Mobile crane and method thereof

Abstract

This invention provides a method for improving the control of guy cable tension in guy cables of mobile cranes. [Solution] The present invention relates to a method for controlling the tension of a first guy cable 6 between the boom 12 of a mobile crane and the superstructure 21 of the mobile crane, wherein the tension of the first guy cable is automatically controlled by setting the tension of a second guy cable 16 between the boom 12 of the crane and the components 3 of the crane.

Description

Technical Field

[0001] The present invention relates to a method for controlling the tension of a first guy cable between the boom of a mobile crane and the upper structure of the mobile crane.

Background Art

[0002] It is known from the prior art that a mobile crane has a ballast for creating a counterweight for the load lifted by the mobile crane. In this case, the ballast can be formed by a mobile ballast trailer or can be arranged on the ballast trailer. The ballast can also be called derrick ballast.

[0003] Mobile cranes equipped with ballast or derrick ballast are disclosed, for example, in US11,235,961B2, EP0989087A1, JP6260591B, JP7230895B, and EP3925924A4.

[0004] It is further known that a ballast trailer of a mobile crane known from the prior art is connected to an auxiliary boom of the crane by a guy cable, and the auxiliary boom is connected to the upper structure of the crane by a further guy cable.

[0005] The guy cables are affected by the corresponding guy cable tensions. When the mobile crane is traveling, these guy cable tensions change. In particular, when the upper structure is rotated or when the mobile crane is made to travel over uneven ground, there can be a large change in the guy cable tension in the guy cable between the auxiliary boom and the upper structure.

[0006] Prior art has shown that, in order to control the guy cable tension in a guy cable, the length of the guy cable between the auxiliary boom and the ballast trailer can be adjusted by a ballast lifting cylinder located within the guy cable, thereby allowing the ballast trailer or the ballast placed on the ballast trailer to be lifted or lowered, and / or thereby changing the force that the ballast trailer introduces into the auxiliary boom via the guy cable. [Overview of the project]

[0007] The ballast lifting cylinders are controlled manually by the operator via four control elements on the mobile crane's dashboard.

[0008] These four operating elements are shown in Figure 2, which illustrates an excerpt from the mobile crane operating manual. Similarly, Figure 2 provides a functional description of these four operating elements.

[0009] When the "raise derrick ballast" and "lower derrick ballast" operation elements are activated, both ballast lifting cylinders operate in the same manner.

[0010] Given this background, the object of the present invention is to provide a method that can improve the control of guy cable tension in guy cables of mobile cranes.

[0011] This objective is achieved by a method having the features of independent claim 1. A configuration preferred to the present invention is the subject of the dependent claims.

[0012] Therefore, according to the present invention, the first guy cable tension is automatically controlled by setting a second guy cable tension in the second guy cable between the crane boom and the crane components.

[0013] Preferably, the method is performed by a computer.

[0014] Preferably, the component is a ballast trailer.

[0015] Ballast trailers can be realized by loading ballast onto a "Self-Propelled Modular Transporter" (SPMT). The ballast trailer may also be self-propelled.

[0016] Preferably, the control of the first guy cable tension and / or the setting of the second guy cable tension are configured to be performed while the mobile crane is traveling, after the mobile crane has traveled, and during and / or after the rotation of the superstructure.

[0017] Preferably, one or more lifting elements, particularly hydraulic cylinders, are arranged on the second guy cable, and the tension of the second guy cable is set by setting the length of the lifting element or group of lifting elements, thereby setting the length of the second guy cable.

[0018] Hydraulic cylinders can also be called ballast lifting cylinders.

[0019] Preferably, the length of the second guy cable is changed by only a very small amount, for example, on the order of centimeters or decimeters.

[0020] In addition, or alternatively, the control (adjustment) of the first guy cable tension may also be performed in the form of open-loop control of the first guy cable tension, and the second guy cable tension, specifically the length of the second guy cable, may be set manually by the operator.

[0021] In other words, preferably, the tension of the second guy cable can be set by setting or changing the length of the lifting element or a group of lifting elements and / or the second guy cable.

[0022] Preferably, it is carried out such that the automatic control of the first cable tension starts after a command from the operator of the mobile crane and / or after release by the control unit of the mobile crane.

[0023] Preferably, one or more measuring elements, in particular measuring sensors, are arranged on the first cable, which are designed and arranged to measure the first cable tension.

[0024] Preferably, the first cable tension is controlled within a set value or a range of set values, and / or the set value or the range of set values is defined by learning the measured value of the first cable tension.

[0025] Preferably, during control, the second cable tension is maintained within a predetermined value range, in particular depending on the first cable tension.

[0026] Preferably, the first and / or second cable tensions are held within a defined range.

[0027] Preferably, with the measured value of the first cable tension as the actual value, a predetermined numerical value or range of numerical values of the first cable tension as the set value or range of set values, and adjustable values of the second cable tension and / or the length of the second cable as the manipulated variables, the control of the first cable tension is carried out within a control loop.

[0028] Preferably, the boom is an auxiliary boom or a derrick boom.

[0029] The invention relates to a mobile crane, in particular a crawler crane, comprising a boom, a superstructure, and components, in particular a ballast trailer, where a first cable is provided between the boom and the superstructure, a second cable is provided between the boom and the components, and the mobile crane comprises means designed to carry out the method according to the invention. Relates to a mobile crane.

[0030] Preferably, no additional components are required to implement the present invention in a mobile crane known from the prior art.

[0031] Preferably, the present invention improves the operational convenience of a mobile crane and provides added value in terms of operating speed.

[0032] By controlling or setting the second guy cable tension, specifically by setting the length of the ballast hoisting cylinder, the first guy cable tension is continuously monitored and maintained. Therefore, preferably, there is no longer a need to interrupt the slewing and / or traveling operations of the mobile crane in order to manually modify the length of the ballast hoisting cylinder.

[0033] Preferably, the availability of the mobile crane is improved. This is because, in the method according to the present invention, there is no risk of inadvertently exceeding the cut-off limit of the first guy cable tension and / or the hydraulic cut-off limit at the backstop of the main boom and / or the backstop of the auxiliary boom. Normally, when the cut-off limit is exceeded, all traveling or slewing operations of the mobile crane will stop. Therefore, when the method according to the present invention is executed during the operation of the mobile crane, preferably, the stop commands issued by the crane controller are reduced.

[0034] It should be noted here that the words "a" and "an" do not necessarily refer to only one element. This is one possible embodiment, but it is also possible to specify a plurality of elements. Similarly, the use of the plural form also includes the existence of the corresponding singular elements, and conversely, the singular form also includes a plurality of corresponding elements. Furthermore, all features of the present invention described in this specification may be combined with each other as necessary, or the features may be claimed independently of each other.

[0035] Further advantages, features, and effects of the present invention will become apparent from the following description of the preferred embodiments with reference to the drawings. In the drawings, the same or similar components are denoted by the same reference numerals. [Brief explanation of the drawing]

[0036] [Figure 1] Figure 1 is a schematic diagram of an embodiment of the mobile crane according to the present invention. [Figure 2] Figure 2 is a table showing the operating elements for a conventional mobile crane and a description of their functions. [Modes for carrying out the invention]

[0037] In the crawler crane type shown in Figure 1, the load 7 is suspended from the main boom 8 by a hoisting rope 20.

[0038] The main boom 8 is connected to the auxiliary boom 12 by the main boom guy cable 10 and is tiltable.

[0039] The auxiliary boom 12 is connected to the superstructure 21 by a first guy cable 14.

[0040] In addition, the auxiliary boom 12 is also connected to the ballast trailer 3 by a second guy cable 16. A second guy cable tension F2 is generated in the second guy cable 16, which is schematically shown by the arrow labeled reference numeral 23 in Figure 1.

[0041] The second guy cable 16 has two ballast lifting cylinders 4 arranged in parallel as lifting elements. One of the ballast lifting cylinders 4 is positioned on the left, and the other ballast lifting cylinder 4 is positioned on the right. The length of the ballast lifting cylinders 4 is variable, and as a result, the length of the second guy cable 16 is also variable.

[0042] The ballast trailer 3 is kept at a constant distance from the crawler crane 1 by the guide 17.

[0043] The second guy cable tension F2 is related to the force absorbed by the weight of the ballast trailer 3 after load 7 introduces a right-rotating moment to the boom system in Figure 1.

[0044] The crawler crane 1 has a crane controller 18.

[0045] The first guy cable tension F1 generated in the first guy cable 14 due to the load 7 is schematically represented by the arrow labeled reference numeral 6 in Figure 1. The first guy cable tension F1 is measured by two tension measuring sensors 5, each having two measuring cells, and processed by the crane controller 18.

[0046] Even if the load 7 remains constant, the tension F1 of the first guy cable can be changed by altering the angle of the main boom, schematically shown by the curved arrow of reference numeral 11 in Figure 1, or by altering the angle of the auxiliary boom, schematically shown by the curved arrow of reference numeral 15 in Figure 1, or by changing the length of the second guy cable 16 using the ballast lifting cylinder 4.

[0047] The crane controller 18 has a ballast automatic control function programmed as a control program. This ballast automatic control function includes commands for performing the method according to the present invention on the mobile crane when ballast automatic control is performed.

[0048] Automatic ballast control can be performed by the crane controller 18. When the crawler crane 1 is traveling on the crawler lower structure 2, and when the upper structure 21 of the crawler crane 1 is rotated by the slewing device 19 to which the ballast trailer 3 is attached, the automatic ballast control assists the operator of the crawler crane 1.

[0049] The ballast automatic control generates control commands, and these control commands cause the ballast lifting cylinders 4 to automatically follow the changes as needed, i.e., their lengths are changed.

[0050] The ballast automatic control is a support program to assist the slewing and travel of the crawler crane 1. If the operator of the crawler crane 1 selects it, the crane controller 18 activates its function under certain conditions. For example, one condition is that the crawler crane 1 is operational, i.e., prepared to lift the load 7. Another condition is that the load limiting operation has not been stopped by the crane controller 18.

[0051] For example, after automatic ballast control is selected by operating a switch, the automatic ballast control function saves the current first guy cable tension F1 provided by the crane controller 18. The first guy cable tension F1 is then programmed for automatic ballast control.

[0052] The first guy cable tension F1 consists of multiple components that interact to keep the entire boom system, including the main boom 8 and auxiliary boom 12, stable and secure. This means that the entire boom system will not tilt forward in the direction of the load 7, nor backward in the direction of the ballast trailer 3.

[0053] By contracting the ballast lifting cylinder 4, the length of the second guy cable 16 is shortened. The tension F2 of the second guy cable increases as it further resists the rightward rotation moment caused by the load 7 in Figure 1, while the tension F1 of the first guy cable decreases.

[0054] By extending the ballast lifting cylinder 4, the length of the second guy cable 16 increases, the tension F2 of the second guy cable decreases, and the tension F1 of the first guy cable increases.

[0055] Preferably, in the method according to the present invention, a change occurs in the tension F1 of the first guy cable due to changing the length of the second guy cable 16, and a change occurs in the tension F2 of the second guy cable as a result.

[0056] The first guy cable tension F1 and the second guy cable tension F2 together form a leftward rotation moment in Figure 1, which counteracts the rightward rotation moment in Figure 1 caused by the load 7. Preferably, the first guy cable tension F1 is maintained within a certain range. If the first guy cable tension F1 is too large, there is a risk that the entire crawler crane 1 will tilt forward and fall over to the ground beyond its tipping point. A large first guy cable tension F1 also acts through the slewing device 19 along with its moment. Therefore, the slewing device 19 is subjected not only to a compressive load but also to a moment superimposed on that compression. If the first guy cable tension F1 is too small, there is a risk that the entire boom system will fall backward, and the backstops 9 and 13 need to hold their corresponding booms in place.

[0057] The tension F2 of the second guy cable must also be maintained within the specified limits. If the tension F2 of the second guy cable increases, the moment of the slewing device 19 is reduced, and instead the pressure transmitted to the slewing device 19 increases.

[0058] Preferably, the crane controller 18 does not define a predetermined range for the second guy cable tension F2. The entire ballast trailer 3 or the ballast placed on the ballast trailer 3 can be fully hoisted, resulting in the second guy cable tension F2 being at its maximum, or the ballast trailer 3 or the ballast placed on the ballast trailer 3 can be fully lowered, resulting in the second guy cable tension F2 being at its minimum. Independent open-loop control or setting of the second guy cable tension F2 is preferably not possible. This is because the second guy cable tension F2 directly affects the first guy cable tension F1. Therefore, the defined limit of the second guy cable tension F2 is preferably defined by the limit of the first guy cable tension F1, or indirectly by the first guy cable tension F1.

[0059] Furthermore, the direction of action that defines the lever arms of the first guy cable tension F1 and the second guy cable tension F2 must also be considered. The lever arm of the second guy cable tension F2 is more efficient than the lever arm of the first guy cable tension F1.

[0060] After learning the first guy cable tension F1, when the crawler crane 1 with the ballast trailer 3 is driven over rough terrain by the crawler substructure 2 or slewing by the slewing device 19, the ballast automatic control calculates whether the ballast lifting cylinder 4 should be extended or retracted, i.e., whether the guy cable 16 should be lengthened or shortened, by comparing the stored first guy cable tension F1 with the current first guy cable tension F1. Once the result is obtained, the ballast lifting cylinder 4 is driven in the corresponding direction. This calculation is performed continuously to always maintain the previously learned first guy cable tension F1. This is done by a known PI controller.

[0061] In the guy cable 14, no adjustment is made to the pulley device shown in Figure 1.

[0062] In the absence of effective automatic ballast control, the operator can manually set the length of the second guy cable 16 using the ballast lifting cylinder 4 via four operating elements on the dashboard of the crane operator's cab, as shown in Figure 2, so that the first guy cable tension F1 can be maintained within a desired range during slewing or traveling. The left and right ballast lifting cylinders 4 can be extended or retracted using the four operating elements on the dashboard.

[0063] If the operator does not manually and continuously readjust the ballast lifting cylinder 4, the tension of the second guy cable F2 will be affected when traveling over uneven terrain, and consequently, the tension of the first guy cable F1 will also be affected.

[0064] The length of the second guy cable 16 then affects the angle of the main boom 11 and the angle of the auxiliary boom 15 in the form of an angle change. This effect is prevented or kept within a narrow range by the backstop 9 of the main boom and the backstop 13 of the auxiliary boom.

[0065] Backstops 9 and 13 consist of hydraulic cylinders attached to the main boom 11 and auxiliary boom 12 of the crawler crane 1. These cylinders extend or retract depending on the applied force in order to stabilize the crawler crane 1.

[0066] As the ballast trailer 3 enters the recess 22, the entire boom system, including the main boom 8 and auxiliary boom 12, is pulled backward, resulting in a redistribution of force between the second guy cable tension F2 and the first guy cable tension F1. This force redistribution is made possible by the fact that the guide 17 keeps the ballast trailer 3 at a constant distance from the crawler crane 1.

[0067] The redistribution of force directly affects the first guy cable tension F1 on the one hand, and also affects the backstop 9 of the main boom and the backstop 13 of the auxiliary boom on the other hand.

[0068] Preferably, the first guy cable tension F1 is within a specified range between the minimum and maximum forces. These limits are defined by a load chart and monitored by the crane controller 18. If these limits are exceeded, the travel or slewing operation will be stopped.

[0069] As a result of the redistribution of unnecessary force, backstops 9 and 13 are compressed, the oil present in the backstops is compressed, and the hydraulic pressure rises. In this case, the hydraulic pressure in backstops 9 and 13 may exceed the maximum allowable hydraulic pressure, resulting in the cessation of the driving or turning operation. The hydraulic pressure is measured and monitored. However, in the ballast automatic control or method according to the present invention, the hydraulic pressure is neither an operating variable nor a control variable. The hydraulic pressure is a result of the control by the ballast automatic control.

[0070] After the ballast automatic control is turned on, the ballast automatic control takes over the readjustment of the ballast lifting cylinder 4.

[0071] Since the first guy cable tension F1 remains constant or within a certain range, the operator can concentrate more on the slewing and traveling operations. The first guy cable tension F1 never reaches either the minimum required tension or the maximum allowable tension, and the crawler crane 1 does not stop traveling or slewing.

[0072] Similarly, the hydraulic pressure at the backstop 9 of the main boom and the backstop 13 of the auxiliary boom remains constant or within narrow limits. This is because the redistribution of force in the boom system due to uneven terrain is minimal.

[0073] Figure 2 shows four operating elements for manual control of the first guy cable tension F1 and manual setting of the second guy cable tension F2. These operating elements are designed as push buttons.

[0074] Alternatively, or in addition to, the operator of the crawler crane 1 can drive the ballast lifting cylinder 4 by the four operating elements shown in Figure 2.

[0075] By turning on and holding the first operating element from the top in Figure 2, the ballast lifting cylinder 4 is retracted, thereby lifting the ballast trailer 3 or the ballast placed on the ballast trailer, and increasing the tension F2 of the second guy cable. When the operating element is released, the lifting is interrupted.

[0076] By turning on and holding the second operating element from the top in Figure 2, the ballast lifting cylinder 4 is extended, thereby lowering the ballast trailer 3 or the ballast placed on the ballast trailer, and reducing the tension F2 of the second guy cable. Releasing the operating element interrupts the descent.

[0077] By turning on and holding the third operating element from the top in Figure 2, the left ballast lifting cylinder 4 is locked. Releasing the operating element releases the left ballast lifting cylinder 4.

[0078] By turning on and holding the fourth operating element from the top in Figure 2, the ballast lifting cylinder 4 on the right side is locked. Releasing the operating element releases the ballast lifting cylinder 4 on the right side. [Explanation of Symbols]

[0079] 1 Crawler crane 2. Crawler undercarriage 3 ballast trailers 4. Ballast lifting cylinder 5. Sensor for measuring tension 6. First guy cable tension F1 7 Load 8 Main Boom 9. Main boom backstop 10 Main boom guy cables 11. Main boom angle 12 Auxiliary boom 13. Backstop for auxiliary boom 14. First Guy Cable 15. Angle of the auxiliary boom 16. Second Guy Cable 17 Guide 18 Crane Controller 19. Swivel device 20. Hoisting rope 21 Superstructure 22 Indentation 23. Second Guy Cable Tension F2

Claims

1. A method for controlling the tension of a first guy cable between the boom of a mobile crane and the superstructure of a mobile crane, The tension of the first guy cable is automatically controlled by setting a second guy cable tension on the second guy cable between the boom of the crane and the components of the crane. method.

2. The aforementioned component is a ballast trailer. The method according to claim 1.

3. The control of the first guy cable tension and / or the setting of the second guy cable tension are performed while the mobile crane is traveling, after the mobile crane has traveled, and during and / or after the rotation of the superstructure. The method according to claim 1 or 2.

4. One or more lifting elements, particularly hydraulic cylinders, are arranged on the second guy cable, and the setting of the tension of the second guy cable is performed by setting the length of the one or more lifting elements, specifically the second guy cable. The method according to any one of claims 1 to 3.

5. The automatic control of the first guy cable tension begins after a command from the operator of the mobile crane and / or after release by the control unit of the mobile crane. The method according to any one of claims 1 to 4.

6. One or more measuring elements, in particular a measuring sensor, are arranged on the first guy cable, and the measuring sensor is designed and positioned to measure the tension of the first guy cable. The method according to any one of claims 1 to 5.

7. The first guy cable tension is controlled to a set value or within a set value range, and / or the set value or set value range is defined by learning the measured values ​​of the first guy cable tension. The method according to any one of claims 1 to 6.

8. During control, the tension of the second guy cable is maintained within a predetermined range, particularly in accordance with the tension of the first guy cable. The method according to any one of claims 1 to 7.

9. The control of the first guy cable tension is performed within a control loop, with the measured value of the first guy cable tension being the actual value, a predetermined numerical value or range of numerical values ​​of the first guy cable tension being the set value or range of set values, and an adjustable value of the second guy cable tension and / or the length of the second guy cable being the control variable. The method according to any one of claims 1 to 8.

10. The boom is an auxiliary boom or a derrick boom. The method according to any one of claims 1 to 9.

11. A mobile crane, particularly a crawler crane, comprising a boom, superstructure, and components, especially a ballast trailer, A first guy cable is provided between the boom and the superstructure, a second guy cable is provided between the boom and the component, and the mobile crane is equipped with means designed to perform the method according to any one of claims 1-10. Mobile crane.

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