JP4616447B2 - Crane and crane control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a crane for lifting and lowering a suspended load and a crane control method.
[0002]
[Prior art]
FIG. 8 shows the cargo handling situation of the container crane 1 installed on a quay or the like. In the figure, when the load n of the ground g is loaded on the ship s using the trolley 3 on the girder 2, the main winding motor 6 provided in the trolley is driven, and the wire 4 is lowered to suspend the hanger. After gripping the load n at 5, the wire 4 is wound up, and then the trolley 3 is moved to move the suspended load n to the unloading position, and then the wire 4 is lowered to land the suspended load n on the ship S. To load.
FIG. 9 shows a one-cycle output pattern of the winding and lowering speeds of the conventional main winding motor 6 at the time of cargo handling. At the time of winding and lowering, the motor speed is accelerated at a constant acceleration up to the top speed vmax (double speed of the base speed v0), and decelerated from the top speed vmax at a constant deceleration. The top speed vmax is set according to the weight of the suspended load. That is, the top speed vmax is small when the suspension load is large, and the top speed vmax is large when the suspension load is small.
[0003]
[Problems to be solved by the invention]
By the way, with the conventional main motor, when the speed is increased from the base speed v0 to the double speed control region, acceleration / deceleration is performed at a constant acceleration and constant deceleration that do not exceed the motor overload capacity from the top speed vmax and the suspended load. It was. For this reason, in order to shorten the cycle time by increasing the acceleration / deceleration, it is necessary to increase the motor specification, resulting in an increase in cost.
[0004]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a crane and a crane control method that can shorten the lifting and lowering time of a suspended load.
[0005]
[Means for Solving the Problems]
The crane according to claim 1, a motor for hoisting and lowering a suspended load, a suspended load holding torque calculating unit for calculating a suspended load holding torque necessary for holding a suspended load based on the weight of the suspended load, A maximum torque calculating unit that calculates a maximum torque that can be generated by the motor; and a control unit that performs acceleration control of the motor within a region of an acceleration torque of the suspended load obtained by subtracting the suspended load holding torque from the maximum torque; It is provided with.
[0006]
In order to suspend a suspended load from a crane, a predetermined suspended load holding torque is required even if the acceleration is zero.
In this crane, the suspended load holding torque is subtracted from the maximum torque that the motor can produce, and the acceleration torque of the suspended load that can be safely lifted and lowered without dropping the suspended load is calculated. The acceleration control (acceleration / deceleration of the suspended load) is controlled within the range of the acceleration torque. As a result, the torque of the motor can be used effectively, and the acceleration time is shortened. In addition, the suspended load is prevented from dropping due to excessive acceleration.
[0007]
The crane according to claim 2 is the crane according to claim 1, wherein the weight of the suspended load is calculated based on the torque current and the suspended load speed of the motor during the constant acceleration of the motor. A calculation unit is provided.
[0008]
In this crane, torque current and suspended load speed are used to calculate the weight of the suspended load. For example, the current of the motor is detected using an ammeter to obtain a torque current component, and the suspended load amount is estimated using the suspended load speed.
[0009]
The crane control method according to claim 3 calculates a load holding torque necessary for holding a load based on a weight of the load, sequentially calculates a maximum torque that can be output by the motor, and outputs the maximum torque. The acceleration control of the motor is performed within the region of the acceleration torque of the suspended load obtained by subtracting the suspended load holding torque from the suspension load.
[0010]
In this invention, the torque for holding the suspended load is subtracted from the maximum torque that can be generated by the motor, and the acceleration torque that can be safely wound and lowered without dropping the suspended load by the crane is calculated. Within the range of the acceleration torque, acceleration control (acceleration / deceleration) of the suspended load is performed. As a result, the torque of the motor can be used effectively, and the acceleration time is shortened. In addition, the suspended load is prevented from dropping due to excessive acceleration.
[0011]
According to a fourth aspect of the present invention, in the crane control method according to the third aspect, prior to the acceleration control of the motor, the suspended load is accelerated at a constant acceleration for a certain period of time. The suspension load amount is calculated based on the above.
[0012]
In the present invention, for example, when accelerating a suspended load from a speed of 0 to a predetermined speed, first the acceleration is increased at a constant acceleration, and the suspended load amount is calculated during that time. Thereafter, the acceleration control of the motor is performed.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described. In addition, about the structure same as the past, the same code | symbol is used and the description is abbreviate | omitted.
In this example, between the speed of 0 and the base speed, the suspended load is estimated by detecting the torque current of the main winding motor that is winding the suspended load at a constant acceleration, and the current output is based on this estimated suspended load. Calculates the maximum acceleration or maximum deceleration that the motor can output at the motor speed in real time, and variably controls the acceleration up to the calculated maximum speed or the deceleration from the maximum speed to the base speed in the constant output range. Thus, the winding and lowering cycle times are shortened.
FIG. 1 is a block diagram of a crane control apparatus according to the present invention. As shown in the figure, this apparatus includes a crane controller 8 that controls the entire operation of the crane based on an operation command from the master controller 7, and a motor controller 9 that drives a main winding motor 6 in response to a signal from the crane controller 8. , An ammeter 10 for measuring the torque current I of the main winding motor 6 is provided. In the motor controller 9, a torque current component is detected from the current measurement value detected by the ammeter 10 and sent to the crane control device 8.
[0014]
Next, details of the crane control device 8 will be described.
FIG. 2 is a partial block diagram of the crane control device 8. In the figure, reference numeral 15 denotes a suspended load amount calculation unit that estimates and outputs the total weight M of the suspended load from the torque current and the suspended load speed, and reference numeral 16 denotes the suspended load necessary for holding the suspended load based on the suspended load amount M. A suspended load holding torque calculating unit that calculates a torque for use, a reference numeral 18 is a maximum torque calculating unit that calculates a maximum torque that the motor can output based on the motor speed V1, and a reference numeral 20 is a torque for holding the suspended load from the maximum torque. It is a control part which performs acceleration control of the said motor based on the acceleration torque of the suspended load calculated | required by pulling.
[0015]
Now, in the container crane of this example, the speed control system which sets the top speed vmax of the main winding motor 6 according to the suspended load amount M is adopted. FIG. 3 shows the output characteristics of the main winding motor 6. This is a constant torque region where the rated torque is output until the motor speed reaches the base speed v0. The base speed v0 to the top speed vmax is a constant output region where the output torque decreases in inverse proportion to the speed. That is, when the speed is increased, the outputtable torque of the main winding motor 6 decreases after the base speed v0 is exceeded.
FIG. 4 shows a comparison between the maximum motor power of the main winding motor 6 and the actual output, which is necessary only to suspend the amount of suspended load with respect to the maximum motor power kwmax of the main winding motor 6 regardless of the lifting / lowering of the suspended load. The motor output kw1 (region A) is low as shown in the figure. That is, the region between kw1 and kwmax (region B) is a torque region that can be used for acceleration or deceleration. Since the maximum motor power kwmax of the main winding motor 6 decreases with the motor speed, it is necessary to control the motor acceleration while monitoring the maximum motor power kwmax in order to use this torque region effectively.
[0016]
Next, an acceleration control method for the main winding motor 1 will be described with reference to an acceleration control flow shown in FIG.
First, the suspended load n is wound up at a constant acceleration. The motor controller 9 detects the torque current I of the main winding motor 6 in the constant torque region from the motor speed 0 (step S1). The detected torque current I is taken into the suspended load amount calculation unit 15 of the crane control device 8. The suspension load amount calculation unit 15 estimates a suspension load amount (including wire and suspension weight) M from the suspension load speed and the torque current I (step S2).
FIG. 6 shows the relationship between time and motor speed. The estimation of the suspended load amount is performed in the suspended load amount calculation section indicated by reference numeral A in FIG.
[0017]
After the suspension load amount calculation section A has passed and the motor speed has reached the base speed v0, the following control from step S3 is performed. The following control is performed at a control cycle (for example, every 25 ms).
The suspended load holding torque calculation unit 16 uses the estimated suspended load amount M to calculate the formula −C ₁ = (Mg / η) / {(πα) ² GD ² }.
(However, at the time of lowering, -C ₁ = (Mgη) / {(πα) ² GD ² })
Is calculated. Further, the maximum torque calculation unit is expressed by the formula C ₂ / V 1 = Pm / {(πα) ² GD ² · V 1}.
Is calculated.
In the above equations,
M: Total weight of suspended load [kg] g; Gravity acceleration 9.8 [m / s ² ]
η: Overall mechanical efficiency α: Speed [rpm] / Motor speed [m / min] ratio GD ² ; Moment of inertia [kg · m ² ] V1; Current motor speed [m / s]
Pm: Maximum motor power [w]
It is.
From the difference (C ₂ / V ₁ + C ₁ ), the control unit 20
Acceleration a or maximum deceleration d = (C ₁ × V ₁ + C ₂ ) / V 1
Is calculated (step S3).
[0018]
Further, the control unit 20 obtains the speed command value V by the following equation, and accelerates the main winding motor 6 in the constant output region by this speed command value V, or decelerates and lowers it (steps S4 and S5).
V = V1 + a or d × T
T: Control period (sec) of crane control device 8
Thus, as shown in FIG. 6, the acceleration time t ₂ -t ₁ is shortened compared to the acceleration time t ₃ -t ₁ according to the conventional method, and the cycle time required for the lifting operation of the suspended load is greatly reduced.
In the next control cycle, the value of V1 becomes V, and the above control is repeated.
In the case of deceleration, since the suspended load amount M has already been estimated, control corresponding to steps S3 to S5 is performed. As a result, as shown in FIG. 7, the deceleration time t ₆ -t ₅ is shortened compared to the deceleration time t ₆ -t ₄ according to the conventional method.
[0019]
Thus, according to the crane of this example, the torque current of the main winding motor 6 that is winding the suspended load at a constant acceleration is detected to estimate the amount of the suspended load, and this estimated suspended load amount is used to determine the main winding motor. The maximum acceleration or maximum deceleration that can be produced by the motor 6 is calculated, and in the constant output region, the acceleration is accelerated to the calculated maximum acceleration or the deceleration is reduced to the maximum deceleration. Winding and unwinding cycle times can be greatly shortened.
[0020]
The validity of the suspended load amount M estimated during hoisting at a constant acceleration may be performed during hoisting constant speed operation after completion of acceleration. That is, during the hoisting constant speed operation, the crane control device 8 estimates the suspended load amount M from the suspended load speed and the torque current I in the same manner as in steps S1 and S2. When it is determined that the speed is too high, the crane control device 8 reduces the hoisting speed. As a result, cargo handling can be performed more safely.
[0021]
【The invention's effect】
As described above, according to the present invention, the amount of suspension load is estimated by detecting the torque current of the main-winding motor that is winding the suspended load at a constant acceleration, and the main-winding motor is output using this estimated amount of suspended load. The maximum acceleration or deceleration that can be obtained is calculated, and in the constant output area, the calculated maximum acceleration or the maximum deceleration can be accelerated or decelerated to the maximum deceleration. Lowering cycle time can be greatly shortened.
[Brief description of the drawings]
FIG. 1 is an apparatus block diagram of a crane shown as an embodiment of the present invention.
FIG. 2 is a block diagram showing an internal configuration of a crane control device.
FIG. 3 is a diagram showing output characteristics of a main winding motor.
FIG. 4 is a comparison diagram of motor power and actual output of the main winding motor.
FIG. 5 is an acceleration control flowchart in the crane.
FIG. 6 is a diagram showing an acceleration output pattern in the crane.
FIG. 7 is a diagram showing the deceleration output pattern.
FIG. 8 is a diagram illustrating a cargo handling situation of a container crane.
FIG. 9 is a diagram showing a one-cycle output pattern of the winding and unwinding speeds of a conventional main winding motor during cargo handling.
[Explanation of symbols]
6 Main winding motor 15 Suspended load amount calculating unit 16 Suspended load holding torque calculating unit 18 Maximum torque calculating unit 20 Control unit

Claims (6)

A motor for hoisting and lowering the suspended load, a suspended load holding torque calculating unit for calculating a suspended load holding torque necessary for holding the suspended load based on the weight of the suspended load,
A maximum torque calculator for calculating a maximum torque that can be generated by the motor;
A crane , comprising: a control unit that performs acceleration control of the motor in a region of acceleration torque of a suspended load obtained by subtracting the suspended load holding torque from the maximum torque. The crane according to claim 1,
A crane comprising a suspended load amount calculation unit for calculating a weight of the suspended load based on a torque current and a suspended load speed of the motor during a constant acceleration of the motor. Calculate the load holding torque necessary for holding the load based on the weight of the load, and sequentially calculate the maximum torque that the motor can output and subtract the load holding torque from the maximum torque. A crane control method comprising performing acceleration control of a motor within a region of acceleration torque of a suspended load. In the crane control method according to claim 3,
A crane control method characterized by accelerating a suspended load at a constant acceleration for a certain period of time prior to the acceleration control of the motor, and calculating a suspended load amount based on a torque current and a suspended load speed during this period. The crane according to claim 1 or 2,
  The said control part calculates the acceleration a of the said motor based on the following formula | equation, The crane characterized by the above-mentioned.
a = (C ₁ × V1 + C ₂ ) / V1
C ₁ =-(Mg / η) / {(πα) ² GD ² })
C ₂ = Pm / {(πα) ² GD ² }
here,
M: Weight of the suspended load
g: Gravity acceleration
η: Mechanical efficiency
α: Ratio of the rotation speed of the motor and the winding / lowering speed
GD ² : Moment of inertia of the motor
V1: Current speed of the motor
Pm: Maximum output of the motor In the crane control method according to claim 3 or claim 4,
  The crane control method characterized by calculating the acceleration a of the motor based on the following equation.
a = (C ₁ × V1 + C ₂ ) / V1
C ₁ =-(Mg / η) / {(πα) ² GD ² })
C ₂ = Pm / {(πα) ² GD ² }
here,
M: Weight of the suspended load
g: Gravity acceleration
η: Mechanical efficiency
α: Ratio of the rotation speed of the motor and the winding / lowering speed
GD ² : Moment of inertia of the motor
V1: Current speed of the motor
Pm: Maximum output of the motor

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