JPH022791B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for a crane that is controlled by an inverter and is operated on the floor using a pendant switch.

[Conventional technology]

Conventionally, when an operator operates a crane on the floor using a pendant switch, he or she can only control the crane's rated speed in one step, and if the operator wants to operate the crane at a fine movement speed, he or she must perform an inching operation.

[Problem to be solved by the invention]

However, in the conventional system, when it was desired to operate at a fine movement speed, an inching operation was used, which required sophisticated techniques to operate the crane.

Furthermore, regardless of the size of the suspended load, it is not possible to obtain the optimum arbitrary speed required by the operation cycle of the crane.

In view of this point, an object of the present invention is to enable an operator to operate a crane on the floor at an optimum speed according to the operating cycle of the crane, thereby improving the efficiency of crane operation.

[Means to solve the problem]

In order to achieve the above object, the present invention allows the operator to set the desired steady speed at which the operator wishes to operate using an arbitrary speed setting device of a pendant switch, and controls the speed using an inverter so that the speed can be controlled over a wide range at will. .

〔Example〕

The present invention will be described below based on embodiments shown in the drawings.

The figure shows an example in which the present invention is applied to an overhead crane that is operated from the floor by a push button.
1. A traverse motor M2 and a traverse motor M3 are provided, and a speed control method using an inverter is applied to each motor. Inverter A2 further drives travel motor M3.
A travel inverter A3 is provided for each of the vehicles, and each inverter is operated based on a command from a control device. A pendant switch D for operating from the floor is connected to the control device C, and the pendant switch D has a push button switch for forward/reverse drive commands to each of the motors, that is, a hoisting motor M.
For example, the eastbound pushbutton 3, the westbound pushbutton 4, and the travel direction for the travel motor M3, for example, the south. The pendant switch D is equipped with a row push button 5 and a north row push button 6, and the pendant switch D is equipped with the inverters A1, A2,
A3 arbitrary speed setters, that is, a hoisting arbitrary speed setting device 7, a traversing arbitrary speed setting device 8, and a traveling arbitrary speed setting device 9 are attached.

Regenerative braking units B1, B2, and B3 each consisting of a resistor group are connected to each of the inverters to absorb the generated regenerative power.

Since the operation procedure using the inverter for each motor is the same, for example, the hoisting motor M
1 will be explained based on FIG. 2.

The hoisting motor M1 is a squirrel cage induction motor, and a variable voltage, variable frequency inverter A1 is connected between its primary side and a power source. The output frequency of the inverter is made variable by a signal from a pulse generator, for example, and a variable resistor 10 in the speed setting circuit is drawn out from take-out terminals H, O, and L, and is attached to a pendant switch D. constitutes the main part of the hoisting arbitrary speed setting device 7. Switch SW1 is a switch for forward rotation when the circuit is open and reverse rotation, that is, up and down when the circuit is closed, switch SW2
is a start/stop switch, and push buttons 1 and 2 of the pendant switch D are switched only when pressed.
It turns ON for SW2, and turns OFF when released, and each push button 1 and 2 corresponds to switch SW1.
They are related so that they can be turned ON and OFF together.

The regenerative braking unit B1 is mainly composed of a group of resistors, and the inverter is provided with a motor current detection means (not shown), so that when a regenerative current is generated, the generated current is applied to the regenerative braking unit.
In the figure, 20 is a thermal relay, 21 is a discharge resistor, and 22 is an emergency safety switch in case of a failure. Reference numeral 30 denotes a starting circuit, and when the starting push button 31 is pressed and closed, the solenoid of the electromagnetic switch 32 is energized, and the self-holding contact 34 is closed together with the circuit contact 33 for the inverter A1, thereby being self-held. 35
is a stop push button.

Next, to explain its function, when push button 1 for raising pendant switch D is pressed, switch SW
Switch SW1 is turned off, switch SW2 is turned on, and the hoisting motor M1 of the crane is driven. Prior to or after the operation of the push button 1, the hoisting arbitrary speed setting device 7 is set to a desired steady speed. An arbitrary steady speed of hoisting is set in the hoisting arbitrary speed setter 7 by a knob of a variable resistor 10. Variable resistor 1
0, the resistance value changes by increasing or decreasing the indication scale of the knob, the resistance value is applied to the pulse generator as a gate signal, and the frequency of the inverter is raised to a predetermined arbitrary frequency, that is, an arbitrary steady speed,
Perform winding.

Next, when lowering the lowering, in normal operation, the primary side current and voltage of the motor are detected, and based on this, the pulse width modulator is activated to control the frequency of the inverter, and the lowering is performed at a predetermined speed. When performing regenerative braking, regenerative energy generated in the motor is applied to the regenerative control unit B1 and is consumed by the resistor group. In this case, when regenerative braking is performed, the frequency of regenerative braking is low compared to the total operating time, so the power consumption is low, and there is no problem with the cooling means for the resistor group.

〔Effect of the invention〕

As described above, according to the present invention, by operating the arbitrary speed setter provided on the pendant switch, the operator can easily, steplessly, and arbitrarily set the optimum speed for the operating cycle. This has the advantage of improving the efficiency of crane operation.

[Brief explanation of drawings]

FIG. 1 is an overall block wiring diagram of a crane device to which the present invention is applied, and FIG. 2 is a block wiring diagram of a hoisting motor. A1...Hoisting inverter, A2...Traversing inverter, A3...Traveling inverter, B1, B2, B
3... Regenerative braking unit, D... Pendant switch, M1... Hoisting motor, M2... Traversing motor,
M3...Travel motor, 1-6...Push button switch, 7...
Hoisting arbitrary speed setter, 8...traverse arbitrary speed setter,
9... Traveling arbitrary speed setting device.

Claims (1)

[Claims] 1. In a crane whose drive source is a squirrel-cage induction motor whose speed is controlled by an inverter, the steady speed of hoisting, traversing, and traveling of the crane is arbitrarily set in advance by controlling the frequency generated by the inverter. The pendant switch is equipped with an arbitrary speed setting device with a variable resistor that generates a signal that can be used, and a push button switch for commanding forward and reverse rotation of each motor, allowing the operator to arbitrarily set the speed for the relevant operation cycle from the floor. A control device for an inverter crane operated by a floor pendant switch.