KR200338991Y1 - Apparatus for preventing over-weight of hoist - Google Patents

Abstract

Start the overload protection device of hoist. The overload protection device of the present invention monitors a current value change through an up switch that generates a hoist operation command signal of a hoist motor, a down switch that generates a hoist operation command signal, and at least one current transformer coupled to the hoist motor. Means, an alarm means for alarming an overload condition at the time of overload detection, a display means for displaying a load, and a switching drive for stopping the ascending operation of the hoisting motor at the time of overload detection. Further, in the up operation mode by the up switch, the state of the monitoring signal provided from the monitoring means is determined to detect an overload condition, and the detected load state is displayed in comparison with the rated load. The control unit generates an alarm and includes a control means for displaying only the detected load state without performing an alarm generation even if an overload is detected in the down operation mode by the down switch.

Description

Hoist overload protection device {Apparatus for preventing over-weight of hoist}

The present invention relates to a hoist overload protection device, and more particularly, to an overload protection device that can prevent the generation of false alarms due to false detection.

In general, a hoist is a device that lifts or lifts a heavy object using a hoisting motor and moves it to a desired position. Unlike hoists, cranes can move left and right as well as feed. Therefore, when the hoist or crane does not bear the load due to overload in the process of lifting and moving the object and drops the object on the way, a very dangerous situation may develop and in severe cases, a person may be injured.

Therefore, in order to prevent such a problem, the hoist adopts a safety device that monitors an overload condition when lifting an object and stops operation with an alarm in an overload condition.

There are three types of hoists:

First, the standard type is a hoist driven by one motor and operates L phase and H phase simultaneously. The Cliff type uses L phase as a hoist using two low speed motors and two high speed motors. Used for high speed motors. In addition, the pole change type (motor pole change type) is a hoist whose speed is variable by changing the number of poles of a motor using one motor. L phase is used at low speed and H phase is used at high speed. Requires a change.

Due to these various types, if the overcurrent protection device is to be configured as the current detection method, only one set of the overload protection device is required for the standard type, but the cliff type and the pole change type each have one overload protection at low and high speeds. There was a problem that two sets are required because the device must be installed.

Applicant has been registered with the patent registration No. 267456 regarding the overload protection device in order to improve this problem.

Typically, the electrical overload protection device is to detect the current of the motor to detect the overload condition. Therefore, when overload is detected, more current flows as compared with the normal case. Typically, more current flows in the motor when hoisting (raising) when lowering (lowering).

However, in small hoists with a rated load of less than 1 ton, in particular chain hoists, more current flows than when normal. Therefore, in the case of ascending, the overload condition is detected by the overcurrent during the fall, but the malfunction occurs that the alarm sounds even though it is detected under the rated load and operated normally.

Therefore, it is often found that drivers manipulate and use an overload detection criterion to a value exceeding an overload threshold in order to prevent false alarms from occurring. In this case, when an operator uses a hoist in violation of the safety regulations in the field, an accident risk such as a worker is exposed to danger due to failure to detect an overload condition in a timely manner follows.

An object of the present invention is to provide a hoist overload prevention device that can prevent the false alarm by displaying only the load in the descent (lowering) operation mode to block the alarm in order to solve the problems of the prior art.

1 is a view showing the circuit configuration of the hoist overload prevention device according to the present invention.

Figure 2 is a flow chart for explaining the operation of the overload protection device according to the present invention.

3 is a timing chart for explaining the operation of the overload protection device according to the present invention

Figure 4 is a timing chart for explaining the operation of the overload protection device during the descent operation according to the present invention.

<Description of the code | symbol about the principal part of drawing>

10: first supervisory circuit 12: second supervisory circuit

14 alarm circuit 16 switching driver

18: control unit 20: memory

22: display unit 24: input unit

26: delay unit 28: power supply unit

UP1, 2: Up switch DW1, 2: Down switch

M1, M2: Hoist motor DWS1, DWS2: Fall detection circuit

The apparatus of the present invention to achieve the above object of the present invention

An up switch for generating a hoisting operation command signal of the hoisting motor;

A down switch for generating a lowering operation command signal of the hoisting motor;

Falling detection means for generating a falling detection signal during the turn-on operation of the down switch;

Monitoring means for monitoring a current value change through at least one current transformer coupled to the hoisting motor;

Alarm means for alarming an overload condition upon overload detection;

Display means for displaying a load;

A switching driver for stopping the lifting operation of the hoisting motor when an overload is detected; And

In the rising operation mode by the up switch, the state of the monitoring signal provided from the monitoring means is determined to detect an overload condition, and the detected load state is displayed on the display means in comparison with the rated load. Means and control the switching drive to generate an alarm,

And a control means for stopping the operation of the alarm means and displaying only the detected load state on the display means so as not to perform an alarm generation even if an overload is detected when the falling detection signal is input from the falling down means. do.

Hereinafter, with reference to the accompanying drawings, it will be described in detail the present invention through an embodiment of the present invention.

Figure 1 shows a circuit configuration of a preferred embodiment of the hoist overload protection device according to the present invention. 1 is an example in which the overload protection device of the present invention is applied to a wire clip hoist hoist (WIRE CREEP HOIST CRANE).

The cliff hoist includes two hoisting motors, specifically a high speed hoisting motor M1 and a low speed creep hoisting motor M2. The hoisting motor M1 has three-phase AC inputs R, S, and T connected to the motor inputs U, V, and W respectively through an up switch UP1, and a three-phase AC input R, S through a down switch DW1. , T are connected to motor inputs W, V, and U, respectively. The three-phase AC inputs R, S, and T are respectively connected to the motor inputs U, V, and W through the up switch UP2, and the three-phase AC inputs R, through the down switch DW2. S and T are connected to motor inputs W, V and U, respectively.

In the present invention, each of the down switches DW1 and DW2 is connected to the corresponding falling detection circuits DWS1 and DWS2, respectively.

The first current transformer CT1 is coupled to the V-phase input line of the hoisting motor M1, and the second current transformer CT1 is coupled to the V-phase input line of the cliff hoisting motor M2. Each of the motors M1 and M2 is configured to be braked by DC magnetic brakes MB1 and MB2 connected to S and T phases via the down switches DW1 and DW2, respectively.

The overload protection device of the present invention, which is installed in the cliff hoist crane configured as described above, in the present invention, each of the down switches DW1 and DW2 is connected to the corresponding falling detection circuits DWS1 and DWS2, respectively. The first falling detection signal is generated by inputting the voltages of both ends of the relay which is turned on by the turning-on operation of the falling detection circuit DWS1.

The falling detection circuit DWS1 constants the TNR for absorbing the surge voltage across the relay, the diode D1 for half-wave rectifying the relay driving signal, the resistors R1 and R2 for limiting the current, and the half-wave rectified voltage signal. Zener diode (ZD1) for maintaining the same, a photocoupler (PC) for transmitting the signal of the hot circuit portion to the cold circuit portion, and a capacitor (C1) for removing high frequency noise of the output signal of the photocoupler. Accordingly, the falling detection circuit DWS1 converts an AC signal provided to the relay through the down switch into a DC signal by the diode D1 and the zener diode ZD1 and detects the falling DC signal through the photo coupler PC. Output as a signal.

The falling detection circuit DWS2 generates a second falling detection signal by inputting voltages of both ends of the relay that are turned on by the turn-on operation of the drop switch DW2 in the same configuration as the DWS1.

A first value of holding the peak value of the first current detected through the first current transformer CT1 coupled to the hoisting motor M1, and rapidly discharging the held peak value when the detected value of the first current is reduced to a predetermined value or less; Holds the peak value of the second current detected through the supervisor circuit 10 and the second current transformer CT2 coupled to the cliff hoisting motor M2, and if the detected value of the second current decreases below a predetermined value, hold. And a second supervisory circuit 12 for rapidly discharging the peak value. The apparatus also includes an alarm circuit 14 for alarming an overload condition upon overload detection and a switching driver 16 for stopping the lift operation of the hoist motors M1 and M2 upon overload detection.

In addition, the device inputs the falling detection signals provided from the falling detection circuits DWS1 and DWS2 and through the first or second monitoring circuits 10 and 12 to detect an overload of the hoisting motors M1 and M2. Counting the detected overload operation time, and if it detects the excess state of the set overload operation time is determined as the overload detection, and control the alarm circuit 14 and the switching drive unit 16 to generate a warning to raise the hoist motor (M1, M2) ) Stop operation, the counting down operation time of the hoist motor (M1, M2) through the first or second monitoring circuit (10, 12), the counted down operation time is equal to the set recovery time In this case, the alarm circuit 14 and the switching driver 16 are restored to their normal state, and there is no overload detection at the time of rising, and when the overload is detected in the down operation mode, the alarm circuit 14 is disabled to block the alarm occurrence. Ha Only the load state include a control unit 18 for displaying on the display unit.

The controller 18 is composed of a microprocessor and analog-to-digital converts the monitoring signals provided through the first and second monitoring circuits 10 and 12 to process data. The start time, overload operation time, recovery time and the like used in the control unit 18 are stored in a nonvolatile memory such as a memory 20 such as an EEPROM. These setting times are set by the user via the input unit 22 and the 7 segment LED display 24. The input unit 22 includes a storage key, a selection key, an up key, a down key, a return key, an L test key, an H test key, and the like.

In addition, the apparatus includes a delay unit 26 for blocking a control signal applied to the switching driver 16 during the predetermined time period for a predetermined time in order to prevent malfunction due to the initial starting current. Reference numeral 28 is a power supply for providing a first operating voltage VCC and a second operating voltage VDD to the device. The prevention device configured as described above is installed and sealed in the case so that the set time and the set current cannot be easily changed.

2 shows a control program of the overload protection device according to the present invention, and FIGS. 3 and 4 show operation timing charts.

First, the control unit 18 checks whether the power is turned on (100), and when the power is turned on, checks whether the rising operation starts (102). If it is not the rising operation in step 102 performs a set mode routine (114).

In the setting mode routine, the keys provided in the input unit 24 are operated to view the data displayed on the display unit 22, and the start time, that is, the start time t1, the overload operation time, that is, the impact time t2, and the return time t3. Etc.) and L phase operating current and H phase operating current. The operating current is the overload upper limit. The setting can be set precisely in units of 100mA in the range of 99.9A or less and in units of 1A in the range of 99.9 ~ 1000A.

Each time of the time setting is as follows.

1. Start time-Start time: It is the time to delay the overload detection at the initial start to prevent the overload malfunction caused by the starting current of the motor.

2. Shock time-Overload operation time: It is time to perform overload prevention operation by judging as overload if overcurrent continuously flows over the set time.

3. Auto return time: It is the time set for auto return after overload operation. If hoist down button is pressed, hoist motor operates in the opposite direction than when hoisting motor and current flows. Therefore, since the current flows only in the operating time, it is a time for automatically returning when the setting time becomes zero by subtracting the current flowing time from the setting time.

If the start of the rising in step 102, the values of the flag values F1 and F2 are treated as 0 (106), the start time t1 of FIG. 3 is counted (108) and overload detection is started at the same time (116). In step 108, it is checked whether the count of the start time is completed (110). If it is completed, the flag value F1 is set to 1 and the flag value F2 is set to 1 (114).

If the value of F2 is not set to 1, since there is no overload detection, an overload detection step 116 is performed. If the state is not overloaded, normal operation is performed (118). If the state is overloaded, the impact time t2 of FIG. 3 starts counting (120). If it is determined that the impact time has elapsed (122), and if the shock time has elapsed, that is, it is determined that the overcurrent state has been maintained for a predetermined time or more, the value of F2 is set to 1 (124), and the value of F1 is set to 1 It is checked whether or not (126).

If the value of F1 is not set to 1 in step 126, since the initial start time has not yet elapsed, step 110 is performed to wait for the initial start time to elapse.

If the initial starting time has elapsed in step 114 and an overload condition is detected, it is checked whether the falling detection signal is input (114-1). When the initial start time, that is, the start time, passes through the steps 112 and 114 without the falling detection signal being input in step 114-1, the driving control of the hoisting motor is stopped by controlling the switching driver 16, that is, the up switch. Turn off (128). In addition, the alarm circuit 14 is controlled to drive a buzzer to intermittently generate an alarm sound, and to flash an alarm lamp to display an alarm state.

When the driver recognizes such an alarm state and inputs a descending command to drive the hoisting motor down (130), counting the down driving time and down counting the return time t3 of FIG. 3 set by the counted down driving time ( 132). When the return time is down counted to the zero state (134), the switching driver 16 is returned to the normal state and the alarm of the alarm circuit 14 is stopped (136).

If the falling detection signal is input in step 114-1, the currently detected overload detection state is recognized as an erroneous detection generated by the hoisting motor itself when falling and is blocked to prevent an alarm (114-2). The display unit is displayed as it is (114-3), and the normal normal mode of step 118 is performed.

Therefore, according to the present invention, it is possible to prevent the occurrence of a false detection such as an alarm occurrence due to the overload is detected during the normal operation during the driving operation up and down.

Therefore, if an overload condition is detected from the initial startup, the start time is terminated and an overload prevention operation is performed. After the initial startup time has elapsed, an overload prevention operation is performed immediately after the impact time has elapsed. Therefore, the impact time is preferably set to a time equal to or smaller than the startup time.

In the above-described embodiment, the application example of the cliff hoist has been described, but the overload prevention device of the present invention can be applied to a hoist composed of a standard hoist or a pole change motor using one winding motor. In the standard type, the first and second sensing circuits simultaneously operate the L and H phases, while the pole change type uses the L phase at a low speed and the H phase at a high speed.

As described above, according to the present invention, the operation can be prevented from being stopped due to a malfunction by preventing a malfunction in which the overload is detected during the fall while operating normally during the rise, thereby improving the work efficiency of the worker.

It also prevents the operator from manipulating the hoist in violation of safety regulations, thus reducing the risk of an accident.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art various modifications and variations of the present invention without departing from the spirit and scope of the present invention described in the claims below I can understand that you can.

Claims (1)

An up switch for generating a hoisting operation command signal of the hoisting motor; A down switch for generating a lowering operation command signal of the hoisting motor; Falling detection means for generating a falling detection signal during the turn-on operation of the down switch; Monitoring means for monitoring a current value change through at least one current transformer coupled to the hoisting motor; Alarm means for alarming an overload condition upon overload detection; Display means for displaying a load; A switching driver for stopping the lifting operation of the hoisting motor when an overload is detected; In the rising operation mode by the up switch, the state of the monitoring signal provided from the monitoring means is determined to detect an overload condition, and the detected load state is displayed on the display means in comparison with the rated load. Means and control the switching drive to generate an alarm, And a control means for stopping the operation of the alarm means and displaying only the detected load state on the display means so as not to perform an alarm operation even if an overload is detected when the fall detection signal is input from the fall detection means. Hoist overload protector.