SU1597339A1 - Apparatus for preventing overload of hoisting machine - Google Patents

Abstract

FIELD OF THE INVENTION The invention relates to a lifting and transport machinery, namely, devices for preventing overloading of load-lifting machines. The purpose of the invention is to increase safety. Load sensor 1 is associated with comparators 2-4. The triggers 6, 10 are connected to the comparators 2, 3. The trigger 6 through the one-shot 7, block AND 9 and block OR 8 is connected to the execution unit 11. Comparators 2-4 are tuned to the appropriate load levels. When the machine is started up under the control of Comparators 2-4, it is accelerated to achieve a predetermined load, after which the machine is braked and starts up again, depending on the signal of the comparator 4. 2 Il.

Description

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The invention relates to hoisting and transport machinery, namely, k devices for preventing overloading of hoisting machines, mainly bridge type cranes.

The purpose of the invention is to increase safety.

1 shows a functional diagram of the device; Fig. 2 shows the curve for changing the forces in a machine as a function of time when it is loaded.

The device for preventing the overloading of the lifting machine comprises a load sensor 1 connected to one of the inputs of the comparators 2-k, the other inputs of which are connected to the outputs of the setpoint generator of 5 load levels. Trigger 6 is connected - :) with inputs to outputs of Comparators 2 and 3, and its output is connected to the input of a single vibrator 7, the direct and inverse outputs of which are connected to one input of the blocks OR 8 and AND 9. The other input of the block AND 9 is connected to the output of the comparator . The inputs of the trigger 10 are connected to the output of the block AND 9 and to the output of the comparator 3, and the output to another input of the block OR 8, the output of which is connected through the control unit 11 to the control circuit of the lifting machine.

Sensor 1 load is made in the form of load unit. The trigger 6 may be connected to the input of the one-shot 7 via a differentiating chain (not shown). Unit 5 includes potentiometers of the reference voltages of the respective levels. The Executive unit 11 is designed as an amplifier.

The device works as follows.

Three levels of loads 12-1 are controlled, which correspond to the reference voltages of the comparators 2, k, 3, respectively.

The load level 12 is used to control the drive of the lifting mechanism in a controlled manner. Its value is lower than the nominal load and is selected experimentally for a particular lifting machine by changing the reference voltage of the commander 2 so that the signal from the sensor 1 when lifting the nominal load does not exceed level 15. The second load level 13 is used to prevent overloads when lifting freights above nominal

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or to limit the dynamic loads during operation of a machine with a nominal load or close to it, which can occur during a sudden lifting of a load with a pickup. This level is set by the comparator k. The third level And is used to bring the device to its original state and corresponds to the minimum load on the lifting mechanism, for example, on the weight of the load gripping device. The level is set by changing the reference signal of the comparator 3.

In the initial state (load is omitted) the signal from sensor 1 is below the level I l (Fig. 2), the triggers 6 and 10 are set to the inverse signal of the comparator 3, in which their output signal is equal to logic zero, the lift drive is unlocked. When the mechanism is turned on, as the cables are tensioned, the value of the signal from sensor 1 begins to grow. When its value exceeds the level 1, the comparator 3 will work and its output will be low, which unlocks the information inputs of triggers 6 and 10. A further increase in the signal to level 12 will trigger the comparator 2, which triggers three | Ger 6, and he, in turn, starts the one-shot 9 through a differentiating chain. Then through the block OR 8 and block 11, the drive of the lifting mechanism is switched off for a time determined by the duration of the pulse of the single-vibrator 7. For the duration of the pulse, applying the inverse signal of the one-vibrator 7 to the input of the block AND 9, the trigger 10 is blocked in case The time signal from sensor 1 reaches the AND level and the comparator k will work.

At the end of the time delay, the signal from sensor 1 can be either lower or higher than level 13. If the signal is lower than level 13, the one-vibrator signal 7 through the block OR 8 activates (unlocks) the drive and the started lifting continues. Repeated disconnection of the device will occur if the signal of sensor 1 is exceeded by level 13. As a result, the further operation of the mechanism is allowed only for descent.

To bring the device back to its original state, it is necessary to reduce by

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Claims (1)

Claim A device to prevent overloading of hoisting machines, one with a chain hoisting machine control, characterized in that, in order to increase safety, it is provided with triggers WMOs ⁵ rows one of which is connected to the outputs of the two comparators monostable having an input connected to the output of the first flip-flop, block And 10 inputs of which are connected to the inverted output of the one-shot and to the output of the third comparator, and the output is predominantly of a bridge-type crane containing a load sensor connected to one of the inputs of at least three comparators, the other inputs of which are connected to the outputs of one input of the second trigger, the other input which is connected to the output of the second comparator’s house, and the unit OR, the inputs of which are connected to the outputs of the one-shot and the second τρπι - master load levels, and a block is used, the output of which is from the heur, and the output is connected to the input of the executive unit.