Ice-breaking apparatus for ships and barges for operation on icy waters

An ice-breaking apparatus for use in ships and barges operating on icy waters, including nozzles for jetting high pressure fluid, is disclosed. By impinging force or cavitation caused by the high pressure fluid jetted from the nozzles, grooves or cracks are formed on an ice floe, and then, the ice floe is broken from these grooves or cracks by the hull. This ice-breaking apparatus facilitates breakage of ice floes or the like, and when this ice-breaking apparatus is attached, ships or barges for operation on icy waters can be built without increasing dimensions or propulsion powers particularly for navigation on icy waters. The ice-breaking apparatus includes echo distance measuring apparatus for automatically controlling and maintaining the nozzles at optimum positions from the ice-surface.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
The present invention relates to an ice-breaking apparatus for facilitating 
navigation of ships or barges on icy waters. 
(2) Brief Description of the Prior Art 
Icebreakers or iceboats have been generally used as vessels navigating on 
icy waters. In vessels of this type, the kinetic energy of the vessel is 
utilized for breaking ices and in order to obtain a high ice-breaking 
capacity, therefore, it is necessary to increase the kinetic energy by 
enlarging the hull or enhancing the power of the main engine and it also 
is necessary to improve the structure and shape of the hull per se so that 
the kinetic energy can be transmitted effectively at high efficiency to 
ices to be broken. Accordingly, attempts have heretofore been made to 
attain improvements in the foregoing points. In practice, however, in 
building ships or vessels of this type, various economical and other 
limitations are imposed on increse of dimensions of the hull or 
powering-up of the engine, and therefore, no satisfactory ice-breaking 
capacity can be obtained in many cases. 
In general, the ice-breaking operation is divided in two types; namely, 
continuous ice breaking applied to relatively thin ices and charging 
ice-breaking applied to thick ices. Continuous ice breaking is performed 
by thrust of a ship and a knife edge mounted on the bow. Charging ice 
breaking is performed by repeating an approach run along a certain 
distance and a collision against ice. 
These conventional ice-breaking methods, however, are very inefficient. For 
example, in case of continuous ice breaking, the advance speed is 
ordinarily lower than several knots though the speed is changed to some 
extent depending on the thickness of ice or the capacity of the ship, and 
in case of charging ice breaking, the opening distance by one charging 
operation is only in the range of from several meters to several hundred 
meters. Accordingly, the ice-breaking efficiency is low, especially in 
case of charging ice breaking, and further, there is always involved a 
risk that during the ice-breaking operation, the ship will be blocked by 
ice and will not be allowed to escape. 
OBJECTS OF THE INVENTION 
The present invention is to eliminate the foregoing defects involved in 
conventional continuous ice breaking and charging ice breaking by 
icebreakers or iceboats. 
It is therefore a primary object of the present invention to increase the 
efficiency of continuous ice breaking or charging ice breaking in 
icebreakers or iceboats navigating on ice waters and barges (inclusive of 
pushers and tugboats) for operation on ice waters without increasing 
dimensions of the vessels or powers of main engines thereof. 
Another object of the present invention is to moderate dangers involved in 
charging ice breaking and ensure efficient and safe navigation. 
Still another object of the present invention is to provide a distance 
measuring device for automatically controlling and maintaining the fluid 
nozzles at optimum positions from the ice-surface. 
Other objects and advantages of the present invention will become apparent 
from the following detailed description. 
BRIEF SUMMARY OF THE INVENTION 
In accordance with the present invention, the foregoing objects can be 
attained by an ice-breaking apparatus for ships and barges for operation 
on icy waters, including nozzles for jetting high pressure fluid to ice to 
break ice, wherein a rotatable turret is mounted on the bow and nozzles 
are disposed on an extensible arm attached to said turret or nozzles are 
disposed on the bow portion, either independent of or in combination with 
said nozzles disposed on the extensible arm. 
According to the present invention, cracks or grooves are formed on ice by 
the action of high pressure fluid, for example, high pressure water, 
jetted from the above-mentioned nozzles, whereby the kinetic energy need 
not be especially increased. Further, since ice is broken only at 
necessary parts or portions thereof, the operation efficiency can be 
remarkably enhanced. Moreover, since the hull intrudes into broken or 
cracked ice, damages on the hull by the ice-breaking operation can be 
effectively prevented from occurring, and in case of charging 
ice-breaking, the foregoing risk of stalling in ice can be eliminated.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
FIG. 1 illustrates the state where ice is broken according to the customay 
continuous ice-breaking method. As is seen from FIG. 1, a vessel is 
allowed to advance through generation and development of cracks on an ice 
floe and breakage of the ice floe. Accordingly, if a state promoting 
breakage of an ice floe is artificially realized in advance or conditions 
for bringing about this state with ease are produced, it will be possible 
to perform the ice-breaking operation more readily and easily than in the 
conventional methods. 
As means for generating cracks in ice floes, as pointed out hereinbefore, 
there has been used a knife edge mounted on the bow. In the present 
invention, an ice-breaking nozzle for jetting high pressure fluid is used 
instead of such conventional knife edge. One of characteristic features of 
the present invention resides in the use of such nozzle. 
This ice-breaking nozzle may be disposed directly on the bow or it may be 
supported on an extensible arm mounted on a turret device disposed on the 
hull. In principle, the present invention includes these two features as 
main embodiments. 
The present invention will now be described in greater detail in 
conjunction with the accompanying drawings. 
Referring to FIG. 2 illustrating the structure of the bow portion 2 where a 
number of nozzles 1 are arranged, the nozzles 1 are embedded in the bottom 
portion of a groove 3 formed on the bow 2 so that damages of the nozzles 
by direct contact or collision with ice can be prevented. 
High pressure fluid, for example sea water or fresh water stored in the 
ship, which has been pressurized, is jetted from these nozzles, whereby 
cracks become formed on ice. Accordingly, the ice-breaking efficiency is 
enhanced and the sailing speed is elevated. In case of charging 
ice-breaking, if cuts are formed at the first charging, ice is readily 
broken at the second charging, and hence, the ice-breaking capacity can be 
remarkably enhanced. 
In the embodiment shown in FIG. 2, ice is thrust down by the bow portion 
and thus broken. On the other hand, in the embodiment shown in FIG. 3, ice 
is raised up from below and thus broken. Namely, in the embodiment 
illustrated in FIG. 2, nozzles are arranged so that cracks are generated 
from the upper portion of ice 4 and in the embodiment shown in FIG. 3, 
nozzles are arranged so that cracks are generated from the lower portion 
of ice 4. 
When nozzles are disposed in the bow portion as shown in FIGS. 2 and 3, in 
order to maintain an optimum distance between each nozzle 1 and ice 4 and 
prevent damages of the nozzles at the time of collision, the nozzles are 
disposed at a position inner than the position of the shell plating in the 
bow portion and they are surrounded by electrically heated panels. As 
means for maintaining a certain distance between the nozzles 1 and ice 4, 
in the embodiments shown in FIGS. 2 and 3, a groove 3 is formed. 
Alternatively, an optimum distance can be maintained by depressing only 
parts of the bow near the nozzles 1. 
FIG. 4 illustrates an embodiment in which a movable type ice-breaking 
apparatus is mounted on a vessel. In FIG. 4, reference numeral 2 
represents the bow portion of an icebreaker or iceboat or barge. A 
rotatable turret 5 is disposed on the deck, and an extensible arm 6, the 
length of which can be adjusted, is mounted on this turret 5. On the top 
end portion of the arm 6, there are arranged a hydraulic device 7 for 
adjusting the vertical position of nozzles and another hydraulic device 8 
for adjusting the nozzle angle, and a head 10 is attached through a damper 
9. The top end of the arm 6 is connected to a hydraulic winch through a 
wire 11. By this winch, the load of the arm and other members is 
supported, and this winch is operated when a large displacement is 
required for the head 10. 
In the structure shown in FIG. 4, optimum conditions for the ice-breaking 
nozzles can be optionally selected. More specifically, the distance from 
the bow, the distance from the ice surface, the cutting angle and other 
conditions can be appropriately set by operating the extensible arm 6 
suitably. Further, distance measuring device including an ultrasonic wave 
generator and an ultrasonic wave receiver is disposed in the vicinity of 
the nozzles, and the nozzles are automatically controlled so that they are 
located at optimum positions from the ice surface irrespective of the 
convex-concave state of the ice surface and the change of posture of the 
vessel. 
When the ice-breaking apparatus of the present invention is used for 
continuous ice breaking, breaking of ice in a direction facilitating the 
advance of the ship is effectively attained or promoted, and the sailing 
speed can be made much higher than in the case where the ice-breaking 
apparatus of the present invention is not used. In case of charging 
ice-breaking, if the ship is stopped at the ice-breaking point and ice is 
cut or cracked in advance by using the ice-breaking apparatus of the 
present invention, an easily broken state is brought about in ice, and as 
compared with the case where the ice-breaking apparatus of the present 
invention is not used, the critical ice-breaking capacity can be 
remarkably enhanced. 
FIG. 5 illustrates a head structure and a high pressure water (or sea 
water) pipe system. Sea water or fresh water in a sea chest or water tank 
12 is sucked by a booster pump 13 and passed through a heat exchanger 14 
and a filter 15, and the pressure is further elevated by a piston pump 16. 
A thermometer 17 is disposed between the heat exchanger and the filter, 
and the piston pump is driven by an electric motor 18. Pressurized water 
from the piston pump is introduced to the head through a nozzle line 19. A 
by-pass valve 20 is disposed in the midway of this line to discharge high 
pressure water in case of emergency. The head includes a type (a) and a 
type (b). The head (a) is a moving type head. A skirt 21 is attached to 
prevent the head from being damaged at the time of collision, and in the 
interior, there are disposed a nozzle 22 and an echo distance measuring 
device 23. This echo distance measuring device is connected to the 
interior of the ship through power and signal cables 24. The nozzle is 
heated by an electrically heated panel 25 so as to prevent freezing of the 
liquid in the nozzle. For the same reason, a nichrome wire 26 is aligned 
along the nozzle line. 
The head (b) is one to be disposed in the bow structure. High pressure 
water supplied through a nozzle line 19 is distributed by a control valve 
28, passed through a heated pipe 26 and introduced to a designated nozzle 
22. The nozzles 22 are arranged on the bottom face of a slit 3 formed on a 
shell plating 29 of the bow in the state surrounded by an electrically 
heated panel 25. 
In the present invention, an ice floe is broken or breaking of an ice floe 
is promoted by an impinging force or cavitation caused by jetting of high 
pressure fluid, and since grooves or cracks promoting breakage of the ice 
floe can be formed on the ice floe effectively by such impinging force or 
cavitation, the energy required for breakage of ice can be remarkably 
reduced according to the present invention. 
As will be apparent from the foregoing illustration, according to the 
present invention, prior to breakage of an ice floe, grooves or cracks are 
formed on the ice floe, and therefore, breakage of the ice floe can be 
remarkably facilitated and the ice-breaking capacity of a ship or barge 
can be enhanced. Moreover, dangers involved in the ice-breaking operation 
can be drastically diminished and safe and efficient navigation can be 
ensured. Accordingly, the present invention makes great and valuable 
contribution to the art.