Crane and method for orienting such a crane in response to the wind direction

Abstract

The present invention relates to a method for orienting a crane (1) in accordance with the wind direction. The crane has a boom (3) that can rotate about a vertical axis (5), a slewing mechanism motor (7), and a slewing mechanism brake (8) that is used to hold the boom in a slewing position with a holding torque during the operation of the crane. When the crane is out of service, the boom is braked with a standstill braking torque to prevent rotation, and the standstill braking torque is less than the holding torque during the operation of the crane. The standstill braking torque is applied by a slip clutch (10) in the form of a hysteresis clutch or a hysteresis brake, and the slip clutch is preferably arranged between the slewing mechanism brake (8) and the slewing mechanism drive (7) or between the slewing mechanism drive (7) and the output gear (11).

Description

Technical Field

[0001] The present invention relates to a method for changing the orientation of a crane in accordance with the wind direction. The crane has a boom that can rotate about a vertical axis, a slewing mechanism motor, and a slewing mechanism operating brake for holding the boom in a rotational position with a holding torque during the operation of the crane. When the crane is in a stopped state, the rotation of the boom is braked with a stopped braking torque that is less than the holding torque during the operation of the crane. Herein, the present invention also relates to the crane itself, in particular in the form of a slewing tower crane. Background Art

[0002] In slewing tower cranes and other crane types, the boom can rotate about a vertical slewing mechanism axis. For this purpose, the provided slewing mechanism can have, for example, a slewing mechanism drive in the form of an electric motor, and the drive movement of the slewing mechanism drive is converted into a rotational movement of the boom by a slewing mechanism transmission in the form of, for example, a planetary gear. In so-called up-slewing cranes, the boom rotates relative to the tower for supporting the boom, while in so-called down-slewing cranes, the entire tower and the boom mounted thereon rotate relative to the chassis or support base.

[0003] During the operation of the crane, the rotational movement is controlled by corresponding control of the slewing mechanism drive. Among them, a slewing mechanism brake for braking and also for preventing rotation is provided at a specific rotational position. For safety reasons, such a slewing mechanism brake can generally be constructed such that the brake is preloaded to its braking operation position, for example, by a corresponding spring device, and can be released by adjusting an actuator to release the rotatability.

[0004] However, during the outage period or in the outage state, when the crane is shut down, it is desirable for the crane to still be able to rotate so that in the presence of wind, the crane can be oriented in the most favorable rotational position for each wind direction. For example, since a rotating tower crane is generally more stable in preventing tilting motion in the plane of the boom extending vertically through the boom than in preventing tilting motion transverse to the plane of the boom due to its ballast, in strong winds, the crane should orient itself so that the wind blows from behind and use the wind to orient the boom as parallel to the wind direction as possible, because otherwise, it may cause the crane to tilt or the crane has to perform additional ballasting. To allow this automatic orientation in the wind, the running brake or the rotary mechanism brake is assigned a wind direction orientation device that, when the crane is out of service, releases the brake that is normally preloaded to its braking position. The "end of operation" position of the rotary mechanism brake can be adjusted by a manually operated control lever, but optionally can also be adjusted by an electric release drive that can move the brake actuator to the locked non-braking position before the crane is shut down. For example, document EP 14 22 188 B1 shows such a wind direction orientation device for the rotary mechanism brake of a rotating tower crane.

[0005] However, the free rotatability of the crane in the outage state can lead to instability of the crane due to self-rotation under adverse wind conditions. For example, when the crane is located between two buildings and only the boom or only the counterweight arm is exposed to the wind, only the boom or only the counterweight arm is subjected to the wind on one side, whereby the crane can rotate faster and faster because the crane does not stop when the boom turns out of the wind area or before the counterweight arm turns into the wind area. Therefore, the boom and the counterweight arm can alternately enter the wind, so that the accumulation of this cyclic wind action can cause the automatic rotation of the crane, which causes the crane to rotate too fast and tilt it.

[0006] To avoid this undesirable automatic rotation, it has been proposed not to allow the rotary mechanism to rotate completely unbraked in the outage state, but to assign an additional brake to the rotary mechanism that allows the crane to rotate in the wind but can be slightly braked to mitigate the above-mentioned self-rotation problem. For example, it has been considered to provide a mild outage brake at the output of the rotary mechanism transmission that prevents the rotation of the crane with a limited braking torque that is less than the torque generated by the wind action, so that the crane can still be oriented in the wind but can only rotate at a low speed.

[0007] However, it is difficult to design such an additional brake in terms of braking torque so as to be equally applicable to different wind conditions and different crane positions. For example, in medium wind, too high a braking torque may cause the crane to be unable to self-align correctly, while in very adverse wind conditions with high wind speeds, the same braking torque cannot sufficiently suppress the autorotation. In addition, for a slewing tower crane with a luffing jib, the luffing position when the crane is shut down affects the required braking torque.

[0008] In document DE 20 2014 001 801 U1, regarding this problem, it is proposed to use the electric motor of the slewing drive as a slewing brake when the crane is in the shut-down state. The electric motor allows rotational movement in the wind, but brakes the rotational movement through the braking action of its electric motor. This results in a braking torque depending on the rotational speed, which increases as the rotational speed increases, while in a very slow rotational movement, no or only a very small braking torque is generated.

[0009] In addition, in document EP 20 25 637 B1, a slewing tower crane is proposed. When the crane is shut down, its operating brake is deactivated. Instead, a separate shut-down brake is activated, which is used to provide a braking force that should correspond to the wind torque on the jib minus the wind torque on the counter-jib and minus the drag torque on the slewing mechanism. Since the lever arms of the jib and the counter-jib and the contact surfaces change relative to the wind direction, especially being maximum when the jib is transverse to the wind direction and zero when the jib is parallel to the wind direction, in order to simulate such a wind torque depending on the rotational angle as a braking torque, the control of the brake becomes relatively complex.

[0010] Document US2009 / 0308827 A1 shows a slewing tower crane. In addition to the operating brake that is deactivated to change the azimuth with the wind direction, the tower crane also includes an additional brake that is activated in the shut-down state of the crane. The additional brake is a friction disc brake, which is preloaded in the braking position by a spring device and is deactivated by an electromagnet when the crane itself is in the operating state and the main operating brake is working. Here, the spring preloading force for driving the brake shoes against the brake pads is adjusted by a threaded shaft, thereby adjusting the braking force of the above additional brake. Due to the difference between the static friction coefficient and the sliding friction coefficient, when the crane loosens or starts to rotate in the wind, the braking force decreases significantly as the rotational speed increases. Although the braking force is relatively high in the static state, when the initial static friction is overcome, the braking force drops sharply. This makes it difficult to appropriately adjust the braking force, and it can hardly be compensated by the adjusting shaft for adjusting the spring device. Summary of the Invention

[0011] It is accordingly an object of the present invention to provide an improved crane of the above type which avoids the disadvantages of the prior art and develops the prior art in an advantageous manner. In particular, for varying and difficult wind conditions as well as different crane configurations, rotation which endangers the stability of the crane should also be reliably prevented when the crane is shut down, but at the same time the crane should be able to orient itself freely in the wind.

[0012] Accordingly, when the crane is shut down, the rotation of the jib is braked with a shut-down braking torque which is significantly less than the holding torque applied during operation, but which is also effective in the case of a very slight rotation at a very low speed close to zero. According to the invention, the shut-down braking torque remains substantially constant at least within a rotational speed range and a rotational angle range of the jib. Despite the obvious prejudice that the crane has to be braked more strongly at higher rotational speeds and a stronger braking is required at stronger wind torques than at lower wind torques, it is sufficient to brake the rotation of the jib with only this constant, small braking torque if the small braking torque is applied equally over the entire rotational angle range and is also provided when the crane is still stationary and not rotating, in particular if this torque is maintained at least approximately uniformly when the crane starts to move from the stationary state due to the wind and no release torque occurs. This uniform braking torque, which is in particular already provided when starting to move from zero rotational speed, can effectively prevent self-rotation even if the braking torque is very small and significantly lower than the holding torque provided during operation.

[0013] In particular, the shut-down braking torque is maintained at least approximately constantly even in a low rotational speed range down to zero rotational speed, such that the braking torque provided when initially starting to rotate under the action of the wind is the same as the braking torque provided when the crane jib rotates faster under the action of the wind force. Thus, a release effect (Losreiβeffekt) in the case of a stronger jib rotational acceleration can be avoided, as occurs with a disc brake due to different static and sliding friction coefficients.

[0014] The shutdown braking torque can be provided in various ways, and advantageously, an additional shutdown brake provided in addition to the running holding brake is dispensed with. According to one aspect of the invention, the shutdown running torque is provided by an adjustable slip clutch (in particular, in the form of a hysteresis clutch and / or a hysteresis brake), and the slip clutch can be arranged in the rotary mechanism transmission system between the running holding brake and the rotary mechanism drive motor or between the drive motor and the output gear, and the output gear meshes with a rotary ring that is non-rotatably mounted on the boom or a tower for supporting the boom. If the transmission system between the drive motor and the output gear has a rotary mechanism transmission device, the slip clutch can be integrated into the rotary mechanism transmission device, in particular, arranged inside the transmission device housing and assigned to one of the gear elements.

[0015] Advantageously, the slip clutch is adjustable in terms of the slip torque such that the slip clutch can be switched between a running position and a shutdown position. If the crane is running and the rotary mechanism transmission system is to transmit the normal torque, the slip clutch is adjusted to a relatively high slip torque, and the slip torque is at least equivalent to the holding torque of the holding brake, such that slipping during the operation of the crane only occurs in the case of overload. On the other hand, the slip clutch can be switched to the shutdown position by a corresponding shutdown control device, and in this shutdown position, the slip clutch only provides a very small slip torque, in particular, significantly less than the holding torque provided by the running brake. Therefore, when the crane is shut down, it is possible to achieve a change in orientation with the wind direction, wherein the slip clutch slips and thereby provides the desired and small braking torque, and the braking torque can be substantially constant over the entire rotational speed range and rotational angle range of the crane.

[0016] In particular, the slip clutch is configured as a hysteresis clutch, and the hysteresis clutch advantageously generates its torque only through the air gap between the rotor and the stator and does not require friction components, such that the hysteresis clutch can smoothly provide the desired torque and has excellent torque repetition accuracy. Such a hysteresis clutch and / or a hysteresis brake operates without wear and can have two segmented permanent excitation type annular magnets that surround the hysteresis disk. If the same magnetic poles face each other, the maximum magnetic field acts on the hysteresis disk, which will cause a magnetic flux in the circumferential direction within the hysteresis disk and generate the maximum torque. If different magnetic poles face each other, the minimum magnetic field acts on the hysteresis disk and the magnetic flux extends directly through the hysteresis disk, resulting in the minimum torque.

[0017] Advantageously, no starting torque (Losbrechmoment) occurs in such a hysteresis clutch or a hysteresis brake, and a uniform braking torque can be generated over the entire rotational speed range without wear.

[0018] A hysteresis clutch or a hysteresis brake can be electromagnetically configured so that the magnitude of the torque provided can be adjusted by electrical control. However, if the hysteresis clutch or the hysteresis brake has a permanent magnet, the holding brake can also operate without a power supply.

[0019] Regardless of whether it is an electromagnetic configuration or a permanent magnet configuration, it can be advantageous to use such a hysteresis clutch or a hysteresis brake even without the adjustability of the braking torque, because no release torque (Losreiβmoment) occurs, but the torque or the braking torque is provided smoothly and approximately constantly over the entire speed range of interest, especially in the low speed range including zero speed.

[0020] In an improved example of the present invention, the hysteresis clutch can be configured to have an adjustable gap between two half couplings so that the slip torque can be adjusted by adjusting the gap size. When the hysteresis clutch or the hysteresis brake is configured with a permanent magnet, the torque and the braking torque can also be simply adjusted by such an adjustable clutch gap between the rotor and the stator.

[0021] In particular, the hysteresis clutch can have a tapered gap between its half couplings wherein at least one of the half couplings is configured to be axially adjustable so that the radial clearance dimension and / or the axial length of the tapered gap can be adjusted by axially adjusting the half coupling relative to the other half coupling.

[0022] Therefore, by axially adjusting one of the half couplings, the slip torque can be simply converted into a high value for normal crane operation and a low value for crane shutdown.

[0023] At the same time, by this axial adjustment in combination with the tapered gap, the desired braking torque or slip torque can be adjusted very accurately and precisely.

[0024] When using such an adjustable slip clutch, a standard, known running holding brake can be used. It doesn't matter that such a conventional running holding brake itself generates a release torque. This is not important because the slip clutch provides a significantly smaller slip torque when changing its orientation with the wind direction, which allows the crane to rotate with a relatively small and stable braking torque.

[0025] According to another aspect of the present invention, the parking braking torque is also provided by the running holding brake itself. In this case, a conventional running holding brake with organic brake linings is preferably replaced by a spring-actuated brake, which is configured such that its braking torque is adjustable and is adjusted by a parking control device when the crane is parked, so as to provide at least approximately constant braking torque, which is significantly less than the holding torque when the crane is started, and is at least approximately constant over the entire rotational speed range and rotational angle range of the crane, that is, it is also effective when starting the rotational movement from zero rotational speed. When the crane is parked, the spring force exerted by the running brake can be adjusted to a low spring force value, which provides the desired parking braking torque. In order to provide the desired higher holding torque when the crane is running, the spring force can be increased, for example, by adjusting the spring device and / or by applying additional braking force, for example, by a brake actuator such as a pressure cylinder. For example, when the crane is parked, a part of the spring device can also be deactivated, for example, by deactivating one or more preloaded springs, so as to provide a correspondingly smaller parking braking force.

[0026] For example, the spring preloading force can be generated by a mechanical spring device, such as a disc spring or a helical spring, but can also be generated by a hydraulic spring device, such as a pressure tank with adjustable pressure.

[0027] Advantageously, the rotary mechanism brake has a composite friction lining to reduce wear and to enable a uniform braking torque even when starting the rotary movement from zero rotational speed.

[0028] The composite friction lining can be, for example, a part of a brake shoe that can brake a brake disc. However, alternatively, the rotary mechanism brake can also be configured in the form of a multi-disc brake, where the composite friction linings are pressed against each other in the form of discs.

[0029] For example, the parking braking torque can be less than 50% of the running holding torque provided when the crane is running, so as to be able to hold the crane in the desired rotational position during operation. Generally, this holding torque during crane operation is calculated such that a wind load of 72 km / h and / or a dynamic pressure of 250 Pa from the most unfavorable direction affect the rotating part and the maximum load, but the crane can still be held. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be described in more detail below based on preferred exemplary embodiments and related drawings.

[0031] Figure 1 A partial perspective view of a rotating tower crane according to an advantageous embodiment of the present invention is shown, which is configured as an upper-rotating type and has a rotary mechanism for rotating a boom relative to a tower.

[0032] Figure 2 shows Figure 1 a schematic view of a transmission system of a slewing mechanism of a crane, wherein, according to an advantageous embodiment of the present invention, an adjustable slip clutch is integrated in the slewing mechanism drive as a hysteresis clutch between the drive motor and the output gear.

[0033] Figure 3 shows according to an alternative embodiment of the present invention Figure 1 a schematic view of a transmission system of a slewing mechanism of a crane, wherein only a slewing mechanism brake configured in the form of an adjustable spring-actuated friction brake is provided. Detailed Description

[0034] As Figure 1 shown, the crane under discussion can be a revolving tower crane 1 configured as a so-called up-swing crane, the tower 2 of which carries a boom 3 and a counterweight arm 4, the boom 3 and the counterweight arm 4 extending substantially horizontally and being rotatable relative to the tower 2 about a vertical tower axis 5. However, instead of Figure 1 the crane configuration shown, the revolving tower crane 1 can also be configured as a down-swing crane, and / or can include a luffing jib, and / or can be fixed to the tower base or superstructure by cables.

[0035] In order to be able to rotate the boom 3, a slewing mechanism 6 is provided, which in the illustrated embodiment is arranged at the top of the tower 2 between the boom 3 and the tower 2 and can include a gear ring, and an output gear driven by a drive motor 7 meshes with the gear ring.

[0036] An advantageous embodiment of the drive device of the slewing mechanism 6 can include an electric drive motor 7, which can drive an output shaft through a slewing mechanism transmission. For example, the slewing mechanism transmission can be a planetary gear in order to reduce / convert the rotational speed of the drive motor 7 to the rotational speed of the output shaft in a desired manner.

[0037] In order to be able to brake the rotational movement of the boom 3 during crane operation and / or hold the rotational position reached by the boom 3, the slewing mechanism 6 includes a slewing mechanism service brake, which can be arranged, for example, on the input side of the slewing mechanism transmission. For example, the service brake can include a friction disc brake or a multi-disc brake in a known manner, which is preloaded by a preloading device in the braking position and released by an electrically controlled actuator in the form of, for example, an electromagnet to release the brake. As an alternative or supplement to such a mechanical service brake, an electric service brake in the form of a braking chopper with a switchable braking resistor can also be provided, which can be integrated or distributed into the converter for controlling the electric motor.

[0038] As Figure 2 shown, the slip clutch 10 can be integrated into the rotary mechanism drive 9, i.e., between the drive motor 7 and the output gear 11. The slip clutch is advantageously configured as a hysteresis clutch and its slip torque is adjustable.

[0039] Preferably, the hysteresis clutch forming the slip clutch 10 can be configured cylindrically and / or have an internal permanent magnet rotor and an external hollow cylindrical hysteresis ring. Such an arrangement enables easy cooling of the hysteresis ring, which may be significantly heated during operation.

[0040] The air gap of the hysteresis clutch can be oil-free, or, for example, when the slip clutch 20 operates in the oil sump of the rotary mechanism drive, the air gap is also advantageously filled with oil. Here, the generated loss heat is dissipated through the oil sump of the drive housing, but a separate oil circuit can also be provided.

[0041] In order to be able to adjust the slip torque of the slip clutch 20, the hysteresis clutch can advantageously include an adjustable air gap. In the case of a cylindrical air gap, the air gap can be axially shortened while maintaining the same radial air gap width by axial adjustment of at least one half-coupling, in order to adjust the slip torque as required.

[0042] However, advantageously, the air gap between the half-couplings can also be configured conically, in order to adjust the width or length of the air gap in its radial and axial directions by axial adjustment of at least one half-coupling. By adjusting the size of the air gap, the slip torque can be adjusted and set, and / or the shape or steepness of the torque characteristic curve / slip characteristic curve can be adjusted and set.

[0043] The shutdown control device 12, only schematically shown, can perform the axial adjustment of the hysteresis clutch in order to adjust the slip torque to a desired low value significantly lower than the holding torque required during crane operation when the crane is shut down.

[0044] For normal crane operation, the two half-couplings are then axially adjusted relative to each other again, thereby providing a relatively high slip torque, which can also be significantly higher than the holding torque of the service brake.

[0045] As Figure 3 shown, the rotary mechanism brake 8 itself can also be used to provide a constant braking torque when the crane is shut down without releasing (Losreißen) when the rotary motion is started. In particular, the rotary mechanism brake 8 can be configured such that the torque it provides is adjustable.

[0046] In particular, the rotary mechanism brake 8 can be a wheel drive type brake, which can be set to a defined braking torque, for example by configuring the spring device 13 to be adjustable for preloading the friction elements relative to each other.

[0047] For example, when the crane is out of operation, the out-of-operation control device 12 can deactivate a part of the spring elements, so that when the crane is out of operation, only a part of the spring elements are effective and thus a part of the spring preloading force is effective. However, during normal crane operation, all spring elements can be activated, and when driving the rotary mechanism, the spring device can be released or the spring preloading force can be overcome by a pressure medium cylinder. If the cylinder is deactivated again subsequently, all spring elements engage and press the friction elements of the brake against each other to provide full holding force or braking force.

[0048] Advantageously, the service brake is equipped with a synthetic friction lining.

Claims

1. A method for orienting a crane (1) according to the wind direction, the crane having a boom (3) capable of rotating about a vertical axis (5), a slewing mechanism motor (7), and a slewing mechanism brake (8), the slewing mechanism brake being configured to hold the boom (3) in a rotational position with a holding torque during operation of the crane, wherein, when the crane (1) is out of operation, the boom (3) is braked with an outage braking torque to prevent rotation, the outage braking torque being less than the holding torque during operation of the crane, characterized in that the outage braking torque remains constant within a rotational speed range and a rotational angle range of the boom (3), wherein the outage braking torque is applied by a slip clutch (10) in the form of a hysteresis clutch or a hysteresis brake, wherein the hysteresis clutch is adjusted differently based on whether the crane is in an operating mode or an outage mode, the hysteresis clutch is adjusted to an outage position to provide a slip torque less than the operating holding torque provided by the slewing mechanism brake, and the hysteresis clutch is adjusted to an operating position, at which the hysteresis clutch provides a slip torque at least as large as the operating holding torque of the slewing mechanism brake.

2. The method for orienting a crane (1) according to claim 1, characterized in that, the slip clutch is arranged between the slewing mechanism brake (8) and the slewing mechanism drive (7) or between the slewing mechanism motor (7) and the output gear (11).

3. A crane having a boom (3) capable of rotating about a vertical axis (5), a slewing mechanism motor (7) for rotating the boom (3) about the vertical axis (5), and a slewing mechanism brake (8) for braking rotation of the boom (3), characterized in that, in the transmission system of the slewing mechanism, a slip clutch (10) in the form of a hysteresis clutch is provided between the slewing mechanism motor (7) and the slewing mechanism brake (8) or between the slewing mechanism motor (7) and the output gear, the output gear engaging a rotating ring connected to the boom (3) in a non-rotatable manner, wherein outage control means are provided for adjusting the slip clutch (10) between an outage position and an operating position, at which the slip clutch (10) provides a slip torque less than the operating holding torque provided by the slewing mechanism brake (8), and at which the slip clutch (10) provides a slip torque at least as large as the holding torque of the slewing mechanism brake (8).

4. The crane according to claim 3, characterized in that, the hysteresis clutch is configured to have an adjustable clearance.

5. The crane according to claim 4, wherein, The hysteresis clutch has a tapered gap, wherein at least one of the half couplings of the hysteresis clutch is configured to be axially adjustable such that the radial clearance dimension and / or the axial length of the tapered gap is adjustable.

6. The crane according to claim 4, wherein, The hysteresis clutch has a cylindrical gap, wherein at least one of the half couplings of the hysteresis clutch is configured to be axially adjustable such that the axial length dimension of the cylindrical gap is adjustable.

7. The crane according to claim 3, wherein, The shutdown control device is configured to axially adjust at least one of the half couplings of the slip clutch (10).

8. The crane according to any one of claims 3-7, wherein, The slip clutch (10) is integrated in the rotary mechanism transmission (9) and is housed in the transmission housing of the rotary mechanism transmission (9).

9. The crane according to any one of claims 3-7, wherein, The rotary mechanism brake (8) is configured to be adjustable in its braking torque so as to be able to provide braking torques of different magnitudes. A shutdown control device is provided for adjusting the rotary mechanism brake (8) to a shutdown braking torque, and the shutdown braking torque is less than the holding torque provided during the operation of the crane.

10. The crane according to any one of claims 3-7, wherein, The rotary mechanism brake (8) is configured to be spring-driven and has a spring device, and the spring force of the spring device is adjustable to apply braking forces of different magnitudes.

11. The crane according to claim 10, wherein, The shutdown control device is configured to adjust the spring preload of the spring device such that the spring force provided by the spring device when the crane is shut down is less than the spring force provided during the expected operation of the crane.

12. The crane according to any one of claims 3-7, wherein, The rotary mechanism brake (8) has a composite friction lining.

13. The crane according to any one of claims 3-7, wherein, The shutdown braking torque is between 5% and 50% or between 5% and 25% of the holding torque provided during the operation of the crane.

14. The crane according to any one of claims 3-7, characterized in that The crane is a rotating tower crane.

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