GB2069902A - Submersible hammer - Google Patents

Abstract

A submersible hammer 21 for driving piles comprises a piston 36 and cylinder 35 assembly provided in conjunction with a ram 30 to move the same upwardly when the piston is lifted. Sea water is supplied as power medium at a pressure in excess of the ambient pressure and an inlet valve 50 effects fluid communication between the pressurized sea water and the piston to lift the piston, and thus the ram, and to terminate such communication when the piston reaches a predetermined level. An exhaust valve 51 vents the sea water allowing the piston and ram to fall until the ram impacts the upper end of a pile to drive the same into the sea bed. Provision is also made to brake the piston and ram in the event of excessive movement thereof during the impact stroke. A control system which may also use ambient sea water as its control medium controls the flow of the power medium. <IMAGE>

Description

SPECIFICATION Submersible hammer This invention relates to power operated hammers of the type used for driving piles and the like, and more particularly to hydraulically operated, submersible hammers.

Submersible hammers have been proposed for driving piles into the sea bed to support various off-shore structures. These hammers have been driven by steam, air or oil. Steam driven hammers of course require the availability of a steam generator; air is inefficient because of its compressibility and adiabatic losses; and, where oil is used, leakage is difficult to control and leads to loss of oil and pollution of the water.

More specifically, where compressed air is used, excessive leakage occurs between the pistons and cylinder walls of the hammer, and the air must be compressed to at least several atmospheres above the ambient pressure in order to exhaust, thus requiring appropriate high capacity equipment and giving rise to the generation of excessive heat and imposing cooling requirements.

Where the hammers have been driven by oil, in addition to the pollution problems lost oil must be made up and, since the oil is recycled in the system, sufficient conduit must be furnished to provide a closed system.

According to the present invention, there is provided a hydraulic hammer adapted to operate in an underwater environment and which utilizes sea water as its hydraulic power medium. Sea water may also be used as the pilot control medium although it should be noted that air may be employed for this purpose.

The hammer may comprise a piston and cylinder assembly provided in conjunction with a ram, to move this ram upwardly in a cylindrical guide member when the piston is actuated. A sea water pump supplies sea water at the depth of the cylinder and at a pressure in excess of the ambient pressure, and valve means are arranged to effect fluid communication between the pressurized sea water and one side of the piston to lift the piston, and thus the ram, and when this piston and ram have been thus lifted a predetermined distance, to terminate such communication and to vent the pressurized sea water allowing the piston and ram freely to fall until the ram impacts the upper end of a pile to drive the same into the sea bed.

Among the advantages of the present invention are the fact that sea water, being substantially incompressible, is an excellent and freely available hydraulic medium and, since it may be exhausted into the sea no return hose is necessary thus easing the handling of the overall system.

Additionally, minor leaks are of no serious consequence since they represent neither a fire nor a pollution problem and of course no make-up hydraulic medium need be provided. Moreover, since a single acting hydraulic hammer requires some means of admitting unpressurized fluid to the cylinder during that part of the power stroke between fluid cut-off and top-of-stroke, this fluid ordinarily being supplied by an exhaust accumulator or by reverse flow through an exhaust line, in the present case the required unpressurized fluid is merely sucked in from ambient seat water and is discharged back to the sea along with the power fluid driving the impact stroke.

According to one aspect of the present invention, the hammer comprises a piston and cylinder assembly defining a variable volume chamber, inlet valve means operable to admit hydraulic power medium to the chamber to move the piston upwardly, means for supplying hydraulic power medium to the inlet valve means at a pressure greater than the ambient pressure of the underwater environment of the chamber, exhaust valve means operable to vent this chamber to its ambient environment, and control means for closing the inlet valve means and opening its exhaust valve means when the piston reaches a predetermined position in its upward movement. The piston is connected to a pile driving ram which is lifted when the piston is raised and drops to impact the end of a pile to be driven when the chamber is vented.The cylinder extends beyond the maximum length of the variable volume chamber and is open to the ambient environment at its end opposite the chamber, preferably at its upper end so that as the piston is raised, ambient sea water in the cylinder is driven out into the sea and returns as the piston and ram drop.

According to another aspect of the invention, the control means include means for sensing the position of the piston in the cylinder and are operable to control operations of its inlet and exhaust valve means upon arrival of the piston at respective predetermined positions in its cycle.

More specifically, the control means may include cam means associated with the piston for movement therewith and control fluid supply means operable by the cam means to control the flow of fluid control medium for activating the inlet and exhaust valve means.

The inlet valve means may comprise a valve body having an elongate passageway closed at one end, a tubular valve member movable along the longitudinal axis of the passageway, a second passageway communicating with the elongate passageway and with the chamber and a valve seat in the elongate passageway against which an end of the tubular valve member may rest to close communication between the passageways. The elongate passageway in the valve body is counterbored to provide recess means therein, the valve member is provided with flange means extending into the recess means to form a control chamber, and the control means include a port for delivering control medium to the control chamber to act against the flange means to move the valve member relatively to the valve body.I prefer that the recess means be formed in stepped configuration, that the flange means include a plurality of flanges cooperating with the recess means to provide a plurality of control chambers and that the control means include a port communicating with each control chamber for delivering control medium to its respective control chamber to act against one of the flanges to effect movement of the valve member relatively to the valve body.

The flanges formed on the valve member are constructed to have different annular areas, respectively, for a purpose later to be described, and the parts for delivering control medium are positioned relative to the chambers and flanges to deliver the control medium to the control chambers so as to act respectively on flange surfaces to move the valve member in either upward or downward direction relatively to the valve body.

The exhaust valve means is constructed so as to be similar in certain structural respects to the inlet valve means, the particular differences to be discussed later. For present purposes, suffice it to say that this exhaust valve means also comprise a valve body having an elongate passageway closed at one end, a tubular valve member movable along the longitudinal axis of its passageway, a second passageway communicating with the elongate passageway and with the variable volume chamber, and a valve seat in the elongate passageway against which an end of the tubular valve member may rest to close communication between the passageways. In this case, the control means may differ somewhat from those of the inlet valve means, these differences later to be explained, and the enclosed end of the passageway is open to the ambient environment.

After the piston is raised, the exhaust valve means is opened to establish communication between the variable volume chamber in the cylinder, the second passageway in the exhaust valve body, the tubular valve member and the elongate passageway to its open end and thus the ambient environment. Thus, as the piston drops, the variable volume chamber is vented through the circuit just described so that the sea water used as the power medium to raise the piston is forced back to the sea through the open end of the elongated passageway in the exhaust valve means.

There has thus been outlined rather broadly the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject of the claims appended hereto. Those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures for carrying out the several purposes of the invention.

It is important, therefore, that the claims be regarded as including such equivalent constructions as do not depart from the spirit and scope of the invention.

Specific embodiments of the invention have been chosen for purposes of illustration and description, and are shown in the accompanying drawings, forming a part of the specification wherein: Fig. 1 is an elevational view of an off shore platform illustrating a driven pile affixed to one leg and a second pile about to be driven by a hammer according to the present invention; Fig. 2 is an enlarged partial elevational view illustrating a ram resting atop a pile to be driven and a hammer of the present invention above the ram; Fig. 3 is an enlarged cross-sectional view of the inlet and exhaust valve means as connected to the variable volume chamber; and Fig. 4 is a schematic view of the hammer and the hydraulic power medium and control medium circuits.

Referring now to Fig. 1 of the drawing there is shown an off-shore platform which includes a deck 11 supported at a level above the maximum wave height of the sea by a plurality of legs 12 resting on the sea bed 14 and connected by horizontal structural members 1 5. The legs are each equipped with a series of in-line guides 1 7 for receiving and guiding a pile 19 to be driven into the sea bed. A sleeve 20 integral with each leg near the bottom thereof embraces the upper end of a driven pile to which it is made fast by grouting, for example, so that each pile serves to anchor one of the legs.

As viewed in Fig. 1, the left hand pile has been driven and the right hand pile is shown extending through the sleeve 20 and several guides 1 7 in preparation for driving, this pile being surmounted by a hammer 21 and a ram extending through the two uppermost guides 1 7.

The deck 11, of course, supports whatever equipment (not shown) is required for the purpose at hand. Additionally, the deck supports a rig 22 for lowering the piles and the hammer, and a pump 24 provided with a sea water inlet line 1 5 and a pressure outlet line 26 leading to the hammer as will be described.

Turning now to Fig. 2, it will be seen that the hammer 21 is constituted by a hollow, outer casing 27 the lower end of which closely fits about the upper end of a pile 1 9 to be driven, the casing being equipped internally with a ring 29 contacting the top of the pile to limit the degree of penetration of the pile into the casing.

A ram 30 is shown at rest atop the pile 19 and supported centrally of the casing interior by a plurality of vertically spaced guide rings 31 secured to the interior surface of the casing.

A platform 32 formed with a central opening 34 is secured inside the casing above the ram 30 and supports a centrally disposed upstanding power cylinder 35, the diameter of which is greater than that of the opening 34. The cylinder 35 is open at its upper end and contains a piston 36 adapted for reciprocating movement therein and connected to the ram 30 by a rod 37 that passes through the opening 34 in the platform 32.

It will be noted that the piston and cylinder assembly 36, 37 cooperate to form a variable volume chamber 39 beneath the piston. The upper end of the piston is connected to a second rod 40 which extends upwardly beyond the open end of the cylinder 35 through a bearing 41 supported centrally of the casing 27 by a spider 42, and carries a cam 44 for reciprocal movement with the piston 36 and arranged to actuate control poppets 45, 46 and 47 positioned within the casing, as shown, for a purpose to be described.

Incidentally, the casing 27 is open at its upper end and is formed with several openings 49 in its side wall by which the interior of the casing is in communication with the ambient environment.

Returning now to the platform 32, it will be seen that there are supported thereon an inlet valve 50 and an exhaust valve 51 which control the piston 36, and therefore the ram 30 connected to it by the rod 37.

Referring now to Fig. 3, the inlet and exhaust valves 50 and 51 are shown in enlarged crosssection supported on the platform 32 that is mounted within the casing 27 (not shown). The inlet valve 50 is constituted by a valve body 52 defining an elongate passageway 54 open at its top, as viewed, to provide an inlet for a hydraulic pressure medium which, as mentioned, is preferably sea water. The passageway 54 is constructed to provide downwardly facing annular shoulders 55 and 56 of progressively greater surface areas, and upwardly facing shoulders 57 and 59 also of progressively greater surface areas.

The valve body also defines a second passageway communicating with the passageway 54 near its bottom and with the variable volume chamber 39.

A tubular valve member 61 is shown disposed within the elongate passageway 54 for movement along the longitudinal axis thereof and extends down across the passageway 60 so that its lower end abuts against a seat 62 positioned in a recess formed in the valve body, the facing ends of the seat and the valve member being chamfered for effective engagement to close communication between the passageway 54 and 60 when in the position illustrated.

The annular shoulders 55, 56, 57 and 59 in the passageway 54 serve to define an annular recess 64 of varying diameter in the valve body 52 and the valve member 61 is formed with enlarged exterior portions or flanges 63 extending into respective portions of the recess to provide control chambers 64a and 64b, 64c and 64d with which ports 65a, 65b, 65c and 65d communicate, respectively, to deliver control medium to the corresponding chambers to act against respective flanges to effect movement of the valve member 61 relative to the valve body 52 in a manner later to be described in greater detail. The enlarged portions or flanges of the valve member are sealed against the recess surfaces in a suitable manner as by O-rings, as shown.

Still referring to Fig. 3, the exhaust valve 51 is structurally similar in many respects to the inlet valve. Thus, the exhaust valve is constituted by a valve body 66 defining an elongate passageway 67 open at its top, as viewed, to provide an outlet for the hydraulic pressure medium. The passageway 67 is constructed to provide downwardly facing annular shoulders 69 and 70 of progressively greater surface areas, and an upwardly facing shoulder 71. The valve body also defines a second passageway 72 communicating with the passageway 67 near its bottom and with the variable volume chamber 39.

A tubular valve member 74 is shown disposed within the elongate passageway 67 for movement along the longitudinal axis thereof and extends down across the passageway 72 so that its lower end abuts against a seat 75 positioned in a recess formed in the valve body, the facing ends of the seat and the valve member being chamfered for effective engagement to close communication between the passageways 67 and 72 when in the position illustrated.

The annular shoulders 69, 70 and 71 in the passageway 67 serve to define an annular recess 76 of varying diameter in the valve body 66 and the valve member 74 is formed with enlarged exterior portions or flanges 77a, 77b extending into respective portions of the recess to provide control chambers 79a, 79b and 79c with which ports 80a, 80b and 80c communicate, respectively, to deliver control medium to the corresponding chambers to act against respective flanges to effect movement of the valve member 74 relative to the body 66 in a manner later to be described. As in the case of the inlet valve, the control chambers may be sealed in any convenient manner such as by the use of O-rings between the flanges and recess walls.

Fig. 4 illustrates schematically the hammer and the hydraulic power medium and control medium circuits. Thus, there are shown two circuits, the power circuit controlled by the power inlet and exhaust valves, and the control circuit which is controlled by the cam of the piston, cam and ram assembly. In Fig. 4 the ram 30 is shown in its position when resting on a pile to be driven.

The pile has positioned the ram, the cam 44 and piston assembly so that the cam actuates the bottom control poppet 46 to open, while an overstroke control poppet 47 and a cutoff control poppet 45 are not engaged and remain closed.

In the initial position of the systems, pressurized control fluid emanating from a control fluid source 81 acts through line 82 on the smaller pilot actuator on the left side of a control cycling spool valve 84 to keep the spool shifted to the right, as viewed. While the fluid under pressure flowsthrough lines 85, check valve 83 and line 86, communicating with an accumulator 86a, to pressurize an inlet safety operator 87 to hold the power inlet valve 88 closed, and from line 86 through line 89 to pressurize an exhaust safety operator 90, the control fluid pressure in line 85 is too low to pass through diving bell blowdown valve 91. Control fluid, also pressurizes an exhaust bias operator 92 of the power inlet and exhaust valves.Since, as shown, the area of the piston in the exhaust bias operator 92 is greater than that of the exhaust safety operator 90, its force overcomes that exerted by the exhaust safety operator so that the power exhaust valve 94 corresponding to the exhaust valve 51 described earlier with reference to Figs. 1 to 3, is held open.

Thus, the power cylinder 35 is neither pressurized nor exhausted.

Because the bottom control poppet 46 is opened by the cam 44, pressurized control fluid passes through that poppet to the actuator at the right side of the cycling valve 84, as viewed. This actuator is of greater area than that of the left actuator so that the net force on the spool moves it to the left, closing the line 82 and opening the line 95 directly to the line 81 a from the control fluid source 87 thus delivering control fluid through line 95 to exhaust cycling operator 96.

The combined areas of the exhaust cycling operator and the exhaust safety operator 90 being greater than that of the exhaust bias operator causes the power exhaust valve 94 to close while the inlet cycling operator 97, now pressurized through the lines 95 and 99 and being of larger area than that of the inlet safety operator 87, causes the power inlet valve 88, corresponding to the valve 50 described earlier with reference to Figs. 1 to 3, to open whereupon pressurized power fluid is delivered from the power fluid source 100 through line 101, in communication with a safety accumulator 101 a, through inlet valve 88 and line 102 to power cylinder 104 as well as through line 105 which communicates with line 102, to exert closing pressure on the power exhaust valve 94, and to the overstroke relief valve 106.

The power fluid thus causes the piston 107, corresponding to the piston 36 described earlier with reference to Figs. 1 to 3, to rise along with the cam 44 which moves away from the bottom control poppet 46. The control cycling valve 84 nevertheless remains in its left position because pressure is maintained on the right hand pilot actuator through line 99a which communicates with pressurized line 95.

As the cam 44 rises, it opens the cutoff control.

poppet 45 which admits control fluid through line 109 to the large pilot actuator at the left side of the control cycling valve, as viewed, thus to produce a net force shifting the valve spool to the right. This in turn vents the inlet and exhaust cycling operators 97 and 96 through lines 99 and 95 to cause the inlet safety operator 87 to close the power inlet valve 88 and to allow ambient sea water to enter the system through the power check valve 110, under the influence of the rising piston and cam assembly, until the power exhaust valve 94 opens which occurs after the power inlet valve closes because of the relative sizing of the respective operators. Upon opening, the exhaust valve 94 allows ambient sea water to be drawn into it while it also enters through the check valve 110 as the piston and cam assembty continue to rise.

The piston and ram assembly ultimately stop rising and begin to descend expelling power fluid from the cylinder through the exhaust valve to the sea and eventually actuating the cutoff control poppet 45 to admit control fluid from line 85 through the poppet 45 to line 109 and the left side of the control cycling valve 84. The piston further descends past the cutoff poppet 46 at about the same time that the ram 30 strikes the pile at which time the system has returned to its initial condition thus completing a cycle of operation and is ready to repeat unless there occurs interruption of the control or power fluid supply or mislocation of the pile.In such case, the piston would descend somewhat beyond its normal lower limit and actuate an overstroke control poppet 47 which passes control fluid from line 85 through line 111 to an overstroke valve 112 to block flow of the control fluid from its source to the inlet cylinder operator 97 and venting the same.

With both the power inlet valve and the relief valve 106 closed, the power fluid trapped within the cylinder 104 is forced by the still descending piston to blow over the overstroke relief valve 106, the overstroke relief valve blowoff pressure acting on the piston areas generating a braking force that stops the piston and ram before the piston engages internal stops, the kinetic energy of the ram being dissipated at the relief valve as heat in the fluid.

In the event of a loss of control fluid, in which case the hammer might try to continue the power upstroke, or fail to stop and recycle if loss of control fluid occured while the power inlet valve is open and the power exhaust valve is closed, enough fluid is trapped by the safety check valve 83 and stored in the safety accumulator to close both the inlet and exhaust valves.

It will be appreciated that the control fluid pressure can be raised above the blowndown relief valve setting of diving bell 114 so that control fluid can blow over this valve into the diving bell to displace ambient sea water. When the hammer is driving, the return from the cycling valve is conducted to the diving bell continuously to displace sea water.

From the foregoing description it will be seen that I contribute a submersible hammer adapted to operate in an underwater environment and which utilizes sea water as the power medium and which may also use sea water as the pilot control medium thus to obtain the advantages noted.

I believe that the construction and operation of my novel submersible hammer will now be understood and that the several advantages thereof will be fully understood by those persons skilled in the art.

Claims (23)

1. A hydraulic hammer for operating in an underwater environment, said hammer comprising: a piston and cylinder assembly defining a variable volume chamber, inlet valve means operable to admit hydraulic power medium to said chamber to move said piston upwardly, means for supplying hydraulic power medium to said inlet valve means at a pressure greater than the ambient pressure of the underwater environment of said chamber, exhaust valve means operable to vent said chamber to its ambient environment and control means for closing said inlet valve means and opening said exhaust valve means when said piston reaches a predetermined position in its upward movement.

2. A hydraulic hammer according to Claim 1, wherein a ram is connected to said piston for movement therewith.

3. A hydraulic hammer according to any of Claims 1 or 2, wherein said cylinder extends beyond the maximum length of said variable volume chamber and is open to the ambient environment at its end opposite said chamber.

4. A hydraulic hammer according to Claim 1, wherein said control means include means for sensing the position of said piston and operable to control the operation of said inlet and exhaust valve means upon the arrival of said piston at respective predetermined positions in its cycle.

5. A hydraulic hammer according to any of Claims 1,2 or 4 wherein said control means include cam means disposed relatively to said piston for actuation thereby and control fluid supply means operable by said cam means to control the flow or fluid control medium for actuating said inlet and exhaust valve means.

6. A hydraulic hammer according to any of Claims 1,2 or 4 wherein said control means include cam means disposed relatively to said piston for actuation thereby and control fluid supply means operable by said cam means to control the flow of fluid medium to brake said piston upon descent thereof beyond a predetermined lower limit.

7. A hydraulic hammer according to Claim 5, wherein said cylinder extends beyond the maximum length of said variable volume chamber and is open to the ambient environment at its end opposite said chamber.

8. In a hydraulic hammer, a piston and cylinder assembly defining a variable volume chamber, inlet valve means operable to admit hydraulic power medium to said chamber to move said piston upwardly, means for supplying pressurized hydraulic power medium to said inlet valve means, exhaust valve means operable to vent said chamber to its ambient environment to permit said piston to move downwardly, and means controlling said inlet and exhaust valve means in response to the arrival of said piston at predetermined positions in its upward and downward strokes, said inlet valve means comprising a valve body having an elongate passageway closed at one end, a tubular valve member movable along the longitudinal axis of said passageway, a second passageway communicating with said elongate passageway and with said chamber, and a valve seat in said elongate passageway against which an end of said tubular valve member may rest to close communication between said passageways.

9. Apparatus according to Claim 8, wherein said control means include means for sensing the position of said piston and operable to control the operation of said inlet and exhaust valve means upon the arrival of said piston at respective predetermined positions in its cycle.

10. Apparatus according to any of Claims 8 or 9 wherein said control means include cam means disposed relatively to said piston for movement thereby and control fluid supply means operable by said cam means to control the flow of fluid control medium for actuating said inlet and exhaust valve means.

11. Apparatus according to Claim 8, wherein a said elongate passageway is formed with recess means, said valve member is provided with flange means extending into said recess means to form a control chamber and said control means include a port for delivering control medium to said control chamber to act against said flange means to move said valve member relative to said valve body.

1 2. Apparatus according to Claim 11, wherein said recess means are formed in stepped configuration and said flange means include a plurality of flanges cooperating with said recess means to provide a plurality of control chambers, said control means include a port communicating with each control chamber for delivering control medium to its respective control chamber to act against one of said flanges to move said valve member relative to said valve body.

1 3. Apparatus according to Claim 12, wherein said flanges are formed with different annular areas, respectively.

14. Apparatus according to either Claim 1 2 or 13 wherein said ports are positioned relative to said chambers and flanges to deliver control medium to said chambers to act selectively on flange surfaces to move said valve member in either upward or downward directions relatively to said valve body.

1 5. Apparatus according to either of Claims 8, 11, 12 or 13 wherein said means for supplying pressurized hydraulic power medium to said inlet valve means include conduit means communicating with the enclosed end of said elongate passageway whereby said hydraulic medium flows along said elongate passageway, through said tubular valve member and said second passageway to said chamber when said inlet valve means are open.

1 6. In a hydraulic hammer, a piston and cylinder assembly defining a variable volume chamber, inlet valve means operable to admit hydraulic power medium to said chamber to move said piston upwardly, means for supplying pressurized hydraulic pressure medium to said inlet valve means, exhaust valve means operable to vent said chamber to its ambient environment to permit said piston to move downwardly, and means for controlling said inlet and exhaust valve means in response to the arrival of said piston at predetermined positions in its upward and downward strokes, said exhaust valve means comprising a valve body having an elongate passageway closed at one end and open to the ambient environment at the other end, a tubular valve member movable along the longitudinal axis of said passageway, a second passageway communicating with said elongate passageway and with said chamber and a valve seat in said elongate passageway against which an end of said tubular valve member may rest to close communication between said passageways.

17. Apparatus according to Claim 16, wherein a said elongate passageway is formed with recess means, said valve member is provided with flange means extending into said recess means to form a control chamber and said control means include a port for delivering control medium to said control chamber to act against said flange means to move said valve member relative to said valve body.

18. Apparatus according to Claim 17, wherein said recess means are formed in stepped configuration and said flange means include a plurality of flanges cooperating with said recess means to provide a plurality of control chambers, said control means include a port communicating with each control chamber for delivering control medium to its respective control chamber to act against one of said flanges to move said valve member relative to said valve body.

1 9. Apparatus according to Claim 18, wherein said flanges are formed with different annular areas, respectively.

20. Apparatus according to either Claims 1 8 or 1 6 wherein said ports are positioned relative to said chambers and flanges to deliver control medium to said chambers to act respectively on flange surface to move said valve member in either upward or downward directions relatively to said valve body.

21. Apparatus according to either Claims 1 6, 17, 18 or 19, wherein the enclosed end of said valve body communicates with the ambient environment whereby said hydraulic power medium flows from said chamber, through said second passageway, said tubular valve member and along said first passageway to the ambient environment when said exhaust valve means are open.

22. A hydraulic hammer substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

23. Any novel feature described herein or shown in the drawings.