HK1108679B - Lifting device and the operation method thereof - Google Patents

Description

Hoisting device and operation method thereof

Technical Field

The present invention relates to a lifting device for a container crane and a method for operating the lifting device.

Background

A typical lifting device comprises the following components: an electric motor, a motor shaft, a clutch, optionally in combination with a brake disc or brake drum, a brake, a transmission input shaft, a transmission output shaft, a clutch, a rope drum with a wire rope and a brake disc or brake drum in combination with a safety brake. This arrangement is effected by a unidirectional drive or a multidirectional drive or a combination of several drives.

According to the prior art, this type of lifting device is not sufficiently safe in case of overload. Especially when the load to be lifted gets stuck, a huge overload may occur. In said connection, if in a stuck situation, one or more electric motors with high rotational speed save a lot of rotational kinetic energy by their own momentum, even the load lifted by the drive performance may be temporarily overloaded.

The prior art systems cause a reduction in the drive performance of the motor by measuring the power and torsional stress. However, in this case, it takes some time from the recording of the actual situation until the performance actually degrades, i.e., a very large overload is generated.

In exceptional cases, special systems are employed to reach critical operating conditions that avoid overload. This is avoided by means of a hydraulic and/or pneumatic production system with deflection roller application in the wire rope. In addition, the measurement method can be implemented on an electronic basis (e.g., torque, rotational speed, etc.) in the case of different power transmission shafts and evaluated by a corresponding control arrangement.

These systems introduce critical load conditions for initiating the braking method and shutting down the motor.

On the one hand, it involves the major disadvantage of high costs, caused by the bulky hydraulic system or the necessary electronic control, and on the other hand, the non-decouplers of the motors and actuators or their light weights (flyweights), respectively, cause that during the braking descent step considerable load peaks will reach the maximum admissible value.

Disclosure of Invention

The object of the invention is to improve the lifting device described above in such a way that the safety of operation can be additionally increased. In addition, an operation method of the lifting device is established.

This object is achieved by the invention and is illustrated in the figures by way of a two-sided transmission.

A hoisting device according to the invention has a drive and an electric motor, the drive shaft of which is connected to the input side of the drive and the output side of which is connected to the rope drum, characterized in that a clutch device is arranged between the electric motor and the transmission, by means of which clutch device the connection between the electric motor and the rope reel can be completely or partially disconnected in the event of an overload, and the clutch device has a disengageable bolt which is connected to a disk, or a disk is located directly in front of or behind the disengageable bolt, the clutch device acting on an overload serves to completely or partially disconnect the connection and does not automatically re-establish this connection again, or the clutch device is used for completely or partially disconnecting the connection and for automatically reestablishing the connection or for automatically reestablishing the connection by means of a control signal.

Movement or rotation sensors are provided on the side of the motor and on the side of the rope drum, respectively, as seen from the side of the clutch device, and a controller is provided for comparison of the movements.

The controller has a proximity sensor for detecting axial movement of the disc by the break-away bolt.

The two parts of the clutch, which are identical to the clutches arranged opposite to each other, are provided with markings, and the movement sensor is provided with a scanning device for the markings.

The control unit is provided with a control device having at least one brake.

The clutch which reacts to an overload is a slipping friction clutch or a separating clutch.

The clutch acting on the overload is a clutch of the mechanical, hydraulic, electrical or electromagnetic type or a combination of these types and is arranged between the electric motor and the transmission.

The hoisting device is a container crane for hoisting a load.

The invention also relates to a method for operating a hoisting device, the movements of the bolt and the disc being measured and compared with each other, at least one brake being controlled for locking the rope drum and/or the actuator in the event that the difference between the movements is greater than a certain value.

The clutch which reacts to an overload is designed as a sliding friction clutch which reaches a stick-friction condition when the overload situation is eliminated.

The driving performance of the motor is reduced at the same time or after the effect of overloading and reducing the power of the clutch device.

The release of one or several brakes is initiated based on a speed measurement method and an evaluation of the difference in speed on the different power transmission shafts or on the devices connected to these shafts.

There are several ways of implementing the invention. Two embodiments of the present invention will be described in more detail below with reference to the accompanying drawings.

Drawings

Fig. 1 shows a first variant of a lifting device according to the invention for the conversion of the device;

fig. 2 shows a partial cross-sectional view of a second variant of the lifting device according to the invention in fig. 1, which is used for the changeover of the device.

Detailed Description

Fig. 1 and 2 show a lifting device equipped with two electric motors 1, 1 ', which are connected to a drive 6 via drive shafts 2, 2 ', clutches 3, 3 ' with additional brake discs 4, 4 ' or additional brake drums 4, 4 ', brakes 14, 14 ', and via drive input shafts 5, 5 ', respectively. The transmission 6 drives the rope drums 9, 9 ' via the transmission output shafts 7, 7 ' and the clutches 8, 8 '. The rope drum is provided with ropes 12, 12 ' with brake discs 10, 10 ' or brake drums and safety brakes 11, 11 '. According to the invention, the lifting device is equipped with a drive shaft 2, 2 ' with a clutch device 13, 13 ', which clutch device 13, 13 ' completely or partially disconnects the electric motor 1, 1 ' from the rope drum 9, 9 ' in the event of an overload exceeding the permissible load. This will prevent complete or partial damage to the drive due to overloading. In such a manner that the electric motors 1, 1 ' are separated from the rope reels 9, 9 ' by the clutch devices 13, 13 ', a part or all of the brakes 11, 11 ', 14 ' are activated as a result of the load to be lifted being maintained in a suspended position. Since the motor 1, 1 ' is decoupled from the transmission 6, the introduction of residual kinetic energy into the rope drum 9, 9 ' is also prevented after switching off the motor 1, 1 '. In an additional embodiment, which is not shown in the figures, the clutch device 13, 13 'can also be arranged in the transmission 6 or in front of the rope drum 9, 9'.

In addition, the lifting device is equipped with two controllers 15, 15 ' for operating the brakes 11, 11 ', 14 '. In order to identify the switching of the clutch device 13, 13', the following two variants are preferably used:

fig. 1 shows a first variant:

the controllers 15, 15 ' are connected on both sides of the movement sensors 16, 16 ' of the clutch devices 13, 13 ' provided as a plurality of clutches. The clutch devices 13, 13 ' show coupling disks 17, 17 ' which are arranged opposite one another and have teeth 18, 18 ' on their periphery. The movement sensors 16, 16 ' count the number of teeth 18, 18 ' of the passing coupling disks 17, 17 '. The controller 15, 15 ' compares the number of teeth 18, 18 ' passing over a defined period of time and makes a decision from the result of the movement of the coupling disc 17, 17 '. In case of an accidental difference between the movements of the coupling discs 17, 17 ', the controller controls some or all of the brakes 11, 11', 14 'so that they stop the rope reels 9, 9'. The movement sensors 16, 16' are preferably designed as proximity switches.

Fig. 2 shows a variant of the clutch device 13, which shows how the control device 15, 15 'is connected to a movement sensor 24, which is designed as a clutch, arranged on the motor-side half of the clutch device 13, 13'. The clutch device 13, 13' is shown with a bolt 23 arranged axially on the motor side, which in turn is connected with the disk 22 in a tight or loose manner. During the switching of the clutch device 13, 13 ', the movement sensor 24 detects the axial movement of the bolt 23 and the disk 22, 22' and transmits a signal to the control. Said control unit controls some or all of the brakes 11, 11 ', 14 ', in which case the rope reels 9, 9 ' stop. Preferably, the movement sensor 24 is provided as a proximity switch.

In addition, the controllers of both variants are connected to the speed sensors 19, 19 ', 20' of the motors 1, 1 'and to the rope reels 9, 9'. In this way, the brakes 11, 11 ', 14 ' are initially controlled by the controller 15, 15 ' before the lifting device in question is operated, so that the brakes 11, 11 ', 14 ' can be tested one by one, since the movement of the corresponding brake disc 4, 4 ', 10 ' will be prevented. Thereafter the motors 1, 1 ' will be started and the speed of the rope drums 9, 9 ' is measured, if necessary, as well as the speed of the motors 1, 1 '. For example, when the speed sensors 20, 20 'determine that the movement of the rope drums 9, 9' exceeds the normal speed, the safe operating braking performance of the hoisting device will be insufficient despite the locking of the brakes 11, 11 ', 14'. In this case the display 21, 21' is activated for the operator of the lifting device and prevents a new activation of the lifting device or only an emergency operation of the lifting device.

The arrangement of the system arrangement according to the invention is advantageous in that the movement sensors are arranged in such a way that they detect the activation of the clutch device 13 and transmit a signal to the controller 15.

The embodiment according to the invention has the great advantage that the separation does not take place automatically again in this case. In this way, it is not possible for the operator of the device in question to operate the protected device again without visual inspection and verification.

The invention provides for the clutch to be designed as a sliding friction clutch, which in this arrangement ideally meets the requirement of eliminating the connection between the electric motor and the cable drum, since it transmits a portion of the energy during the sliding friction operation. According to the invention, the overload situation can be eliminated again by the operation of the downstream load-side brake, the slipping friction clutch can again reach the stick-friction condition, and the hoisting device can be immediately continued to be operated.

Since the motor and the rope drum are completely separate, any overload can be completely excluded.

The great advantage of the embodiment method according to the invention is that the operating brakes 14, 14 'and the safety brakes 11, 11' belonging to the prior art are subjected to load-side power in this case, said safety brakes being released from the clutch device 13. In this connection, the driving performance of the electric motor is reduced, according to the invention, simultaneously with or after the effect of overloading and reducing the power of the clutch device. The implementation has the great advantage that in the event of an overload, the performance of the motor can also be reduced due to the excess.

The advantage of the mechanical separation between the motor and the rope reel in the clutch device 13 is that it can work by itself without any third party energy source. In contrast, the hydraulic solution makes it possible to achieve a high performance density with a small unit volume and size, with the result that the flywheel effect of the clutch device 13 can be controlled to a low level. The electronic processing and electrification implementation of the clutch device 13 with the start operation is advantageous because it receives the disengagement signal in a direct manner.

The integration of the monitoring system for detecting an overload situation in the clutch device 13 is particularly advantageous for retrofitting existing lifting devices. The implementation method can be independently operated on the existing hoisting device without any additional system modification treatment.

In many hoisting devices, a control system according to the prior art is incorporated for monitoring the abnormal speed of the individual input and output drives (all devices from the motor 1, 1 ' up to the brake disc 10, 10 ') in order to ensure that the safety brake 11, 11 ' can be activated in the event of a failure of one of the devices. These faults can be, for example, a break of the drive shaft 2, 2 ', 5 ', 7 ' or the transmission 6 of the clutch 3, 3 ', 8 '. In the present invention, the advantage of the clutch device 13 is utilized in such a way that in the case of disengagement the relation between the speed of the electric motor 1, 1 'and the drive shaft 2, 2' and the speed of all devices after the clutch device 13 changes. This change is automatically detected by the control system for monitoring abnormal speed and can therefore be used to introduce the braking method according to claim 10.

The reduction of the driving performance of the motor during an overload occurrence is of great benefit, since it provides a simple and economical arrangement with the integrity of the usual braking system 4, 14, 4 ', 14' between the motor and the rope drum. In the prior art, these devices can also be connected directly to the integrated clutch.

Claims (12)

1. Hoisting device with a transmission (6) and an electric motor (1), the drive shaft (2) of which is connected to the input side (5) of the transmission and the output side (7) of which is connected to the rope drum (9), characterized in that a clutch device (13) is provided between the electric motor (1) and the transmission (6), by means of which clutch device the connection between the electric motor (1) and the rope drum (9) can be completely or partially disconnected in the event of an overload, and that the clutch device (13) has disengageable bolts (23, 23 '), which disengageable bolts (23, 23 ') are connected to a disk (22), or a disk (22) is located directly in front of or behind the disengageable bolts (23, 23 '), the clutch device acting on the overload serving to completely or partially disconnect the connection and not automatically reestablish it again, or the clutch device is used for completely or partially disconnecting the connection and for automatically reestablishing the connection or for automatically reestablishing the connection by means of a control signal.

2. Hoisting device as claimed in claim 1, characterized in that movement or rotation sensors (16) are provided on the side of the motor (1) and on the side of the rope drum (9), respectively, as seen from the side of the clutch means (13), and a control (15) is provided for comparison of the movements.

3. Lifting device as claimed in claim 2, characterized in that the control unit (15) has a proximity sensor (24) for detecting the axial displacement of the discs (22, 22 ') carried by the disengageable bolts (23, 23').

4. Lifting device as claimed in claim 2, characterized in that the clutch halves (17) which are arranged opposite one another with respect to the clutch means (13) are provided with markings and in that the movement sensor (16) is provided with a scanning device for said markings.

5. Hoisting device as claimed in claim 2, characterized in that the control unit (15) is provided with a control device having at least one brake (11, 14).

6. Lifting device according to claim 1, characterized in that the clutch device (13) acting on an overload is a sliding friction clutch or a disconnect clutch.

7. Lifting device according to claim 1, characterised in that the clutch means (13) acting on an overload is a clutch of the mechanical, hydraulic, electrical or electromagnetic type or a combination of these types and is arranged between the electric motor (1) and the transmission (6).

8. The hoisting device of claim 1, wherein the hoisting device is a container crane for hoisting a load.

9. Method for operating a hoisting device according to any one of claims 1-8, characterized in that the movements of the disengageable bolt (23, 23 ') and the disc (22, 22') are measured and compared with each other, and that in case the difference between the movements is larger than a certain value, at least one brake is controlled for locking the rope reel and/or the actuator.

10. Method according to claim 9, characterized in that the clutch device (13) which reacts to an overload is designed as a slipping friction clutch which reaches a sticking friction condition when the overload situation is eliminated.

11. A method according to claim 9 or 10, characterized in that the driving performance of the electric motor is reduced at the same time as or after the effect of overloading and reducing the power of the clutch device.

12. Method according to claim 9 or 10, characterized in that the release of one or several brakes is initiated on the basis of a speed measurement method and an evaluation of the difference in speed on the different power transmission shafts or on the devices connected to these shafts.