JPS61162493A - Method of controlling winding brake for crane, etc. - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling a hoisting brake for a crane or the like, which performs speed control using a vvvIP type inverter device.

[Conventional technology and its problems]

In general, in cranes and the like that use a V''V'VIF inverter device to control the speed, there is a predetermined period of time from when a start command is input to the inverter until, for example, an inverter output voltage higher than the load holding voltage is supplied to the hoisting motor. A timer is used to prevent the load from falling by delaying the time to release the hoisting brake.1 For this purpose, a timer is used.In the prior art, the normally open contact of the timer is the contact for the hoisting brake main circuit. When the contact is activated, the hoisting brake is open regardless of whether the inverter has started or not, and at this time, no current flows to the hoisting motor and no torque is generated. In this case, there is a problem of dropping the load.

[Means for solving problems]

The present invention has been made in view of the above points, and is based on the condition that a contact that operates by detecting the current and current of one motor is connected to the brake control layer circuit, and that current flows through the motor and generates torque. The purpose is to provide a control method that allows the brake to be fully operated without causing the brake to be released.
A motor current detection relay is provided on the 4'e@ path, and this contact is connected in series with each operation command contact for hoisting and lowering and the electromagnetic switch fill for brake operation, and after the motor current detection relay is activated, the hoisting It is designed to release the brake.

〔Example〕

FIG. 1 is a control circuit diagram showing only the winding and up-down operations used in this embodiment, and FIG. 2 is a circuit configuration diagram showing an overview of the device, both of which only show the winding and up-down operations.

In the figure, 11 is the power supply, MIN is the inverter, MH is the hoisting motor, BH is the hoisting brake, and power supply 11 is the breaker M.
OB is connected to the input terminals R, S, and T of the inverter via the contactor 52M, the hoisting motor MH is connected to the output terminals tr, v, and v of the inverter 12, and the hoisting brake BE is connected to the electromagnetic contactor. The hoisting motor MH is connected to the output terminals aE and vn of the inverter 2 through 75H.
.

It constitutes the hoisting brake BHO main circuit.

13 is a speed setting device for the hoisting motor MH, and two terminals of a variable resistor VR, which can be operated by a knob, are connected to terminals 1 and 2 of the inverter.

The DC voltage at this terminal 1.2r11J is divided by a variable resistor VR, and a frequency corresponding to this voltage is outputted from the inverter 2 to set the speed of the hoisting motor ME. Reference numeral 14 denotes a hoisting control unit consisting of operating switches PE53 and PE54 for driving the hoisting motor MH'1r forward and backward, and is connected to terminals 3, 4.5 of the inverter 1, and the hoisting motor MH'1r is used to hoist and lower the suspended load. That is, when the operating switch PBS3 is closed, the hoisting control unit 1 is operated in the normal direction, that is, when the operating switch PBS4 is closed, the hoisting is stopped.
4 is arranged so that it can be operated at the hand of the crane operator.

The control circuit for the hoisting motor MH is constituted by the following loop.

■Main power operation loop consisting of operation switch PE81 PBS2 and contactor 52 M coil connected ■Arm and winding consisting of the hoisting operation switch PBS3 and hoisting operation command relay fill 5H[X normally closed contact 5HD A hoisting operation loop composed of a lower operation switch PE54, a lowering operation command relay fill 5 HDr, and an arm made of a normally closed contact 6HTI, which are arranged in parallel.

In addition, if either the upper or lower side of this loop is activated,
The other is configured so that it does not operate. Normally open contact 37D of the current relay that operates by detecting the motor current, and control relay fill 75H for opening and closing the brake.
The first arm consisting of X and the relay coil 75HX
A brake opening/closing loop composed of a normally open contact 75HX operated by a brake opening/closing loop and a second arm comprising a brake opening/closing electromagnetic coil 75H.

■Auxiliary relay 37EX 37HY with hoisting current shortage detection loop that detects motor current and issues a signal to open brake 75) I when this current falls below a set value
The normally open contact 75HX of the relay, the hoisting operation command relay 36UH%, and the lowering operation command relay 6DH are throttled as shown in FIG.

[Effect]

The operation of the above configuration will be explained with reference to the time chart shown in FIG.

■First, as a hoisting operation preparation operation, the main power operation switch P
When B81 is pressed, the magnetic contactor coil 52M is energized and 1
When the normally open contact 52M is closed and the self-held O When activated, the inverter 12 starts outputting at low voltage and low frequency, and current begins to flow through the hoisting motor MH. In this state, the motor MH is locked by the brake BE. At the same time, when the current exceeds the set value, the normally open contact 37D of the current relay closes, and the relay coil 75H for brake opening/closing control is energized, and the normally open contact 751
1X, thereby energizing the brake electromagnetic contactor filter 75H and starting the opening operation of the brake BH.

(2) At time t2, the opening operation of the brake Bl is completed, and the hoisting motor MH is driven at a voltage and frequency according to the partial voltage of the variable resistor VR of the speed setting device 3.

(2) The case where the output voltage or current of the inverter 2 becomes abnormal and the suspended load cannot be held will be explained.

During normal hoisting, brake opening/closing control relay 75HX
Normally open contact 75HXN Normally open contact 5t
TH is closed, the auxiliary relay coil 37HX is energized, and the normally open contact 37HX is closed.

Even during operation, if the motor current is insufficient, the contacts of the current detection relay 37D open and close, and the normally open contacts 75HX, 75H, 371iX open, locking the brake and stopping the motor. The auxiliary relay 37 is stopped and the normally open contact of the auxiliary relay 37HY is closed.
Hz can be activated and a failure alarm can be issued.

Although current detection has been described above, a voltage detection method may also be used.

In this state, when an abnormality occurs as described above, when the supply current to the motor is cut off, the normally open contact 37D opens by the current detection relay, and immediately the brake control relay 75HX
The normally open contact opens, the brake operating electromagnetic contactor 75H opens, and the brake immediately closes to prevent the suspended load from falling.

■In the case of a stop, if the operation switch command is turned off at time t3 in the reverse order to the above (time tS), the output voltage and frequency of the inverter will rapidly decrease, and at time t4 when the frequency has reached a constant level. The brake closes and the hoisting motor MH stops. After that, the output of the inverter becomes zero.

Although the above explanation has been given for the case of winding up, the same applies to the case of lowering, so the explanation thereof will be omitted. In addition to the above, the present invention can also be applied to a hoisting machine using an inverter equipped with a motor and a brake, even if there is an auxiliary hoisting device in the navigating lane.

〔Effect of the invention〕

According to the present invention, the brake is released after detecting the torque generated by the motor when operating a crane or the like using an inverter by current detection, so a simple device can prevent suspended loads from falling and ensure safety. It can be made to work.

[Brief explanation of the drawing]

FIG. 1 is a control circuit diagram of the present invention, FIG. 2 is a circuit configuration diagram, and FIG. 3 is a time chart diagram. MH is the hoisting motor, BH is the brake, 11 is the power supply,
12 is an inverter, 13 is a hoisting motor speed setting device,
14 is a hoisting control unit, and 37Dl is a normally open contact.

Claims (1)

[Claims] In cranes and the like that are equipped with a motor and a brake and whose speed is controlled by an inverter, a normally open contact that is activated by detecting the motor current is provided in the hoisting brake operation switch circuit, and the brake is activated by closing this normally open contact. is released and drives the hoisting of the crane, and when the inverter output is lost due to a malfunction or the like and current is not supplied to the motor and the suspended load cannot be held, the brake is restrained. A hoisting brake control method for a crane, etc., characterized by the following: