System for lifting a load, in particular for lifting a load in the presence of a relative movement due to swell

Abstract

The present invention relates to a system (1) for lifting a load (C), in particular for lifting a load (C) in the presence of a relative movement due to swell. The lifting system (1) comprises at least one lifting point (1a) which has a chassis (2) comprising: - controlled braking means (6), cooperating with a movable block of pulleys (52), and - manoeuvring means (8) which cooperate with said movable block of pulleys (52) and which are configured to restore a potential energy to said movable block of pulleys (52), so as to tend to increase said distance dimension (D).

Description

[0001] System for lifting a package, in particular for lifting a package in the presence of relative movement due to waves

[0002] Technical field of the invention

[0003] The present invention relates to the technical field of package lifting systems, in particular for lifting a package in the presence of relative movement due to swell.

[0004] State of the art

[0005] In the field of lifting at sea, the main difficulty encountered concerns the relative speeds between the reference frame of the lifting equipment and the reference frame on which the package to be recovered is placed or must be placed.

[0006] Traditionally, offshore lifting systems have high lifting speeds to allow experienced crane operators to follow the movements of the swell by turning and unturning actions.

[0007] The package is initially removed from the deck by always leaving slack in the lifting straps, then by taking up the slack during the package's ascent phase in order to accompany the natural movement of the package imposed by the swell.

[0008] To assist crane operators, there are now cranes with active wave compensation that automatically compensate for relative movements between the two reference frames.

[0009] This active compensation aims to keep the cables taut at all times so as to prevent slack and thus avoid a slack take-up shock.

[0010] However, in practice, this technical solution is heavy, expensive and very dependent on sensors.

[0011] Another solution consists of cranes with shock absorbers: a shock absorber device, generally hydraulic, filters as dynamically as possible any force exceeding a certain preset threshold.

[0012] However, this type of solution is not able to recover significant shocks due to very high relative speeds.

[0013] In view of the above, it is interesting to propose alternative solutions suitable for lifting packages in the presence of relative movement due to swell.

[0014] In particular, it would be interesting to propose a solution that does not only aim to deal with the effects of shocks but to make them impossible, or at least to limit them.

[0015] Presentation of the invention

[0016] In order to propose another solution adapted to the compensation of the swell, the present invention proposes a system for lifting a package, in particular for lifting a package in the presence of a relative movement due to the swell. The lifting system comprises at least one lifting point which comprises a frame comprising:

[0017] - at least one lifting cable associated with:

[0018] -- a winch, for maneuvering the said lifting cable, in turns and out turns,

[0019] -- hauling means comprising:

[0020] - a fixed block of sheaves, secured to said chassis, and

[0021] - a movable block of sheaves, cooperating with said chassis by means of sliding means defining a degree of freedom in translation perpendicular to the axis of rotation of said sheaves, the distance dimension of said movable block of sheaves relative to said fixed block of sheaves being variable,

[0022] - controlled braking means, cooperating with said mobile block of sheave(s) and controllable between two bistable configurations:

[0023] -- an inactive configuration, in which said controlled braking means allow free translation of said mobile block of sheave(s) according to said degree of freedom in translation, in particular adapted to passive compensation of swell, and

[0024] -- an active configuration, in which said controlled braking means allow the moving block of sheave(s) to move in a single direction according to said degree of freedom in translation, corresponding to an increase in said distance dimension, and

[0025] - control means for controlling said winch and said controlled braking means, in particular during the launching or recovery operation of said package,

[0026] - operating means which cooperate with said mobile block of sheave(s) and which are configured to restore potential energy, advantageously elastic potential energy or gravitational potential energy, to said mobile block of sheave(s) so as, in the inactive configuration, to tend to maintain a constant tension in said at least one lifting cable and, in the active configuration, to tend to increase said distance dimension.

[0027] The present invention thus proposes a technical solution using the swell:

[0028] - half the time, the movement imposed on the package by the environment is an ascent which facilitates recovery, and

[0029] - the other half of the time is a descent of the package which facilitates launching or depositing on the other reference point.

[0030] This synchronization also has the advantage of reducing the speeds:

[0031] - upon recovery, this results in a minimized dynamic amplification coefficient, and

[0032] - when launching, or depositing on another reference point, this limits the accelerations felt by the package. Instead of managing shocks when the lifting cables are tensioned, the lifting system according to the invention ensures passive self-tensioning and, advantageously, load transfer at wave crest (where the relative speed is by definition zero).

[0033] The speeds of tracking relative movements are ensured by maneuvering means configured to restore potential energy, which make it possible to take up or give slack at very high speeds compared to what is available to the winch.

[0034] This approach significantly reduces the power requirement for the winch. This solution is therefore very efficient and very economical.

[0035] The bistable controlled braking means also advantageously allow:

[0036] - lifting at very moderate maximum speed compared to other prior art solutions (low power requirement),

[0037] - passive compensation of relative movements by keeping the lifting cables taut at a relatively low value, with a high speed capacity for tracking relative movements.

[0038] These controlled, bistable braking means advantageously allow switching from one mode to another safely and almost instantly in relation to the phenomena involved.

[0039] Other non-limiting and advantageous characteristics of the product in accordance with the invention, taken individually or in all technically possible combinations, are as follows:

[0040] - the control means are configured to, on the one hand, prevent a switch from said active configuration to said inactive configuration when the traction on said cable is greater than a determined minimum threshold, in particular when said package is suspended from said cable, and on the other hand, authorize a switch from said active configuration to said inactive configuration when the traction on said cable is less than a determined minimum threshold, in particular when said package rests on a reference frame;

[0041] - for lifting a package in the presence of relative movement due to swell, the control means are configured to implement a lifting method comprising the following operations:

[0042] (i) during an operation to launch said package to a new repository:

[0043] - a step of suspending said package from said lifting cable, in which said controlled braking means are in active configuration and the mobile block of sheave(s) is in an average position centered on an available stroke,

[0044] - a step of lowering said package near the highest wave crests of the swell, - when the package is placed on a wave crest, a step of deflecting, preferably to come tangent to said wave crest,

[0045] - when said package transfers its weight from said lifting cable to said new reference system, a step of switching said braking means to the inactive configuration so that said lifting system ensures passive compensation for the swell, and / or

[0046] (ii) during a recovery operation of said package, starting from an inactive configuration in which said lifting system provides passive compensation for the swell,

[0047] - if said package is in an upward movement, a step of transition to said active configuration so that said mobile block of sheave(s) continues its movement by increasing said distance dimension, this up to a wave crest where said mobile block of sheave(s) is blocked in translation, or

[0048] - if said package is in a downward movement, a step of maintaining the controlled braking means in the inactive configuration then a step of switching to said active configuration at the start of said upward movement of said package;

[0049] - the sliding means comprise a sliding spar which carries the movable block of sheave(s), which extends coaxially with said degree of freedom in translation and which cooperates with said controlled braking means;

[0050] - the operating means, configured to restore elastic potential energy or gravitational potential energy to said mobile block of sheaves, consist of a spring member or a counterweight;

[0051] - the control means comprise a centering module which, in the inactive configuration of the controlled braking means, is configured to control said winch so as to position the mobile block of sheave(s) in a centered position, advantageously an average position centered on an available stroke, preferably prior to a lift preceding a launch and / or in the passive swell compensation phase; preferably, said centering module consists of a slow centering module which, in the inactive configuration of the controlled braking means, cooperates with means for instantaneous and averaged measurement of the position of said mobile block of sheave(s) over a period of time and which is configured to control said winch when the average position of said mobile block of sheave(s) reaches an actuation threshold on said degree of freedom in translation;

[0052] - the control means comprise an end-of-travel safety module which is configured to actuate said winch when said movable block of sheave(s) reaches an end-of-travel threshold on said translational degree of freedom, so as to actively push said movable block of sheave(s) back relative to said end-of-travel threshold;- the control means comprise an automatic recovery module and / or an automatic launch module, configured to automatically control said winch and said controlled braking means during a recovery operation and / or a launch operation of said package, which automatic recovery module and / or automatic launch module is preferably associated with at least one measurement sensor configured to measure the relative vertical distance between a reference frame of said chassis and a destination reference frame, for example in the case where the average distance between the reference frame of said chassis and the destination reference frame is not known or variable;

[0053] - the lifting system consists of a crane with a lifting point, the chassis of which includes an upright and a boom, and a gantry with at least two lifting points.

[0054] The present invention also relates to a method for lifting a package, in particular for lifting a package in the presence of relative movement due to swell, by implementing a lifting system according to the invention.

[0055] This lifting process includes the following operations:

[0056] (i) during an operation to launch said package to a new repository:

[0057] - a step of suspending said package from said lifting cable, in which said controlled braking means are in active configuration and the mobile block of sheave(s) is in an average position centered on an available stroke,

[0058] - a stage of lowering said package near the highest wave crests of the swell,

[0059] - when the package is placed on a wave crest, a step deviates, preferably to come tangent to said wave crest,

[0060] - when said package transfers its weight from said lifting cable to said new reference system, a step of switching said braking means to the inactive configuration so that said lifting system ensures passive compensation for the swell, and / or

[0061] (ii) during a recovery operation of said package, starting from an inactive configuration in which said lifting system provides passive compensation for the swell,

[0062] - if said package is in an upward movement, a step of transition to said active configuration so that said mobile block of sheave(s) continues its movement by increasing said distance dimension, this up to a wave crest where said mobile block of sheave(s) is blocked in translation, or

[0063] - if said package is in a downward movement, a step of maintaining the controlled braking means in the inactive configuration then a step of switching to said active configuration at the start of said upward movement of said package. Preferably, in passive compensation for the swell, said method comprises a step of controlling said winch to tend to maintain the mobile block of sheave(s) in an average position.

[0064] Of course, the various features, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive.

[0065] Detailed description of the invention

[0066] In addition, various other characteristics of the invention emerge from the appended description given with reference to the drawings which illustrate non-limiting embodiments of the invention and where:

[0067] [Fig. 1] is a general and perspective view of a lifting system according to the invention, in the form of a crane comprising a lifting point;

[0068] [Fig. 2] is a general and perspective view of the lifting system according to Figure 1, in which the chassis is hidden;

[0069] [Fig. 3] is a general and perspective view of the lifting system according to another embodiment in which the sliding means define a degree of freedom in horizontal translation and the maneuvering means comprise an offset counterweight;

[0070] [Fig. 4] is a general and perspective view of a lifting system according to a variant of figure 3, which differs by the arrangement of the mobile block of sheave(s) on the sliding beam.

[0071] It should be noted that, in these figures, the structural and / or functional elements common to the different variants may have the same references.

[0072] The present invention thus relates to a lifting system 1 for lifting a package C.

[0073] This lifting system 1 is particularly suitable for lifting a package C in the presence of relative movement due to swell, in particular for off-shore or sea applications.

[0074] More generally, the lifting system 1, for example a crane or a gantry, is suitable for handling a package C between two reference frames which exhibit relative movement due to the swell.

[0075] The term "swell" refers to the oscillation of the sea surface, particularly due to waves.

[0076] Generally speaking, the highest point of a wave is called the crest; the lowest point is called the trough. The size of the wave is determined by the distance between the crest and the trough. The period is the time elapsed between two crests.

[0077] As discussed below, a "highest peak" advantageously corresponds to the highest peak during a period of time. By "package" is meant any object (or load) intended to be handled by the lifting system 1. Such a package C may have various shapes and sizes, for example a basket for transhipment of people (figure 1 for example), a container or a boat.

[0078] By "reference points" we advantageously include any surface intended to receive package C, in particular an origin reference point and a destination reference point, for example a ship, a platform, the surface of the water.

[0079] Generally speaking and according to the invention, the lifting system 1 comprises at least one lifting point 1a which comprises a chassis 2 comprising:

[0080] - at least one lifting cable 3 associated with a winch 4 and hauling means 5,

[0081] - controlled braking means 6, cooperating with the hauling means 5,

[0082] - control means 7, for controlling the winch 4 and the controlled braking means 6, in particular during the operation of launching or recovering the package C, and

[0083] - maneuvering means 8 which cooperate with the hauling means 5 and which are configured to restore potential energy, in particular to ensure passive compensation for the swell.

[0084] Lifting cable

[0085] The 3 lifting cable is classic in itself.

[0086] It consists, for example, of a lifting cable made of synthetic material or metallic material.

[0087] This lifting cable 3 is capable of undergoing a tensile force which is generated by the package C suspended from said lifting cable 3.

[0088] In other words, package C is intended to be suspended from the end of the lifting cable 3. When suspended, this package C is thus intended to exert a tensile force, or a traction force, on the lifting cable 3.

[0089] By "suspended" we mean a configuration in which package C is located high up and at a distance from the reference points.

[0090] This lifting cable 3 cooperates with the winch 4 and with the hauling means 5.

[0091] Winch

[0092] Winch 4 is classic in itself.

[0093] This winch 4 is suitable for maneuvering the lifting cable 3:

[0094] - on a turn, to exert a force on the lifting cable 3 by winding it onto the winch 4, and advantageously to generate a rise of the package C from a reference point, and

[0095] - deviates, to release the force on the lifting cable 3 by unwinding from the winch 4, and advantageously to generate a descent of the package C towards a reference point.

[0096] Hauling means The hauling means 5 include:

[0097] - a fixed block of sheaves 51, secured to the chassis 2, and

[0098] - a mobile block of sheave(s) 52, cooperating with the chassis 2 by means of sliding means 53.

[0099] In particular, the mobile block of sheaves 52 preferably comprises a single sheave 52 or several two sheaves 52.

[0100] Preferably, the sheaves 51, 52 (also called “pulleys”) have respective axes of rotation 5T, 52', which extend in parallel planes and which define between them a distance dimension D.

[0101] The distance dimension D is advantageously measured according to a degree of freedom in translation T, described below.

[0102] The sliding means 53 define a degree of freedom in translation T for the mobile block of sheave(s) 52.

[0103] This degree of freedom in translation T extends perpendicularly to the axis of rotation 51', 52' of the sheaves 51, 52.

[0104] Generally speaking, this degree of freedom in translation T can be oriented vertically (notably figures 1 or 2) or horizontally (notably figures 3 and 4).

[0105] As developed subsequently, the aforementioned distance dimension D (corresponds to the distance between the rotation axis 52' of the mobile block of sheaves 52 and the rotation axis 5T of the fixed block of sheaves 51, measured on the degree of freedom in translation T) is variable.

[0106] For example, the possible travel of the mobile block of sheave(s) 52, depending on the degree of freedom in translation T, is for example 1 m to 2 m, for example 1.5 m (i.e. 6 m at the hook).

[0107] Generally, the sliding means 53 comprise, for example, a sliding spar 531 (also called a “rod”), forming a slide, which carries the movable block of sheave(s) 52.

[0108] Where appropriate, the sliding spar 531 extends coaxially with the translational degree of freedom T. This sliding spar 531 is movable in a direction coaxial with said translational degree of freedom T.

[0109] The movable block of sheave(s) is advantageously carried at one of the ends 531a, 531b of the sliding beam 531.

[0110] As developed below, this sliding beam 531 cooperates with the controlled braking means 6, so as to control the movement of the mobile block of sheave(s) 52.

[0111] Controlled braking means

[0112] The controlled braking means 6 cooperate with the mobile block of sheave(s) 52, where appropriate via the sliding beam 531. These controlled braking means 6 can be controlled between two bistable configurations: an inactive configuration and an active configuration.

[0113] According to the inactive configuration, the controlled braking means 6 allow free translation of the mobile block of sheave(s) 52 according to the degree of freedom in translation T.

[0114] As developed subsequently, such an inactive configuration is particularly suitable for passive swell compensation. In this case, the movable block of sheave(s) 52 (and possibly the associated sliding spar 531) can oscillate passively, particularly as a function of the relative movement between the two reference frames.

[0115] According to the active configuration, the controlled braking means 6 allow the mobile block of sheave(s) 52 to move in a single direction according to the degree of freedom in translation T, corresponding to an increase in the aforementioned distance dimension D.

[0116] In other words, the controlled braking means 6 are structured to:

[0117] - authorize a path of the mobile block of sheave(s) 52 in a first direction according to the degree of freedom in translation T, corresponding to an increase in the distance dimension D, and

[0118] - prevent the moving block of sheave(s) 52 from moving in a second direction according to the degree of freedom in translation T, corresponding to a reduction in the distance dimension D.

[0119] Such an active configuration is particularly interesting for allowing the continuation of a movement by increasing the distance rating D, for example when the package C follows an upward trajectory to a wave crest.

[0120] For example, the controlled braking means 6 comprise mechanical, mobile means, cooperating with the sliding spar 531 so as to define the active and inactive configurations.

[0121] Means of ordering

[0122] The control means 7 are configured for controlling the winch 4 and the controlled braking means 6, in particular during the operation of launching or recovering the package C.

[0123] Such control means 7 comprise, for example, a computer program implemented by a computer, for example in the form of an industrial programmable logic controller. This computer program advantageously comprises instructions which, when the program is executed by a computer, cause the latter to control the winch 4 and / or the controlled braking means 6 (preferably according to an algorithm).

[0124] According to a preferred embodiment, the control means 7 are configured to prevent the controlled braking means 6 from switching from the active configuration to the inactive configuration when the traction on the lifting cable 3 is greater than a determined minimum threshold. In this sense, preferably, the control means 7 are configured to prevent the controlled braking means 6 from switching from the active configuration to the inactive configuration when this package C is suspended from said cable.

[0125] Still according to this preferred embodiment, the control means 7 are configured to authorize a switchover of the controlled braking means 6, from the active configuration to the inactive configuration, when the traction on said cable is less than a determined minimum threshold.

[0126] In this sense, preferably, the control means 7 are configured to allow a switch of the controlled braking means 6, towards the inactive configuration, when the package C rests on a reference frame.

[0127] By "minimum threshold" is meant, for example, a tensile force on the lifting cable 3 which is greater than the maximum force exerted by the lifting system 1, for taking up slack.

[0128] Again according to a definition, the minimum threshold advantageously corresponds to a traction value exerted by the lifting cable 3 when the package C rests on a reference frame.

[0129] More generally, for lifting a package C in the presence of a relative movement due to the swell and during an operation of launching the package C towards a new reference point, the control means 7 are configured to implement a lifting method which comprises the following operations:

[0130] - a step of suspending the package C from the lifting cable 3, in which the controlled braking means 6 are in active configuration and the mobile block of sheave(s) 52 is in an average position centered on an available stroke,

[0131] - a stage of descent of package C near the highest wave crests of the swell,

[0132] - when package C is placed on a wave crest, a step deviates, preferably to come tangent to said wave crest,

[0133] - when said package C transfers its weight from the lifting cable 3 to the new reference frame, a step of switching the controlled braking means 6 to the inactive configuration so that the lifting system 1 ensures passive compensation for the swell.

[0134] For lifting a package C in the presence of a relative movement due to the swell and starting from an inactive configuration in which said lifting system 1 ensures passive compensation of the swell, the control means 7 are configured to implement a lifting method which comprises the following operations:

[0135] - if said package C is in an upward movement, a step of passing the controlled braking means 6 towards said active configuration so that said mobile block of sheaves 52 continues its movement by increasing said distance dimension D, this up to a wave crest where said mobile block of sheaves 52 is blocked in translation, or

[0136] - if said package C is in a downward movement, a step of maintaining the controlled braking means 6 in said inactive configuration then a step of switching to said active configuration at the start of an upward movement of said package C and an increase in said distance dimension D.

[0137] Still according to the invention, the control means 7 advantageously comprise a centering module 71 which, in the inactive configuration of the controlled braking means 6, is configured to control the winch 4 so as to position the mobile block of sheave(s) 52 in a centered position, advantageously an average position centered on an available stroke.

[0138] This centering module 71 advantageously comprises an initial centering module 71a, which aims to position the mobile block of sheaves 52 in a centered position prior to an operation of launching the package C from a reference frame.

[0139] The centering module 71 also advantageously comprises a slow centering module 71b configured so that, in the inactive configuration of the controlled braking means 6, it tends to maintain the mobile block of sheave(s) 52 in a centered position, advantageously an average position centered on an available stroke.

[0140] Preferably, the slow centering module 71b cooperates with means for instantaneous and averaged measurement of the position of the mobile block of sheave(s) 52 over a period of time (period of 30 s to 90 s for example), in particular when the controlled braking means 6 are in the inactive configuration.

[0141] The means for instantaneous and averaged measurement of the position of the mobile block of sheave(s) 52 consist, for example, of a cable or laser position sensor.

[0142] This slow centering module 71b is configured to control the winch 4 (turning and unturning) when the average position of said mobile block of sheave(s) 52 reaches an actuation threshold according to the degree of freedom in translation T.

[0143] For example, the actuation threshold is 3% to 7%, in length relative to the total stroke, depending on the translational degree of freedom T.

[0144] Generally, the control means 7 advantageously comprise an end-of-travel safety module 72 (also called a dynamic end-of-travel avoidance module).

[0145] This end-of-travel safety module 72 is configured to actuate the winch 4 (turns and deturns) when the movable block of sheave(s) 52 reaches an end-of-travel threshold on the translational degree of freedom T, so as to actively push said movable block of sheave(s) 52 back relative to said end-of-travel threshold. The purpose of this end-of-travel safety module 72 is to prevent the movable block of sheave(s) 52 from reaching a mechanical end-of-travel position.

[0146] For example, this end-of-stroke threshold is 5 to 15%, relative to the total stroke.

[0147] Preferably, an increasing speed order is imposed by this end-of-travel safety module 72 to prevent the mobile block of sheave(s) 52 from reaching the end of the travel. Preferably, this speed increases towards the maximum available speed, under the action of the motor and its frequency converter.

[0148] Still according to the invention, the control means 7 advantageously comprise an automatic recovery module 73 and / or an automatic launch module 74, configured to automatically control the winch 4 and the controlled braking means 6 during the recovery operation and / or the launch operation of the package C.

[0149] The automatic recovery module 73 and / or the automatic launch module 74 is preferably associated with at least one measurement sensor 75 (for example a laser or a radar, illustrated in FIG. 1) configured to measure the vertical relative distance between a frame of reference of the chassis 2 and a destination frame of reference, for example in the case where the average distance between the frame of reference of the chassis 2 and the destination frame of reference is not known or variable.

[0150] Preferably, said at least one measuring sensor 75 makes it possible to measure the relative vertical position of the destination reference frame with respect to the lifting system 1, among:

[0151] - the average position,

[0152] - the highest position,

[0153] - the lowest position.

[0154] From these measurements, it is possible to determine:

[0155] - the instantaneous vertical speed (by derivation All / At),

[0156] - the maximum speed uphill and downhill (over the last 1 to 5 minutes for example),

[0157] - the average absolute speed (over the last 1 to 5 minutes, for example),

[0158] - the length to be unwound by the winch 4 to obtain the centering of the mobile block of sheave(s) 52 in the theoretical centered position.

[0159] In practice, the automatic launch module 74 is advantageously executed at the most opportune moment, for example so that the package C is deposited on a wave crest, at the start of descent, to minimize the load transfer acceleration felt by the package C.

[0160] Preferably, the automatic launch module 74 is executed in the middle of a wave rise. The automatic recovery module 73 can be executed at any time. In particular, the automatic recovery module 73 waits for the start of a rising edge to transmit the control instruction for the controlled braking means 6 in active configuration.

[0161] Means of maneuver

[0162] The operating means 8 cooperate with said mobile block of sheaves 52.

[0163] These maneuvering means 8 are configured to restore potential energy to the mobile block of sheaves 52 so that:

[0164] - in inactive configuration, to tend to maintain a constant tension in said at least one lifting cable, and

[0165] - in active configuration, tend to increase the distance rating D.

[0166] More precisely, these maneuvering means 8 are configured to accumulate the potential energy coming from the mobile block of sheaves 52 when the distance dimension D decreases.

[0167] In other words, the operating means 8 are intended to restore a restoring force, corresponding to the restored potential energy.

[0168] The operating means 8 are adapted to maintain sufficient tension to tension said at least one lifting cable 3, in the inactive configuration and in the active configuration of the controlled braking means 6.

[0169] Without being limiting, this tension advantageously depends on the maximum length of said at least one lifting cable 3 which hangs during passive compensation of the hoe, on the linear density of said at least one lifting cable 3 and on the value of the destabilizing forces (for example winds, accelerations of the reference frames) which tend to cause said at least one lifting cable 3 to come out of its / their ideal natural position(s) of straightness between the sheaves 51, 52 and the fixed points.

[0170] Preferably, this voltage must also be greater than the force exerted by the controlled braking means 6 in the active configuration, in the direction of increasing the distance dimension D.

[0171] By "potential energy" we preferably include:

[0172] - elastic potential energy, for example in the form of a spring member (not shown), advantageously mechanical or pneumatic, and / or

[0173] - gravitational potential energy, for example in the form of a counterweight.

[0174] For example, a spring organ accumulates elastic potential energy (for example by being stressed) when the distance dimension D decreases.

[0175] For example, a counterweight accumulates gravitational potential energy (e.g. by its displacement in height) when the distance dimension D decreases.

[0176] In general, the counterweight may possibly be formed by: - ​​the sliding spar 531, directly, in particular in the case of a vertical translational degree of freedom T (figure 2), and / or

[0177] - an offset counterweight 85, suspended from one end of the sliding spar 531 (for example at a proximal end 531b, on the side of the winch 4), for example via a cable / pulley assembly, and advantageously exerting a traction force on the sliding spar 531.

[0178] Conversely, the potential energy is here restored in the form of a restoring force, by the increase in the distance dimension D.

[0179] Generally speaking and taking into account the operating means 8 exerting potential energy on the mobile block of sheave(s) 52, the distance dimension D is notably variable depending on the traction force exerted by the package C via the lifting cable 3:

[0180] - the distance rating D tends to increase when the traction force exerted by the package C decreases, and

[0181] - the distance dimension D tends to decrease when the traction force exerted by the package C increases.

[0182] In other words, the movements of the mobile block of sheave(s) 52 are determined by:

[0183] - the tensile force exerted by package C on lifting cable 3,

[0184] - the restoring force corresponding to the potential energy restored by the operating means 8, and

[0185] - and where applicable, the turning and de-turning maneuvers carried out on the lifting cable 3 via the winch 4.

[0186] Methods of implementation

[0187] In this case, as illustrated in the figures, the lifting system 1 consists here of a crane comprising a lifting point 1a.

[0188] In this case, the frame 2 has an upright 2a and an arrow 2b.

[0189] Generally speaking, the winch 4, the hauling means 5, the controlled braking means 6 and the maneuvering means 8 are advantageously carried by the chassis 2.

[0190] According to the embodiment illustrated in Figures 1 and 2, the winch 4 and the hauling means 5 are carried by the upright 2a. In particular, the sliding means 53 define a degree of freedom in vertical translation T, along this upright 2a.

[0191] The operating means 8, cooperating with said mobile block of sheave(s) 52, consist here of gravitational potential energy, for example in the form of a counterweight formed directly by the sliding beam 531 oriented vertically, the upper end of which carries the mobile block of sheave(s) 52.

[0192] The sliding spar 531 cooperates with the controlled braking means 6 which are carried by the upright 2a. The operating means 8 may also comprise a remote counterweight (not shown), exerting downward traction on the sliding spar 531.

[0193] According to embodiments illustrated in Figures 3 and 4, the winch 4 and the hauling means 5 are carried by the boom 2b. In particular, the sliding means 53 define a degree of freedom in horizontal translation T, along the boom 2b.

[0194] The operating means 8, cooperating with said movable block of sheave(s) 52, consist here of gravitational potential energy, for example in the form of an offset counterweight 85 intended to exert a traction force on the horizontally oriented sliding beam 531, one of the ends 531a, 531b of which carries the movable block of sheave(s) 52.

[0195] The sliding spar 531 cooperates with the controlled braking means 6 which are carried by the arrow 2b.

[0196] The embodiments illustrated in Figures 3 and 4 differ in particular by the arrangement of the movable block of sheave(s) 52 on the sliding beam 531.

[0197] According to the embodiment illustrated in Figure 3, the movable block of sheave(s) 52 is carried by a distal end 531a of the sliding spar 531 (at a distance from the winch 4) and the offset counterweight 85 is secured to a proximal end 531b of the sliding spar 531 (on the side of the winch 4).

[0198] In other words, the mobile block of sheave(s) 52 and the offset counterweight 85 are secured to ends 531a, 531b of the sliding spar 531 which are located on either side of the controlled braking means 6.

[0199] Alternatively, according to the embodiment illustrated in Figure 4, the mobile block of sheave(s) 52 and the offset counterweight 85 are secured to the same proximal end 531b of the sliding spar 531 (on the side of the winch 4).

[0200] In other words, the mobile block of sheave(s) 52 and the offset counterweight 85 are secured to the same end 531b of the sliding spar 531, which is located on one side only of the controlled braking means 6.

[0201] This latter embodiment, according to figure 4, has the advantage of being relatively compact.

[0202] Alternatively and not shown, the lifting system 1 may also consist of a gantry comprising at least two lifting points 1a according to the invention.

[0203] Lifting process

[0204] Generally, in passive swell compensation, the controlled braking means 6 are in the inactive configuration. The lifting system 1 and the package C are based on two different reference systems.

[0205] The mobile block of sheave(s) 52 is then subjected to two inverse forces:

[0206] - the tensile force exerted by the package C via the lifting cable 3, and - the restoring force corresponding to the potential energy restored by the operating means 8.

[0207] In this case, if the height difference between the reference frames decreases (for example a wave raises package C), the tension in the lifting cable 3 decreases and, naturally, the distance dimension D increases under the action of the operating means 8.

[0208] Conversely, if the height difference between the reference frames increases (for example a wave causes package C to descend), the tension in the lifting cable 3 increases and, naturally, the distance dimension D decreases.

[0209] Passively, the lifting cable 3 is advantageously maintained at an average tension (namely preferably a force exerted by the maneuvering means 8 divided by the number of strands of the hauling means 5).

[0210] Still generally, in passive compensation of the swell, the method comprises a step of controlling the winch 4 to split to maintain the mobile block of sheave(s) 52 in an average position.

[0211] This centering of the mobile block of sheave(s) 52 is ensured here by the aforementioned slow centering module 71b.

[0212] In practice, if an actuation threshold is reached by increasing the distance dimension D, the slow centering module 71b controls the winch 4 in a turn so as to tend to bring back, advantageously on average, the mobile block of sheave(s) 52 into a central position.

[0213] Conversely, if an actuation threshold is reached by reducing the distance dimension D, the slow centering module 71b controls the winch 4 in such a way as to tend to bring back, advantageously on average, the mobile block of sheave(s) 52 into a central position.

[0214] Generally, if an end-of-travel threshold is reached, the end-of-travel safety module 72 is executed to actuate the winch 4, turning or deflecting as appropriate, so as to actively push the mobile block of sheave(s) 52 back relative to said end-of-travel threshold.

[0215] The present invention also relates to the method for lifting a package C, in particular for lifting a package C in the presence of a relative movement due to swell, by implementing a lifting system 1 according to the invention.

[0216] During an operation to launch package C to a new reference point, the lifting process advantageously includes the following operations:

[0217] - a step of suspending the package C from the lifting cable 3, in which the controlled braking means 6 are in active configuration and the mobile block of sheave(s) 52 is in an average position centered on an available stroke, - a step of lowering the package C near the highest wave crests of the swell,

[0218] - when package C is placed on a wave crest, a step deviates, preferably to come tangent to said wave crest,

[0219] - when said package C transfers its weight from the lifting cable 3 to the new reference frame, a step of switching the controlled braking means 6 to the inactive configuration so that said lifting system 1 ensures passive compensation for the swell.

[0220] This launching operation can be provided by the automatic launching module 74.

[0221] Preferably, before the launch operation (when the package is still on the initial reference frame), the initial centering module 71a ensures centering of the mobile block of sheaves 52 in order to benefit from a safety margin. Such a procedure thus ensures self-centering of the mobile block of sheaves 52 before the launch operations.

[0222] To this end, the following operations are advantageously implemented:

[0223] - switching the controlled braking means 6 to inactive configuration,

[0224] - give winch 4 a direction to turn or deviate, to the middle position,

[0225] - switching the controlled braking means 6 to active configuration.

[0226] At the end of this centering, if the operator lifts package C, the mobile block of sheave(s) 52 is centered for safe launching.

[0227] During an operation to recover said package C, starting from an inactive configuration in which said lifting system 1 provides passive compensation for the swell, the lifting method advantageously comprises a step of transitioning to the active configuration.

[0228] This recovery operation can be performed by the automatic recovery module 73.

[0229] If package C is in an upward movement, the mobile block of sheave(s) 52 continues its movement by increasing the distance dimension D, this until a wave crest where the mobile block of sheave(s) 52 is blocked in translation.

[0230] Once the wave crest is reached, the controlled braking means 6 prevent the distance D from decreasing. The start of the descent of the next wave then gradually places the package C on the lifting cable 3.

[0231] Conversely, if said package C is in a downward movement, the method comprises a step of maintaining the controlled braking means 6 in the inactive configuration, before a step of switching to said active configuration at the start of an upward movement of the package C. At the end of these operations, the package C hangs at the end of the lifting cable 3, above and at a distance from a reference frame.

[0232] If a wave crest arrives later, package C rises again and locks at a new maximum level. When the controlled braking means 6 are in active configuration, an operator can turn to begin extracting package C from its original reference frame.

[0233] Advantageously, in the event of a power failure:

[0234] - in compensation for the swell: lifting system 1 being passive, it continues to operate normally; - in lifting: if package C is close to a reference point and if this reference point comes back into contact with package C, then the latter rises to the new highest point.

[0235] Of course, various other modifications may be made to the invention within the scope of the appended claims.

Claims

Claims

1. Lifting system (1) for a package (C), in particular for lifting a package (C) in the presence of relative movement due to swell, which lifting system (1) comprises at least one lifting point (1a) which comprises a frame (2) comprising: - at least one lifting cable (3) associated with: -- a winch (4), for maneuvering said lifting cable (3), in turns and unturns, -- hauling means (5) comprising: - a fixed block of sheaves (51), secured to said chassis (2), and - a mobile block of sheaves (52), cooperating with said chassis (2) by means of sliding means (53) defining a degree of freedom in translation (T) perpendicular to the axis of rotation of said blocks of sheaves (51, 52), the distance dimension (D) of said mobile block of sheaves (52) relative to said fixed block of sheaves (51) being variable, - controlled braking means (6), cooperating with said mobile block of sheave(s) (52) and controllable between two bistable configurations: -- an inactive configuration, in which said controlled braking means (6) allow free translation of said mobile block of sheave(s) (52) according to said degree of freedom in translation (T), in particular adapted to passive compensation of swell, and -- an active configuration, in which said controlled braking means (6) allow the mobile block of sheave(s) (52) to move in a single direction according to said degree of freedom in translation (T), corresponding to an increase in said distance dimension (D), and - control means (7), for controlling said winch (4) and said controlled braking means (6), in particular during the operation of launching or recovering said package (C), - operating means (8) which cooperate with said mobile block of sheave(s) (52) and which are configured to restore potential energy to said mobile block of sheave(s) (52) so as, in the inactive configuration, to tend to maintain a constant tension in said at least one lifting cable (3) and, in the active configuration, to tend to increase said distance dimension (D).

2. Lifting system (1), according to claim 1, characterized in that the control means (7) are configured to: - preventing a switch from said active configuration to said inactive configuration when the traction on said lifting cable (3) is greater than a determined minimum threshold, in particular when said package (C) is suspended from said lifting cable (3), and - authorize a switch from said active configuration to said inactive configuration when the traction on said lifting cable (3) is less than a determined minimum threshold, in particular when said package (C) rests on a reference frame.

3. Lifting system (1), according to any one of claims 1 or 2, in particular for lifting a package (C) in the presence of a relative movement due to swell, characterized in that the control means (7) are configured to implement a lifting method which comprises the following operations: (i) during an operation to launch said package (C) towards a new repository: - a step of suspending said package (C) from said lifting cable (3), in which said controlled braking means (6) are in active configuration and the mobile block of sheave(s) (52) is in an average position centered on an available stroke, - a step of lowering said package (C) near the highest wave crests of the swell, - when the package (C) is placed on a wave crest, a step deviates, preferably to come tangent to said wave crest, - when said package (C) transfers its weight from said lifting cable (3) to said new reference system, a step of switching said controlled braking means (6) to inactive configuration so that said lifting system (1) ensures passive compensation for the swell, and / or (ii) during a recovery operation of said package (C), starting from an inactive configuration in which said lifting system (1) provides passive compensation for the swell: - if said package (C) is in an upward movement, a step of passing towards said active configuration so that said mobile block of sheave(s) (52) continues its movement by increasing said distance dimension (D), this up to a wave crest where said mobile block of sheave(s) (52) is blocked in translation, or - if said package (C) is in a downward movement, a step of maintaining the controlled braking means (6) in the inactive configuration then a step of switching to said active configuration at the start of said upward movement of said package (C).

4. Lifting system (1), according to any one of claims 1 to 3, characterized in that the sliding means (53) comprise a sliding spar (531) which carries the movable block of sheave(s) (52), which extends coaxially with said degree of freedom in translation (T) and which cooperates with said controlled braking means (6).

5. Lifting system (1), according to any one of claims 1 to 4, characterized in that the operating means (8), configured to restore energy elastic potential or gravitational potential energy on said movable block of sheave(s) (52), consist of a spring member or a counterweight (85).

6. Lifting system (1), according to any one of claims 1 to 5, characterized in that the control means (7) comprise a centering module (71) which, in the inactive configuration of the controlled braking means (6), is configured to control said winch (4) so ​​as to position the mobile block of sheave(s) (52) in a centered position, advantageously an average position centered on an available stroke, preferably prior to an operation of launching the package from a reference frame and / or in the passive swell compensation phase.

7. Lifting system (1), according to claim 6, characterized in that said centering module (71) consists of a slow centering module (71b) which, in the inactive configuration of the controlled braking means (6), cooperates with means for instantaneous and averaged measurement of the position of said mobile block of sheave(s) (52) over a period of time and which is configured to control said winch (4) when the average position of said mobile block of sheave(s) (52) reaches an actuation threshold on said degree of freedom in translation (T).

8. Lifting system (1), according to any one of claims 1 to 7, characterized in that the control means (7) comprise an end-of-travel safety module (72) which is configured to actuate said winch (4) when said movable block of sheave(s) (52) reaches an end-of-travel threshold on said degree of freedom in translation (T), so as to actively push said movable block of sheave(s) (52) relative to said end-of-travel threshold.

9. Lifting system (1), according to any one of claims 1 to 8, characterized in that the control means (7) comprise an automatic recovery module (73) and / or an automatic launch module (74), configured to automatically control said winch (4) and said controlled braking means (6) during a recovery operation and / or a launch operation of said package (C), which automatic recovery module (73) and / or automatic launch module (74) is preferably associated with at least one measuring sensor (75) configured to measure the relative vertical distance between a reference frame of said chassis (2) and a destination reference frame, for example in the case where the average distance between the reference frame of said chassis (2) and the destination reference frame is not known or variable.

10. Lifting system (1), according to any one of claims 1 to 9, characterized in that it consists of: - a crane comprising a lifting point (1a), the chassis (2) of which comprises an upright (2a) and a boom (2b), or - a gantry comprising at least two lifting points (1a).

11. A method of lifting a package (C), in particular for lifting a package (C) in the presence of relative movement due to swell, by implementing a lifting system (1) according to any one of claims 1 to 10, which lifting method comprises the following operations: (i) during an operation to launch said package (C) towards a new repository: - a step of suspending said package (C) from said lifting cable (3), in which said controlled braking means (6) are in active configuration and said mobile block of sheave(s) (52) is in an average position centered on an available stroke, - a step of lowering said package (C) near the highest wave crests of the swell, - when the package (C) is placed on a wave crest, a step deviates, preferably to come tangent to said wave crest, - when said package (C) transfers its weight from said lifting cable (3) to said new reference system, a step of switching said braking means to inactive configuration so that said lifting system (1) ensures passive compensation for the swell, and / or (ii) during an operation to recover said package (C), starting from an inactive configuration in which said lifting system (1) provides passive compensation for the swell, - if said package (C) is in an upward movement, a step of passing towards said active configuration so that said mobile block of sheave(s) (52) continues its movement by increasing said distance dimension (D), this up to a wave crest where said mobile block of sheave(s) (52) is blocked in translation, or - if said package (C) is in a downward movement, a step of maintaining the controlled braking means (6) in the inactive configuration then a step of switching to said active configuration at the start of said upward movement of said package (C).

12. Method for lifting a package (C), according to claim 11, characterized in that, in passive compensation for the swell, said method comprises a step of piloting said winch (4) to tend to maintain the mobile block of sheave(s) (52) in an average position.

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