Crane

Abstract

The invention relates to a crane (100) with a luffable boom (105) and a boom restrainer (120) for restraining undue accelerated upward pivoting of the boom, e.g. in case of loss of load. A rigid element (121) extends between the boom and the crane structure (104) above the boom pivot axis. It is movable with the boom as it is pivoted upward, and engaged with the boom when upright. Passive countering means (130) provide clearance for movement of the element, and upon a release, use stored energy to engage the element to counteract upward boom pivoting. Active clearance means (140) initiate said release by upon detection of an anomalous situation - otherwise they keep the passive means in a state of stored energy thereof.

Description

[0001] Title: CRANE

[0002] The invention relates to a crane, e.g. for use on an offshore vessel, e.g. the crane being mounted on a vessel. The crane may be embodied as a heavy lift crane for use in offshore applications, e.g. for wind turbine installation, more in particular for installation of monopiles for supporting wind turbines. The invention further relates to an offshore crane vessel comprising such a crane, and to a pile installation method in which use is made of such an offshore crane vessel.

[0003] In the field of cranes, in particular offshore cranes, there is a trend towards larger cranes, in particular for installing monopiles for supporting offshore wind turbines. Installing offshore wind turbines at locations with larger water depths than currently encountered, results in larger and heavier foundations. Hence, it is expected that in the near future monopiles need to be installed that are longer than 100 meters. The mass of such monopiles may be more than 1000 mt, e.g. more than 1500 mt, e.g. more than 2000 mt. In the Arcadis Ost 1 windfarm, monopiles of 110 meters and 2000 mt have recently been installed. The installation of larger and heavier monopiles may be expected to be necessary in the near future: e.g. 130 meter monopiles are under development, and even longer ones may be expected.

[0004] Larger and heavier monopiles, require larger and heavier offshore cranes, in particular require cranes having a long boom combined with a high lifting capacity. Typically, cranes for installing monopiles are slewing cranes. The cranes can e.g. be pedestal mounted cranes, be around-the-leg cranes, or be mast cranes. The cranes have a boom for supporting and positioning the monopile. The length of these crane booms may be 150 meters or more.

[0005] In addition there is also a trend to install these piles from a floating vessel. Once overboarded, the pile is vertically lowered into the sea next to the vessel.

[0006] Lifting these heavy loads over the side of the vessel, also referred to as overboarding, may require the vessel to be stabilized, to prevent the hull of the vessel from tilting sideways, also referred to as rolling, during the installation procedure. Typically, ballast in the form of ballast water tanks is used to counter balance for load supported by the crane, and to thus keep the floating vessel level. It is observed that herein, roll is defined as the tilting rotation of a vessel about its longitudinal axis (front-back or bow-stern) axis. Furthermore, rolling motion towards a steady state (or list) angle due to the ship's own weight distribution is referred to as heel. List refers to an unintentional or unexpected offset, as caused by flooding, shifting cargo, etc. Roll is typically in play when overboarding and lifting a load along a side of the vessel, e.g. at starboard or port side of the vessel.

[0007] The lifting and lowering of long piles makes that the boom is mainly in a raised, near-vertical or substantially vertical, position, typically between 70 and 85 degrees with the horizontal - i.e. between 15 and 30 degrees with the vertical. On a vessel the horizontal would be considered parallel to the deck, assuming the deck is kept level. In this raised position of the boom, the boom is relatively close to the crane structure. An undue sudden reduction in load, e.g. by partial or complete loss of the load supported by the crane, e.g. due to a breakage of the hoisting cable, or a sudden movement of a vessel on which the crane is mounted caused e.g. by a freak wave, may cause the boom to be lifted further upwards. The lift is caused by the release of bending and stretching forces in the crane, in particular the boom and the wires supporting the boom.

[0008] Furthermore, in case of a floating vessel, the effect of a reduction in load supported by the crane may cause the ballast of the vessel to tilt the vessel, and thus the crane, into a slanted position. This moves the boom of the crane upwards relative to the horizontal, even in addition to the lift already caused by the release of the bending and stretching forces in the crane.

[0009] The loss of load supported by a crane, may, due to release of tension and bending forces in the crane and / or by the ballast of the vessel no longer being balanced by the load, cause the boom of the crane to collide with the crane structure and / or with parts of the vessel, causing damage to the crane, the vessel and the boom of the crane in particular.

[0010] When the boom is in a raised position, the loss of load may cause the boom to pivot into, or beyond, a vertical upright position. Once the boom has pivoted beyond the vertically upright position, it can no longer be supported by the luffing system. The boom will therefore collide with the crane structure and / or the vessel. In is furthermore noted that, when the boom is positioned close to the upright position, the weight of the luffing wires may pull the boom into, or beyond the vertically upright position. Furthermore, when the boom is in an upright, or in a near upright position, gravity no longer effectively pulls the boom in a downward direction. Thus, the boom may get stuck in this position.

[0011] Furthermore, in particular in case of a sudden loss of load, or a sudden movement of a vessel caused e.g. by a freak wave, the dynamic movement of the boom may cause slack in the wires of the luffing system and / or the hoisting system, and may even cause these wires to run off their sheaves.

[0012] Prior art heavy lift cranes with auxiliary devices for counteracting undue upwards acceleration of the raised boom in case of sudden load loss or vessel movements are disclosed in W02022002963 by the applicant and in W02022037960. These cranes are of the type comprising a base structure, a crane structure, supported by the base structure such as to be slewable about a vertical slew axis relative to the base structure. The boom typically has a length of 80 - 200 meters. The boom typically has a pivot end, a mid-section, and a hoisting end opposite the pivot end. The boom is supported, in particular at the pivot end, by the crane structure such as to be pivotal relative thereto about a horizontal boom pivot axis. The crane structure extends with an upper part thereof to above the boom pivot axis. The cranes comprise a boom luffing assembly, comprising a boom luffing winch and a boom luffing wire extending from the boom luffing winch to the boom - in particular to the hoisting end thereof, for upward and downward pivoting of the boom about the boom pivot axis and for supporting the boom in a hoisting position relative to the crane structure. The luffing assembly is configured for upward pivoting of the boom in, i.e. into and within, a range of upright orientations of the boom, in which it is typically at an angle with the vertical rotation axis of between 0 and 30°. As explained before, the crane is in heavy lift operations typically employed with the boom in these upright orientations, with the mentioned risk of the boom to tip over. The cranes comprise a hoisting assembly for hoisting a load, comprising a hoisting winch, a departure sheave on the boom, in particular at the hoisting end of the boom, and a hoisting wire extending from the hoisting winch via the departure sheave to a load suspension device.

[0013] The auxiliary devices for counteracting undue upwards acceleration of the raised boom act in these prior art cranes between the crane structure and the boom, in particular between interconnected respective rigid elements provided halfway the length thereof in the form of pipes and beams, respectively protruding from the crane and boom in a direction towards the boom and the crane structure, and moveable along one another to increase or decrease an overlap therebetween. In both cases, the auxiliary device can be switched from a mode in which it enables upwards boom movement to a mode in which it slows down, preferably stops, the undue upwards accelerated movement of the boom, upon detection thereof. In W02022002963, the device comprises a hydraulic cylinder and a gas buffer, which is activatable to dampen the upward movement of the boom. The hydraulic cylinder and gas buffer thereto have a large capacity to enable quick release of the corresponding energy and provide the large force required to counter the acceleration in an adequate reaction time. In W02022037960, a motor of the device drives a movement between the protruding rigid beams in normal operation via a rack and pinion system, and upon detection of an undue upwards acceleration of the boom employ powerful blocking means in the form of e.g. a brake acting on the pinion.

[0014] The present invention aims to provide an improved crane e.g. for use on an offshore vessel, or at least an alternative for existing heavy lift cranes e.g. for such use.

[0015] The present inventors have realized that a drawback of the prior art devices arises from the large power needed to actively counteract the boom acceleration. In W02022002963, a high- capacity gas buffer and the hydraulic cylinder is provided vertically halfway the crane, which is awkward given the considerate height thereof. Providing the capacity, e.g. also the hydraulic power at the crane foot instead, would be even more advantageous as it would require excessive tubing towards the required height, furthermore compromising the reaction time. Engaging the boom lower, would involve an even larger required counterforce and thus, required capacity, and furthermore an increased risk of buckling of the boom where this even larger force engages it. In W02022037960, the large required countering power engages at the drive, in particular the pinion, which inevitably involves engagement of moving and vulnerable parts - such as the pinion - which may damage as a consequence of these sudden and large mechanical loads acting thereon.

[0016] The present invention is based on the first insight that these drawbacks may be reduced or prevented when the counteracting of the boom acceleration is done passively, by passive countering means, instead of actively as in the prior art, and the enabling of the upwards movement of the boom during normal operation is done actively, by active clearance means which actively counteract the passive countering means during this normal operation. The switching to the active mode may then be achieved by stopping the action of the active clearance means. The invention is furthermore based on the second insight that the required power of the active clearance means may be significantly reduced relative to the power of the prior art active countering means, since the therein required fast response time of these active means is a proportional factor in the required active power. In contrast to such active counteracting of the boom acceleration, maintaining the passive means of the invention to the mode in which these enable normal operation, does not involve such response time requirements. The reduction of power required for the auxiliary device, would reduce or eliminate the drawbacks encountered in the prior art: less power would have to be provided on the crane itself at a large height, and the load on vulnerable (moving) parts of the devices may be reduced. The present invention provides a crane according to claim 1. This crane is in particular envisaged being embodied as a heavy lift crane.

[0017] The crane comprises a boom restrainer which is mounted on the upper part of the crane structure above the boom pivot axis and operative between the upper part of the crane structure and the boom for restraining upward pivoting of the boom in said range of upright orientations thereof. The upper part of the crane structure may in particular be a stay of the luffing assembly of the crane, e.g. further including a luffing frame which extends behind the stay to a similar height above the boom pivot axis. It is envisaged that the said height is at least 5 - 10% of the height of the boom when the boom is in said range of upright positions.

[0018] The boom restrainer comprises firstly a rigid intermediate element extending between the boom and the upper part of the crane structure above the boom pivot axis, and guided relative to the crane structure such as to be movable along with the upwards pivoting of the boom to follow said angle thereof within said range, e.g. the rigid element being connected or connectable with the boom at least in the range of upright orientations, or e.g. the rigid element being integral therewith. Examples are a pipe or beam extending from the boom towards the upper part of the crane structure.

[0019] The boom restrainer comprises secondly the passive countering means, which includes one or more engaging elements which are configured to be brought and maintained in a state of stored energy. In this state the engaging elements provide clearance for movement of the intermediate element, and thereby of the boom, within said range. The engaging elements, upon a release, e.g. quick release, of said state, use said stored energy to engage, within said range, the intermediate element and thereby counteract, preferably block, said upward pivoting thereof within said range to slow down, preferably stop, the boom. In embodiments, the engaging means store elastic energy, for example in the form of a compression of a set of springs. These springs may be mechanical springs such as a spiral spring, but elements which function as a spring based on other principles, e.g. a gas spring, are also envisaged. Another envisaged form of stored energy is e.g. (electro) magnetic energy. Other examples may be thought of by the skilled person.

[0020] The boom restrainer comprises secondly active clearance means, which includes one or more actuators which are configured and arranged for, e.g. controllably, maintaining said engaging elements of the passive countering means in said state of stored energy. Furthermore, the actuators are configured and arranged to allow for, e.g. establish, said release, e.g. quick release, from this state. For example, the actuators are one or more hydraulic cylinders which can be activated to provide a force onto the engaging elements of the passive countering means, e.g. one or more springs, in the line(s) of force thereof opposite to the direction of their engagement of the intermediate element.

[0021] A trigger system of the boom restrainer comprises detection means for detecting an anomalous situation causing or potentially causing undue accelerated upward pivoting of the boom. For example such situation involving an upward pivoting of the boom into or within said range of upright orientations thereof at an acceleration which exceeds a predetermined threshold value. The detection means may register the upwards acceleration of the boom itself. However, in view of the required high reaction speed, it is preferred that the detection means register a possible cause thereof which would inevitably lead to the undue accelerated upward boom pivoting, e.g. monitoring the loss of the load, a (high) downward acceleration of the load, and / or a roll and / or or pitch of the vessel exceeding a predetermined reference value. Such detection means are known from the prior art, e.g. being in the form of optical sensors, and / or e.g. sensors monitoring tension in the hoisting wire and / or in the luffing wire, and / or e.g. one or more sensors to monitor roll or pitch of the vessel, when the crane is provided thereon. The trigger system is configured initiate said release, e.g. quick release, by the active clearance means upon detection of said anomalous situation, and preferably to not initiate said release, e.g. quick release, maintaining the passive countering means in the state of stored energy, when said anomalous situation is not detected by the detection means. In an embodiment said initiation is established by a power switch, e.g. an electronic circuit establishing a power loss for the active clearance means to instantly stop these from maintaining the state of stored energy. In an embodiment said initiation is established by a control unit programmed to operate the active clearance means accordingly.

[0022] In embodiments the actuators of the active clearance means are one or more hydraulic cylinders which are configured and arranged to exert a force onto the engaging elements of the passive countering means which opposes the force exerted thereby in the state of stored energy, for maintaining the engaging elements in the state of stored energy thereof. For example the hydraulic cylinders are arranged to be with the piston in the retracted position in the state of stored energy of the passive countering means, so that the maintenance of the state of stored energy involves a pushing force exerted thereby on the engaging elements, and the release into the engagement with the first intermediate element involves a release of the hydraulic fluid from the chamber to move the piston to an extended position. For example the piston is arranged against the engaging elements. In embodiments the stored energy is elastic potential energy, and the actuators of the active clearance means are arranged and configured to act in the line of force thereof to maintain the engaging elements in the state of stored elastic potential energy. The engaging elements of the passive countering means may for example comprise one or multiple springs, e.g. acting on the engaging elements in a direction towards the upper part of crane structure, so as to cause or to increase an initial frictional engagement with the first rigid intermediate element. The actuators, e.g. one or multiple cylinders, may be configured and arranged for maintaining a tensioned, e.g. compressed, state of the springs. For example one cylinder is configured and arranged to counteract the action of an assigned respective one of the springs. It is particularly envisaged that the actuators maintain the springs at least partly compressed for storing the elastic energy of its deformation in the state of stored energy, and the springs are enabled to extend towards its neutral state upon release towards the engagement with the first intermediate element by operating a valve of the cylinders. It is particularly envisaged that the cylinders are in an extended state for maintaining the state of stored energy, thus pressing against the springs to keep them compressed, so that the (quick) release from said state may be achieved by initiating release of the hydraulic fluid from the fluid chamber of the cylinders.

[0023] In embodiments the passive countering means comprise distinct engaging members dedicated to move towards and engage the first intermediate element upon release from the state of stored energy, and distinct energy storage members dedicated to effectuate said movement of the engaging members. In such embodiments the distinct energy storage members of the passive countering means and active clearance means may for example each act in opposed directions on the engaging members. The functions of engaging and energy storing being performed by dedicated separate parts enables an effective design wherein each of the parts is optimized for its dedicated purpose.

[0024] In one such embodiment the boom restrainer functions as a wedge socket for the first intermediate element. The passive countering means comprise therein as the distinct engaging members one or more wedge members which are arranged such, that the stored energy when released acts thereon with the line of force thereof in the line of movement of the wedge members. These wedge members are arranged for being, upon the (quick) release of the actuators of the active clearance means, movable slantedly to a longitudinal axis of the first rigid intermediate element towards frictional engagement with the first rigid intermediate element, a wedge surface thereof therein being movable along a guiding surface e.g. that is slanted towards the first intermediate element when seen in the longitudinal direction of the first rigid intermediate element towards the upper part of the crane structure. The one or more wedge members are configured to by said frictional engagement provide frictional braking, preferably stopping or holding, of the elongated rigid intermediate element. In this embodiment it is envisaged that the trigger system causes by the (quick) release a movement of the wedge members such as to establish the engagement of the first intermediate element by the wedge members, so that (further) movement of the engaged first rigid intermediate element towards the crane structure also involves a further movement of the wedge members towards a longitudinal axis of the first intermediate element, resulting in a tighter engagement and increasingly larger friction thereof, e.g. until the wedge members are locked in between the guiding surface and the intermediate element so that the intermediate element pulled itself stuck against the wedge members.

[0025] In this embodiment the distinct energy storage members of the passive countering means and active clearance means may for example each act in opposed directions on respective longitudinal ends of the wedge members, considering the longitudinal direction of the first intermediate element from the boom towards the upper part of the crane structure. For example springs acting on respective boom-facing ends of the wedge-members and hydraulic cylinders acting on opposed respective ends facing the upper part of the crane structure. The distinct energy storage members of the passive countering means, active clearance means, and wedge members which engage the first intermediate element being arranged in series considering the line of movement makes for a particularly effective and elegant solution wherein the lines of force of the passive and active means may be effectively aligned for favorable mechanical loading, efficient energy transfer, and reduction of required number of parts.

[0026] In preferred embodiments the first intermediate element is an elongate first rigid intermediate element, e.g. a pipe, e.g. a cylindrical pipe, or a beam. The elongate first rigid intermediate element is therein with one end thereof engageable with, e.g. connectable or connected with, the boom at least in said range of upright orientations thereof and longitudinally directed from the boom with this same end towards the upper part of the crane structure with an opposite end. This enables to slow down or stop the undue acceleration of the boom by engaging the intermediate element at distances from the boom which depend on its angle with the vertical slew axis while the circumference is the same or substantially the same, preferably constant along at least a relevant part of its length, facilitating the engagement at these different angles as it can be performed in a similar or preferably the same way - in particular involving a similar or the same movement of the engaging elements. A pipe, in particular a cylindrical pipe, is particularly preferred given its favorable moment of inertia of its cross-section relative to the amount of material - and thus weight thereof, while it can be engaged by engaging members distributed around the circumference all in the same manner, and having a large contact area for frictional braking.

[0027] In an example of such embodiments, the elongate first rigid element is rigidly connected to the boom or integral therewith and extends substantially perpendicularly to the boom. In another example the elongate first rigid element is pivotally connected to the boom and extends at an angle with the boom that increases with the upwards pivoting of the boom in said range of upright positions thereof. The connection with the boom is preferably releasable at least outside the range of upright positions. The engaging elements preferably are provided such as engage the elongate first rigid intermediate element at multiple locations distributed around its circumference, e.g. to reduce the load per engaging element when engaging the elongate first rigid intermediate element and increase the contact surface for the benefit of a braking friction force. In embodiments the boom restrainer comprises a boom connector comprising a first connector part secured to or integral with the first rigid intermediate element and a second connector part secured to or integral with the boom for receiving the first connector part in a direction opposite to the direction of said pivoting of the boom when the boom is within said range, for connection of said first rigid intermediate element with the boom.

[0028] The boom restrainer may further comprise an actuator, e.g. a motor and chain, rack and pinion, or winch system for driving a movement of the first rigid intermediate element relative to the crane structure to have the first connector part follow the movement of the second connector part resulting from the pivoting movement of the boom. In an envisaged use, during upward pivoting of the boom into and within the said range of upright positions the action of the luffing assembly pulls the second connector part against the first connector part, which thereby pushes the first intermediate element in the direction towards the crane structure to retract the first intermediate element further in this direction as the upward pivoting continues, and the driving of the relative movement between the first intermediate element and the crane structure is to be applied for following the downward pivoting of the boom. In other uses the first intermediate element may also be actively driven during the upward pivoting into and within the said range, e.g. keeping the connector parts at a small spacing from one another. In an embodiment the boom restrainer further comprises a linear motion drive configured to provide linear motion of the first rigid intermediate element relative to the crane structure, e.g. relative to the second intermediate element when present, to have the outer end follow a pivoting movement of the boom controlled by the luffing assembly. The passive countering means and the active clearance means may be connected to the upper part of the crane structure via a second rigid intermediate element, e.g. an elongate second rigid intermediate element, e.g. a pipe or beam, which is with one end thereof connected to, or integral with, the upper part of the crane structure above the boom pivot axis and longitudinally directed from the upper part of the crane structure towards the boom, e.g. extending perpendicularly to the slew axis. Preferably the first rigid intermediate element is longitudinally guided along the second rigid intermediate element through guiding means interconnecting both rigid elements, for example the first rigid intermediate element longitudinally sliding along the second rigid intermediate element between retracted and extended positions.

[0029] In embodiments at least the first rigid intermediate element, the passive countering means, and the active clearance means are provided at or near a top end of the upper part of the crane structure, e.g. at a height above the boom pivot axis of between 20-280% of the boom height, e.g. around 25-40%, when the boom is in said range of upright orientations. It is in particular envisaged that the entire boom restrainer is provided in said range of the boom height, e.g. except for the control system.

[0030] In embodiments, the actuators of the active clearance means of the boom restrainer are configured to once the engaging elements have been brought into the state of stored energy, assume a locking state in which they maintain the engaging elements in the state of stored energy substantially without requiring energy. In case of hydraulic cylinders this may be achieved by having the cylinders and engaging elements reach an equilibrium wherein the force caused by an over- or underpressure in the cylinders and exerted thereby on the engaging elements is equal and oppositely directed to the force exerted by the engaging elements on the cylinders. Maintaining the locking state of the cylinders then involves maintaining the over- or underpressure in the cylinders, which may come down to maintaining the fluid inside the chamber, i.e. keeping one or more valves of hydraulic fluid lines closed. The release from the state of stored energy may then be effectuated by opening these valves so as to trigger said movement of the engaging members into engagement of the first rigid intermediate element. For example the control system controls these valves correspondingly. Also in this embodiment it is favorable that the required power is limited to the maintenance of the energy storing members in the energy storing state, so that the hydraulic cylinders can remain of limited capacity to facilitate fast release of fluid - and thus a short response time. This may be further facilitated by providing more cylinders of less capacity. This is in particular facilitated by embodiments wherein these may be arranged distributed around the circumference of the first intermediate element, preferably being elongate, most preferably having a constant circumference along its length.

[0031] In embodiments, the boom restrainer provides a collapsed mode in which it is free from the boom and is folded along the upper part of the crane structure, with the first rigid element in a retracted position. In an example wherein the second rigid intermediate element is provided, the second rigid intermediate element is pivotable relative to the crane structure around a horizontal axis to move the boom restrainer into said collapsed position.

[0032] In an embodiment, the boom restrainer functions as a boom stop when the boom is pivoted upwards to reach an angle of between 3 and 5° with the vertical slew axis, e.g. 4°. For example the boom restrainer thereto comprises an end stop for the movement of the first intermediate element towards the crane structure when upwards pivoting the boom, corresponding to the boom position at this angle.

[0033] In embodiments, the crane is suitable for use on a vessel, the base structure of the crane being adapted to be mounted to, or formed integral with, the vessel. For example the vessel is therein a floating vessel and the crane further comprises a motion compensation system to compensate for motion of the vessel induced by sea state motions, e.g. waves and currents, and wind. In other examples the vessel is a semisubmersible, or a jack-up vessel, e.g. the crane therein also being provided with said motion compensation system for usability of the jack-up vessel also in floating state. The invention furthermore relates to a vessel, e.g. a floating vessel, a jack-up vessel, a semisubmersible, etc., comprising the heavy lift crane according to the invention, the base structure of the crane being mounted to, or formed integral with, the vessel, the crane e.g. being provided with said motion compensation system. For example the vessel is also equipped for storage and transport of one or more piles to be installed by means of the crane.

[0034] The invention furthermore relates to a pile installation method in which use is made of the crane according to the invention, or a vessel according to the invention.

[0035] The pile installation method comprises: suspending a pile, e.g. a monopile, from the load suspension device, displacing the pile towards an installation location by operating the hoist winches of the crane, and / or by operating the luffing winches of the crane to pivot the boom about its boom pivot axis, and / or by slewing the boom around the vertical slew axis, wherein during at least said displacing of the pile, the boom restrainer is operated by the control system thereof to detect by the detection means an anomalous situation involving an upward pivoting of the boom within said range of upright orientations thereof at an acceleration which exceeds a predetermined threshold value, and to control the operation of the active clearance means such as to initiate said quick release upon detection of said anomalous situation, and to maintain these in the state of stored energy when said anomalous situation is not detected.

[0036] The method may in particular be performed on the vessel according to the invention, e.g. therein performing motion compensation to compensate for sea state and / or wind induced motions of the vessel.

[0037] The invention furthermore relates to a crane comprising: a base structure; a crane structure, supported by the base structure such as to be slewable about a vertical slew axis relative to the base structure; and a boom, preferably having a length of 80 - 200 meters, e.g. having a pivot end, a midsection, and a hoisting end opposite the pivot end, wherein the boom is supported, in particular at the pivot end, by the crane structure such as to be pivotal relative thereto about a horizontal boom pivot axis.

[0038] The crane structure extends with an upper part thereof to a height above the boom pivot axis. The crane further comprises: a boom luffing assembly, comprising a boom luffing winch and a boom luffing wire extending from the boom luffing winch to the boom, e.g. the hoisting end thereof, for upward and downward pivoting of the boom about the boom pivot axis and for supporting the boom in a hoisting position relative to the crane structure, the luffing assembly being configured for upward pivoting of the boom into and within a range of upright orientations of the boom, e.g. in which it is at an angle with the vertical rotation axis of between 0 and 30°; and a hoisting assembly for hoisting a load, comprising a hoisting winch, a departure sheave, e.g. at the hoisting end of the boom and a hoisting wire extending from the hoisting winch via the departure sheave to a load suspension device.

[0039] The crane further comprising a boom restrainer operative between the upper part of the crane structure and the boom for restraining upward pivoting of the boom in said range of upright orientations thereof, the boom restrainer comprising: a first rigid intermediate element extending between the boom and the upper part of the crane structure above the boom pivot axis and guided relative to the upper part of the crane structure such as to be movable along with the upward pivoting of the boom to follow said angle thereof within said range, e.g. the element being connected or connectable with the boom as described herein, countering means, comprising one or more friction members which are movable into, and can be maintained in, a clearance position to provide clearance for movement of the first rigid intermediate element, and thereby of the boom into and within said range, wherein the friction elements are movable along a defined movement trajectory from this clearance position towards a braking position in engagement of the rigid intermediate element, wherein the movement trajectory is such that movement, e.g. further movement, of the engaged first rigid intermediate element towards the crane structure involves a further movement of the friction elements towards a longitudinal axis of the first intermediate element, resulting in a tighter engagement and increasingly larger friction thereof, the friction elements thereby counteracting, preferably blocking, said upward pivoting of the boom within said range to slow down, preferably stop, the boom, driving means, comprising one or more actuators, configured and arranged for at least moving said friction elements of the countering means from the clearance position thereof into said braking position, a trigger system comprising detection means for detecting an anomalous situation involving an upward pivoting of the boom within said range of upright orientations thereof at an acceleration which exceeds a predetermined threshold value, and configured to initiate said driven movement into said braking position upon detection of said anomalous situation, and to not initiate said movement, maintaining the countering means in the clearance position thereof, when said anomalous situation is not detected.

[0040] With this crane, the counteracting of the boom acceleration is as in the precedingly described crane done passively, by the friction elements of the countering means tightening their grip as a consequence of the undue movement of the boom, instead of actively as in the prior art. The required power may be significantly reduced relative to the power of the prior art active countering means. The reduction of power required for the auxiliary device, would reduce or eliminate the drawbacks encountered in the prior art: less power would have to be provided on the crane itself at a large height, and the load on vulnerable (moving) parts of the devices may be reduced. In embodiments, the actuators of the driving means may comprise e.g. (electro)magnetic actuators, and / or e.g. one or more hydraulic cylinders, e.g. combined with one or more springs, e.g. as described herein before.

[0041] In embodiments, the friction members are in the form of one or more wedge members as described before, movable with a slanted wedge surface thereof along a guiding surface slanted towards the longitudinal axis of the intermediate element in the longitudinal direction of the first intermediate element towards the upper part of the crane structure, so as to be movable slantedly to the longitudinal axis of the first intermediate element towards engagement thereof, and towards a tighter engagement thereof by said longitudinal movement of the first intermediate element. Examples are easily envisaged by the skilled person from the relevant embodiments described herein before.

[0042] In embodiments, the crane is suitable for use on a vessel, the base structure of the crane being adapted to be mounted to, or formed integral with, the vessel. For example the vessel is therein a floating vessel and the crane further comprises a motion compensation system to compensate for motion of the vessel induced by sea state motions, e.g. waves and currents, and wind. In other examples the vessel is a semisubmersible, or a jack-up vessel, e.g. the crane therein also being provided with said motion compensation system for usability of the jack-up vessel also in floating state. The invention furthermore relates to a vessel, e.g. a floating vessel, a jack-up vessel, a semisubmersible, etc., comprising the heavy lift crane according to the invention, the base structure of the crane being mounted to, or formed integral with, the vessel, the crane e.g. being provided with said motion compensation system. For example the vessel is also equipped for storage and transport of one or more piles to be installed by means of the crane.

[0043] The crane may be embodied according to one or more of the embodiments described herein before for the previously discussed crane.

[0044] The present invention also relates to a crane according to claim 14. Herein a boom restrainer is mounted on the upper part of the crane structure and operative between the upper part of the crane structure and the boom for restraining undue accelerated upward pivoting of the boom, e.g. in case of loss of load. The boom restrainer comprises:

[0045] - an elongated rigid intermediate element extending between the boom and the upper part of the crane structure and longitudinally guided by guiding means of the boom restrainer such as to be movable with the boom as it pivots upward, the elongated rigid intermediate element having an outer end being connected or connectable with the boom, - one or more wedge members configured for frictional engagement with the rigid intermediate element, each wedge member being movable with a wedge surface thereof along a guiding surface which is slanted towards the rigid intermediate element when seen in the longitudinal direction of the rigid intermediate element towards the upper part of the crane structure, the one or more wedge members configured to provide frictional braking, preferably holding / stopping, of the elongated rigid intermediate element to prevent occurrence of undue accelerated upward pivoting of the boom.

[0046] Preferably, the elongated rigid intermediate element is a pipe, e.g. a cylindrical pipe.

[0047] Preferably, wedge members are provided at multiple locations distributed around the circumference of the elongated rigid intermediate element, e.g. the pipe.

[0048] In embodiments, the boom restrainer further comprise a linear motion drive configured to move the rigid intermediate element in its longitudinal direction relative to the crane structure in order to have the outer end follow a pivoting movement of the boom when controlled by the boom luffing assembly, e.g. within a range of upright boom position. For example, the linear motion drive is configured to keep the outer end pressed against the boom within said range of upright boom positions. Preferably, the outer end of the rigid intermediate element is releasably connected to the boom, which releasable connection is to be disconnected when the boom is outside of the range of upright positions.

[0049] In embodiments, the boom restrainer further comprises one or more springs acting on the one or more wedge members in a direction towards the upper part of crane structure, so as to cause or increase initial friction engagement with the elongated rigid intermediate element. For example, the wedge member(s) may be continuously in a limited frictional contact with the rigid intermediate element, e.g. allowing for a slow, controlled back and fro movement of the intermediate element as the boom is slowly pivoted under control of the luffing assembly and such that upon a sudden acceleration due to loss of load or the like the wedge(s) is / are tightened and brake / stop the intermediate element and thereby the boom.

[0050] In a preferred embodiment, the one or more wedges are normally held clear from the elongated rigid intermediate element and are brought into frictional engagement only when needed / desired to provide frictional braking, preferably stopping or holding, of the elongated rigid intermediate element and thereby braking or avoiding undue upward pivoting of the boom. For example, the boom restrainer further has active clearance means which comprise one or more actuators which are configured and arranged for maintaining the one or more wedge members cleared from the elongated rigid intermediate element, e.g. with the one or more springs discussed above in a state of stored energy. The one or more actuators of the active clearance means are configured to allow for a release, preferably a quick release, of the wedge members so as to frictionally engage the elongated rigid intermediate element.

[0051] For example, the actuators of the active clearance means comprise a hydraulic cylinder, e.g. arranged to exert a force on the wedge member opposite to the force of the one or more springs. For example, a spring acts on a respective boom-facing end of the wedge-member and a hydraulic cylinder acts on opposed respective end facing the upper part of the crane structure.

[0052] In an embodiment, the boom restrainer further has a trigger system comprising detection means for detecting an anomalous situation causing or potentially causing undue accelerated upward pivoting of the boom and configured to initiate said quick release by the active clearance means upon detection of said anomalous situation.

[0053] In an embodiment, the boom restrainer allows for a crane operator to initiate the release of the one or more wedge members so as to frictionally engage the elongated rigid intermediate element. For example, the crane operator may decide to bring the boom is a desired upright position in the course of a lift operation and keep the boom in said position for a while, e.g. when slewing a load into an overboard position. The operator then may choose to initiate the release of the one or more wedge members. If during the lift operation a loss of load or the like would occur, the intermediate rigid element would be held immediately by the engaged wedge members and undue upward pivoting of the boom would effectively be restrained immediately.

[0054] In an embodiment, when the boom is within a range of upright positions, a stopping of the luffing assembly could be detected, e.g. as the one or more luffing winches are stopped, and a controller of the boom restrainer could then automatically initiate the release of the one or more wedge members so as to frictionally engage the elongated rigid intermediate element. If the luffing means are then operated again, the same could be detected and automatically initiate the operation of active clearance means, such that the wedge members are disengaged, e.g. the associated springs being compressed, e.g. allowing the intermediate rigid member to follow the luffing motion of the boom. In an embodiment, the outer end of the elongated rigid intermediate element is provided with a first connector part and the boom is provided with a second connector part, said connector parts being configured to provide for a releasable connection between the outer end and the boom, e.g. when the boom is outside of a range of upright positions of the boom.

[0055] In embodiments, the crane is suitable for use on a vessel, the base structure of the crane being adapted to be mounted to, or formed integral with, the vessel. For example the vessel is a floating vessel and the crane further comprises a motion compensation system to compensate for motion of the vessel induced by sea state motions, e.g. waves and currents, and wind. In other examples the vessel is a semisubmersible, or a jack-up vessel, e.g. the crane therein also being provided with said motion compensation system for usability of the jack-up vessel also in floating state.

[0056] The invention furthermore relates to a vessel, e.g. a floating vessel, a jack-up vessel, a semisubmersible, etc., comprising the heavy lift crane according to the invention, the base structure of the crane being mounted to, or formed integral with, the vessel, the crane e.g. being provided with said motion compensation system. For example the vessel is also equipped for storage and transport of one or more piles to be installed by means of the crane.

[0057] The crane may be embodied according to one or more of the embodiments described herein before for the previously discussed cranes.

[0058] The invention furthermore relates to a pile installation method in which use is made of either of the cranes, or vessels, as described above.

[0059] The pile installation method comprises: suspending a pile, e.g. a monopile, from the load suspension device, displacing the pile towards an installation location by operating the hoist winches of the crane, and / or by operating the luffing winches of the crane to pivot the boom about its boom pivot axis, and / or by slewing the boom around the vertical slew axis, wherein during at least said displacing of the pile, the boom restrainer is operated by the control system thereof to detect by the detection means an anomalous situation involving an upward pivoting of the boom within said range of upright orientations thereof at an acceleration which exceeds a predetermined threshold value, and to control the operation of the driving means such as to initiate said movement towards the braking position thereof upon detection of said anomalous situation, and e.g. to maintain these in the clearance position when said anomalous situation is not detected. The method may in particular be performed on the vessel according to the invention, e.g. therein performing motion compensation to compensate for sea state and / or wind induced motions of the vessel.

[0060] It is noted that also for this crane, vessel and method, features described in relation to the crane according to any of the claims may be applied to obtain similar effects and advantages.

[0061] Hereinafter the invention will be described in a non-limiting way with reference to the appended drawings. In the drawings: figure 1 shows an embodiment of a crane according to the invention, figure 2 shows a part of the crane with the boom and crane structure in different positions, figures 3a-e shows a part of the crane with increasing boom angles in a range of upright orientations, figure 4a, b show in a vertical longitudinal cross-section a part of the boom restrainer of the crane, along with a part of the boom, figure 5 shows in a horizontal longitudinal cross-section a part of the boom restrainer of the crane, figures 6a, b shows in a longitudinal vertical cross section a part of the boom restrainer of the crane, in two different states, figure 7 shows a top view on a part of the boom restrainer, and figure 8 shows a part of the boom restrainer in a transversal cross-section,

[0062] The figures illustrate a crane 100 according to the invention. In figure 1 , and also in figures 3a-e, and 4a, b, the crane 100 is shown in an upright position.

[0063] Figures 1 and 2 illustrate that the crane comprises a base structure 103, a crane structure 104, supported by the base structure 103 such as to be slewable about a vertical slew axis 104x relative to the base structure by means of slew bearing 104b, and a boom 105. The crane structure 104 comprises a luffing stay 104s and a luffing frame 104f which form an upper part of the crane structure 104 extending vertically to above the boom pivot axis 104x. Indicated in figure 1 is that the boom has a pivot end 105a, a mid-section 105b, a hoisting end 105c opposite the pivot end 105a, and a longitudinal axis 1051. The boom 105 is supported at the pivot end by the crane structure 104 such as to be pivotal relative thereto about a horizontal boom pivot axis 105x, see figures 1 and 2. In figure 2, the crane 100 is partly shown with the boom 105 pivoted around the axis 105x in two upright positions, at angles 0=01, and 0—05 with the horizontal of 70° and 86° respectively, and with the boom 105 and luffing stay 104s of the crane structure 104 pivoted downwards in a storage and transport position, wherein the boom 105 is horizontal and supported onto a boom rest, for use e.g. during transportation over sea when the crane 100 is provided on a vessel.

[0064] A boom luffing assembly of the crane 100 comprises a boom luffing winch and a boom luffing wire 106 extending from the boom luffing winch to the hoisting end 105c for upward and downward pivoting of the boom 105 about the boom pivot axis 105x and for supporting the boom in a hoisting position relative to the crane structure 104. The luffing assembly is configured for upward pivoting of the boom 105 into and within a range of upright orientations of the boom 105 in which it is at an angle with the vertical rotation axis 104x of between 0 and 30°. That is, an angle 0 with the horizontal of between 70 and 90°. In this range typically heavy and large loads such as monopiles are lifted.

[0065] Figures 3a-e show an inner section of the boom 105 along with the stay 104s, with the boom 105 being pivoted to different upright orientations within the said range of upright orientations at angles of respectively 0=0i=7O° in figure 3a, 0=02=75° in figure 3b, O=©3=80° in figure 3c, O=©4=85° in figure 3d, and O=©5=86° in figure 3e.

[0066] The boom 105 of the illustrated crane 100 is pivotable to an angle Os of at most 86° for safety reasons, being stopped by boom stop 153 upon reaching this angle.

[0067] A hoisting assembly of the crane 100 for hoisting a load, comprises a hoisting winch, a departure sheave 108 at the hoisting end 105c of the boom 105 and a hoisting wire 107 extending from the hoisting winch via the departure sheave 108 to a load suspension device 109.

[0068] The crane 100 further comprises a boom restrainer 120 operative between the crane structure 104, in particular the stay 104s thereof, and the boom 105 for restraining upward pivoting of the boom 105 in said range of upright orientations thereof. See figures 1 , 2 and 3a- e for its arrangement and positions in the crane 100, and figures 4-8 for a more detailed view on its parts.

[0069] Referring firstly to figures 3a-e, the boom restrainer 120 comprises firstly a first rigid intermediate element, in the form of a pipe 121 , extending between the boom 105 and the stay 104s. It is guided relative to the stay 104s such as to be movable along with the upward pivoting of the boom 105 to follow said angle O thereof within said range, the pipe 121 being connectable with the boom 105 within said range. Now referring to figures 4a-8, the boom restrainer 120 further comprises passive countering means 130, comprising one or more engaging elements in the form of multiple springs 131 and respective wedge shaped members 132 which can be brought and maintained in a state of stored energy. The stored energy is elastic potential energy in the springs 131. The wedge members 132 are arranged such that the stored elastic potential energy of each of the springs 131 acts with the line of force 1311 - see figures 6a and 6b - thereof in the line of movement of the wedge members 132. The wedge members 132 are arranged for being movable slantedly to a longitudinal axis 121x of the pipe 121 towards engagement therewith. In the shown embodiment the line of force 1311 of the springs 131 is at an angle y of around 10° with the longitudinal pipe axis 121x. A wedge surface 132s moves along a guiding surface 133s that is slanted towards the pipe 121 when seen in the longitudinal direction of the pipe 121 towards the stay 104s. The wedge members 132 are provided at multiple locations distributed around the circumference of the pipe 121 to engage the pipe 121.

[0070] In the state of stored energy, shown in figure 6a, the engaging elements 131 ,132 provide clearance for movement of the pipe 121 , and thereby of the boom 105, into and within said range. The wedge members are arranged at some spacing to the pipe circumference, and the springs 131 are in a compressed state to provide the state of stored elastic potential energy.

[0071] Upon quick release of said state, the engaging elements 131 ,132 are moved to the position of figure 6b. To establish this movement at least part of said stored elastic potential energy is used to engage, within said range, the pipe 121 at its circumference. It can be verified in figure 6b that the wedge member 132 has moved with its wedge surface 132s along the guiding surface 133s into engagement with the pipe 121. There is correspondingly, no spacing visible anymore between the wedge 132 and the pipe 121. The spring 131 is extended relative to the situation in figure 6b. Furthermore, as can be envisaged since the movement to said state is accompanied by the pipe 121 moving rapidly towards the stay 104s, the engaging members together function as a wedge socket for the pipe 121 , inside which the pipe 121 pulls itself stuck upon the engagement. By the engagement, the engaging elements 131 , 132 counteract, in particular block, the upward pivoting of the boom 105 within said range to slow down, the boom 105.

[0072] In figures 4 and 5, for illustrative purposes, one of the visible springs and respective wedge members are shown in the state of stored energy and the other one is shown in the countering state. In practice, it is in principle envisaged that multiple, e.g. all, of the wedges assume the same state for effective and efficient functionality. One alternative use of the boom restrainer is envisaged in which only a part, e.g. only one, of the engaging elements 131, 132 is released in a controllable way, i.e., not quickly releasing said state but slowly and controllably moving the part of the wedge member(s) 132 to the countering state thereof, for purposely providing friction thereto in case some additional braking of the upward pivoting movement of the boom 105 is desired.

[0073] Active clearance means 140 of the boom restrainer 120 comprise one or more actuators 141, in this case hydraulic cylinders 141 with respective pistons 141 p, which are configured and arranged for at least maintaining said engaging elements, here springs and wedge members 131,132 of the passive countering means in said state of stored energy, and for establishing said quick release from this state. Thereto in this embodiment, each of the cylinders 141 is arranged in line with a respective wedge member 132 and spring 131, at the opposite side of the wedge member 132 than the spring 131 such as to be able to exert a force against the wedge member 132 opposite to that of the spring 131. Thus, the cylinder 141 counteracts the action of the spring 131 indirectly, via the wedge member 132. The piston 141b is arranged to engage the wedge member 132 and the fluid chamber 141c is secured in place relative to the stay 104s. In the state of stored energy shown in figure 6a, the cylinders 141 are extended. In this way, the cylinders 141 are configured and arranged to exert a force onto the wedge members 132, and therewith, on the springs 131, which opposes the force exerted thereby in the state of stored energy, for maintaining the engaging elements 131,132 in the state of stored energy thereof. In the countering state shown in figure 6b they are retracted - verify the position of the piston 141 p. Thereby the cylinders 141 allow for the wedge members 132 to assume their positions of engagement of the pipe 121. Hydraulic power unit 142 is indicated in figure 4.

[0074] A trigger system, not shown, comprises detection means for detecting an anomalous situation involving an upward pivoting of the boom 105 within said range of upright orientations thereof at an acceleration which exceeds a predetermined threshold value, and is configured to control the operation of the active clearance means 140 such as to initiate said quick release upon detection of said anomalous situation, and to maintain these in the state of stored energy when said anomalous situation is not detected. The quick release involves in this case an opening of the valves (not shown) of the fluid chambers 141c - see figures 6a, b - of the cylinders 141 by the control system, and the maintenance of the state of stored energy (figure 6a) keeping these valves closed to thus maintain the overpressure in the cylinders 141 which pushes the piston 141 p against the wedge members 132 against the pushing action of the springs 131 thereon. The wedge members 132 are accommodated inside a housing 145 which is secured relative to the stay 104s. It can be accessed by loosening of the bolt 145b, e.g. after the wedge socket has closed to prevent a boom tipover, to bring the wedge members 132 and the springs 131 back to their state of stored energy. See figure 6a.

[0075] The passive countering means 130 and the active clearance means 140 are connected to the stay 104s via an elongate second rigid intermediate element in the form of beam 122, which is with one end thereof connected to the stay 104s and longitudinally directed from the stay 104s towards the boom 105, extending substantially perpendicularly to the slew axis 104x. See figure 2, figures 3a-e, and figure 4 for some detail.

[0076] In figures 4a, b it is best visible that the restrainer 120 has a housing 145 in which the pipe 121 is longitudinally guided to slide longitudinally supported along the beam 122 by guiding means 125, here rollers at the axial ends of the housing 145 and engaging on the pipe, interconnecting both elongate rigid elements 121 ,122. The cylinder 125c of the guiding means 125 provides for control of, restraining, the angle of the pipe 121 with the beam 122.

[0077] The pipe 121 is within the said range of upright orientations of the boom 105 with one, outer, end 121 o thereof connected to the boom 105 and longitudinally directed from the boom 105 towards the stay 104s, facing the stay 104s with the opposed end 121 i. As is visible most clearly in figures 4a, b, a first connector part 124a of a boom connector interconnecting said pipe end 121o with the boom 105 is secured to said end of the pipe 121 and a second connector part 124b secured to the boom 105 for receiving the first connector part 104a in a direction opposite to the direction of said upward pivoting of the boom 105 when the boom 105 is within said range, for connection of said pipe with the boom 105. The connector parts are configured such that the connection is both pivotal and releasable: when the boom 105 is pivoted outside said range, the connection is released. The first connector part 124a is a male connector part, and the second connector part 124b a female connector part, so that the connection is easily made by inserting the male part in the female part. In particular the female part is C-shaped when viewed from the side, with the opening directed to the boom restrainer, in particular the male part, and the male part is o-shaped when viewed from the side. The insertion can be established automatically upon pivoting of the boom 105 upward into the range - here at 70° - with the pipe 121 already in the extended position of figure 3a relative to the beam 122. As can be verified from figures 3a-e, the pipe 121 extends at an angle with the boom 105 that slightly increases with the upward pivoting of the boom 105 in said range. This angle change is facilitated by the pivotability provided by the C / o shape of the connector parts 124a,b. The guiding means 125 also allow for, and controllably restrain - in particular by cylinder 125c - the angle at which pipe 121 extends relative to the beam 122, the angle decreasing as upward pivoting of the boom 105 within the said range of upright orientations of the boom 105 continues. This enables that the pipe 121 and the force exerted thereby on the boom 105 to restrain its movement when necessary in case of an undue upward boom acceleration, is directed at a larger angle with the boom 105 which approaches perpendicularity thereto, in particular at larger angles of the boom 105 with the vertical slew axis 104x involving larger angles between the pipe 121 and beam 122.

[0078] As seen best in figure 4, the boom restrainer 120 further comprises a motor 155m for driving via a chain 155c a relative movement of the pipe 121 and beam 122 such as to have the first connector part 124a follow the movement of the connector part 124b resulting from the pivoting movement of the boom 105 under control of the luffing assembly. In an envisaged use, during upward pivoting of the boom 105 into and within the said range of upright positions the action of the luffing assembly pulls the second connector part 124b against the first connector part 124a, which thereby pushes the pipe 121 in the direction towards the beam 122 to retract the pipe 121 further as the upward pivoting continues, and the driving of the relative movement between the pipe 121 and the beam 122 is to be applied for following the downward pivoting of the boom 105. In other uses the pipe 121 may also be actively driven during the upward pivoting into and within the said range, e.g. keeping the connector parts at a small spacing from one another.

[0079] The boom restrainer 120 provides a collapsed mode in which it is disconnected from the boom 105 and extends along the stay 104s. In figure 2 this mode is shown in the storage and transport position of the crane 100, for use e.g. during transportation over sea when the crane 100 is provided on a vessel. Herein the pipe 121 is fully retracted relative to the beam 122, the pipe 121 and boom 122 and interconnecting parts being folded towards the stay 104s to extend there along only at a small angle therewith. To provide this position, the beam 122 of the boom restrainer 120 is provided with a pivotability relative to the stay 104s, and a pivot lock which is switchable between a locking mode in which it keeps the beam 122 fixed relative to the stay 104s at the angle at which it extends towards the boom 105 for providing the boom restraining function, that is, here substantially horizontally, and a clearance mode in which it allows the pivoting of the boom restrainer 120 relative to the stay 104s to the collapsed position thereof. The pivot lock is provided in the shown embodiment by the third intermediate element 123 in the form of a beam forming in the locking mode a link between a boom-facing end of the beam 122 and a connection point with the stay 104s below the pivotal interconnection of the other end of the beam 122 with the stay 104s. The connection with the stay 104s is releasable - see in figure 2 the secured and released state of this connection. As indicated in figure 2 the boom restrainer 120 further comprises sea fastenings 151 for the first and second elongate rigid elements 121 , 122 in the maximally retracted position of the pipe 121. Furthermore the end stops 152a, 152b are provided on the third elongate rigid element 123, to limit the pivoting of the boom restrainer 120 towards the stay 104s to the collapsed position there along, preventing collision therewith, see also figures 4a, b.

[0080] The boom restrainer 120 also serves as an end stop for the upward pivoting of the boom 104. As shown in figures 4a, b, the pipe 121 is fully retracted and the outer end 101o abuts against the housing 145 of the boom restrainer 120. This makes that the boom restrainer 120 functions as a regular boom stop at a near-vertical position of the boom, in this case when the boom has an angle of 4° with the vertical slew axis 104x, i.e. the upright orientation of figure 3e.

[0081] Furthermore, pipe rotation lock 154 prevents rotation of the pipe 121 around a longitudinal axis thereof.

[0082] Figure 8 shows six wedge members 132 in frictional engagement with the rigid intermediate element 121. The wedge members 132 are all arranged inside of the housing 145.

[0083] The figures 1 - 8 also illustrate that the boom restrainer 120 comprises:

[0084] - an elongated rigid intermediate element 121 extending between the boom 105 and the upper part of the crane structure 104s, 104f and longitudinally guided by guiding means 125 of the boom restrainer 120 such as to be movable with the boom 105 as it is pivoted under control of the luffing assembly in a range of upright orientations, the elongated rigid intermediate element 121 having an outer end 121o engaging, e.g. being connected or connectable, with the boom 105 in a range of upright orientations of the boom,

[0085] - one or more wedge members 132 configured for frictional engagement with the rigid intermediate element 121 , each wedge member 132 being movable with a wedge surface 132s thereof along a guiding surface 144s which is slanted towards the rigid intermediate element 121 when seen in the longitudinal direction 121x of the rigid intermediate element towards the upper part of the crane structure 104s, 104f, the one or more wedge members 132 configured to provide frictional braking, preferably holding / stopping, of the elongated rigid intermediate element 121 to prevent occurrence of undue accelerated upward pivoting of the boom.

[0086] The elongated rigid intermediate element is a cylindrical pipe 121. As can be seen in Figure 8 the wedge members 132 are provided at multiple locations distributed around the circumference of the elongated rigid intermediate element 121.

[0087] The boom restrainer 120 further comprise a linear motion drive 155m, 155c configured to move the rigid intermediate element 121 in its longitudinal direction relative to the crane structure in order to have the outer end follow a pivoting movement of the boom when controlled by the boom luffing assembly, in the range of upright positions of the boom.

[0088] The boom restrainer 120 further comprises one or more springs 131 acting on the one or more wedge members 132 in a direction towards the upper part of crane structure 104s, 104f , so as to cause or increase initial friction engagement with the elongated rigid intermediate element 121.

[0089] The one or more wedges 132 are normally held clear from the elongated rigid intermediate element 121 and are brought into frictional engagement only when needed / desired to provide frictional braking, preferably stopping or holding, of the elongated rigid intermediate element 121 and thereby braking or avoiding undue upward pivoting of the boom.

[0090] The boom restrainer 121 further has active clearance means 140 which comprise one or more actuators 141 which are configured and arranged for maintaining the one or more wedge members 132 cleared from the elongated rigid intermediate element 121 , e.g. with the one or more springs discussed above in a state of stored energy. The one or more actuators 141 of the active clearance means 140 are configured to allow for a release, preferably a quick release, of the wedge members 132 so as to frictionally engage the elongated rigid intermediate element 121.

[0091] The actuators 141 of the active clearance means comprise a hydraulic cylinder 141c, e.g. arranged to exert a force on the wedge member opposite to the force of the one or more springs. For example, a spring acts on a respective boom-facing end of the wedge-member and a hydraulic cylinder acts on opposed respective end facing the upper part of the crane structure.

[0092] The outer end of the elongated rigid intermediate element 121o is provided with a first connector part 124a and the boom 105 is provided with a second connector part 124b, said connector parts being configured to provide for a releasable connection between the outer end and the boom, e.g. when the boom is outside of a range of upright positions of the boom.

Claims

C L A I M S1. Crane (100), e.g. configured for use on or mounted on a vessel, the crane comprising: a base structure (103); a crane structure (104), supported by the base structure (103) such as to be slewable about a vertical slew axis (104x) relative to the base structure; and a boom (105), supported by the crane structure (104) such as to be pivotal relative thereto about a horizontal boom pivot axis (105x), wherein the crane structure (104) extends with an upper part (104s,104f) thereof to a height above the boom pivot axis (105x), the crane further comprising: a boom luffing assembly, comprising a boom luffing winch and a boom luffing wire (106) extending from the boom luffing winch to the boom ; and a hoisting assembly for hoisting a load, comprising a hoisting winch, a departure sheave on the boom and a hoisting wire extending from the hoisting winch via the departure sheave to a load suspension device, the crane further comprising: a boom restrainer (120) operative between the upper part (104s, 104f) of the crane structure (104) above the boom pivot axis (105x) and the boom (105) for restraining undue accelerated upward pivoting of the boom, e.g. in case of loss of load, the boom restrainer comprising:- a first rigid intermediate element (121) extending between the boom and the upper part of the crane structure above the boom pivot axis (105x) and guided relative to the upper part of the crane structure such as to be movable with the boom as the boom is pivoted upward in a range of upright orientations under control of the boom luffing assembly, the first rigid intermediate element being configured to be engaged, e.g. connected or connectable, with the boom in said range of upright orientations,- passive countering means (130), comprising one or more engaging elements (131 ,132) which are configured to be brought and maintained in a state of stored energy, in which the engaging elements provide clearance for movement of the first rigid intermediate element, and thereby of the boom into and within said range, and wherein the engaging elements, upon a release, e.g. quick release, of said state, use said stored energy to engage, within said range, the rigidintermediate element and thereby counteract, preferably block, said upward pivoting of the boom within said range to slow down, preferably stop, the boom,- active clearance means (140), comprising one or more actuators (141) configured and arranged to at least maintain said engaging elements of the passive countering means in said state of stored energy, and to allow for said release from this state, and- a trigger system comprising detection means for detecting an anomalous situation causing or potentially causing undue accelerated upward pivoting of the boom, e.g. involving an upward pivoting of the boom within said range of upright orientations thereof at an acceleration which exceeds a predetermined threshold value, and configured to initiate said release by the active clearance means upon detection of said anomalous situation, e.g. and to not initiate said release, maintaining the passive countering means in the state of stored energy, when said anomalous situation is not detected.

2. Crane according to claim 1 , wherein the stored energy is elastic potential energy, and wherein the actuators of the active clearance means are arranged and configured to act in the line of force thereof to maintain the engaging elements in the state of stored elastic potential energy, e.g. wherein the engaging elements of the passive countering means comprise one or more springs (131), e.g. acting on the engaging elements in a direction towards the upper part of crane structure, so as to cause or to increase an initial frictional engagement with the first rigid intermediate element (121), and the actuators, e.g. multiple cylinders, are configured and arranged for maintaining a tensioned, e.g. compressed, state of the springs (131).

3. Crane according to claim 1 or 2, wherein the passive countering means of the boom restrainer (120) comprise one or more wedge members (132) arranged such, that the stored energy when released acts thereon with its line of force the in the line of movement of the wedge members, the wedge members being arranged for being, upon the release of the actuators of the active clearance means, movable slantedly to a longitudinal axis (121x) of the first rigid intermediate element towards frictional engagement with the first rigid intermediate element, each wedge member being movable with a wedge surface (132s) thereof along a guiding surface (133s) that is slanted towards the first intermediate element (121) when seen in the longitudinal direction of the first rigid intermediate element towards the upper part of the crane structure, the one or more wedge members being configured to by said frictionalengagement provide frictional braking, preferably stopping or holding, of the elongated rigid intermediate element.

4. Crane according to claim 3, wherein the passive countering means and active clearance means each act in opposed directions on respective longitudinal ends of the wedge members, considering the longitudinal direction of the first intermediate element from the boom towards the upper part of the crane structure, e.g. springs (131) acting on respective boom-facing ends of the wedge-members (132) and hydraulic cylinders (141) acting on opposed respective ends facing the upper part (104s,104f) of the crane structure.

5. Crane according to any one or more of claims 1 - 4, wherein the first intermediate element is an elongate first rigid intermediate element, e.g. a pipe, e.g. a cylindrical pipe, or beam, which is with one end thereof engageable with, e.g. connectable or connected with, the boom in said range of upright orientations and longitudinally directed from the boom with this end towards the upper part of the crane structure with an opposite end, e.g. the elongate first rigid element being rigidly connected to the boom or integral therewith and extending substantially perpendicularly to the boom, or e.g. pivotally connected to the boom and extending at an angle with the boom that increases with the upward pivoting of the boom in said range, e.g. wherein said connection with the boom is releasable at least outside the range of upright positions, e.g. wherein said engaging elements (131 ,132) are provided at multiple locations distributed around the circumference of the first rigid intermediate element, so as to engage the elongate first rigid intermediate element at multiple locations distributed around its circumference, e.g. the wedge members being arranged in a housing (145) of the boom restrainer.

6. Crane according to any one or more of claims 1 - 5, wherein the passive countering means and the active clearance means are mounted to the upper part of the crane structure via a second rigid intermediate element (122), e.g. an elongate second rigid intermediate element, which is with one end thereof connected to, or integral with, the upper part of the crane structure above the boom pivot axis (105x) and longitudinally directed from the upper part of the crane structure towards the boom, e.g. extending perpendicularly to the slew axis, e.g. the first rigid intermediate element being longitudinally guided along the second rigid intermediate element through guiding means interconnecting both rigid elements, e.g. the first rigid intermediate element longitudinally sliding along the second rigid intermediate element.

7. Crane according to any one or more of claims 1 - 6, wherein at least the first rigid intermediate element, the passive countering means, and the active clearance means are provided in at or near a top end of the upper part of the crane structure (104), e.g. at a height above the boom pivot axis of between 20-80% of the boom height, e.g. around 25-40%, when the boom is in said range of upright orientations.

8. Crane according to any one or more of claims 1 - 7, wherein the crane is configured for use on a vessel, the base structure of the crane being adapted to be mounted to, or formed integral with, the vessel, e.g. with the hull of the vessel.

9. Crane according to any one or more of claims 1 - 8, wherein the boom restrainer comprises a boom connector (124) configured to provide for a releasable connection between the outer end and the boom, e.g. released or releasable when the boom is outside of a range of upright positions of the boom, the boom connector comprising a first connector part (124a) secured to or integral with the first rigid intermediate element and a second connector part (124b) secured to or integral with the boom for receiving the first connector part in a direction opposite to the direction of said pivoting of the boom when the boom is within said range, for connection of said first rigid intermediate element with the boom.

10. Crane according to any one or more of claims 1 - 9, wherein the actuators of the active clearance means of the boom restrainer are configured to once the engaging elements have been brought into the state of stored energy, assume a locking state in which they maintain the engaging elements in the state of stored energy substantially without requiring energy.11 . Crane according to any one or more of claims 1 - 10, wherein the actuators of the active clearance means are hydraulic cylinders which are configured and arranged to exert a force onto the engaging elements of the passive countering means which opposes the force exerted thereby in the state of stored energy, for maintaining the engaging elements in the state of stored energy thereof.

12. Crane according to any one or more of claims 1 - 11 , wherein the boom restrainer (120) provides a collapsed mode in which it is free from the boom and is folded along the upper part (104s, 104f) of the crane structure with the first rigid element in a retracted position, e.g. wherein the crane is according to claim 6 and said second rigid intermediate element (122) is pivotable relative to the crane structure around a horizontal axis to move the boom restrainer into said collapsed position.

13. Crane according to any one or more of claims 1 - 12, wherein the boom restrainer further comprises a linear motion drive (155m, 155c) configured to provide linear motion of the first rigid intermediate element relative to the crane structure, e.g. relative to the second intermediate element when present, to have the outer end (121o) follow a pivoting movement of the boom controlled by the luffing assembly.

14. Crane (100), e.g. configured for use on or mounted on a vessel, the crane comprising: a base structure (103), e.g. configured to be fixed or fixed to the hull of the vessel; a crane structure (104) supported by the base structure (103) such as to be slewable about a vertical slew axis (104x) relative to the base structure; and a boom (105) supported by the crane structure (104) such as to be pivotal relative thereto about a horizontal boom pivot axis (105x), wherein the crane structure (104) extends with an upper part (104s, 104f) thereof to a height above the boom pivot axis (105x), the crane further comprising: a boom luffing assembly, comprising a boom luffing winch and a boom luffing wire (106) extending from the boom luffing winch to the boom, a hoisting assembly for hoisting a load, comprising a hoisting winch, a departure sheave on the boom, and a hoisting wire extending from the hoisting winch via the departure sheave to a load suspension device, the crane further comprising: a boom restrainer (120), mounted on the upper part of the crane structure and operative between the upper part (104s,104f) of the crane structure (104) and the boom (105) for restraining undue accelerated upward pivoting of the boom, e.g. in case of loss of load, the boom restrainer comprising: an elongated rigid intermediate element (121) extending between the boom and the upper part of the crane structure and longitudinally guided by guiding means (125) of the boom restrainer such as to be movable along with the boom as the boom is pivoted in a range of upright orientations under control of the boom luffing assembly, the elongated rigid intermediate element having an outer end (121 o) configured to be engaged, e.g. connected or connectable, with the boom in said range of upright positions, one or more wedge members (132) configured for frictional engagement with the rigid intermediate element, each wedge member being movable with a wedge surface(132s) thereof along a guiding surface (133s) which is slanted towards the rigid intermediate element (121) when seen in the longitudinal direction of the rigid intermediate element towards the upper part of the crane structure, the one or more wedge members being configured to by said frictional engagement provide frictional braking, preferably stopping or holding, of the elongated rigid intermediate element.

15. Crane according to claim 14, wherein the elongated rigid intermediate element is a pipe, e.g. a cylindrical pipe.

16. Crane according to claim 14 or 15, wherein the wedge members (132) are provided at multiple locations distributed around the circumference of the elongated rigid intermediate element (121), e.g. the pipe (121), so as to frictionally engage the elongate first rigid intermediate element at multiple locations distributed around its circumference, e.g. the wedge members being arranged in a housing (145) of the boom restrainer.

17. Crane according to any one or more of claims 14 - 16, wherein the boom restrainer further comprises a linear motion drive (155m, 155c) configured to provide linear motion of the rigid intermediate element relative to the crane structure to have the outer end (121 o) follow a pivoting movement of the boom controlled by the luffing assembly.

18. Crane according to any one or more of claims 14-17, wherein the boom restrainer further comprises one or more springs (131) acting on the one or more wedge members in a direction towards the upper part of crane structure, so as to cause or to increase an initial frictional engagement with the elongated rigid intermediate element (121).

19. Crane according to any one or more of claims 14-18, wherein the boom restrainer further has active clearance means (140) which comprise one or more actuators (141) which are configured and arranged for maintaining the one or more wedge members (132) cleared from the elongated rigid intermediate element (121), e.g. with the one or more springs (131) of claim 18 in a state of stored energy, and which are configured to allow for a release, e.g. a quick release, of the one or more wedge members so as to frictionally engage the elongated rigid intermediate element (121).

20. Crane according to claim 19, wherein the actuator(s) of the active clearance means (140) comprise a hydraulic cylinder, e.g. arranged to exert a force on the wedge member opposite to the force of the one or more springs (131), e.g. wherein a spring (131) acts on arespective boom-facing end of the wedge-member (132) and a hydraulic cylinder (141) acts on opposed respective end facing the upper part (104s,104f) of the crane structure21 . Crane according to claim 19 or 20, wherein the boom restrainer further has a trigger system comprising detection means for detecting an anomalous situation causing or potentially causing undue accelerated upward pivoting of the boom, e.g. involving an upward pivoting of the boom within said range of upright orientations thereof at an acceleration which exceeds a predetermined threshold value, and configured to initiate said release by the active clearance means upon detection of said anomalous situation, e.g. and to not initiate said release, maintaining the passive countering means in the state of stored energy, when said anomalous situation is not detected.

22. Crane according to any one or more of claims 1 - 21 , wherein the boom restrainer comprises a boom connector (124), the outer end (121o) of the elongated rigid intermediate element (121) being provided with a first connector part (124a) and the boom being provided with a second connector part (124b), said connector parts being configured to provide for a releasable connection between the outer end and the boom, e.g. released or releasable when the boom is outside of a range of upright positions of the boom.

23. Vessel comprising the crane according to any one or more of claims 1 - 22, the base structure (103) of the crane being mounted to, or formed integral with, the vessel, e.g. the hull of the vessel.

24. Pile installation method in which use is made of a crane (100) according to any one or more of claims 1 - 22 or a vessel according to claim 23.

25. Pile installation method according to claim 24, wherein use is made of a crane (100) according to any one or more of claims 1 - 13, and wherein the pile installation method comprises: suspending a pile, e.g. a monopile, from the load suspension device of the crane (100), displacing the pile towards an installation location by operating the one or more hoist winches of the crane, and / or by operating the one or more luffing winches of the crane to pivot the boom about its boom pivot axis, and / or by slewing the boom around the vertical slew axis, wherein during at least said displacing of the pile, the boom restrainer (120) is operated by the trigger system thereof to detect by the detection means an anomalous situation causingor potentially causing undue accelerated upward pivoting of the boom, e.g. involving an upward pivoting of the boom (105) within said range of upright orientations thereof at an acceleration which exceeds a predetermined threshold value, and to control the operation of the active clearance means (140) such as to initiate said quick release upon detection of said anomalous situation, e.g. and to maintain the passive countering means (130) in the state of stored energy when said anomalous situation is not detected.

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