EP4053065B1 - Device and method for controlling a crane rotational gear and crane - Google Patents

Description

The present invention relates to a device and a method for controlling a crane slewing gear and a crane, in particular a crawler crane, with such a device.

Most cranes, for example tower cranes, mobile cranes and ship or floating cranes, comprise an upper part with a boom (also referred to as the superstructure), which can be rotated via a slewing gear on a lower section of the crane (also referred to as the undercarriage). is stored. In the case of tower cranes, the superstructure can, for example, comprise the boom together with the counter-jib or the boom and the mast, which is mounted on a stationary undercarriage, while in mobile cranes the undercarriage typically has a wheel or crawler chassis for moving the crane, while the rotating superstructure next to the boom a rear ballast and other components such as guy stand, derrick boom, etc. can have. In the case of ship cranes, a floating body forms the undercarriage, while rail cranes have a rail vehicle that can be moved on rails as the undercarriage.

In all of these types of cranes, the jib (or jib system including guying and, if applicable, ballast) rotates about a vertical axis by an actuation of the slewing gear (which can also be referred to as a slewing ring). The crane slewing gears can usually be driven by one or more hydraulic motors and can have one or more holding brakes to fix the superstructure in a specific position. The latter are often also hydraulically driven.

Accelerations from different influences act on the entire crane structure, which are caused externally by the environment and/or internally by the crane operator driving the machine. The external influencing variables include the wind and heeling or inclination of the crane, the working load, the working radius, the dead weight and the experience of the crane operator. The properties of the drive and the sensitivity of the crane control can be named as internal influencing variables.

As a rule, the slewing motion of the crane can be driven at maximum power and speed without restriction, regardless of the possible crane configurations and loads. However, depending on the crane configuration and load capacity, improper operation of the slewing gear during operation, for example with crawler cranes, or the actuation of an emergency stop with abrupt braking of the slewing movement can lead to impermissibly high lateral forces and thus to damage or even the crane tipping over.

In the event of an emergency stop of category 0 or a machine failure, the slewing gear typically comes to an immediate stop. This leads to a significantly higher load on the cantilever structure. Without countermeasures, these circumstances lead to significantly higher moments of inertia and subsequently to significantly higher loads on the cantilever structure.

The document US5159813A discloses a device for controlling a crane slewing gear comprising a hydraulic motor by means of which the slewing gear can be driven or braked, a load detection device, an alignment detection device, a hydraulic limiting circuit by means of which a hydraulic pressure applied to the motor can be limited to a limit value, and a control unit which is connected to the limiting circuit connected is.

The present invention is therefore based on the task of reducing the risk of damage caused by improper operation or external influences caused by impermissibly high lateral forces or torques in cranes with a slewing gear.

According to the invention, this object is achieved by a device having the features of claim 1 and by a method having the features of claim 21 . Advantageous embodiments of the invention result from the dependent claims and the following description.

• mindestens einen hydraulischen Motor, mittels welchem das Drehwerk rotatorisch antreibbar oder abbremsbar ist,
• mindestens eine Haltebremse, mittels welcher das Drehwerk im Stillstand gehalten werden kann,
• einen hydraulischen Bremskreis, mittels welchem die Haltebremse hydraulisch steuerbar ist,
• eine Lasterfassungseinrichtung, mittels welcher eine momentan vom Kran aufgenommene Last erfassbar ist, und
• eine Ausrichtungserfassungseinrichtung, mittels welcher eine momentane Ausrichtung des Krans und/oder mindestens einer Krankomponente erfassbar ist.

According to the invention, a device for controlling a crane slewing gear is proposed, which comprises the following:

• at least one hydraulic motor, by means of which the slewing gear can be driven or braked in rotation,
• at least one holding brake, by means of which the slewing gear can be held at a standstill,
• a hydraulic brake circuit, by means of which the holding brake can be controlled hydraulically,
• a load detection device, by means of which a load currently picked up by the crane can be detected, and
• an alignment detection device, by means of which a current alignment of the crane and/or at least one crane component can be detected.

In addition to the load to be manipulated by the crane, the measured load also includes, in particular, traction equipment or hoisting ropes, load handling equipment (e.g. hook blocks), sling equipment and/or hangers. The load detection device can be a load cell. The slewing gear is held in a stationary position by means of the holding brake.

According to the invention, a hydraulic limiting circuit is provided, by means of which a hydraulic pressure applied to the engine can be limited to a specific limit value. Said hydraulic pressure can be a pressure difference.

Furthermore, a control unit is provided according to the invention, which is connected to the limiting circuit and set up, depending on at least the to determine a maximum permissible torque and/or a variable derived therefrom for a current rotational movement of the slewing gear based on the detected load and the detected alignment and, on this basis, to automatically limit an angular acceleration and/or angular velocity of the slewing gear by appropriate control or regulation of the limiting circle. This ensures that the torques acting on the crane structure do not exceed the maximum permissible torque.

The variable derived from the maximum permissible torque can be a maximum permissible angular acceleration. The corresponding control of the limiting circuit and thus of the slewing gear motor can take place in that a maximum permissible pressure resulting from the maximum permissible torque (or the derived variable), in particular differential pressure, is calculated for the hydraulic system and the pressure in the hydraulic system is limited to a corresponding range becomes. This can be the pressure difference between the supply lines or control lines of the slewing gear motor that are responsible for a right and a left movement. Accordingly, the derived variable can be this permissible differential pressure, on which the hydraulic control of the slewing gear is based. It is also conceivable that all of the aforementioned variables are calculated in the control unit.

According to the invention, the limiting and braking circuits are connected to one another or interconnected and set up such that if the control unit fails or an emergency stop of the crane is triggered, the slewing gear can be braked automatically while maintaining the slewing gear limitation. In other words, the load- and geometry-dependent slewing gear torque limitation according to the invention, which ensures that the torques acting on the crane structure do not exceed the maximum permissible torque, is effective even when braking due to an emergency stop or a failure of the power supply to the crane.

The device according to the invention implements a load and geometry-dependent slewing gear limitation, taking into account the relevant influencing variables, in which the measurements and calculations required for slewing gear limitation and the corresponding control or regulation of the slewing gear drive are carried out automatically. The crane driver does not have to actively intervene in the control process, so that the potential for danger due to incorrect operation is minimized. For safety reasons, an active influence on the control or regulation process can even be completely ruled out.

Due to the usually very high number of possible equipment variants (especially in the case of mobile cranes), the approach according to the invention is superior to simply limiting the boom head speed and/or acceleration to a maximum permissible value. For example, the interaction of the influences of load capacity and boom dead weight changes significantly with the respective equipment status. For example, when using a short main boom and maximum lifting capacity, the maximum permissible lifting capacity (also referred to as SWL - "safe working load" -) is the main determining factor, while when using a main boom with a long luffing needle, the dead loads of the boom system are the main determining factor.

All of these influences of alignment, setup, load and other relevant factors are preferably automatically taken into account by the slewing gear limitation according to the invention and are automatically converted into a safe rotary movement by appropriate control of the drive.

The load and geometry-dependent slewing gear torque limit or slewing gear limitation protects the structure of the crane from being overloaded by the slewing gear. The device according to the invention limits the maximum possible torque when accelerating and/or decelerating the slewing gear to a maximum permissible value, both during operation and in the event of an emergency stop, a power failure or some other fault. The initial value here is in particular the maximum permissible angular acceleration of the superstructure with the existing Utilization of the maximum structure load capacity. From this, a maximum permissible torque or a maximum permissible pressure in the slewing gear is calculated according to the crane configuration, the current load and the current angular positions. In particular, the slewing gear pressure is limited to this maximum permissible pressure by the system. If a constant delay time is to be ensured, the crane rotation speed can also be limited by the device according to the invention.

In one possible embodiment, it is provided that the control unit is set up to take into account current geometry data of the crane for determining the maximum permissible torque and/or the variable derived therefrom. These can be read in directly via suitable sensors and/or stored in the control unit or in a memory to which the control unit has access. So it is conceivable that a database with the relevant data for all possible set-up states is stored in the crane and the crane driver selects the current set-up state (for example the current boom configuration and/or ballasting) in advance. Automatic detection of the current crane configuration via appropriate sensors is also possible. Provision of geometry data via a wireless communication channel is also conceivable, for example access by the control unit to a cloud with the stored data.

Preferably, the geometric data relate to a set-up state, a dimension, a mass, the position of a center of gravity and/or a moment of inertia of the crane and/or at least one of its components. The geometric data contain in particular all relevant component masses, center of gravity coordinates and dimensions of the entire machine or at least of the components of the crane that are decisive for the calculation of the permissible torque. The moments of inertia of the components can also be calculated by the control unit from other geometric data.

In a further possible embodiment it is provided that the control unit is set up to determine the maximum permissible torque and/or the variable derived therefrom to take current environmental data into account, with the environmental data preferably relating to a wind direction and/or wind strength detected by at least one wind measuring device. From this, the wind load acting on the crane can be determined, in particular with recourse to the previously mentioned geometric data of the crane. The wind measuring device is preferably positioned at the boom tip (e.g. at the tip of a seesaw needle) and may comprise an anemometer. However, several wind measuring devices distributed over the crane can also be used to determine the instantaneous wind load more precisely.

In a further possible embodiment, it is provided that the load currently being picked up by the crane and the current orientation of the crane can be detected in real time and made available to the control unit. This also applies in particular to the measured environmental conditions, in particular the wind load. The measurements can be taken at regular time intervals during the operating life of the crane. The control unit is set up to adapt the maximum permissible torque and/or the variable derived therefrom for the current rotational movement of the slewing gear and the corresponding control or regulation of the limiting circuit as a function of the measurements in real time. Any change in the relevant influencing variables thus immediately leads to an adjustment or recalculation of the limit values on which the slewing gear limitation according to the invention is based, and thus to a change in the actuation of the slewing gear.

In a further possible embodiment it is provided that the current alignment of the crane relates to a current boom angle, a current inclination or heeling of the crane and/or a current slewing gear or slewing platform angle. In a more complex boom configuration, for example using a main boom and a seesaw attached thereto, multiple angles between the respective boom components may also be measurable to capture the overall alignment. Should it be the outrigger If it is a telescopic jib, the telescoping state or the telescopic length also counts in particular for the detectable alignment. The angle or angles can be measurable via angle sensors. The current working radius in particular results from the measured angles in combination with the known dimensions of the crane. The inclination or heeling can be measured using one or more electrical inclination sensors.

In a further possible embodiment, a simulation means is provided, which is set up to use a physical simulation model of the crane or at least one crane component, taking into account at least a current set-up status, a current alignment and a current lifted load of the crane, the maximum permissible torque and/or the torque thereof to calculate the derived variable for the current rotary movement of the slewing gear. The simulation means can be provided in the control unit or can be executed by the control unit or can be implemented/executable in a separate simulation unit connected to the control unit. The simulation unit can be located in the crane or outside of the crane (e.g. in the form of a cloud).

In a further possible embodiment, it is provided that the control unit is set up to calculate a maximum permissible hydraulic differential pressure and, on this basis, an angular acceleration and/or angular velocity of the slewing gear by appropriate control or regulation of the limiting circuit, in particular by appropriate electrical actuation of a limit pressure adjustment valve of the bounding circle to limit automatically. The differential pressure is in particular the pressure difference between the control lines of the drive or motor responsible for a right and a left movement.

In a further possible embodiment it is provided that the brake circuit comprises a first hydraulic accumulator and a brake valve, with the holding brake, in particular a pressure chamber of the holding brake, being connected to a control pressure line via the brake valve in a first position of the brake valve and in a second Position of the brake valve can be connected to a hydraulic tank or a tank line or to the first hydraulic accumulator. The brake valve is preferably electrically controllable and is in the de-energized state in particular in the second position. The control pressure is, in particular, a comparatively low pressure level that is introduced into a control pressure line in order to activate certain functions. At the same time, the control pressure can be applied to a valve of the limiting circuit. The first hydraulic accumulator can preferably be charged with control pressure via a check valve. The brake valve can be a binary directional control valve.

In a further possible embodiment, it is provided that the brake circuit includes a changeover valve, via which the brake valve can be connected to the tank or to the first hydraulic accumulator in the second position, the changeover valve preferably being hydraulically controllable via a control connection. The switching valve is preferably a binary directional control valve. In the non-activated state, it preferably connects the brake valve to the tank, with the brake valve connecting in particular the holding brake to the changeover valve in the non-activated state. If the brake and changeover valves are not actuated, the holding brake is preferably relieved to the tank and is therefore applied.

In a further possible embodiment it is provided that the control connection of the switching valve can be connected to the tank or a tank line or to a high-pressure line of the limiting circuit via a first safety valve of the brake circuit. The maximum of the operating pressures of the control lines preferably always prevails in the high-pressure line. The first safety valve can be electrically controllable. Alternatively, it can be hydraulically controllable via a signal line ("slewing gear on") that can be pressurized when the slewing gear is actuated. The first safety valve is preferably switched in a non-controlled state (control current or control pressure below the set control threshold of the valve) in such a way that the control port of the changeover valve connected to the high-pressure line. The first safety valve can preferably be switched electrically or hydraulically together with a second safety valve of the limiting circuit.

In a further possible embodiment, it is provided that the brake circuit is set up to automatically switch the brake valve to the second position and to the first hydraulic accumulator in the event of a failure of the control unit (e.g. due to a failure of the power supply) and/or if an emergency stop of the slewing gear is triggered connect to. In this state, the first hydraulic accumulator is preferably connected to the tank via a throttle unit, so that the first hydraulic accumulator slowly discharges. As a result, in the event of a failure of the control unit or an emergency stop, the holding brake is initially held open above the pressure level prevailing in the hydraulic accumulator (which in particular corresponds to the control pressure level immediately before the failure/emergency stop). If the pressure level in the accumulator falls below a minimum brake release pressure, the holding brake applies. The slewing gear therefore initially remains controlled and limited in the event of a loss of power supply or an emergency stop.

In a further possible embodiment, it is provided that the limiting circuit comprises two hydraulic control lines, each causing a left or right rotation of the slewing gear, and a hydraulic pressure limiting device, the latter being set up to connect the control lines to one another in a hydraulically conductive manner (so that the oil from the line with a higher pressure flows into the line with the lower pressure) if the pressure difference in the control lines exceeds a limit pressure which is dependent on the determined maximum permissible torque. This limits the motor controlled via the control lines and thus the slewing gear movement.

In a further possible embodiment, it is provided that the pressure-limiting device comprises at least one hydraulic pressure-limiting valve, via which the control lines can be connected to one another in a hydraulically conductive manner and which can be hydraulically controlled or pilot-controlled via a pilot control line, the pilot control pressure prevailing in the pilot control line being adjustable via a hydraulic limit pressure circuit as a function of the determined maximum permissible torque. The limit pressure circuit ensures that the at least one pressure relief valve opens when the pressure difference in the control lines exceeds a specific limit value or limit pressure, which is dependent on the permissible torque determined by the control unit or the permissible angular acceleration. One pressure-limiting valve is preferably provided for each control line.

In a further possible embodiment it is provided that the limit pressure circuit comprises a differential pressure valve which is set up to connect the pilot control line to a tank when the limit pressure is exceeded by the pressure difference in the control lines, the differential pressure valve preferably being hydraulically controllable via a limit pressure line. The differential pressure valve can be a pressure compensator, which opens when the pressure present at a high-pressure port exceeds the sum of a limit pressure present at a differential pressure port and a low pressure present at a low-pressure port. In this case, the differential pressure valve can be controlled via the limit pressure line in particular in that the limit pressure defines the pressure difference between the other connections at which the differential pressure valve switches or opens.

The high-pressure connection is preferably supplied with the maximum and the low-pressure connection with the minimum of the operating pressures prevailing in the control lines, optionally reduced by a defined factor via one or more throttles. Depending on the direction of rotation of the slewing gear, the pressure in one of the two control lines is higher and forms the "high pressure" in the high-pressure line, which runs to the high-pressure connection of the differential pressure valve. The pressure of the other line forms the low pressure. As a result, by selecting the limiting pressure, that pressure difference between the control lines can be set at which the at least one pressure-limiting valve opens and the slewing gear limitation begins.

In a further possible embodiment it is provided that the limit pressure circuit comprises a second hydraulic accumulator which is connected to the limit pressure line and which can be connected to a control pressure line via a second safety valve of the limit pressure circuit. The control pressure line is preferably also connected to the brake pressure valve and via a check valve to the first hydraulic accumulator. The second safety valve can be electrically controlled. Alternatively, it can be hydraulically controllable via a signal line ("slewing gear on") that can be pressurized when the slewing gear is actuated. The signal line can operate/control the first safety valve at the same time. The second safety valve can preferably be switched electrically or hydraulically together with a first safety valve of the brake circuit.

In another possible embodiment, it is provided that the limit pressure circuit includes a limit pressure adjustment valve that can be controlled by the control unit, by means of which the limit pressure line can be connected to a control pressure line (in particular the control pressure line described above) and the limit pressure can be adjusted as a function of the determined maximum permissible torque. The limit pressure adjustment valve can have a falling characteristic so that the maximum limit pressure is set when there is no activation (provided that the control pressure in the control pressure line is > zero). The implementation of the load-dependent and geometry-dependent slewing gear limitation according to the invention thus takes place via the limit pressure circuit and in particular via a corresponding setting of the limit pressure by the limit pressure adjustment valve.

In a further possible embodiment, it is provided that the limiting circuit is set up to automatically disconnect the second hydraulic accumulator from the control line in the event of a failure of the control unit and/or if an emergency stop of the slewing gear is triggered, so that the pressure of the second hydraulic accumulator prevails in the limit pressure line. The connection can be separated by switching the second safety valve. Thus, the slewing gear limitation according to the invention is maintained even in the event of a failure of the power supply or control unit or in the event of an emergency stop.

In a further possible embodiment, it is provided that the high-pressure line is connected to the control lines via a valve arrangement in such a way that the higher pressure of the control lines always prevails in it, with the valve arrangement preferably comprising two valves, in particular check valves, via which one of the control lines each connected to the high-pressure line. Analogously, the low-pressure line can be connected to the control lines via valves, in particular check valves, in such a way that its pressure level ("low pressure") is always limited to the minimum of the pressures in the control lines.

In a further possible embodiment it is provided that an emergency stop or emergency stop function is provided, which can be triggered by the crane operator and/or automatically by the control unit if an emergency stop is triggered, whereby the power supply can be switched off automatically as a result of the triggering of the emergency stop function and/or the slewing gear can be braked automatically while maintaining the slewing gear limitation. As a result, abrupt braking, which can lead to impermissibly high accelerations occurring, can be avoided.

The present invention further relates to a crane with a slewing gear and a device according to the invention for controlling the slewing gear. The slewing gear can include one or more slewing gear motors, which can be limited or controlled via the device according to the invention. This obviously results in the same advantages and properties as for the device according to the invention, which is why a repeated description is dispensed with at this point. The crane can be a crawler crane.

• Erfassung einer momentan vom Kran aufgenommenen Last,
• Erfassung einer momentanen Ausrichtung des Krans und/oder einer Krankomponente,
• Ermittlung eines maximal zulässigen Drehmoments und/oder einer davon abgeleiteten Größe für eine aktuelle Drehbewegung des Drehwerks in Abhängigkeit wenigstens der erfassten Last und der erfassten Ausrichtung,
• Steuern oder Regeln eines Antriebsmotors des Drehwerks derart, dass die Winkelbeschleunigung und/oder Winkelgeschwindigkeit des Drehwerks auf einen vom maximal zulässigen Drehmoment abhängigen Wert begrenzt ist / sind, und
• bei einem Ausfall der Steuereinheit oder der Auslösung eines Notstopps, automatisches Abbremsen des Drehwerk, sodass die maximal zulässige Winkelbeschleunigung und/oder Winkelgeschwindigkeit des Drehwerks nicht überschritten wird / werden.

The present invention further relates to a method for controlling a slewing crane using the device according to the invention with the following steps:

• Detection of a load currently picked up by the crane,
• Detection of a current orientation of the crane and/or a crane component,
• Determination of a maximum permissible torque and/or a variable derived therefrom for a current rotational movement of the slewing gear as a function of at least the detected load and the detected orientation,
• Controlling or regulating a drive motor of the slewing gear in such a way that the angular acceleration and/or angular velocity of the slewing gear is/are limited to a value dependent on the maximum permissible torque, and
• if the control unit fails or an emergency stop is triggered, automatic braking of the slewing gear so that the maximum permissible angular acceleration and/or angular velocity of the slewing gear is/are not exceeded.

Here, too, the advantages and properties are obviously the same as for the device according to the invention, which is why a repeated description is dispensed with at this point.

Figur 1:

eine schematische Darstellung der erfindungsgemäßen Vorrichtung zur Steuerung des Krandrehwerks gemäß einem Ausführungsbeispiel;

Figur 2:

verschiedene Ansichten eines Krans mit einem über die erfindungsgemäße Vorrichtung gesteuerten Drehwerk gemäß einem Ausführungsbeispiel, wobei verschiedene Elemente der erfindungsgemäßen Vorrichtung und deren Anordnung gezeigt sind; und

Figur 3:

einen Schaltplan des zur Steuerung des Drehwerksmotors verwendeten Hydrauliksystems gemäß einem Ausführungsbeispiel.

Further features, details and advantages of the invention result from the exemplary embodiments explained below with reference to the figures. Show it:

Figure 1:

a schematic representation of the inventive device for controlling the crane slewing gear according to an embodiment;

Figure 2:

various views of a crane with a slewing gear controlled via the device according to the invention according to an exemplary embodiment, wherein various elements of the device according to the invention and their arrangement are shown; and

Figure 3:

a circuit diagram of the hydraulic system used to control the slewing gear motor according to an embodiment.

The figure 1 shows in a block diagram the components and influencing factors of the device according to the invention and the method according to the invention for controlling a slewing gear 10 of a crane 1. The permissible torque or the permissible angular acceleration for the slewing gear movement is calculated in a control unit 20, which is in the exemplary embodiments considered here are the CPU of the crane controller.

In the following embodiment, a crawler crane 1 is considered, which in the figure 2 is shown. The crawler crane 1 comprises an undercarriage 2 with crawler undercarriages and an uppercarriage 3 mounted on the undercarriage 2 so that it can rotate about a vertical axis via a slewing gear 10. The uppercarriage 3 has a boom 4 that can pivot about a horizontal axis, which in the exemplary embodiment considered here is a main boom 4a and a rocking needle 4a, which are braced over guy structures. At the rear, the superstructure 3 has a superstructure or rear ballast 5 with two lateral stacks of several ballast plates. The guying of the main boom 4a takes place via a guying frame 7, which is mounted on the superstructure 3 so that it can pivot about a horizontal axis.

In the figure 2 shows sections of various components of the crane 1 with elements of the device according to the invention, such as crane sensors or slewing gear components. The slewing gear 10 can be seen at the bottom right, which comprises a large-diameter bearing 6 and several motors 12 driving the large-diameter bearing 6 via pinions. At the tip of the seesaw needle 4b is an anemometer 19 for determining the current wind load.

The crane slewing gear 10 is controlled hydraulically, with an exemplary embodiment of the hydraulic system in FIG figure 3 shown and described below. For the sake of simplicity, in the figure 3 only one slewing gear motor 12 is shown.

1. Overview

Depending on the crane configuration and load capacity, incorrect operation of the slewing gear during operation or activation of the emergency stop can lead to inadmissibly high transverse forces. In the event of an emergency stop of category 0 or a failure of the machine, the power supply to the drive element(s) is immediately interrupted and the holding brake(s) of the slewing gear is/are applied. This leads to a significantly higher load on the cantilever structure. Without countermeasures, these circumstances lead to significantly higher moments of inertia and subsequently to significantly higher loads on the cantilever structure.

According to the invention, a load and geometry-dependent slewing gear torque limitation (hereinafter also simply referred to as slewing gear limitation) is selected as a solution. The initial value is the maximum permissible angular acceleration of the superstructure 3 when the maximum structural load is utilized. From this, a maximum permissible torque or a maximum permissible pressure in the slewing gear 10 is calculated according to the crane configuration, the current load and the current angular positions. The device according to the invention limits the slewing gear pressure to this maximum permissible pressure.

Since a constant delay time is to be guaranteed, the crane rotation speed is also limited. The slewing gear limitation also takes effect in the event of an emergency stop or failure of the crane control 20. In these cases, at least one hydraulic accumulator means that the maximum permissible pressure in the slewing gear 10 continues to be limited to the last permissible value and the holding brake 14 is applied until the slewing movement comes to a standstill, but no longer than for a few seconds, kept open.

In the valid load table range, the slewing gear torque limitation is permanently active, unless switched off via a correction value.

definiert. Hierbei bezeichnen ΣI(AL) _x die Summe der Trägheitsmomente I(AL) der verschiedenen Auslegerteile, d.h. das Gesamtträgheitsmoment des Auslegers 4, I(OW) das Trägheitsmoment des Oberwagens 3, I(WL) das Trägheitsmoment der Arbeitslast, α_zul die maximal zulässige Winkelbeschleunigung, M(FQ[%]) das sich aus der maximal zulässigen Querkraft ergebende Drehmoment, M(W) das sich aus der momentanen Windlast ergebende Moment und M(K) das sich aus der momentanen Krängung bzw. Schräglage des Krans 1 ergebende Moment.The permissible angular acceleration is determined using the initial equation: $$\left({\displaystyle \sum I{\left(\mathit{AL}\right)}_x+I\left(\mathit{OW}\right)+I\left(\mathit{WL}\right)}\right)\cdot a_{\mathit{allowed}}\le M\left(\mathit{fq}\left[\%\right]\right)-M\left(W\right)-M\left(K\right)$$

Are defined. Here Σ I ( AL ) _x denote the sum of the moments of inertia I ( AL ) of the various boom parts, i.e. the total moment of inertia of the boom 4, I(OW) the moment of inertia of the superstructure 3, I(WL) the moment of inertia of the working load, α _perm the maximum permissible angular acceleration, M ( FQ [ % ]) the torque resulting from the maximum permissible transverse force, M ( W ) the moment resulting from the current wind load and M ( K ) the torque resulting from the current heeling or inclined position of the crane 1 Moment.

For this purpose, the following influencing variables are fed to the CPU or control unit 20, ie the physical simulation model executed by it.

a) Influences from geometry data

The geometry information includes all relevant component masses, center of gravity coordinates and dimensions of the entire machine. These are supplied to the physical simulation model by preselecting the device setup state required for safe crane operation.

b) Influences from crane sensors

The influencing variables from the current workload and the current working radius are recorded via the force measuring straps 16, angle sensors 18 and pressure sensors and are also supplied to the physical simulation model. The working load is the total load resulting from the hoisting ropes, bottom blocks, slings, hangers and the load to be manipulated.

c) Influences from disturbance variables

Disturbance variables are those variables that can also have an effect on the crane system from outside, essentially beyond their control. These are in particular the heeling or inclined position of the machine and the wind load. The wind speed is recorded by means of an anemometer 19, the heeling by means of at least one electric inclination sensor 17 and is also supplied to the physical simulation model.

The physical simulation model calculates the maximum permissible boom angular accelerations in real time, taking into account all influences from a) - c), which in turn are converted into the maximum permissible slewing gear differential pressures and used to control the crane slewing gear 10 .

Any changes in the influencing variables, individually or in any superimposition, as listed under a) - c), immediately lead to changes in the control of the slewing gear 10. The change in the control of the slewing gear 10 is always determined from the calculated, permissible boom angular acceleration α _perm and limited.

The hydraulic brake system is combined with the load and geometry-dependent slewing gear limitation to ensure the permissible braking acceleration even in the event of an abrupt loss of energy supply, e.g. if an emergency stop button is pressed or other events that lead to an abrupt loss of energy supply.

A concrete example for the implementation of the load and geometry-dependent slewing gear limitation according to the invention is described below.

2. Calculation algorithm

When decelerating due to an emergency stop or machine failure, the same approaches apply in principle as when accelerating or decelerating in normal crane operation. Therewith the same specified limits apply. All the necessary calculation variables for the following initial equation are already available either in the GEO files, in the structural data or in the software as existing parameters.

3. Determining the moment of inertia of the basic device

The basic device is loaded into 3D CAD software and measured in its standard state (superstructure 3, winches, standard equipment, etc.). The mass moment of inertia in the z-axis of the entire superstructure including the winches is included as a constant in the GEO file "superstructure". The rear ballast 5 and the A-frame 7 are not included in the superstructure model and are calculated separately (e.g. partial ballasting). The total moment of inertia J _total [kgm ² ] is calculated from: $$J_{\mathit{in\; total}}=J_{\mathit{OW}}+J_{\mathit{AWAY}}+J_{\mathit{hb}}+J_D+J_{\mathit{DB}}.$$

J _OW denotes the mass moment of inertia of the superstructure 3 (geo file specification), J _AB the mass moment of inertia of the guy stand or A-frame 7, J _HB the mass moment of inertia of the rear ballast 5 (e.g. calculated from the mass of the rear ballast 5 multiplied by the radius of the center of gravity to the center of rotation), J _D is the mass moment of inertia of the derrick boom (if one is attached) and J _DB is the mass moment of inertia of the derrick ballast (if one is used).

3. Calculation of permissible angular acceleration

The permissible angular acceleration α _per is calculated with the existing utilization of the maximum structural load as a special load case without wind and heeling, since these permissible forces can only occur in an emergency stop or outside of standard operation. The permissible angular acceleration α _perm is output as a curve (over several points) depending on the utilization of the maximum structural load.

4. Calculation of the mass moments of inertia

$$J_{\mathit{WL}}={\displaystyle \sum \left(m{\left(\mathit{WL}\right)}_x\cdot r{\left(\mathit{WL}\right)}_x^2\right)},$$

wobei J_AL [kgm²] das Massenträgheitsmoment des Auslegersystems, m(AL) _x [kg] die Masse eines einzelnen Auslegerelements (z.B. Anlenkstück, Zwischenstück, Kopf etc.), r(AL) _x [m] den Schwerpunktabstand des betreffenden Auslegerstücks vom Rotationszentrum, J_WL [kgm²] das Massenträgheitsmoment der Arbeitslasten, m(WL) _x [kg] die Masse einer einzelnen Arbeitslast (WL, "working load") und r(AL) _x [m] den Arbeitsradius der betreffenden Arbeitslast bezeichnen.The mass moments of inertia from boom segments and working loads are calculated as follows: $$J_{\mathit{AL}}={\displaystyle \sum \left(m{\left(\mathit{AL}\right)}_x\cdot \mathrm{right}{\left(\mathit{AL}\right)}_x^2\right)},$$

$$J_{\mathit{WL}}={\displaystyle \sum \left(m{\left(\mathit{WL}\right)}_x\cdot \mathrm{right}{\left(\mathit{WL}\right)}_x^2\right)},$$

where J _AL [kgm ² ] is the mass moment of inertia of the boom system, m ( AL ) _x [kg] the mass of an individual boom element (e.g. pivot piece, intermediate piece, head etc.), r ( AL ) _x [m] the center of gravity distance of the boom section in question from the center of rotation, J _WL [kgm ² ] the mass moment of inertia of the workloads, m ( WL ) _x [kg] the mass of a single workload (WL) and r ( AL ) _x [m] the working radius of the workload in question.

5. Calculation of the permissible slewing gear pressure

From the data of the installed slewing gear motors 12, the motor equipment, the number of motors 12, the known moments of inertia, the limit torque of the boom 4 and the friction losses, the pressure difference for controlling the slewing gear can be calculated. If a permanently specified maximum angular acceleration α _max is defined for crane 1, the maximum permissible angular acceleration for crane 1 in the current configuration and alignment is the lower value of α _perm and α _max . The value for α _max is stored in the crane controller or in a memory or in a file loaded at the start of operation. For the sake of simplicity, it is only mentioned below that the relevant value is stored "in the crane controller".

bzw. $$M_{\mathit{DW}}=M_{\mathit{mot}}\cdot \left({\mathit{\Delta p}}_{\mathit{zul}}+{\mathit{\Delta p}}_{\mathit{reib}}\right)\cdot f\cdot i\cdot \frac{Z\left(R\right)}{Z\left(G\right)}.$$

The previously considered total mass moment of inertia J _total multiplied by the permissible angular acceleration α _perm results in the torque on the slewing gear M _DM , which is defined using constant values and the pressure difference: $$M_{\mathit{DW}}=J_{\mathit{in\; total}}\cdot a_{\mathit{allowed}}$$

or. $$M_{\mathit{DW}}=M_{\mathit{engines}}\cdot \left({\mathit{\Delta p}}_{\mathit{allowed}}+{\mathit{\Delta p}}_{\mathit{rub}}\right)\cdot f\cdot i\cdot \frac{Z\left(R\right)}{Z\left(G\right)}.$$

wobei Δp_reib [bar] den krantypabhängigen Druckverlust durch Reibung (z.B. ermittelt durch Versuch), α_zul [1/s] die durch das physikalische Simulationsmodell berechnete maximal zulässige Winkelbeschleunigung, / die Anzahl der Drehwerksmotoren 12, i das Übersetzungsverhältnis des Drehwerks, Z(R) die Zähnezahl des das Großwälzlager 6 antreibenden Ritzels, Z(G) die Zähnezahl des Großwälzlagers 6, M_mot [Nm/bar] das motorspezifische Drehmoment und J_gesamt [kgm²] das Gesamtmassenträgheitsmoment des Krans 1 samt Last darstellen.This results in the maximum permissible pressure difference Δp _perm for controlling the slewing gear motor 12: $${\mathit{\Delta p}}_{\mathit{allowed}}=\frac{J_{\mathit{in\; total}}\cdot a_{\mathit{allowed}}}{f\cdot i\cdot M_{\mathit{engines}}}\cdot \frac{Z\left(R\right)}{Z\left(G\right)}-{\mathit{\Delta p}}_{\mathit{rub}},$$

where Δ p _friction [bar] is the pressure loss dependent on the crane type due to friction (e.g. determined by testing), α _per [1/s] the maximum permissible angular acceleration calculated using the physical simulation model, / the number of slewing gear motors 12, i the transmission ratio of the slewing gear, Z (R) the number of teeth of the pinion driving the slewing bearing 6, Z(G) the number of teeth of the slewing bearing 6, M _mot [Nm/bar] the motor-specific torque and J _total [kgm ² ] the total mass moment of inertia of the crane 1 including the load.

6. Determination of Δ p _friction by experiment

The friction loss Δ p _friction at maximum speeds of the individual slewing gear stages is determined on the basis of tests on the test bench. These are type-dependent and therefore variable. The loss pressure is necessary to maintain a constant speed and is measured at the slewing gear motor 12 by the crane 1 at a constant Rotational speed is rotated in the second stage. The measured pressure loss corresponds to the friction losses in slewing gear stage 2. For practical reasons, a fixed value for Δ p _friction can also be deducted here.

7. Limitation to Δ p _mαx

The previously determined maximum permissible differential pressure of the hydraulic system Δp _perm is limited to a specified Δp _max [bar], which is stored in the crane control. This ensures that crane 1 cannot reach a speed that cannot be slowed down within an integration time set on crane 1. In an open hydraulic system, the maximum differential pressure corresponds to the maximum absolute pressure. In a closed system, on the other hand, the maximum differential pressure corresponds to the difference between the maximum absolute pressure and the feed pressure.

8. Consideration of the minimum differential pressure Δ p _min

The required minimum differential pressure Δ p _min in the hydraulic system depends on the system and is stored in the crane control. If the calculated maximum permissible differential pressure Δ p _perm is less than Δ p _min , the calculated value must be set to Δ p _min . However, it is preferably ensured in advance that there are no crane configurations for which Δp _perm is below Δp _min (eg 80 bar).

9. Determination of the maximum permitted crane slewing speed

From the permissible angular acceleration α _perm that is now available, the permissible crane slewing speed can be determined in order to safely come to a standstill within the given integration time. The minimum integration time t _min is stored in the crane controller and can be a few seconds. The achievable boom head speed depending on the permissible angular acceleration α _perm is described with the following equation or the following algorithm:

Here, v(K) [m/min] denotes the boom head speed without limit for a maximum permissible speed, t [s] the integration time from the slewing gear slide (set on the device), t _min [s] the minimum integration time that can be set on the device (t ≥ t _min ) and r [m] the working radius of the working load and F _Q as the permissible lateral force. With the term (Δ p _max +Δ p _friction )/(Δ p _zul +Δ p _friction ), too high α _zul is normalized to an angular acceleration ∝ that can be achieved with Δ p _mαx . This ensures that the device can be brought to a standstill with the maximum possible pressure difference Δ p _max within the integration time t . The factor 60 is used to convert to m/min.

wobei v_max,Kopf [m/min] die maximal zulässige Kopfgeschwindigkeit unabhängig vom Arbeitsradius und v_max,Pers [m/min] die maximal zulässige Kopfgeschwindigkeit unabhängig vom Arbeitsradius bei einem Personentransport bezeichnen.In the case of passenger transport and/or derrick operation, v ( K ) can additionally be limited to a specific maximum value, for example to 30 m/min. In the case of derrick operation, the crane rotation speed can likewise be limited to a maximum value, for example to 0.2 rpm. This can be done using the following algorithm:

where v _max,head [m/min] denotes the maximum permitted head speed independent of the working radius and v _max,pers [m/min] denotes the maximum permitted head speed independent of the working radius when transporting people.

wobei n_zul [1/min] die Krandrehgeschwindigkeit in Abhängigkeit von der maximal zulässigen Winkelbeschleunigung ∝ _zul und r_max den Radius des am weitesten entfernten Kopfes darstellen.The resulting crane slewing speed follows the equation: $$n_{\mathit{allowed}}=\frac{v\left(K\right)}{2\cdot \pi \cdot {\mathrm{right}}_{\mathit{Max}}},$$

where n _perm [rpm] is the crane rotation speed depending on the maximum permissible angular acceleration ∝ _perm and r _max is the radius of the furthest head.

With DWB _{max,revolution} [1/min] as the maximum permissible rotation speed per mode (which can be stored in the crane control), the result is:

10. Implementation of the slewing gear limitation in derrick operation

The slewing gear limitation is not active in derrick mode. In derrick mode, the head speed is reduced to 30 m/min and the maximum rotational speed to 0.2 rpm.

11. Slewing gear limitation for floating bodies

In the case of operation on floating bodies or "floating units" (e.g. ship crane), it is assumed that the inclination is caused by the load on the crane 10 . If the jib 4 of the crane 1 is not in the axis of symmetry of the floating body, there is also a lateral inclination in addition to the inclination in the direction of the jib. This condition leads to an increase in tilting moment, which is correctly recorded and taken into account by appropriate sensors. Under this consideration, the rear ballast 5 becomes the driving or braking influencing variable during operation. Small lateral inclinations (<1%) are usually negligible.

12. Scope of Validity

The load and geometry-dependent slewing gear torque limitation can be provided, for example, for all operating modes without derrick and can be switched off via a correction value.

13. Consideration of wind

When considering the wind, only the driving and the braking influence can be considered separately. It can usually be ruled out that the wind suddenly changes from driving to braking, i.e. without any time delay. If the wind is driving, the delay time increases, but the load on the boom 4 remains unchanged because the allowable pressure remains unchanged.

If the wind has a braking effect, the delay time is shortened, but the load on the boom 4 remains unchanged since the permissible pressure remains unchanged.

14. Impact of load swing on the structure

In normal crane operation, the swinging of the load is controlled and minimized by the crane operator. Since the load and geometry-dependent slewing gear torque limitation is not a driver assistance system, but has to fulfill the function of pure "boom protection", only the emergency stop load case is included in the consideration.

15. Normalization operating lever

If the rotational speed is limited, a dead travel occurs with a master switch control. The reason for this is that the maximum permissible rotation speed depends on the current geometric position and the measured values of the device. This value therefore changes constantly during operation. However, the standardization of the master switch must not be influenced by this, otherwise the device can no longer be moved.

16. Hydraulic system

In the figure 3 a circuit diagram of an exemplary embodiment of the hydraulic system of the crane 1 for driving the slewing gear 10 and for controlling the motor 12 is shown.

The slewing gear 10 is controlled by a hydraulic motor 12 which drives a shaft 13 in rotation. Of course, several such motors 12 can also be provided as the slewing gear drive. The two pressure or control lines R and L for hydraulically driving the motor 12 are supplied with hydraulic oil from an energy source not shown here. For a clockwise rotation of the slewing gear 10, the control line R and for a counterclockwise rotation, the control line L with a corresponding operating pressure. When the slewing gear 10 is actuated, one of the two control lines R, L always has a higher pressure level than the other. A pressure sensor 30, 32 is connected to each control line R, L.

The hydraulic system has a brake circuit 100, a limiting circuit 200 and a limit pressure or differential pressure circuit 201 (the latter can also be regarded as part of the limiting circuit 200). The brake circuit 100 can be housed in its own brake block. Likewise, the limiting circuit 200 can be accommodated in its own limiting block and/or the limit pressure circuit 201 in its own limit pressure block or differential pressure block. The lines leading into a hydraulic tank are referred to below as tank line T. For the sake of simplicity, the tank itself is also provided with the reference symbol T.

Pilot operated secondary pressure relief valves 220, 222 are installed between the two control lines R, L of the drive 12 in such a way that they direct oil from the high pressure side to the low pressure side when responding.

Via the non-return valves 224, 226, the current operating pressure is taken from the higher-pressure side of the control lines R and L with the "high pressure" signal and fed to the differential pressure control. Different pressures can prevail in the high-pressure line H, which is provided with the reference character H in FIG. 3, since throttles are arranged at different positions. From "high pressure" a signal or pressure level is generated via the throttle 218, which is limited via the check valves 214 and 216 to "low pressure", i.e. to the smaller of the pressure levels prevailing in the control lines R, L and is fed to the differential pressure control. Regardless of the direction of rotation of the slewing gear 10, "high pressure" denotes the maximum and "low pressure" the minimum of the operating pressures "right" and "left" of the slewing gear 10.

The current operating pressure is measured via the throttles 228 and 229 and the differential pressure valve 206, which is designed as a pressure compensator in this exemplary embodiment ("high pressure") converted to a pilot pressure. This pilot pressure acts via the throttles 230 and 232 as pilot control on the pressure-limiting valves 220 and 222.

The "high pressure" signal (i.e. the pressure prevailing in the high pressure line H after the restrictor 228) acts on the high pressure side of the pressure compensator 206 to open it. The "low pressure" signal (i.e. the pressure prevailing in the low-pressure line N) acts on the low-pressure side of the pressure compensator 206 to close it, supported by a "pressure difference signal" from the pressure control, which differs from the pressure prevailing in the limit pressure line G (limit pressure ) results.

The pressure compensator 206 opens when the "high pressure" signal exceeds the value formed from "low pressure" and "pressure difference signal". In this case, the pilot pressure (i.e. the pressure prevailing after the throttles 230 and 232) is diverted into the tank and the pressure setting of the secondary pressure limitations 220, 222 is thus controlled or changed.

The differential pressure is controlled via an electrically controllable, proportional limit pressure adjustment valve 204, which is designed here as a pressure-reducing valve. A control pressure which defines the maximum differential pressure between the control lines R, L is present at the limit pressure adjustment valve 204 . The control pressure is converted by the limit pressure setting valve 204 into the limit pressure present at the pressure compensator 206 . The limit pressure adjustment valve 204 has a falling characteristic curve, so that the maximum control pressure is present in the de-energized state, i.e. the maximum possible limit pressure prevails.

The limit pressure adjustment valve 204 is electrically controlled directly or indirectly by the control unit 20 . As a result, the maximum permissible torque or the permissible angular acceleration ∝ _perm determined via the physical simulation model and the maximum permissible pressure difference Δp _perm derived therefrom are used in a corresponding control of the differential pressure present at the pressure compensator 206 or limit pressure implemented. The adjustment of the limit pressure in the limit pressure line G by the valve 204 thus decides at what pressure difference in the control lines R and L the pressure relief valves 220, 222 open and oil flows from the high-pressure side to the low-pressure side.

The pressure compensator 206 has a specific transmission ratio i, which can be i=12.7, for example. For example, a pressure signal at the control pressure level of 0-30 bar corresponds to a pressure protection at the operating pressure level of 0-380 bar.

A second safety valve 208, a pressure-limiting valve 212 used to limit the maximum pressure of the limit pressure, and a second hydraulic accumulator 202 are inserted into the limit-pressure line G. If a maximum value for the pressure control is exceeded, the pressure relief valve 212 switches and relieves the pressure limit line G against the tank T. A pressure measuring device 210 is provided to measure the current value of the pressure control, which measures the limit pressure prevailing in the pressure limit line G and can be designed as an analog pressure sensor .

The second safety valve 208 is a digital, ie binary, directional seated valve (only two switching positions). In the in the figure 3 shown embodiment, this is electrically controlled

Brake circuit 100 (or brake block) includes an electrically controlled, digital brake valve 104, an electrically controlled, digital safety valve 108 and a hydraulically controlled, digital changeover valve 106. Brake circuit 100 or brake block also includes a first hydraulic accumulator 102, which has a check valve 112 is acted upon or charged with control pressure from the control line ST.

The outlet of the brake valve 104 embodied as a 3/2-way valve in the present exemplary embodiment is connected to a pressure chamber of the holding brake 14 .

By applying pressure (opening pressure), the holding brake 14 is released against the force applied by a compression spring, so that the shaft 13 can rotate freely. If the hydraulic pressure in the pressure chamber falls below a certain value (minimum brake opening pressure), the holding brake 14 engages and exerts a braking torque on the shaft 13 or the motor 12 . The position of the brake valve 104 thus defines whether the holding brake 14 of the slewing gear 10 remains open (first position of the brake valve 104, takes place with corresponding electrical control) or application of the holding brake 14 should be initiated (second position of the brake valve 104, no electrical control or .current = 0).

The position of switchover valve 106 defines whether the outlet line of brake valve 104 is connected to the tank or tank line T or to accumulator pressure from first hydraulic accumulator 102 . Pressurized (first position of the brake valve 104) there is a connection to the first hydraulic accumulator 102 (and thus control pressure), pressure relieved (second position of the brake valve in which figure 3 shown) there is a connection to tank T.

The first safety valve 108 is a digital, ie binary, directional seated valve (only two switching positions). In the in the figure 3 shown embodiment, it is electrically controlled and designed as a 3/2-way valve.

The position of the first safety valve 108 defines whether the hydraulic control of the changeover valve 106 is subjected to the current operating pressure ("high pressure") of the slewing gear 10 (according to the figure 3 switching position shown: the control port of the changeover valve 106 is connected to the high-pressure line H of the limiting circuit 200) or the control port is tank-relieved.

The first and second safety valves 108, 208 can be controlled via a common electrical signal. Alternatively, the previously mentioned hydraulic control can take place via a hydraulic signal "slewing gear on". The safety valves 108, 208 are preferably switched as soon as the "Slewing gear on" signal assumes a specific value, for example a value greater than 5 bar.

Safety valves 108, 208 define whether the operational activation of holding brake 14 and differential pressure valve 206 is effective (with electrical activation: current = 1; with hydraulic activation: e.g. pressure signal > 5 bar), or whether the activation via the pressures in the first and second hydraulic accumulators 102 and 202 (with electrical control: current = 0; with hydraulic control: e.g. pressure signal <5 bar).

It should be noted at this point that in relation to the electrical actuation of the valves, in simplified terms, if there is an effective actuation of "current = 1" (i.e. the electrical signal is sufficient to switch the valve) and if there is no (or for a switching of the valve not sufficient) control of "current = 0" is spoken. A drive current greater than zero, but which is not sufficient for switching, is also referred to as "current=0".

In the de-energized state (diesel engine of crane 1 off, all valves not actuated), the system is depressurized. Any thermal expansion of the enclosed oil volume that may occur is reduced by leakage from the valves involved. The holding brake 14 of the slewing gear 10 is closed. The pressure switch-on stages of the slewing gear motor 12 is at a low pressure stage. If the holding brake 14 is overcome by external forces, the hydraulic motor 12 pumps oil against the resistance of the secondary pressure limitation (valves 220, 222) in accordance with the direction of rotation of the drive. Due to the pressure relief of the pilot control of the pressure-limiting valves 220, 222, the operating pressures that occur here are not sufficient to change anything in the switching state of the system.

When the diesel engine of the crane 1 is switched on, control pressure is applied to the system (ie a control pressure >zero prevails in the control pressure line ST). The first hydraulic accumulator 102 on the brake block is charged with control pressure from the line ST via the check valve 112 . The control pressure is at the brake valve 104 and at the limit pressure adjustment valve 204. Because of its inverse characteristic, the limit pressure adjustment valve 204 applies control pressure to the second safety valve 208 .

The "high pressure" signal between the throttles 228, 229, 230 and 232 rises to the level of the feed (open hydraulic system: usually <5 bar; closed hydraulic system: usually around 30-40 bar). In order to keep the holding brake 14 closed, the switching threshold of the switchover valve 106 must be above the pressure level of the feed so that it is not switched. In a preferred exemplary embodiment, this switching threshold has a value of 5 bar in order to be able to be switched on by the signal “slewing gear on”. For this reason, said exemplary embodiment can only be used for slewing gears 10 operated in an open circuit.

When the entry lever is closed, the limit pressure adjustment valve 204 is adjusted to the value specified by the software or the control unit 20 for the maximum permissible drive and braking torque. Due to the design, the limit pressure adjustment valve 204 delivers a minimum value for the pressure difference signal that cannot be undershot when there is full current, i.e. for the limit pressure in line G. Due to the transmission ratio in the pressure compensator 206, there is a minimum pressure protection of the slewing gear operating pressure of, for example, approx. 80 bar.

When the master switch is actuated ("slewing gear operation" status), the slewing gear 10 behaves as described in the basic function as long as the operating pressure is below the currently permissible maximum pressure according to the limit pressure adjustment valve 204 . The slewing gear drive 12 should not actively reach the pressure level specified by the limit pressure setting valve 204 by suitably controlling the slewing gear dynamics. This prevents unnecessary heat energy from accumulating.

The first and second safety valves 108, 208 are automatically actuated when the crane operator activates the "rotate slewing gear" command. The first safety valve 108 switches to the position in which the control port of the switching valve 106 is connected to the tank line T. The second safety valve 208 switches into the position in which the limit pressure setting valve 204 is connected to the pressure compensator 206, so that a limit pressure generated from the control pressure in accordance with the electrical actuation of the limit pressure setting valve 204 prevails in the limit pressure line G. Thus, the limit pressure is not specified by the second hydraulic accumulator 202, but via the control pressure and the limit pressure adjustment valve 204. The second hydraulic accumulator 202 is charged to the current limit pressure and the secondary pressure limitations of the valves 220 and 222 are thus pilot-controlled.

If the currently valid maximum differential pressure or limit pressure is exceeded (e.g. due to external forces due to side wind, inclined position or collision with obstacles), the differential pressure valve 206 opens so that oil flows from the pilot chambers of the secondary pressure relief valves 220, 222 into the tank T. The pilot control of the pressure relief valves 220, 222 drops slightly as a result. The operating pressure "right" or "left" (depending on the actuation of the slewing gear 10) opens the associated valve 220, 222 and oil flows from the high to the low pressure side of the slewing gear drive 12. A further increase in the differential pressure, i.e. the pressure difference in the control lines R and L, is prevented.

If the emergency stop is activated while the slewing gear is moving, all electrical controls are switched off and the diesel engine is stopped. The brake valve 104, the limit pressure adjustment valve 204 and the first and second safety valves 108, 208 drop out together, i.e. the operation of the safety valves 108, 208 is suspended.

The rotational energy of the superstructure 3 with the boom 4 and load, as well as any external forces, drive the motor 12 . Depending on the direction of rotation, an operating pressure builds up in the control lines R, L, which counteracts the rotation. Coming from the check valves 224, 226, this operating pressure actuates the changeover valve 106, since the first safety valve 108 is in the open position in the de-energized position (cf. figure 3 ) is located. Through the second hydraulic accumulator 202 the final pilot pressure on the valves 220, 222 is maintained. The control pressure stored in the first hydraulic accumulator 102 keeps the holding brake 14 open via the valves 104 and 106 . The superstructure 3 is braked with the permissible torque.

The first hydraulic accumulator or brake accumulator 102 is gradually emptied via the throttle 110 and the opening pressure in the holding brake 14 is thus reduced. If the minimum brake opening pressure is not reached, holding brake 14 closes. If, before the first hydraulic accumulator 102 is emptied, the "high pressure" signal in line H falls below the actuating pressure of switchover valve 106, the latter drops and connects holding brake 14 to tank line T, which Holding brake 14 can come up.

If the entry lever is opened during the movement of the slewing gear, the activation of the energy source and thus the delivery of oil into the control lines R, L are first retracted in an integrated manner. The actuation of the safety valves 108, 208 is canceled by appropriate electrical control. Thereafter, the brake valve 104 is de-energized so that it assumes the second position (cf. figure 3 ).

The last value of the differential pressure control or the limit pressure in the line G is initially retained due to the second hydraulic accumulator 202 and gradually decreases via leakage at the differential pressure valve 206 . As long as the operating pressure is above the switching threshold of the changeover valve 106, the holding brake 14 remains open. With the exception of a diesel engine stop, the processes described above with regard to the "emergency stop actuated" state take place.

Reference list:

1

crane

2

undercarriage

3

superstructure

4

boom

4a

main boom

4b

seesaw needle

5

rear ballast

6

slewing bearing

7

Guy stand / A-frame

10

slewing gear

12

Motor / slewing gear drive

13

Wave

14

holding brake

16

load cell

17

tilt sensor

18

angle sensor

19

anemometer

20

control unit

30

pressure sensor

32

pressure sensor

100

brake circuit

102

First hydraulic accumulator

104

brake valve

106

switching valve

108

First safety valve

110

throttle unit

112

check valve

200

perimeter circle

201

limit pressure circuit

202

Second hydraulic accumulator

204

limit pressure adjustment valve

206

Differential pressure valve (pressure compensator)

208

Second safety valve

210

pressure gauge

212

pressure relief valve

214

check valve

216

check valve

218

throttle

220

pressure relief valve

222

pressure relief valve

224

check valve

226

check valve

227

throttle

228

throttle

229

throttle

230

throttle

232

throttle

G

limit pressure line

H

high pressure line

L

Control line for "rotate slewing gear to the left"

N

low pressure line

R

Control line for "rotate slewing gear to the right"

ST

control pressure line

T

tank / tank line

Claims (15)

1. An apparatus for controlling a crane slewing gear (10) comprising

   - at least one hydraulic motor (12 by means of which the slewing gear (10) is rotationally drivable or brakable;

   - at least one holding brake (14) by means of which the slewing gear (10) can be held stationary;

   - a hydraulic brake circuit (100) by means of which the holding brake (14) is hydraulically controllable;

   - a load sensing device (16) by means of which a load instantaneously taken up by the crane (1) can be sensed;

   - an orientation sensing device (17, 18) by means of which an instantaneous orientation of the crane (1) and/or of at least one crane component can be sensed;

   - a hydraulic limitation circuit (200) by means of which a hydraulic pressure applied to the motor (12) can be limited to a specific limit value; and

   - a control unit (20) that is connected to the limitation circuit (200) and that is configured to determine a maximum permitted torque and/or a parameter derived therefrom for a current rotational movement of the slewing gear (10) in dependence on at least the sensed load, the crane configuration, and the sensed orientation and to automatically limit an angular acceleration and/or angular speed of the slewing gear (10) on this basis by a corresponding control or regulation of the limiting circuit (200),

   wherein the limitation and brake circuits (100, 200) are connected to one another and are configured to automatically brake the slewing gear (10) while maintaining the slewing gear limitation on a failure of the control unit (20) or on a triggering of an emergency stop.
2. An apparatus in accordance with claim 1, characterized in that the control unit (20) is configured to take account of current geometry data of the crane (1) for the determination of the maximum permitted torque and/or the parameter derived therefrom, with the geometry data preferably relating to an equipment state, a dimension, a mass, the position of a center of gravity and/or a moment of inertia of the crane (1) and/or of at least one crane component.
3. An apparatus in accordance with claim 1 or claim 2, characterized in that the control unit (20) is configured to take account of current environmental data for the determination of the maximum permitted torque and/or of the parameter derived therefrom, with the environmental data preferably relating to a wind direction and/or strength sensed via at least one wind measurement device (19).
4. An apparatus in accordance with one of the preceding claims, characterized in that the load instantaneously taken up by the crane (1) and the instantaneous orientation of the crane (1) can be sensed in real time and can be provided to the control unit (20), with the control unit (20) being configured to adapt the maximum permitted torque and/or the parameter derived therefor for the current rotational movement of the slewing gear (10) and the corresponding control or regulation of the limitation circuit (200) in real time.
5. An apparatus in accordance with one of the preceding claims, characterized in that the instantaneous orientation of the crane (1) relates to an instantaneous boom angle, an instantaneous tilt of the crane (1), and/or an instantaneous slewing gear angle.
6. An apparatus in accordance with one of the preceding claims, characterized by a simulation means that is preferably provided in the control unit (20) and that is configured to calculate the maximum permitted torque and/or the parameter derived therefrom for the current rotational movement of the slewing gear (10) using a physical simulation model of the crane (1) or of at least one crane component while taking account of an instantaneous equipment state, an instantaneous orientation, and an instantaneously raised load of the crane (1).
7. An apparatus in accordance with one of the preceding claims, characterized in that the control unit (20) is configured to calculate a maximum permitted hydraulic differential pressure and to automatically limit an angular acceleration and/or an angular speed of the slewing gear (10) on its basis by a corresponding control or regulation of the limitation circuit (200), in particular by an electric control of a limit pressure setting valve (204).
8. An apparatus in accordance with one of the preceding claims, characterized in that the brake circuit (100) comprises a first hydraulic store (102) and a brake valve (104), with the holding brake (14) being connectable via the brake valve (104) to a control pressure line (ST) in a first position and to a tank (T) or to the first hydraulic store (102) in a second position, and with the brake valve (104) preferably being electrically controllable; and in that the brake circuit (100) preferably comprises a switchover valve (106) via which the brake valve (104) is connectable to the tank (T) or to the first hydraulic store (102) in the second position, with the switchover valve (106) preferably being hydraulically controllable via a control connector.
9. An apparatus in accordance with claim 8, characterized in that the control connector of the switchover valve (106) is connectable via a first safety valve (108) of the brake circuit (100) to the tank (T) or to a high pressure line (H) of the limitation circuit (200), with the first safety valve (108) preferably being electrically switchable together with a second safety valve (208) of the limitation circuit (200).
10. An apparatus in accordance with one of the claims 8 or 9, characterized in that the brake circuit (100) is configured to automatically switch the brake valve (104) into the second position and to connect it to the first hydraulic store (102) and preferably to connect the first hydraulic store (102) to the tank (T) via a restrictor unit (110) on a failure of the control unit (20) and/or on a triggering of an emergency stop of the slewing gear (10).
11. An apparatus in accordance with one of the preceding claims, characterized in that the limitation circuit (200) comprises two hydraulic control lines (R, L) respectively effecting a left hand or right hand rotation of the slewing gear (10) and a hydraulic pressure limitation apparatus that is configured to conductively connect the control lines (R, L) to one another when the pressure difference in the control lines (R, L) exceeds a limit pressure depending on the determined maximum permitted torque; in that the pressure limitation apparatus preferably comprises at least one hydraulic pressure limitation valve (220, 222) via which the control lines (R, L) are connectable to one another and that is hydraulically controllable via a pre-control line, with the pre-control pressure present in the pre-control line being able to be set via a hydraulic limit pressure circuit (201) in dependence on the determined maximum permitted torque; in that the limit pressure circuit (201) particularly preferably comprises a differential pressure valve (206) that is configured to connect the pre-control line to a tank (T) on an exceeding of the limit pressure by the pressure difference in the control lines (R, L), with the differential pressure valve (206) preferably being hydraulically controllable via a limit pressure line (G); and in that the limit pressure circuit (201) very particularly preferably comprises a second hydraulic store (202) that is connected to the limit pressure line (G) and that is connectable to a control pressure line (ST) via a second safety valve (208) of the limit pressure circuit (201), with the second safety valve (208) preferably being electrically switchable together with a first safety valve (108) of the brake circuit (100).
12. An apparatus in accordance with claim 11, characterized in that the limit pressure circuit (201) comprises a limit pressure setting valve (204) that is controllable by the control unit (201) and by means of which the limit pressure line (G) is connectable to a control pressure line (ST) and the limit pressure can be set in dependence on the determined maximum permitted torque; in that the limitation circuit (200) is preferably configured to automatically disconnect the second hydraulic store (202) from the control line (ST) on a failure of the control unit (20) and/or on a triggering of an emergency stop of the slewing gear (10) so that the pressure of the second hydraulic store (202) is present in the limit pressure line (G); and in that an emergency stop function is particularly preferably provided that is automatically triggerable by the control unit (20) by the crane operator and/or on the presence of an emergency stop triggering state, with the power supply being automatically able to be switched off and/or with the slewing gear (10) being able to be automatically brakeble by means of the holding brake (14) while maintaining the slewing gear limitation as a consequence of the triggering of the emergency stop function.
13. An apparatus in accordance with one of the preceding claims, characterized in that the high pressure line (H) is connected to the control lines (R, L) via a valve arrangement such that the higher pressure of the control lines (R L) is always present in the high pressure line (H), with the valve arrangement preferably comprising two valves, in particular check valves (224, 226), via which the respective one of the control lines (R, L) is connected to the high pressure line (H).
14. A crane (1), in particular a crawler crane, having a slewing gear (10) and an apparatus for controlling the slewing gear (10) in accordance with one of the preceding claims.
15. A method of controlling a crane slewing gear (10) by means of an apparatus in accordance with one of the claims 1 to 13, the method comprising the steps:

    - sensing a load instantaneously taken up by the crane (1);

    - sensing an instantaneous orientation of the crane (1) and/or of a crane component;

    - determining a maximum permitted torque and/or a parameter derived therefrom for a current rotational movement of the slewing gear (10) in dependence on at least the sensed load and the sensed orientation;

    - controlling or regulating the motor (12) such that the angular acceleration and/or the angular speed of the slewing gear (10) is/are limited to a value dependent on the maximum permitted torque; and

    - on a failure of the control unit (20) or on the triggering of an emergency stop, automatically braking the slewing gear (10) so that the maximum permitted angular acceleration and/or angular speed of the slewing gear (10) is/are not exceeded.

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