Lifting device, in particular a mobile crane or a cable-operated excavator, having an apparatus for monitoring the raising and lowering procedures of a boom system and corresponding method

Abstract

The invention relates to a lifting device, in particular a mobile crane or a cable-operated excavator, having an apparatus for monitoring the raising and lowering procedures of a boom system of the lifting device.

Claims

1. A lifting device (1), having an apparatus for monitoring raising and lowering procedures of a boom system of the lifting device (1), the apparatus comprising a device for detecting loads increasing an overturning moment of the lifting device (1); a device for detecting loads stabilizing or reducing the overturning moment of the lifting device (1); a control unit configured to calculate a limit holding force (FGrenz) for a holding line of the boom system of the lifting device (1) from the detected loads; and a device for detecting actual holding force of the holding line, wherein the control unit is configured to compare the limit holding force (FGrenz) and the actual holding force.

2. A lifting device (1) in accordance with claim 1, wherein the control unit is configured to output at least one signal in dependence on the comparison between the limit holding force (FGrenz) and the actual holding force.

3. A lifting device (1) at least in accordance with claim 2, wherein the at least one signal is a representation of the current utilization with respect to permitted utilization for a machine operator on a monitor of the lifting device and/or for stopping a movement of the lifting device (1).

4. A lifting device (1) in accordance with claim 1, wherein the device for detecting the loads increasing the overturning moment, detects the weight of the boom system and the wind force on a boom system of the lifting device (1).

5. A lifting device (1) in accordance with claim 1, wherein the device for detecting the loads stabilizing or reducing the overturning moment, detects the weight of a carrier unit of the lifting device.

6. A lifting device (1) in accordance with claim 1, wherein a sensor system for detecting the current geometry of the lifting device (1) is provided; and the control unit is a control computer of the lifting device (1) or an external computer.

7. A lifting device (1) in accordance with claim 1, wherein the device for detecting the actual holding force of the holding line, comprises at least one force measurement tab and/or at least one force measurement axis.

8. A lifting device (1) in accordance with claim 1, wherein the control unit is configured to calculate the loads increasing the overturning moment simultaneously for a wide range of positions of the boom system in addition to current position of the boom system.

9. A lifting device (1) in accordance with claim 1, wherein the control unit is configured not to stop a movement or a direction of movement of the lifting device (1) as long as the limit holding force (FGrenz) is not exceeded or to selectively release the movement or the direction of movement again after a stop due to an exceeding of the limit load, when maximum permitted load at a lifting hook hook increases with the direction of movement.

10. A lifting device (1) in accordance with claim 1, which is a mobile crane or a cable-operated excavator.

11. A method of monitoring the raising and lowering procedures of a boom system of a lifting device (1), comprising the steps of: detecting loads increasing overturning moment of the lifting device (1); detecting the loads stabilizing or reducing the overturning moment of the lifting device (1); calculating a limit holding force (FGrenz) for a holding line of a main boom (2) of the lifting device (1) from the detected loads, by a control unit; detecting actual holding force of the holding line; and comparing the limit holding force (FGrenz) and the actual holding force by the control unit.

12. A method in accordance with claim 11, wherein the lifting device (1) is a mobile crane or a cable-operated excavator.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Further details and advantages of the invention are explained with reference to the embodiment shown by way of example in the FIGURE.

(2) The only FIG. 1 shows an overview of the forces acting on the lifting device 1 for the example of a crawler crane 1 having a main boom 2 and a luffing needle 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(3) The arrow 31 designates the weight of the luffing needle 3; the arrow 32 designates the wind force acting on the load L; the arrow 21 designates the weight of the main boom 2; the arrow 22 designates the wind force acting on the boom system consisting of the main boom 2 and the optional luffing boom 3; and the arrow 11 designates the weight of the carrier unit or to the lifting device 1. The unmarked arrows indicate the respective distances of the forces and/or centers of mass of the components with respect to an overturning edge and/or on the boom pivot point 12. The moments with respect to the boom pivot point 12 can be detected or calculated with reference to the distances and the forces.

(4) In the embodiment of the FIGURE, the loads increasing the overturning moment act counter clockwise and the loads stabilizing the overturning moment act clockwise with respect to the boom pivot point 12.

(5) The limit holding force FGrenz represents the maximum permitted force in the holding line that may be reached during the raising or lowering procedures without an overturning of the lifting device occurring. It corresponds to 100% of the permitted utilization while considering the specifications through relevant standards with respect to stability.

(6) If the individual balance points and wind areas in particular of the luffing boom 3 and of the main boom 2 and the corresponding load engagement points for the given crane configuration of the control are known, the calculation of the maximum permitted load L at the hook and of the limit force FGrenz can advantageously take place online directly on the control computer of the crane.

(7) The current geometry of the machine (boom angle, angle of rotation) required for a calculation carried out on the control can be permanently detected by corresponding sensor systems (inclinometer, rotary encoder) on the machine or can be manually input into the control computer.

(8) Alternatively, the calculation of the maximum permitted load L at the hook and of the limit force FGrenz can take place offline via an external computer. The limit force FGrenz in this case has to be transferred to the control for every boom position. The current geometry of the machine (boom angle, angle of rotation) can also be measured permanently in this case by a corresponding sensor system on the machine.

(9) The actual current force F in the holding line is measured by a corresponding sensor system (force measurement tabs or force measurement axes) on the machine and are compared by the control computer on the machine with the calculated current limit holding force FGrenz and are advantageously displayed to the machine operator on the monitor as the current utilization with respect to the permitted utilization.

(10) If it is found that the current force F is or could be >FGrenz, i.e. the utilization is >100%, those movements of the boom system that result in a further increase of the utilization and thus in the overload can be stopped by the control unit.

(11) The direction of movement or the movement that is to be stopped or released is determined as follows:

(12) The control unit calculates the maximum permitted load at the hook simultaneously for a wide range of positions in addition to the current position of the boom system. Permitted directions of movement are defined by comparing the results. A permitted direction of movement is present when the maximum permitted load at the hook increases with this direction of movement.

(13) After a stop due to an exceeding of the limit load, permitted directions of movement of the lifting device are selectively released again by the control unit.

(14) The calculation of the range in addition to the current position can advantageously take place online on the control computer of the machine or alternatively offline on an external computer. The directions of movement to be released in this case have to be transferred to the control for every boom position.