EP3847123A1

EP3847123A1 - Crane and method for weathervaning such a crane

Info

Publication number: EP3847123A1
Application number: EP19802127.1A
Authority: EP
Inventors: Christoph Eiwan
Original assignee: Liebherr Werk Biberach GmbH
Current assignee: Liebherr Werk Biberach GmbH
Priority date: 2018-11-07
Filing date: 2019-11-07
Publication date: 2021-07-14
Also published as: WO2020094770A1; US12024406B2; US20210300735A1; CN113165854A; DE102018127783A1; BR112021008181A2

Abstract

A method for weathervaning a crane (1) which has a boom (3) which can rotate about a vertical axis (5), a slewing gear motor (7) and a slewing gear service brake (8) for securing the boom (3) in a rotational position with a securing torque in the crane mode, wherein in the case of a crane which has been decommissioned, the boom is braked against rotation with a decommissioned mode braking torque which is less than the specified securing torque in the crane mode, wherein the decommissioned mode braking torque is applied by a slip clutch (10) in the form of a hysteresis clutch or hysteresis brake which is preferably arranged between the slewing gear brake (8) and the slewing gear drive (7) or between the slewing gear drive (7) and an output gear (11).

Description

Crane and method for wind-clearing such a crane

The present invention relates to a method for clearing the wind from a crane, which has a boom which can be rotated about an upright axis, a slewing gear motor and a slewing gear service brake for holding the boom in a rotating position with a holding torque, the boom with the crane when it is out of operation an out-of-service braking torque that is smaller than the specified holding torque in crane operation is braked against rotation. The invention also relates to such a crane itself, in particular in the form of a tower crane.

In the case of tower cranes, but also other types of cranes, the jib can be rotated about an upright slewing axis, wherein a slewing gear provided for this purpose can have a rotary drive, for example in the form of an electric motor, the drive movement of which via a slewing gear, for example in the form of a planetary gear, in a rotary movement of the boom is implemented. In the case of so-called top-turners, the boom is rotated relative to the tower carrying the boom, while in the case of so-called bottom-turners the entire tower together with the boom mounted thereon is turned relative to the undercarriage or the support base. In crane operation, the rotary movements are controlled by correspondingly controlling the rotary drive, a rotary mechanism brake being provided for braking and also for rotationally locking in a certain rotary position. For safety reasons, such slewing gear brakes can usually be designed in such a way that the brake is pretensioned into its braking operating position, for example by a corresponding spring device, and can be released by an actuating actuator in order to release the rotatability.

In non-operation or in the non-operation state when the crane is switched off, however, it is desirable for the crane to be able to turn in order to be able to align itself in the rotational position that is most favorable for the respective wind direction. For example, since tower cranes are usually much more stable due to their ballast against tipping movements in the jib level than with tipping movements perpendicular to the jib level perpendicular to the jib level, the crane should align itself in strong wind so that the wind comes from behind and the boom is aligned with the wind as parallel to the wind direction as possible, otherwise the crane could tip over or the crane would have to be additionally loaded. In order to allow such automatic alignment in the wind, the service brake or slewing gear brake is assigned a wind release device which releases the brake which is normally biased into its braking position when the crane is out of operation. This "evening" position of the slewing brake can be set by means of an actuating lever that can be actuated manually, but possibly also by a motorized ventilation drive, which can move the brake actuator into a locked non-braking position before the crane is switched off. EP 14 22 188 B1, for example, shows such a wind release device for the slewing gear brake of a tower crane.

However, the free rotation of the crane when not in operation can lead to instabilities of the crane due to self-rotation under unfavorable wind conditions. For example, if the crane is between two buildings and only the jib or only the counter jib is exposed to the wind, only the jib or the counter jib is blown by the wind on one side, whereby the Crane can be set in ever faster rotation, since the crane does not stop when the boom has turned out of the wind or before the counter-boom comes into the wind. As a result, the jib and the counter jib can alternately get into the wind, so that a rocking of this cyclical wind load can lead to autorotation of the crane, which causes the crane to turn and tilt too quickly.

In order to avoid such an unwanted autorotation, it has already been proposed not to let the slewing gear turn completely without braking when it is not in operation, but to assign an additional brake to the slewing gear, which allows the slewing motion of the crane under the wind, but slows it down slightly, to defuse the above-mentioned autorotation problem. For example, it was considered to provide a light out-of-service brake at the output of the slewing gear, which opposes the crane rotation with a limited braking torque which is smaller than the torque generated by the wind, so that the crane can still align itself in the wind, but only with it can turn at a lower rotational speed.

However, such an additional brake is difficult to design with regard to the braking torque in order to be equally suitable for different wind conditions and also different crane positions. For example, a braking torque that is too high when the wind is still moderate can result in the crane not aligning itself properly, while the same braking torque cannot adequately prevent the above-mentioned autorotation in very unfavorable wind conditions with high wind speeds. In the case of tower cranes with a luffing jib, the luffing position in which the crane was parked can also have an influence on the braking torque required.

With regard to this problem, the document DE 20 2014 001 801 U1 suggests using the electric motor of the slewing gear drive when the crane is switched off, as a slewing gear brake, which allows rotating movements in the wind, but does so due to its electromotive braking effect. kung brakes. This results in a speed-dependent braking torque which increases with increasing rotational speed, while no or only a very small braking torque is generated in the case of very slow rotational movements.

In addition, EP 20 25 637 B1 proposes a tower crane whose service brake is deactivated when the crane is switched off. Instead, a separate out-of-service brake is activated which is to provide a braking force which should correspond to the wind moment on the boom minus the wind moment on the counter-boom and minus a drag torque of the slewing gear. Since the lever arm or the contact surface of the boom and also the counter-boom changes with respect to the wind direction, in particular when the boom is at right angles to the wind and is zero and when the boom is parallel to zero, the control of the brake becomes relatively complex by one to simulate such a torque-dependent wind torque as braking torque.

The document US 2009/0308827 A1 shows a rotary tower which, in addition to the service brake, which is deactivated for the wind release, has an additional brake which is activated when the crane is out of operation. This additional brake is a friction disc brake that is biased into the braking position by a spring device and is deactivated by an electromagnet when the crane is in operation and the main service brake is working. The braking force of the auxiliary brake mentioned can be adjusted by adjusting the spring preload that drives the brake shoes against the brake disc by means of a screw spindle. Due to the difference between static friction and sliding friction coefficient, when the crane is torn loose or initially twisted under wind forces, the braking force drops significantly with increasing rotational speed. While the braking force is relatively high at a standstill, it drops sharply when the initial static friction is overcome. This makes it difficult to adjust the braking force appropriately and can hardly be compensated for by the adjusting spindle for adjusting the spring device. The present invention is therefore based on the object of creating an improved crane of the type mentioned at the outset which avoids disadvantages of the prior art and advantageously develops the latter. In particular, for changing, difficult wind conditions and different crane configurations when the crane is parked, an autorotation which jeopardizes the stability of the crane is to be reliably prevented, but at the same time a free alignment of the crane in the wind is made possible.

According to the invention, the stated object is achieved by a method according to claim 1 and a crane according to claim 3. Preferred embodiments of the invention are the subject of the dependent claims.

It is therefore proposed that, when the crane is out of operation, braking the jib rotation of the jib with an out-of-service braking torque which is significantly smaller than the holding torque applied during operation, but also for very slight rotations with very low, zero-going turns - speed affects. According to the invention, the non-operating braking torque is kept at least approximately constant over the rotational speed range and over the rotational angle range of the boom. Despite the obvious prejudice that the crane would have to be braked more strongly at higher speeds and that stronger braking is required when the wind is stronger than when the wind is low, it is sufficient to brake the boom with a constant, small braking torque to prevent it from twisting if one such a small braking torque is equally measured over the entire angle of rotation range and is also provided when the crane is still standing and not rotating, in particular if the torque is kept at least approximately uniform from standstill due to wind-induced loosening and no breakaway torque occurs. Such a uniform braking torque, which is already available when the movement is initiated from zero speed, can effectively prevent autorotation, even if the braking moment is very small and is clearly below the holding torque provided during operation.

In particular, the out-of-service braking torque is kept at least approximately constant, even in the low speed range down to zero speed, so that when starting to turn under wind the same braking torque is provided as when turning the crane boom faster under wind forces. In this way, a breakaway effect with a stronger rotational acceleration of the boom, as occurs in disc brakes due to the different static and sliding friction coefficients, can be avoided.

The mentioned non-operating braking torque can be provided in various ways, advantageously without an additional non-operating brake, which would be provided in addition to the operating holding brake. According to one aspect of the present invention, said out-of-service operating torque is generated with the aid of an adjustable slip clutch, in particular in the form of a hysteresis clutch and / or brake, which is in the drive train between the service holding brake and the drive motor of the slewing gear or can be installed between said drive motor and an output pinion, which meshes with a slewing ring, to which the boom or a tower supporting the boom is connected in a rotationally fixed manner. If the drive train has a slewing gear transmission between the drive motor and the driven wheel, the slipping clutch can be integrated into the mentioned slewing gear transmission, in particular arranged in the interior of the transmission housing and assigned to one of the transmission elements.

The mentioned slip clutch is advantageously adjustable with regard to the torque at which slipping occurs, so that the slip clutch can be switched over between an operating position and a non-operating position. If the crane is in operation and the slewing gear drive train is to transmit the usual torques, the slip clutch is set to a relatively high slip torque, which is at least the holding torque of the mentioned one Holding brake can correspond, so that slipping in crane operation takes place only in the event of an overload. On the other hand, the slip clutch can be switched from a corresponding out-of-operation control device to an out-of-operation position, in which the slip clutch only provides a much smaller slip torque, which is in particular significantly smaller than the holding torque provided by the service brake. When the crane is out of operation, a wind release can be achieved in which the slip clutch slips and thereby provides the desired, small braking torque, which can be essentially constant over the entire speed range and angle of rotation range of the crane.

In particular, the above-mentioned slip clutch is designed as a hysteresis clutch, which advantageously generates its torque exclusively via the air gap between the rotor and stator and does not require any friction components, so that the hysteresis clutch can provide the desired torque smoothly and with excellent torque repetition accuracy. Such a hysteresis clutch and / or brake operates without wear and can have two ring magnets permanently excited in segments, which enclose a hysteresis disk. If the same poles face each other, a maximum magnetic field acts on the hysteresis disc, which causes a flow of lines of force in the circumferential direction within the hysteresis disc and generates a maximum moment. If there are opposing poles, the smallest magnetic field acts on the hysteresis disc and the line of force flows directly through it, which results in a minimal torque.

Advantageously, no breakaway torque occurs in such a hysteresis clutch or brake, and a braking torque that is largely uniform over the entire speed range can be generated without wear occurring.

The hysteresis clutch or brake could be designed electromagnetically in order to adjust the amount of the torque provided by electrical control. to be able to ask. However, if the hysteresis clutch or brake has permanent magnets, the decommissioning brake can also work without a power supply.

Regardless of the electro-magnetic or permanent magnetic design, the use of such a hysteresis clutch or brake can be advantageous even without the braking torque being adjustable in that no breakaway torque occurs, but the torque or braking torque is gentle and approximately constant over the entire, interesting speed range, in particular including the low speed range including the speed zero, is provided gently.

In a further development of the invention, the hysteresis clutch mentioned can be designed with a gap of adjustable size between the two coupling halves in order to be able to adjust the slip torque by adjusting the gap size. With such an adjustable coupling gap between the rotor and the stator, the torque or braking torque can be set in a simple manner even if the hysteresis coupling or brake is designed to be permanent magnetic.

In particular, the hysteresis coupling can have a conical gap between its coupling halves, at least one of the coupling halves being designed to be axially adjustable, so that the said conical gap is radially and / or axially adjustable by axially adjusting the coupling half relative to the other coupling half can be adjusted.

The changeover of the slip torque to a high value for regular crane operation and a lower value for the crane which is out of operation can thus be achieved in a simple manner by axially adjusting one of the coupling halves. At the same time, the desired braking or slipping torque can be set very precisely and precisely by such an axial adjustment in conjunction with a conical gap.

When using such an adjustable slip clutch, a normal service holding brake known per se can be used, it being irrelevant if such a regular service holding brake would itself generate a breakaway torque. This is irrelevant, since in the wind release the above-mentioned slip clutch provides a significantly smaller slip torque, which allows the crane to rotate under a uniform, relatively small braking torque.

According to a further aspect of the present invention, however, the out-of-service braking torque mentioned can also be provided by the service-holding brake itself, in which case the conventional service-holding brakes with organic brake pads are replaced by a preferably spring-actuated brake, which its braking torque is adjustable and is set by an out-of-operation control device when the crane is out of operation in such a way that an at least approximately constant braking torque is provided which is significantly smaller than the holding torque in the switched-on crane operation and over the entire range of rotation speed and angle of rotation Crane is at least approximately constant, that is, even when initiating a turning operation out of zero rotational speed.

The stated spring force application of the service brake can be set to a low spring force value when the crane is not in operation, which provides the desired out-of-service braking torque. In order to be able to provide the desired higher holding torque in crane operation, the spring force mentioned can be increased, for example by adjusting the spring device, and / or an additional braking force can be applied, for example, by a brake actuator such as a pressure cylinder. For example, a part of a spring device can also be put out of operation when the crane is out of operation, for example by one or more pre- tension springs are deactivated to provide a correspondingly smaller out-of-service braking force.

The spring preload can be generated, for example, by a mechanical spring device with, for example, disc springs or spiral springs, but also by a hydraulic spring device, for example with an adjustable pressure accumulator.

Advantageously, the slewing gear brake mentioned can have synthetic friction linings in order to reduce wear and to enable a uniform braking torque even when initiating a rotational movement from zero rotational speed.

The synthetic friction linings mentioned can be part of brake pads, for example, by means of which a brake disc can be braked. Alternatively, however, the slewing gear brake can also be designed in the form of a multi-disc brake, in which the synthetic friction linings mentioned are pressed against one another in the form of discs.

The out-of-service braking torque can, for example, be less than 50% of the operating folding torque which is provided in crane operation in order to be able to hold the crane in a desired rotational position during operation. Such a holding torque for crane operation is usually dimensioned such that a wind load of 72 km / h and / or a dynamic pressure of 250 Pa act on the rotating part and the maximum load capacity from the most unfavorable direction and can still be held.

The invention is explained in more detail below on the basis of preferred exemplary embodiments and associated drawings. The drawings show:

Fig. 1: a perspective, partial representation of a tower crane according to an advantageous embodiment of the invention, the top-slewing is designed and has a slewing gear for rotating the boom relative to the tower,

Fig. 2: a schematic representation of the drive train of the slewing gear of the

Crane from Figure 1, wherein according to an advantageous embodiment of the invention, an adjustable slip clutch in the form of a flyster clutch is integrated in the slewing gear between the drive motor and output pinion and

Fig. 3: a schematic representation of the drive train of the slewing gear of the

Crane from Figure 1 according to an alternative embodiment of the invention, in which only a slewing gear brake is provided, which is designed in the form of an adjustable spring force operated friction brake.

As shown in FIG. 1, the crane in question can be a tower crane 1 designed as a so-called top-slewing crane, the tower 2 of which carries a jib 3 and a jib 4, which extend essentially horizontally and about the upright tower axis 5 are rotatable relative to the tower 2. Instead of the crane configuration shown in FIG. 1, the tower crane 1 could, however, also be designed as a bottom slewing and / or comprise a luffing jib and / or anchored to the tower base or superstructure.

In order to be able to rotate the boom 3, a rotating mechanism 6 is provided, which in the embodiment shown is provided at the upper end of the tower 2 between the boom 3 and the tower 2 and can comprise a toothed ring with which a drive wheel driven by a drive motor 7 can be provided combs.

An advantageous embodiment of the drive device of the slewing gear 6 can comprise an electric drive motor 7 which can drive an output shaft via a slewing gear gear. The mentioned slewing gear mechanism can be a planetary gear mechanism, for example, in order to reduce / translate the speed of the drive motor 7 into a speed of the output shaft in the desired manner. In order to brake the rotary movements of the boom 3 in crane operation and / or to be able to maintain an approached rotational position of the boom 3, the slewing gear 6 comprises a slewing gear service brake which can be arranged, for example, on the input side of the slewing gear mechanism. In a manner known per se, the service brake can comprise, for example, a friction disc or multi-disc brake device which is pretensioned into the braking position by a pretensioning device and can be released by an electrical actuating actuator, for example in the form of an electromagnet, in order to release the brake . As an alternative or in addition to such a mechanical service brake, an electromotive service brake can also be provided, for example in the form of a brake chopper with switchable braking resistors, which can be integrated in the converter controlling the electric motor 2 or can be assigned to it.

As FIG. 2 shows, a slip clutch 10 can be integrated into the slewing gear 9, ie between the drive motor 7 and drive pinion 11, which is advantageously designed as a flyster clutch and its slip torque can be adjusted.

The flyster clutch, which forms the slip clutch 10, can preferably be constructed in a cylindrical manner and / or have an internal permanent magnetic rotor and an external, hollow cylindrical flyster ring. Such an arrangement enables simple cooling of the flyster reading ring, which can be subject to considerable heating during operation.

The air gap of the flyster clutch can be free of oil or advantageously also oil-filled, for example when the slip clutch 20 is running in the oil bath of the rotary transmission. The resulting heat loss is dissipated via the oil bath of the gear housing, but a separate oil circuit can also be provided. In order to be able to set the slip torque of the slip clutch 20, the hysteresis clutch can advantageously have an air gap that is adjustable. In the case of a cylindrical air gap, an axial adjustment of at least one coupling half with a constant radial air gap width can be used to axially shorten the same, in order to adjust the slip torque as desired.

Advantageously, the air gap between the coupling halves can also be conical, in order to adjust the air gap both in its radial and in its axial width or length by means of an axial adjustment of at least one coupling half. By adjusting the size of the air gap, the slip torque and / or the shape or slope of the torque / slip characteristic can be adjusted and adjusted.

An out-of-operation control device 12, which is only shown schematically, can carry out the aforementioned axial adjustment of the hysteresis adjustment in order to set the slip torque to the desired low value significantly below the holding torque required in crane operation when the crane is out of operation.

For regular crane operation, the two coupling halves are then axially adjusted relative to one another in such a way that there is a relatively high slip torque, which can also be significantly above the holding torque of the service brake.

As FIG. 3 shows, the slewing gear brake 8 itself can also be used to provide a constant braking torque when the crane is switched off, without tearing loose when initiating the rotary movement. In particular, the rotary brake 8 can be designed to be adjustable with regard to its provided torque.

The slewing gear brake 8 can in particular be a wheel-operated brake that can be set to a defined braking torque, for example in that the spring device 13 is designed to be adjustable relative to one another for pretensioning the friction elements.

Said out-of-operation control device 12 can deactivate, for example, part of the spring elements when the crane is stopped, so that only a part of the spring elements and thus part of the spring preload is active when the crane is stopped. In normal crane operation, however, all the spring elements can be activated, the spring device being released when the slewing gear is actuated, or the spring preload being overcome by a pressure medium cylinder. If the air cylinder is then deactivated again, all the spring elements act and press the friction elements of the brake against one another in order to provide the full holding force or braking force.

The service brake is advantageously equipped with synthetic friction linings.

Claims

Liebherr-Werk Biberach GmbH Biberach on the Riss crane and method for freeing the wind from such a crane

1. A method for clearing the wind of a crane (1) which has a boom (3) which can be rotated about an upright axis (5), a slewing gear motor (7) and a slewing gear brake (8) for holding the boom (3) in a rotating position during crane operation has a holding torque, the boom (3) being braked against rotation when the crane (1) is out of operation with an out-of-service braking torque that is smaller than the holding torque in crane operation, characterized in that the out-of-service braking torque is greater than Rotation speed range and the rotation angle range of the boom (3) is kept constant.

2. The method according to the preceding claim, wherein the out-of-service braking torque by a slip clutch (10) in the form of a hysteresis clutch or brake, which is preferably between the slewing gear brake (8) and the slewing gear drive (7) or between the slewing gear drive (7) and a driven wheel (11) is arranged, is applied.

3. Crane, in particular tower crane, with a boom (3) rotatable about an upright axis (5), a slewing gear motor (7) for rotating the boom (3) about the upright axis (5) and a slewing gear brake ( 8) for braking the twisting of the boom (3), characterized in that a slip clutch (10) in the form of a hysteresis clutch between the slewing gear motor (7) and the slewing gear brake (8) or between the slewing gear motor (7) and one Output gear, which is in engagement with a turntable connected to the boom (3) in a rotationally fixed manner, is provided in the drive train of the slewing gear.

4. Crane according to the preceding claim, characterized in that the hysteresis clutch is formed with a gap of adjustable size.

5. Crane according to the preceding claim, wherein the hysteresis coupling has a conical gap, wherein at least one of the coupling halves of the hysteresis coupling is designed to be axially adjustable, so that the conical gap in its radial gap dimension and / or in its axial length is adjustable.

6. Crane according to claim 4, wherein the hysteresis coupling has a cylindrical gap, at least one of the coupling halves being axially adjustable, so that the cylindrical gap is adjustable in its axial length dimension.

7. Crane according to one of the preceding claims, wherein a non-operating control device for adjusting the slip clutch (10) between a non-operating position in which the slip clutch (10) provides a smaller slip torque, which is smaller than that of the slewing gear brake ( 8) provided operating holding torque, and an operating position in which the slip clutch (10) provides a slip torque that is at least as large as the holding torque of the slewing gear brake (8).

8. Crane according to the preceding claim, wherein the non-operating control device is designed for the axial adjustment of one of the coupling halves of the slip clutch (10).

9. Crane according to one of the preceding claims, wherein the slip clutch (10) is integrated in a slewing gear (9) and is received inside a gear housing of the slewing gear (9).

10. Crane according to the preamble of claim 3 or one of the preceding claims, wherein the slewing gear brake (8) is designed to be adjustable in its braking torque, so that braking torques of different sizes can be prepared, an out-of-operation control device for adjusting the slewing gear brake (8 ) on an out-of-service braking torque which is smaller than the holding torque provided for crane operation.

11. Crane according to the preceding claim, wherein the slewing gear brake (8) is spring-actuated and has a spring device which is adjustable in its spring force for applying braking forces of different magnitudes.

12. Crane according to the preceding claim, wherein the decommissioning control device is designed to adjust the spring preload of the spring device so that the spring device provides a lower spring force when the crane is out of operation than in the intended crane operation.

13. Crane according to one of the preceding claims, wherein the slewing gear brake (8) has synthetic friction linings.

14. Crane according to one of the preceding claims, wherein the out-of-service braking torque is between 5% to 50% or between 5% and 25% of the holding torque provided in crane operation.