JP2021062960A - Control system and crane - Google Patents

Abstract

To provide a control system and a crane which maintain a state in which rotation of a drive shaft is stopped even if a mechanical failure occurs in a mechanical brake device.SOLUTION: A control system 10 includes a control device 11 connected to each of an inverter 7 for controlling drive of an electric motor 6 and a mechanical brake device 9 for mechanically braking rotation of a drive shaft 8 of the electric motor 6. The control system is configured so that the control system includes a drive parameter acquisition device 13 for acquiring a drive parameter θx related to the drive of the electric motor 6, a driving state of the electric motor 6 controlled by the inverter 7 by the control device 11 is composed of a stop state, a power driving state, a braking driving state, and a preliminary excitation state in which the rotation of the driving shaft 8 is stopped by generating torque on the basis of the driving parameter θx acquired by the drive parameter acquisition device 13, and in the case that a state in which the drive shaft 8 of the electric motor 6 is stopped is held, the control device 11 controls the inverter 7 to make the electric motor 6 in the preliminarily excited state as a spare of the mechanical brake device 9.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control system and a crane, and more particularly to a control system and a crane for holding a stopped state of a drive shaft of an electric motor.

A crane control device has been proposed in which a mechanical braking device mechanically brakes the rotation of the drive shaft of an electric motor to hold the drive shaft of the electric motor in a stopped state (see, for example, Patent Document 1). This control device activated the mechanical brake device by forcibly stopping the supply of current to the mechanical brake device when a problem occurred in the circuit that supplies the current to the mechanical brake device, and the drive shaft stopped. Holds the state.

JP-A-2017-143648

However, the device described in Patent Document 1 does not take any measures against a mechanical failure of the mechanical brake device. Therefore, even if a mechanical failure occurs in the mechanical brake device and the rotation of the drive shaft of the electric motor cannot be braked without the mechanical brake device operating, or even if the mechanical braking device is activated, the drive shaft of the electric motor It is not possible to cope with the situation where the rotation cannot be braked.

An object of the present invention is to provide a control system and a crane that keep the drive shaft of an electric motor stopped even if a mechanical failure occurs in the mechanical braking device.

The control system of the present invention that achieves the above object is a control including a control device connected to each of an inverter that controls the drive of the electric motor and a mechanical brake device that mechanically brakes the rotation of the drive shaft of the electric motor. The system includes a drive parameter acquisition device that acquires drive parameters related to the drive of the electric motor, and the drive state of the electric motor controlled by the inverter by the control device is a stop in which the rotation of the drive shaft is stopped without generating torque. A state, a power running drive state in which the drive shaft is rotationally driven to output a driving force, a braking drive state in which the drive shaft is rotationally driven to apply a braking force, and the drive parameter acquired by the drive parameter acquisition device. A pre-excited state in which the rotation of the drive shaft is stopped due to a torque based on the above is generated, and when the drive shaft is held in the stopped state, the control device is used as a spare for the mechanical brake device. It is characterized in that the inverter is controlled to bring the electric motor into the pre-excited state.

The crane of the present invention that achieves the above object is provided with the control system described above, and is characterized in that the electric motor rotates and drives a drum around which a cord-like body is wound.

According to the present invention, by controlling the electric motor to be in the pre-excited state as a spare of the mechanical brake device, even if a mechanical failure occurs in the mechanical brake device, the electric motor is in the pre-excited state and the drive shaft is rotated. Can be electrically braked to keep the drive shaft stopped.

It is a figure which combined the block diagram which illustrates the embodiment of the control system provided with the crane, and the block diagram which illustrates the embodiment of a crane. It is a flow chart which illustrates the control method of a crane by a control system. It is a flow chart which follows I of FIG. It is a flow chart which follows II of FIG. 2 is a flow chart illustrating a control method performed in parallel with the control method shown in FIGS. 2 to 4.

Hereinafter, embodiments of the control system and the crane of the present disclosure will be described. In the figure, the electrical connection is indicated by the alternate long and short dash line in the figure, and includes a wired connection via a signal line and a wireless connection via a wireless communication device.

As illustrated in FIG. 1, the crane 1 of the present embodiment includes a control system 10 and performs cargo handling work at a container terminal. The crane 1 includes a drum 4 around which a cord-like body 3 suspending a suspension body 2 is wound, an electric motor 6 that rotationally drives the drum 4 via a transmission 5, and an inverter 7 that controls the drive of the electric motor 6. And a mechanical braking device 9 that mechanically brakes the rotation of the drive shaft 8 of the electric motor 6.

The type of the crane 1 is limited as long as it can raise and lower the suspension body 2 up and down by winding and unwinding the cord-like body 3 by the drum 4 which is rotationally driven by the electric motor 6 controlled by the inverter 7. is not it. Examples of the crane 1 include a gantry crane having a girder supported above the leg structure and a trolley moving along the extending direction of the girder, a quay crane, and an unloader. A gantry crane is a crane in which a girder is configured to straddle a storage lane in which a container is stored, and cargo handling work is performed between the storage lane and a transport vehicle. A quay crane is a crane in which a girder is configured to project to the sea side and cargo handling work is performed between a ship and a carrier. The unloader is a crane in which the girder is configured to project to the sea side and handles bulk cargo such as steel stones and coal between the ship and the hopper. Examples of the crane 1 include jib cranes without girders and trolleys and overhead cranes without leg structures.

The hanging body 2 is a hanging tool and a hanging load (for example, a container) when the hanging tool suspended from the cord-shaped body 3 is joined to the hanging load, and when the hanging tool is not joined to the hanging load. It is a hanging tool. Examples of the hanger include a spreader for a container, but the hanger is not particularly limited, and a grab bucket, a hook, or a coil lifter may be used.

The electric motor 6 is composed of a servomotor capable of controlling the position θx of the drive shaft 8 in addition to the rotation speed Vx of the drive shaft 8. The electric motor 6 of the present embodiment is composed of an induction motor among the servomotors. The drive state of the electric motor 6 is controlled via the inverter 7, and the drive state controlled by the inverter 7 includes a stop state, a power running drive state, a braking drive state, and a pre-excitation state.

The stopped state is a state in which the rotation of the drive shaft 8 is stopped without the electric motor 6 generating torque. Further, the stopped state is a state in which electric power is not supplied to the electric motor 6 from the inverter 7. The power running drive state is a state in which the drive shaft 8 is rotationally driven to output a driving force for rotating the drum 4 in the direction of winding the cord-like body 3. Further, the power running drive state is a state in which electric power is supplied to the electric motor 6 from the inverter 7. The braking drive state is a state in which the drum 4 rotates in the direction in which the cord-shaped body 3 is fed, and the drive shaft 8 is rotationally driven to apply braking force in accordance with the rotation. As the braking drive state, regenerative braking in which the drive shaft 8 is rotationally driven to generate regenerative power is exemplified. When the braking drive state is regenerative braking, the electric power generated by the electric motor 6 is supplied to the inverter 7 and stored in a battery (not shown) mounted on the crane 1, and the resistance of the braking resistor installed on the crane 1. It is in a state where it is consumed as heat, or it is in a state where it is stored in a battery installed outside the crane 1 via a bus bar or a power supply cable. In addition, as the braking drive state, reverse phase braking (also referred to as plucking) and single phase braking are also exemplified.

The pre-excitation state is determined by the electric motor 6 based on the drive parameters (position θx of the drive shaft 8 and rotational speed Vx) related to the drive of the electric motor 6 earned by the drive parameter acquisition device (position acquisition device 13 and rotational speed acquisition device 14) described later. The rotation of the drive shaft 8 is stopped while the torque is generated. Further, the pre-excitation state is a state in which electric power is supplied to the electric motor 6 from the inverter 7. Examples of the pre-excitation state include a state in which speed control (also referred to as 0-speed control) and a state in which position control (also referred to as servo lock control) is performed. The speed control in the pre-excited state is a control in which the rotation speed Vx of the drive shaft 8 is used as a drive parameter and the rotation speed Vx is kept at zero by the inverter 7. In the position control, the position of the drive shaft 8 (more specifically, the angular position) is used as a drive parameter, and the position of the drive shaft 8 is held by the inverter 7. The pre-excitation state may be a state in which the rotation of the drive shaft 8 is stopped, a state in which the speed is controlled, or a state in which the position is controlled.

The mechanical braking device 9 is a brake that brakes the rotation of the drive shaft 8 of the electric motor 6 by a frictional force. The mechanical brake device 9 of the present embodiment is composed of an electro-hydraulic thruster disc brake device. In the electro-hydraulic thruster disc brake device, when the power supply is stopped, the hydraulic pressure is released and the thruster is driven, and the brake lining is pressed against the disc directly fixed to the drive shaft 8. The drive shaft is generated by the frictional force generated. The rotation of No. 8 is braked, and when power is supplied, the thruster is driven by flood control to separate the brake lining from the disc and release the braking of the rotation of the drive shaft 8. The mechanical braking device 9 may be any device that brakes the rotation of the drive shaft 8 by frictional force when the supply of electric power is stopped, and releases the braking of the rotation of the drive shaft 8 when the supply of electric power is supplied. It is not limited to electrohydraulic thruster disc brakes.

The control system 10 of the present embodiment is provided in the crane 1 and controls the inverter 7 and the mechanical brake device 9 to wind and unwind the cord-like body 3 that suspends the suspension body 2 by the drum 4. is there. The control system 10 is not limited to the one applied to the drum 4 that winds up and unwinds the cord-like body 3 that suspends the suspension body 2 in the crane 1, and applies to the drum that undulates the girder and the drum that traverses the trolley. May be applied. Further, the target to be rotationally driven by the electric motor 6 is not limited to the drum, and the control system 10 is not limited to the one applied to the crane 1.

The control system 10 includes a control device 11, an operation device 12, a position acquisition device 13, a rotation speed acquisition device 14, a brake operation acquisition device 15, and a warning device 16. The control device 11 is electrically connected to each of the inverter 7, the mechanical brake device 9, the operation device 12, the brake operation acquisition device 15, and the warning device 16, and the electric motor 6 and the position acquisition device 13 are electrically connected via the inverter 7. And each of the rotation speed acquisition device 14 is electrically connected. Each of the position acquisition device 13 and the rotation speed acquisition device 14 may be electrically connected to the control device 11 directly without using the inverter 7.

The control device 11 is hardware composed of a central processing unit (CPU) that performs various information processing, an internal storage device that can read and write programs and information processing results used for performing various information processing, and various interfaces. Is. When the control device 11 is installed on the crane 1, it is installed in a machine room or a trolley (not shown). The control device 11 is not limited to the one installed on the crane 1, and may be installed at a remote location away from the crane 1.

In the operation device 12, the driver operates the operation console 12b based on the information displayed on the display device 12a, and the drive command C1 and the stop command C2 are transmitted to the control device 11 as the operation signals. The drive command C1 is an operation signal for putting the electric motor 6 into a power running drive state or a braking drive state, and is an operation signal for rotationally driving the drive shaft 8. The drive command C1 includes an acceleration command and a deceleration command. The stop command C2 is an operation signal that activates the mechanical brake device 9 and puts the electric motor 6 in a stopped state, and is an operation signal that stops the rotation of the drive shaft 8 and holds the state in which the drive shaft 8 is stopped. The stop command C2 in the present embodiment is also an operation signal for putting the electric motor 6 into a pre-excited state. Similar to the control device 11, the operation device 12 may be installed in a machine room or trolley (not shown) when it is installed in the crane 1, and may be installed in a remote place away from the crane 1. In addition, instead of the operating device 12 operated by the driver, a higher-level control device that automatically controls the crane 1 is provided, and the higher-level control device transmits the drive command C1 and the stop command C2 to the control device 11. Good.

The position acquisition device 13 functions as a drive parameter acquisition device, and is a device that acquires the position (more specifically, the angular position) θx of the drive shaft 8. Examples of the position acquisition device 13 include a rotary encoder and a potentiometer. The rotation speed acquisition device 14 functions as a drive parameter acquisition device and also functions as a brake parameter acquisition device for acquiring brake parameters related to the effectiveness of the mechanical brake device 9, and is a device for acquiring the rotation speed Vx of the drive shaft 8. Examples of the rotation speed acquisition device 14 include a rotary encoder and a potentiometer. The drive parameter acquisition device may be composed of one device having the function of the position acquisition device 13 and the function of the rotation speed acquisition device 14. Further, in the crane 1, the drive parameter acquisition device calculates the position θx and the rotation speed Vx of the drive shaft 8 based on the winding amount and the feeding amount of the cord-like body 3, the position and the rotation speed of the drum 4. It may be configured.

In the present embodiment, the effectiveness of the mechanical brake device 9 indicates a state in which the mechanical brake device 9 is operated and a braking force is actually applied to the drive shaft 8. Examples of the brake parameters include a change in deceleration of the drive shaft 8 before and after the mechanical brake device 9 is activated, and a braking force applied to the drive shaft 8. In the present embodiment, the brake parameter uses the change in the deceleration of the drive shaft 8 according to the rotation speed Vx of the drive shaft 8. A load cell is exemplified as a brake parameter device when the braking force applied to the drive shaft 8 is used as the brake parameter.

The brake operation acquisition device 15 is a device that acquires the operating state of the mechanical brake device 9, and is preferably a device that acquires that the mechanical brake device 9 is operated so as to apply a braking force to the drive shaft 8. .. Examples of the brake operation acquisition device 15 include a limit switch and a laser range finder. For example, the limit switch is installed in the drive mechanism of the mechanical brake device 9 and detects the operating state of the drive mechanism when the brake lining is operated so as to come into contact with the disc. The laser rangefinder is installed to detect the distance between the brake lining and the disc. In the present embodiment, the operation of the mechanical brake device 9 indicates that the drive mechanism of the mechanical brake device 9 is driven. That is, it is assumed that the operation of the mechanical brake device 9 and the effect of the mechanical brake device 9 are not synonymous. When the brake operation acquisition device 15 detects that the mechanical brake device 9 has been activated, it outputs an ON as an operation signal C3, and when it detects that the mechanical brake device 9 is not operating, it outputs an OFF as an operation signal C3. As the brake operation acquisition device 15, a device that acquires a state in which braking to the drive shaft 8 is released without the mechanical brake device 9 operating may be used, and the mechanical brake device 9 is not operating. It may be acquired that the mechanical braking device 9 has been activated if that is not acquired.

The warning device 16 is attached together with the operating device 12. An example of the warning device 16 is a device that emits a warning sound, but the warning device 16 is a display device different from the display device 12a and the display device 12a and is composed of a device that displays a warning on the screen and a device that vibrates the driver. May be good. Further, the warning device 16 may be configured to warn by blinking light.

The control device 11 has a brake control unit 17, an electric motor control unit 18, and a warning control unit 19 as functional elements for holding the drive shaft 8 of the electric motor 6 in a stopped state. Each functional element is stored as a program in the internal storage device of the control device 11, read out by the central processing unit, and executed as appropriate. In addition to the program, electric circuits in which each function independently functions are also exemplified as each functional element. Further, each of the functional elements may be configured by a programmable logic controller (PLC), and the control device 11 may be an aggregate of a plurality of PLCs.

The brake control unit 17 is a functional element that receives a stop command C2 and controls to operate the mechanical brake device 9 based on the stop command C2. Specifically, when the stop command C2 is input, the brake control unit 17 stops the supply of power to the mechanical brake device 9 and operates the mechanical brake device 9 so as to brake the rotation of the drive shaft 8. .. Further, when the drive command C1 is input and the stop command C2 is released, the brake control unit 17 supplies power to the mechanical brake device 9 to release the braking of the rotation of the drive shaft 8 of the mechanical brake device 9. To operate.

The brake control unit 17 is configured to operate the mechanical brake device 9 when the rotation speed Vx of the drive shaft 8 becomes slower than the preset first set speed Va when the stop command C2 is input. It is desirable to be done. Specifically, in addition to the stop command C2, the brake control unit 17 inputs the rotation speed Vx of the drive shaft 8 acquired by the rotation speed acquisition device 14. When the stop command C2 is input, the brake control unit 17 forces the electric motor 6 to the inverter 7 by the electric motor control unit 18 when the input rotation speed Vx of the drive shaft 8 is equal to or higher than the first set speed Va. Control is performed to reduce the rotational speed Vx of the drive shaft 8 by reducing the driving force output in the driving state or increasing the braking force applied in the braking drive state. Then, when the rotation speed Vx of the drive shaft 8 becomes slower than the first set speed Va, the brake control unit 17 stops the supply of power to the mechanical brake device 9 and operates the mechanical brake device 9.

The first set speed Va is a value set in advance by an experiment or a test, and is stored in the internal storage device of the control device 11. The first set speed Va is set to a value at which the state immediately before the rotation speed Vx of the drive shaft 8 is decelerated by the electric motor 6 and the rotation of the drive shaft 8 is stopped can be determined. The first set speed Va is preferably set based on the rated speed of the electric motor 6, and has a positive correlation with the rated speed. The rated speed is a speed set in advance according to the type of the electric motor 6 and the inverter 7. When the first set speed Va is set to zero, the operation of the mechanical brake device 9 becomes slow, and the drive shaft 8 may not be stopped at a desired timing. Further, if the first set speed Va is set to a speed faster than 10% of the rated speed, sudden braking occurs when the mechanical braking device 9 is operated, which lowers the durability of the mechanical braking device 9 and suspends it. There is a risk that the body 2 will shake significantly. Therefore, the first set speed Va is preferably set to a speed faster than zero, slower than 10% of the rated speed, and more preferably set to a speed of 4% to 6% of the rated speed. .. When the first set speed Va is set to a speed of 4% to 6% of the rated speed, it is advantageous to avoid the operation delay and sudden braking of the mechanical braking device 9.

The electric motor control unit 18 is a functional element in which a drive command C1 is input and the drive state of the electric motor 6 is controlled via the inverter 7 based on the drive command C1. Further, the electric motor control unit 18 receives a stop command C2 and controls the inverter 7 to put the electric motor 6 in a pre-excited state as a spare of the mechanical brake device 9 based on the pre-brake operating condition, and also sets the pre-brake release condition. Based on this, it is a functional element that controls the inverter 7 to release the pre-excited state of the electric motor 6. In addition, while the electric motor control unit 18 is in the pre-excited state of the electric motor 6 in the inverter 7, even if a command other than the drive command C1 of the electric motor 6 is input, the operation other than the rotational drive of the drum 4 by the electric motor 6 is performed. It is a functional element that controls to prohibit. The electric motor control unit 18 is input with the acquired values acquired by the position acquisition device 13, the rotation speed acquisition device 14, and the brake operation acquisition device 15. The electric motor control unit 18 has a timer 18a.

The preliminary brake operating condition is established unless the mechanical brake device 9 is activated or the mechanical brake device 9 is activated but the braking force is not applied so that the mechanical brake device 9 stops the rotation of the drive shaft 8. To do. In the present embodiment, the electric motor control unit 18 determines that the mechanical brake device 9 is not operating when the operation signal C3 output from the brake operation acquisition device 15 is off. Further, in the electric motor control unit 18, the rotation speed Vx acquired by the rotation speed acquisition device 14 that functions as the brake parameter acquisition device when the mechanical brake device 9 is activated is set to a speed slower than the first set speed Va in advance. If the vehicle does not decelerate to the second set speed Vb, it is determined that no braking force is applied. When the brake parameter acquisition device is composed of a load cell, the electric motor control unit 18 may determine that the braking force is not applied when the braking force detected by the load cell is lower than a preset threshold value. .. Further, the electric motor control unit 18 has a braking force when the deceleration of the drive shaft 8 after the mechanical brake device 9 is activated is not greater than the deceleration of the drive shaft 8 before the mechanical brake device 9 is activated. May be determined not to be given. In the present embodiment, the mechanical brake device 9 is configured to operate when the rotation speed Vx of the drive shaft 8 becomes equal to or less than the first set speed Va. Therefore, when the rotational speed Vx of the drive shaft 8 does not decelerate to the second set speed Vb when the mechanical brake device 9 is operated, it is possible to determine that the braking force is not applied.

The second set speed Vb is a value set in advance by experiments or tests and set to a speed slower than the first set speed Va, and is stored in the internal storage device of the control device 11. The second set speed Vb is used for determining whether or not the preliminary brake operating condition is satisfied, and is used for timing the motor 6 to be in the pre-excited state. The second set speed Vb is a value capable of determining that the rotation speed Vx of the drive shaft 8 is decelerating so that the rotation of the drive shaft 8 is stopped by the operation of the mechanical brake device 9, that is, the mechanical brake device 9 Is set to a value at which it can be determined that the deceleration of the drive shaft 8 has increased due to the operation of. Further, the second set speed Vb is a value capable of determining a state immediately before the rotation speed Vx of the drive shaft 8 is decelerated by the electric motor 6 and the rotation of the drive shaft 8 is stopped, and the electric motor 6 is pre-excited to the inverter 7. The state in which the inverter 7 does not become overloaded when set to is set to a value that can be determined. Like the first set speed Va, the second set speed Vb is preferably set based on the rated speed of the electric motor 6, and has a positive correlation with the rated speed. When the second set speed Vb is set to zero, the operation of the spare brake is delayed due to the response delay in the control system, and the drive shaft 8 may not be stopped at a desired timing. Further, if the second set speed Vb is set to a speed of 5% or more of the rated speed, the inverter 7 may be overloaded when the spare brake is operated, and the operation of the spare brake may be stopped. Therefore, the second set speed Vb is preferably set to a speed faster than zero, slower than 5% of the rated speed, and more preferably set to a speed of 1% to 3% of the rated speed. .. When the second set speed Vb is set to a speed of 1% to 3% of the rated speed, it is advantageous to avoid the operation delay of the spare brake and the overload of the inverter 7.

The pre-brake release condition is determined when it is determined that the drive command C1 is input by the operating device 12 while the motor 6 is controlled to the pre-excited state, or after the motor 6 counted by the timer 18a is in the pre-excited state. It is established when it is determined that the elapsed time tx has reached the preset release period ta.

The release period ta is a value set in advance by an experiment or a test, and is stored in the internal storage device of the control device 11. The release period ta is set to a value at which the overload of the inverter 7 when the electric motor 6 is driven in the pre-excited state can be determined. The release period ta is preferably set based on the capacity of the inverter 7, and has a positive correlation with the capacity of the inverter 7.

The warning control unit 19 causes the warning device 16 to warn the driver when the motor 6 is pre-excited by the motor control unit 18, and stops the warning of the warning device 16 when the drive command C1 is input by the operating device 12. It is a functional element that controls the operation.

As illustrated in FIGS. 2 to 5, the control method of the crane 1 of the present embodiment will be described as a function of the control system 10. This control method is started when the stop command C2 is issued by the operation of the operating device 12. Each of the position acquisition device 13, the rotation speed acquisition device 14, and the brake operation acquisition device 15 acquires an acquisition value each time a preset cycle elapses. It is assumed that one cycle elapses when the order returns to the upper step in the control flow or when those devices acquire the acquired value. At the start of the control flow, it is assumed that the vertical movement speed of the suspension body 2 is decelerated at a constant deceleration. In the state where the vertical movement speed of the suspension body 2 is decelerated at a constant deceleration, the speed at which the electric motor 6 is controlled to the power running drive state and the drum 4 winds up the cord-like body 3 when the suspension body 2 is raised. May be in a decelerated state, or a state in which the speed at which the electric motor 6 is controlled to the braking drive state and the drum 4 pays out the cord-like body 3 is decelerated when the suspension body 2 is lowered. Further, it is assumed that the control method illustrated in FIGS. 2 to 4 and the control method illustrated in FIG. 5 are processed in parallel.

As illustrated in FIG. 2, when the stop command C2 is generated by the operating device 12, the rotation speed acquisition device 14 acquires the rotation speed Vx of the drive shaft 8 (S110). Next, the brake control unit 17 determines whether or not the acquired rotation speed Vx is slower than the preset first set speed Va (S120). When it is determined that the rotation speed Vx is slower than the first set speed Va (S120: YES), the brake control unit 17 stops the supply of power to the mechanical brake device 9 and brakes the rotation of the drive shaft 8. A command is issued to operate the mechanical brake device 9 (S130). On the other hand, if it is determined that the rotation speed Vx is equal to or higher than the first set speed Va (S120: NO), the process returns to step S110.

As illustrated in FIG. 3, when a command to operate the mechanical brake device 9 is issued, the brake operation acquisition device 15 acquires that the mechanical brake device 9 has been activated and transmits an operation signal C3 (S210). In step S210, the operation signal C3 is turned on when the mechanical brake device 9 is activated, and the operation signal C3 is turned off when the mechanical brake device 9 is not operating. Next, the electric motor control unit 18 determines whether or not the preliminary brake operating condition is satisfied.

Specifically, the electric motor control unit 18 determines whether or not the operation signal C3 is on. (S220). When the operation signal C3 is determined to be ON (S220), the rotation speed acquisition device 14 acquires the rotation speed Vx of the drive shaft 8 (S230). Then, the electric motor control unit 18 determines whether or not the acquired rotation speed Vx has been decelerated to the preset second set speed Vb (S240). The steps S230 and S240 may be performed after a predetermined time (for example, 1 second to 2 seconds) has elapsed from the operation of the mechanical brake device 9.

When it is determined that the operation signal C3 is ON (S220: YES) and the rotation speed Vx is decelerated to the second set speed Vb (S240: YES), the preliminary brake operation condition is not satisfied and the motor control unit 18 Causes the inverter 7 to stop the electric motor 6 (S250), and this control flow ends. The state in which step S250 is completed is a state in which the drive shaft 8 of the electric motor 6 is held in a stopped state by the mechanical brake device 9.

On the other hand, when it is determined that the operation signal C3 is off (S220: NO), or the operation signal C3 is determined to be on and the rotation speed Vx is not decelerated to the second set speed Vb (S220: YES, S240). : NO), the preliminary brake operating condition is satisfied, and the electric motor control unit 18 controls the inverter 7 to put the electric motor 6 in the pre-excited state.

Specifically, when the preliminary brake operating condition is satisfied, the rotation speed acquisition device 14 acquires the rotation speed Vx of the drive shaft 8 (S260). Then, the electric motor control unit 18 determines whether or not the acquired rotation speed Vx has been decelerated to the preset second set speed Vb (S270). If it is determined that the rotation speed Vx has not decelerated to the second set speed Vb (S270: NO), the process returns to step S260. On the other hand, when it is determined that the rotation speed Vx has been decelerated to the second set speed Vb (S270: YES), the position acquisition device 13 acquires the position θx of the drive shaft 8 (S280). Next, the electric motor control unit 18 puts the electric motor 6 in the position control (servo lock control) state in the pre-excitation state in the inverter 7 so as to hold the acquired position θx (S290), and the mechanical brake device 9 As a spare, the electric brake in the pre-excited state of the electric motor 6 is operated. When the pre-brake operating condition is satisfied, the inverter 7 may be put into the speed control (0-speed control) state in the pre-excitation state of the electric motor 6.

The electric motor 6 is put into the speed control state in the pre-excited state in the inverter 7 until the rotation speed Vx of the drive shaft 8 becomes zero, and steps S280 and S290 are performed when the rotation speed Vx becomes zero. It may be. That is, when the preliminary brake operating condition is satisfied, the rotational speed Vx may be reduced to zero by speed control, and then the position θx of the drive shaft 8 may be held by position control.

As illustrated in FIG. 4, when the electric motor 6 is put into a pre-excited state as a spare of the mechanical brake device 9, the warning control unit 19 issues a warning to the driver by the warning device 16 (S310). Next, the electric motor control unit 18 determines whether or not the preliminary brake release condition is satisfied. Specifically, the electric motor control unit 18 determines whether or not the drive command C1 is issued by the operating device 12 (S320). Further, the electric motor control unit 18 counts the time tx elapsed since the electric motor 6 is in the pre-excited state, and determines whether or not the counted time tx has reached the preset release period ta (S330, S340). ..

When it is determined that the drive command C1 has been issued (S320: YES) and the warning device 16 stops the warning (S350), the preliminary brake release condition is satisfied, and the motor control unit 18 pre-excites the motor 6 to the inverter 7. The state is released, the electric motor 6 is put into the power running state or the braking drive state by the inverter 7 based on the drive command C1 (S360), and this control flow ends.

On the other hand, if it is determined that the drive command C1 cannot be issued by the time the counted time tx reaches the release period ta (S330: YES) (S320: NO), the preliminary brake release condition is set without stopping the warning. When established, the electric motor control unit 18 causes the inverter 7 to release the pre-excited state of the electric motor 6, and causes the inverter 7 to put the electric motor 6 into the braking drive state so as to lower the suspension body 2 (S370). In this step S370, the suspension body 2 is lowered and landed at a predetermined position. Then, the electric motor control unit 18 causes the inverter 7 to stop the electric motor 6 (S380). Then, the warning device 16 stops the warning (S390), and this control flow ends.

As illustrated in FIG. 5, when the electric motor 6 is put into a pre-excited state as a spare of the mechanical brake device 9 (S410: YES), the electric motor control unit 18 operates the drive command C1 of the operating device 12 other than the vertical movement. (S420), and this control flow ends. Examples of operations other than the vertical movement include a traversing operation of a trolley (not shown), a traveling operation by a traveling device of a crane 1, and a jib turning operation (not shown). Therefore, in this step S420, the electric motor control unit 18 issues a control prohibition command to the control unit that controls the traversing operation of the trolley, the traveling operation of the traveling device, the turning operation of the jib, and the like.

On the other hand, if the electric motor 6 is not in the preliminary example state (S410: NO), the electric motor control unit 18 releases the prohibition of operations other than vertical movement (S430), and this control flow ends. In step S430, the electric motor control unit 18 issues a control permission command to the control unit that controls the traversing operation of the trolley, the traveling operation of the traveling device, the turning operation of the jib, and the like.

As described above, the crane 1 provided with the control system 10 is configured to control the inverter 7 to put the electric motor 6 in the pre-excited state as a spare of the mechanical brake device 9. Therefore, according to the crane 1, even if a mechanical failure occurs in the mechanical brake device 9 and the mechanical brake device 9 does not operate normally or the mechanical brake device 9 operates, the drive shaft 8 Even if a situation occurs in which the rotation cannot be braked, the motor 6 is in a pre-excited state and the electric brake is activated, so that the state in which the rotation of the drive shaft 8 is stopped can be maintained. That is, by having an electric brake as a backup function against a mechanical failure of the mechanical brake device 9, it is possible to improve safety in cargo handling work.

In the speed control in the pre-excited state of the electric motor 6, the position of the drive shaft 8 stopped for the control of controlling the speed may shift. On the other hand, the position control can suppress the displacement of the position of the drive shaft 8 stopped for the control of controlling the position. Therefore, it is desirable that the control system 10 controls the position so as to hold the acquired position θx of the drive shaft 8 when the electric motor 6 is put into the pre-excited state. As described above, using the position-controlled electric motor 6 as a spare of the mechanical brake device 9 is advantageous for improving the accuracy of the stop position.

It is desirable that the control system 10 considers the response delay. In the present embodiment, the response delay is a delay from when the control device 11 issues a command to the inverter 7 to put the electric motor 6 in the pre-excited state until the electric motor 6 is actually put into the pre-excited state, which is a waste time element and a primary delay. It is indicated by the transmission characteristics shown in combination with the element and the multiple lag element. Therefore, it is desirable that the control system 10 is performed before the rotation speed Vx of the drive shaft 8 acquired by controlling the inverter 7 to put the electric motor 6 in the pre-excited state becomes zero. In the present embodiment, the timing for putting the electric motor 6 into the pre-excited state is the timing when the rotation speed Vx of the drive shaft 8 is later than the second set speed Vb set to a speed faster than zero. In this way, by timing the motor 6 to be in the pre-excited state using the second set speed Vb set to a speed faster than zero, the motor 6 before the rotation speed Vx of the drive shaft 8 becomes zero. Can be put into a pre-excited state. This is advantageous in avoiding the delay in the operation of the electric brake due to the delay in response.

It is desirable that the control system 10 warns the driver that the electric motor 6 is in the pre-excited state by the warning device 16 when the electric motor 6 is in the pre-excited state as a spare of the mechanical brake device 9. When the time tx elapsed after the electric motor 6 is put into the pre-excited state as a spare of the mechanical brake device 9 reaches the release period ta, the inverter 7 becomes overloaded and the pre-excited state of the electric motor 6 is released. Therefore, by warning the electric motor 6 that the electric motor 6 is in the pre-excited state by the warning device 16, it is advantageous to promote the driver to operate the operating device 12 and issue the drive command C1.

If the drive command C1 is not issued from the operation device 12 by the time tx reaches the release period ta, the electric motor control unit 18 automatically lowers the suspension body 2 and brakes and drives the electric motor 6 to land on the floor. It is preferable to put it in a state.

In addition to determining the operating status of the mechanical brake device 9 acquired by the brake operation acquisition device 15, the control system 10 has applied a braking force so that the rotation of the drive shaft 8 is stopped by the mechanical brake device 9. It is desirable to determine whether or not. As a result, although the mechanical braking device 9 is operated by the stop command C2, it is possible to cope with a situation in which the rotation of the drive shaft 8 cannot be braked.

For example, when the electric motor 6 is in the pre-excited state, if the trolley is operated in a transverse manner, the suspension body 2 may swing. If the electric motor 6 or the inverter 7 is overloaded due to this runout, the state in which the rotation of the drive shaft 8 is stopped may not be maintained. Therefore, it is desirable that the control system 10 prohibits operations other than the rotational drive of the drum 4 when the electric motor 6 is in the pre-excited state. In this way, when the electric motor 6 is in the pre-excited state, the operation other than the rotational drive of the drum 4 is prohibited, which is advantageous for avoiding an overload on the electric motor 6 and the inverter 7, and the drive shaft 8 It is advantageous to keep the rotation stopped.

1 Crane 2 Suspended body 3 Cord-shaped body 4 Drum 6 Electric motor 7 Inverter 8 Drive shaft 9 Mechanical brake device 10 Control system 11 Control device 13 Position acquisition device 14 Rotation speed acquisition device 15 Brake operation acquisition device

Claims (6)

In a control system including a control device connected to each of an inverter for controlling the drive of an electric motor and a mechanical brake device for mechanically braking the rotation of the drive shaft of the electric motor.
A drive parameter acquisition device for acquiring drive parameters related to the drive of the electric motor is provided.
The drive state of the electric motor controlled by the inverter by the control device includes a stopped state in which the rotation of the drive shaft is stopped without generating torque, and a power running drive state in which the drive shaft is rotationally driven to output a driving force. A braking drive state in which the drive shaft is rotationally driven to apply a braking force, and a pre-excitation state in which torque based on the drive parameter acquired by the drive parameter acquisition device is generated and the rotation of the drive shaft is stopped. , Consists of
A control system characterized in that, when the drive shaft is held in a stopped state, the control device controls the inverter to put the electric motor in the pre-excited state as a spare of the mechanical brake device. .. The control system according to claim 1, wherein the drive parameter comprises a position of the drive shaft, and the pre-excitation state is a state in which position control for holding the position of the drive shaft acquired by the drive parameter acquisition device is performed. .. The drive parameter consists of the rotation speed of the drive shaft in addition to the position of the drive shaft, and the control to bring the drive shaft into the pre-excited state is performed before the rotation speed of the drive shaft acquired by the drive parameter acquisition device becomes zero. The control system according to claim 2, which is configured as described above. The control system according to claim 1, further comprising a warning device that warns the driver that the electric motor is in the pre-excited state when the electric motor is in the pre-excited state as a spare of the mechanical brake device. .. A crane according to any one of claims 1 to 4, wherein the electric motor rotates and drives a drum around which a cord-like body is wound. The crane according to claim 5, wherein while the electric motor is in the pre-excited state, the control device controls to prohibit operations other than rotational driving of the drum.

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