. Sheet 18 of 26

US 2017/0081010 A1

Patent Application Publication

Fig. 8Mar. 23, 2017. Sheet 19 of 26

US 2017/0081010 A1

Patent Application Publication

Fig. 19

Mar. 23, 2017. Sheet 20 of 26

US 2017/0081010 A1

Patent Application Publication

Mar. 23, 2017. Sheet 21 of 26

US 2017/0081010 A1

Fig. 20

CrOSS Section A-A

Patent Application Publication

Mar. 23, 2017. Sheet 22 of 26

US 2017/0081010 A1

Fig. 21

Cross Section A-A

Patent Application Publication

Mar. 23, 2017. Sheet 23 of 26

Fig. 22

2

US 2017/0081010 A1

Patent Application Publication

Mar. 23, 2017. Sheet 24 of 26

US 2017/0081010 A1

Fig. 23

|

s

rw

r r

as

es al e e 82

rar wa wa wa aw ra ra wa raPatent Application Publication

Fig. 24

Mar. 23, 2017. Sheet 25 of 26

US 2017/0081010 A1

Patent Application Publication Mar. 23, 2017. Sheet 26 of 26

US 2017/008101.0 A1|}|- - -

Ajpºesdas

dog334øp rix}US 2017/008101.0 A1

STEERING DEVICE AND METHOD FOR
STEERING THE SAMECROSS-REFERENCE TO RELATEDAPPLICATION

0001. The present application claims the priorities basedon Japanese Patent Application No. 2014-017401 "STEERING DEVICE filed Jan. 31, 2014 and Japanese Patent
Application No. 2014-052040 “STEERING DEVICE filed
Mar. 14, 2014, a content of which is incorporated herein byreference.
TECHNICAL FIELD

0002 The present invention relates to a steering device
which allows for high propulsive performance of marine
vehicles due to saving of main engine fuel consumption
during navigation of these vehicles (see, for example, Non
Patent Literature 1). More particularly, the invention is asteering mechanism which improves the conventional rud
der behind a propeller to enhance the propulsive perfor
mance of the propeller. The mechanism also utilizes therudder at the time of stopping, enhances the steering ability
at a slow vessel speed, and reduces the underwater noise
emitted by the propeller and the rudder. The present invention is suitable for effective water trafficking of ships bymaking use of rudder assisted Steering of marine vehicles byusing the method described in this application.
BACKGROUND ART

0003. The conventional rudder is positioned in the slip
stream of a propeller and hence by creating an additional
resistant component. When a rudder is not disposed behinda propeller but to remain in the same lateral plane with thepropeller, it is left to arrange the rudder aside or in front of
the propeller. In view of interference with a propulsion shaft,configuration of two or more rudders must be taken. On theother hand, Non-Patent Literatures 2 and 3 pay an attention
to the stopping ability, and propose the adoption of asingle-shaft propulsion with twin rudders for ship handling.
It is stated therein that, upon request of a Sudden stop at
emergency, the two rudders cooperate at a right angle to ahull by taking position behind the propeller to block its
slipstream, and to provide the vessel with a powerful stop
ping ability. This way of steering and stopping technique is
not much different from the prior art, in a point that therudder still acts as a resistance component in the slip streamof a propeller. As the prior invention of twin rudder, there isMar. 23, 2017

angle of 90 degree, it becomes necessary to also contrive asteering shaft driving mechanism, and Patent Literature 3
proposes an oil hydraulic driving mechanism which enables
a rudder angle near 180 degree, using a rotary vane. Patent
Literature 4 describes the proposal that the effect of straightening a propeller slipstream in a region sandwiched by two
rudders is exerted, and a high propulsive efficiency can berealized. However, in this latter arrangement, since therudders are arranged at the slipstream of a propeller, it seems
that there is a limitation in improvement of the propulsive
performance. Inter alia, in domestic vessels, since the Sup
port by tugboats inside the bay will not be expected, theturning ability at the slow ship speeds should be maintainedby own ship handling. In the case of the rudder arranged
outside of the propeller slip stream aiming to only higher
propulsive efficiency, the special attention should be paid tothe movement of the rudder during the steering motion andalso mechanism and a steering method are the same. An
invention which recognizes or suggests a solution by dis
criminating at the time of slow speed navigation and at thetime of cruising concerning steering in this case has not beenfound out. In this respect, as a method for steering two
rudders, FIG. 4 of Patent Literature 5 presents a “method for
displaying a moving direction for a system of two rudders'.
In this presentation the rudder position and a moving direc
tion of a ship are displayed in ships having two rudders as
Such rudder arrangement of steering modes of (b) indicatesforward right turning, and (e) right turning on the spot.
However the present invention is not suggested by a positional relationship between a turning central position of two
rudders and a propeller in propeller slipstream arrangement.
In addition, there is proposed a ship in which two rudders arearranged on both sides of a propeller, for the purpose of
shortening the length of the propeller and that of a stern
rudder for expansion of space for a stein (Patent Literature4). However, according to configuration shown in FIG. 8 ofPatent Literature 4, it seems that there is limitation in asteering range, and it is difficult to create a deflected streamof a propeller slipstream.
PRIOR ART LITERATURES

Patent Literatures

Patent Literature 1 JP-A-2014-73815
Patent Literature 2JP-A-50-55094
Patent Literature 3 JP-A-2011-73526

the invention disclosed in Patent Literature 1. The same

invention prioritizes improvement in propulsive perfor
mance due to such a rudder plate that “two rudder plates arearranged in front of or aside the propeller, and does notconcentrate on the stopping ability. On the other hand,configuration having two steering shafts is also disclosed in
FIG. 12 of Patent Literature 1, and since a rudder plate
rotates around a steering shaft included in a rudder plate
face, the rudder plate cannot take position behind the propeller slipstream and hence a problem arises in the steering
ability, particularly, at a slow vessel speed. This is problem
atic for domestic vessels and patrol boats which cannot
receive assistance of tugboats. When the number of rudders
is 2, utilization of a camber comes in sight, but Patent
Literature 2 is limited to use the effect of camber in a twin

rudder arrangement in propeller slipstream. At a rudder

Patent Literature 4 JP-A-2010-13087
Patent Literature 5 JP-B-6-92240
Non-Patent Literatures

Non-Patent Literature 10004 https://www.mlit.go.jp/report/press/kaiji 06 hh
000061.html“Regarding Evaluation of Support for Technology Development for Curtailing CO from Marine Vessels', accom
panying material “Regarding Evaluation of Support forTechnology Development for Curtailing CO from Marine
Vessels', Ministry of Land, Infrastructure, Transport andTourism, Marine Bureau, Heisei 25 Year (2013) March 29

US 2017/008101.0 A1

Non-Patent Literature 2 New Conception of New Steering
Machine Rudder System-Rotary Vane Steering Machine,
Vec Twin Rudder System (2) Journal of the Japan Instituteof Marine Engineering, vol. 45, No. 3, P97-104

Mar. 23, 2017at the propeller slipstream is solved, and this is also asteering device and a steering procedure of the present
invention.
Means to Solve the Problems

Non-Patent Literature 3 New Conception of New Steering
Machine Rudder System-Rotary Vane Steering Machine,
Vec Twin Rudder System (1) Journal of the Japan Instituteof Marine Engineering, vol. 45, No. 2, P93-99
SUMMARY OF THE INVENTION

Problems to be Solved by the Invention
0005. As shown above, many attempts have been madefor a contrivance to improve the propulsion performance ofships using the single-shaft and single rudder combination
but these attempts had limited impact on the propulsion
performance under the restricted condition of the same
configuration. There is also contrivance for maintaining
turning performance under configuration of twin-shaft pro
pulsion, but there is a problem in regards to the cost ofadditional engine requirement. There is also contrivance for
Supplementing decrease in performance generated fromshape modification while maintaining turning performanceby contrivance of a rudder shape, but there is limitation in
improvement in cruising propulsion performance of mainly
traveling straight. A Kort nozzle which eliminates the needfor a dedicated rudder at a stern has a problem in a point of
propulsive efficiency performance. By simple arrangementof a rudder on both sides of a propeller, higher propulsive
performance than before is obtained, but it is insufficient forpursuing high turning performance. The present invention isa new rudder and arrangement system offering a universal
rudder of an era and propeller system for merchant ships
which can provide a fast water stream utilizing a fossil fuel.
0006. A new rudder is expected to save a fossil fuelconsumption amount and a CO2 generation amount due toimprovement in propulsive performance, and maintain highturning performance and the stopping ability at emergency.
0007. Then, at the time of straight cruising, it is preferable that the rudder is not positioned in the propeller
slipstream, and at the time of emergency stopping it ispreferable that the rudder is positioned in the propeller
slipstream and can be steered until a right angle to a ship
hull, and a turning mechanism realizing a rudder angle of 90
degree is preferable.
0008 Even when the rudder is not positioned in theslipstream of a propeller, it is required to deflect the propeller slip stream to maintain the turning ability.
0009. The present invention was done in view of theaforementioned problems, and an object thereof is to pro
vide a steering device in which, in order to enhance a
propulsion efficiency of a propeller at the time of straightcruising, a rudder is not positioned in the propeller slip
stream. At the time of emergency stopping, a rudder angle of
90 degree to the ship hull enables the propeller slipstream todeflect to assist stopping and then back to straight position
for turning to maintain turning performance.
0010 For a new rudder, arrangement and movement of
the rudder at the time of veering are further elaborated, aproblem of maintaining turning performance at a slow speed
is recognized, and inconvenience of not disposing the rudder

O011

The present invention solving this problem is asfollows.

Invention Described in Claim 10012. A steering device having a driving mechanism
rotating a steering shaft, and a power mechanism driving
this, wherein the steering shaft is biaxially arranged to rotate
on both sides of a screw shaft upper portion, each steering
shaft connects and Suspends a rudder plate from the upper
portion of the rudder plate, and two rudder plates can turnfrom aside of a propeller to a downstream of the propeller byrotating two steering shafts.

The Operational Advantage of the Invention
0013. In the invention described in claim 1, the steering
shaft is biaxially arranged to rotate on both sides of a screw
shaft upper portion, the steering shaft connects and Suspends
a rudder plate from the upper portion of the rudder plate, anda power mechanism Such as an electric servomotor or ahydraulic cylinder turns two rudders from aside of a propeller to a downstream of the propeller by rotation of twosteering shafts via a driving mechanism. At the time of direct
cruising, since two rudders are arranged on both sides of thepropeller parallel with a ship longitudinal axis, and do nothinder a propeller slip stream, higher propulsive perfor
mance can be provided as compared with the propeller
arrangement of the conventional technology. Since two
rudders are arranged on both sides of the propeller, and thenarrower and smaller rudder can be used for each rudder ascompared with the conventional single rudder configuration,and the rudder receives a Smaller fluid viscous resistance,

and therefore, a high propulsive efficiency is obtained. It ispreferable that the smaller rudder herein has a length ofabout a half of that of the case of single rudder configurationin terms of a rudder length. At the time of steering, since twosteering shafts are used, dedicated Steering shafts are dis
posed for two rudder plates, and two rudder plates are turned
from aside of the propeller to the downstream of the propeller by the rotation of two steering shafts. By this arrange
ment the turning radius can be smaller, two rudder plates anda rear end of the propeller are brought close to each other,and a deflected propeller slipstream can be generated at alarge rudder angle to realize a high turning performance.
Herein, it is preferable that a smaller turning radius is, forexample, Such that the turning radius is around a half of apropeller radius.
0014) A power mechanism of the invention described inclaim 1 may be a hydraulic cylinder in which two steering
shafts are rotated by a cylinder shaft. This shaft is driven
linearly by a hydraulic cylinder which is reciprocated by an
oil pressure and crank mechanism which converts a recip
rocating linear motion into a rotation motion. Alternatively
the power mechanism may be a hydraulic cylinder con
structed of a bevel gear which is attached to the steering
shaft and can rotate the steering shaft together with rotation,
and a bevel gear mechanism which converts a rotational
plane from horizontal into vertical, Here, the power mecha
nism is an electric servomotor or a hydraulic motor mechaUS 2017/008101.0 A1

nism, or when the electric servomotor mechanism or thehydraulic motor mechanism is a vertical type, the steering
shaft is directly driven with the hydraulic motor, and the gear
mechanism may be omitted.
0015 The power mechanism of the invention describedin claim 1 is a hydraulic cylinder and the driving mechanism
thereof comprises a rotation driven mechanism freely rotat
ing the two steering shafts by a cylinder shaft and crankmechanism which are reciprocation-driven by a hydrauliccylinder being reciprocated preferably by oil pressure, and in
this case, two rudder plates arranged on both sides of thepropeller at the time of direct cruising turn around thepropeller with two steering shafts being reciprocation-rotated by the cooperation of a cylinder shaft and a crankmechanism. This mechanism is reciprocation-driven linearlywith a hydraulic cylinder being reciprocated by an oilpressure, and a rudder angle seen from its ship axis ischanged. By rotation of the steering shaft of this driving
mechanism, one of two rudders is moved into the propeller
slipstream, thereby, a more deflected slipstream can beproduced, and the effect of providing high turning perfor
mance is obtained, as compared with the case where therudder plate is rotated around a shaft on a rudder plate on
both sides of the propeller to obtain a rudder angle. Suchsimplicity is obtained that when a straight motion is con
verted into a rotational motion by a crank mechanism torotate two steering shafts using a hydraulic device which isnormally mounted in a ship as a power source, a steering
device mechanism may be on an extended line of theprevious mechanism, and the economical property is excel
lent. In a configuration that two steering shafts are rotated inconjunction by a linking crank mechanism, since two rudderplates synchronously turn around the propeller, there is also
an advantage that a steering control mechanism may be
simple.
0016. The steering device according to claim 1, in which
the power mechanism of the invention described in claim 1
is an electric servomotor or a hydraulic motor mechanism,and the driving mechanism thereof is a bevel, gear which is
attached to the steering shaft and can rotate the steering shaft
together with rotation, and a bevel gear mechanism whichconverts a rotation plane between vertical and horizontal isalso preferable, and in this case, at the time of straightcruising, when the electric servomotor mechanism or thehydraulic motor mechanism is driven, a rudder angle can be
independently changed together with the steering shaft
which is rotation-driven with the bevel gear mechanism, toturn rudder plates arranged on both sides of the propeller
around the propeller to move at least one rudder plate ofthem to the downstream of the propeller, and high turning
performance is exerted. Further, when both rudder plates are
moved to a slipstream side around the propeller until a planevertically intersecting with a ship longitudinal axis, thecomplete stopping action can be provided. In this regard,
since two rudders are independently steering-controlled by
the electric servomotor mechanism or the hydraulic motor
mechanism, as compared with the steering device describedin the first part, soft control is possible, a degree of freedomof ship handling is enhanced, and the effect of providing thefiner turning function is obtained.
0017. In the present invention, the steering device
according to claim 1, in which two rudder plates arearranged on both sides of the propeller at the ahead conditionof the ship, the length of two rudder plates are configured soMar. 23, 2017as to locate the leading edges of the two rudders are
protruding ahead of the propeller plane in a bow direction,and the preferred action of Straightening a propeller water
stream is exhibited, and in this case, two rudders provide thefunction of straightening a water stream flowing into thepropeller by interaction thereof to enhance propulsive performance of the propeller. In a system of simply positioning
the rudder forward away from the propeller in order to
exclude a steering portion resistance force generated from apropeller slip stream, Such straightening action is not
obtained. The effect given by the rudder in connection withthe present invention is different in principle from effect of
the straightened stream generating function by the rudder ofpropeller slipstream arrangement. According to the steering
device in this case, two rudder plates are arranged on bothsides of the propeller at the ahead condition of the ship, andthe length of two rudder plates are configured so as to locate
the leading edges of two rudders are protruding ahead of thepropeller plane in a bow direction. In Such configuration,
there is the effect of suppressing turbulence of a, water
inflow into the propeller caused by a region sandwiched by
two rudder plates protruding in a bow direction, imparting
the straightening effect at an inlet portion, at a propeller
rotation Surface in a region Sandwiched by two rudders,water flow is bounded and regulated, and accelerating a flowrate of the slipstream, to enhance turning performance. In acase of modification of a fuller ship aiming the larger cargospace, the flow regulation effect of the present invention isincreased because the upstream flow of a propeller is notformed by enlargement of a stern shape.
0018. In the present invention, it is preferable to characterize the steering device according to claim 1 So that two
rudder plates are arranged on both sides of the propeller at
the ahead condition of the ship, the length of two rudderplates are configured so as to locate the leading edges of two
rudders are protruding ahead of the propeller plane in a bow
direction, and the action of straightening a propeller slip
stream is exhibited, and in this case, two rudder plates
improve propulsive efficiency by flow regulation effect onan outlet flow of a propeller and turning performance byaccelerating flow at the same time, when two rudder plates
are arranged on both sides of the propeller at the ahead
condition of the ship, the length of two rudder plates are
configured so as to locate the leading edges of two rudders
are protruding ahead of the propeller plane in a bow direction.

Invention Described in Claim 20019. The steering device according to claim 1, whereinboth of two rudder plates face each other across the propeller, and can turn simultaneously around the propeller in thesame direction.

Operational Advantage of the Invention
0020. According to the steering device claimed in thepresent claim, both of two rudder plates face each otheracross the propeller, and turn simultaneously around thepropeller in the same direction. Two propellers become
simple Such as the same motion, and there is an advantagethat ship handling becomes easy. When a ship is faced in theright direction, the rudder on the right side is turned counterclockwise in front of the propeller, and the rudder on theleft side is turned counterclockwise similarly behind theUS 2017/008101.0 A1

propeller, hence a deflected water stream as an azimuthing
thruster is generated, consequently the advantage of excel
lent maneuverability can be obtained.
Invention Described in Claim 30021. The steering device according to any one of claim
1 or 2, wherein two rudder plates can turn simultaneously inthe same rotation direction, and can turn simultaneously ina direction opposite to each other, while both face each otheracross the propeller.

Operational Advantage of the Invention
0022. According to the steering device claimed in thepresent claim, two rudder plates can turn simultaneously inthe same rotational direction, and can turn simultaneously ina direction opposite to each other, while both face each otheracross the propeller. Each rudder can rotate around its own
steering shaft, independent from each other. In this case, likethe invention described in the present claim, not only highturning performance Such as a deflected water flow induced
by a thruster, but also the maximum stopping ability can beprovided, if both of them face with the propeller at the sametime, and rotate simultaneously around the propeller in thesame direction, or if both can constitute a plane intersecting
vertically behind the propeller at stopping motion. By a freerotating mechanism around the steering shaft, this stopping
motion is realized. In order to make this stopping action
work more effectively, smaller distances between two rudderplates and a rear end of the propeller are better. In thesteering device claimed in claim 1, since the number ofsteering shafts is 2, and a dedicated steering shaft is disposed
for two rudder plates, when the rudder plate is turned aroundthe propeller, a turning radius can be reduced, distances
between two rudder plates and a rear end of the propeller are
made to be close, and the effect of enhancing the stopping
ability is exerted.
Invention Described in Claim 4 The steering device
according to claim 3, wherein a rudder angle range exceeds
70 degree, and two rudder plates cooperate to almost blocka propeller slipstream.
Operational Advantage of the Invention
0023. When a structure that rotation of an electric servo
motor mechanism or a hydraulic motor mechanism isdirectly transmitted to the rudder via a bevel gear or without
via a gear So as to freely rotate is adopted, a movable range
is increased, and it becomes possible to apply a large rudder
angle. By turning the rudder plate around the propeller, toapply a large rudder angle in a range of a total 180 degree
or more of each rudder to turn to left and right 90 degree, it
becomes possible to utilize the rudder for stopping a ship,
and it becomes possible to maintain high turning perfor
mance. According to the steering device claimed in thepresent claim, since two rudder plates move so as to almost
block the propeller slipstream just at the back thereof at
emergency stop, the effect of maximizing a stopping force isexerted. An object of steering in this case is to shorten a time
when the propeller is freely rotating with its own inertia after
propeller driving is reset in the case necessitating emergency
stop, and to impose the reverse rotation of the propeller
promptly.

Mar. 23, 2017

Invention Described in Claim 50024. The steering device according to any one of claims
1 to 3, wherein the rudder plates are plate-like, and are
molded into a reverse L-letter type.
Operational Advantage of the Invention
0025 Rudder plates are suspended from the steering
shaft, and when rudder plates are integrally formed (monoblock) by welding, press processing, forging processing or
the like, a structure thereof becomes simple, and the advan
tageous effect is imparted in a point of the strength and theeconomical property. Integral (monoblock) molding of rud
der plates into a reverse L-letter type is most simple con
figuration, and the most advantageous effect is imparted ina point of the strength and economical property.
Invention Described in Claim 60026. The steering device according to claim 5, wherein
the rudder plates form a camber on a surface opposite to two
rudder plates to generate an advancing thrust.

Operational Advantage of the Invention
0027. The steering device described in the present claim
is characterized in that the rudder plate has a wing profile so
as to generate a thrust for pushing a ship hull forward by theeffect of a camber. By forming a camber inside a flow
between two rudder plates, a thrust pushing a ship hullforward can be generated. By enlarging cambers (a distance
between the mean line and chord line of a wing profile), thisthrust can be increased, but since a resistance is increased

simultaneously, there is an optimal camber. By increasing afront width of two rudder plates relative to a rear width, andtilting the rudder plates at 10 degree or less relative to a ship
center line, the steering device is optimized.
Invention Described in Claim 70028. The steering device according to claim 5, wherein
the rudder plates are plate-like, and at least one of an upper
portion or a lower portion of each of the rudder plates iscanted towards a steering shaft side.

Operational Advantage of the Invention
0029 When a part is canted towards a steering shaft side,a moment of inertia of the rudder plate around the steering
shaft can be more reduced, a driving power mechanism may
be smaller, and the effect of realizing energy saving ofoperation is imparted, as compared with the case of vertical
Suspension. An excessive gap between the propeller and thecamber is reduced, and a thrust is maintained.

Invention Described in Claim 80030 The steering device according to claim 1 or 5,
wherein the rudder plate has a limit of a chord length whichis allotted when one rudder plate is arranged at a propeller
slipstream, and a wing thickness of the rudder plate isthinner than a wing thickness allotted when one rudder plateis arranged at the propeller slipstream.

Operational Advantage of the Invention
0031. Two rudders are arranged on both sides of thepropeller at the time of direct traveling, and when one rudderUS 2017/008101.0 A1of twin rudder configuration has a rudder area Smaller thanthat giving the same rudder performance by one rudder, as
compared with single rudder configuration, and a chord
length is Smaller than that of the case of one rudder, an
aspect ratio of a wing is increased to suppress a fluid
resistance, and a high propulsive efficiency is obtained by athin small rudder.

Invention Described in Claim 90032. The steering device according to any one of claims
1 to 3, wherein the driving mechanism can perform by freely
Switching each mode of two-dependent modes in which two
rudder plates are turning-driven independently of each other,and a two-same direction mode in which two rudder plates
are both turning-driven in the same direction.

Operational Advantage of the Invention
0033. The invention described, in claim 9 is the steering
device in which, when the driving mechanism operates,
driving is enabled by dividing into two-dependent modes inwhich two rudders are driven independently of each other sothat a sufficient steering force can be generated even at a
Small vessel speed, and a two-same direction mode mainly
used at cruising in which two rudders are turned in the same
direction. In the case where a vessel speed is reduced, since
a water current speed and a discharge flow rate produced by
the propeller become small, and these become insufficientfor steering, the present inventors came to realize that, in aregion where a vessel speed is reduced, steering is different
from that at cruising. Then, according to the steering deviceof the present invention, in the steering device constituting
the invention described in claim 1, a basic frameworkcompensating for decrease in a steering power at a low speed
and, at the same time, realizing improvement in steering
performance and operating performance at cruising navigation is defined, as a steering category, for example, as thatwith a predetermined vessel speed being a boundary, at a
vessel speed in a range Smaller than the above vessel speed,
the steering shaft can be steered in a two-independent modein which left and right rudders have no constriction inde
pendently of each other.
0034. At the time of a low speed or at the time of a
cruising speed, by dividing a steering mode into one modeof two-independent modes or a two-same direction mode,
improvement in operating performance of the present invention, the steering ability at a low vessel speed, silent navi
gation, and the emergency stopping ability at Stoppage of aship are used depending on the situation, and the effectdepending on the situation is exerted.
Invention Described in Claim 100035. The steering device according to claim 9, whereinin the two-independent modes, the rudder plate on a broadside opposite to a veering direction can turn from aside of
the propeller to behind the propeller by rotation of thesteering shaft, and simultaneously with this, or before orafter this, the other rudder plate on a broadside on a veering
direction side can turn from aside of the propeller to behindthe propeller from a rudder angle of 90° until a rudder angle
takes a rudder angle of an interference limit with othermechanism, by rotation of the steering shaft.

Mar. 23, 2017

Operational Advantage of the Invention
0036. According to the present steering device, the effectof generating a thrust flow to aside of a broadside in a
veering direction is obtained. It is preferable that steerage ofthe rudder plate on a broadside opposite to a veering
direction remains at a rudder angle of 45° to 55°, and otherrudder plate can turn at a rudder angle from more than 90°
to a limit that does not interfere with other mechanism suchas the propeller and a screw shaft, for example, 105°.
Invention Described in Claim 110037. A method for steering the steering device according
to claim 10, comprising, in the two-independent mode,turning the rudder plate on a broadside opposite to a veering
direction from aside of the propeller to behind of thepropeller by rotation of the steering shaft,simultaneously with this, or before or after this, turning theother rudder plate on a broadside on a veering direction sidefrom aside of the propeller to behind of the propeller froma rudder angle of 90° until a rudder angle takes a rudder
angle of an interference limit with other mechanism, byrotation of the steering shaft
and after turning of the two rudder plates, further, increasing
the propeller rotational speed more than the propeller rota
tional speed at the ship condition with a straight course
keeping.

Operational Advantage of the Invention
0038 According to steering of the present invention, theeffect of increasing a flow velocity laterally will enhance thesteering ability Particularly when it is desired to let therudder work at a low vessel speed, according to the invention described in the present claim, there is obtained theeffect of imparting the thruster function to the rudder without
increasing a vessel speed, even when the more powerfulthruster function is exerted by the function of the propeller.
Effect of the Invention

0039. According to the present invention, at the time ofstraight cruising, the effect of imparting high propulsive
performance so that the rudder is not positioned at thepropeller slipstream is provided, and at the time of emer
gency stopping, a high stopping force due to a rudder angleof 90 degree relative to a ship hull at the propeller slipstream
is obtained, and the excellent effect of providing a steering
device which freely deflects and straightens a water streamof the propeller for turning to maintain turning performanceis exerted.

0040. According to the present invention, the further
excellent effect of providing a steering device which still
maintains the turning ability due to generation of a thrust
flow even at low speed navigation using the present device
and a method for steering the same is exerted, and further,a steering device which reduces a water cleaving noise of therudder and a method for steering the same are provided.
BRIEF DESCRIPTION OF THE DRAWINGS

0041 FIG. 1 A side view of a stern of a ship to which afirst embodiment of the present steering device is applied.
0042 FIG. 2 A plane view of the steering device inconnection with the first embodiment at the time of steering.
0043 FIG. 3 A front view of the same device.

US 2017/008101.0 A10044 FIG. 4. A perspective of the same device.
0045 FIG. 5 A perspective of a gear driving mechanismof the same device.

0046 FIG. 6A A perspective of a crank driving mecha
nism in connection with another embodiment of a driving
mechanism of the same device.

0047 FIG. 6B A perspective of a crank driving mecha
nism in connection with another embodiment of a driving
mechanism of the same device.

0048 FIG. 7 A plane view/a front view of the samedevice at the time of direct traveling.
0049 FIG. 8 A plane view/a front view of the samedevice at the time of Starboard turning.
0050 FIG. 9 A plane view/a front view of the samedevice at the time of larboard turning.
0051 FIG. 10 A plane view/a front view of the samedevice at the time of stopping.
0052 FIG. 11 A comparison view between uniaxial turning of the same device at the time of stopping.
0053 FIG. 12 An arrangement view of a rudder plate anda propeller of the same device.
0054 FIG. 13 A front view including a propeller at arudder plate portion of a steering device in connection witha second embodiment (the case where a lower portion of areverse L-letter type rudder plate includes an arc shape).
0055 FIG. 14 A side view of the same device.
0056 FIG. 15 A perspective of the same device.
0057 FIG. 16 A side schematic view of a stein of a shipusing a steering device in connection with a third embodi
ment.

0058 FIG. 17 A front schematic view of a rudder and asteering shaft of the same device.
0059 FIG. 18 A perspective schematic view of a rudder
and a steering shaft of the same device.
0060 FIG. 19 A horizontal sectional B-B schematic viewof a driving mechanism of the same device.
0061 FIG. 20 A plane schematic view/a front schematic
view of the same device at the time of starboard turning ina two-same direction mode.

0062 FIG. 21 A plane schematic view/a front schematic
view of the same device at the time of larboard turning in a
two-independent mode.
0063 FIG. 22 A front view including a propeller of arudder plate portion of a steering device in connection witha fourth embodiment (case where a rudder plate includes acanted portion).
0064 FIG. 23 A side schematic view of a stein of a shipusing a steering device in connection with a fourth embodi
ment.

0065 FIG. 24. A perspective of the same device.
0066 FIG. 25 A graphic view for comparing experimental, result of a steering force of each of a two-independentmode? a two-same direction mode of a model steering device
in connection with one embodiment of the present invention.
MODE FOR CARRYING OUT THE INVENTION

0067. Each embodiment of the present steering device
will be illustrated below. FIG. 1 is a side view of a stern ofa ship equipped with a steering device according to a first
embodiment (interior of a ship is a sectional view), FIG. 2
is a vertical view of the same steering device at the time ofsteering, FIG. 3 is a front view of the same steering device,and FIG. 4 is a perspective of the same steering device.

Mar. 23, 20170068 A steering device according to a first embodiment
comprises a propeller 20 attached to a rear end 11a of a stern
tube 11 of a ship hull 10, two rudder plates 30, and amechanism driving rudder plates 30 via a steering shaft 40.
Two rudder plates 30 are arranged on both sides of thepropeller 20. A cambered shape 31 is formed inside two
rudder plates 30. The Front ends of two rudder plates extend
forward of the plane formed by a propeller rotation plane.
The length of this protrusion can be extended forward insuch a way that it does not interfere with the ship hull 10, thelength depends on a wave created by a ship hull shape 10 andan economical vessel speed, and also depends on thestraightening water flow between the two rudder plates 30,
a use mode such as a forward thrust generated by the camber
31 of the rudder plates 30, and the water viscous resistance.
It may be optimized under these constraint conditions. The
two rudder plates 30 may be also rudder plates 30 having nocamber 31, and in this case aims at a low fluid resistance ofthe rudder plates 30 and the straightening effect on vortex
generation in the vicinity of a Stein.
0069. The rudder plates 30 exhibit a reverse L-letter plate
shape as shown in a front view 3, and are fixed at the steering
shaft 40 which is rotatably supported by the ship bottom
portion of the ship hull 10. At the time of steering; withrotation of the steering shaft 40, the rudder plates 30 turnaround the propeller as shown in FIG. 2. By turning of therudder plates 30 around the propeller as shown in FIG. 2
rather than rotation around a shaft on a plate surface. This
increases the deflected flow of the propeller slipstream, andturning performance is improved.
0070 The two rudder plates 30 have such a shape that athrust for impelling the ship hull 10 forward is generated by
the effect of the camber 31. By tilting the rudder plates 30
at 10 degree or less relative to a ship center line by making
a front thickness greater than a rear thickness, the rudderplates are arranged so as to have a suitable attack angle, they
have an optimal rudder plate shape having little resistanceon a flow in the vicinity of the stern of the ship hull 10 while
increasing a propeller efficiency, and an overall greater
forward thrust can be obtained.

0071. Upon rotation of the steering shaft 40 by thedriving mechanism, shown in FIG. 1 and FIG. 5, eachdriving shaft is freely rotated using a bevel gear 120 and anelectric servomotor mechanism 130. When the two rudders

are turned so as to be closed simultaneously from a direction
seen from a ship stein 11 of FIG. 1 toward a center, they canbe positioned as shown in FIG. 2 and FIG. 10, and can beused as a brake at the time of an emergency. In addition, theelectric servomotor mechanism 130 exerts the same effect in

the case of a hydraulic servomotor mechanism, or a mecha
nism of a combination of an electric servomotor and ahydraulic servomotor.
(0072 FIG. 7 shows arrangement of the rudder plates 30
when travelling straight ahead, FIG. 8 shows the turningstate of the rudder plates 30 at the time of right turning, FIG.
9 shows the turning state of the rudder plates 30 at the timeof left turning, and FIG. 10 shows the turning state of therudder plates 30 at the time of stopping if the two shafts canbe driven independently by the driving mechanism as shownin FIG. 5, turning positions from FIG. 7 to FIG. 10 become
possible, it results in a steering device which affords a highstopping force by imparting a rudder angle of 90 degree
relative to the ship hull 10 by the propeller slipstream at thetime of emergency stopping, while providing the effect that

US 2017/008101.0 A1

the rudder plates 30 are positioned on both sides of thepropeller to impart a high propulsive efficiency without
positioning in the propeller slipstream when straight cruis
ing, and freely deflects and straightens a water stream of thepropeller 20 in order to turn a ship, and assures good turning
performance. FIG. 11 shows an possible position of a rudderplate 230 which has turned around a steering shaft 240 at thetime of emergency stopping in the case where the steering
shaft is uniaxial, and a possible turning arc 230 of the rudderplate in this case is additionally shown in FIG. 20. In the caseof two steering shafts, since the rudder plate turning radius
becomes Small by each turning, when two steering shafts
each have a turning mechanism, the rudder plate 230 can
approach a position closer to the propeller as compared withthe case of a one steering shaft, a rudder angle can approachvertically relative to a propeller screw shaft, and the braking
effect can be maximized.

0073 FIG. 6A and FIG. GB show other version in which
the gear driving mechanism of FIG. 5 is a crank mechanism.
As shown in FIG. 6A, by rotating the steering shaft 40 by amechanism of a hydraulic cylinder 100 and a crank mecha
nism 110, two rudder plates 30 can be freely turned. This isan embodiment in which oil pressure is a power source, andsince an oil pressure system is frequently used in a ship it canbe utilized for this purpose so the driving device in connec
tion with the present invention can be realized at a smaller
COSt.

0074 According to the steering device shown in FIG. 6B,
the crank mechanisms driving two steering shafts are connected, and two steering shafts are rotated by conjunctive
synchronization. A conjunctive synchronous rotation of twosteering shafts by crank mechanisms has an advantage thatsteering becomes easy, and a steering device mechanism
may be also simple. In the case of this embodiment, tworudder plates do not cooperatively make a movement so as
to almost block the propeller slipstream, and increase in a
stopping force in the case of Sudden stop cannot be obtained,
but by arranging two rudder plates on both sides of thepropeller at the time of direct traveling, two effects ofcapable of turning rudder plates to the slipstream side of thepropeller at the time of rotation of a ship while obtaining
high propulsive performance, and obtaining high turning
performance can be achieved.
0075 FIG. 13 is a front view including a propeller of arudder plate portion of a steering device in connection witha second embodiment, FIG. 14 shows a side view of thesame, and FIG. 15 shows a perspective of the same. The
second embodiment is different from the first embodiment in

the following points.
0076. The second embodiment is the case where an arc
shape is included at a lower portion of the reverse L-letter
type rudder plate of the first embodiment, and provides theeffect of realizing the effect imparted by the first embodi
ment by requiring a smaller steering device driving mecha
nism. The second embodiment will be illustrated below.

0077. In the second embodiment, a steering shaft 40 fromwhich a rudder plate 30 is suspended, is arranged laterally
from a center of a propeller 20 at a distance D, and is fixed
on a ship bottom 10. Herein, D is a numerical value smaller
than a propeller radius R. An upper portion of the rudderplate 30 is constructed into a reverse L-letter type, and therudder plate 30 suspended from the ship bottom 10 isisolated from the steering shaft, center by R-D+C. C. is a gap
between a propeller rotation radius and the rudder plate. A

Mar. 23, 2017

central portion of the rudder plate 30, that is, a portion lower
than a horizontal line passing through a propeller centershaft is a 4 arc, and is configured to be slightly isolated
from, and opposite to the rudder plate which is similarly
Suspended from an opposite steering shaft. Herein, parameters of R, D and C. are optimally designed in view of various
elements such as propeller performance, rudder perfor
mance, a ship type and the like.
(0078. In order to turn the reverse L-letter type rudderplate 30 around the steering shaft 40 with a horizontal
portion of a L-letter type being an arm, the rotational inertia
moment becomes great in proportion to a length of an arm
to be turned, as compared with the case where the portion isrotated around the steering shaft in a form of inclusion of thesteering shaft in a rudder plate Surface in the conventional
steering device. Then, as a power device driving the steering
shaft, a larger shaft than before becomes necessary, anddisadvantage arises in respect of a combination with a ship
type, and an economic efficiency, in Some cases. Even in
Such a case, if it becomes possible to reduce the inertia
moment as much as possible so that a smaller steering device
driving power Source may be used, a more preferable
steering device excellent in energy saving and an operational
efficiency can be provided. Herein, since the inertia moment
I of a mass point in at a distance r from a rotation center
satisfies:
I=nr2

equation (1),concerning a portion lower than a horizontal axis line of apropeller central line of a reverse L-letter type rudder plate
portion of the steering device in connection with the first
embodiment shown in FIG.3, when a part of the rudder plateis a /4 arc shape as in FIG. 13 showing this embodiment, thedistance from the steering shaft rotation center is reduced
and, therefore, the inertia moment is reduced in proportion
to the square thereof.
0079 Since a necessary driving force is in proportion to
the inertia moment, and a driving energy is also in proportion to the inertia moment, in the steering device in accor
dance with the second embodiment shown in FIG. 13, it

results in that a smaller power mechanism is enough, andenergy saving is realized. Energy saving is one object of thepresent invention, and this satisfies the aims of the invention.
0080. In the second embodiment, a camber 31 is formed
on a Surface opposite to two rudder plates, that is, inside therudder plates (FIG. 15). The camber aims at improving
propulsive performance by a thrust generated by the wing
shape. Although the camber 31 is also formed in the first
embodiment, in the rudder plate of the steering device inaccordance with the second embodiment, by making arudder plate lower portion of a reverse L-letter type a /4 arc
shape, the rudder plate becomes closer to the propeller, andsince a water flow velocity in the vicinity of the camber isincreased, the secondary effect that a thrust becomes greater,
as it would with a fixed nozzle and an improvement inpropulsive performance is greater can be expected.
I0081. Then, a third embodiment of the steering device
will be illustrated. FIG. 16 is a side view of a stern of a ship
equipped with the steering device in accordance with thethird embodiment (the interior of a ship is shown by asectional view), FIG. 17 is a front view of the same steering
device, and FIG. 18 is a schematic view of a perspective ofa rudder portion of the same steering device.

US 2017/008101.0 A10082 Also in the third embodiment, likewise the first
embodiment, the steering shafts 40 are each arranged at a
distance D smaller than a radius R of a propeller 20 from ascrew shaft center 5, a rudder plate surface of the rudderplate 30 facing the propeller 20 is vertically arranged at a
positive minimum distance a from an outer edge of thepropeller 20 having a radius R on a rotation plane of thepropeller 20, and the rudder plate surface is characterized inthat a turning radius is defined by a distance in which a
radius r is represented by the following equation:from aside of the propeller 20 to a slipstream side of thepropeller 20 by rotation of two steering shafts 40, the rudderplate surface is turned at a radius r from aside of thepropeller to be downstream of the propeller by rotation of
the steering shaft, the rudder is placed on both sides of thepropeller, two rudders each have the steering shaft, thesteering shaft is attached off-center inside the rudder plate,and each steering shaft rotates independently. This configu
ration defines that a rudder face of the rudder plate forms aface isolated from the steering shaft, and a rotation axis by
the steering shaft is not present in line with the rudder face,and makes the meaning of turning clear and, at the sametime, defines that the rudder plate is positioned laterally
isolated at a distance a from the propeller rotation Surface
outer edge. The steering shaft has a more compact configu
ration that it is arranged on an inner side than a propeller
radius, and makes clear a difference between rudder platearrangement of the conventional steering device of two
rudders (see FIG. 2 of Patent Literature 1). That is, this is apreferable embodiment in a point that a turning radius isreduced, a turning moment of the rudder plate can be
reduced in proportion to the square of a turning radius r, andit becomes possible to miniaturize a driving mechanism anda power mechanism, and consequently, this leads to energy
saving which is an object of the present invention.
0083. In this way, concerning definition between parameters, even when a turning radius r is more reduced, if achord length of one rudder plate is a sufficient length forcovering a propeller radius R, it is preferable that the turning
radius r is around a half of the propeller radius R, a size of
one rudder plate is defined from a relationship with a turning
radius of the rudder plate in view of a chord length of therudder plate covering the propeller radius R, and as a result,harmonization with reduction in the turning moment of thepropeller is obtained, being preferable.
0084. The size of two rudder plates which are arranged
on both sides of the propeller is such that one rudder plateof twin rudder configuration can be reduced compared to therudder area which imparts the same performance of a single
rudder. When a height of the rudder is the same, that is,conceptually, a rudder width in a vessel axis direction, achord length in the case of a wing can be smaller than thatof single rudder, and in this case, an aspect ratio of a wing
becomes greater. Since the wing having a greater aspect ratio
Suppresses reduction in a lift force and increase in a fluid
resistance due to wraparound from a wing end, a small
rudder satisfies a required specification, a width of therudder is reduced, a rudder face which merely undergoes a
Small fluid viscous resistance is formed, and a high propul
sive efficiency is obtained at the time of cruising, as com
pared with single rudder which imparts the same rudder
performance.

Mar. 23, 2017

I0085. Upon rotation of a steering shaft 40 by a driving/power mechanism 90, the steering shaft 40 is directly rotatedby a rotary vane-type hydraulic motor 140 (see FIG. 18).
This results in that two rudder plates 30 freely turn aroundthe propeller 20. That is, as shown in a sectional view of adriving mechanism shown in FIG. 19, when a hydraulic oil
is supplied into hydraulic chambers 132, 133 which arepartitioned with a vane 134 of a vane-type hydraulic motor
140 by a power mechanism, the differential force works on
the vane 134 due to a pressure difference between left andright hydraulic chambers 132, 133 partitioned by the vane,
and a rotor 130 is differentially operated. It results in that thesteering shaft 40 directly connected to the rotor 130 freely
turns the rudder plate 30 connected to the steering shaft 40.
In hydraulic chambers 132, 133, a part of a semi-cylindricalspace is partitioned with the vane 134, and since the vanepartitioning this can be rotated in a range of approximately
180°, a range exceeding 90°, for example, a wide rudder
angle range can be supported.
I0086 According to the third embodiment as stated above,
the power mechanism of the driving mechanism is a Vane
type hydraulic motor mechanism 140, this is directly boundto the steering shaft 40 as a dedicated mechanism for eachsteering shaft 40, and when rudder plates 30 are turned
towards a center from a direction seen from a stern 11 of

FIG. 16 so as to be closed simultaneously, two rudders canbe also emergency-braked at the time of emergency as in
FIG. 10, rudder plates can be positioned at a slipstream at
more than 90° up to maximally 105°, and a breaking power
can be maximized. In addition, the driving mechanism 90
may be any mechanism as far as it is a separate power
mechanism and driving mechanism 90 which can indepen
dently drive two steering shafts 40 freely, and may directly
drive the steering shafts 40 using an electric servomotor
mechanism as a power source, or may drive the steering
shafts 40 via a speed reduction mechanism, and if necessary,vertical/horizontal plane conversion of a rotating plane may
be performed depending on arrangement configuration ofeach instrument.

I0087. When the driving mechanism 90 is driven, it ispreferable that the steering shaft can be steered by switching
into at least two steering modes of a two-independent mode
and a two-same direction mode. Hereinafter, according to asteering mode, motion of the rudder plate in the third
embodiment will be illustrated using schematic views of aplane view/a front view of FIG. 7, FIG. 8, FIG. 20 and FIG.
21. A mechanism and a steering method appropriate tosteering property of the steering mode are as follows.
I0088 At the time of veering steering in the two-same
direction mode, basically, rudders are symmetrically steeredaround the propeller, and in the case where a ship is facedin the right direction, when the rudder on a right side is
moved counterclockwise in front of the propeller, and therudder on a left side is turned, similarly counterclockwise atbehind of the propeller, a rightward deflected slipstream(flow F shown with two-dot chain line of FIG. 20) is
generated from a counter current (flow FR shown with
two-dot chain line FIG. 20), and the effect of obtaining thedesired steering property is exerted.
I0089. In the two-independent mode, left and right rudders
are independently steered. Steering in this independent
mode is determined by a person, for example, a chief
navigator, or a master of a ship. For example, since when aship speed is reduced, a current speed and a discharge flowUS 2017/008101.0 A1

rate generated by the propeller are reduced, and become
insufficient for steering, the rudder is steered in the two
independent mode being a steering mode corresponding toship handling at the time of a low speed. On the other hand,for example, at a cruising speed in a range greater than apredetermined ship speed, performance is maintained bysteering Suitable for a cruising speed according to thetwo-same direction mode in which left and right rudders
take a rudder angle opposite to each other. Even in one
steerage, this is a steering device which enables different
steering by either steering mode of the two-independent
mode or the two-same direction mode.

0090 FIG. 21 shows the turning state of rudder plates 32,
33 at the time of steering in a starboard direction at the timeof undocking, in which a side thrust flow is generated by thetwo-independent mode of the invention in connection withthe third embodiment. In the two-independent mode, arudder plate 33 on a port side opposite to a starboard veering
direction is turned from aside of the propeller 20 to adownstream of the propeller by rotation of the steering
shafts 42 at a first stage, and at the same time, the otherrudder plate 32 on a starboard side is turned from aside of
the propeller 20 to the downstream of the propeller byrotation of the steering shaft 41, the rudder plate is turning
driven so as to take a rudder angle of 90°, and jointly as anext stage, the propeller rotational speed is increased thanthat at the time of straight travelling.
0091 Even in the two-independent mode, at a low ship
speed region, the rotation number of the propeller is Suppressed low in normal steering, and when a propeller water
stream is at a low speed, since only a weak deflected flow is
generated, a Sufficient turning power is not obtained. Then,in the case of starboard veering ship handling generating athrust flow in the two-independent mode, the rudder plate 33
on a port side opposite to a veering direction is turned, forexample, by 45° from aside of the propeller to the down
stream of the propeller by rotation of the rudder shaft 42 at
a first stage and, at the same time or as a second stage, when
the other rudder plate 32 on a starboard side is turned fromaside of the propeller to the downstream of the propeller byrotation of the rudder shaft 41 to take a large rudder angleof 90° to 105°, a flow is concentrated from a port to apropeller central side by the rudder plate 33 which hasturned by 45°, a pressure at a central portion becomes high,on the other hand, a propeller water stream which is dis
charged backward from a starboard right semicircle regionis blocked, by the rudder plate 32 taking a rudder angle of90°, a flow must be toward a lateral, but is pushed by apressure near a central portion of the propeller 20, and a flow
to a lateral of a starboard in a veering direction (right) is
generated. Then, ship handling similar to a thruster becomes
possible by discharge of a lateral flow to the just beside aveering direction. At the time of porting the helm, left andright are inverted.
0092. Meanwhile, since almost all of a propeller water
stream flows laterally, even when the propeller rotational
speed is increased, a forward vessel speed is not muchincreased. On the other hand, when the propeller rotational
speed is increased, since a water stream flowing laterally
becomes fast, and a flow rate is also increased, a ship control
force in the transverse direction is dramatically enhanced.
That is, when veering steering in a two-independent mode isperformed, as a third stage, the effect of dramaticallyenhancing the steering ability by increasing the rotation

Mar. 23, 2017

number of the propeller 20 is obtained. In this case, evenwhen the propeller rotational speed is increased, a speed ofa ship is not increased, and the rudder works as a thruster.
0093. At the time of veering in the two-same directionmode, the rudder plate on a side opposite to a veering
direction is turned from aside of the propeller to the down
stream of the propeller by rotation of the rudder shaft, andselectively, the other rudder plate is turned from aside of thepropeller to the propeller upstream side by rotation of theother rudder shaft. FIG. 20 shows the turning state of therudder plate 30 at the time of the two-same direction mode:
starboard turning, and motion becomes left and right inversion to this at the time of porting the helm. In this case, as
shown in FIG. 20, there is an advantage that, when both of
the two rudder plates 30 face each other across the propeller
20, and are turned around the propeller 20 in the same
direction, two propellers take the same motion, becoming
simple, and ship handling becomes easy. When a ship isfaced in the right direction, the rudder on a right side is
moved counterclockwise in front of the propeller, and therudder on a left side is turned counterclockwise similarly atbehind of the propeller, thereby, a deflected water stream ina rudder angle direction can be generated, and the ship isturned in a rudder angle direction by the counteraction.
0094. At the time of veering in the two-same directionmode, the rudder plate on a side opposite to a veering
direction, for example, in the case of starboard helm, the portside rudder is turned from aside of the propeller to thedownstream of the propeller by rotating the rudder shaft ofa port side, and in the case of portside helm, the starboard
side rudder is turned from aside of the propeller to the up
steam of the propeller by rotating the rudder shaft of a
starboard side, deflects a propeller slipstream along a large
rudder angle, provides high turning performance by a rudder
force due to a counterforce. In this case, the rudder force

contribute to steering performance by adding the turning
moment to the ship because the rudder is positioned suffi
ciently isolated from a ship center line. Selectively, the otherrudder plate is turned upstream of the propeller from asideof the propeller by rotating the rudder shaft, the rudder plateis arranged at a position Sufficiently isolated from the ship
center line as compared with a conventional rudder, andturning of one rudder plate in front of the propeller imparts
the maneuverability by a counterforce received from a water
stream along the vessel, and another rudder plate turningbehind the propeller changes a direction of a water stream ofthe propeller slipstream to contribute the ship turning ability.
Since the rudder is located at a position sufficiently isolated
from the ship center line, the present steering device pro
vides the rudder force which contribute to steering perfor
mance by adding the turning moment to the ship.
(0095. At the ahead condition of the ship with the twosame direction rudder plate mode, both rudder plates arearranged at aside of the propeller. Since the resistancecomponent, which is originated from a rudder behind apropeller, can be eliminated, the propulsive efficiency of aship is increased, and higher propulsive performance can beprovided compared with ship with a rudder located in abehind of a propeller. FIG. 7 shows the steering mode of therudder in the case of ahead going. Regardless of a steeringmode, at the ahead condition of the ship, the rudder plate isarranged like the rudder plate 30 shown in FIG. 7. An
upward bald arrow shows a steering direction of a ship, andan upward fine arrow of a one-dot chain line schematicallyUS 2017/008101.0 A1

indicates flow of water. That is, in the case of straight course
keeping ship handling, the two rudder plates 30 are retainedlaterally on both sides of the propeller 20. At the ahead
condition of a ship, two rudders are maintained on both sidesof the propeller parallel with a ship axis. Since a propeller
water stream is not obstructed by the rudders, a rudder dragreceiving from the flow is reduced as compared with exist
ing two rudders arrangement behind the propeller, andhigher propulsive performance can be provided. In this case,since the rudder is not placed in a high speed rotation flowof the propeller slipstream, a noise emitted from the propeller and rudder can be eliminated, and the additional effectof enabling calm cruising is also obtained, and this effect is
Suitable, particularly, for patrol boats, and military ships.
0096. In stop maneuver, when the propeller is stopped, at
a next stage, a rudder angle exceeding 70 degree is taken in
the two-independent mode, and the two rudder plates cooperate to almost block the propeller slipstream. Selectively;
thereafter, the propeller may be reversed. Herein, taking arudder angle exceeding 70 degree is preferably to take arudder angle of 90°, or a rudder angle of up to 105 degreeexceeding this, In rudder plate arrangement shown in FIG.
10, at the time of emergency stop, two rudder plates almost
block the propeller slipstream near the back of it to maxi
mize a stopping power. An object of this steering is to reset
propeller driving, and thereafter, shorten the time during
which the propeller rotates by the inertia to enable thepropeller to reversely rotate early, in the case where sudden
stop is necessary. When it is necessary to reversely rotate thepropeller like this, reverse rotation of the propeller can be
stopped to accelerate reverse rotation of the propeller. In
addition, when both rudder plates are turned to an upstreamside 45° forward as a speed reducing stage at the time ofinitial motion of stop maneuver, both rudder plates receivea water stream at a vessel speed, and a speed of a ship canbe reduced by the counterforce thereof.
0097. When the steering device 1 in connection with thethird embodiment shown in FIG. 18 is used, since two shafts

each are independently driven by a hydraulic motor mecha
nism 140, and free turning from FIG. 20 to FIG. 21 becomes
possible, it results in that there is provided the steering
device 1 that, at the time of straight cruising, rudder plates
30 are positioned on both sides of the propeller 20 without
positioning at the propeller slipstream, the effect of imparting a high propulsive efficiency is provided, and at the sametime, at the time of emergency stopping, a rudder angle
range exceeds 70 degree, the two rudder plates cooperate toturn around the propeller so as to almost block the propeller
slipstream, a rudder angle, for example, of 90 degree to aship hull 10 is imparted at the propeller slipstream to obtaina high stopping power, a water stream of the propeller 20 isfreely deflected and straightened for turning a ship tomaintain turning performance.
0098. A fourth embodiment of the steering device is thecase where a lower portion of the reverse L-letter typerudder plate of the third embodiment is folded to a propellerside, and a L-letter corner is also folded, and effect ofrealizing the effect imparted by the first embodiment by a
Smaller steering device driving mechanism is provided. This
will be illustrated below.

0099 FIG. 22 is a front view including a propeller of arudder plate portion of the steering device in connection
with the fourth embodiment, FIG. 23 is a side view of theMar. 23, 2017

same, and FIG. 24 shows a perspective of the same. The
fourth embodiment is different from the third embodiment in

the following points.
0100. When a reverse L-letter type rudder plate 30 isattached inside off-center from the rudder shaft 40 with ahorizontal portion of a L-letter type being an arm, ascompared with the case of an embodiment in which it is incenter of the rudder shaft in a rudder plate plane in theconventional steering device, the rotation inertia moment
becomes in proportion to the square of a turning radius, agreat power mechanism for driving the rudder shaft isrequired, and disadvantage can occur from a view point ofcompatibility with a ship shape, and the economy. If theinertia moment can be reduced as much as possible so thata small steering device driving power source may be used,a preferable steering device excellent in energy saving canbe provided. When a lower portion of the reverse L-letter
type rudder plate of the steering device in connection withthe first embodiment shown in FIG. 4 is folded to a propellerside, and a mass point distance from a rudder shaft rotation
center is reduced by chamfering of a L-letter corner, theinertia moment is reduced, a driving force may be a smaller
motive power mechanism, and energy saving which is anobject of the present invention is realized. When the rudderplate has a plate-like form similar to a reverse L-letter type
like this, this is most simple configuration among a form of
the rudder plate in a point of integral formation, and is mostadvantageous in regards of the strength and the economy.
Integral formation may be by any of processing Such as
welding press processing, forging processing and the like,and assembling Such as bolting, riveting and the like. In thiscase, folding has the effect of increasing rigidity, decreasinga plate thickness, and further reducing the inertia moment.
0101 FIG. 25 shows a graphic view of experimental
result of the steering effort of the present invention model
implementation product device in the case where steering at
the time of the two-independent mode of a model steering
device in connection with the fourth embodiment is imple
mented. Based on the following specifications, a relationshipbetween a vessel speed and a rudder force was obtained by
an experimental model.
<Specifications Around Rudder of Model Steering Device,
Unit mm0102 Propeller radium: 2400, rudder height: 3050, chord
length: 1500 at a height of 1950 or more from lower end,
1150 at a lowest end, a chord length linearly decreasing
towards a lower end, maximum plate thickness: 150, Steering shaft central position: 600 from ship axis center, steering
shaft diameter: 340<Results(0103 FIG. 25 shows a relative rudder force of a model
rudder in a longitudinal axis relative to a model ship relative
vessel speed in a transverse axis. It is seen that, in the
two-same direction mode, the rudder force is increased byabout 20% as compared with the conventional single rudder,and in the two-independent mode, the rudder force isremarkably improved by 50%, particularly, in a low speed
region. Effectiveness of the present invention which changes
a rudder Steering method at the time of the two-same
direction mode and at the time of the two-independent mode,
and is provided with a driving mechanism of the rudder
Supporting this change is confirmed. When steering in the
two-same direction mode is also implemented in a low speedUS 2017/008101.0 A1

region, the steering effort is inferior by 20% to the conventional model, and Superiority of a steering method of par
ticularly setting up a steering method in the two-independent
mode using the device in connection with the present
invention can be confirmed.

0104. As described above, embodiments in connection
with the present invention have been illustrated, but thepresent invention is not limited to Such embodiments, andcan be implemented by various modifications in Such arange not departing from the gist of the present invention.
INDUSTRIAL APPLICABILITY

0105. The present invention can be applied to a steering
portion of Surface ships, particularly, big ships, domestic
vessels and patrol boats requiring quick ship handling evenat a low speed.
DESCRIPTION OF REFERENCE NUMBERS

0106]
0107
0108
0109
0110
0111

0112
0113
0114
0115
0116)
0117
0118
0119)
0120

1 Steering device
2 Propulsive device
5 Screw shaft
10 Ship hull
11 Stern tube
12 Stern

20 Propeller
30 Rudder plate
31 Camber
40 Rudder shaft
90 Driving/Power mechanism
100 Hydraulic cylinder
110 Crank mechanism
120 Bevel gear
130 Electric servomotor mechanism or hydraulicmotor mechanism

0121 140 Rotary vane-type hydraulic motor mechanism
1. A steering device having a driving mechanism rotatinga steering shaft, and a power mechanism driving this,wherein the steering shaft is biaxially arranged to rotate on
both sides of a screw shaft upper portion, each steering shaft
connects and Suspends a rudder plate from the upper portionof the plates, and two rudder plates can be turned from asideof a propeller to a downstream of the propeller by rotationof the two steering shafts.
2. The steering device according to claim 1, wherein bothof two rudder plates face each other across the propeller, canturn simultaneously around the propeller in the same direction.

3. The steering device according to claim 1, wherein two
rudder plates can turn simultaneously in the same rotation
direction while both face each other across the propeller, andtwo rudder plates can turn simultaneously in a direction
opposite to each other,Mar. 23, 2017

4. The steering device according to claim 3, wherein arudder angle range exceeds 70 degree, has two rudder plates
which cooperate to almost block a propeller slipstream.
5. The steering device according to claim 1, wherein therudder plates are plate-like, can be formed into a reverse
L-letter type.
6. The steering device according to claim 5, wherein therudder plates are characterized in that they form a camber on
a Surface opposite to two rudder plates, can generate an
additional forward thrust.

7. The steering device according to claim 5, wherein therudder plates are plate-like, and at least one of the upper orlower portions is canted towards a steering shaft side.
8. The steering device according to claim 1, wherein therudder plates has a limit of a chord length, which is allottedwhen one rudder plate is arranged at a propeller slipstream,
and a wing thickness of the rudder plate is Smaller than awing thickness allotted when one rudder plate is arranged at
the propeller slipstream.
9. The steering device according to claim 1, wherein thedriving mechanism can perform by freely Switching eachmode of a two-independent mode in which two rudder plates
are turning-driven independently of each other and a twosame direction mode in which two rudder plates are both
turning-driven in the same direction.
10. The steering device according to claim 9, wherein in
the two-independent mode, the rudder plate on a broadside
opposite to a veering direction can be turned from aside of
the propeller to behind of the propeller by rotating thesteering shaft, and simultaneously with this, or before orafter this, the other rudder plate on a broadside on a veering
direction side can be turned from aside of the propeller tobehind of the propeller from a rudder angle of 90° until arudder angle takes a rudder angle of an interference limit
with other mechanism, by rotating the steering shaft.
11. A method for steering the steering device according toclaim 10 comprises the two-independent modes turning therudder plate on a broadside opposite to a veering direction
from aside of the propeller to behind of the propeller byrotating the steering shaft, simultaneously with this, orbefore or after this, turning the other rudder plate on abroadside and veering direction side from aside of thepropeller to behind of the propeller from a rudder angle of
90° until a rudder angle takes a rudder angle of an interference limit with other mechanism by rotation of the steering
shaft, and after turning of the two rudder plates, further,increasing the propeller rotational speed more than thepropeller rotational speed at the time of a ship condition withstraight course keeping.
k

k

k

k

k