Hydraulic and earth engineering – Subterranean or submarine pipe or cable laying – retrieving,... – Submerging – raising – or manipulating line of pipe or cable...
Patent
1997-12-08
2000-04-25
Lillis, Eileen Dunn
Hydraulic and earth engineering
Subterranean or submarine pipe or cable laying, retrieving,...
Submerging, raising, or manipulating line of pipe or cable...
405 73, 405226, 405248, 37323, 37327, 37331, 37343, 416129, E02F 388, F16L 120
Patent
active
060536632
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a device for creating a local water flow or water jet in a body of water, in such a way that bed material from the bed below said body of water can be displaced, which device comprises a jet pipe, a screw disposed rotatably in the jet pipe, and means for supplying a countertorque in the opposite direction to the torque exerted on the device through the rotation of the screw.
2. Description of the Related Art
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 which trench a pipeline, for example, can be laid. For this purpose, the device is moved at some distance above the water bed along the path in which the trench is to be made. The rotating screw in this case supplies the desired water flow.
Since the rotating screw exerts a torque on the device, unless countermeasures were taken, the device would start to rotate uncontrollably about its axis, which is, of course, very undesirable. On account of that, blades are provided in the outlet of the jet pipe, which blades exert a countertorque on the device as a result of the water flow in the jet pipe, in such a way that the device is stabilized as regards such a rotary movement.
A great disadvantage of this device is that the torque generated and the countertorque are the same for a specific outflow rate of the water flow in the jet pipe only within a limited speed of rotation range. On variation of the distance of the device from the bottom, said outflow rate varies, and therefore so does the countertorque.
The torque generated and the countertorque are not easy to keep the same during operation of the device. Rotation of the device therefore has to be prevented by other, additional means.
SUMMARY OF THE INVENTION
The object of the invention is therefore to provide a device of the above mentioned type which does not have these disadvantages. That is achieved through accommodating a second screw in the jet pipe, which second screw is rotatable in the opposite direction to the direction of rotation of the first screw, the screw direction of which being opposite and the combination of pitch with its speed of rotation being such that the torque generated is the same or virtually the same as that of the first screw. The pitch angle is preferably opposite to that of the first screw.
The second screw not only provides the desired countertorque, as a result of which the device remains stable, but also contributes to more efficient functioning of the device as regards the displacement of bed material such as, for example, during the making of a trench in the water bed. This means that no energy is lost during the stabilization of the device.
Through a suitable choice of the second screw it can also be ensured that the required countertorque is always supplied, with the result that no further measures need be taken for synchronizing the operation of the screws.
The first screw and the second screw are preferably accommodated coaxially in the jet pipe; in that case one of the screws can be connected to a hollow driving shaft, and the other screw can be connected to a central driving shaft running coaxially through the hollow driving shaft.
Both driving shafts can project from the jet pipe at the inlet end thereof, and can each be connected to a drive unit. At the top end of the jet pipe suspension means can also be provided, for suspension of the device from a bearing element such as a cable, which is in turn connected to a vessel on the water surface.
The device can also be used for covering pipes, levelling the water bed, jet washing articles or moving quantities of soil etc.
At the outlet side of the jet pipe the device can have various types of nozzles, which can be a round, oval or rectangular shape.
The means for driving the screws may include a drilling motor.
The drilling motor may be a "MOINEAU(.TM.)", hydraulic or suitably adapted electric motor.
Alternatively and advantageously the drilling motor may comprise a st
REFERENCES:
patent: 142577 (1873-09-01), Morse
patent: 3235232 (1966-02-01), Conover
patent: 4585401 (1986-04-01), Baldenko et al.
patent: 4932144 (1990-06-01), Sills
patent: 5171139 (1992-12-01), Underwood et al.
patent: 5249378 (1993-10-01), Frame
Dikken Jacob Jan
Lucieer Willem Jan
Smit Paul
Stewart Kenneth Roderick
Van Denham-Susman Hector Filippus Alexander
Lillis Eileen Dunn
Mayo Tara L.
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