EP3256415B1 - Crane, as well as process for monitoring the overload protection of such a crane - Google Patents

Description

The present invention relates to a crane with a boom, on which at least one load suspension device can be raised and lowered, an overload protection device having detection means for detecting the radius and the load on the at least one load suspension device, and a monitoring device for monitoring the overload protection device being provided and Determination means for determining a guy holding the boom and / or induced in a guy. The invention also relates to a method for monitoring the overload protection device of such a crane.

On cranes such as construction cranes, for example mobile construction cranes, tower cranes or luffing jib cranes with a luffing jib, the crane load is usually monitored by means of a crane control or an overload protection device implemented therein to determine whether a critical load limit has been reached, so that the crane threatens to topple over or is otherwise endangered in order to then switch off the corresponding drive devices of the crane in good time if necessary. Such an overload protection device usually works with stored load curves, which are the permissible load for a respective radius Specify, where the actual outreach and the actual load are recorded on the crane by means of sensors and compared with the load for the respective outreach permitted by the stored load curve. If the actual, recorded load state approaches the load curve or if it is reached or even exceeded, the crane drives are switched off by the overload protection device or at least slowed down and / or a corresponding warning signal is displayed. The actual load can be determined, for example, from the hoist cable taking into account the reeving, for example by means of a lifting force sensor indicating the driving force of the hoisting winch or also force sensors assigned to deflection rollers or cylinders. The outreach, i.e. the horizontal distance from an assumed tipping axis, in particular from the articulation or luffing axis of the jib, can be determined in different ways depending on the type of crane, for example by means of a position sensor which indicates the position of a trolley cable winch, or an angular position transmitter which Indicates the angle of attack of the boom or other suitable projection sensors, it also being possible to provide a plurality of such sensors or detection means in combination with one another.

However, such an overload protection device can only work safely and reliably if the said detection means actually detect the overhang and the load correctly and precisely and do not supply incorrect values. In rough crane operation, however, it can happen that, for example, angle sensors that are intended to detect the jib angle of attack slip, or the load detection means incorrectly detect the actual load because they are based on incorrect rope reeving. If, for example, the load hook is operated with a double reeving, but the overload protection device assumes only a single reeving, the load hook actually hangs a load twice as large as specified by the load detection means. As a result of such errors, the overload protection device would assume incorrect values of the actual throat and / or the actual load, so that despite The stability of the crane may be jeopardized in comparison with the permissible load value for the corresponding radius according to the stored load curve.

In order to prevent such malfunctions, it has already been considered to monitor the overload protection device with a monitoring device and to do this to see whether a tensioning force actually induced in the tensioning of the boom corresponds to the expected tensioning force based on the throat depth indicated by the sensors or detection means of the overload protection device - and load values are to be expected. For this purpose, the tensioning force measured during a scaling process can be assigned or compared with the detected load and throat values, so that if the deviations are too large, it can be concluded that the overload protection device is malfunctioning. However, such a scaling process by comparing the induced bracing force with the load and unloading values detected by the overload protection device is relatively complex and cannot really rule out malfunctions with sufficient accuracy and safety in the event of changes that occur in crane operation.

From Scripture EP 0 667 315 A1 A tower crane is known whose overload protection calculates a product corresponding to the load moment from the measured load and the outreach. In addition, the load torque is measured directly using a load torque sensor that detects the deformation of a corner post of the tower top. The immediately measured load torque is compared with the calculated product, a signal being emitted if the immediately measured load torque deviates from the product by a predetermined value.

From the scriptures CN 1139413 A . JP 2000-191 286 A . JP 4224929 B2 . JP 2008-110 825 A and JP 3281481 B2 Cranes are also known whose overload protection calculates and adds up a load moment and a dead moment from the measured load, the outreach and a jib luffing angle and compares it with a permissible tipping moment.

The present invention is therefore based on the object of specifying an improved crane and an improved method for monitoring the overload protection device, avoiding the disadvantages of the prior art and developing the latter in an advantageous manner. In particular, precise and permanently reliable monitoring of the overload protection device and its load and unloading detection means are to be created without complex scaling processes.

According to the invention, the stated object is achieved by a crane according to claim 1 and a method according to claim 7. Preferred embodiments of the invention are the subject of the dependent claims.

It is therefore proposed that when comparing the moments acting in opposite directions on the crane or boom, this is also due to the weight of the Consider the dead moment arising from the jib and any other crane components and to carry out the torque comparison continuously as background monitoring even in crane operation. According to the invention, it is provided that the monitoring device determines an anchoring torque online in crane operation from the continuously determined anchoring force, determines a load moment from the continuously measured radius and the continuously detected load, determines a dead moment with the aid of stored crane data, the sum of the mentioned load moment and the compares said dead torque with said tensioning torque and, if a deviation determined during the adjustment exceeds a tolerance threshold, emits an error and / or shutdown signal. If the evaluation unit determines that the tensioning torque calculated by the torque calculator does not correspond to the sum of the opposing load and dead moments or deviates too much from it, it can be assumed that the sensor or the detection means of the overload protection device detects the load and detect the outreach, something is wrong or the overload protection device is incorrectly calculating. The tolerance threshold mentioned can be set appropriately in order to take into account variable secondary loads such as, for example, wind forces, retrospectively attached billboards on the boom or other disturbance variables such as, for example, customary measurement tolerances.

By taking into account the dead torque of the boom and any attachments attached to it, such as a trolley rope, additional deflection pulleys or a boom extension in the form of a flyjib, the monitoring can be carried out much more precisely and precisely and even minor errors, for example by slipping angle sensors, can be noticed, whereby by the determination of the dead torque with the help of stored crane data is no longer a complex scaling process or the operator no longer has to configure any special parameters when scaling, ie adjusting the crane. The data required for monitoring can be loaded semi-automatically or fully automatically in the background when setting up the crane.

In a further development of the invention, the monitoring device mentioned can in particular also be used to monitor a crane with a luffing jib and the angle detector of the overload protection device provided for determining the jib angle of attack. The angle detector mentioned can in principle be designed differently, for example an angle position sensor which is attached in the region of the luffing axis of the boom. As an alternative or in addition, a drum position and / or drive position sensor can also be provided as the angle detector, which is assigned to a retraction mechanism and / or detects the position of the guy rope and / or linkage for the boom and thus the boom angle.

Advantageously, the boom angle of attack determined with the aid of the mentioned angle of inclination or luffing angle is taken into account both when determining the load moment and when determining the dead moment, since a change in the angle of the boom means both the unloading of the load suspension device and the lever arm or the unloading of the center of gravity of the dead leg mass can influence. The monitoring device or its torque calculator can calculate the aforementioned dead torque on the basis of the stored crane data, which can include the boom weight, the boom length, the center of gravity and / or the center of gravity distance from the luffing axis of the boom, taking into account the aforementioned boom angle or luffing angle. In particular, the fact that the lever arm of the dead mass and thus the dead moment becomes smaller with an increasingly steeper boom can be taken into account by taking the boom luffing angle into account. In a similar way, the torque calculator can also take the angle of attack into account for the load torque, since the lever arm or the outreach of the load suspension device and thus the resulting load torque becomes smaller with an increasingly steeper boom.

In a further development of the invention, the boom angle of attack determined by the named angle detector or luffing angle sensor can, however, not only be taken into account when calculating the dead moment and the load moment, but also when calculating the guying torque rotating in the opposite direction, since the effective lever arm of the guying usually also changes by adjusting the angle of the boom.

Advantageously, the monitoring device or its torque calculator calculates a lever arm of the anchoring force on the jib, the outreach of the at least one load-carrying device and the lever arm of the dead load of the jib, from the respectively determined jib angle of attack or luffing angle, in order then to additionally use the respectively determined anchoring force, the respective to determine the specific torque and the stored boom dead weight and to compare the torque rotating clockwise and counterclockwise.

If the crane has more than one load handler, for example in the form of a first load hook that runs from a main part of the boom or from a trolley, and a second load hook that runs from a boom extension or a so-called flyjib, the multiple load handlers can each individual lever arms are determined or projections are taken into account in order to precisely determine the load moments generated in each case.

In the aforementioned determination of the lever arms of the guying force, the at least one load suspension device and the dead load, the monitoring device can advantageously assume that the lever arm can be related to a common tilt axis. In particular, the monitoring device can relate all lever arms of the guying, load and dead load forces to the luffing axis of the boom, whereby a simple yet sufficiently precise torque calculation can be achieved. The calculation model used for this purpose, which the monitoring device uses, is hereby significantly simplified without losing accuracy.

In principle, however, the torque calculation can also be based on different or other tilting axes, for example the base of the tower of a tower crane or an undercarriage support point located under the boom. The aforementioned calculation of the lever arms based on the luffing axis of the boom, however, noticeably simplifies the moment calculation.

The above-mentioned determining means for determining the guying force holding the boom or induced in the guying can basically be designed differently. For example, in an advantageous further development of the invention, a force transmitter can be assigned to the neck rope or the neck tensioning rod that holds the boom in order to measure the tensioning force directly. As an alternative or in addition, at least one force transmitter can also be assigned to a guy strut or support, for example in the form of a spire over which the guy rope runs, in order to detect reaction forces induced by the guy rope or linkage in the guy support. As an alternative or in addition, force and / or expansion and / or bending deformation sensors can also be assigned to a structural part of the crane, which is subjected to a corresponding deformation due to the anchoring force. For example, in the case of a tower crane in the form of a top-slewing crane, the bending moment introduced into the tower or the bending and / or expansion load resulting in the tower can be recorded, which is a measure of the bracing or reaction torque counteracting the load and dead moments.

In this respect, the anchoring force used in the context of the present invention can mean the force directly induced in an anchoring or holding the boom or an associated reaction force that occurs in a structural part of the crane and a measure of the anchoring counteracting the load and dead moments. or reaction moment.

Fig. 1:

eine schematische, ausschnittsweise Darstellung eines Turmdrehkrans mit wippbarem Ausleger und am Ausleger angebrachter Auslegerverlängerung in Form eines Flyjibs, sowie der am Ausleger angreifende Kräfte und Momente,

Fig. 2:

ein Datenflussdiagramm zur Verdeutlichung der Bestimmung der Last- und Ausladungs- bzw. Hebelarmwerte, der hieraus abgeleiteten Momentenberechnung und des Abgleichs der im Uhrzeigersinn drehenden Momente mit den im Gegenuhrzeigersinn drehenden Momenten, und

Fig. 3:

eine Lastkurve der Überlastsicherungsvorrichtung für einen Turmdrehkran mit horizontaler Wippstellung des Auslegers.

The invention is explained in more detail below on the basis of preferred exemplary embodiments and associated drawings. The drawings show:

Fig. 1:

1 shows a schematic, partial representation of a tower crane with a luffing jib and a jib extension attached to the jib in the form of a flyjib, as well as the forces and moments acting on the jib,

Fig. 2:

a data flow diagram to illustrate the determination of the load and unloading or lever arm values, the derived torque calculation and the comparison of the clockwise rotating moments with the counterclockwise rotating moments, and

Fig. 3:

a load curve of the overload protection device for a tower crane with a horizontal luffing position of the boom.

How Fig. 1 indicates that the crane 1 can be designed as a construction crane or tower crane, which comprises a tower 2, which can be supported on a rotating platform 3, which is seated on an undercarriage and can be rotated about an upright axis of rotation. When trained as a top-slewing tower 2 can also be anchored in a rotationally fixed manner. The aforementioned undercarriage can be designed as a truck, caterpillar carriage or can be moved in some other way, but can also be a firmly anchored or firmly supported support base.

Said tower 2 can carry a boom 3 which can be rocked up and down about a horizontal rocking axis 4, which can extend at the foot of the boom 3 or between tower 2 and boom 3. When designed as a top-slewing boom 3 can also be rotated about an upright axis, in particular the longitudinal axis of the tower around the tower 2.

The cantilever 3 is anchored by means of anchoring 5, said anchoring 5 can have a neck rope 7 which can be adjusted by a retractor 7, by the rocking angle or the angle of attack of the cantilever 3 preferably to be able to adjust continuously. The mentioned neck rope 7 can in this case be guided or deflected over a tower tip 8 which is only indicated, but alternatively or additionally also other support struts and in particular instead of a guy rope also a guy rod can be provided.

How Fig. 1 shows, a lifting cable with a load hook 9 articulated thereon can run off via a corresponding deflection roller in the area of the boom tip, wherein said load hook 9 or the lifting cable connected thereto could also be guided over a trolley which runs along the boom 3 in a manner known per se can be moved.

How Fig. 1 further shows, a boom extension 10 in the form of a flyjib can be attached to the boom 3, it being possible for a further lifting device in the form of a load hook 11 to run off the flyjib on a corresponding lifting rope.

How Fig. 1 illustrates, act on the boom 3 several useful and dead load forces, which have different lever arms and according Fig. 1 exert clockwise rotating moments on the boom 3. The load hooks 9 and 11 running from the boom 3 or the boom extension 10 pull the boom 3 accordingly Fig. 1 clockwise downwards, whereby the forces F _{G + S} and F * _{G + S} each result from the payload attached to the load hook 9 or 11 and the rope and hook weight. The horizontal radius of the forces F _{G + S} and F * _{G + S} determines their lever arm I _{G + S} and I _FJ with respect to the luffing axis 4 of the boom 3, which can be regarded as a tilting axis.

Furthermore, the dead load of the boom 3 tries this boom 3 with the force F _A according to Fig. 1 pull clockwise downwards, the dead load mentioned being composed of the dead weight of the boom 3, the dead weight of the flyjib or the boom extension 10 and any additional components attached to it, such as a trolley rope, deflection pulleys, headlights, winches, actuators and other attachments can. The dead load representative dead load force F _A can be regarded as attacking in the center of gravity S, cf. Fig. 1 , The dead loads or weight forces mentioned and the geometry of the boom including the distance of the center of gravity S from the luffing axis 4 can be stored in the form of crane data in a memory 12 of the crane control 13.

On the other hand, the anchoring force F _N acts on the cantilever 3, which can be applied by the aforementioned neck rope of the anchoring 5 and according to Fig. 1 tries to pull the boom 3 counterclockwise.

The above-mentioned bracing force F _N has the in Fig. 1 visible lever arm I _N , which forms a straight line through the rocking axis 4 perpendicular to the neck rope 7.

In order to keep the boom 3 in balance, the sum of all the clockwise rotating moments must correspond to the sum of all the counterclockwise rotating moments. With regard to the forces and moments explained above, this means that the bracing torque due to the bracing force F _N must correspond to the sum of the load moments by the load hooks 9 and 11 and the dead load torque, as the following equation expresses: $${\mathrm{F}}_{\mathrm{N}}\times {\mathrm{I}}_{\mathrm{N}}={\mathrm{F}}_{\mathrm{A}}\times {\mathrm{I}}_{\mathrm{A}}+{\mathrm{F}}_{\mathrm{G}+\mathrm{S}}\times {\mathrm{I}}_{\mathrm{G}+\mathrm{S}}+\mathrm{F}{*}_{\mathrm{G}+\mathrm{S}}\times {\mathrm{I}}_{\mathrm{FJ}}$$

How out Fig. 1 As can be seen, the lever arms I _A , I _{G + S} and I _{FJ of} the payloads and dead loads and also the lever arm I _{N of} the guying force F _{N are influenced} by the luffing angle or angle of attack of the boom 3, the lever arms I _A , I _{G + S} and I _FJ of dead loads and payloads change significantly more when the angle of attack of the boom 3 changes than the lever arm I _{N of} the tensioning force F _N , at least in the usual angle of attack of the boom 3, which is between a horizontal orientation of the boom 3 and an orientation of the boom 3 pointing upwards at an acute angle to the vertical can be enough. The lesser influence on the lever arm I _{N of} the guying force F _N is essentially due to the geometry of the guying, since the guying angle of the neck rope 6 to the jib 3 is adjusted relatively weakly when the jib 3 is rocked, if the jib 3 is in a conventional manner is quite long in relation to the height of the spire.

An overload protection device 14 implemented in the crane control 13 determines the unloading of the payloads F _{G + S} and F * _{G + S} as well as the payloads themselves using suitable detection means 15 and 16. For this purpose, an angle transmitter 17 can detect the luffing or pitching angle of the boom 3 , so that the outreach, ie the lever arms I _{G + S} and I _{FJ, can be} determined using the stored crane geometry or boom geometry data. If a trolley can be moved on the boom 3, a trolley position transmitter can also be provided. On the other hand, the lifting cables leading to the load hooks 9 and 11 can be provided with lifting force transmitters 18, which can be assigned to the lifting winch drives or deflection roller suspensions in order to determine the lifting cable forces. From the correspondingly determined load values and outreach values, the overload protection device 14 mentioned can carry out a comparison with one or more load curves, which can / can be stored in the memory of the crane control 13. Such a stored load curve 23 is shown by way of example in FIG. 4.

In order to be able to monitor the function of the overload protection device 14 in the background, a monitoring device 19 is also provided, which consists of the aforementioned payloads and dead loads F _{G + S} , F * _{G + S} and F _A and the associated overhang values or lever arms I _{G + S} , I _FJ and I _A calculates the payload and dead load moments acting on the boom 3. These useful and dead load moments all act clockwise Fig. 1 and Fig. 2 ,

On the other hand, the above-mentioned monitoring device 19 or the torque computer 20 implemented therein calculates this in the counterclockwise direction Fig. 1 and Fig. 2 on the boom 3 acting torque, which results from the Anchoring force F _N and the associated lever arm I _N results. As explained above, the angle of attack of the boom 3, which is measured by the aforementioned angle sensor 17, is taken into account in the torque calculation, more precisely in the determination of the lever arms.

An evaluation unit 21 of the monitoring device 19 then compares the above-mentioned tensioning torque which rotates counterclockwise with the sum of the load and dead load torques rotating clockwise, cf. Fig. 2 , To be more precise, said evaluation unit 21 determines the difference between said tensioning torque rotating counterclockwise and the sum of the load and dead load torques rotating clockwise. If the resulting difference exceeds a certain tolerance threshold, the evaluation unit 21 concludes that the overload protection device 14, in particular its detection means 15 and 16, is not working properly.

In such a case, the evaluation unit 21 can on the one hand issue an error message, which can be output on a display device in the crane cabin and / or on a display device on the radio terminal. On the other hand, the evaluation unit 21 can also output a shutdown signal in order to shutdown actuators, in particular a main linkage drive and / or a flyjib winch drive and / or a retracting gear drive.

The tolerance threshold mentioned serves to take into account disturbance variables such as wind forces, retrospectively attached advertising signs on the boom or other disturbance variables and can be stored in the memory 12 of the crane control 13 in the form of a fixed, predetermined threshold value. As an alternative or in addition, the tolerance threshold mentioned can also be adapted to the resulting disturbance variables, for example depending on a wind measurement signal, in particular in such a way that the tolerance threshold is lowered when there is little or no wind and the tolerance threshold is increased with increasingly larger, stronger winds. An adaptation of the tolerance threshold depending on other influencing variables is conceivable.

How Fig. 2 shows, the monitoring device 19 can determine the tensioning force F _N by means of a force transmitter 24 or detect it by sensors, wherein the said force transmitter 24 can be directly assigned to the tensioning 5 or the neck rope 6. For example, the force transmitter 24 can detect the winch torque of the pull-in unit 7 on which the neck rope 6 is wound.

Claims (7)

1. Crane, having a boom (3) at which at least one load receiving means (9, 11) is arranged in a liftable and lowerable manner, wherein an overload protection device (14) comprises detection means (15, 16) for detecting the outreach and the load on the at least one load receiving means (9, 11) and is configured to compare the detected load and the detected outreach with a stored load curve and to switch-off and/or slow-down a crane drive upon reaching or exceeding the load curve, and wherein a monitoring device (19) for monitoring the overload protection device (14) is provided and comprises determination means (22) for determining a tensioning force holding the boom (4) and/or induced in a guy cable (5), wherein the monitoring device (19) is configured to determine a lifting torque (F_G+S × I_G+S + F*_G+S × I_FJ) from the detected outreach (I_G+S, I_FJ) and the detected load (F_G+S, F*_G+S), characterized in that the monitoring device (19) determines online in crane operation a tensioning torque (F_N x I_N) from the determined tensioning force (F_N), determines a dead torque (F_A x I_A) using stored crane data, compares the sum of the named lifting torque (F_G+S × I_G+S + F*_G+S × I_FJ) and the named dead torque (F_A x I_A) with the named tensioning torque (F_N x I_N) and then, if a difference of the tensioning torque from said sum of lifting torque and dead torque exceeds a tolerance threshold, outputs an error signal and/or shutdown signal.
2. Crane in accordance with the preceding claim, wherein the boom (3) is luffably supported about a horizontal luffing axis (4) and the detection means (15) of the overload protection device (14) for detecting the outreach comprise a luffing angle encoder (17) for determining a boom luffing angle or boom setting angle (β), wherein the monitoring device (19) is configured to take into account the boom setting angle (β) determined by the luffing angle encoder (17) both on the determination of the lifting torque and of the dead torque and on the determination of the tensioning torque.
3. Crane in accordance with the preceding claim, wherein a lever arm (I_N) of the tensioning force (F_N) on the boom (3), the outreach (I_G+S, I_FJ) of the at least one load receiving means (9, 11), and the lever arm (I_A) of the dead lifting force (F_A) of the boom (3) can be calculated by the monitoring device (19) from the boom setting angle (β) determined by the luffing angle encoder (17).
4. Crane in accordance with one of the preceding claims, wherein the monitoring device (19) is configured such that the lever arm (I_N) of the tensioning force (F_N), the outreach (I_G+S, I_FJ) of the at least one load receiving means (9, 11) and the lever arm (I_A) of the dead lifting force (F_A) of the boom (3) is related to a common tilt axis, in particular the luffing axis (4) of the boom (3), and/or is calculated with respect to the named tilt axis.
5. Crane in accordance with one of the preceding claims, wherein the determination means (22) for determining the tensioning force (F_N) comprises a force transmitter for detecting the tension force in a neck cable or in neck rods (6) and/or is associated with the named neck cable or neck rods (6).
6. Crane in accordance with one of the preceding claims, wherein the stored crane data comprise the weight of the boom (3) and/or the weight of a boom extension (10) and/or the length of the boom (3) and/or the length of the boom extension (10) and/or the distance of the center of gravity (S) of the boom (3) from a boom luffing axis (4) and/or the distance of the center of gravity of the boom extension (10) from the boom luffing axis (4).
7. Method of monitoring the overload protection device (14) of a crane (1) that detects the actual load acting on at least one load receiving means (9, 11) and the outreach of the at least one load receiving means using detection means (15, 16) and compares them with a load value permitted for the respective outreach, in particular from a stored load curve, and outputs a warning signal upon reaching or exceeding of the permitted load value and/or at least switches off and/or slows down a crane drive, wherein the overload protection device (14) is monitored for its correct function by a monitoring device (19), characterized in that a tensioning torque is also continuously determined in crane operation by the monitoring device (19) from a continuously determined tensioning force, a lifting torque is determined from the detected outreach and from the detected actual load, a dead torque is determined from stored crane data, the difference between the determined tensioning torque and the sum of the named lifting torque and the dead torque is formed, and an error signal and/or signal is output upon exceeding of a tolerance threshold by the named difference.

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