Counterweight device, crane with such a device, and methods for determining weight

Abstract

The invention relates to a counterweight device for a crane, in particular for a mobile crane, comprising a base plate, one or more ballast elements stackable on the base plate, and a measuring device by means of which the weight of a ballast stack of ballast elements stacked on the base plate can be detected. According to the invention, the measuring device comprises at least one lifting cushion integrated into the base plate, which is designed to lift the ballast stack from the base plate by filling it with a pressure medium, and at least one sensor for detecting pressure in the at least one lifting cushion. The invention further relates to a crane with such a counterweight device and to a method for weighing ballast using such a device.

Description

[0001] The present invention relates to a counterweight device for a crane, in particular for a mobile crane, according to the preamble of claim 1.

[0002] Conventional cranes have a counterweight device to generate a moment that counteracts the load, preventing the crane from tipping over and thus contributing to its stability. Especially in mobile cranes, conventional counterweight devices comprise several ballast elements that can typically be stacked on top of each other in one or more stacks. The weight of the counterweight device can be adjusted by varying the ballast elements accordingly, thus adapting it to the specific crane application.

[0003] For the stability of the crane, it is therefore essential that the currently effective weight of the counterweight device is known. This is usually incorporated into the crane's load moment limitation, which determines corresponding limits for the maximum permissible load for specific crane movements from the current crane configuration (including the current counterweight) and continuously monitors the crane movement. If the current load exceeds the corresponding limit for the current crane movement or position, the crane operator can be warned and / or the load moment limitation can automatically intervene in the crane's control. The load moment limitation prevents tipping in the direction of the load as well as tipping in the direction of the counterweight arrangement due to an insufficient load moment.

[0004] State-of-the-art technology allows the crane operator to manually enter the currently used ballasting via an input unit, thus providing the information to the control system or load moment limiter. However, this carries the risk of incorrect inputs by the crane operator.

[0005] Cranes are also known to have a measuring device that automatically determines the current ballasting, i.e. the weight of the counterweight device. The problem with this, however, is that the sensors used to measure the weight of the ballast elements can become damaged or dirty during crane operation. In addition, some solutions are based on measuring the oil pressure in one or more cylinders, e.g. in ballasting cylinders that are arranged on the upper carriage of the crane and lift the ballasted counterweight device onto the upper carriage, or in cylinders specially provided for the measurement. For this purpose, the counterweight device or the respective ballast stack is raised a short distance and then lowered again. The friction in the cylinder can be eliminated from the two measured pressures (raising, lowering), which allows a more reliable statement about the weight of the counterweight device.However, this solution is complex and is not available for cranes that do not have such cylinders (e.g. cranes that are ballasted with the help of an auxiliary crane).

[0006] From DE 28 14 540 C2 it is already known to arrange an air cushion under a counterweight in order to enable the counterweight to slide on the ground during the rotating and sliding movement of the crane.

[0007] The present invention is therefore based on the object of providing a simple and reliable method for detecting the weight of the counterweight device in such cranes. In particular, reliable ballast weighing should be enabled using simple and cost-effective components.

[0008] According to the invention, this object is achieved by a counterweight device having the features of claim 1, a crane having the features of claim 10, and a method having the features of claim 14. Advantageous embodiments of the invention emerge from the subclaims and the following description.

[0009] Accordingly, on the one hand, a counterweight device is proposed which comprises a base plate, in particular a plurality (i.e. at least two) ballast elements which can be stacked on the base plate, and a measuring device. The weight of a ballast stack of ballast elements stacked on the base plate can be detected by means of the measuring device. The weight of the ballast stack which can be detected by the measuring device is also referred to below as the ballast weight. The ballast elements or the ballast stack formed from the ballast elements can be deposited or stacked on a storage surface of the base plate. The storage surface is formed in particular by the upper side of the base plate. The ballast elements and the base plate can in principle have any desired shape, for example a substantially triangular or rectangular shape in plan view. The base plate can have any desired shape, for example a continuous shape orplate shape, or for example just represent a frame structure.

[0010] According to the invention, the measuring device comprises at least one lifting cushion integrated into the base plate (also referred to as a lifting cushion), which is designed to lift the ballast stack from the base plate by filling the at least one lifting cushion with a pressure medium (air, water, oil, etc.). The at least one lifting cushion is thus designed to completely lift the ballast stack against the weight of the ballast stack, so that at some point it lifts off the base plate and no longer rests on it. In this state, in particular the entire weight of the ballast stack rests on the at least one lifting cushion. The at least one lifting cushion can be designed to lift the ballast stack by several cm, for example 1-2 cm, from the base plate.

[0011] According to the invention, the measuring device comprises at least one sensor by means of which a pressure in the at least one lifting bag can be detected. This can be a pressure sensor, which can be arranged, for example, in the lifting bag or in a pressure line of the lifting bag, via which the bag can be filled with the pressure medium.

[0012] A basic idea of ​​the present invention is therefore to carry out simple and reliable ballast weighing using one or more lifting bags integrated into the base plate, whereby the ballast stack is lifted until it is only resting on the at least one lifting bag. The weight of the raised ballast stack can be determined from the pressure measured in the lifting bag(s) and made available to a control and / or load moment limiter. The ballast weighing according to the invention is based on simple and cost-effective components (lifting bags) which do not have their own mechanics and are therefore less susceptible to errors. Since the load orthe ballast weight is determined via the pressure in the lifting bag(s) and no distorting friction effects occur (as, for example, in the case of ballast weighing using ballasting cylinders), the reliability of the ballast weighing according to the invention depends only on the accuracy of the sensors used to detect the pressure.

[0013] The result of the ballast weighing according to the invention does not necessarily have to be an exact value, since the weight fractionation based on a specific number of ballast elements allows the ballasting to be reliably determined even with a slightly deviating value. The ballast elements can, for example, have individual masses of 5t or 10t (or any other mass).

[0014] The value of the ballast weight determined by the measuring device is preferably provided to a control and / or load moment limiter. The other dead weights of the additional components of the counterweight device (such as the base plate itself) are particularly known to this control and / or load moment limiter, so that if the ballast weight is known (i.e. the recorded weight of the ballast elements lifted via the at least one lifting bag and whose arrangement and number can be varied), the entire counterweight is also known. This can be included in a load moment limiter and compared, for example, with a selected load capacity table. In response, a confirmation signal can be issued to the crane driver if the ballasting is correct and / or a warning signal can be issued if the ballasting is incorrect, i.e. insufficient. The ballast weighing according to the invention thus significantly reduces the risk of incorrect ballasting.

[0015] The ballast weighing process can be completed, in particular, by completely lowering the raised ballast stack, i.e., by releasing pressure medium from the at least one lifting cushion. Preferably, the entire ballast weighing process, including raising the ballast stack, recording the pressure, calculating the ballast weight, and subsequently lowering the ballast stack, is carried out automatically, in particular by a control system or crane control system. The ballast weighing process can be initiated by the crane operator, for example, at the push of a button.

[0016] It should be noted that in the case of a low ballasting load, only a single ballast element may be placed on the base plate. In this case, the raised "ballast stack" consists of only a single ballast element.

[0017] In one possible embodiment, the measuring device comprises at least two lifting bags and at least two corresponding sensors for measuring the pressures in the individual lifting bags. Each lifting bag is assigned at least one sensor for measuring the respective pressure. The total weight of the lifted ballast stack is then determined by combining (e.g., adding) the measured individual pressures and converting them into the effective weight force. The filling and emptying of the lifting bags is controlled and / or regulated, in particular, by a control system such that the ballast stack is raised / lowered evenly and safely.

[0018] The measuring device preferably comprises at least three lifting bags and at least three corresponding sensors for recording the pressures in the individual lifting bags. This results in stable and secure storage of the raised ballast stack, which rests on at least three "support points" when raised. Exactly three lifting bags can be provided. In many cases, this is sufficient for stable storage and precise ballast weighing and can be used in particular for ballast elements with an essentially triangular base area. Of course, more than three lifting bags, e.g. exactly four lifting bags, can be used, for example when using essentially rectangular ballast elements. In principle, any number of lifting bags is conceivable.

[0019] In a further possible embodiment, the lifting bags are not directly connected to one another. In other words, pressure medium cannot flow directly from one lifting bag to another. This counteracts the tipping of the raised ballast stack if the crane or the base plate is tilted. Such an inclination can occur, for example, due to a tilt of the crane (e.g. on inclined ground) or due to deformation of the crane's superstructure. In such an inclination, the center of gravity of the ballast stack shifts. If the lifting bags were connected to one another, all lifting bags would receive the same pressure. The lifting bag further away from the center of gravity of the ballast stack would receive more volume at the same pressure and thus lift the lowest ballast element of the ballast tower further.This would cause the center of gravity to shift more and more, resulting in the risk of the ballast stack tipping over.

[0020] Preferably, each lifting bag is connected to a pressure source (e.g., a pressure accumulator of the crane) or to a connection for connecting such a pressure source. In principle, each lifting bag can be pressurized by its own pressure source, or all lifting bags can be pressurized by a common pressure source. It is also conceivable to connect a common pressure source to all lifting bags and provide corresponding valves between the lifting bags and the pressure source, which can be controlled, in particular, by a controller. Such valves can be binary switchable or continuously adjustable in flow.

[0021] The pressure source is preferably a pressure source of the crane, e.g., a pressure accumulator that can be filled with pressure via the crane's power supply. This can be, for example, a compressed air reservoir or a hydraulic accumulator (e.g., for hydraulic oil or water).

[0022] In a further possible embodiment, the counterweight device comprises at least one proximity sensor, which can be used to detect whether the ballast stack in the area of ​​the at least one lifting cushion is resting on the base plate or has been lifted off it. The at least one proximity sensor is connected, in particular, to a controller and delivers a corresponding signal when the ballast stack (or its lowest ballast element) is resting on the base plate or not in this area.

[0023] The at least one proximity sensor is preferably arranged on or in the base plate in the area of ​​the at least one lifting cushion. In particular, the at least one proximity sensor is arranged in the area of ​​an outer edge of the base plate and thus as far out as possible, so that even small movements of the ballast stack relative to the base plate can be quickly detected.

[0024] The counterweight device preferably comprises several lifting cushions, with each lifting cushion being assigned at least one proximity sensor. This allows detection if the ballast stack has not been completely lifted from the base plate and is still resting, for example, in the area of ​​a lifting cushion. The pressure of the lifting cushions is preferably recorded, and thus the ballast weight is determined, only when all proximity sensors signal that the ballast stack has been lifted.

[0025] In a further possible embodiment, the base plate has at least one recess in which the at least one lifting bag is arranged. The counterweight device preferably comprises a plurality of lifting bags, each lifting bag being arranged in its own recess. The at least one lifting bag and the at least one recess are designed such that the ballast stack rests completely on the base plate when the at least one lifting bag is in a depressurized state (i.e. when it is not filled). In particular, the recess is deeper than the height of the lifting bag in the unfilled state. When the at least one lifting bag is fully filled, the ballast stack is completely lifted from the base plate and rests only on the at least one lifting bag. The height of the latter is therefore greater than the depth of the recess when fully filled.

[0026] In a further possible embodiment, a limit stop is arranged on the base plate to secure the raised ballast stack against tipping and / or slipping. Since the ballast stack only rests on the at least one lifting bag in the fully raised state, such a limit stop can ensure the necessary safety and prevent tipping and / or slipping. The limit stop is designed to completely or partially enclose at least part of the ballast stack placed on the base plate at the sides. The limit stop preferably has a minimum height relative to a deposit surface of the base plate, which is greater than a maximum projection of the at least one lifting bag in the filled state relative to the deposit surface. In other words, the limit stop still encloses part of the ballast stack even when it is fully raised.

[0027] The boundary can be designed as a circumferential wall, e.g., a circumferential sheet, forming a type of pocket, the bottom of which forms the base plate and in which the ballast stack is placed. The pocket can have a height that essentially corresponds to the height of one or two ballast elements. Alternatively or additionally, the boundary can have a height that varies in the circumferential direction. The shape of the boundary in plan view follows, in particular, the outer contour or the shape of the base plate and the ballast elements.

[0028] In a further possible embodiment, the counterweight device comprises a safety device for securing the ballast elements of a ballast stack against slipping or falling, in particular in the event of a load break. This can prevent one or more ballast elements of the stack from slipping or even falling when the ballast stack is lifted and / or when the base plate is tilted. For this purpose, the safety device comprises at least one safety element which is detachably connectable to at least one of the ballast elements of the ballast stack. In principle, it is sufficient if the safety element connects the base plate to the uppermost ballast element of the ballast stack, since the ballast elements located between them are mutually secured, in particular by corresponding projections and recesses.Alternatively, the safety element can connect several or all ballast elements of the ballast stack to each other and to the base plate. This provides even better security.

[0029] The safety element can be guided along the outer sides of the ballast elements when secured or connected. For this purpose, the ballast elements can have corresponding connecting elements on their outer sides, which can be reversibly connected to corresponding connecting elements of the safety element (e.g., arresting elements on the ballast elements and holes or recesses on the safety element at regular intervals along the vertical axis of the ballast stack). Alternatively (or additionally, if multiple safety elements are provided), the safety element can run through the ballast elements when secured or connected, with the ballast elements having corresponding recesses for this purpose (e.g., in the center).

[0030] In a further possible embodiment, it is provided that the safety element is designed to permit movement of the ballast stack perpendicular to a storage surface of the base plate (i.e. along the stacking direction or height axis of the ballast stack) by a certain distance in the secured state. The ballast stack can therefore move a certain distance relative to the base plate even in the secured state. The safety element is designed such that the distance by which the ballast stack can be lifted relative to the base plate corresponds at least to a maximum projection (e.g. 1-2 cm) of the at least one lifting bag in the filled state from the storage surface. This ensures that even in the secured state the ballast stack can be lifted from the base plate by filling the at least one lifting bag in order to carry out the ballast weighing.

[0031] The safety element is designed in particular in such a way that it is not subjected to tensile stress when the ballast stack is completely lifted (i.e. when the at least one lifting cushion is completely filled), since this would falsify the measurement result of the pressure resulting from the dead weight of the ballast stack.

[0032] In another possible embodiment, the counterweight device comprises at least two base plates, each of which can support a ballast stack comprising a plurality of ballast elements. Each of the base plates comprises at least one lifting cushion and at least one associated sensor, so that automatic ballast weighing according to the method described above can be performed by each of the base plates for the ballast stack placed thereon. The lifting cushions of the various base plates can be supplied by a common pressure source and / or the sensors can be read by a common control system.

[0033] Preferably, the base plates are each pivotably mounted on a ballast frame. The base plates can, in particular, each be pivoted relative to the ballast frame about a vertical pivot axis by means of an actuator. This allows the centers of gravity of the ballast stacks mounted on the base plates to be shifted and, in particular, their distances from a vertical rotation axis of a crane's superstructure to be changed, which corresponds to a change in the ballast radius. This allows a higher maximum load to be achieved with the same weight (increasing the ballast radius) or, if necessary (e.g., in confined spaces), the ballast radius to be reduced.

[0034] The invention further relates to a crane with a counterweight device according to the invention. This obviously results in the same advantages and properties as for the counterweight device according to the invention, which is why a repeated description is omitted. The crane can be a mobile crane comprising a mobile undercarriage and a superstructure rotatably mounted on the undercarriage. The undercarriage can have a wheeled chassis, a rail chassis, or a crawler chassis. In the present case, a mobile crane is generally understood to mean a mobile crane, for example, a lattice boom crane with a crawler chassis. This can optionally also have a derrick boom with suspended ballast or a ballast carriage.

[0035] The crane according to the invention preferably comprises a pressure accumulator (e.g., compressed air or hydraulic accumulator) connected to the at least one lifting bag and designed to fill it with a pressure medium and provide a pressure sufficient to completely lift the ballast stack from the base plate. The pressure in the pressure accumulator comes, in particular, from a power supply for the crane components in the crane itself.

[0036] In one possible embodiment, the crane comprises a control system connected to the at least one sensor and to the previously described at least one proximity sensor. The control system can be a crane control system, a separate control unit, or a combination of several control units. The control system is preferably configured to stop filling at least one lifting bag with pressure medium as soon as the associated proximity sensor signals that the ballast stack has been completely lifted from the base plate in the area of ​​the respective lifting bag.

[0037] In another possible embodiment, the counterweight device comprises a plurality of lifting cushions, a plurality of sensors, and a plurality of proximity sensors, and the controller is configured to determine the weight of the ballast stack by detecting the pressures in the individual lifting cushions as soon as all proximity sensors signal that the ballast stack has been completely lifted from the base plate. The controller is preferably configured to determine the weight of the ballast stack by combining the detected individual pressures, in particular by summing the detected pressures. The resulting total pressure is then converted into a corresponding weight force.

[0038] In a further possible embodiment, the controller is configured to determine the weight of the ballast stack from the detected pressure of at least one lifting bag (in the case of multiple lifting bags, from the total pressure, which in turn was determined from the detected individual pressures) using a predefined assignment rule, in particular a calibration curve or calibration table, which is stored in the controller or in a data storage device connected to the controller. According to such a curve or table, a ratio of pressure to mass or weight of the ballast can be specified.

[0039] The invention further relates to a method for determining the weight of ballast elements of a counterweight device according to the invention. The method, which can be applied analogously to the crane according to the invention comprising such a counterweight device, comprises the following steps: - Stacking several ballast elements on the base plate to form a ballast stack. Ballasting, i.e., moving and stacking the ballast elements of the ballast stack, is carried out primarily by means of an auxiliary crane. Ballasting using one or more ballasting cylinders is preferably not provided or possible. - Filling the at least one lifting bag embedded in the base plate with a pressure medium until the ballast stack is completely lifted off the base plate and rests only on the at least one lifting bag. - Detecting a pressure in the at least one lifting bag using the at least one sensor of the measuring device. This may include detecting multiple pressures in multiple lifting bags. - Determining the weight of the lifted ballast stack from the measured pressure, in particular using a predetermined assignment rule such as a calibration curve or calibration table.

[0040] This obviously results in the same advantages and properties as for the counterweight device according to the invention or the crane according to the invention. In particular, the method can comprise any of the steps described with respect to the counterweight device according to the invention or the crane according to the invention or relate to any of the described optional embodiments of the counterweight device or the crane, in any desired combination. Therefore, all optional variants will not be listed again.

[0041] In one possible embodiment of the method, the at least one lifting bag is filled with a pressure medium until the associated proximity sensor signals that the ballast stack has been completely lifted from the base plate. Preferably, the counterweight device comprises several lifting bags, several sensors, and several proximity sensors, as described above. The weight of the ballast stack is determined by detecting and combining the pressures in the individual lifting bags as soon as all proximity sensors signal that the ballast stack has been completely lifted from the base plate.

[0042] Further features, details, and advantages of the invention will become apparent from the following exemplary embodiments explained with reference to the figures. They show: Fig. 1: a mobile crane known from the state of the art; Fig. 2: the ballasted counterweight device of a known mobile crane; Fig. 3: a perspective view of the base plate and a ballast element with a schematically drawn measuring device according to an embodiment of the invention; Fig. 4a-b: side schematic sectional views of a lifting bag in the pressureless and in the filled state in a recess of the base plate according to an embodiment; Fig. 5: a perspective view of the counterweight device according to an embodiment without ballast stack; Fig. 6: a sectional view through a ballast stack of the counterweight device according to an embodiment; and Fig. 7: the counterweight device according to Fig. 5 with ballast stack.

[0043] The Fig. 1 shows a perspective view of an example of a mobile crane 1' known from the prior art, which comprises a mobile undercarriage 2 with a wheeled chassis and an uppercarriage 4 mounted on the undercarriage 2 for rotation about a vertical axis of rotation, on which uppercarriage 4 a telescopic boom 6 is pivotably mounted about a horizontal luffing axis. In the example shown here, a folding jib 7 is mounted laterally on the telescopic boom 6, which can be mounted to a boom head of the telescopic boom 6 if required. The mobile crane 1' has a counterweight device 8 at the rear of the uppercarriage. In the example shown here, this counterweight device 8 is not ballasted, but rather only two pivoting supports can be seen, on which ballast stacks can be mounted.

[0044] The ballasted counterweight device 8 of such a known mobile crane 1' is shown in a side view in the Fig. 2. Here, the superstructure 4 (also referred to as the rotating platform) can be seen together with the counterweight device 8, with several ballast elements 14 stacked into a ballast stack 15 and supported on the supports. The ballasting or stacking of the individual ballast elements 14 is carried out, for example, by an auxiliary crane.

[0045] In such known cranes, each ballast tower or ballast stack 15 can first be lowered a short distance and then raised again via ballasting cylinders mounted on the superstructure 4. During lowering and raising (to eliminate friction), the pressure in the cylinder is measured and then converted into the weight of the ballast stack 15.

[0046] In the counterweight device according to the invention, ballast weighing is not performed via hydraulic cylinders, but via pressure measurement in lifting cushions integrated into the base plate and capable of lifting the ballast stacks from the base plate. This allows the weight of the ballast stack to be measured more accurately, eliminating the need for cylinders that temporarily lower and raise the ballast stacks for weight measurement. Furthermore, the solution according to the invention is based on simple elements that do not have their own mechanical components and are therefore less prone to failure and, moreover, more cost-effective.

[0047] An embodiment of the base plate 12 of the counterweight device 10 according to the invention with integrated lifting cushions 30 is shown in the Fig. 3. In this exemplary embodiment, the ballast elements 14 and also the base plate 12 have a substantially triangular base area, with three lifting bags 30 integrated into the base plate 12 and arranged in the region of the three "corners" of the base plate 12. It should be noted that, of course, other geometries and / or a different number of lifting bags 30 are also possible (for example, four lifting bags 30 for rectangular ballast elements).

[0048] The lifting cushions 30 are arranged in specially provided recesses 18 of the base plate 12, as shown in the Fig. 4a and Fig. 4b is shown in schematic sectional views. The lifting cushions 30 can be filled with a pressure medium (e.g. compressed air). As shown in the Fig. As shown schematically in Figure 3, the lifting bags 30 can be connected to a pressure accumulator 34 (or generally to a pressure source) via which the lifting bags 30 are filled. In the exemplary embodiment shown here, the lifting bags 30 are connected to a connection 35, which in turn is connected to the pressure accumulator 34. The lifting bags 30 are thus not connected to one another, but rather to the pressure accumulator 34.

[0049] To fill the lifting bags 30, appropriate valves can be integrated into the connection between the pressure accumulator 34 and connection 35, into the connecting lines between connection 35 and the lifting bags 30, into the connection or connection device 35 itself, or at another location in the pressure system. A control system, e.g., the crane control system, can control and / or regulate the compressed air supply to the lifting bags 30 and thus fill or empty them. Preferably, all lifting bags 30 can be filled or emptied independently of one another.

[0050] The counterweight device 10 according to the invention comprises a measuring device by means of which the pressures in the lifting cushions 30 can be measured and transmitted to the control system. Fig. In the embodiment shown in Figure 3, sensors 32, which are pressure sensors in this case, are integrated into the pressure lines of the lifting bags 30. Each sensor 32 detects the pressure prevailing in the associated lifting bag 30.

[0051] The principle of ballast weighing according to the invention is based on the fact that the lifting cushions 30 are designed to lift the entire ballast stack 15 by filling them with pressure medium until the ballast stack 15 is completely lifted from the base plate 12 and only rests on the lifting cushions 30. This is shown in the Fig. 4b, whereby it can be seen that the lifting cushions 30 lie completely in the recess 18 in the emptied state (cf. Fig. 4a) and in the fully filled state protrude beyond the support surface 19 of the base plate 12 and have a greater height than the depth of the recess 18, so that the lowest ballast element 14 of the ballast stack 15 no longer contacts the support surface 19 of the base plate 12 in the area of ​​the lifting cushion 30.

[0052] In order to detect when the ballast stack 15 is completely lifted, i.e. when the lowermost ballast element 14 of the ballast stack 15 is lifted from the base plate 12 in the area of ​​each of the lifting cushions 30, the measuring device in the embodiment shown here comprises three proximity sensors 36, which are arranged in the area of ​​the respective lifting cushions 30 in the base plate 12 (cf. Fig. 4a-b) and send a corresponding signal to the control system when the lowest ballast element 14 has moved away from the base plate 12. As shown in the Fig. As can be seen in Figure 3, the proximity sensors 36 are arranged in outer regions of the base plate 12, so that they are as far away as possible from the center of the base plate 12. This allows them to react quickly and even to small movements of the lowest ballast element 14 of the ballast stack 15. Of course, the proximity sensors 36 could also be arranged at a different location on the base plate 12 or in the ballast element 14. Likewise, more or fewer, or in the simplest case, only a single proximity sensor 36 could be provided to detect a lifted state of the ballast stack 15.

[0053] As soon as all proximity sensors 36 send the "lifted" signal, the pressures in the lifting bags 30 are recorded via sensors 32 and transmitted to the control system. The individual pressures are added together to form a total pressure, which is then converted into a mass or weight of the ballast stack 15. For this purpose, a calibration curve can be stored in the control system, for example, which specifies a pressure-to-mass ratio of the ballast.

[0054] It should be noted that an exact determination of the ballast weight with an exact kg specification is not absolutely necessary, since the ballast plates 14 have masses of several tons and therefore no exact kg specification is required to determine the ballast density. From the weight determined from the pressures, it is easy to determine how many ballast elements 14 or which arrangement of ballast elements 14 is present in the raised ballast stack 15. From this, the exact weight can then be derived if necessary. For this purpose, the masses of the available ballast elements 14 can be stored in the control system, so that the control system is preferably able to automatically derive the appropriate ballast configuration from the recorded weight.

[0055] This determined value can, for example, be compared with a selected load capacity table, and either an "OK" or a message (e.g., "Crane incorrectly rigged") can be issued to the crane operator. The weighing process is completed by releasing all pressure in the lifting bags 30. The crane can then operate safely (after the "OK") according to the respective load capacity table. Instead of load capacity tables, dynamic calculations of the permissible loads based on the determined weight of the counterweight device or ballast can also be used for load moment limitation.

[0056] Because the lifting bags 30 are not interconnected, tipping of the ballast stack 15 can be avoided when the base plate 12 is tilted, since the center of gravity of the ballast stack 15 changes when tilted. If all lifting bags 30 are interconnected, they receive the same pressure, which can promote tipping, since lifting bags 30 farther from the center of gravity receive more volume.

[0057] As already mentioned, the lifting of the lowest ballast element 14, and thus of the ballast stack 15, from the base plate 12 is monitored via proximity sensors 36. If the first of the proximity sensors 36 signals that the ballast element 14 has been lifted, a valve (controlled by the control system), for example, shuts off the flow of filling medium to the corresponding lifting bag 30. Only when all proximity sensors 36 signal "lifted" is the pressure in all lifting bags 30 measured, from which the total weight of the ballast stack 15 can be calculated. If a proximity sensor 36 signals "not lifted" again, the corresponding lifting bag 30 will be further filled if necessary.

[0058] To ensure sufficient stability of the ballast stack 15 in the lifted state, the counterweight device 10 preferably has a limit. An embodiment of this is shown in Fig. 5, wherein in this embodiment, two base plates 12 are provided, which are mounted on a common ballast frame 11 of the counterweight device 10 so as to be pivotable about vertical pivot axes. The pivoting of the base plates 12 is effected via corresponding actuators in the form of hydraulic cylinders 13. Each of the base plates 12 comprises corresponding lifting cushions 30 and a measuring device according to the principle described above. The function of the limit stop will now be explained using this embodiment, although only one base plate with a limit stop or a different base plate shape could also be provided.

[0059] In this embodiment, the boundary is formed by a casing or wall 22 extending around the outside of the base plate 12, which forms a receiving area or a "pocket" 20, the bottom of which is formed by the base plate 12 with the lifting cushions 30. The ballast elements 14 are placed in this pocket 20 and stacked to form a ballast stack 15. In the embodiment shown here, the pocket 20 surrounds only the lowest or the two lowest ballast elements 14, as in the Fig. 7, which shows the counterweight device 10 with one of the two final ballast stacks 15. Fig. 7, it should be noted that, as shown, the ballast elements are not completely enclosed by the boundary 22. Due to their triangular shape, the ballast elements are nevertheless held in a form-fitting manner by the pocket 20 or the boundary 22. The pocket 20 can ensure that the ballast tower 15 is securely held and does not slip off the base plate 12 even when lifted off. Alternatively, the pocket 20 can completely surround the ballast elements 14, at least in the lower area.

[0060] Additional protection of the ballast tower 15 in the event of a load break can optionally be achieved by means of a safety device. An example of this is shown in the Fig. 6, showing a section through a stacked ballast stack 15. In this exemplary embodiment, the securing device comprises a securing element in the form of a securing chain 24, which connects the uppermost ballast element 14 of the ballast stack 15 to the base plate 12 or another sufficiently strong point on or around the pocket 20. For this purpose, all ballast elements 14 of the ballast stack 15 comprise a central recess 17, through which the securing chain 24 runs from bottom to top, i.e. parallel to the vertical axis of the ballast stack 15. Alternatively, it can be provided that the securing chain 24 is connected to each ballast element 14. The securing chain 24 must not be subjected to tensile stress when the ballast stack 15 is lifted off the ground, as this would falsify the measurement result. The safety chain 24 therefore has a sufficient length so that the lifting of the ballast stack 15 (for example by approx. 10-20 mm) is not impaired.

[0061] Positioning elements, for example in the form of one or more positioning lugs 16 (cf. Fig. 5), which interact with corresponding recesses or grooves at least in the lowest ballast element 14. These can serve to guide the ballast stack 15 during lifting. Friction of the ballast plates 14 against the inner wall of the pocket 20 during lifting is thus eliminated, since the lowest ballast element 14 is aligned with the positioning lugs 16.

[0062] The crane according to the invention can, except for the counterweight device, Fig. 1 shown components or the structure shown.

[0063] The crane according to the invention can also have more than two ballast stacks. If the counterweight device with all components is sufficiently dimensioned, then it is conceivable for a pocket 20 to have two or more ballast stacks 15. In this case, it is conceivable for each ballast stack 15 to have its own measuring device, or for both ballast stacks to rest on a common measuring device.

[0064] The device according to the invention can also be used on the ballast receptacles of a crawler crane. Here, too, similar, particularly cuboid-shaped pockets are provided for receiving ballast plates 14 on the superstructure 4.

[0065] The device according to the invention can also be used on ballast stacks on a ballast wagon or on suspended ballast. Here, too, various stacks with one or more ballast plates 14 are provided. List of reference symbols: 1' mobile crane (state of the art) 2 undercarriages 3 axis of rotation 4 superstructures 8 Counterweight device (state of the art) 10 Counterweight device 11 Ballast frame 12 Base plate 13 Actuator 14 Ballast element 15 ballast stacks 16 Positioning nose 17 Central recess 18 Recess 19 storage space 20 Recording area (pocket) 22 Limitation 24 security element 30 lifting bags 32 Sensor (pressure sensor) 34 Pressure source (pressure accumulator) 35 connection 36 Proximity sensor

Claims

[1] Counterweight device (10) for a crane, in particular for a mobile crane, comprising a base plate (12), one or more ballast elements (14) stackable on the base plate (12) and a measuring device by means of which the weight of a ballast stack (15) of ballast elements (14) stacked on the base plate (12) can be detected, characterized by that the measuring device comprises at least one lifting cushion (30) integrated into the base plate (12), which is designed to lift the ballast stack (15) from the base plate (12) by filling it with a pressure medium, and at least one sensor (32) for detecting a pressure in the at least one lifting cushion (30). [2] Counterweight device (10) according to claim 1, wherein the measuring device comprises at least two, preferably at least three lifting cushions (30) and at least two, preferably at least three sensors (32) for detecting the pressures in the individual lifting cushions (30). [3] Counterweight device (10) according to the preceding claim, wherein the lifting cushions (30) are not directly connected to one another, wherein preferably each lifting cushion (30) is connected to a pressure source (34) or to a connection (35) for connecting a pressure source (34). [4] Counterweight device (10) according to one of the preceding claims, further comprising at least one proximity sensor (36), which is preferably arranged on the base plate (12) in the region of the at least one lifting cushion (30), in particular in the region of an outer edge of the base plate (12), and by means of which a resting or lifted state of the ballast stack (15) on / from the base plate (12) in the region of the at least one lifting cushion (30) can be detected. [5] Counterweight device (10) according to one of the preceding claims, wherein the base plate (12) has at least one recess (18) in which the at least one lifting cushion (30) is arranged, wherein the lifting cushion (30) and the recess (18) are designed such that the ballast stack (15) rests completely on the base plate (12) in a pressure-free state of the at least one lifting cushion (30) and is completely lifted off the base plate (12) and rests only on the at least one lifting cushion (30) in a fully filled state of the at least one lifting cushion (30). [6] Counterweight device (10) according to one of the preceding claims, wherein a boundary (22) for securing the raised ballast stack (15) against tipping and / or slipping is arranged on the base plate (12), which boundary is designed to laterally enclose completely or partially at least part of a ballast stack (15) deposited on the base plate (12), wherein the boundary preferably has a minimum height relative to a deposit surface (19) of the base plate (12), which is greater than a maximum projection of the at least one lifting cushion (30) in the filled state relative to the deposit surface (19). [7] Counterweight device (10) according to one of the preceding claims, further comprising a safety device for securing the ballast elements (14) of a ballast stack (15) against slipping or falling, wherein the safety device comprises at least one safety element (24) which, in the secured state, runs on outer sides of the ballast elements (14) or through recesses formed in the ballast elements (14) and detachably connects at least one ballast element (14) to the base plate (12). [8] Counterweight device (10) according to the preceding claim, wherein the safety element (24) is designed to permit, in the secured state, a movement of the ballast stack (15) perpendicular to a support surface (19) of the base plate (12) by a distance which corresponds at least to a maximum projection of the at least one lifting cushion (30) in the filled state to the support surface (19). [9] Counterweight device (10) according to one of the preceding claims, comprising at least two base plates (12), on each of which a plurality of ballast elements (14) can be stacked to form ballast stacks (15), wherein each of the base plates (12) comprises at least one lifting cushion (30) and at least one associated sensor, wherein the base plates (12) are preferably pivotally mounted on a ballast frame (11) and in particular are each pivotable about a vertical pivot axis relative to the ballast frame (11) by means of an actuator (13). [10] Crane, in particular a mobile crane comprising a mobile undercarriage (2) and a superstructure (4) rotatably mounted on the undercarriage (2), comprising a counterweight device (10) according to one of the preceding claims and a pressure source, in particular a pressure accumulator, which is connected to the at least one lifting cushion (30) and is designed to fill the at least one lifting cushion (30) with a pressure medium and to provide such a pressure that the ballast stack (15) lifts completely off the base plate (12). [11] Crane according to the preceding claim, wherein the counterweight device (10) is further developed at least by the features of claim 4, comprising a control which is connected to the at least one sensor and to the at least one proximity sensor (36), wherein the control is preferably designed to stop filling of at least one lifting bag (30) as soon as the associated proximity sensor (36) signals complete lifting of the ballast stack (15) from the base plate (12) in the region of the lifting bag (30). [12] Crane according to the preceding claim, wherein the counterweight device (10) comprises a plurality of lifting cushions (30), a plurality of sensors (32) and a plurality of proximity sensors (36) and the control is arranged to determine the weight of the ballast stack (15) by detecting the pressures in the individual lifting cushions (30) as soon as all proximity sensors (36) signal a complete lifting of the ballast stack (15) from the base plate (12), wherein the control is preferably arranged to determine the weight of the ballast stack (15) by a combination, in particular by adding the detected individual pressures. [13] Crane according to one of the two preceding claims, wherein the control is arranged to determine the weight of the ballast stack (15) from the detected pressure of the at least one lifting cushion (30) using a predetermined allocation rule, in particular a calibration curve or calibration table, which is stored in the control or in a data memory connected to the control. [14] Method for determining the weight of ballast elements of a counterweight device (10) according to one of claims 1 to 9, comprising the following steps: - stacking several ballast elements (14) on the base plate (12) to form a ballast stack (15), in particular by means of an auxiliary crane, - filling the at least one lifting cushion (30) with a pressure medium until the ballast stack (15) lifts completely off the base plate (12) and rests only on the at least one lifting cushion (30), - detecting a pressure in the at least one lifting cushion (30) by means of the at least one sensor (32), - Determining the weight of the lifted ballast stack (15) from the detected pressure, in particular based on a predetermined allocation rule. [15] Method according to the preceding claim, wherein the counterweight device (10) is further developed at least by the features of claim 4, wherein the at least one lifting cushion (30) is filled with a pressure medium until the associated proximity sensor (36) signals a complete lifting of the ballast stack (15) from the base plate (12), wherein preferably the counterweight device (10) comprises a plurality of lifting cushions (30), a plurality of sensors (32) and a plurality of proximity sensors (36) and the weight of the ballast stack (15) is determined by detecting and combining the pressures in the individual lifting cushions (30) as soon as all proximity sensors (36) signal a complete lifting of the ballast stack (15) from the base plate (12).

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