JP7602355B2 - Load rotation device - Google Patents

Description

The present invention relates to a load rotation device for rotating a load such as a crane.

In loading and unloading operations using cranes, the load is rotated (horizontally rotated) until it is in the specified orientation, and then lowered to the desired location. Rotating a load is usually accomplished by an assistant standing nearby assisting the load (pulling or pushing the load). However, when the load is large or heavy, multiple assistants must work together while communicating with each other, which creates the problem of significantly reducing work efficiency. In addition, if a worker is assisting the load nearby, there is a risk of an accident, such as the worker falling over if hit by the rotating load.

In light of this situation, a device that mechanically rotates a suspended load without human power (load rotation device) has been developed and is used in cargo handling operations. A known load rotation device incorporates a gyro device (see reference number 10 in the figure), as shown in FIG. 1 of Patent Document 1. As shown in FIG. 2 of Patent Document 1, the gyro device includes a disk-shaped member called a "flywheel" (see reference number 10a in the figure) and a member called a "gimbal" that supports the flywheel (see reference number 11 in the figure). This type of load rotation device is interposed between the hook of the crane and the suspended load, and rotates the load by the gyro effect generated by tilting (tilting) the gimbal while rotating the flywheel at high speed.

However, in the above-mentioned load rotation device, while the gimbal continues to tilt in one direction, the gyro effect continues to be applied from the flywheel to the gimbal, and the rotation speed of the load continues to increase. Therefore, if the load is a light load, the rotation speed of the load may become too fast, which may cause danger. In this regard, load rotation devices that feedback control the rotation speed of the load have been proposed. For example, paragraphs 0022 to 0032 and FIG. 1 of Patent Document 2 describe that in a load attitude control device (load rotation device) that uses the gyro effect to rotate a load, the load angular velocity φ' _M (rotation speed of the load) is read by a gyro sensor 101, and the torque controller 206 controls the load angular velocity φ' M so that the deviation between the angular velocity command value φ' and the load angular velocity φ' _M becomes zero.

Japanese Patent Application Publication No. 63-074891 JP 2014-133600 A

However, in a load rotation device that uses feedback control of the load rotation speed, the correction process for the load rotation speed is delayed, so if a disturbance such as wind occurs, there is a risk that the load will continue to rotate at a rotation speed that exceeds the limit until the correction process catches up. Also, not only is it necessary to provide a sensor (such as a gyro sensor) that detects the load rotation speed, but it is also necessary to perform complex control, such as various calculations.

The present invention has been made to solve the above problems, and provides a load rotation device that can reliably limit the rotation speed of a suspended load even when disturbances such as wind occur. Another object of the present invention is to limit the rotation speed of a suspended load using a simple method that does not require a separate sensor to detect the rotation speed of the suspended load.

The above issues are:
A flywheel and
a flywheel rotating motor that drives the flywheel to rotate;
A gimbal that supports the flywheel;
a gimbal tilting motor that drives the gimbal to tilt;
A load rotation device that rotates a load by using a gyro effect that occurs when a gimbal is tilted while a flywheel is rotated,
This problem is solved by providing a load rotation device characterized in that it is equipped with a rotation speed limiting means which, when the tilt torque T of the gimbal tilting motor exceeds a limit value _Tr , holds the input current to the gimbal tilting motor at the value at that time, thereby stopping the tilting by the gimbal tilting motor, thereby limiting the rotation speed of the load (meaning the angular velocity of rotation of the load; the same applies below).

As already mentioned, in a load rotation device that utilizes the gyroscopic effect, while the gimbal continues to tilt in one direction, the rotation speed of the load continues to increase due to the gyroscopic effect exerted on the gimbal by the flywheel. Therefore, when the load starts to rotate, a gyroscopic effect is generated by the rotation of the load, and a torque is applied to the output shaft of the gimbal tilting motor in the opposite direction to the direction in which the output shaft is rotating (tilting). In the following, this reverse torque is referred to as "torque generated by load rotation" and may be expressed as "torque T'" using the symbol "T'". In addition, the torque that the gimbal tilting motor outputs to the output shaft to tilt the gimbal is referred to as "tilting torque" and may be expressed as "tilting torque T" using the symbol "T".

The torque T' generated by the rotation of the load increases as the rotation speed of the load increases. When viewed from the perspective of the tilt torque T of the gimbal tilt motor, torque T' becomes a resistance force (resistance torque). For this reason, as the rotation speed of the load increases, a large resistance torque (torque T') is applied to the output shaft of the gimbal tilt motor, and the tilt torque T of the gimbal tilt motor increases. Conversely, as the rotation speed of the load decreases, the resistance torque (torque T') applied to the gimbal tilt motor decreases, and a smaller tilt torque T of the gimbal tilt motor is sufficient. In this way, the rotation speed of the load is directly reflected in the tilt torque T of the gimbal tilt motor.

In this regard, the load rotation device of the present invention is configured to stop the tilting by the gimbal tilting motor when the tilting torque T of the gimbal tilting motor exceeds the limit value _Tr (when the rotation speed of the load is about to exceed the upper limit), thereby preventing the rotation speed of the load from increasing any further (limiting the rotation speed). By limiting the rotation speed of the load based on the tilting torque T, which directly reflects the rotation speed of the load, it is possible to quickly and reliably limit the rotation speed of the load when the rotation speed of the load is about to exceed the upper limit, even when there is a disturbance such as wind. In addition, it is possible to limit the rotation speed of the load in a simple manner without the need for complex calculations.

In the load rotation device of the present invention, the above series of operations (operations that limit the rotation speed of the load when the tilt torque T exceeds the limit value Tr) are executed by a rotation speed limiting means. An example of this rotation speed limiting means is a current-limiting torque limiter. An inverter device that controls the frequency of the AC current input to the gimbal tilting motor is usually interposed between the gimbal tilting motor (AC motor) and the power source, and the current-limiting torque limiter can be realized by control using this inverter device. Therefore, in the load rotation device of the present invention, there is no need to provide a separate sensor (such as a gyro sensor) for detecting the rotation speed of the load. This makes it possible to simplify the configuration of the load rotation device.

Preferably, a load slewing device is provided that is provided with a limit value adjusting means for adjusting the limit value T _r .

Preferably, a load rotation device is provided in which, when the tilt torque T of the gimbal tilting motor falls below a limit value _Tr , the limit on the rotation speed of the load by the rotation speed limiting means is released, the input current to the gimbal tilting motor increases, and tilting of the gimbal tilting motor resumes.

As described above, the present invention makes it possible to provide a load rotation device that can reliably limit the rotation speed of a suspended load even when disturbances such as wind occur. It also makes it possible to limit the rotation speed of a suspended load using a simple method that does not require a separate sensor to detect the rotation speed of the suspended load.

FIG. 1 is a perspective view showing a state in which a load of a crane is rotated using a load rotation device. FIG. 4 is a flow chart showing an example of a load rotation operation by the load rotation device. 13 is a graph showing the relationship between the power supply time to the gimbal tilting motor and the rotation speed of the load when the limit value T _r is changed in the load rotation device.

A preferred embodiment of the load slewing device will now be described in more detail with reference to the drawings. Figure 1 is a perspective view showing how a load 50 from a crane is slewing using the load slewing device 10. The enlarged circled portion of Figure 1 shows the internal structure of the load slewing device 10 in a see-through state.

As shown in Fig. 1, the load slewing device 10 rotates a load 50 suspended from a crane hook 60 or the like in the direction of arrow _A1 around a vertical axis _L1 . The load slewing device 10 is provided in a location where it can transmit a rotation force to the load 50 when it rotates around the vertical axis _L1 . In the example shown in Fig. 1, the load slewing device 10 is interposed between the load 50 and the crane hook 60, and is attached above the load 50, but even if it is attached below the load 50, the load 50 can be rotated.

The load rotation device 10 includes a flywheel 11, a flywheel rotation motor 12, a gimbal 13, a gimbal tilt motor 14, and a rotation speed limiting means 15 housed in a housing 16. The flywheel 11 is disk-shaped, and its center is supported by the gimbal 13 in a state in which it can rotate in the direction of the arrow _A2 about an axis _L2 . The flywheel rotation motor 12 drives the flywheel 11 to rotate about the axis _L2 . The gimbal 13 is frame-shaped surrounding the flywheel 11, and both ends are supported in a state in which it can tilt in the direction of the arrow _A3 about an axis _L3 . The axis _L3 , which is the tilt center of the gimbal 13, and the axis _L2 , which is the rotation center of the flywheel 11, are not parallel to each other (intersect) and are usually perpendicular to each other. The gimbal tilting motor 14 drives the gimbal 13 to tilt about the axis _L3 . The rotation speed limiting means 15 limits the rotation speed of the suspended load 50 (angular velocity of rotation of the suspended load 50).

In the load rotation device 10 of this embodiment, the flywheel rotation motor 12 and the gimbal tilt motor 14 are both electric motors. An inverter device (not shown) that controls the frequency of the AC current input to the gimbal tilt motor 14 is connected to the electric motor (AC motor) that constitutes the gimbal tilt motor 14, and this inverter device is equipped with a current-limiting torque limiter. This torque limiter functions as a rotation speed limiting means 15, as described later. In a non-operating state in which no current is input to either electric motor (the flywheel rotation motor 12 and the gimbal tilt motor 14), the flywheel 11 is in a state in which it can freely rotate around the axis _L2 , and the gimbal 13 is in a state in which it can freely tilt around the axis _L3 . In this non-operating state, the flywheel 11 and the gimbal 13 are balanced so that the flywheel 11 stands vertically (the axis _L2 , which is the center of rotation of the flywheel 11, lies horizontally).

When the flywheel rotation motor 12 is driven (current input to the flywheel rotation motor 12 is started) from the above non-operating state, the flywheel 11 starts to rotate about the axis _L2 (rotate in the direction of the arrow _A2 ). When the gimbal tilting motor 14 is driven (current input to the gimbal tilting motor 14 is started), the gimbal 13 starts to tilt about the axis _L3 (tilt in the direction of the arrow _A3 ). In this way, when the gimbal 13 is tilted while the flywheel 11 is rotating, a gyro effect is exerted from the flywheel 11 to the gimbal 13, and a gyro moment is generated in the housing 16 of the load rotation device 10 about the vertical axis _L1 . This gyro moment causes the load rotation device 10 to rotate about the vertical axis _L1 (rotate in the direction of the arrow _A1 ). Since the load 50 is suspended below the load slewing device 10, when the load slewing device 10 rotates about the vertical axis _L1 , the load 50 also rotates about the vertical axis _L1 (rotates in the direction of arrow _A3 ).

The direction in which the load 50 rotates can be reversed by reversing the direction in which the flywheel 11 is rotated or the direction in which the gimbal 13 is tilted. When the load 50 has rotated to the desired direction, the rotation by the load rotation device 10 is stopped, and the rotation of the load 50 is stopped. The load rotation device 10 of this embodiment can be operated by a remote controller 17.

As described above, the load rotation device 10 rotates the load 50 by the gyro effect that occurs when the gimbal 13 is tilted while the flywheel 11 is rotating. However, while the gimbal 13 continues to tilt, the gyro effect continues to be exerted from the flywheel 11 to the gimbal 13, and the rotation speed of the load 50 continues to increase. For this reason, if the rotation speed of the load 50 is not limited, the rotation speed of the load 50 will become too fast, which may cause danger.

In this regard, the load rotation device 10 uses the above-mentioned rotation speed limiting means 15 (torque limiter) to limit an increase in the rotation speed of the suspended load 50. When the tilt torque T of the gimbal tilting motor 14 (the torque with which the gimbal tilting motor 14 tilts the gimbal 13 about the axis _L3 ) exceeds a predetermined limit value (defined as _Tr ), this rotation speed limiting means 15 (torque limiter) holds the input current to the gimbal tilting motor 14 at the value at that time, and stops the tilting by the gimbal tilting motor.

That is, when the load 50 is rotating, the gyro effect caused by the rotation of the load 50 applies a torque T' to the output shaft of the gimbal tilting motor 14 in the opposite direction to the direction in which the output shaft is rotating (tilting) (the direction of the tilting torque T), and the tilting torque T of the gimbal tilting motor 14 increases. In other words, the rotation speed of the load 50 is directly reflected in the tilting torque T of the gimbal tilting motor 14. Therefore, the tilting torque T of the gimbal tilting motor 14 is an index of the rotation speed of the load 50. Therefore, by limiting the cymbal tilting motor 14, the increase in the rotation speed of the load 50 can be limited.

FIG. 2 shows an example of a flow diagram of the rotation operation of the load 50 by the load rotation device 10. The rotation of the flywheel 11 is assumed to have already started at a stage prior to step S1 in FIG. 2. As shown in FIG. 2, when the rotation operation of the load 50 starts (step S1), the tilt of the gimbal 13 starts (step S2). Specifically, the current input to the gimbal tilting motor 14 starts, and the current is increased. Then, the gimbal 13 gradually starts to tilt to one side from the initial position (standing vertically), and the load 50 starts to rotate in the direction of the arrow A ₁ ( FIG. 1 ) due to the gyro effect caused by the rotation of the flywheel 11. As the tilt angle of the gimbal 13 increases, the rotation speed of the load 50 (angular velocity of rotation of the load 50) gradually accelerates.

In this way, when the gimbal 13 is tilted and the load 50 is rotating, if a rotation stop operation is performed by the remote controller 17 or the like ("YES" in step S3), the current input to the gimbal tilting motor 14 is stopped (step S7). As a result, the gimbal 13 is released from the restraint by the gimbal tilting motor 14 and can be freely tilted in the direction of the arrow _A3 (FIG. 1). Therefore, the tilting of the gimbal 13 to one side is stopped, and thereafter, due to the gyro effect of the load 50 rotating by inertia, the gimbal 13 begins to tilt in the opposite direction (the side returning to the initial position), and the rotation of the load 50 is stopped. This ends the rotation operation of the load 50 (step S8).

On the other hand, if the gimbal 13 continues to tilt without performing a rotation stop operation ("NO" in step S3), the rotation speed of the load 50 continues to increase, and the tilt torque T of the gimbal tilting motor 14 continues to increase until it reaches the limit value T _r ("NO" in step S4). On the other hand, if the tilt torque T of the gimbal tilting motor 14 exceeds the limit value T _r ("YES" in step S4), the tilt of the gimbal 13 is stopped (step S5). Specifically, the input current to the gimbal tilting motor 14 is held at the value at that time (the current-carrying state at that time is held). When the tilt torque T of the gimbal tilting motor 14 is balanced with the torque T' (FIG. 1) due to the gyro effect caused by the rotation of the load 50, the tilt of the gimbal 13 stops.

When the tilt of the gimbal 13 is stopped, the gyro effect caused by the rotation of the flywheel 11 is no longer exerted on the load 50, and the increase in the rotation speed of the load 50 stops. Even when the tilt of the gimbal 13 is stopped, the load 50 continues to rotate due to inertia, but the rotation speed gradually decreases due to resistance such as friction. While the tilt torque T of the gimbal tilting motor 14 is greater than the limit value T _r , the state in which the tilt of the gimbal 13 is stopped is maintained ("NO" in step S6), but when the tilt torque T of the gimbal tilting motor 14 becomes smaller than the limit value T _r , the tilt of the gimbal 13 starts again ("YES" in step S6).

As described above, by limiting the rotation speed of the load 50 using a method for limiting the tilt torque T of the gimbal tilt motor 14, the rotation speed of the load 50 can be quickly limited when necessary. Therefore, even when external disturbances such as wind are occurring, the increase in the rotation speed can be reliably suppressed so that the rotation speed does not exceed the upper limit. In addition, there is no need to perform complex calculations, and the rotation speed of the load 50 can be limited in a simple manner. Furthermore, there is no need to provide a separate sensor (such as a gyro sensor) for detecting the rotation speed of the load 50. Therefore, the configuration of the load rotation device 10 can be simplified.

Furthermore, as shown in step S6 of FIG. 2, when the tilting torque T of the gimbal tilting motor 14 becomes smaller than the limit value T _r , the tilting of the gimbal tilting motor 14 is resumed. This makes it possible to continue rotating the load 50 at the rotation speed just before it exceeds the upper limit, and also makes it possible to increase the efficiency of loading and unloading operations, such as by rotating the load 50 to the desired orientation in a short period of time.

Incidentally, in the load rotation device 10, as can be seen from the execution of the process of step S4 in Fig. 2, the maximum value (maximum angular velocity) of the rotation speed of the load 50 changes depending on the limit value T _r . Fig. 3 is a graph showing the relationship between the power supply time to the gimbal tilting motor 14 and the rotation speed of the load 50 when the limit value T _r is changed in the load rotation device 10. In the graph, curve A shows the case where the limit value T _r is set to 100% of the rated torque of the gimbal tilting motor 14, curve B shows the case where the limit value T _r is set to 70% of the rated torque of the gimbal tilting motor 14, curve C shows the case where the limit value T _r is set to 50% of the rated torque of the gimbal tilting motor 14, and curve D shows the case where the limit value T _r is set to 30% of the rated torque of the gimbal tilting motor 14. 3, when the limit value T _r is set to a high value, the maximum value (maximum angular velocity) of the rotation speed of the load 50 increases, and conversely, when the limit value T _r is set to a low value, the maximum value (maximum angular velocity) of the rotation speed of the load 50 increases. The graph in FIG. 3 was obtained by numerical calculation, but it has been confirmed that results similar to this can be obtained by actual measurement.

In view of such characteristics, it is preferable to provide the load rotation device 10 with a limit value adjustment means (not shown) for adjusting the limit value T _r that limits the rotation speed of the load 50. This makes it possible to adjust the maximum value (maximum angular velocity) of the rotation speed of the load 50. In addition, since the maximum value (maximum angular velocity) of the rotation speed of the load 50 also varies depending on the load (moment of inertia of rotation) of the load, it is also possible to adjust the limit value T _r according to the load of the load 50 by setting the limit value T _r low when the load 50 is light and setting the limit value T _r high when the load 50 is heavy.

In other words, the limit value T _r may be one that cannot be changed from a single predetermined value, but various loads are assumed as the load 50, from a light load with a small moment of inertia in the rotation direction to a heavy load with a large moment of inertia. That is, since a light load is likely to have a faster rotation speed than a heavy load, if the limit value T _r is set assuming a heavy load, when the load 50 is switched to a light (small) load, the peripheral speed (rotation speed) of the load 50 may become unnecessarily slow. Therefore, by providing a limit value adjustment means 15 (torque limiter) that adjusts the limit value T _r , the rotation speed of the load 50 can be increased within a range that does not reach the critical speed.

The limit value adjustment means may be one that adjusts the limit value T _r in stages (one that selects the control value T _r from a plurality of predetermined values) or one that adjusts the limit value T _r continuously. Examples of the operation portion of the limit value adjustment means include various types of operation portions such as buttons, switches, dials, levers, and touch panels. These operation portions may be provided in the remote controller 17 (FIG. 1). This allows the worker 70 to manually adjust the rotation speed of the suspended load 50.

REFERENCE SIGNS LIST 10 Load rotation device 11 Flywheel 12 Flywheel rotation motor 13 Gimbal 14 Gimbal tilt motor 15 Rotation speed limiting means 16 Housing 17 Remote controller 50 Suspended load 60 Hook 70 Worker A ₁ Rotation direction of suspended load A ₂ Rotation direction of flywheel A ₃ Tilting direction of gimbal L ₁ Vertical axis that is the rotation center of suspended load L ₂ Axis that is the rotation center of flywheel L ₃ Axis that is the tilt center of gimbal

Claims (2)

A flywheel and
a flywheel rotating motor that drives the flywheel to rotate;
A gimbal that supports the flywheel;
a gimbal tilting motor that drives the gimbal to tilt;
A load rotation device that rotates a load by using a gyro effect that occurs when a gimbal is tilted while a flywheel is rotated,
A rotation speed limiting means is provided, which is a current-limiting torque limiter and limits the rotation speed of the load .
When the gimbal tilt angle is increased while the flywheel is rotating, the rotation speed of the load accelerates.
When the load is rotating and the rotation stop operation is performed, the current input to the gimbal tilt motor is stopped, and the rotation of the load is stopped.
If no turning stop operation is performed,
When the tilt torque T of the gimbal tilting motor exceeds a predetermined limit value T _r , the rotation speed control means maintains the input current to the gimbal tilting motor at the value at that time, and the tilting by the gimbal tilting motor is stopped.
When the tilt torque T of the gimbal tilting motor falls below the limit value T _r , the limit on the rotation speed of the load by the rotation speed limiting means is released, the input current to the gimbal tilting motor increases, and tilting of the gimbal tilting motor resumes.
A load rotating device characterized by the above.
2. A load rotating device according to claim 1, further comprising a limit value adjusting means for adjusting the limit value _Tr.

Images