EP0691301B1 - Slewing gear for a crane - Google Patents

Abstract

The rotating parts of the crane are driven by gearing from an electric motor controlled by an actuator in response to measurements of its rotational speed and torque. When the load suspended from the jib is swinging forwards during run-up of the motor and rotation of the jib, the driving torque is reduced as the speed increases. When the load is swinging backwards the torque is maintained at a substantially constant value. <IMAGE>

Description

The invention relates to a method for controlling the drive of a slewing gear for a crane, preferably a tower crane rotating below or above.

Known rotating mechanisms have a between the electric motor and the gear Fluid coupling, one holding and braking the drive pinion The brake is only opened when the motor has such a fluid coupling has built up great torque, for example, on the crane boom acting wind loads prevents the boom from turning back. With this Known slewing gear is basically started with a high Torque, which is a relative according to the resulting acceleration stimulates wide swinging of the load. The control takes place in the known slewing gear of the motor drive via the motor torque, so that the motor has a braking counter torque generated when the load swings to the boom exerts a pulling moment. Such a motor control can but the unwanted swaying of the load cannot be suppressed, so that a sensitive control of the rotational speed during the turning operation and Deceleration phase is not possible.

FR 25 20 133 is a drive control for a horizontal movement mechanism known in the case of elastic disturbances during the drive occur. For this purpose, a control loop with four feedback couplings is provided, namely a loop for regulating the drive torque, a loop for regulating the absolute speed of the moving part, a loop for the differential speed between the speed of the moving part and the Speed of the drive and a loop for the speed of the drive. The four loops in their interaction enable a bumpless and vibration-free drive. The directional shift is a special area of application of the boom of an overhead rotating tower crane.

DE 42 21 915 A1 describes a tower crane rotating below with a base frame known, which consists of several tower sections. The boom is horizontal Swivel axis is pivotally mounted and is attached to a climbing basket, which is firmly connected to the revolving platform for the assembly of the tower. By The tower is passed through the climbing cage as a whole or in individual tower sections inserted from above and connected to the revolving stage. Subsequently the climbing cage including the extension arm is raised to the tower head and locked there.

The object of the invention is a method for controlling the drive of a slewing gear of the type specified at the beginning to create a sensitive and precise Control of the rotation of the boom allows.

According to the invention, this object is achieved by a method for regulating the drive of the slewing gear solved according to claims 1 and 2.

The drive motor is directly without the gear driving the pinion Interposition of a fluid coupling connected so that the drive pinion by appropriate control of the drive motor in the sensitive Controls way that the desired drive characteristic is achieved.

By measuring the engine speed and engine torque, the for the Control the drive pinion. The slewing gear is provided with such a drive control that the unavoidable commuting the load is dampened. This is during start-up and turning operation achieves that with a swinging, ie pulling load by lowering the engine torque consciously accepting an increasing engine speed that by appropriate Tracking the suspension point of the rope on the boom oscillating movement dampens. When the load swings back then increases the motor torque to maintain the set speed gently from below again, so that the target speed essentially is maintained without the pendulum the movement is strengthened again. In the inventive So the slewing gear is maintained while maintaining the target speed the engine torque regulated so that this in the sense of damping the pendulum movement works.

During the braking phase, the engine torque is again in the sense a damping and suppression of the pendulum movement regulated. This is done in that especially during the braking phase occurring pre-oscillation of the load the specified speed drop is maintained so that the engine torque is braking works. When the load swings back, however, the engine torque so lowered that the braking moment of the backward swinging Load is exploited.

As with the slewing gear the engine torque both during the start-up and braking phase as well as during turning operation in an optimal way from the swinging load to the Boom transmitted power is adjusted, can be optimal Achieve damping of the pendulum movement.

By the speed control of the drive motor according to the invention can be approached gently against any wind loads, without large torque preventing a smooth start must be built.

Due to the control of the drive motor according to the invention infinitely different speeds Set smooth acceleration and deceleration of the rotary motion.

The invention can also be defined in such a way that a rotational speed the target value is that the current Rotational speed is determined that when the Setpoint with a constant or increasing setpoint over time and / or if the value falls below the target value if the time falls Setpoint the engine torque is reduced to zero and that otherwise the current speed of rotation is regulated to the setpoint becomes.

The electric motor on the slewing gear is slip-free coupled with the rotational movement of the boom, with a detector provided to determine the speed of rotation of the boom and the control unit for controlling according to the above specified method is formed. According to the invention then when the load is swinging in the sense of a desired boom movement acts, an acting torque of the rotary drive taken away. This is a control loop for regulation the speed of rotation of the boom or the acting torque opened on the boom. This ensures that the energy of the swinging load to the positive or negative Boom acceleration used and thereby reduced becomes. As a result, a pendulum movement of the load is damped becomes.

By determining and regulating the speed of rotation of the The crane operator drives the crane with pinpoint accuracy, especially when wind loads occur. This is achieved through a slip-free coupling of the rotary motor supported on the rotating movement of the boom.

According to an advantageous embodiment, the acting Torque only if the current speed of rotation deviates from the target value, the amounts of which are less than a maximum value are reduced to zero and otherwise counteract the deviations. This ensures that the current Speed of rotation from a predetermined setpoint or certain setpoint curve does not deviate too much.

A further preferred embodiment is characterized by this that the acting torque is only changed continuously. This can be achieved, for example, by using an electric motor an asynchronous motor in connection with a phase control is used. By just changing the Torque ensures that a smooth movement is reached and the loads on the crane are kept low. Alternatively, an asynchronous motor with an electrical one Frequency control can be provided.

According to a further preferred embodiment, a harmonic Rotary movement of the boom is achieved in that inconsistent setpoint targets, a constant setpoint curve is determined. This means that when a new setpoint is entered this is compared with the previous setpoint and Adjustment is run through an adjusted setpoint curve. Here becomes a particularly easy movement reached when the determined setpoint curve, i.e. the setpoint curve, represents a continuously differentiable function.

According to a further preferred embodiment, that the acting torque when falling below the setpoint by the current speed of rotation with a falling setpoint curve is only reduced to zero if the current speed of rotation is greater than the target value target. By this measure ensures that when the boom brakes this is not too strong, i.e. below the desired target value target, is decelerated in its rotational speed.

In the slewing gear it is also provided that the greatest driving torque of the motor is limited, so that the Construction of the crane can not be overloaded.

If the rotation needs to be braked quickly, this is done this through a special program after the commuting leading Load is constantly braked by a counter torque. The slewing gear according to the invention enables rapid braking thus also a normal counter attack, whereby a counter electronic control is provided.

The motor can be a conventional slip ring asynchronous motor act with the desired Switch on the motor characteristics at different resistance levels or an asynchronous motor with a special rotor.

The regulation of the speed and the engine torque can be done in the usual way Way through a phase control based on the set Voltage time area if an asynchronous motor is used as the drive motor is selected, or by a conventional frequency control respectively.

According to the present invention, the drive starts speed-controlled, while braking is torque-controlled by reversing the rotating field (so-called "counter") is made.

Braking is automatically braked whenever the Control lever is reset to zero. This automatic Braking is initiated particularly gently, since the start of the braking process current speed actual value as speed setpoint which is then taken to zero after a curve ramp is returned. The difference between this setpoint and The current speed of rotation is the target value for the acting Braking torque. Since when initiating the braking process Speed setpoint equal to that of the current speed of rotation the braking torque always starts from zero and completely bumpless.

In addition to the automatic braking process through automatic, The crane operator can counteract torque-controlled countermeasures Increase torque by opposing a setpoint the current direction of rotation. The crane operator remains in this counter position finds a torque-controlled after the braking process Reversal of the direction of rotation instead. The acting torque is continuously adjustable from zero to maximum using the control lever, so that it is possible to swing the boom in the wind To keep "floating", which is a particularly sensitive positioning enables.

The acting torque is both regulated in the speed Operation as well as in torque-controlled operation to a maximum Limited amount. Here, in particular, the efficiency reversal between driving and braking considered that the maximum permissible, acting on the crane construction Torque is not exceeded.

The maximum torque can vary depending on the length of the boom, which can vary depending on the crane type become. Another option to switch to a maximum The amount of torque applied is for different boom positions intended.

A special procedure is used for speed-controlled starting for the fact that the one that occurs particularly with slewing cranes Whip effect due to jerking of the boom when Acceleration of the boom does not occur. If by the load and / or the wind conditions do not change the rotational speed can follow the constant course of the setpoint because of the torque limitation a maximum acceleration torque is not can be exceeded is provided at a maximum Deviation between setpoint and current speed of rotation the steady increase in the setpoint stopped until the Deviation is again within the intended limit. Hereby is achieved that the acting torque when rushing the boom (whip effect) is reduced and therefore no further acceleration energy in the construction is initiated.

Fig. 1

ein die Aktivierung der verschiedenen Regler betreffendes Flußdiagramm,

Fig. 2

ein die Drehzahl- und Momentenregler betreffendes Flußdiagramm,

Fig. 3

ein den Bremsregler betreffendes Flußdiagramm und

Fig. 4

ein Flußdiagramm für die Verarbeitung der Reglersignale zur Steuerung des Motors.

Exemplary embodiments of the control of the slewing gear are explained in more detail below with reference to the drawing. In this shows:

Fig. 1

a flow chart relating to the activation of the various controllers,

Fig. 2

a flow chart relating to the speed and torque controllers,

Fig. 3

a flowchart relating to the brake controller and

Fig. 4

a flowchart for the processing of the controller signals for controlling the engine.

1, in a first step checked whether the rotational speed setpoint set with the control lever is zero. If this is the case, the brake controller activated to initiate braking. It is slowed down by Counter automatically whenever the control lever is at zero is deferred.

If the set speed setpoint is different from zero, in a second step it is checked whether the setpoint direction is the same as the direction of rotation. If this is not the case, then the brake controller is activated. If the setpoint direction was changed, d. that is, a setpoint was set against the current direction of rotation given in order to achieve a faster braking, so in addition, the torque controller is activated and the speed controller deactivated.

Has the setpoint direction not changed, i. that is the direction of rotation due to other influences against the Set direction of rotation, so in a third step the speed controller is activated and the torque controller is deactivated.

If the setpoint direction is the same as the direction of rotation, the system checks whether whether the setpoint since the last change in the direction of rotation was zero. If not, for example what the Torque-controlled reversal of direction after rapid braking by countering and maintaining the counter creation, the torque controller is activated and the speed controller is deactivated.

If the setpoint is zero when the direction of rotation was last changed was, the slewing gear according to the invention is in the start-up and Rotary operation and the speed controller is activated accordingly and the torque controller is deactivated.

The flow chart shown in FIG. 2 shows the further processing of the set rotational speed setpoint. In the setpoint processing, the setpoint is compared with the actual value and a constant setpoint curve to the setpoint target is created. The prepared setpoint is measured together with the measured Speed value processed in the speed controller if this is active.

If the target direction of rotation is the same as the actual direction of rotation, then the setpoint is reduced depending on the speed. The reduced setpoint or the setpoint is set with the torque characteristic processed further.

3 shows the flow diagram for the brake control system. As long as the brake controller is inactive, the current speed saved as brake controller setpoint. As soon as the brake controller becomes active, a setpoint curve is in the form a ramp from the last stored speed value to 0 is generated. This setpoint course is with the measured speed processed in the brake controller.

Fig. 4 shows a flow chart for the processing of the controller signals to control the engine. The totalizer checks the activity the controller and determines the with the measured speed Current limitation. Boom position, current limitation and the measured Current are processed in the current controller so that the power section ensures the operation of the engine according to the invention, which provides the torque required to turn the crane.

Claims (7)

1. Process for the control of the drive system of slewing gear for a crane, preferably a turret slewing crane slewing at top or bottom, with an electric motor driving, via a transmission system, the combing pinion operating with a slewing ring on the crane masses to be turned,

   a control unit governing the control movements applied to an actuation device, according to the type of motor, and

   means for measuring the motor revolutions and motor torque,

   characterised in that

   during start-up and slewing operation, when motor revolutions are increased as the load swings forwards, the driving torque is reduced towards zero, and

   in that as the load swings back the driving torque is essentially held at the same level.
2. Process for the control of the drive system of slewing gear for a crane, preferably a turret slewing crane slewing at top or bottom, with an electric motor driving, via a transmission system, the combing pinion operating with a slewing ring on the crane masses to be turned,

   a control unit governing the control movements applied to an actuation device, according to the type of motor, and

   means for measuring the motor revolutions and motor torque,

   characterised in that

   during the braking phase, the specified revolution reduction in a forward-swinging load situation is essentially held at the same level by means of braking torque applied to the motor, and

   in that as the load swings back the motor torque is reduced, so as to make full use of the braking moments of the back-swinging load.
3. Process according to claim 1 or 2, characterised in that on actuation of the actuation device initiating the slewing movement, the motor torque increases according to a pre-set time function corresponding to the specified target value for revolutions.
4. Process according to any of claims 1 and 3, characterised in that the maximum drive torque of the motor is restricted.
5. Process according to any of claims 1 to 4, characterised in that rapid braking of the slewing movement is carried out by means of a special program, whereby as the swinging load accelerates forwards, it is continuously braked by a counter-torque.
6. Process according to any of claims 1 to 5, characterised in that the motor used is a slip-ring asynchronous motor controlled by a generalised phase control system.
7. Process according to any of claims 1 to 5, characterised in that the motor is a motor controlled with a frequency regulation system.

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