NO20110155A1 - Device for reducing wear on wires in winch-powered wave power plants - Google Patents

Abstract

The invention is a device for reducing wear on wires in a winch or hoist system with a working main winch (1) in that wires can be slowly flushed over, or from above an additional winch (2), from or to the main winch (1). The additional winch is fixed at the opposite end of the cable (3) relative to the main winch. The invention comprises means for allowing such flushing to occur by itself, without the need for human monitoring or intervention. In this way, the auxiliary winch displaces the wire relative to which portions of the one that rolls most back and forth on the main winch, wear is distributed over a larger area of the wire, and the service life is extended. In this way, the invention acts as a substitute for manual "slip and cut" operations, which are used as a life-long maintenance method on drill ropes. The invention is primarily intended to be used in winch-powered wave power plants, where long-term reliability combined with low maintenance costs is particularly desirable.

Description

Background

Some wave power systems use cables, ropes or ropes or similar — hereafter referred to only as cables — connected to a winch or hoist system, to absorb and transfer mechanical energy from the waves. Among these are N0325878 and N0329110. A challenge with such systems is that they often have a tendency for certain parts of the wire to be exposed to wear and tear to a greater extent than others. This applies to winch-driven wave power plants, but also in other contexts where cables are used to transfer mechanical work, where the cable comes into contact with a winch drum or pulley wheel or the like, and where the cable moves reciprocatingly for a large part of the time of use more or less along the same the parties. The wire is typically worn most along the parts where it most often and with the greatest force rolls off and on the winch drum, around a pulley wheel or the like. Such wear leads to the cable having to be replaced after a while, so as not to risk the winch/hoist system breaking down or having an uncontrolled shutdown as a result of a cable break. An alternative to replacing the wire is to perform a so-called "slip and cut" operation, — a method used in the oil industry, as part of the maintenance of drilling rigs, e.g. to extend the life of the cable on the derrick hoist. The method involves pulling out a certain amount of wire from a winch, loosening the wire's end attachment, and making a new end attachment correspondingly further into the wire, and then cutting off the protruding end of the wire that has been left over. This is done manually when the winch has traveled a certain number of "ton-miles". This distributes the wear on the wire, and it lasts longer. For wave power, it is an important point that maintenance costs are kept at a low level, so that wave power can become economically interesting. Carrying out manual maintenance of systems standing in the sea is a cost driver. This particularly applies in periods when there is a lot of bad weather - and that is often when maintenance of the wave power systems is most needed. Shutdown in connection with maintenance also means loss of energy production and loss of income.

The present invention relates to a device which automatically shifts the wear areas on the wire in a winch or hoist system, with the same purpose being achieved as manual "slip and cut" operations. The invention solves the challenge, described in the introduction, with area-concentrated wear of the wire, without requiring human labor and without the system having to be stopped. The purpose of the invention is to increase the lifetime of the wire and reduce the need for manual maintenance thereof.

Areas of application

The invention can be used in contexts where a wire is used in such a way that

wear tends to be concentrated along certain parts of the wire, for example where the wire most of the time and/or with the greatest load rolls in contact with a pulley wheel, a winch drum or the like. Hoist and winch systems, e.g. in derricks, passenger lifts and cranes, can benefit from the invention. But where the invention has its greatest economic potential for application is in contexts where manual maintenance of cables, for example by replacement or "slip and cut", entails significant costs. Costs include here:

1) the costs of the maintenance work itself

2) loss of income (e.g. as a result of loss of production) or loss that can be calculated in another way, as a result of the system having to be taken out of operation while maintenance is in progress.

Wave power has a challenge with potentially large costs on both of these points. Wave power systems with cables are intended as the primary field of application for the invention.

Known technology

US6932553 describes a "multipurpose system for a drilling and well intervention" which contains some of the same elements as the present invention: "Two main hoisting winches 17 and 18 can be used in this invention. If two are used, each end can be wound onto a separate winch. By winding the two ends 26a and 26b each onto a separate winch 17, 18, as shown in FIG. 2, it is possible to achieve the same hoist cable speed at a relatively low speed of revolution on the winches 17, 18. (...) This design also allows hoist cable 25 that has reached its fatigue life to be wound from one winch 18 to the other 17 therefore eliminating the need to slip and cut the fatigued cable from the system thereby reducing operational nonproductive time. »

However, US6932553 does not describe any activator system with a control mechanism which ensures that overspooling occurs by itself, which is a characterizing feature of the present invention, according to claim 1. US6932553 also does not describe any differentiation in operation or structure between the two winches ("hoisting winches 17 and 18"), in contrast to in the present invention where the additional winch, according to claim 1, is slow-moving compared to the working main winch, and where the activator system — possibly with a blocking mechanism (according to claim 2) — is connected to the additional winch.

Definitions of terms

In this description, the following terms have the following meanings:

Vaier means rope or similar, such as rope, line, etc.

Overwinding means that wire is unwound from one winch: the winch to which one end of the wire is attached, and onto the other winch: the winch to which the other end of the wire is attached, or vice versa.

Activator system means a device with mechanical components — and possibly other components, e.g. electrical, electronic and/or hydraulic components —, which regulate overspooling of ropes, by determining when and under what conditions the auxiliary winch shall be activated to rotate, and to ensure that this rotation is activated.

Rotation (of the winch) outwards is rotation in the direction of rotation which causes the wire to be unwound from the winch drum.

Rotation (of the winch) inwards is rotation in the direction of rotation which causes the rope to be wound onto the winch drum.

A flow restrictor is a part of a hydraulic passage that functions in such a way that it limits, or under certain conditions prevents — in whole or in part — the hydraulic flow through the passage.

Figures and reference numbers

Figure 1 shows an embodiment of the invention with the main elements main winch 1, additional winch 2, and the activator system 4 which controls the additional winch, and an exemplified embodiment of the blocking mechanism for the additional winch. Figure 2 and Figure 5 show one possible way in which the invention can be integrated with a winch-driven wave power plant. Figures 3 and 4 show details of the same, with the same exemplified embodiment of the blocking mechanism 5,6 as shown in Figure 1. Figure 6 shows another example of how the invention can be integrated into a winch-driven wave power plant, with main winch 1 and additional winch 2 attached to the same structure under water and a pulley 13 attached to the float so that the winch system and the pulley together form a pulley for the wire 3. Figure 7 shows an example of a hydraulic implementation of a sensor and activator system for controlling the additional winch. Figure 8 and Figure 9 show alternative blocking mechanisms for the additional winch.

Description

A main winch 1 has winch cable 3 rolled onto it, and the other end of the winch cable is rolled onto an additional winch 2 at the opposite end of the cable stretch.

The main winch is the working winch in the system, i.e. the one that rolls in and out the most. Combined with the wave power system described in N0325878, this coincides with "winch 2" (see page 9, line 27). Matched with N0329110, it coincides with "drum 10" (see page 6, line 18).

The auxiliary winch's function is, at a low speed compared to the main winch, to reel over the wire, so that the most exposed areas of wear on the wire are moved, slowly but surely, as the main winch performs work that causes wear. This overspooling can either take place by extra cables that were previously spooled onto the main winch being spooled onto the additional winch. Or by extra cables from the additional winch being unwound from this and onto the main winch. The latter is the preferred method, as this requires less energy, in that the pulling force, which acts from the cable (main winch) on the auxiliary winch, and the cable movement has the same direction.

The additional winch is controlled by an activator system 4. This activator system controls the overflow of wire and determines whether, to what extent and under what conditions the additional winch should be allowed to rotate. The activator system 4 may contain a blocking mechanism which prevents the additional winch from rotating out as a result of traction on the wire applied from the outside. In Figures 1 - 7, this blocking mechanism is embodied as a worm gear, with a worm gear wheel 5 mounted on the auxiliary winch's shaft, and a worm screw 6 in contact with the worm gear wheel, mounted with the worm gear shaft parallel to the tangent of the worm gear wheel disc in the plane of the worm gear wheel. The angle of the worm's threads is sufficiently close to 90° in relation to the worm's shaft, so that the frictional force becomes greater than the thrust force when a torsional moment acts from the worm gear wheel 5 on the worm 6. The worm gear thus becomes self-blocking, so that rotation of the gear can only take place with incoming torque from the auger shaft. This is the standard way of constructing a self-locking worm gear well known to mechanical engineers. The embodiment of the blocking mechanism described here, and shown in the figures, is given as an example. It is only one of several possible and known to engineers ways that can be used to block the additional winch, so that only torque applied to the additional winch from the activator system 4 can cause the additional winch to rotate.

The activator system 4 comprises a motor control unit 7, which regulates the activity of the activator system. The motor control unit contains a motor and means for controlling this motor. □ Mastering □ here means being able to determine the work rate of the engine and/or start and stop it. The term □ motor □ is used here in a broad sense, and refers to a device that causes rotation of the auxiliary winch, for example by one or more mechanical elements having the ability to perform work to rotate the auxiliary winch and/or suspend the activator system's blocking mechanism (so that rotation of the additional winch can be done with the help of external power). In principle, this can be any device that can be constructed by a professional, as long as it entails this capability. In the embodiment to which Figure 7 refers, the motor of the motor control unit is identical to the hydraulic motor 19. But the motor of the motor control unit is not limited to being a hydraulic motor, as shown in Figure 7. Nor are the means for controlling the motor limited to being the same as shown in figure 7. The motor control unit controls when the additional winch should wind over the cables, and how much. In the exemplified embodiment of the worm gear activator system, this occurs by the motor control unit rotating the worm screw. The rewinding rate can be time-controlled, or determined by other parameters, for example: the frequency of force impulses (jerks) in the winch cable above a certain strength, or the product of force and distance traveled by the cable (number of "ton-miles").

With reference to the embodiment shown in Figure 1, time-controlled overwinding can be implemented by the motor in the motor control unit being some device with mechanical elements, with which an engineer will be familiar — for example, a device with a tensioned spring —, which above time does work on the worm shaft and causes it to rotate. Any kind of clockwork mechanism can in principle be used for this.

Overwinding determined by the frequency of power impulses in the wire above a certain strength can be achieved, for example, by utilizing the force that acts axially on the auger's shaft when the wire is exposed to said power impulses, while allowing this force to activate a certain rotation of the auger, using mechanics, to which a person skilled in the art submitted to the task, without inventive effort, will have no difficulty in producing the means to perform the function of.

Spooling as a function of work done by the winch (number of "ton-miles") can be implemented, for example, by having electronic sensors record workload and distance traveled for the main winch, and by feeding this data into a processing unit, for example a computer in the engine control unit, which calculates, on the basis of the input data, how much wire is to be spooled over, and executes this spooling by activating the motor control unit's motor, which here can be an electric or hydraulic motor, for example. Although, with today's technology, it may be preferable to implement such a sensor and activator system based on electronics and electrical signals, in principle there is nothing in the way of implementing it purely mechanically or hydraulically. This is also something that a specialist in the field can be expected to be able to carry out with ease, without inventive effort. An example of such a hydraulic implementation is shown in Figure 7 and explained below. The elements 14 - 18 in the figure show, simplified, a mechanical-hydraulic system for transforming and passing on wave energy that is absorbed by the winch 1. This corresponds to parts of the hydraulic subsystem described in N0329152.1 the implementation exemplified in figure 7 and in the following description , the sensor and activator system is integrated with this. It is assumed that there is a passage from the hydraulic system connected to the main winch to the auxiliary winch's motor control unit. If the main winch 1 and additional winch 2 are both fixed to the same structure, as in the example shown in figure 6, it is uncomplicated to construct such a passage. The main winch continues its rotating movement to a gear 14 which causes the output shaft 14b from the gear to rotate faster than the winch drum. The output shaft is connected to a one-way clutch 15, which works so that only outward rotation of the main winch is transferred to a hydraulic pump 16. The pump is connected to a turbine unit with a power-take-off system 17. The turbine unit and power-take-off The off system is not described in more detail here. It can be assembled as described in N0329152, or have a different design that acts to restructure the energy from the pump 16 into useful energy. The point here is that every time the winch cable 3 is pulled out, there will be a hydraulic flow from the pump 16 to the turbine unit 17. The hydraulic passage that connects the pump to the turbine unit has a side run. This side run leads, via a flow restrictor 20, to a hydraulic motor 19 in the motor control unit 7. The flow restrictor can be a throttle valve as shown in figure 7, a flow control valve, a narrowing of the hydraulic passage or another hydraulic component that limits the hydraulic flow to the motor 19. When the pump 16 is activated as a result of unwinding rotation of the winch, a small part of the flow from the pump will pass through the flow restrictor and activate the hydraulic motor 19 which thus causes the additional winch to rotate. Depending on which way the motor 19 is mounted in relation to the additional winch's direction of rotation, the additional winch will rotate outwards and reel out cables, or inwards and reel cables in on itself. Both mounting directions will work in relation to fulfilling the function of the invention, although the mounting direction which provides rotation of the additional winch outwards will require less energy from the motor 19.

Another possibility is to let the activator system 4, which controls the additional winch, be operated manually. (Manual operation of the auxiliary winch can be arranged — for example — by replacing the motor control unit 7 with a hand crank.) Or it can be remotely controlled.

The worm gear mechanism shown in Figures 1 - 7, and based on what has been described above, is one of several possible embodiments of the blocking mechanism for the additional winch. In principle, this can be replaced with any blocking mechanism, regardless of design, whose function is to prevent force from the cable from moving the additional winch but not vice versa.

An alternative to using a worm gear or a similar blocking mechanism (ie a blocking mechanism whose function is to prevent force from the wire from moving the auxiliary winch but not vice versa) is to use a one-way blocking mechanism. Figure 8 shows the additional winch with such a one-way blocking mechanism made in the form of a ratchet. Another embodiment is shown in Figure 9, where inclined locking pawls 21a,b are laid next to the wire 3 and prevent it from being pulled out from the additional winch. The locking pawls are located next to the wire with the free end pointing in the direction of the wire outwards from the additional winch, at a suitable angle, so that the locking pawls wedge the wire between them when the wire is tried to be pulled out of the additional winch, and so that the wire detaches from the wedge grip when the additional winch starts to wind wire in, and the locking pawls then — as long as the wire moves in the winding direction — freely allow the wire to slide past.

A one-way blocking mechanism works by allowing movement in one direction — here: in the winding direction of the auxiliary winch — but blocking movement in the opposite direction. This works without further ado for the overspool configuration where the activator system is set to spool wire onto the auxiliary winch. However, a ratchet, or equivalent, can also act as a blocking mechanism for the overspool configuration where ropes are spooled onto the main winch. But this requires a more sophisticated functional structure of the ratchet and the motor control unit 7, in that the motor control unit can actively suspend the blocking by tilting out the ratchet's blocking pawl 22 so that the ratchet tooth wheel 23 can rotate beyond one segment before it is again blocked by the pawl.

In the overwinding configuration, where the overwinding occurs by extra wire from the main winch being wound over to the additional winch, the additional winch will over time have more and more wire wound onto it, while the amount of extra wire on the main winch decreases. The additional winch must then be sized to have room for as much extra wire as you want the main winch to be able to provide. In the overflow configuration where extra wire from the additional winch is spooled onto the main winch, the amount of wire on the main winch will increase over time, while it decreases on the additional winch. The main winch must then be sized to have room for the desired amount of extra cables from the additional winch. Regardless of configuration: When the amount of extra wire in this way is "used up", it is time to carry out manual maintenance, by removing the old wire and adding new wire, with extra wire wound onto the correct winch. It is also possible, and probably desirable, to implement a warning system, for example connected to the engine control unit 7, which notifies the operators of the winch system when it is time to change ropes.

The point of the invention is that the time that elapses between each time manual maintenance of the wire must be carried out is extended, and that this saves costs.

Examples of integration of the invention in a winch-driven wave power plant

A winch-driven wave power plant has a winch, which here coincides with the main winch 1, which provides energy transfer from a wave energy absorbing unit, which is exemplified here as a float 8, as can be seen from figures 2, 5 and 6. The main winch 1 is set in motion of the waves, and this changing movement is further channeled into a power conversion machinery (not described in more detail, as the structure of this varies from wave power system to wave power system), where the energy is transformed into useful energy, for example electric current. Here, as in N0325878 and N0329110, the winch 1 is self-tightening, and thus reels in automatically when the pulling force from the wire is sufficiently low.

Figures 2 and 5 show a winch-driven wave power plant where the wave energy-absorbing winch 1, i.e. the main winch, is placed in a winch unit 9 underwater, anchored to the seabed or a deeper-lying structure by means of an anchoring element 10 (in the figures shown as a chain). The figures also show, starting from the winch unit in the same direction as the anchoring element: an umbilical cord 11, that is to say a cable for transmitting electric current and possibly control signals from the power plant to shore. The winch unit 9 is connected by cable 3 to the float 8, which floats in the water surface 12. The additional winch is here attached to the float. Figures 2 and 5 show an exit of the wire from the additional winch through a funnel 24 in the float and out through a bending stiffener 25 on the underside of the float.

A configuration with the additional winch attached to the float can also be integrated with a design of a winch-driven wave power plant where the winch unit is on land, as in N0325878 Figure 4. Alternatively, the winch unit 9 with the wave-powered winch 1 and the additional winch 2 can switch places, which would mean that the winch unit is inside the float, as in N0329110, and the additional winch with activator system 4 is underwater.

Figure 6 shows yet another alternative configuration, where both the main winch 1 and the additional winch 2 are attached to the winch unit 9, underwater. The cable stretched from the main winch to the auxiliary winch passes through a pulley wheel 13 connected to the float — also called a block. The cable 3, the pulley wheel and the two end attachments of the cable, respectively on the main winch and the additional winch, on the same structure, namely the winch unit 9, together form a hoist. This pulley arrangement will cause the main winch to be rotated when the waves lift the float, and it will work so that the cable at the main winch moves twice as fast as the float, which in the context of wave power can be considered an advantage, as it gives an up-gear to the movement of the main winch. One of the problems with the utilization of wave energy is that the wave movements are initially very slow. Gearing up this movement is therefore appropriate, because the transmitted effect can then be handled in the form of smaller forces and lower torque, and consequently with a lower dimensioning of the components.

With a pulley arrangement as shown in figure 6, the forces from the float on the wire will be lower, about half as great, because there are two wire ends that hold the float. Thus, both the wire 3 and the main winch 1 can be downsized, and still be able to perform the same amount of work, which can also be considered an advantage. Another advantage of such an arrangement is that it makes it easier to implement an overflow function for the additional winch based on input data from sensors arranged in connection with the main winch — whether these sensors are electronic, hydraulic or mechanical.

Figure 6 shows a single pulley (gear factor x 2). But the same arrangement of main winch and additional winch can be used with a double hoist (four-turn hoist) (gear factor x 4), a six-turn hoist (gear factor x 6), etc., to obtain an even greater gearing factor, if desired. A luff hoist (gear factor x 3) or gyn hoist (gear factor x 5) etc. is also possible, but then one of the winches, the additional winch or the main winch, must be attached to the float.

Claims (9)

1. A winch device with a cable (3), a main winch (1) at one end of the cable, and at the other end of the cable an additional winch (2) characterized in that the additional winch (2) rotates slowly compared to how fast the main winch typically rotates and that the additional winch is controlled by an activator system (4) comprising a motor control unit (7), which controls overspooling of wire in one direction between the two winches to displace the wire in relation to the drum of the main winch and other possible elements with which the wire is in wear-causing contact , so that wear over time is distributed over larger parts of the wire. 2. Device according to claim 1 where the activator system (4) contains a blocking mechanism which prevents external traction on the wire (3) from rotating the additional winch (2) without this being determined by the activator system (4). 3. Device according to claim 2, where the blocking mechanism is a worm gear, with a worm gear wheel (5) connected to the auxiliary winch, and a worm screw (6) connected to the rest of the activator system (4), which blocks the transfer of rotary power movement from the auxiliary winch to the activator system, but not vice versa. 4. Device according to claim 2, where the blocking mechanism is a one-way blocking of the additional winch, which prevents cables from being pulled out, but freely allows cables to be wound onto the additional winch (2) by activating the blocking mechanism as a result of cables being attempted pulled out, but deactivated by inward movement. 5. Device according to claim 4 where the one-way blocking is a ratchet, with a ratchet tooth wheel (23) connected to the additional winch (2) and a blocking pawl (22) on the ratchet tooth wheel, which blocks rotation of the ratchet in one direction. 6. Device according to claim 5 where the motor control unit (7) can remove the pawl (22) and allow the ratchet to rotate in the blocking direction. 7. Device according to claim 4 where the one-way blocking is angled locking pawls (21a, b) placed next to the wire (3) in such a direction and at a sufficient angle that they wedge the wire when the wire is tried to be pulled out of the additional winch (2) , but detaches from the wedge grip and lies free when the additional winch reels in the wire. 8. Device according to claims 1 - 7, where the motor control unit comprises means for controlling rotation of the additional winch. 9. Device according to one of claims 1-7, where the motor control unit comprises a processing unit adapted to send signals to a motor in the motor control unit for controlled rotation of the additional winch.