United States Patent 3698341

A sea-ice breaker for ships, including a ship-borne high capacity source of compressed air and a submersible free-floating vertical ram assembly for pivotal attachment to the bow of a ship, the ram consisting of three chambers: an uppermost spheroidal chamber reinforced for splitting the ice from beneath by impact and having connection to the high-pressure air supply for throwing the ice aside after splitting by exhausting fluid against it under high pressure; a middle chamber connected through a header with a downwardly disposed array of parallel pipes and having connection to the high pressure air supply for driving the ram upward against the ice by rapid downward expulsion of seawater from the pipes; and a bell-like lower chamber open at the bottom to serve as an air-spring, and having connection to the high pressure air supply for adjusting the nominal buoyancy of the ram assembly and for supplying extra driving force to the ram when required.

Application Number:
Publication Date:
Filing Date:
Primary Class:
International Classes:
B63B35/08; (IPC1-7): B63B35/08
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US Patent References:
3572273N/AMarch 1971Wood
3130701IcebreakersApril 1964Langballe

Primary Examiner:
Blix, Trygve M.
I claim

1. An ice breaker system for ships, comprising: vertically elongated ram means for impacting ice from beneath, the vertically elongated ram means comprising plural rigid compartments; means for oscillating the ram means including pipe means extending downward from connection with a said compartment, said pipe means being vented at an upper portion thereof for receiving ambient seawater and the like into the interior of the ram means cyclically and having means associated therewith for ejecting said received seawater downward through the pipe means.

2. An ice breaker system for ships as recited in claim 1, wherein the means for oscillating includes a compressed air system for carriage aboard a said ship and wherein the means for movable attachment includes an arm attached at one end to the ram means and adapted at the other end for pivotal attachment to a said ship and means for passage of compressed air from said ship to a compartment in the ram means for ejecting seawater downward from said pipe means.

3. An ice breaker system for ships comprising: ram means, having plural rigid compartments, for impacting the ice from beneath; means for oscillating the ram means including: pipe means extending downward from connection with a said rigid compartment; a compressed air system for carriage aboard a said ship, means for passage of compressed air from a said ship to one of said rigid compartments in the ram means for ejecting fluid from said pipe means; one of said plural compartments including a connection to said air passage means; a valve and orifice for expelling air upward from the ram means; and means for movable attachment of the ram means to a said ship including an arm attached at one end to the ram means and adapted at the other end for pivotal attachment to a said ship.

4. An ice breaker system for ships as recited in claim 3 wherein the plural compartments are in vertical relation and include an upper compartment, a middle compartment and a lower compartment, with the lower compartment being open at the bottom and the pipe means extending downward therethrough from the middle compartment.

5. An ice breaker system for ships as recited in claim 4, wherein the lower compartment has a valve connection with the compressed air passage means for thereby trimming the displacement of said ram means.

6. An ice breaker system for ships as recited in claim 5, wherein the compressed air passage means includes valved connection with said middle compartment.

7. An ice breaker system for ships as recited in claim 6, wherein the upper compartment comprises a spheroidal chamber, with the upper wall of the chamber forming an impact structure for ice breaking by said system.

8. An ice breaker system for ships as recited in claim 7, and an impact sensor on the ram means for controlling the valve for expelling air upward from the ram means.

9. An ice breaker attachment as recited in claim 8, wherein the ram means is pivotally adapted for storage, beneath a said ship parallel therewith, whereupon said ejection of fluid from the pipe means gives forward impulse to said ship.

10. An ice breaker system as recited in claim 7, and a compartment for storage of compressed air positioned intermediate the upper and middle compartments and having valved passage for air to said upper and middle compartments.

11. An ice breaker system as recited in claim 7, and a hemi-spherical member open at one side, the hemispherical member attached to the lower end of the pipe means with said open side downward.

12. An ice breaker system for ships comprising: ram means having plural rigid compartments for impacting ice from beneath; means for oscillating the ram means including: pipe means extending downward from connection with a said rigid compartment, a compressed air system for carriage aboard a said ship, means for passage of compressed air from a said ship to one of said rigid compartments in the ram means for ejecting fluid from said pipe means; means for movable attachment of the ram means to a said ship including an arm attached at one end to the ram means and adapted at the other end for pivotal attachment to a said ship; said ram means additionally comprising a unitary, laterally extended double ram means, each of said double ram means being independently actuable by the means for oscillating the ram means, and cradle means for limiting the travel of a ram means and stabilizing it against a said ship, whereby said oscillation of the ram means provides for oscillation of a said ship.

13. An ice breaker system for ships as recited in claim 12, wherein the laterally extended double ram means comprises two independent ram assemblies fixedly spaced apart by strut means.

This invention relates generally to equipment for ships and specifically to ice-breaker attachments for clearing shipping channels through pack ice.

In the past, ice-breaking as a regular practice has been largely confined to temperate zones, and in the Arctic regions to summer only.

Special vessels find employment in clearing harbor entrances, canals, and shipping channels where sufficient winter traffic warrants the expenditure, but are not economical for escorting a few ships at a time.

The polar ice pack has historically barred navigation in winter, and even in summer has resisted penetration by all but specially equipped vessels, which have occasionally threaded through open channels and thin ice along the continental shores.

Today, because of the discovery of vast oil reserves on the Polar Shores of the North American continent where the great distances and environmental extremes make pipeline installation and maintenance impractical, it is urgently important to provide a means of economically transporting oil out by water on a regular, dependable schedule.

Vessels are normally not navigable through solid pack ice. Recent experiments with a very large specially powered and armored ship indicate that much larger, more powerful and more heavily armored vessels will be required to traverse the polar regions reliably in good summer conditions. For 7 to 9 months of the year even ships now on the drawing boards will be icebound.

The ideal approach to the problem of polar shipping is to provide a means whereby every ordinary vessel capable of high-seas operation can easily be adapted to open a path for itself through the northern route around the Continent in any season and weather condition, and this is the principal object of this invention.

Further objects of this invention are to provide an economical attachment for ships of the type described which shatters the ice and throws it aside, creating a wide clear channel to avoid side pressures on the ship hull; which is free-floating and places minimum stress on the ship hull in the ice-breaking operation; which is relatively light in weight but highly effective at breaking ice, by reason of mass-in-line, streamlined construction delivering maximum force at the point of impact through an impacting head which is externally convex and internally stiffened by compressed air; which is efficient, energy conserving, and fast cycling, by reason of oscillator construction including a bell-contained air mass which acts as an oscillator spring coupling with the driving impulses; which is easily stowed, transported, and deployed for use; and finally, which is adapted for economical, rugged, simple, rigid, all metal construction.

I embody this invention, typically, in a rigid, free-floating ram or air-hammer assembly for hinged attachment to a ship, the assembly having plural chambers vertically in line, with propulsive pipes connected to a median chamber for driving the ram upward against ice on expulsion of water from the pipes by compressed gas, with a bell open at the bottom comprising the lower chamber which acts as an air-spring and buoyancy control chamber, and with a spheroidal impact head and gas-expulsion uppermost chamber.

The above objects and advantages of my invention will become better understood from an examination of the following description, and from drawings, in which:

FIGS. 1, 2 and 3 are side elevations of the ram assembly of this invention operatively attached to the bow of a ship.

FIG. 4 is a front elevation of the ram assembly and gas system installed in a ship, with the ram assembly in section;

FIG. 5 is a side view of a ship showing the stored position of the invention.

FIG. 6 is a detail section of a stabilizer;

FIG. 7 is a further embodiment of the ram assembly; and

FIGS. 8 and 9 are front and side elevations of another embodiment of this invention.

Now taking up the drawings in detail, FIG. 1 shows the ram assembly, or pneumatically actuated hammer assembly 10, in position to drive upward against the bottom of pack ice I, and break a passage for ship S. The ram assembly is pivotally attached to the bow of ship S by arms 12 and 12' which are paired, as shown in FIG. 4, and attach to the bell or sleeve 50 of the ram assembly. At least one arm 12 is tubular, adapting it for feeding gas back and forth between the ram actuating gas compressing and distributing system carried aboard the ship S and the ram assembly.

FIG. 2 shows head 52 of the ram 10 impacting against the ice in the upward part of an oscillatory cycle, splitting the ice. The ram drives upward under reactive thrust of downward expulsion of seawater at high velocity from ram actuator tubes 54, by provisions described later. The lower ends of the tubes act as jet nozzles.

FIG. 3 shows the broken ice being thrown clear of the area by the ram, assisted by fluid expelled under high pressure from the head 52 of the ram.

Following the FIG. 3 stage, the ram rapidly submerges, in the downward part of the oscillatory cycle, driven by the combination of upward fluid expulsion from the head and resonant downward urging of an air spring arrangement in the bottom of the ram assembly as will be seen. In the same manner, the device continues to repeat the process, cycling up and down, being in the meantime moved forward under fresh ice by continuous forward motion of the ship.

As FIG. 4 indicates, the width of the ram is proportioned to the path width to be cleared for the particular ship. Because of the magnitude of the impact provided, followed almost simultaneously by the rapid expulsion of compressed gas driving water and ice upward from the top of the ram, breakage and clearance of ice extends beyond the sides of the ram, so that the ram need not be as wide across as the path to be cleared although it can be made so.

As shown in FIG. 4, gas system 18 carried aboard the ship includes a high capacity, high compression pump 20, such as a turbine driven pump, and associated valving, piping and gas storage.

Pump 20 draws for compression through inlet 22, valve 24 and pipe 26, compresses the air and pumps it through pipe 28 into accumulator tank 30.

The compressed air passes through valve 34 downward through pipe 38, pipe pivot 16, arm 12, and pipe pivot 14 into ram assembly 10.

When it is desired to reduce the pressure in the ram assembly, valve 34 is closed and simultaneously valve 36 is opened, with or without closure of valve 24, depending on the speed of pressure-reduction-required.

Ram assembly 10 includes three major compartments, designated by 1, 2 and 3 which receive and utilize the compressed air pumped into the ram from shipboard.

Compartment 1 is a spheroidal shaped high compression accumulator which receives, through pipe 40, and stores, air at the full pressure of the pumping system 18. The upper part of this chamber comprises the driving head 52 of the ram assembly. Although, as will be seen, part of this pressure is drawn off at the moment of ram assembly impact with the ice above, the air in this chamber is still highly compressed and helps prevent collapse of the chamber. Relatively light-weight construction of the chamber is made reasible by this arrangement.

Following ram impact with the ice, compressed air is dumped upward from the chamber through valve 42, distributor 44 and nozzles 46. This jet-like expulsion throws broken shards of ice aside and gives a downward impulse to the ram assembly. In normal operation the distributor 44 will be filled with water as result of prior submergence, adding to the mass of the fluid expelled when valve 42 opens, and to the efficiency of ice-removal and downward thrust of the ram assembly.

Compartment 2 is the middle compartment. It connects through valve 56 with the high-pressure air supply from the ship. The lower wall 58 of the compartment is a header, supplying air to plural downwardly extending actuator or jet tubes 54. The actuator tubes 54 are normally filled with water to a predetermined level, and high velocity expulsion of the water causes reactive upward thrusting of the ram assembly, as previously described.

Compartment 2 vents to compartment 1 through valve 56 so that chamber 2 tends to assume the pressure of chamber 1 when valve 56 is opened. When the air in chamber 1 is dumped, following impact, chamber 2 is vented through chamber 1, allowing the actuator tubes to refill from below with water on the downward stroke of the ram assembly. Braces 62 are preferably provided between the actuator tubes and the sleeve, and between each other.

Compartment 3, the lowermost compartment, is essentially a bell chamber, open at the bottom and elsewhere closed by the header structure 58 and sleeve 50. It fairs-in with the upper compartment 1, and protectively shrouds the actuator pipes 56.

Compartment 3 is of substantially greater volume than that required to float the ram assembly. This compartment is normally filled to an intermediate level with water, and valve 60 normally remains closed. Valve 60 admits compressed air to compartment 3, and vents it, when required, to the pressure in system 18, which pressure may be reduced for the purpose. This arrangement provides for trimming the mean displacement of the ram assembly.

The air in compartment 3 serves other important functions. It comprises a large air-spring providing the fast restoring force essential to practical rapid oscillation of the ram assembly, pressure in the compartment going from positive to negative as the ram assembly drives upward, and vice versa. Addition of air to compartment 3 can be used to increase the upward driving force of the ram assembly in emergencies. Operation of the valves is synchronized by means well known in the art, such as by an electrical programmer system, the valves being adapted for electrical actuation. An impact switch 64, FIG. 4 can be used to synchronize the operation of valve 42 with the time of impact.

Sequence of operation of the system is as follows: with the ram assembly in the FIG. 1 position, and valves 34, 36, 42, 56 and 60 closed, valve 34 is opened and chamber 1 is pressurized. Valve 56 is then opened ejecting water in high velocity jets from tubes 54 by air pressure, and driving the ram assembly rapidly upward. Following impact with the ice, as in FIG. 2, valve 42 is opened, venting the pressure in chamber 1 and chamber 2. At this uppermost position of travel, pressure in unvented chamber 3 has been reduced below atmospheric, and the differential urges the ram assembly downward again, in conjunction with the thrust generated at valve 42 and the force of gravity. During downward stroke of the ram assembly, valves 42 and 56 are closed, pumping system 18 repressurizes chamber 1 and the descent of the ram assembly repressurizes the air in compartment 3. Near the bottom of the stroke valve 56 is opened, pressurizing the actuator tubes, and the cycle begins again.

The general proportions of the system should be so related to each other and to the pressure and capacity of the pumping system, as to permit oscillation of the ram assembly as described at the natural frequency of the assembly, for maximum efficiency. That is to say, during continuous operation, in the upward half of the cycle, momentum of the water expelled from the tubes should substantially exceed the momentum developed by the buoyancy alone of the ram assembly plus the momentum transferred to the ice. In the downward half cycle, momentum developed in expulsion of fluid from the head should substantially exceed the free falling momentum of the ram assembly to the floating level, to prevent critical damping of the oscillation by the surrounding water.

Three short actuator tubes are shown for clarity of exposition, but this is not a limitation on the number or length for any application.

FIG. 5 shows a stowed position of the assembly beneath a ship S. It will be seen that in the position, ejection of water from the actuator tubes 54 will give forward impulse to the ship; and, on release of chain C, ejection of water from the actuator tubes 54 will swing the ram assembly into the vertical position, ready for use.

FIG. 6 shows, in section, a hemispherical stabilizer 70 attached to the lower ends of actuator tubes 54, with the open end down. In actual test it has been determined that the stabilizer increases the thrust from the actuator tubes attached to it and reinforces the tubes by joining them together, in addition to stabilizing the operation of the ram assembly. It can be seen also, that addition of air sufficient to fill the stabilizer provides lift useful in folding the ram assembly for storage under the ship.

FIG. 7 shows a further embodiment 710 of the ram assembly of this invention. The principal differences from the FIG. 4 embodiment lie in provision of a high-pressure accumulator chamber 704 between chambers 701 and 702, and in the valving of the various chambers. The high-pressure accumulator chamber 704 is installed in reinforcing proximation to the chambers above and below. It is isolated from the supply pipe 740 by valve 776, from chamber 701 by valve 772 and from chamber 702 by valve 778.

Thus, a high pressure can be stored in the ram assembly 710 itself and released instantaneously, with minimum frictional loss, into chamber 701, chamber 702, or both. For example at the top of the stroke of the ram assembly 710, while chamber 702 is being vented to the sea through valve 780 to allow water to rise again in actuator tubes 754, and while chamber 701 is still exhausting through orifices 746, pressure can be accumulating in chamber 704 in preparation for the power stroke in the next half-cycle.

Valve 774 can be opened to supply extra capacity to chamber 701 when required, or valves 774 and 778 can both be opened to supply extra capacity to the actuator tubes through chamber 702.

Valve 782 allows air to be supplied to chamber 703 from chamber 702. Trim valves 784-790 are scaled in height to allow venting air from chamber 703 to the predetermined height chosen by the valve actuated; any required number of trim valves can be used.

Chamber 701 can be isolated by closure of valves 742, 772 and 774 when exhaust from the chamber is not needed.

FIG. 8 and 9 are front and side elevations, respectively, of another embodiment of this invention which is designed for ice breaking by rolling and pitching the ship as well as by the method previously described.

As shown best in FIG. 8, a unitary, laterally extended, double ram 800 of two ram assemblies 810 and 810' affixed together by a bridge strut 892. Each ram assembly 810 is substantially the same as ram assembly 10, FIG. 4, or ram assembly 710, FIG. 7. Each ram assembly is provided with a suitable air supply as at 18, FIG. 4, or a shared supply with the ram assemblies remaining independently actuable. Arms 812 and 812' pivot the double ram 800 in similar manner to that previously described. In the extreme upward limit of travel of the double ram, the heads 852 of the respective ram assemblies nest into recesses 853 and 855 in a cradle 857, which is welded to the bow of the ship S. The recesses are shaped to receive and firmly stabilize the double ram against the structure of the ship when the double ram is buoyantly thrust upward into the recesses.

The lowermost compartments, or bell compartments in the ram assemblies, correspond to compartment 3 in FIG. 4 but are preferably made longer vertically by downward elongation of sleeves 850, to prevent the lower edges from emerging above the surface of the water when the ship is rolled or pitched by the assembly. The added mass also lowers the center of gravity even more with respect to the pivots, further stabilizing the structure.

In operation in the ship rolling or pitching mode, the lowermost compartments are substantially filled with air, raising the double ram against the cradle and buoyantly clamping it there, fixed in position by the recesses and the pivot arm. Next, each ram assembly 810 is operated in the manner previously described, with air pulses thrusting water from the actuator tubes 854.

The pulses from the individual ram assemblies 810 and 810' are synchronized as required to produce the ship motion desired. If pitching is desired, both ram assemblies are pulsed together, oscillating the bow of the ship up and down. If rolling is desired, the ram assemblies are alternately actuated, twisting the ship about the long axis. If a combination of the two ship motions is desired, the ram assemblies are phased in operation to pitch and roll the ship in combination.

It can readily be seen that this embodiment of my invention with suitable adaptation can be recessed entirely within the ship for the purpose of rocking the ship. It can also be seen that the structure disclosed, in the location shown, when used as ram assembly, will break a very wide path through the ice, further relieving side pressure of ice on the hull of the ship, as may be necessary. Also, a single large ram of my design can be internally modified to produce rolling ship-motion, by splitting the actuator tubes into left-and right-hand banks, each with a separately controlled air supply. Adaptation of the cradle design to contain a single ram head instead of two can easily be made in the light of my teachings.

Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.