MXPA97006003A - Device to create a water flow lo - Google Patents

Abstract

The present invention relates to a device for creating a local water flow or water jet in a body of water, in such a way that the bed material coming from the bed can move under said body of water, comprises an injection pipe, a screw rotatably positioned in the injection pipe, and means for supplying a counter torque in the direction opposite to the torque exerted on the device through the rotation of the screw. According to the invention, a second screw is accommodated in the injection pipe, the second screw of which is rotatable in the direction opposite to the direction of rotation of the first screw, and the pitch angle of which is opposite that of the first screw.

Description

DEVICE FOR CREATING A LOCAL WATER FLOW BACKGROUND OF THE INVENTION The invention relates to a device for creating a local water flow or a water jet in a body of water, such that the bed material coming from the bed under said body of water may be displaced, which device comprises an injection pipe, a screw rotatably placed in the injection pipe, and means for supplying a counterbore in the direction opposite to the torque exerted on the device through the rotation of the screw. Such a device is known from EP-A-289520. With this known device it is possible to make a trench in a water bed, in whose trench it can lie, by example, a conduit. For this purpose, the device moves at a certain distance above the water bed along the path in which the trench is to be made. In this case, the rotating screw supplies the desired water flow. 20 Since the rotating screw exerts a torque on the device, unless countermeasures were taken, the device would begin to rotate uncontrollably around its axis, which, of course, is very undesirable. Taking this into account, they are provided blades at the outlet of the injection pipe, the blades of which exert a counter torque on the device as a result of the flow of water in the injection pipe, in such a way that the device is stabilized with respect to such rotary movement. A great disadvantage of this device is that the generated torque and the counter torque are the same for a specific discharge velocity of the water flow in the injection pipe only within a limited speed of the rotation range. With the variation of the distance of the device from the bottom, said discharge speed varies, and consequently also the counter torque. It is not easy to keep the torque generated and the counter torque equal during the operation of the device. Accordingly, the rotation of the device has to be avoided by other additional means. SUMMARY OF THE INVENTION Accordingly, the object of the invention is to provide a device of the type mentioned above that does not have these disadvantages. This is achieved through the accommodation of a second screw in the injection pipe, the second screw of which is rotatable in the direction opposite to the direction of rotation of the first screw, the direction of the screw being opposite and the combination of pitch being such with its rotation speed that the generated torque is the same or virtually the same as that of the first screw. The pitch angle is preferably opposite that of the first screw. The second screw not only provides the desired counter torque, as a result of which the device remains stable, but also contributes to a more efficient operation of the device with respect to the displacement of the bed material such as, for example, during the elaboration of a trench. in the water bed. This means that no energy is lost during stabilization of the device. Through the proper choice of the second screw you can also make sure that the required counter torque is always supplied, with the result that no additional measures should be taken to synchronize the operation of the screws. Preferably, the first screw and the second screw are coaxially accommodated in the injection pipe; in the case that one of the screws can be connected to a hollow motor shaft, and the other screw can be connected to a central motor shaft that passes coaxially through the hollow motor shaft. Both drive axes can be projected from the injection pipe at the inlet end thereof, and each can be connected to a drive unit. At the upper end of the injection pipe, suspension means can also be provided, for suspending the device from a support element such as a cable, which in turn is connected to a container on the surface of the water. The device can also be used to cover pipes, level the water bed, rinse articles by jet or move quantities of land, etc. On the outlet side of the injection pipe, the device can have various types of nozzles, which can be round, oval or rectangular in shape. The means for directing the screws may include a drilling motor. The drilling motor can be a "Moineau" electric motor, adapted hydraulically or suitably. Alternatively and advantageously, the drilling motor may comprise a stator and a rotor rotatably mounted on the stator, the stator being provided with a rod recess and an exhaust port, the rotor being provided with a rotor channel and at least one channel for driving motor fluid from the rotor channel to a chamber between the rotor and the stator, being provided to the rod recess with a rod which, in use, forms a seal between the stator and the rotor. Such a drilling motor is described in pending US 08 / 191,693 (SUSMAN et al.). Although not essential, it is highly desirable that the rotor be provided with a seal for the clutch with the stator. Preferably, the seal is made of a material selected from the group consisting of plastic materials, polyethylethylacetone, metal, copper alloys and stainless steel. Advantageously, the rod is made of a material selected from the group consisting of plastic materials, polyethylethylacetone, copper metal alloys and stainless steel. Preferably, the stator is provided with recesses of rod that are placed opposite each other and two exhaust holes that are placed opposite each other, providing each of the recesses with a respective rod, the rotor having two seals that are placed opposite each other. yes. Advantageously, the drilling motor may comprise two drilling motors installed with their respective rotors connected together, each motor comprising a stator and a rotor rotatably mounted on the stator, the stator being provided with a recess of rod and an exhaust hole, provided to the rotor with a rotor channel and at least one channel for driving motive fluid from the rotor channel to a chamber between the rotor and the stator, providing the rod recess with a rod which, in use, forms a seal between the stator and the rotor. Preferably, the drilling motors are connected in parallel, although they could be connected in series if desired. Advantageously, the drilling motors are installed so that, in use, one drilling motor operates out of phase with the other. Thus, in a preferred embodiment, each drilling motor has two chambers and the chambers in the first drilling motor are 90 ° out of phase with the chambers in the second drilling motor. Similarly, in a mode in which each drilling motor has four chambers, the chambers in the first drilling motor would preferably be 45 ° out of phase with the chambers in the second drilling motor. This installation helps to ensure a smooth output of power and inhibits the loss of speed. The device can provide means for directing the device, in use. Preferably, the steering means comprises at least four openings in the device, the openings also being separated around a plane through the device, which plane is proposed substantially horizontal in use, openable gates in each of the four openings, and means for controlling the opening and closing of each gate, preferably providing each gate with a portion, the portion of which extends inwardly when the gate is opened (in order to direct or empty - water through the respective opening), closing the portion even more the opening when the gate is closed. Preferably, the control means comprises an electric or hydraulic actuator for each gate, each actuator being controlled by an electrical connection extending above the surface. Alternatively, the steering means may comprise one or more openable covers located at the outlet. Each screw may include a plurality of blades, the blades moving one screw 180 ° with respect to the blades of the other screw of the pair. The screws can be found in the form of injectors. For example, the screws may be in the form of injectors provided with jets of water at the tips thereof as disclosed in GB 2 240 568. The invention will be explained in more detail below with reference to a number of exemplary embodiments shown in FIG. the figures. BRIEF DESCRIPTION OF THE DRAWINGS The figure shows a longitudinal cross-sectional view of a drill motor for use in an embodiment of the present invention. Figures 2A-2D show a series of cross-sectional views along line A-A of Figure 1 showing the engine in four different positions. Figures 3A-3D show a series of cross-sectional views along line B-B of Figure 1 showing the engine in four different positions. Figure 4 shows a longitudinal cross-sectional view of a first embodiment of an underwater excavation apparatus according to the present invention. Figures 5A-5C show a series of views of a first injector for use in the apparatus of Figure 4. Figures 6A-6C show a series of views of a second injector for use in the apparatus of Figure 4. Figure 7 shows a schematic side view of the apparatus of Figure 4 connected to a hose reel provided in, for example, the stern of a ship. Figure 8 shows a longitudinal cross-sectional view of a second embodiment of an underwater excavation apparatus according to the present invention. Figure 9 shows a third embodiment of the apparatus according to the invention, partially in longitudinal section. Figure 10 shows a discharge nozzle for the apparatus. Figure 11 shows a first possible application of the apparatus. Figure 12 shows a second possible application of the apparatus. Figure 13 shows an alternative embodiment of Figure 12. Figure 14 shows a possible additional embodiment of the apparatus. Figure 15 shows a first alternative discharge nozzle. Figure 16 shows a second alternative discharge nozzle. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES Some embodiments of an underwater excavation apparatus according to the present invention are set forth herein. Two embodiments comprise a drilling motor. In order to facilitate the understanding of the modalities of the exposed underwater excavation apparatus, a detailed description of the drilling motor will first be given. Referring to Figure 1, the generally designated drilling motor 10 is shown. The drilling motor 10 comprises a first motor 20 and a second motor 50. The first motor 20 comprises a stator 21 and a rotor 23. An upper portion 22 of the rotor 23 extends through an upper support assembly 24 which comprises a thrust bearing 26 and seals 25. The drive fluid, eg water, drilling mud or gas under pressure, flows underneath through a central sub-channel. 12 towards a central rotor channel 27, and then outward through flow channels of the rotor 28 to the action chambers 31 and 32. After a working stroke of the motor, the drive fluid flows through the exhaust holes 33 in the stator 21, and then descending through an annular channel circumjacent the stator 21 and the flow channels 35 in a lower support assembly 34. A portion 36 of the rotor 23 extends through the lower support assembly 34, which comprises a thrust bearing 37 and seals 38. The ends of the stator 21 are crenelated and the castellations engage in recesses in the respective upper support assembly 24 and the lower support assembly 34, respectively to inhibit rotation of the stator 21. The upper support assembly 24 and the lower support assembly 34 are a slight fit in an outer tubular member 14 and are held against rotation by compression between threaded sleeves 16 and 84. A channeled connection 39 links a fluted end of the rotor 23 to a fluted end of a rotor 53 of the second motor 50. The second motor 50 has a stator 51. An upper portion 52 of the rotor 53 extends through an upper support assembly 54. The seals 55 are positioned between the upper support assembly 54 and the exterior of the upper portion 52 of the rotor 53. The rotor 53 moves on thrust bearings 56 with respect to the upper support assembly 54. The drive fluid flows into a channel of central rotor 57 from the central rotor channel 27 and then outwardly through rotor flow channels 58 to action chambers 61 and 62. After a working stroke of the motor, the driving fluid flows through holes of exhaust 63 in the stator 51, and then downwardly through an annular channel circumjacent the stator 51 and flow channels 65 in a lower support assembly 64. A portion 66 of the rotor 53 extends through a bottom support bracket 64. The rotor 53 moves on thrust bearings 67 with respect to the lower support assembly 64 and seals 68 seal the rotor-support assembly interface. Also the drive fluid that flowed through the flow channels 35 in the lower support assembly 34, flows downwardly through channels 79 in the upper support assembly 54, past the stator 51 and through the raceway channels. flow 65 in the lower support assembly 64. The upper support assembly 54 and the lower support assembly 64 are a slight fit in an outer tubular member 18 and are held against rotation by compression between the threaded sleeve 84 and a threaded sleeve lower (not shown). Figures 2A-2D and 3A-3D illustrate a typical cycle for the motors, first and second, 20 and 50 respectively, and show the state of the two motors with respect to each other at various times in the cycle. For example, Figure 2C shows an escape period for the first engine 20 while Figure 3C, at the same time, shows a power period for the second engine 50. As shown in Figure 2A, the driving fluid that flow through the flow channels of the rotor 28 enters the action chambers 31 and 32. Due to the geometry of the chambers (as discussed below) and the resultant forces, the driving fluid moves the rotor in the direction of the hands of the clock as seen in Figure 2B. The action chamber 3 is sealed at one end by a rotating vane rod 71 which strikes an outer surface 72 of the rotor 23 and a portion 74 of a rod recess 75. At the other end of the action member 31, a seal in a lobe 77 of the rotor 23 it collides hermetically with an inner surface of the stator 21. As shown in Fig. 2B, the rotor 23 has moved to a point near the end of a power period. As shown in Figure 2C, the drive fluid initiates exhaust at this point in the engine cycle through the exhaust holes 33. As shown in Figure 2D, the rotating vane rods 71 and the seals 76 have sealed hermetically the action chambers and the motor fluids flowing therein will rotate the rotor 23 until the seals 76 again move past the exhaust ports 33. The second motor 50 operates as the first motor 20; but, as is preferred, and as shown in Figures 3A-3D, the two motors are out of phase at 90 ° so that while one motor is discharging motor fluid the other is providing power. In one embodiment, the seals 76 are made of polyethylethylacetone (PEEK). The rotating vane rods 71 are also made of PEEK. The rotors (23, 25) and the stators (21, 51) are preferably made of corrosion resistant materials such as stainless steel. When a seal 76 in the first motor 20 rotates past an exhaust port 33, the driving fluid that caused the rotation exits and flows downward, then through the channels 79, past the exhaust ports 63 and the flow channels 65. Referring now to Figure 4 there is shown a first embodiment of a subsea digging apparatus according to the present invention, generally designated 100. The apparatus 100 comprises a connector body 105 having an internally threaded frusto-conical portion 110 for its connection to a drill pipe, coiled pipe or any pipe capable of transporting drive fluid to drive the drill motor 10 provided within the apparatus 100. The connector body 105 has a through bore 115 which communicates with the central sub-channel 12 of the motor 20. An external pipe 120 is rigidly connected to the connector body 105, such that a portion of the connector body 105 is located co n the outer pipe 120. Around an external surface of the connecting body portion 105 a first part of a pivot 125 is rigidly connected. The pivot 125 comprises first and second parts, rotatable with respect to each other. The second part of the pivot 125 is rigidly connected to an upper part 11 of the motor 10 whose part is rigidly clutched with the stator 21. The pivot 125 is in this mode a known "gland" including radial supports and combined thrust bearings. Accordingly, it is apparent that the rotors 23, 53 are rotatable with respect to the stators 21, 51 and with respect to the external pipe 120, while the stators 21, 51 are rotatable by themselves with respect to the external pipe 120. The portion 66 of the rotor 53 is rigidly connected to one end of a motor shaft 130 by means of a female spine coupling provided on the motor shaft 130. On the other side of the motor shaft 130 a first injector is provided in the form of a first Injector 135. The stator 51 is rigidly clutched with a second injector in the form of a second injector 140 by means of bolts 145 connecting the second injector 140 to a flanged portion 150 at the end of the outer tubular member 18 of the engine 50. The injectors , first and second, 135, 140 are connected together by a combined thrust bearing and radial support 155. Accordingly, it is apparent that the first injector 135 rotates with the rotors 23, 53, while the second injector 140 rotates with the stators 21, 51. At the end of the outer tube 120 a flanged portion 160 is provided. Under the flanged portion 160 a marine support 165 is provided. A hollow body 170 is connected to the flanged portion 160 by means of bolts 169. The hollow body 170 has at an inlet thereto, four inlet guide vanes 175. In an outlet to the body 170 is provided a plurality of exit guide blades 180. Guide blades 175, 180 are provided in order to produce a predefined flow of water through the hollow body 170, as is known in the art. A safety grid 185 is provided within the inlet of the hollow body 170. Circumferentially spaced equidistantly about the hollow body 170 a plurality of (in this embodiment 8) longitudinal reinforcement strips 186 is provided.

Circumferentially around the outlet of the hollow body 170 are provided steering means in the form of four equally spaced openings 190 in the hollow body 170 in a plane through the apparatus 100, whose plane attempts to be substantially horizontal in use. Each opening 190 has a gate 195. Each gate 195 provides a portion whose portion extends inwardly when the gate 195 is in (in order to direct-or empty-water through the respective opening 190), the portion further closes the opening 190 when gate 195 is closed. Each gate 195 is openable and lockable by control means in the form of electric or hydraulic actuators 200 connected to gate 195 by connector members 205 and carried by a flange 210 provided around hollow body 170 The actuators 200 are controlled by an electrical connection (not shown) that extends above the surface. Referring now to Figures 5A-5C and 6A-6C, detailed drawings of the first and second injectors 135, 140 are shown. As can be seen, each injector 135, 140 contains six blades. The injectors 135, 140 are substantially identical except that their blades move relative to each other at 180 ° so that the injectors 135, 140 rotate in opposite directions of rotation. Referring to Figure 7, the apparatus 100, for being submerged in the sea, connected to a hose reel 215 provided, for example, in the stern of a ship 220. In use, the apparatus 100 is lowered to the desired position. , for example, just above the bottom of the sea as it is known in the matter. The position of the apparatus 100 can be controlled by the positioning means by the controlled opening / closing of the gates 195 and the operation of the injectors 135, 140. Once in the desired position, the apparatus 10 can be operated by pumping motive fluid towards the drilling motor 10. The rotors 23, 53 consequently start to rotate thus directing the first injector 135 in one direction. In addition, the second injector 140 also begins to rotate by taking the reactive torque of the first injector 135. Accordingly, the injectors 135, 140 rotate at the same speed in opposite directions. Referring to Figure 8, a second embodiment of an underwater excavation apparatus according to the present invention is shown. The parts of this second embodiment are identified by the same integers as the parts of the first embodiment, but suffixed. An apparatus shown in FIG. 9 comprises an injection pipe that is shown in its entirety by 301, and in which the first screw 302 and the second screw 303 are rotatably accommodated. The first screw 302 is mounted on the hollow shaft 304, while the second screw 303 is mounted on the shaft 305, which runs coaxially through the hollow shaft 304. Both shafts 304 and 305 are operable by means of the drive unit 306, which may also contain an inverting device, such that the axes 304 and 305, and therefore the screws 302 and 303, are operable in opposite directions of rotation. Since the pitch angle of the screw blades 307 of the first screw 302 is opposite to the pitch angle of the screw blades 308 of the second screw 303, the two screws 302, 303 create a downward flow here, traveling through the access lattice 309 through the injection pipe 301 and out of the nozzle 310. A discharge nozzle 318 is shown in Figure 10. The flanges 312 They can also act as flow guide deflectors. Flow guide deflectors 341 can be accommodated in nozzle 310. It is also possible to fit flow guide deflectors between screw 302 and 303, in order to reduce undesirable turbulence. Both axes 304, 305 are accommodated in a housing 311, from which the liner 313 of the injection pipe 301 is suspended by means of flanges 312. At its upper end, the housing 311 is connected by means of a rotating support to the upper part 314, to which a lifting cable 315 can be fixed, and from whose upper part 314 one or more electric and / or hydraulic lines 316 for the drive unit 306. The liner 313 of the injection pipe 301 is provided on the outside with radial projections 317, which give the liner 313 the necessary stiffness. The alternative nozzle 318 shown in the figure is designed so that it sharpens down. When such a taper nozzle 318 is used, a greater flow rate of flow coming from outside the injection pipe 301 can be obtained. Since the first screw 302 rotates in the opposite direction to that of the second screw 303, and the screws 302 and 303 are more identical, with the exception that the pitch angle of their screw blades 307, 308, the resultant torque in operation about the longitudinal axis of the device is equal to zero. The very stable operation of the device can be obtained in this way, without additional measures being necessary for stabilization. Figure 11 shows a first potential application of the apparatus according to the invention. The apparatus, indicated in its entirety by 319, is held by means of the cable 315 in relation to the container 320. The distance from the bed 321 of the water body in which the container 320 is located in this case is selected from the apparatus of according to the invention which can form a trench 323 in said water bed 321. In order to keep the apparatus 319 in place during the forward movement of the container 320, a stabilizing cable 324 is provided, whose cable 324 has at its lower end a balancing weight 326. Said balancing weight 326 moves together with the apparatus in a fixed position relative to the container 320 and the water bed, the connecting cable 327 between the balancing weight 326 and the apparatus according to the invention which ensures a corresponding position of said apparatus. Instead of the cables 324 and 327 and the balancing weight 326, it is also possible to ensure the correct positioning of the apparatus by means of a stabilizing cable 325. Under normal circumstances, the container will make a movement in relation to the water bed 321 which coincides with your course. However, this course is changed when there are transverse flows in the body of water. In that case, it can happen that the apparatus 319 takes a path on the water bed 321 that forms an angle with the course of the container 320. The desired course of the trench 323 in the water bed 321 can be achieved by adjusting the course of the container 320, that is, directed at an angle to any transverse flow. In the embodiment in Figure 12, the apparatus 319 according to the invention is connected to the container 320 by means of a single stabilizing cable 328 and the lifting cable 315. In this case, the apparatus 319 is tilted slightly forward and downwardly. , so that the jet 322 is directed not only downwards but also towards the front. This means that the spilled material moves better in a desired direction. It is also possible to suspend the device at an angle in another direction by fixing the cables 315 and 328 in a different place in the container 320, for example on both sides. Another variant is that one of the cables 315 or 328 is fixed in another container. Figure 13 shows the situation according to figure 12, but in this case, the device 329 is provided with transversely directed, controllable drive screws, which better position the device 329. Instead of drive screws, they could be used also jets of water, possibly placed in injection pipes. In the possible embodiment of Figure 14, the apparatus 329 according to the invention is suspended from a floating container or platform 332 by means of a chain of metal tubes 331. As is customary in the case of drilling installations, the chain 331 is suspended in a tower 333, which is equipped to assemble and take chain 331. Such an apparatus is very suitable for greater depths of water, of several hundred meters. Figure 15 shows an alternative discharge nozzle, comprising a pipe section 350 for mounting to the apparatus. The pipe section 350 is connected to a support structure consisting of arms 351. At the upper end of said support structure, two regulating devices 352 are located. Each regulating device 352 comprises an arc-shaped baffle plate 353 as well as a planar closure plate 354. The plates 353, 354 of each device 352 are mutually connected by means of articulated structures 356, so as to move as a unit each round joint 357. The plates 353 are partially located in the discharge path from the pipe section 350, whereby the flow is diverted partially to the sides and descending or ascending (depending on the position of the plates 353), as indicated by the arrows. In this way, the lower material can be removed in a more efficient manner from a trench. Cylinder-piston devices 358 are provided to establish the position of the regulating devices 352. As indicated by the dotted lines 359, the regulating devices 352 can be placed in such a position that the plates 354 close, whereby they are directed to the flow completely to the sides. Figure 16 shows a discharge nozzle comprising a pipe section 360, which opens outwardly through a single downstream pipe 361, and two opposite, curved pipes 362, which are directed to the sides and descending way or ascending way. This discharge nozzle offers an effluent in a downward direction as well as in a lateral and downward or upward direction.

Claims (32)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and therefore the property described in the following claims is claimed as property. 1. An underwater excavation apparatus (319, 329) to create a local water flow or water jet in a body of water, such that the bed material coming from the bed (321) under said body of water can be displaced, which device comprises an injection pipe (301). ), a screw (302) rotatably positioned in the injection pipe, means for supplying a counter torque in the direction opposite to the torque exerted on the device through the rotation of the screw, and cable means (315, 324, 325, 327, 328) or chain means (331) for positioning the apparatus with respect to the bed (321), characterized in that a second screw (303) is accommodated in the same injection pipe (301) and coaxially with respect to the first screw ( 302), whose second screw is rotatable is the direction opposite to the direction of rotation of the first screw (302), the direction of the screw being opposite and the combination of the step with its speed being such that the generated torque is the same. or virtually the same as that of the first screw (302). The device according to claim 1, characterized in that the pitch angle of the second screw is opposite that of the first screw. The device according to claim 1 or 2, characterized in that the first screw (302) and the second screw (303) are arranged coaxially in the injection pipe (301). The device according to claim 3, characterized in that one of the screws (302) is connected to a hollow motor shaft (304), and the other screw (303) is connected to a central motor shaft (305) which passes coaxially to through the hollow motor shaft (304). The device according to claim 4, characterized in that both drive shafts (304, 305) are projected from the injection pipe (301) at the input end thereof, and each one is connected to a drive unit ( 306). The device according to one of the preceding claims, characterized in that the outlet end (318) of the injection pipe (301) is sharpened. . The device according to one of the preceding claims, characterized in that the injection pipe (301) is provided with transversely directed, controllable water displacement means (330). 8. The device according to one of the preceding claims, characterized in that the injection pipe (301) can be placed at an angle towards the vertical. The device according to one of the preceding claims, characterized in that the means for driving the screws includes a drilling motor. The device according to claim 3, characterized in that the drilling motor is one of an electric motor "oineau", suitable or hydraulically adapted. The device according to claim 10, characterized in that the drilling motor comprises a stator and a rotor rotatably mounted on the stator, the stator being provided with a rod recess and an exhaust port, the rotor being provided with a rotor channel and at least one channel for driving driving fluid from the rotor channel into a chamber between the rotor and the stator, providing the recess rod with a rod which, in use, forms a seal between the stator and the rotor. The device according to claim 11, characterized in that the rotor is provided with a seal for its clutch with the stator. 13. The device according to claim 12, characterized in that the seal is made of a material selected from the group consisting of plastic materials, polyethylethylacetone, metal, copper alloys and stainless steel. The device according to any of claims 11 to 13, characterized in that the rod is made of a material selected from the group consisting of plastic materials, polyethylethylacetone, metal, copper alloys and stainless steel. 15. The device according to any of claims 11 to 14, characterized in that the stator is provided with two recesses of rod that are placed opposite each other, and two exhaust holes that are placed opposite each other, providing each of the recesses of rod with a respective rod, having two seals that are placed opposite each other. 16. The device according to claim 9, characterized in that two drilling motors are provided with their respective rotors connected together, each motor comprising a stator and a rotor rotatably mounted on the stator, the stator being provided with a rod recess and a Exhaust orifice, provided to the rotor with a rotor channel and at least one channel to drive the driving fluid from the rotor channel to a chamber between the rotor and the stator, being provided to the rod recess with a rod that, in use, forms a seal between the stator and the rotor. 17. The device according to claim 16, characterized in that the drilling motors are connected in parallel. 18. The device according to claim 16, characterized in that the drilling motors are connected in series. The device according to any of claims 16 to 18, characterized in that the drilling motors are installed so that, in use, one drilling motor operates out of phase with the other. The device according to claim 19, characterized in that each drilling motor has two chambers and the chambers in the first drilling motor are 90 ° out of phase with the chambers in the second drilling motor. The device according to claim 19, characterized in that each drilling motor has four chambers and the chambers in the first drilling motor are 45 ° out of phase with the chambers in the second drilling motor. 22. The device according to any of claims 1 to 21, characterized in that it comprises means for directing the device, in use. The device according to claim 22, characterized in that the steering means comprises at least four openings in the device, the openings also being separated around a plane through the device, whose plane is intended to be substantially horizontal in use, openable gates in each of the four openings, and means for controlling the opening and closing of each gate. The device according to claim 23, characterized in that each gate provides a portion whose portion extends inwardly when the gate is opened (in order to direct - or empty - water through the respective opening) in addition, the portion closes the opening when the gate closes. 25. The device according to any of claims 23 or 24, characterized in that the control means comprises an electric or hydraulic actuator for each gate, each actuator being controlled by means of an electrical connection extending above the surface. 26. The device according to claim 22, characterized in that the steering means comprises one or more openable covers located at the outlet. 27. The device according to any of the preceding claims, characterized in that each screw includes a plurality of blades, the blades moving one screw by 180 ° with respect to the blades of the other screw of the pair. 28. The apparatus for excavating the device according to any of the preceding claims, characterized in that the screws are in the form of injectors. 29. The device according to claim 28, characterized in that the screws are in the form of injectors provided with jets of water at the tips thereof. 30. The device according to any of the preceding claims, characterized in that the outlet end has diverting means for directing the flow at least partially towards the sides. The device according to any of the preceding claims, characterized in that the outlet end has diverting means for directing the flow at least partially upwards. 32. The device according to claim 30 or 31, characterized in that the diverter means is selectively controllable.