JP2000355405A - Brake controller for stacker crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake controller for a stacker crane preventing a collapse of cargo on a carriage by preventing sudden braking of a motor when power is cut off and not requiring a safety factor of chains and ropes more than necessary. SOLUTION: A contact X1 closed by an inoperative state of an electromagnetic contactor CT when power is cut off is serially connected to a regenerative resistance R. An electric current generated by a servomotor M working as a generator is fed to the regenerative resistance R via the contact X1 and a brake BR is maintained in an inoperative state by a voltage generated at the regenerative resistance R. Also, an electric current of the regenerative resistance R is fed to an armature of the servomotor M for applying braking to the motor and smoothly stopping a carriage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stacker crane used in an automatic warehouse or the like, and more particularly to control of a brake when power is cut off.

[0002]

2. Description of the Related Art FIG. 2 is a schematic perspective view showing an example of a stacker crane. In the figure, the stacker crane 1 is 1
A pair of masts 2 is provided, and a carriage 3 for carrying a load is provided along the masts 2 so as to be able to move up and down in the direction of arrow P. The carriage 3 is equipped with a fork 4 for performing a cargo handling operation.

[0005] Reference numerals 5 and 6 denote sensors provided on the side of the carriage 3, which are constituted by, for example, reflection type photoelectric sensors. Reference numeral 7 denotes a forcible deceleration dog provided on the upper part of the mast 2, which is formed of an elongated plate-like member extending in the vertical direction of the carriage 3. Reference numeral 8 denotes a forced deceleration dog provided at a lower portion of the mast 2 and, like the dog 7, is constituted by an elongated plate-like member extending in the elevating direction of the carriage 3.

[0004] Reference numeral 9 denotes a lifting drive device for raising and lowering the carriage 3, which is composed of a servomotor described later. Reference numeral 10 denotes a traveling rail on which the traveling vehicle 15 of the crane 1 travels in the direction of arrow Q, and reference numeral 11 denotes a traveling drive device provided at an end of the traveling vehicle 15.

[0005] A guide rail 12 is provided above the crane 1, and the guide roller 13 is guided by the guide rail 12 when the traveling vehicle 15 travels on the traveling rail 10. An upper frame 14 supports the guide roller 13 and is connected to the mast 2. 16 is mounted on the crane 1 and the carriage 3
Is a controller installed on the floor and controlling the entire warehouse.

In the crane 1 having the above configuration,
The carriage 3 is moved at a predetermined speed between an upper end position and a lower end position by a chain or a rope (not shown) driven by the lifting drive device 9. When the carriage 3 moves up and the sensor 5 detects the dog 7, the carriage 3 is decelerated and stops at the upper end position. When the carriage 3 descends and the sensor 6 detects the dog 8, the carriage 3 is similarly decelerated and stopped at the lower end position.

[0007]

In the above-described stacker crane 1, when the power is cut off due to a power failure or the like when the carriage 3 is moved up and down, the lifting drive 9 is operated.
Is suddenly braked, and the carriage 3 stops. That is, an electromagnetic brake (not shown) such as a disc brake is connected to the motor of the lifting / lowering drive device 9, and this electromagnetic brake is normally driven by a solenoid or the like and is in an open state. In an emergency, the motor is activated and the motor is braked. For this reason, when the power supply is cut off when the carriage 3 moves up and down, the electromagnetic brake is activated and the motor is suddenly braked.

However, when the motor is suddenly braked in this way, the carriage collapses due to a sudden shock caused by the sudden stop of the carriage 3, and if the strength of the chain or rope for raising and lowering the carriage 3 is weak, these may be cut. This may lead to a serious accident that the carriage 3 falls. For this reason, there has been a problem that the safety factor of the chain or the rope must be made higher than necessary, and it becomes expensive.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and prevents a sudden brake from being applied to a motor when power is cut off, thereby preventing collapse of a load and a safety factor of a chain or a rope. It is an object of the present invention to provide a brake control device for a stacker crane that does not require more than necessary.

[0010]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention uses a power generated by a motor as a generator when a power supply is cut off to maintain a brake in a non-operation state. Things. By doing this,
Since the brake is not activated immediately after the power is cut off, it is possible to prevent the carriage from being suddenly subjected to a sudden stop shock due to the sudden braking of the motor.

Further, the present invention utilizes a regenerative resistor conventionally provided for absorbing the regenerative energy of the motor, and when the power is turned off, the generated current of the motor flows from the regenerative resistor to the armature of the motor, so that the braking torque is applied to the motor. Is generated.

With this arrangement, when the moving speed of the carriage immediately before the power is turned off is high, the induced voltage also increases due to the high rotational speed of the motor, and a large current flows through the regenerative resistor. Big braking torque acts on the motor by flowing to the amateur. In addition, when the moving speed of the carriage is low, the induced voltage is also low because the rotation speed of the motor is small, a small current flows through the regenerative resistor, and a small braking torque acts on the motor. In this way, as a result of the automatic deceleration corresponding to the speed of the carriage, the carriage stops smoothly.

When the motor is to be braked using the regenerative resistor as described above, a braking electromagnetic contactor driven by turning on the power is provided, and the normally closed contact of the electromagnetic contactor is connected in series with the regenerative resistor. It is preferable that the normally closed contact be closed when the power supply is shut off, so that the generated current of the motor flows to the armature of the motor through the regenerative resistor.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings. FIG. 1 is a circuit diagram showing an electrical configuration of a brake control device according to the present invention. In the figure, E is a three-phase AC power supply, SW is a power switch, and CV is an AC / DC composed of _six diodes D _{1 to} D _6.
Converter, CT electromagnetic contactor for braking, X ₁ is normally closed contact of the electromagnetic contactor CT, X ₂ is an electromagnetic contactor with normally open contacts (not shown), normally closed contact X ₁ for regeneration normally open It is connected in parallel to the contact X _2. R regenerative resistor connected to the normally closed contact _{X 1} series, IV are six diodes _D 7 _{to D 12} and six transistors _Tr 1 _{~Tr 6} DC / AC inverter including the, M is 2 The servomotor BR of the lifting drive device 9 is a brake for braking the servomotor M.

The power switch SW is composed of three switches connected to each phase of the three-phase AC power supply E, and these switches are turned on and off in conjunction with each other. AC / DC converter CV
This is a full-wave rectifier circuit that converts three-phase AC to DC. Electromagnetic contactor CT is connected to the output side of the AC / DC converter CV, the movable element (not shown) is driven by a current flowing through the coil, the normally closed contact X ₁ in the open state. Normally open contact X ₂
Is closed by the operation of the regenerative electromagnetic contactor, and a regenerative current flows through the regenerative resistor R. Incidentally, the normally open contact _{X 2} and regenerative resistor R
Is a conventional feature.

The DC / AC inverter IV controls the rotation of the servo motor M by ON / OFF control of each of the transistors Tr _{1 to} Tr ₆ . Each transistor Tr ₁ -T
control signal from a control circuit to the base (not shown) of the r ₆ is given, the transistor is ON on the basis of this signal, OF
F. Brake BR is an electromagnetic brake, is connected in parallel X ₁ and normally closed contact and a series circuit of the regenerative resistor R.

Next, the operation will be described. When the power switch SW is turned on, power is supplied to the servomotor M from the three-phase AC power supply E via the AC / DC converter CV and the DC / AC inverter IV, and the servomotor M rotates. As a result, the carriage 3 (FIG. 2) moves.
At this time, since power is also supplied to the brake BR, the brake BR is in a non-operating state (open state), and the brake on the servomotor M is not applied.

Further, normal is electromagnetic contactor CT is operated by turning on the power, the normally closed contact X ₁ is in the open state. On the other hand, the normally open contact X ₂ is regenerative electromagnetic contactor is closed by operating a signal from the control circuit.
When the normally open contact X ₂ is closed, the current servo motor M is generated as a generator flows to the regenerative resistor R, the braking torque acts on the servo motor M.

That is, when the carriage 3 carries a load upward, the servo motor M functions as an original motor and raises the carriage 3 by rotation. However, when the carriage 3 carries the load downward, the No. 3 descends by its own weight, so that there is no need to energize the servo motor M. Therefore, the servo motor M is in a non-driving state. However, since the carriage 3 is connected to the rotation shaft of the servo motor M by a chain or a rope, when the carriage 3 descends by its own weight, the servo motor M rotates. As a result, the servo motor M generates an induced voltage. That is, the servo motor M functions as a generator.

At this time, if there is no regenerative resistor R, the path of the current generated by the servo motor M is not formed, so that the servo motor M does not work as a generator, and the carriage 3 falls freely because no braking torque is applied. but generated current of the DC / flow from AC inverter IV to the regenerative resistor R via the contact X _2, further motor braking torque is generated by flowing the armature of the servomotor M motor, so braking is applied.

The above is the operation in the normal state.
When the power is cut off due to a power failure or the like, the servomotor M loses the driving force because the current is not supplied, and rotates as the carriage 3 descends to act as a generator. That is, the contact X ₂ is in the open state by the power-off, the contact X ₁ for electromagnetic contactor CT is inoperative is in the closed state, the series circuit of the contacts X ₁ and the regenerative resistor R is formed,
The current generated by the power generation of the servo motor M is DC / AC
Flowing through the regenerative resistor R from the inverter IV via the contact _{X 1.}

As a result, a voltage is generated at both ends of the regenerative resistor R, and this voltage is supplied to the brake BR as power. For this reason, the brake BR maintains the non-operating state (open state) by this voltage, and does not operate immediately even if the power is cut off. Therefore, the servo motor M
The sudden braking of the carriage 3 can prevent the collapse of the load due to the sudden stop shock of the carriage 3.

On the other hand, when the current of the regenerative resistor R flows from the DC / AC inverter IV to the armature of the servomotor M, a braking torque is generated in the servomotor M, and the servomotor M is decelerated by receiving the braking torque. You. When the motor is decelerated, the generated current is reduced, so that the braking torque is reduced and the servo motor M is further decelerated,
By repeating this, the servo motor M is gradually decelerated.

If the moving speed of the carriage 3 is high immediately before the power is turned off, the electric power generated by the servomotor M is large, so that the current flowing from the regenerative resistor R to the servomotor M is also large, and a large braking torque is generated. Works.
When the moving speed of the carriage 3 is low, the electric power generated by the servo motor M is small, so that the current flowing from the regenerative resistor R to the servo motor M is also small, and a small braking torque is applied. In this manner, the deceleration according to the speed of the carriage 3 is automatically performed, so that it is not necessary to perform special deceleration control.

When the servo motor M decelerates to a certain extent, the voltage of the regenerative resistor R decreases and the brake BR operates. At this time, the speed of the carriage 3 is sufficiently low, so that a sudden shock due to the stoppage occurs. Does not occur. Thus, the carriage 3 stops smoothly after deceleration.

In the above embodiment, a servo motor is used as a motor. However, any motor other than a servo motor may be used as long as it has a permanent magnet.

[0027]

According to the present invention, it is possible to avoid sudden braking of the motor when the power is turned off, so that the carriage can be prevented from being collapsed due to a sudden shock, and the chain and the rope can be made stronger than necessary. Without doing so, safety can be ensured.

Further, by utilizing the regenerative resistor, the speed is automatically reduced in accordance with the speed of the carriage, so that there is an advantage that the control is not required and the configuration is simplified.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an electrical configuration of a brake control device according to the present invention.

FIG. 2 is a schematic perspective view showing an example of a stacker crane.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Stacker crane 3 Carriage 9 Elevating drive E E 3 phase alternating current power supply SW Power switch CV AC / DC converter CT Electromagnetic contactor X ₁ Normally closed contact X ₂ Normally opened contact IV DC / AC inverter M Servo motor BR Brake

Claims (3)

[Claims] 1. A stacker crane having a carriage for carrying a load, a motor for moving the carriage, and a brake for braking the motor, the brake is operated by electric power generated by the motor when power is cut off. A brake control device for a stacker crane, wherein the brake control device is maintained in an inoperative state. 2. A regenerative resistor through which a current generated by a motor flows when power is cut off. A voltage generated at the regenerative resistor maintains the brake in a non-operating state, and a current of the regenerative resistor flows through an armature of the motor to the motor. The brake control device for a stacker crane according to claim 1, wherein a braking torque is generated. 3. A braking electromagnetic contactor driven by turning on a power supply, a normally closed contact of the electromagnetic contactor is connected in series with a regenerative resistor, and the normally closed contact is closed when power is turned off. 3. The brake control device for a stacker crane according to claim 2, wherein the generated current of the motor flows through the regenerative resistor to the armature of the motor.