Device and method for ballast weighing on a crane and a corresponding crane

Abstract

Device for weighing ballast on a crane, with at least two ballasting cylinders (1, 1') which are designed to raise / lower the ballast (2) and which each comprise at least one pressure sensor (10, 10'; 11, 11') in the region of the piston and / or rod side, and with at least one evaluation unit (3) which is designed to calculate the mass moved by the ballasting cylinders (1, 1') from the pressures detected by the pressure sensors (10, 10'; 11, 11') when the ballasting cylinders (1, 1') are extended and retracted, excluding the frictional forces occurring in the ballasting cylinders (1, 1').

Description

The invention relates to a device for ballasting a crane, having at least two ballasting cylinders which are designed to raise / lower the ballast and which each comprise at least one pressure transmitter in the region of the piston and / or rod side, and having at least one evaluation unit which is designed to calculate the mass moved by the ballasting cylinders from the pressures detected by the pressure transmitters when the ballasting cylinders are moved in and / or extended, with exclusion of the frictional forces occurring in the ballasting cylinders. The invention is further directed to a method for calculating the ballast weight of a crane with a corresponding device.The counterweight provides a moment that counteracts the load carried by the crane. The counterweight thus contributes substantially to the stability of the crane. If the crane has an automatic load moment limitation, for example, the size of the effective counterweight or the mass and the effective lever arm of the counterweight are used in the calculation for the stability of the crane. The terms mass and weight are intended to be used both here, since it is clear to the person skilled in the art how to use or convert the respectively necessary size. It is known that the crane driver or other operators of the crane manually input the data necessary for carrying out the load torque limitation. The problem with this procedure is that errors can occur when manually inputting the necessary data and / or the necessary data cannot be easily retrieved.CN 102 249 152 A and DE 10 2016 203 607 A1 each disclose devices for ballasting a crane.Against this background, it is an object of the invention to provide a device or a method which can reduce corresponding incorrect inputs and / or can subject the manual inputs of a crane driver or another operator to a counter-check or a plausibility check. According to the invention, a completely autonomous method or a completely autonomous device can also be provided, which make inputs by a crane driver or an operator superfluous.This object is achieved by a device according to claim 1, which is designed for ballast weighing on a crane and comprises at least two ballast cylinders which are designed to raise / lower the ballast. Advantageous embodiments are the subject of the dependent claims. Accordingly, a device is provided in which the ballasting cylinders each comprise at least one pressure transmitter in the region of the piston and / or rod side and which further comprises at least one evaluation unit which is configured to calculate the mass moved by the ballasting cylinders from the pressures detected by the pressure transmitters during the retraction and / or extension of the ballasting cylinders, excluding the frictional forces occurring in the ballasting cylinder.Components already present on a crane such as the ballasting cylinders can thus advantageously be used as part of the device according to the invention for determining the ballast weight. The amount of additional necessary components can thus be reduced. It is also conceivable that the evaluation unit is designed as part of a control / regulation already provided on the crane. The frictional forces occurring in the ballasting cylinders can be excluded, for example, by means of stored frictional values which the evaluation unit can use and which can be taken into account in the calculation of the mass.In a preferred embodiment, it can be provided that the pressure transmitters are arranged directly in the ballasting cylinders. Pressure-sensitive areas of the pressure transmitters can be directly exposed to the pressure medium contained in the ballasting cylinders and for this purpose do not have to be coupled to the ballasting cylinders via any additional pressure lines or the like, which would otherwise have to be designed as components different from the ballasting cylinders, such as external pressure lines. With such an arrangement of the pressure sensors, the measurement accuracy can be increased. The measurement accuracy is increased in that a direct pressure measurement can be carried out in the space of the cylinder, which delivers more accurate measurement values than is the case with a measurement which takes place in a region which is led out of the space of the cylinder via pipelines and is thus spaced apart from the cylinder. The arrangement of the pressure transmitters in the ballasting cylinders also reduces the risk of damage, since the pressure transmitters are better protected by the structure of the ballasting cylinders than would be the case with pressure transmitters not arranged within the ballasting cylinders.It is conceivable that the pressure transmitters are arranged within feedthroughs in the walls of the ballasting cylinders, in order to thus enable a pressure measurement that is as direct as possible.In a further preferred embodiment, it is conceivable that exactly one pressure transmitter is arranged on the rod side and one pressure transmitter is arranged on the piston side of the ballasting cylinders. By means of the pressure measurement on both sides of the ballasting cylinders which is possible as a result, it is possible to determine an accurate value of the pressure difference between the two sides of the ballasting cylinders and to calculate a value, which is as accurate as possible, of the force exerted by the ballasting cylinders from this.The invention is further directed to a method for calculating the ballast weight of a crane with an apparatus according to any one of claims 1 to 3. The method comprises the steps:detecting the pressures in the ballasting cylinders; andcalculating the mass held by the ballasting cylinders on the basis of the pressures detected and taking into account the associated surfaces.In this case, dimensions of the ballasting cylinders or the surfaces on which the pressure medium acts, which dimensions are required for calculating the held mass, can be stored in the evaluation unit or input, so that, as explained further below, a calculation of the forces exerted by the ballasting cylinders via the surfaces of the ballasting cylinders subjected to corresponding pressures is possible. The term "held mass" can of course also refer to a mass moved by means of the ballasting cylinders.According to the method, the pressure can be detected in each of exactly one space of the ballasting cylinders and, on the basis of these pressures, the load on the ballasting cylinders and thus the effective ballast weight can be determined or calculated. The space can be the rod-side or piston-side working space of the ballasting cylinders.In a preferred embodiment, it can be provided thatdetecting the pressures in the ballasting cylinders when the ballasting cylinders are retracted and / or extended; wherein in particularcalculating pressure differences in the ballasting cylinders on the basis of the pressures detected during the retraction and / or extension.It is conceivable that, in order to increase the accuracy of the calculation, pressures are detected in each space of the ballasting cylinders and the pressure is detected both when the ballasting cylinders are retracted and when the ballasting cylinders are extended. By calculating the pressure differences, the measurement accuracy of the calculation can be further increased.In a preferred embodiment, it is conceivable that the method comprises the step:performing a plausibility check, wherein the calculated mass is compared with a mass that is input, in particular manually.The mass of the ballast weight can thus be entered by an operator into the evaluation unit or into another computing unit and / or regulation / control and / or checked according to the method. If it is determined according to the method that a difference exists between calculated mass and manually input mass that exceeds a limit value, then a warning signal can be output, for example, by means of the evaluation unit and / or the operation of the crane can be restricted. An automatic input of the weight or mass of the ballast is also conceivable, wherein a correspondingly provided detection device detects the weight of attached ballast bodies and makes it available to the evaluation unit or makes it available for carrying out the plausibility check.A possible chopping of a ballast detection can also be incorporated into the plausibility test. For example, weights of 2, 6, 10, 14 or 18 tons can be used as possible ballast weights. If the control or the evaluation unit has determined a value of, for example, 2.4 tom according to the present invention, then it can set the ballast for the load torque limitation or the actual ballast weight to 2 tom. The blur permissible in this case for assigning the actual ballast weight can moreover be variable in a situation-related manner. For example, the influence of the ambient temperature can likewise be included.In a further preferred embodiment, it is conceivable that the method comprises the step:using the calculated mass in the load torque limitation of the crane.The use of the calculated mass and other variables relates to the use of the calculated value of the mass for carrying out further method steps. The load torque limitation can be configured to prevent the crane from moving and / or to output warning messages if a specific load is exceeded, in order to avoid unstable states of the crane. For this purpose, the load torque limitation must know the effective ballast weight in order to determine or calculate permissible positions or loads of the crane from this and to prevent tilting forward or rearward or a fall back of the crane. This can occur, for example, if the boom is set too steeply for the effective ballast.In a further preferred embodiment, it is conceivable that the method comprises the step:measuring the temperature of the fluid medium and compensating temperature-related influences on the calculated mass.The temperature of the fluid medium or of the hydraulic medium can be measured here, for example, within the ballasting cylinders and / or within lines leading away from the ballasting cylinders and / or from the ballasting cylinders. Since different viscosities of the medium can be taken into account at different temperatures of the hydraulic medium, it is possible by the temperature detection to take into account temperature-related influences on the pressure conditions in the device or to determine corresponding compensation values or correction values from stored tables or the like and to use them for correcting the calculated mass or for compensating errors in a further calculation step.The same applies to an alternative or additional compensation of friction influences on the calculated mass.In a further preferred embodiment, it is conceivable that the method comprises the step:bracing the ballast with a rotating platform of the crane after ballasting has taken place.The bracing can be carried out between the processes of inward and / or outward movement or after completion of the inward or outward movement of the ballasting cylinders. In the present case, the method according to the invention for calculating the ballast weight can be considered as ballasting.The invention is further directed to a crane having an apparatus according to any one of claims 1 to 3.Further details and advantages of the invention are explained in more detail on the basis of the embodiment shown by way of example in the figures. The following are shown: FIGS. 1 a, 1 b : Schematic representations of two devices according to the invention; FIG. 2 : first pressure-time diagram of a method according to the invention; FIGS. 3 a, 3 b : second pressure-time diagrams of a method according to the invention.FIG. 1a is a schematic illustration of a device according to the invention for ballasting on a crane. Here, a left ballasting cylinder 1 and a right ballasting cylinder 1' for lifting a ballast 2, which is not explained in more detail, are shown. The ballasting cylinders 1, 1' each comprise at least one pressure transmitter 10, 10', which are each arranged in the region of the piston side and / or rod side of the ballasting cylinders 1, 1'. Further pressure transmitters 11, 11' can be provided on the piston side of the ballasting cylinders 1, 1'. Depending on whether there is an embodiment with one pressure transmitter or with two pressure transmitters per ballasting cylinder 1, 1', either the pressure difference between the two pressure transmitters of a ballasting cylinder 1, 1' or the absolute pressure measured at a single pressure transmitter can be determined or used according to the invention.The pressure transducers 10, 11; 10', 11' can be coupled to an evaluation unit 3. The evaluation unit 3 is configured to calculate the mass moved by the ballasting cylinders 1, 1' from pressures detected by at least two of the pressure transmitters 10, 11; 10', 11' during the retraction and / or extension of the ballasting cylinders 1, 1'.The counterweight provides a moment counteracting the crane load or the load lifted by the crane. Thus, the counterweight contributes substantially to the stability of the crane. Load moment limiting of the crane uses the size of the effective counterweight (mass and effective lever arm) in calculating the safety of the crane and can prevent the crane from tilting backwards or forwards in impermissible crane positions. The backward tilting can occur if the boom of the crane is set too steeply for the effective ballast. Up to now, the crane rider has entered the data manually. In order to avoid incorrect inputs here, a device is to be provided which subjects the inputs of the crane driver to at least one counter-check / plausibility check. In the best case, the device should be able to operate completely autonomously and make input by the crane driver superfluous.In each of the two ballasting cylinders 1, 1', a pressure transmitter 10, 11; 10', 11' can be installed on the ring and piston surfaces. On the basis of a pressure measurement, in particular in the ring and / or piston space (during the retraction and extension of the ballasting cylinders 1, 1'), it is possible to determine the mass which hangs on the ballasting cylinders 1, 1'.The pressure transmitters 10, 11; 10', 11' can be installed directly in the cylinder and do not have to be connected to them via lines. This increases the measurement accuracy, so that line losses and temperature errors can be avoided to the greatest possible extent.A temperature measurement and a correction of the pressure values on the basis of the temperature values and the consideration of a friction factor can likewise be provided.FIG. 1b shows an embodiment of the invention in which at least one piston rod of the ballasting cylinders 1, 1' is clamped in the ballast. As a result, the symbolically shown center of gravity of the ballast device can be located at a distance a from the longitudinal axis of the piston rod. When two ballasting cylinders 1, 1' are used, the center of gravity of the ballasting device can be located outside the plane which spans the longitudinal axes of the ballasting cylinders 1, 1'.In the exemplary embodiment shown in FIG. 1 b, the following applies for the retraction of the ballasting cylinder:The following applies to the case of extension:In this case, the following also applies: where m is the weight of the ballast device and the further parameters are shown in the figure. Here, the parameters P mean pressure values, the parameters A mean corresponding surfaces of the ballasting cylinder, the parameters F mean forces and the indices K and R mean piston-side and ring-side parameters, respectively.FIG. 2 shows the pressure curve in an embodiment of the invention in which only one pressure sensor 10, 10' or pressure transmitter 10, 10' is provided per ballasting cylinder 1, 1'. The pressure profile of the ring side is shown here correspondingly by the pressure generators 10, 10'. Owing to asymmetry, the pressure on the left and right is of different magnitude. The diagram is divided into 5 sections. Section 90 shows the area "ballast bottom". Here, the ballast rests on the undercarriage. Section 102 shows the area "Retract ballast.". Here, the ballasting cylinders 1, 1' retract and move the ballast upward. The section 91 shows a "standstill" area, in which ballast hangs with its entire weight on the ballasting cylinders 1, 1'. The ballast does not contact either an upper carriage or an under carriage of the crane. In this region, the pressure measurement takes place according to a simplified method, for example at 55 seconds. The second section 102 again shows "ballasting". Section 100 shows the area "ballast is at the top.". Here, the ballasting cylinders 1, 1' press the ballast against the superstructure of the crane.In the following, calculation examples are now given with reference to FIG. 2 only with one pressure transducer 10, 10' in each annular space. 1. measured values (measured values):Annular surface pressure: 57.1 barAnnular surface pressure on the left: 51.1 bar.2. Force calculation:Force Cylinder to the right [N]:Pressure Ring Surface to the right * Ring Surface * 1057,1 bar* 233.26 cm 2* 10 = 133193,3 NForce Cylinder to the left [N]:Pressure Ring area left * Ring area * 1051,1 bar* 233.26 cm 2* 10 = 119197,5 N3. Total force [kN]:Force Cylinder left + Force Cylinder right (133193.3N + 119197.5N) / 1000 = 252.39kN4. Ballast Detection:Mass determined [to]: Total force / 9.81 252.39 kN / 9.81=25.72 to5. Difference from the actual ballast:Actual ballast 26toObtained ballast: 25.72toDeviation: 280kgIn this case, it is possible to take into account the pressure in the annular space and the force exerted on the piston as a result. The above example can of course be used analogously if only one pressure transmitter 11, 11' is present in each of the piston chambers of the ballasting cylinders. Depending on the orientation of the ballast cylinders 1, 1' with respect to the crane, pressure transmitters can be arranged in those working spaces of the ballast cylinders 1, 1' which are pressurized by the mass of the ballast.In order to further increase the accuracy, a sequence of movements of the ballasting cylinders 1, 1' can be carried out automatically. The starting position is a state in which the ballast to be attached to the superstructure of the crane is stacked on the undercarriage in the mounting position and the connecting means between the ballasting cylinders 1, 1' and the ballast are overlapped to such an extent that the ballasting process can be terminated by just retracting the ballasting cylinders 1, 1'. The ballasting cylinders 1, 1' execute these movements as soon as the crane operator presses the button "Lift ballast", for example. The sequence of movements can continue to run independently as long as the crane rider keeps the button pressed. Acoustic feedback may be provided.First, the ballasting cylinders 1, 1' are extended for, for example, half a second--the piston or piston rod may be "locked" for the first time. Subsequently, the ballasting cylinders 1, 1' are retracted and the ballast 2 is pulled up. A pressure increase takes place on the ring surface until the ballast 2 is lifted from the undercarriage.When the ballast 2 is lifted from the undercarriage, a constant pressure is established. Subsequently, the ballast 2 can be braced, whereby the pressure in the annular surface increases. Shortly before the ballting process is completed, the measurement sequence for ballast weighing is initiated.In this case, the ballast 2 is extended again for a specific time. The ballast 2 hangs freely in the air and is held exclusively by the ballast cylinders 1, 1'. When the ballting cylinders 1, 1' are extended, the pressure in the ring and piston surface is measured, for example at 15000 ms, as can be seen from FIG. 3. From the measured pressures, a differential force is calculated when the ballasting cylinder is extended.Subsequently, the ballasting cylinders 1, 1' are retracted again and the ballast 2 is raised. Here too, a pressure measurement takes place during retraction in the ring and piston chamber, for example at just 25000 ms. A differential force when the ballasting cylinders 1, 1' are retracted is calculated from the measured pressures.From the differential forces during the retraction and extension a mass is determined which represents the attached ballast 2.In each of the two ballasting cylinders 1, 1', a pressure transmitter 10, 11; 10', 11' can be installed on the ring and piston surfaces. On the basis of a pressure measurement in the ring and piston surface (during the retraction and extension of the ballasting cylinders 1, 1'), the mass which hangs on the ballasting cylinders 1, 1' can be determined.A factor can also be taken into account in order to improve the result determined once more, similar to the rocker cylinder pressure measurement for the weighing. Furthermore, temperature compensation can also be included in the calculation.FIGS. 3a and 3b describe the method whereby an improvement can be achieved during the pressure measurement in the ballasting cylinders 1, 1' when the ballasting cylinders 1, 1' are retracted and when the ballasting cylinders 1, 1' are subsequently extended, by calculating the friction during the measurement.The portions shown in FIG. 3 a correspond to the portions shown in FIG. 2. The section 101 is shown anew in FIG. 3 a. Here, the ballasting cylinders 1, 1' extend and move the ballast away from the superstructure. The two curves 110 show the pressure profile on the ring side of the ballasting cylinders 1, 1'. They are tapped from the pressure generators 10 and 10'. The two curves 111 show the pressure profile on the piston side of the ballasting cylinders 1, 1'. They are tapped from the pressure transmitters 11 and 11'.The portions shown in FIG. 3 a correspond to the portions shown in FIG. 3 a. FIG. 3 bshows the "weighed ballast" stored in the controller. At the beginning of the measurement, an old value 112 for the "weighed ballast" is present. If the measurement cycle according to the invention begins, i.e. when the section 100 transitions into the section 101, then the old value is deleted. At just 25000 ms, the controller has determined the new value 113 for the "weighed ballast" by means of the method according to the invention and stored it in the controller. The control can of course be identical to the evaluation unit 3.The force occurring on the annular surface when the ballasting cylinders 1, 1' are retracted can be calculated as follows by way of example:Force Annular surface Cylinder to the right [N]:Pressure: ring area to the right * ring area *10161.0 bar *40.25cm 2*10=64802.5NForce Annular surface Cylinder on the left [N]:Pressure: Ring area to the left * Ring area * 10 161.7 bar * 40.25 cm 2 * 10 = 65084.25NTotal force: annular area [kN]:Force Cylinder left + Force Cylinder right (64802.5N + 65084N) / 1000=129.89kNThe force occurring on the piston surface during the retraction of the ballasting cylinders 1, 1' can be calculated as follows by way of example:Force piston surface cylinder left / right [N]: Pressure piston surface left / right * Annular surface * 1023, 5 bar*13.87 cm 2*10=244409.45NTotal force piston surface [kN]: force cylinder left + force cylinder right(24409.45N + 24409.45N) / 1000 = 48.82kNThe differential force during the retraction of the ballasting cylinders 1, 1' can be calculated as follows by way of example:Total force [kN]: Total force Annular area [kN] - Total force Piston area [kN]129.89kN-48.82kN = 81.07kNForce on the annular surface during the extension of the ballasting cylinders 1, 1' (at 15 sec) can be calculated as follows by way of example:Force Annular surface Cylinder to the right [N]:Pressure: ring surface to the right * ring surface * 10 235.0 bar* 40.25 cm 2 * 10 = 94587.5NForce Annular surface Cylinder on the left [N]:Pressure: Ring area on the left * Ring area * 10 235 bar* 40.25 cm 2 * 10 = 94587.5NTotal force: annular area [kN]:Force Cylinder left + Force Cylinder right (94587.5N + 94587.5N) / 1000 = 189.17kNForce on the piston surface when the ballasting cylinders 1, 1' are extended (at 15 sec) can be calculated as follows by way of example:Force piston surface cylinder left / right [N]: Pressure piston surface left / right * Ring surface * 1059,5 bar*103.87cm 2*10=11802.65NTotal force piston surface [kN]: force cylinder left + force cylinder right(61802.65N + 61802.65N) / 1000=132.61 kNThe differential force during the extension of the ballasting cylinder (at 15 sec) can be calculated as follows by way of example:Total force [kN]:Total force Annular surface [kN] Total force Piston surface [kN] 189.17 kN - 123.61 kN = 65.56 kNDetermined mass [t]:((Differential force extension+ Differential force retraction) / 2) / 9.81 ((81.07kN+65.56kN) / 2) / 9.81=7.47to→ Difference from the actual ballast:Actual ballast 7.36to Determined ballast: 7.47to Deviation: 110kgThe practical operation of the ballasting can be as follows: Ballast is located on the undercarriage and the signal "ballast down" is present. In this case, the ballast weight calculated last is zeroed.The operator activates the "Raise ballast" button on an operator control unit or on an operator control unit (button remains pressed). First, the ballasting cylinders are extended for a defined period of time--cylinders may be "locked" for the first time. The ballast is then retracted by the ballasting cylinders (ballast is pulled up). A pressure increase takes place on the ring surface until the ballast is lifted from the undercarriage.When the ballast 2 is lifted from the undercarriage, a constant pressure is established. The ballast is then braced, in this case the pressure in the ring and piston surface increases. Shortly before the ballting process is completed, the measurement sequence for ballast weighing is initiated. In this case, the ballast is extended again for a specific time (ballast hangs freely in the air). When the ballting cylinder or the ballasting cylinders 1, 1' is extended, the pressure in the ring and piston surface is increased. From the measured pressures, a differential force is calculated when the ballasting cylinder is extended. The ballast is then retracted again; here too, a pressure measurement takes place during the retraction. From the measured pressures, a differential force is calculated when the ballasting cylinder is retracted. From the differential forces during the retraction and extension a mass is determined which represents the attached ballast.

Claims

Device for ballasting on a crane, having at least two ballasting cylinders (1, 1') which are designed to raise / lower the ballast (2) and which each comprise at least one pressure transmitter (10, 10'; 11, 11') in the region of the piston and / or rod side, and having at least one evaluation unit (3) which is designed to calculate the mass moved by the ballasting cylinders (1, 1') from the pressures detected by the pressure transmitters (10, 10'; 11, 11') when the ballasting cylinders (1, 1') are moved in and out, excluding the frictional forces occurring in the ballasting cylinders (1, 1').Device according to claim 1, characterised in that the pressure transmitters (10, 10') are arranged directly in the ballasting cylinders (1, 1').Device according to claim 1 or 2, characterised in that exactly one pressure transmitter (10, 10') each is arranged on the rod side and one pressure transmitter (11, 11') each is arranged on the piston side of the ballasting cylinders (1, 1').Method for calculating the ballast weight of a crane with a device according to any one of claims 1 to 3, characterised bythe steps of: • detecting the pressures in the ballast cylinders (1, 1'); and • calculating the mass held by the ballast cylinders (1, 1') on the basis of the detected pressures and taking into account the associated surfaces.Method according to claim 4, characterised in that: • the pressures in the ballasting cylinders (1, 1') are detected when the ballasting cylinders (1, 1') are retracted and / or extended; • pressure differences in the ballasting cylinders (1, 1') being calculated on the basis of the pressures detected when the ballasting cylinders are retracted and extended.Method according to Claim 4 or 5, characterized bythe step: • carrying out a plausibility check, wherein the calculated mass is compared with a mass which is input in particular manually.Method according to any of claims 4 to 6, characterized bythe step of: • using the calculated mass in the load torque limitation of the crane.Method according to one of Claims 4 to 7, characterized bythe step: • measuring the temperature of the fluid medium and compensating temperature-dependent influences on the calculated mass.Method according to one of Claims 4 to 8, characterized bythe step: • bracing the ballast with a rotary platform of the crane after ballasting has taken place.Crane having a device according to one of Claims 1 to 3.

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