Boom stabilisation system for offshore crane

Abstract

A boom stabilization system for an offshore crane (1) includes: a boom (3) mounting component arranged to be mounted to the boom of the offshore crane; a support mounting component mounted to a support structure (2) for the offshore crane; wherein the boom mounting component includes a frame (12) having at least one longitudinally extending chord (16); wherein the support mounting component includes a biasing element (14) biased toward an extended position, wherein the boom mounting component and the support mounting component are configured to engage each other when the boom angle of the boom exceeds a first predetermined threshold. The system is configured to use the biasing element to cause a limitation and / or reduction in the boom angle so as to suppress slack in the luffing cable (5) of the offshore crane at least when the boom angle exceeds a second predetermined threshold, the second predetermined threshold being greater than the first predetermined threshold.

Description

Technical Field

[0001] This invention relates to offshore cranes. In particular, this invention relates to a boom stabilization system for offshore cranes. Background Technology

[0002] Offshore cranes are well-known and are typically mounted on floating structures, such as ships, barges, or jack-up platforms. They are used for a variety of purposes, including heavy lifting operations at sea, such as installing and decommissioning heavy structures like wind turbines, wind turbine infrastructure, platforms, and platform tops.

[0003] Offshore cranes typically consist of a boom pivotally mounted to a supporting structure. At the end of the boom, a load can be lifted. Various failure modes are known to crane designers, and offshore cranes are designed and constructed with such failure modes in mind. In some failure modes, excessive boom swing caused by the sudden absence of one or more forces or by a catastrophic event (e.g., loss of load, luffing or lifting cable failure, ship movement, hook failure) can lead to excessive boom instability. This can result in structural damage, or in some cases, complete destruction of the boom and / or other crane components and / or structures near the boom. Various structures are known to limit the position of the boom and / or define its end position. A common structure is a boom stop: typically a hydraulic cylinder mounted on an A-frame or similar structure, which engages the boom in a direction transverse to its longitudinal direction. When the boom reaches its end position, the boom stop engages a stop surface. However, the effectiveness of such boom stops is limited and may not prevent structural damage to the boom or other crane components in cases of excessive boom instability. A possible alternative or additional measure to improve boom stability is to impose a relatively large minimum working radius (also known as minimum reach distance) on the crane, which is the horizontal distance from the crane base to the nearest possible location of the load suspended from the crane. However, a large minimum reach distance limits the crane's versatility in terms of possible load locations and may also result in the crane requiring excessive space for operation, which can be particularly problematic in confined environments such as ship decks or offshore platforms. Summary of the Invention

[0004] The object of this invention is to provide a boom stabilization system for offshore cranes. In particular, the object of this invention is to provide a boom stabilization system that can efficiently and / or effectively limit or prevent damage to the crane, while allowing the crane to have a relatively small minimum outrigger distance.

[0005] Therefore, the present invention provides a boom stabilization system according to claim 1, comprising a boom mounting component and a support mounting component. One of the boom mounting component and the support mounting component includes a frame having at least one longitudinally extending chord, and the other of the boom mounting component and the support mounting component includes a biasing element biased toward an extended position. The boom mounting component may include a frame having at least one longitudinally extending chord, wherein the distance from at least one chord to the boom is larger near the base of the frame and smaller near the end of the frame. Subsequently, the at least one longitudinally extending chord may include an angle with respect to the longitudinal principal axis of the boom, wherein the angle may be in the range of 1 degree to 30 degrees, more preferably in the range of 5 degrees to 25 degrees, even more preferably in the range of 10 degrees to 20 degrees, for example, about 15 degrees. It has been found that such an angle can produce a particularly advantageous combination of lateral and longitudinal stabilizing effects on the boom, wherein the lateral component can be associated with more directly counteracting unfavorable swaying motions, while the longitudinal component can be associated with the load on the boom along its longitudinal axis. Without wishing to be bound by theory, it is believed that such an angle can therefore advantageously convert at least a portion of the momentum associated with the boom swing into a load on the boom along its longitudinal axis.

[0006] The frame can be implemented as a truss or non-truss, such as a box frame or a frame comprising plates and / or trusses. Thus, viewed from the side, the frame having at least one chord can be triangular relative to the boom, with the chord extending obliquely toward the boom. The frame base can be located at the bottom end of the boom (boom base). The distance between at least one chord and the boom can be greater at the boom base than at a distance away from the boom base, with the chord pointing toward the boom. At least one chord of the frame can be connected to the boom via a bracket or truss, at least at the bottom and / or top end of the chord. At least one chord of the frame can be directly connected to the boom, or can be connected to the boom via a bracket. In the latter case, at least one chord can be said to be floating, or can be said to be supported on the boom only by a bracket. Preferably, the frame comprising at least one chord is mounted to the boom and permanently connected to the boom, even during normal operation. The truss or bracket of the frame can be connected to the truss or bracket of the boom, and / or can be connected to the chord of the boom. In known designs, the boom includes trusses, supports, and / or chords, and may even consist primarily of such trusses, supports, and / or chords. However, it should be understood that the boom can be designed to partially or completely lack such elements, for example, including one or more beams, plates, etc. Multiple trusses or supports can be provided along the length of the frame, which can be connected to the boom at various longitudinal and / or radial locations. Thus, along the boom length where the boom mounting components are connected to the boom, the connections between the trusses of the frame of the boom mounting components on one side and the trusses or chords of the boom on the other side are provided at multiple different locations in the axial (i.e., longitudinal direction of the boom) and / or radial (i.e., transverse to the axial direction). Such multiple and / or different connections at different locations can beneficially transfer loads from the stabilizing system to the boom. The boom mounting components implemented as frames are typically connected to the boom by welding and / or bolting, but hinged connections can also be considered.

[0007] One of the boom mounting component and the support mounting component may be hingedly mounted to its associated mounting base to allow the boom mounting component to follow the movement of the boom when engaged with the support mounting component. Furthermore, one of the boom mounting component and the support mounting component is a compressible element, preferably biased toward an extended position to allow it to follow the movement of the boom and / or absorb energy when engaged with the support mounting component.

[0008] The boom is pivotally connected at its base to a support structure or base structure. Such a support structure or base structure can be, for example, a slewing platform. Support mounting components of the boom stabilization system are mounted to such a support structure. The support mounting components may include a biasing element offset toward an extended position. The biasing element is typically a compressible element, as it can be compressed upon contact and / or under load. The biasing element can be, for example, a hydraulic cylinder, a pneumatic cylinder, or a spring-based system. The biasing element may be pivotally mounted to the support structure at its lower end and may be configured at its outer free end to engage with the frame of the boom mounting components. Subsequently, the bottom end of at least one chord of the frame is preferably configured to engage with the outer end of the biasing element when the angle of the boom relative to the horizontal becomes relatively large (i.e., greater than a first threshold, which can be predetermined). The angle of the boom relative to the horizontal plane is generally referred to as the boom angle. Engagement between the frame and the biasing element is envisioned at or near a boom angle of approximately 60 degrees, preferably between approximately 40 and 70 degrees. As the boom angle subsequently increases, the biasing element is compressed by the frame against the biasing force. In unintended swinging motions, when the boom angle increases, especially rapidly, the biasing element can absorb the energy of the motion (e.g., swinging motion), while forces such as overturning moments can be transmitted via the frame to the boom chords. Thus, the force can be directed in a direction that does not amplify the boom's swinging motion, but rather to the boom chords designed to withstand such high loads. Therefore, the boom stabilization system effectively prevents excessive boom swinging and, consequently, prevents damage to the boom due to excessive swinging motion. Furthermore, by providing a truss, a relatively lightweight structure can be provided that effectively directs loads to the boom chords, for example, in cases where excessive boom swinging is possible, thereby limiting or preventing failure.

[0009] Advantageously, the boom mounting components and / or support mounting components are provided with engagement elements that engage with each other when the boom angle exceeds a predetermined angle.

[0010] Multiple biasing elements can be provided to engage with the frame of the boom mounting components. For example, two or more biasing elements can be considered to share a common engagement element, thus they can be considered to be positioned in parallel. Alternatively, the biasing elements can be positioned in series. Moreover, combinations of series and parallel configurations of multiple biasing elements are possible.

[0011] Furthermore, it is understood that the compressible element serving as a biasing element may additionally include a damping element, such as a gas damper or a pleated region.

[0012] Alternatively, the support mounting component can be a fixed element such as a frame, and the boom mounting component can be a compressible element such as a biasing element. Furthermore, engagement occurs when the boom angle exceeds a first predetermined threshold, and the boom mounting component is compressed, while the load can be directed to the support and / or the boom.

[0013] In optional detailed configurations, such as in the event of a disaster, when the boom might begin to accelerate, the biasing element can be locked to stop further movement of the boom, thereby preventing further acceleration. Locking of the biasing element can occur at any position between the fully extended and fully compressed positions (inclusive). For example, locking of the biasing element can be passively achieved when the pressure in the biasing element increases too rapidly. Locking can be accomplished mechanically, hydraulically, or by other means, such as for holding the biasing element or for shutting off fluid flow. Thus, in the extended position, the biasing element can be locked, i.e., the extended position of the biasing element is frozen and the biasing element is blocked in that position. The portions of the biasing element that can extend relative to each other between the fully extended and fully compressed positions are blocked at the locked position and cannot move relative to each other. Therefore, optionally, the boom stabilization system can be configured to allow the biasing action of the biasing element to be suspended by locking the biasing element, thereby essentially fixing the normally variable-length biasing element, at least until the subsequent release of the lock. When the boom mount and support mount engage, potentially causing pressure buildup in the bias element, the bias element can be locked. If the pressure on the bias element becomes too high, for example, exceeding a predetermined threshold, the bias element can be locked; when the pressure may become lower or drop below the predetermined threshold, the lock can be released, allowing the bias element to remain engaged with the boom mount support. Such thresholds for locking and releasing can be the same, but preferably different, to prevent excessively rapid switching between locking and releasing. In other words, a hysteresis effect regarding locking and releasing can thus be provided.

[0014] During normal crane operation, when the boom angle becomes greater than a predetermined boom angle, the support mounting component and the boom mounting component engage. During normal crane operation, when the support mounting component and the boom mounting component are engaged, they move together with the boom. In normal operation, the movement of the support mounting component and the engaged boom mounting component with the boom is smooth. Subsequently, in normal operation, the biasing element of the support mounting component is compressed and / or extended to follow the boom movement. In normal operation, the boom stabilization system does not introduce or transfer any additional load to the boom. In some cases, the boom end may accelerate, and when the boom angle exceeds the predetermined boom angle, engagement occurs between the boom mounting component and the support mounting component before the boom mounting component and the support mounting component are engaged. Furthermore, the engaged boom mounting component and the support mounting component move together, while the additional energy from the boom acceleration can be absorbed by the biasing element and / or the biasing element can be locked. Thus, loads can be introduced into the longitudinal direction of the boom and / or the support structure. The boom is capable of handling large loads via the chord. This effectively prevents excessive boom sway without causing damage to the boom and / or its environment, or causing only limited damage.

[0015] Because the biasing element is biased toward its extended position, this can help maintain tension on the luffing cable of the luffing system when the boom mount and support mount are engaged, potentially allowing for suppression of cable slack, particularly by making the biasing element sufficiently large to correspondingly limit or reduce the boom angle.

[0016] In any case, when the boom angle is around 60 degrees, the bottom end of at least one chord engages with its associated offset element, which can follow the boom's tilt. During normal operation, a boom angle of approximately 83 degrees can be achieved. The offset element can then be in its fully retracted position; in other words, it can be fully compressed. When the boom is lowered, the offset element also follows the boom's movement, and when the boom angle becomes less than approximately 60 degrees, the offset element and frame can disengage, and the offset element returns to its extended position.

[0017] Typically, an A-frame can be mounted to a supporting structure, such as to guide the luffing system and / or lifting system of a crane. Such an A-frame usually has four connections to the supporting structure, arranged in two pairs spaced apart from each other. When the boom has two boom legs at its lower end, the boom base connection can be integrated into one pair of such connections on the A-frame, or the boom base can have its own supporting connection independent of the A-frame connection. In the latter example, the boom base connection is typically mounted externally to the A-frame connection. Furthermore, when the boom is a single boom with a single boom leg, the connection from the boom base to the supporting structure can be separate from the connection to the A-frame or similar frame structure. Advantageously, biasing elements are also mounted on the supporting structure adjacent to the A-frame.

[0018] The boom mounting component of the boom stabilization system is mounted on the upper side of the boom, which can also be referred to as the rear side of the boom, i.e., the side of the boom opposite to the side where the load lifted by the boom is typically positioned. Viewed from the side, it can be seen that the boom has an additional triangular frame mounted on this upper side, particularly near the boom base. Of course, the frame can be a three-dimensional structure with a more prismatic shape, having a larger base at the frame base and boom base, and a smaller end where at least one chord of the frame meets or nearly meets the chord of the boom. When the lower end of the boom is constructed as two boom legs, each boom leg can be provided with such a frame for the boom mounting component. Subsequently, two offset elements are also arranged. For each chord of the frame of the boom mounting component, an associated offset element supporting the mounting component is envisioned. For example, when a frame on a boom leg has two longitudinally extending chords connected to the boom via a truss, there may be two lower ends of the chords configured to engage with two corresponding bias elements. Alternatively, the two lower ends of the chords may engage to form a single engagement element with the corresponding bias element.

[0019] In the rest position, the biasing element is not engaged and is preferably positioned such that it can optimally engage with the frame on the boom when the boom angle reaches approximately 50 degrees, preferably approximately 60 degrees. Therefore, in the rest position, the biasing element has an angle relative to the support platform, allowing engagement with the frame at or near a boom angle of 50 to 70 degrees, preferably approximately 60 degrees. To hold the biasing element in the rest position, a support arm can be provided that holds the biasing element in the rest position and also accommodates the biasing element when it disengages from the frame. The support arm can be U-shaped to limit excessive lateral movement of the biasing element. In fact, the biasing element is preferably hinged to the support structure, so excessive lateral movement of the biasing element could lead to failure of the hinged connection, which can be prevented by the support arm, particularly by the U-shape of the support arm (e.g., a U-shaped bracket). Advantageously, in the rest position, the biasing element is also biased toward its extended position. When engaged, the biasing element can be compressed and / or extended to follow the movement of the boom. In addition, the angular position of the bias element can be different from the stationary position so that it can follow the movement of the boom.

[0020] The boom stabilization system is configured to use the bias stiffness of a biasing element to limit and / or reduce the boom angle, so as to suppress slack in the luffing cable of the offshore crane, at least when the boom angle exceeds a second predetermined boom angle threshold, which is greater than a first predetermined boom angle threshold. The second predetermined boom angle threshold may be in the range of 77 degrees to 89 degrees, preferably in the range of 80 degrees to 86 degrees, for example, about 83 degrees.

[0021] By using biasing elements to suppress slack in this way, it is advantageous to improve the stability of the boom and the overall stiffness of the crane when the boom angle is relatively large. Typically, at such large boom angles, slack in the luffing cable is relatively easy to occur, leading to reduced boom stability and overall crane stiffness, particularly associated with the risk of excessive boom sway. For example, environmental influences from wind or waves often cause boom instability, where relatively small disturbances can sometimes be amplified, subsequently resulting in impacts to the crane structure, such as when the boom essentially falls back to the smaller boom angle limited by the luffing cable. Such impacts, especially if excessive, can cause damage to crane components such as the luffing cable and pulleys, which in turn can even cause the boom to detach from its luffing cable and fall. Furthermore, in some cases, the boom may overturn due to excessive sway, i.e., tilt backward beyond its vertical position.

[0022] In this regard, without being bound by theory, it is generally assumed that at relatively large boom angles, the so-called recovery action of the boom against uncontrolled rotation or swaying is relatively small. In this context, the recovery action can be understood as the change in the lateral component of the force exerted on the boom by the luffing cable due to the change in boom angle. The initial equilibrium of this force is typically caused, for example, by the gravitational component acting on the boom directly and / or via the suspended load, which drives the boom toward a decreasing boom angle, i.e., those gravitational components acting laterally to the boom's main axis to generate a downward moment on the boom. As the boom angle approaches 90 degrees (corresponding to a vertical boom main axis), the recovery action further decreases as the direction of the forces from gravity and the luffing cable becomes increasingly parallel to the boom's main axis, resulting in a smaller lateral force component, thus leaving only a small moment associated with the distance between the boom's main axis and the luffing cable and / or the lifting cable connected to the boom.

[0023] At the same time, simply pulling the luffing cable (e.g., using a winch) to reduce the slack in it will not be effective and may even exacerbate the problem, because this only raises the lower limit of the boom angle imposed by the luffing cable, meaning the boom may still swing further to a larger boom angle.

[0024] In contrast, when a boom stabilization system is configured to use the offset stiffness of an offset element to limit and / or reduce the boom angle in order to suppress slack in the luffing cable of an offshore crane, the boom can remain stable, even at relatively high boom angles, thus substantially increasing the typically relatively small reset action. Specifically, while the luffing cable can impose a variable lower limit on the boom angle, the boom stabilization system can simultaneously impose a substantially corresponding upper limit on the boom angle, such that in terms of uncontrolled boom rotation, the boom can be substantially and continuously constrained to a very narrow (e.g., near-zero) range of possible boom angles, while still allowing controlled adjustment of the boom angle over a relatively wide range of possible boom angles (e.g., including boom angles up to approximately 90 degrees). Furthermore, the increased likelihood of safe crane operation at such large boom angles improves the crane's versatility and, in particular, reduces the minimum reach distance of the crane, thereby, for example, relaxing requirements for free deck space around the crane.

[0025] Optionally, at least selectively and / or when the boom angle exceeds a second predetermined boom angle threshold, the bias stiffness of the bias element is designed to maintain the boom angle at a variable lower limit applied to the boom angle by the luffing cable, wherein, in particular, the bias stiffness is designed with respect to the boom angle to dampen possible environmental disturbances acting on the boom.

[0026] Referring to the explanation above, in this way, regarding uncontrolled boom rotation, the boom can therefore be essentially and continuously constrained to a very narrow range of possible boom angles, while still allowing controlled adjustment of the boom angle within a relatively wide range of possible boom angles. Generally, such uncontrolled boom rotation can be particularly associated with environmental disturbances, such as relatively random boom movements caused by wind and / or waves, which can act directly on the boom and / or via the vessel or offshore platform on which the crane is mounted and / or via the load suspended from the crane.

[0027] Therefore, when the lower limit of the boom angle applied by the luffing cable is fixed, the boom stabilization system is preferably configured to substantially limit or constrain the boom angle to said lower limit. When the lower limit of the boom angle applied by the luffing cable increases (i.e., when the luffing cable is pulled in), the limitation or constraint provided by the boom stabilization system preferably follows this lower limit, i.e., substantially increases the upper limit applied to the boom angle accordingly. When the lower limit of the boom angle applied by the luffing cable decreases (i.e., when the luffing cable is extended), the limitation or constraint provided by the boom stabilization system also preferably follows this lower limit, i.e., substantially decreases the upper limit applied to the boom angle accordingly, to the extent that the boom angle reduction can be achieved by the boom stabilization system if gravity alone cannot fully or stably reduce the boom angle.

[0028] Alternatively, the boom stabilization system is configured to actively change the bias stiffness of the bias element, preferably using a hydraulic or pneumatic control circuit operably connected to the bias element.

[0029] In this way, the offset stiffness can be increased if needed and when boom stabilization is required, while a reduced offset stiffness is permissible in other cases. Advantageously, such a reduced offset stiffness can lead to improved energy efficiency, for example, in terms of the energy required to pull in the luffing cable. It should be understood that when the offset stiffness is actively increased in this manner, it is preferable to achieve appropriate active control of the luffing cable, for example, via a winch associated with the luffing cable, particularly to prevent excessive opposing forces from both the luffing cable and the offset element. Thus, for example, the speed and / or torque of the winch associated with the luffing cable can be synchronized with the operation of the offset element.

[0030] Optionally, the boom stabilization system is configured to not cause a limitation and / or reduction in the boom angle when the boom angle does not exceed a second predetermined boom angle threshold.

[0031] In this way, the crane can operate with higher energy efficiency, particularly in terms of the energy requirements for pulling in luffing cables. Meanwhile, when the boom angle does not exceed a second predetermined boom angle threshold, the boom remains sufficiently stable due to the gravitational component (i.e., due to the sufficiently large reset action associated with such a small boom angle). However, it should be understood that at such a small boom angle, the biasing element may still exert some influence on the boom angle, particularly a damping effect, which does not imply a limitation or reduction in the boom angle. Such a small damping effect can advantageously contribute to boom stability, for example, preventing excessive swaying as explained elsewhere in this document. Therefore, the biasing element can exhibit a larger bias stiffness when the boom angle exceeds the second predetermined boom angle threshold and a smaller, but non-zero, bias stiffness when the boom angle is between the first and second predetermined boom angle thresholds. This angle-dependent difference in bias stiffness can be achieved in various ways, as further explained elsewhere in this document.

[0032] Optionally, the boom stabilization system includes one or more sensors arranged to generate signals indicating that slack in the luffing cable may need to be suppressed in order to stabilize the offshore crane.

[0033] For example, such sensors can respond to changes in one or more of the following: the boom angle, the piston position of the biasing element, the tension in the luffing cable, the tension in the lifting cable (e.g., associated with load loss), and the speed and / or magnitude of the boom. It should be understood that such and other parameters can at least partially indicate the potential need to suppress slack in the luffing cable to stabilize the crane. For example, the potential need to suppress slack can typically increase with increasing boom angle, stronger winds, stronger wave action on the ship or platform, and lighter crane loads. In cases where suppression of such slack is necessary, utilizing the limitations and / or reductions in the boom angle provided by the boom stabilization system may be particularly advantageous, while at other times, less or no utilization of available limitations and / or reductions may be preferred, for example, due to energy efficiency considerations. To facilitate a balance between safety and efficiency during crane operation, the generated signal, or a signal derived from it, can be presented to the crane operator, who can then take appropriate responsive actions, such as by actively controlling the boom stabilization system and / or another component of the crane. In some cases, an automatic controller can be provided, configured to receive signals and automatically take such responsive actions, for example, based on predetermined criteria that can represent the desired balance between safety and efficiency. Advantageously, such responsive actions may include increasing the stiffness of the bias element of the boom stabilization system to suppress slack in the luffing cable, and other possible actions. The increase in stiffness can be achieved, for example, by increasing the hydraulic or pneumatic pressure in a hydraulic or pneumatic control line operatively connected to the bias element (e.g., one or more hydraulic or pneumatic cylinders connected to the bias element). Correspondingly, the stiffness can be reduced if the need to suppress slack earlier is reduced or terminated (e.g., when the boom angle is relatively low, when environmental conditions are relatively mild, when the crane load is relatively heavy, etc.). Such increases and / or decreases in stiffness can be, for example, stepwise, switching between two, three, four, five, or more predetermined stiffness levels, depending, for example, on the crossing of thresholds such as possible third and further predetermined boom angle thresholds and / or other parameters mentioned herein. Alternatively, such increases and / or decreases can be gradual, i.e., gradual adjustments proportional to, for example, the gradual change required to suppress slack. Correspondingly, the generated or derived signal can be discrete or continuous. Furthermore, such a signal can be one-dimensional or multi-dimensional and can be generated using one or more possible sensors. In some cases, the generated or derived signal can be a composite signal representing the overall requirement to suppress slack in the amplitude transformer cable based on inputs from different sensors and / or on evaluations of sensor data according to multiple criteria (such as thresholds).A further possibility is that the adjustment of the stiffness of the bias element (or more generally, the operation of the boom stabilization system) is jointly controlled by the operator and the automatic controller. For example, at a lower, first level of risk, the operator is advised to take a response, leaving the decision to the operator, while at a higher, second level of risk, the system automatically takes such a response. As a further possibility, the system could allow the operator to switch between different modes, such as manual and automatic modes. In some cases, switching to automatic mode can also be automatic, such as when the risk of slack in the luffing cable is determined to be relatively high. Therefore, many different variations of the boom stabilization system can facilitate safe crane operation at large boom angles, especially when combined with appropriate energy efficiency, where various relevant factors can be considered, and where the crane operator can participate more or less.

[0034] The present invention further relates to an offshore crane having a boom pivotally mounted to a support structure, wherein the crane is equipped with a boom stabilization system. Boom-based components are mounted to the boom, and support-based components are mounted to the support structure, preferably pivotally mounted to the support structure.

[0035] In the example, as mentioned elsewhere herein, at least one chord of the frame mounted to the lower end of the boom has an angle of approximately 8 to 30 degrees relative to the longitudinal direction of the boom, preferably approximately 10 to 20 degrees, and more preferably approximately 15 degrees. The frame may be mounted at the lower 10% to 50% of the boom, for example, at the lower 10% to 40% (preferably 12% to 35%) of the boom length. The upper end of at least one longitudinal frame chord of the boom mounting component may extend to approximately 20% to 40% of the boom length, preferably approximately 25%.

[0036] More generally, and advantageously, the boom mounting component is mounted at the lower end of the boom, preferably at the lower 10% to 50% of the boom chord. As described above, the boom mounting component can be a frame or a compressible element, such as a biasing element. Attached Figure Description

[0037] These and other aspects will be further illustrated with reference to the accompanying drawings, which include exemplary embodiments. The drawings show:

[0038] Figure 1a It is an offshore crane with a boom stabilization system in the first position;

[0039] Figure 1b It is an offshore crane with a boom stabilization system in the second position;

[0040] Figure 1c It is an offshore crane with a boom stabilization system in a third position;

[0041] Figure 2 It is the boom of an offshore crane with a boom mounting component that has a boom stabilization system;

[0042] Figure 3 yes Figure 2 Details of the boom mounting components;

[0043] Figure 4 In the context of Figure 1c Details of the support mounting components with support arms in the corresponding situation;

[0044] Figure 5 This is an alternative embodiment of the boom mounting components of the boom stabilization system;

[0045] Figure 6 It is an offshore crane with a boom stabilization system in the fourth position;

[0046] Figure 7 It is a top view of a ship equipped with an offshore crane.

[0047] It should be noted that the accompanying drawings are given by way of example and are not intended to limit this disclosure. The drawings are not drawn to scale. Corresponding elements are indicated by their respective reference numerals. Detailed Implementation

[0048] Figure 1a An offshore crane 1 is shown mounted on a support structure or base structure 2. The offshore crane 1 includes a boom 3 and an A-frame 4, the boom 3 being pivotally mounted to the support structure 2, and the A-frame 4 including, for example, a luffing system 5 and / or a lifting system. Here, a pair of connectors of the A-frame 4 are positioned between the pivotal connection of the boom to the support structure 2, but it should be understood that they can also overlap. The boom 3 has a boom base 6 and a boom end 7. At the boom end 7, a load can be lifted. The offshore crane 1 is provided with a boom stabilization system 8, which includes a boom mounting component 9 and a support mounting component 10. Here, the boom mounting component 9, viewed from the side, is a triangular truss 12 connected to the upper or rear side 11 of the boom. A coupling element 13 is provided at the lower end or base end of the truss, the coupling element 13 being configured to engage with the support mounting component 10. Here, the support mounting component 10 is provided with an offset element 14, such as a hydraulic cylinder or a pneumatic cylinder. The biasing element 14 is pivotally mounted to the support structure 2 and extends in the longitudinal direction. An engagement element 15 is provided at the outer end of the biasing element, which is configured to engage with the engagement element 13 of the boom mounting component 9. For example, in cases of excessive load and / or movement, the boom mounting component 9 and the support mounting component 10 work together to prevent or limit excessive swaying of the boom 3.

[0049] exist Figure 1aThe diagram shows the boom 3 in a first position, where the boom mounting component 9 is detached from the support mounting component 10 and is not engaged with the support mounting component 10. Typically, this applies to boom angles up to approximately 50 to 70 degrees, for example, to approximately 50 to 60 degrees. The boom angle α is considered to be the angle between the longitudinal axis of the boom and the horizontal plane, such as... Figure 1a The diagram is schematically shown. The biasing element 12 of the supporting component 10 is biased toward the extended position.

[0050] Figure 1b It is shown that when the boom angle reaches a predetermined angle α1 (which can be set to any value between approximately 50 and 70 degrees, or approximately such an angle, for example, approximately 60 degrees), the boom mounting component 9 engages with the support mounting component 10. For this purpose, the boom mounting component 9 may be provided with a boom-based engagement element 13, and the support mounting component 10 may be provided with a support-based engagement element 15. Subsequently, the boom-based engagement element 13 and its associated support-based engagement element 15 engage. For example, when the boom mounting component 9 has a chord 16 (the lower end 17 of which is provided with the boom engagement element 13), the boom-based engagement element 13 has a corresponding and associated support-based engagement element 15 on the associated biasing element 14. In another example, frame 12 may have two longitudinally extending chords 16, each chord having a boom-based engagement element 13 at its lower end 17, and two associated support-based engagement elements 15, which may connect to two separate bias elements or to the same single bias element. Multiple bias elements may be arranged in series, in parallel, or in a combination of series and parallel. Once the boom mounting component 9 engages with the support mounting component 10, the bias element 14 is compressed against the biasing force. Thus, the bias element 14 can follow the movement of the crane boom 3 until the bias element 14 is fully compressed and the boom 3 is in its most upward position, for example, as... Figure 6 As shown. The boom angle α3 can be as high as 90 degrees. In the event of unintended boom movement and / or boom acceleration, the boom stabilization system 8 can absorb the energy generated by such movement and can direct excess load to the chord of the boom 3 and / or to the support structure 2. Therefore, damage such as excessive swaying from the boom 3 can be limited or prevented. Figure 1c The boom 3 is shown at a boom angle α2, which is between angles α1 and α3. Angle α2 may correspond to a second predetermined boom angle, as further explained elsewhere herein.

[0051] from Figure 1a , 1b 1c and Figure 6 It can be seen from this, and in Figure 4 As shown in more detail below, the biasing element 14 is supported by the support arm 18. The support arm 18 holds the biasing element 14 in a neutral position, as... Figure 1a As shown, at this position, the biasing element 14 is ready to engage the boom mounting component 9. For optimal engagement of the boom mounting component 9, when the boom 3 reaches boom angle α1, the biasing element 14 is preferably positioned at an angle β, which is between approximately 30 degrees and approximately 65 degrees, depending on (e.g., similar to) the envisioned engagement angle α1. Once the biasing element 14 is engaged with the frame 12, the biasing element 14 can rotate with the boom 3, and at least with respect to such rotation, it can disengage from the support arm 18. The support arm 18 may be provided with a U-shaped bracket at its outer end, which also restricts the lateral movement of the biasing element 14. In this sense, the support arm 18 can continuously cooperate with the biasing element 14 at various rotational positions.

[0052] Figure 2 An example of a boom 3 of an offshore crane is shown. Here, the boom 3 includes two boom legs 19a, 19b at its boom base 6. Each boom leg 19a, 19b is hinged to a support structure to allow the boom 3 to pivot only about the axis of rotation of the hinge. Frames 12a, 12b are mounted to the upper or rear side 11 of the boom 3.

[0053] Here, the boom mounting component 9 includes two frames 12a and 12b, which are connected to two legs 19a and 19b, specifically each frame is connected to a corresponding leg. Therefore, each leg 19a and 19b is provided with an additional frame 12a and 12b. Each frame 12a and 12b includes chords 16a and 16b, respectively. The chords 16a and 16b extend longitudinally and are arranged at an angle relative to the boom 3 (specifically relative to the longitudinal axis of the boom). Here, the angle θ between the chord 16 and the longitudinal axis (see...) Figure 1c The angle is approximately 15 degrees. The distance between the lower ends 20a and 20b of chord 16 and the boom 3 is greater than the distance between the upper ends 21a and 21b of chord 16 and the boom 3. Chords 16a and 16b are connected to the boom 3 via truss or support 22. Figure 3 As can be seen from the details, the upper ends 21a and 21b of the chords 16a and 16b are floating and not directly connected to the boom, but rather connected via truss 22. This ensures smoother force transmission. At the lower ends 20a and 20b, the chords 16a and 16b are connected to the boom 3 via truss 22. Here, truss 22 connects to the boom legs 19a and 19b. Figure 3As shown, the boom-based connecting element 13 located at the lower ends 20a, 20b of the chords 16a, 16b is implemented as a flared element. It should be understood that the connecting element can also be other shapes. In this embodiment, the two frames 12a, 12b are interconnected by an additional bracket 33, but this is optional. The bracket 33 can also be omitted. The longitudinally extending frame chords 16a, 16b are connected to the boom 3 via multiple trusses 22, particularly to the boom base 6. The multiple trusses 22 can be connected to the trusses 34 of the boom 3, or they can be connected to the chords 35 of the boom 3. By connecting the longitudinally extending chords 16a, 16b to the boom 3 at multiple different locations, loads can be distributed to the boom 3, allowing relatively large loads to be transferred before potential damage. This allows for relatively high load transfer of forces that may occur when the boom ends may swing and / or accelerate. Furthermore, the distances D1 between the lower ends 20a and 20b of the frame chords 16a and 16b and the boom 3 (particularly the upper side 11 of the boom 3) are greater than the distances D2 between their upper ends 21a and 21b and the boom 3. In instances where the frame chord 16 is directly connected to the boom 3 (e.g., to the boom chord 35), the distance D2 even becomes zero. Thus, at least one frame chord is inclined toward the boom 3, thereby effectively guiding the force to be transmitted to the boom 3 or the boom chord 35.

[0054] It should be noted that the frame 12 may be provided with two chords instead of a single chord, which may extend toward the two upper chords of the boom 3 or boom leg 19.

[0055] Figure 4 The boom base 6 is shown, which is hinged to the support structure 2 via boom connectors 23a and 23b of the boom legs 19a and 19b. Here, the boom connectors 23a and 23b are separate from the A-frame connectors 24a and 24b. The boom mounting structure 9 is shown engaging with the support mounting member 10, with corresponding engaging elements 13 and 15 cooperating with each other. In this position of the boom 3, the biasing element 14 of the support mounting member 10 is almost completely compressed, indicating that the boom 3 is in its upper position or nearly in its upper position. Figure 4 In the specific example, boom 3 in this case has a boom angle of approximately 83 or 85 degrees. However, in some variations, boom angles as high as approximately 90 degrees or even greater are possible, such as... Figure 6 As shown in the example. Return to Figure 4 As can be applied accordingly Figure 6The illustration shows biasing elements 14a and 14b, which engage with frames 12a and 12b of the boom mounting structure 9, respectively, and are hinged to the support structure 2 via connectors 25a and 25b. As explained above, each biasing element 14a and 14b of the support mounting component 10 is supported by support arms 18a and 18b. Before engagement with the boom mounting component 9, the U-shaped ends 28a and 28b of the support arms 18a and 18b support the biasing elements 14a and 14b in a neutral position. Furthermore, the U-shaped ends 28a and 28b restrict the lateral movement of the biasing elements 14a and 14b, which ensures the integrity of the hinge connectors 25a and 25b. Here, the boom 3 is in an upward position, i.e., at a large boom angle, and it can be seen that the biasing elements 14a and 14b are a distance from the bottom of the U-shaped support ends 28a and 28b, but still between the arms of the U-shaped support ends 28a and 28b. In this example, support arms 18a and 18b are interconnected by rod 29, but this is optional.

[0056] Figure 5 An alternative embodiment of the boom mounting component 9 is shown. The boom mounting component 9 is connected to the boom 3, and particularly to the boom base 6. Here, the boom base 6 has two boom legs 19a, 19b. The boom mounting component 9 includes at least one frame 12, provided here with two frames 12a, 12b, for each boom leg 19a, 19b. Each frame has at least one longitudinally extending chord 16a, 16b, which is spaced at its lower end from the boom 3 and extends in a direction toward the boom 3. Here, the longitudinally extending frame chord 16a, 16b is divided into two chords 30a, 31a and 30b, 31b, which are directly connected to the corresponding boom chords of the boom legs 19a, 19b. In this embodiment, the frames 12a, 12b include a plurality of trusses 22, which are connected to the boom chords at multiple different locations. Thus, forces can be distributed to the boom 3.

[0057] In an alternative embodiment, advantageously, the boom mounting member 12 can be a compressible element biased toward the extended position. Then, the support mounting member 10 can be a frame or frame-like structure. Such a frame-like structure can be hingedly mounted to the support structure 2 to allow the boom mounting member and the support mounting member to follow the boom's movement once engaged. Alternatively, the boom mounting member is hingedly mounted to the boom such that it can follow the boom's movement when engaged with the support mounting member.

[0058] The boom stabilization system is configured to use the bias stiffness of the bias element 14 to cause a limitation and / or reduction in the boom angle, so as to limit and / or reduce the boom angle at least when the boom angle exceeds a second predetermined boom angle threshold (e.g., corresponding to...). Figure 1c(α2 in the text) suppresses slack in the luffing cable 5 of the offshore crane 1, wherein the second predetermined boom angle threshold is greater than the first predetermined boom angle threshold (e.g., corresponding to α2 in the text). Figure 1b (α1 in the text).

[0059] The boom stabilization system can be essentially passive, meaning its boom stabilization function can operate independently of any active control (or at least without active control). Such a passive configuration greatly enhances the reliable and safe operation of the system, as opposed to active systems, which can be relatively sensitive to various failures in associated active components such as controllers or power supplies. In the case of a passive system, the bias stiffness of the bias element 14 can be designed to be large enough to stabilize the boom 3 under various conditions and at various boom angles, while still allowing the boom 3 to move, for example, via the actively driven luffing cable 5.

[0060] Alternatively, in some variations, the boom stabilization system may include one or more active elements and / or subsystems, for example, supplementing and thus not necessarily diminishing the passive functions described above. As an example, the bias element 14 or associated elements may be configured to actively extend the bias element 14 toward an extended position, for example, depending on a pressure threshold or other threshold, thereby applying an active reaction force to resist the swing of the boom 3, rather than merely passively damping or blocking. In other words, the bias stiffness of the bias element 14 can be variable, particularly controllable, thereby selectively achieving more or less bias. Such active behavior can not only further limit or prevent uncontrolled swing of the boom 3, but also thereby allow for the safe selection of even larger boom angles, such as boom angles up to approximately 90 degrees, as... Figure 6 Angle α3 is shown in the diagram. In particular, the active system can safely allow such a large angle with limited or no energy loss. In contrast, when such a large boom angle is allowed using a passive system (which is not necessarily excluded here), the drive luffing cable 5 may be less energy efficient due to the continuous drag caused by the relatively high non-variable bias stiffness, as explained above.

[0061] However, it is also conceivable to achieve variable (e.g., boom angle-dependent) offset stiffness in a passive boom stabilization system. In this case, passive offset elements with nonlinear stiffness can be applied, for example, formed by a set of offset sub-elements, each with different, for example, linear stiffness. When such different offset sub-elements are arranged in parallel, the sub-elements with higher stiffness can be arranged to engage at higher boom angles than the sub-elements with lower stiffness. Alternatively or additionally, when such different offset sub-elements are arranged in series, the resulting overall stiffness may be dominated by the sub-elements with lower stiffness at smaller boom angles, and by the sub-elements with higher stiffness at larger boom angles.

[0062] Therefore, this disclosure describes and illustrates an example of a boom stabilization system for an offshore crane, the system including a boom mounting component arranged for mounting to the boom of the offshore crane; a support mounting component mounted to a support structure for the offshore crane; wherein the boom mounting component includes a frame having at least one longitudinally extending chord; wherein the support mounting component includes a biasing element biased toward an extended position; wherein the boom mounting component and the support mounting component are configured to engage each other when the boom angle of the boom exceeds a first predetermined threshold; wherein the boom stabilization system is configured to use the bias stiffness of the biasing element to cause a limitation and / or reduction in the boom angle so as to suppress slack in the luffing cable of the offshore crane at least when the boom angle exceeds a second predetermined boom angle threshold, the second predetermined boom angle threshold being greater than the first predetermined boom angle threshold.

[0063] like Figure 6 As shown, the boom stabilization system advantageously enables the crane 3 to operate safely at boom angles up to approximately 90 degrees, particularly in suppressing slack in the luffing cable 5. For comparative illustrative purposes only, a slack luffing cable 5s... Figure 6 The dashed line indicates that the boom stabilization system can effectively suppress such slack, keeping the luffing cable 5 taut, thus continuing to contribute to the stability of the boom 3 even at such a relatively large boom angle α3.

[0064] like Figure 7 As shown in the top view, the boom stabilization system enables crane 3 (mounted here on vessel 36) to operate safely at a greater boom angle. The minimum reach distance of crane 3 can be effectively reduced, from a larger minimum reach distance 37a to a smaller minimum reach distance 37b, resulting in increased availability of the space around crane 3 (in this case, the deck space of vessel 36). Figure 7 The shaded area between 37a and 37b is shown in the middle.

[0065] For the purposes of clarity and concise description, features are described herein as part of the same or separate embodiments; however, it should be understood that the scope of the claims and disclosure may include embodiments having all or some of the described features. It will be understood that the illustrated embodiments have the same or similar components unless they are described differently.

[0066] Any reference numerals enclosed in parentheses in the claims should not be interpreted as limiting the claims. The term "comprising" does not exclude the presence of features or steps other than those listed in the claims. Furthermore, the terms "a" and "the" should not be interpreted as limited to "only one," but are used to mean "at least one," and do not exclude multiple. The fact that certain measures are referenced in mutually different claims does not mean that a combination of these measures is without advantage. Many variations will be apparent to those skilled in the art, provided they are included within the scope of the invention as defined in the appended claims.

Claims

1. A boom stabilization system for an offshore crane, comprising: - A boom mounting component, which is arranged to be mounted to the boom of the offshore crane; - Support mounting components, which are mounted to the support structure used for the offshore crane; - Wherein, one of the boom mounting component and the support mounting component includes a frame, the frame having at least one longitudinally extending chord; - Wherein, the other of the boom mounting component and the support mounting component includes a biasing element biased toward the extended position. - Wherein, the boom mounting component and the support mounting component are configured to engage with each other when the boom angle exceeds a first predetermined boom angle threshold. - Wherein, the boom stabilization system is configured to use the bias stiffness of the bias element to cause a limitation and / or reduction in the boom angle, so as to suppress slack in the luffing cable of the offshore crane at least when the boom angle exceeds a second predetermined boom angle threshold, the second predetermined boom angle threshold being greater than the first predetermined boom angle threshold.

2. The system according to claim 1, wherein, The boom mounting component includes a frame having the at least one longitudinally extending chord, wherein the support mounting component includes the biasing element biased toward the extended position.

3. The system according to claim 2, wherein, The distance from the at least one chord to the boom is greater near the base of the frame and smaller near the end of the frame.

4. The system according to claim 2 or 3, wherein, Viewed from the side, the frame is triangular relative to the boom, wherein at least one chord extends obliquely toward the boom.

5. The system according to any one of claims 2 to 4, wherein, The frame is permanently connected to the boom.

6. The system according to any one of claims 2 to 5, wherein, Along the length of the boom to which the boom mounting component is connected, the connection between the truss of the frame of the boom mounting component and the truss or chord of the boom is provided at multiple different locations in the axial direction, i.e., the longitudinal direction of the boom, and / or in the radial direction, i.e., transverse to the axial direction.

7. The system according to any one of the preceding claims, wherein, The support mounting components will be installed onto the support structure, and the boom, particularly at the base of the boom, will be pivotally connected to the support structure.

8. The system according to any one of the preceding claims, wherein, The first predetermined boom angle threshold is in the range of 40 degrees to 70 degrees, preferably about 60 degrees.

9. The system according to any one of the preceding claims further includes a support arm configured to hold the biasing element in a stationary position, wherein the biasing element has an angle relative to the support platform such that it can engage with the frame at or near an angle of 50 to 70 degrees, preferably about 60 degrees.

10. The system according to claim 9, wherein, The support arm has a U-shape to limit the lateral movement of the biasing element, particularly at the rest position.

11. The system according to any one of the preceding claims, wherein, The second predetermined boom angle threshold is in the range of 77 degrees to 89 degrees, preferably in the range of 80 degrees to 86 degrees, for example, about 83 degrees.

12. The system according to any one of the preceding claims, wherein, At least selectively and / or when the boom angle exceeds the second predetermined boom angle threshold, the bias stiffness of the biasing element is designed to maintain the boom angle at a variable lower limit applied to the boom angle by the luffing cable, wherein, in particular, the bias stiffness is designed with respect to the boom angle to dampen possible environmental disturbances acting on the boom.

13. The system according to any one of the preceding claims is configured to actively change the bias stiffness of the bias element, preferably using a hydraulic or pneumatic control circuit operably connected to the bias element.

14. The system according to any one of the preceding claims is configured to not cause a limitation and / or reduction in the boom angle when the boom angle does not exceed the second predetermined boom angle threshold.

15. The system according to any one of the preceding claims, comprising one or more sensors arranged to generate signals indicating that slack in the luffing cable may need to be suppressed in order to stabilize the offshore crane.

16. An offshore crane having a boom pivotally mounted to a supporting structure, wherein, The crane is provided with a boom stabilization system according to any one of the preceding claims, wherein the boom mounting component is mounted to the boom, and the support mounting component is mounted to the support structure, preferably pivotally mounted to the support structure.

17. The marine crane according to claim 16 when dependent on claim 2, wherein, The at least one longitudinally extending chord of the frame has an angle between approximately 1 degree and 30 degrees relative to the longitudinal direction of the boom.

18. The marine crane according to claim 16 or 17 when dependent on claim 2, wherein, The frame is installed on the boom at the lower 10% to 50% of the boom length, preferably at the lower 12% to 40% of the boom length.

19. The offshore crane according to claim 18, wherein, The upper end of the at least one longitudinal frame chord of the boom mounting component extends to about 10% to 50% of the boom length, preferably to about 30% of the boom length.

20. A vessel, such as a jack-up vessel, equipped with an offshore crane according to any one of the preceding claims.

21. The use of an offshore crane according to any one of claims 16 to 19 and / or a vessel according to claim 20 for lifting operations, particularly for heavy lifting operations at sea.

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