Apparatus for compensating diagonal pull in cranes

Abstract

The invention relates to an apparatus for compensating diagonal pull in cranes having at least one boom, having a boom drive for adjusting an angle and/or a length of the boom and/or for traveling a trolley, and having a control/regulation apparatus for controlling/regulating the boom drive. The invention is further directed to a crane having a corresponding apparatus.

Claims

1. A tower crane, comprising a tower (1); a boom (2) mounted on the tower (1) to extend outwardly therefrom; a boom drive (3) arranged for adjusting an angle of the boom (2); a sensor (5) arranged for detecting the angle of the boom (2); and a control/regulation apparatus (4) arranged for controlling the boom drive (3), wherein a detected sensor value is kept constant by the control/regulation apparatus (4) and the boom drive (3) on raising and/or placing down of a load (6) by the crane (1), the sensor (5) is one of an inclinometer, an optical sensor, a length sensor for measuring deformation, a GPS sensor or a hoist rope sensor in or at a guying of the crane (1), and the ratio of the sensor value or a reference value to outreach displacement due to the deformation of the crane (1), is scaled or determined using a test weight and/or determined by calculation.

2. The crane in accordance with claim 1, wherein the boom drive (3) is at least a retraction winch (8) or a guying winch (9).

3. The crane in accordance with claim 1, wherein the boom drive (3) is a hydraulic piston-cylinder apparatus.

4. The crane in accordance with claim 1, wherein the control/regulation apparatus (4) controls the boom drive (3) on the basis of a reference value calculated from a plurality of different sensor values.

5. A tower crane, comprising a tower (1); a boom (2) mounted on the tower (1) to extend outwardly therefrom; a trolley (7) slidably mounted along the boom (2); a boom drive (3) arranged for traveling the trolley (7); a sensor (5) arranged for detecting a deformation of at least a part of the crane (1); and a control/regulation apparatus (4) arranged for controlling the boom drive (3), wherein a detected sensor value is kept constant by the control/regulation apparatus (4) and the boom drive (3) on raising and/or placing down of a load (6) by the crane (1), the sensor (5) is one of an inclinometer, an optical sensor, a length sensor for measuring deformation, a GPS sensor or a hoist rope sensor in or at a guying of the crane (1), and the ratio of the sensor value or a reference value to outreach displacement due to the deformation of the crane (1), is scaled or determined using a test weight and/or determined by calculation.

6. The crane in accordance with claim 5, wherein the boom drive (3) is at least a retraction winch (8) or a guying winch (9).

7. The crane in accordance with claim 5, wherein the boom drive (3) is a hydraulic piston-cylinder apparatus.

8. The crane in accordance with claim 5, wherein the control/regulation apparatus (4) controls the boom drive (3) on the basis of a reference value calculated from a plurality of different sensor values.

9. The crane in accordance with claim 8, wherein the reference value is a load torque calculated from outreach of the crane (1) and weight of the load (6).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

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

(2) FIG. 1a: a prior art crane of the category with a load lying on the ground;

(3) FIG. 1b: a prior art crane of the category just before the raising of a load;

(4) FIG. 1c: a prior art crane of the category just after the raising of a load;

(5) FIG. 2a: a crane with an apparatus in accordance with the invention for compensating diagonal pull with a load on the ground;

(6) FIG. 2b: a crane with an apparatus in accordance with the invention for compensating diagonal pull just before the raising of a load;

(7) FIG. 2c: a crane with an apparatus in accordance with the invention for compensating diagonal pull just after the raising of a load;

(8) FIG. 3: effective structure on the use of a crane with an apparatus in accordance with the invention;

(9) FIGS. 4a-4c: crane while raising a load;

(10) FIG. 5: characteristic of the load torque and of the outreach displacement of a crane;

(11) FIG. 6: characteristic of the load torque and of the outreach displacement of a crane with the time of the raising of a load;

(12) FIG. 7: characteristic of the output values of an absolute encoder and of the boom angle of a crane without a load and with a maximum permitted load;

(13) FIG. 8: a schematic view of a different boom inclination in accordance with a first approach; and

(14) FIG. 9: a schematic view of a different boom inclination in accordance with a second approach.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(15) FIG. 1a shows a crane 1 known from the prior art having a boom 2 that does not have an apparatus in accordance with the invention for compensating diagonal pull. The crane 1 comprises a boom drive 3 that can adjust the boom 2 and/or that can move the trolley 7. With a load 6 placed on the ground, the crane 1 is at least not loaded by the load 6 and therefore also does not have any deformations caused by the load.

(16) The term of the boom drive 3 can also mean a drive for moving the boom 2 or also any other drive provided at the crane such as a retraction winch 8 or a guying winch 9 by means of which further or different crane components can be moved.

(17) On raising the load 7 from the ground, the crane 1 is also correspondingly loaded, even while the load initially still remains on the ground or contacts the ground. This inter alia has the result of a horizontal movement of the upper crane or in particular of the boom 2 and of a corresponding diagonal pull of the rope, as FIG. 1b shows.

(18) If the load 6 rises from the ground, as shown in FIG. 1c, a diagonal position or a diagonal pull of the rope of the crane 1 results due to the horizontal movement or slewing movement of the upper crane at the time of the raising of the load 6 previously shown in FIG. 1b, which can result in load oscillation and accordingly in an outreach increase due to the load oscillation.

(19) The crane 1 shown in FIG. 2a and having an apparatus in accordance with the invention for compensating the diagonal pull initially hardly differs from the crane 1 shown in FIG. 1a from the prior art, with respective cranes being shown in n unloaded state in FIGS. 1a and 2a. If, however, the crane 1 in accordance with the invention in accordance with FIG. 2b starts to raise the load 6 while the load is still on the ground or is still in contact with the ground, the outreach of the crane 1 can be automatically reduced in accordance with the invention, whereby the diagonal pull is correspondingly reduced and an oscillation movement on a further raising of the load 6 is prevented. If the crane 1 raises the load from the ground as shown in FIG. 2c, no diagonal pull is present in accordance with the invention at that time and no load oscillation arises. For this purpose, as shown in FIG. 2b, the trolley 7 is traveled and/or the boom 2 is pivoted such that the rope has no diagonal pull or is vertically arranged.

(20) The inclination of the boom 2, the deformation on the basis of a detected length change of the boom 2 and/or the strain in the guying of the crane 1 can, for example, be detected by means of the sensor 5 shown in FIGS. 2a to 2c.

(21) At least one corresponding sensor 5 can, for example, be provided at the boom 2 or can alternatively or additionally thereto be provided at further components such as at the tower of the crane. The control/regulation apparatus 4 can detect the values detected by the sensor 5 or by the sensors 5 and can determine on their basis how the boom drive 3 is to be controlled so that no diagonal pull arises where possible.

(22) To accordingly set the control/regulation apparatus 4, that can, for example, be formed as part of the crane 1, to control the boom drive 3, a known test weight can be raised by means of the crane 1, with the detected sensor values being able to be correspondingly stored. This can be carried out at different boom angles or outreaches of the crane 1. A correspondingly prepared value table having the detected sensor values, the test weight and/or the corresponding boom angles or outreaches can be used to compensate the diagonal pull in operation of the crane 1.

(23) FIG. 3 shows a schematic representation of the effective structure on the use of a crane 1 having an apparatus in accordance with the invention. In this respect, one or more reference values are first determined that are in a clear relationship with the deformation of the crane 1 or of the steel structure of the crane 1. A value that is in particular calculated can equally be generated or detected by the interaction of two or more sensors 5. In this respect, the following sensors can be used in any desired combination and number: Load torque sensors; inclinometers in the tower and/or boom 2 of the crane 1; force sensors or a metering shaft or a tensile force sensor in the hoist rope line; outreach sensors; force sensors in the guying, in the guying rope, in the neck rope and/or in the retraction rope; GPS sensors; optical sensors such as a camera; force sensors and/or strain sensors and/or length sensors in the steel construction of the crane 1; force sensors and/or hydrostatic pressure sensors in the support of the crane 1; pressure sensors in an adjustment cylinder of the crane 1; and/or absolute encoders on a hoisting drum or winch.

(24) The deformation of the crane 1 can be generated or determined from the determined reference value or from the determined reference values using a transfer function. The transfer function can be formed, for example, using a calculated connection or a map. The deformation can, for example, correspond to an outreach displacement and/or to an angle change of the tower and/or boom 2. Different crane configurations or tower/boom configurations or hoist rope reevings can be taken into account here depending on the crane type.

(25) There are the following possibilities for the determination of the transfer function: the transfer function can be fixedly stored in a control or in the control/regulation apparatus 4. In the present case, the terms control and control/regulation apparatus 4 can be used as synonyms; the transfer function or the transfer functions can be determined once by the crane operator, for example by measurements and/or by calculations, and can then be fixedly stored in the control or in the control/regulation apparatus 4; the transfer function can be determined by reference measurements or by scaling. In one or more measurements, the reference value or the reference values and additionally the deformation can be measured to determine their relationship; the transfer function can be determined by a combination of calculation and the reference measurement. The relationship between the reference value and the outreach displacement can be stored in the crane control, but can additionally be checked and/or adapted by a reference measurement; the transfer function can be determined by its calculation in the control or in the control/regulation apparatus 4; the transfer function can be sent to the control or to the control/regulation apparatus 4, for example, via UMTS, LTE, 4G and/or 5G.

(26) Finally, in accordance with the active principle shown, the now known deformation of the crane and thus the diagonal pull can be displayed and corrected or compensated; The deformation is only visualized, e.g. on a display, on the display of the deformation. The operator thus has the possibility of carrying out the correction himself, for example via a manual control device; On an automatic correction, the crane control compensates the outreach displacement fully automatically; This mode can either be permanently active or can be activated as required by the operator, e.g. via a selection switch and/or a display input; and the correction movement can also be controlled by the operator via a button or via a control lever and/or via a display input. The travel movement for compensating the diagonal pull is thus deliberately specified by the operator.

(27) The deformation of the crane 1 can be measured, for example, while using a payload sensor and an outreach sensor.

(28) In a first approach, the corresponding sensors 5 for measuring the payload and the outreach can be installed in the crane 1. The load torque that in this case represents the reference value is determined by calculation in the crane control from these two sensors 5. It is equally conceivable that the outreach is a second reference value in addition to the load torque. This substantially depends on the crane structure and on the static relationships caused thereby.

(29) The diagonal pull can be determined by a reference measurement or by scaling. After the assembly of the crane 1, the relationship between the reference value “load torque” and the outreach displacement can be determined using a reference measurement. The outreach displacement can here correspond to the deformation of the steel construction of the crane 1. For this purpose, a known payload with a known outreach can be raised and the outreach increase resulting from the raising is measured. The outreach displacement Δs here results from the following equation:
Δs=s.sub.real−s.sub.Outreach sensor

(30) FIGS. 4a-4c illustrate this relationship. FIG. 4a here shows a crane with a load placed on the ground, with the crane not being loaded by the load. FIG. 4b shows the crane in which the load to be raised by it is admittedly still on the ground, but a portion of its weight force already acts on the crane. A horizontal movement of the crane 1 or of the upper crane is effected in this state. FIG. 4c shows the crane of FIG. 4b at the moment of the raising of the load from the ground, with the measured outreach increase Δs being shown in FIGS. 4b and 4c.

(31) In this example, a linear relationship between the load torque and the outreach displacement is assumed that is shown in FIG. 5. Non-linear relationships would equally be conceivable. The above-determined relationship is stored in the crane control 4.

(32) The crane operator can activate the automatic correction of the diagonal pull at a display to compensate a unwanted diagonal pull. On a raising of a load, the load torque is calculated, in particular online, from the payload and from the outreach.

(33) The outreach with the trolley 7 is here automatically corrected by the correspondingly determined outreach displacement.
s*=s—s.sub.cor

(34) Since the crane 1 is initially deformed before the raising of the load 6 and since this deformation is compensated simultaneously or with a time offset, there is no longer any diagonal pull at the time of the raising of the load 6 from the ground. This situation is shown in FIG. 6 and in FIGS. 2a to 2c.

(35) If the invention is used in connection with a mobile crane having a luffing boom, a different active principle can also be considered. It is thus conceivable that the deformation of the steel construction is measured by inclinometers in the boom and by absolute value encoders of the guying winch 9. The diagonal pull can in this situation be determined by means of a transfer function that can be fixedly stored in the control. The compensation of the diagonal pull then takes place via corresponding correction commands.

(36) In this case, the boom inclination in a mobile crane having a luffing boom is adjusted using the guying winch 9 that is designed with an absolute value encoder. There is a relationship between the values of the inclinometer in the boom and of the absolute encoder of the guying winch 9. On the attachment of a payload, the inclination of the boom changes due to the deformation of the steel construction of the tower and the boom and due to the stretching of the guying rope, the absolute encoder of the guying winch remains constant, in contrast. The relationship between the boom angle and the absolute encoder thereby changes. More details on this can be seen from FIG. 7.

(37) The relationship between the measurement values of the inclinometer and of the absolute value encoder of the guying winch in the unloaded state (without payload) are fixedly stored in this example. An expected angle of inclination is thus associated with each value of the absolute encoder. On the raising of a payload, there is now a difference between the expected and the actual boom inclination. In the first approach, this difference can be corrected in that the boom angle is corrected to the original value again using the guying winch 9. In this respect, however, only the bending angle of the tower and of the boom is compensated, but not the deflection of the tower (horizontal path of the upper crane as a result of the tower bending). More details on this can be seen from FIG. 8.

(38) In a second approach, the deflection of the tower can also be compensated in addition to the compensation of the angle. In this case, the boom angle has to be set more steeply than originally on a load. More details on this can be seen from FIG. 9.

(39) The diagonal pull is visually presented to the crane operator at a display, possibly with an acoustic signal, to compensate the diagonal pull. The operator can trigger the correction movement or a correction command to adjust the boom by a button or by an input at the touch display.