OPERATING METHOD FOR A CRANE INSTALLATION, IN PARTICULAR FOR A CONTAINER CRANE

Abstract

A crane installation, in particular a container crane, has a trolley for transporting a load. The load to be transported determines loading of the trolley. The crane installation has a travel drive connected to the trolley and a trolley controller connected to the travel drive for controlling travel movements of the trolley. The trolley controller controls acceleration operations and braking operations during the travel movement of the trolley as a function of the loading of the trolley and the maximum available drive force of the travel drive. At least one acceleration operation has two sections with positive acceleration values of equal magnitude and an intermediate section with negative acceleration values of the same magnitude, and at least one braking operation has two sections with negative acceleration values of equal magnitude and an intermediate section with positive acceleration values of the same magnitude.

Claims

1.-12. (canceled)

13. An operating method for a crane installation, in particular for a container crane, with a trolley for transporting a load, said method comprising: determining loading of the trolley based on the load to be transported; and controlling travel movements of the trolley with a travel drive connected to the trolley and a trolley controller connected to the travel drive, wherein the travel movements comprise acceleration operations and braking operations during the travel movements of the trolley as a function of the loading of the trolley and a maximum available drive force of the travel drive, wherein at least one of the acceleration operations comprises two sections having positive acceleration values of equal magnitude and an intermediate section having a negative acceleration value of a magnitude equal to the magnitude of the positive acceleration values, and wherein at least one of the braking operations comprises two sections having negative acceleration values of equal magnitude and an intermediate section having a positive acceleration value of a magnitude equal to the magnitude of the negative acceleration values.

14. The method of claim 13, further comprising acquiring the loading of the trolley with a load measuring device connected to the trolley.

15. The method of claim 13, wherein the travel movement of the trolley comprises at least one acceleration section and at least one braking section, and wherein the positive and/or negative acceleration values depend on the loading.

16. The method of claim 13, wherein a maximum acceleration of the travel movement is determined from a maximum drive force of the travel drive and a minimum loading of the trolley.

17. The method of claim 13, further comprising: determining a maximum acceleration of the travel movement by a maximum drive force of the travel drive and a maximum loading of the trolley; and increasing the maximum acceleration at a current loading compared to the maximum acceleration at the maximum loading by a factor K.sub.accel, wherein K.sub.accel=m.sub.load.sub._.sub.max/m.sub.load.sub._.sub.curr with m.sub.load.sub._.sub.curr<, wherein m.sub.load.sub._.sub.max is the maximum loading and m.sub.load.sub._.sub.curr is the current loading.

18. The method of claim 13, further comprising compensating oscillation of the load when the load reaches a target position.

19. The method of claim 13, further comprising compensating oscillation of the load when the load reaches a maximum travel speed.

20. The method of claim 13, further comprising operating an electric motor of the travel drive at at least two different operating points during the travel movement.

21. The method of claim 20, wherein at least one of the operating points is located in a field-weakening range of the electric motor.

22. The method of claim 21, further comprising after attaining a rated rotational speed, operating the electric motor in the field-weakening range to increase the speed of the travel movement

23. A computer program stored on a machine-readable con-transitory storage medium and comprising machine code, wherein the machine code, when loaded into a memory of a trolley controller and executed by the trolley controller, causes the trolley controller to receive loading of a trolley controlled by the trolley controller, and control acceleration operations and braking operations during a travel movement of the trolley as a function of the loading of the trolley and a maximum available drive force of the travel drive, wherein at least one of the acceleration operations comprises two sections having positive acceleration values of equal magnitude and an intermediate section having a negative acceleration value of a magnitude equal to the magnitude of the positive acceleration values, and wherein at least one of the braking operations comprises two sections having negative acceleration values of equal magnitude and an intermediate section having a positive acceleration value of a magnitude equal to the magnitude of the negative acceleration values.

24. The computer program of claim 23, wherein the trolley controller further determines a maximum acceleration of the travel movement from a maximum drive force of the travel drive and a minimum loading of the trolley.

25. The computer program of claim 23, wherein the trolley controller further determines a maximum acceleration of the travel movement from a maximum drive force of the travel drive and a maximum loading of the trolley, and increases the maximum acceleration at a current loading compared to the maximum acceleration at the maximum loading by a factor K.sub.accel, wherein K.sub.accel=m.sub.load.sub._.sub.max/m.sub.load.sub._.sub.curr with m.sub.load.sub._.sub.curr<, wherein m.sub.load.sub._.sub.max is the maximum loading and m.sub.load.sub._.sub.curr is the current loading.

26. The computer program of claim 23, wherein the trolley controller further compensates oscillations of the load when the load reaches a target position or when the load reaches a maximum travel speed.

27. The computer program of claim 23, wherein the trolley controller further operates an electric motor at at least two different operating points during the travel movement.

28. The computer program of claim 27, wherein the trolley controller further operates the electric motor in a field-weakening range.

29. The computer program of claim 28, wherein the trolley controller operates the electric motor in a field-weakening range after attaining a rated rotational speed in order to increase the speed of the travel movement.

Description

[0028] FIG. 1 shows a cutout of a container crane installation, as is used for example for loading and unloading a ship located at a dock, with a horizontally oriented jib 2. Guided on the jib 2 is a traveling trolley 4subsequently only referred to as trolley 4for transshipment of a load. The load may be present in the form of one or even two container 6, for example. The trolley 4 is connected to a travel drive 8. This is preferably a rope-guided travel drive 8 with two electric motors 10. The two electric motors 10 are, for example, mechanically connected to the trolley 4 via a rope drive 12 such that they are opposing in the direction of movement. The trolley 4 runs on the jib 2 on rollers or wheels 14. Rope-guided travel drives 8 permit high acceleration values, which are not limited by a friction value between the roller 14 and a rail guidance of the jib 2.

[0029] Arranged in the trolley 4 is a hoisting gear (not shown here) for raising and lowering the load 6 to be transported. The hoisting gear comprises hoist rope 16, which is fastened at its ends to a headblock 18. The headblock 18 connects a spreader 20 to the hoisting gear. The spreader 20 grasps the load 6 for transportation.

[0030] The trolley 4 thus enables, via the hoisting gear, vertical movements of the load 6 in the direction of the double-ended arrow 22 and, via the electric motors 10, horizontal travel movements of the load 6 in the trolley direction (double-ended arrow 24).

[0031] The hoisting gear of the trolley 4 comprises at least one load measuring device 26, in accordance with FIG. 1 two load measuring devices 26. The load measuring devices 26 may be realized by different technologies, such as ring force transducers, load measuring axes, pressure force transducers or even load measuring bolts. In the present exemplary embodiment, the load measuring devices 26 are embodied as ring force transducers, which are arranged on the rope end points of the hoist rope 16. As measuring washers they simultaneously serve the load acquisition and act as overload protection.

[0032] The load 6 currently to be transported on the travel trolley 4 is acquired via the load measuring devices 26 and is passed on to trolley controller 28. The trolley controller 28 determines control signals for the travel drive 8 from the current load values, as is described in further detail below. The trolley controller 28 is generally embodied as a software-programmable device. Its functionality is determined in this case by a computer program, by which the trolley controller 28 is programmed. The computer program comprises machine code which can be executed by the trolley controller 28. The execution of the machine code by the trolley controller causes the operation of the crane installation explained in more detail below.

[0033] The crane installation is equipped for automatic operation, which enables a target specification for the trolley movements. It is therefore not necessary for the trolley 4 to have a crane driver cabin. Instead, the trolley 4 has sensors for acquiring the position of the load 6 to be transported, the measurement signals of which are fed to the trolley controller 28 for automatic controlling of the travel paths of the trolley 4. The picking up and setting down of the load is carried out by a remote control desk 30, which enables the remote control of the trolley movement.

[0034] The trolley controller 28 determines from the current value of the load m.sub.load.sub._.sub.curr a loading factor K.sub.load of the crane. The loading factor K.sub.load is defined by the relationship of the current loading m.sub.load.sub._.sub.curr to the maximum possible loading m.sub.load.sub._.sub.max of the crane on the basis of the drive design, i.e. the rated loading or rated load. Therefore, expressed as a formula:

K.sub.load=m.sub.load.sub._.sub.curr/m.sub.load.sub._.sub.max(1)

[0035] The value of the loading factor K.sub.load is always less than or equal to one.

[0036] Associated with the rated load or rated loading of the crane, which is designed as the maximum loading m.sub.load.sub._.sub.max, is a maximum acceleration value a.sub.max.sub._.sub.rated, which is determined by the rated drive force of the travel drive 8, at which changes in speed take place within the travel path of the trolley 4.

[0037] The inventive idea substantiated in the trolley controller 28 is now of increasing the acceleration a.sub.max.sub._.sub.rated to the value a.sub.max.sub._.sub.adept at a lower loading of the crane than the rated loading m.sub.load.sub._.sub.max (K.sub.load<1), as permits the rated drive force of the travel drive 8. The factor for increase in acceleration is the reciprocal of the loading factor:

K.sub.accel=1/K.sub.load(2)

[0038] This means that the current maximum possible acceleration at a loading of the crane which is lower than the rated loading increases accordingly:

a.sub.max.sub._.sub.adapt=a.sub.max.sub._.sub.rated*K.sub.accel=a.sub.max.sub._.sub.rated/K.sub.load(3)

[0039] With the modification of the maximum acceleration a.sub.max.sub._.sub.rated by the loading factor K.sub.load or acceleration factor K.sub.accel, it is achieved that for each travel operation travel always takes place at the maximum possible acceleration a.sub.max.sub._.sub.adapt regardless of the load to be transported.

[0040] FIG. 2 shows the relationship between the magnitude of the moved mass and the load-dependent acceleration a.sub.max.sub._.sub.curr described above. Here, the load-dependent acceleration a.sub.max.sub._.sub.curr is plotted on the x-axis and the magnitude of the moved mass is plotted on the y-axis. The moved mass results from the sum of fixed mass of the trolley 4, headblock 18 with hoist ropes 16 and spreader 20 plus the variable mass, for example in the form of the container 6 to be transported. At the maximum moved mass, the travel drive 8 can bring about the maximum acceleration a.sub.max.sub._.sub.rated. This operating state BP1 is characterized in the diagram by the upper start of a working line 34. The maximum possible acceleration during an empty run a.sub.max.sub._.sub.empty, i.e. only the fixed moved mass without a load to be transported, is specified by the operating point BP2 at the lower end point. Between these two operating points BP1 and BP2, it is possible to travel at a higher acceleration a.sub.max.sub._.sub.adapt according to the magnitude of the reduced load with respect to the maximum load. The higher acceleration a.sub.max.sub._.sub.adapt lies between the maximum acceleration a.sub.max.sub._.sub.rated at full loading and the maximum acceleration during an empty run a.sub.max.sub._.sub.empty, see in the diagram the operating range 38 on the x-axis.

[0041] FIG. 3 shows three typical speed profiles 40, 42, 44 of the trolley 4 on a given travel distance, which are simplified by comparison and result at different load states during automatic operation of the crane. On the one hand, this means that the load-dependent maximum possible acceleration a.sub.max.sub._.sub.adapt already explained above is used for building up speed and for braking and, on the other hand, the load vibration or load oscillation is also taken into consideration in the motion characteristic. The speed profile 40 results during a loading of the crane at maximum loading, the speed profile 42 results at a partial loading of the crane, and the speed profile 44 results during an empty run of the crane 4.

[0042] What is typical for all three speed profiles 40, 42, 44 is that following an increase in speed up to a first maximum speed 46 (local maximum), which however is lower than the generally possible maximum speed v.sub.max, there follows a reduction in speed up to a local minimum 48, which is again followed by a maximum possible increase in speed at a.sub.max up to the maximum possible speed v.sub.max. Running symmetrically to this is the speed profile in the braking phase or in the braked section of the travel movement up to the target position. The changes in speed are designed such that the oscillation of the load is settled at least at the target position and preferably also when attaining the maximum speed v.sub.max.

[0043] The speed profile 40 is also set in conventional crane installations when only a partial loading is present or even when an empty run is performed. By contrast, in the context of the present invention, during a lower loading the acceleration is increased to the extent that the maximum motor drive force is used for acceleration. The application of the present invention therefore results in a time saving compared to a conventional trolley controller at a partial loading, which assumes the variable t.sub.amax during an empty run.

[0044] As is known, in various electric motors, such as synchronous motors, asynchronous motors. DC motors etc. for example, it is possible to achieve an increase in the rated rotational speed by reducing the magnetic flux in the excitation winding. This operating range is also referred to as the field-weakening range. FIG 4 shows the typical course of a motor characteristic curve M(n), which shows the generated torque M as a function of the rotational speed n, with a first operating point AP1 in normal field operation and a second operating point AP2 in field-weakening operation. At operating point AP1, a moment M.sub.1 is generated at a rotational speed of n.sub.1 and at operating point AP2 a moment M.sub.2 is generated at a rotational speed n.sub.2. At operating point AP2, although the generated torque is reduced, the rotational speed is simultaneously increased.

[0045] By using electric motors and the operation thereof in the field-weakening range, it is possible to increase the time saving during the transshipment of cargo even further, in particular with long travel distances of the trolley 4. A typical case of this is shown in FIG. 5. Longer travel distances can then be traveled at a constant, increased speed. With an electromotive travel drive without field-weakening operation or without using the field-weakening operation, it is possible for a speed profile 50 to be realized for example, in which a maximum travel speed v.sub.1 can be attained with the drive moment M.sub.1. A further time saving during the transshipment of cargo can now be achieved if, during approach, when the rated rotational speed n.sub.1 has been attained at operating point AP1, there is a switch to the operating point AP2 of the field-weakening operation. Then, although the drive moment M.sub.2 is reduced, the maximum travel speed v.sub.2 is increased further. In a similar manner, during braking, when the travel speed v.sub.1 has been attained, there is a switch back to the operating point AP1 . This relationship is illustrated by the speed profile 52. Also represented in FIG. 5 is the time saving t.sub.vmax which can be achieved by the field-weakening operation.

[0046] FIG. 6 shows the acceleration profiles associated with the speed profiles 50 and 52. Owing to the higher drive moment M.sub.1 available during normal operation, an acceleration value of a.sub.1 can be attained. The acceleration value a.sub.2 which can be achieved in field-weakening operation is lower than in normal operation.

[0047] In very long travel distances, by way of the further cascading of operating points in field-weakening operation, a further increased end speed and thus a further time saving can be attained during cargo transport.

[0048] The present invention has many advantages. In particular, there is a greater transshipment.

[0049] Although the invention has been illustrated and described in detail with the preferred exemplary embodiment, the invention is not restricted by the examples disclosed and other variations can be derived therefrom by a person skilled in the art without departing from the protective scope of the invention.